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Protein carbamylation links inflammation, smoking, uremia and atherogenesis

Nature Medicine volume 13, pages 11761184 (2007) | Download Citation

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Abstract

Post-translational modification and functional impairment of proteins through carbamylation is thought to promote vascular dysfunction during end-stage renal disease. Cyanate, a reactive species in equilibrium with urea, carbamylates protein lysine residues to form ε-carbamyllysine (homocitrulline), altering protein structure and function. We now report the discovery of an alternative and quantitatively dominant mechanism for cyanate formation and protein carbamylation at sites of inflammation and atherosclerotic plaque: myeloperoxidase-catalyzed oxidation of thiocyanate, an anion abundant in blood whose levels are elevated in smokers. We also show that myeloperoxidase-catalyzed lipoprotein carbamylation facilitates multiple pro-atherosclerotic activities, including conversion of low-density lipoprotein into a ligand for macrophage scavenger receptor A1 recognition, cholesterol accumulation and foam-cell formation. In two separate clinical studies (combined n = 1,000 subjects), plasma levels of protein-bound homocitrulline independently predicted increased risk of coronary artery disease, future myocardial infarction, stroke and death. We propose that protein carbamylation is a mechanism linking inflammation, smoking, uremia and coronary artery disease pathogenesis.

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Acknowledgements

Supported by US National Institutes of Health grants HL70621, P01 HL076491 and P01 HL077107 and by the Cleveland Clinic General Clinical Research Center (M01 RR018390).

Author information

Author notes

    • Eric J Topol

    Current address: The Scripps Research Institute, Scripps Genomic Medicine, and Scripps Health, La Jolla, California 92037, USA.

Affiliations

  1. Departments of Cell Biology, Cleveland Clinic, Cleveland, Ohio 44195, USA.

    • Zeneng Wang
    • , Stephen J Nicholls
    • , Joseph A DiDonato
    •  & Stanley L Hazen
  2. Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio 44195, USA.

    • Stephen J Nicholls
    • , Eric J Topol
    • , Joseph A DiDonato
    •  & Stanley L Hazen
  3. Pathology, Cleveland Clinic, Cleveland, Ohio 44195, USA.

    • E Rene Rodriguez
  4. Department of Internal Medicine and Biocenter Oulu, University of Oulu and Clinical Research Center, Oulu University Hospital, Finland.

    • Outi Kummu
    •  & Sohvi Hörkkö
  5. Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio 44195, USA.

    • John Barnard
  6. Sidney Kimmel Cancer Center, San Diego, California 92121, USA.

    • Wanda F Reynolds

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Contributions

Z.W. performed the biochemical, cellular, animal model and mass spectrometry studies, as well as assisting in drafting the manuscript. S.J.N. assisted with clinical studies design and statistical analysis. E.R.R. performed histology studies on human atherosclerotic plaque. O.K. and S.H. generated the monoclonal antibody to carbamylated LDL. J.B. assisted with clinical trial design and statistical analyses. W.F.R. collaborated in MPO transgenic mouse studies. E.J.T. participated in acquisition of clinical data and materials. J.A.D. participated in biochemical and cell biological characterization studies of carbamylated proteins. S.L.H. conceived the idea for the study, designed experiments, drafted manuscript and provided all funding. All authors provided critical review and comments on the manuscript.

Competing interests

S.L.H. is named as co-inventor on pending patents filed by the Cleveland Clinic that relate to the use of biomarkers to inflammatory and cardiovascular diseases. He is also the scientific founder and a consultant to PrognostiX Inc., and has received honoraria and consulting fees related to cardiovascular biomarkers from Abbott, BioSite, Lilly, Merck, Pfizer, Wyeth and Biophysical.

Corresponding author

Correspondence to Stanley L Hazen.

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    Supplementary Fig. 1, Supplementary Tables 1–4 and Supplementary Methods

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DOI

https://doi.org/10.1038/nm1637

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