Renal sinus fat and renal hemodynamics: a cross-sectional analysis

Abstract

Objectives Increased renal sinus fat (RSF) is associated with hypertension and chronic kidney disease, but underlying mechanisms are incompletely understood. We evaluated relations between RSF and gold-standard measures of renal hemodynamics in type 2 diabetes (T2D) patients. Methods Fifty-one T2D patients [age 63 ± 7 years; BMI 31 (28-34) kg/m 2 ; GFR 83 ± 16 mL/min/1.73 m 2 ] underwent MRIscanning to quantify RSF volume, and subcutaneous and visceral adipose tissue compartments (SAT and VAT, respectively). GFR and effective renal plasma flow (ERPF) were determined by inulin and PAH clearances, respectively. Effective renal vascular resistance (ERVR) was calculated. Results RSF correlated negatively with GFR (r = − 0.38; p = 0.006) and ERPF (r = − 0.38; p = 0.006) and positively with mean arterial pressure (MAP) (r = 0.29; p = 0.039) and ERVR (r = 0.45, p = 0.001), which persisted after adjustment for VAT, MAP, sex, and BMI. After correction for age, ERVR remained significantly related to RSF. Conclusions In T2D patients, higher RSF volume was negatively associated to GFR. In addition, RSF volume was positively associated with increased renal vascular resistance, which may mediate hypertension and CKD development. Further research is needed to investigate how RSF may alter the (afferent) vascular resistance of the renal vasculature.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Metabolic Surgery to Treat Obesity in Diabetic Kidney Disease, Chronic Kidney Disease, and End-Stage Kidney Disease; What Are the Unanswered Questions?

“…In a cross-sectional exercise study RSF was not associated with eGFR or uACR at baseline, but had a significant association with uACR post-exercise, after adjustment for multiple variables including VAT (106). In a study of people with type 2 diabetes, RSF had an association with mGFR that remained significant after adjustment for BMI and VAT, but not after adjustment for age (107).…”

“…It is hoped that designating fatty kidney as a distinct clinical entity will help to focus research efforts (125). In longitudinal studies of changes in renal ectopic fat depots after metabolic surgery, it remains a challenge to separate the effect of RSF reduction from concomitantly occurring VAT and total body fat reductions (107). Despite this, future studies of metabolic surgery should include measurements of renal sinus and peri-renal fats pre-and post-intervention to further characterise the contribution of ectopic kidney fat reduction to its renoprotective effects.…”

“…A paracrine effect of RSF mediated through locally secreted cytokines and vasoconstrictive factors has also been suggested as a link between RSF and renal function. One study found an association between RSF, mGFR and renal vascular resistance, a parameter implicated in the progression of CKD ( 107 ). Spit et al hypothesize that the increased inflammation and reduced adiponectin from obese adipose tissue may mediate reduced renal vasorelaxation ( 107 ).…”

“…One study found an association between RSF, mGFR and renal vascular resistance, a parameter implicated in the progression of CKD ( 107 ). Spit et al hypothesize that the increased inflammation and reduced adiponectin from obese adipose tissue may mediate reduced renal vasorelaxation ( 107 ). However, when blood markers of inflammation were measured no association with RSF was found, suggesting that peri-renal fat and RSF depots are too small to have independent associations with systemic inflammation ( 102 ).…”

Nephroprotective effects of GLP-1 receptor agonists: where do we stand?

“…Additionally, obesity has been linked to DKD by provoking glomerular hyperfiltration, secondary to changes in sodium retention and increased sympathetic nervous system activity [42]. Intrarenal fat deposition ('fatty kidney'), in particular fat accumulation in the renal sinus (RSF), has been linked to hypertension [43], renal inflammation and fibrosis, and unfavorable renal hemodynamic function [44]. Intervention trials aimed at weight loss have indeed showed evidence for renoprotection.…”