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West RJ, Burleson S, Gulledge T, Miller JW, Chappelle AH, Krieger S, Graham C, Snyder S, Simon G, Plehiers PM. Exploring structure/property relationships to health and environmental hazards of polymeric polyisocyanate prepolymer substances-2. Dermal sensitization potential in the mouse local lymph node assay. Toxicol Ind Health 2022; 38:556-577. [PMID: 35624531 DOI: 10.1177/07482337221089587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The sensitization potencies of twenty custom-designed monomer-depleted polymeric polyisocyanate prepolymer substances and their associated toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI) monomer precursors were investigated by means of the mouse Local Lymph Node Assay (LLNA). These polymeric prepolymers were designed to represent the structural features and physical-chemical properties exhibited by a broad range of commercial polymeric polyisocyanate prepolymers that are produced from the reaction of aromatic and aliphatic diisocyanate monomers with aliphatic polyether and polyester polyols. The normalization of LLNA responses to the applied (15-45-135 mM) concentrations showed that the skin sensitization potency of polymeric polyisocyanate prepolymers is at least 300 times less than that of the diisocyanate monomers from which they are derived. The sensitization potency of the prepolymers was shown to be mainly governed by their hydrophobicity (as expressed by the calculated octanol-water partition coefficient, log Kow) and surfactant properties. Neither hydrophilic (log Kow <0) nor very hydrophobic (log Kow >25) prepolymers stimulated lymphocyte proliferation beyond that of the dosing vehicle control. The findings of this investigation challenge the generally held assumption that all isocyanate (-N=C=O) bearing substances are potential skin (and respiratory) sensitizers. Further, these findings can guide the future development of isocyanate chemistries and associated polyurethane applications toward reduced exposure and health hazard potentials.
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Affiliation(s)
- Robert J West
- 550512International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
| | | | - Travis Gulledge
- Currently Burleson Research Technologies, StrideBio Inc, Durham, NC, USA
| | - Jason W Miller
- Environmental Analytics, Covestro LLC, Pittsburgh, PA, USA
| | - Anne H Chappelle
- 550512International Isocyanate Institute, Inc, Mountain Lakes, NJ, USA
| | - Shannon Krieger
- 5470Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI, USA
| | | | - Stephanie Snyder
- Environmental Analytics, Covestro LLC, Pittsburgh, PA, USA.,Product Safety and Regulatory Affairs, Covestro LLC, Pittsburgh, PA, USA
| | - Glenn Simon
- Simon Toxicology, LLC, Raleigh, NC, USA (Consultant to Vencorex US, Inc.)
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2
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Ndreu L, Sasse S, Karlberg AT, Karlsson I. Haptenation of Macrophage Migration Inhibitory Factor: A Potential Biomarker for Contact Hypersensitivity. FRONTIERS IN TOXICOLOGY 2022; 4:856614. [PMID: 35465102 PMCID: PMC9019732 DOI: 10.3389/ftox.2022.856614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/03/2022] [Indexed: 11/13/2022] Open
Abstract
The immunological response in contact hypersensitivity is incited by small electrophilic compounds, known as haptens, that react with endogenous proteins after skin absorption. However, the identity of hapten-modified proteins seen as immunogenic remains as yet largely unknown. In a recent study, we have for the first time identified a hapten-modified protein in the local lymph nodes of mice treated topically with the model hapten tetramethylrhodamine isothiocyanate (TRITC). The TRITC modification was located on the N-terminal proline of the protein macrophage migration inhibitory factor (MIF). The focus of the current study was to investigate the presence of the same hapten-protein conjugate in blood samples from mice treated topically with TRITC. Furthermore, TRITC modifications of the two major blood proteins, namely hemoglobin (Hb) and albumin (Alb), as well as TRITC modifications of MIF other than the N-terminal proline, were examined. Following incubation with different molar ratios of TRITC, a proteomic approach was applied to characterize conjugate formation of the three aforementioned proteins, using high resolution mass spectrometry (HRMS). The targeted screening of the TRITC-treated mice blood and lymph node samples for these sites led to the identification of only the same TRITC-MIF conjugate previously detected in the lymph nodes. No Hb and Alb conjugates were detected. Quantification of both the TRITC-modified and unmodified N-terminal peptide of MIF in blood and lymph node samples gave interesting insights of MIF’s role in murine contact hypersensitivity. Incubation of MIF with four different haptens encompassing different reactivity mechanisms and potencies, showed adduct formation at different amino acid residues, suggesting that MIF can be the preferred target for a wide variety of haptens. The present study provides essential progress toward understanding of hapten-protein conjugate formation in contact hypersensitivity and identifies hapten-modified MIF as a potential biomarker for this condition. Further investigation of MIF as a target protein can be a next step to determine if MIF is a biomarker that can be used to develop better diagnostic tools and targeted therapeutics for individuals with allergic contact dermatitis.
