HTLV-1 induces a Th1-like state in CD4+CCR4+ T cells that produces an inflammatory positive feedback loop via astrocytes in HAM/TSP

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.

Targeted immunotherapy for HTLV-1-associated myelopathy: a step in the right direction

This scientific commentary refers to ‘Long-term safety and efficacy of mogamulizumab (anti-CCR4) for treating virus-associated myelopathy’ by Sato et al. (https://doi.org/10.1093/brain/awad139).

Retroviral b-Zip protein (HBZ) contributes to the release of soluble and exosomal immune checkpoint molecules in the context of neuroinflammation

HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive, neuroinflammatory demyelinating condition of the spinal cord. We have previously shown that aberrant expression and activity of immune checkpoint (ICP) molecules such as PD-1 and PD-L1/PD-L2, negatively associates with the cytolytic potential of T cells in individuals with HAM/TSP. Interestingly, ICPs can exist in a soluble cell-free form and can be carried on extracellular vesicles (EVs) and exosomes (small EVs, <300nm) while maintaining their immunomodulatory activity. Therefore, we investigated the role of soluble and exosomal ICPs in HTLV-1 associated neuroinflammation. For the very first time, we demonstrate a unique elevated presence of several stimulatory (CD27, CD28, 4-1BB) and inhibitory (BTLA, CTLA-4, LAG-3, PD-1, PD-L2) ICP receptors in HAM/TSP sera, and in purified exosomes from a HAM/TSP-derived HTLV-1-producing (OSP2) cells. These ICPs were found to be co-localized with the endosomal sorting complex required for transport (ESCRT) pathway proteins and exhibited functional binding with their respective ligands. Viral proteins and cytokines (primarily IFNγ) were found to be present in purified exosomes. IFNγ exposure enhanced the release of ICP molecules while antiretroviral drugs (Azidothymidine and Lopinavir) significantly inhibited this process. HTLV-1 b-Zip protein (HBZ) has been linked to factors that enhance EV release and concurrent knockdown here led to the reduced expression of ESCRT associated genes (eg. Hrs, Vsp4, Alix, Tsg101) as well as abrogated the release of ICP molecules, suggesting HBZ involvement in this process. Moreso, exosomes from OSP2 cells adversely affected CD8 T-cell functions by dimishing levels of cytokines and cytotoxic factors. Collectively, these findings highlight exosome-mediated immunmodulation of T-cell functions with HBZ and ESCRT pathways as an underlying mechanism in the context of HTLV-1-induced neuroinflammation.

Immunopathogenesis of viral infections in neurological autoimmune disease

Autoimmune diseases develop due to self-tolerance failure in recognizing self and non-self-antigens. Several factors play a role in inducing autoimmunity, including genetic and environmental elements. Several studies demonstrated the causative role of viruses; however, some studies showed the preventive effect of viruses in the development of autoimmunity. Neurological autoimmune diseases are classified based on the targets of autoantibodies, which target intracellular or extracellular antigens rather than neurons. Several theories have been hypothesized to explain the role of viruses in the pathogenesis of neuroinflammation and autoimmune diseases. This study reviewed the current data on the immunopathogenesis of viruses in autoimmunity of the nervous system.

Viral co-infections in leprosy: a scoping review

CONTEXT

The most reported viral co-infections in leprosy are human immunodeficiency virus (HIV), human T-cell lymphotropic virus (HTLV), hepatitis B virus (HBV), hepatitis C virus (HCV), and SARS-CoV-2. In co-infections, the burden of an agent can be increased or decreased by the presence of others. To address this issue, we need to fully understand their prevalence, risk factors, immunology, clinical manifestations, and treatment. The purpose of this scoping review is to describe the clinical and epidemiological characteristics of the most reported viral co-infections in leprosy to inform clinicians and guide future research.

METHODS

The authors conducted a literature search of five databases for articles on each of the aforementioned co-infections published prior to October 2022. Two independent reviewers conducted the selection process and identified 53 papers meeting the study inclusion criteria. The data extraction process and evidence synthesis were conducted by one reviewer and double-checked by a second one, consistent with best practice recommendations for scoping reviews.

RESULTS

For all assessed viruses, most studies reported prevalence rates in leprosy patients higher than the general population. Studies found that HTLV, HBV, and HCV chronic infections were highest in multibacillary leprosy, whereas HIV was mostly found in paucibacillary leprosy, and SARS-Cov-2 affected leprosy subtypes equally. Overall, co-infections were also associated with higher rates of leprosy reactions, except for COVID-19. Forty-six percent of the studies discussed issues related to treatment, which led to favorable outcomes for the most part.

CONCLUSIONS

This review summarizes the existing literature on viral co-infections in leprosy patients, generating valuable insights and recommending areas for future research.

Viral-induced neuroinflammation: Different mechanisms converging to similar exacerbated glial responses

There is increasing evidence that viral infections are the source/origin of various types of encephalitis, encephalomyelitis, and other neurological and cognitive disorders. While the involvement of certain viruses, such as the Nipah virus and measles virus, is known, the mechanisms of neural invasion and the factors that trigger intense immune reactions are not fully understood. Based on recent publications, this review discusses the role of the immune response, interactions between viruses and glial cells, and cytokine mediators in the development of inflammatory diseases in the central nervous system. It also highlights the significant gaps in knowledge regarding these mechanisms.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Following the Clues: Usefulness of Biomarkers of Neuroinflammation and Neurodegeneration in the Investigation of HTLV-1-Associated Myelopathy Progression

