Quantitative assessment of cyanide in cystic fibrosis sputum and its oxidative catabolism by hypochlorous acid

Jason P. Eiserich, Sean P. Ott, Tamara Kadir, Brian M Morrissey, Keri A. Hayakawa, Michele La Merrill, Carroll E Cross

Research output: Contribution to journalArticle

Abstract

Rationale: Cystic fibrosis (CF) patients are known to produce cyanide (CN-) although challenges exist in determinations of total levels, the precise bioactive levels, and specificity of its production by CF microflora, especially P. aeruginosa. Our objective was to measure total CN- levels in CF sputa by a simple and novel technique in P. aeruginosa positive and negative adult patients, to review respiratory tract (RT) mechanisms for the production and degradation of CN-, and to interrogate sputa for post-translational protein modification by CN- metabolites. Methods: Sputa CN- concentrations were determined by using a commercially available CN- electrode, measuring levels before and after addition of cobinamide, a compound with extremely high affinity for CN-. Detection of protein carbamoylation was measured by Western blot. Measurements and main results: The commercial CN- electrode was found to overestimate CN- levels in CF sputum in a highly variable manner; cobinamide addition rectified this analytical issue. Although P. aeruginosa positive patients tended to have higher total CN- values, no significant differences in CN- levels were found between positive and negative sputa. The inflammatory oxidant hypochlorous acid (HOCl) was shown to rapidly decompose CN-, forming cyanogen chloride (CNCl) and the carbamoylating species cyanate (NCO-). Carbamoylated proteins were found in CF sputa, analogous to reported findings in asthma. Conclusions: Our studies indicate that CN- is a transient species in the inflamed CF airway due to multiple biosynthetic and metabolic processes. Stable metabolites of CN-, such as cyanate, or carbamoylated proteins, may be suitable biomarkers of overall CN- production in CF airways.

Original languageEnglish (US)
Pages (from-to)146-154
Number of pages9
JournalFree Radical Biology and Medicine
Volume129
DOIs
StatePublished - Dec 1 2018

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Keywords

  • Carbamylated protein
  • Cyanate
  • Cyanide
  • Cyanogen chloride
  • Cystic fibrosis
  • Hypochlorous acid
  • Ion-specific electrode
  • Myeloperoxidase
  • Neutrophils
  • P. aeruginosa

ASJC Scopus subject areas

  • Biochemistry
  • Physiology (medical)

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