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Affiliation(s)
- Lorena Ndreu
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Samantha Sasse
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Ann-Therese Karlberg
- Department of Chemistry and Molecular Biology, Dermatochemistry, University of Gothenburg, Gothenburg, Sweden
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, Stockholm, Sweden
- *Correspondence: Isabella Karlsson,
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3
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Schupp T, Plehiers PM. Absorption, distribution, metabolism, and excretion of methylene diphenyl diisocyanate and toluene diisocyanate: Many similarities and few differences. Toxicol Ind Health 2022; 38:500-528. [PMID: 35301910 DOI: 10.1177/07482337211060133] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are high production volume chemicals used for the manufacture of polyurethanes. For both substances, the most relevant adverse health effects after overexposure in the workplace are isocyanate-induced asthma, lung function decrement and, to a much lesser extent, skin effects. Over the last two decades many articles have addressed the reactivity of MDI and TDI in biological media and the associated biochemistry, which increased the understanding of their biochemical and physiological behavior. In this review, these new insights with respect to similarities and differences concerning the adsorption, distribution, metabolism, and excretion (ADME) of these two diisocyanates and the implications on their toxicities are summarized. Both TDI and MDI show very similar behavior in reactivity to biological macromolecules, distribution, metabolism, and excretion. Evidence suggests that the isocyanate (NCO) group is scavenged at the portal-of-entry and is not systemically available in unbound reactive form. This explains the lack of other than portal-of-entry toxicity observed in repeated-dose inhalation tests.
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Affiliation(s)
- Thomas Schupp
- 39002Münster University of Applied Sciences, Steinfurt, Germany
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4
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Abstract
Chemicals are measured regularly in air, food, the environment, and the workplace. Biomonitoring of chemicals in biological fluids is a tool to determine the individual exposure. Blood protein adducts of xenobiotics are a marker of both exposure and the biologically effective dose. Urinary metabolites and blood metabolites are short term exposure markers. Stable hemoglobin adducts are exposure markers of up to 120 days. Blood protein adducts are formed with many xenobiotics at different sites of the blood proteins. Newer methods apply the techniques developed in the field of proteomics. Larger adducted peptides with 20 amino acids are used for quantitation. Unfortunately, at present the methods do not reach the limits of detection obtained with the methods looking at single amino acid adducts or at chemically cleaved adducts. Therefore, to progress in the field new approaches are needed.
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5
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Ndreu L, Erber LN, Törnqvist M, Tretyakova NY, Karlsson I. Characterizing Adduct Formation of Electrophilic Skin Allergens with Human Serum Albumin and Hemoglobin. Chem Res Toxicol 2020; 33:2623-2636. [PMID: 32875789 PMCID: PMC7582624 DOI: 10.1021/acs.chemrestox.0c00271] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
![]()
Skin
(contact) allergy, the most predominant form of immunotoxicity
in humans, is caused by small electrophilic compounds (haptens) that
modify endogenous proteins. Approximately 20% of the general population
in the Western world is affected by contact allergy. Although the
importance of the hapten–protein conjugates is well established
in the initiation of the immunological reaction, not much progress
has been made regarding identification of these conjugates in vivo or exploration of their potential as diagnostic
tools. In this study, the human serum albumin (HSA) and human hemoglobin
(Hb) adductome for three representative contact allergens with different
chemical properties, 1-chloro-2,4-dinitrobenzene (DNCB), 1,2-epoxy-3-phenoxypropane
(PGE), and 2-bromo-2-(bromomethyl)glutaronitrile (MDBGN), were studied.
Plasma and red blood cell lysate were used as a source for HSA and
Hb, respectively. The Direct Peptide Reactivity Assay was used to
investigate adduct formation of MDBGN with nucleophilic moieties and
revealed that MDGBN is converted to 2-methylenepentanedinitrile in
the presence of sulfhydryl groups prior to adduct formation. Following
incubation of HSA and Hb with haptens, an Orbitrap Q Exactive high-resolution
mass spectrometer was used to perform an initial untargeted analysis
to screen for adduct formation, followed by confirmation by targeted
Parallel Reaction Monitoring analysis. Although a subset of adducted
sites was confirmed by targeted analysis, only some of the adducted
peptides showed an increase in the relative amount of the adducted
peptide with an increased concentration of hapten. In total, seven
adduct sites for HSA and eight for Hb were confirmed for DNCB and
PGE. These sites are believed to be the most reactive. Further, three
of the HSA sites (Cys34, Cys62, and Lys190) and six of the Hb sites (subunit α: Val1, His45, His72; subunit β: Cys93, His97, and Cys112) were haptenated already
at the lowest level of hapten to protein molar ratio (0.1:1), indicating
that these sites are the most likely to be modified in vivo. To the best of our knowledge, this is the first time that the adductome
of Hb has been studied in the context of contact allergens. Identification
of the most reactive sites of abundant proteins, such as HSA and Hb,
is the first step toward identification of contact allergy biomarkers
that can be used for biomonitoring and to develop better diagnostic
tools based on a blood sample.
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Affiliation(s)
- Lorena Ndreu
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Luke N Erber
- Department of Medicinal Chemistry and the College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Margareta Törnqvist
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and the College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Isabella Karlsson
- Department of Environmental Science, Stockholm University, SE-106 91 Stockholm, Sweden
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Ishihara Y, Ikeda-Ishihara N, Koriyama C, Kakiuchi N, Tanaka M, Vogel CFA, Kawamoto T, Tsuji M. Determination of chemical-specific IgGs in serum by an enzyme-linked immunosorbent assay with partial peptides of human serum albumin. J Toxicol Sci 2018; 43:25-31. [PMID: 29415949 DOI: 10.2131/jts.43.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Many different types of chemicals are used in industry, and occupational allergies are becoming a serious problem in the field of industrial hygiene. In this study, we employed a novel enzyme-linked immunosorbent assay (ELISA) with partial peptides of human serum albumin (HSA) to quantify chemical-specific immunoglobulin G (IgG) in serum for evaluating exposure to chemicals. When HSA partial peptides containing lysine residues were mixed with formaldehyde (FA) or phthalic anhydride (PA), almost all lysine residues were lost. Mass spectrometry revealed that PA and FA formed imine and tertiary amine, respectively, with lysine residues in the peptides. Thus, we used FA- or PA-peptide adducts as an artificial antigen to detect FA- and PA-specific IgGs in serum. The concentrations of FA- and PA-specific IgGs in workers at plants utilizing plastic resins were significantly higher than those in general subjects. This method can estimate exposure levels to chemicals and thus be expected to contribute to the diagnosis of allergies in workers and to the prevention of health hazards due to harmful chemicals.
