YAP1/HIF-1α can Improve Sepsis-Induced ALI by Regulating the Level of Autophagy and Balancing the M1-M2 Polarization of Macrophages

Abstract

Background: Acute lung injury (ALI) is an important cause of death in patients with sepsis. The imbalance of M1-M2 polarization of macrophages (MACs) is a momentous factor leading to the progression of sepsis-induced ALI. Moreover, Yes-associated protein 1 (YAP1)/Hypoxia-inducible factor-1α (HIF-1α) plays a pivotal role in regulating inflammatory response, oxidative stress, and autophagy. Therefore, this study aimed to explore whether YAP1/HIF-1α regulates sepsis-induced ALI through autophagy and polarization of macrophages. Methods: Initially, THP-1 cells were cultured in vitro and the phenotype transformation of M1 and M2 was induced by treating them with Lipopolysaccharide (LPS) + Interferon-γ (IFN-γ) or Interleukin-4 (IL-4), respectively. The expression levels of YAP1, HIF-1α, M1 markers, and M2 markers were assessed using Western blot analysis. The impacts of YAP1 and HIF-1α overexpression on M1 markers (inducible Nitric Oxide Synthase (iNOS) and Cluster of Differentiation (CD)80), M2 markers (Arginase-1 (ARG1) and CD206), autophagy markers (Microtubule-associated protein 1A/1B-light chain 3B-II/I (LC3BII/I), Beclin1, and p62), and inflammatory factors (Tumor Necrosis Factor-alpha (TNF-α), IL-6, and IL-10) were evaluated in LPS-induced sepsis ALI cell model in vitro using cell transfection, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot analysis. Finally, the expression of LC3B in macrophages was determined using the immunofluorescence method. Results: The expression level of YAP1 was found to be up-regulated in M2 macrophages, while the expression of HIF-1α was up-regulated in M1 macrophages. Furthermore, YAP1 overexpression promoted the transformation of LPS-induced ALI macrophages into M2 phenotype, increased the expression of autophagy factors (LC3BII/I and Beclin1), and reduced the activity of inflammatory factors (TNF-α and IL-6). However, HIF-1α overexpression could balance the M2 polarization of macrophages induced by YAP1 overexpression. Additionally, HIF-1α overexpression elevated the expression of macrophage autophagy factors (p62) and inflammatory factors (TNF-α and IL-6) and reduced the expression of macrophage autophagy factors (LC3BII/I and Beclin1) and the viability of IL-10. Conclusions: In summary, YAP1/HIF-1α can improve sepsis-induced ALI, thereby regulating the level of macrophage autophagy and balancing M1-M2 polarization.