Protective effects of isorhynchophylline against silicon-dioxide-induced lung injury in mice

Inhalation of silicon dioxide (SD) results in pulmonary inflammatory responses and fibrosis. Isorhynchophylline (Isorhy) is the main alkaloid in the traditional Chinese herb Tripterygium wilfordii, which is reported to have anti-inflammatory activities in the nervous system. However, the effects of Isorhy on SD-induced pulmonary inflammation and fibrosis in mice are unknown. Male mice were exposed to a single dose of SD (2.5 mg/kg, intranasal inoculation) to induce pulmonary fibrosis (PF). The mice were woken up and immediately treated with Isorhy (20 mg/kg, intraperitoneal injection) for 14 or 42 days. The effects of Isorhy on inflammatory responses and lung fibrosis induced by SD were then investigated. After the 14-day treatment, there was a significant reduction in inflammatory cell infiltration in the lungs of mice, with reduced recruitment of inflammatory cells to the lungs. The concentration of pro-inflammatory factors in the bronchoalveolar lavage fluid was reduced, which alleviated inflammatory injury in the lung tissue. After the 42-day treatment, Isorhy alleviated inflammation and inhibited the release of fibrogenic factors in mice with PF. Isorhy also significantly reduced collagen deposition in the lung tissues of mice. Isorhy has the ability to reduce inflammatory responses and fibrosis associated with SD-induced acute lung injury.