Kidney disease is one of the leading non-communicable diseases related to tremendous health and economic burden globally. Diabetes, hypertension, obesity and cardiovascular conditions are the major risk factors for kidney disease, followed by infections, toxicity and autoimmune causes. The peroxisome proliferator-activated receptor gamma (PPAR-γ) is a ligand-activated nuclear receptor that plays an essential role in kidney physiology and disease. The synthetic agonists of PPAR-γ shows a therapeutic effect in various kidney conditions; however, the associated side effect restricts their use. Therefore, there is an increasing interest in exploring natural products with PPARγ-activating potential, which can be a promising solution to developing effective and safe treatment of kidney diseases. In this review, we have discussed the role of PPAR-γ in the pathophysiology of kidney disease and the potential of natural PPAR-γ agonists in treating various kidney diseases, including acute kidney injury, diabetic kidney disease, obesity-induced nephropathy, hypertension nephropathy and IgA nephropathy. PPAR-γ is a potential target for the natural PPAR-γ agonists against kidney disease; however, more studies are required in this direction.

Background: Liver fibrosis is a chronic pathological condition with a leading cause of liver-related mortality worldwide. In the present study, we have evaluated the antifibrotic effect of crocin, a carotenoid present in the stigma of Crocus sativus, and also explored its putative mechanism of action. Methods: Liver fibrosis was induced by intraperitoneal administration of 30% carbon tetrachloride (CCl₄). The crocin was administered orally at 20, 40 and 80 mg/kg body weight along with CCl₄ up to 8 weeks. Results: Chronic exposure to CCl₄ resulted in elevated levels of liver enzymes and reduced cytochrome P450 2E1 (CYP2E1) activity in the liver. The liver tissue showed cellular swelling, vacuolization, necrosis, infiltration of inflammatory cells and fibrotic changes. The crocin treatment significantly lowered the levels of liver enzymes in serum and improved the liver CYP2E1 mRNA levels. The pathological changes in the liver were also lowered by crocin treatment. The level of pro-inflammatory cytokines, nuclear factor-kappa B, interleukin-6 and tumor necrosis factor α and fibrogenic factor, transforming growth factor β, and α-smooth muscle actin were elevated by the CCl₄ in the liver tissue. However, crocin treatment at different doses significantly reduced the expression of these factors. The increased caspase 3/7 activity was also lowered by crocin. CCl₄ administration decreased the expression of peroxisome proliferator-activated receptor γ (PPAR-γ) in liver tissue. The improved PPAR-γ expression in the liver by crocin treatment indicates its role in the therapeutic effect of crocin. Conclusions: Crocin attenuated the various events in the progression of liver fibrosis via PPAR-γ mediated modulation of inflammatory and fibrogenic pathways.