Faculty of Medicine, University of Toronto, Canada.
Biological Sciences, Sunnybrook Research Institute, Canada.
Endocr Rev. 2017 Dec 1;38(6):538-549. doi: 10.1210/er.2017-00163.
In this era of increased obesity and diabetes prevalence, the browning of white adipose tissue (WAT) has emerged as a promising therapeutic target to induce weight loss and improve insulin sensitivity in this population. The browning process entails a shift in the WAT from primarily storing excess energy to the dissipation of energy as heat. However, this idealistic view of WAT browning being the savior of the metabolic syndrome has been criticized by studies in burn and cancer patients that have shown browning to be detrimental rather than beneficial. In fact, in the context of hypermetabolic states, the browning of WAT has presented with substantial clinical adverse outcomes related to cachexia, hepatic steatosis, and muscle catabolism. Therefore, the previous thought construct of understanding browning as an all-beneficial physiologic event has now been met with skepticism. In this review, we focus on current knowledge of browning of WAT and its adverse metabolic alterations during hypermetabolic states. We also discuss the regulators and signaling pathways involved in the browning process and their potential for being targeted by new or existing drugs to inhibit or alleviate browning, potentially leading to decreased hypermetabolism and improved clinical outcomes. Lastly, the imminent clinical applications of pharmacological agents are explored in the perspective of attenuating WAT browning and its associated adverse side effects reported in burn patients.
在肥胖症和糖尿病盛行的时代,白色脂肪组织(WAT)的棕色化已成为一个有前途的治疗靶点,可以诱导肥胖人群减轻体重并提高胰岛素敏感性。棕色化过程涉及 WAT 从主要储存多余能量向消耗能量以产生热量的转变。然而,这种将 WAT 棕色化视为代谢综合征救星的理想化观点受到了烧伤和癌症患者研究的批评,这些研究表明棕色化弊大于利。事实上,在代谢亢进状态下,WAT 的棕色化与恶病质、肝脂肪变性和肌肉分解代谢等相关的大量临床不良结局有关。因此,之前对棕色化作为一种有益的生理事件的理解观念现在受到了质疑。在这篇综述中,我们重点关注当前关于 WAT 棕色化及其在代谢亢进状态下的不良代谢改变的知识。我们还讨论了棕色化过程中涉及的调节因子和信号通路,以及它们作为新的或现有的药物靶点的潜力,以抑制或减轻棕色化,从而可能降低代谢亢进并改善临床结局。最后,从减轻烧伤患者报告的 WAT 棕色化及其相关不良反应的角度探讨了药理学制剂的即将出现的临床应用。