Human T-cell Leukemia Virus-1 Infection Research Articles

Serum Calcium Level and Functional Atherosclerosis in Relation to Human T-Cell Leukemia Virus 1 Infection in Older Individuals

Serum calcium levels are known to influence vascular function. Cells infected with human T-cell leukemia virus 1 (HTLV-1) impact serum calcium levels and also affect the endothelium. Since a damaged endothelium causes functional atherosclerosis, serum calcium levels in HTLV-1 carriers may be positively associated with functional atherosclerosis. This cross-sectional study enrolled 1694 Japanese individuals aged 60 to 89 years. Functional atherosclerosis was defined as a cardio-ankle vascular index (CAVI) ≥ 9.0. Logistic regression analysis was used to evaluate the relationship between HTLV-1 carrier status and both serum calcium level and functional atherosclerosis. Even after adjusting for known confounding factors, the serum calcium level was significantly positively associated with functional atherosclerosis only in asymptomatic HTLV-1 carriers. The fully adjusted odds ratio and 95% confidence interval of functional atherosclerosis in relation to a one-standard-deviation increment of serum calcium level (0.4 mg/dL in both men and women) were 1.54 (1.18, 2.01) for HTLV-1 carriers (n = 322) and 0.99 (0.87, 1.13) for HTLV-1 non-carriers (n = 1372), respectively. The serum calcium level was positively associated with functional atherosclerosis only among older carriers of HTLV-1 infection. This finding can help effectively estimate the risk of functional atherosclerosis in asymptomatic HTLV-1 carriers.

HTLV-1-associated myelopathy/tropical spastic paraplegia with sporadic late-onset nemaline myopathy: a case report

BackgroundSporadic late onset nemaline myopathy (SLONM) is a muscle disorder characterized by the presence of nemaline rods in muscle fibers. SLONM has no known genetic cause but has been associated with monoclonal gammopathy of undetermined significance and with human immunodeficiency virus (HIV) infection. Human T-cell leukemia virus-1 (HTLV-1) is a known causative agent of adult T-cell leukemia/lymphoma and HTLV-1 associated myelopathy/tropical spastic paraplegia (HAM/TSP), a chronic inflammatory neurological disease. HTLV-1 has been reported to be implicated in inflammatory myopathies, as well as in HIV infection.; however, there have been no reports of an association between HTLV-1 infection and SLONM to date.Case presentationA 70-year-old Japanese woman presented with gait disturbance, lumbar kyphosis, and respiratory dysfunction. The diagnosis of HAM/TSP with SLONM was made based on characteristic clinical symptoms of HAM/TSP, such as spasticity in the lower extremities, and cerebrospinal fluid test results; and of SLONM, such as generalized head drooping, respiratory failure, and muscle biopsy results. Steroid treatment was initiated and improvement in her stooped posture was observed after 3 days of treatment.ConclusionThis is the first case report of SLONM combined with HTLV-1 infection. Further studies are needed to elucidate the relationship between retroviruses and muscle diseases.

Iliopsoas Muscle Weakness as a Key Diagnostic Marker in HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP).

Human T-cell leukemia virus-1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a slowly progressive neurological disease that arises from HTLV-1 infection. Pathologically, the condition is characterized by diffuse myelitis, which is most evident in the thoracic spinal cord. Clinical manifestations of the infectious disease, HAM/TSP, are empirically known to include weakness of the proximal muscles of the lower extremities and atrophy of the paraspinal muscles, which is characteristic of the distribution of disturbed muscles usually seen in muscular diseases, except that the upper extremities are almost normal. This unique clinical presentation is useful information for physicians and physical therapists involved in diagnosing and rehabilitating patients with HAM/TSP, as well as critical information for understanding the pathogenesis of HAM/TSP. However, the precise pattern of muscle involvement in this condition has yet to be reported. The purpose of this study was to identify the muscles affected by HAM/TSP in order to understand the pathogenesis of HAM/TSP as well as to aid in the diagnosis and rehabilitation of HAM/TSP. A retrospective review of medical records was conducted on 101 consecutively admitted patients with HAM/TSP at Kagoshima University Hospital. Among 101 patients with HAM/TSP, all but three had muscle weakness in the lower extremities. Specifically, the hamstrings and iliopsoas muscle were the most frequently affected in over 90% of the patients. Manual muscle testing (MMT) revealed that the iliopsoas was the weakest of the muscles assessed, a consistent feature from the early to advanced stages of the disease. Our findings demonstrate a unique distribution of muscle weakness in HAM/TSP, with the proximal muscles of the lower extremities, particularly the iliopsoas muscle, being the most frequently and severely affected.

VEGF Polymorphism rs3025039 and Human T-Cell Leukemia Virus 1 (HTLV-1) Infection among Older Japanese Individuals: A Cross-Sectional Study.

