Characterization of cellular and molecular factors involved in mucosal inflammation in eosinophilic gastrointestinal diseases

JULIÁN VACCARO; MANUELA ILID; MARÍA BELEN POLO; LORENA MENENDEZ; PAULA BAROBIA; CECILIA ZUBIRI; ANABELA ZOSI; LUCIANA GUZMÁN; VIVIANA BERNEDO; MARCELA GARCÍA; EUGENIA M ALTAMIRANO; JUAN ANDRÉS DE PAULA; JULIETA ARGUERO; CECILIA MUGLIA; RENATA CURCIARELLO; GUILLERMO DOCENA

San Luis

Congreso; LXXI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2023

Sociedad Argentina de Inmunología

Eosinophilic Gastrointestinal Disorders (EoGD) are chronic and immunemediatedconditions marked by gastrointestinal (GI) symptoms and eosinophilicinflammatory infiltration of the GI tract. Food allergens triggered both FoodAllergies and Eosinophilic Esophagitis (EoE) and their prevalence is increasingglobally. Eosinophils are recruited to lamina propria due to a local type 2inflammation dominated by IL-4, IL-5, IL-13, and eotaxins. In addition, persistentinflammation leads to fibrosis and tissue remodeling. Nevertheless, theunderlying mechanisms are poorly understood. We previously showed thatjuvenile polyps from food allergic patients are infiltrated by eosinophils andfibroblasts, and high levels of type 2 cytokines and CCL26 were detected. In thisstudy, we aimed to characterize the cellular and molecular interplays involvinghuman intestinal eosinophils and fibroblasts.Isolated eosinophils and fibroblasts from colonic polyps of food allergic patientswere 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-8secretion were evaluated by immunofluorescence and ELISA, respectively.Eosinophils enriched by cell sorting were exposed to IL-5 (10ng/ml) and cellviability was measured by trypan blue exclusion. Esophagus biopsies from adultpatients 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 byimmunofluorescence. Comparison between groups was made using Student's ttest.We found an eosinophil-dominant cell infiltration in polyps (1,55+/-2,79% of livecells) 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 wassupplemented with rh-IL-5. Polyp fibroblast primary cultures expressed vimentinand secreted IL-8 under different Th2 stimuli (IL-13: 645+/-4,9; IL-9: 629,2+/-104vs. 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 biopsiesfrom adult EoE patients showed expression of α-SMA in lamina propria, whileCCL26 and TSLP were detected in the epithelium. Ex vivo stimulation ofesophageal 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 theinflamed mucosa of food allergic patients, particularly within polyps and theesophageal mucosa of EoE patients. To study cell responses and interactions,we optimized eosinophil and fibroblast isolation and culture conditions from GIhuman tissues. Our findings showed that the type 2 cytokines may activate EoGDfibroblasts.