Enrichment and Measurement of a Signature MDI Human Serum Albumin Peptide Adduct

Details

• Personal Author:
  Bartels MJ ; Green, Brett J. ; Luna LG ; Siegel, Paul D. ; Zhang F
• Description:
  Purpose: The purpose of this study was to develop and validate a signature peptide biomarker LC/MS/MS method to enable the monitoring of 4,4'-methylene diphenyl diisocyanate (4,4'-MDI) adducted to human serum albumin (HSA) in plasma collected from workers occupationally exposed to MDI. Relevance: 4,4'-MDI is used to produce polyurethane. Exposure to isocyanates like MDI may exacerbate airway disorders such as occupational asthma. Therefore it is essential to have a reliable and specific method for biomonitoring the occupational exposure of workers to MDI. Methods: A murine anti-4,4'-MDI monoclonal IgM antibody was bound to magnetic beads and utilized for enrichment of the MDI adducted HSA. Following enrichment, trypsin digestion was performed to generate the predictable MDI adducted HSA signature peptide biomarkers that were quantified by liquid chromatography tandem mass spectrometry (LC/MS/MS). Analysis: An Agilent 6530 LC/QTOF system was utilized for intact adducted protein analysis and an Agilent 6490 LC/MS/ MS system operated in multiple reaction monitoring (MRM) mode was utilized for quantification of the adducted peptide biomarker. Results: In vitro results showed that exposure of 1mM 4,4'-MDI to HSA produces major MDI adducts of both HSA isomers. LC/MS/MS quantitation of the 1 mM 4,4'-MDI adducted HSA trypsin digest was performed. The longer MDI adducted K(MDA) VPQVSTPTLVEVSR peptide was quantifiable and it's concentration was 276.63 ng/mL which accounted for 10.31% of the total MDI adducted albumin when 0.1 mg/mL of HSA was digested. No quantifiable amounts resulted for MDI adducted K(MDA) and YTK(MDA) amino acid or short peptide, respectively. These results demonstrated that the primary site of adduction appears to be K(MDA)VPQVSTPTLVEVSR. The MDI adducted HSA remained stable over 8 days when stored under both -80 degrees C and room temperature conditions. IgM magnetic bead capture of the adducted 4,4'-MDI HSA protein showed that enrichment is favorable to that without bead capture as evident by the ability to pull down and quantify adducted albumin with higher concentrations of plasma present. Conclusions: The MDI adducted HSA is stable at both -80 degrees C and room temperature over 8 days. Of the possible 413/414 HSA signature on the peptide adducts, the 414 lysine on K(MDA)VPQVSTPTLVEVSR appears to be the primary site of adduction. Sensitivity of the signature peptide method in matrix standards is comparable to Sabbioni's (2010) lysine amino acid methodology with the added benefit of more selectivity. Additional work is planned with human exposure samples. Implications: Biological monitoring is advantageous as sampling is less time-consuming and HSA protein adduct biomarkers have long half-lives and may be used to monitor long-term exposure. In addition HSA protein adducted biomarkers reflect the absorbed dose which integrates such factors as lung ventilation, alternative routes of exposure and acquired metabolic characteristics. Thus future work may correlate albumin related biomarker levels, rather than air levels, to potential sensitization, resulting from MDI occupational exposure. [Description provided by NIOSH]
• Subjects:
  Asthma, Occupational Biomarkers Hypersensitivity Isocyanates Occupational Health Safety
• Keywords:
  4,4'methylenebisphenyl Isocyanate Biological Effects Biological Monitoring Diisocyanates Exposure Assessment MDI Occupational Asthma Sensitization
• Publisher:
  Work Wellness and Disability Prevention Institute (WWDPI)
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Maryland ; Michigan ; OSHA Region 3 ; OSHA Region 5 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  67
• NIOSHTIC Number:
  nn:20054295
• Citation:
  Isocyanates & Health: Past, Present and Future, April 3-4, 2013, Potomac, Maryland. Vancouver, BC, Canada: Work Wellness and Disability Prevention Institute (WWDPI), 2013 Apr; :67
• Email:
  luna@dow.com
• CAS Registry Number:
  Diphenylmethane diisocyanate (CAS RN 101-68-8)
• Federal Fiscal Year:
  2013
• Peer Reviewed:
  False
• Source Full Name:
  Isocyanates & Health: Past, Present and Future, April 3-4, 2013, Potomac, Maryland
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:cd42ac8a3d8dc2c540fcd6f7439be444ddbdf4351ea91f517a8a3b3254f2c70464173f636ee2d93dc2c1c413d702fe57092c4b3bd42648129d25a049e4b09b2b
• Download URL:
  https://stacks.cdc.gov/view/cdc/216889/cdc_216889_DS1.pdf
• File Type:
  [PDF - 704.66 KB ]