title: Novel anti-inflammatory mechanisms of N-Acetyl-Ser-Asp-Lys-Pro in hypertension-induced target organ damage.
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.
authors.affiliation: Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, MI 48202, USA.
authors.forename: Umesh
authors.initials: U
authors.lastname: Sharma
authors.forename: Nour-Eddine
authors.initials: NE
authors.lastname: Rhaleb
authors.forename: Saraswati
authors.initials: S
authors.lastname: Pokharel
authors.forename: Pamela
authors.initials: P
authors.lastname: Harding
authors.forename: Saman
authors.initials: S
authors.lastname: Rasoul
authors.forename: Hongmei
authors.initials: H
authors.lastname: Peng
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Carretero
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001391:Azo Compounds; D015153:Blotting, Western; D006332:Cardiomegaly / Q000473:pathology; D002469:Cell Separation; D003094:Collagen / Q000378:metabolism; D005355:Fibrosis / Q000473:pathology; D037502:Galectin 3 / Q000096:biosynthesis; D006339:Heart Rate / Q000502:physiology; D006973:Hypertension / Q000139:chemically induced / Q000150:complications / Q000473:pathology*; D066298:In Vitro Techniques; D007249:Inflammation / Q000188:drug therapy / Q000209:etiology / Q000473:pathology*; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D020556:Neutrophil Infiltration / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology*; D013234:Stem Cells / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D001391:Azo Compounds; D037502:Galectin 3; D009842:Oligopeptides; D014409:Tumor Necrosis Factor-alpha; D000804:Angiotensin II; C009798:C.I. direct red 80; D003094:Collagen; C058504:goralatide