BACKGROUND: Acute lung injury (ALI) is a life-threatening inflammatory disease. Macrophage polarization plays a key role in the occurrence of pulmonary inflammation. Therefore, regulating the phenotype of macrophages is a potentially effective method for the treatment of ALI. This study aims to explore the potential molecular mechanism of SOCS1 in M1 polarization of macrophages and ALI.
METHODS: The ALI animal model was established by intratracheal infusion of LPS (5 mg/kg), and the cell model was established by stimulating RAW264.7 macrophages with LPS (1 μg/mL). The levels of autophagy and macrophage markers were detected by immunofluorescence, MDC staining, western blot. ELISA was used to measure the levels of inflammatory cytokines. The level of MPO in the lungs was determined, and inflammatory cells and proteins in BALF were detected.
RESULTS: The expressions of SOCS1, TFEB and p-AMPK decreased in the ALI model. Overexpression of SOCS1 inhibited the M1 polarization of macrophages induced by LPS, reduced the expressions of pro-inflammatory factors IL-1β, IL-6 and TNF-α, increased the expression of anti-inflammatory factor IL-10, and decreased the expressions of iNOS, CD80 and CD86, and increase the expressions of Arg1, CD206 and CD163. Further studies have revealed that SOCS1 activates autophagy by up-regulating the expression of TFEB, thereby inhibiting the polarization of M1 in macrophages. Furthermore, SOCS1 can promote the nuclear translocation of TFEB, while the phosphorylation of AMPK can up-regulate SOCS1 to promote the expression of TFEB.
CONCLUSION: AMPK promotes nuclear transfer of TFEB by up-regulating SOCS1, thereby enhancing autophagy and inhibiting M1 polarization in macrophages, thus alleviating ALI.
