1
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Kemp J, Ladwig PM, Snyder MR. Alpha-1-Antitrypsin (A1AT) Proteotyping by LC-MS/MS. Methods Mol Biol 2024; 2750:95-106. [PMID: 38108970 DOI: 10.1007/978-1-0716-3605-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The diagnosis of alpha-1-antitrypsin (A1AT) deficiency is established by quantitation of protein concentration in serum (immunoassay) followed by determination of specific allelic variants by phenotyping (isoelectric focusing (IEF) gel electrophoresis) and/or allele-specific genotyping. Various phenotyping and genotyping methodologies are available, and each has their own advantages and disadvantages. As an alternative, mass spectrometry is emerging as a powerful tool in the identification and quantitation of proteins and peptides. The method described here, referred to as proteotyping, is a proteomic method using trypsin digestion and tandem mass spectrometry that detects the most common deficiency alleles, S and Z, associated with A1AT deficiency.This qualitative mass spectrometry method is based on the principle that the S and Z mutations lead to amino acid changes which result in a change in the mass of the A1AT protein. When the A1AT protein is proteolytically digested, multiple peptides are generated, two of which include the sites of the S and Z mutations, respectively. Peptides generated from wild-type A1AT (M alleles) differ in sequence and mass from peptides generated from the S and Z alleles at these two specific locations. The mass difference allows for differentiation of S and Z peptides, representing the deficiency alleles, from non-S and non-Z peptides, representing the wild-type alleles (M). Interpretation of the peptide patterns in conjunction with A1AT quantitation by immunoassay allows for an accurate assessment for the presence of deficiency alleles in the majority of patients.
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Affiliation(s)
- Jennifer Kemp
- Division of Clinical Biochemistry and Immunology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Paula M Ladwig
- Division of Clinical Biochemistry and Immunology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Melissa R Snyder
- Division of Clinical Biochemistry and Immunology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA.
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2
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Liu X, Kouassi KGW, Vanbever R, Dumoulin M. Impact of the PEG length and PEGylation site on the structural, thermodynamic, thermal, and proteolytic stability of mono-PEGylated alpha-1 antitrypsin. Protein Sci 2022; 31:e4392. [PMID: 36040264 PMCID: PMC9375436 DOI: 10.1002/pro.4392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 11/11/2022]
Abstract
Conjugation to polyethylene glycol (PEG) is a widely used approach to improve the therapeutic value of proteins essentially by prolonging their body residence time. PEGylation may however induce changes in the structure and/or the stability of proteins and thus on their function(s). The effects of PEGylation on the thermodynamic stability can either be positive (stabilization), negative (destabilization), or neutral (no effect). Moreover, various factors such as the PEG length and PEGylation site can influence the consequences of PEGylation on the structure and stability of proteins. In this study, the effects of PEGylation on the structure, stability, and polymerization of alpha1-antitrypsin (AAT) were investigated, using PEGs with different lengths, different structures (linear or 2-armed) and different linking chemistries (via amine or thiol) at two distinct positions of the sequence. The results show that whatever the size, position, and structure of PEG chains, PEGylation (a) does not induce significant changes in AAT structure (either at the secondary or tertiary level); (b) does not alter the stability of the native protein upon both chemical- and heat-induced denaturation; and (c) does not prevent AAT to fully refold and recover its activity following chemical denaturation. However, the propensity of AAT to aggregate upon heat treatment was significantly decreased by PEGylation, although PEGylation did not prevent the irreversible inactivation of the enzyme. Moreover, conjugation to PEG, especially 2-armed 40 kDa PEG, greatly improved the proteolytic resistance of AAT. PEGylation of AAT could be a promising strategy to prolong its half-life after infusion in AAT-deficient patients and thereby decrease the frequency of infusions.
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Affiliation(s)
- Xiao Liu
- Advanced Drug Delivery and BiomaterialsLouvain Drug Research Institute, Université catholique de Louvain (UCLouvain)BrusselsBelgium
| | - Kobenan G. W. Kouassi
- Advanced Drug Delivery and BiomaterialsLouvain Drug Research Institute, Université catholique de Louvain (UCLouvain)BrusselsBelgium
| | - Rita Vanbever
- Advanced Drug Delivery and BiomaterialsLouvain Drug Research Institute, Université catholique de Louvain (UCLouvain)BrusselsBelgium
| | - Mireille Dumoulin
- Department of Life SciencesInBios, Center for Protein Engineering, Nanobodies to Explore Protein Structure and Functions, University of LiègeLiègeBelgium
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3
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Liu X, Vanvarenberg K, Kouassi KGW, Mahri S, Vanbever R. Production and characterization of mono-PEGylated alpha-1 antitrypsin for augmentation therapy. Int J Pharm 2022; 612:121355. [PMID: 34883205 DOI: 10.1016/j.ijpharm.2021.121355] [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] [Received: 09/07/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 12/16/2022]
Abstract
Alpha-1 antitrypsin (AAT) is an endogenous inhibitor of serine proteases which, in physiological conditions, neutralizes the excess of neutrophil elastase and other serine proteases in tissues and especially the lungs. Weekly intravenous infusion of plasma-purified human AAT is used to treat AAT deficiency-associated lung disease. However, only 2 % of the AAT dose reach the lungs after intravenous infusion. Inhalation of AAT might offer an alternative route of administration. Yet, the rapid clearance of AAT from the respiratory tract results in high and frequent dosing by inhalation and limited efficacy. In the present study, we produced and characterized in vitro a PEGylated version of AAT which could offer a prolonged body residence time and thereby be useful for augmentation therapy by the intravenous and inhalation routes. Two PEGylation reactions - N-terminal and thiol PEGylation - and three polyethylene glycol (PEG) chains - linear 30 kDa, linear 40 kDa and 2-armed 40 kDa - were used. The yields of mono-PEGylated AAT following purification by anion exchange chromatography were 40-50 % for N-terminal PEGylation and 60-70% for thiol PEGylation. The PEG-AAT conjugates preserved the ability to form a protease-inhibitor complex with neutrophil elastase and proteinase 3 as well as the full inhibitory capacity to neutralize neutrophil elastase activity. These results open up interesting prospects for PEGylated AAT to achieve a prolonged half-life and an improved therapeutic efficacy in vivo.
