Effect of peroxynitrite on intestinal epithelial barrier dysfunction induced by polymicrobial sepsis

• Grant number: 22/14857-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2023
• End date: July 31, 2024
• Field of knowledge: Biological Sciences - Morphology - Histology
• Principal Investigator: Rafael Simone Saia
• Grantee: Lucas de Souza Ortolan
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The intense activation of the systemic inflammatory response induced by sepsis has been associated with the generation of free radicals by multiple cell types. It is evident that several deleterious effects attributed to nitric oxide (NO) in sepsis are, in fact, indirectly mediated by peroxynitrite (ONOO). Peroxynitrite has been recognized as responsible for some sepsis associated complications, including cardiovascular collapse, vasoplegia, endothelial dysfunction, reduced neutrophil rolling and adhesion, and modifications of different biological molecules. However, there is a gap in the literature regarding the role of peroxynitrite in intestinal epithelial barrier dysfunction. The aim of this study is to investigate the role of peroxynitrite in intestinal epithelial barrier dysfunction induced by polymicrobial sepsis. Mice will be treated immediately after the end of the CLP with the FeTPPS scavenger (5 or 15mg/kg) or with the same volume of saline solution. Furthermore, it will be also evaluated: intestinal permeability in the ileum and colon; quantification of cytokines and 3-nitrotyrosine; expression of junctional proteins in the ileum and colon; evaluation of the morphology of tight junctions (TJ) by transmission electron microscopy; histological analysis of the intestinal mucosa; microbiological analysis inblood, peritoneal lavage and mesenteric lymph nodes; and the mucosal infiltration of neutrophils by myeloperoxidase. We hypothesized that the administration of a peroxynitrite scavenger attenuates the increase in intestinal permeability, reduces the synthesis of pro-inflammatory mediators, preserves the structure of the epithelium and decreases bacterial translocation induced by sepsis.