Previous studies have reported a close correlation between vascular endothelial growth factor (VEGF), which plays an important role in angiogenesis, and human T-cell leukemia virus 1 (HTLV-1). However, an association between genetic characteristics related to VEGF and HTLV-1 infection has not yet been reported. Because the VEGF polymorphism rs3025039 is inversely associated with serum concentrations of VEGF, we focus on rs3025039 in the present study. To clarify the association between the VEGF polymorphism rs3025039 and HTLV-1 infection, a cross-sectional study of 1924 Japanese individuals aged 60–79 years who participated in general health check-ups was conducted. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (CIs) for HTLV-1 infection in relation to rs3025039 genotype were calculated with adjustment for known confounders. Compared with rs3025039 CC-homozygotes, (T) allele carriers had a significantly lower OR for HTLV-1 infection. The adjusted OR and 95% CI for HTLV-1 infection was 0.70 (0.54–0.91) (p = 0.009). Genetic characteristics related to lower angiogenesis activity might be associated with a lower chance of establishing HTLV-1 infection. Although further investigation is necessary, angiogenesis might play a crucial role in the establishment of HTLV-1 infection.

Transcriptomic analysis reveals genetic factors regulating early steroid-induced osteonecrosis of the femoral head.

The present study aimed to explore the signaling pathways involved in development of early steroid-induced osteonecrosis of the femoral head (SONFH) and identify diagnostic biomarkers regulating peripheral blood in SONFH patients. We downloaded transcriptome data and identified differentially expressed genes (DEGs) using the R software. We used ClusterProfiler to perform enrichment analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, and analyzed protein–protein interactions using the STRING database. Network X was used to visualize the networks in Python. A total of 584 DEGs were identified, of which 294 and 290 were upregulated and downregulated, respectively. Enrichment analysis showed that the DEGs were mainly involved in red blood cell differentiation, cell protein catabolism, gas transportation, activation of myeloid leukocytes, phagocytosis, and inflammatory response. Pathway analysis revealed that these DEGs were involved in regulation of mitophagy-animal, human T-cell leukemia virus-1 infection, Forkhead box O, phagocytosis, osteoclast differentiation, and cytokine–cytokine receptor interaction. Quantitative real-time polymerase chain reaction results were consistent with findings from protein–protein interaction network analysis. Several genes, including peroxiredoxin 2, haptoglobin, matrix metallopeptidase 8, formyl peptide receptor 2, and integrin subunit alpha X, promote SONFH occurrence by regulating the redox, inflammatory response, and osteoblast and osteoclast structure and function pathways. They may be important targets for designing approaches for early diagnosis and treatment of SONFH.

MiR-150 in HTLV-1 infection and T-cell transformation.

Human T-cell leukemia virus-1 (HTLV-1) is a retrovirus that persistently infects CD4+ T-cells, and is the causative agent of adult T-cell leukemia/lymphoma (ATLL), tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM) and several inflammatory diseases. T-cell transformation by HTLV-1 is driven by multiple interactions between viral regulatory proteins and host cell pathways that govern cell proliferation and survival. Studies performed over the last decade have revealed alterations in the expression of many microRNAs in HTLV-1-infected cells and ATLL cells, and have identified several microRNA targets with roles in the viral life cycle and host cell turnover. This review centers on miR-150-5p, a microRNA whose expression is temporally regulated during lymphocyte development and altered in several hematological malignancies. The levels of miR-150-5p are reduced in many HTLV-1-transformed- and ATLL-derived cell lines. Experiments in these cell lines showed that downregulation of miR-150-5p results in activation of the transcription factor STAT1, which is a direct target of the miRNA. However, data on miR-150-5p levels in freshly isolated ATLL samples are suggestive of its upregulation compared to controls. These apparently puzzling findings highlight the need for more in-depth studies of the role of miR-150-5p in HTLV-1 infection and pathogenesis based on knowledge of miR-150-5p-target mRNA interactions and mechanisms regulating its function in normal leukocytes and hematologic neoplasms.

Epidemiological Evidence of Nosocomial and Zoonotic Transmission of Human T-Cell Leukemia Virus-1 in a Large Survey in a Rural Population of Central Africa.

Central Africa is one of the largest areas of high endemicity for human T-cell leukemia virus-1 (HTLV-1). However, no preventive measures are yet implemented to reduce its transmission, which can be sexual, from mother-to-child, or through contaminated blood products. Rare zoonotic transmissions from nonhuman primates (NHPs) have also been reported in this region. Here we investigated the HTLV-1 prevalence and associated risk factors in a rural population in Cameroon. From 2019 to 2021, we performed a cross-sectional survey in the eastern region of Cameroon. HTLV-1 infection was first screened by ELISA, then tested by western blot and envelope gene targeted polymerase chain reaction. Risk factors associated with HTLV-1 infection were identified by logistic regression in univariable and multivariable analyses. Among 3400 participants, HTLV-1 prevalence was 1.1% (95% confidence interval [CI], .7-1.5). Factors independently associated with HTLV-1 infection were Pygmy ethnicity (adjusted odd ratio [aOR], 2.9; 95% CI, 1.3-6.2), history of surgery (aOR, 6.3; 95% CI, 2.2-17.8), and NHP bite (aOR, 6.6; 95% CI, 2.2-19.8). These results suggest both iatrogenic and zoonotic transmission of HTLV-1 in Cameroon. Further studies are needed to assess the risk of nosocomial transmission of HTLV-1, to guide public health authorities in implementing preventive measures to control HTLV-1 transmission.

