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Binder MD, Nwoke EC, Morwitch E, Dwyer C, Li V, Xavier A, Lea RA, Lechner-Scott J, Taylor BV, Ponsonby AL, Kilpatrick TJ. HLA-DRB1*15:01 and the MERTK Gene Interact to Selectively Influence the Profile of MERTK-Expressing Monocytes in Both Health and MS. Neurol Neuroimmunol Neuroinflamm 2024; 11:e200190. [PMID: 38150649 PMCID: PMC10752576 DOI: 10.1212/nxi.0000000000200190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 10/31/2023] [Indexed: 12/29/2023]
Abstract
BACKGROUND AND OBJECTIVES HLA-DRB1*15:01 (DR15) and MERTK are 2 risk genes for multiple sclerosis (MS). The variant rs7422195 is an expression quantitative trait locus for MERTK in CD14+ monocytes; cells with phagocytic and immunomodulatory potential. We aimed to understand how drivers of disease risk and pathogenesis vary with HLA and MERTK genotype and disease activity. METHODS We investigated how proportions of monocytes vary with HLA and MERTK genotype and disease activity in MS. CD14+ monocytes were isolated from patients with MS at relapse (n = 40) and 3 months later (n = 23). Healthy controls (HCs) underwent 2 blood collections 3 months apart. Immunophenotypic profiling of monocytes was performed by flow cytometry. Methylation of 35 CpG sites within and near the MERTK gene was assessed in whole blood samples of individuals experiencing their first episode of clinical CNS demyelination (n = 204) and matched HCs (n = 345) using an Illumina EPIC array. RESULTS DR15-positive patients had lower proportions of CD14+ MERTK+ monocytes than DR15-negative patients, independent of genotype at the MERTK SNP rs7422195. Proportions of CD14+ MERTK+ monocytes were further reduced during relapse in DR15-positive but not DR15-negative patients. Patients homozygous for the major G allele at rs7422195 exhibited higher proportions of CD14+ MERTK+ monocytes at both relapse and remission compared with controls. We observed that increased methylation of the MERTK gene was significantly associated with the presence of DR15. DISCUSSION DR15 and MERTK genotype independently influence proportions of CD14+ MERTK+ monocytes in MS. We confirmed previous observations that the MERTK risk SNP rs7422195 is associated with altered MERTK expression in monocytes. We identified that expression of MERTK is stratified by disease in people homozygous for the major G allele of rs7422195. The finding that the proportion of CD14+ MERTK+ monocytes is reduced in DR15-positive individuals supports prior data identifying genetic links between these 2 loci in influencing MS risk. DR15 genotype-dependent alterations in methylation of the MERTK gene provides a molecular link between these loci and identifies a potential mechanism by which MERTK expression is influenced by DR15. This links DR15 haplotype to MS susceptibility beyond direct influence on antigen presentation and suggests the need for HLA-based stratification of approaches to MERTK as a therapeutic target.
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Affiliation(s)
- Michele D Binder
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Eze C Nwoke
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Ellen Morwitch
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Chris Dwyer
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Vivien Li
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Alexandre Xavier
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Rodney A Lea
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Jeannette Lechner-Scott
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Bruce V Taylor
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Anne-Louise Ponsonby
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
| | - Trevor J Kilpatrick
- From the Florey Institute of Neuroscience and Mental Health (M.D.B., E.C.N., E.M., C.D., V.L., A.-L.P., T.J.K.); Department of Anatomy and Physiology (M.D.B.), University of Melbourne, Parkville; Crux Biolabs (E.C.N.), Bayswater; Department of Neurology (C.D.), Royal Melbourne Hospital, Parkville; Department of Neurology (A.X., J.L.-S.), John Hunter Hospital, Newcastle; Hunter Medical Research Institute (A.X., J.L.-S.), University of Newcastle, New South Wales Genomics Research Centre (R.A.L.), Centre of Genomics and Personalised Health, Queensland University of Technology; and Menzies Institute for Medical Research (B.V.T.), University of Tasmania, Hobart, Australia
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Blades F, Chambers JD, Aumann TD, Nguyen CTO, Wong VHY, Aprico A, Nwoke EC, Bui BV, Grayden DB, Kilpatrick TJ, Binder MD. White matter tract conductivity is resistant to wide variations in paranodal structure and myelin thickness accompanying the loss of Tyro3: an experimental and simulated analysis. Brain Struct Funct 2022; 227:2035-2048. [PMID: 35441271 DOI: 10.1007/s00429-022-02489-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/25/2022] [Indexed: 11/30/2022]
Abstract
Myelination within the central nervous system (CNS) is crucial for the conduction of action potentials by neurons. Variation in compact myelin morphology and the structure of the paranode are hypothesised to have significant impact on the speed of action potentials. There are, however, limited experimental data investigating the impact of changes in myelin structure upon conductivity in the central nervous system. We have used a genetic model in which myelin thickness is reduced to investigate the effect of myelin alterations upon action potential velocity. A detailed examination of the myelin ultrastructure of mice in which the receptor tyrosine kinase Tyro3 has been deleted showed that, in addition to thinner myelin, these mice have significantly disrupted paranodes. Despite these alterations to myelin and paranodal structure, we did not identify a reduction in conductivity in either the corpus callosum or the optic nerve. Exploration of these results using a mathematical model of neuronal conductivity predicts that the absence of Tyro3 would lead to reduced conductivity in single fibres, but would not affect the compound action potential of multiple myelinated neurons as seen in neuronal tracts. Our data highlight the importance of experimental assessment of conductivity and suggests that simple assessment of structural changes to myelin is a poor predictor of neural functional outcomes.
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Affiliation(s)
- Farrah Blades
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia.,Centre for Solar Biotechnology, Institute for Molecular Biosciences, University of Queensland, St Lucia, QLD, 4072, Australia
| | - Jordan D Chambers
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Timothy D Aumann
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Andrea Aprico
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Eze C Nwoke
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - David B Grayden
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Trevor J Kilpatrick
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Michele D Binder
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, 3010, Australia. .,Department of Anatomy and Physiology, University of Melbourne, Parkville, VIC, 3010, Australia.
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