Direct visualization of antigen-specific T cells: HTLV-1 Tax11-19- specific CD8(+) T cells are activated in peripheral blood and accumulate in cerebrospinal fluid from HAM/TSP patients

Pathway-based prediction of the therapeutic effects and mode of action of custom-made multiherbal medicines

Multiherbal medicines are traditionally used as personalized medicines with custom combinations of crude drugs; however, the mechanisms of multiherbal medicines are unclear. In this study, we developed a novel pathway-based method to predict therapeutic effects and the mode of action of custom-made multiherbal medicines using machine learning. This method considers disease-related pathways as therapeutic targets and evaluates the comprehensive influence of constituent compounds on their potential target proteins in the disease-related pathways. Our proposed method enabled us to comprehensively predict new indications of 194 Kampo medicines for 87 diseases. Using Kampo-induced transcriptomic data, we demonstrated that Kampo constituent compounds stimulated the disease-related proteins and a customized Kampo formula enhanced the efficacy compared with an existing Kampo formula. The proposed method will be useful for discovering effective Kampo medicines and optimizing custom-made multiherbal medicines in practice.

Novel insights into human T-lymphotropic virus type-1 (HTLV-1) pathogenesis-host interactions in the manifestation of HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus type-1 (HTLV-1) was the first discovered human oncogenic retrovirus, the etiological agent of two serious diseases have been identified as adult T-cell leukaemia/lymphoma malignancy and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a debilitating chronic neuro-myelopathy. Despite more than 40 years of molecular, histopathological and immunological studies on HTLV-1-associated diseases, the virulence and pathogenicity of this virus are yet to be clarified. The reason why the majority of HTLV-1-infected individuals (∼95%) remain asymptomatic carriers is still unclear. The deterioration of the immune system towards oncogenicity and autoimmunity makes HTLV-1 a natural probe for the study of malignancy and neuro-inflammatory diseases. Additionally, its slow worldwide spreading has prompted public health authorities and researchers, as urged by the WHO, to focus on eradicating HTLV-1. In contrast, neither an effective therapy nor a protective vaccine has been introduced. This comprehensive review focused on the most relevant studies of the neuro-inflammatory propensity of HTLV-1-induced HAM/TSP. Such an emphasis on the virus-host interactions in the HAM/TSP pathogenesis will be critically discussed epigenetically. The findings may shed light on future research venues in designing and developing proper HTLV-1 therapeutics.

HLA-A*24 Increases the Risk of HTLV-1-Associated Myelopathy despite Reducing HTLV-1 Proviral Load

Increased human T-cell leukemia virus type 1 (HTLV-1) proviral load (PVL) is a significant risk factor for HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). There is controversy surrounding whether HTLV-1-specific cytotoxic T lymphocytes (CTLs) are beneficial or harmful to HAM/TSP patients. Recently, HTLV-1 Tax 301-309 has been identified as an immunodominant epitope restricted to HLA-A*2402. We investigated whether HLA-A*24 reduces HTLV-1 PVL and the risk of HAM/TSP using blood samples from 152 HAM/TSP patients and 155 asymptomatic HTLV-1 carriers. The allele frequency of HLA-A*24 was higher in HAM/TSP patients than in asymptomatic HTLV-1 carriers (72.4% vs. 58.7%, odds ratio 1.84), and HLA-A*24-positive patients showed a 42% reduction in HTLV-1 PVL compared to negative patients. Furthermore, the PVL negatively correlated with the frequency of Tax 301-309-specific CTLs. These findings are opposite to the effects of HLA-A*02, which reduces HTLV-1 PVL and the risk of HAM/TSP. Therefore, we compared the functions of CTLs specific to Tax 11-19 or Tax 301-309, which are immunodominant epitopes restricted to HLA-A*0201 or HLA-A*2402, respectively. The maximum responses of these CTLs were not different in the production of IFN-γ and MIP-1β or in the expression of CD107a-a marker for the degranulation of cytotoxic molecules. However, Tax 301-309-specific CTLs demonstrated 50-fold higher T-cell avidity than Tax 11-19-specific CTLs, suggesting better antigen recognition at low expression levels of the antigens. These findings suggest that HLA-A*24, which induces sensitive HTLV-1-specific CTLs, increases the risk of HAM/TSP despite reducing HTLV-1 PVL.

Artificial Antigen-Presenting Cell Fabrication for Murine T Cell Expansion

Antigen-presenting cells (APCs), such as dendritic cells and macrophages, have a unique ability to survey the body and present information to T cells via peptide-loaded major histocompatibility complexes (signal 1). This presentation, along with a co-stimulatory signal (signal 2), leads to activation and subsequent expansion of T cells. This process can be harnessed and utilized for therapeutic applications, but the use of patient-derived APCs can be complex and inefficient. Alternatively, artificial APCs (aAPCs) provide a simplified method to achieve T cell activation by presenting the two necessary stimulatory signals. This protocol describes the utilization of magnetic nanoparticles and stimulatory proteins to create aAPCs that can be employed for activating and expanding antigen-specific T cells for both basic and translational immunology and immunotherapy studies. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Protein and particle modification for aAPC fabrication Basic Protocol 2: aAPC validation by immunolabeling of conjugated protein Support Protocol 1: Quantification of aAPC stock concentration Basic Protocol 3: Determination of aAPC usage for murine CD8+ T cell activation Support Protocol 2: Isolation of murine CD8+ T cells.

XCL1, a serum biomarker in neurological diseases; HTLV-1-associated myelopathy and multiple sclerosis

The XCL1-XCR1 axis has a potential role in the recruitment of immune cells to the site of inflammation. The present study aimed to examine the relation of XCL1 serum levels with Multiple sclerosis (MS) and HTLV-1-associated myelopathy (HAM), as chronic inflammatory diseases of the central nervous system (CNS). DNA was extracted to evaluate HTLV-1 proviral load (PVL) using real-time PCR. Serum levels of XCL1 was determined by using an ELISA assay. The serum level of XCL1 was significantly higher in patients with HAM than that of asymptomatic carriers (ACs) and healthy controls (HCs) (p < 0.001 and p < 0.0001, respectively) and was also higher in MS patients compared to HCs (p < 0.0001). Moreover, the concentration of XCL1 serum level was significantly different between the ACs and HCs group (p < 0.0001). In conclusion, increased expression of XCL1 might contribute to the migration of autoreactive T cells to the central nervous system and play a critical role in the development and pathogenesis of inflammatory neurological diseases including HAM and MS.

T cell receptor repertoire analysis in HTLV-1-associated diseases

Human T lymphotropic virus 1 (HTLV-1) is a human retrovirus identified as the causative agent in adult T-cell leukemia/lymphoma (ATL) and chronic-progressive neuroinflammatory disorder HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 is estimated to infect between 5-20 million people worldwide, although most infected individuals remain asymptomatic. HTLV-1 infected persons carry an estimated lifetime risk of approximately 5% of developing ATL, and between 0.25% and 1.8% of developing HAM/TSP. Most HTLV-1 infection is detected in CD4⁺ T cells in vivo which causes the aggressive malignancy in ATL. In HAM/TSP, the increase of HTLV-1 provirus induces immune dysregulation to alter inflammatory milieu, such as expansion of HTLV-1-specific CD8⁺ T cells, in the central nervous system of the infected subjects, which have been suggested to underlie the pathogenesis of HAM/TSP. Factors contributing to the conversion from asymptomatic carrier to disease state remain poorly understood. As such, the identification and tracking of HTLV-1-specific T cell biomarkers that may be used to monitor the progression from primary infection to immune dysfunction and disease are of great interest. T cell receptor (TCR) repertoires have been extensively investigated as a mechanism of monitoring adaptive T cell immune response to viruses and tumors. Breakthrough technologies such as single-cell RNA sequencing have increased the specificity with which T cell clones may be characterized and continue to improve our understanding of TCR signatures in viral infection, cancer, and associated treatments. In HTLV-1-associated disease, sequencing of TCR repertoires has been used to reveal repertoire patterns, diversity, and clonal expansions of HTLV-1-specific T cells capable of immune evasion and dysregulation in ATL as well as in HAM/TSP. Conserved sequence analysis has further been used to identify CDR3 motif sequences and exploit disease- or patient-specificity and commonality in HTLV-1-associated disease. In this article we review current research on TCR repertoires and HTLV-1-specific clonotypes in HTLV-1-associated diseases ATL and HAM/TSP and discuss the implications of TCR clonal expansions on HTLV-1-associated disease course and treatments.

