Immune Pathways in Doxorubicin Cardiotoxicity: A Cardio-Immunology Perspective

Abstract

Anthracyclines such as doxorubicin remain central to cancer therapy, but their clinical utility is constrained by dose-limiting cardiotoxicity and long-term cardiovascular sequelae. Although traditionally attributed to cardiomyocyte-intrinsic mechanisms, including mitochondrial dysfunction, oxidative stress, and DNA damage, emerging evidence demonstrates that these initial injuries rapidly activate the immune system, transforming doxorubicin-induced cardiotoxicity (DIC) into a multicellular inflammatory process. Release of mitochondrial and nuclear danger signals triggers innate immune pathways and recruitment of neutrophils, monocytes, and lymphocytes, whose sustained activation promotes maladaptive remodeling, fibrosis, and chronic dysfunction. Conversely, specific immune subsets exert context-dependent cardioprotective effects, underscoring the dual role of immune responses in disease progression. This review frames DIC within a cardioimmunology paradigm, highlighting the intersection of mitochondrial stress, sterile inflammation, and adaptive immunity across acute and chronic phases of injury. We discuss emerging therapeutic strategies that extend beyond cardiomyocyte protection, including immune recalibration rather than broad immunosuppression, immune-targeted interventions, and biomarker-guided monitoring, to enable mechanism-based, individualized cardioprotection without compromising anticancer efficacy.

Central Illustration

Highlights

• •Doxorubicin-induced cardiotoxicity (DIC) limits anthracycline use.
• •DIC extends beyond cardiomyocyte injury and involves innate and adaptive immunity.
• •Immune cells can be both pathogenic and cardioprotective during DIC progression.
• •Immune recalibration and biomarker monitoring may enable targeted cardioprotection.

Cancer affects millions of individuals worldwide and remains the second-leading cause of death in the United States,^1,2 although advancements in treatment strategies, ranging from traditional chemotherapies to emerging therapeutic modalities, have substantially improved survival rates. Among anticancer therapies, anthracyclines, particularly doxorubicin (DOX), have long been a cornerstone of chemotherapy.³ However, despite their broad efficacy across multiple malignancies, their clinical use is limited by dose-dependent toxicities, most notably cardiotoxicity, which may persist or manifest even years after treatment completion.

With more than 18 million cancer survivors in the United States alone, the long-term cardiovascular consequences of cancer treatment have become a major public health concern.⁴ The clinical burden of anthracycline-related cardiotoxicity is substantial: The incidence of heart failure increases from approximately 5% at cumulative DOX doses of 400 mg/m² to nearly 48% at 700 mg/m², with no clearly defined safe threshold. The 30-year cumulative incidence of heart failure among patients exposed to high anthracycline doses reaches 7.2%, corresponding to a 7-fold excess risk compared with unexposed survivors.^4,5 Accordingly, in populations with prolonged survival after anthracycline-based treatment, such as breast cancer survivors, cardiovascular disease has emerged as the leading competing cause of mortality, surpassing cancer recurrence, particularly in older patients.⁵

Individual susceptibility to DOX-induced cardiotoxicity (DIC) is influenced by multiple clinical factors, including cumulative anthracycline dose, older age at treatment, preexisting cardiac dysfunction, exposure to additional cardiotoxic therapies such as HER2-targeted agents or mediastinal radiotherapy. Cardiovascular comorbidities, such as hypertension, diabetes, dyslipidemia, and obesity, further increase risk.^5,6 The marked interindividual variability in cardiac outcomes, which cannot be fully explained by cumulative dose alone, underscores the need for a deeper mechanistic understanding of DIC and the development of effective preventive strategies to mitigate its long-term sequelae.⁷

For decades, DIC has been interpreted primarily through a cardiomyocyte-centered lens. One of the most well-established mechanisms involves the inhibition of topoisomerase IIβ (Top2β), the isoform predominantly expressed in quiescent cardiomyocytes, which results in DNA double-strand breaks, suppression of key transcriptional regulators of mitochondrial biogenesis, such as PGC1α and PGC1β, and activation of downstream stress-signaling cascades including ERK pathways.8, 9, 10 In parallel, DOX accumulation in mitochondria, oxidative stress, and iron dysregulation contribute to mitochondrial dysfunction, leading to progressive energetic failure and cardiomyocyte loss.11, 12, 13

However, emerging evidence suggests that DIC is not solely a consequence of direct cardiomyocyte injury but reflects a more complex and systemic pathophysiology. The heart actively responds to injury through a network of adaptive and maladaptive cellular interactions that shape disease progression. In this context, immune activation has gained recognition as a critical amplifier of cardiac damage. DOX-induced cellular stress and mitochondrial damage trigger the release of damage-associated molecular patterns (DAMPs), initiating an innate immune response that may perpetuate injury and contribute to long-term cardiac remodeling.^14,15

Despite these advances, the mechanisms by which immune responses influence the onset, persistence, and progression of DIC remain incompletely understood. The following sections will examine the evolving understanding of DIC, from early clinical observations to current mechanistic and immunological insights, with particular emphasis on the emerging role of the immune system in modulating cardiac outcomes. By integrating these perspectives, this review aims to highlight how advancing knowledge may inform the development of future cardioprotective strategies targeting both immune and nonimmune cardiac cell populations in the context of DOX therapy.

