Daily Moderate Ethanol Ingestion Attenuates Postischemic Microvascular Dysfunctio

University Of Missouri-Columbia, Columbia MO

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Abstract

DESCRIPTION (provided by applicant): Regular consumption of ethanol (EtOH) at low to moderate levels protects organs and microvasculature from the deleterious effects of ischemia and reperfusion (I/R). Recently, we discovered that antecedent ethanol ingestion provokes the development of an anti-inflammatory phenotype (reduced postischemic formation of inflammatory mediators and markedly attenuated adhesion molecule expression, oxidant production, and leukocyte rolling, adhesion, and emigration in postcapillary venules) via a novel mechanism that remains effective in the presence of co-existing risk factors for cardiovascular disease. Surprisingly, our work uncovered important roles for proinflammatory calcitonin gene-related peptide (CGRP) and tumor necrosis factor-? (TNF) mediated neutrophil activation during the period of ethanol exposure in initiating this adaptive transformation that becomes apparent in postcapillary venules when tissues are exposed to I/R 24 hrs after EtOH. In the current proposal, we seek to build on these fundamental observations to evaluate the overall hypothesis that daily moderate EtOH induces TRPV1-dependent CGRP release from sensory neurons, which in turn activates CD4+ T lymphocytes to express tumor necrosis factor-? (TNF). TNF-dependent, neutrophil proteasemediated generation of signals in the interstitium engage endothelial integrin ?v?3 to induce increased HO-1 expression/activity to limit postischemic microvascular dysfunction. To address this postulate, we propose to determine the roles of: (1) EtOH-induced, CGRP-dependent activation of T lymphocytes, which subsequently produce TNF to activate tissue resident neutrophils to proteolytically generate signals that trigger the development of an anti-inflammatory phenotype in response to antecedent ethanol; and (2) neutrophil protease-initiated, ?v?3 integrin-dependent increased HO-1 expression and activity as downstream mediators of the anti-inflammatory phenotype seen during I/R. Intravital microscopic approaches will be used to quantify postischemic leukocyte/endothelial cell interactions. The effects of EtOH to elevate plasma and tissue CGRP and TNF levels, induce T cell and neutrophil activation, and increase HO-1 expression and activity to prevent I/R-induced endothelial adhesion molecule and inflammatory mediator expression will also be investigated. Significance: This work will identify new links between CGRP-activated T cells, signals generated by the proteolytic activity of TNF-activated neutrophils, and ?v?3-dependent HO-1 expression/activity in the acquisition of tolerance to I/R by antecedent ethanol ingestion. Completing these studies will provide the mechanistic basis for development of translational therapeutics in relevant patient populations.