Panuveitis induced by donor-derived CD8+ T cells after allogeneic hematopoietic stem cell transplantation for adult T-cell leukemia

Purpose

This article presents a case of panuveitis that occurred after unrelated allogeneic hematopoietic stem cell transplantation (allo-HSCT) in a patient with lymphoma-type human T-cell leukemia virus type-1 (HTLV-1)-associated adult T-cell leukemia (ATL).

Observations

A 45-year-old man developed unilateral panuveitis 18 months after undergoing allo-HSCT. He underwent vitrectomy, and depositions of grey-white granules localized on the retinal artery were observed in the eye. Cytological examination of the vitreous aspirates showed that the atypical lymphoid cells stained positive for CD3 and CD8, but negative for CD4, B-cell markers, and cytomegalovirus antigen. Interphase fluorescence in situ hybridization using X‐ and Y‐chromosome probes revealed complete donor chimerism in CD8⁺ T cells in the vitreous aspirates.

Conclusions and importance

Donor-derived CD8⁺ T lymphocytes can induce panuveitis like HTLV-1-assiciated uveitis after allo-HSCT in patients with ATL. Pathological diagnosis of vitreous infiltration by vitrectomy is helpful in patients with ATL. Donor-derived CD8⁺ T lymphocytes-induced panuveitis is recurrent but susceptible to regional corticosteroid treatment.

•

/This is a primary case of panuveitis induced by donor-derived CD8⁺ T lymphocytes in a patient with aggressive ATL after allo-HSCT.

•

/Pathological diagnosis of vitreous infiltration by vitrectomy is helpful in patients with ATL to determine the phenotypes of cells infiltrating the eye of ATL patients.

•

/Donor-derived CD8⁺ T lymphocytes-induced panuveitis is recurrent but susceptible to regional corticosteroid treatment.

Potential role of HTLV-1 Tax-specific cytotoxic t lymphocytes expressing a unique t-cell receptor to promote inflammation of the central nervous system in myelopathy associated with HTLV-1

Human T-lymphotropic virus 1 (HTLV-1) infection causes two serious diseases: adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy (HAM). Immunological studies have revealed that HTLV-1 Tax-specific CD8⁺ cytotoxic T-cells (Tax-CTLs) in asymptomatic carriers (ACs) and ATL patients play an important role in the elimination of HTLV-1-infected host cells, whereas Tax-CTLs in HAM patients trigger an excessive immune response against HTLV-1-infected host cells infiltrating the central nervous system (CNS), leading to local inflammation. Our previous evaluation of HTLV-1 Tax_301-309 (SFHSLHLLF)-specific Tax-CTLs (Tax_301-309-CTLs) revealed that a unique T-cell receptor (TCR) containing amino acid (AA)-sequence motif PDR, was shared among HLA-A*24:02⁺ ACs and ATL patients and behaved as an eliminator by strong activity against HTLV-1. However, it remains unclear whether PDR⁺Tax_301-309-CTLs also exist in HLA-A*24:02⁺ HAM patients and are involved in the pathogenesis of HAM. In the present study, by high-throughput TCR repertoire analysis technology, we revealed TCR repertoires of Tax_301-309-CTLs in peripheral blood (PB) of HLA-A*24:02⁺ HAM patients were skewed, and a unique TCR-motif PDR was conserved in HAM patients (10 of 11 cases). The remaining case dominantly expressed (-DR, P-R, and PD-), which differed by one AA from PDR. Overall, TCRs with unique AA-sequence motifs PDR, or (-DR, P-R, and PD-) accounted for a total of 0.3-98.1% of Tax_301-309-CTLs repertoires of HLA-A*24:02⁺ HAM patients. Moreover, TCR repertoire analysis of T-cells in the cerebrospinal fluid (CSF) from four HAM patients demonstrated the possibility that PDR⁺Tax_301-309-CTLs and (-DR, P-R, and PD-)⁺Tax_301-309-CTLs efficiently migrated and accumulated in the CSF of HAM patients fostering increased inflammation, although we observed no clear significant correlation between the frequencies of them in PB and the levels of CSF neopterin, a known disease activity biomarker of HAM. Furthermore, to better understand the potential function of PDR⁺Tax_301-309-CTLs, we performed immune profiling by single-cell RNA-sequencing of Tax_301-309-CTLs, and the result showed that PDR⁺Tax_301-309-CTLs up-regulated the gene expression of natural killer cell marker KLRB1 (CD161), which may be associated with T-cell activation and highly cytotoxic potential of memory T-cells. These findings indicated that unique and shared PDR⁺Tax_301-309-CTLs have a potential role in promoting local inflammation within the CNS of HAM patients.

Pathogenesis of HTLV-1 infection and progression biomarkers: An overview

Infection by human T-cell lymphotropic virus type 1 (HTLV-1) occurs in lymphocytes, which travel throughout the body, thus affecting several target organs and causing varied clinical outcomes, particularly in populations that are underserved and do not have access to healthcare. However, the mechanism of pathogenesis is not yet fully understood. The TAX and HTLV-1 basic leucine zipper factor (HBZ) proteins maintain viral persistence and affect pathogenesis through cell proliferation and immune and inflammatory responses that accompany each clinical manifestation. TAX expression leads to inhibition of transcription error control, OX40 overexpression, and cell proliferation in adult T-cell leukemia (ATL). OX40 levels are elevated in the central nervous system (CNS), and the expression of TAX in the CNS causes neuronal damage and loss of immune reactivity among patients with HTLV-1-associated myelopathy (HAM). HBZ reduces viral replication and suppresses the immune response. Its cell compartmentalization has been associated with the pathogenesis of HAM (cytoplasmic localization) and ATL (nuclear localization). TAX and HBZ seem to act antagonistically in immune responses, affecting the pathogenesis of HTLV-1 infection. The progression from HTLV-1 infection to disease is a consequence of HTLV-1 replication in CD4⁺ T and CD8⁺ T lymphocytes and the imbalance between proinflammatory and anti-inflammatory cytokines. The compartmentalization of HBZ suggests that this protein may be an additional tool for assessing immune and inflammatory responses, in addition to those already recognized as potential biomarkers associated with progression from infection to disease (including human leukocyte antigen (HLA), killer immunoglobulin-like receptors (KIR), interleukin (IL)-6, IL-10, IL-28, Fas, Fas ligand, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and mannose-binding lectin).

MHC multimer: A Molecular Toolbox for Immunologists

The advent of the major histocompatibility complex (MHC) multimer technology has led to a breakthrough in the quantification and analysis of antigen-specific T cells. In particular, this technology has dramatically advanced the measurement and analysis of CD8 T cells and is being applied more widely. In addition, the scope of application of MHC multimer technology is gradually expanding to other T cells such as CD4 T cells, natural killer T cells, and mucosal-associated invariant T cells. MHC multimer technology acts by complementing the T-cell receptor-MHC/peptide complex affinity, which is relatively low compared to antigen-antibody affinity, through a multivalent interaction. The application of MHC multimer technology has expanded to include various functions such as quantification and analysis of antigen-specific T cells, cell sorting, depletion, stimulation to replace antigen-presenting cells, and single-cell classification through DNA barcodes. This review aims to provide the latest knowledge of MHC multimer technology, which is constantly evolving, broaden understanding of this technology, and promote its widespread use.

Extracellular vesicles from HTLV-1 infected cells modulate target cells and viral spread

BACKGROUND

The Human T-cell Lymphotropic Virus Type-1 (HTLV-1) is a blood-borne pathogen and etiological agent of Adult T-cell Leukemia/Lymphoma (ATLL) and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). HTLV-1 has currently infected up to 10 million globally with highly endemic areas in Japan, Africa, the Caribbean and South America. We have previously shown that Extracellular Vesicles (EVs) enhance HTLV-1 transmission by promoting cell-cell contact.