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Affiliation(s)
- Xiao Liu
- Université catholique de Louvain (UCLouvain), Louvain Drug Research Institute, Advanced Drug Delivery & Biomaterials, Brussels, Belgium
| | - Kevin Vanvarenberg
- Université catholique de Louvain (UCLouvain), Louvain Drug Research Institute, Advanced Drug Delivery & Biomaterials, Brussels, Belgium
| | - Kobenan Guy Wilfried Kouassi
- Université catholique de Louvain (UCLouvain), Louvain Drug Research Institute, Advanced Drug Delivery & Biomaterials, Brussels, Belgium
| | - Sohaib Mahri
- Université catholique de Louvain (UCLouvain), Louvain Drug Research Institute, Advanced Drug Delivery & Biomaterials, Brussels, Belgium
| | - Rita Vanbever
- Université catholique de Louvain (UCLouvain), Louvain Drug Research Institute, Advanced Drug Delivery & Biomaterials, Brussels, Belgium.
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4
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Forgrave LM, Wang M, Yang D, DeMarco ML. Proteoforms and their expanding role in laboratory medicine. Pract Lab Med 2022; 28:e00260. [PMID: 34950758 PMCID: PMC8672040 DOI: 10.1016/j.plabm.2021.e00260] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 10/31/2021] [Accepted: 11/22/2021] [Indexed: 12/17/2022] Open
Abstract
The term “proteoforms” describes the range of different structures of a protein product of a single gene, including variations in amino acid sequence and post-translational modifications. This diversity in protein structure contributes to the biological complexity observed in living organisms. As the concentration of a particular proteoform may increase or decrease in abnormal physiological states, proteoforms have long been used in medicine as biomarkers of health and disease. Notably, the analytical approaches used to analyze proteoforms have evolved considerably over the years. While ligand binding methods continue to play a large role in proteoform measurement in the clinical laboratory, unanticipated or unknown post-translational modifications and sequence variants can upend even extensively tested and vetted assays that have successfully made it through the medical regulatory process. As an alternate approach, mass spectrometry—with its high molecular selectivity—has become an essential tool in detection, characterization, and quantification of proteoforms in biological fluids and tissues. This review explores the analytical techniques used for proteoform detection and quantification, with an emphasis on mass spectrometry and its various applications in clinical research and patient care including, revealing new biomarker targets, helping improve the design of contemporary ligand binding in vitro diagnostics, and as mass spectrometric laboratory developed tests used in routine patient care.
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Affiliation(s)
- Lauren M. Forgrave
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - Meng Wang
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - David Yang
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
| | - Mari L. DeMarco
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
- Department of Pathology and Laboratory Medicine, St. Paul's Hospital, Providence Health Care, 1081 Burrard St, Vancouver, V6Z 1Y6, Canada
- Corresponding author. Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.
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5
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Murray JD, Willrich MA, Krowka MJ, Bobr A, Murray DL, Halling KC, Graham RP, Snyder MR. Liquid Chromatography-Tandem Mass Spectrometry-Based α1-Antitrypsin (AAT) Testing. Am J Clin Pathol 2021; 155:547-552. [PMID: 33083828 DOI: 10.1093/ajcp/aqaa149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Failure to produce sufficient quantities of functional α1-antitrypsin (AAT) can result in AAT deficiency (AATD) and significant comorbidities. Laboratory testing plays a vital role in AATD, with diagnosis requiring documentation of both a low AAT level and a mutated allele. This retrospective evaluation examines the efficacy of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) (proteotyping)-based algorithm for AATD detection. METHODS A 16-month retrospective data analysis was performed on two cohorts: 5,474 samples tested with the proteotype-based algorithm and 16,147 samples directly tested by isoelectric focusing (IEF) phenotyping. RESULTS LC-MS/MS reduced the rate of IEF testing by 97%. The 3% of cases reflexed to IEF resulted in 12 (0.2%) additional phenotype findings. Retrospectively applying the proteotype-based algorithm to the IEF cohort demonstrated a 99.9% sensitivity for the detection of deficiency-associated phenotypes. Most deficiency phenotypes missed by the proteotyping algorithm would come from heterozygous patients with an F, I, or P paired to an S or Z. In all of these cases, patient AAT levels were greater than 70 mg/dL, above the threshold for AAT augmentation therapy. CONCLUSIONS The proteotype algorithm is a sensitive and cost-effective approach for the diagnosis of clinical AAT deficiency.
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Affiliation(s)
| | | | - Michael J Krowka
- Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN
| | - Aleh Bobr
- Blood Bank and Tissue Services, University of Nebraska Medical Center, Omaha
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6
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Norris Bradley M, Shuford CM, Holland PL, Levandoski M, Grant RP. Quality over quantity: A qualitative, targeted bottom-up proteomics approach to genotyping apolipoprotein L1. Clin Biochem 2020; 82:58-65. [DOI: 10.1016/j.clinbiochem.2020.03.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/04/2020] [Accepted: 03/26/2020] [Indexed: 12/18/2022]
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7
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Holmes DT, Romney MG, Angel P, DeMarco ML. Proteomic applications in pathology and laboratory medicine: Present state and future prospects. Clin Biochem 2020; 82:12-20. [PMID: 32442429 DOI: 10.1016/j.clinbiochem.2020.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/13/2020] [Accepted: 05/13/2020] [Indexed: 12/11/2022]
Abstract
Clinical mass spectrometry applications have traditionally focused on small molecules, particularly in the areas of therapeutic drug monitoring, toxicology, and measurement of endogenous and exogenous steroids. More recently, the use of matrix assisted laser desorption/ionization time of flight mass spectrometry for the identification of microbial pathogens has been widely implemented. Following this evolution, there has been an expanding role for the measurement of peptides and proteins in pathology and laboratory medicine. This review explores the current state of protein measurement by clinical mass spectrometry and the analytical strategies employed, as well as emerging applications in clinical chemistry, clinical microbiology and anatomical pathology.