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurodegenerative disease due to axonal damage of the corticospinal secondary to an inflammatory response against infected T-cells. In the present work, we aimed to evaluate biomarkers of neurodegeneration and neuroinflammation in the definition of HAM/TSP prognosis. Neurofilament light (NfL) and phosphorylated heavy (pNfH) chains, total Tau protein, cellular prion protein (PrPc), inflammatory chemokines, and neopterin were quantified in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n=21), HTLV-1 asymptomatic carriers (AC) (n=13), and HTLV-1 seronegative individuals with non-inflammatory non-degenerative neurological disease (normal-pressure hydrocephalus) (n=9) as a control group. HTLV-1 proviral load in peripheral blood mononuclear cells and the expression of chemokine receptors CCR4, CCR5, and CXCR3 in infected CD4⁺ T-cells (HTLV-1 Tax⁺ cells) were also assessed. CSF levels of Tau, NfL, and pNfH were similar between groups, but PrPc and neopterin were elevated in HAM/TSP patients. Most individuals in the control group and all HTLV-1 AC had CSF/serum neopterin ratio < 1.0, and two-thirds of HAM/TSP patients had ratio values > 1.0, which positively correlated with the speed of disease progression and pNfH levels, indicating active neuroinflammation. HAM/TSP patients showed high serum levels of CXCR3-binding chemokines (CXCL9, CXCL10, and CXCL11) and elevated CSF levels of CCL2, CCL3, CCL4, CCL17, CXCL5, CXCL10, and CXCL11. Indeed, CXCL10 concentration in CSF of HAM/TSP patients was 5.8-fold and 8.7-fold higher in than in HTLV-1 AC and controls, respectively, and correlated with CSF cell counts. HAM/TSP patients with typical/rapid disease progression had CSF/serum CXCL10 ratio > 1.0 and a higher frequency of CXCR3⁺Tax⁺CD4⁺ T-cells in blood, which indicated a positive gradient for the migration of infected cells and infiltration into the central nervous system. In conclusion, the slow progression of HAM/TSP abrogates the usefulness of biomarkers of neuronal injury for the disease prognosis. Thus, markers of inflammation provide stronger evidence for HAM/TSP progression, particularly the CSF/serum neopterin ratio, which may contribute to overcome differences between laboratory assays.

CCR4 as a Therapeutic Target for Cancer Immunotherapy

Simple Summary

CCR4 is a chemokine receptor selectively expressed on normal T cell subsets such as type 2 helper T cells, skin-homing T cells and regulatory T cells, and on skin-associated T cell malignancies such as adult T cell leukemia/lymphoma (ATLL), which is etiologically associated with human T lymphocyte virus type 1 (HTLV-1), and cutaneous T cell lymphomas (CTCLs). Mogamulizumab is a fully humanized and glyco-engineered monoclonal anti-CCR4 antibody used for the treatment of refractory/relapsed ATLL and CTCLs, often resulting in complete remission. The clinical applications of Mogamulizumab are now being extended to solid tumors, exploring the therapeutic effect of regulatory T cell depletion. This review overviews the expression of CCR4 in various T cell subsets, HTLV-1-infected T cells, ATLL and CTCLs, and the clinical applications of Mogamulizumab.

Abstract

CCR4 is a chemokine receptor mainly expressed by T cells. It is the receptor for two CC chemokine ligands, CCL17 and CCL22. Originally, the expression of CCR4 was described as highly selective for helper T type 2 (Th2) cells. Later, its expression was extended to other T cell subsets such as regulatory T (Treg) cells and Th17 cells. CCR4 has long been regarded as a potential therapeutic target for allergic diseases such as atopic dermatitis and bronchial asthma. Furthermore, the findings showing that CCR4 is strongly expressed by T cell malignancies such as adult T cell leukemia/lymphoma (ATLL) and cutaneous T cell lymphomas (CTCLs) have led to the development and clinical application of the fully humanized and glyco-engineered monoclonal anti-CCR4 Mogamulizumab in refractory/relapsed ATLL and CTCLs with remarkable successes. However, Mogamulizumab often induces severe adverse events in the skin possibly because of its efficient depletion of Treg cells. In particular, treatment with Mogamulizumab prior to allogenic hematopoietic stem cell transplantation (allo-HSCT), the only curative option of these T cell malignancies, often leads to severe glucocorticoid-refractory graft-versus-host diseases. The efficient depletion of Treg cells by Mogamulizumab has also led to its clinical trials in advanced solid tumors singly or in combination with immune checkpoint inhibitors. The main focus of this review is CCR4; its expression on normal and malignant T cells and its significance as a therapeutic target in cancer immunotherapy.

Strongyloides stercoralis and HTLV-1 coinfection in CD34+ cord blood stem cell humanized mice: Alteration of cytokine responses and enhancement of larval growth

Viral and parasitic coinfections are known to lead to both enhanced disease progression and altered disease states. HTLV-1 and Strongyloides stercoralis are co-endemic throughout much of their worldwide ranges resulting in a significant incidence of coinfection. Independently, HTLV-1 induces a Th1 response and S. stercoralis infection induces a Th2 response. However, coinfection with the two pathogens has been associated with the development of S. stercoralis hyperinfection and an alteration of the Th1/Th2 balance. In this study, a model of HTLV-1 and S. stercoralis coinfection in CD34+ umbilical cord blood hematopoietic stem cell engrafted humanized mice was established. An increased level of mortality was observed in the HTLV-1 and coinfected animals when compared to the S. stercoralis infected group. The mortality was not correlated with proviral loads or total viral RNA. Analysis of cytokine profiles showed a distinct shift towards Th1 responses in HTLV-1 infected animals, a shift towards Th2 cytokines in S. stercoralis infected animals and elevated TNF-α responses in coinfected animals. HTLV-1 infected and coinfection groups showed a significant, yet non-clonal expansion of the CD4+CD25+ T-cell population. Numbers of worms in the coinfection group did not differ from those of the S. stercoralis infected group and no autoinfective larvae were found. However, infective larvae recovered from the coinfection group showed an enhancement in growth, as was seen in mice with S. stercoralis hyperinfection caused by treatment with steroids. Humanized mice coinfected with S. stercoralis and HTLV-1 demonstrate features associated with human infection with these pathogens and provide a unique opportunity to study the interaction between these two infections in vivo in the context of human immune cells.

