T cell receptor V genes in multiple sclerosis: increased use of TCRAV8 and TCRBV5 in MBP-specific clones

T Cell Receptor Sequences Amplified during Severe COVID-19 and Multisystem Inflammatory Syndrome in Children Mimic SARS-CoV-2, Its Bacterial Co-Infections and Host Autoantigens

Published hypervariable region V-beta T cell receptor (TCR) sequences were collected from people with severe COVID-19 characterized by having various autoimmune complications, including blood coagulopathies and cardiac autoimmunity, as well as from patients diagnosed with the Kawasaki disease (KD)-like multisystem inflammatory syndrome in children (MIS-C). These were compared with comparable published v-beta TCR sequences from people diagnosed with KD and from healthy individuals. Since TCR V-beta sequences are supposed to be complementary to antigens that induce clonal expansion, it was surprising that only a quarter of the TCR sequences derived from severe COVID-19 and MIS-C patients mimicked SARS-CoV-2 proteins. Thirty percent of the KD-derived TCR mimicked coronaviruses other than SARS-CoV-2. In contrast, only three percent of the TCR sequences from healthy individuals and those diagnosed with autoimmune myocarditis displayed similarities to any coronavirus. In each disease, significant increases were found in the amount of TCRs from healthy individuals mimicking specific bacterial co-infections (especially Enterococcus faecium, Staphylococcal and Streptococcal antigens) and host autoantigens targeted by autoimmune diseases (especially myosin, collagen, phospholipid-associated proteins, and blood coagulation proteins). Theoretical explanations for these surprising observations and implications to unravel the causes of autoimmune diseases are explored.

Infiltrating T-lymphocyte Receptor Vβ Gene Family Utilization in Autoimmune Thyroid Disease

The expression of T-cell antigen receptor (TCR) Vβ genes in autoimmune thyroid diseases (AITDs) was investigated. RNA was extracted from the thyroid tissue of 23 patients with early-stage Graves' disease, 19 patients with late-stage Graves' disease and 20 patients with Hashimoto's disease. Peripheral blood lymphocytes from patients and 20 normal subjects (controls) were analysed in parallel. AITD was found to be associated with diminished TCR Vβ gene family utilization. In addition, AITDs appeared to select for specific TCR Vβ families. The Vβ3, Vβ5 and Vβ8 families were expressed more frequently in thyroid-infiltrating T-lymphocytes of early-stage Graves' disease than other Vβ gene families. Selective expression was not observed in infiltrating T-lymphocytes obtained from thyroid tissue of patients with late-stage Graves' disease or Hashimoto's disease. Preferentially expressed TCR Vβ gene families may be useful as molecular targets for targeted immunotherapy of AITDs.

Emerging immunopharmacological targets in multiple sclerosis

Inflammatory demyelination of the central nervous system (CNS) is the hallmark of multiple sclerosis (MS), a chronic debilitating disease that affects more than 2.5 million individuals worldwide. It has been widely accepted, although not proven, that the major pathogenic mechanism of MS involves myelin-reactive T cell activation in the periphery and migration into the CNS, which subsequently triggers an inflammatory cascade that leads to demyelination and axonal damage. Virtually all MS medications now in use target the immune system and prevent tissue damage by modulating neuroinflammatory processes. Although current therapies such as commonly prescribed disease-modifying medications decrease the relapse rate in relapsing-remitting MS (RRMS), the prevention of long-term accumulation of deficits remains a challenge. Medications used for progressive forms of MS also have limited efficacy. The need for therapies that are effective against disease progression continues to drive the search for novel pharmacological targets. In recent years, due to a better understanding of MS immunopathogenesis, new approaches have been introduced that more specifically target autoreactive immune cells and their products, thus increasing specificity and efficacy, while reducing potential side effects such as global immunosuppression. In this review we describe several immunopharmacological targets that are currently being explored for MS therapy.

