Effect of intermedin on activation of nucleotide-binding oligomerization domain-like receptor protein 3 and pyroptosis in lipopolysaccharide induced macrophages / 中华风湿病学杂志

ABSTRACT

Objective:The effect of intermedin (IMD) on ATP-induced activation of inflammatory bodies and pyroptosis of cells and its mechanism were studied using lipopolysaccharide (LPS)-sensitized mouse macrophage line RAW 264.7.Methods:The cells were divided into the control groups, the LPS groups, LPS+IMD groups, and LPS+IMD+LY294002 groups. The expression of interleukin (IL)-1β and IL-18 and the activation of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammatory cells were detected by real-time PCR and western blotting, and the pyroptosis of cells was detected by propidium iodide (PI) staining. The measurement data was represented by MS± SD, and the inter-group difference was compared with ANOVA calculations, and P<0.05 represented the difference with statistical significance. Results:Compared with the control group [(0.83±0.09) vs (0.49±0.04)], the ratio of phosphorylated phosphatidylinositol-3-kinase, p-PI3K)/phosphatidylinositol-3-kinase (PI3K) (0.44±0.05) and p-Akt/Akt (0.27±0.06) in the LPS group was significantly decreased. The ratios of p-PI3K/PI3K (1.22±0.18) and pAkt/Akt (0.83±0.09) in LPS+IMD group was significantly increased ( F=31.40, P<0.001; F=50.88, P<0.001). Compared with the control group, the mRNA and protein expressions of IL-1β, IL-18 and NLRP3 inflammasome (NLRP3, caspase-1, ASC) in RAW264.7 cells were up-regulated in the LPS group (LPS and ATP). Compared with LPS group, IMD treatment inhibited the expression of inflammatory cytokines IL-1β, IL-18 and NLRP3 inflammasome, which was blocked by LY294002, a blocker of PI3K/Akt pathway. The results of real-time PCR showed that the relative expression of IL-1β mRNA was (1.00±0.11) in the control group, (8.32±0.61) in the LPS group, (8.32±0.55) in the LPS+IMD group, and (7.23±0.41) in the LPS+IMD+LY group ( F=15.42, P<0.001). The relative expression of IL-18 mRNA in the control group was (1.00±0.17), (1.82±0.21) in the LPS group, (1.14±0.15) in the LPS+IMD group, and (1.53±0.11) in the LPS+IMD+LY group respectively ( F=18.16, P<0.001). The relative expression of NLRP3 mRNA in the control group was (1.00±0.13), (2.58±0.18) in the LPS group, (1.07±0.17) in the LPS+IMD group, and (1.33±0.32) in the LPS+IMD+LY group respectively ( F=15.98, P< 0.001); The relative expression of caspase-1 mRNA in the control group was (1.00±0.09), (6.20±0.19) in the LPS group, (3.43±0.06) in the LPS+IMD group, and (5.50±0.45) in the LPS+IMD+LY group respectively ( F=18.39, P<0.001). The relative expression of ASC mRNA in the control group was (1.00±0.21), (4.58±0.48) in the LPS group, (2.07±0.51) in the LPS+IMD group, and (3.33±0.32) in the LPS+IMD+LY group respectively ( F=15.19, P<0.001). Western blotting results showed that the relative expression of IL-1β protein was as follows (100%) in the control group, [(188±14)%] in the LPS group, [(112±11)%] in the LPS+IMD group, and [(171±27)%] in the LPS+IMD+LY group respectively ( F=21.25, P<0.001). The relative expression of IL-18 protein in the control group was 100%, [(183±16)%] in the LPS group, [(115±19)%] in the LPS+IMD group, and [(179±23)%] in the LPS+IMD+LY group respectively ( F=19.62, P<0.001). The relative expression of NLRP3 protein was 100% in the control group, [(149±15)%] in the LPS group, [(106±10)%] in the LPS+IMD group, and [(144±15)%] in LPS+IMD+LY group respectively ( F=14.35, P<0.001). The relative expression of ASC protein was 100% in the control group, [(188±12)%] in the LPS group, [(110±18)%] in the LPS+IMD group, and [(192±8)%] in the LPS+IMD+LY group ( F=15.79, P<0.001). Conclusion:IMD inhibits the activation of NLRP3 inflammasome and cell pyroptosis by regulating PI3K/Akt activity.