Mesenteric inflammation is related to reduced Endothelial Purinergic P2Y6 Receptor Expression and Function during schistosomiasis

Introduction: Schistosomiasis is an intravascular infectious disease promoting chronic portal-mesenteric inflammation and endothelial dysfunction related to cell damage activating purinergic signaling. The P2Y₆ receptor (P2Y₆R) is activated by UDP and is associated to vascular (Arterioscler. Thromb. Vasc. Biol. (2014) 34:2237) and non-infectious intestine inflammation (Gut. (2022) 71:43). However, its role in mesenteric endothelial cells (EC) is unknown. Therefore, our aim was to investigate the mesenteric endothelial P2Y₆R expression and function during schistosomiasis. Methods: Primary cultures of EC were obtained from control and S. mansoni-infected mice (50-70 days p.i.; CEUA UFRJ 124/22). Confluent EC were pre-treated with vehicle (basal) or P2Y₆R selective antagonist (MRS2578 1 μM) or ectonucleotidase inhibitor (ARL67156 100 μM) for 30 min and then stimulated with UDP (100 μM) for 5h to adhesion assay with freshly isolated monocytes for more 30 min. Data were expressed as mean and SEM. Results: In the control group UDP increased monocyte adhesion to EC from 2.6 ± 0.1 to 5.0 ± 0.4 cells/field (P < 0.001, n=4) and its effect was inhibited by MRS2578. In the infected group, UDP failed to induce monocyte adhesion (P = 0,92 basal vs UDP; n=4) and the ectonucleotidase inhibitor did not change the monocyte adhesion, discarding UDP hydrolysis. The RT-qPCR and immunocytochemistry analysis revealed reduced endothelial P2Y₆R gene transcription (P < 0.01, n=3) and expression (P < 0.05, Student´s t test, n =2-3) in the infected group compared to control, respectively, corroborating functional data. Noteworthy, we showed recently that schistosomiasis upregulated endothelial P2Y₂R function (Front. Immunol. (2024) 14:1328897). Conclusion: Schistosomiasis reduced endothelial P2Y₆R expression and function, which may counteract the upregulated P2Y₂R in the murine mesenteric vessels that favors mesenteric inflammation. Acknowledgments: FIOCRUZ (RJ), CNPq, CAPES, FAPERJ.