Effects of Weight Loss on Structural and Functional Alterations of Subcutaneous Small Arteries in Obese Patients

Abstract

Abstract-Structural alterations of subcutaneous small resistance arteries, as indicated by an increased media:lumen ratio, are frequently present in hypertensive and/or diabetic patients and may represent the earliest alteration observed. In addition, media:lumen ratios of small arteries have a strong prognostic significance. However, no data are available about the structure of small resistance arteries of obese patients, particularly after weight loss. We have investigated 27 patients with severe obesity. Twelve of them were normotensive, and 15 were hypertensive. All of the obese patients underwent bariatric surgery. We compared results obtained with those observed in 13 normotensive lean controls and in 13 hypertensive lean patients. All of the subjects and patients underwent a biopsy of subcutaneous fat during surgical intervention. In 8 obese patients, a second biopsy was obtained after consistent weight loss, during a surgical intervention for abdominoplasty. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph, and structural parameters were measured. A concentration-response curve to acetylcholine was performed to evaluate endothelial function. Obese patients, independent from the presence of hypertension, show the presence of an increased media:lumen ratio and media cross-sectional area, together with an impaired endothelial-dependent vasodilatation. After surgical correction of obesity and consistent weight loss, a significant improvement of microvascular structure and of some oxidative stress/inflammation markers were observed. In conclusion, our data suggest that the presence of obesity is associated with structural alterations of subcutaneous small resistance arteries, mainly characterized by hypertrophic remodeling. Weight loss may improve microvascular structure. (Hypertension. 2011;58:29-36.)Key Words: remodeling Ⅲ hypertension Ⅲ obesity Ⅲ microcirculation Ⅲ small arteries A lterations in the microcirculation are common accompaniments of cardiovascular and metabolic diseases 1,2 and may involve small resistance arteries, arterioles, capillaries, and postcapillary venules. 3 In particular, the structure of subcutaneous 1-3 and cerebral 4 small resistance arteries (lumen diameter: 100 to 300 m) may be altered in the presence of cardiovascular or metabolic diseases. Essential hypertension is associated with a narrowing of the internal lumen and with an increase of media wall thickness, with consequent increase in the media:lumen ratio. 1 The observed increase in the media:lumen ratio may be the consequence of an eutrophic remodeling (rearrangement of otherwise normal material around a narrowed lumen) or of a hypertrophic remodeling (vascular smooth muscle cell hypertrophy or hyperplasia). 5 Eutrophic remodeling of subcutaneous small arteries is commonly seen in essential hypertension, whereas an inward hypertrophic remodeling, with evident smooth muscle cell growth, was shown in patients with type 2 diabetes mellitus, regardless of the presence of elevated or normal ...

Obesity-Related Perivascular Adipose Tissue Damage Is Reversed by Sustained Weight Loss in the Rat

“…13,14 The mechanisms that underlie these improvements are unclear but are likely to be a consequence of improvements in inflammatory and adipokine profiles. [15][16][17] Our studies demonstrate that bariatric surgery can reverse obesity-induced PVAT damage 6 months after surgery through reduction of adipose inflammation and increasing local adiponectin and nitric oxide (NO) bioavailability. 10 This correlated with reduced blood pressure and improvements in lipid profiles and blood glucose levels, suggesting that the restoration of PVAT function could contribute to the cardiovascular benefits of losing weight.…”

Definition and Epidemiology of Arterial Disease

“…Eutrophic remodelling (rearrangement of the same cellular material around a narrowed lumen resulting in increased media/lumen ratio) has been described in patients with essential hypertension [ 24 ] and hypertrophic remodelling (increase in wall thickness or media cross-sectional area and preservation of the lumen diameter) in individuals with diabetes [ 25 -27 ]. Similarly, obese patients exhibit an increase in media-to-lumen ratio in keeping with hypertrophic remodelling [ 28 ], and persistent weight loss following weight-loss surgery regresses these vascular changes [ 29 ].…”

Childhood obesity: a life-long health risk

“…Human obesity, characterized by accumulation of ectopic (particularly visceral) fat [63] , is associated with abnormal endothelium-dependent vasomotion and enhanced contractility to endothelin-1 [64,65] . Accordingly, a reduction in energy intake [66] or reduction in body weight [67] improves vascular function in obese patients. In human resistance arteries obesity is associated with vascular hypertrophy as indicated by an increased media-to-lumen ratio [68] , and a recent important study demonstrated that functional vascular abnormalities observed in obese individuals can be largely normalized by lowering body weight by reducing intra-abdominal fat mass in adults [67] .…”

“…Accordingly, a reduction in energy intake [66] or reduction in body weight [67] improves vascular function in obese patients. In human resistance arteries obesity is associated with vascular hypertrophy as indicated by an increased media-to-lumen ratio [68] , and a recent important study demonstrated that functional vascular abnormalities observed in obese individuals can be largely normalized by lowering body weight by reducing intra-abdominal fat mass in adults [67] . Thus, any reduction of obesity -in children as well as adults -is likely to translate into improved overall health and survival [4,15,69] .…”