Abstract 15720: Synergistic Effect of Acetylation and Methylation Modifiers in Attenuating Lung Vascular Hyperpermeability in Endotoxemia-Induced Inflammatory Lung Injury

Abstract

Background: Migration of fluid and inflammatory cells across vascular endothelial barrier is crucial in pathogenesis of acute lung injury (ALI) in sepsis. Currently no treatment can effectively improve the profound dysregulation of lung endothelial barrier in ALI. Hypothesis: We hypothesized that combinatorial treatment with DNA methyl transferase inhibitor 5-Aza 2-deoxycytidine (Aza) and histone deacetylase (HDAC) inhibitor Trichostatin A (TSA) would synergistically preserve lung microvascular endothelial barrier function. Methods and Results: The trans-endothelial electrical resistance (TER) and capillary filtration coefficient (K fc ) data show that in LPS-exposed endothelial cells and mice, therapy with Aza+TSA leads to a significant decrease in lung microvascular permeability as compared with either alone. The ChiP data show that the VE-cadherin promoter region was more acetylated at histone 3 in LPS-induced lung ECs treated with Aza+TSA than either alone. In an ALI mouse model, post-injury treatment with a single dose of Aza+TSA prevented lung injury and afforded a significantly higher survival rate (80%) as compared with mice treated with either Aza or TSA alone. These effects were mediated by a significant attenuation of adverse lung histopathological changes and preservation of endothelial barrier integrity. Aza+TSA also significantly reduced neutrophil infiltration in the ALI model. The RT-PCR array data revealed that 42 inflammation-related miRNAs were differentially expressed in LPS-induced endothelial cells, among which miRNA-92a, 125b, 133a, 146, 214, 222, and 424 were strongly upregulated. Importantly, Aza+TSA treatment significantly reduced the expression of these miRNAs. The protection was ascribed to inhibition of the eNOS-Cav1-MLC2 signaling pathway and enhanced acetylation of histone markers on the VE-cadherin promoter. Conclusions: These data for the first time show the efficacy of synergistic effect of Aza+TSA therapy in preventing ALI in LPS-induced endotoxemia, and raise the possibility of an essential role of DNMT and HDAC in pathogenesis of ALI. This novel combinatorial regimen may improve and prolong the lives of people with ALI.