Protective effects of intranasal curcumin on silica-induced lung damage

Objective: Being anti-inflammatory and an antioxidant in nature, curcumin has been studied for its anti-asthmatic effects, but its impact on silicosis has not been investigated before. It is a form of occupational lung illness caused by inhaling crystalline silica. It is particularly common among those who work in construction-related sectors. Therefore, present study has been undertaken to investigate impact of intranasal curcumin on silica induced lung damage in mice model of silicosis. Materials and methods: Mice model of silicosis was developed by intranasal silica instillation (2.5 mg/mice) for different durations mainly 7, 14 and 21 days, where the longest duration of silica exposure (21 days) mimics chronic occupational exposure of silica dust leading to silicosis. Curcumin (5 mg/kg,i.n) and /or dexamethasone, a known corticosteroid (10 mg/kg,i.p) was administered an hour prior to silica administration. Results: Present study revealed silica induced lung damage in the mice model of silicosis characterized by airway inflammation, collagen deposition and enhanced expression of fibrosis markers (MMP-9, alpha-SMA, Hydroxyproline), which were significantly reduced in curcumin treatment groups. Inhibitory effects of curcumin were compared with standard drug, dexamethasone, a corticosteroid and was found better in protecting structural alterations in the lung. Damaged and abnormal mitochondria (enlarged and irregular shapes) were observed in silicosis group which were reduced in curcumin and dexamethasone treatment groups as revealed in transmission electron microscopic studies. Conclusions: Present study shows protective effects of intranasal curcumin on silica-induced airway inflammation and structural changes thereby lung damage. Hence, it can be considered as an alternative and complementary medication for silicosis.