The effect of FTY720 at different doses and time-points on LPS-induced acute lung injury in rats

We sought to assess the protective effect of different doses of Fingolimod (FTY720) in a rat model of acute lung injury (ALI) induced by intratracheal instillation of lipopolysaccharide (LPS) and explored the underlying mechanisms. The ALI model was established in rats and different doses of FTY720 (0.1 mg/kg, 0.2 mg/kg, 0.5 mg/kg, 1 mg/kg, or 2 mg/kg) were injected intraperitoneally. Lung computed tomography and blood gas analyses were performed at 6 h, 24 h, and 48 h after intraperitoneal injection, and the lung tissues were extracted to prepare paraffin sections for histopathological examination. The levels of inflammatory cytokines (TNF-α, IL-6, and IL-1β) were detected by ELISA, and the expressions of inflammatory pathway proteins in each group were measured by Western blot analysis. A single intraperitoneal injection of FTY720 inhibited LPS-induced NF-κB activation, reduced the level of inflammatory cytokines, and decreased the infiltration of inflammatory cells. Moreover, it alleviated lung tissue injury, as shown by marked attenuation of pulmonary oedema and improved arterial partial pressure of oxygen (PaO₂) and the general condition of ALI rats. In conclusion, our results demonstrate the protective effect of FTY720 against LPS-induced ALI. The underlying mechanism of the protective effect may involve inhibition of LPS-induced activation of NF-κB and regulation of the inflammatory pathway to alleviate barrier dysfunction of alveolar capillaries.