Propofol Improves Survival In A Murine Model of Sepsis Via Inhibiting Rab5a -Mediated Intracellular Trafficking of TLR4

Background：Propofol is a widely used anesthetic and sedative, which has been reported to exert an anti-inflammatory effect. TLR4 plays a critical role in coordinating the immuno-inflammatory response during sepsis. Whether propofol can act as an immunomodulator through regulating TLR4 are still unclear. In view of its potential as a sepsis therapy, we investigated the mechanisms underlying the immunomodulatory activity of propofol.Methods: The effects of propofol on TLR4 and Rab5a (a master regulator involved in intracellular trafficking of immune factors) were investigated in macrophage (from Rab5a-/- and WT mice) following treatment with lipopolysaccharide or cecal ligation and puncture in vitro and in vivo, and in peripheral blood monocyte from sepsis patients and healthy volunteers. Results: We showed that propofol reduced membrane TLR4 expression on macrophage in vitro and in vivo. Rab5a participated in TLR4 intracellular trafficking and both Rab5a expression and the interaction between Rab5a and TLR4 were inhibited by propofol. We also showed Rab5a upregulation in peripheral blood monocyte of septic patients, accompanied by increased TLR4 expression on the cell surface. Both were correlated with SOFA score of sepsis patients and higher expression of Rab5a were found in septic non-survivors. Propofol downregulated the expression of Rab5a and TLR4 in these cells.Conclusions：We demonstrated that Rab5a regulates intracellular trafficking of TLR4 and that propofol reduces membrane TLR4 expression on macrophages by targeting Rab5a. Our study not only reveals a novel mechanism for the immunomodulatory effect of propofol but also indicates that Rab5a may be a potential therapeutic target against sepsis.