Chemokines and chemokine receptors in metabolic dysfunction-associated steatohepatitis: pathogenic mechanisms and clinical implications

Abstract

Metabolic dysfunction-associated steatohepatitis (MASH), an advanced stage of metabolic dysfunction-associated steatotic liver disease (MASLD), is characterized by persistent hepatic inflammation and fibrosis and frequently progresses to cirrhosis or hepatocellular carcinoma. Chemokines and their receptors, which drive disease progression and complications by orchestrating immune cell recruitment, inflammatory responses, and fibrotic processes, are central to the pathophysiology of MASH. Emerging evidence also underscores their functions as active metabolic integrators, reciprocally linking systemic insulin resistance to hepatic inflammation. This review aims to elucidate the pathogenic contributions of key chemokines such as chemokine (C–C motif) ligand (CCL)2, CCL5, CCL20, and chemokine (C–X–C motif) ligand (CXCL)10 in MASH by assessing their dual potential as therapeutic targets and non-invasive biomarkers for early detection. We also survey the current landscape of chemokine-directed therapies to critically evaluate both their efficacy and limitations. Although early clinical trials targeting chemokine pathways have yielded mixed outcomes, emerging research underscores the complexity of chemokine signaling and highlights multiple opportunities for stage-tailored and sex-specific interventions. Therefore, a deeper understanding of chemokine function in MASH holds considerable promise for facilitating the development of targeted, multidimensional treatment strategies, paving the way for personalized management of this progressive liver disorder.

Graphical Abstract

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease in the world, affecting up to 30% of the global population [1, 2]. In a pivotal nomenclature shift by multisociety Delphi consensus, “MASLD” replaced the previously used term “nonalcoholic fatty liver disease (NAFLD),” representing a move away from an exclusionary diagnosis ("nonalcoholic") and toward a positive, criterion-based framework centered on cardiometabolic dysfunction [3]. The diagnosis of MASLD requires the presence of hepatic steatosis along with at least one of the following five cardiometabolic risk criteria: (1) body mass index ≥ 25 kg/m² or waist circumference > 94/80 cm (ethnicity-specific cutoffs for men/women), (2) type 2 diabetes or fasting glucose level ≥ 100 mg/dL, (3) antihypertensive treatment or blood pressure ≥ 130/85 mmHg, (4) plasma triglycerides (TG) ≥ 150 mg/dL, and (5) plasma high-density lipoprotein (HDL)-cholesterol < 40/50 mg/dL (for men/women), thereby explicitly anchoring the disease in the context of systemic metabolic dysfunction.

The disease spectrum begins with metabolic dysfunction-associated steatotic liver (MASL), characterized by hepatic fat accumulation exceeding 5%. An estimated 20–30% of patients progress to metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (NASH), which is characterized by lobular inflammation, hepatocyte ballooning, and cell death. Although the transition to MASH is critical, it is crucial to note that the disease remains reversible until advanced fibrosis develops, and even early fibrotic changes in MASH have been shown to regress with interventions targeting the underlying metabolic disturbances; however, without such interventions, progressive fibrosis, cirrhosis, and hepatocellular carcinoma may develop [4]. Although several MASH-targeted therapies are under clinical evaluation, resmetirom, a thyroid hormone receptor-beta agonist, is the only currently approved pharmacologic treatment [5]. Therefore, elucidating the intricate pathogenesis of MASH and identifying strategies for early diagnosis and intervention are critical.

The etiology of MASH remains unclear. A range of factors—including insulin resistance, central obesity, environmental and dietary influences, the gut microbiota composition, and genetic and epigenetic predispositions—have been implicated in MASLD progression. When the liver’s capacity to handle free fatty acid (FFA) influx is overwhelmed, a cascade of maladaptive responses ensues, involving reactive oxygen species generation, endoplasmic reticulum stress, and hepatocellular dysfunction and damage. These processes collectively provoke hepatic inflammation and facilitate the transition from simple steatosis to MASH. Inflammation, which triggers immune responses, inflammatory cell infiltration, apoptotic pathways, hepatocyte death, and hepatic stellate cell (HSC) activation, all of which ultimately drive collagen deposition and fibrosis, is central to this pathogenic sequence.

Notably, chemokines—small signaling proteins that guide immune cell migration in inflammation and tissue repair—and their receptors (comprising both classical G protein-coupled receptors and atypical chemokine receptors [ACKRs]) play crucial roles in this network, mediating pivotal signal transduction during inflammation [6–8], although their role in MASH extends far beyond immune cell recruitment. They also function as crucial integrators at the crossroads of metabolism and inflammation, and their signals can directly act on core metabolic cells such as hepatocytes [9] to regulate lipid metabolism and mitochondrial oxidative stress. These findings position chemokines not only as passive bystanders but also as active effector molecules of pathophysiologies driven by metabolic dysfunction.

While the roles of chemokines in MASLD have been broadly reviewed, this article focuses specifically on MASH. Growing evidence indicates that chemokines drive inflammatory responses and disease progression in MASH through multiple mechanisms—including leukocyte recruitment, immune modulation, fibrosis promotion, and potential disruption of lipid metabolism. A deeper understanding of chemokine biology is therefore essential for deciphering MASH pathophysiology and identifying new therapeutic strategies. Specifically, this review systematically examines the mechanisms of action and functions of chemokines in MASH, critically assesses their diagnostic and prognostic potential by establishing a hierarchy of evidence, and discusses emerging therapies targeting chemokine pathways. By integrating both the chemotactic and non-chemotactic roles of chemokines into the core of MASH-related metabolic dysregulation and translational challenges (e.g., pathway redundancy), we aim to present a pathophysiological model that extends beyond conventional inflammatory paradigms and provides a critical theoretical foundation for future research and clinical translation.

Biology of chemokines and their receptors

Chemokine classification

Chemokines are small chemotactic cytokines that serve as principal regulators of immune cell trafficking by generating concentration gradients that direct the leukocyte migration and positioning necessary for immune surveillance, inflammatory responses, and tissue homeostasis.

On the basis of the configuration of conserved N-terminal cysteine residues, chemokines are classified into four main subfamilies: CC, CXC, XC, and CX3C [10–12]. Functionally, chemokines are broadly divided into two groups: homeostatic and inflammatory chemokines [13]. Homeostatic chemokines regulate constitutive leukocyte migration involved in organ development, immune monitoring, and tissue repair. CXCL12, CXCL13, CCL14, CCL19, CCL20, CCL21, CCL25, and CCL27 are representative homeostatic chemokines. In contrast, inflammatory chemokines are typically induced during an infection or under pathological conditions and facilitate immune cell recruitment to inflammatory loci, contributing to host defense and injury responses. Key examples include CXCL8, CCL2, CCL3, CCL4, CCL5, CCL11, and CXCL10. However, it should be noted that the homeostatic and inflammatory chemokine classification is not rigid, as some chemokines, such as CCL20, have both homeostatic and inflammatory functions.

Chemokine receptors and chemokine signaling pathways

Chemokines mediate their effects by binding to members of a group of seven-transmembrane G protein-coupled receptors (GPCRs). To date, 18 conventional chemokine receptors have been identified, many of which exhibit promiscuous ligand‒receptor binding [14, 15]. Chemokine signaling is initiated by ligand‒receptor binding and G protein activation, with the signal transduction cascade proceeding through several key stages. First, the dissociated Gα and Gβ/γ subunits activate distinct effectors: Gαi inhibits the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway, whereas Gβ/γ stimulates the phospholipase C-beta (PLC-β)/inositol-1,4,5-trisphosphate (IP3) pathway to mobilize intracellular calcium [14]. Concurrently, G protein-triggered phosphatidylinositol 3-kinase (PI3K) activation directs actin polymerization [16] and cytoskeletal rearrangements essential for chemotaxis [17]. A feedback mechanism is subsequently engaged, where GPCR kinase (GRK)-mediated receptor phosphorylation recruits β-arrestin [18]. This recruitment halts G protein signaling by uncoupling the receptor to promote its internalization. In addition to this regulatory role, β-arrestin serves as a nodal point for scaffolding the activation of mitogen-activated protein kinase (MAPK) pathways such as the p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathways. In a parallel signaling axis, the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway, which is often activated by cytokines, can also be co-opted to transduce signals that modulate gene expression and guide cell migration [11].

In addition to classical chemokine receptors, the chemokine receptor family also includes ACKRs. ACKRs (including ACKR1–4 and putative members such as CCRL2/ACKR5) are structurally uncoupled from the canonical Gαi-protein signaling pathways that trigger directed migration. It was initially believed that ACKRs were “silent” scavengers, but this longstanding paradigm has now been revised, as several ACKRs have been demonstrated to engage in specific and biologically relevant signal transduction. Notably, one of their key characteristics is their bias toward β-arrestin coupling upon ligand binding [19]. ACKR2, ACKR3, and ACKR4 recruit β-arrestins, which links them to the endocytic machinery for efficient chemokine scavenging and receptor recycling as well as to the activation of downstream signaling pathways such as MAPK and Akt phosphorylation. However, ACKR1 is an exception, as it does not recruit β-arrestins but can still activate signaling pathways. ACKR2 activation has been shown to trigger a β–arrestin1–Rac1–PAK1–LIM kinase–cofilin cascade important for its scavenging activity [20]. Furthermore, ACKRs can heterodimerize with classical chemokine receptors (e.g., ACKR3 and CXCR4) and thereby modulate their signaling output. However, the essential developmental functions of ACKR3 appear to rely on signaling mechanisms independent of both G proteins and β-arrestins, indicating the existence of other, yet to be fully elucidated, transduction pathways [21]. Thus, the chemokine system constitutes a finely tuned network comprising both classical signaling receptors and multifaceted atypical receptors that play indispensable roles in orchestrating immune responses in complex pathologies such as MASH.

