Circular RNA circVAPA mediates alveolar macrophage activation by modulating miR-212-3p/Sirt1 axis in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening condition associated with the inflammatory activation of alveolar macrophages. Here, we examined the role of circVAPA in regulating inflammasome activation and macrophage inflammatory polarization in an ARDS model.

circVAPA expression levels were analyzed in macrophages isolated from healthy controls and patients with ARDS. In vitro cell models of mouse alveolar macrophages and an in vivo mouse ARDS model were established through Lipopolysaccharide (LPS) stimulation. The effects of circVAPA knockdown on macrophage inflammatory polarization, inflammasome activation, and pulmonary tissue damage were investigated in both cell and animal models. The interaction between circVAPA and downstream factors was verified through a luciferase reporter assay and by silencing circVAPA.

circVAPA upregulation in alveolar macrophages was associated with the inflammation in ARDS patients. circVAPA was also upregulated in LPS-stimulated mouse alveolar macrophages (MH-S cells). Additionally, circVAPA knockdown attenuated the inflammatory activation of MH-S cells and reduced the expression of pyroptosis-related proteins. circVAPA silencing also mitigated the inflammatory effects of LPS-stimulated MH-S cells on lung epithelial cells (MLE-12), and alleviated the inflammatory damage in the pulmonary tissue of ARDS mouse model. We further showed that miR-212-3p/Sirt1 axis mediated the functional role of circVAPA in the inflammatory polarization of MH-S cells.

Our data suggest that circVAPA promotes inflammasome activity and macrophage inflammation by modulating miR-212-3p/Sirt1 axis in ARDS. Targeting circVAPA may be employed to suppress the inflammatory activation of alveolar macrophages in ARDS.