RESULTS

Here, we separated EVs into subpopulations using differential ultracentrifugation (DUC) at speeds of 2 k (2000×g), 10 k (10,000×g), and 100 k (100,000×g) from infected cell supernatants. Proteomic analysis revealed that EVs contain the highest viral/host protein abundance in the 2 k subpopulation (2 k > 10 k > 100 k). The 2 k and 10 k populations contained viral proteins (i.e., p19 and Tax), and autophagy proteins (i.e., LC3 and p62) suggesting presence of autophagosomes as well as core histones. Interestingly, the use of 2 k EVs in an angiogenesis assay (mesenchymal stem cells + endothelial cells) caused deterioration of vascular-like-tubules. Cells commonly associated with the neurovascular unit (i.e., astrocytes, neurons, and macrophages) in the blood-brain barrier (BBB) showed that HTLV-1 EVs may induce expression of cytokines involved in migration (i.e., IL-8; 100 k > 2 k > 10 k) from astrocytes and monocyte-derived macrophages (i.e., IL-8; 2 k > 10 k). Finally, we found that EVs were able to promote cell-cell contact and viral transmission in monocytic cell-derived dendritic cell. The EVs from both 2 k and 10 k increased HTLV-1 spread in a humanized mouse model, as evidenced by an increase in proviral DNA and RNA in the Blood, Lymph Node, and Spleen.

CONCLUSIONS

Altogether, these data suggest that various EV subpopulations induce cytokine expression, tissue damage, and viral spread.

A chimeric HLA-A2:β2M:Ig fusion protein for the study of virus-specific CD8+ T-cells

INTRODUCTION

The response mediated by CD8⁺ T-cells in the context of infection and vaccination has been thoroughly investigated and represents one of the most important branches that allow for the development of immunity against intracellular pathogens and, thus, the establishment of robust antiviral responses. However, there is a lack of methods to assess antigen-specific CD8⁺ T-cells.

OBJECTIVE

Search for the ideal assays to assess the function of antigen-specific CD8⁺ T-cells.

METHODS

In the present study a chimeric HLA-A2:β2M:Ig fusion protein was produced, purified, and evaluated in functional CD8⁺ T-cell response studies using samples from Influenza A patients and humanized mice upon adenoviral vaccination.

RESULTS

The HLA-A2:β2M:Ig molecule, bound to immunodominant viral peptides by passive transfer, was able to induce robust antiviral CD8⁺ T-cell responses mediated by IFN-γ. The in vitro IFN-γ release assay using the chimeric HLA-A2:β2M:Ig fusion protein detected bona fide human CD8⁺ T-cells, demonstrating superior production of IFN-γ by human CD8⁺ T-cells induced by Influenza A immunodominant GILGFVFTL peptide. Removal of antigen-presenting cells and CD8⁺ T-cell enrichment improved significantly the IFN-γ production. The chimeric HLA-A2:β2M:Ig fusion protein also triggered HLA-A2-restricted CD8⁺ T-cell response in a humanized mouse model upon vaccination with adenovirus encoding HLA-A2-restricted HIV p24 antigen. The results strongly suggest the use of tailor-made assays for detecting HLA-A2-restricted CD8⁺ T-cell Responses in the Humanized Mouse Model.

CONCLUSION

The chimeric HLA-A2:β2M:Ig fusion protein-based assays provided a sensitive tool that may be paramount to measure virus-specific CD8⁺ T-cell response in a range of viral infections of clinical relevance.

Pilates exercise improves the clinical and immunological profiles of patients with human T-cell lymphotropic virus 1 associated myelopathy: A pilot study

BACKGROUND

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is an infectious chronic-inflammatory disease, which can lead to lower limb motions.

METHODS

The study evaluated the effects of serial Pilates exercises on the clinical and immunological profiles of patients with HAM/TSP. Eight patients with ages ranging from 39 to 70 years old (2 males and 6 females), 2 wheelchair users and 6 with compromised gait, were evaluated. The patients were submitted to 20 Pilates sessions for 10 weeks. Data were collected at 3 time points (beginning of the study, after Pilates sessions and after 10 weeks without Pilates) and consisted of evaluations of the pain level, spasticity, motor strength, balance, mobility, functional capacity, quality of life and quantification of IFN-γ, IL-10 and IL-9 cytokines levels.

RESULTS

After the Pilates sessions, significant improvements in pain level, static and dynamic balance, trunk control, mobility and quality of life were observed, with simultaneous and significant reductions in the serum levels of the cytokines IFN-γ and IL-10. However, after 10 weeks without Pilates, there were significant changes in terms of increasing pain and regression of mobility, with no changes in strength, spasticity, functional capacity in any of the periods of the study.

CONCLUSIONS

The results suggest that Pilates may be a promising auxiliary physical therapy for patients with HAM/TSP.

An update on human T-cell leukemia virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) focusing on clinical and laboratory biomarkers

Human T-cell leukemia virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a rare inflammatory disease causing unremitting and progressive neurological disorders, such as spastic paraparesis, neurogenic bladder, and sensory disturbance of the lower extremities. Although there is no cure, immune-modulating agents such as corticosteroids are most widely used to slow disease progression. Biomarkers for the clinical assessment of HAM/TSP should be identified because the prediction of functional prognosis and the assessment of treatment efficacy are challenging due to the slowly progressive nature of the disease. The lack of surrogate biomarkers also hampers clinical trials of new drugs. This review summarizes biomarker candidates for the clinical assessment of patients with HAM/TSP. Most of the reported biomarker candidates are associated with viral components or inflammatory mediators because immune dysregulation provoked by HTLV-1 infection is thought to cause chronic inflammation and damage the spinal cord of patients with HAM/TSP. Although information on the diagnostic accuracy of most of the reported biomarkers is insufficient, several molecules, including inflammatory mediators such as CXCL10 and neopterin in the cerebrospinal fluid, have been suggested as potential biomarkers of functional prognosis and treatment response. Several clinical trials for HAM/TSP are currently underway, and we expect that these studies will provide not only evidence pertaining to treatment, but also novel findings regarding the utility of biomarkers in this disease. The establishment of clinical biomarkers will improve patient care and promote the development of therapies for HAM/TSP.

Human T-lymphotropic virus type 1 (HTLV-1) and cellular immune response in HTLV-1-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus type 1 (HTLV-1) is associated with adult T cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is an inflammatory disease of the spinal cord and clinically characterized by progressive spastic paraparesis, urinary incontinence, and mild sensory disturbance. The interaction between the host immune response and HTLV-1-infected cells regulates the development of HAM/TSP. HTLV-1 preferentially infects CD4⁺ T cells and is maintained by proliferation of the infected T cells. HTLV-1-infected cells rarely express viral antigens in vivo; however, they easily express the antigens after short-term culture. Therefore, such virus-expressing cells may lead to activation and expansion of antigen-specific T cell responses. Infected T cells with HTLV-1 and HTLV-1-specific CD8⁺ cytotoxic T lymphocytes invade the central nervous system and produce various proinflammatory cytokines and chemokines, leading to neuronal damage and degeneration. Therefore, cellular immune responses to HTLV-1 have been considered to play important roles in disease development of HAM/TSP. Recent studies have clarified the viral strategy for persistence in the host through genetic and epigenetic changes by HTLV-1 and host immune responses including T cell function and differentiation. Newly developed animal models could provide the opportunity to uncover the precise pathogenesis and development of clinically effective treatment. Several molecular target drugs are undergoing clinical trials with promising efficacy. In this review, we summarize recent advances in the immunopathogenesis of HAM/TSP and discuss the perspectives of the research on this disease.

