Institut National de la Santé et de la Recherche Médicale, U1213, Lyon, Université Lyon 1, Villeurbanne, and Université de Lyon, Lyon, France.
Neuroendocrinology. 2018;106(4):352-356. doi: 10.1159/000484526. Epub 2017 Oct 24.
A large number of genomic studies have reported associations between the gut microbiota composition and metabolic diseases such as obesity or type 2 diabetes. This led to the widespread idea that a causal relationship could exist between intestinal microbiota and metabolic diseases. At odds with this idea, some compelling studies reported that global changes in microbiota composition have no effect on the host metabolism in obese mice or humans. However, specific bacteria are able to confer host metabolic benefits, such as Akkermansia muciniphila or Prevotella copri, when they are given by gavage in obese mice. A crucial link by which gut bacteria communicate with the host mucosa is based on metabolites or low-molecular-weight compounds. Among them, short-chain fatty acids produced from the fermentation of dietary fibers initiate beneficial effects on the host metabolism via the activation of intestinal gluconeogenesis (a mucosal function exerting antidiabetic and antiobesity effects through the activation of gut-brain neural circuits). However, fermentation of short-chain fatty acids is a function that is widespread among the main bacterial phyla and thus weakly depends on microbiota composition. Therefore, even if some bacteria may confer on the host metabolic benefits, the causal role of microbiota in metabolic diseases is not established.
大量的基因组研究报告了肠道微生物组成与肥胖症或 2 型糖尿病等代谢疾病之间的关联。这导致了一种广泛的观点，即肠道微生物群与代谢疾病之间可能存在因果关系。与这一观点相悖的是，一些引人注目的研究报告称，肥胖小鼠或人类肠道微生物组成的全球变化对宿主代谢没有影响。然而，当特定的细菌通过灌胃给予肥胖小鼠时，它们能够赋予宿主代谢益处，例如 Akkermansia muciniphila 或 Prevotella copri。肠道细菌与宿主黏膜进行交流的一个关键环节是基于代谢物或低分子量化合物。其中，膳食纤维发酵产生的短链脂肪酸通过激活肠道糖异生（一种通过激活肠道-大脑神经回路发挥抗糖尿病和抗肥胖作用的黏膜功能）对宿主代谢产生有益影响。然而，短链脂肪酸的发酵是主要细菌门普遍具有的功能，因此它在很大程度上依赖于微生物群落的组成。因此，即使某些细菌可能赋予宿主代谢益处，也不能确定微生物群在代谢疾病中的因果作用。