Doxorubicin-Induced Cardiotoxicity: Clinical Course, Mechanisms, and Therapeutic Perspectives

Cancer therapy-related cardiovascular toxicity is a major limitation of anthracycline chemotherapy, influencing both immediate cancer outcomes and long-term cardiovascular health. Among anthracyclines, DOX is the most widely used and best studied agent, and its cardiac toxicity has become a paradigm for understanding the interplay between cancer therapies and cardiovascular disease. Understanding the origins of this toxicity has been essential for management and prevention. Early clinical observations distinguished acute and chronic forms of DIC.^16,17 Acute toxicity, occurring within 2 weeks from treatment, typically presents with transient ventricular dysfunction or arrhythmias and was historically considered reversible.¹⁸ In contrast, chronic toxicity, manifesting within the first year or decades later, has been regarded as irreversible.^9,16,17 This classification, derived mainly from childhood cancer survivor cohorts, provided the first clinical framework for interpreting the long-term effects of anthracyclines.¹⁸ Subsequent evidence reframed DIC as a continuous process initiated at first exposure, with early biomarkers such as troponin indicating subclinical injury. Acute and chronic manifestations are now recognized as stages of a single continuum, emphasizing the need for early detection and prevention.17, 18, 19

Mechanistic studies have revealed the multifactorial nature of DIC. DOX interacts with Top2β, leading to DNA damage and transcriptional dysregulation, while impairing mitochondrial function, disrupting the electron transport chain, and increasing reactive oxygen species (ROS) production.^8,20,21 These insults activate inflammatory cascades, including nuclear factor-κB activation, amplifying proinflammatory signaling.²² Together, oxidative stress, inflammation, and DNA damage drive cardiomyocyte death and progressive dysfunction.¹⁰ In addition, DOX induces long-lasting epigenetic modifications, including altered DNA methylation and hydroxymethylation, which reprogram gene networks governing mitochondrial homeostasis, oxidative stress, and inflammation. This “epigenetic memory” may predispose cardiomyocytes to dysfunction long after the initial exposure.^23,24

These mechanistic insights have guided therapeutic development in recent years. Dexrazoxane remains the only cardioprotective agent approved by the U.S. Food and Drug Administration. Although its activity was initially attributed to iron chelation, its efficacy is also thought to be from Top2β inhibition, a mechanism that has spurred the development of selective Top2β inhibitors as potential alternatives.^17,25,26 Nevertheless, its clinical practice use is largely confined to selected high-risk settings given still-limited evidence of benefit and historical, though increasingly debated, concerns regarding safety and potential interference with anticancer efficacy.27, 28, 29 Neurohormonal antagonists, such as beta-blockers and angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs), have also demonstrated benefit in selected contexts.30, 31, 32, 33 In breast cancer patients, trimetazidine has been associated with improved ejection fraction, while combinations of ACEIs/ARBs and beta-blockers have improved global longitudinal strain.^30,34, 35, 36, 37 Nonetheless, evidence remains heterogeneous, and their effectiveness in preventing cardiotoxicity and disease progression is inconsistent.³⁸

A major limitation of current strategies is their predominant focus on protecting cardiomyocytes, without adequately addressing alterations in other cardiac cell types. Immune cells, in particular, are likely key contributors to DIC pathogenesis, especially given the well-established capacity of DOX to induce immunogenic cell death, leading to the release of proinflammatory signals that amplify immune activation and perpetuate cardiac injury over time.^23,24 Although historically under-recognized, recent studies have begun to define the contributions of specific immune cell populations, identifying neutrophils and neutrophil elastase as key mediators of cardiac damage,³⁹ or uncovering a pathogenic CD8⁺ T cell response driving cardiac fibrosis and systolic dysfunction.⁴⁰ Despite these advances, a unified framework explaining how DOX reshapes the cardiac immune landscape is still lacking. Elucidating the interactions between immune cells and resident cardiac populations, including cardiomyocytes, fibroblasts, and endothelial cells, will be critical for developing next-generation cardioprotective strategies that address the full cellular complexity of DIC.