Immunovirological markers in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP)

Human T cell lymphotropic virus 1 (HTLV-1) is a human retrovirus and infects approximately 10–20 million people worldwide. While the majority of infected people are asymptomatic carriers of HTLV-1, only 4% of infected people develop HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is a chronic, progressive, neurological disease which usually progresses slowly without remission, and is characterized by perivascular inflammatory infiltrates in chronic inflammatory lesions of the central nervous system (CNS), primarily affecting the spinal cord. A high HTLV-1 proviral load, high levels of antibodies against HTLV-1 antigens, and elevated concentration of proteins are detected in cerebrospinal fluid (CSF) of HAM/TSP patients. These chronically activated immune responses against HTLV-1 and infiltration of inflammatory cells including HTLV-1 infected cells into the CNS contribute to clinical disability and underlie the pathogenesis of HAM/TSP. Since the disease development of HAM/TSP mainly occurs in adults, with a mean age at onset of 40–50 years, it is important for HTLV-1-infected carriers and HAM/TSP patients to be monitored throughout the disease process. Recent advances in technologies and findings provide new insights to virological and immunological aspects in both the CNS as well as in peripheral blood. In this review, we focus on understanding the inflammatory milieu in the CNS and discuss the immunopathogenic process in HTLV-1-associated neurologic diseases.

Neuroimmunology of Human T-Lymphotropic Virus Type 1-Associated Myelopathy/Tropical Spastic Paraparesis

Human T-lymphotropic virus type 1 (HTLV-1) is the etiologic agent of both adult T-cell leukemia/lymphoma and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HAM/TSP is clinically characterized by chronic progressive spastic paraparesis, urinary incontinence, and mild sensory disturbance. Given its well-characterized clinical presentation and pathophysiology, which is similar to the progressive forms of multiple sclerosis (MS), HAM/TSP is an ideal system to better understand other neuroimmunological disorders such as MS. Since the discovery of HAM/TSP, large numbers of clinical, virological, molecular, and immunological studies have been published. The host-virus interaction and host immune response play an important role for the development with HAM/TSP. HTLV-1-infected circulating T-cells invade the central nervous system (CNS) and cause an immunopathogenic response against virus and possibly components of the CNS. Neural damage and subsequent degeneration can cause severe disability in patients with HAM/TSP. Little progress has been made in the discovery of objective biomarkers for grading stages and predicting progression of disease and the development of molecular targeted therapy based on the underlying pathological mechanisms. We review the recent understanding of immunopathological mechanism of HAM/TSP and discuss the unmet need for research on this disease.

Combinatorial screening algorithm to engineer multiepitope subunit vaccine targeting human T-lymphotropic virus-1 infection

Human T-lymphotropic virus (HTLV), the first human retrovirus has been discovered which is known to cause the age-old assassinating disease HTLV-1 associated myelopathy. Cancer caused by this virus is adult T cell leukemia/lymphoma which targets 10-20 million throughout the world. The effect of this virus extends to the fact that it causes chronic disease to the spinal cord resulting in loss of sensation and further causes blood cancer. So, to overcome the complications, we designed a subunit vaccine by the assimilation of B-cell, cytotoxic T-lymphocyte , and helper T-lymphocyte epitopes. The epitopes were joined together along with adjuvant and linkers and a vaccine was fabricated which was further subjected to 3D modeling. The physiochemical properties, allergenicity, and antigenicity were evaluated. Molecular docking and dynamics were performed with the obtained 3D model against toll like receptor (TLR-3) immune receptor. Lastly, in silico cloning was performed to ensure the expression of the designed vaccine in pET28a(+) expression vector. The future prospects of the study entailed the in vitro and in vivo experimental analysis for evaluating the immune response of the designed vaccine construct.

Viral antigens detectable in CSF exosomes from patients with retrovirus associated neurologic disease: functional role of exosomes

BACKGROUND

HTLV-1 infects over 20 million people worldwide and causes a progressive neuroinflammatory disorder in a subset of infected individuals called HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). The detection of HTLV-1 specific T cells in the cerebrospinal fluid (CSF) suggests this disease is immunopathologically mediated and that it may be driven by viral antigens. Exosomes are microvesicles originating from the endosomal compartment that are shed into the extracellular space by various cell types. It is now understood that several viruses take advantage of this mode of intercellular communication for packaging of viral components as well. We sought to understand if this is the case in HTLV-1 infection, and specifically if HTLV-1 proteins can be found in the CSF of HAM/TSP patients where we know free virus is absent, and furthermore, if exosomes containing HTLV-1 Tax have functional consequences.

RESULTS

Exosomes that were positive for HTLV-1 Tax by Western blot were isolated from HAM/TSP patient PBMCs (25/36) in ex vivo cultures by trapping exosomes from culture supernatants. HTLV-1 seronegative PBMCs did not have exosomes with Tax (0/12), (Fisher exact test, p = 0.0001). We were able to observe HAM/TSP patient CSF (12/20) containing Tax⁺ exosomes but not in HTLV-1 seronegative MS donors (0/5), despite the absence of viral detection in the CSF supernatant (Fisher exact test p = 0.0391). Furthermore, exosomes cultivated from HAM/TSP PBMCs were capable of sensitizing target cells for HTLV-1 specific CTL lysis.

CONCLUSION

Cumulatively, these results show that there are HTLV-1 proteins present in exosomes found in virus-free CSF. HAM/TSP PBMCs, particularly CD4⁺CD25⁺ T cells, can excrete these exosomes containing HTLV-1 Tax and may be a source of the exosomes found in patient CSF. Importantly, these exosomes are capable of sensitizing an HTLV-1 specific immune response, suggesting that they may play a role in the immunopathology observed in HAM/TSP. Given the infiltration of HTLV-1 Tax-specific CTLs into the CNS of HAM/TSP patients, it is likely that exosomes may also contribute to the continuous activation and inflammation observed in HAM/TSP, and may suggest future targeted therapies in this disorder.

Immunophenotypic characterization of CSF B cells in virus-associated neuroinflammatory diseases

Intrathecal antibody synthesis is a well-documented phenomenon in infectious neurological diseases as well as in demyelinating diseases, but little is known about the role of B cells in the central nervous systems. We examined B cell and T cell immunophenotypes in CSF of patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) compared to healthy normal donors and subjects with the other chronic virus infection and/or neuroinflammatory diseases including HIV infection, multiple sclerosis (MS) and progressive multifocal leukoencephalopathy. Antibody secreting B cells (ASCs) were elevated in HAM/TSP patients, which was significantly correlated with intrathecal HTLV-1-specific antibody responses. High frequency of ASCs was also detected in patients with relapsing-remitting multiple sclerosis (RRMS). While RRMS patients showed significant correlations between ASCs and memory follicular helper CD4+ T cells, CD4+CD25+ T cells were elevated in HAM/TSP patients, which were significantly correlated with ASCs and HTLV-1 proviral load. These results highlight the importance of the B cell compartment and the associated inflammatory milieu in HAM/TSP patients where virus-specific antibody production may be required to control viral persistence and/or may be associated with disease development.

Immune Responses to Retroviruses

Retroviruses are genome invaders that have shared a long history of coevolution with vertebrates and their immune system. Found endogenously in genomes as traces of past invasions, retroviruses are also considerable threats to human health when they exist as exogenous viruses such as HIV. The immune response to retroviruses is engaged by germline-encoded sensors of innate immunity that recognize viral components and damage induced by the infection. This response develops with the induction of antiviral effectors and launching of the clonal adaptive immune response, which can contribute to protective immunity. However, retroviruses efficiently evade the immune response, owing to their rapid evolution. The failure of specialized immune cells to respond, a form of neglect, may also contribute to inadequate antiretroviral immune responses. Here, we discuss the mechanisms by which immune responses to retroviruses are mounted at the molecular, cellular, and organismal levels. We also discuss how intrinsic, innate, and adaptive immunity may cooperate or conflict during the generation of immune responses.

Role of HTLV-1 Tax and HBZ in the Pathogenesis of HAM/TSP

Human T cell lymphotropic virus type 1 (HTLV-1) infection can lead to development of adult T cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a subset of infected subjects. Understanding the interaction between host and HTLV-1 and the molecular mechanisms associated with disease pathogenesis is critical for development efficient therapies. Two HTLV-1 genes, tax and HTLV-1 basic leucine zipper factor (HBZ), have been demonstrated to play important roles in HTLV-1 infectivity and the growth and survival of leukemic cells. Increased HTLV-1 Tax expression induces the expression of various cellular genes such as IL-2 and IL-15, which directly contributes to lymphocyte activation and immunopathogenesis in HAM/TSP patients. However, little is known about the molecular and cellular mechanism of HBZ in development of HAM/TSP. It has been reported that HBZ mRNA expression was detected in HAM/TSP patients higher than in asymptomatic carriers and correlated with proviral load and disease severity. Unlike HTLV-1 tax, HBZ escapes efficient anti-viral immune responses and therefore these reactivities are difficult to detect. Thus, it is important to focus on understanding the function and the role of HTLV-1 tax and HBZ in disease development of HAM/TSP and discuss the potential use of these HTLV-1 viral gene products as biomarkers and therapeutic targets for HAM/TSP.

