Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic inflammatory disease driven by HTLV-1-infected CD4+ T cells; however, the phenotypic and functional characteristics of disease-associated T-cell subsets remain incompletely understood. We analyzed samples using flow cytometry (n = 3–5 per group) and RNA-seq (n = 13), focusing on CADM1highCD4+ T cells enriched for HTLV-1-infected cells to evaluate a transferrin receptor (TfR)-expressing subset. TfR+CADM1highCD4+ T cells were detected in both asymptomatic carriers and patients with HAM, but their frequency among CD4+ T cells was higher in HAM patients. These cells exhibited a Treg-like phenotype with higher Foxp3 and CTLA-4 expression than TfR− cells and showed increased Ki-67 positivity, consistent with proliferation. Despite this phenotype, they produced interferon-γ, indicating inflammatory potential, while Foxp3 expression was lower in HAM patients than in asymptomatic carriers, suggesting a more inflammatory phenotype. Furthermore, TfR transcript levels (RNA-seq TPM) correlated with clinical indicators of disease activity, including neopterin and CXCL10 protein levels, and the Osame motor disability score. Collectively, these findings suggest that TfR identifies a proliferative, Foxp3-low, Treg-like inflammatory CD4+ T-cell subset that is associated with disease activity in HAM.

Human T-cell leukemia virus type 1 (HTLV-1) establishes lifelong infection and is associated with severe diseases such as adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Cytotoxic T lymphocytes (CTLs), especially those specific for the viral protein Tax, play a pivotal role in controlling HTLV-1 infection. However, conventional humanized mouse models fail to fully reconstitute human immune responses, limiting their utility for evaluating CTL-mediated immunity. This study aimed to establish a physiologically relevant in vivo model to investigate human CTL responses against HTLV-1. To achieve this, we utilized NOG-HLA-A02 transgenic (Tg) mice expressing human HLA-A02:01 on thymic epithelial cells, enabling proper development of HLA-restricted human T cells. Compared to conventional humanized NOG mice, HTLV-1-infected humanized NOG-HLA-A02 Tg mice exhibited significantly reduced HTLV-1 proviral load (PVL), decreased expansion of infected CD4+ T cells, a trend toward increased frequencies of Tax-specific CD8+ T cells, and prolonged survival. These results demonstrate that the expression of HLA-A02:01 facilitates robust CTL-mediated immune control of HTLV-1. This model provides a powerful platform for dissecting HTLV-1 immunopathogenesis and evaluating CTL-targeted therapeutic strategies, including vaccines and immune checkpoint inhibitors.

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy (HAM) after a long latent period in a fraction of infected individuals. These HTLV-1-infected cells typically have phenotypes similar to that of CD4+T cells, but the cell status is not well understood. To extract the inherent information of HTLV-1-infected CD4+ cells, we integratively analyzed the ATAC-seq and RNA-seq data of the infected cells. Compared to CD4+T cells from healthy donors, we found anomalous chromatin accessibility in HTLV-1infected CD4+ cells derived from ATL cases in terms of location and sample-to-sample fluctuations in open chromatin regions. Further, by focusing on systematically selected genes near the open chromatin regions, we quantified the difference between the infected CD4+ cells in ATL cases and healthy CD4+T cells in terms of the correlation between the chromatin structures and the gene expressions. Based on a further analysis of chromatin accessibility, we detected TLL1 (Tolloid Like 1) as one of the key genes that exhibit unique gene expressions in ATL cases. A luciferase assay indicated that TLL1 has an isoform-dependent regulatory effect on TGF-β. Overall, this study provides results about the status of HTLV-1-infected cells, which are qualitatively consistent across the different scales of chromatin accessibility, transcription, and immunophenotype.

