1
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Gaetani ML, Pinto IC, Li M, O'Connor P, Giorgi-Coll S, Tyreman M, Rumary KL, Schouten JA, Davis P, Dixon AM. Towards detection of structurally-diverse glycated epitopes in native proteins: Single-chain antibody directed to non-A1c epitope in human haemoglobin. Mol Immunol 2024; 166:16-28. [PMID: 38181455 DOI: 10.1016/j.molimm.2023.12.008] [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] [Received: 10/02/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/07/2024]
Abstract
Over 500 million people worldwide are affected by diabetes mellitus, a chronic disease that leads to high blood glucose levels and causes severe side effects. The predominant biological marker for diagnosis of diabetes is glycated haemoglobin (GHb). In human blood the predominant reducing sugar, glucose, irreversibly conjugates onto accessible amine groups within Hb. Most methods for diagnosis and monitoring of diabetes selectively detect N-terminal glycation at Val-1 on the β-globin chain, but not glycation at other sites. Detection of other glycated epitopes of GHb has the potential to provide new information on the extent, duration and timing of elevated glucose, facilitating personalised diagnosis and intelligent diabetic control. In this work, a new anti-GHb Fab antibody (Fab-1) specific for haemoglobin A1c (HbA1c) with nanomolar affinity was discovered via epitope-directed immunisation and phage display. A single chain variable fragment (scFv) antibody derived from Fab-1 retained affinity and specificity for HbA1c, and affinity was enhanced tenfold upon addition of an enhanced green fluorescent protein tag. Both the scFv and Fab-1 recognised an epitope within HbA1c that was distinct from β-Val-1, and our data suggest that this epitope may include glycation at Lys-66 in the β-globin chain. To our knowledge, this is the first report of an scFv/Fab anti-glycated epitope antibody that recognises a non-A1c epitope in GHb, and confirms that fructosamine attached to different, discrete glycation sites within the same protein can be resolved from one another by immunoassay.
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Affiliation(s)
- Miss Lucia Gaetani
- Medical Research Council Doctoral Training Programme, Warwick Medical School, UK
| | - Isabel Campos Pinto
- iBET, Bayer Satellite Lab, Av. República, Quinta do Marquês, Edifício iBET/ITQB, Oeiras 2780-157, Portugal
| | - Meng Li
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Peter O'Connor
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | | | - Matthew Tyreman
- Global Access Diagnostics, Thurleigh, Bedfordshire MK44 2YA, UK
| | | | | | - Paul Davis
- Global Access Diagnostics, Thurleigh, Bedfordshire MK44 2YA, UK
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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2
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Gao W, Jin Y, Huang Y, Tang H. Discordantly high HbA1c may assist in diagnosing α-thalassemia but not diabetes: A case report. J Diabetes Investig 2022; 13:1633-1635. [PMID: 35474445 PMCID: PMC9434564 DOI: 10.1111/jdi.13820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/18/2022] [Accepted: 04/25/2022] [Indexed: 02/05/2023] Open
Abstract
Glycated hemoglobin (HbA1c) is an important method for monitoring blood glucose and diagnosing diabetes. High‐performance liquid chromatography is more commonly used in the laboratory for the detection of HbA1c. Although HbA1c detected by high‐performance liquid chromatography is susceptible to abnormal hemoglobin, there are few reports that it is affected by α‐thalassemia. Previous reports have generally concluded that α‐thalassemia does not affect or lower HbA1c. Here, we report a case of discordantly high HbA1c inconsistent with fasting blood glucose. Finally, the patient was diagnosed with α‐thalassemia and insulin resistance. α‐Thalassemia might lead to a discordantly high HbA1c result, which could be attributed to elevated hemoglobin H. In this case, glycated albumin might accurately reflect the real average level of blood glucose. When finding discordant HbA1c, patients should be advised to undergo thalassemia and hemoglobinopathy screening by diabetologists/endocrinologists or primary care physicians to avoid a missed diagnosis of hematopathy.
