Effects And Mechanism Research Of PSRC1 Against Atherosclerosis Based On The Gut Microbiota And Microbial Metabolites

BackgroundProline/serine-rich coiled-coil protein 1(PSRC1),a microtubule-related protein,plays a crucial role in the process of cell mitosis and growth.PSRC1 has been previously reported to be strongly linked to lipid metabolism,the severity of coronary stenosis and the susceptibility to coronary artery disease.Our previous work showed that overexpression of PSRC1 slowed the development of atherosclerosis by inhibiting foam cell formation and inflammation in high-fat diet apoE-/-mice.The gut microbiota is a very complex microbial community with complex composition and function.Dysbiosis mainly affects atherosclerosis by aggravating inflammatory response,interfering with lipid metabolism and producing various metabolites.Accumulating studies have confirmed that the composition of gut microbiota and microbial metabolites varied significantly with the severity of coronary heart disease.Trimethylamine-N-oxide(TMAO),a gut microbiota-dependent metabolite derived from choline-riched substances in food,holds the characteristics of inhibiting reverse cholesterol transport,promoting the formation of foam cells and promoting inflammation.Plasma levels of TMAO have been demonstrated a significant association with the risk of major cardiovascular events.Given that PSRC1 involves in regulating immune-inflammatory response,and maladaptive inflammatory and immune responses are responsible for intestinal barrier integrity and function dysregulation,we hypothesized whether the atherosclerosis-protective role of PSRC1 is related to the regulation of gut microbiota and microbial metabolites.To this end,we constructed PSRC1-/-apoE-/-mice to clarify the role and mechanism underlying PSRC1-mediated gut microbiota,TMAO and atherosclerosis progression.Methods and Results1.The role of PSRC1 in the development of atherosclerosisUsing western blot,RT-PCR,immunohistochemistry and immunofluorescence,we investigated the expression of PSRC1 in TMAO-induced atherosclerosis in vivo and in vitro.The study found that TMAO treatment caused an increase in atherosclerotic plaque areas and a reduced expression of PSRC1 in macrophages.2.Effect of PSRC1 on the gut microbiota and TMAOUsing metagenomics,RNA-seq,untargeted metabolomics,liquid chromatography mass spectrometry(LC-MS)and other experimental methods,we investigated the influence of PSRC1 knockdown on mouse gut microbial composition and function,hepatic FMO3 expression,plasma metabolites and colonic inflammatory microenvironment.Fecal bacteria transplantation was used to further explore the effect of gut microbial dysbiosis on atherosclerosis.The study found that PSRC1 deletion could increase the enrichment of TMA-producing bacteria and TMAO synthesis pathways,upregulate the expression of hepatic FMO3 and thus increase the levels of TMAO and its precursor betaine.Gavage with fecal suspension from PSRC1-knockout mice increased plasma TMAO levels and promoted atherosclerosis progression in recipients.3.Mechanisms underlying PSRC1 against atherosclerosis via manipulating TMAO1)Oil red O staining,immunofluorescence and Nile red staining were used to detect the effect of PSRC1 deficiency on the progression of atherosclerosis.2)RAW264.7 cells transfected with the targeting PSRC1-overexpressed adenovirus and BMDMs isolated from PSRC1-/-mice were used as the research objects,and the effect of PSRC1 on cholesterol accumulation and inflammatory genes expression in TMAO-induced macrophages were observed.The study found that PSRC1 knockout further aggravates TMAO-induced atherosclerosis by promoting foam cells formation in macrophages and inflammatory response in animals.Furthermore,knockdown of PSRC1 increased TMAO-mediated macrophage cholesterol uptake and inflammatory gene expression in cultured cells.In contrast,knockdown of PSRC1 inhibited the reverse cholesterol transport in macrophages,which could be attributed to the suppression of LXRα,while overexpression of PSRC1 displayed the opposite phenotype.ConclusionsThis study suggested that PSRC1 inhibited atheroscleosis by regulating the gut microbiota and microbial metabolite TMAO pathways.Our work also revealed an interactive regulation between PSRC1 and TMAO:PSRC1 inhibited TMAO-induced cholesterol accumulation and inflammatory response.Deficiency of PSRC1 could promote the generation of TMAO,and overexpression of PSRC1 and reduced TMAO consumption could further alleviate atherosclerosis.Conversely,increasing TMAO inhibits PSRC1 expression and thus promotes atherosclerosis development.