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Affiliation(s)
- Yasuhiro Ishihara
- Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University.,Center for Health and the Environment, University of California, USA
| | - Nami Ikeda-Ishihara
- Division of Gene Research, Natural Science Center for Basic Research and Development, Hiroshima University
| | - Chihaya Koriyama
- Department of Epidemiology and Preventive Medicine, Kagoshima University Graduate School of Medical and Dental Sciences
| | - Noriaki Kakiuchi
- Department of Work Systems and Health, Institute of Industrial Ecological Science, University of Occupational and Environmental Health
| | | | - Christoph F A Vogel
- Center for Health and the Environment, University of California, USA.,Department of Environmental Toxicology, University of California, USA
| | - Toshihiro Kawamoto
- Department of Environmental Health, University of Occupational and Environmental Health
| | - Mayumi Tsuji
- Department of Environmental Health, University of Occupational and Environmental Health
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7
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Wisnewski AV, Liu J, Redlich CA, Nassar AF. Polymerization of hexamethylene diisocyanate in solution and a 260.23 m/z [M+H] + ion in exposed human cells. Anal Biochem 2017; 543:21-29. [PMID: 29175138 DOI: 10.1016/j.ab.2017.11.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/16/2017] [Accepted: 11/20/2017] [Indexed: 10/18/2022]
Abstract
Hexamethylene diisocyanate (HDI) is an important industrial chemical that can cause asthma, however pathogenic mechanisms remain unclear. Upon entry into the respiratory tract, HDI's N=C=O groups may undergo nucleophilic addition (conjugate) to host molecules (e.g. proteins), or instead react with water (hydrolyze), releasing CO2 and leaving a primary amine in place of the original N=C=O. We hypothesized that (primary amine groups present on) hydrolyzed or partially hydrolyzed HDI may compete with proteins and water as a reaction target for HDI in solution, resulting in polymers that could be identified and characterized using LC-MS and LC-MS/MS. Analysis of the reaction products formed when HDI was mixed with a pH buffered, isotonic, protein containing solution identified multiple [M+H]+ ions with m/z's and collision-induced dissociation (CID) fragmentation patterns consistent with those expected for dimers (259.25/285.23 m/z), and trimers (401.36/427.35 m/z) of partially hydrolyzed HDI (e.g. ureas/oligoureas). Human peripheral blood mononuclear cells (PBMCs) and monocyte-like U937, but not airway epithelial NCI-H292 cell lines cultured with these HDI ureas contained a novel 260.23 m/z [M+H]+ ion. LC-MS/MS analysis of the 260.23 m/z [M+H]+ ion suggest the formula C13H29N3O2 and a structure containing partially hydrolyzed HDI, however definitive characterization will require further orthogonal analyses.
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Affiliation(s)
- Adam V Wisnewski
- Department of Internal Medicine, Yale University, New Haven, CT 06520, United States.
| | - Jian Liu
- Department of Internal Medicine, Yale University, New Haven, CT 06520, United States
| | - Carrie A Redlich
- Department of Internal Medicine, Yale University, New Haven, CT 06520, United States
| | - Ala F Nassar
- Department of Internal Medicine, Yale University, New Haven, CT 06520, United States
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8
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Sullivan KM, Enoch SJ, Ezendam J, Sewald K, Roggen EL, Cochrane S. An Adverse Outcome Pathway for Sensitization of the Respiratory Tract by Low-Molecular-Weight Chemicals: Building Evidence to Support the Utility ofIn VitroandIn SilicoMethods in a Regulatory Context. ACTA ACUST UNITED AC 2017. [DOI: 10.1089/aivt.2017.0010] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kristie M. Sullivan
- Physicians Committee for Responsible Medicine, Washington, District of Columbia
| | - Steven J. Enoch
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, England
| | - Janine Ezendam
- National Institute for Public Health and the Environment (RIVM), Centre for Health Protection, Bilthoven, The Netherlands
| | - Katherina Sewald
- Fraunhofer Institute for Toxicology and Experimental Medicine ITEM, Hannover, Germany
| | - Erwin L. Roggen
- 3Rs Management & Consulting ApS (3RsMC ApS), Lyngby, Denmark
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9
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Hettick JM, Law BF, Lin CC, Wisnewski AV, Siegel PD. Mass spectrometry-based analysis of murine bronchoalveolar lavage fluid following respiratory exposure to 4,4'-methylene diphenyl diisocyanate aerosol. Xenobiotica 2017. [PMID: 28629263 DOI: 10.1080/00498254.2017.1344791] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
1. Diisocyanates are highly reactive electrophiles utilized in the manufacture of a wide range of polyurethane products and have been identified as causative agents of occupational allergic respiratory disease. However, in spite of the significant occupational health burden associated with diisocyanate-induced asthma, the mechanism of disease pathogenesis remains largely unknown. 2. To better understand the fate of inhaled diisocyanates, a nose-only aerosol exposure system was constructed and utilized to expose a BALB/c mouse model to an aerosol generated from 4,4'-methylene diphenyl diisocyanate (MDI). Tissue and bronchoalveolar lavage samples were evaluated 4 and 24 h post-exposure for evidence of diisocyanate-protein haptenation, and a label-free quantitative proteomics strategy was employed to evaluate relative changes to the protein content of the cellular fraction of the lavage fluid. 3. Following MDI aerosol exposure, expression of the number of proteins with immunological or xenobiotic metabolism relevance is increased, including endoplasmin, cytochrome P450 and argininosuccinate synthase. Western blot analysis indicated MDI-conjugated protein in the lavage fluid, which was identified as serum albumin. 4. Tandem mass spectrometry analysis of MDI-albumin revealed MDI conjugation occurs at a dilysine motif at Lys525, as well as at a glutamine-lysine motif at Lys414, in good agreement with previously published in vitro data on diisocyanate-conjugated serum albumin.