Human T-cell leukemia virus type 1 (HTLV-1) infects mainly CD4+ T lymphocytes and causes both malignant and inflammatory diseases: the aggressive malignancy known as Adult T-cell leukemia/lymphoma (ATL) and several chronic inflammatory syndromes. HTLV-1 infection is established by integration of proviral DNA ( 9000 bp) into the host genome. In HTLV-1, two viral genes, tax and HBZ, play critical roles in viral transcription and promotion of T-cell proliferation, respectively. The present study was undertaken to test the hypothesis that the higher-order structure of proviral chromatin regulates its transcription on both the plus strand and the minus strand. ATAC-seq analysis identified an open chromatin region in the pol gene of proviral DNA, which we name IPOR, in many ATL cases. Using reporter assays, it was found that the sequence of IPOR suppresses the transcription of the plus strand and activates that of the minus strand. Binding motifs of Eomes and TEAD proteins were predicted in this region, and we confirmed recruitment of the transcription factors to their respective motifs by ChIP-qPCR. A mutant of IPOR which cannot bind the transcription factors weakened the transcriptional activating effects compared with the wild type, suggesting that the IPOR and those transcription factors suppress the 5' long terminal repeat (LTR) but activate the 3'LTR. In addition, a mutant HTLV-1 molecular clone, which possesses the IPOR mutant, produced a higher titer of virus than the wild type. RNA-seq analysis of HTLV-1-infected cell lines, in which Tax expression can be traced after induction, revealed that EOMES expression decreases during the tax transcriptional burst and resumes following termination of the burst. These findings suggested that the expression dynamics of Eomes affect the transient expression of Tax. The IPOR sequence appears to regulate the transcription from both LTRs, suppressing the 5'LTR but activating the 3'LTR. Recruitment of Eomes to the IPOR is likely to influence the expression of Tax and HBZ. Since both viral genes are involved in diverse mechanisms for viral replication, cellular proliferation, and immune regulation, the IPOR may play a role in fine-tuning the modes of viral persistence in vivo.

Striatal cholinergic interneurons (ChIs) play a key modulatory role in basal ganglia circuits and is increasingly recognized as contributors to levodopa-induced dyskinesia (LID) development and expression in Parkinson's disease (PD). We aimed to investigate whether zonisamide (ZNS) exhibits the potential contribution of the cholinergic system to the antidyskinetic effects. Unilateral PD model rats were treated with levodopa and/or ZNS. Two weeks post-treatment, LID severity was assessed, and striatal mRNA expression levels for muscarinic M1 (Chrm1) and M4 (Chrm4) receptors, and nicotinic α7 (Chrnα7) and β2 (Chrnβ2) subunits, as well as prodynorphin (Pdyn) and proenkephalin (Penk), were analyzed using real-time RT-PCR. Additionally, the proportion of striatal phosphorylated extracellular signal-regulated kinase (pERK)-positive ChIs was observed using immunohistochemistry. LID was absent in ZNS (Group Z) or saline + DMSO-treated (Group N) rats but pronounced in levodopa-treated rats (Group I). Rats receiving both levodopa and ZNS (Group IZ) showed less-pronounced LID and increased locomotive activity compared with Group I. Chrm1, Chrm4, Chrnα7, and Chrnβ2 receptor mRNA levels remained unchanged in Groups N and I. Conversely, Chrm1, Chrm4, and Chrnβ2 receptor mRNA levels were reduced in Group Z, whereas all receptor mRNAs were downregulated in Group IZ. Additionally, the proportion of striatal pERK-positive ChIs significantly increased in Group I, whereas its reduction was observed in Group IZ. These findings suggest that ZNS may serve as a dual-purpose therapy by potentially alleviating LID while maintaining locomotor function, possibly through the suppression of striatal ChI overactivity and downregulation of acetylcholine receptor expression.

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic neurodegenerative disease. This multicenter, randomized phase 3 study evaluated the efficacy and safety of 0.3 mg/kg intravenous mogamulizumab, a monoclonal antibody targeting-CC chemokine receptor 4, every 12 weeks in HAM/TSP patients. This study comprised a 24-week double-blind, placebo-controlled period, 24-week open-label period, and extension treatment period. The primary endpoint was the proportion of patients with a ≥ 1-grade improvement in the Osame motor disability score (OMDS). Secondary endpoints were changes in HTLV-1 proviral load, 10-m timed walk, cerebrospinal fluid (CSF) neopterin levels, and safety. The exploratory endpoint was CSF chemokine C-X-C motif ligand 10 (CXCL10) levels. Thirty-four and 33 patients were randomized to mogamulizumab and placebo arms, respectively. At the end of the double-blind period, no significant difference was found in the OMDS improvement rate or other secondary efficacy endpoints assessing motor activities. However, the mogamulizumab arm showed a significant decrease in HTLV-1 proviral load (− 59.39 ± 29.91% vs. placebo 2.32 ± 36.31%) and CSF neopterin ( p < 0.001)/CXCL10 levels ( p = 0.004). The baseline OMDS pattern and the 60–80% HTLV-1 proviral load reduction were sustained through the open-label and extension treatment periods. Although a higher incidence of rash (69.2%) was reported, the safety profile was similar compared with a previous phase 1/2a study. We found no significant difference in clinical benefit; however, mogamulizumab may provide long-term clinical benefit by preventing disease progression, as CSF neopterin/CXCL10 levels are associated with long-term prognosis in HAM/TSP. Clinical Trial Registration Number: NCT03191526 (registered date: 6-June-2017).

