Mechanism of gut microbiota metabolite TMAO activating inflammatory pathway HMGB1/NLRP3 to promote cerebral ischemic penumbra damage in mice / 中风与神经疾病杂志

ABSTRACT

@#Objective To explore the mechanism of the gut microbiota metabolite trimethylamine-N-oxide （TMAO） acting on high mobility group box 1 （HMGB1）/NOD-like receptor protein 3 （NLRP3） to regulate inflammatory response after cerebral ischemia/reperfusion （I/R） injury in mice. Methods A mouse atherosclerosis model was established by feeding on TMAO and high-fat diet.A mouse model of middle cerebral artery occlusion （MCAO） was prepared using the suture method.Mice were randomly divided into sham group，2-week-TMAO-feeding group，and 6-week-TMAO-feeding group.After I/R injury，we measured the protein levels of NLRP3，HMGB1，cleaved interleukin-1β （Cle-IL-1β），and zonula occludens-1 （ZO-1） by Western blotting.After six weeks of TMAO feeding，mice were randomly divided into sham group，I/R group，TMAO+I/R group，and TMAO+DMB+I/R group.For each group，we scored neurological function，determined NLRP3，HMGB1，Cle-IL-1β，and ZO-1 protein expression by Western blot，measured brain infarct volume with TTC staining，and measured the water content of brain tissue. Results Compared with those of the sham group，NLRP3，HMGB1，and Cle-IL-1β protein expression increased significantly and ZO-1 decreased significantly with the length of TMAO feeding （all P<0.05）.Compared with the I/R group，the TMAO+I/R group showed a significant decline in neurological scores，significantly increased NLRP3，HMGB1，and Cle-IL-1β expression，significantly decreased ZO-1 expression，a significant increase in brain infarct volume，and a significant decrease in the water content of brain tissue （all P<0.05）.With DMB lowering TMAO，the TMAO+DMB+I/R group had significantly better neurological scores，significantly lower NLRP3，HMGB1，and Cle-IL-1β levels，a significantly increased ZO-1 level，and significantly reduced brain infarct volume and brain tissue water content，as compared with the TMAO+I/R group （all P<0.05）. Conclusion The gut microbiota metabolite TMAO can upregulate HMGB1/NLRP3-mediated inflammatory response in mice with cerebral I/R injury，worsening the breakdown of the blood-brain barrier to exacerbate brain tissue damage.