Chemokines in MASH

The progression of MASH is driven by a self-perpetuating cycle involving the complex interplay between metabolic dysfunction and hepatic inflammation, which is orchestrated predominantly by chemokines. This pathogenic cascade originates from a triad of metabolic stressors: systemic insulin resistance, visceral adipose tissue dysfunction, and gut dysbiosis. These drivers induce the upregulation of key chemokines (such as CCL2, CCL5, CXCL1, and CCL20) via lipotoxic and microbial signals (e.g., FFAs and lipopolysaccharide (LPS)). These in turn recruit and activate immune cells such as macrophages and neutrophils, triggering a pro-inflammatory cytokine storm and direct cellular injury. This local damage further aggravates hepatocyte insulin resistance and lipid accumulation, thereby amplifying the initial metabolic lipotoxic insult and stimulating further chemokine production. This model positions chemokines not as passive bystanders but as active pathogenic integrators that link systemic metabolic disturbances with local inflammatory and fibrogenic responses. Consequently, therapeutic strategies targeting these molecules must consider their embedded role within this intricate network to achieve the ultimate aim of disrupting the core vicious cycle that sustains disease progression (Table 1; Fig. 1).

Table 1.

The roles of chemokines and their receptors in the pathogenesis of MASH

Chemokine	Alternative name	Chemokine receptor	Cellular source	Target cell	Key functions in MASH
CCL2	MCP-1	CCR2	Hepatocytes, Kupffer cells, HSCs, LSECs, erythrocytes	Monocytes, HSCs, endothelial cells	Promoting monocytes infiltration Inducing migration and activation of HSCs Triggering autophagy in endothelial cells
CCL3	MIP-1α	CCR1,5	Macrophages, hepatocytes, HSCs	Macrophages	Promoting monocytes infiltration and M1 polarization
CCL5	RANTES	CCR1,3,5	Hepatocytes, HSCs, LSECs, NK cells	Macrophages, Neutrophils, Hepatocytes, Endothelial cells	Promoting monocytes infiltration Promoting neutrophils infiltration Promoting hepatocyte steatosis Promoting migration, proliferation, and collagen deposition in HSCs
CCL11	Eotaxin-1	CCR3	Hepatocytes	Hepatocytes	Promoting a pro-inflammatory/pro-lipogenic phenotype of hepatocytes
CCL20	MIP-3α	CCR6	Hepatocytes, HSCs	Macrophages, HSCs	Promoting monocytes to M1 polarization and a pro-fibrotic phenotype Increasing extracellular matrix production of HSCs
CCL24	Eotaxin-2	CCR3	T cells, monocytes, LSECs, fibroblasts	HSCs	Inducing HSC motility, α-smooth muscle actin expression, and type I collagen secretion
CCL25	TECK	CCR9	Hepatocytes, HSCs, LSECs	Macrophages, HSCs	Promoting monocytes infiltration Increasing fibrogenic activity of HSCs
CXCL1	GRO-α	CXCR2	Hepatocytes, macrophages, HSCs	Neutrophils, HSCs	Promoting neutrophil infiltration Inducing HSCs to express α-smooth muscle actin and type I collagen
CXCL9	MIG	CXCR3	Hepatocytes, LSECs	Treg, Th17	Promoting the differentiation of CD4 + T cells into Th17 cells while inhibiting their differentiation into Treg cells Enhancing the proliferation of Th17 cells
CXCL10	IP-10	CXCR3	Hepatocytes, LSECs, macrophages, HSCs,	Macrophages, T cells, NK cells	Attracting activated CXCR3+ T lymphocytes and macrophages Impairing autophagic flux by inhibiting autolysosome formation, blocking the degradation of autophagy-related proteins, and leading to the accumulation of ubiquitinated proteins Enhancing the recruitment of CXCR3+ NK cells that mitigate fibrosis progression
CXCL12	SDF-1α	CXCR4,7	Hepatocytes, LSECs, bile duct epithelial cells	CD4+ T cells	Facilitating CD4+ T-cell migration
CX3CL1	Fractalkine	CX3CR1	HSCs, Macrophages	Macrophages	Alleviating inflammation and fibrosis by limiting macrophage infiltration and promoting M2 polarization

Fig. 1.

The central role of chemokines in orchestrating metabolic dysregulation, inflammation, and fibrosis in MASH. Multiple chemokine pathways drive MASH pathogenesis by concurrently inducing hepatic steatosis, inflammation, and fibrosis. In hepatocytes, the CCL20–CCR6 axis promotes cholesterol deposition, while CXCL10–CXCR3 signaling induces mitochondrial dysfunction, endoplasmic reticulum stress, and impaired autophagy, collectively contributing to steatosis. Concurrently, chemokines orchestrate hepatic inflammation by recruiting monocytes and macrophages via CCL2–CCR2, CCL3/CCL5–CCR1/CCR5, and CCL20–CCR6; neutrophils via CXCL1–CXCR2; and T cells and NK cells via CXCL9/CXCL10–CXCR3 and CXCL12–CXCR4, while also polarizing macrophages toward a pro-inflammatory M1 phenotype through CCL3, CCL20, and CXCL1. Furthermore, multiple chemokine pathways—including CCL2–CCR2, CCL5–CCR1/CCR5, CCL20–CCR6, CCL24–CCR3, and CXCL1–CXCR2—directly activate quiescent hepatic stellate cells (qHSCs) into collagen-producing activated HSCs (aHSCs), thereby accelerating fibrosis. Together, these chemokine-mediated mechanisms integrate metabolic dysfunction, inflammation, and fibrosis into a self-sustaining cycle that propagates MASH progression

The CC chemokine family

CCL2

CCL2 (also known as monocyte chemoattractant protein-1 (MCP-1)) is among the most extensively studied chemokines in MASH and plays a pivotal role in disease pathogenesis by mediating immune cell recruitment and activating pro-fibrotic pathways. It is produced by multiple hepatic cell types—including hepatocytes, Kupffer cells [22], HSCs [23, 24], liver sinusoidal endothelial cells (LSECs) [25], and cholangiocytes [26]—and acts primarily via its receptor CCR2, which is highly expressed on bone marrow-derived monocytes and promotes their chemotaxis to the liver [27]. In addition to promoting monocyte recruitment, CCL2 directly facilitates HSC migration and activation [28] and induces autophagy in endothelial cells [25], thereby exacerbating both inflammatory and fibrotic processes. Genetic inhibition of the CCL2/CCR2 axis reduces monocyte infiltration, inflammation, and fibrosis in MASH preclinical models [29].

Notably, CCL2 upregulation is sexually dimorphic. Hepatic CCL2 is significantly upregulated in dietary models such as the methionine‒choline-deficient (MCD) diet and high-fat diet (HFD). However, male mice show more pronounced increases in hepatic CCL2 in response to diet than female mice do [30–32], suggesting a mechanism underlying sex-based differences in MASH susceptibility. This sex-specific disparity in CCL2 expression, which could be related to sex-specific chemokine expression, the influence of sex hormones, or sex-specific activation of inflammasomes, could influence the severity and progression of MASH, suggesting a potential avenue for personalized therapeutic strategies targeting chemokine pathways in a sex-specific manner.

The expression of CCL2 is tightly regulated by multiple signaling pathways activated in MASH, mainly cell death and stress pathways. Receptor-interacting kinase 3 (RIP3)-dependent JNK activation promotes CCL2 release, fostering macrophage recruitment and perpetuating a cycle of cell death and fibrosis [33]. Inflammatory signaling through the JNK/Src homology region 2 domain-containing phosphatase (SHP)/nuclear factor kappa B (NF-κB) [34] and Sparcl1/Toll-like receptor 4 (TLR4)/NF-κB/p65 axes enhances CCL2 expression, exacerbating macrophage-mediated inflammation. Epigenetic and transcriptional control is exerted by methyltransferase-like 3 (METTL3), an m⁶A methyltransferase that binds to the CCL2 promoter and recruits histone deacetylase (HDAC)1/2 to repress transcription via histone deacetylation. Accordingly, METTL3 overexpression ameliorates MASH by suppressing CCL2, whereas its deletion exacerbates the disease [35]. Additional modulators include Notch activation in hepatocytes [29] and group IVA phospholipase A2 (IVA-PLA2) in HSCs [24], which further upregulate CCL2, linking metabolic injury to chemokine-driven inflammation and fibrogenesis. Conversely, the gut microbiota can exert protective effects on this axis via metabolic byproducts. Short-chain fatty acids (SCFAs), such as butyrate, which is produced by commensal bacteria, have been shown to epigenetically suppress hepatic CCL2 transcription by inhibiting histone deacetylases (HDACs), thereby reducing macrophage infiltration. This highlights a potential therapeutic avenue in which restoring the gut microbial balance could dampen the hepatic CCL2–CCR2 inflammatory drive [36]. Additionally, CCL2 functions as a critical mediator of the crosstalk between visceral adipose tissue (VAT) and the liver. Clinical studies have shown that circulating CCL2 levels are strongly correlated with visceral adiposity and insulin resistance (HOMA-IR) in patients with MASLD, independent of hepatic fibrosis stage [37]. In obesity, expanded visceral adipose tissue secretes high levels of CCL2, which contributes to systemic insulin resistance by recruiting macrophages into adipose tissue; these macrophages release TNF-α, which in turn impairs insulin signaling, thereby establishing an “adipose‒liver” axis of metabolic inflammation [38]. This intricate regulation by metabolic stress pathways, coupled with its systemic correlation with insulin resistance, underscores that CCL2 is not merely a downstream inflammatory mediator but an integral component of maladaptive metabolic responses, directly linking lipotoxicity to chemokine-driven pathology (Fig. 2).

Fig. 2.

Pathogenic role and regulation of the CCL2/CCR2 axis in MASH. CCL2 is a central chemokine in MASH pathogenesis. It is secreted by multiple hepatic cell types, including hepatocytes, Kupffer cells, and hepatic stellate cells (HSCs). Its primary receptor, CCR2, is highly expressed on bone marrow-derived monocytes, guiding their chemotaxis to the liver. Beyond immune recruitment, CCL2 directly promotes HSC migration and activation and induces autophagy in liver sinusoidal endothelial cells (LSECs). The expression of CCL2 is tightly regulated by several signaling pathways activated in MASH: (1) RIP3-dependent JNK activation promotes CCL2 release; (2) the JNK/SHP/NF-κB and Sparcl1/TLR4/NF-κB/p65 pathways enhance CCL2 transcription, amplifying macrophage-mediated inflammation; (3) the methyltransferase METTL3 binds to the Ccl2 promoter, recruiting HDAC1/2 to deacetylate histones H3K9 and H3K27, thereby repressing CCL2 transcription and ameliorating MASH. HSC, hepatic stellate cell; LSEC, liver sinusoidal endothelial cell

CCL2 has also been extensively investigated as a candidate biomarker for MASH. Consistent with its pathogenic roles, circulating and hepatic CCL2 levels are frequently higher in patients with MASH than in those with MASL or healthy controls [39, 40]. Transcriptomic analyses often identify CCL2 as a hub gene in disease-related networks [41], and meta-analyses have corroborated its upregulation in MASH versus MASLD [42]. These associative data robustly position CCL2 within the disease process. Promising initial reports, such as a single-center study proposing a serum CCL2 cutoff (≥ 227 pg/mL) for MASH diagnosis that demonstrated high diagnostic accuracy [43], highlight its potential. Models that incorporate CCL2 along with other parameters have also been shown to better predict disease progression [39]. Moreover, elevated CCL2 levels systematically correlate with cardiovascular risk [44], underscoring its link to extrahepatic metabolic complications.

