Molecular analysis of T cell clonotypes in muscle-infiltrating lymphocytes from patients with human T lymphotropic virus type 1 polymyositis

Gene expression and TCR amino acid sequences selected by HLA-A02:01-restricted CTLs specific to HTLV-1 in ATL patients

Adult T-cell leukaemia/lymphoma (ATL) is an aggressive malignancy of peripheral T cells caused by human T-cell lymphotropic virus type-1 (HTLV-1). Tax is the most important regulatory protein for HTLV-1. We aimed to reveal a unique amino acid sequence (AA) of complementarity-determining region 3 (CDR3) of the T-cell receptor (TCR)β and TCRα chains of HLA-A*02:01-restricted Tax11-19 -specific cytotoxic T cells (Tax-CTLs). The gene expression profiles (GEP) of Tax-CTLs were assessed by the next-generation sequence (NGS) method with SMARTer technology. Tax-CTLs seemed to be oligoclonal, and their gene compositions were skewed. The unique motifs of 'DSWGK' in TCRα and 'LAG' in TCRβ at CDR3 were observed in almost all patients. Tax-CTL clones harbouring the 'LAG' motif with BV28 had a higher binding score than those without either of them, besides a higher binding score associated with longer survival. Tax-CTLs established from a single cell showed killing activities against Tax-peptide-pulsed HLA-A2+ T2 cell lines. GEP of Tax-CTLs revealed that genes associated with immune response activity were well preserved in long-term survivors with stable status. These methods and results can help us better understand immunity against ATL, and should contribute to future studies on the clinical application of adoptive T-cell therapies.

Human T cell lymphotropic virus type-1 associated lymphoma presenting as an intramuscular mass of the calf

Adult T cell leukemia/lymphoma (ATLL) is a mature T cell neoplasm caused by the human oncogenic retrovirus human T lymphotropic virus type-1 (HTLV-1). While several musculoskeletal manifestations have been described in ATLL, skeletal muscle involvement is unusual, with only four cases reported in the English-language literature. We present a rare case of ATLL manifesting as an intra-muscular calf mass in a 58-year-old man who immigrated to the USA from West Africa. While skeletal muscle involvement by lymphoma is uncommon, it remains important to consider within the differential diagnosis when there are suggestive imaging findings because it entails important technical biopsy considerations as well as treatment implications. This case report also raises awareness of ATLL presenting outside of typical HTLV-1 endemic areas, related to current population migration patterns. ATLL should therefore be considered in patients with appropriate risk factors.

Study of the T-cell receptor repertoire by CDR3 spectratyping

The T-cell receptor (TCR) is the key player within the so called immunological synapse and the analysis of its repertoire offers a picture of both versatility and wideness of the whole immune T-cell compartment. Among the different approaches applied to its study the so-called spectratyping identifies the pattern of the third complementarity determining region (CDR3) length distribution in each one of the beta variable (TRBV) subfamilies encoded by the corresponding genes. This technique consists in a CDR3 fragment analysis through capillary electrophoresis, performed after cell separation, RNA extraction and reverse transcriptase PCR. This review will run through the most relevant studies which have tried to dissect the TCR repertoire usage in patients with different immune-mediated and infective diseases as well as solid or haematologic malignancies.

Clinical presentation of axial myopathy in two siblings with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Background

The clinical features of myositis related with Human T-cell leukemia virus type 1 (HTLV-1) remains unclear despite epidemiological studies suggesting inflammatory myopathy associated with the virus.

Case presentation

Here, we described the clinical presentations, muscle biopsy studies and laboratory results of two siblings with HTLV-1-associated myelopathy / tropical spastic paraparesis (HAM/TSP) who were affected with lumbar lordosis. Computed tomography (CT) scans demonstrated marked paraspinal muscle atrophy in both patients. Immunohistochemical studies of biopsy tissue obtained from one of the patients revealed inflammatory change of the muscle. Upon oral prednisolone therapy, the patient showed improvement in muscle strength and serum creatine kinase (CK) level.

Conclusion

Myopathy or specifically axial myopathy should be considered as clinical symptom when treating the patients with HTLV-1 infection.

