Protective effects of neferine on amiodarone-induced pulmonary fibrosis in mice

The effects of neferine, a bisbenzylisoquinline alkaloid extracted from the Chinese traditional medicine seed embryo of Nelumbo nucifera Gaertn, on amiodarone-induced pulmonary fibrosis in mice were evaluated. Adult Kunming mice were induced to develop pulmonary fibrosis through intratracheal instillation of amiodarone (6.25 mg/kg) on the 1st, 3rd and 5th day. Mice were treated orally with saline, neferine (20 mg/kg), prednisolone (15 mg/kg), pirfenidone (100 mg/kg) twice a day after the third amiodarone instillation. On Day 21, all the lung tissues were collected for hydroxyproline measurement and the histological examination by hematoxylin-eosin and Masson staining. All the blood sample were collected for surfactant protein-D (SP-D) levels assay, Th1/Th2 balance valuation, CD4+CD25+ regulatory T cells (Tregs) analysis by Enzyme-linked immunosorbent assay and flow cytometry. Our data showed that neferine significantly restored the significant reductions in body weights, the increased levels of lung index and hydroxyproline, the abnormal histological findings, the serum SP-D increase, the Th1/Th2 imbalance by decreasing IL-4 and increasing IFN-γ levels and the increases in the population of CD4+CD25+ Tregs associated with amiodarone instillation in mice. Similar changes were also observed in the prednisolone or pirfenidone treated mice. In conclusion, these results indicated that neferine possessed a significant inhibitory effect on amiodarone-induced pulmonary fibrosis, probably due to its properties of anti-inflammation, SP-D inhibition and restoring increased CD4+CD25+ Tregs which may modulate Th1/Th2 imbalance by suppressing Th2 response (from Th2 polarity toward a Th1 dominant response).