Immune System Activation as a Central Driver of Doxorubicin-Induced Damage Within the Heart

Innate immune activation

A central question in DIC is how early myocardial injury progresses to overt, and often delayed, cardiac dysfunction. While canonical mechanisms, such as oxidative stress, Top2β modulation, and mitochondrial dysfunction, are central to the initial insult, they do not fully explain the marked heterogeneity in long-term cardiac outcomes among patients exposed to similar cumulative doses, nor the progression of cardiotoxicity years after treatment completion.^7,9,10 Notably, adverse remodeling can occur even in the absence of significant cardiomyocyte loss, implicating secondary processes, particularly immune-mediated mechanisms, in disease progression.^41,42 Indeed, DOX-induced cellular stress can trigger immunogenic signaling, as mitochondrial damage and redox imbalance lead to the release of DAMPs, including mitochondrial DNA and oxidized proteins, which activate innate immune sensors and drive sterile inflammation.^6,24 The magnitude and persistence of this response are shaped by patient-specific factors including age, sex, comorbidities, genetics, drugs, and prior immune history,43, 44, 45, 46 many of which converge on the concept of immune fitness, defined as the ability to mount a proportionate and self-limiting response to tissue injury.⁴⁷ Impaired immune fitness, as observed in aging or metabolic disease, can modulate susceptibility to DIC. Age-related immunosenescence compromises the resolution of inflammation and favors persistent proinflammatory macrophage polarization.48, 49, 50 In parallel, metabolic comorbidities such as obesity and diabetes can establish a state of chronic low-grade immune activation, lowering the threshold for DOX-triggered inflammation.51, 52, 53 Additionally, sex-dependent hormonal regulation of innate and adaptive immunity may influence the severity of cardiotoxic responses.^54,55 Finally, although genetic variants associated with interindividual susceptibility to DIC predominantly involve pathways related to drug transport, metabolism, oxidative stress, and DNA damage response rather than classic immune signaling,⁵⁶ some genes intersect with immune regulation. For example, variants in RAC2 and CYBA, which modulate NADPH oxidase activity and ROS production, can also influence immune cell function. These observations suggest that genetically determined differences in immune-redox balance may contribute to variability in cardiac susceptibility by shaping immune fitness and the inflammatory response to injury. Thus, variability in immune regulation, rather than anthracycline dose alone, likely underlies the divergent clinical trajectories of DIC, positioning cardiomyocyte injury as the initiating event of a broader immune-driven cascade (Central Illustration).

Central Illustration.

Innate and Adaptive Immune Responses as Drivers of DOX-Induced Cardiac Injury

DOX-induced cardiomyocyte stress triggers DAMP release, activating innate immune sensors such as TLR9 and the NLRP3 inflammasome, promoting a pro-inflammatory cytokine cascade with recruitment of innate immune cells, endothelial activation, and fibroblast reprogramming. Adaptive responses involving cytotoxic CD8⁺ T cells and B cells amplify cardiac injury, while CD4⁺ regulatory T cells and iNKT cells exert opposing cardioprotective effects. While initially reversible and potentially physiological, sustained and deregulated activation drives irreversible myocardial remodeling, with patient-specific factors shaping its magnitude. Several mediators within these pathways represent potential therapeutic targets, including IFN-γ, IL-1β, CD8⁺ T cells and monocyte recruitment. DAMPs = damage-associated molecular patterns; DOX = doxorubicin; ECM = extracellular matrix; FcγRIIB = Fc gamma receptor IIB; ICAM-1 = intercellular adhesion molecule-1; IFN-γ = interferon gamma; IL = interleukin; iNKT = invariant natural killer T cells; NETs = neutrophil extracellular traps; NLRP3 = NOD-like receptor protein 3; ROS = reactive oxygen species; SLAMF7 = signaling lymphocytic activation molecule family member 7; SR-A1 = scavenger receptor A1; TNF-α = tumor necrosis factor alpha; TLR = Toll-like receptor; TRPA1 = transient receptor potential ankyrin 1.

At the molecular level, DOX-induced sterile inflammation is driven by DAMPs released from injured cardiomyocytes and fibroblasts,^57,58 which engage pattern recognition receptors, including Toll-like receptors (TLRs) and the NLRP3 inflammasome, expressed by both immune cells and resident cardiac cells, such as cardiomyocytes and endothelial cells.^59,60 Activation of these innate sensors induces the release of proinflammatory cytokines and chemokines, among them TNF-α, IL-1β, IL-6, CCL2, CXCL9, and CXCL10, creating a chemotactic gradient that orchestrates the recruitment of immune cells to the myocardium, amplifying and perpetuating inflammation.61, 62, 63 Experimental models demonstrate that these early signals are sufficient to induce cardiac remodeling and dysfunction, even in the absence of significant cardiomyocyte death.^41,42,64 For example, in preclinical murine models, low-dose DOX, at levels insufficient to induce cardiomyocyte apoptosis, can promote perivascular reactive fibrosis through TLR9 activation by DOX-induced mitochondrial DAMPs. This process triggers IL-1β secretion, driving fibroblast activation and collagen deposition via the SAPK/JNK signaling pathway. Similar findings in human cardiac fibroblasts support the translational relevance of this mechanism.⁴¹ Furthermore, experimental evidence indicates that NLRP3 inflammasome activation alone is sufficient to drive cardiac fibrosis. In a murine model with fibroblast-restricted NLRP3 gain-of-function, increased IL-1β and IL-18 production led to marked collagen deposition in both atria and ventricles, demonstrating that innate immune-derived cytokines can act as direct fibrogenic drivers in the myocardium.⁶⁵ At the translational level, single-nucleus RNA sequencing of left ventricular tissue from patients with end-stage DIC at the time of transplantation revealed a significantly expanded population of periostin (POSTN⁺)-activated fibroblasts compared with both nonfailing donors and patients with nonischemic cardiomyopathy. These findings support the concept that immune-driven fibroblast activation and cardiac remodeling represent a persistent signature of DOX cardiotoxicity, lasting years after chemotherapy exposure.⁶⁶ Together, these findings support a paradigm in which inflammation is not merely secondary but a central driver of DIC, analogous to other forms of sterile cardiac injury.67, 68, 69

