Etiology of Hunner Lesions: Linking Immune Dysregulation and Chronic Inflammation in Interstitial Cystitis/Bladder...

Hunner lesions (HL) are distinctive ulcerative bladder lesions characterized by a central scar and surrounding erythema. Traditionally, HL has been used as a clinical diagnostic tool for a subset of patients with interstitial cystitis/bladder pain syndrome (IC/BPS); however, emerging evidence supports a unique pathophysiology for IC/BPS with HL (HIC) that is distinct from IC/BPS without HL (NHIC). This review is aimed at synthesizing current literature on the etiology of HL/HIC and evaluate whether HIC and NHIC warrant classification as separate clinical conditions with distinct management strategies.

A comprehensive literature review using PubMed was conducted to identify literature surrounding HL etiology and pathophysiology. Case-control studies, cohort studies, experimental studies, case reports, and animal studies were included; editorial comments and literature reviews were excluded from this review.

Emerging data suggest that a subset of patients might be predisposed to HIC, including alteration in major histocompatibility complex (MHC) molecules, HLA amino acid positions, and additional protein expression alterations detected by RNA sequencing. Hypoxia-inducible factor activation and chronic ischemia have also been shown to play a role in HL development. Both local and systemic inflammation are seen in HIC, with clonal B-cell expansion influencing the upregulation of inflammatory cytokines, chemokines, and lymphoplasmacytic cells. With additional validation these biomarkers have the potential to serve as a diagnostic tool.

Hunner lesion with IC/BPS is a chronic condition likely caused by an upregulation of humoral immunity leading to an overexpression of inflammatory markers within the urothelium, suggesting an autoimmune-mediated pathology for this patient subgroup.