1.
Microbes: possible link between modern lifestyle transition and the rise of metabolic syndrome.
Moossavi, S, Bishehsari, F
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2019;(3):407-419
Abstract
The rapid decrease in infectious diseases globally has coincided with an increase in the prevalence of obesity and other components of metabolic syndrome. Insulin resistance is a common feature of metabolic syndrome and can be influenced by genetic and non-genetic/environmental factors. The emergence of metabolic syndrome epidemics over only a few decades suggests a more prominent role of the latter. Changes in our environment and lifestyle have indeed paralleled the rise in metabolic syndrome. Gastrointestinal tract microbiota, the composition of which plays a significant role in host physiology, including metabolism and energy homeostasis, are distinctly different within the context of metabolic syndrome. Among humans, recent lifestyle-related changes could be linked to changes in diversity and composition of 'ancient' microbiota. Given the co-adaptation and co-evolution of microbiota with the immune system over a long period of time, it is plausible that such lifestyle-related microbiota changes could trigger aberrant immune responses, thereby predisposing an individual to a variety of diseases. Here, we review current evidence supporting a role for gut microbiota in the ongoing rise of metabolic syndrome. We conclude that population-level shifts in microbiota can play a mediatory role between lifestyle factors and pathogenesis of insulin resistance and metabolic syndrome.
2.
[Microbiome & NASH - partners in crime driving progression of fatty liver disease].
Wree, A, Geisler, LJ, Tacke, F
Zeitschrift fur Gastroenterologie. 2019;(7):871-882
Abstract
Along with the increasing prevalence of obesity, metabolic syndrome and type 2 diabetes, non-alcoholic fatty liver disease (NAFLD) is rapidly increasing and poses a major challenge for gastroenterologists. Many studies have demonstrated that the microbiome is closely associated with the progression of nutrition-related diseases, especially of fatty liver disease. Changes in the quantity and quality of the intestinal flora, commonly referred to as dysbiosis, result in altered food metabolism, increased permeability of the intestinal barrier ("leaky gut") and consecutive inflammatory processes in the liver. This favors both the progression of obesity and metabolic disorders as well as NAFLD towards non-alcoholic steatohepatitis (NASH), hepatic fibrosis, cirrhosis and hepatocellular carcinoma (HCC). Important molecular mechanisms include microbial metabolites, microbial and endogenous signaling substances (so-called PAMPs/DAMPs) as well as bile acids. Essential cellular mechanisms include immune cells in the gut and liver, especially macrophages and Kupffer cells, as well as intestinal epithelial cells and hepatocytes as central regulators of metabolism. In this review article, we briefly summarize the relevant species of the human microbiome, describe the microbial analytics, explain the most important molecular relationships between microbiome and NAFLD/NASH, and finally the opportunities and challenges of microbiome-modulating therapy for the treatment of fatty liver disease.