CHARACTERIZATION OF CELLULAR AND MOLECULAR FACTORS INVOLVED IN MUCOSAL INFLAMMATION IN EOSINOPHILIC GASTROINTESTINAL DISEASES

JULIÁN VACCARO; MANUELA ILID; BELEN POLO; LORENA MENENDEZ; PAULA BOROBIA; CECILIA ZUBIRI; LUCIANA GUZMÁN; VIVIANA BERNEDO; MARCELA GARCÍA; EUGENIA M. ALTAMIRANO; JUAN A. DE PAULA; JULIETA ARGUERO; CECILIA ISABEL MUGLIA; RENATA CURCIARELLO; GUILLERMO H. DOCENA

San Luis

Congreso; Reunión Anual de Sociedades de Biociencia SAI 2023; 2023

Eosinophilic Gastrointestinal Disorders (EoGD) are chronic and immune-mediated conditions marked by gastrointestinal (GI) symptoms and eosinophilic inflammatory infiltration of the GI tract. Food allergens triggered both Food Allergies and Eosinophilic Esophagitis (EoE) and their prevalence is increasing globally. Eosinophils are recruited to lamina propria due to a local type 2 inflammation dominated by IL-4, IL-5, IL-13, and eotaxins. In addition, persistent inflammation leads to fibrosis and tissue remodeling. Nevertheless, the underlying mechanisms are poorly understood. We previously showed that juvenile polyps from food allergic patients are infiltrated by eosinophils and fibroblasts, and high levels of type 2 cytokines and CCL26 were detected. In this study, we aimed to characterize the cellular and molecular interplays involving human intestinal eosinophils and fibroblasts.Isolated eosinophils and fibroblasts from colonic polyps of food allergic patients were primarily cultured. Fibroblasts were stimulated in vitro with rh-IL-13 (10ng/ml), rh-IL-9 (10ng/ml) and rh-TGF-β (10ng/ml), and vimentin and IL-8 secretion were evaluated by immunofluorescence and ELISA, respectively. Eosinophils enriched by cell sorting were exposed to IL-5 (10ng/ml) and cell viability was measured by trypan blue exclusion. Esophagus biopsies from adult patients with EoE were ex vivo stimulated with IL-13 (10ng/ml). Secreted CCL26, IL-33, IL-25 and TSLP were assessed by ELISA. Inflammatory parameters (α-SMA, CCL26, IL-33, TSLP) were evaluated in esophagus biopsies by immunofluorescence. Comparison between groups was made using Student´s t-test.We found an eosinophil-dominant cell infiltration in polyps (1,55+/-2,79% of live cells) with IgE+ cells (35,41+/-20,36% of the total cells). Sorted Lin-Siglec-8+ eosinophils (35% of yield) showed a higher viability when the culture medium was supplemented with rh-IL-5. Polyp fibroblast primary cultures expressed vimentin and secreted IL-8 under different Th2 stimuli (IL-13: 645+/-4,9; IL-9: 629,2+/-104 vs. medium: 482,3+/- 45 pg/ml). Eosinophil-conditioned media also triggered IL-8 secretion by fibroblasts (172,4 vs. medium: 57,6 pg/ml). Esophageal biopsies from adult EoE patients showed expression of α-SMA in lamina propria, while CCL26 and TSLP were detected in the epithelium. Ex vivo stimulation of esophageal biopsies with IL-13 induced TSLP (124,3+/-35,7 vs. medium: 45,26+/-9,3 pg/ml), but no CCL26, IL-25 or IL-33 secretion.In conclusion, we observed eosinophilic infiltration and activated fibroblasts in the inflamed mucosa of food allergic patients, particularly within polyps and the esophageal mucosa of EoE patients. To study cell responses and interactions, we optimized eosinophil and fibroblast isolation and culture conditions from GI human tissues. Our findings showed that the type 2 cytokines may activate EoGD fibroblasts.