Abstract 12613: Combinatorial Treatment With Epigenetic Modifiers Reduce Endotoxemia-Induced Inflammation in Human Macrophages and Favors Anti-Inflammatory M2 Plasticity

Abstract

Introduction: Macrophages are key mediators of the pathogenesis of acute lung injury (ALI). During ALI, lung macrophages shift into the M1 phenotype and induce severe inflammatory responses and lung tissue damage. Recently, we have shown that pan inhibition of DNA methyl transferase (DNMT) and histone deacetylase (HDAC) abrogated the inflammation and protected the mice from endotoxemia-induced ALI. Hypothesis: We hypothesize that the treatment with a combination of DNMT1-specific inhibitor, procainamide (PRO) and HDAC6-specific inhibitor, tubastatin A (TBA) attenuates lipopolysaccharide (LPS)-induced inflammation in human macrophages via polarization of macrophages towards anti-inflammatory M2 phenotype. Methods & Results: Human macrophage cell line (THP-1) was employed in this study. RNA sequencing analysis has identified a significant reduction in the mRNA expression of a panel of pro-inflammatory genes by PRO+TBA treatment in LPS-induced macrophages, and these results were validated and confirmed by qRT-PCR for the expression of TNFα and IL1β. The expression of pro-inflammatory genes IL1β, TNFα and M1 macrophage marker CD80 was significantly decreased (studied by various analysis) by PRO+TBA treatment at 24 hrs after in LPS challenged macrophages, compared to untreated or treated with either PRO alone or TBA alone (Fig. 1 and 2). On the other hand, the expression of anti-inflammatory gene TSG6 and M2 macrophage marker CD206 were significantly increased by PRO+TBA treatment at 72 hrs after LPS challenged macrophages, compared to untreated or treated with either PRO alone or TBA alone (Fig. 2). Conclusions: Our results have clearly demonstrated that the combined PRO+TBA treatment significantly reduced the expression of pro-inflammatory genes and M1 phenotype marker; and increased the expression of anti-inflammatory genes and M2 phenotype marker in human macrophages challenged with LPS.