title: Modification of β-Defensin-2 by Dicarbonyls Methylglyoxal and Glyoxal Inhibits Antibacterial and Chemotactic Function In Vitro.
abstract: BACKGROUND
  Beta-defensins (hBDs) provide antimicrobial and chemotactic defense against bacterial, viral and fungal infections. Human β-defensin-2 (hBD-2) acts against gram-negative bacteria and chemoattracts immature dendritic cells, thus regulating innate and adaptive immunity. Immunosuppression due to hyperglycemia underlies chronic infection in Type 2 diabetes. Hyperglycemia also elevates production of dicarbonyls methylgloxal (MGO) and glyoxal (GO).
  
  
  METHODS
  The effect of dicarbonyl on defensin peptide structure was tested by exposing recombinant hBD-2 (rhBD-2) to MGO or GO with subsequent analysis by MALDI-TOF MS and LC/MS/MS. Antimicrobial function of untreated rhBD-2 vs. rhBD-2 exposed to dicarbonyl against strains of both gram-negative and gram-positive bacteria in culture was determined by radial diffusion assay. The effect of dicarbonyl on rhBD-2 chemotactic function was determined by chemotaxis assay in CEM-SS cells.
  
  
  RESULTS
  MGO or GO in vitro irreversibly adducts to the rhBD-2 peptide, and significantly reduces antimicrobial and chemotactic functions. Adducts derive from two arginine residues, Arg22 and Arg23 near the C-terminus, and the N-terminal glycine (Gly1). We show by radial diffusion testing on gram-negative E. coli and P. aeruginosa, and gram-positive S. aureus, and a chemotaxis assay for CEM-SS cells, that antimicrobial activity and chemotactic function of rhBD-2 are significantly reduced by MGO.
  
  
  CONCLUSIONS
  Dicarbonyl modification of cationic antimicrobial peptides represents a potential link between hyperglycemia and the clinical manifestation of increased susceptibility to infection, protracted wound healing, and chronic inflammation in undiagnosed and uncontrolled Type 2 diabetes.
authors.affiliation: Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Janna G
authors.initials: JG
authors.lastname: Kiselar
authors.affiliation: Department of Periodontics, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: George R
authors.initials: GR
authors.lastname: Dubyak
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Caroline
authors.initials: C
authors.lastname: El Sanadi
authors.affiliation: Department of Biological Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Ghosh
authors.affiliation: Center for Proteomics and Bioinformatics, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Lundberg
authors.affiliation: Department of Biological Sciences, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Wesley M
authors.initials: WM
authors.lastname: Williams
mesh_terms: D056704:Adaptive Immunity; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000276:immunology; D001419:Bacteria / Q000276:immunology*; D001424:Bacterial Infections / Q000276:immunology*; D006037:Glyoxal / Q000031:analogs & derivatives* / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D008745:Methylation; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D023083:beta-Defensins / Q000737:chemistry* / Q000276:immunology*
chemical_list: D000900:Anti-Bacterial Agents; C106641:DEFB4A protein, human; D011994:Recombinant Proteins; D023083:beta-Defensins; D006037:Glyoxal