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Affiliation(s)
- Daniel T Holmes
- Department of Pathology and Laboratory Medicine, St. Paul's Hospital, 1081 Burrard St, Vancouver, BC V6Z 1Y6, Canada; University of British Columbia Department of Pathology and Laboratory Medicine, Vancouver, BC V6T 2B5 Canada.
| | - Marc G Romney
- Department of Pathology and Laboratory Medicine, St. Paul's Hospital, 1081 Burrard St, Vancouver, BC V6Z 1Y6, Canada; University of British Columbia Department of Pathology and Laboratory Medicine, Vancouver, BC V6T 2B5 Canada.
| | - Peggi Angel
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charelston, SC 29425 Canada.
| | - Mari L DeMarco
- Department of Pathology and Laboratory Medicine, St. Paul's Hospital, 1081 Burrard St, Vancouver, BC V6Z 1Y6, Canada; University of British Columbia Department of Pathology and Laboratory Medicine, Vancouver, BC V6T 2B5 Canada.
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8
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Coelho Graça D, Lescuyer P. Ultrahigh Performance Mass Spectrometry in Clinical Chemistry: A Taste of the Future? Clin Chem 2019; 65:943-945. [DOI: 10.1373/clinchem.2019.305631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/20/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Didia Coelho Graça
- Division of Laboratory Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Pierre Lescuyer
- Division of Laboratory Medicine, Geneva University Hospitals, Geneva, Switzerland
- Department of Medicine, Faculty of Medicine, Geneva University, Geneva, Switzerland
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9
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Franciosi AN, Carroll TP, McElvaney NG. Pitfalls and caveats in α1-antitrypsin deficiency testing: a guide for clinicians. THE LANCET RESPIRATORY MEDICINE 2019; 7:1059-1067. [PMID: 31324540 DOI: 10.1016/s2213-2600(19)30141-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 01/04/2023]
Abstract
α1-antitrypsin deficiency (AATD) remains the only readily identified genetic cause of chronic obstructive pulmonary disease (COPD). Furthermore, there is growing evidence that even a moderate deficiency increases the risk of lung disease among smokers. Despite these facts, the uptake of testing for AATD in at-risk populations remains low for many reasons, and a lack of clarity among clinicians regarding the most appropriate diagnostic techniques presents a major deterrent. This Personal View addresses the benefits of diagnosis, the technical basis of the available diagnostic methods, and possible clinical confounders for each test. We include a series of unusual cases encountered at our National Centre of Expertise to provide context. The topics covered should equip clinicians with the core knowledge required to confidently assess patients for AATD.
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Affiliation(s)
- Alessandro N Franciosi
- Irish Centre for Genetic Lung Disease, Royal College of Surgeons in Ireland, Dublin, Ireland; Department of Medicine, Beaumont Hospital, Dublin, Ireland.
| | - Tomás P Carroll
- Irish Centre for Genetic Lung Disease, Royal College of Surgeons in Ireland, Dublin, Ireland; Alpha-1 Foundation Ireland, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Noel G McElvaney
- Irish Centre for Genetic Lung Disease, Royal College of Surgeons in Ireland, Dublin, Ireland; Department of Medicine, Beaumont Hospital, Dublin, Ireland
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10
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Pac LJ, Cheeney G, Westerhoff M, Konnick EQ, Greene DN, Lockwood CM. Real-Time PCR to Detect α-1 Antitrypsin S and Z Alleles in Formalin-Fixed Paraffin-Embedded Tissue. J Appl Lab Med 2018; 3:18-25. [PMID: 33626829 DOI: 10.1373/jalm.2017.025858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/26/2018] [Indexed: 11/06/2022]
Abstract
BACKGROUND α-1 Antitrypsin (A1AT) deficiency is an autosomal recessive genetic disease with incomplete penetrance that can cause pulmonary and liver disease. Multiple methods are available to determine A1AT genotype using peripheral blood specimens, but none are validated to detect A1AT alleles in formalin-fixed paraffin-embedded (FFPE) tissue. METHODS A real-time PCR assay was validated to detect the SERPINA1 S and Z alleles (NM_000295.4: c.863A>T, p.E288V and c.1096G>A, p.E366K, respectively) in FFPE liver tissue using allele-specific dual hybridization probes and melting curve analysis. Validation experiments were performed on genomic DNA samples (n = 11) with A1AT genotypes previously determined by orthogonal methods. RESULTS The S and Z allele assays accurately genotyped all FFPE validation specimens that had a threshold cycle <32. Validation samples produced mean melting temperatures of 55.4 °C (SD = 0.30) for mutant S alleles, 48.6 °C (SD = 0.28) for non-S alleles, 61.2 °C (SD = 0.34) for mutant Z alleles, and 54.7 °C (SD = 0.19) for non-Z alleles. Samples failing to meet quality control parameters were infrequent. CONCLUSIONS Poor PCR amplification because of low nucleic acid concentration in small biopsy specimens and time-dependent degradation in specimens stored for extended periods were the most common reasons for assay failure. The ability to determine A1AT genotype from archived surgical pathology specimens can facilitate research on the role of A1AT globules in liver disease.
