OBJECTIVE To investigate the role of peroxisome proliferator-activated receptor γ(PPARγ) in the treatment of renal injury in IgA nephropathy rats by Cynanchi Paniculati Radix et Rhizoma.
METHODS The 120 SD male rats were randomly divided into blank group, model group, Cynanchi Paniculati Radix et Rhizoma low, high dose group, positive drug(prednisone) group, and PPARγ agonist group. Collect urine, serum, and kidney tissues. Measure urinary protein, blood urea nitrogen(BUN), serum creatinine(Scr), and IgA levels. Hematoxylin-eosin(HE) staining was used to observe the histopomorphological changes of renal tissues. Transmission electron microscope was used to observe the ultrastructural damages of rat kidneys; TdT-mediated dUTP Nick-End Labeling(TUNEL staining) was used to observe the proportion of apoptotic positive cells in rat kidneys; ELISA was used to detect the contents interleukin(IL)-1β, IL-6, tumor necrosis factor-alpha(TNF-α) and reactive oxygen species(ROS) in kidneys; colorimetric method was used to detect the levels of malondialdehyde(MDA), glutathione peroxidase(GSH-Px), and total superoxide dismutase(SOD) in kidney tissue; quantitative real-time polymerase chain reaction(qRT-PCR) was used to detect the expression of PPARγ, Toll-like receptor 4(TLR4) and p-NF-κB at the mRNA level in rat kidney tissue; Western blotting was used to detect the protein expressions of PPARγ, TLR4, NF-κB and Caspase-3 in rat kidney tissue. Immunohistochemical method(IHC) was used to detect the protein expressions of NOD-like receptor protein 3(NLRP3) and Cleaved Caspase-1. Immunofluorescence(IF) was used to detect the protein expression of Cleaved Caspase-1 in rat kidney tissue.
RESULTS Compared with the model group, treatment with Cynanchi Paniculati Radix et Rhizoma significantly reduced urinary protein, BUN, Scr and IgA levels in rats with IgA nephropathy(P<0.05 or P<0.01), and the inflammatory cell infiltration and mitochondrial damage of kidney tissue were significantly alleviated. The number of TUNEL-positive cells, the expression and activity of Cleaved Caspase-3 protein, the contents of IL-1β, IL-6 and TNF-α, the levels of ROS and MDA were decreased, and the activities of SOD and GSH-Px were increased in low- and high-dose groups of Cynanchi Paniculati Radix et Rhizoma, which were significantly different from those in model group(P<0.05 or P<0.01). In addition, compared with the model group, the mRNA and protein levels of PPARγ in kidney of rats in low- and high-dose groups of Cynanchi Paniculati Radix et Rhizoma were increased, while the mRNA and protein levels of TLR4 and NF-κB were decreased(P<0.05 or P<0.01). In addition, the protein levels of NLPR3 and Cleaved Caspase-1 were significantly decreased in the rats kidney tissue in Cynanchi Paniculati Radix et Rhizoma group, and there were significant differences compared with model group(P<0.01).
CONCLUSION The renoprotective effects of Cynanchi Paniculati Radix et Rhizoma in IgA nephropathy rats may be mediated through the regulation of PPARγ, leading to the suppression of oxidative stress, apoptosis, and inflammation.
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