Table 2.
Key host immunopathological pathways in PegIFN-α therapy for chronic hepatitis B: an integrated framework.
| Mechanism category | Key cells/tissues involved | Mechanism type | Core signaling pathways & molecular drivers | Critical effector molecules & processes | Pathophysiological consequence/clinical correlation | Key references |
|---|---|---|---|---|---|---|
| Systemic Inflammation & Cytokine Release | Macrophages, dendritic cells, endothelial cells. | Immune-mediated | Synergistic TNF-α & IFN-γ → hyperactivated JAK/STAT1; NF-κB activation. | Excessive TNF-α, IL-6, IFN-γ production; self-amplifying feedback loop; SASP induction. | Early toxicities: Flu-like syndrome (fever, myalgia, fatigue). Propagates tissue injury systemically. | (36–38) |
| Hematopoietic Suppression & Dysfunction | HSPCs, myeloid progenitors, megakaryocytes. | Direct cellular toxicity | Chronic JAK-STAT → SOCS induction; p38 MAPK activation. | SOCS-1-mediated inhibition of thrombopoietin signaling; HSPC exhaustion & skewed differentiation; ineffective hematopoiesis. | Dose-limiting cytopenias (neutropenia, thrombocytopenia); ↑ infection/bleeding risk. | (18, 39–42, 44) |
| Paradoxical Lymphocyte Consumption | Circulating CD8+ T cells (total & virus-specific). | Direct cellular toxicity (on immune cells) | PegIFN-α–potentiated pro-apoptotic cytokine milieu. | Activation-induced cell death/dysfunction; failure to reconstitute exhausted HBV-specific clones. | Systemic lymphopenia; highlights disconnect between innate activation and adaptive immune reconstitution. | (13, 94) |
| Loss of Peripheral Tolerance & Autoimmunity | APCs, Tregs, autoreactive lymphocytes. | Immune-mediated | IFN-α → IRAK1-p38 MAPK pathway (Treg apoptosis); JAK-STAT-driven MHC I/II upregulation. | IRAK1-mediated Treg apoptosis; enhanced self-antigen presentation; autoantibody production (e.g., anti-TPO). | Autoimmune phenomena: Thyroid dysfunction (most common), drug-induced autoimmune hepatitis. | (22–24, 50, 51, 95) |
| Neurotoxicity via Central Inflammation | Microglia, neurons, HPA axis. | Immune-mediated | Peripheral cytokines → CNS JAK-STAT/IDO activation; HPA axis dysregulation. | IDO-mediated tryptophan/serotonin depletion; dopaminergic dysfunction; sustained microglial activation. | Neuropsychiatric toxicity: depression, cognitive impairment, fatigue. | (19, 45–49) |
| Pulmonary Vascular Injury | Pulmonary endothelium, vascular smooth muscle cells. | Direct cellular toxicity | Sustained IFN-α → Caveolin-1 insufficiency → dysregulated eNOS/STAT1/AKT; chemokine induction. | Endothelial dysfunction (↑ CX3CL1); constitutive STAT1 activation; interferon gene signature. | Pulmonary arterial hypertension (PAH); interstitial inflammation. | (68, 69, 71–73) |
| Cardiac & Renal Direct Immunotoxicity | Cardiomyocytes, cardiac endothelium; renal podocytes/endothelium. | Cardiac: Immune-mediated | Cardiac: Cytokine-mediated negative inotropy. Renal: Direct IFN-α/β signaling. | Cardiac: TNF-α/IL-1β-mediated contractile depression. Renal: Podocyte injury, endothelial thromboresistance impairment. | Cardiac: Rare myopericarditis, cardiomyopathy. Renal: Proteinuria, FSGS, thrombotic microangiopathy. | Cardiac (74–76, 80, 82): |
| Renal: Direct cellular toxicity | Renal (84, 86–88, 91): | |||||
| Gastrointestinal & Dermatological Toxicity | Gut epithelium, skin keratinocytes/lymphocytes. | GI: Direct cellular toxicity | GI: Synergistic IFN-γ/TNF-α → JAK/STAT1 cytotoxicity. Derm: Direct IFN-α signaling on immune cells. | GI: Cytokine-driven sickness behavior, epithelial barrier disruption. Derm: Hair cycle disruption (alopecia), psoriasiform eruptions. | GI: Nausea, anorexia, diarrhea. Derm: Alopecia, rash, psoriasis exacerbation. | GI (54–56, 96): |
| Derm: Immune-mediated | Derm (57–60): | |||||
| Ocular Vascular Injury | Retinal capillary endothelium, platelets. | Direct cellular toxicity | Cytokine-mediated endothelial injury (JAK/STAT, NF-κB); IL-17A activation of JAK1. | Endothelial damage/permeability (TNF-α, IFN-γ, IL-17A); synergy with thrombocytopenia. | Asymptomatic retinopathy (common); symptomatic hemorrhage (rare). | (27, 30, 31, 61, 62) |
This table summarizes the principal immunopathological pathways discussed in Section 3. The “Mechanism Type” column distinguishes between Immune-mediated toxicities (where tissue damage is inflicted by activated immune effector cells such as T cells, NK cells, or autoantibodies) and Direct cellular toxicity (where the JAK-STAT signaling cascade directly induces dysfunction, stress responses, or apoptosis in the affected non-immune target cells). Both categories are direct consequences of PegIFN-α-induced systemic immune activation, which underlies both therapeutic efficacy and multisystem toxicity. These stand in contrast to the pre-existing state of T-cell exhaustion characteristic of chronic HBV infection, which the therapy aims to reverse. The central clinical paradox lies in attempting to overcome the latter without overwhelming the host via the former.
AKT, protein kinase B; APC, antigen-presenting cell; CD8, cluster of differentiation 8; CX3CL1, C-X3-C motif chemokine ligand 1; eNOS, endothelial nitric oxide synthase; FSGS, focal segmental glomerulosclerosis; GI, gastrointestinal; HBV, hepatitis B virus; HPA, hypothalamic-pituitary-adrenal; HSPC, hematopoietic stem and progenitor cell; IDO, indoleamine 2,3-dioxygenase; IFN, interferon; IL, interleukin; IRAK1, interleukin-1 receptor-associated kinase 1; JAK, Janus kinase; MAPK, mitogen-activated protein kinase; MHC, major histocompatibility complex; NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells; PAH, pulmonary arterial hypertension; PegIFN-α, pegylated interferon-alpha; SASP, senescence-associated secretory phenotype; SOCS, suppressor of cytokine signaling; STAT, signal transducer and activator of transcription; TNF-α, tumor necrosis factor-alpha; Treg, regulatory T cell.