Screening And Mechanism Investigation Of Probiotic Strains For Their Hypertension-preventive Effects

With the development of society,the incidence of hypertension keeps increasing,which has brought a burden to the social medical system.Previous studies have shown that the elevated vascular reactive oxygen species(ROS)can raise blood pressure and promote vascular fibrosis and hypertrophy,thus accelerating the development of hypertension.Recent studies have shown that gut microbial dysbiosis can also promote hypertension.Therefore,antioxidative ability and intestinal flora can be selected as targets for the prevention of hypertension.It had been reported that probiotics could enhance antioxidative ability and helped to eliminate ROS.In addition,probiotics can also help to modulate gut microbiome.Therefore,probiotics with antioxidative properties are likely to prevent the formation of hypertension.In this study,probiotic strains with antioxidative properties were screened through in vitro experiments and their hypertension-preventive effects were tested on animal models.Finally the underlying mechanisms of their hypertension-preventive effects were also investigated.1.Antioxidative probiotics were screened with A7R5 cell model.A total of 62 probiotic strains were tested,9 of which could significantly reduce ROS in A7R5 cells.Among them,Bifidobacterium longum CCFM752 and Lactobacillus casei FNMHLBE25M1 could inhibit NADPH oxidase activation,thus inhibiting superoxide anion(O2^·-)generation;L.casei FNMHLBE25M1 and Lactobacillus plantarum CCFM1149 could increase intracellular total SOD activity and help to scavenge O2^·-;Bifidobacterium bifidum FJSWX9M8 and FNT16-2,B.longum CCFM752,L.casei FNMHLBE25M1,and L.plantarum CCFM1149,CCFM10,CCFM239 and CCFM639 could enhance intracellular CAT activity and help to degrade hydrogen peroxide.2.To test the hypertension-preventive effects of probiotics,spontaneously hypertensive rats(SHR)were selected as animal model,and their effects on vascular remodeling,endothelial NO synthetic ability,and antioxidative ability were also evaluated.Among these probiotics,B.longum CCFM752 and L.plantarum CCFM1149 could eliminate O₂^·-and hydrogen peroxide in A7R5 cells,and L.plantarum CCFM10 could only decrease hydrogen peroxide,while B.longum CCFM666 and L.plantarum L86 did not show obvious antioxidative effects.Results showed that B.longum CCFM752 prevented the development of hypertension and aortic remodeling,and promoted the aortic endothelial NO synthetic ability and antioxidative ability.Although L.plantarum CCFM10 prevented the development of hypertension,it failed to prevent the aortic remodeling or enhance the NO synthetic ability and antioxidant capacity.L.plantarum CCFM1149 failed to prevent hypertension,but prevented aortic fibrosis and enhanced aortic antioxidative ability.In contrast,B.longum CCFM666 and L.plantarum L86 could not prevent hypertension or aortic remodeling,and failed to increase endothelial NO synthetic ability and antioxidant capacity in SHR.3.The underlying mechanisms of hypertension-preventive effects of B.longum CCFM752 were explored.The influence of CCFM752 on host metabolism was analyzed through serum metabolomics.Results showed that B.longum CCFM752 significantly upregulated proline and pyridoxamine 5'-phosphate,both of which are negatively correlated with blood pressure and positively correlated with antioxidative capacity and endothelial nitric oxide synthase activity.The influence of CCFM752 on intestinal microbiome was tested by analyzing fecal microbiome.Results showed that CCFM752 recovered the microbial?-diversity and the phylum level of Actinobacteria,and significantly upregulated 9 bacterial genera that are negatively correlated with blood pressure,including Lactobacillus and Bifidobacterium,and also down-regulated Turicibacter.Spearman's correlation analysis showed that among the 4 metabolites changed by CCFM752,proline and pyridoxamine 5'-phosphate were correlated with bacterial genera associated with blood pressure,and the rest two of them could not correlate with any genus.This indicated that CCFM752 may partially change metabolism,antioxidative capacity,endothelial nitric oxide synthesis,as well as blood pressure through modulating gut microbiome,and it may also influence metabolism and blood pressure in other ways simultaneously.