Neuroimmunological aspects of human T cell leukemia virus type 1-associated myelopathy/tropical spastic paraparesis

Human T cell leukemia virus type 1 (HTLV-1) is a human retrovirus etiologically associated with adult T cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Only approximately 0.25-4 % of infected individuals develop HAM/TSP; the majority of infected individuals remain lifelong asymptomatic carriers. Recent data suggest that immunological aspects of host-virus interactions might play an important role in the development and pathogenesis of HAM/TSP. This review outlines and discusses the current understanding, ongoing developments, and future perspectives of HAM/TSP research.

Immunopathogenesis of human T-cell leukemia virus type-1-associated myelopathy/tropical spastic paraparesis: recent perspectives

Human T-cell leukemia virus type-1 (HTLV-1) is a replication-competent human retrovirus associated with two distinct types of disease only in a minority of infected individuals: the malignancy known as adult T-cell leukemia (ATL) and a chronic inflammatory central nervous system disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic progressive myelopathy characterized by spastic paraparesis, sphincter dysfunction, and mild sensory disturbance in the lower extremities. Although the factors that cause these different manifestations of HTLV-1 infection are not fully understood, accumulating evidence from host population genetics, viral genetics, DNA expression microarrays, and assays of lymphocyte function suggests that complex virus-host interactions and the host immune response play an important role in the pathogenesis of HAM/TSP. Especially, the efficiency of an individual's cytotoxic T-cell (CTL) response to HTLV-1 limits the HTLV-1 proviral load and the risk of HAM/TSP. This paper focuses on the recent advances in HAM/TSP research with the aim to identify the precise mechanisms of disease, in order to develop effective treatment and prevention.

Pathophysiology of inflammatory and autoimmune myopathies

The main subtypes of inflammatory myopathies include dermatomyositis (DM), polymyositis (PM), necrotizing autoimmune myositis (NAM) and sporadic inclusion-body myositis (sIBM). The review provides an update on the main clinical characteristics unique to each subset, including fundamental aspects on muscle pathology helpful to assure accurate diagnosis, underlying immunopathomechanisms and therapeutic strategies. DM is a complement-mediated microangiopathy leading to destruction of capillaries, distal hypoperfusion and inflammatory cell stress on the perifascicular regions. NAM is an increasingly recognized subacute myopathy triggered by statins, viral infections, cancer or autoimmunity with macrophages as the final effector cells mediating fiber injury. PM and IBM are characterized by cytotoxic CD8-positive T cells which clonally expand in situ and invade MHC-I-expressing muscle fibers. In IBM, in addition to autoimmunity, there is vacuolization and intrafiber accumulation of degenerative and stressor molecules. Pro-inflammatory mediators, such as gamma interferon and interleukin IL1-β, seem to enhance the accumulation of stressor and amyloid-related misfolded proteins. Current therapies using various immunosuppressive and immunomodulating drugs are discussed for PM, DM and NAM, and the principles for effective treatment strategies in IBM are outlined.

Single-cell analysis of T-cell receptor repertoire of HTLV-1 Tax-specific cytotoxic T cells in allogeneic transplant recipients with adult T-cell leukemia/lymphoma

Adult T-cell leukemia (ATL) is a lymphoproliferative malignancy associated with human T-cell lymphotropic virus type 1 (HTLV-1) infection. Recently, it has been shown that allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment for ATL, and that HTLV-1 Tax-specific CD8(+) cytotoxic T cells (CTL) contribute to the graft-versus-ATL effect. In the present study, we, for the first time, analyzed the T-cell receptor (TCR) repertoire of isolated Tax(301-309) (SFHSLHLLF)-specific CTLs in HLA-A*2402(+) ATL patients before and after allo-HSCT by single-cell reverse transcription-PCR. The Tax(301-309)-specific CTLs in bone marrow and peripheral blood showed highly restricted oligoclonal diversity. In addition, a unique conserved amino acid motif of "P-D/P-R" in TCR-beta complementarity-determining region 3 in either BV7- or BV18-expressing CTLs was observed not only in all of the samples from ATL patients, but also in samples from the same patient before and after HSCT. Furthermore, the P-D/P-R motif-bearing CTL clones established from peripheral blood samples after HSCT exhibited strong killing activity against the HTLV-1-infected T cells of the patient. CTL clones were not established in vitro from samples prior to allo-HSCT. In addition, CTL clones with a strong killing activity were enriched in vivo after HSCT in the patient. Hence, Tax(301-309)-specific CTLs in ATL patients might have a preference for TCR construction and induce strong immune responses against the HTLV-1-infected T cells of patients, which contribute to the graft-versus-ATL effects after allo-HSCT. However, further analyses with a larger number of patients and more frequent sampling after allo-HSCT is required to confirm these findings.