Clone clusters in autoreactive CD4 T-cell lines from probable multiple sclerosis patients form disease-characteristic signatures

We developed a method for selectively propagating disease-related autoreactive T-cell lines (auTCLs) based on their increased resistance to apoptosis. The generated auTCLs homogeneously co-express CD45RO and CD49a, adhere strongly to extracellular matrix proteins and express high interleukin-17 (IL-17) messenger RNA levels, resembling a T-cell subset proposed to transmigrate into tissues and induce systemic and local inflammation in rheumatoid arthritis. The combinations of T-cell oligoclones that comprise probable multiple sclerosis (pMS) disease-related lines use a unique portfolio of T-cell receptor beta-chain variable allele (BV genes) combinations forming 'disease-specific cluster patterns'. The auTCL derived from different patients and from different myelin epitopes display striking similarities in BV gene allele clusters and are derived primarily from a disease-prone hotspot residing in the BV gene locus between Vbeta6 and Vbeta9. Conversely, healthy subject TCLs use different BV gene allele sets, forming 'healthy responder usage formats'. These formats were absent from the pMS patient V-beta gene allele combinations evaluated in this study. Hierarchical clustering of the BV gene combinations, distinguish three pMS auTCL groups, implying existence of up to three disease-related immune response patterns. These subgroup patterns may reflect different disease subclasses or alternatively they may suggest immune reactivity to different aetiological agents. Analyses of clonal-clustering patterns may potentially aid in subclassification of MS or in characterizing aetiological agents of this disease.

Congruent Effects of Estrogen and T-Cell Receptor Peptide Therapy on Regulatory T Cells in EAE and MS

Both estrogen (E2) and T-cell receptor (TCR) peptides have beneficial effects on the clinical course of experimental autoimmune encephalomyelitis (EAE) and possibly multiple sclerosis (MS) that involve distinct but congruent mechanisms. Of interest, these two approaches share an ability to enhance expression of the FoxP3 gene and associated activity of regulatory T (Treg) cells. E2 increases the number and activity of FoxP3(+) T cells through Esr-1 signaling during TCR activation of CD4(+)CD25(-) T cells. In contrast, TCR peptide therapy appears to increase the frequency of regulatory FoxP3(+) T cells specific for self-TCR determinants expressed by targeted pathogenic T cells. The combined effects on Treg expansion and activation induced by these distinct immunoregulatory approaches may account for their potent effects on clinical EAE and argue for a similar combined therapeutic approach for MS.

Long-term human coronavirus-myelin cross-reactive T-cell clones derived from multiple sclerosis patients

Autoimmune reactions associated with MS involve genetic and environmental factors. Because murine coronaviruses induce an MS-like disease, the human coronaviruses (HCoV) are attractive candidates as environmental factors involved in a demyelinating pathology. We previously reported the isolation of HCoV-229E/myelin basic protein (MBP) cross-reactive T-cell lines (TCL) in MS patients. To investigate antigenic cross-reactivity at the molecular level, 155 long-term T-cell clones (TCC) were derived from 32 MS patients by in vitro selection with MBP, proteolipid protein (PLP) or HCoV (strains 229E and OC43). Overall, 114 TCC were virus-specific, 31 were specific for myelin Ag and 10 other were HCoV/myelin cross-reactive. Twenty-eight virus-specific TCC and 7 myelin-specific TCC were obtained from six healthy donors. RACE RT-PCR amplification of the Vbeta chains of five of ten the cross-reactive TCC confirmed clonality and sequencing identified the CDR3 region associated with cross-reactivity. Our findings have promising implications in the investigation of the role of molecular mimicry between coronaviruses and myelin in MS as a mechanism related to disease initiation or relapses.

