Gut Microbiome and Inflammatory Bowel Disease

Gut Microbiome and Inflammatory Bowel Disease
Modulation of Gut Microbiota in Obesity and Cardiometabolic Disorders Changes in gut microbiota are associated with metabolic disorders such as obesity, type 2 diabetes and cardiovascular risk factors. Patrice D. Cani (Brussels, Belgium), Willem M. de Vos (Wageningen, The Netherlands) and collaborators have identified Akkermansia muciniphila as a potential target to treat cardiometabolic disorders and inflammation. A. muciniphila is a mucin-degrading bacterium living in the gut\'s mucus layer. The authors demonstrated that feeding mice with A. muciniphila reduced bodyweight, fat mass and inflammation, and restored gut barrier function by acting on mucus layer thickness and restoring the production of antimicrobial proteins. The authors also showed that in obese people, the abundance of A. muciniphila was inversely related to fasting plasma nadph oxidase levels, visceral fat accumulation and adipocyte diameter in subcutaneous adipose tissue. Upon caloric restriction, obese individuals with higher baseline A. muciniphila showed improved insulin sensitivity markers and other cardiometabolic risk factors. In summary, strategies to modulate A. muciniphila composition in the human gut to treat obesity and cardiometabolic disorders warrant further investigation.
Liver Diseases and Gut Microbiota The hepatic portal vein conducts blood from the gastrointestinal tract to the liver, carrying metabolites produced by the gut microbiota making the liver one of the main organ that can be influenced by microbiome composition and activities. Philippe Gérard (Jouy-en-Josas, France) and collaborators demonstrated that a specific dysbiosis in intestinal microbiota (IM) was associated with alcoholic liver disease (ALD) severity in patients. The researchers transplanted germ-free and conventional mice with human IM from alcoholic patients with or without alcoholic hepatitis (AH). Mice receiving IM from an AH patient developed more severe liver inflammation with an increased number of liver T and NK lymphocyte subsets, higher liver necrosis, greater intestinal permeability and higher translocation of bacteria than mice harboring the IM from an alcoholic patient without AH (noAH). Distinct differences in IM composition could be observed, with key deleterious bacterial species being associated with AH and the Faecalibacterium genus being associated with noAH. A subsequent transfer of IM from a noAH patient could improve alcohol-induced liver lesions in conventional mice previously transplanted with IM from an AH patient. In conclusion, it may be possible to prevent and manage ALD by IM manipulation.
Gut Microbiota in Cystic Fibrosis
Skin Microbiota in Health and Disease While the gut microbiota is intensively investigated, knowledge about the skin microbiota, its protective function and immunomodulatory properties remains limited. The skin microbiota of the face and upper back is dominated by Staphylococcus and Propionibacterium species; in particular, Propionibacterium acnes predominately colonizes sebaceous areas. Using comparative genomics analysis, Holger Brüggemann (Aarhus, Denmark) and colleagues revealed the multi-phyletic composition of P. acne; certain P. acnes phylotypes are associated with healthy skin while others are associated with skin disorders such as acne vulgaris and progressive macular hypomelanosis. Confocal microscopy revealed the colonization pattern of P. acnes within the lumen of sebaceous follicles; healthy skin contained an organized, biofilm-like network of bacteria that does not seem to get in close contact with the adjacent keratinocyte layer. In contrast, in acne-affected skin, P. acnes was found to be tightly associated to skin cells, which might lead to the activation of innate immune responses. The data highlighted the fragile balance between P. acnes and the skin microenvironment, and a dysbiosis in P. acnes phylotype composition may lead to skin disorders.