Chronic kidney disease (CKD) is progressive loss in renal function that afflicts approximately 25 million adults in the United States alone, with the majority remaining undiagnosed. Our current study found distinctive microbiota features associated with CKD status were found in specific oral locations. A combination of some of those taxa features was reasonably predictable of the CKD status suggesting a sampling from specific oral locations as a potential noninvasive test to identify individuals with or at risk of developing CKD.

Taxonomic representation of statistically and biologically consistent differences between each environmental chemical treatment and controls at postnatal day 62 rats. Cladogram plots present the Lefse results on gut microbiome of environmental chemical treated rats and controls at postnatal day 62. Differences are represented in the color for the most abundant class (red indicating increase, green indicating reduction). Each circle’s diameter is proportional to the taxon’s relative abundance.

This proof-of-principle study examines whether postnatal, low-dose exposure to environmental chemicals modifies the composition of gut microbiome. Three chemicals that are widely used in personal care products—diethyl phthalate (DEP), methyl paraben (MPB), triclosan (TCS) — and their mixture (MIX), were administered at doses comparable to human exposure to Sprague-Dawley rats from birth through adulthood. Fecal samples were collected at two time points: postnatal day (PND) 62 (adolescence) and PND 181 (adulthood). The gut microbiome was profiled by 16S rRNA gene sequencing, taxonomically assigned and assessed for diversity.

Metagenomic profiling revealed that the low-dose chemical exposure resulted in significant changes in the overall bacterial composition, but in adolescent rats only. Specifically, the individual taxon relative abundance for Bacteroidetes (Prevotella) was increased while the relative abundance of Firmicutes (Bacilli) was reduced in all treated rats compared to controls. Increased abundance was observed for Elusimicrobia in DEP and MPB groups, Betaproteobacteria in MPB and MIX groups, and Deltaproteobacteria in TCS group. Surprisingly, these differences diminished by adulthood (PND 181) despite continuous exposure, suggesting that exposure to the environmental chemicals produced a more profound effect on the gut microbiome in adolescents. We also observed a small but consistent reduction in the bodyweight of exposed rats in adolescence, especially with DEP and MPB treatment (p < 0.05), which is consistent with our findings of a reduced Firmicutes/Bacteroidetes ratio at PND 62 in exposed rats.

This study provides initial evidence that postnatal exposure to commonly used environmental chemicals at doses comparable to human exposure is capable of modifying the gut microbiota in adolescent rats; whether these changes lead to downstream health effects requires further investigation.

The relative abundance of Barnesiellaceae and Blautia in PSC and non-PSC-IBD at multiple locations. Boxplots (left panel) show the mean and variance of the relative abundance; Dot plots (right panel) show the relative abundance for each individual samples and the lines link the samples from the same subject. Green: non-PSC IBD; blue: PSC.

A recent research with collaboration with SHARE  explored the mucosa-associated microbiota in primary sclerosing cholangitis (PSC) patients across different locations in the gut, and to compare it with inflammatory bowel disease (IBD)-only patients and healthy controls. We found that the overall microbiota profile was similar across multiple locations in the gut from the same individual regardless of disease status. In this study, the mucosa associated-microbiota of patients with primary sclerosing cholangitis was characterised by enrichment of Blautia andBarnesiellaceae and by major shifts in operational taxa units within Clostridiales order.

Full text