Expression of the T cell receptor Vbeta repertoire in a human T cell resistant to asbestos-induced apoptosis and peripheral blood T cells from patients with silica and asbestos-related diseases

To explore the effects of asbestos and silica on the human immune system, an experimental model of low-dose and long-term exposure was established using a human HTLV-1-immortalized polyclonal T cell line, MT-2 (MT-2Org). MT-2 cells were continuously exposed to asbestos at a concentration (10 microg/ml) which does not induce complete cell death during short-term exposure. After acquiring resistance to CB-induced apoptosis (designated MT-2Rst), an immunological comparison was made between the MT-2Org and MT-2Rst lines in terms of T cell receptor-Vbeta (TcR-Vbeta) expression. MT-2Rst cells showed excess expression of various TcR-Vbeta, although TcR-Vbeta-overpresenting cells were characterized as undergoing apoptosis due to first contact with CB. Patients with asbestos-related diseases (ARD), such as asbestosis and malignant mesothelioma, were compared with silicosis (SIL) patients as a disease control and with healthy donors (HD). SIL and ARD not only differed in their causative materials, silica and asbestos as mineral silicates, but also in terms of complications; autoimmune disorders in SIL and tumors in ARD. ARD patients showed a restricted overpresentation of TcR-Vbeta without clonal expansion, whereas SIL patients revealed significant overpresentation of TcR-Vbeta 7.2. These experimental and clinical analyses indicate the superantigenic and dysregulation of autoimmunity-inducing effects of asbestos and silica, respectively.

A 40-cM region on chromosome 14 plays a critical role in the development of virus persistence, demyelination, brain pathology and neurologic deficits in a murine viral model of multiple sclerosis

Theiler virus persists and induces immune-mediated demyelination in susceptible mice and serves as a model of multiple sclerosis. Previously, we identified 4 markers--D14Mit54, D14Mit60, D14Mit61, and D14Mit90--in a 40-cM region of chromosome 14 that are associated with demyelination in a cross between susceptible DBA/2 and resistant B10.D2 mice. We generated congenic-inbred mice to examine the contribution of this 40-cM region to disease. DBA Chr.14B10 mice, containing the chromosomal segment marked by the microsatellite polymorphisms, developed less spinal cord demyelination than did DBA/2 mice. More demyelination was found in the reciprocal congenic mouse B10.D2 Chr.14D2 than in the B10.D2 strain. Introduction of the DBA/2 chromosomal region onto the B10.D2 genetic background resulted in more severe disease in the striatum and cortex relative to B10.D2 mice. The importance of the marked region of chromosome 14 is indicated by the decrease in neurological performance using the Rotarod test during chronic disease in B10.D2 Chr.14D2 mice in comparison to B10.D2 mice. Viral replication was increased in B10.D2 Chr.14D2 mice as determined by quantitative real-time RT-PCR. These results indicate that the 40-cM region on chromosome 14 of DBA/2 mice contributes to viral persistence, subsequent demyelination, and loss of neurological function.

Complementarity-determining region 3 spectratyping analysis of the TCR repertoire in multiple sclerosis

Multiple sclerosis (MS) is considered to be an autoimmune disease mediated by T cells reactive with Ags in the CNS. Therefore, it has been postulated that neuroantigen-reactive T cells bearing particular types of TCRs are expanded clonally during the course of the disease. However, there is a controversy with regard to the TCR usage by T cells associated with the development of MS. By the use of complementarity-determining region 3 spectratyping analysis that is shown to be a useful tool for identification of pathogenic TCR in autoimmune disease models, we tried to demonstrate that spectratype was T cells bearing particular types of TCR are activated in MS patients. Consequently, it was found that Vbeta5.2 were often oligoclonally expanded in peripheral blood of MS patients, but not of healthy subjects. Sequence analysis of the complementarity-determining region 3 region of spectratype-derived TCR clones revealed that the predominant TCR clone was different from patient to patient, but that similar results were obtained in a patient examined at different time points. More importantly, examination of cerebrospinal fluid T cells and longitudinal studies of PBLs from selected patients revealed that Vbeta5.2 expansion was detectable in the majority of patients examined. These findings suggest that Vbeta5.2 spectratype expansion is associated with the development of MS and that TCR-based immunotherapy can be applicable to MS patients if the TCR activation pattern of each patient is determined at different stages of the disease.

