Suppressing Sart1 to modulate macrophage polarization by siRNA-loaded liposomes: a promising therapeutic strategy for pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and diffuse form of interstitial lung disease of unknown etiology with a fatal outcome. Although various strategies for IPF have been developed over the last few decades, no significant positive impact on the prognosis of IPF has been observed. According to the current paradigm, macrophages have been recognized to play a significant role in IPF pathogenesis. Here, we report a potential nanomedicine-based gene therapy for IPF based on regulate macrophage polarization. Method: C57BL/6 mice were obtained and used to establish a bleomycin (BLM)-induced pulmonary fibrosis animal model, and Sart1 siRNA-loaded liposomes were designed for in vivo experiment. The experimental animals were administered BLM intratracheally on day 0 and treated with Sart1 siRNA on days 14 and 17. In the in vitro experiment, we further examined the function of Sart1 in macrophages. Results: Our data indicated that the liposomes could passively target the fibrotic area in the lung and efficiently accumulate in macrophages. The suppression of Sart1 by siRNA-loaded liposomes significantly protected mice against BLM-induced lung injury and fibrosis, which was attributed to attenuated M2 macrophage infiltration in the lung. Conclusion: Our study provides a valuable reference for modulating macrophage polarization and a promising strategy for the treatment of pulmonary fibrosis in clinical settings.