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.

Rationale and Objectives: To evaluate the prevalence, size, and characteristics of gynecomastia on thoracic computed tomography (CT) in patients with spinal and bulbar muscular atrophy (SBMA) or amyotrophic lateral sclerosis (ALS), compared to those of patients with myasthenia gravis (as controls).Materials and Methods: A total of 189 male patients (SBMA [n = 15]; ALS [n = 76]; control [n = 98]) who underwent thoracic computed tomography were included. The size of breast glandular tissue diameters, and characteristic of CT-depicted gynecomastia were com-pared.Results: On multivariate logistic regression analysis, mean breast glandular tissue diameter (adjusted odds ratio [aOR] 1.13, 95% confi-dence interval [CI] 1.08-1.19), maximum breast glandular tissue diameter (aOR 1.14, 95% CI 1.08-1.20), prevalence of CT-depicted gynecomastia (aOR 21.71, 95% CI 5.39-87.38), dendritic or diffuse pattern of gynecomastia (aOR 35.30, 95% CI 8.02-155.40), and bilat-eral gynecomastia (aOR 41.96, 95% CI 10.20-172.69) were positively associated with SBMA, but not ALS. On receiver operating charac-teristic (ROC) analysis, the area under the curve of the mean breast tissue diameter for predicting SBMA was 0.92 with the optimal cutoff value of 16.5 mm. The ROC analysis showed that a maximum breast tissue diameter of 18.6 mm can also effectively distinguish SBMA from controls.Conclusion: These findings suggest that the evaluation of breast glandular tissue on thoracic CT could be a screening examination to dis-tinguish SBMA patients and assist in its differential diagnosis.

Significance Human T cell leukemia virus type 1 (HTLV-1) proviral load is associated with the risk of developing HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP) and several small-scale candidate gene approaches have also identified associations of particular HLA alleles with HAM/TSP risk. However, no large-scale genome-wide association (GWA) studies have been performed to date. By a large-scale GWA study and comprehensive genotyping of classical HLA genes, we found that HLA-DRB1 alleles carrying leucine at the antigen presentation groove domain (DRB1-GB-7-Leu) increased the susceptibility to HAM/TSP. Individuals who were homozygous for DRB1-GB-7-Leu had a ninefold increased odds of developing HAM/TSP. This effect of DRB1-GB-7-Leu was independent of proviral load. These findings identify DRB1-GB-7-Leu as a genetic risk marker of HAM/TSP development.

Glutamate, GABA, acetylcholine, dopamine, and serotonin interact with each other to regulate the flow of neural information in the striatum. Serotonin type 1A receptor (5HT1A) is primarily expressed on glutamatergic nerve terminals, and 5HT1B is expressed on GABAergic medium spiny neurons (MSNs). Zonisamide (ZNS) reportedly improves the off period without worsening levodopa-induced dyskinesia (LID) in patients with advanced Parkinson's disease. In this study, LID model rats were prepared by administrating levodopa to unilaterally 6-OHDA-lesioned rats. We analyzed changes in serotonergic neurotransmission of LID model rats to elucidate the relationship between LID and the serotonergic system and pathomechanism of the anti-dyskinetic effects of ZNS. Abnormal involuntary movements (AIMs) were most severe in intermittently levodopa-treated rats but milder in rats intermittently medicated with levodopa and ZNS. Continuously levodopa-infused rats or intermittently ZNS-injected rats did not develop AIMs, and no differences in the expression of brain-derived neurotrophic factor, 5-HT transporter, 5HT1A, and 5HT1B mRNA between the lesioned striatum and normal side were observed. Expression of 5HT1B mRNA was elevated in the lesioned striatum of intermittently levodopa-treated rats, but this elevation was normalized by concomitant use of ZNS. The severity of AIMs was correlated with the ratio of 5HT1B to 5HT1A mRNA expression in the lesioned striatum, indicating that the anti-LID effect of ZNS is based on inhibition via 5HT1B receptors to direct pathway MSNs sensitized by intermittent levodopa treatment. Selectively acting serotonergic drugs, especially those that lower the 5HT1B to 5HT1A ratio, are promising new therapeutic agents to attenuate LID development.