Neutrophils

Within this cardioimmuno framework, neutrophils are among the earliest responders to cardiac injury, and their rapid activation plays a central role in amplifying tissue damage.^69,70 Following DOX exposure, marked neutrophil infiltration occurs in the myocardium, accompanied by upregulation of S100A8/A9 and increased circulating levels of neutrophil-associated markers such as myeloperoxidase (MPO), PGLYRP1, and CEACAM8, findings consistently observed in both preclinical models and cancer survivors.71, 72, 73 Notably, S100A8/A9, released by activated neutrophils and monocytes, act as DAMPs that amplify inflammatory signaling through receptors such as TLR4 and RAGE, thereby propagating innate immune activation and tissue injury.⁷⁴ Functionally, neutrophils contribute to cardiac injury through the release of ROS, proteolytic enzymes, and inflammatory mediators that degrade the extracellular matrix, damage endothelial cells, and impair cardiomyocyte viability. Mechanistically, neutrophil-derived MPO activates the p38-MAPK pathway, promoting apoptosis and exacerbating inflammation.⁷² Consistently, genetic or pharmacologic neutrophil depletion (eg, anti-Ly6G antibodies) attenuates myocardial injury and reduces chemokine expression, including CXCL1 and IL-8, supporting a direct pathogenic role in DIC.³⁹ Beyond these canonical roles, neutrophils also contribute to DIC through the formation of neutrophil extracellular traps (NETs). Elevated circulating levels of NET DNA have been detected in lymphoma patients with DOX-related cardiac dysfunction, while preclinical studies show that DOX stimulates HMGB1-dependent NET formation in cardiac tissue. These NETs are sensed by the transmembrane receptor Coiled-Coil Domain Containing 25 (CCDC25) on cardiomyocytes, triggering intracellular ROS production and autophagic flux, ultimately impairing contractility. Importantly, both genetic and pharmacologic targeting of CCDC25 alleviates cardiac injury without compromising the anticancer efficacy of DOX, highlighting a novel immunomodulatory approach with dual therapeutic benefit.^75,76

Monocytes and macrophages

As the inflammatory response progresses, monocytes are recruited to the injured myocardium. A key mediator of this process is intercellular adhesion molecule-1 (ICAM-1), which is rapidly upregulated on cardiac endothelial cells in response to IL-1β and IL-6 generated during DOX-induced sterile inflammation. Endothelial ICAM-1 facilitates the transendothelial migration of both proinflammatory Ly6C^high monocytes and T lymphocytes into the myocardium, the former through interaction with lymphocyte function-associated antigen-1 (LFA-1), thereby linking innate cytokine signaling to myeloid cell infiltration.^77,78 This process is self-reinforcing: Once recruited, monocyte-derived macrophages release TNF-α and other cytokines that further upregulate ICAM-1 on endothelial cells and cardiac fibroblasts. In turn, activated fibroblasts secrete chemokines like macrophage inflammatory protein-1α (MIP-1α), sustaining monocyte recruitment and amplifying myocardial injury.⁷⁹ Once in the myocardium, monocyte differentiate into macrophages with high functional plasticity. Under anthracycline stress, macrophage polarization is skewed toward proinflammatory programs, with suppression of reparative M2-like phenotypes in a time- and dose-dependent manner.⁶³ This imbalance impairs resolution of inflammation and promotes persistent injury. For instance, IL-27p28 deficiency in mice enhances M1-like polarization, limits M2-like differentiation, and increases cardiomyocyte apoptosis, effects reversed by adoptive transfer of wild-type monocytes.⁸⁰ This proinflammatory milieu promotes fibrogenesis. In murine models, a shift toward proinflammatory macrophage dominance in DOX-treated hearts is associated with increased interstitial fibrosis and ROS accumulation, linking innate immune polarization to myocardial collagen deposition.⁸¹ Accordingly, DOX-induced innate immune activation has been shown to contribute directly to cardiac fibrosis, in concert with NLRP3-derived cytokines, reinforcing its central role in adverse remodeling in DIC.^66,81,82

