Perirenal Adipose Tissue—Current Knowledge and Future Opportunities

Abstract

The perirenal adipose tissue (PRAT), a component of visceral adipose tissue, has been recently recognized as an important factor that contributes to the maintenance of the cardiovascular system and kidney homeostasis. PRAT is a complex microenvironment consisting of a mixture of white adipocytes and dormant and active brown adipocytes, associated with predipocytes, sympathetic nerve endings, vascular structures, and different types of inflammatory cells. In this review, we summarize the current knowledge about PRAT and discuss its role as a major contributing factor in the pathogenesis of hypertension, obesity, chronic renal diseases, and involvement in tumor progression. The new perspectives of PRAT as an endocrine organ and recent knowledge regarding the possible activation of dormant brown adipocytes are nowadays considered as new areas of research in obesity, in close correlation with renal and cardiovascular pathology. Supplementary PRAT complex intervention in tumor progression may reveal new pathways involved in carcinogenesis and, implicitly, may identify additional targets for tailored cancer therapy.

Pro-Inflammatory Profile of Adipokines in Obesity Contributes to Pathogenesis, Nutritional Disorders, and Cardiovascular Risk in Chronic Kidney Disease

“…PRAT and accumulation of fatty acids in renal parenchyma cause the damage of tubulointerstitial tissue, proximal tubular epithelial cells, and endothelial cells [ 46 ]. Non-esterified fatty-acid (NEFA) accumulation leads to insulin resistance and apoptosis of podocytes which cannot regenerate [ 39 , 47 , 48 ]. Insulin resistance and hyperinsulinemia lead to activation of the sympathetic nervous system, which was confirmed by an increase in the concentration of catecholamines, and contributes to the occurrence of vasoconstriction [ 49 ].…”

Fatty kidney: A possible future for chronic kidney disease research

“…In fifty‐one patients with type 2 diabetes, renal sinus fat was negatively correlated with GFR and effective renal plasma flow and positively correlated with effective renal vascular resistance and mean arterial pressure mellitus after adjustments for body mass index, visceral adipose tissue and gender 100 . Perirenal adipose tissue has been linked to carotid intima–media thickness, vascular calcifications, visceral adiposity, hypertension and number of medications used in the treatment of hypertension, atherosclerosis, cardiovascular events, microalbuminuria and progression of chronic kidney disease in multiple large‐scale studies 63,101–107 . Although most studies, especially the cross‐sectional studies, do not consider perirenal fat thickness or renal sinus fat as an individual risk factor for the development of CKD, a few studies demonstrate that both are individual risk factors independent from other traditional risk factors.…”

Perirenal Adipose Tissue Inflammation: Novel Insights Linking Metabolic Dysfunction to Renal Diseases

“…In human embryos, PRAT-derived adipocyte progenitors differentiated in vitro exhibit similar features of BAT including PRDM16 and UCP1 expression, as well as a comparable mitochondrion copy number, gene expression patterns, and oxygen consumption rates ( 22 ). In newborns, PRAT predominantly consists of brown adipocytes with a thin layer of WAT, which exhibit an age-dependent, progressive regression, such that adult PRAT appears to be predominantly white with dispersed pockets of multilocular adipocytes ( 23 , 24 ). However, recent studies have shown that adult PRAT comprises spatially-distinct populations of dormant unilocular and multilocular UCP1-expressing adipocytes ( 21 , 24 – 26 ).…”