| 1. |
- Carlsson, Henrik, 1987-, et al.
(författare)
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Strategy for identifying unknown hemoglobin adducts using adductome LC-MS/MS data : Identification of adducts corresponding to acrylic acid, glyoxal, methylglyoxal, and 1-octen-3-one
- 2016
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Ingår i: Food and Chemical Toxicology. - : Elsevier BV. - 0278-6915 .- 1873-6351. ; 92, s. 94-103
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Tidskriftsartikel (refereegranskat)abstract
- Electrophilic compounds have the ability to form adducts with nucleophilic sites in proteins and DNA in tissues, and thereby constitute risks for toxic effects. Adductomic approaches are developed for systematic screening of adducts to DNA and blood proteins, with the aim to detect unknown internal exposures to electrophiles. In a previous adductomic screening of adducts to N-terminals in hemoglobin, using LC-MS/MS, 19 unknown adducts were detected in addition to seven previously identified adducts. The present paper describes the identification of four of these unknown adducts, as well as the strategy used to identify them. Using LC-MS data from the screening, hypotheses about adduct identities were formulated: probable precursor electrophiles with matching molecular weights were suggested based on the molecular weights of the modifications and the retention times of the analytes, in combination with comparisons of theoretical Log P calculations and databases. Reference adducts were generated by incubation of blood samples with the hypothesized precursor electrophiles. The four identified precursor electrophiles, corresponding to the observed unknown adducts, were glyoxal, methylglyoxal, acrylic acid and 1-octen-3-one. Possible origins/exposure sources and toxicological information concerning the electrophilic precursors are discussed. The identified adducts could be explored as possible biomarkers for exposure.
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| 2. |
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| 3. |
- Ndreu, Lorena, 1990-
(författare)
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Mass Spectrometry Strategies for Characterization of Contact Allergens and their Protein Conjugates in Vitro and in Vivo
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Humans are daily exposed to chemicals from various sources, including cosmetics, jewelry, clothes, and hair dyes, which can result in the occurrence of contact allergy and subsequent allergic contact dermatitis (ACD), a type IV delayed hypersensitivity reaction. ACD is characterized by inflammation and eczema at the site of exposure, and no definitive cure for this condition has been identified to date, with only symptomatic treatment options involving corticosteroids being available.The research presented in this thesis is centered around mass spectrometry (MS) strategies aimed at enhancing our comprehension of events that occur during the early stages of the development of contact allergy. Special emphasis is given to characterizing various contact allergens (haptens) and their interactions with endogenous proteins, as these interactions are considered crucial in the initiation of contact allergy. Moreover, the thesis endeavors to explore the activation of prehaptens and prohaptens, which are non-reactive compounds capable of transforming into haptens outside or inside the skin, respectively.In Paper I, a bottom-up proteomics approach was employed to investigate the adductome of two major blood proteins, human serum albumin (HSA) and hemoglobin (Hb). The study aimed to identify the most reactive sites on these proteins upon exposure to different haptens with varying sensitization potencies. Highly susceptible sites on HSA and Hb were identified as the most likely targets for in vivo modification. This study is the first investigation of the Hb adductome in the context of contact allergy and may contribute to the development of improved diagnostic tools using blood samples. With Hb on focus, Paper II evaluated three different MS-based methods, including bottom-up proteomics, detachment of N-terminal adducts by FIRE, and limited proteolysis (LiP), to determine the most suitable approach for assessing exposure through this protein. The three methods showed different strengths and limitations depending on the nature of the hapten. In Paper III, the research conducted revealed the presence of a hapten-protein conjugate in blood samples mice treated with the synthetic hapten tetramethyl rhodamine isothiocyanate (TRITC) topically. The identified protein was the macrophage migration inhibitory factor (MIF), marking the first instance of such a conjugate being detected in blood samples after topical hapten application. The study also indicated that MIF could potentially be modified by other contact allergens, suggesting its potential as a biomarker for the condition. In Paper IV, contact allergy to propolis, a by-product of honey used in biocosmetics, was investigated. Air oxidation experiments with a model peptide and MS detection, revealed that quinones formed from the oxidation of major propolis components are responsible for adduct formation. The identified adducts are likely the cause of contact allergy to propolis, providing valuable insights into the underlying mechanisms of propolis contact allergy and potential implications for clinical diagnosis. In Paper V, the bioactivation of cinnamic alcohol, a common ingredient in many cosmetic products, was investigated using in vitro systems and a targeted MS approach. Two metabolites, namely pOH-cinnamic alcohol and pOH-cinnamic aldehyde, were identified as of particular interest and their sensitizing potency was evaluated, with the latter categorized as a moderate sensitizer.In summary, this doctoral thesis employed MS techniques to characterize contact allergens and their protein conjugates, yielding valuable insights into the molecular mechanisms underlying contact allergy development. The findings have potential implications for improving diagnostic tools and strategies for preventing and treating contact allergy.
