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Baysac K, Sun G, Nakano H, Schmitz EG, Cruz AC, Fisher C, Bailey AC, Mace E, Milner JD, Ombrello MJ. PLCG2-associated immune dysregulation (PLAID) comprises broad and distinct clinical presentations related to functional classes of genetic variants. J Allergy Clin Immunol 2024; 153:230-242. [PMID: 37769878 DOI: 10.1016/j.jaci.2023.08.036] [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: 02/13/2023] [Revised: 08/11/2023] [Accepted: 08/21/2023] [Indexed: 10/02/2023]
Abstract
BACKGROUND Pathogenic variants of phospholipase C gamma 2 (PLCG2) cause 2 related forms of autosomal-dominant immune dysregulation (ID), PLCγ2-associated antibody deficiency and immune dysregulation (PLAID) and autoinflammatory PLAID (APLAID). Since describing these conditions, many PLCG2 variants of uncertain significance have been identified by clinical sequencing of patients with diverse features of ID. OBJECTIVE We sought to functionally classify PLCG2 variants and explore known and novel genotype-function-phenotype relationships. METHODS Clinical data from patients with PLCG2 variants were obtained via standardized questionnaire. PLCG2 variants were generated by mutagenesis of enhanced green fluorescent protein (EGFP)-PLCG2 plasmid, which was overexpressed in Plcg2-deficient DT-40 B cells. B-cell receptor-induced calcium flux and extracellular signal-regulated kinase phosphorylation were assayed by flow cytometry. In some cases, stimulation-induced calcium flux was also measured in primary patient cells. RESULTS Three-fourths of PLCG2 variants produced functional alteration of B-cell activation, in vitro. Thirteen variants led to gain of function (GOF); however, most functional variants defined a new class of PLCG2 mutation, monoallelic loss of function (LOF). Susceptibility to infection and autoinflammation were common with both GOF and LOF variants, whereas a new phenotypic cluster consisting of humoral immune deficiency, autoinflammation, susceptibility to herpesvirus infection, and natural killer cell dysfunction was observed in association with multiple heterozygous LOF variants detected in both familial and sporadic cases. In some cases, PLCG2 variants produced greater effects in natural killer cells than in B cells. CONCLUSIONS This work expands the genotypic and phenotypic associations with functional variation in PLCG2, including a novel form of ID in carriers of heterozygous loss of PLCG2 function. It also demonstrates the need for more diverse assays for assessing the impact of PLCG2 variants on human disease.
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Affiliation(s)
- Kathleen Baysac
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Guangping Sun
- Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md
| | - Hiroto Nakano
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Elizabeth G Schmitz
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Anthony C Cruz
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Charles Fisher
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Alexis C Bailey
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md
| | - Emily Mace
- Division of Allergy, Immunology and Rheumatology, Department of Pediatrics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY
| | - Joshua D Milner
- Division of Allergy, Immunology and Rheumatology, Department of Pediatrics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY
| | - Michael J Ombrello
- Translational Genetics and Genomics Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Md.
