Dysbiosis And Resilience Of Gut Microbiota In Patients With Ischemic Stroke And The Gut Microbial Function Prediction

BackgroundIschemic stroke is the most common cerebrovascular disease,nearly seventy percent stroke are ischemic stroke in China.Ischemic stroke is a high morbidity,high recurrence rate,high disability rate and high mortality disease that has a serious impact on the citizen's health and life.Mountains of risk factors have been proven to involve in the process of ischemic stroke,and recent studies indicated that the gut microbiota might be a new risk factor for ischemic stroke.Current studies have reported the gut microbiota influence on occurrence and prognosis of ischemic stroke via microflora metabolites or immunization.A previous study indicated that the gut microbiota were obvious dysbiosis in patients with large-artery atherosclerotic stroke or transient ischemic attack and the degree of dysbiosis was related to the severity of ischemic stroke.However,studies about acute ischemic stroke patients' gut microbiota are limited,whether the results are repeatable are still unknown.Whether the dysbiosis of gut microbiota after stroke will return to pre-stroke level and,if so,when it will recover is still unknown.What's more,whether the dysbiosis of gut microbiota in stroke patients would influence the microbial functions is unknown either.PurposeIn this study,to explore the characteristics and recovery of gut microbiota in patients with acute ischemic stroke,16S rRNA gene sequencing technology was used.Next,we used Phylogenetic Investigation of Communities by Reconstruction of Unobserved States(PICRUSt)to predict the gut microbial functions of ischemic stroke patients.MethodsTwenty-eight patients with non-cardiogenic acute ischemic stroke were included and fecal samples were collected as more times as possible.According to the interval between stroke onset and the time of fecal samples collection,we divided them into four groups,namely T1 group(1-4 day),T2 group(5-7 day),T3 group(8-20 day)and T4 group(29-119 day).Twenty-eight healthy volunteers were included as healthy controls,and their clinical data and fecal samples were collected.Bacterial DNA in fecal samples were extract and the V4 variable region were amplified via polymerase chain reaction(PCR),then the PCR products were mixed together and send to Illumina platform for sequencing.ResultsCompared to healthy control group(HC),acute ischemic stroke(AIS)patients showed a higher phylogenetic diversity(P=0.002)and the gut microbial community was significantly different(P<0.001).Stroke patients had more opportunistic pathogens,such as Enterobacteriaceae,Bradyrhizobiaceae and Clostridia,and fewer commensal or beneficial genera such as Bacteroides,Prevotella and Fusobacterium.There was no significant difference among T1 group,T2 group and T3 group in gut microbial diversity and community composition,which meant the dysbiosis of gut microbiota in acute ischemic stroke patients would last more than 3 weeks.The gut microbial alpha diversity in T4 was significantly lower than other groups,the gut microbial composition between T4 and HC group was similar,but the beta diversity between T4 and HC group was still significant difference(P<0.001).These results indicated 4 weeks after onset,the gut microbiota in stroke patients began to restore.According to PICRUSt analysis,in the level two,thirty-five out of 41 KEGG pathways showed increased abundance and 2 out of 41 showed decreased abundance in acute ischemic stroke patients(false discovery rate,q<0.05),which related to cardiovascular diseases,nervous system,metabolic diseases,digestive system and so on.Trimethylamine-N-Oxide(TMAO)is a vital risk factor for cardiovascular diseases,but its role in cerebrovascular diseases was still unknown.We found 6909 KO genes in total,among which 35 genes were correlated with choline,betaine,carnitine and trimethylamine metabolism.Within these genes,twenty-one KOs differed significantly between AIS and HC group.Regrettably,TMAO levels of the acute ischemic stroke patients included in this study were undetected.The changed KEGG pathways and the genes related to TMAO were showed a degree of recovery 4 weeks after onset.ConclusionAcute ischemic stroke patients showed significant dysbiosis of gut microbiota and the dysbiosis lasted more than 3 weeks.Four weeks after onset,the gut microbiota in ischemic stroke patients began to restore,but the alpha diversity declined.The gut microbial function significantly changed in acute ischemic stroke patients,which relate to nervous system,cardiovascular system and other systems or pathways,including the genes relate to TMAO.Whether the dysbiosis of gut microbiota and microbial functions after stroke will completely return to pre-stroke level and the meaning of TMAO to ischemic stroke patients need further studies to explore.