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Affiliation(s)
- Justin M Hettick
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown , WV , USA and
| | - Brandon F Law
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown , WV , USA and
| | - Chen-Chung Lin
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown , WV , USA and
| | | | - Paul D Siegel
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown , WV , USA and
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10
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Hagerman LM, Law BF, Bledsoe TA, Hettick JM, Kashon ML, Lemons AR, Wisnewski AV, Siegel PD. The influence of diisocyanate antigen preparation methodology on monoclonal and serum antibody recognition. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2016; 13:829-839. [PMID: 27124286 PMCID: PMC5016257 DOI: 10.1080/15459624.2016.1183013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Exposure to diisocyanates (dNCOs), such as methylene diphenyl diisocyanate (MDI) can cause occupational asthma (OA). Currently, lab tests for dNCO specific IgE are specific, but not sensitive, which limits their utility in diagnosing dNCO asthma. This may be due to variable preparation and poor characterization of the standard antigens utilized in these assays. The aim of this study was to produce and characterize a panel of antigens prepared using three different commonly employed methods and one novel method. The conjugates were examined for recognition by anti-MDI monoclonal antibodies (mAbs) in varying enzyme linked immunosorbant assay (ELISA) formats, extent of crosslinking, total amount of MDI, the sites of MDI conjugation, relative shape/charge, and reactivity with human serum with antibodies from sensitized, exposed workers. Results indicate that while there are minimal differences in the total amount of MDI conjugated, the extent of crosslinking, and the conjugation sites, there are significant differences in the recognition of differently prepared conjugates by mAbs. Native and denaturing polyacrylamide gel electrophoresis demonstrate differences in the mobility of different conjugates, indicative of structural changes that are likely important for antigenicity. While mAbs exhibited differential binding to different conjugates, polyclonal serum antibodies from MDI exposed workers exhibited equivalent binding to different conjugates by ELISA. While differences in the recognition of the different conjugates exist by mAb detection, differences in antigenicity could not be detected using human serum from MDI-sensitized individuals. Thus, although dNCO conjugate preparation can, depending on the immunoassay platform, influence binding of specific antibody clones, serologic detection of the dNCO-exposure-induced polyclonal antibody response may be less sensitive to these differences.
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Affiliation(s)
- Lauren M Hagerman
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
| | - Brandon F Law
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
| | - Toni A Bledsoe
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
| | - Justin M Hettick
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
| | - Michael L Kashon
- b Biostatistics and Epidemiology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown , West Virginia
| | - Angela R Lemons
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
| | - Adam V Wisnewski
- c Department of Internal Medicine , Yale School of Medicine , New Haven , Connecticut
| | - Paul D Siegel
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown West Virginia
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11
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Mhike M, Hettick JM, Chipinda I, Law BF, Bledsoe TA, Lemons AR, Nayak AP, Green BJ, Beezhold DH, Simoyi RH, Siegel PD. Characterization and comparative analysis of 2,4-toluene diisocyanate and 1,6-hexamethylene diisocyanate haptenated human serum albumin and hemoglobin. J Immunol Methods 2016; 431:38-44. [PMID: 26853746 DOI: 10.1016/j.jim.2016.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 02/03/2016] [Accepted: 02/03/2016] [Indexed: 01/17/2023]
Abstract
Diisocyanates (dNCOs) are low molecular weight chemical sensitizers that react with autologous proteins to produce neoantigens. dNCO-haptenated proteins have been used as immunogens for generation of dNCO-specific antibodies and as antigens to screen for dNCO-specific antibodies in exposed individuals. Detection of dNCO-specific antibodies in exposed individuals for diagnosis of dNCO asthma has been hampered by poor sensitivities of the assay methods in that specific IgE can only be detected in approximately 25% of the dNCO asthmatics. Apart from characterization of the conjugates used for these immunoassays, the choice of the carrier protein and the dNCO used are important parameters that can influence the detection of dNCO-specific antibodies. Human serum albumin (HSA) is the most common carrier protein used for detection of dNCO specific-IgE and -IgG but the immunogenicity and/or antigenicity of other proteins that may be modified by dNCO in vivo is not well documented. In the current study, 2,4-toluene diisocyanate (TDI) and 1,6-hexamethylene diisocyanate (HDI) were reacted with HSA and human hemoglobin (Hb) and the resultant adducts were characterized by (i) HPLC quantification of the diamine produced from acid hydrolysis of the adducts, (ii) 2,4,6-trinitrobenzene sulfonic acid (TNBS) assay to assess extent of cross-linking, (iii) electrophoretic migration in polyacrylamide gels to analyze intra- and inter-molecular cross-linking, and (iv) evaluation of antigenicity using a monoclonal antibody developed previously to TDI conjugated to Keyhole limpet hemocyanin (KLH). Concentration-dependent increases in the amount of dNCO bound to HDI and TDI, cross-linking, migration in gels, and antibody-binding were observed. TDI reactivity with both HSA and Hb was significantly higher than HDI. Hb-TDI antigenicity was approximately 30% that of HSA-TDI. In conclusion, this data suggests that both, the extent of haptenation as well as the degree of cross-linking differs between the two diisocyanate species studied, which may influence their relative immunogenicity and/or antigenicity.