Immunogenetics and the Pathological Mechanisms of Human T-Cell Leukemia VirusType 1- (HTLV-1-)Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

Human T-cell leukemia virus type 1 (HTLV-1) is a replication-competent human retrovirus associated with two distinct types of disease only in a minority of infected individuals: the malignancy known as adult T-cell leukemia (ATL) and a chronic inflammatory central nervous system disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the factors that cause these different manifestations of HTLV-1 infection are not fully understood, accumulating evidence suggests that complex virus-host interactions play an important role in determining the risk of HAM/TSP. This review focuses on the role of the immune response in controlling or limiting viral persistence in HAM/TSP patients, and the reason why some HTLV-1-infected people develop HAM/TSP whereas the majority remains asymptomatic carriers of the virus.

Polymyositis–dermatomyositis and infections

In genetically predisposed individuals, viruses, bacteria, or parasitic infectious agents are suspected to induce autoimmunity and/or to exacerbate the disease once the self-tolerance is broken. Although direct evidence for this association is still lacking, numerous data from animal models as well as from humans support the hypothesis of a direct contribution of pathogens to the induction of several autoimmune diseases. This review focused on the possible role of infectious agents as triggers of autoimmunity in polymyositis (PM) and dermatomyositis (DM). Epidemiological studies, clinical and experimental findings that support the hypothesis of infection-induced PM and DM are summarized and discussed. In addition, immune response abnormalities and immunosuppressive medications may be responsible for the high percentage of infectious complications in PM and DM patients. In this review, the increased risk of developing infections in these patients is also underlined and published data are reported.

Inclusion body myositis associated with human T-lymphotropic virus-type I infection: eleven patients from an endemic area in Japan

The objective of this study was to investigate the association of human T-lymphotropic virus-type I (HTLV-I) infection with sporadic inclusion body myositis in 11 patients from an endemic area in Japan. The clinical features were consistent with sporadic inclusion body myositis, and anti-HTLV-I antibodies were present in the sera of all patients. Their muscle biopsies showed the diagnostic features of inclusion body myositis, including endomysial T-cell infiltration, rimmed vacuoles, deposits of phosphorylated tau, and abnormal filaments in the nuclei and cytoplasm of the myofibers. The fibers expressed major histocompatibility complex class I antigens and were invaded by CD8 and CD4 cells. In a single human leukocyte antigen-A2-positive patient, in situ human leukocyte antigen-A*0201 / Tax11-19-pentamer staining showed pentamer-positive cells surrounding the muscle fibers. Double-immunogold silver staining and polymerase chain reaction in situ hybridization revealed that HTLV-I proviral DNA was localized on helper-inducer T cells, but not on muscle fibers. Human T-lymphotropic virus-type I proviral loads in peripheral blood mononuclear cells from each patient were similar to those in HTLV-I-associated myelopathy/tropical spastic paraparesis. This study suggests that HTLV-I infection may be one of the causes of sporadic inclusion body myositis, as has been reported in human immunodeficiency virus type-1 infection.

Ex vivo analysis of human T lymphotropic virus type 1-specific CD4+ cells by use of a major histocompatibility complex class II tetramer composed of a neurological disease-susceptibility allele and its immunodominant peptide

HLA-DRB1*0101 is associated with susceptibility to human T lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Here, we used a synthetic tetramer of DRB1*0101 and its epitope peptide to analyze HTLV-1-specific CD4(+) T cells ex vivo. The frequency of tetramer(+)CD4(+) T cells was significantly greater in patients with HAM/TSP than in healthy HTLV-1 carriers (HCs) at a given proviral load and correlated with HTLV-1 tax messenger RNA expression in HCs but not in patients with HAM/TSP. These cells displayed an early to intermediate effector memory phenotype and were preferentially infected by HTLV-1. T cell receptor gene analyses of 2 unrelated DRB1*0101-positive patients with HAM/TSP showed similar Vbeta repertoires and amino acid motifs in complementarity-determining region 3. Our data suggest that efficient clonal expansion of virus-specific CD4(+) T cells in patients with HAM/TSP does not simply reflect higher viral burden but rather reflects a rapid turnover caused by preferential infection and/or in vivo stimulation by major histocompatibility complex-peptide complexes.

