Renal Sinus Fat Is Expanded in Patients with Obesity and/or Hypertension and Reduced by Bariatric Surgery Associated with Hypertension Remission

Abstract

Renal sinus fat is a fat depot at the renal hilum. Because of its location around the renal artery, vein, and lymphatic vessels, an expanded renal sinus fat mass may have hemodynamic and renal implications. We studied whether renal sinus fat area (RSF) associates with hypertension and whether following bariatric surgery a decrease in RSF associates with improvement of hypertension. A total of 74 severely obese and 46 lean controls were studied with whole-body magnetic resonance imaging (MRI). A total of 42 obese subjects were re-studied six months after bariatric surgery. RSF was assessed by two independent researchers using sliceOmatic. Glomerular filtration rate (eGFR) was estimated according to the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration). Patients with obesity accumulated more RSF compared to lean controls (2.3 [1.7–3.1] vs. 1.8 [1.4–2.5] cm2, p = 0.03). Patients with hypertension (N = 36) had a larger RSF depot compared to normotensive subjects (2.6 [2.0–3.3] vs. 2.0 [1.4–2.5] cm2, p = 0.0007) also after accounting for body mass index (BMI). In the pooled data, RSF was negatively associated with eGFR (r = −0.20, p = 0.03), whereas there was no association with systolic or diastolic blood pressure. Following bariatric surgery, RSF was reduced (1.6 [1.3–2.3] vs. 2.3 [1.7–3.1] cm2, p = 0.03) along with other markers of adiposity. A total of 9/27 of patients achieved remission from hypertension. The remission was associated with a larger decrease in RSF, compared to patients who remained hypertensive (−0.68 [−0.74 to −0.44] vs. −0.28 [−0.59 to 0] cm2, p = 0.009). The accumulation of RSF seems to be involved in the pathogenesis of hypertension in obesity. Following bariatric surgery, loss of RSF was associated with remission from hypertension.

The Beneficial Effects of Bariatric-Surgery-Induced Weight Loss on Renal Function

“…From a pathophysiologic standpoint, it has been suggested that excessive fat accumulation in this specific fat depot would result in increased intra-abdominal pressure and the compression of the low-pressure renal venous structures [ 66 , 67 ], which would lead to the alteration of the renal hemodynamics, possibly by the activation of the renin angiotensin aldosterone system (RAAS) [ 67 ]. While several studies have shown that RSF is increased in patients with obesity, in a recent study we showed for the first time that following bariatric surgery, RSF is decreased [ 68 ]. Importantly, this decrease was associated with a remission from hypertension following bariatric surgery and a decrease in the number of antihypertensive drugs needed [ 68 ].…”

“…While several studies have shown that RSF is increased in patients with obesity, in a recent study we showed for the first time that following bariatric surgery, RSF is decreased [ 68 ]. Importantly, this decrease was associated with a remission from hypertension following bariatric surgery and a decrease in the number of antihypertensive drugs needed [ 68 ]. On the contrary, we could not detect any association with renal function, but in this study only eGFR data—rather than mGFR data—were available [ 68 ].…”

“…Importantly, this decrease was associated with a remission from hypertension following bariatric surgery and a decrease in the number of antihypertensive drugs needed [ 68 ]. On the contrary, we could not detect any association with renal function, but in this study only eGFR data—rather than mGFR data—were available [ 68 ].…”

Are we ready for an adipocentric approach in people living with type 2 diabetes and chronic kidney disease?

“…In this context, it is clearly expected that substantial WL will be the most effective measure to improve or resolve adipose tissue dysfunction, including renal involvement. Indeed, changes in renal fat deposition may explain the renoprotective effect of bariatric surgery or certain glucagon-like peptide 1 (GLP1) receptor agonist (RA) treatments [ 13 , 17 ].…”

Bariatric surgery to treat hypertension

“…Another important mechanism in regulating blood pressure could be the distribution of fat depots. Our group has recently shown that renal sinus fat (RSF) decreases following bariatric surgery and that this decrease is associated with remission from hypertension [9]. Reduction of RSF may alleviate the pressure on the renal vein and thus contribute to a less activated RAAS.…”