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Affiliation(s)
- Morgen Mhike
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA; Department of Chemistry, Portland State University, Portland, OR 97207, USA
| | - Justin M Hettick
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Itai Chipinda
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Brandon F Law
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Toni A Bledsoe
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Angela R Lemons
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Ajay P Nayak
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Brett J Green
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Donald H Beezhold
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | - Reuben H Simoyi
- Department of Chemistry, Portland State University, Portland, OR 97207, USA
| | - Paul D Siegel
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
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12
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Hulst AG, Verstappen DRW, van der Riet-Van Oeveren D, Vermeulen NPE, Noort D. Mass spectrometric identification of isocyanate-induced modifications of keratins in human skin. Chem Biol Interact 2015; 237:141-50. [PMID: 26070416 DOI: 10.1016/j.cbi.2015.06.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 05/13/2015] [Accepted: 06/03/2015] [Indexed: 11/24/2022]
Abstract
In the current paper we show that exposure of human callus to isocyanates leads to covalent modifications within keratin proteins. Mass spectrometric analyses of pronase digests of keratin isolated from exposed callus show that both mono- and di-adducts (for di-isocyanates) are predominantly formed on the ε-amino group of lysine. In addition, numerous modified tryptic keratin fragments were identified, demonstrating rather random lysine modification. Interestingly, preliminary experiments demonstrate that in case of MDI a similar lysine di-adduct was formed with lung elastin. Our data support the hypothesis that skin sensitization through antigenic modifications of skin proteins by isocyanates could play a role in occupational isocyanate-induced asthma. It is further envisaged that the elucidated adducts will also have great potential for use as biomarkers to assess skin exposure to isocyanates. Advantageously, the various lysine adducts display the presence of a characteristic daughter fragment at m/z 173.1 [lysine-NCO](+), enabling generic and rapid screening for exposure to isocyanates.
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Affiliation(s)
- Albert G Hulst
- TNO, Department of CBRN Protection, P.O. Box 45, 2280 AA Rijswijk, The Netherlands
| | - Daan R W Verstappen
- TNO, Department of CBRN Protection, P.O. Box 45, 2280 AA Rijswijk, The Netherlands; Section of Molecular Toxicology, AIMMS, VU University, Amsterdam, The Netherlands
| | | | - Nico P E Vermeulen
- Section of Molecular Toxicology, AIMMS, VU University, Amsterdam, The Netherlands
| | - Daan Noort
- TNO, Department of CBRN Protection, P.O. Box 45, 2280 AA Rijswijk, The Netherlands.
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13
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Vojdani A, Kharrazian D, Mukherjee PS. Elevated levels of antibodies against xenobiotics in a subgroup of healthy subjects. J Appl Toxicol 2014; 35:383-97. [PMID: 25042713 PMCID: PMC4365752 DOI: 10.1002/jat.3031] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/15/2014] [Accepted: 04/27/2014] [Indexed: 12/27/2022]
Abstract
In spite of numerous research efforts, the exact etiology of autoimmune diseases remains largely unknown. Genetics and environmental factors, including xenobiotics, are believed to be involved in the induction of autoimmune disease. Some environmental chemicals, acting as haptens, can bind to a high-molecular-weight carrier protein such as human serum albumin (HSA), causing the immune system to misidentify self-tissue as an invader and launch an immune response against it, leading to autoimmunity. This study aimed to examine the percentage of blood samples from healthy donors in which chemical agents mounted immune challenges and produced antibodies against HSA-bound chemicals. The levels of specific antibodies against 12 different chemicals bound to HSA were measured by ELISA in serum from 400 blood donors. We found that 10% (IgG) and 17% (IgM) of tested individuals showed significant antibody elevation against aflatoxin-HSA adduct. The percentage of elevation against the other 11 chemicals ranged from 8% to 22% (IgG) and 13% to 18% (IgM). Performance of serial dilution and inhibition of the chemical–antibody reaction by specific antigens but not by non-specific antigens were indicative of the specificity of these antibodies. Although we lack information about chemical exposure in the tested individuals, detection of antibodies against various protein adducts may indicate chronic exposure to these chemical haptens in about 20% of the tested individuals. Currently the pathological significance of these antibodies in human blood is still unclear, and this protein adduct formation could be one of the mechanisms by which environmental chemicals induce autoimmune reactivity in a significant percentage of the population.