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| 4. |
- Pedersen, Marie, et al.
(författare)
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Hemoglobin adducts of acrylamide in human blood-What has been done and what is next?
- 2022
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Ingår i: Food and Chemical Toxicology. - 0278-6915 .- 1873-6351. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- Acrylamide forms in many commonly consumed foods. In animals, acrylamide causes tumors, neurotoxicity, developmental and reproductive effects. Acrylamide crosses the placenta and has been associated with restriction of intrauterine growth and certain cancers. The impact on human health is poorly understood and it is impossible to say what level of dietary exposure to acrylamide can be deemed safe as the assessment of exposure is un-certain. The determination of hemoglobin (Hb) adducts from acrylamide is increasingly being used to improve the exposure assessment of acrylamide. We aim to outline the literature on Hb adduct levels from acrylamide in humans and discuss methodological issues and research gaps. A total of 86 studies of 27,966 individuals from 19 countries were reviewed. Adduct levels were highest in occupationally exposed individuals and smokers. Levels ranged widely from 3 to 210 pmol/g Hb in non-smokers from the general population and this wide range sug-gests that dietary exposure to acrylamide varies largely. Non-smokers from the US and Canada had slightly higher levels as compared with non-smokers from elsewhere, but differences within studies were larger than between studies. Large studies with exposure assessment of acrylamide and related adduct forming compounds from diet during early-life are encouraged for the evaluation of health effects.
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| 5. |
- Rajczewski, Andrew T., et al.
(författare)
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Mass Spectrometry-Based Strategies for Assessing Human Exposure Using Hemoglobin Adductomics
- 2023
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Ingår i: Chemical Research in Toxicology. - 0893-228X .- 1520-5010. ; 36:12, s. 2019-2030
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Tidskriftsartikel (refereegranskat)abstract
- Hemoglobin (Hb) adducts are widely used in human biomonitoring due to the high abundance of hemoglobin in human blood, its reactivity toward electrophiles, and adducted protein stability for up to 120 days. In the present paper, we compared three methods of analysis of hemoglobin adducts: mass spectrometry of derivatized N-terminal Val adducts, mass spectrometry of N-terminal adducted hemoglobin peptides, and limited proteolysis mass spectrometry . Blood from human donors was incubated with a selection of contact allergens and other electrophiles, after which hemoglobin was isolated and subjected to three analysis methods. We found that the FIRE method was able to detect and reliably quantify N-terminal adducts of acrylamide, acrylic acid, glycidic acid, and 2,3-epoxypropyl phenyl ether (PGE), but it was less efficient for 2-methyleneglutaronitrile (2-MGN) and failed to detect 1-chloro-2,4-dinitrobenzene (DNCB). By contrast, bottom-up proteomics was able to determine the presence of adducts from all six electrophiles at both the N-terminus and reactive hemoglobin side chains. Limited proteolysis mass spectrometry, studied for four contact allergens (three electrophiles and a metal salt), was able to determine the presence of covalent hemoglobin adducts with one of the three electrophiles (DNCB) and coordination complexation with the nickel salt. Together, these approaches represent complementary tools in the study of the hemoglobin adductome.
