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: Janna G Kiselar, Xiaowei Wang, George R Dubyak, Caroline El Sanadi, Santosh K Ghosh, Kathleen Lundberg, Wesley M Williams
• Journal: PloS one (PLoS One) Vol. 10 Issue 8 Pg. e0130533 ( 2015) ISSN: 1932-6203 [Electronic] United States
• PMID: 26244639 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• DEFB4A protein, human
• Recombinant Proteins
• beta-Defensins
• Glyoxal

Topics

• Adaptive Immunity
• Anti-Bacterial Agents (chemistry, immunology)
• Bacteria (immunology)
• Bacterial Infections (immunology)
• Glyoxal (analogs & derivatives, immunology)
• Humans
• Immunity, Innate
• Methylation
• Recombinant Proteins (chemistry, immunology)
• Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
• beta-Defensins (chemistry, immunology)