However, translating these associations into robust, standalone clinical biomarkers faces significant hurdles. The diagnostic performance of CCL2 is highly context dependent and has not been consistently validated in large, independent, and diverse cohorts. The impressive performance metrics reported in initial, often single-center, studies are susceptible to overfitting and may not be generalizable to broader populations. The profound variability in its relationship with core histological features is also a key limitation. While CCL2 levels are correlated with hepatocyte ballooning [43], NAFLD activity score (NAS) [38], and hepatic monocyte-derived macrophage infiltration [29, 45], their associations with fibrosis stage are inconsistent and vary dramatically across demographics. For example, circulating CCL2 often serves as an indicator of visceral adipose tissue mass and systemic inflammation [37, 46], rather than a liver-specific indicator of fibrotic burden, in adults; in contrast, pediatric studies frequently report a strong correlation with fibrosis [47]. This discrepancy between adults and children is not a minor nuance but rather a fundamental illustration of how biomarker performance can be confounded by age, comorbidities, and disease drivers. It also underscores the critical gap between identifying a molecule associated with a disease and deploying it as a reliable diagnostic or prognostic tool across heterogeneous patient populations. Furthermore, a critical “specificity crisis” hampers the clinical utility of circulating CCL2. Given that MASH is intrinsically linked to obesity, the massive expansion of visceral adipose tissue—a prolific source of CCL2—creates “background noise” that may drown out the liver-specific signal. This systemic spillover likely explains why the serum CCL2 level is better correlated with insulin resistance than with the hepatic fibrosis stage in adults. Therefore, unless liver-specific isoforms or methylation signatures can be identified, systemic CCL2 levels may remain a marker of “metabolic inflammation” rather than a precise surrogate for hepatic injury.

Pharmacological inhibition of the CCL2/CCR2 axis has proven effective in multiple animal models [48]. For example, the Spiegelmer mNOX-E36, a CCL2-neutralizing agent, attenuated hepatic steatosis and macrophage infiltration in an MCD diet-induced MASH model, highlighting the potential of direct chemokine blockade [49]. Similarly, small-molecule CCR2 antagonists such as CCX872 have been shown to ameliorate liver inflammation and fibrosis in a fat-, fructose-, and cholesterol-rich (FFC) diet-fed mouse model, primarily by reducing the hepatic influx of pro-inflammatory CD11b⁺CD11c⁺F4/80⁺ monocytes [38]. The CCR2 inhibitor propagermanium also confers protective effects in an HFD-induced rat model, particularly when it is administered during the early stages of the disease, mitigating adipose tissue inflammation and improving liver pathology [50].

CCL3

CCL3 (macrophage inflammatory protein-1α, MIP-1α) is expressed predominantly by hepatic macrophages, with particularly high levels observed in CD11c⁺ M1-polarized subsets [51], although hepatocytes and HSCs also contribute to its production [52]. This chemokine signals through the CCR1 and CCR5 receptors, which are expressed on a range of immune cells, including macrophages, T cells, eosinophils, neutrophils, and natural killer (NK) cells, enabling CCL3 to coordinate diverse inflammatory responses [53].

In experimental MASH models, such as those induced by a high-fat high-cholesterol (HFHC) diet, CCL3 levels are markedly elevated in both the liver and serum. Moreover, bone marrow-specific deletion of CCL3 in these models attenuates macrophage infiltration and reduces M1 polarization, underscoring its role in driving both inflammation and fibrogenesis [51]. The regulatory mechanisms governing CCL3 expression are multifaceted and cell type specific. For example, in a choline-deficient dietary model, TIR-domain-containing adapter-inducing interferon-β (TRIF)-dependent TLR4 signaling specifically downregulates CCL3 in HSCs, whereas myeloid differentiation primary response 88 (MyD88)-dependent TLR4 signaling upregulates its expression in macrophages, hepatocytes, and HSCs [52]. Furthermore, the tumor suppressor odd-skipped related 1 (OSR1) modulates CCL3 transcription by binding to its CpG island, influencing methylation status and thereby contributing to the inflammatory milieu in MASH [54].

Clinically, CCL3 levels are consistently higher in patients with MASH than those with MASL or healthy controls [55], a conclusion strongly supported by meta-analyses [42]. Circulating CCL3 concentrations are positively correlated with histological disease severity, the NAS, and alanine transaminase levels [55], supporting its potential utility as a prognostic biomarker for disease progression and treatment response. In addition to its hepatic effects, CCL3 may also contribute to systemic manifestations of MASH. Elevated serum levels of CCL3 and its related chemokine CCL4 have been associated with neuroinflammation in a diet-induced animal model of n’sic fatty liver disease (DIAMOND) in mice, suggesting a possible role in MASH-related extrahepatic comorbidities such as cognitive decline and brain atrophy [56], although this potential connection still warrants further investigation.

CCL5

CCL5 (regulated upon activation, normal T-cell expressed and secreted, RANTES) is produced by multiple hepatic cell types—including hepatocytes [57], HSCs [58], LSECs [25], and NK cells [59]—and promotes the migration of macrophages and neutrophils through the receptors CCR1, CCR3, and CCR5. Patients with MASH have elevated serum levels of CCL5, and both CCL5 and its receptor CCR5 are upregulated in animal models of MASH [57]. Global interleukin (IL)-15 knockout in MASH model mice results in marked downregulation of CCL5 and reduced macrophage infiltration, underscoring its essential role in macrophage recruitment and the maintenance of hepatic inflammation [60]. HSC-derived CCL5 contributes to hepatocyte steatosis in early MASH, indicating its involvement in both metabolic dysregulation and inflammatory pathways [58]. Furthermore, in a MASH-related hepatocellular carcinoma model, a reduction in circulating CCL5 levels attenuated hepatic neutrophil accumulation, confirming its function in neutrophil recruitment [61]. Together, these findings suggest that CCL5 not only helps initiate inflammatory processes in early disease stages but also may assume more complex roles as MASH advances.

CCL5 expression is induced under inflammatory and lipotoxic conditions [62]. In hepatocytes, FFA stimulation promotes CCAAT/enhancer-binding protein β (C/EBP-β) binding to the CCL5 promoter, driving its transcriptional activation [57]. Moreover, CCL5 secreted from lipids-overloaded with Fa2N-4 hepatocytes activates LX2 stellate cells, increasing their migration, proliferation, and collagen deposition [57]. Crucially, these findings reveal a direct, non-chemotactic axis between metabolic stress and fibrosis: lipid-overloaded hepatocytes secrete CCL5, which in turn directly activates stellate cells to drive collagen deposition. This positions CCL5 as a key signal transducer that translates a metabolic insult (hepatocyte steatosis) into a profibrotic response. Additionally, autophagy-impaired LSECs from both MASH patients and experimental models exhibit increased CCL5 expression, which promotes endothelial-to-mesenchymal transition, apoptosis, and fibrosis, revealing a role of endothelial dysfunction in CCL5-mediated pathogenesis [25].

Therapeutic targeting of the CCL5 pathway, particularly its receptor CCR5, reveals a complex, cell-specific paradox. The CCL5 inhibitor Met-CCL5 significantly attenuates liver fibrosis in HFD-induced MASH model rats, supporting its use as an anti-fibrotic agent [57]. However, while pharmacological inhibition of CCR5 can ameliorate MASH, global genetic deletion of CCR5 may exacerbate hepatic steatosis [63]. This discrepancy stems from the distinct functions of CCR5 in different cell types. In hepatocytes, CCR5 signaling plays a non-canonical, metabolic homeostatic role by constraining lipogenesis, likely via STAT3 suppression. Conversely, in immune cells such as granulocytic myeloid-derived suppressor cells (g-MDSCs), CCR5 promotes a pro-inflammatory phenotype by driving the release of factors that enhance STAT3-mediated lipogenesis in hepatocytes. Adoptive transfer studies have confirmed that CCR5-deficient g-MDSCs can reduce hepatic lipogenesis without worsening inflammation [63]. Therefore, the net effect of modulating the CCL5/CCR5 axis is determined by the delicate balance between its protective metabolic function in parenchymal cells and its pathogenic role in immune cells. This dichotomy poses a significant pharmacological risk: systemic blockade of CCR5/CCL5 to dampen immune recruitment could inadvertently release the 'brake' on hepatocyte lipogenesis, potentially exacerbating steatosis even while reducing inflammation. This 'on-target adverse effect' highlights the inadequacy of systemic antagonists and underscores the urgent need for cell type-specific delivery systems (e.g., myeloid-targeted nanoparticles) that can silence the receptor on immune cells while sparing its metabolic protective function in hepatocytes.

CCR1—a shared receptor for CCL3, CCL5, and CCL23—is upregulated in both human MASH and experimental models, particularly in macrophages. Both genetic deletion and pharmacological inhibition of CCR1 ameliorate steatosis, inflammation, and fibrosis in mice, highlighting CCR1 as a promising target for modulating multiple chemokine pathways in MASH [64].

CCL11

CCL11 (eotaxin-1), a hepatocyte-derived chemokine that signals through the CCR3 receptor, has been increasingly recognized as a contributor to MASH pathogenesis. Clinically, CCL11 levels are elevated in patients with MASH, and its hepatic expression is upregulated by FFAs such as palmitic acid [65]. Studies on CCL11-deficient mice have demonstrated that loss of this chemokine attenuates the MASH phenotype, leading to improved insulin sensitivity and reduced weight gain, adipose accumulation, immune cell infiltration, and hepatic fibrosis. Furthermore, transcriptomic analyses have identified interferon regulatory factor 1 (IRF1) as a key downstream mediator of CCL11-induced hepatocellular changes, revealing a defined mechanistic pathway through which CCL11 exacerbates disease progression [65].