Recent insights on astrocyte mechanisms in CNS homeostasis, pathology, and repair

Astrocytes play essential roles in development, homeostasis, injury, and repair of the central nervous system (CNS). Their development is tightly regulated by distinct spatial and temporal cues during embryogenesis and into adulthood throughout the CNS. Astrocytes have several important responsibilities such as regulating blood flow and permeability of the blood-CNS barrier, glucose metabolism and storage, synapse formation and function, and axon myelination. In CNS pathologies, astrocytes also play critical parts in both injury and repair mechanisms. Upon injury, they undergo a robust phenotypic shift known as "reactive astrogliosis," which results in both constructive and deleterious outcomes. Astrocyte activation and migration at the site of injury provides an early defense mechanism to minimize the extent of injury by enveloping the lesion area. However, astrogliosis also contributes to the inhibitory microenvironment of CNS injury and potentiate secondary injury mechanisms, such as inflammation, oxidative stress, and glutamate excitotoxicity, which facilitate neurodegeneration in CNS pathologies. Intriguingly, reactive astrocytes are increasingly a focus in current therapeutic strategies as their activation can be modulated toward a neuroprotective and reparative phenotype. This review will discuss recent advancements in knowledge regarding the development and role of astrocytes in the healthy and pathological CNS. We will also review how astrocytes have been genetically modified to optimize their reparative potential after injury, and how they may be transdifferentiated into neurons and oligodendrocytes to promote repair after CNS injury and neurodegeneration.

Risk factors for HTLV-1, acute kidney injury, and urinary tract infection among aboriginal adults with end stage kidney disease in central Australia

Central Australia is a human T-cell leukemia virus type 1c (HTLV-1c) endemic region and has the highest incidence of chronic kidney disease (CKD) in Australia. The factors associated with HTLV-1 seropositivity among Aboriginal Australian adults with CKD receiving hemodialysis (HD) were determined. A retrospective observational study of Aboriginal adults (≥ 18 years) who were receiving regular HD at the two main dialysis units in Alice Springs, December 1, 2010 to December 31, 2015. Demographic and clinical data before commencing HD were extracted from hospital records from the first presentation to Alice Springs Hospital (ASH) to HD commencement and associations were determined using logistic regression. Among 373 patients receiving HD, 133 (35.9%) were HTLV-1 infected. Identifiable factors associated with HTLV-1 status included increasing age, male gender, and diabetes before HD. The odds of diabetes mellitus were significantly higher among patients with HTLV-1 (adjusted odds ratio [aOR]: 2.76, 95% confidence interval [CI]: 1.19, 6.39; p = 0.017). More than one-fifth of participants had an acute kidney injury, the risk of which was increased among those with a previous blood stream infection (aOR: 3.02, 95% CI: 1.71, 5.34, p < 0.001). Men with a high HTLV-1 proviral load (≥500 copies per 105 peripheral blood leukocytes) had an increased risk of urinary tract infection (UTI) before HD (aOR: 5.15, 95% CI: 1.62, 16.40; p = 0.006). A strong association between HTLV-1 and diabetes, and an increased risk of UTI among men with a high HTLV-1 PVL, suggest that interactions between HTLV-1 infection and conventional risk factors may increase the risk for CKD in this population.

HTLV-1 oncovirus-host interactions: From entry to the manifestation of associated diseases

Human T lymphotropic virus type-1 (HTLV-1) is a well-known human oncovirus, associated with two life-threatening diseases, adult T cell leukaemia/lymphoma (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). The study of this oncogenic virus is significant from two different aspects. First, HTLV-1 can be considered as a neglected public health problem, which may spread slowly worldwide. Second, the incidence of HTLV-1 associated diseases due to oncogenic effects and deterioration of the immune system towards autoimmune diseases are not fully understood. Furthermore, knowledge about viral routes of transmission is important for considering potential interventions, treatments or vaccines in endemic regions. In this review, novel characteristics of HTLV-1, such as the unusual infectivity of virions through the virological synapse, are discussed in the context of the HTLV-1 associated diseases (ATL and HAM/TSP).

A significant association between CXCL10 -1447 A > G and IL18 -607 C > A gene polymorphism with human T-cell lymphotropic virus type 1 associated myelopathy/tropical spastic paraparesis (HAM-TSP), a case-control report from city of Mashhad, Iran

Human T-cell lymphotropic virus type 1 (HTLV-1) is the first isolated retrovirus from humans, and 2-3% of infected individuals suffer from HTLV-1 associated myelopathy tropical spastic paraparesis (HAM-TSP). Previous studies indicated that the risk of HAM-TSP could be correlated with the individuals' genetic alterations. Mashhad is one of the areas infected with HTLV-1 in Iran. This study designed to examine the association between several important gene polymorphisms and HAM-TSP. Genotypes of 232 samples from controls, HTLV-1 carriers, and HAM-TSP patients were examined for FAS-670 (A > G), CXCL10-1447 (A > G), Foxp3-3279 (C > A), IL-18 -137 (C > G), and IL-18 -607 (C > A) gene polymorphisms by different polymerase chain reaction (PCR) techniques. A non-significant association was observed between FAS-670 A > G, Foxp3-3279 C > A, and IL-18 -137 C > G gene polymorphisms and HAM-TSP. Nevertheless, a significant (P < 0.001) association between CXCL10-1447 A > G and IL-18 -607 C > A gene polymorphisms with HAM-TSP was observed in our study population. As previous studies revealed that the CXCL10 level in the cerebrospinal fluid of HAM-TSP patients was associated with the disease progression, and as we noticed, a direct association was observed between CXCL10-1447 A > G polymorphism and HAM-TSP. These polymorphisms might be recommended as a valuable prediction criterion for the severity of the disease. The contradiction between our findings and other studies regarding IL-18 -607 C > A gene polymorphism might be associated with various factors such as genotypes frequency in diverse races and population heterogeneity in the city of Mashhad.

