Abstract 3112: Identifying NogoB Receptor As A Resilience Factor In Preventing Diabetes-associated Vasculature Complications Through The Regulation Of Histone Acetylation

Abstract

The COVID-19 pandemic has underlined the link between cytokine storms and acute lung injury (ALI). Importantly, diabetic patients demonstrate a higher susceptibility to severe lung injury and increased mortality, indicating that hyperglycemia could compromise the host's resilience necessary to counteract cytokine-induced lung injury. Single-nucleus RNA-seq data from COVID-19 patients reveal a significant decline in endothelial cells expressing the Nogo-B receptor (NgBR). Our recent research confirms that NgBR plays a pivotal role in maintaining the structural integrity of blood vessels by regulating KAT7-mediated histone acetylation.To investigate NgBR's resilience role, we examined its expression in response to hyperglycemic stress. We found a reduction in NgBR expression levels in endothelial cells (ECs) isolated from db/db mice, mirroring observations in ECs from Streptozocin (STZ)-injected mice. Moreover, when human microvascular endothelial cells (HMECs) were exposed to high glucose levels, NgBR expression increased initially but subsequently declined with extended exposure. This inhibitory effect of high glucose on NgBR expression was both time- and dose-dependent and was mediated through the DNA methylation mechanism.We also examined the effects of NgBR loss on the integrity of pulmonary vasculature and the pathogenesis of lung injury. We induced genetic depletion of NgBR in ECs through tamoxifen administration and found severe lung hemorrhage in NgBR inducible endothelial cell-specific knockout (iecKO) mice. Impaired EC junctions were identified by reduced VE-cadherin immunostaining. Following exposure to a lipopolysaccharide (LPS), ALI model, we observed increased neutrophil accumulation in the alveolar or interstitial space, alveolar wall thickening, and edema in the lungs of either NgBR iecKO or diabetic mice. RNA-seq analysis revealed that NgBR knockdown resulted in decreased transcription of CDC42, a key gene regulating endothelial adherens junction through KAT7-mediated histone acetylation. Our findings indicate that NgBR is a resilience factor for maintaining vascular integrity, and epigenetic medicine can rescue NgBR loss in endothelial cells and the severity of diabetes-associated acute lung injury.