Frequency and reactivity of antigen-specific T cells were concurrently measured through the combination of artificial antigen-presenting cell, MACS and ELISPOT

Conventional peptide-major histocompatibility complex (pMHC) multimer staining, intracellular cytokine staining, and enzyme-linked immunospot (ELISPOT) assay cannot concurrently determine the frequency and reactivity of antigen-specific T cells (AST) in a single assay. In this report, pMHC multimer, magnetic-activated cell sorting (MACS), and ELISPOT techniques have been integrated into a micro well by coupling pMHC multimers onto cell-sized magnetic beads to characterize AST cell populations in a 96-well microplate which pre-coated with cytokine-capture antibodies. This method, termed AAPC-microplate, allows the enumeration and local cytokine production of AST cells in a single assay without using flow cytometry or fluorescence intensity scanning, thus will be widely applicable. Here, ovalbumin257-264-specific CD8+ T cells from OT-1 T cell receptor (TCR) transgenic mice were measured. The methodological accuracy, specificity, reproducibility, and sensitivity in enumerating AST cells compared well with conventional pMHC multimer staining. Furthermore, the AAPC-microplate was applied to detect the frequency and reactivity of Hepatitis B virus (HBV) core antigen18-27- and surface antigen183-191-specific CD8+ T cells for the patients, and was compared with conventional method. This method without the need of high-end instruments may facilitate the routine analysis of patient-specific cellular immune response pattern to a given antigen in translational studies.

Programmed death 1 is highly expressed on CD8+ CD57+ T cells in patients with stable multiple sclerosis and inhibits their cytotoxic response to Epstein-Barr virus

Growing evidence points to a deregulated response to Epstein-Barr virus (EBV) in the central nervous system of patients with multiple sclerosis (MS) as a possible cause of disease. We have investigated the response of a subpopulation of effector CD8⁺ T cells to EBV in 36 healthy donors and in 35 patients with MS in active and inactive disease. We have measured the expression of markers of degranulation, the release of cytokines, cytotoxicity and the regulation of effector functions by inhibitory receptors, such as programmed death 1 (PD-1) and human inhibitor receptor immunoglobulin-like transcript 2 (ILT2). We demonstrate that polyfunctional cytotoxic CD8⁺ CD57⁺ T cells are able to kill EBV-infected cells in healthy donors. In contrast, an anergic exhaustion-like phenotype of CD8⁺ CD57⁺ T cells with high expression of PD-1 was observed in inactive patients with MS compared with active patients with MS or healthy donors. Detection of CD8⁺ CD57⁺ T cells in meningeal inflammatory infiltrates from post-mortem MS tissue confirmed the association of this cell phenotype with the disease pathological process. The overall results suggest that ineffective immune control of EBV in patietns with MS during remission may be one factor preceding and enabling the reactivation of the virus in the central nervous system and may cause exacerbation of the disease.

MAIT cells are reduced in frequency and functionally impaired in human T lymphotropic virus type 1 infection: Potential clinical implications

HTLV-1 infection is associated with several inflammatory disorders, including the neurodegenerative condition HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is unclear why a minority of infected subjects develop HAM/TSP. The cellular immune response has been implicated in the development of inflammatory alterations in these patients; however the pathogenic mechanisms for disease progression remain unclear. Furthermore, HTLV-1-infected individuals have an increase incidence of Mycobacterium tuberculosis (Mtb) infection, suggesting that immunological defect are associated with HTLV-1 infection. Evidence suggests an important role for Mucosal-associated invariant T (MAIT) cells in the early control of Mtb infection. Chronic viral infections like HIV and HCV have been associated with decreased frequency and functionality of MAIT cells. We hypothesized that HTLV-1 infection is associated with similar perturbations in MAIT cells. We investigated MAIT cell frequency, phenotype, and function by flow cytometry in a cohort of 10 asymptomatic and 10 HAM/TSP HTLV-1 infected patients. We found that MAIT cells from HTLV-1-infected subjects were reduced and showed high co-expression of the activation markers CD38 and HLA-DR but normal levels of CCR6 and CD127. MAIT cells had a lower expression of the transcription factor PLZF in HAM/TSP patients. Unlike Tax-specific CD8+T cells, which are hyperfunctional, MAIT cells from HTLV-1-infected subjects had a poor IFNγ response following antigen stimulation. MAIT cell perturbations in HTLV-1 infection were not associated with HTLV-1 proviral load and MAIT cells were not infected by HTLV-1 in vivo. Rather, MAIT cells loss was associated with immune activation. Overall, our results do not support a role for MAIT cells in HAM/TSP pathogenesis but reduced numbers of MAIT cells, together with their poor functionality, could contribute to the increased susceptibility of HTLV-1-infected individuals to other infectious agents.

Development of neurologic diseases in a patient with primate T lymphotropic virus type 1 (PTLV-1)

Background

Virus transmission from various wild and domestic animals contributes to an increased risk of emerging infectious diseases in human populations. HTLV-1 is a human retrovirus associated with acute T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 originated from ancient zoonotic transmission from nonhuman primates, although cases of zoonotic infections continue to occur. Similar to HTLV-1, the simian counterpart, STLV-1, causes chronic infection and leukemia and lymphoma in naturally infected monkeys, and combined are called primate T-lymphotropic viruses (PTLV-1). However, other clinical syndromes typically seen in humans such as a chronic progressive myelopathy have not been observed in nonhuman primates. Little is known about the development of neurologic and inflammatory diseases in human populations infected with STLV-1-like viruses following nonhuman primate exposure.

Results

We performed detailed laboratory analyses on an HTLV-1 seropositive patient with typical HAM/TSP who was born in Liberia and now resides in the United States. Using a novel droplet digital PCR for the detection of the HTLV-1 tax gene, the proviral load in PBMC and cerebrospinal fluid cells was 12.98 and 51.68 %, respectively; however, we observed a distinct difference in fluorescence amplitude of the positive droplet population suggesting possible mutations in proviral DNA. A complete PTLV-1 proviral genome was amplified from the patient’s PBMC DNA using an overlapping PCR strategy. Phylogenetic analysis of the envelope and LTR sequences showed the virus was highly related to PTLV-1 from sooty mangabey monkeys (smm) and humans exposed via nonhuman primates in West Africa.

Conclusions

These results demonstrate the patient is infected with a simian variant of PTLV-1, suggesting for the first time that PTLV-1smm infection in humans may be associated with a chronic progressive neurologic disease.

Effect of Pulsed Methylprednisolone on Pain, in Patients with HTLV-1-Associated Myelopathy

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is an immune mediated myelopathy caused by the human T-lymphotropic virus type 1 (HTLV-1). The efficacy of treatments used for patients with HAM/TSP is uncertain. The aim of this study is to document the efficacy of pulsed methylprednisolone in patients with HAM/TSP. Data from an open cohort of 26 patients with HAM/TSP was retrospectively analysed. 1g IV methylprednisolone was infused on three consecutive days. The outcomes were pain, gait, urinary frequency and nocturia, a range of inflammatory markers and HTLV-1 proviral load. Treatment was well tolerated in all but one patient. Significant improvements in pain were: observed immediately, unrelated to duration of disease and maintained for three months. Improvement in gait was only seen on Day 3 of treatment. Baseline cytokine concentrations did not correlate to baseline pain or gait impairment but a decrease in tumour necrosis factor-alpha (TNF-α) concentration after pulsed methylprednisolone was associated with improvements in both. Until compared with placebo, treatment with pulsed methylprednisolone should be offered to patients with HAM/TSP for the treatment of pain present despite regular analgesia.

