Cross-talk between inflammation and angiotensin II: studies based on direct transfection of cardiomyocytes with AT1R and AT2R cDNA - PubMed (original) (raw)

. 2012 Dec;237(12):1394-401.

doi: 10.1258/ebm.2012.012212.

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Cross-talk between inflammation and angiotensin II: studies based on direct transfection of cardiomyocytes with AT1R and AT2R cDNA

Xianwei Wang et al. Exp Biol Med (Maywood). 2012 Dec.

Abstract

Ischemic myocardium exhibits inflammation, local angiotensin II (Ang II) generation and up-regulation of LOX-1, a lectin-like ox-LDL receptor. To define the inter-active roles of Ang II and inflammation in furthering tissue injury, cultured HL-1 cardiomyocytes were treated with Ang II. Ang II treatment up-regulated the expression of Ang II type 1 (AT1R) and type 2 (AT2R) receptors as well as LOX-1. Ang II also activated p44/42MAPK, p38MAPK, c-Jun and NF-κB, and increased the expression of inflammation-related genes (interleukins-6, interleukins-10, tumor necrosis factor-α, intercellular adhesion molecule-1). To study how inflammation per se might affect expression of Ang II receptors and LOX-1, cultured, cardiomyocytes were treated with lipopolysaccharide (LPS). Like Ang II, LPS increased the expression of AT1R, AT2R and LOX-1. LPS also activated mitogen-acticated protein kinase (MAPKs), c-Jun and NF-κB, and pro-inflammatory genes. The selective inhibitors of MAPKs, c-Jun and NF-κB each blocked the transcription of LOX-1 and pro-inflammatory genes in response to Ang II as well as LPS. These observations suggested a positive feedback between Ang II and inflammation. To delineate the role of AT1R and AT2R in LOX-1 expression, another set of cardiomyocytes were transfected with AT1R or AT2R cDNA. Forced over-expression of AT1R resulted in activation of MAPKs, c-Jun and NF-κB, up-regulation of inflammatory genes and LOX-1; on the other hand forced AT2R over-expression induced up-regulation of pro-apoptotic signals (pro-IL-1β and IL-1β), and decreased LOX-1 expression. These studies show that both Ang II and inflammation mediator LPS up-regulate AT1R, AT2R and LOX-1 expression. Up-regulation of AT1R promotes inflammation and LOX-1 expression, whereas up-regulation of AT2R promotes apoptosis signals and decreases LOX-1 expression.

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