Advances in the immunobiology and treatment of inflammatory myopathies

The clinical spectrum and immunopathogenesis of inflammatory myopathies are summarized with an update on possible triggering factors, cell degeneration, and emerging new therapies.

Histone deacetylase mediated transcriptional activation reduces proviral loads in HTLV-1 associated myelopathy/tropical spastic paraparesis patients

Epigenetic modifications of chromatin may play a role in maintaining viral latency and thus persistence of the human T-lymphotropic virus type 1 (HTLV-1), which is responsible for HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). A major determinant of disease progression is increased peripheral blood proviral load (PVL), possibly via the accumulation of infected cells in the central nervous system (CNS) creating a damaging inflammatory response. Current therapeutic approaches that focus on reducing either cell proliferation, viral replication, or tissue invasion are still unsatisfactory. Contrasting with these inhibitory strategies, we evaluated the efficacy of a novel approach aimed, paradoxically, at activating viral gene expression to expose virus-positive cells to the host immune response. We used valproate (VPA), a histone deacetylase inhibitor that has been used for decades as a chronic, safe treatment for epileptic disorders. Based on in vitro and in vivo data, we provide evidence that transient activation of the latent viral reservoir causes its collapse, a process that may alleviate the condition of HAM/TSP. This represents the first such approach to treating HAM/TSP, using gene activation therapy to tilt the host-pathogen balance in favor of an existing antiviral response. This trial is registered at http://clinicaltrials.gov/as no. NCT00519181.

Inclusion body myositis with human immunodeficiency virus infection: four cases with clonal expansion of viral-specific T cells

OBJECTIVE

Sporadic inclusion body myositis (sIBM), a common adult-onset myositis, is characterized by an antigen-driven inflammatory response and vacuolar degeneration. The cause is unknown. We report the association of sIBM with human immunodeficiency virus (HIV) infection and explore the clonality and viral specificity of the autoinvasive T cells.

METHODS

Clinicopathological studies in four HIV-infected patients with IBM were performed. The clonal restriction of endomysial T cells, compared with peripheral blood, was examined by spectratyping. Immunohistochemical studies using human leukocyte antigen-A* 0201-gag tetramers and the most dominant Vb families were performed in serial muscle biopsy sections to examine whether clonally expanded autoinvasive T cells are viral specific and invade muscle fibers expressing the allele-specific monomorphic major histocompatibility complex class I antigen.

RESULTS

Prominent clonal restriction of certain Vb families was noted among the endomysial T cells with evidence of in situ expansion. Approximately 10% of the autoinvasive CD8(+) cells were human leukocyte antigen-A* 0201-HIV-gag specific and invaded muscle fibers expressing the specific human leukocyte antigen-A* 0201 allele. These cells belonged to restricted Vb families. The HIV gag antigen was present on several endomysial macrophages but not within the muscle fibers.

INTERPRETATION

sIBM develops in patients who harbor HIV. In HIV-IBM, a subset of CD8(+) T cells surrounding muscle fibers are viral specific and may play a role in the disease mechanism by cross-reacting with antigens on the surface of muscle fibers. This study provides a paradigm that a chronic viral infection in genetically susceptible individuals can trigger viral specific T cell clones that persist within the muscle and lead to development of sIBM.

