Mechanisms of bariatric surgery for weight loss and diabetes remission

Obesity and type 2 diabetes(T2D) lead to defects in intestinal hormones secretion, abnormalities in the composition of bile acids (BAs), increased systemic and adipose tissue inflammation, defects of branched-chain amino acids (BCAAs) catabolism, and dysbiosis of gut microbiota. Bariatric surgery (BS) has been shown to be highly effective in the treatment of obesity and T2D, which allows us to view BS not simply as weight-loss surgery but as a means of alleviating obesity and its comorbidities, especially T2D. In recent years, accumulating studies have focused on the mechanisms of BS to find out which metabolic parameters are affected by BS through which pathways, such as which hormones and inflammatory processes are altered. The literatures are saturated with the role of intestinal hormones and the gut-brain axis formed by their interaction with neural networks in the remission of obesity and T2D following BS. In addition, BAs, gut microbiota and other factors are also involved in these benefits after BS. The interaction of these factors makes the mechanisms of metabolic improvement induced by BS more complicated. To date, we do not fully understand the exact mechanisms of the metabolic alterations induced by BS and its impact on the disease process of T2D itself. This review summarizes the changes of intestinal hormones, BAs, BCAAs, gut microbiota, signaling proteins, growth differentiation factor 15, exosomes, adipose tissue, brain function, and food preferences after BS, so as to fully understand the actual working mechanisms of BS and provide nonsurgical therapeutic strategies for obesity and T2D.肥胖和2型糖尿病(T2D)导致肠道激素分泌缺陷、胆汁酸(BA)合成异常、脂肪组织炎症增加、支链氨基酸分解代谢异常和肠道菌群失调。减重手术(BS)已被证明在治疗肥胖和2型糖尿病方面非常有效, 这使得我们不能将BS简单地视为减重手术, 而是一种减轻肥胖及其合并症, 尤其是2型糖尿病的手段。近年来, 越来越多的研究关注BS的发病机制, 试图找出BS通过哪些途径影响代谢参数, 如哪些激素和炎症过程发生改变。目前已有大量文献证明肠道激素及其与神经网络相互作用形成的脑-肠轴在BS后肥胖和T2D缓解中的作用。此外, BS后的益处还与BAs、肠道菌群等因素有关。这些因素的相互作用使得BS引起代谢改善的机制更加复杂。迄今为止, 我们还没有完全了解BS诱导的代谢改变的确切机制及其对T2D本身疾病过程的影响。本文综述了BS后肠道激素、BAs、BCAAs、肠道菌群、信号蛋白、生长分化因子15、外泌体、脂肪组织、脑功能、食物偏好等方面的变化, 以期全面了解BS的实际作用机制, 为肥胖和T2D的非手术治疗提供策略。.