Inhibitive Effect and Mechanism of Ursolic Acid on TGF-β1 and IL-1 Expression in Silicosis Rat

Objective To study possible mechanism of inhibitive effect of ursolic acid on transforming growth factor beta-1 (TGF-β1) and interleukin-1 (IL-1) expressions in silicosis rats.

Methods Totally 80 Wistar rats were randomly divided into control, model, ursolic acid, and solvent control groups, with 20 rats each. Except the control group, the other groups were induced by intratracheal instillation of silica (SiO₂) (250 mg/kg). Then 40 mg/kg ursolic acid, 0.6% (mass fraction) sodium carboxymethyl cellulose (10 mL/kg) solution, and normal saline (10 mL/kg) were given to ursolic acid, solvent control, and control groups respectively for 56 consecutive phosphorylated days. ELISA was used to detect serum IL-1 and TGF-β1 in rats. Immunohistochemical and Western blot assays were applied to detect phosphorated protein kinase B (p-AKT1) in lung tissues.

Results Compared with the control group, the contents of IL-1 and TGF-β1 and the expression of p-AKT1 were significantly higher in the model group and the solvent control group (P < 0.05). However, down-regulations were observed in the ursolic acid group compared with the model group and the solvent control group (P < 0.05). According to the linear regression analysis, the correlation coefficients of the contents of IL-1 and TGF-β1 with p-AKT1 at four time points were greater than 0 (P < 0.01).

Conclusions Ursolic acid could reduce the expression of IL-1 and TGF-β1 and alleviate the development of silicosis probably by inhibiting p-AKT1 activation.