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Affiliation(s)
- Aristo Vojdani
- Immunosciences Lab., Inc., 822 S. Robertson Blvd., Ste. 312, Los Angeles, CA, 90035, USA
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14
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Nayak AP, Hettick JM, Siegel PD, Anderson SE, Long CM, Green BJ, Beezhold DH. Toluene diisocyanate (TDI) disposition and co-localization of immune cells in hair follicles. Toxicol Sci 2014; 140:327-37. [PMID: 24798378 DOI: 10.1093/toxsci/kfu079] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Diisocyanates (dNCOs) are potent chemical allergens utilized in various industries. It has been proposed that skin exposure to dNCOs produces immune sensitization leading to work-related asthma and allergic disease. We examined dNCOs sensitization by using a dermal murine model of toluene diisocyanate (TDI) exposure to characterize the disposition of TDI in the skin, identify the predominant haptenated proteins, and discern the associated antigen uptake by dendritic cells. Ears of BALB/c mice were dosed once with TDI (0.1% or 4% v/v acetone). Ears and draining lymph nodes (DLNs) were excised at selected time points between 1 h and 15 days post-exposure and were processed for histological, immunohistochemical, and proteomic analyses. Monoclonal antibodies specific for TDI-haptenated protein (TDI-hp) and antibodies to various cell markers were utilized with confocal microscopy to determine co-localization patterns. Histopathological changes were observed following exposure in ear tissue of mice dosed with 4% TDI/acetone. Immunohistochemical staining demonstrated TDI-hp localization in the stratum corneum, hair follicles, and sebaceous glands. TDI-hp were co-localized with CD11b(+) (integrin αM/Mac-1), CD207(+) (langerin), and CD103(+) (integrin αE) cells in the hair follicles and in sebaceous glands. TDI-hp were also identified in the DLN 1 h post-exposure. Cytoskeletal and cuticular keratins along with mouse serum albumin were identified as major haptenated species in the skin. The results of this study demonstrate that the stratum corneum, hair follicles, and associated sebaceous glands in mice are dendritic cell accessible reservoirs for TDI-hp and thus identify a mechanism for immune recognition following epicutaneous exposure to TDI.
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Affiliation(s)
- Ajay P Nayak
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Justin M Hettick
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Paul D Siegel
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Stacey E Anderson
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Carrie M Long
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505 Department of Microbiology, Immunology and Cell Biology, School of Medicine, West Virginia University, Morgantown, West Virginia 26506
| | - Brett J Green
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
| | - Donald H Beezhold
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia 26505
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15
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Lemons AR, Siegel PD, Mhike M, Law BF, Hettick JM, Bledsoe TA, Nayak AP, Beezhold DH, Green BJ. A murine monoclonal antibody with broad specificity for occupationally relevant diisocyanates. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2014; 11:101-110. [PMID: 24369932 PMCID: PMC4624273 DOI: 10.1080/15459624.2013.843783] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Diisocyanates (dNCOs) used in industrial applications are well known low molecular weight allergens. Occupational exposure is associated with adverse health outcomes including allergic sensitization and occupational asthma. In this study, we report the production and initial characterization of a dNCO-hapten specific murine IgM monoclonal antibody (mAb). Female BALB/c mice were immunized intraperitoneally with 25 μg of 4,4'-methylene diphenyl diisocyanate (MDI)-keyhole limpet hemocyanin. Following six biweekly booster immunizations, splenocytes were recovered and fused to Sp2/0-Ag14 murine myeloma cell line for hybridoma production. Hybridomas were then screened in a solid-phase indirect enzyme-linked immunosorbent assay (ELISA) against 40:1 4,4'-MDI- human serum albumin (HSA). mAb reactivity to dNCO-HSA conjugates and dNCO-HSA spiked human serum were characterized using a sandwich ELISA. One hybridoma produced a multimeric IgM mAb (15D4) that reacted with 4,4'-MDI-HSA. Sandwich ELISA analysis demonstrated comparable reactivity with other occupationally relevant dNCO-HSA adducts, including 2,4-toluene diisocyanate (TDI)-HSA, 2,6-TDI-HSA, and 1,6-hexamethylene diisocyanate (HDI)-HSA, but not other electrophilic chemical HSA conjugates. The limit of quantification (LOQ) of 4,4'-MDI-HSA, 2,4-TDI-HSA, 2,6-TDI-HSA, and 1,6-HDI-HSA sandwich ELISAs were 567.2, 172.7, 184.2, and 403.5 ng/mL (8.67, 2.60, 2.77, and 6.07 pmol/mL), respectively. In contrast, experiments using dNCO-supplemented human sera showed an increase in the detectable limit of the assay. A mAb has been produced that has potential utility for detecting mixed diisocyanate exposures in occupational environments. The mAb may have additional utility in the standardization of specific IgE detection immunoassays as well as chromatographic-mass spectrometric methods to enrich dNCO adducted HSA in the plasma of occupationally exposed workers.
