Role of Lipid Metabolism Disorders in Renal Ageing and Renal Fibrosis / 生物化学与生物物理进展

ABSTRACT

Chronic kidney disease (CKD) has become a significant global public health problem. It is defined as chronic renal structural and functional dysfunction caused by various reasons. The prevalence of obesity and diabetes has increased dramatically in developing countries, which substantially affected the patterns of CKD observed in these regions. It’s inevitable that the disease spectrum of CKD is converting to metabolic diseases. CKD is also considered an independent risk factor for renal aging and cardiovascular disease in the elderly, which usually progresses to end-stage renal disease (ESRD). Renal interstitial fibrosis is the pathological basis of ESRD and is a microscopic manifestation of renal aging. Conversely, renal aging is a risk factor for interstitial fibrosis. Although the healthy kidney has a relatively low lipid level, CKD-associated dyslipidemia has been extensively studied. Nevertheless, less is known about the contribution of lipid disorders to the development of renal senescence and interstitial fibrosis. Recent studies have demonstrated that lipid metabolism disorders occur in the progress of renal aging and interstitial fibrosis. Renal lipids accumulate once lipid uptake and synthesis exceed the balance with lipolysis, which is mainly characterized by increased levels of triglyceride (TG) and oxidized low-density lipoprotein, and decreased levels of high-density lipoprotein. Excessive lipid accumulation in the kidney not only induces lipotoxicity and endoplasmic reticulum stress but also increases intracellular and mitochondrial reactive oxygen species, which induce stress injury and senescence in renal tubular epithelial cells. Pro-inflammatory and pro-fibrotic cytokines in a senescence-associated secretory phenotype secreted by senescent renal tubular epithelial cells further accelerate their senescence as well as the occurrence of inflammation and pericyte loss, promoting secretion of extracellular matrix (ECM) and subsequent fibrosis in the tubulointerstitial compartment. In addition, podocyte hypertrophy also leads to glomerulosclerosis. Currently, most of the studies on inhibiting or even reversing renal interstitial fibrosis are still in the experimental stage. What’s more, effective drugs to slow down renal aging have not been reported. Many inflammatory and fibrotic factors are both components of the senescence-associated secretory phenotype (SASP), nevertheless, they are not sufficient to recognize cellular senescence. Given that indicators of senescence may vary from disease to disease and organ to organ, there is a need for more sensitive and specific senescence assays. Crucial enzymes and regulatory proteins of lipid metabolic pathways are expected to be potential targets for ameliorating renal aging and interstitial fibrosis. Lipid-lowering approach might represent another therapeutic in the management of kidney injury associated with metabolic dysfunction. Thus, clarifying the molecular regulatory mechanisms of lipid metabolism in kidney is extremely important for the delay of renal aging and the treatment of interstitial fibrosis. This review outlines the effects of lipid metabolism disorders on renal aging and renal fibrosis, analyses the role of lipid metabolism disorders in the development of renal diseases, and summarizes the potential targets and strategies for the prevention of renal aging and renal fibrosis based on lipid metabolism regulation, which will provide a reference for the discovery of new targets for the treatment of renal fibrosis.