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Affiliation(s)
- Lincoln J Pac
- Department of Laboratory Medicine, University of Washington, Seattle, WA.,Department of Pathology, University of Washington, Seattle, WA
| | - Gregory Cheeney
- Department of Laboratory Medicine, University of Washington, Seattle, WA.,Department of Pathology, University of Washington, Seattle, WA
| | | | - Eric Q Konnick
- Department of Laboratory Medicine, University of Washington, Seattle, WA
| | - Dina N Greene
- Department of Laboratory Medicine, University of Washington, Seattle, WA
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11
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van den Broek I, Fu Q, Kushon S, Kowalski MP, Millis K, Percy A, Holewinski RJ, Venkatraman V, Van Eyk JE. Application of volumetric absorptive microsampling for robust, high-throughput mass spectrometric quantification of circulating protein biomarkers. CLINICAL MASS SPECTROMETRY (DEL MAR, CALIF.) 2017; 4-5:25-33. [PMID: 39193127 PMCID: PMC11322776 DOI: 10.1016/j.clinms.2017.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/23/2017] [Accepted: 08/23/2017] [Indexed: 01/22/2023]
Abstract
Volumetric absorptive micro sampling (VAMS™) allows accurate sampling of 10 µL of blood from a minimally invasive finger prick and could enable remote personalized health monitoring. Moreover, VAMS overcomes effects from hematocrit and sample heterogeneity associated with dried blood spots (DBS). We describe the first application of VAMS with the Mitra® microsampling device for the quantification of protein biomarkers using an automated, high-throughput sample preparation method coupled with mass spectrometric (MS) detection. The analytical performance of the developed workflow was evaluated for 10 peptides from six clinically relevant proteins: apolipoproteins A-I, B, C-I, C-III, E, and human serum albumin (HSA). Extraction recovery from blood with three different levels of hematocrit varied between 100% and 111% for all proteins. Within-day and total assay reproducibility (i.e., 5 replicates on 5 days) ranged between 3.2-10.4% and 3.4-12.6%, respectively. In addition, after 22 weeks of storage of the Mitra microsampling devices at -80 °C, all peptide responses were within ±15% deviation from the initial response. Application to data-independent acquisition (DIA) MS further demonstrated the potential for broad applicability and the general robustness of the automated workflow by reproducible detection of 1661 peptides from 423 proteins (average 15.7%CV (n = 3) in peptide abundance), correlating to peptide abundances in corresponding plasma (R = 0.8383). In conclusion, we have developed an automated workflow for efficient extraction, digestion, and MS analysis of a variety of proteins in a fixed small volume of dried blood (i.e., 10 µL). This robust and high-throughput workflow will create manifold opportunities for the application of remote, personalized disease biomarker monitoring.
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Affiliation(s)
- Irene van den Broek
- Advanced Clinical Biosystems Research Institute, The Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Qin Fu
- Advanced Clinical Biosystems Research Institute, The Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | | | | | - Kevin Millis
- Cambridge Isotope Laboratories, Tewksbury, MA, USA
| | - Andrew Percy
- Cambridge Isotope Laboratories, Tewksbury, MA, USA
| | - Ronald J. Holewinski
- Advanced Clinical Biosystems Research Institute, The Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Vidya Venkatraman
- Advanced Clinical Biosystems Research Institute, The Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Jennifer E. Van Eyk
- Advanced Clinical Biosystems Research Institute, The Heart Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
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12
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Abstract
Deficiency of alpha-1 antitrypsin (AAT) is caused by mutations in the SERPINA1 gene that results in low concentrations of AAT in circulation. The low AAT concentration can result in uninhibited neutrophil elastase activity in the lung, leading to pulmonary tissue damage and lung disease. Clinical evaluation for possible AAT deficiency includes two critical components: measuring AAT concentration in serum and identification of AAT deficiency alleles. In this chapter the methods by which AAT concentration can be measured in the clinical laboratory are described. The two most common methodologies for AAT quantification employ immunometric techniques, specifically nephelometry and turbidimetry, which are both based on light scatter technology. The AAT in the patient sample is combined with an anti-AAT polyclonal antibody solution leading to polymer formation and a proportional amount of subsequent light scatter. Descriptions of each method are presented, and specifics of quality control and assay parameters are discussed. A special discussion focuses on interpretation of results in the context of the different AAT genetic phenotypes and in the context of patients with active inflammatory conditions. Emerging techniques for AAT quantitation by mass spectrometry are also described given that both AAT quantitation and allele identification can be performed on the same assay.
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Affiliation(s)
- Leslie J Donato
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA.
| | - Melissa R Snyder
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First St. SW, Rochester, MN, 55905, USA
| | - Dina N Greene
- Department of Laboratory Medicine, Chemistry Division, University of Washington, Seattle, WA, USA
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13
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Bengtson P, Valtonen-André C, Jonsson M. Phenotyping of α-1-Antitrypsin by liquid chromatography-high resolution mass spectrometry. CLINICAL MASS SPECTROMETRY (DEL MAR, CALIF.) 2016; 2:34-40. [PMID: 39192843 PMCID: PMC11324609 DOI: 10.1016/j.clinms.2017.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 02/16/2017] [Accepted: 02/16/2017] [Indexed: 11/19/2022]
Abstract
More than seventy-five isotypes of α-1-antitrypsin (AAT) have been described. To assess risks associated with AAT deficiency, isotype identification is necessary. Isoelectric focusing (IEF) is traditionally used for isotype differentiation, however, IEF has limited scope since it is a manual procedure that is not suitable for automation, and antitrypsin variants must differ in net charge in order to be resolved. In comparison, mass spectrometric assays are easily automated and offer a more complete solution for characterization of proteins. To capitalize on these advantages, we have developed a qualitative top-down liquid chromatography-mass spectrometry (LC-MS) method for selective phenotyping of AAT. This technique requires no sample pretreatment, and has the potential for use in routine clinical diagnostics. We have validated our LC-MS results against both DNA sequencing and IEF. Thus far, this method has identified the AAT variants PLowell, S and Z, as well as unique fragments shared by different M alleles. Its high selectivity is indirectly illustrated by the detection of a variant carrying the amino acid substitution p.Ala308Ser, which cannot be visualized by IEF.