Antibody-mediated suppression of Vbeta5.2/5.3(+) T cells in multiple sclerosis: results from an MRI-monitored phase II clinical trial

The objective of this study was to evaluate the safety and efficacy of the humanized antibody ATM-027 in a baseline versus treatment magnetic resonance imaging-monitored study. Expansion of Vbeta5.2/5.3(+) T cells has been demonstrated in the peripheral blood, cerebrospinal fluid, and brain lesions of MS patients. In a phase I study, ATM-027 depleted these cells in peripheral blood and, in parallel, T-cell MBP reactivity and IFN-gamma expression were reduced. We studied 59 patients with relapsing-remitting MS (47 on ATM-027 and 12 on placebo) stratified for HLA-DR2 status. Monthly intravenous injections were given for 6 months. Individual dose titration was employed to obtain depletion of the target T-cell level and downregulation of antigen receptor density as monitored by flow cytometry. Five monthly magnetic resonance imaging scans were performed before treatment to establish baseline activity, six during treatment, and three during follow-up. Additional immunological assessments were performed to elucidate the mechanism of action of ATM-027. The treatment was safe and well tolerated, inducing consistent suppression of the target cell population. During run-in, active lesions were found in 78.7% (37/47) of patients treated with ATM-027. During treatment, the median number of lesions was reduced by 33% (p = 0.13) independent of DR2 status. The corresponding volume of enhancement was 221 mm(3) at baseline, with a reduction of 10% during treatment. Decreased numbers of cells expressing interferon-gamma messenger RNA, and decreased T-cell reactivity to several myelin antigens were found in ATM-027 treated patients. In conclusion, consistent suppression of Vbeta 5.2/5.3(+) T cells was achieved. However, the effect size on magnetic resonance imaging was considerably less than the targeted 60%.

T-cell receptor bias in patients with allergic bronchopulmonary aspergillosis

CD4(+) Th2 helper cell mediated immune responses have been shown to play a crucial role in the pathogenesis of ABPA. HLA and TCR are the candidate genes, which can influence the specificity of these responses. We have previously established a strong association of HLA DR2/5 in ABPA susceptibility. The study was designed to determine whether allergen specific T cell express a limited usage of T cell receptor (TCR) Vbeta gene repertoire in ABPA and to find an association of susceptible HLA-DR determinants with the identified TCR gene segments. TCR Vbeta typing was performed on antigen specific T cell lines from 14 ABPA and 12 nonABPA patients. The majority of ABPA patients (86%) expressed allergen specific T cells with Vbeta13 genes indicating its role in susceptibility, whereas in nonABPA controls, Vbeta1 genes T cell repertoires were predominantly expressed. The unrestricted pattern of Vbeta gene amplification seen before antigen stimulation suggests an oligoclonal expansion of a specific T cell population in response to the allergen Asp f 1 in ABPA and nonABPA patients. The increased usage of Vbeta13 in ABPA and Vbeta1 in nonABPA indicates their importance in susceptibility and resistance, respectively.

Multiple sclerosis retrovirus particles and recombinant envelope trigger an abnormal immune response in vitro, by inducing polyclonal Vbeta16 T-lymphocyte activation

A retroviral element (MSRV) defining a family of genetically inherited endogenous retroviruses (HERV-W) has recently been characterized in cell cultures from patients with multiple sclerosis (MS). To address the possible relationship with MS, direct detection of circulating virion RNA was proposed but revealed technically difficult to perform in standardized conditions, in the face of multiple endogenous HERV-W copies. A parallel approach has evaluated MSRV potential pathogenicity in relation to characteristic features of multiple sclerosis, in particular, T-lymphocyte-mediated immunopathology. We report here that MSRV particles induce T-lymphocyte response with a bias in the Vbeta16 chain usage in surface receptor, whatever the HLA DR of the donor. A recombinant MSRV envelope-but not core-protein reproduced similar nonconventional activation. Molecular analysis of Vbeta CDR3 showed that Vbeta16 expansions are polyclonal. Our results thus provide evidence that MSRV envelope protein can trigger an abnormal immune response with similar characteristics to that of superantigens.

