Objective  To investigate the regulatory effect and its mechanism of chrysophanol (CP) on renal injury and immune response in immunoglobin A (IgA) nephropathy rats.

  Methods  IgA nephropathy rat model was established by the method of lipopolysaccharide + bovine serum protein + carbon tetrachloride. Then the rats were randomly divided into 5 groups: control group, IgA group, IgA+low, medium and high dose of CP groups(2.5, 5 and 10 mg/kg for each group respectively). IgA+CP groups were intraperitoneally injected with different doses of chrysophanol once a day for 4 weeks, and the control group and IgA group were given isovolumetric saline. Urine protein content, serum creatinine and urea nitrogen were detected at 24 h after the administration of drugs. Kidney histopathological damage and apoptosis were measured by HE and TUNEL staining. The expression levels of Caspase-3 and Caspase-9 were detected by RT-PCR and Western blot; The contents of malondialdehyde (MDA), superoxide dismutase (SOD) and (glutathione peroxidase, Gpx) were detected by enzyme-linked immunosorbent assay (ELISA). The expression of interleukin-1β, -6 (IL-1β, IL-6) and tumor necrosis factor (TNF-α) in serum and kidney tissue were measured by ELISA and Western blot, respectively. The mRNA and protein expression levels of toll-like receptro 4 (TLR4), nuclear factor-κB P65 (NF-κB P65) were also detected by RT-PCR and Western blot, and vascular cell adherin molecule (VCAM-1) protein level was deteted by Western blot.

  Results  In IgA nephropathy rats, the administration of CP reduced proteinuria, serum creatinine and urea nitrogen in a dose-dependent manner (P < 0.01). It also improved the pathological damage of kidney tissue, reduced the apoptosis rate (P < 0.01), and decreased the mRNA and protein expression levels of apoptosis-related proteins Caspase-3 and Caspase-9 (P < 0.01). CP inhibited MDA production while increased the activities of antioxidant enzymes Gpx and SOD (P < 0.01), and decreased the levels of serum and protein expression of IL-1β, IL-6 and TNF-α (P < 0.01), as well as the expression levels of TLR4, NF-κB P65 and VCAM-1 (P < 0.01).

  Conclusion  Chrysophanol could play a protective role in IgA nephropathy rats, and its mechanism may be related to alleviating kidney injury and regulating immune response.