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Affiliation(s)
- Per Bengtson
- Department of Clinical Chemistry, University Health Care in Region Skåne, Lund, Sweden
| | | | - Magnus Jonsson
- Department of Clinical Chemistry, University Health Care in Region Skåne, Malmö, Sweden
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14
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Mills JR, Cornec D, Dasari S, Ladwig PM, Hummel AM, Cheu M, Murray DL, Willrich MA, Snyder MR, Hoffman GS, Kallenberg CGM, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, St Clair EW, Stone JH, Specks U, Barnidge DR. Using Mass Spectrometry to Quantify Rituximab and Perform Individualized Immunoglobulin Phenotyping in ANCA-Associated Vasculitis. Anal Chem 2016; 88:6317-25. [PMID: 27228216 DOI: 10.1021/acs.analchem.6b00544] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Therapeutic monoclonal immunoglobulins (mAbs) are used to treat patients with a wide range of disorders including autoimmune diseases. As pharmaceutical companies bring more fully humanized therapeutic mAb drugs to the healthcare market analytical platforms that perform therapeutic drug monitoring (TDM) without relying on mAb specific reagents will be needed. In this study we demonstrate that liquid-chromatography-mass spectrometry (LC-MS) can be used to perform TDM of mAbs in the same manner as smaller nonbiologic drugs. The assay uses commercially available reagents combined with heavy and light chain disulfide bond reduction followed by light chain analysis by microflow-LC-electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-Q-TOF MS). Quantification is performed using the peak areas from multiply charged mAb light chain ions using an in-house developed software package developed for TDM of mAbs. The data presented here demonstrate the ability of an LC-MS assay to quantify a therapeutic mAb in a large cohort of patients in a clinical trial. The ability to quantify any mAb in serum via the reduced light chain without the need for reagents specific for each mAb demonstrates the unique capabilities of LC-MS. This fact, coupled with the ability to phenotype a patient's polyclonal repertoire in the same analysis further shows the potential of this approach to mAb analysis.
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Affiliation(s)
- John R Mills
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Divi Cornec
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States.,Rheumatology Department, Brest University Hospital , 29609 Brest, Cedex, France
| | - Surendra Dasari
- Department of Health Sciences Research, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Paula M Ladwig
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Amber M Hummel
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Melissa Cheu
- Genentech Inc. , South San Francisco, California 94080, United States
| | - David L Murray
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Maria A Willrich
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Melissa R Snyder
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Gary S Hoffman
- Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States
| | | | - Carol A Langford
- Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States
| | - Peter A Merkel
- University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Paul A Monach
- Boston University Medical Center , Boston, Massachusetts 02115, United States
| | - Philip Seo
- Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Robert F Spiera
- Hospital for Special Surgery , New York, New York 10021, United States
| | | | - John H Stone
- Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | - Ulrich Specks
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - David R Barnidge
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
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15
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Kandregula CAB, Smilin Bell Aseervatham G, Bentley GT, Kandasamy R. Alpha-1 antitrypsin: Associated diseases and therapeutic uses. Clin Chim Acta 2016; 459:109-116. [PMID: 27259467 DOI: 10.1016/j.cca.2016.05.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Chaya A Babu Kandregula
- Laboratory of Pulmonary Medicine, National Facility for Drug Development for Academia, Pharmaceutical & Allied Industries, Department of Pharmaceutical Technology, Centre for Excellence in Nanobio Translational REsearch (CENTRE), Anna University - BIT Campus, Tiruchirappalli, Tamil Nadu 620024, India
| | - G Smilin Bell Aseervatham
- Laboratory of Pulmonary Medicine, National Facility for Drug Development for Academia, Pharmaceutical & Allied Industries, Department of Pharmaceutical Technology, Centre for Excellence in Nanobio Translational REsearch (CENTRE), Anna University - BIT Campus, Tiruchirappalli, Tamil Nadu 620024, India
| | - Gary T Bentley
- Department of Internal Medicine, Morsani College of Medicine, Tampa, FL 33612, USA
| | - Ruckmani Kandasamy
- Laboratory of Pulmonary Medicine, National Facility for Drug Development for Academia, Pharmaceutical & Allied Industries, Department of Pharmaceutical Technology, Centre for Excellence in Nanobio Translational REsearch (CENTRE), Anna University - BIT Campus, Tiruchirappalli, Tamil Nadu 620024, India.
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16
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Sabbagh B, Mindt S, Neumaier M, Findeisen P. Clinical applications of MS-based protein quantification. Proteomics Clin Appl 2016; 10:323-45. [DOI: 10.1002/prca.201500116] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/18/2015] [Accepted: 12/30/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Bassel Sabbagh
- Institute for Clinical Chemistry; Medical Faculty Mannheim of the University of Heidelberg; University Hospital Mannheim; Mannheim Germany
| | - Sonani Mindt
- Institute for Clinical Chemistry; Medical Faculty Mannheim of the University of Heidelberg; University Hospital Mannheim; Mannheim Germany
| | - Michael Neumaier
- Institute for Clinical Chemistry; Medical Faculty Mannheim of the University of Heidelberg; University Hospital Mannheim; Mannheim Germany
| | - Peter Findeisen
- Institute for Clinical Chemistry; Medical Faculty Mannheim of the University of Heidelberg; University Hospital Mannheim; Mannheim Germany
- MVZ Labor Dr. Limbach und Kollegen; Heidelberg Germany
- Working Group Proteomics of the German United Society for Clinical Chemistry and Laboratory Medicine e.V. (DGKL); Bonn Germany
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17
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van den Broek I, Romijn FPHTM, Nouta J, van der Laarse A, Drijfhout JW, Smit NPM, van der Burgt YEM, Cobbaert CM. Automated Multiplex LC-MS/MS Assay for Quantifying Serum Apolipoproteins A-I, B, C-I, C-II, C-III, and E with Qualitative Apolipoprotein E Phenotyping. Clin Chem 2016; 62:188-97. [DOI: 10.1373/clinchem.2015.246702] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 11/03/2015] [Indexed: 12/31/2022]
Abstract
Abstract
BACKGROUND
Direct and calculated measures of lipoprotein fractions for cardiovascular risk assessment suffer from analytical inaccuracy in certain dyslipidemic and pathological states, most commonly hypertriglyceridemia. LC-MS/MS has proven suitable for multiplexed quantification and phenotyping of apolipoproteins. We developed and provisionally validated an automated assay for quantification of apolipoprotein (apo) A-I, B, C-I, C-II, C-III, and E and simultaneous qualitative assessment of apoE phenotypes.