The objective was to evaluate the long-term efficacy and safety of tacrolimus monotherapy in myasthenia gravis (MG) patients. Immunosuppressive drug-naïve MG patients were administered tacrolimus, followed by thymectomy in some of the cases according to the clinical guideline for MG. Additional aggressive immunosuppressive therapies were allowed if the patients without thymectomy did not achieve minimal manifestation (MM) or better status after 3 weeks of tacrolimus administration or in the thymectomized patients by 1-2 weeks after the operation (i.e., 1st evaluation). Of all 14 patients included in this study, 8 of them (57%) achieved MM or better status at the 1st evaluation, and the remaining 6 (43%), who had failed to gain MM or better status at the 1st evaluation, also achieved MM or better status with 1 course of aggressive immunosuppressive therapy. The quantitative MG (QMG) scores, MG-Activities of Daily Living (ADL) scales, and anti-acetylcholine receptor (AchR) antibody levels were significantly decreased at 6 months and maintained thereafter. At the end of the follow-up period (41-70 months), all patients were in MM or better status. None of the patients experienced severe adverse effects. Our small preliminary study indicates that long-term tacrolimus monotherapy is possibly effective and safe for MG patients.

Human T-lymphotropic virus type 1 (HTLV-1)–associated myelopathy/tropical spastic paraparesis (HAM/TSP) is chronic myelopathy characterized by slowly progressive spastic paraparesis and urinary dysfunction. A few biomarkers in the cerebrospinal fluid are known to be related to disease activity, but no biomarker has been reported in peripheral blood. This study aims to explore the expression level of the adhesion molecule during the expression level of the adhesion molecule among HAM/TSP disease activity. In lymphocyte function–associated antigen 1 and DNAX accessory molecule 1, no variation in expression levels specific to HTLV-1 infection was observed in CD4-positive T cells; however, TSLC1 expression was higher in HAM patients than in asymptomatic carriers and non-infected persons. TSLC1 tended to be higher in patients whose symptoms were worsening. On the contrary, the expression level of TSLC1 in CD8-positive T cells was lower in HAM patients than in asymptomatic carriers, and this tendency was stronger in patients whose symptoms had deteriorated. No significant correlation was found between TSLC1 and either of the transcription factors Tax or HBZ in any T cell group. Therefore, TSLC1 expression in CD4-positive T cells might be a useful biomarker of HAM/TSP disease activity.

Adult T-cell leukemia and human T-cell leukemia virus type 1 (HTLV-1) - associated myelopathy/tropical spastic paraparesis, which develop after HTLV-1 infection, are difficult to cure. In particular, the mode of HTLV-1 propagation is not well understood. Poly (ADP-ribose) polymerase-1 is reported to be a co-activator of HTLV-1 Tax protein; however, the effects of polyADP-ribosylation on infectivity of HTLV-1 have not been fully clarified. We studied the effects of a PARP inhibitor on two modes of HTLV-1 transmission: through cell adhesion between MT-2 cells (an HTLV-1-infected cell line) and uninfected cells and through virus particles produced by HTLV-1-producing c77 cells. Although the PARP inhibitor decreased HTLV-1 infection through cell adhesion, it increased HTLV-1 infection through virion production and caused apoptosis of HTLV-1-infected cells. Thus, careful consideration is required for clinical application of PARP inhibitors in HTLV-1 patients.

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma (ATL). Following viral infection with HTLV-1, certain infected cells exhibit clonal proliferation. Additional genetic and epigenetic changes in these clonally proliferating cells provide them with the selective advantage of growth, which eventually results in ATL. The precise mechanism, however, has yet to be completely elucidated. It has previously been established that APOBEC3 enzymes are potent host-antiviral restriction factors. Conversely, previous studies have reported that the A3B level is increased in tumor virus infections, such as those caused by HBV and HPV, suggesting that A3B exerts a function as a mutagen. Therefore, the present study analyzed the expression of APOBEC3 family members in various HTLV-1 infection states. No significant differences were observed in the expression between healthy donors and patients with HTLV-1-associated myelopathy. Although no significant changes in the expressions of A3C, A3D, A3F and A3G between uninfected and HTLV-1-infected mice were observed, an increased A3B expression was observed in a short-term humanized mouse model following HTLV-1 infection. In a long-term humanized mouse model following HTLV-1 infection, the gene expression array data exhibited an apparent increase in A3B and CADM1, which are indicators of ATL. Collectively, the results of the present study suggest that A3B is likely involved in the development of ATL in HTLV-1-infected humanized mice.