In human patients with MASH, hepatic CCL11 expression is positively correlated with the levels of serum alanine transaminase, total TG, and total cholesterol (TC) and with the levels of inflammatory and fibrotic markers such as tumor necrosis factor α (TNF-α) and collagen type 1 alpha 1 chain (COL1A1) [65]. These associations support the potential of CCL11 as a diagnostic and prognostic biomarker for MASH-related inflammation and fibrosis. However, the preliminary nature and limited sample sizes of the existing studies highlight the need for validation in larger, more diverse cohorts before CCL11 can be translated into clinical practice.

Interventions targeting the CCL11–CCR3 axis, which use either a neutralizing anti-CCL11 antibody or the CCR3 antagonist SB297006, have shown efficacy in murine MASH models in terms of improved metabolic and histologic features, including weight gain, insulin resistance, hepatic steatosis, immune cell infiltration, and fibrosis [65]. Together, these findings establish CCL11 as a functionally relevant chemokine and a promising target for therapeutic intervention in MASH.

CCL20

CCL20 (macrophage inflammatory protein 3α, MIP-3α) is markedly upregulated in the livers of both human MASH patients and experimental model mice. Although traditionally attributed to hepatocytes [66] and HSCs [67], we recently identified hepatic progenitor cells (HPCs) and cholangiocytes as the primary cellular sources of CCL20 in MASH, with its transcription driven by the RELB and SOX9 transcription factors. CCL20 signals exclusively through its receptor CCR6, which is predominantly expressed on lymphocytes but is also functionally upregulated in hepatocytes in MASH [9]. In mice fed an MCD diet, hepatic CCL20 transcription increases progressively over time, indicating a role in disease progression [68]. Under lipotoxic conditions, CCL20 promotes the polarization of macrophages to the pro-inflammatory M1 and pro-fibrotic phenotypes [66] and concurrently activates HSCs to increase extracellular matrix production and accelerate fibrosis [67].

Mechanistically, the CCL20–CCR6 axis represents a paradigm of the direct, non-chemotactic role of chemokines in metabolic dysregulation. In hepatocytes, CCL20 activates the MKK4–JNK–JUN pathway, leading to the upregulation of oxidized low-density lipoprotein receptor 1 (OLR1). This cascade enhances oxidized low-density lipoprotein uptake and intracellular cholesterol deposition, directly linking CCL20 to metabolic dysregulation in hepatocytes [9]. Concurrently, CCL20 modulates sterol regulatory element-binding proteins (SREBPs) via sirtuin 1 (SIRT1), thereby affecting fatty acid synthesis, uptake, and storage. Through these dual mechanisms, CCL20 directly reprograms hepatocyte lipid metabolism, acting as a core driver of metabolic dysfunction independently of immune cell recruitment. This metabolic crosstalk is bidirectional: CCL20 expression is robustly upregulated by fatty acid loading (e.g., palmitate) [69]—mediated by the ERK1/2 and p38 MAPK signaling pathways [70]—mimicking the lipotoxic environment of insulin-resistant visceral adiposity. Thus, CCL20 lies at a critical intersection between metabolic dysfunction and inflammation, acting as both a responder to lipid overload and an amplifier of cholesterol dysregulation.

Clinical evidence also strongly supports the translational importance of CCL20. Transcriptomic analyses consistently rank CCL20 among the most upregulated chemokines in the liver in MASH patients [70, 71], and a comprehensive meta-analysis of over 8,000 participants identified CCL20 as the most predictive chemokine for diagnosing MASH [42]. Importantly, elevated serum CCL20 levels are closely correlated with intrahepatic CCL20 expression and advanced fibrosis stage [69, 70], highlighting its utility as a non-invasive diagnostic biomarker and a prognostic indicator for fibrosis progression. Genetic or viral knockdown of CCL20–CCR6 signaling ameliorates steatosis and cholesterol deposition in preclinical models, further reinforcing its therapeutic potential [9].

CCL24

CCL24 is produced in the liver by a variety of cell types, including activated T cells, monocytes, epithelial and endothelial cells, and fibroblasts [72–74]. It acts primarily through the CCR3 receptor to exert pro-inflammatory and pro-fibrotic effects such as promoting the recruitment of immune cells [75, 76] and fibroblasts [77]. Clinically, patients with MASH have significantly elevated hepatic as well as circulating CCL24 and CCR3 levels, supporting their relevance in disease pathogenesis.

Therapeutic targeting of CCL24 has yielded encouraging outcomes in experimental models. Treatment with CM-101, a monoclonal antibody against CCL24, significantly alleviated liver injury and fibrosis in mice with MCD diet-induced MASH, and mechanistic investigations demonstrated that CM-101 suppressed CCL24-induced HSC motility, α-smooth muscle actin expression, and type I collagen secretion [78]. These results underscore the potential of CCL24 inhibition as an anti-fibrotic approach in MASH and other fibrotic liver disorders.

CCL25

CCL25, also referred to as thymus-expressed chemokine (TECK), is expressed in the liver by hepatocytes, HSCs, and endothelial cells. The exclusive receptor CCR9 is expressed on a diverse range of immune cells, such as T cells, NK cells, dendritic cells, HSCs, and macrophages [79, 80]. Clinically, both CCL25 and CCR9 levels are elevated in both the serum and liver of MASH patients, supporting the pathophysiological relevance of this chemokine axis [81].

Experimental studies further underscore its functional significance. CCR9 knockout alleviated key aspects of MASH, improved liver function, reduced inflammation, and attenuated fibrosis in a HFHC diet model; moreover, the mice had a reduced CCR9 + CD11b + macrophage population. In vitro, CCR9-deficient HSCs have diminished fibrogenic activity, and therapeutic treatment with a CCR9 antagonist suppressed fibrosis progression in MASH model mice. Notably, CCR9 blockade also prevented the development of MASH-associated hepatocellular carcinoma in a mouse model, highlighting the broad therapeutic potential of targeting this pathway [81].

Emerging evidence also implicates the CCL25–CCR9 axis in gut–liver crosstalk during MASH pathogenesis. Dysfunctional CD103 + CD11b + dendritic cells may lead to impaired intestinal CCL25/CCR9 signaling, contributing to intestinal immune imbalances, which in turn exacerbate hepatic inflammation and disease progression [82]. This evolving perspective positions CCL25 not only as a mediator of intrahepatic inflammation and fibrosis but also as a potential regulator of the gut–liver axis, revealing a multifaceted role in MASH that warrants further investigation.

The CXC chemokine family

CXCL1

CXCL1, a major neutrophil chemoattractant, serves as a critical mediator of pathological neutrophil recruitment to the liver in MASH by signaling through the CXCR2 receptor, thereby promoting the transition from MASL to MASH [83]. Within the liver, CXCL1 is produced by hepatocytes [84], macrophages, and HSCs [52, 85]. Notably, prominent hepatic neutrophil infiltration and marked upregulation of CXCL1 are hallmarks of human MASH. Pathological neutrophil accumulation is seldom observed in simple steatotic livers in obese individuals or in mice fed a HFD [86], and only modest elevations in CXCL1 are detected in purely steatotic livers or murine HFD models [86].

A key challenge in modeling robust neutrophilic inflammation in common mouse models of MASH, such as HFD-induced models, lies in fundamental interspecies differences in the CXCR2 ligand system. Humans express a broad repertoire of CXCR2 agonists, including IL-8 and CXCL1, whereas mice lack a direct IL-8 ortholog and rely primarily on the functional homologs KC (CXCL1) and CXCL2 for neutrophil recruitment. This divergence in genetic repertoire and inflammatory signaling likely underlies the generally attenuated neutrophil-driven pathology in most dietary murine models of MASH. Nevertheless, experimental enhancement of CXCL1 signaling in mice unequivocally exacerbates MASH pathology [87]. Adenoviral-mediated overexpression of CXCL1 in HFD-fed mice induces potent neutrophil chemotaxis, activates pro-inflammatory kinases such as apoptosis signal-regulating kinase 1 (ASK1) and p38 MAPK, and amplifies liver injury and inflammation [88], confirming that the downstream inflammatory machinery remains functional in mice and that CXCL1 is sufficient to drive disease progression when adequately expressed.

The regulation of CXCL1 is complex and orchestrated by multiple layers of signaling. At the most upstream level, the gut‒liver axis plays a pivotal initiating role. Mechanistic studies have demonstrated that the secretion of CXCL1 by hepatic stellate cells is strictly dependent on the activation of TLR4 by gut-derived microbial products (such as LPS); notably, microbiota depletion significantly abrogates hepatic CXCL1 expression and subsequent neutrophil infiltration, directly linking intestinal permeability to hepatic inflammation [89]. Downstream of this trigger, TLR4 signaling exerts different effects on CXCL1 through its adaptor proteins—TRIF-dependent signaling upregulates CXCL1 in HSCs, whereas MyD88-dependent signaling appears to have a net downregulatory effect on macrophages, HSCs, and hepatocytes [52]. Once initiated, inflammation is sustained by local feed-forward loops. For example, neutrophil-derived myeloperoxidase (MPO) autonomously stimulates HSCs [85] and Kupffer cells [90] to produce CXCL1, an effect inhibited by the scavenger taurine. Additionally, in vivo IL-1α levels also modulate serum CXCL1 [91]. Finally, from a pharmacological perspective, the mitochondrial translocator protein (TSPO) ligand 3,17,19-androsten-5-triol (Atriol) downregulates CXCL1, partly by inhibiting the NF-κB signaling pathway in hepatocytes and macrophages, revealing a novel pharmacological route for CXCL1 modulation [90].

In addition to its proinflammatory functions, CXCL1 directly contributes to fibrosis. Recruited neutrophils activate HSCs and increase the production of survival factors such as granulocyte‒macrophage colony‒stimulating factor (GM-CSF) and IL-15. CXCL1 can also directly stimulate HSCs to express α-smooth muscle actin and type I collagen [92]. Recent functional studies further emphasize its direct pathogenic role, as recombinant CXCL1 treatment was found to impair mitochondrial function in hepatocytes, activate HSCs, and promote macrophage migration; moreover, these detrimental effects were effectively counteracted by Atriol, suggesting that CXCL1 inhibition is a viable therapeutic strategy [90].