In contrast, resident cardiac macrophages, which are self-renewing, exert protective effects in DOX-induced cardiac dysfunction. In murine models, the SR-A1-c-Myc signaling axis governs the proliferation and maintenance of this reparative macrophage pool. Disruption of either SR-A1 or c-Myc impairs macrophage renewal, exacerbates inflammation, and worsens cardiac dysfunction, emphasizing the importance of maintaining reparative macrophage populations in DIC.⁸³ Further insight into macrophage regulation is provided by studies on Signaling Lymphocytic Activation Molecule Family member 7 (SLAMF7), an inhibitory receptor that mitigate M1-like activation in the injured heart. In preclinical murine models of DIC, DOX significantly downregulates SLAMF7 expression in cardiac macrophages, and its genetic deletion, both global and macrophage-specific, aggravates disease severity, leading to worsened systolic dysfunction, increased myocardial fibrosis, enhanced ROS accumulation, and elevated circulating levels of TNF-α, IL-1β, and IL-6. Mechanistically, SLAMF7 exerts its protective effects by interacting with TRAF6 to suppress downstream NF-κB signaling, thereby restraining proinflammatory macrophage polarization and fibrogenic cytokine production. Consistently, restoration of SLAMF7 signaling through recombinant protein administration reduces proinflammatory macrophage infiltration, attenuates collagen deposition, and improves cardiac function in DOX-treated mice, demonstrating that targeting innate immune regulatory checkpoints in macrophages can mitigate fibrotic remodeling in DIC.⁸¹ Overall, these findings highlight macrophage polarization as a central immunoregulatory node and a promising therapeutic target in DIC. Notably, the molecular determinants of macrophage polarization extend beyond receptor-mediated signaling to include intracellular redox-sensitive pathways.⁸⁴ Preclinical studies show that TRPA1 deficiency exacerbates apoptosis, inflammation, and functional decline in DOX-treated hearts, supporting a cardioprotective role through modulation of redox-immune crosstalk.⁸⁵

Collectively, these findings identify innate immune activation as a central driver of DOX-induced cardiac injury. DAMP-mediated signaling links early cardiomyocyte stress to sustained inflammation, immune cell recruitment, and fibroblast activation, ultimately promoting adverse remodeling. Thus, the balance between proinflammatory and reparative immune responses emerges as a key determinant of disease progression, highlighting innate immunity as a critical mechanistic axis in DIC.

Adaptive immune responses

Beyond innate immunity, adaptive immune responses are increasingly recognized as key contributors to DIC. Preclinical studies reveal that DOX promotes myocardial infiltration by CD8⁺ cytotoxic T cells characterized by granzyme B expression and IFNγ production.⁴⁰ Mechanistically, DOX selectively upregulates ICAM-1 on cardiac fibroblasts, enabling LFA-1–dependent CD8⁺ T cell adhesion and contact-dependent degranulation. Granzyme B released upon this interaction directly promotes fibroblast-to-myofibroblast transformation in a dose-dependent manner, increasing collagen I, collagen III, and αSMA expression, and identifying cardiac fibroblasts as both targets and amplifiers of cytotoxic T cell activity. Notably, this T cell–mediated injury is temporally dissociated from the direct cytotoxic effects of DOX: T cell–deficient Tcra^−/− mice exhibit similar early cardiomyocyte death as wild-type animals but are protected from chronic fibrosis and late dysfunction, indicating that CD8⁺ T cells amplify rather than initiate cardiac damage. Consistently, CD8⁺ T cell depletion is protective, whereas CD4⁺ T cell depletion worsens injury, likely reflecting loss of Foxp3⁺Helios⁺ regulatory T cells that restrain cytotoxic responses. In patients, circulating IFNγ⁺CXCR3⁺CD8⁺ T cells expand after anthracycline treatment, and plasma levels of the CXCR3 ligands CXCL9 and CXCL10 correlate with systolic decline, implicating a potentially targetable chemokine axis. However, these findings are limited by small cohort size and the lack of identified cardiac autoantigens. Their consistency across species, including canine and human models, nonetheless supports the translational relevance of T cell–mediated cardiac injury.⁴⁰

Beyond this initial DOX-driven ICAM-1-dependent interaction, a broader amplification loop sustains inflammation once lymphocytes have infiltrated the myocardium. Activated cardiac fibroblasts produce chemokines that promote leukocyte retention within the myocardium and upregulate both ICAM-1 and VCAM-1 via CD40-CD40L signaling, reinforcing the bidirectional crosstalk with infiltrating lymphocytes.^79,86 Concurrently, endothelial cells respond to DOX-induced DNA damage via activation of the cGAS-STING pathway, resulting in the production of proinflammatory cytokines and enhanced leukocytes recruitment.^87,88 Together, these processes establish a self-perpetuating inflammatory circuit that sustains immune activation and promotes myocardial senescence.⁸⁹

In contrast to cytotoxic lymphocytes, invariant natural killer T (iNKT) cells exert cardioprotective effects. Their activation limits cardiomyocyte damage via the IFNγ-STAT1-ERK signaling axis. Accordingly, iNKT-deficient mice show worsened cardiac function, reduced ERK phosphorylation, and impaired mitochondrial homeostasis after DOX exposure. Conversely, restoration of IFNγ signaling rescues these defects, confirming an unexpected protective role for this unconventional lymphocyte population in regulating inflammation and preserving cardiac integrity.⁹⁰