Clinical symptoms and the odds of human T-cell lymphotropic virus type 1-associated myelopathy/ tropical spastic paraparesis (HAM/TSP) in healthy virus carriers: application of best-fit logistic regression equation based on host genotype, age, and provirus load

The authors have previously developed a logistic regression equation to predict the odds that a human T-cell lymphotropic virus type 1 (HTLV-1)-infected individual of specified genotype, age, and provirus load has HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in southern Japan. This study evaluated whether this equation is useful predictor for monitoring asymptomatic HTLV-1-seropositive carriers (HCs) in the same population. The authors genotyped 181 HCs for each HAM/TSP-associated gene (tumor necrosis factor [TNF]-alpha-863A/C, stromal cell-derived factor 1 (SDF-1) +801G/A, human leukocyte antigen [HLA]-A*02, HLA-Cw*08, HTLV-1 tax subgroup) and measured HTLV-1 provirus load in peripheral blood mononuclear cells using real-time polymerase chain reaction (PCR). Finally, the odds of HAM/TSP for each subject were calculated by using the equation and compared the results with clinical symptoms and laboratory findings. Although no clear difference was seen between the odds of HAM/TSP and either sex, family history of HAM/TSP or adult T-cell lenkemia (ATL), history of blood transfusion, it was found that brisk patellar deep tendon reflexes, which suggest latent central nervous system compromise, and flower cell-like abnormal lymphocytes, which is the morphological characteristic of ATL cells, were associated with a higher odds of HAM/TSP. The best-fit logistic regression equation may be useful for detecting subclinical abnormalities in HCs in southern Japan.

Sporadic inclusion body myositis--diagnosis, pathogenesis and therapeutic strategies

Sporadic inclusion body myositis (sIBM) presents with a characteristic clinical phenotype of slow-onset weakness and atrophy, affecting proximal and distal limb muscles and facial and pharyngeal muscles. Histologically, sIBM is characterized by chronic myopathic features, lymphocytic infiltrates invading non-vacuolated fibers, vacuolar degeneration, and accumulation of amyloid-related proteins. The cause of sIBM is unclear, but two processes-one autoimmune and the other degenerative-appear to occur in parallel. In contrast to dystrophies, in sIBM the autoinvasive CD8(+) T cells are cytotoxic and antigen-driven, invading muscle fibers expressing major histocompatibility complex class I antigen and costimulatory molecules. The concurrent degenerative features include vacuolization, filamentous inclusions and intracellular accumulations of amyloid-beta-related molecules. Although viruses have not been amplified from the muscle fibers, at least 12 cases of sIBM have been seen in association with retroviral infections, indicating that a chronic persistent viral infection might be a potential triggering factor. Emerging data imply that continuous upregulation of cytokines and major histocompatibility complex class I on the muscle fibers causes an endoplasmic reticulum stress response, resulting in intracellular accumulation of misfolded glycoproteins and activation of the transcription factor NFkappaB, leading to further cytokine activation. In spite of the brisk, antigen-driven T-cell infiltrates, sIBM does not respond to immunotherapies. New therapies using monoclonal antibodies against lymphocyte signaling pathways might prove helpful in arresting disease progression.

Flow cytometry evaluation of the T-cell receptor Vbeta repertoire among human T-cell lymphotropic virus type-1 (HTLV-1) infected individuals: effect of interferon alpha therapy in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Human T-cell lymphotropic virus type-1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is chronic inflammatory disease of the spinal cord characterized by perivascular lymphocytic cuffing and parenchymal lymphocytic infiltration. In this study using flow cytometry, we have investigated the T-cell receptor (TCR) Vbeta repertoire of peripheral blood T lymphocytes in 8 HAM/TSP patients, 10 HTLV-1 infected healthy carriers, and 11 uninfected healthy controls to determine if there is a biased usage of TCR Vbeta. We found that TCR Vbeta7.2 was under-utilized and Vbeta12 was over-utilized in CD4+ T cells of HTLV-1 infected individuals compared with healthy uninfected controls, whereas there were no such differences in CD8+ T cells. Comparison of Vbeta repertoire changes before and after interferon-alpha (IFN-alpha) treatment for HAM/TSP revealed that one out of five patients showed dramatic decrease of specific Vbeta in CD8+ T cells. Our results suggest that dominant Vbeta subpopulations in CD4+ T cells evolved associated with chronic HTLV-1 infection, and IFN-alpha treatment for HAM/TSP does not induce a specific pattern of TCR Vbeta changes.