The translational importance of targeting CXCL1 is strongly supported by recent interventional studies. Both pharmacological inhibition of the upstream NF-κB/CXCL1 axis by celastrol and direct antibody-based neutralization of CXCL1 successfully ameliorate key features of MASH, including steatosis, inflammation, and fibrosis, in preclinical models, mirroring the therapeutic benefits of Atriol [90]. Collectively, this evidence establishes the CXCL1 pathway as a promising therapeutically actionable target in MASH. However, the translational viability of targeting CXCL1 hinges on defining the precise 'therapeutic window.' Neutrophil infiltration is often an early, acute response to lipotoxicity (neutrophil burst), which may subside or become less dominant as the disease transitions to chronic, lymphocyte-driven fibrosis. If human MASH is diagnosed at an advanced stage (e.g., F2/F3), targeting the upstream neutrophil recruiter CXCL1 might be ineffective if the disease drivers have already shifted to autonomous macrophage or stellate cell activation. Thus, CXCL1 inhibition may be best positioned as an early preventive strategy rather than a reversal therapy for established fibrosis.

CXCL8

CXCL8 (interleukin-8, IL-8) is a potent neutrophil-recruiting chemokine that signals through the CXCR1 and CXCR2 receptors. Its expression is significantly elevated in the livers of MASH patients [40, 93], yet its precise mechanistic role has long been obscured by the absence of a direct CXCL8 ortholog in mice. While this interspecies divergence restricts rodent-based investigations, human-centric studies have begun to unravel its regulation, particularly linking it to the gut‒liver axis. Emerging evidence indicates that dysregulated bile acid metabolism—a consequence of gut dysbiosis—directly drives hepatic CXCL8 expression. Specifically, secondary bile acids such as deoxycholic acid (DCA) can activate signaling pathways in hepatocytes to induce CXCL8 secretion [94]. This finding provides a critical mechanistic bridge explaining how an altered microbiome translates into the hallmark neutrophilic inflammation observed in human MASH.

Clinically, CXCL8 exhibits distinctive sexual dimorphism. Systemic CXCL8 levels are significantly higher in female MASH patients than in both healthy controls and MASL patients [95], suggesting a sex-specific regulatory mechanism that warrants further exploration. Meta-analyses further indicate that CXCL8 levels are elevated across the steatotic liver disease spectrum, with moderate increases in MASL and more marked elevations in MASH [42]. Collectively, these attributes position CXCL8 not only as a general inflammation marker but also as a promising candidate for stage-sensitive diagnosis and monitoring, with particular utility in stratifying female patient populations. Nevertheless, the absence of a CXCL8 ortholog in rodents represents a formidable 'translational blind spot.' While surrogate markers such as CXCL1/CXCL2 are used in mice, they cannot recapitulate the potent, sustained neutrophil recruitment driven by CXCL8 in humans. This biological divergence implies that standard murine models may fundamentally underestimate the severity of neutrophilic inflammation in human MASH. Consequently, preclinical success in mice may yield false optimism for human trials, necessitating the use of 'humanized' mouse models or complex organoids to faithfully evaluate CXCL8-targeted interventions.

CXCL9

CXCL9 (monokine induced by interferon-γ, MIG) is produced mainly by hepatocytes and LSECs and mediates immune cell trafficking, particularly of T cells and NK cells, via its receptor CXCR3 [84]. Experimental models show increased hepatic CXCL9 expression in MASH. Longitudinal studies in DIAMOND mice revealed time-dependent upregulation, with a notable increase at 24 weeks (MASH stage) and further elevation by 40 weeks (hepatocellular carcinoma stage). This progressive increase, which was more pronounced in male mice, suggests that sustained CXCL9 expression may be linked to progression toward liver cancer, potentially contributing to sex-based disparities in MASH-related hepatocarcinogenesis [96].

The functional influence of CXCL9 on T-cell polarization further underscores its pathogenic role. In an MCD-induced MASH model, hepatic knockout of CXCL9 altered CXCR3 expression patterns, reducing its expression on regulatory T cells (Tregs) while increasing its expression on T helper 17 (Th17 cells). This shift favors Th17 cell differentiation and expansion over Treg development, tilting the immune balance toward a pro-inflammatory state [97].

Clinically, CXCL9 has emerged as a promising biomarker and multifunctional mediator in MASH. Its expression is elevated in the livers of obese individuals, even at early fibrosis stages (F0), and transcriptomic analyses support its diagnostic utility for predicting MASH [98]. In addition, CXCL9 correlates with M1 macrophage infiltration and is enriched in amino acid metabolism pathways, linking it to both inflammatory and metabolic dysregulation [99]. Furthermore, its involvement in extrahepatic conditions such as atherosclerosis and inflammatory bowel disease reinforces its potential as a prognostic indicator for MASH and its systemic complications [100, 101].

CXCL10

CXCL10 (interferon-γ-inducible protein 10, IP-10) plays a complex and context-dependent role in MASH pathogenesis, exhibiting both pro-inflammatory and protective functions. It is produced predominantly by hepatocytes [102], with additional contributions from LSECs [103], macrophages, and HSCs [104]. CXCL10 signals through its receptor, CXCR3, which is expressed on T cells, NK cells, and macrophages.

In experimental MASH models, hepatic CXCL10 is significantly upregulated, and its level is correlated with the severity of lobular inflammation [105]. It acts as a dual-function driver of disease progression. First, acting as a classical chemokine, it promotes the recruitment of CXCR3 + T lymphocytes and macrophages, thereby exacerbating inflammation, hepatocyte apoptosis, and fibrosis [104]. Second, CXCL10 is intrinsically linked to metabolic dysregulation. Mechanistically, lipotoxicity—a hallmark of insulin-resistant states—directly drives CXCL10 transcription in hepatocytes via the activation of the mixed lineage kinase 3 (MLK3)–MAPK–STAT1 axis [106]. Once induced, CXCL10 exerts "chemokine-independent" metabolic toxicity by directly impairing autophagic flux and inhibiting autolysosome formation [107]. This creates a vicious cycle in which lipotoxicity induces CXCL10, which in turn exacerbates mitochondrial dysfunction and cellular injury independent of immune recruitment. Consequently, serum CXCL10 levels are significantly elevated in patients with insulin resistance and correlate positively with the HOMA-IR index [108]. Additionally, hepatocytes release extracellular vesicles enriched with CXCL10, which further enhances macrophage activation [102].

Genetic ablation of CXCL10 markedly attenuated the hepatic infiltration of pro-inflammatory macrophages without significantly affecting the recruitment of NK cells, natural killer T (NKT) cells, neutrophils, or dendritic cells in an FFC diet-induced MASH mouse model. This finding underscores the specific and crucial role of CXCL10 in driving macrophage-mediated sterile inflammation in MASH [109]. Consistent with this, both genetic and pharmacological inhibition of CXCL10 have been demonstrated to ameliorate liver injury, inflammation, and fibrosis, an effect primarily attributed to a reduction in pro-inflammatory macrophage accumulation [108].

The paradox of CXCL10—promoting inflammation while potentially limiting fibrosis—is not random but is strictly dictated by spatiotemporal determinants and cellular sources. Temporally, in the early phase of injury, CXCL10 expression may be protective by recruiting CXCR3 + NK cells to clear senescent stellate cells, thereby acting as a 'fibrosis brake' [110]. However, in established MASH, sustained, high-level CXCL10 secretion (driven by chronic lipotoxicity) overwhelmingly recruits pro-inflammatory CXCR3 + macrophages and Th1 cells, tipping the balance toward injury [104]. Spatially, the function of CXCL10 is context dependent on its origin. Hepatocyte-derived CXCL10 is intimately linked to autocrine mitochondrial dysfunction and apoptosis [107], initiating damage signals. In contrast, LSEC-derived CXCL10 is dynamically regulated by free fatty acids to modulate local immune surveillance [103]. Therefore, the net clinical outcome of CXCL10 signaling is determined by the specific disease stage and the dominant cellular driver, suggesting that therapeutic blockade must be critically timed to target the chronic inflammatory phase while sparing early protective surveillance (Fig. 3).

Fig. 3.

Dual and context-dependent roles of CXCL10 in MASH pathogenesis. CXCL10 exhibits a multifaceted role in MASH, driven by lipotoxic stress. In hepatocytes, free fatty acids activate the MLK3-MAPK (MKK3/6-p38) signaling cascade, leading to STAT1 phosphorylation and subsequent upregulation of CXCL10 transcription. Hepatocytes also release CXCL10-enriched extracellular vesicles that activate macrophages, propagating inflammation. Elevated CXCL10 impairs autophagic flux by inhibiting autolysosome formation, leading to the accumulation of ubiquitinated proteins and aggravated cellular injury. Through its receptor CXCR3, hepatocyte-derived CXCL10 recruits T lymphocytes and macrophages, exacerbating inflammation, apoptosis, and fibrosis. Paradoxically, in early disease stages, the CXCL10-CXCR3 axis also recruits hepatic NK cells, which can attenuate fibrosis progression. In addition, liver sinusoidal endothelial cells (LSECs) exposed to free fatty acids downregulate CXCL10 expression, which reduces monocyte migration and promotes an anti-inflammatory phenotype. The net effect of CXCL10 is thus determined by the balance between these opposing pro-inflammatory and protective mechanisms, which are influenced by the cellular source and disease stage. (LSEC, liver sinusoidal endothelial cell; NK cell, natural killer cell)

Clinically, transcriptomic analyses consistently identify CXCL10 as one of the most upregulated genes in the livers of patients with MASH [71, 111]. Serum CXCL10 levels are also elevated in patients [42] and correlate with lobular inflammation and the NAS, supporting its utility as a noninvasive biomarker [108, 112, 113]. However, given their dual functions, therapies targeting CXCL10 require precise patient stratification and stage-specific approaches to maximize efficacy and minimize potential adverse effects.

