Porter Craig, Herndon David N, Bhattarai Nisha, Ogunbileje John O, Szczesny Bartosz, Szabo Csaba, Toliver-Kinsky Tracy, Sidossis Labros S
*Metabolism Unit, Shriners Hospitals for Children; and Departments of †Surgery, ‡Anesthesiology, and §Internal Medicine, University of Texas Medical Branch, Galveston, Texas.
Shock. 2015 Sep;44(3):258-64. doi: 10.1097/SHK.0000000000000410.
Chronic cold exposure induces functionally thermogenic mitochondria in the inguinal white adipose tissue (iWAT) of mice. Whether this response occurs in pathophysiological states remains unclear. The purpose of this study was to determine the impact of severe burn trauma on iWAT mitochondrial function in mice. Male BALB/c mice (10-12 weeks) received full-thickness scald burns to ∼30% of the body surface area. Inguinal white adipose tissue was harvested from mice at 1, 4, 10, 20, and 40 days postinjury. Total and uncoupling protein 1 (UCP1)-dependent mitochondrial thermogenesis were determined in iWAT. Citrate synthase activity was determined as a proxy of mitochondrial abundance. Immunohistochemistry was performed to assess iWAT morphology and UCP1 expression. Uncoupling protein 1-dependent respiration was significantly greater at 4 and 10 days after burn compared with sham, peaking at 20 days after burn (P < 0.001). Citrate synthase activity was threefold greater at 4, 10, 20, and 40 days after burn versus sham (P < 0.05). Per mitochondrion, UCP1 function increased after burn trauma (P < 0.05). After burn trauma, iWAT exhibited numerous multilocular lipid droplets that stained positive for UCP1. The current findings demonstrate the induction of thermogenically competent mitochondria within rodent iWAT in a model of severe burn trauma. These data identify a specific pathology that induces the browning of white adipose tissue in vivo and may offer a mechanistic explanation for the chronic hypermetabolism observed in burn victims.
长期冷暴露可诱导小鼠腹股沟白色脂肪组织(iWAT)中产生具有功能的产热线粒体。这种反应在病理生理状态下是否发生尚不清楚。本研究的目的是确定严重烧伤创伤对小鼠iWAT线粒体功能的影响。雄性BALB/c小鼠(10 - 12周龄)接受约30%体表面积的全层烫伤。在受伤后1、4、10、20和40天从小鼠身上采集腹股沟白色脂肪组织。测定iWAT中总的和依赖解偶联蛋白1(UCP1)的线粒体产热。测定柠檬酸合酶活性作为线粒体丰度的指标。进行免疫组织化学以评估iWAT形态和UCP1表达。与假手术组相比,烧伤后4天和10天依赖解偶联蛋白1的呼吸显著增加,在烧伤后20天达到峰值(P < 0.001)。与假手术组相比,烧伤后4、10、20和40天柠檬酸合酶活性增加了三倍(P < 0.05)。在每个线粒体中,烧伤创伤后UCP1功能增加(P < 0.05)。烧伤创伤后,iWAT出现大量多泡脂滴,UCP1染色呈阳性。目前的研究结果表明,在严重烧伤创伤模型中,啮齿动物iWAT内可诱导产生具有产热能力的线粒体。这些数据确定了一种在体内诱导白色脂肪组织褐变的特定病理情况,并可能为烧伤患者中观察到的慢性高代谢提供一种机制解释。