Recent evidence regarding microbiota is modifying the cornerstones on pathogenesis and the approaches to several gastrointestinal diseases, including biliary diseases. The burden of biliary diseases, indeed, is progressively increasing, considering that gallstone disease affects up to 20% of the European population. At the same time, neoplasms of the biliary system have an increasing incidence and poor prognosis. Framing the specific state of biliary eubiosis or dysbiosis is made difficult by the use of heterogeneous techniques and the sometimes unwarranted invasive sampling in healthy subjects. The influence of the microbial balance on the health status of the biliary tract could also account for some of the complications surrounding the post-liver-transplant phase. The aim of this extensive narrative review is to summarize the current evidence on this topic, to highlight gaps in the available evidence in order to guide further clinical research in these settings, and, eventually, to provide new tools to treat biliary lithiasis, biliopancreatic cancers, and even cholestatic disease.

Background Endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) is a valid option for EUS-guided biliary drainage that has been increasingly used in the last decade. The aims of this study were to provide a systematic review with meta-analysis and meta-regression of the features and outcomes of this procedure. Methods The MEDLINE, Scopus, Web of Science, and Cochrane databases were searched for literature pertinent to EUS-HGS. Meta-analysis of the proportions and meta-regression of potential modifiers of the main outcome measures were applied. The main outcome was technical success; secondary outcomes were clinical success and procedure-related adverse events (AEs). Results 33 studies, including 1644 patients, were included in the meta-analysis. Malignant biliary obstruction (MBO) was the underlying cause in almost all cases (99.6%); the main indications for EUS-HGS were duodenal/papillary invasion (34.8%), surgically altered anatomy (18.4%), and hilar stenosis (16.0%). The pooled technical success of EUS-HGS was 97.7% (95%CI 96.1%–99.0%; I 2 = 0%), the intention-to-treat clinical success rate was 88.1% (95%CI 84.7%–91.2%; I 2 = 33.9%), and procedure-related AEs occurred in 12.0% (95%CI 9.8%–14.5%; I 2 = 20.4%), with cholangitis/sepsis (2.8%) and bleeding (2.3%) the most frequent. The rate of procedure-related AEs was lower with the use of dedicated stents on univariable meta-regression analysis. Meta-regression showed that technical success and clinical success rates were modified by the centers’ experience (>4/year). Conclusions EUS-HGS represents an effective and safe procedure for EUS-guided biliary drainage in patients with MBO. Future studies should address the impact of center experience, patient selection, and the use of dedicated stents to improve performance of this technique.

Diet is the first to affect our intestinal microbiota and therefore the state of eubiosis. Several studies are highlighting the potential benefits of taking certain nutritional supplements, but a dietary regime that can ensure the health of the intestinal microbiota, and the many pathways it governs, is not yet clearly defined. We performed a systematic review of the main studies concerning the impact of an omnivorous diet on the composition of the microbiota and the production of short-chain fatty acids (SCFAs). Some genera and phyla of interest emerged significantly and about half of the studies evaluated consider them to have an equally significant impact on the production of SCFAs, to be a source of nutrition for our colon cells, and many other processes. Although numerous randomized trials are still needed, the Mediterranean diet could play a valuable role in ensuring our health through direct interaction with our microbiota.

Steatohepatitis and hepatobiliary manifestations constitute some of the most common extra-intestinal manifestations of Inflammatory Bowel Disease (IBD). On the other hand, non-alcoholic fatty liver disease (NAFLD) affects around 25% of the world’s population and is attracting ever more attention in liver transplant programs. To outline the specific pathways linking these two conditions is a pressing task for 21st-century researchers. We are accustomed to expecting the occurrence of fatty liver disease in obese people, but current evidence suggests that there are several different pathways also occurring in underweight patients. Genetic factors, inflammatory signals and microbiota are key players that could help in understanding the entire pathogenesis of NAFLD, with the aim of defining the multiple expressions of malnutrition. In the current review, we summarize the most recent literature regarding the epidemiology, pathogenesis and future directions for the management of NAFLD in patients affected by IBD.