Interferon Regulatory Factor 5 siRNA-Loaded Folate-Modified Cationic Liposomes for Acute Lung Injury Therapy.

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is an overwhelming pulmonary inflammation with limited clinical treatment strategies. Interferon regulatory factor 5 (IRF5) is a crucial regulator of inflammation factors, which can be upregulated under an inflammatory state and related to the efferocytosis of macrophages. Herein, IRF5 was knockdown by small interfering RNA (siIRF5) to promote the anti-inflammatory effect of macrophages. Macrophage-targeting cationic liposome modified by folate (FA-LP) was developed to deliver siIRF5 (FA-LP/siIRF5). Liposomes were characterized for their particle size, zeta potential, protein adsorption and hemolysis of red blood cells. The amount of IRF5 mRNA and the expression of IRF5 were measured using quantitative reverse transcription PCR (RT-qPCR) and western blot, respectively. The phenotype and efferocytosis of macrophages and the regulatory pathway of efferocytosis and biodistribution of liposomes in the ALI mice model were investigated. Data revealed that FA-LP/siIRF5 could obviously downregulate the expression of IRF5 in macrophages, skewing the polarization of macrophages to M2 phenotype (anti-inflammatory state) and thus improving their efferocytosis. Moreover, regulation of efferocytosis of macrophages by siIRF5 is related to the NF- B pathway. The in vivo biodistribution of FA-LP exhibited higher accumulation in the inflammatory lungs, suggesting that FA-LP could be considered as a promising gene delivery system and FA-LP/siIRF5 is an alternative strategy for the treatment of ALI/ARDS. To the best of our knowledge, this is the first study reporting that siIRF5 can be used for the treatment of ALI/ARDS.