A NOVEL OPSONIC EXTRACELLULAR CIRP INHIBITOR MOP3 ALLEVIATES GUT ISCHEMIA/REPERFUSION INJURY.

Introduction: Gut ischemia and reperfusion (I/R) injury promotes the release of damage-associated molecular patterns (DAMPs) such as extracellular cold-inducible RNA-binding protein (eCIRP). Gut I/R often leads to acute lung injury (ALI), a major contributor to mortality. Milk fat globule-epidermal growth factor-factor VIII-derived oligopeptide-3 (MOP3) is a novel peptide that attenuates sepsis by opsonizing eCIRP and facilitating its phagocytic clearance. We hypothesized that MOP3 reduces inflammation, mitigates gut and lung injury, and improves survival in gut I/R injury. Methods: Phagocytosis of FITC-labeled eCIRP by intestinal epithelial cells was determined by confocal microscopy, and the cell supernatant was evaluated for cytokine expression by ELISA. Adult C57BL/6 mice underwent 60 min of gut ischemia via superior mesenteric artery occlusion followed by reperfusion. Mice were treated with MOP3 or vehicle via retro-orbital injection at the time of reperfusion. At 4 h post-I/R, blood, gut, and lungs were harvested for further assay. In additional mice, 36-h survival was assessed. Plasma levels of injury and inflammatory markers were measured with colorimetry and ELISA, respectively. Tissue mRNA expression was measured with qPCR. Myeloperoxidase (MPO), TUNEL, histologic injury, and ZO-1 immunohistochemistry assessments were performed. Results: MOP3 significantly increased eCIRP phagocytosis by intestinal epithelial cells ( P < 0.01) and decreased IL-6 release ( P < 0.001). Gut I/R caused elevated plasma eCIRP levels. MOP3 treatment significantly reduced plasma levels of IL-1β ( P < 0.01), IL-6 ( P < 0.05), and lactate dehydrogenase ( P < 0.05) along with a significant decrease in gut ( P < 0.05) and lung ( P < 0.001) injury scores as well as gut cell death ( P < 0.05). Moreover, MOP3 reduced pulmonary levels of chemokines and the granulocyte activation marker MPO after gut I/R. Mechanistically, ZO-1 expression in the gut was decreased following gut I/R injury, whereas MOP3 significantly reversed the decrease in ZO-1 mRNA expression ( P < 0.001). Finally, mice treated with MOP3 exhibited a significant decrease in mortality ( P < 0.05). Conclusions: Treatment with MOP3 effectively mitigates organ injury induced by gut I/R. This beneficial effect is attributed to the facilitation of eCIRP clearance, directing the potential of MOP3 as an innovative therapeutic approach for this critical and often fatal condition.