Alterations of the salivary and fecal microbiome in patients with primary sclerosing cholangitis.

BACKGROUND: Primary sclerosing cholangitis (PSC) is a chronic, progressive liver disease known for its frequent concurrence with inflammatory bowel disease. PSC can progress to cirrhosis, end-stage liver disease, hepatobiliary cancer, and/or colorectal cancer. The etiopathogenesis of PSC remains poorly understood, and, as such, pharmacotherapy has yet to be definitively established. Little is known about the salivary microbiome in PSC and PSC-IBD. This study aimed to evaluate the oral microbiome of patients with PSC, with association to these patient's fecal microbial composition. METHODS: Saliva, fecal samples and Food Frequency Questionnaires were collected from 35 PSC patients with or without concomitant inflammatory bowel disease and 30 age- and BMI-matched healthy volunteers. 16S rRNA gene sequencing was performed using Illumina MiSeq platform. RESULTS: The salivary microbial signature of PSC was significantly altered as compared to healthy controls, independent of concomitant IBD, and was comprised of 19 significantly altered species, of which, eight species were consistently overrepresented in both fecal and saliva of patients with PSC, including Veillonella, Scardovia and Streptococcus. CONCLUSIONS: PSC is characterized by microbial dysbiosis in the gut and the salivary microbiome, independently from IBD. The PSC dysbiotic signature includes a reduction in autochthonous bacteria and an increased relative abundance of pathogenic bacteria, including an invasion of oral bacteria to the gut. PSC is a strong modulator of the microbial profile, in the gut and the oral microbiome. These results may lead to the development of biomarkers for screening and early diagnosis or the development of personalized medicine in PSC.

p53 is required for brown adipogenic differentiation and has a protective role against diet-induced obesity.

Proper regulation of white and brown adipogenic differentiation is important for maintaining an organism's metabolic profile in a homeostatic state. The recent observations showing that the p53 tumor suppressor plays a role in metabolism raise the question of whether it is involved in the regulation of white and brown adipocyte differentiation. By using several in vitro models, representing various stages of white adipocyte differentiation, we found that p53 exerts a suppressive effect on white adipocyte differentiation in both mouse and human cells. Moreover, our in vivo analysis indicated that p53 is implicated in protection against diet-induced obesity. In striking contrast, our data shows that p53 exerts a positive regulatory effect on brown adipocyte differentiation. Abrogation of p53 function in skeletal muscle committed cells reduced their capacity to differentiate into brown adipocytes and histological analysis of brown adipose tissue revealed an impaired morphology in both embryonic and adult p53-null mice. Thus, depending on the specific adipogenic differentiation program, p53 may exert a positive or a negative effect. This cell type dependent regulation reflects an additional modality of p53 in maintaining a homeostatic state, not only in the cell, but also in the organism at large.