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

Exp Biol Med (Maywood). 2012 Dec;237(12):1394-401. doi: 10.1258/ebm.2012.012212.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Angiotensin II / genetics
  • Angiotensin II / metabolism*
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Cell Line
  • Cytokines / biosynthesis
  • Cytokines / genetics
  • DNA, Complementary / genetics
  • Extracellular Signal-Regulated MAP Kinases / genetics
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Inflammation / genetics
  • Inflammation / metabolism
  • Inflammation / pathology
  • Inflammation Mediators / metabolism
  • Lipopolysaccharides / pharmacology
  • Mice
  • Myocytes, Cardiac / metabolism*
  • Myocytes, Cardiac / pathology
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Receptor, Angiotensin, Type 1 / biosynthesis*
  • Receptor, Angiotensin, Type 1 / genetics
  • Receptor, Angiotensin, Type 2 / biosynthesis*
  • Receptor, Angiotensin, Type 2 / genetics
  • Scavenger Receptors, Class E / biosynthesis
  • Scavenger Receptors, Class E / genetics
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Up-Regulation*

Substances

  • Cytokines
  • DNA, Complementary
  • Inflammation Mediators
  • Lipopolysaccharides
  • NF-kappa B
  • Olr1 protein, mouse
  • Receptor, Angiotensin, Type 1
  • Receptor, Angiotensin, Type 2
  • Scavenger Receptors, Class E
  • Angiotensin II
  • Extracellular Signal-Regulated MAP Kinases