Effects of gut microbiota metabolite TMAO on neuroinflammation and neurovascular unit damage in stroke mice based on NLRP3 signaling pathway
Objective To investigate the effects of the gut microbiota metabolite trimethylamine N-oxide(TMAO)on neuroinflammation and neurovascular unit damage in mice with cerebral infarction based on the NOD-like receptor pro-tein 3(NLRP3)signaling pathway.Methods Totally 120 male C57 mice were fed a high-fat diet containing 1％choline for 6 weeks and then were randomly divided into the sham operation(Sham)group,ischemia/reperfusion(I/R)group,and TMAO+I/R group,with 40 mice in each group.Mice in the Sham and I/R groups were fed the normal diet with puri-fied water,while mice in the TMAO+I/R group received the high-fat diet with 0.12％TMAO in drinking water.After 6 weeks,we established the middle cerebral artery occlusion(MCAO)models in the I/R and TMAO+I/R groups,and mice in the Sham group received a sham surgery.At 24 h after reperfusion in the I/R group and the TMAO+I/R group,and at the same time period in the Sham group,the degree of neurological deficit was evaluated using the Longa scoring method.The complete brain tissues were taken out.Western blotting was used to detect the expression levels of inflamma-tory proteins NLRP3,Cleaved-Caspase-1,Cleaved-IL-1β,and tight junction protein ZO-1.The TTC staining method was used to analyze the percentage of cerebral infarction volume,and the water content of brain tissue was measured and the cerebral blood flow was monitored.Results Compared with the Sham group,the Longa scores and the relative expres-sion levels of NLRP3,Cleaved-Caspase-1,and Cleaved-IL-1β proteins in the brain tissues increased in the I/R group and the TMAO+I/R group,while the relative expression level of ZO-1 protein in the brain tissues decreased(all P<0.05);the cerebral blood flow on both sides and the ratio of cerebral blood flow on the left to that on the right decreased in the I/R group and the TMAO+I/R group(all P<0.05);the percentage of cerebral infarction volume and the water content of brain tissues increased in the I/R group and the TMAO+I/R group(all P<0.05).Compared with the I/R group,the Longa score and the relative expression levels of NLRP3,Cleaved-caspase-1,and Cleaved-IL-1β proteins in the brain tissues increased in the TMAO+I/R group,while the relative expression level of ZO-1 protein decreased(all P<0.05);the cere-bral blood flow on both sides and the ratio of cerebral blood flow on the left to that on the right decreased in the TMAO+I/R group(all P<0.05);the percentage of cerebral infarction volume and the water content of the brain tissues increased in the TMAO+I/R group(all P<0.05).Conclusion The gut microbiota metabolite TMAO can promote neuroinflammation and neurovascular unit damage in mice with cerebral infarction by up-regulating the NLRP3 inflammasome-mediated inflammatory response,resulting in irreversible neurological damage.
cerebral infarctiontrimethylamine oxideNLRP3 inflammasomeneuroinflammationneurovascular unit damagemice
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