B cells are increasingly recognized as additional key contributors to DIC, promoting cardiac injury through antibody deposition and proinflammatory cytokine production. In preclinical models, B cell depletion attenuates DOX-induced cardiac dysfunction, apoptosis, and fibrosis, highlighting their pathogenic role. Importantly, exercise modulates this response by upregulating the inhibitory receptor FcγRIIB on B cells, thereby raising their activation threshold and reducing autoantibody deposition and inflammatory signaling. Accordingly, adoptive transfer of exercise-conditioned B cells into B cell–deficient mice confers significant cardioprotection, whereas transfer of FcγRIIB-deficient B cells abrogates this effect. These findings identify B cell regulation as a novel immunomodulatory mechanism underlying exercise-induced cardioprotection and highlight the therapeutic potential of targeting B cell–dependent pathways.⁹¹

Taken together, these observations reveal that adaptive immune contributions to DIC are functionally heterogeneous, with CD8⁺ cytotoxic T cells and B cells that promote fibrosis and cardiac dysfunction, while Treg and iNKT exert counter-regulatory, cardioprotective effects. Thus, disease progression is determined not by immune activation per se, but by the balance among these distinct subsets. Importantly, these immune-mediated processes are temporally dissociated from the direct cytotoxic effects of DOX and are sustained by amplification mechanisms such as fibroblast-immune crosstalk, extending beyond the period of drug exposure. This subset-level specificity represents an underexplored dimension of DIC pathophysiology that current cardioprotective strategies have yet to address. Advances in single-cell and transcriptomic technologies are now beginning to resolve this complexity,92, 93, 94 providing a foundation for the development of more precise, targeted immunomodulatory approaches in cardio-oncology.

Therapeutic Modulation of Immune Responses in Doxorubicin-Induced Cardiotoxicity

Understanding contribution of the immune system to DIC is still at an early stage. However, it is increasingly recognized that immune activation plays a central role and that the immune system exerts complex, multidimensional effects: While immune responses can drive tissue injury, they are also critical for tumor surveillance and tissue repair. This duality creates a therapeutic challenge, demanding strategies that selectively attenuate harmful immune activation while safeguarding the protective mechanisms involved in antitumor immunity and cardiac recovery. Addressing this challenge will require moving beyond broad immunosuppression toward approaches based on immune recalibration, selectively modulating immune responses and delivering interventions at the most appropriate stage of disease progression.

Selectivity may be achieved adapting therapeutic approaches already explored in other immune-mediated disorders to the context of DIC. For example, IFNγ neutralization with emapalumab has been shown to attenuate CD8⁺ T cell–driven injury in hemophagocytic lymphohistiocytosis, a rare syndrome characterized by severe immune dysregulation and hyperinflammation.⁹⁵ In parallel, emerging preclinical studies on anti-CD8 monoclonal antibodies suggest a potential paradigm shift in cardiovascular immunotherapy⁹⁶ with possible implications for DIC. Similarly, IL-1β modulation has been associated with improved cardiovascular outcomes⁹⁷ and may even enhance antitumor activity,⁹⁸ making this pathway particularly attractive in patients receiving doxorubicin-based chemotherapy. Given the established role of macrophages and recruited monocytes in cardiac remodeling under stress⁶⁸ and after DOX exposure, CCR2 inhibition could limit monocyte infiltration into the heart,⁹⁹ while macrophage reprogramming strategies could mitigate their proinflammatory effects.¹⁰⁰

Timing is likely to be equally critical, as the immune landscape in DIC evolves dynamically from acute injury responses to chronic adaptive immune activation. Supporting this concept, a recent mouse model of DIC demonstrated that exercise-induced upregulation of the inhibitory receptor FcγRIIB on B cells increased their activation threshold, reduced pathogenic antibody deposition, and attenuated inflammatory cytokine release during subsequent doxorubicin exposure, highlighting the importance of immune modulation before chemotherapy administration.⁹¹ Similar timing-dependent effects have been described in other cardiovascular contexts. For instance, TNF-α exacerbates tissue injury in prolonged ischemia but can mediate ischemic preconditioning when exposure is transient.¹⁰¹

Several therapies already used in cardiovascular disease combine selective immune modulation with favorable timing profiles, making them attractive candidates for DIC prevention or treatment. Sodium-glucose cotransporter 2 inhibitors are a prime example, since they improve outcomes in heart failure across etiologies,^102,103 while mitigating excessive inflammation.¹⁰⁴ In a murine model of DIC, empagliflozin inhibited c-Jun N-terminal kinase (JNK) signaling, a driver of cytokine production, oxidative stress, and apoptosis, thereby reducing inflammation, preserving ventricular function, and limiting remodeling despite ongoing DOX exposure.¹⁰⁵ Glucagon-like peptide-1 receptor agonists may provide similar benefits by reducing systemic and myocardial inflammation^106,107 while simultaneously improving cardiac metabolism and function.¹⁰⁸ In addition, nonpharmacological approaches such as remote ischemic conditioning may offer cardioprotection in DIC¹⁰⁹ by engaging endogenous immune-priming mechanisms and broadly modulating immune responses.^110,111

Overall, these studies illustrate how immune modulation in DIC may be pursued through mechanistically selective strategies. However, successful translation into clinical practice will require careful consideration of additional challenges, including patient heterogeneity, optimal therapeutic timing, and preservation of antitumor immune competence.

