Altered Gut Microbial Metabolism of Essential Nutrients in Primary Sclerosing Cholangitis.

BACKGROUND & AIMS: To influence host and disease phenotype, compositional microbiome changes, which have been demonstrated in patients with primary sclerosing cholangitis (PSC), must be accompanied by functional changes. We therefore aimed to characterize the genetic potential of the gut microbiome in patients with PSC compared with healthy controls (HCs) and patients with inflammatory bowel disease (IBD). METHODS: Fecal DNA from 2 cohorts (1 Norwegian and 1 German), in total comprising 136 patients with PSC (58% with IBD), 158 HCs, and 93 patients with IBD without PSC, were subjected to metagenomic shotgun sequencing, generating 17 billion paired-end sequences, which were processed using HUMAnN2 and MetaPhlAn2, and analyzed using generalized linear models and random effects meta-analyses. RESULTS: Patients with PSC had fewer microbial genes compared with HCs (P < .0001). Compared with HCs, patients with PSC showed enrichment and increased prevalence of Clostridium species and a depletion of, for example, Eubacterium spp and Ruminococcus obeum. Patients with PSC showed marked differences in the abundance of genes related to vitamin B6 synthesis and branched-chain amino acid synthesis (Qfdr < .05). Targeted metabolomics of plasma from an independent set of patients with PSC and controls found reduced concentrations of vitamin B6 and branched-chain amino acids in PSC (P < .0001), which strongly associated with reduced liver transplantation-free survival (log-rank P < .001). No taxonomic or functional differences were detected between patients with PSC with and without IBD. CONCLUSIONS: The gut microbiome in patients with PSC exhibits large functional differences compared with that in HCs, including microbial metabolism of essential nutrients. Alterations in related circulating metabolites associated with disease course, suggesting that microbial functions may be relevant for the disease process in PSC.

Vitamin B-12 status in infancy is positively associated with development and cognitive functioning 5 y later in Nepalese children.

Background: Poor vitamin B-12 (cobalamin) status is widespread in South Asia. Insufficient vitamin B-12 status has been linked to poor neurodevelopment in young children.Objective: We measured the associations between vitamin B-12 status in infancy (2-12 mo) and the development and cognitive functioning in Nepalese children 5 y later.Design: Vitamin B-12 status was assessed in infancy with the use of plasma cobalamin, total homocysteine (tHcy), and methylmalonic acid (MMA). At 5 y of age, we measured development with the use of the Ages and Stages Questionnaire, 3rd edition (ASQ-3), and cognitive functioning by using the Developmental Neuropsychological Assessment, 2nd edition (NEPSY II), in 320 children. In regression models, we estimated the associations between vitamin B-12 status, including a combined indicator of vitamin B-12 status (3cB12) and scores on the ASQ-3 and NEPSY II subtests.Results: All markers of vitamin B-12 status with the exception of plasma cobalamin were significantly associated with the total ASQ-3 scores in the multiple regression models. A 1-unit increase in the 3cB12 score was associated with an increase in the total ASQ-3 score of 4.88 (95% CI: 2.09, 7.68; P = 0.001). Increases in both plasma tHcy and MMA (indicating poorer status) were associated with a decrease in scores on the NEPSY II affect recognition and geometric puzzle subtests. Each unit increment in 3cB12 scores was associated with increases of 0.82 (95% CI: 0.49, 1.14; P < 0.0005), 0.59 (95% CI: 0.10, 1.09; P = 0.020), and 0.24 (95% CI: 0.02, 0.47; P = 0.035) in the affect recognition, geometric puzzle, and block construction scores, respectively.Conclusions: Vitamin B-12 status in infancy is associated with development and performance on social perception tasks and visuospatial abilities at 5 y of age. The long-term effects of poor vitamin B-12 status in infancy need further investigation in randomized controlled trials.