The Association Between Ambient Temperature And Blood Pressure And The Mediating Effect Of Gut Microbiota

BackgroundHypertension is a group of clinical symptoms with persistently elevated blood pressure(BP),which can significantly increase the risk of cardiovascular disease morbidity and mortality.With the rapid development of China’s economy and rapid changes of social lifestyle and behavior,the prevalence of hypertension is increasing year by year.Previous studies have shown that lower temperature was associated with higher BP,cold ambient temperature led to marked changes in the gut microbiota composition,and the development of hypertension was closely related gut microbiota.However,there was limited epidemiological evidence on the effects of temperature exposure on gut microbiota,and exploring whether gut microbiota is a possible biological mechanism of temperature affecting BP.ObjectiveTo investigate the relationship among ambient temperature,BP,the diversity and composition of gut microbiota and the mediating effect of intestinal microbiota on the association of temperature affecting BP.MethodsFrom October 2015 to February 2016,a multi-stage cluster sampling method was used to obtained subjects(5 952)from the Guangdong Gut Microbiome Project.The data collected included socioeconomic characteristics,health status,dietary status,physical examination,blood biochemical test and gut microbiota information.Daily meteorological data from weather station were matched with participants’ residential addresses and the date of fecal sampling.We first used the distributed lag nonlinear model to establish the exposure-response relationship between daily average temperature and BP,the exposure-response relationship among temperature and gut microbiota α diversity,relative richness of four dominant phylum.Principal coordinate analysis based on a similarity matrix of genera abundance were used to explore the effect of temperature on gut microbialβ-diversity.And then we preformed multivariate association analyses to identify associations between ambient temperature and gut microbial genera.Generalized additive model was conducted to analyze the relationship among gut microbial α-diversity,phylum/genera composition and BP.Finally,we used mediation analysis to explore the possible mediating effect of gut microbiota on the association between temperature and BP.Results1.The exposure-response curves of temperature and BP were approximately negative parabola.When daily average temperature increased by 10℃,systolic BP(SBP),diastolic BP(DBP),Pulse pressure(PP)and Mean arterial pressure(MAP)decreased by 6.3(95% CI: 5.3,7.4),2.2(95%CI: 1.6,2.8),4.2(95%CI: 3.3,5.0)and 3.6(95%CI: 2.9,4.3)mm Hg,respectively.2.The exposure-response curve of daily average temperature and gut microbial α-diversity of Shannon,Chao1,Observed Species,PD Whole Tree liked U-shaped.Ambient temperature was significantly distinguished with respect to principal coordinates based on a similarity matrix of genera abundance.Ambient temperature was negatively associated with Phylum Firmicutes,and positively associated with Phylum Bacteroidetes and Proteobacteria.When participants were exposed to cold temperature,gut microbiota was characterized by increased levels of SMB53,Clostridium1,Dialister,Ruminococcus2,Butyricicoccus,Roseburia,Ruminococcus,Dorea,Clostridium2,Turicibacter,Clostridium5,cc＿115,YRC22 and Desulfovibrio and reduced levels of Escherichia,Klebsiella,Herbaspirillum,Ralstonia,Sutterella,Bradyrhizobium,Bacteroides,Sediminibacteriu and Butyricimonas.3.The decreases in α-diversity of Shannon,Chao1,and Phylum Bacteroidetes and the increase in Phylum Firmicutes were associated with higher BP.At genus level,the Turicibacter,Streptococcus,Lachnospira,Prevotella,SMB53 with higher relative abundance,while Bacteroides,Akkermansia,Parabacteroides,Alistipes,Butyricimonas,Coprobacillus with lower relative abundance were associated with higher BP.4.Phylum Firmicutes and genera SMB53,Turicibacter,Prevotella,Ruminococcus,Butyricimonas,Bacteroides,Parabacteroides,Alistipes and Phascolarctobacterium were the mediating variable of the temperature affecting BP.Conclusion1.The reverse relationships between ambient temperature and several BP indicators suggest it should be considered in clinical/community manage of hypertension.2.Ambient temperature significantly contributes to the intestinal microbiome α-and β-diversity.Ambient temperature was negatively associated with Phylum Firmicutes and energy metabolizing bacteria,and positively associated with Phylum Bacteroidetes,Proteobacteria,acetate-,butyrate-producing bacteria.Ambient temperature led to marked changes in the gut microbiota composition.3.The decreases in intestinal microbiome α-diversity and Phylum Bacteroidetes,acetate-,butyrate-producing and obesity reducing bacteria,and the increases in Phylum Firmicutes and opportunistic bacteria significantly contribute to higher BP.4.Phylum Firmicutes,the acetate,butyrate-and lactate-producing bacteria,obesity reducing bacteria and opportunistic bacteria are the mediators of temperature affecting BP.