Human T Cell Leukemia Virus Type 1 Infection of the Three Monocyte Subsets Contributes to Viral Burden in Humans

Because the viral DNA burden correlates with disease development, we investigated the contribution of monocyte subsets (classical, intermediate, and nonclassical monocytes) to the total viral burden in 22 human T cell leukemia virus type 1 (HTLV-1)-infected individuals by assessing their infectivity status, frequency, as well as chemotactic and phagocytic functions. All three monocyte subsets sorted from HTLV-1-infected individuals were positive for viral DNA, and the frequency of classical monocytes was lower in the blood of HTLV-1-infected individuals than in that of uninfected individuals, while the expression levels of the chemokine receptors CCR5, CXCR3, and CX3CR1 in classical monocytes were higher in HTLV-1-infected individuals than uninfected individuals; the percentage of intermediate monocytes and their levels of chemokine receptor expression did not differ between HTLV-1-infected and uninfected individuals. However, the capacity of intermediate monocytes to migrate to CCL5, the ligand for CCR5, was higher, and a higher proportion of nonclassical monocytes expressed CCR1, CXCR3, and CX3CR1. The level of viral DNA in the monocyte subsets correlated with the capacity to migrate to CCL2, CCL5, and CX3CL1 for classical monocytes, with lower levels of phagocytosis for intermediate monocytes, and with the level of viral DNA in CD8(+) and CD4(+) T cells for nonclassical monocytes. These data suggest a model whereby HTLV-1 infection augments the number of classical monocytes that migrate to tissues and become infected and the number of infected nonclassical monocytes that transmit virus to CD4(+) and CD8(+) T cells. These results, together with prior findings in a macaque model of HTLV-1 infection, support the notion that infection of monocytes by HTLV-1 is likely a requisite for viral persistence in humans.

IMPORTANCE

Monocytes have been implicated in immune regulation and disease progression in patients with HTLV-1-associated inflammatory diseases. We detected HTLV-1 DNA in all three monocyte subsets and found that infection impacts surface receptor expression, migratory function, and subset frequency. The frequency of nonclassical patrolling monocytes is increased in HTLV-1-infected individuals, and they have increased expression of CCR1, CXCR3, and CX3CR1. The viral DNA level in nonclassical monocytes correlated with the viral DNA level in CD4(+) and CD8(+) T cells. Altogether, these data suggest an increased recruitment of classical monocytes to inflammation sites that may result in virus acquisition and, in turn, facilitate virus dissemination and viral persistence. Our findings thus provide new insight into the importance of monocyte infection in viral spread and suggest targeting of monocytes for therapeutic intervention.

Application of the pMHC Array to Characterise Tumour Antigen Specific T Cell Populations in Leukaemia Patients at Disease Diagnosis

Immunotherapy treatments for cancer are becoming increasingly successful, however to further improve our understanding of the T-cell recognition involved in effective responses and to encourage moves towards the development of personalised treatments for leukaemia immunotherapy, precise antigenic targets in individual patients have been identified. Cellular arrays using peptide-MHC (pMHC) tetramers allow the simultaneous detection of different antigen specific T-cell populations naturally circulating in patients and normal donors. We have developed the pMHC array to detect CD8+ T-cell populations in leukaemia patients that recognise epitopes within viral antigens (cytomegalovirus (CMV) and influenza (Flu)) and leukaemia antigens (including Per Arnt Sim domain 1 (PASD1), MelanA, Wilms' Tumour (WT1) and tyrosinase). We show that the pMHC array is at least as sensitive as flow cytometry and has the potential to rapidly identify more than 40 specific T-cell populations in a small sample of T-cells (0.8-1.4 x 10(6)). Fourteen of the twenty-six acute myeloid leukaemia (AML) patients analysed had T cells that recognised tumour antigen epitopes, and eight of these recognised PASD1 epitopes. Other tumour epitopes recognised were MelanA (n = 3), tyrosinase (n = 3) and WT1(126-134) (n = 1). One of the seven acute lymphocytic leukaemia (ALL) patients analysed had T cells that recognised the MUC1(950-958) epitope. In the future the pMHC array may be used provide point of care T-cell analyses, predict patient response to conventional therapy and direct personalised immunotherapy for patients.

Human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis: Clinical presentation and pathophysiology

Human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a slowly progressive neurodegenerative disorder in which lesions of the central nervous system cause progressive weakness, stiffness, and a lower limb spastic paraparesis. In some cases, polymyositis, inclusion body myositis, or amyotrophic lateral sclerosis-like syndromes are associated with HTLV-1. TSP was first described in Jamaica in 1888 and known as Jamaican peripheral neuritis before TSP was related to HTLV-1 virus, the first retrovirus being identified, and the disease is since named HAM/TSP. There is no established treatment program for HAM/TSP. Prevention is difficult in low-income patients (i.e., HTLV-1 infected breast feeding mothers in rural areas, sex workers). Thus, there is a need for new therapeutic avenues. Therapeutic approaches must be based on a better understanding, not only of clinical and clinicopathological data, but also of the pathophysiology of the affection. Consequently, a better understanding of existing or newly developed animal models of HAM/TSP is a prerequisite step in the development of new treatments.

Visualization of HTLV-1-specific cytotoxic T lymphocytes in the spinal cords of patients with HTLV-1-associated myelopathy/tropical spastic paraparesis

Activated human T-lymphotropic virus type-1 (HTLV-1)–specific CD8-positive cytotoxic T lymphocytes (CTLs) are markedly increased in the periphery of patients with HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP), an HTLV-1–induced inflammatory disease of the CNS. Although virus-specific CTLs play a pivotal role to eliminate virus-infected cells, the potential role of HTLV-1–specific CTLs in the pathogenesis of HAM/TSP remains unclear. To address this issue, we evaluated the infiltration of HTLV-1–specific CTLs and the expression of HTLV-1 proteins in the spinal cords of 3 patients with HAM/TSP. Confocal laser scanning microscopy with our unique staining procedure made it possible to visualize HTLV-1–specific CTLs infiltrating the CNS of the HAM/TSP patients. The frequency of HTLV-1–specific CTLs was more than 20% of CD8-positive cells infiltrating the CNS. In addition, HTLV-1 proteins were detected in CD4-positive infiltrating T lymphocytes but not CNS resident cells. Although neurons were generally preserved, apoptotic oligodendrocytes were frequently in contact with CD8-positive cells; this likely resulted in demyelination. These findings suggest that the immune responses of the CTLs against HTLV-1–infected CD4-positive lymphocytes migrating into the CNS resulted in bystander neural damage.

Development of thyroglobulin antibodies after GVAX immunotherapy is associated with prolonged survival

Cancer immunotherapy induces a variety of autoinflammatory responses, including those against the thyroid gland, which can be exploited to predict clinical outcomes. Considering the paucity of information about thyroid autoimmunity in patients receiving cancer vaccines, we designed our study to assess the development of thyroglobulin antibodies (TgAbs) in patients treated with GVAX (vaccine made of a tumor cell type transfected with GM-CSF) and/or ipilimumab and correlated seroconversion with survival. Using both in house and commercial ELISA assays, we measured TgAbs in patients with pancreatic (No. = 53), prostate (No. = 35) or colon (No. = 8) cancer, before and after treatment with GVAX only (No. = 34), GVAX plus ipilimumab (No. = 42) or ipilimumab (No. = 20), and correlated their levels with patient's survival, disease status and T-cell surface markers. Antibodies to thyroperoxidase, myeloperoxidase, proteinase 3, insulin and actin were also measured. TgAbs specifically developed after GVAX, independent of the underlying cancer (81% in prostate, 75% colon cancer and 76% pancreatic cancer) and co-administration of ipilimumab (75% in GVAX only and 78% in GVAX plus ipilimumab). This TgAbs seroconversion could be detected mainly by the in house assay, suggesting that the thyroglobulin epitopes recognized by the antibodies induced by GVAX are different from the epitopes seen in the classic form of Hashimoto thyroiditis. Notably, TgAbs seroconversion was associated with significantly prolonged survival (p = 0.01 for pancreas and p = 0.005 for prostate cancer). In conclusion, GVAX immunotherapy induces the appearance of TgAbs that recognize a unique antigenic repertoire and associate with prolonged survival.

