Combined administration of epigenetic modifiers regulates macrophage polarization by HIF‐2α signaling and protects mice from acute lung injury

Abstract

ObjectiveAcute lung injury (ALI) is a common pulmonary disease caused by bacterial infection leading to an imbalance between pro‐inflammatory and anti‐inflammatory immune responses. Studies have shown that macrophage polarization (M1 and M2) during ALI plays a key role in regulating these responses. Here, we have examined the use of DNA methyltransferase (DNMT1) inhibitor Procainamide (PRO) and histone deacetylase 6 (HDAC6) inhibitor Tubastatin A (TBA) together in protecting mice from ALI.HypothesisWe hypothesized that combined treatment with PRO+TBA would reduce inflammation and promote an anti‐inflammatory M2 macrophage phenotype by regulating the HIF2α signaling pathway.MethodsTo show the effect of PRO+TBA, lipopolysaccharide (LPS)‐induced macrophages (RAW 264.7) were treated with either PRO (500 μM), TBA (5 μM), or together (PRO+TBA) for 24 hours. The mRNA and protein expressions of HIF‐2α, NOS2 (M1), and CD206 (M2) were measured by RT‐PCR and Western analyses in lung tissue and macrophages.ResultsOur results revealed that LPS significantly decreased the mRNA and protein expressions of HIF‐2α in lung tissue and macrophages. This expression was significantly increased in LPS‐induced macrophages treated with PRO+TBA. Furthermore, LPS induces the expression of M1 macrophages and increased expression of NOS2 and other inflammatory cytokines whereas LPS induced macrophages treated with PRO+TBA considerably suppressed the expression of M1 macrophages and increased the expression of CD206 and anti‐inflammatory cytokines by M2 macrophages. These results suggest that PRO+TBA treatment together generates more M2 macrophages there by reducing the LPS‐induced inflammatory responses.ConclusionOverall, these data suggest that the combinatorial treatment with PRO+TBA regulates macrophage cell polarization and protects mice from ALI through HIF‐2α signaling pathway. Thus, epigenetic modifiers may be used as potential therapeutic drugs for ALI.Support or Funding InformationAmerican heart Association‐16GRNT30950010 to JRThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.