METHODS
We used 5 value-assigned human serum pools for external calibration. Serum proteins were denatured, reduced, and alkylated according to standard mass spectrometry–based proteomics procedures. After trypsin digestion, peptides were analyzed by LC-MS/MS. For each peptide, we measured 2 transitions. We compared LC-MS/MS results to those obtained by an immunoturbidimetric assay or ELISA.
RESULTS
Intraassay CVs were 2.3%–5.5%, and total CVs were 2.5%–5.9%. The LC-MS/MS assay correlated (R = 0.975–0.995) with immunoturbidimetric assays with Conformité Européenne marking for apoA-I, apoB, apoC-II, apoC-III, and apoE in normotriglyceridemic (n = 54) and hypertriglyceridemic (n = 46) sera. Results were interchangeable for apoA-I ≤3.0 g/L (Deming slope 1.014) and for apoB-100 ≤1.8 g/L (Deming slope 1.016) and were traceable to higher-order standards.
CONCLUSIONS
The multiplex format provides an opportunity for new diagnostic and pathophysiologic insights into types of dyslipidemia and allows a more personalized approach for diagnosis and treatment of lipid abnormalities.
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Affiliation(s)
| | | | - Jan Nouta
- Department of Clinical Chemistry and Laboratory Medicine
| | | | | | - Nico P M Smit
- Department of Clinical Chemistry and Laboratory Medicine
| | - Yuri E M van der Burgt
- Department of Clinical Chemistry and Laboratory Medicine
- Center for Proteomics and Metabolomics, Leiden University Medical Center, Leiden, the Netherlands
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18
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Cui Y, Zhuang D, Tan T, Yang J. Highly sensitive visual detection of mutant DNA based on polymeric nanoparticles-participating amplification. RSC Adv 2016. [DOI: 10.1039/c6ra19860k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Taking advantage of the nanoparticles' large surface area and structural repeating characteristics, polymeric nanoparticles-participating polymerization-based amplification system was designed to enhance the sensitivity of detection.
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Affiliation(s)
- Yanjun Cui
- State Key Laboratory of Chemical Resource
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
| | - Dequan Zhuang
- State Key Laboratory of Chemical Resource
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
| | - Tianwei Tan
- State Key Laboratory of Chemical Resource
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
| | - Jing Yang
- State Key Laboratory of Chemical Resource
- Beijing Key Laboratory of Bioprocess
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
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19
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SERPINA1 Full-Gene Sequencing Identifies Rare Mutations Not Detected in Targeted Mutation Analysis. J Mol Diagn 2015; 17:689-94. [DOI: 10.1016/j.jmoldx.2015.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 05/19/2015] [Accepted: 07/01/2015] [Indexed: 01/18/2023] Open
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20
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Donato LJ, Karras RM, Katzmann JA, Murray DL, Snyder MR. Quantitation of circulating wild-type alpha-1-antitrypsin in heterozygous carriers of the S and Z deficiency alleles. Respir Res 2015; 16:96. [PMID: 26243289 PMCID: PMC4531808 DOI: 10.1186/s12931-015-0256-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 07/27/2015] [Indexed: 11/23/2022] Open
Abstract
Background Alpha-1-antitrypsin (A1AT) deficiency disease results from mutations in the A1AT gene. Controversy exists in regards to treatment of heterozygous carriers of the S and Z deficiency alleles. Quantitation of allelic expression has not been possible with standard laboratory methods. Here we show that the recently described method for liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of A1AT tryptic peptides can differentiate between mutated (S and Z) and wild-type (non-S and non-Z) proteins allowing for quantitation of circulating allelic expression in heterozygous patients. Methods Serum (244 M/M, 61 M/Z, and 63 M/S) was combined with isotopically labeled peptide standards, digested with trypsin, and quantitated by LC-MS/MS. Total and allele-specific A1AT quantitation was performed by comparison of peptide peak height ratios to a standard curve for each peptide. Linear regression was used to compare results and central 95th percentile intervals were calculated using parametric analysis. Results Quantitation of circulating wild-type A1AT based on the proteotypic and allelic (non-S and non-Z) peptides was validated in M/M patients. Proteotypic peptide concentrations correlated linearly with quantitation by non-Z and non-S peptides [slopes (Spearman correlation coefficient) of 1.09 (0.89) and 0.98 (0.80), respectively]. Allele-specific quantitation showed significant differences in wild-type protein expression in M/Z and M/S patients. Although average total A1AT concentration was lower for M/Z patients, the percentage of wild-type protein in M/Z patients was significantly higher at 82 % (55- > 95 %) compared to 63 % (43-83 %) for M/S heterozygotes. In a cohort of M/Z patients with sufficient total A1AT (≥80 mg/dL), half had insufficient wild-type protein that could have clinical implications for pulmonary dysfunction. Conclusions For the first time, a method to quantitate A1AT allele protein expression is described. Given the wide range of circulating wild-type protein observed in heterozygous patients, this method has the potential to reveal correlations between allele concentration and development and/or severity of clinical symptoms.
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Affiliation(s)
- L J Donato
- Department of Laboratory Medicine & Pathology Mayo Clinic, Mayo Clinic, 200 First St. SW, 55905, Rochester, MN, USA.
| | - R M Karras
- Present address: University of Minnesota, Minneapolis, MN, USA.
| | - J A Katzmann
- Department of Laboratory Medicine & Pathology Mayo Clinic, Mayo Clinic, 200 First St. SW, 55905, Rochester, MN, USA.
| | - D L Murray
- Department of Laboratory Medicine & Pathology Mayo Clinic, Mayo Clinic, 200 First St. SW, 55905, Rochester, MN, USA.
| | - M R Snyder
- Department of Laboratory Medicine & Pathology Mayo Clinic, Mayo Clinic, 200 First St. SW, 55905, Rochester, MN, USA.
