Effects of the S1PR3 specific agonist peptide GPS-725.017 on acute lung injury in mice / 中华急诊医学杂志

ABSTRACT

Objective:To design a modified S1PR3 specific agonist, GPS-725.017, and investigate its protective effect on acute lung injury by promoting macrophage clearance of bacteria.Methods:A short peptide derived from the intracellular region of S1PR3 receptor was named GPS725.017, which was modified with norleucine (Nle) and myristicacid (myr) at its N terminus. Mice were divided into the sham operation group, solvent group and GPS-725.017 treatment group. The acute lung injury model was induced by endotracheal injection of E. coli (5×10 6 CFU), and the experimental group was treated with GPS-725.017 (10 mg/kg). The 48-h survival rate of mice was recorded. After 5 h of modeling, the bacterial load and inflammatory cytokines in peripheral blood and lung were detected, and Vps34 protein content in alveolar macrophages was determined by Western blot. After 12-h of modeling, lung tissues were collected for H&E staining and pathological scores. Results:Compared with the solvent group, the survival rate of mice in the GPS-725.017 treatment group was significantly improved ( P<0.01), the bacterial CFU in blood and alveolar lavage fluid was significantly lower than that in the solvent group ( P<0.001), and the levels of TNF-α and IL-1β in blood and alveolar lavage fluid were significantly lower than those in the solvent group ( P<0.001). Western blot showed that the expression level of Vps34 protein in alveolar macrophages was significantly higher than that in the solvent group ( P<0.01). Histopathology result showed that the pathological damage of lung in the treatment group was significantly less than that in the solvent group ( P<0.001). Conclusions:The modified synthetic S1PR3 specific agonist GPS-725.017 could specifically activate the S1PR3 receptor on the membrane of alveolar macrophages and up-regulate the expression level of intracellular Vps34 protein, which can promote the removal of bacteria in alveolar macrophages, significantly reduce the degree of lung injury and improve the survival rate in ALI mice.