TCR peptide therapy in human autoimmune diseases

Inflammatory Th1 cells reacting to tissue/myelin derived antigens likely contribute to the pathogenesis of diseases such as multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. One regulatory mechanism that may be useful for treating autoimmune diseases involves an innate second set of Th2 cells specific for portions of the T cell receptor of clonally expanded pathogenic Th1 cells. These Th2 cells are programmed to respond to internally modified V region peptides from the T cell receptor (TCR) that are expressed on the Th1 cell surface in association with major histocompatibility molecules. Once the regulatory Th2 cells are specifically activated, they may inhibit inflammatory Th1 cells through a non-specific bystander mechanism. A variety of strategies have been used by us to identify candidate disease-associated TCR V genes present on pathogenic Th1 cells, including BV5S2, BV6S5, and BV13SI in MS, BV3, BV14, and BV17 in RA, and BV3 and BV13S1 in psoriasis. TCR peptides corresponding to the mid region of these BV genes were found to be consistently immunogenic in vivo when administered either i.d. in saline or i.m. in incomplete Freund's adjuvant (IFA). In MS patients, repeated injection of low doses of peptides (100-300 microg) significantly boosted the number of TCR-reactive Th2 cells. These activated cells secreted cytokines, including IL-10, that are known to inhibit inflammatory Th1 cells. Cytokine release could also be induced in TCR-reactive Th2 cells by direct cell-cell contact with Th1 cells expressing the target V gene. These findings indicate the potential of regulatory Th2 cells to inhibit not only the target Th1 cells, but also bystander Th1 cells expressing different V genes specific for other autoantigens. TCR peptide vaccines have been used in our studies to treat a total of 171 MS patients (6 trials), 484 RA patients (7 trials), and 177 psoriasis patients (2 trials). Based on this experience in 824 patients with autoimmune diseases, TCR peptide vaccination is safe and well tolerated, and can produce significant clinical improvement in a subset of patients that respond to immunization. TCR peptide vaccination represents a promising approach that is well-suited for treating complex autoimmune diseases.

Clonal expansion of infiltrating T cells in the spinal cords of SJL/J mice infected with Theiler's virus

Intracerebral infection of susceptible mice with Theiler's murine encephalomyelitis virus results in immune-mediated inflammatory demyelination in the white matter and consequent clinical symptoms. This system has been utilized as an important virus model for human multiple sclerosis. Although the potential involvement of virus-specific Th cells has been studied extensively, very little is known about the nature of T cells infiltrating the CNS during viral infection and their role in the development of demyelinating disease. In this study, the clonal nature of T cells in the spinal cord during the disease course was analyzed using size spectratyping and sequencing of the TCR beta-chain CDR3 region. These studies clearly indicate that T cells are clonally expanded in the CNS after viral infection, although the overall TCR repertoire appears to be diverse. The clonal expansion appears to be Ag-driven in that it includes Th cells specific for known viral epitopes. Interestingly, such restricted accumulation of T cells was not detectable in the infiltrates of mice with proteolipid protein peptide-induced experimental autoimmune encephalomyelitis. The initial T cell repertoire (7-9 days postinfection) seems to be more diverse than that observed in the later stage (65 days) of virally induced demyelination, despite the more restricted utilization of Vbeta subfamilies. These results strongly suggest continuous stimulation and clonal expansion of virus-specific T cells in the CNS of Theiler's murine encephalomyelitis virus-infected mice during the entire course of demyelinating disease.