Astrocytes in rare neurological conditions: Morphological and functional considerations

Astrocytes are a population of central nervous system (CNS) cells with distinctive morphological and functional characteristics that differ within specific areas of the brain and are widely distributed throughout the CNS. There are mainly two types of astrocytes, protoplasmic and fibrous, which differ in morphologic appearance and location. Astrocytes are important cells of the CNS that not only provide structural support, but also modulate synaptic activity, regulate neuroinflammatory responses, maintain the blood-brain barrier, and supply energy to neurons. As a result, astrocytic disruption can lead to widespread detrimental effects and can contribute to the pathophysiology of several neurological conditions. The characteristics of astrocytes in more common neuropathologies such as Alzheimer's and Parkinson's disease have significantly been described and continue to be widely studied. However, there still exist numerous rare neurological conditions in which astrocytic involvement is unknown and needs to be explored. Accordingly, this review will summarize functional and morphological changes of astrocytes in various rare neurological conditions based on current knowledge thus far and highlight remaining neuropathologies where astrocytic involvement has yet to be investigated.

Human T-cell leukaemia virus type 1 associated pulmonary disease: clinical and pathological features of an under-recognised complication of HTLV-1 infection

The lung is one of several organs that can be affected by HTLV-1 mediated inflammation. Pulmonary inflammation associated with HTLV-1 infection involves the interstitium, airways and alveoli, resulting in several clinical entities including interstitial pneumonias, bronchiolitis and alveolitis, depending on which structures are most affected. Augmentation of the inflammatory effects of HTLV-1 infected lymphocytes by recruitment of other inflammatory cells in a positive feedback loop is likely to underlie the pathogenesis of HTLV-1 associated pulmonary disease, as has been proposed for HTLV-1 associated myelopathy. In contrast to the conclusions of early case series, HTLV-1 associated pulmonary disease can be associated with significant parenchymal damage, which may progress to bronchiectasis where this involves the airways. Based on our current understanding of HTLV-1 associated pulmonary disease, diagnostic criteria are proposed.

Decrease in naïve T cell production due to HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) development

Human T-lymphocytic virus 1 (HTLV-1) is mainly associated with adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP exhibit significant changes in their immune response, and HTLV-1 infection can interfere in cytokine production and perhaps in T cell production. The aims of this study were to evaluate thymic function in HAM/TSP patients and HTLV-1 healthy carriers (HCs) and correlate it to age and interleukin 7 (IL-7) gene expression. Thymic function in 21 HAM/TSP patients and 12 HCs was evaluated by quantifying T cell receptor rearrangement excision circle (TREC) particles and IL-7 gene expression, both measured by quantitative polymerase chain reaction. HAM/TSP patients presented lower TREC particle counts (p = 0.0112) and lower IL-7 expression (p = 0.0102) than HCs. Both TREC particles and IL-7 gene expression were separately analyzed in two age groups: ≤ 59 years and ≥60 years, The ≤59-year-old HAM/TSP patients had a lower TREC count compared with the ≤59-year-old HCs (p = 0.0476). In conclusion, HAM/TSP development could interfere with thymic function because the results showed TREC particle reduction in HAM/TSP patients in relation to HCs, and it could be associated with a concomitant reduction in IL-7 expression.

Changes of inflammatory cytokines/chemokines during ravidasvir plus ritonavir-boosted danoprevir and ribavirin therapy for patients with genotype 1b hepatitis C infection

This study investigated the safety and efficacy of ravidasvir (RDV) plus ritonavir-boosted danoprevir (DNVr) and ribavirin (RBV) regimens for treatment-naïve non-cirrhotic patients with hepatitis C virus (HCV) genotype 1b in mainland China. We also gained insight into HCV-host interactions during anti-HCV treatment. 16 patients with HCV and 10 healthy people enrolled the study. Three of 16 patients received 12-weeks' placebo treatment first and served as the placebo controls. All (n = 16) patients received 12-weeks' RDV plus DNVr and RBV treatment. The adverse effects (AEs), viral loads, alanine transaminase, and aspartate aminotransferase were recorded during study. We also performed multianalyte profiling of 48 cytokines/chemokines in 16 patients with HCV and 10 normal controls. Seventy-five percent patients treated with RDV plus DNVr and RBV experienced AEs. No death, treatment-related serious AEs or AEs leading to discontinuation were reported. The serum HCV-RNA levels remained extremely high in 3 placebo controls after treated with placebo. After RDV plus DNVr and RBV treatment, all patients achieved sustained virologic response (SVR) at posttreatment week 12, but 1 patient experienced viral relapse at SVR 24. The cytokine/chemokine expression pattern was markedly altered in patients with HCV as compared with healthy controls. The interferon-inducible protein-10 (IP-10) decreased after anti-HCV treatment, and dramatically increased in one patient with viral relapse. The regimen of RDV and DNVr plus RBV represents a highly safe and effective treatment option for HCV patients in mainland China. The IP-10 has the potential to be an indicator of innate immune viral recognition.

