Dexmedetomidine protects against renal ischemia reperfusion injury and cell pyroptosis via the α2-receptor/heat shock pro-tein 70/NOD-like receptor-related protein 3 pathway
Objective To observe the protective effect of dexmedetomidine(Dex)on renal ischemia reperfusion(IR)and to in-vestigate whether the mechanism is through activation of α2 receptor/heat shock protein 70(HSP70)thereby attenuating NOD-like receptor-related protein 3(NLRP3)-mediated cellular pyroptosis.Methods Sixty-four SPF-grade C57/BL6 male mice,8-10 weeks old,weighing 24-26 g,were selected.According to the random number table method,they were divided into four groups(n=16):a sham-operated(Sham)group,a renal IR group,an IR+Dex group,and an IR+Dex+atipamezole(ATI)(IR+Dex+ATI)group.A renal IR injury model was established by clamping the bilateral renal clitoris for 45 min and then restoring blood perfusion for 48 h in all groups except the Sham group.In the IR+Dex group,50 μg/kg of Dex was intraperitoneally injected 30 min before clamping the renal clitoris and immediately after releasing the clamp,while 250 μg/kg of Dex was intraperitoneally injected at the same time in the IR+Dex+ATI group,and the other groups received the same amount of sterile normal saline.Then,blood samples and kidney tissues were collected from mice after 48 h of reperfusion.The serum creatinine(Cr)and urea nitrogen(BUN)levels were detected by an automatic biochemi-cal analyzer to evaluate the renal function of mice.The hematoxylin-eosin staining(H-E staining)was used to evaluate the renal patho-logical damage,the expression of HSP70 was detected by immunohistochemistry.The levels of HSP70,NLRP3,gasdermin D(GSDMD),caspase-1,apoptosis-associated speck-like protein(ASC),cleaved caspase-1,and the N terminal fragment of GSDMD protein(GSDMD-N)were detected by Western blot.The mRNA levels of HSP70,NLRP3,GSDMD,caspase-1,ASC,interleukin(IL)-1β,and IL-18 were detected by real-time fluorescence quantitative polymerase chain reaction(FQ-PCR).Results Compared with the Sham group,the IR group showed increases in serum Cr and BUN levels,renal injury scores,HSP70 positive rate,the mRNA levels of HSP70,NLRP3,GSDMD,caspase-1,ASC,IL-1β and IL-18,the protein levels of HSP70,NLRP3,GSDMD,caspase-1,GSDMD-N,cleaved caspase-1 and ASC(all P＜0.05).Compared with the IR group,the IR+Dex group presented decreases in serum Cr and BUN levels,renal injury scores,the mRNA levels of NLRP3,GSDMD,caspase-1,ASC,IL-1β and IL-18,the protein levels of NLRP3,GSDMD,caspase-1,GSDMD-N,cleaved caspase-1,and ASC(all P＜0.05),as well as increases in HSP70 protein levels(all P＜0.05).Compared with the IR+Dex group,the IR+Dex+ATI group showed increases in serum Cr and BUN levels,renal injury score,the mRNA levels of NLRP3,GSDMD,caspase-1,ASC,IL-1β and IL-18,the protein levels of NLRP3,GSDMD,caspase-1,GSDMD-N,cleaved caspase-1,and ASC(all P＜0.05);as well as decreases in HSP70 positive rate,and the mRNA and protein levels of HSP70(all P＜0.05).Conclusions Dex can alleviate renal IR injury,possibly by activating α2 receptors to upregulate HSP70,thereby inhibiting NLRP3 inflammasome activation and the cascade of pyroptosis-related reactions.
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