Protective effect of modified Huangqi Chifeng decoction on immunoglobulin A nephropathy through toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B signaling pathway

OBJECTIVE

To examine the nephroprotective mechanism of modified Huangqi Chifeng decoction (, MHCD) in immunoglobulin A nephropathy (IgAN) rats.

METHODS

To establish the IgAN rat model, the bovine serum albumin, lipopolysaccharide, and carbon tetrachloride 4 method was employed. The rats were then randomly assigned to the control, model, telmisartan, and high-, medium-, and low-dose MHCD groups, and were administered the respective treatments via intragastric administration for 8 weeks. The levels of 24-h urinary protein, serum creatinine (CRE), and blood urea nitrogen (BUN) were measured in each group. Pathological alterations were detected. IgA deposition was visualized through the use of immunofluorescence staining. The ultrastructure of the kidney was observed using a transmission electron microscope. The expression levels of interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-β1 (TGF-β1) were examined by immunohistochemistry and quantitative polymerase chain reaction. Levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor-kappa B (NF-κB) P65, were examined by immunohistochemistry, Western blotting, and quantitative polymerase chain reaction.

RESULTS

The 24-h urine protein level in each group increased significantly at week 6, and worsen from then on. But this process can be reversed by treatments of telmisartan, and high-, medium-, and low-dose of MHCD, and these treatments did not affect renal function. Telmisartan, and high-, and medium-dose of MHCD reduced IgA deposition. Renal histopathology demonstrated the protective effect of high-, medium-, and low-dose of MHCD against kidney injury. The expression levels of MCP-1, IL-6, and TGF-β1 in kidney tissues were downregulated by low, medium and high doses of MHCD treatment. Additionally, treatment of low, medium and high doses of MHCD decreased the protein and mRNA levels of TLR4, MyD88, and NF-κB.

CONCLUSIONS

MHCD exerted nephroprotective effects on IgAN rats, and MHCD regulated the expressions of key targets in TLR4/MyD88/NF-κB signaling pathway, thereby alleviating renal inflammation by inhibiting MCP-1, IL-6 expressions, and ameliorating renal fibrosis by inhibiting TGF-β1 expression.