Diet-induced cholestasis modifies the maternal gut metabolome and microbiota, resulting in offspring metabolic impairment, altered intestinal metabolites and bacteria.

摘要

Background: Pregnancy is associated with a change in the gut microbiome by the third trimester. Gut microbiota influence enterocyte signals that impact susceptibility to metabolic disorders, for example diabetes mellitus. Bile acids influence microbial growth, thus intestinal bile acid exposure in pregnancy may contribute to metabolic impairments observed in cholestatic pregnancy. The initial offspring microbiota is largely determined by the maternal microbiota, with inheritance in utero, at delivery, via lactation and in the shared environment of early neonatal life. The offspring of cholestatic pregnancies demonstrate metabolic impairments; in a mouse model of cholestasis, female pups had impaired glucose tolerance and dyslipidaemia when challenged with a Western diet. Similarly, the 16 year old children of mothers with intrahepatic cholestasis of pregnancy had raised BMI and fasting insulin (boys), higher hip and waist girth (girls), and lower fasting HDL cholesterol (girls) than the children of uncomplicated pregnancies in the North Finland Birth Cohort. We hypothesise that the offspring of cholestatic pregnancies develop an abnormal gut microbial and metabolite composition secondary to maternal alterations, contributing to phenotype of the offspring. Methods: C57BL/6 female mice were fed normal chow or 0.5% cholic acid-supplemented diets and subsequently mated. Their offspring were fed normal chow or Western diets. Ultra-performance liquid chromatography - mass spectrometry was used to assess the caecal metabolome. 16S rRNA sequencing was performed to determine the caecal microbiota. Results were compared using OPLS-DA, PCA, NMDS, and t-tests with Benjamini-Hochberg correction for multiple measures. Results: Supplementation of the maternal diet with cholic acid significantly alters the maternal microbiota with a similar effect to that of normal pregnancy, enhancing the abundance of Bacteroidetes and sulphur-utilising bacteria, with an associated reduction in microbial richness and diversity. Adult offspring of cholic acid fed mothers, when challenged with a Western diet, had increased susceptibility to obesity, impaired glucose tolerance, dyslipidaemia and hepatosteatosis. This phenotype was more marked in the female offspring. The offspring microbiota was significantly affected by maternal and neonatal diet, with a gender difference in the microbial composition revealed in the pups of mothers fed cholic acid when fed a Western diet. The female offspring of cholic acid fed mothers had a higher abundance of Alistipes, a bile-resistant member of the Bacteroidetes phylum, than males. Interestingly, this group had lower caecal bile acids (p = 0.036) than from normally-fed mothers when challenged with a Western diet, particularly deoxycholic acid, cholic acid and ω-muricholic acid. Conclusions: Pregnancy and cholic acid feeding have similar impacts upon the composition of the gut microbiome and metabolome. Maternal cholic acid feeding results in increases in bile-resistant bacteria in the caecum of female offspring. A gender difference in the microbiome and bile acid content of the caecum is revealed by a Western diet. Together, these findings demonstrate how the establishment of the offspring gut microbiome, and associated metabolome is influenced by an altered maternal environment, contributing to an increased long-term risk of metabolic impairment.