Sex and FOXP3 gene rs2232365 polymorphism may be associated with the clinical and pathological aspects of chronic viral diseases

Background

The forkhead box protein 3 (FOXP3) transcription factor is one of the main markers of immunological suppression in different pathological profiles, and the presence of polymorphic variants may alter the gene expression of this factor. Despite descriptions of an association between the presence of the rs2232365 polymorphism and chronic diseases, the role of the sex variant in this context has not yet been elucidated, as the FOXP3 gene is located on the human sex chromosome X.

Results

To contribute to this topic, 323 women and 373 men were enrolled in the study, of which 101 were diagnosed with chronic viral liver diseases (39 women and 62 men), 67 with HTLV-1 infection (44 women and 23 men), 230 with coronary artery disease (91 women and 139 men) and 298 healthy and uninfected blood donors (149 women and men). They were genotyped for the rs2232365 polymorphism. The rs2232365 polymorphism was associated with clinical and pathological aspects and biomarkers of viral infections only in men, with functional differences between different infections.

Conclusions

A relationship is suggested between sex and FOXP3 rs2232365 polymorphism, resulting in different biological repercussions.

Pulmonary Disease Is Associated With Human T-Cell Leukemia Virus Type 1c Infection: A Cross-sectional Survey in Remote Aboriginal Communities

Background

The human T-cell leukemia virus type 1 (HTLV-1) subtype c is endemic to central Australia. We report the first large-scale, community-based, health survey of HTLV-1 and its disease associations in this setting.

Methods

Aboriginal community residents aged &gt;2 years in 7 remote communities were invited to do a health survey that included a questionnaire, spirometry, and clinical examination by a physician blinded to HTLV-1 status, clinical records, and spirometry results. Blood was drawn for HTLV-1 serology and proviral load (PVL). Pulmonary disease was assessed clinically and spirometrically and, where records were available, radiologically after the clinical assessment. Associations between specific diseases and HTLV-1 status were determined using logistic regression, adjusting for available confounders.

Results

Overall, 579 residents (164 children aged 3–17 years; 415 adults) were examined (37.7% of the estimated resident population). HTLV-1 prevalences for children and adults were 6.1% and 39.3%, respectively. No associations were found between HTLV-1 and any assessed clinical condition among children. Chronic pulmonary disease and gait abnormalities were more common among adults with HTLV-1 infection. Adjusted odds ratios among participants with PVL ≥1000 per 105 peripheral blood leukocytes were 7.08 (95% confidence interval [CI], 2.67–18.74; P &lt; .001), 9.81 (95% CI, 3.52–27.35; P &lt; .001), and 14.4 (95% CI, 4.99–41.69; P &lt; .001) for clinically defined chronic pulmonary disease, moderate-severe expiratory airflow limitation, and radiologically determined bronchiectasis/bronchiolitis, respectively, and 5.21 (95% CI, 1.50–18.07; P = .009) for gait abnormalities.

Conclusions

In the first study of HTLV-1 disease associations based on community recruitment and blinded assessment, HTLV-1 infection was strongly associated with pulmonary disease and gait abnormalities.

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.

The Role of Chemokines in the Pathogenesis of HTLV-1

Human T cell leukemia virus type 1 (HTLV-1) is a human retrovirus that is associated with two main diseases: HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T cell leukemia/lymphoma (ATL). Chemokines are highly specialized groups of cytokines that play important roles in organizing, trafficking, homing, and in the migration of immune cells to the bone marrow, lymphoid organs and sites of infection and inflammation. Aberrant expression or function of chemokines, or their receptors, has been linked to the protection against or susceptibility to specific infectious diseases, as well as increased the risk of autoimmune diseases and malignancy. Chemokines and their receptors participate in pathogenesis of HTLV-1 associated diseases from inflammation in the central nervous system (CNS) which occurs in cases of HAM/TSP to T cell immortalization and tissue infiltration observed in ATL patients. Chemokines represent viable effective prognostic biomarkers for HTLV-1-associated diseases which provide the early identification of high-risk, treatment possibilities and high-yielding clinical trials. This review focuses on the emerging roles of these molecules in the outcome of HTLV-1-associated diseases.

HTLV-1c associated bronchiolitis in an Aboriginal man from central Australia

We describe the first case of HTLV associated bronchiolitis to be associated with HTLV-1c subtype infection. An Aboriginal man with HTLV-1 infection was repeatedly admitted to Alice Springs Hospital, central Australia, with hypercapnic respiratory failure from the age of 28 years. High resolution CT chest findings were consistent with bronchiolitis and large numbers of lymphocytes were found in bronchoalveolar lavage fluid (BALF). After extensive investigations failed to find a cause, he was tested for HTLV-1 and found to have a high HTLV-1c proviral load (6.8 %) in peripheral blood leukocytes and in BALF (4.7 %). The administration of systemic corticosteroids resulted in a rapid clinical response; however, he did not continue treatment after discharge and died due to respiratory failure in the community.

HTLV-1 infection of myeloid cells: from transmission to immune alterations

Human T cell leukemia virus type 1 (HTLV-1), the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and the demyelinating neuroinflammatory disease known as HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP), was the first human retrovirus to be discovered. T-cells, which represent the main reservoir for HTLV-1, have been the main focus of studies aimed at understanding viral transmission and disease progression. However, other cell types such as myeloid cells are also target of HTLV-1 infection and display functional alterations as a consequence. In this work, we review the current investigations that shed light on infection, transmission and functional alterations subsequent to HTLV-1 infection of the different myeloid cells types, and we highlight the lack of knowledge in this regard.