Skeletal muscle involvement in human immunodeficiency virus (HIV)-infected patients in the era of highly active antiretroviral therapy (HAART)

Skeletal muscle involvement can occur at all stages of human immunodeficiency virus (HIV) infection, and may represent the first manifestation of the disease. Myopathies in HIV-infected patients are classified as follows: (1) HIV-associated myopathies and related conditions, including HIV polymyositis, inclusion-body myositis, nemaline myopathy, diffuse infiltrative lymphocytosis syndrome (DILS), HIV-wasting syndrome, vasculitic processes, myasthenic syndromes, and chronic fatigue; (2) muscle complications of antiretroviral therapy, including zidovudine and toxic mitochondrial myopathies related to other nucleoside-analogue reverse-transcriptase inhibitors (NRTIs), HIV-associated lipodystrophy syndrome, and immune restoration syndrome related to highly active antiretroviral therapy (HAART); (3) opportunistic infections and tumor infiltrations of skeletal muscle; and (4) rhabdomyolysis. Introduction of HAART has dramatically modified the natural history of HIV disease by controlling viral replication, but, in turn, lengthening of the survival of HIV-infected individuals has been associated with an increasing prevalence of iatrogenic conditions.

Substantial proportions of identical β-chain T-cell receptor transcripts are present in epithelial ovarian carcinoma tumors

To determine whether clonally expanded T cells are present in tumor specimens from patients with epithelial ovarian carcinoma (EOC) we amplified by the non-palindromic adaptor PCR (NPA-PCR) or by Vbeta-specific PCR beta-chain T-cell receptor (TCR) transcripts from these tumor specimens. The amplified transcripts were cloned and sequenced. Sequence analysis revealed the presence of substantial proportions of multiple identical copies of beta-chain TCR transcripts, suggesting the presence of clonal expansions of T cells in these patients, which were statistically significant by the binomial distribution in seven of nine patients. Independent amplification in separate experiments of beta-chain TCR transcripts from one patient by either NPA-PCR or by Vbeta-specific PCR, followed by cloning and sequencing, revealed identical clonal expansions irrespectively of the amplification method used. Multiple identical copies of beta-chain TCR transcripts can be derived only by specific antigen-driven proliferation and clonal expansion of the T-cell clones which recognize these antigens. Because of the very large size of the TCR repertoire, the probability of finding by chance multiple identical copies of these transcripts within an independent sample of T cells is negligible. These results demonstrate that T cells infiltrating solid tumor specimens or malignant ascites of patients with EOC contain monoclonal/oligoclonal populations of T cells.

TCR Analyses

T-cells play a crucial role in immune surveillance against transformed cells and intracellular infections; they are involved in auto-immune reactions. They recognize their targets, i.e. MHC / peptide complexes, trough the T-cell receptor. TCR usage determines the molecular interaction of the immune system with biologically relevant MHC/peptide molecules. The TCR coding genes (variable, diversity and junctional) determine the molecular composition of the TCR alpha and beta heterodimer. The random association of the VDJ genes constitutes the complementarity determining region 3 (CDR3) responsible for antigen recognition and TCR specificity. The molecular composition of a T-cell population can be objectively defined by measuring the CDR3 region. Qualitative and quantitative comparisons of the TCR composition in different anatomic compartments, or longitudinally over time, allow to asses the entire TCR repertoire. This methodology can be supplemented with functional T-cell based assays and aids to objectively describe any alteration in the T-cell pool. TCR CDR3 analysis is useful in immunomonitoring, e.g. examining patients after BMT or solid organ transplantation, patients with HAART therapy, or patients receiving molecularly defined vaccines.

Direct evidence for a chronic CD8+-T-cell-mediated immune reaction to tax within the muscle of a human T-cell leukemia/lymphoma virus type 1-infected patient with sporadic inclusion body myositis

