Dataset Information

Defects of CTLA-4 Are Associated with Regulatory T Cells in Myasthenia Gravis Implicated by Intravenous Immunoglobulin Therapy.

ABSTRACT: Myasthenia gravis (MG) is a CD4+ T cell-dependent autoimmune disease resulting from aberrant immune response mediated by circulating autoantibodies at the neuromuscular junction. Intravenous immunoglobulin (IVIg) is an expensive and commonly used immunotherapeutic approach to treat patients with MG. The mechanisms of actions involved in IVIg treatment, however, remain to be investigated. In an effort to examine the roles of various subsets of CD4+ T cells in the periphery blood of MG and uncover the mechanisms that contribute to the therapeutical effects of IVIg, we first demonstrated that a subset of CD4+ T cells, CTLA-4-expressing regulatory T (Treg) cells, were underrepresented and functionally defective in MG patients. The dynamic profiling during the IVIg therapy course further revealed an inverse relationship between the frequency of CTLA-4+ Treg and the quantitative MG (QMG) score that represents disease severity. Our mechanistic studies indicated that IVIg expands CTLA-4-Treg cells via modulating antigen-presenting dendritic cells (DCs). To determine the molecular defects of CTLA-4 in abnormities of Treg in MG patients, we demonstrated hypermethylation at -658 and -793 CpGs of CTLA-4 promoter in MG Tregs. Interestingly, IVIg therapy significantly reduced the methylation level at these two sites in MG patients. Overall, our study may suggest a role of CTLA-4 in functionally defected Treg cells in MG and its actions involved in IVIg therapy.

SUBMITTER: Xu W

PROVIDER: S-EPMC7042523 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Defects of CTLA-4 Are Associated with Regulatory T Cells in Myasthenia Gravis Implicated by Intravenous Immunoglobulin Therapy.

Xu Wenhua W Ren Mingshan M Ghosh Swagata S Qian Kai K Luo Zhaofeng Z Zhang Aimei A Zhang Cuiping C Cui Jiajun J

Mediators of inflammation 20200214

Myasthenia gravis (MG) is a CD4<sup>+</sup> T cell-dependent autoimmune disease resulting from aberrant immune response mediated by circulating autoantibodies at the neuromuscular junction. Intravenous immunoglobulin (IVIg) is an expensive and commonly used immunotherapeutic approach to treat patients with MG. The mechanisms of actions involved in IVIg treatment, however, remain to be investigated. In an effort to examine the roles of various subsets of CD4<sup>+</sup> T cells in the periphery b ...[more]

PMID: 32148437

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Project description:ObjectiveTo find out if the failure in immunotolerance of myasthenia gravis (MG) is a possible aspect of deduction in Breg cells and to characterize B cell subsets in MG.MethodsFlow cytometry detection and enzyme-linked immunosorbent assays in peripheral blood films of 10 MG patients and 10 healthy controls (HCs) were performed after isolation of B cells. The CD19+CD5+CD1d+ Breg cells percentages were measured to complement a B cell phenotype assay and frequencies of B cell subsets. The clinical outcome measures and immunological variables of patients with MG were compared with HCs.ResultsPatients with MG had relatively lowered percentages of CD19+CD5+CD1d+ Breg cells as compared to HCs. The production of interleukin (IL)-10 and transforming growth factor (TGF)-?1 was relatively lesser in patients with MG than HCs, which were linked with more severe of MG disease status according to Myasthenia Gravis Foundation of America (MGFA) clinical classification. The reduction of cytokine production was more significant for IL-10 than TGF-?1 when compared to HCs.ConclusionIt has been observed that the reduced number of B cells is able to produce IL-10 in MG patients but lesser than compared to HCs. The Bregs reduction mainly was regarded by the severity of disease status, which was highly significant and also by disease duration which was statistically significant as well. The findings of the measurement of B cell phenotype assay and frequencies of B cell subsets between MGs and HCs give us new ideas to develop B cell-mediated therapies of MG such as (1) isolated B cells of MGs could be cultured with steroids, e.g., dexamethasone in vitro to see if it induces the CD19+CD5+CD1d+ Breg cells, (2) it may observe whether induced CD19+CD5+CD1d+ Bregs have higher production of IL-10 and TGF-?1, as both are linked with disease severity, and (3) after completion in vitro steps, through further research in vivo to observe whether it improves the function of MG disease status.

Project description:Myasthenia gravis (MG) is an autoimmune disease affecting the neuromuscular junction, whose clinical hallmark is muscle weakness and early fatigability. Azathioprine (AZA) is commonly used in Myasthenia Gravis therapy. AZA is a purine antagonist, which inhibits the cell cycle in the resting and DNA synthesis phases. It is usually used as an immunosuppressant to block T- and B-cell proliferation. AZA, bioconverted to 6-mercaptopurine by glutathione S-transferase (GST), can be metabolized either through the hypoxanthine phosphoribosyl transferase pathway to active 6-thioguanine nucleotides (6-TGN) or through the thiopurine S-methyltransferase (TPMT) pathway to inactive methyl-thiopurine metabolites. The incorporation of active 6-TGNs into DNA, causing breaks in DNA strands resulting in interference with RNA production and thereby protein synthesis, is responsible for the drug effect. The response to AZA is determined by which metabolic pathway is being favored. While balanced use of both HPRT and TPMT pathways results in responsiveness to AZA, hyperactivity of TPMT skews the balance towards the TPMT pathway and results in unresponsiveness to AZA with no pharmacological effect. In contrast, low TPMT activity skews the balance towards the HPRT pathway, resulting in increasing side-effects due to the accumulation of 6-TGNs. Current treatments for MG therapy are often inadequate because less than 40% of patients achieve complete remission with available drugs. This reflects the lack of drugs acting on target sites for which there is strong evidence of pathogenicity and the inability to identify responder patients. No criteria for responsiveness are available, exposing patients to unpredictable failures and unpredictable side effects. These individuals are at particular risk for adverse drug reaction (ADRs) or therapeutic failure. Genetic profiling with the Affymetrix drug metabolizing enzymes and transports genotyping array offers the ability to determine 1,931 variants and 225 genes involved in drug metabolism and disposition. Accordingly, the study of well-known drug-metabolizing genes can be involved in the specific metabolic pathway of a drug, which is more likely to define genotype-phenotype association and thereby genotype profiles relevant to drug response that can be applied as predictive biomarkers for pharmacological treatment.

Dataset Information

Defects of CTLA-4 Are Associated with Regulatory T Cells in Myasthenia Gravis Implicated by Intravenous Immunoglobulin Therapy.

Publications

Defects of CTLA-4 Are Associated with Regulatory T Cells in Myasthenia Gravis Implicated by Intravenous Immunoglobulin Therapy.

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