Study Of Correlation Between Gut Microbiome And Urinary Calcium Oxalate Stones

RESEARCH BACKGROUND AND PURPOSE: Urinary stones are a kind of common and frequent non-neoplastic diseases in the urinary system,among which upper urinary tract calcium oxalate stones are the most common.With the development of diagnostic technology and endoscopic technology,great progress has been made in the diagnosis and treatment of the disease,but its high prevalence and recurrence rate still bring a huge burden to patients and social economy.As a whole,gut microbiome has been confirmed to be closely related to a variety of diseases.This study takes gut microbiome as a breakthrough point and uses metabolomics analysis as a method to explore the correlation between gut microbiome and urinary calcium oxalate stones,to further explore the mechanism of the occurrence and development of urinary calcium oxalate stones.To provide a new theoretical basis for the prevention and treatment of urinary calcium oxalate stones.METHODS: Forty fecal samples were included in this study,including 20 patients with urinary calcium oxalate stones in the experimental group(RC group)and 20 healthy volunteers in the control group(NC group).The fecal samples of the experimental group and the control group were tested and analyzed by metabolomics analysis,and the differential metabolites between the experimental group and the control group were identified by the difference analysis between the two groups.The correlation analysis and KEGG function annotation analysis of the differential metabolites were performed to find out the differential metabolic pathways between the experimental group and the control group.RESULTS: There were 10 different metabolites between the experimental group and the control group,among which the expression of erucamide,saccharin,and hydroxyisocaproic acid was up-regulated in the experimental group,and the expression of DL-norvaline,N-Acetyl-L-tyrosine,thioetheramide-PC,gentisic acid,3,3-dimethylglutaric acid,lithocholic acid,and pyrocatechol was down-regulated.Correlation analysis showed that the expression of gentisic acid and pyrocatechol was highly positively correlated,and the expression of 3,3-dimethylglutaric acid and lithocholic acid was positively correlated.There was a negative correlation between gentisic acid and hydroxyisocaproic acid,3,3-dimethylglutaric acid and hydroxyisocaproic acid,3,3-dimethylglutaric acid and saccharin,lithocholic acid and hydroxyisocaproic acid,lithocholic acid and saccharin.KEGG pathway annotation and analysis showed that gentisic acid was involved in the tyrosine metabolism pathway,lithocholic acid was circulating in the human body as a secondary bile acid,and saccharin could stimulate the G protein-coupled receptors of the second family of taste receptors(T2R)to produce bitter taste.COUCLUSION: gentisic acid and lithocholic acid possibly play a role in preventing calcium oxalate stone formation by directly or indirectly regulating immune inflammatory response in the kidney,inhibiting oxidative stress response,and indirectly regulating lipid and glucose metabolism in the human body and kidney.This study confirmed that gentisic acid and lithocholic acid were low expressed in the metabolites of gut microbiome in the experimental group.The results showed that the two substances did not play a sufficient role in inhibiting urinary calcium oxalate stone formation in patients with stones.The decrease in the expression of saccharin in the experimental group may reflect the decrease in the expression of T2 R in the patient’s body,which makes the patient eat foods containing oxalates,leading to the increase of oxalate in the human body,and promoting the occurrence and development of urinary calcium oxalate stones.