Discussion and Future Perspectives

Over recent decades, the paradigm of DIC has evolved from a predominantly cardiomyocyte-centered model toward a broader framework integrating canonical mechanisms of DOX toxicity, including Top2β inhibition, oxidative stress, and mitochondrial dysfunction, with immune-mediated processes. Within this expanded view, the immune system emerges as a central determinant of cardiac outcome, capable of amplifying injury through inflammatory cascades while simultaneously shaping long-term remodeling. This perspective positions DIC within the broader field of cardio-immunology, where sterile inflammation and adaptive immune activation are viewed not merely as secondary responses to tissue damage, but as active contributors to disease progression.

A defining feature of immune involvement in DIC is its temporal complexity. Early innate immune activation, triggered within hours of DOX exposure through DAMP release and pattern recognition receptor engagement, contributes to the acute phase of cardiac injury. In contrast, persistent adaptive immune activation, including cytotoxic T cell infiltration, dysregulated macrophage polarization, and B cell–mediated responses, appears to underlie chronic remodeling that progresses long after drug exposure has ceased. This temporal stratification has direct implications for monitoring and therapeutic design, as interventions tailored to specific phases of immune involvement may achieve cardioprotection without broadly compromising immune competence. Translating this concept into clinical practice will require sensitive tools capable of detecting immune-driven myocardial injury before overt functional decline. Biomarkers, including troponins, MPO, and cytokine signatures, together with advanced imaging modalities such as global longitudinal strain and cardiac magnetic resonance mapping, may provide this opportunity.112, 113, 114, 115 However, biomarker selection warrants careful consideration because DIC involves systemic myotoxicity extending beyond the cardiomyocyte compartment. In immune checkpoint inhibitor (ICI)–related myocarditis, where systemic immune-mediated myotoxicity involves both cardiac and skeletal muscle, the traditional distinction between cardiac troponin I as the more cardiac-specific biomarker and cardiac troponin T as a broader cardiomuscular marker becomes clinically relevant^116,117: TNNT2 is significantly overexpressed in immune-injured skeletal muscle, whereas TNNI3 is not, suggesting that cardiac troponin T may more accurately reflect the total cardiomuscular burden of ICI-induced myotoxicity.¹¹⁸ This observation may have broader implications for anthracycline cardiotoxicity, as anthracycline treatment can disrupt high-energy phosphate metabolism and promote structural remodeling in both myocardial and skeletal muscle tissue, even when conventional biomarkers and left ventricular ejection fraction (LVEF) remain unchanged.¹¹⁹ Standard monitoring strategies may therefore underestimate the true extent of DOX-induced injury, whereas incorporation of tissue-level assessments into research protocols could enable earlier and more comprehensive detection of immune-mediated cardiomusculotoxicity. Integrating such immunocardiac monitoring approaches into cardio-oncology practice could ultimately refine risk stratification and facilitate mechanism-guided interventions.

The temporal and mechanistic heterogeneity of immune involvement in DIC further supports the need for therapeutic precision. Neutrophils, macrophages, T cell subsets, B cells, and iNKT cells all contribute to the evolution of toxicity, yet their roles are dynamic, context-dependent, and often paradoxical, since the same immune populations that propagate injury may also facilitate repair. This complexity extends to resident nonimmune cardiac populations, considering, for example, that cardiac fibroblasts orchestrate myocardial inflammation by producing chemokines, modulating leukocyte retention, and upregulating adhesion molecules through bidirectional crosstalk with infiltrating immune cells, thereby participating in the transition from acute injury to chronic fibrotic remodeling.^79,120,121 Such complexity highlights the need for deeper mechanistic resolution, which will require integration of emerging technologies with robust preclinical models.¹²² Although mechanistic insights have historically relied on murine systems, improving translational relevance increasingly depends on the incorporation of human-based models. In this context, both 2-dimensional and 3-dimensional platforms are gaining prominence, including induced pluripotent stem cell (iPSC)–derived coculture systems,¹²³ as well as more advanced 3-dimensional models such as heart–immune cell assembloids¹²⁴ and multiorganoid platforms.¹²⁵ These approaches, already well established in other areas of cardiovascular research, should be systematically leveraged in cardio-oncology to better define immune-cardiac interactions in DIC. In parallel, technological advances are transforming the ability to interrogate immune involvement at high resolution. Single-cell approaches, particularly single-cell RNA sequencing, combined with computational modeling, are reshaping the study of cardiac inflammation by enabling detailed characterization of cellular heterogeneity and functional states. These methods allow identification of immune cell subsets, activation trajectories, and stage-specific responses, while also capturing stromal-immune crosstalk and the spatial organization of inflammatory processes,¹²⁶ representing an important avenue for future investigation.⁶⁶ Complementary multimodal imaging strategies, integrating positron emission tomography, magnetic resonance imaging, and metabolic imaging, may further enhance the ability to map the spatiotemporal dynamics of myocardial inflammation,¹²² potentially enabling identification of optimal therapeutic windows.

