Intestinal microbiota and their metabolic contribution to type 2 diabetes and obesity

Abstract

Obesity and type 2 diabetes mellitus (T2DM) are common, chronic metabolic disorders with associated significant long-term health problems at global epidemic levels. It is recognised that gut microbiota play a central role in maintaining host homeostasis and through technological advances in both animal and human models it is becoming clear that gut microbiota are heavily involved in key pathophysiological roles in the aetiology and progression of both conditions. This review will focus on current knowledge regarding microbiota interactions with short chain fatty acids, the host inflammatory response, signaling pathways, integrity of the intestinal barrier, the interaction of the gut-brain axis and the subsequent impact on the metabolic health of the host.

Alterations in the Oral Microbiome Associated With Diabetes, Overweight, and Dietary Components

“…The latter may be due to increased consumption of fibers, micronutrients, and bioactive compounds with anti-inflammatory properties, all of which are present in relatively high amounts in many of the foods comprising the MedDiet (12). It may be that this dietary effect is mediated in part by changes in the gut microbiome, since there is evidence from human and mouse studies, that altered composition and function of the gut microbiota can contribute to the development of obesity and T2DM, through altered microbial production of short-chain fatty acids and microbial metabolism of host bile acids, both of which can impact on host glucose metabolism and insulin signaling (13). Obesity and T2DM are associated with gut barrier disruption and increased permeability to bacterial-derived inflammogens such as LPS, leading to increased systemic inflammation (13)(14)(15).…”

“…It may be that this dietary effect is mediated in part by changes in the gut microbiome, since there is evidence from human and mouse studies, that altered composition and function of the gut microbiota can contribute to the development of obesity and T2DM, through altered microbial production of short-chain fatty acids and microbial metabolism of host bile acids, both of which can impact on host glucose metabolism and insulin signaling (13). Obesity and T2DM are associated with gut barrier disruption and increased permeability to bacterial-derived inflammogens such as LPS, leading to increased systemic inflammation (13)(14)(15). MedDiet intervention in overweight and obese subjects lowers plasma cholesterol and alters the gut microbiome and metabolome independently of energy intake, with an increased diversity of the gut microbiome being correlated with reduced systemic inflammation as indicated by serum hs-CRP concentrations (16).…”

Metabolites of Gut Microbiota and Possible Implication in Development of Diabetes Mellitus

“…As one type of microbial metabolite, SCFAs serve as an energy source, facilitate lipids and carbohydrates metabolism, and decrease cytokines secretion . SCFAs may favorably influence diabetes in multiple pathways.…”

“…150 Besides, propionate can also maintain the glucose and energy homeostasis and is beneficial for weight loss. 151 Further, it affects the glucose metabolism via decreasing plasma fatty acids 141 and modulating insulin sensitivity. 152 The benefits of SCFAs are proposed to be mediated by the following mechanisms.…”

Do intestinal microbiota contribute to obesity?

“…Jednocześnie niektóre publikacje wykazują brak korelacji pomiędzy bakteriami z grupy Bacteroidetes i Firmicutes a masą ciała [36]. Wzrost liczby bakterii z rodziny Prevotellaceae prawdopodobnie przyczynia się do wzrostu liczebności archeonów metanogennych, ponieważ bakterie Bacteroidetes w procesie fermentacji białek i węglowodanów uwalniają wodór, tak ważny dla rozwoju metanogenów [37,38]. Nasuwa się pytanie, czy zmiany w składzie mikrobioty u otyłych osobników są skutkiem, czy przyczyną otyłości.…”