CXCL12

CXCL12 is produced mainly by hepatocytes, LSECs, and bile duct epithelial cells and signals through its receptor, CXCR4, which is expressed predominantly on lymphocytes and endothelial cells [114]. While the CXCL12–CXCR4 axis has been well-characterized in liver cancer [115], its role in MASH is only beginning to be clarified. In murine MASH models, CXCL12 promotes the migration of CD4⁺ T cells via CXCR4, and inhibition of this receptor reduces their accumulation in hepatic tissue. Interestingly, although hepatic CXCL12 levels and CXCR4 expression on CD4 + T cells remain largely unaltered, the enhanced binding affinity between CXCL12 and CXCR4 appears to be a key driver of disease progression. In support of this observation, in vitro studies have shown that CD4 + T cells from MASH patients have significantly greater migratory capacity than those from patients with MASL, an effect that is reversed upon CXCR4 inhibition [116]. Together, these findings indicate that strengthened CXCL12–CXCR4 interactions increase the degree of hepatic homing of CD4 + T cells and contribute to liver inflammation in MASH. Thus, therapeutic targeting of this axis may represent a promising approach to ameliorate T-cell-driven inflammation and fibrosis, particularly in MASH patients with pronounced T-cell activation. A critical caveat in targeting the CXCL12–CXCR4 axis is its essential role in physiological homeostasis, including hematopoiesis and stem cell maintenance. Long-term inhibition raises concerns about compromised liver regeneration and systemic immune competence. Future research must therefore distinguish between the 'pathological' high-affinity signaling in MASH and the 'physiological' baseline signaling, potentially requiring allosteric modulators that dampen excessive activation without abolishing the axis entirely.

The CX3C chemokine family

CX3CL1

CX3CL1 (fractalkine) is produced mainly by HSCs and macrophages in the liver and signals through its receptor CX3CR1, which is expressed predominantly on macrophages and at low levels on HSCs and endothelial cells [117]. Hepatic CX3CL1 expression is markedly elevated in murine MASH models. Interestingly, unlike classical pro-inflammatory chemokines that drive injury, this upregulation appears to be a compensatory protective response. Bone marrow transplantation from CX3CR1-deficient mice into wild-type MASH recipients worsened metabolic and hepatic pathology, resulting in impaired glucose tolerance, enhanced liver inflammation, and accelerated fibrosis. In contrast, in vivo overexpression of CX3CL1 confers protection against MASH-related fibrosis [118].

In addition to the liver, the CX3CL1‒CX3CR1 axis plays a fundamental role in maintaining systemic metabolic homeostasis. Research has demonstrated that CX3CR1 deficiency exacerbates diet-induced obesity, adipose tissue inflammation, and systemic insulin resistance in mice [119]. These findings suggest that CX3CL1 signaling is essential for restraining the polarization of pro-inflammatory macrophages in visceral adipose tissue, thereby preserving insulin sensitivity and preventing the metabolic deterioration that drives MASH progression [119].

The interplay between CX3CL1 and CCL2 represents a critical bifurcation point in MASH immunity, determining whether the immune response resolves or progresses to fibrosis. This dichotomy operates at three levels: First, macrophage programming: while CCL2 engagement of CCR2 drives M1-dominant polarization and sustains a pro-inflammatory state via NF-κB activation, CX3CL1 acts as an 'immune checkpoint', fostering a restorative M2 phenotype and inhibiting the production of IL-1β and TNF-α [118]. Second, fibrotic regulation: CX3CL1 directly inhibits HSC activation, in contrast with the pro-fibrotic drive of CCL2 [118]. Third, metabolic impact: The CX3CL1–CX3CR1 axis improves systemic insulin sensitivity, directly countering the insulin-desensitizing effects of the CCL2–CCR2 axis. Consequently, CX3CL1 should be viewed not only as another chemokine but also as a compensatory feedback mechanism induced by metabolic stress. MASH progression, therefore, represents a tipping point where this protective 'brake' (CX3CL1) is overwhelmed by the pro-inflammatory 'accelerator' (CCL2). Consistent with this model, CCL2 knockout in CX3CR1-deficient mice rescues the phenotype [118], confirming that disease outcomes are shaped by the ratio of these antagonistic signals rather than the absolute level of any single molecule. A persistent blind spot in harnessing the CX3CL1–CX3CR1 axis is the functional dichotomy between its membrane-bound and soluble isoforms [120]. While soluble CX3CL1 acts as a chemoattractant, membrane-bound CX3CL1 functions as an adhesion molecule that promotes cell survival and retention [121]. Current therapeutic strategies that indiscriminately block CX3CR1 may inadvertently disrupt the protective, anti-apoptotic signals mediated by the membrane-bound form on hepatocytes or Kupffer cells [117]. Future investigations must therefore dissect the specific contributions of each isoform—potentially via ADAM10/17 metalloprotease regulation—to design precision therapies that preserve homeostatic adhesion while blocking pathogenic recruitment.

Atypical chemokine receptors (ACKRs)

While classical chemokine receptors drive inflammation, ACKRs serve as critical negative regulators in the MASH microenvironment by shaping chemokine gradients and dampening inflammatory signals. Unlike classical GPCRs, ACKRs (ACKR1–4 and CCRL2) do not couple to G proteins but instead function primarily as scavenger receptors or engage in β-arrestin-biased signaling to resolve inflammation [19].

CCRL2 (ACKR5) has emerged as a pivotal interface between immune regulation and systemic metabolism. In high-fat diet-induced obesity models, CCRL2 deficiency was shown to exacerbate insulin resistance and adipose tissue inflammation by increasing the infiltration of macrophages and promoting their polarization toward the pro-inflammatory M1 phenotype [122]. These findings suggest that CCRL2 acts as a protective metabolic checkpoint against the metabolic dysfunction that underpins MASH.

ACKR2 (also known as D6) functions as a scavenger for inflammatory CC chemokines, including CCL2, CCL5 and CXCL10 [123]. By internalizing and degrading these ligands, ACKR2 acts as a "molecular sink" to reduce their extracellular concentration, thereby limiting the excessive recruitment of monocytes and macrophages [124]. In the context of MASH, ACKR2 may play a pivotal role in preventing the transition from simple steatosis to overt steatohepatitis by rapidly clearing the surplus of inflammatory chemokines before they can trigger massive immune infiltration.

ACKR3 (CXCR7), a high-affinity receptor for CXCL12 and CXCL11, modulates signaling distinct from the classical CXCR4 pathway. ACKR3 signals exclusively through β-arrestin recruitment, influencing cell migration and survival [125]. By competing with CXCR4 for CXCL12 binding, ACKR3 can fine-tune the fibrotic response driven by hepatic stellate cells and the recruitment of immune cells, highlighting its potential as a therapeutic target that mechanistically uncouples fibrosis from inflammation [126].

Furthermore, ACKR4 exhibits a zonated expression pattern in the healthy liver, predominantly in liver sinusoidal endothelial cells, where it scavenges the homeostatic chemokines CCL19 and CCL21 [127]. This clearance mechanism is essential for maintaining hepatic immune zonation and preventing the formation of ectopic lymphoid structures, which are often associated with chronic liver inflammation.

Collectively, these findings underscore that ACKRs are not merely silent decoys but also active, essential components of the MASH microenvironment. They offer a unique therapeutic opportunity: rather than solely blocking pro-inflammatory receptors, strategies that increase ACKR scavenger function could actively promote the resolution of inflammation and restore hepatic homeostasis.

Chemokines as diagnostic and prognostic biomarkers in MASH

Liver biopsy remains the gold standard for diagnosing MASH, yet its invasive nature and associated risks limit its widespread clinical utility. Non-invasive markers often lack sufficient sensitivity, particularly in early disease stages, underscoring the urgent need for reliable biomarkers to facilitate screening and disease monitoring. Owing to their central roles in MASH pathogenesis, chemokines have therefore emerged as promising candidates for both diagnostic and prognostic applications (Table 2).

Table 2.

