1. In severely obese individuals, perivascular adipose tissue (PVAT) showed dysfunction prior to bariatric surgery and showed restored function when resampled six months postoperatively.
2. Improvements to PVAT function and resulting small artery tone occurred while patients remained severely obese.
Evidence Rating Level: 2 (Good)
Study Rundown: Perivascular adipose tissue (PVAT) normally exerts an opposing or attenuating effect against vasoconstrictors on small arteries through release of adiponectin and nitric oxide. This effect is lost in PVAT sampled from severely obese individuals. The present study showed that PVAT function in bariatric surgery patients six months post-operatively was restored to levels comparable to healthy controls, despite the patients remaining severely obese. When compared against tissue obtained from the same patients before their operation, the post-operative PVAT had decreased inflammation and adipose tissue hypoxia. These findings suggest a mechanism for bariatric surgery decreasing cardiac risk independent of weight loss.
In-Depth: Gluteal tissue samples were obtained from 7 healthy patients and before and after surgery from 15 severely obese patients. Adipose tissue was analyzed for inflammatory markers by immunohistochemistry and nitric oxide assay, and endothelial-denuded microvessels were analyzed for contractility using wire myography and with pharmacologic vasoconstrictors. Before surgery, severely obese PVAT did not have anticontractile activity. Results showed restored anticontractile function against vasoconstrictors after surgery (p <0.01), reduced macrophage staining (p<0.01), and reduced inflammatory markers such as IL-6 (p<0.001). There was no significant reduction in circulating TNF-alpha levels.
By Gina Siddiqui and Allen Ho
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