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Affiliation(s)
- Angela R Lemons
- a Allergy and Clinical Immunology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention , Morgantown , West Virginia
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16
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Mhike M, Chipinda I, Hettick JM, Simoyi RH, Lemons A, Green BJ, Siegel PD. Characterization of methylene diphenyl diisocyanate-haptenated human serum albumin and hemoglobin. Anal Biochem 2013; 440:197-204. [PMID: 23743149 DOI: 10.1016/j.ab.2013.05.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 05/14/2013] [Accepted: 05/17/2013] [Indexed: 11/30/2022]
Abstract
Protein haptenation by polyurethane industrial intermediate 4,4'-methylene diphenyl diisocyanate (MDI) is thought to be an important step in the development of diisocyanate (dNCO)-specific allergic sensitization; however, MDI-haptenated albumins used to screen specific antibody are often poorly characterized. Recently, the need to develop standardized immunoassays using a consistent, well-characterized dNCO-haptenated protein to screen for the presence of MDI-specific IgE and IgG from workers' sera has been emphasized and recognized. This has been challenging to achieve due to the bivalent electrophilic nature of dNCOs, leading to the capability to produce multiple cross-linked protein species and polymeric additions to proteins. In the current study, MDI was reacted with human serum albumin (HSA) and hemoglobin (Hb) at molar ratios ranging from 1:1 to 40:1 MDI/protein. Adducts were characterized by (i) loss of available 2,4,6-trinitrobenzene sulfonic acid (TNBS) binding to primary amines, (ii) electrophoretic migration in polyacrylamide gels, (iii) quantification of methylene diphenyl diamine following acid hydrolysis, and (iv) immunoassay. Concentration-dependent changes in all of the above noted parameters were observed, demonstrating increases in both number and complexity of conjugates formed with increasing MDI concentrations. In conclusion, a series of bioanalytical assays should be performed to standardize MDI-antigen preparations across lots and laboratories for measurement of specific antibody in exposed workers that in total indicate degree of intra- and intermolecular cross-linking, number of dNCOs bound, number of different specific binding sites on the protein, and degree of immunoreactivity.
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Affiliation(s)
- Morgen Mhike
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
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17
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Pham NT, Jewell WT, Morin D, Jones AD, Buckpitt AR. Characterization of model peptide adducts with reactive metabolites of naphthalene by mass spectrometry. PLoS One 2012; 7:e42053. [PMID: 22870282 PMCID: PMC3411726 DOI: 10.1371/journal.pone.0042053] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 07/02/2012] [Indexed: 01/29/2023] Open
Abstract
Naphthalene is a volatile polycyclic aromatic hydrocarbon generated during combustion and is a ubiquitous chemical in the environment. Short term exposures of rodents to air concentrations less than the current OSHA standard yielded necrotic lesions in the airways and nasal epithelium of the mouse, and in the nasal epithelium of the rat. The cytotoxic effects of naphthalene have been correlated with the formation of covalent protein adducts after the generation of reactive metabolites, but there is little information about the specific sites of adduction or on the amino acid targets of these metabolites. To better understand the chemical species produced when naphthalene metabolites react with proteins and peptides, we studied the formation and structure of the resulting adducts from the incubation of model peptides with naphthalene epoxide, naphthalene diol epoxide, 1,2-naphthoquinone, and 1,4-naphthoquinone using high resolution mass spectrometry. Identification of the binding sites, relative rates of depletion of the unadducted peptide, and selectivity of binding to amino acid residues were determined. Adduction occurred on the cysteine, lysine, and histidine residues, and on the N-terminus. Monoadduct formation occurred in 39 of the 48 reactions. In reactions with the naphthoquinones, diadducts were observed, and in one case, a triadduct was detected. The results from this model peptide study will assist in data interpretation from ongoing work to detect peptide adducts in vivo as markers of biologic effect.
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Affiliation(s)
- Nathalie T Pham
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, California, United States of America.
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18
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Analysis of naphthalene adduct binding sites in model proteins by tandem mass spectrometry. Chem Biol Interact 2012; 199:120-8. [PMID: 22659010 DOI: 10.1016/j.cbi.2012.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 05/16/2012] [Accepted: 05/23/2012] [Indexed: 12/15/2022]
Abstract
The electrophilic metabolites of the polyaromatic hydrocarbon naphthalene have been shown to bind covalently to proteins and covalent adduct formation correlates with the cytotoxic effects of the chemical in the respiratory system. Although 1,2-naphthalene epoxide, naphthalene diol epoxide, 1,2-naphthoquinone, and 1,4-napthoquinone have been identified as reactive metabolites of interest, the role of each metabolite in total covalent protein adduction and subsequent cytotoxicity remains to be established. To better understand the target residues associated with the reaction of these metabolites with proteins, mass spectrometry was used to identify adducted residues following (1) incubation of metabolites with actin and protein disulfide isomerase (PDI), and (2) activation of naphthalene in microsomal incubations containing supplemental actin or PDI. All four reactive metabolites bound to Cys, Lys or His residues in actin and PDI. Cys₁₇ of actin was the only residue adducted by all metabolites; there was substantial metabolite selectivity for the majority of adducted residues. Modifications of actin and PDI, following microsomal incubations containing ¹⁴C-naphthalene, were detected readily by 2D gel electrophoresis and phosphor imaging. However, target modifications on tryptic peptides from these isolated proteins could not be readily detected by MALDI/TOF/TOF and only three modified peptides were detected using high resolution-selective ion monitoring (HR-SIM). All the reactive metabolites investigated have the potential to modify several residues in a single protein, but even in tissues with very high rates of naphthalene activation, the extent of modification was too low to allow unambiguous identification of a significant number of modified residues in the isolated proteins.