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21
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Signal amplification strategies for DNA and protein detection based on polymeric nanocomposites and polymerization: A review. Anal Chim Acta 2015; 877:19-32. [DOI: 10.1016/j.aca.2015.01.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 11/23/2022]
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22
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Assessment of the influence of the patient's inflammatory state on the accuracy of a haptoglobin selected reaction monitoring assay. Clin Proteomics 2014; 11:38. [PMID: 25392709 PMCID: PMC4228078 DOI: 10.1186/1559-0275-11-38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/11/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The use of targeted LC-MS/MS methods for protein quantitation in clinical laboratories implies a careful evaluation of potential sources of analytical interference. In this study, we investigated whether inflammation, which is associated with both the release of proteolytic enzymes and increased expression of acute phase protease inhibitors, is affecting the accuracy of a haptoglobin selected reaction monitoring (SRM) assay. RESULTS A SRM assay was developed and used to quantify haptoglobin in 57 human serum samples. The SRM assay had CVs (n = 6) of 12.9% at 698 mg/L and 11.8% at 1690 mg/L. Results of the SRM assay were compared to those of a commercial immunonephelometric test. Passing-Bablok regression gave a proportional bias of 0.92 (95% CI: 0.82 to 1.04) and a constant bias of 75.40 (95% CI: -71.09 to 251.04), indicating that SRM and immunonephelometric assays provided comparable results. We then investigated whether the accuracy of the SRM assay was influenced by the patient's inflammatory state by assessing the relationship between the serum CRP concentration and the bias between the two methods. No correlation was found between the SRM/immunoassay bias and the CRP concentration (Pearson correlation coefficient r = 0.0898). CONCLUSIONS These data indicate that neither the release of proteolytic enzymes nor the increased level of protease inhibitors occurring during inflammation processes have a significant impact on the haptoglobin SRM assay accuracy. Such studies provide important information about potential sources of analytical interferences in protein SRM assays.
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23
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Ladwig PM, Barnidge DR, Snyder MR, Katzmann JA, Murray DL. Quantification of Serum IgG Subclasses by Use of Subclass-Specific Tryptic Peptides and Liquid Chromatography–Tandem Mass Spectrometry. Clin Chem 2014; 60:1080-8. [DOI: 10.1373/clinchem.2014.222208] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
BACKGROUND
Measurement of IgG subclasses is a useful tool for investigation of humoral immune deficiency in the presence of total IgG within reference intervals and IgG4-related disease. Nephelometry has been the method of choice for quantification. We describe an LC-MS/MS method that can multiplex all 4 subclasses along with total IgG by use of either IgG subclass-specific peptide stable isotope–labeled internal standards or a surrogate digest standard for quantification and does not rely on antigen/antibody reactions.
METHODS
We combined serum with labeled internal peptide standards and intact purified horse IgG. Samples were denatured, reduced, alkylated, and digested. We analyzed the digested serum by LC-MS/MS for IgG subclasses 1–4 and total IgG.
RESULTS
We assayed 112 patient sera by LC-MS/MS and immunonephelometry. The mean of the slopes and R2 values for IgG1, IgG2, IgG3, IgG4, and IgG were 1.18 and 0.93, respectively. Interassay imprecision for the LC-MS/MS method was <15% for total IgG and subclasses and was slightly improved by use of a calibrator peptide from an exogenous horse IgG. Summed total IgG correlated with the measured total IgG within 10%. Reference intervals and analytical measuring range were all similar to our previous validation data for the immunonephelometry assays.
CONCLUSIONS
Total IgG and IgG subclasses 1, 2, 3, and 4 can be quantified by LC-MS/MS with performance comparable to nephelometry.
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Affiliation(s)
- Paula M Ladwig
- Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | | | | | - David L Murray
- Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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24
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Minimalistic sample preparation strategies for LC–MS quantification of large molecule biopharmaceuticals: a case study highlighting alpha-1 antitrypsin protein. Bioanalysis 2014; 6:1813-25. [DOI: 10.4155/bio.14.146] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Large molecule biotherapeutics pose a distinctive bioanalytical challenge for LC–MS assay development, particularly when optimizing sample enrichment steps. Alpha-1 antitrypsin (AAT) is used as an example for highlighting large-molecule assay-development strategies. Results: Two sensitive and selective LC–MS/MS-based quantification assays were developed. Fit-for-purpose assay qualifications for BAL and serum matrices were performed by assessing sensitivity, precision and accuracy, dilution linearity and interferences. Conclusion: Our approach to sample preparation focuses on optimizing the simplest methodology necessary to generate fit-for-purpose bioanalytical assays. To measure AAT protein levels in preclinical species with selectivity and increased assay sensitivity, a minimalistic sample preparation strategy was adopted that included either traditional direct digestion or a more complicated immunoprecipitation enrichment process.
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25
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Xu L, Yuan L, Liu S. Macroinitiator triggered polymerization for versatile immunoassay. RSC Adv 2014. [DOI: 10.1039/c3ra45504a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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26
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Bornhorst JA, Greene DN, Ashwood ER, Grenache DG. α 1 -Antitrypsin Phenotypes and Associated Serum Protein Concentrations in a Large Clinical Population. Chest 2013; 143:1000-1008. [DOI: 10.1378/chest.12-0564] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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27
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Greene DN, Elliott-Jelf M, Straseski JA, Grenache DG. Facilitating the laboratory diagnosis of α1-antitrypsin deficiency. Am J Clin Pathol 2013; 139:184-91. [PMID: 23355203 DOI: 10.1309/ajcp6xbk8ulzxwfp] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
α(1)-Antitrypsin (AAT) deficiency leads to deterioration of the lungs that can be prevented with diagnosis and treatment. Isoelectric focusing (IEF) electrophoresis is the current biochemical gold standard for detecting AAT deficiency variants but involves complex interpretation. Variant AAT samples were collected over a 2-year period. Stability of AAT for phenotype determination was assessed in whole blood, dried blood spots, and dried serum spots. A compendium displaying 13 common and 5 rare AAT phenotypes was created, and a detailed methodology describing how to recognize AAT banding patterns and interpret a rare phenotype accompanied these visual data. AAT was stable for IEF phenotype analysis for at least 1 week in whole blood and for 24 hours on dried serum spots. In conclusion, a reference compendium of known AAT phenotypes was established that can serve as a resource for interpreting AAT phenotypes.
