"Role of TLR4 in murine model of Intestinal Ischemia / Reperfusion Injury"

Campolo Michela, Di Paola Rosanna, Ahmad Akbar, Esposito Emanuela, Cuzzocrea Salvatore. university of messina, department of Clinical and Experimental Medicine and Pharmacology,School of Medicine, Italy

The Toll-like receptors were named after the fruit-fly receptor Toll, which was first discovered because it has an important role in early fly development and was later recognized as contributing to innate immunity in adult flies. TLRs are a type of pattern recognition receptor (PRR) and recognize molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs). Activation of the TLRs leads not only to the induction of inflammatory responses but also to the development of antigen-specific adaptive immunity. The TLR-induced inflammatory response is dependent on a common signaling pathway. A large body of evidence suggests that TLRs participate in the recognition of endogenous proteins that are released from damaged tissues after ischemia/reperfusion injuries (I/RI). An ischemic injury occurs when a tissue is temporarily deprived of blood supply, whereas reperfusion injury occurs when blood resupply triggers an intense inflammatory response.

I/RI to the intestine is a major cause of organ dysfunction in surgery and transplantation. Intestinal I/RI can result locally in extensive tissue damage and distantly in a systemic inflammatory response. Although the role of TRL has been recognized in I/RI, little data exists regarding TLR4 in intestinal I/RI, for this reason, the aim of this study was to investigate the role of TLR-4 in C57BL/10ScN (TLR-4 KO) on the modulation of the secondary events in mice subjected to intestinal I/RI. Intestinal I/R provokes local and systemic alterations mainly derived from the release of cytotoxic substances and the interaction between neutrophils and endothelial cells. Substances involved in this process are ROS, NO, transcription factors, complement activation factors, and proteases. This injury was induced in C57BL/10ScN (TLR4 KO) (n=10 for each group)and in TRL-4 wild type (TLR4 WT) male mice (25–30 g) by clamping the superior mesenteric artery and the celiac trunk for 30 min, followed by release of the clamp, allowing reperfusion for 1h. After 60 min of reperfusion, animals were killed for histological examination of the ileum tissue, neutrophil infiltration, western blot analysis to study the production of pro-inflammatory cytokines such as iNOS, COX2, IL-6. The results were analyzed by one-way ANOVA, followed by a Bonferroni post-hoc test for multiple comparisons. Non parametric data were analyzed with the Fisher\'s exact test. A P value < 0.05 was considered significant. *, P<0.05, versus sham, °P < 0.05, versus I/R. These finding obtained by the histological and molecular examinations showed a similar inflammation pathway in both groups of animals. Taken together these findings establis hed that the absence of TLR4 receptor is not able to protect the local mucosal damage after intestinal I/RI.