Adult T-cell leukemia is one of the life-threatening diseases that occur in individuals infected with human T-cell leukemia virus type 1 (HTLV-1). Clinical trials of hematopoietic stem cell transplantation therapy are being performed in addition to chemotherapy; however, neither is satisfactory. As a pretreatment for transplantation, anticancer drugs or whole-body irradiation is used to decrease the number of HTLV-1-infected cells, but there are numerous side effects. Therefore, in the present study, using a mouse model of HTLV-1 infection, the long-term survival and number of infected cells in the reservoir organ were investigated in order to determine the effect of γ-irradiation on HTLV-1-infected mice in vivo. There was no improvement in the survival period following γ-irradiation in the γ-irradiated group after HTLV-1 infection when compared with the HTLV-1-infected group. It was also found that the incidence of splenomegaly was ≥80% in the HTLV-1-infected and γ-irradiated group, which was significantly higher than that in the HTLV-1-infected mice. The tissue morphology in the spleen became non-uniform because of γ-rays. Importantly, the number of infected cells in the spleen was increased 4.1-fold in the HTLV-1-infected and γ-irradiated mice compared with that in the HTLV-1-infected mice. Careful consideration might be necessary when using whole-body irradiation in patients with HTLV-1 infection.

Millions of people are infected with human T-lymphotropic virus type 1 (HTLV-1) worldwide; notable endemic areas include Brazil, the Caribbean islands, Iran, and Japan. A small number of those infected develop the progressive neurodegenerative disease HTLV-1-associated myelopathy (HAM), also known as tropical spastic paraparesis (TSP), which is characterized by chronic spinal cord inflammation and accompanying myelopathic symptoms. The corticosteroid prednisolone (PSL) is a classic treatment for HAM/TSP, yet its effectiveness remains controversial owing to insufficient and conflicting studies. We conducted a multicenter retrospective study using data collected by physicians monitoring patients with HAM/TSP at 7 hospitals throughout Japan. The Osame Motor Disability Score (OMDS) was used to evaluate 57 patients treated with low-dose PSL (mean 4.8 mg/day) versus 29 untreated patients. Roughly half of the evaluations spanned < 3 years (Short-Term) and half > 3 years (Long-Term), with a mean of 3.4 years. While the OMDS of most untreated patients remained unchanged in the Short-Term (87%) and worsened in the Long-Term (79%), most treated patients improved in the Short-Term (52%) and remained unchanged or improved in the Long-Term (68%). Overall, the mean change in OMDS per year was –0.13 in the Steroids group and +0.12 in the Untreated group (p < 0.01). This study addressed the effectiveness of PSL for HAM/TSP in 3 novel ways: 1) continuous low-dose administration; 2) comparison with an untreated group; and 3) Long-Term evaluation. These findings provide robust evidence supporting PSL maintenance therapy for HAM/TSP.

•We describe an autopsy case of acute myelitis resembling human T-lymphotropic virus type 1-associated myelopathy (HAM) combined with adult T-cell leukemia/lymphoma.•The histopathological findings in the spinal cord were compatible with those of HAM. There was no leukemic infiltration in the spinal cord.

Human T-cell leukemia virus type 1 (HTLV-1) infects mainly CD4(+)CCR4(+) effector/memory T cells in vivo. However, it remains unknown whether HTLV-1 preferentially infects these T cells or this virus converts infected precursor cells to specialized T cells. Expression of viral genes in vivo is critical to study viral replication and proliferation of infected cells. Therefore, we first analyzed viral gene expression in non-human primates naturally infected with simian T-cell leukemia virus type 1 (STLV-1), whose virological attributes closely resemble those of HTLV-1. Although the tax transcript was detected only in certain tissues, Tax expression was much higher in the bone marrow, indicating the possibility of de novo infection. Furthermore, Tax expression of non-T cells was suspected in bone marrow. These data suggest that HTLV-1 infects hematopoietic cells in the bone marrow. To explore the possibility that HTLV-1 infects hematopoietic stem cells (HSCs), we analyzed integration sites of HTLV-1 provirus in various lineages of hematopoietic cells in patients with HTLV-1 associated myelopathy/ tropical spastic paraparesis (HAM/TSP) and a HTLV-1 carrier using the high-throughput sequencing method. Identical integration sites were detected in neutrophils, monocytes, B cells, CD8(+) T cells and CD4(+) T cells, indicating that HTLV-1 infects HSCs in vivo. We also detected Tax protein in myeloperoxidase positive neutrophils. Furthermore, dendritic cells differentiated from HTLV-1 infected monocytes caused de novo infection to T cells, indicating that infected monocytes are implicated in viral spreading in vivo. Certain integration sites were re-detected in neutrophils from HAM/TSP patients at different time points, indicating that infected HSCs persist and differentiate in vivo. This study demonstrates that HTLV-1 infects HSCs, and infected stem cells differentiate into diverse cell lineages. These data indicate that infection of HSCs can contribute to the persistence and spread of HTLV-1 in vivo.