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Affiliation(s)
- Dina N. Greene
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT
| | - M.C. Elliott-Jelf
- ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT
| | - Joely A. Straseski
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT
- ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT
| | - David G. Grenache
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT
- ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT
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28
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Yuan L, Xu L, Liu S. Integrated tyramide and polymerization-assisted signal amplification for a highly-sensitive immunoassay. Anal Chem 2012. [PMID: 23181414 DOI: 10.1021/ac302439v] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A novel strategy for ultrasensitive detection of model protein based on the integration of tyramide signal amplification (TSA) and polymerization-assisted signal amplification was proposed. The surface-initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) was triggered by the initiator-coupled protein immobilized on the electrode surface through sandwiched immunoreactions. Growth of long chain polymeric materials provided numerous epoxy groups for subsequent coupling of horseradish peroxidase (HRP), which in turn significantly increased the loading of quantum dots (QDs) labeled tyramide in the presence of hydrogen peroxide. As a result, electrochemiluminescence (ECL) and square-wave voltammetric (SWV) measurements showed 9.4- and 10.5-fold increase in detection signal in comparison with the unamplified method, respectively. To demonstrate the feasibility of this approach, human immunoglobulin G antigen (IgG) as a model target protein was employed and the detection limits were 0.73 and 0.09 pg mL(-1) for ECL and SWV, respectively. The results showed that sensitivity of the presented immunoassay significantly increased by one-order of magnitude and offered great application promises in providing a sensitive, specific, and potent method for biological detection.
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Affiliation(s)
- Liang Yuan
- State Key Laboratory of Bioelectronics, School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, 211189, P.R. China
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29
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Abstract
Because of the potential applications of biosensors in clinical diagnosis, biomedical research, environmental analysis, and food quality control, researchers are very interested in developing sensitive, selective, rapid, reliable, and low-cost versions of these devices. A classic biosensor directly transduces ligand-target binding events into a measurable physical readout. Because of the limited detection sensitivity and selectivity in earlier biosensors, researchers have developed a number of sensing/signal amplification strategies. Through the use of nanostructured or long chain polymeric materials to increase the upload of signal tags for amplification of the signal readout associated with the ligand-target binding events, researchers have achieved high sensitivity and exceptional selectivity. Very recently, target-triggered polymerization-assisted signal amplification strategies have been exploited as a new biosensing mechanism with many attractive features. This strategy couples a small initiator molecule to the DNA/protein detection probe prior to DNA hybridization or DNA/protein and protein/protein binding events. After ligand-target binding, the in-situ polymerization reaction is triggered. As a result, tens to hundreds of small monomer signal reporter molecules assemble into long chain polymers at the location where the initiator molecule was attached. The resulting polymer materials changed the optical and electrochemical properties at this location, which make the signal easily distinguishable from the background. The assay time ranged from minutes to hours and was determined by the degree of amplification needed. In this Account, we summarize a series of electrochemical and optical biosensors that employ target-triggered polymerization. We focus on the use of atom transfer radical polymerization (ATRP), as well as activator generated electron transfer for atom transfer radical polymerization (AGET ATRP) for in-situ formation of polymer materials for optically or electrochemically transducing DNA hybridization and protein-target binding. ATRP and AGET ATRP can tolerate a wide range of functional monomers. They also allow for the preparation of well-controlled polymers with narrow molecular weight distribution, which was predetermined by the concentration ratio of the consumed monomer to the introduced initiator. Because the reaction initiator can be attached to a variety of detection probes through well-established cross-linking reactions, this technique could be expanded as a universal strategy for the sensitive detection of DNA and proteins. We see enormous potential for this new sensing technology in the development of portable DNA/protein sensors for point-of-need applications.
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Affiliation(s)
- Yafeng Wu
- State Key Laboratory of Bioelectronics, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 210096, People's Republic of China
| | - Wei Wei
- State Key Laboratory of Bioelectronics, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 210096, People's Republic of China
| | - Songqin Liu
- State Key Laboratory of Bioelectronics, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 210096, People's Republic of China
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30
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Replacing immunoassays with tryptic digestion-peptide immunoaffinity enrichment and LC-MS/MS. Bioanalysis 2012; 4:281-90. [PMID: 22303832 DOI: 10.4155/bio.11.319] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
For decades, immunoassays have provided the framework for protein biomarker studies in clinical medicine and in therapeutic monitoring for drug development. At the same time, investigators have uncovered many issues that make immunoassays unreliable in many human serum and plasma samples. LC-MS/MS after tryptic digestion of proteins is potentially an attractive solution, but the sensitivity of the method is not sufficient to measure many important low-abundance proteins directly. The use of antipeptide antibodies to immunoenrich peptides of interest can improve the sensitivity of the approach, greatly simplify the matrix enabling shortened chromatographic runs, and facilitate the multiplexed quantification of analytes, which could reduce the costs of quantitative protein measurements in complex specimens. We provide an overview of the method and the steps needed to develop an assay. In addition, we review the efforts to make this method generally more applicable.
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31
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Bystrom CE. A Step Toward Simplicity for a Complex Analyte. Clin Chem 2011; 57:1091-2. [DOI: 10.1373/clinchem.2011.167478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Cory E Bystrom
- Quest Diagnostics Nichols Institute, San Juan Capistrano, CA
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