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Affiliation(s)
- Wei Gao
- Health Management Center, West China Hospital, Sichuan University, Chengdu, 610041, P.R. China
| | - Yanwen Jin
- Biliary surgery, West China Hospital, Sichuan University, Chengdu, 610041, P.R. China
| | - Yan Huang
- Health Management Center, West China Hospital, Sichuan University, Chengdu, 610041, P.R. China
| | - Huairong Tang
- Health Management Center, West China Hospital, Sichuan University, Chengdu, 610041, P.R. China
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3
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Pratumvinit B, Reesukumal K, Hanyongyuth S, Wangchaijaroenkit S, Pooliam J, Kost GJ, Kamkang P, Loh TP. Hemoglobin A1c Levels Are Slightly but Significantly Lower in Normoglycemic Subjects With the Hemoglobin E Phenotype. Ann Lab Med 2019; 39:209-213. [PMID: 30430785 PMCID: PMC6240528 DOI: 10.3343/alm.2019.39.2.209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/13/2018] [Accepted: 10/12/2018] [Indexed: 01/08/2023] Open
Abstract
Hb mutations can alter the structure, behavior, stability, or quantity of the globin chain produced. Some Hb variants shorten the erythrocyte life span, resulting in physiologically lower hemoglobin A1c (HbA1c) levels. The hemoglobin E (HbE) phenotype involves a single-nucleotide polymorphism that reduces β-globin chain synthesis. We compared the HbA1c levels of subjects with normal Hb (HbAA; N=131) and HbE (N=148) phenotypes, examining potential hematological and biochemical factors contributing to differences in HbA1c levels. All had normal fasting plasma glucose (<5.6 mmol/L), AST, ALT, and creatinine levels. Mean±SD HbA1c levels differed between HbAA and HbE subjects: 5.5±0.3% and 5.3±0.3% (P<0.001) according to an immunoassay, and 5.5±0.3% and 5.3±0.3% (P<0.001) according to cation-exchange HPLC, respectively. In multiple logistic regression, only mean corpuscular volume (P<0.001) contributed to the difference in HbA1c levels between groups. Although a 0.2% difference in HbA1c is relatively small and unlikely to alter clinical decisions, epidemiologically, this can lead to misclassification of a significant proportion of the population, especially since the threshold of non-diabetes HbA1c (≤5.6%) falls very close to the HbA1c median of the general population.
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Affiliation(s)
- Busadee Pratumvinit
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
| | - Kanit Reesukumal
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Sithikan Hanyongyuth
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Sujitra Wangchaijaroenkit
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Julaporn Pooliam
- Division of Clinical Epidemiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Gerald J Kost
- Point-of-Care Testing Center for Teaching and Research (POCT·CTR), School of Medicine, University of California, Davis, California, USA
| | - Panumas Kamkang
- Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Tze Ping Loh
- Department of Laboratory Medicine, National University Hospital, Singapore
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4
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A simple means to differentiate labile HbA1c from haemoglobin variant on Bio-Rad Variant II Turbo 2.0 cation-exchange HPLC method. Pathology 2017; 49:817-818. [PMID: 29079002 DOI: 10.1016/j.pathol.2017.08.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/23/2017] [Accepted: 08/03/2017] [Indexed: 11/22/2022]
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5
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Sherwani SI, Khan HA, Ekhzaimy A, Masood A, Sakharkar MK. Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients. Biomark Insights 2016; 11:95-104. [PMID: 27398023 PMCID: PMC4933534 DOI: 10.4137/bmi.s38440] [Citation(s) in RCA: 521] [Impact Index Per Article: 65.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/09/2016] [Accepted: 06/09/2016] [Indexed: 02/06/2023] Open
Abstract
Diabetes is a global endemic with rapidly increasing prevalence in both developing and developed countries. The American Diabetes Association has recommended glycated hemoglobin (HbA1c) as a possible substitute to fasting blood glucose for diagnosis of diabetes. HbA1c is an important indicator of long-term glycemic control with the ability to reflect the cumulative glycemic history of the preceding two to three months. HbA1c not only provides a reliable measure of chronic hyperglycemia but also correlates well with the risk of long-term diabetes complications. Elevated HbA1c has also been regarded as an independent risk factor for coronary heart disease and stroke in subjects with or without diabetes. The valuable information provided by a single HbA1c test has rendered it as a reliable biomarker for the diagnosis and prognosis of diabetes. This review highlights the role of HbA1c in diagnosis and prognosis of diabetes patients.
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Affiliation(s)
- Shariq I. Sherwani
- Department of Internal Medicine, Division of Pulmonary Medicine, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Haseeb A. Khan
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
- CORRESPONDENCE: ;
| | - Aishah Ekhzaimy
- Division of Endocrinology, Department of Medicine, King Khalid University Hospital, Riyadh, Saudi Arabia
| | - Afshan Masood
- Obesity Research Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Meena K. Sakharkar
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Canada
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Affiliation(s)
- David C Klonoff
- Diabetes Research Institute, Mills-Peninsula Health Services, San Mateo, CA, USA
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7
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Abstract
In vivo modification of proteins by molecules with reactive carbonyl groups leads to intermediate and advanced glycation end products (AGE). Glucose is a significant glycation reagent due to its high physiological concentration and poorly controlled diabetics show increased albumin glycation. Increased levels of glycated and AGE-modified albumin have been linked to diabetic complications, neurodegeneration, and vascular disease. This review discusses glycated albumin formation, structural consequences of albumin glycation on drug binding, removal of circulating AGE by several scavenger receptors, as well as AGE-induced proinflammatory signaling through activation of the receptor for AGE. Analytical methods for quantitative detection of protein glycation and AGE formation are compared. Finally, the use of glycated albumin as a novel clinical marker to monitor glycemic control is discussed and compared to glycated hemoglobin (HbA1c) as long-term indicator of glycemic status.
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