Exploring the Mechanism of Macrophages in Influenza A Virus-Induced Pneumonia through miR-1260 Targeting of Sema3A
Influenza virus is a seasonal respiratory infectious virus that poses a global threat. Macrophages, as innate immune cells, play a crucial role in combating influenza virus infection. In this study, we established a mouse model of pneumonia infected with influenza A virus (IAV), a composite mouse model of IAV infection combined with macrophage clearance, and an in vitro co-culture system of lung epithelial cells and macrophages to comprehensively simulate the process of IAV infection. By utilizing HE staining, immunohistochemistry, and immunofluorescence techniques, we discovered that IAV infection can significantly induce lung tissue damage and promote macrophage recruitment in mice. More specifically, after infecting the co-culture system with IAV, we observed morphological changes in both upper chamber MLE-12 cells and lower chamber RAW246.7 cells, along with a significant increase in the viral load and levels of inflammatory factors. High-throughput sequencing of RAW246.7 cells detected and validated the involvement of miR-1260 and Sema3A-mediated PI3K/AKT/mTOR signaling pathways in the infection process. Subsequently, we transfected miRNA mimics, inhibitors, and Sema3A-siRNA into RAW264.7 cells. The post-transfection results indicated that miR-1260 can synergistically intensify cell damage by targeting the Sema3A-mediated PI3K/AKT/mTOR signaling pathways. In the composite model of lung macrophage clearance combined with IAV-induced pneumonia, the mice exhibited worse conditions in terms of body weight, food intake, organ index, levels of inflammatory factors, viral load, and pathological damage compared to the IAV pneumonia model. These results are associated with the mechanism that miR-1260 targets Sema3A to mediate the PI3K/AKT/mTOR pathways. In conclusion, macrophages exert an anti-IAV effect by antagonizing the miR-1260 targeting Sema3A-mediated PI3K/AKT/mTOR signaling pathways.