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Obesity is a risk factor that promotes progressive kidney disease. Studies have shown that an adipocytokine imbalance contributes to impaired renal function in humans and animals, but the underlying interplay between adipocytokines and renal injury remains to be elucidated. We aimed to investigate the mechanisms linking obesity to chronic kidney disease. We assessed renal function in high-fat (HF) diet-fed and normal diet-fed rats, and the effects of preadipocyte- and adipocyte-conditioned medium on cultured podocytes. HF diet-fed and normal diet-fed Sprague Dawley rats were used to analyze the changes in plasma BUN, creatinine, urine protein and renal histology. Additionally, podocytes were incubated with preadipocyte- or adipocyte-conditioned medium to investigate the effects on podocyte morphology and protein expression. In the HF diet group, 24 h urinary protein excretion (357.5 ± 64.2 mg/day vs 115.9 ± 12.4 mg/day, P < 0.05) and the urine protein/creatinine ratio were significantly higher (1.76 ± 0.22 vs 1.09 ± 0.15, P < 0.05), increased kidney weight (3.54 ± 0.04 g vs 3.38 ± 0.04 g, P < 0.05) and the glomerular volume and podocyte effacement increased by electron microscopy. Increased renal expression of desmin and decreased renal expression of CD2AP and nephrin were also seen in the HF diet group (P < 0.05). Furthermore, we found that adipocyte-conditioned medium-treated podocytes showed increased desmin expression and decreased CD2AP and nephrin expression compared with that in preadipocyte-conditioned medium-treated controls (P < 0.05). These findings show that adipocyte-derived factor(s) can modulate renal function. Adipocyte-derived factors play an important role in obesity-related podocytopathy.

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an oligomeric complex that assembles in response to exogenous signals of pathogen infection and endogenous danger signals of non-microbial origin. When NLRP3 inflammasome assembly activates caspase-1, it promotes the maturation and release of the inflammatory cytokines interleukin-1B and IL-18. Aberrant activation of the NLRP3 inflammasome has been implicated in various diseases, including chronic inflammatory, metabolic, and cardiovascular diseases. The NLRP3 inflammasome can be activated through several principal mechanisms, including K⁺ efflux, lysosomal damage, and the production of mitochondrial reactive oxygen species. Interestingly, metabolic danger signals activate the NLRP3 inflammasome to induce metabolic diseases. NLRP3 contains three crucial domains: an N-terminal pyrin domain, a central nucleotide-binding domain, and a C-terminal leucine-rich repeat domain. Protein–protein interactions act as a ‘pedal or brake’ to control the activation of the NLRP3 inflammasome. In this review, we present the mechanisms underlying NLRP3 inflammasome activation after induction by metabolic danger signals or via protein–protein interactions with NLRP3 that likely occur in metabolic diseases. Understanding these mechanisms will enable the development of specific inhibitors to treat NLRP3-related metabolic diseases.