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The human gut microbiome interacts with each other and the host, which has significant effects on health and disease development. Intestinal homeostasis and inflammation are maintained by the dynamic interactions between gut microbiota and the innate and adaptive immune systems. Numerous metabolic products produced by the gut microbiota play a role in mediating cross‐talk between gut epithelial and immune cells. In the event of an imbalance between the immune system and microbiota, the body becomes susceptible to infections and homeostasis is compromised. This review mainly focuses on the interplay between microbes and the immune system, such as T‐cell‐ and B‐cell‐mediated adaptive responses to microbiota and signalling pathways for effective communication between the two. We have also highlighted the role of microbes in the activation of the immune response, the development of memory cells and how the immune system determines the diversity of human gut microbiota. The review also explains the relationship of commensal microbiota and their relation to the production of immunoglobulins. [ABSTRACT FROM AUTHOR]

Objective: Gut microbiota influence metabolic pathways related to the pathogenesis of obesity, insulin-resistance and diabetes. Antibiotic therapy can alter the microbiota, and is commonly used in western countries. We sought to evaluate whether past antibiotic exposure increases diabetes risk. Research design and methods: We conducted a nested case-control study using a large population-based database from the UK. The cases were defined as those with incident diagnosis of diabetes. For every case, four eligible controls matched on age, sex, practice-site, and duration of follow-up before index-date were selected using incidence-density sampling. Exposure of interest was antibiotic therapy O1 year before index-date. Odds ratios (ORs) and 95% CIs were estimated using conditional logistic regression. The risk was adjusted for BMI, smoking, last glucose level, and number of infections before index-date, as well as past medical history of coronary artery disease and hyperlipidaemia. Results: The study included 208 002 diabetic cases and 815 576 matched controls. Exposure to a single antibiotic prescription was not associated with higher adjusted diabetes risk. Treatment with two to five antibiotic courses was associated with increase in diabetic risk for penicillin, cephalosporins, macrolides and quinolones with adjusted OR ranging from 1.08 (95% CI 1.05-1.11) for penicillin to 1.15 (95% CI 1.08-1.23) for quinolones. The risk increased with the number of antibiotic courses and reached 1.37 (95% CI 1.19-1.58) for more than 5 courses of quinolones. There was no association between exposure to anti-virals and anti-fungals and diabetes risk. Conclusions:Exposure to certain antibiotic groups increases diabetes risk. [ABSTRACT FROM AUTHOR]

In this review, the influence of fat depots on insulin resistance and the main characteristics of metabolically obese normal-weight and metabolically healthy obese phenotypes are discussed. Medline/PubMed and Science Direct were searched for articles related to the terms metabolically healthy obesity, metabolically obese normal weight, adipose tissue, and insulin resistance. Normal weight and obesity might be heterogeneous in regard to their effects. Fat distribution and lower insulin sensitivity are the main factors defining phenotypes within the same body mass index. Although these terms are interesting, controversies about them remain. Future studies exploring these phenotypes will help elucidate the roles of adiposity and/or insulin resistance in the development of metabolic alterations. [ABSTRACT FROM AUTHOR]