Liver kinase B1 depletion from astrocytes worsens disease in a mouse model of multiple sclerosis

Liver kinase B1 (LKB1) is a ubiquitously expressed kinase involved in the regulation of cell metabolism, growth, and inflammatory activation. We previously reported that a single nucleotide polymorphism in the gene encoding LKB1 is a risk factor for multiple sclerosis (MS). Since astrocyte activation and metabolic function have important roles in regulating neuroinflammation and neuropathology, we examined the serine/threonine kinase LKB1 in astrocytes in a chronic experimental autoimmune encephalomyelitis mouse model of MS. To reduce LKB1, a heterozygous astrocyte-selective conditional knockout (het-cKO) model was used. While disease incidence was similar, disease severity was worsened in het-cKO mice. RNAseq analysis identified Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched in het-cKO mice relating to mitochondrial function, confirmed by alterations in mitochondrial complex proteins and reductions in mRNAs related to astrocyte metabolism. Enriched pathways included major histocompatibility class II genes, confirmed by increases in MHCII protein in spinal cord and cerebellum of het-cKO mice. We observed increased numbers of CD4+ Th17 cells and increased neuronal damage in spinal cords of het-cKO mice, associated with reduced expression of choline acetyltransferase, accumulation of immunoglobulin-γ, and reduced expression of factors involved in motor neuron survival. In vitro, LKB1-deficient astrocytes showed reduced metabolic function and increased inflammatory activation. These data suggest that metabolic dysfunction in astrocytes, in this case due to LKB1 deficiency, can exacerbate demyelinating disease by loss of metabolic support and increase in the inflammatory environment.

Predictors of non-cystic fibrosis bronchiectasis in Indigenous adult residents of central Australia: results of a case-control study

The human T-cell leukaemia virus type 1 (HTLV-1) is associated with pulmonary inflammation. Indigenous Australians in central Australia have a very high prevalence of HTLV-1 infection and we hypothesised that this might contribute to high rates of bronchiectasis in this population. 80 Indigenous adults with confirmed bronchiectasis, each matched by age, sex and language to two controls without bronchiectasis, were recruited. Case notes and chest imaging were reviewed, HTLV-1 serology and the number of peripheral blood leukocytes (PBLs) infected with HTLV-1 (pro-viral load (PVL)) were determined, and radiological abnormality scores were calculated. Participants were followed for a mean±sd of 1.14±0.86 years and causes of death were determined. Median (interquartile range) HTLV-1 PVL for cases was 8-fold higher than controls (cases 213.8 (19.7-3776.3) copies per 105 PBLs versus controls 26.6 (0.9-361) copies per 105 PBLs; p=0.002). Radiological abnormality scores were higher for cases with HTLV-1 PVL ≥1000 copies per 105 PBLs and no cause of bronchiectasis other than HTLV-1 infection. Major predictors of bronchiectasis were prior severe lower respiratory tract infection (adjusted OR (aOR) 17.83, 95% CI 4.51-70.49; p<0.001) and an HTLV-1 PVL ≥1000 copies per 105 PBLs (aOR 12.41, 95% CI 3.84-40.15; p<0.001). Bronchiectasis (aOR 4.27, 95% CI 2.04-8.94; p<0.001) and HTLV-1 PVL ≥1000 copies per 105 PBLs (aOR 3.69, 95% CI 1.11-12.27; p=0.033) predicted death. High HTLV-1 PVLs are associated with bronchiectasis and with more extensive radiological abnormalities, which may result from HTLV-1-mediated airway inflammation.

Impact of host immunity on HTLV-1 pathogenesis: potential of Tax-targeted immunotherapy against ATL

Human T-cell leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and other inflammatory diseases. There is no disease-specific difference in viral strains, and it is unclear how HTLV-1 causes such different diseases manifesting as lymphoproliferation or inflammation. Although some progress has been made in therapies for these diseases, the prognosis for ATL is still dismal and HAM/TSP remains an intractable disease. So far, two regulatory proteins of HTLV-1, Tax and HBZ, have been well studied and shown to have pleiotropic functions implicated in viral pathogenesis. Tax in particular can strongly activate NFκB, which is constitutively activated in HTLV-1-infected cells and considered to contribute to both oncogenesis and inflammation. However, the expression level of Tax is very low in vivo, leading to confusion in understanding its role in viral pathogenesis. A series of studies using IL-2-dependent HTLV-1-infected cells indicated that IL-10, an anti-inflammatory/immune suppressive cytokine, could induce a proliferative phenotype in HTLV-1-infected cells. In addition, type I interferon (IFN) suppresses HTLV-1 expression in a reversible manner. These findings suggest involvement of host innate immunity in the switch between lymphoproliferative and inflammatory diseases as well as the regulation of HTLV-1 expression. Innate immune responses also affect another important host determinant, Tax-specific cytotoxic T lymphocytes (CTLs), which are impaired in ATL patients, while activated in HAM/TSP patients. Activation of Tax-specific CTLs in ATL patients after hematopoietic stem cell transplantation indicates Tax expression and its fluctuation in vivo. A recently developed anti-ATL therapeutic vaccine, consisting of Tax peptide-pulsed dendritic cells, induced Tax-specific CTL responses in ATL patients and exhibited favorable clinical outcomes, unless Tax-defective ATL clones emerged. These findings support the significance of Tax in HTLV-1 pathogenesis, at least in part, and encourage Tax-targeted immunotherapy in ATL. Host innate and acquired immune responses induce host microenvironments that modify HTLV-1-encoded pathogenesis and establish a complicated network for development of diseases in HTLV-1 infection. Both host and viral factors should be taken into consideration in development of therapeutic and prophylactic strategies in HTLV-1 infection.