In vivo immunogenicity of Tax(11-19) epitope in HLA-A2/DTR transgenic mice: implication for dendritic cell-based anti-HTLV-1 vaccine

Viral oncoprotein Tax plays key roles in transformation of human T-cell leukemia virus (HTLV-1)-infected T cells leading to adult T-cell leukemia (ATL), and is the key antigen recognized during HTLV-associated myelopathy (HAM). In HLA-A2+ asymptomatic carriers as well as ATL and HAM patients, Tax(11-19) epitope exhibits immunodominance. Here, we evaluate CD8 T-cell immune response against this epitope in the presence and absence of dendritic cells (DCs) given the recent encouraging observations made with Phase 1 DC-based vaccine trial for ATL. To facilitate these studies, we first generated an HLA-A2/DTR hybrid mouse strain carrying the HLA-A2.1 and CD11c-DTR genes. We then studied CD8 T-cell immune response against Tax(11-19) epitope delivered in the absence or presence of Freund's adjuvant and/or DCs. Overall results demonstrate that naturally presented Tax epitope could initiate an antigen-specific CD8T cell response in vivo but failed to do so upon DC depletion. Presence of adjuvant potentiated Tax(11-19)-specific response. Elevated serum IL-6 levels coincided with depletion of DCs whereas decreased TGF-β was associated with adjuvant use. Thus, Tax(11-19) epitope is a potential candidate for the DC-based anti-HTLV-1 vaccine and the newly hybrid mouse strain could be used for investigating DC involvement in human class-I-restricted immune responses.

Lack of recall response to Tax in ATL and HAM/TSP patients but not in asymptomatic carriers of human T-cell leukemia virus type 1

PURPOSE & METHODS

The immunopathogenic mechanisms responsible for debilitating neurodegenerative and oncologic diseases associated with human T-cell leukemia virus type 1 (HTLV-1) are not fully understood. Quality of cytotoxic T lymphocytes (CTLs) is being increasingly associated with the outcome of persistent HTLV-1 infection. In this respect, a patient cohort (from HTLV-1 endemic region) consisting of seronegative controls (controls), asymptomatic carriers (ACs), and patients with adult T-cell leukemia (ATL) or HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP) was analyzed for CD8(+) T cells polyfunctionality in response to the viral antigen Tax.

RESULTS

Compared to ACs, ATL and HAM/TSP patients had lower frequency and polyfunctionality of CTLs in response to Tax suggesting dysfunction of CD8(+) T cells in these individuals. As an underlying mechanism, programmed death-1 (PD-1) receptor was found to be highly unregulated in Tax-responsive as well as total CD8(+) T cells from ATL and HAM/TSP but not from ACs and directly correlated with the lack of polyfunctionality in these individuals. Further, PD-1 expression showed a direct whereas MIP-1α expression had an indirect correlation with the proviral load providing new insights about the immunopathogenesis of HTLV-associated diseases. Additionally, we identified key cytokine signatures defining the immune activation status of clinical samples by the luminex assay.

CONCLUSIONS

Collectively, our findings suggest that reconstitution of fully functional CTLs, stimulation of MIP-1α expression, and/or blockade of the PD-1 pathway are potential approaches for immunotherapy / therapeutic vaccine against HTLV-mediated diseases.

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.

The Impact of Immune Response on HTLV-I in HTLV-I-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP)

Human T lymphotropic virus type I (HTLV-I) is a retrovirus which is associated with adult T cells leukaemia (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a minority of HTLV-I-infected individuals. It is not clear why a minority of HTLV-I-infected individuals develop HAM/TSP and majority remains lifelong carriers. It seems that the interaction between the virus and the immune response plays an important role in HTLV-I-associated diseases. Although the role of the immune response in HTLV-I pathogenesis is not fully understood, however it seems that the efficacy of the immune response which is involved in controlling or limiting of viral persistence determines the outcome of HTLV-I-associated diseases. Here we discuss the role of innate and adaptive immune response and also the risk factors contribute to the observed differences between HAM/TSP patients and asymptomatic HTLV-I carriers.

Humoral immune response to HTLV-1 basic leucine zipper factor (HBZ) in HTLV-1-infected individuals

Background

Human T cell lymphotropic virus type 1 (HTLV-1) infection can lead to development of adult T cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in a subset of infected subjects. HTLV-1 basic leucine zipper factor (HBZ) gene has a critical role in HTLV-1 infectivity and the development of ATL and HAM/TSP. However, little is known about the immune response against HBZ in HTLV-1-infected individuals. In this study, we examined antibody responses against HBZ in serum/plasma samples from 436 subjects including HTLV-1 seronegative donors, asymptomatic carriers (AC), ATL, and HAM/TSP patients using the luciferase immunoprecipitation system.

Results

Immunoreactivity against HBZ was detected in subsets of all HTLV-1-infected individuals but the test did not discriminate between AC, ATL and HAM/TSP. However, the frequency of detection of HBZ-specific antibodies in the serum of ATL patients with the chronic subtype was higher than in ATL patients with the lymphomatous subtype. Antibody responses against HBZ were also detected in cerebrospinal fluid of HAM/TSP patients with anti-HBZ in serum. Antibody responses against HBZ did not correlate with proviral load and HBZ mRNA expression in HAM/TSP patients, but the presence of an HBZ-specific response was associated with reduced CD4⁺ T cell activation in HAM/TSP patients. Moreover, HBZ-specific antibody inhibited lymphoproliferation in the PBMC of HAM/TSP patients.

Conclusions

This is the first report demonstrating humoral immune response against HBZ associated with HTLV-I infection. Thus, a humoral immune response against HBZ might play a role in HTLV-1 infection.

Dendritic Cells in HIV-1 and HCV Infection: Can They Help Win the Battle?

Persistent infections with human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) are a major cause of morbidity and mortality worldwide. As sentinels of our immune system, dendritic cells (DCs) play a central role in initiating and regulating a potent antiviral immune response. Recent advances in our understanding of the role of DCs during HIV-1 and HCV infection have provided crucial insights into the mechanisms employed by these viruses to impair DC functions in order to evade an effective immune response against them. Modulation of the immunological synapse between DC and T-cell, as well as dysregulation of the crosstalk between DCs and natural killer (NK) cells, are emerging as two crucial mechanisms. This review focuses on understanding the interaction of HIV-1 and HCV with DCs not only to understand the immunopathogenesis of chronic HIV-1 and HCV infection, but also to explore the possibilities of DC-based immunotherapeutic approaches against them. Host genetic makeup is known to play major roles in infection outcome and rate of disease progression, as well as response to anti-viral therapy in both HIV-1 and HCV-infected individuals. Therefore, we highlight the genetic variations that can potentially affect DC functions, especially in the setting of chronic viral infection. Altogether, we address if DCs’ potential as critical effectors of antiviral immune response could indeed be utilized to combat chronic infection with HIV-1 and HCV.

Expansion in CD39⁺ CD4⁺ immunoregulatory t cells and rarity of Th17 cells in HTLV-1 infected patients is associated with neurological complications

HTLV-1 infection is associated with several inflammatory disorders, including the neurodegenerative condition HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It is unclear why a minority of infected subjects develops HAM/TSP. CD4⁺ T cells are the main target of infection and play a pivotal role in regulating immunity to HTLV and are hypothesized to participate in the pathogenesis of HAM/TSP. The CD39 ectonucleotidase receptor is expressed on CD4⁺ T cells and based on co-expression with CD25, marks T cells with distinct regulatory (CD39⁺CD25⁺) and effector (CD39⁺CD25⁻) function. Here, we investigated the expression of CD39 on CD4⁺ T cells from a cohort of HAM/TSP patients, HTLV-1 asymptomatic carriers (AC), and matched uninfected controls. The frequency of CD39⁺ CD4⁺ T cells was increased in HTLV-1 infected patients, regardless of clinical status. More importantly, the proportion of the immunostimulatory CD39⁺CD25⁻ CD4⁺ T-cell subset was significantly elevated in HAM/TSP patients as compared to AC and phenotypically had lower levels of the immunoinhibitory receptor, PD-1. We saw no difference in the frequency of CD39⁺CD25⁺ regulatory (Treg) cells between AC and HAM/TSP patients. However, these cells transition from being anergic to displaying a polyfunctional cytokine response following HTLV-1 infection. CD39⁻CD25⁺ T cell subsets predominantly secreted the inflammatory cytokine IL-17. We found that HAM/TSP patients had significantly fewer numbers of IL-17 secreting CD4⁺ T cells compared to uninfected controls. Taken together, we show that the expression of CD39 is upregulated on CD4⁺ T cells HAM/TSP patients. This upregulation may play a role in the development of the proinflammatory milieu through pathways both distinct and separate among the different CD39 T cell subsets. CD39 upregulation may therefore serve as a surrogate diagnostic marker of progression and could potentially be a target for interventions to reduce the development of HAM/TSP.

