A. Senda1, K. Morishita1, M. Kojima1, S. Doki2, M. Yagi1, T. Kobayashi2, J. Aiboshi1, Y. Otomo1 1Tokyo Medical And Dental University,Departments Of Acute Critical Care And Disaster Medicine,Bunkyo-ku, Tokyo, Japan 2Ochanomizu University,Faculty Of Science,Bunkyo-Ku, TOKYO, Japan
Introduction: Intestinal ischemia-reperfusion (IR) leads to gut barrier failure that initiates a systemic inflammatory response resulting in acute lung injury/multiple organ dysfunction syndrome. Previous studies have shown that mesenteric lymph (ML) has a crucial role in driving the gut-mediated inflammation after IR. Our group have reported that lipid mediators, such as lysophosphatidylcholine (LPC) and arachidonic acid, contained in ML mediate organ injury following trauma/hemorrhagic shock (T/HS) via activation of immune cells. Concurrently, there is a research proving exosome as the major component of inflammatory response. Therefore, we investigated the bioactivity of exosomes released to the ML during intestinal IR injury. We also analyzed the profiles of exosomal lipids of ML to identify the specific mediators carried by ML exosomes.
Methods: Male Sprague-Dawley rats underwent laparotomy followed by ML duct cannulation. Animals were then subjected to 60 minutes of superior mesenteric artery clumping and de-clamping to induce gut IR injury. ML was obtained before (Pre) and after IR (Post-I/R). Exosomes were isolated from ML by ultracentrifugation. The biological activity of ML exosomes in each period was measured by monocyte NF-κB activation. The exosomal lipids in each group were extracted using of Bligh and Dyer method and performed liquid chromatography electrospray ionization mass spectrometry.
Results:The pro-inflammatory activities of exosomes harvested after IR were confirmed by an increase in NF-κB activation (5.6-fold increase compared to control). Lipid analysis of exosomes fraction of ML revealed significant increase in the concentration of polyunsaturated fatty acid (PUFA) (C18:2, C20:4) containing LPCs after IR when compared to that of control ML exosomes?(see Figure).
Conclusion:In response to IR injury, exosome fraction of ML shows significant increase in lipid mediators and triggers inflammation.