Chemokines as diagnostic and prognostic biomarkers for MASH

Chemokine	Participants and sample size	Sample types	Approach	Findings	Value	Refs.
CCL2	18 MASL, 36 MASH	PBMCs	qPCR	The expression level of CCL2 was positively correlated with the degree of ballooning of hepatocytes but not of steatosis or lobular inflammation	Diagnostic and predictive value	[39]
CCL2	14 Controls, 14 MASL, 18 MASH	Liver	Expression profiling by array	CCL2 was one of the hub genes	Diagnostic value	[40]
CCL2	5 Control Children, 35 MASH Children	Plasma	Luminex® assay	CCL2 was also lower in MASH (P = 0.04). CCL2 was higher in children with severe fibrosis (P = 0.008) with an area under the receiver operating characteristic curve (AUROC) of 0.76	Predictive value	[47]
CCL2	30 Controls, 32 MASL, 34 MASH	Serum	ELISA	CCL2 was significantly upregulated in MASH patients compared with MASL patients or control. Serum CCL2 was significantly correlated with the degree of hepatocytes ballooning (the diagnostic endpoint for MASH) without any significant correlation with steatosis or lobular inflammation. The ROC curve analysis of CCL2 for MASH diagnosis revealed an area under curve (AUROC) of 0.959 at cutoff ≥ 227 pg/ml	Diagnostic and predictive value	[43]
CCL2	250 MASLD	Serum	ELISA	Serum CCL2 levels were weakly associated with liver stiffness, but the association was no longer significant after accounting for age, diabetes, and BMI in a multivariable model	Predictive value	[37]
CCL2	10 Controls, 34 MASL, 41 MASH, 16 MASH with Fibrosis, 15 Cirrhosis	Serum	Meso scale discovery V-plex assays	CCL2 featured a clear correlation with cirrhosis	Predictive value	[55]
CCL2	15 MASH,7 without fibrosis, 8 with fibrosis	Visceral adipose	Targeted microarrays	CCL2 were differentially expressed in MASH with fibrosis	Predictive value	[131]
CCL2	16 controls, 48 MASH	Liver	730 immuno-oncology-related targets	CCL2 were significantly increased in MASH with advanced fibrosis compared to MASH with minimal fibrosis	Diagnostic and predictive value	[129]
CCL3	10 Controls, 34 MASL, 41 MASH, 16 MASH with Fibrosis, 15 Cirrhosis	Serum	Meso scale discovery V-plex assays	CCL3 was higher in MASH with fibrosis and featured a clear correlation with AST levels and cirrhosis	Diagnostic and predictive value	[55]
CCL3	4753 Controls, 4059 MASLD	Plasma or serum	ELISA	Concentrations of CCL3 in the MASH group was significantly higher than that in the control group (SMDs of 0.90)	Diagnostic value	[42]
CCL4	4753 Controls, 4059 MASLD	Plasma or serum	ELISA	Concentrations of CCL4 in the MASH group was significantly higher than that in the control group (SMDs of 2.05)	Diagnostic value	[42]
CCL4	15 MASH, 7 without fibrosis, 8 with fibrosis	Visceral adipose	Targeted microarrays	CCL4 were differentially expressed in MASH with fibrosis. CCL4 were found in MASH with T2DM as compared to MASH without T2DM	Predictive value	[131]
CCL5	64 controls, 109 MASL, 60 MASH	Serum	ELISA	CCL5 have been found to be significantly elevated in MASH patients compared to controls	Diagnostic value	[128]
CCL5	16 controls, 48 MASH	Liver	730 immuno-oncology-related targets	CCL5 were significantly increased in MASH with advanced fibrosis compared to MASH with minimal fibrosis	Diagnostic and predictive value	[129]
CCL11	8 Controls, 8 MASH	Liver	qPCR	CCL11 is upregulated in liver from MASH patients and shows positive correlations with serum ALT, TG, TC, and liver inflammation and fibrosis markers such as TNFA and COL1A1	Diagnostic and predictive value	[65]
CCL18	15 MASH, 7 without fibrosis, 8 with fibrosis	Visceral adipose	Targeted microarrays	CCL18 were differentially expressed in MASH with fibrosis	Predictive value	[131]
CCL20	4753 Controls, 4059 MASLD	Plasma or serum	ELISA-Systematic review	Concentrations of CCL20 in the MASH group was significantly higher than that in the control group (SMDs of 2.16). SUCRA probabilities showed that CCL20 had the highest rank in MASH for all chemokines	Diagnostic value	[42]
CCL20	12 transcriptome datasets	Liver	Whole-genome expression profiles-Robust rank aggregation method	CCL20 was one of the top 10 upregulated genes in MASH patients	Diagnostic value	[71]
CCL20	Liver: 35 Controls, 32 MASH fibrosis, serum:106 Controls, 77 MASH fibrosis	Liver and serum	qPCR and ELISA	CCL20 protein levels are increased in patients with MASH fibrosis	Diagnostic and predictive value	[69]
CCL20	21 Controls, 23 MASL, 17 MASH	Liver and serum	nCounter® Human Immunology Panel and ELISA	CCL20 was higher in the liver and serum of MASL and MASH	Diagnostic value	[112]
CXCL5	24 MASL, 53 MASH without fibrosis, 65 MASH with fibrosis	Liver	qPCR	CXCL5 expression is increased in MASH lobular inflammation and advanced fibrosis	Predictive value	[130]
CXCL8	14 Controls, 14 MASL, 18 MASH	Liver	Expression profiling by array	CXCL8 were identified as hub genes	Diagnostic value	[93]
CXCL8	10 Controls, 34 MASL, 41 MASH, 16 MASH with fibrosis, 15 Cirrhosis	Serum	Meso Scale Discovery V-plex assays	CXCL8 was higher in MASH and featured a clear correlation with AST levels and the cirrhosis	Diagnostic and predictive value	[55]
CXCL8	4753 Controls, 4059 MASLD	Plasma or serum	ELISA-systematic review	Concentrations of CXCL8 in the MASL group were significantly higher than that in the control group (SMDs of 1.95). Concentrations of CXCL8 in the MASH group was significantly higher than that in the control group (SMDs of 0.91). SUCRA probabilities showed that CXCL8 had the highest rank in MASL for all chemokines	Diagnostic value	[42]
CXCL8	15 MASH, 7 without fibrosis, 8 with fibrosis	Visceral adipose	Targeted microarrays	CXCL8 were found in MASH with T2DM as compared to MASH without T2DM	Predictive value	[131]
CXCL8	29 normal-weight women, 82 women with morbid obesity (subclassified: 29 normal liver, 32 simple steatosis, and 21 MASH)	Serum	ELISA	CXCL8 was significantly higher in morbid obesity with MASH than in normal-weight	Diagnostic value	[95]
CXCL9	318 adults with obesity (76 normal liver histology, 88 MASL, 72 MASH F0, 82 MASH F1-4)	Liver	NanoString Technologies nCounter assay	CXCL9 was higher in MASL and MASH and featured a clear correlation with fibrosis	Diagnostic and predictive value	[99]
CXCL9	21 Controls, 23 MASL, 17 MASH	Liver and serum	nCounter® Human Immunology Panel and ELISA	CXCL9 was higher in the liver of MASL and MASH	Diagnostic value	[112]
CXCL10	4753 Controls, 4059 MASLD	Plasma or serum	ELISA-Systematic review	Concentrations of CXCL10 in the MASH group was significantly higher than that in the control group (SMDs of 1.46)	Diagnostic value	[42]
CXCL10	12 transcriptome datasets	Liver	Whole-genome expression profiles-Robust rank aggregation method	CXCL10 was one of the top 10 upregulated genes in MASH patients	Diagnostic value	[71]
CXCL10	For MASLD, 58 MASLD and 60 healthy Controls; for MASH, 187 MASH liver biopsies and 154 healthy controls	Liver	Meta-analysis of GEO transcription data	CXCL10 was upregulated genes in MASLD and MASH patients	Diagnostic value	[111]
CXCL10	Liver:15 controls, 11 MASL, 11MASH; Serum: 73 Controls, 78 MASL, 69 MASH	Liver and serum	qPCR and ELISA	Circulating and hepatic CXCL10 levels were significantly higher in human MASH. The Circulating CXCL10 level was correlated with the degree of lobular inflammation and was an independent risk factor for MASH patients	Diagnostic and predictive value	[108]
CXCL10	21 Controls, 23 MASL, 17 MASH	Liver and serum	nCounter® Human Immunology Panel and ELISA	CXCL10 was higher in the liver and serum of MASL and MASH	Diagnostic value	[112]
CXCL11	21 Controls, 23 MASL, 17 MASH	Liver and serum	nCounter® Human Immunology Panel and ELISA	CXCL11 was higher in the liver of MASL and MASH	Diagnostic value	[112]

Current evidence supports the utility of chemokines across two distinct clinical dimensions: distinguishing disease states and staging fibrosis severity. First, regarding diagnostic discrimination, elevated circulating levels of pro-inflammatory chemokines—including CCL2, CCL3, CCL5, and CXCL8—consistently differentiate MASH patients from healthy controls. More granular distinctions have also been reported: CCL4 has shown utility in distinguishing simple steatosis (MASL) patients from healthy controls, whereas CCL11 and CCL5 are particularly valuable in differentiating active MASH from simple steatosis [128], reflecting the accrual of the inflammatory milieu during disease progression. Second, regarding prognostication and fibrosis staging, markers such as CXCL10 and CCL20 have emerged as superior indicators. Unlike general inflammatory markers, these chemokines correlate specifically with histological disease activity and fibrosis stage, supporting their utility in tracking disease progression. This finding is corroborated by tissue-based studies showing that the hepatic expression of CCR2 and CCR5 increases progressively with fibrosis stage [129], whereas CXCL5 [130] and CCL18 [131] expression in liver and adipose tissue, respectively, mirrors the fibrotic burden.

To avoid overinterpreting clinical readiness, a strict hierarchy of evidence must be established. Currently, chemokines can be categorized based on the robustness of their validation. Tier 1 (validated/robust) includes biomarkers such as CXCL10 and CCL2, whose correlations with hepatic inflammation and fibrosis have been reproduced across multiple independent, multicenter cohorts. Notably, composite panels incorporating these markers (e.g., the 'N3-MASH' model) have demonstrated consistent diagnostic performance in external validation cohorts [132]. However, even these top-tier markers face limitations regarding specificity owing to systemic inflammatory overlap. Tier 2 (Exploratory/Preliminary) comprises candidates such as CXCR4 and CCL20, which show high diagnostic potential in pilot studies but currently lack large-scale external validation. Given these constraints—specifically population variability and insufficient independent sensitivity—the field must pivot from identifying isolated associations to validating composite panels that integrate immune markers with metabolic indicators. Future translational efforts should focus on establishing standardized protocols for longitudinal monitoring and leveraging advances in genomics and machine learning to refine patient stratification. Ultimately, a nuanced approach that accounts for chemokine redundancy, pleiotropy, and network interactions will be essential to transform these biomarkers into reliable clinical tools for the early detection and personalized management of MASH.

Therapeutic targeting of chemokine pathways in MASH

Despite the strong preclinical rationale for targeting chemokines and their receptors, developing agents that target them with clinical success has proven to be difficult, resulting in a landscape of cautious optimism shaped by mechanistic complexity and clinical setbacks.

Clinical trials: lessons from targeted antagonism

Clinical investigations in this area remain limited (Table 3). The CCR5 antagonist leronlimab (PRO 140) showed promise in a phase 2 trial, demonstrating a dose-dependent reduction in hepatic steatosis as assessed using magnetic resonance imaging of the proton density fat fraction (MRI-PDFF). More extensive research has focused on the dual CCR2/CCR5 antagonist cenicriviroc (CVC). Initial phase 2 studies established its safety profile and indicated its antifibrotic potential [133], with one year of treatment leading to significant reductions in systemic inflammation and a twofold higher rate of NAS improvement than a placebo [134]; additionally, combination therapy with the farnesoid X receptor (FXR) agonist tropifexor further enhanced fibrosis and inflammation [135, 136]. However, the subsequent large phase 3 AURORA trial did not show significant improvement in liver fibrosis, although CVC did have a favorable safety profile [137].

Table 3.