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Diks AM, Teodosio C, de Mooij B, Groenland RJ, Naber BAE, de Laat IF, Vloemans SA, Rohde S, de Jonge MI, Lorenz L, Horsten D, van Dongen JJM, Berkowska MA, Holstege H. Carriers of the p.P522R variant in PLCγ2 have a slightly more responsive immune system. Mol Neurodegener 2023; 18:25. [PMID: 37081539 PMCID: PMC10116473 DOI: 10.1186/s13024-023-00604-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/14/2023] [Indexed: 04/22/2023] Open
Abstract
BACKGROUND The rs72824905 single-nucleotide polymorphism in the PLCG2 gene, encoding the p.P522R residue change in Phospholipase C gamma 2 (PLCγ2), associates with protection against several dementia subtypes and with increased likelihood of longevity. Cell lines and animal models indicated that p.P522R is a functional hypermorph. We aimed to confirm this in human circulating peripheral immune cells. METHODS We compared effects of p.P522R on immune system function between carriers and non-carriers (aged 59-103y), using in-depth immunophenotyping, functional B-cell and myeloid cell assays, and in vivo SARS-CoV-2 vaccination. RESULTS In line with expectations, p.P522R impacts immune cell function only slightly, but it does so across a wide array of immune cell types. Upon B-cell stimulation, we observed increased PLCγ2 phosphorylation and calcium release, suggesting increased B-cell sensitivity upon antigen recognition. Further, p.P522R-carriers had higher numbers of CD20++CD21-CD24+ naive B cells and IgG1+ memory B cells. In myeloid cells, normalized ROS production was higher upon PLCγ2-dependent stimulation. On classical monocytes, CD33 levels were elevated. Furthermore, carriers expressed lower levels of allergy-related FcεRI on several immune cell subsets. Nevertheless, carriers and non-carriers had similar serological responses to SARS-CoV-2 vaccination. CONCLUSION The immune system from p.P522R-carriers is slightly more responsive to stimulation than in non-carriers.
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Affiliation(s)
- Annieck M Diks
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
- Department of Human Genetics, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Cristina Teodosio
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
- Translational and Clinical Research Program, Cancer Research Center (IBMCC; University of Salamanca - CSIC), Salamanca, Spain
- Department of Medicine, University of Salamanca and Institute of Biomedical Research of Salamanca (IBSAL), Salamanca, Spain
| | - Bas de Mooij
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Rick J Groenland
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Brigitta A E Naber
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Inge F de Laat
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Sandra A Vloemans
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Susan Rohde
- Department of Human Genetics, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Marien I de Jonge
- Laboratory of Medical Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Linda Lorenz
- Department of Human Genetics, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Debbie Horsten
- Department of Human Genetics, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands
| | - Jacques J M van Dongen
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands.
- Translational and Clinical Research Program, Cancer Research Center (IBMCC; University of Salamanca - CSIC), Salamanca, Spain.
- Department of Medicine, University of Salamanca and Institute of Biomedical Research of Salamanca (IBSAL), Salamanca, Spain.
| | - Magdalena A Berkowska
- Department of Immunology, Leiden University Medical Center, Albinusdreef 2, Leiden, ZA, 2333, the Netherlands
| | - Henne Holstege
- Department of Human Genetics, Vrije Universiteit Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands.
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Li K, Ran B, Wang Y, Liu L, Li W. PLCγ2 impacts microglia-related effectors revealing variants and pathways important in Alzheimer’s disease. Front Cell Dev Biol 2022; 10:999061. [PMID: 36147734 PMCID: PMC9485805 DOI: 10.3389/fcell.2022.999061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/15/2022] [Indexed: 11/30/2022] Open
Abstract
Alzheimer’s disease (AD) is an irreversible neurodegenerative disease mainly characterized by memory loss and cognitive decline. The etiology of AD is complex and remains incompletely understood. In recent years, genome-wide association studies (GWAS) have increasingly highlighted the central role of microglia in AD pathology. As a trans-membrane receptor specifically present on the microglia in the central nervous system, phosphatidylinositol-specific phospholipase C gamma 2 (PLCγ2) plays an important role in neuroinflammation. GWAS data and corresponding pathological research have explored the effects of PLCG2 variants on amyloid burden and tau pathologies that underline AD. The link between PLCγ2 and other AD-related effectors in human and mouse microglia has also been established, placing PLCγ2 downstream of the triggering receptor expressed on myeloid cells 2 (TREM2), toll-like receptor 4 (TLR4), Bruton’s tyrosine kinase (BTK), and colony-stimulating factor 1 receptor (CSF1R). Because the research on PLCγ2’s role in AD is still in its early stages, few articles have been published, therefore in this paper, we integrate the relevant research published to date, review the structural features, expression patterns, and related pathways of PLCγ2, and summarize the recent studies on important PLCG2 variants related to AD. Furthermore, the possibility and challenge of using PLCγ2 to develop therapeutic drugs for AD are also discussed.
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