title: Homocysteine elicits an M1 phenotype in murine macrophages through an EMMPRIN-mediated pathway.
abstract: BACKGROUND
  Hyperhomocysteinemia (HHcy) is associated with inflammatory diseases and is known to increase the production of reactive oxygen species (ROS), matrix metalloproteinase (MMP)-9, and inducible nitric oxide synthase, and to decrease endothelial nitric oxide production. However, the impact of HHcy on macrophage phenotype differentiation is not well-established. It has been documented that macrophages have 2 distinct phenotypes: the "classically activated/destructive" (M1), and the "alternatively activated/constructive" (M2) subtypes. We hypothesize that HHcy increases M1 macrophage differentiation through extracellular matrix metalloproteinase inducer (EMMPRIN), a known inducer of matrix metalloproteinases.
  
  
  METHODS
  murine J774A.1 and Raw 264.7 macrophages were treated with 100 and 500 μmol/L Hcy, respectively, for 24 h. Samples were analyzed using Western blotting and immunocytochemistry.
  
  
  RESULTS
  Homocysteine treatment increased cluster of differentiation 40 (CD40; M1 marker) in J774A.1 and Raw 264.7 macrophages. MMP-9 was induced in both cell lines. EMMPRIN protein expression was also increased in both cell lines. Blocking EMMPRIN function by pre-treating cells with anti-EMMPRIN antibody, with or without Hcy, resulted in significantly lower expression of CD40 in both cell lines by comparison with the controls. A DCFDA assay demonstrated increased ROS production in both cell lines with Hcy treatment when compared with the controls.
  
  
  CONCLUSIONS
  Our results suggest that HHcy results in an increase of the M1 macrophage phenotype. This effect seems to be at least partially mediated by EMMPRIN induction.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.|Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Winchester
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.|Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.
authors.forename: Sudhakar
authors.initials: S
authors.lastname: Veeranki
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.|Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Givvimani
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.|Department of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, 500 South Preston Street, HSC Building A, KY 40202, USA.
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D051926:Basigin / Q000096:biosynthesis*; D015153:Blotting, Western; D019013:CD40 Antigens / Q000096:biosynthesis; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006710:Homocysteine / Q000494:pharmacology*; D007150:Immunohistochemistry; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D000911:Antibodies, Monoclonal; C497887:Bsg protein, mouse; D019013:CD40 Antigens; D017382:Reactive Oxygen Species; D006710:Homocysteine; D051926:Basigin; D020780:Matrix Metalloproteinase 9
keywords: EMMPRIN; M1; MMP-9; ROS; dérivés réactifs de l’oxygène; homocysteine; homocystéine; macrophage; métalloprotéinase matricielle-9