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| 6. |
- Vryonidis, Efstathios, 1989-, et al.
(författare)
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Dietary intake of acrylamide in the Norwegian EuroMix biomonitoring study : Comparing probabilistic dietary estimates with haemoglobin adduct measurements
- 2023
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Ingår i: Food and Chemical Toxicology. - 0278-6915 .- 1873-6351. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- Acrylamide is a probable human carcinogen with widespread exposure via food. The present study compared acrylamide intake measurements obtained from haemoglobin adduct levels and self-registered dietary consumption data in a group of 144 Norwegian healthy adults. Acrylamide adducts to N-terminal valine in haemoglobin were measured and used to estimate the intake via the internal dose approach which showed a median (interquartile range) of 0.24 (0.19–0.30) μg/kg bw/day. Data from weighed food records and food frequency questionnaires from the same individuals were used for probabilistic modelling of the intake of acrylamide. The median acrylamide intake was calculated to be 0.26 (0.16–0.39) and 0.30 (0.23–0.39) μg/kg bw/day, respectively from the two sources of self-registered dietary consumption data. Overall, a relatively good agreement was observed between the methods in pairwise comparison in Bland-Altman plots, with the methods disagreeing with 7% or less of the values. The intake estimates obtained with the two dietary consumption methods and one biomarker method are in line with earlier dietary estimates in the Norwegian population. The Margin of Exposure indicate a possible health risk concern from dietary acrylamide. This is the first study with a comparison in the same individuals of acrylamide intake estimates obtained with these methods.
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| 7. |
- Vryonidis, Efstathios, 1989-, et al.
(författare)
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Pathways to Identify Electrophiles In Vivo Using Hemoglobin Adducts : Hydroxypropanoic Acid Valine Adduct and Its Possible Precursors
- 2022
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Ingår i: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 35:12, s. 2227-2240
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Tidskriftsartikel (refereegranskat)abstract
- Analytical methods and tools for the characterization of the human exposome by untargeted mass spectrometry approaches are advancing rapidly. Adductomics methods have been developed for untargeted screening of short-lived electrophiles, in the form of adducts to proteins or DNA, in vivo. The identification of an adduct and its precursor electrophile in the blood is more complex than that of stable chemicals. The present work aims to illustrate procedures for the identification of an adduct to N-terminal valine in hemoglobin detected with adductomics, and pathways for the tracing of its precursor and possible exposure sources. Identification of the adduct proceeded via preparation and characterization of standards of adduct analytes. Possible precursor(s) and exposure sources were investigated by measurements in blood of adduct formation by precursors in vitro and adduct levels in vivo. The adduct was identified as hydroxypropanoic acid valine (HPA-Val) by verification with a synthesized reference. The HPA-Val was measured together with other adducts (from acrylamide, glycidamide, glycidol, and acrylic acid) in human blood (n = 51, schoolchildren). The HPA-Val levels ranged between 6 and 76 pmol/g hemoglobin. The analysis of reference samples from humans and rodents showed that the HPA-Val adduct was observed in all studied samples. No correlation of the HPA-Val level with the other studied adducts was observed in humans, nor was an increase in tobacco smokers observed. A small increase was observed in rodents exposed to glycidol. The formation of the HPA-Val adduct upon incubation of blood with glycidic acid (an epoxide) was shown. The relatively high adduct levels observed in vivo in relation to the measured reactivity of the epoxide, and the fact that the epoxide is not described as naturally occurring, suggest that glycidic acid is not the only precursor of the HPA-Val adduct identified in vivo. Another endogenous electrophile is suspected to contribute to the in vivo HPA-Val adduct level.
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