Treatment Effect Of Lactose Derivatives Gu-4 Endotoxic Shock In Mice And Its Mechanism

Background:Endotoxin shock (ES) is a life-threatening syndrome which characterized by tissue hypoperfusion, hypotension and organ dysfunctions. ES caused extesive concerns because of its high morbidity and high mortality. How to effectively treat ES remains a serious problem to be solved. In the pathogenesis of ES, the interaction between leukocytes and endothelial cells play vital roles:leukocytes adhered to the venule walls will increase blood flow resistance and lead to blood stasis and blockade of microcirculation; futher extravasation of leukocyte will cause tissue damage of various organs. Previously, we reported that a lactosyl derivative Gu-4 functioned on a rat sever burn shock model by targeting Mac-1. We therefore hypothesized that Gu-4 might also exert therapeutic effect on ES.Methods:In vivo experimental approch was adopted to assess the therapeutic effect of Gu-4. The survival rate of mice underwent endotoxin shock was recorded. The pathological changes of major organs from endotoxin shock mice were examined, and the level of inflammatory factors in serum and biochemical changes in lung tissue were determined. The mechanism underlying the biological function of Gu-4 was analysed by in vitro experimental approches. Using adhesion assay and migration assay, the effect of Gu-4 on leukocyte adhesion behevior was investigated. The activation and distribution of Mac-1 as well as Syk signaling pathway were observed by flow cytometry, confocal microscopy and Western blotting.Results:In vivo experimental data showed that Gu-4 greatly improved the outcome of endotoxin shock of mice with 50% survival rate (p<0.05 vs. saline group), and the organ damages such as blood congestion in lung and kidney were significantly ameliorated. The expression pattern of TNF-alpha in serum was not apperently affected by Gu-4 treatment. Under the treatment of Gu-4, the lactic acid level in lung tissue of LPS challenged mice first increased and then decreased. In vitro experimental data demonstrated that the adhesion and transendothelial migration of leukocytes were significantly inhibited by Gu-4 treatment. In particular, the exposure of activeⅠ-domain and cluster formation of Mac-1 upon TNF-αchallenge were inhibited by Gu-4, and the activation of outside-in signaling pathway of spleen tyrosine kinase triggered by high affinity Mac-1 was partially blocked by Gu-4 as well. Conclusions:Lactosyl derivatives Gu-4 increased the survival rate of mice underwent endotoxin shock, the underlying mechanism of which is that Gu-4 inhibited the activation and cluster formation of Mac-1 and thereby blocked Mac-1-mediated adhesion and transendothelial migration of leukocytes. Gu-4 might be a potential therapeutic candidate for sepsis and septic shock.