Thymoquinone effectively alleviates lung fibrosis induced by paraquat herbicide through down-regulation of pro-fibrotic genes and inhibition of oxidative stress.

The potential preventive and therapeutic effects of thymoquinone (TQ) and its molecular mechanism were evaluated in paraquat (PQ)-induced pulmonary fibrosis in mice. TQ was administered orally at the doses of 20 and 40mg/kg during the course and after development of fibrosis. Pathological changes, expressions of genes involved in fibrogenesis, hydroxyproline (HP) and oxidative stress parameters were determined in the lung tissues. TQ dose-dependently recovered the pathological changes induced by PQ. TQ decreased hydroxyproline content, lipid peroxidation and restored the antioxidant enzymes to the normal values. In molecular level, expressions of TGF-β1, α-SMA, collagen 1a1 and collagen 4a1 genes were also returned to the control level by TQ. This study indicated that TQ has the preventive and therapeutic potentials for the treatment of lung fibrosis by inhibition of oxidative stress and down-regulation of profibrotic genes.