Annual Scientific Meeting
Introduction: Eosinophilic esophagitis (EoE) is a chronic allergic disease characterized by esophageal inflammation and fibrosis with a higher disease prevalence in males than females (3:1). The underlying mechanisms behind this sexual dimorphism remain unclear.
Methods: Primary human fibroblasts from males and females with active EoE were isolated from esophageal biopsies. Normal fibroblasts were isolated from donor esophageal explants. Fibroblasts were treated with recombinant IL-4, IL-13, or TGFβ1 and analyzed for inflammatory and fibrotic gene expression by qPCR. Esophageal biopsy specimens from active disease patients were scored using a standardized histology score.
Results: IL-4 or IL-13 induced significantly more eotaxin-3/ccl26 mRNA expression in esophageal fibroblasts from males as compared with females (p< 0.001). This trend was observed in fibroblasts derived from adults or children, consistent with increased EoE onset in males of all ages. TGFβ1 induced significantly higher levels of collagen-1, α-smooth muscle actin, fibronectin, and serpinE1 (p< 0.03) mRNA in male (n=5) EoE esophageal fibroblasts as compared with females (n=3). Hematoxylin and eosin staining of EoE esophageal biopsies (n=153, 125 males and 28 females) revealed that while overall eosinophil count correlated with epithelial remodeling score (r=0.3550, p< 0.0001) within the distal esophagus, this correlation was distinctly stronger in the male patients (r=0.4062, p< 0.0001) than within the female patients (r=0.1546, p=0.4323). The same pattern was found in the middle (male r=0.6080, p< 0.0001; female r=0.4723, p=0.013) and proximal esophageal levels (male r=0.8504, p< 0.0001; female r=0.5235, p=0.006). Immunohistochemical staining of EoE esophageal biopsies showed significantly more TGFβ1-positive cells in female than male patients (p< 0.001) but no differences in Smad2/3 phosphorylation.
Discussion: Male esophageal fibroblasts have a more robust response to Th2 interleukins and TGFβ1 as compared with female fibroblasts in adults and children and during the normal and active disease states, suggesting an intrinsic sexual dimorphism in esophageal cells. Epithelial histologic disease severity in males also correlates more strongly with elevated eosinophil counts than in females, suggesting that the male esophagus may have more profound responses to cytokines or antigens as compared to females. These data support a potential mechanism for the sex biased disease expression of EoE.