Low Frequency Of Regulatory B-Cells And Increased CD4+ and CD8+ Interferon-γ-producing cells in patients with tropical spastic paraparesis associated with human T-cell lymphotropic virus type

INTRODUCTION

Tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM) is a disease caused by human T-cell lymphotropic virus type 1 (HTLV-I) that mainly infects CD4 T cells-for example, those of the CD4+CD25hiFOXP3+ [Treg] phenotype-where it inhibits forkhead box protein P3 (FOXP3) expression and promotes interferon-γ (IFN-γ) expression. However, the role it exerts on regulatory B cells (CD19+CD24hiCD38hi; Breg) is unknown.

METHODS

The frequencies of Treg and Breg cells was evaluated and the Th1 profiles were assessed in TSP/HAM patients and healthy control subjects.

RESULTS

Low percentages of Breg cells and high production of IFN-γ were observed in patients compared to those in healthy control subjects.

CONCLUSIONS

The low percentage of Breg cells in patients and the increase in the frequency of Th1 cells suggest an imbalance in the control of the inflammatory response that contributes to the immunopathogenesis of TSP/HAM.

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.

Cytokine Networks Dysregulation during HTLV-1 Infection and Associated Diseases

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of a neural chronic inflammation, called HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and of a malignant lymphoproliferation, called the adult T-cell leukemia/lymphoma (ATLL). The mechanisms through which the HTLV-1 induces these diseases are still unclear, but they might rely on immune alterations. HAM/TSP is associated with an impaired production of pro-inflammatory cytokines and chemokines, such as IFN-γ, TNF-α, CXCL9, or CXCL10. ATLL is associated with high levels of IL-10 and TGF-β. These immunosuppressive cytokines could promote a protumoral micro-environment. Moreover, HTLV-1 infection impairs the IFN-I production and signaling, and favors the IL-2, IL-4, and IL-6 expression. This contributes both to immune escape and to infected cells proliferation. Here, we review the landscape of cytokine dysregulations induced by HTLV-1 infection and the role of these cytokines in the HTLV-1-associated diseases progression.

Distinct gene expression signatures induced by viral transactivators of different HTLV-1 subgroups that confer a different risk of HAM/TSP

Background

Among human T cell leukemia virus type 1 (HTLV-1)-infected individuals, there is an association between HTLV-1 tax subgroups (subgroup-A or subgroup-B) and the risk of HAM/TSP in the Japanese population. To investigate the role of HTLV-1 subgroups in viral pathogenesis, we studied the functional difference in the subgroup-specific viral transcriptional regulators Tax and HBZ using microarray analysis, reporter gene assays, and evaluation of viral-host protein–protein interaction.

Results

(1) Transcriptional changes in Jurkat Tet-On human T-cells that express each subgroup of Tax or HBZ protein under the control of an inducible promoter revealed different target gene profiles; (2) the number of differentially regulated genes induced by HBZ was 2–3 times higher than that induced by Tax; (3) Tax and HBZ induced the expression of different classes of non-coding RNAs (ncRNAs); (4) the chemokine CXCL10, which has been proposed as a prognostic biomarker for HAM/TSP, was more efficiently induced by subgroup-A Tax (Tax-A) than subgroup-B Tax (Tax-B), in vitro as well as in unmanipulated (ex vivo) PBMCs obtained from HAM/TSP patients; (5) reporter gene assays indicated that although transient Tax expression in an HTLV-1-negative human T-cell line activated the CXCL10 gene promoter through the NF-κB pathway, there was no difference in the ability of each subgroup of Tax to activate the CXCL10 promoter; however, (6) chromatin immunoprecipitation assays showed that the ternary complex containing Tax-A is more efficiently recruited onto the promoter region of CXCL10, which contains two NF-κB binding sites, than that containing Tax-B.

Conclusions

Our results indicate that different HTLV-1 subgroups are characterized by different patterns of host gene expression. Differential expression of pathogenesis-related genes by subgroup-specific Tax or HBZ may be associated with the onset of HAM/TSP.

Electronic supplementary material

The online version of this article (10.1186/s12977-018-0454-x) contains supplementary material, which is available to authorized users.

Patients with chronic hepatitis C receiving sofosbuvir and ribavirin-based treatment, with or without interferon in Zhejiang, China: An observational study

Hepatitis C virus (HCV) is one of the most important virus as the cause of liver disease in China. The aim of the present study was to explore whether sofosbuvir and ribavirin-based treatment can cure patients with chronic hepatitis C in eastern China. We examined a cohort of HCV-monoinfected patients and 9 patients agreed to participate in our treatment and research. The patients were diagnosed with chronic hepatitis C with or without cirrhosis. Nine patients including 4 female and 5 male met the requirements for selection and were willing to participate in this experiment. Sofosbuvir and ribavirin-based treatment with or without interferon was given to the patients. Viral loads, cytokines, and chemokines were recorded during treatment and after treatment. After 2 weeks of sofosbuvir and ribavirin-based treatment, the viral load of patients decreased to limits of detection. Eight patients were cured. Patients had rapid virological response (RVR) with undetectable viral load at week 4 and sustained virological response (SVR). The interferon-inducible protein-10 (IP-10) decreased after the treatment. However, the patient with cirrhosis failed, as the virus reappeared during SVR4. At the same time, the IP-10 dramatically increased as the relapse of the HCV virus. In summary, the IP-10 has the potential to be the biomarker for the prognostic of HCV.

