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.
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Objective To study the effects of the myristoyl-glycine modified peptide which derived from the second intracellular loop of sphingosine 1-phosphate receptor 3 (S1PR3) on activation of mitogenactivated protein kinases (MAPKs) pathway.Methods The phosphorylation levels of JNK and ERK in THP-1 cells were detected by western blot after GPS-725.017 stimulation.Statistical data analysis was conducted by multivariate analysis of variance.Results Western blot showed that 10 min after 30 μmol/L or 50 μmol/L GPS-725.017 stimulated,phosphorylation of ERK significantly increased in comparison with the solvent-treated group [30 μmol/L group:(3.10 ± 0.27) vs.(7.98 ± 0.45),P ＜ 0.01;50 μmol/L group:(4.78 ±0.44) vs.(25.98 ±2.32),P ＜0.01];after 50 μmol/L GPS-725.017 stimulated THP-1 cells for 5 min,10 min,20 min or 30 min,p-ERK or p-JNK level raised at different time points (P ＜0.01vs.solvent group).Conclusions GPS-725.017,a kind of myristoyl-glycine modified peptide derived from S1 PR3,could traverse cytomembrane and activate MAPKs pathway.This study provides an implication of targeting S1PR3 for clinical therapy on inflammatory diseases or sepsis.
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Objective To observe the effect of S1PR2/3 on heart during myocardial ischemia-reperfusion (I/R) in rats. Methods Healthy adult male Sprague-Dawley rats were randomly divided into 7 groups: control group, sham operation group, IR group, IR group treated with DMSO, IR group treated with Cym5541( agonist of S1P3), IR group treated with Cay10444 (antagonist of S1P3), IR group treated with Cay10444/Jte-013 (antagonist both S1P3 and S1P2). In vivo model of myocardial ischemia-reperfusion was established. The hemodynamics, infarction area and mortality was recorded. Results Compared with IR, the S1PR3 antagonist group and S1PR2/3 antagonist group showed signiifcantly reduction of heart rate(HR) and increament left ventricular end-diastolic pressure(LVEDP)(P<0.05). In addition, the infarction area was increased in the S1PR3 antagonist group and S1PR2/3 antagonist treated group (55.7%:28.8%, 51.6%:28.8%), respectively. Treatment with S1PR3 agonist reduced the infarct size compared with IR group(18.6%:28.8%). Blocking S1P2/3 receptors increased IR-induced mortality signiifcantly (53%:22%, P<0.05). Conclusion S1PR2/3 have a beneifcial effect on heart. S1PR2 and S1PR3 were involved in the IR-induced SCD.