Clinical trials targeting chemokines or chemokine receptors

Study title	NCT number registration date	Phase	Enrollment	Status
Efficacy and safety study of cenicriviroc for the treatment of nonalcoholic steatohepatitis (NASH) in adult participants with liver fibrosis	NCT02217475 2014-09-18	Phase II study	289	Completed
ORION: effects of cenicriviroc on insulin sensitivity in subjects with prediabetes or type 2 diabetes mellitus (T2DM) and suspected NAFLD	NCT02330549 2015-07-17	Phase 2a, randomized, double-blind, placebo-controlled, multicenter study	45	Completed
Rollover study of cenicriviroc for the treatment of liver fibrosis in participants with nonalcoholic steatohepatitis	NCT03059446 2017-02-14	Phase II, open-label rollover study	167	Terminated
Study of safety, tolerability, and efficacy of a combination treatment of LJN452 and CVC in adult patients with NASH and liver fibrosis	NCT03517540 2018-09-11	Phase II, randomized, double-blind, multicenter study	193	Completed
Leronlimab (PRO 140) in patients with nonalcoholic steatohepatitis (NASH)	NCT04521114 2020-12-01	Phase II, multicenter, two-part, three-arm, dose-ranging study	87	Completed
AURORA: a study for the efficacy and safety of cenicriviroc (CVC) for the treatment of liver fibrosis in adults with nonalcoholic steatohepatitis	NCT03028740 2017-04-05	Phase 3, multicenter, randomized, double-blind, placebo-controlled study	1778	Terminated

The failure of the phase 3 AURORA trial (Cenicriviroc) to meet its fibrosis endpoint represents a critical turning point [138], revealing the formidable challenges in targeting chemokine pathways. A primary driver of this failure is the fundamental misalignment between preclinical models and human pathophysiology [137]. While rodent models often rely on acute inflammatory stimuli (e.g., an MCD diet) driven by a single axis (such as CCR2/CCL2), human MASH involves chronic evolution characterized by high pathway redundancy. Consequently, the blockade of CCR2/CCR5 in humans likely triggers compensatory mechanisms—enabling alternative receptors (e.g., CCR1, CCR3) or recruitment pathways (e.g., neutrophils via CXCR1/2) to bypass the blockade—rendering insufficient monotherapy [7]. Furthermore, the trial design likely suffered from a temporal mismatch. Cenicriviroc acts primarily as an anti-inflammatory agent that targets monocyte recruitment [133]; however, it has been used in patients with established fibrosis (F2–F3), a stage where disease drivers may have shifted from active inflammation to autonomous fibrogenesis. Thus, targeting upstream inflammation at this advanced stage has proven to be “too little, too late,” highlighting the critical need to stratify future trials not only by fibrosis stage but also by inflammatory activity.

Emerging strategies: precision and combination

To overcome these translational barriers, future strategies are shifting toward precision medicine and rational combinations. First, addressing cell-specific complexity is crucial. While CVC promotes a restorative M2 macrophage phenotype in mice [139], the therapeutic potential of targeting CCR5 is complicated by its opposing role: CCR5 signaling constrains lipogenesis in hepatocytes but promotes inflammation in myeloid cells [63]. This context dependence explains the inconsistent net outcomes of systemic blockade. Consequently, refined approaches, such as nanoparticle-directed preferential delivery of CCR5 antagonists to myeloid cells, are being explored to harness anti-inflammatory benefits while preserving protective hepatocyte functions.

Second, combination therapies represent the most logical avenue to address pathway redundancy and the multifactorial nature of MASH. A promising example is the synergistic combination of a CCR2 inhibitor with a transforming growth factor-β (TGF-β) type I receptor kinase inhibitor (vactoserth). Recent studies have shown that this dual inhibition confers superior anti-fibrotic efficacy while counteracting the unintended exacerbation of hepatic lipid accumulation observed with TGF-β inhibition alone. Mechanistically, the CCR2 inhibitor component restores AMPK activation and inhibits lipogenic pathways (SREBP-1c, FAS), whereas the TGF-β inhibitor component potently suppresses HSC activation and SMAD2/3 signaling [140]. Similarly, pairing chemokine antagonists with metabolic modulators, such as FGF21 agonists [141] or GLP-1R agonists [142], offers a rational path to simultaneously target inflammatory infiltration, fibrogenic signaling, and core metabolic disturbances.

However, while scientifically logical, combination therapy faces formidable pharmacological and regulatory challenges. Pharmacologically, “stacking” immunomodulatory agents raises concerns about cumulative toxicity, particularly broad immunosuppression and increased susceptibility to infections, which may not be evident in short-term animal studies. Regulatory hurdles are equally significant. Developing combination regimens requires demonstrating the “contribution of components”—proving that the combination is superior to each individual agent—which necessitates complex, expensive factorial design trials with large sample sizes. Furthermore, determining the optimal dosing ratio to balance anti-inflammatory efficacy against metabolic side effects remains a complex clinical puzzle that limits the rapid translation of these combinations.

In summary, while chemokine receptor antagonists have shown potential, their translation has been hindered by biological redundancy and trial design limitations. Future success depends on moving beyond monotherapy toward “mechanistically stacked” combinations and adopting precision approaches that account for the spatiotemporal complexity of chemokine signaling.

Conclusions and future perspectives

This review delineates the evolving paradigm of chemokines in MASH, moving beyond their traditional definition as mere leukocyte attractants to establish them as central integrators of the immuno-metabolic interface. As we have discussed, key chemokines such as CCL2, CCL5, CCL20, and CXCL10 function as dual-purpose drivers: they not only orchestrate immune infiltration but also directly reprogram hepatocyte lipid metabolism, exacerbate systemic and hepatic insulin resistance, and impair mitochondrial function, creating a self-perpetuating cycle of injury.

Despite this compelling biological rationale, clinical translation has been hampered by the failure of monotherapies (e.g., in the AURORA trial), exposing the formidable challenges posed by pathway redundancy and spatiotemporal pleiotropy. To bridge this translational gap, the field must pivot toward a more nuanced, precision-medicine approach. Future success will hinge on four strategic pillars: (1) Precision stratification: Clinical trials must move beyond “one-size-fits-all” designs. Future studies should stratify patients not only by fibrosis stage but also by inflammatory endotypes (using biomarkers such as tier 1 validated chemokines) and sex-specific drivers (e.g., sexual dimorphism in CCL2/CXCL8 expression), ensuring that immune-targeted therapies are deployed in the right patient at the right time. (2) Rational combination: Given the high redundancy of chemokine networks, “stacking” therapies are essential. Co-targeting inflammatory hubs (e.g., CCR2/CCR5) alongside core metabolic modulators (e.g., FGF21, GLP-1R agonists, or TGF-β inhibitors) offers a rational path to simultaneously disrupt the fibrotic cycle and restore insulin sensitivity, thereby resolving root metabolic defects. (3) The gut‒liver axis frontier: Determining how the microbiome instructs hepatic immunity is critical. Future research should dissect how specific microbial metabolites (e.g., secondary bile acids, SCFAs) differentially modulate the hepatic chemokine landscape, offering new targets for “microbiome-informed” interventions that stop inflammation at its source. (4) Harnessing regulatory checkpoints: The therapeutic potential of ACKRs remains an untapped frontier. Activating these “silent” scavengers offers a unique opportunity to actively resolve inflammation by clearing excess chemokines without the risks of broad immunosuppression seen with receptor blockade.

In conclusion, while the path forward is complex, the potential rewards are immense. By embracing the complexity of chemokine networks and adopting these multidimensional strategies, the field is poised to overcome current barriers and deliver the next generation of disease-modifying therapies for MASH.

Abbreviations

MASLD

Metabolic dysfunction-associated steatotic liver disease

NAFLD

Non-alcoholic fatty liver disease

TG

Triglycerides

HDL

High-density lipoprotein

MASL

Metabolic dysfunction-associated steatotic liver

MASH

Metabolic dysfunction-associated steatohepatitis

NASH

Non-alcoholic steatohepatitis

HSC

Hepatic stellate cell

GPCRs

G protein-coupled receptors

ACKRs

Atypical chemokine receptors

cAMP

Cyclic adenosine monophosphate

PKA

Protein kinase A

PLC-β

Phospholipase C-beta

IP3

Inositol-1,4,5-trisphosphate

PI3K

Phosphatidylinositol 3-kinase

GRK

GPCR kinase

MAPK

Mitogen-activated protein kinase

JNK

C-Jun N-terminal kinase

ERK1/2

Extracellular signal-regulated kinase 1 and 2

JAK

Janus kinase

STAT

Signal transducers and activators of transcription

LSECs

Liver sinusoidal endothelial cells

MCD

Methionine‒choline-deficient

HFD

High-fat diet

RIP3

Receptor-interacting kinase 3

SHP

Src homology region 2 domain-containing phosphatase

NF-κB

Nuclear factor kappa B

TLR4

Toll-like receptor 4

HDAC

Histone deacetylase

IVA-PLA2

Group IVA phospholipase A2

NAS

NAFLD activity score

FFC

Fat-, fructose- and cholesterol-rich

NK

Natural killer

HFHC

High-fat high-cholesterol

TRIF

TIR-domain-containing adapter-inducing interferon-β

MyD88

Myeloid differentiation primary response 88

OSR1

Odd-skipped related 1

DIAMOND

Diet-induced animal model of nonalcoholic fatty liver disease

IL

Interleukin

FFA

Free fatty acid

C/EBP-β

CCAAT/enhancer-binding protein β

g-MDSCs

Granulocytic myeloid-derived suppressor cells

IRF1

Interferon regulatory factor 1

TNF-α

Tumor necrosis factor α

COL1A1

Collagen type 1 alpha 1 chain

HPCs

Hepatic progenitor cells

OLR1

Oxidized low-density lipoprotein receptor 1

SREBPs

Sterol regulatory element-binding proteins

SIRT1

Sirtuin 1

TECK

Thymus-expressed chemokine

ASK1

Apoptosis signal-regulating kinase 1

MPO

Myeloperoxidase

ABAH

4-Aminobenzoic acid hydrazide

TSPO

Translocator protein

Atriol

3,17,19-Androsten-5-triol

GM-CSF

Granulocyte-macrophage colony-stimulating factor

Tregs

Regulatory T cells

Th17 cells

T helper 17 cells

MLK3

Mixed lineage kinase 3

NKT cells

Natural killer T cells

MRI-PDFF

Magnetic resonance imaging-proton density fat fraction

CVC

Cenicriviroc

FXR

Farnesoid X receptor

TGF-β

Transforming growth factor-β

FGF21

Fibroblast growth factor 21

Author contributions

Min Yin: conceptualization, funding acquisition, writing—original draft, writing—review and editing. Xia Li: conceptualization, funding acquisition, writing—review and editing, supervision. Shanshan Liu: conceptualization, funding acquisition, writing—review and editing, supervision. Yan Zhang: visualization.

Funding

This work was supported by the National Key R&D Program of China to Xia Li (grant no. 2022YFC2010102), the National Natural Science Foundation of China to Shanshan Liu (grant no. 82322002), the National Science Foundation of Hunan Province for Excellent Young Scholars to Shanshan Liu (grant no. 2023JJ20084), and the Natural Science Foundation of Hunan Province to Min Yin (grant no. 2025JJ60688).

Data availability

Data sharing not applicable to this article as no datasets were generated or analyzed during the current study. All information is derived from publicly available articles and datasets.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.