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) infection can lead to the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), concomitantly with or without other inflammatory disorders such as myositis. These pathologies are considered immune-mediated diseases, and it is assumed that migration within tissues of both HTLV-1-infected CD4(+) T cells and anti-HTLV-1 cytotoxic T cells represents a pivotal event. However, although HTLV-1-infected T cells were found in inflamed lesions, the antigenic specificity of coinfiltrated CD8(+) T cells remains to be determined. In this study, we performed both ex vivo and in situ analyses using muscle biopsies obtained from an HTLV-1-infected patient with HAM/TSP and sporadic inclusion body myositis. We found that both HTLV-1-infected CD4(+) T cells and CD8(+) T cells directed to the dominant Tax antigen can be amplified from muscle cell cultures. Moreover, we were able to detect in two successive muscle biopsies both tax mRNA-positive mononuclear cells and T cells recognized by the Tax11-19/HLA-A*02 tetramer and positive for perforin. These findings provide the first direct demonstration that anti-Tax cytotoxic T cells are chronically recruited within inflamed tissues of an HTLV-1 infected patient, which validates the cytotoxic immune reaction model for the pathogenesis of HTLV-1-associated inflammatory disease.

The glycoprotein of a fish rhabdovirus profiles the virus-specific T-cell repertoire in rainbow trout

T-cell responses to viruses are still poorly investigated in lower vertebrates. In rainbow trout, a specific clonal expansion of T cells in response to infection with viral haemorrhagic septicaemia virus (VHSV) was recently identified. Expanded T-cell clones expressed a unique 8 aa Vβ4-Jβ1 junction (SSGDSYSE) in different individuals, reminiscent of a typical public response. To get further insight into the nature of this response the modifications of the T-cell repertoire following immunization with plasmid expressing the VHSV external glycoprotein (G), which is the only protein involved in protective immunity, was analysed. After G-based DNA immunization, CDR3-length spectratypes were skewed for several Vβ-Jβ combinations, including Vβ4-Jβ1. In Vβ4-Jβ1, biases consisted of 6 and 8 aa junctions that were detected from day 52, and were still present 3 months after DNA immunization. Sequence analysis of the Vβ4-Jβ1 junctions showed that the 8 aa junction (SSGDSYSE) was clearly expanded, indicating that viral G protein was probably the target of the anti-VHSV public response. Additional 6 and 8 aa Vβ4-Jβ1 junctions were also expanded in G-DNA-vaccinated fish, showing that significant clonotypic diversity was selected in response to the plasmid-delivered G protein. This higher clonotypic diversity may be related to the demonstrated higher efficiency of G-based DNA vaccines over whole virus immunization. The use of infectious hematopietic necrosis virus (IHNV) recombinant viruses, expressing the VHSV G protein, further substantiated the VHSV G-protein specificity of the 8 aa Vβ4-Jβ1 response and designated the 6 aa Vβ4-Jβ1 response as potentially directed to a T-cell epitope common to VHSV and IHNV.

Oligoclonal expansion of circulating and tissue-infiltrating CD8+ T cells with killer/effector phenotypes in juvenile dermatomyositis syndrome

Although triggering by infectious agents and abnormal immune responses may play some role in the pathogenesis of juvenile dermatomyositis syndrome (JDMS), the precise mechanism of muscle destruction and vascular damage is largely unknown. In this study, we tried to elucidate the role of cytotoxic T cells in two patients with JDMS, who were diagnosed based on the characteristic symptoms, laboratory data, MRI findings and electromyographic patterns. Peripheral blood T cell phenotypes were determined by flow cytometry, using mAbs against specific T cell receptor (TCR) Vbetas. Complementarity-determining region3 (CDR3) size analysis was performed by gene scanning of CDR3 polymerase chain reaction (PCR) amplification products specific for each Vbeta. Subsequently, CDR3 nucleotide sequences were obtained after cloning of the predominant products. The distribution of lymphocytes infiltrating the muscle tissue was analysed by immunohistochemistry. In both patients examined, a unique combination of TCR Vbeta repertoires was increased within the CD8+ T cells. These subpopulations expressed a characteristic phenotype, indicating that they are memory/effector T cells with killer functions. At the same time, immunohistological and molecular biological examinations of the biopsied muscle samples revealed that identical CD8+ T cell clones with identical phenotypes/TCR Vbeta infiltrated within the inflammatory tissue, in particular around vessels. These findings indicate that oligoclonal expansion of CD8+ T cells plays a central role in the pathogenesis of muscle injury in the juvenile form of dermatomyositis syndrome and may provide a useful clinical parameter of disease activity and responsiveness to anti-inflammatory therapy.