No abstract

Background and Aims The 7α-dehydroxylation of primary bile acids (BAs), chenodeoxycholic (CDCA) and cholic acid (CA) into the secondary BAs, lithocholic (LCA) and deoxycholic acid (DCA) is a key function of the gut microbiota. We aimed to study the linkage between fecal BAs and gut microbiota in cirrhosis since this could help understand cirrhosis progression. Methods Fecal microbiota were analyzed by culture-independent multitagged-pyrosequencing, fecal BAs using HPLC and serum BAs using LC-MS in controls, early (Child A), and advanced cirrhotics(Child B/C). A subgroup of early cirrhotics underwent BA and microbiota analysis before/after eight weeks of rifaximin. Results Cross-sectional: 47 cirrhotics(24 advanced) and 14 controls were included. In feces, advanced cirrhotics had the lowest total, secondary, secondary/primary BA ratios, and highest primary BAs compared to early cirrhotics and controls. Secondary fecal BAs were detectable in all controls but in a significantly lower proportion of cirrhotics (p<0.002). Serum primary BAs were higher in advanced cirrhotics compared to the rest. Cirrhotics, compared to controls, had a higher Enterobacteriaceae (potentially pathogenic) but lower Lachonospiraceae, Ruminococcaceae and Blautia (7α-dehydroxylating bacteria) abundance. CDCA was positively correlated with Enterobacteriaceae(r=0.57, p<0.008) while Ruminococcaceae were positively correlated with DCA(r=0.4, p<0.05). A positive correlation between Ruminococcaceae and DCA/CA (r=0.82, p<0.012) and Blautia with LCA/CDCA (r=0.61, p<0.03) was also seen. Prospective study: Post-rifaximin, six early cirrhotics had reduction in Veillonellaceae and in the secondary/primary BA ratios. Conclusions Cirrhosis, especially advanced disease, is associated with a decreased conversion of primary to secondary fecal BAs which is linked with abundance of key gut microbiome taxa.

Centenarians, or individuals who have lived more than a century, represent the ultimate model of successful longevity associated with decreased susceptibility to ageing-associated illness and chronic inflammation [1][2][3] . The gut microbiota is considered to be a critical determinant of human health and longevity [4][5][6][7][8] . Here we show that centenarians (average 107 yo) have a distinct gut microbiome enriched in microbes capable of generating unique secondary bile acids, including iso-, 3-oxo-, and isoallo-lithocholic acid (LCA), as compared to elderly (85-89 yo) and young (21-55 yo) controls. Among these bile acids, the biosynthetic pathway for isoalloLCA had not been described previously. By screening 68 bacterial isolates from a centenarian's faecal microbiota, we identified Parabacteroides merdae and Odoribacteraceae strains as effective producers of isoalloLCA. Furthermore, we generated and tested mutant strains of P. merdae to show that the enzymes 5a-reductase (5AR) and 3bhydroxysteroid dehydrogenase (3bHSDH) were responsible for isoalloLCA production. This secondary bile acid derivative exerted the most potent antimicrobial effects among the tested bile acid compounds against gram-positive (but not gram-negative) multidrug-resistant pathogens, including Clostridioides difficile and vancomycin-resistant Enterococcus faecium.These findings suggest that specific bile acid metabolism may be involved in reducing the risk of pathobiont infection, thereby potentially contributing to longevity. MainThe microbiome has long been recognized as a key player in determining the health status of ageing individuals through its role in controlling digestive functions, bone density, neuronal activity, immunity, and resistance to pathogen infection [9][10][11][12][13] . Microbial consortia in elderly individuals often show increased interindividual variability and reduced diversity, and are thus being linked to immunosenescence, chronic systemic inflammation, and frailty 6,14 . An integrated understanding of the dynamic balance and functions of microbial members with respect to ageing is essential for establishing a strategy toward rational manipulation of the microbiota for restoring and/or maintaining tissue homeostasis and overall health.Centenarians (aged 100 years and older) are known to be less susceptible to age-related diseases including hypertension, diabetes, obesity, and cancer 3,15 . Moreover, centenarians have likely survived periods of hunger and several bouts with infectious diseases such as influenza, tuberculosis, shigellosis, and salmonellosis 16 . It has been postulated that there are centenarian-specific members of the gut microbiota which, rather than representing a mere consequence of ageing, might actively contribute to maintaining homeostasis, resilience, and healthful ageing [4][5][6]8 . In this study, we aimed

CHIP is a U-box-type ubiquitin ligase that induces ubiquitylation and degradation of its substrates, which include several oncogenic proteins. The relationship between CHIP and tumour progression, however, has not been elucidated. Here, we show that CHIP suppresses tumour progression in human breast cancer by inhibiting oncogenic pathways. CHIP levels were negatively correlated with the malignancy of human breast tumour tissues. In a nude mouse xenograft model, tumour growth and metastasis were significantly inhibited by CHIP expression. In contrast, knockdown of CHIP (shCHIP) in breast cancer cells resulted in rapid tumour growth and metastastic phenotypes in mice. In cell-based experiments, anchorage-independent growth and invasiveness of shCHIP cells was significantly elevated due to increased expression of Bcl2, Akt1, Smad and Twist. Proteomic analysis identified the transcriptional co-activator SRC-3 (refs 13, 14, 15, 16, 17, 18, 19) as a direct target for ubiquitylation and degradation by CHIP. Knocking down SRC-3 in shCHIP cells reduced the expression of Smad and Twist, and suppressed tumour metastasis in vivo. Conversely, SRC-3 co-expression prevented CHIP-induced suppression of metastasis formation. These observations demonstrate that CHIP inhibits anchorage-independent cell growth and metastatic potential by degrading oncogenic proteins including SRC-3.

Alcohol abuse with/without cirrhosis is associated with an impaired gut barrier and inflammation. Gut microbiota can transform primary bile acids (BA) to secondary BAs, which can adversely impact the gut barrier. The purpose of this study was to define the effect of active alcohol intake on fecal BA levels and ileal and colonic inflammation in cirrhosis. Five age-matched groups {two noncirrhotic (control and drinkers) and three cirrhotic [nondrinkers/nonalcoholics (NAlc), abstinent alcoholic for >3 mo (AbsAlc), currently drinking (CurrAlc)]} were included. Fecal and serum BA analysis, serum endotoxin, and stool microbiota using pyrosequencing were performed. A subgroup of controls, NAlc, and CurrAlc underwent ileal and sigmoid colonic biopsies on which mRNA expression of TNF-α, IL-1β, IL-6, and cyclooxygenase-2 (Cox-2) were performed. One hundred three patients (19 healthy, 6 noncirrhotic drinkers, 10 CurrAlc, 38 AbsAlc, and 30 NAlc, age 56 yr, median MELD: 10.5) were included. Five each of healthy, CurrAlc, and NAlc underwent ileal/colonic biopsies. Endotoxin, serum-conjugated DCA and stool total BAs, and secondary-to-primary BA ratios were highest in current drinkers. On biopsies, a significantly higher mRNA expression of TNF-α, IL-1β, IL-6, and Cox-2 in colon but not ileum was seen in CurrAlc compared with NAlc and controls. Active alcohol use in cirrhosis is associated with a significant increase in the secondary BA formation compared with abstinent alcoholic cirrhotics and nonalcoholic cirrhotics. This increase in secondary BAs is associated with a significant increase in expression of inflammatory cytokines in colonic mucosa but not ileal mucosa, which may contribute to alcohol-induced gut barrier injury.