The clinical impact of human T-lymphotrophic virus type 1 (HTLV-1) infection on the development of adult T-cell leukemia-lymphoma (ATL) or HTLV-1-associated myelopathy (HAM) / atypical HAM after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and renal transplantation

Because there are limited clinical reports on the impact of human T-lymphotropic virus type 1 (HTLV-1) on organ transplantation, its effects on the development of adult T-cell leukemia-lymphoma (ATL), post-transplantation lymphoproliferative disorder (PTLD) and HTLV-1–associated myelopathy (HAM) or atypical HAM after organ transplantation remain unclear.

We retrospectively analyzed the impact of HTLV-1 in 54 allogeneic hematopoietic stem cell transplantation (allo-HSCT) cases and 31 renal transplantation cases between January 2006 and December 2016.

Among the 54 allo-HSCT cases, nine recipients with ATL tested positive for HTLV-1, and one was found to be an HTLV-1 carrier. All donors tested negative for HTLV-1. Only one HTLV-1 carrier did not present with ATL or HAM development after allo-HSCT. Among nine ATL cases after allo-HSCT, four eventually relapsed due to proliferation of recipient-derived ATL cells. However, in one ATL case, atypical HAM developed rapidly at 5 months after allo-HSCT.

Among the 31 renal transplantation cases, all donors tested negative for HTLV-1, and only recipients tested positive. Only one HTLV-1 carrier recipient did not present with ATL or HAM development after renal transplantation. However, one HTLV-1-negative recipient developed PTLD in the brain 10 years after renal transplantation.

In clinical practice, careful follow-up of HTLV-1 infected recipients after organ transplantation is important because atypical HAM can develop in ATL patients after allo-HSCT. Furthermore, to clarify the risk of ATL or HAM development in HTLV-1 infected recipients, we prospectively followed up our cohort.

Mogamulizumab (Anti-CCR4) in HTLV-1-Associated Myelopathy

BACKGROUND

Human T-lymphotropic virus type 1 (HTLV-1) causes the debilitating neuroinflammatory disease HTLV-1-associated myelopathy-tropical spastic paraparesis (HAM-TSP) as well as adult T-cell leukemia-lymphoma (ATLL). In patients with HAM-TSP, HTLV-1 infects mainly CCR4+ T cells and induces functional changes, ultimately causing chronic spinal cord inflammation. We evaluated mogamulizumab, a humanized anti-CCR4 monoclonal antibody that targets infected cells, in patients with HAM-TSP.

METHODS

In this uncontrolled, phase 1-2a study, we assessed the safety, pharmacokinetics, and efficacy of mogamulizumab in patients with glucocorticoid-refractory HAM-TSP. In the phase 1 dose-escalation study, 21 patients received a single infusion of mogamulizumab (at doses of 0.003 mg per kilogram of body weight, 0.01 mg per kilogram, 0.03 mg per kilogram, 0.1 mg per kilogram, or 0.3 mg per kilogram) and were observed for 85 days. Of those patients, 19 continued on to the phase 2a study and received infusions, over a period of 24 weeks, of 0.003 mg per kilogram, 0.01 mg per kilogram, or 0.03 mg per kilogram at 8-week intervals or infusions of 0.1 mg per kilogram or 0.3 mg per kilogram at 12-week intervals.

RESULTS

The side effects of mogamulizumab did not limit administration up to the maximum dose (0.3 mg per kilogram). The most frequent side effects were grade 1 or 2 rash (in 48% of the patients) and lymphopenia and leukopenia (each in 33%). The dose-dependent reduction in the proviral load in peripheral-blood mononuclear cells (decrease by day 15 of 64.9%; 95% confidence interval [CI], 51.7 to 78.1) and inflammatory markers in cerebrospinal fluid (decrease by day 29 of 37.3% [95% CI, 24.8 to 49.8] in the CXCL10 level and of 21.0% [95% CI, 10.7 to 31.4] in the neopterin level) was maintained with additional infusions throughout the phase 2a study. A reduction in spasticity was noted in 79% of the patients and a decrease in motor disability in 32%.

CONCLUSIONS

Mogamulizumab decreased the number of HTLV-1-infected cells and the levels of inflammatory markers. Rash was the chief side effect. The effect of mogamulizumab on clinical HAM-TSP needs to be clarified in future studies. (Funded by the Japan Agency for Medical Research and Development and the Ministry of Health, Labor, and Welfare; UMIN trial number, UMIN000012655 .).

HTLV-1, the Other Pathogenic Yet Neglected Human Retrovirus: From Transmission to Therapeutic Treatment

Going back to their discovery in the early 1980s, both the Human T-cell Leukemia virus type-1 (HTLV-1) and the Human Immunodeficiency Virus type-1 (HIV-1) greatly fascinated the virology scene, not only because they were the first human retroviruses discovered, but also because they were associated with fatal diseases in the human population. In almost four decades of scientific research, both viruses have had different fates, HTLV-1 being often upstaged by HIV-1. However, although being very close in terms of genome organization, cellular tropism, and viral replication, HIV-1 and HTLV-1 are not completely commutable in terms of treatment, especially because of the opposite fate of the cells they infect: death versus immortalization, respectively. Nowadays, the antiretroviral therapies developed to treat HIV-1 infected individuals and to limit HIV-1 spread among the human population have a poor or no effect on HTLV-1 infected individuals, and thus, do not prevent the development of HTLV-1-associated diseases, which still lack highly efficient treatments. The present review mainly focuses on the course of HTLV-1 infection, from the initial infection of the host to diseases development and associated treatments, but also investigates HIV-1/HTLV-1 co-infection events and their impact on diseases development.

Effectiveness of Daily Prednisolone to Slow Progression of Human T-Lymphotropic Virus Type 1-Associated Myelopathy/Tropical Spastic Paraparesis: A Multicenter Retrospective Cohort Study

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.