Artificial antigen presenting cell (aAPC) mediated activation and expansion of natural killer T cells

Natural killer T (NKT) cells are a unique subset of T cells that display markers characteristic of both natural killer (NK) cells and T cells¹. Unlike classical T cells, NKT cells recognize lipid antigen in the context of CD1 molecules². NKT cells express an invariant TCRα chain rearrangement: Vα14Jα18 in mice and Vα24Jα18 in humans, which is associated with Vβ chains of limited diversity^3-6, and are referred to as canonical or invariant NKT (iNKT) cells. Similar to conventional T cells, NKT cells develop from CD4-CD8- thymic precursor T cells following the appropriate signaling by CD1d ⁷. The potential to utilize NKT cells for therapeutic purposes has significantly increased with the ability to stimulate and expand human NKT cells with α-Galactosylceramide (α-GalCer) and a variety of cytokines⁸. Importantly, these cells retained their original phenotype, secreted cytokines, and displayed cytotoxic function against tumor cell lines. Thus, ex vivo expanded NKT cells remain functional and can be used for adoptive immunotherapy. However, NKT cell based-immunotherapy has been limited by the use of autologous antigen presenting cells and the quantity and quality of these stimulator cells can vary substantially. Monocyte-derived DC from cancer patients have been reported to express reduced levels of costimulatory molecules and produce less inflammatory cytokines^9,10. In fact, murine DC rather than autologous APC have been used to test the function of NKT cells from CML patients¹¹. However, this system can only be used for in vitro testing since NKT cells cannot be expanded by murine DC and then used for adoptive immunotherapy. Thus, a standardized system that relies on artificial Antigen Presenting Cells (aAPC) could produce the stimulating effects of DC without the pitfalls of allo- or xenogeneic cells^{12, 13}. Herein, we describe a method for generating CD1d-based aAPC. Since the engagement of the T cell receptor (TCR) by CD1d-antigen complexes is a fundamental requirement of NKT cell activation, antigen: CD1d-Ig complexes provide a reliable method to isolate, activate, and expand effector NKT cell populations.

Connecting the dots: artificial antigen presenting cell-mediated modulation of natural killer T cells

Natural killer T (NKT) cells constitute an important subset of T cells that can both directly and indirectly mediate antitumor immunity. However, we and others have reported that cancer patients have a reduction in both NKT cell number and function. NKT cells can be stimulated and expanded with α-GalCer and cytokines and these expanded NKT cells retain their phenotype, remain responsive to antigenic stimulation, and display cytotoxic function against tumor cell lines. These data strongly favor the use of ex vivo expanded NKT cells in adoptive immunotherapy. NKT cell based-immunotherapy has been limited by the use of autologous antigen-presenting cells, which can vary substantially in their quantity and quality. A standardized system that relies on artificial antigen-presenting cells (aAPCs) could produce the stimulating effects of dendritic cell (DC) without the pitfalls of allo- or xenogeneic cells. In this review, we discuss the progress that has been made using CD1d-based aAPC and how this acellular antigen presenting system can be used in the future to enhance our understanding of NKT cell biology and to develop NKT cell-specific adoptive immunotherapeutic strategies.

Long-term persistence of limited HTLV-I Tax-specific cytotoxic T cell clones in a patient with adult T cell leukemia/lymphoma after allogeneic stem cell transplantation

PURPOSE

Adult T cell leukemia/lymphoma (ATL) is a highly aggressive malignancy of T cells caused by human T cell lymphotropic virus type 1 (HTLV-1). Recent clinical studies have suggested that allogeneic stem cell transplantation (HSCT) improves the clinical course of ATL by harnessing a graft-versus-ATL effect, and that donor-derived HTLV-1 Tax-specific CD8(+) cytotoxic T cells (CTLs) contribute to the graft-versus-ATL effect after HSCT. However, little is known about the immunological characteristics of Tax-specific CTLs in ATL patients who underwent HSCT.

METHODS

We serially analyzed frequencies, differentiation, functions and clonal dynamics of Tax-specific CTLs in paired samples of peripheral blood (PB) and bone marrow (BM) from an ATL patient after HSCT at the single-cell level. We used flowcytometric and single-cell T cell receptor (TCR) repertoire analysis methods without culture steps.

RESULTS

Donor-derived Tax-specific CTLs effectively suppressed HTLV-1 replication in both PB and BM at least during chronic graft-versus-host disease after HSCT. Furthermore, Tax-specific CTLs had comparable properties between BM and PB, except for preferential accumulation in BM rather than PB. Tax-specific CTLs persistently existed as less-differentiated CD45RA(-)CCR7(-) effector memory CTLs based on predominant phenotypes of CD27(+), CD28(+/-) and CD57(+/-). Our approach using single-cell TCR repertoire analysis method showed highly restricted oligoclonal responses of Tax-specific CTLs, and TCR BV7- or BV30- expressing two predominant CTL clones persistently existed and maintained strong cytotoxic activities against HTLV-1 in both PB and BM over three years after HSCT.

CONCLUSIONS

These findings about Tax-specific CTLs provide insights into future directions for studies on immunotherapy against ATL.

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.

Stable and transient periodic oscillations in a mathematical model for CTL response to HTLV-I infection

The cytotoxic T lymphocyte (CTL) response to the infection of CD4+ T cells by human T cell leukemia virus type I (HTLV-I) has previously been modelled using standard response functions, with relatively simple dynamical outcomes. In this paper, we investigate the consequences of a more general CTL response and show that a sigmoidal response function gives rise to complex behaviours previously unobserved. Multiple equilibria are shown to exist and none of the equilibria is a global attractor during the chronic infection phase. Coexistence of local attractors with their own basin of attractions is the norm. In addition, both stable and unstable periodic oscillations can be created through Hopf bifurcations. We show that transient periodic oscillations occur when a saddle-type periodic solution exists. As a consequence, transient periodic oscillations can be robust and observable. Implications of our findings to the dynamics of CTL response to HTLV-I infections in vivo and pathogenesis of HAM/TSP are discussed.

Reduced Tim-3 expression on human T-lymphotropic virus type I (HTLV-I) Tax-specific cytotoxic T lymphocytes in HTLV-I infection

T cell immunoglobulin and mucin domain-containing molecule-3 (Tim-3) and programmed cell death-1 (PD-1) are T cell exhaustion molecules. We investigated the expression of Tim-3 and PD-1 in human T-lymphotropic virus type I (HTLV-I) infection. Tim-3 expression, but not PD-1 expression, was reduced on CD4(+) and CD8(+) T cells of HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients and HTLV-I carriers as compared with healthy controls. Tim-3 expression was also reduced in HTLV-I Tax-specific cytotoxic T lymphocytes (CTLs) as compared with cytomegalovirus-specific CTLs. Tim-3(+), but not PD-1(+), Tax-specific CTLs produced less interferon-γ and exhibited low cytolytic activity. However, we observed no difference in the expression of Tim-3 or cytolytic activity between Tax-specific CTLs of HAM/TSP patients or carriers. Moreover, HTLV-I-infected CD4(+) T cells showed decreased Tim-3 expression. These data suggest that Tim-3 expression is reduced in HTLV-I infection and that a high number of Tim-3(-) HTLV-I-specific CTLs preserves their cytolytic activity, thereby controlling viral replication.