These mechanistic considerations define the central therapeutic challenge: attenuating maladaptive inflammatory cascades while preserving antitumor immunity and reparative immune functions. This issue is particularly relevant in DIC because DOX exerts part of its antitumor efficacy through immunogenic cell death, whereby DAMPs released from dying tumor cells prime cytotoxic T-lymphocyte responses.^127,128 Likewise, inflammatory mediators implicated in cardiac injury, including IFNγ and TNF-α, also contribute to tumor cytotoxicity.^129,130 Broad immunosuppressive approaches therefore risk impairing not only the inflammatory pathways driving cardiac injury but also immune mechanisms essential for tumor control. This concern is heightened by the increasing use of DOX in combination with ICIs,131, 132, 133, 134 where maintaining immune competence is essential for therapeutic efficacy. The intrinsic myelotoxicity of DOX itself^135,136 already compromises host immune defenses, a burden that could be exacerbated by any additional immunosuppressive intervention.

Accordingly, the therapeutic objective should be immune recalibration rather than broad immunosuppression. Potential strategies include selectively targeting pathways disproportionately activated in the myocardium, exploiting temporal windows in which cardioprotective interventions can be dissociated from peak antitumor immunity, or using delivery systems that preferentially localize immunomodulatory agents to cardiac tissue. Candidate targets include IL-1β and IFNγ signaling, macrophage polarization, neutrophil extracellular trap formation, and immune-metabolic pathways modulated by SGLT2 inhibitors and GLP-1 receptor agonists.^91,95, 96, 97, 98, 99^,104,105 Realizing the translational potential of these approaches will require preclinical models capable of simultaneously evaluating cardiac and antitumor endpoints, together with clinical trial designs sensitive enough to detect cardioprotection without obscuring compromised oncological efficacy.

Beyond mechanistic insights, effective cardioprotection will require patient stratification strategies that account for the substantial inter-individual variability in DIC susceptibility. Clinical factors such as sex, age, comorbidities, and combination therapies modulate immune responses and influence both the risk and severity of cardiac injury. Genetic variability represents an additional, still incompletely characterized dimension of this heterogeneity. Candidate gene studies and genome-wide association studies have identified germline variants associated with anthracycline cardiotoxicity in genes related to drug metabolism (CBR3), transport (SLC28A3), DNA damage response (RARG, Top2β), and sarcomere integrity (TTN),⁵⁶ while genome-wide and transcriptome-wide approaches are beginning to define a broader genetic architecture of anthracycline sensitivity.137, 138, 139 Among the best-characterized variants is the noncoding SNP rs28714259, which disrupts glucocorticoid receptor binding at an enhancer locus and attenuates cardioprotective transcriptional programs in DOX-exposed cardiomyocytes.¹⁴⁰ By contrast, immune-regulatory loci remain under-represented, likely reflecting both methodological and biological limitations. Most studies rely on LVEF-based endpoints that capture late-stage dysfunction rather than upstream immunological events, while immune activation in DIC appears to represent a conserved response to tissue injury rather than a strongly genetically predetermined trait.^137,139 Variants in RAC2 and CYBA, encoding NADPH oxidase subunits, may represent partial exceptions, as their functions span both oxidative stress pathways and hematopoietic cell biology, suggesting a potential role for immune-redox interactions in DIC susceptibility.⁵⁶ In this context, interindividual variability may depend less on whether inflammatory pathways are activated and more on the magnitude, kinetics, and resolution of these responses, features likely shaped by polygenic architecture and environmental influences.^56,137 Future studies integrating immune-specific phenotypes, longitudinal biomarker profiling, and cell type–resolved transcriptomics will therefore be essential to define the genetic architecture of immune-mediated cardiotoxicity and enable mechanism-informed risk stratification.^137,139 Achieving these goals will require close collaboration across cardiology, oncology, and immunology to ensure translation of mechanistic insights into clinically meaningful strategies.

Taken together, the evidence reviewed here reframes DIC as a dynamic immunological condition rather than a static toxic endpoint, in which the immune system acts both as a determinant of injury severity and as a potential therapeutic target. This perspective positions cardioimmunology as a framework capable of shifting cardio-oncology from reactive management toward proactive, mechanism-based strategies that support earlier detection, individualized intervention, and preservation of cardiac function during anthracycline-based chemotherapy.

Declaration of Generative AI and AI-Assisted Technologies

During the preparation of this work the authors used ChatGPT in order to improve the clarity, language and style of the text. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the published article.

Funding Support and Author Disclosures

Research support has been received from the Italian Ministry of Health (GR-2021-12371950), the Italian Ministry of Education, Universities and Research (PRIN 2022 20223YPL49 and PRIN PNRR 2022 P2022ZB72T), Worldwide Cancer Research (grant 25-0373), and the Leducq Transatlantic Network of Excellence (19CVD02Le). Dr Ghigo is cofounder and shareholder of Kither Biotech, a pharmaceutical company focused on the development of PI3K inhibitors for airway diseases not in conflict with the content of this manuscript. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.