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19
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Sabbioni G, Gu Q, Vanimireddy LR. Determination of isocyanate specific albumin-adducts in workers exposed to toluene diisocyanates. Biomarkers 2012; 17:150-9. [PMID: 22229538 DOI: 10.3109/1354750x.2011.645166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Toluene diisocyanates (2,4-TDI and 2,6-TDI) are important intermediates in the chemical industry. Among the main damages after low levels of TDI exposure are lung sensitization and asthma. It is therefore necessary to have sensitive and specific methods to monitor isocyanate exposure of workers. Urinary metabolites or protein adducts have been used as biomarkers in workers exposed to TDI. However, with these methods it was not possible to determine if the biomarkers result from exposure to TDI or to the corresponding toluene diamines (TDA). This work presents a new procedure for the determination of isocyanate-specific albumin adducts. Isotope dilution mass spectrometry was used to measure the adducts in albumin present in workers exposed to TDI. 2,4-TDI and 2,6-TDI formed adducts with lysine: N(ϵ)-[({3-amino-4-methylphenyl}amino)carbonyl]-lysine, N(ϵ)-[({5-amino-2-methylphenyl}amino)carbonyl]-lysine, and N(ϵ)- [({3-amino-2-methylphenyl}amino)carbonyl]-lysine. In future studies, this new method can be applied to measure TDI-exposures in workers.
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Affiliation(s)
- Gabriele Sabbioni
- Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA.
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20
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Hettick JM, Siegel PD, Green BJ, Liu J, Wisnewski AV. Vapor conjugation of toluene diisocyanate to specific lysines of human albumin. Anal Biochem 2011; 421:706-11. [PMID: 22206939 DOI: 10.1016/j.ab.2011.12.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/17/2011] [Accepted: 12/05/2011] [Indexed: 11/24/2022]
Abstract
Exposure to toluene diisocyanate (TDI), an industrially important crosslinking agent used in the production of polyurethane products, can cause asthma in sensitive workers. Albumin has been identified as a major reaction target for TDI in vivo, and TDI-albumin reaction products have been proposed to serve as exposure biomarkers and to act as asthmagens, yet they remain incompletely characterized. In the current study, we used a multiplexed tandem mass spectrometry (MS/MS) approach to identify the sites of albumin conjugation by TDI vapors, modeling the air/liquid interface of the lung. Vapor phase TDI was found to react with human albumin in a dose-dependent manner, with up to 18 potential sites of conjugation, the most susceptible being Lys351 and the dilysine site Lys413-414. Sites of vapor TDI conjugation to albumin were quantitatively limited compared with those recently described for liquid phase TDI, especially in domains IIA and IIIB of albumin. We hypothesize that the orientation of albumin at the air/liquid interface plays an important role in vapor TDI conjugation and, thus, could influence biological responses to exposure and the development of in vitro assays for exposure and immune sensitivity.
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Affiliation(s)
- Justin M Hettick
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, WV 26505, USA.
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21
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Wisnewski AV, Hettick JM, Siegel PD. Toluene diisocyanate reactivity with glutathione across a vapor/liquid interface and subsequent transcarbamoylation of human albumin. Chem Res Toxicol 2011; 24:1686-93. [PMID: 21806041 DOI: 10.1021/tx2002433] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glutathione has previously been identified as a reaction target for toluene diisocyanate (TDI) in vitro and in vivo, and has been suggested to contribute to toxic and allergic reactions to exposure. In this study, the reactivity of reduced glutathione (GSH) with TDI in vitro was further investigated using a mixed phase (vapor/liquid) exposure system to model the in vivo biophysics of exposure in the lower respiratory tract. HPLC/MS/MS was used to characterize the observed reaction products. Under the conditions tested, the major reaction products between TDI vapor and GSH were S-linked bis(GSH)-TDI and to a lesser extent mono(GSH)-TDI conjugates (with one N═C═O hydrolyzed). The vapor-phase-generated GSH-TDI conjugates were capable of transcarbamoylating human albumin in a pH-dependent manner, resulting in changes in the self-protein's conformation/charge, on the basis of electrophoretic mobility under native conditions. Specific sites of human albumin-TDI conjugation, mediated by GSH-TDI, were identified (Lys(73), Lys(159), Lys(190), Lys(199), Lys(212), Lys(351), Lys(136/137), Lys(413/414), and Lys(524/525)) along with overlap with those susceptible to direct conjugation by TDI. Together, the data extend the proof-of-principle for GSH to act as a "shuttle" for a reactive form of TDI, which could contribute to clinical responses to exposure.
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Affiliation(s)
- Adam V Wisnewski
- Department of Internal Medicine, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520-8057, USA.
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22
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Haptenation: chemical reactivity and protein binding. J Allergy (Cairo) 2011; 2011:839682. [PMID: 21785613 PMCID: PMC3138048 DOI: 10.1155/2011/839682] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 04/27/2011] [Indexed: 11/23/2022] Open
Abstract
Low molecular weight chemical (LMW) allergens are commonly referred to as haptens. Haptens must complex with proteins to be recognized by the immune system. The majority of occupationally related haptens are reactive, electrophilic chemicals, or are metabolized to reactive metabolites that form covalent bonds with nucleophilic centers on proteins. Nonelectrophilic protein binding may occur through disulfide exchange, coordinate covalent binding onto metal ions on metalloproteins or of metal allergens, themselves, to the major histocompatibility complex. Recent chemical reactivity kinetic studies suggest that the rate of protein binding is a major determinant of allergenic potency; however, electrophilic strength does not seem to predict the ability of a hapten to skew the response between Th1 and Th2. Modern proteomic mass spectrometry methods that allow detailed delineation of potential differences in protein binding sites may be valuable in predicting if a chemical will stimulate an immediate or delayed hypersensitivity. Chemical aspects related to both reactivity and protein-specific binding are discussed.
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