Novel anti-inflammatory mechanisms of N-Acetyl-Ser-Asp-Lys-Pro in hypertension-induced target organ damage

Am J Physiol Heart Circ Physiol. 2008 Mar;294(3):H1226-32. doi: 10.1152/ajpheart.00305.2007. Epub 2008 Jan 4.

Abstract

High blood pressure (HBP) is an important risk factor for cardiac, renal, and vascular dysfunction. Excess inflammation is the major pathogenic mechanism for HBP-induced target organ damage (TOD). N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP), a tetrapeptide specifically degraded by angiotensin converting enzyme (ACE), reduces inflammation, fibrosis, and TOD induced by HBP. Our hypothesis is that Ac-SDKP exerts its anti-inflammatory effects by inhibiting: 1) differentiation of bone marrow stem cells (BMSC) to macrophages, 2) activation and migration of macrophages, and 3) release of the proinflammatory cytokine TNF-alpha by activated macrophages. BMSC were freshly isolated and cultured in macrophage growth medium. Differentiation of murine BMSC to macrophages was analyzed by flow cytometry using F4/80 as a marker of macrophage maturation. Macrophage migration was measured in a modified Boyden chamber. TNF-alpha release by activated macrophages in culture was measured by ELISA. Myocardial macrophage activation in mice with ANG II-induced hypertension was studied by Western blotting of Mac-2 (galectin-3) protein. Interstitial collagen deposition was measured by picrosirius red staining. We found that Ac-SDKP (10 nM) reduced differentiation of cultured BMSC to mature macrophages by 24.5% [F4/80 positivity: 14.09 +/- 1.06 mean fluorescent intensity for vehicle and 10.63 +/- 0.35 for Ac-SDKP; P < 0.05]. Ac-SDKP also decreased galectin-3 and macrophage colony-stimulating factor-dependent macrophage migration. In addition, Ac-SDKP decreased secretion of TNF-alpha by macrophages stimulated with bacterial LPS. In mice with ANG II-induced hypertension, Ac-SDKP reduced expression of galectin-3, a protein produced by infiltrating macrophages in the myocardium, and interstitial collagen deposition. In conclusion, this study demonstrates that part of the anti-inflammatory effect of Ac-SDKP is due to its direct effect on BMSC and macrophage, inhibiting their differentiation, activation, and cytokine release. These effects explain some of the anti-inflammatory and antifibrotic properties of Ac-SDKP in hypertension.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Angiotensin II / pharmacology
  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Azo Compounds
  • Blotting, Western
  • Cardiomegaly / pathology
  • Cell Separation
  • Collagen / metabolism
  • Fibrosis / pathology
  • Galectin 3 / biosynthesis
  • Heart Rate / physiology
  • Hypertension / chemically induced
  • Hypertension / complications
  • Hypertension / pathology*
  • In Vitro Techniques
  • Inflammation / drug therapy
  • Inflammation / etiology
  • Inflammation / pathology*
  • Kidney / metabolism
  • Kidney / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Myocardium / metabolism
  • Myocardium / pathology
  • Neutrophil Infiltration / drug effects
  • Oligopeptides / pharmacology*
  • Stem Cells / physiology
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Anti-Inflammatory Agents
  • Azo Compounds
  • Galectin 3
  • Oligopeptides
  • Tumor Necrosis Factor-alpha
  • Angiotensin II
  • C.I. direct red 80
  • Collagen
  • goralatide