The Road to HTLV-1-Induced Leukemia by Following the Subcellular Localization of HTLV-1-Encoded HBZ Protein.

Human T cell leukemia virus-1 (HTLV-1) is the causative agent of a severe cancer of the lymphoid lineage that develops in 3-5% of infected individuals after many years. HTLV-1 infection may also induce a serious inflammatory pathology of the nervous system designated HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Two virus-encoded proteins, the viral transactivator Tax-1 and the HTLV-1 basic leucine-zipper factor HBZ, are strongly involved in the oncogenic process. Tax-1 is involved in initial phases of the oncogenic process. Conversely, HBZ seems to be involved in maintenance of the neoplastic state as witnessed by the generation of leukemic/lymphomatous phenotype in HBZ transgenic mice and the persistent expression of HBZ in all phases of the oncogenic process. Nevertheless, the intimate molecular and cellular mechanism mediated by the two viral proteins, particularly HBZ, in oncogenesis still remain elusive. An important step toward the complete comprehension of HBZ-associated oncogenicity is the clarification of the anatomical correlates of HBZ during the various phases of HTLV-1 infection to development of HTLV-1-associated inflammatory pathology and ultimately to the establishment of leukemia. In this review, I will summarize recent studies that have established for the first time a temporal and unidirectional expression of HBZ, beginning with an exclusive cytoplasmic localization in infected asymptomatic individuals and in HAM/TSP patients and ending to a progressive cytoplasmic-to-nuclear transition in leukemic cells. These results are framed within the present knowledge of HTLV-1 infection and the future lines of research that may shed new light on the complex mechanism of HTLV-1- mediated oncogenesis.

Structure of SNX9 SH3 in complex with a viral ligand reveals the molecular basis of its unique specificity for alanine-containing class I SH3 motifs

Class I SH3 domain-binding motifs generally comply with the consensus sequence [R/K]xØPxxP, the hydrophobic residue Ø being proline or leucine. We have studied the unusual Ø= Ala-specificity of SNX9 SH3 by determining its complex structure with a peptide present in eastern equine encephalitis virus (EEEV) nsP3. The structure revealed the length and composition of the n-Src loop as important factors determining specificity. We also compared the affinities of EEEV nsP3 peptide, its mutants, and cellular ligands to SNX9 SH3. These data suggest that nsP3 has evolved to minimize reduction of conformational entropy upon binding, hence acquiring stronger affinity, enabling takeover of SNX9. The RxAPxxP motif was also found in human Tcell leukemia virus-1 (HTLV-1) Gag polyprotein. We found that this motif was required for efficient HTLV-1 infection, and that the specificity of SNX9 SH3 for the RxAPxxP core binding motif was importantly involved in this process.

HTLV-1 Infection and Pathogenesis: New Insights from Cellular and Animal Models.

Since the discovery of the human T-cell leukemia virus-1 (HTLV-1), cellular and animal models have provided invaluable contributions in the knowledge of viral infection, transmission and progression of HTLV-associated diseases. HTLV-1 is the causative agent of the aggressive adult T-cell leukemia/lymphoma and inflammatory diseases such as the HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Cell models contribute to defining the role of HTLV proteins, as well as the mechanisms of cell-to-cell transmission of the virus. Otherwise, selected and engineered animal models are currently applied to recapitulate in vivo the HTLV-1 associated pathogenesis and to verify the effectiveness of viral therapy and host immune response. Here we review the current cell models for studying virus–host interaction, cellular restriction factors and cell pathway deregulation mediated by HTLV products. We recapitulate the most effective animal models applied to investigate the pathogenesis of HTLV-1-associated diseases such as transgenic and humanized mice, rabbit and monkey models. Finally, we summarize the studies on STLV and BLV, two closely related HTLV-1 viruses in animals. The most recent anticancer and HAM/TSP therapies are also discussed in view of the most reliable experimental models that may accelerate the translation from the experimental findings to effective therapies in infected patients.

Comparison of functioning and health-related quality of life among patients with HTLV-1, HIV, and HIV-HTLV-1-coinfection.

INTRODUCTION: Human immunodeficiency virus (HIV) and human T-cell leukemia virus-1 (HTLV-1) viruses are associated with a high global burden of disease, and coinfection is a frequently reported event. We aimed to compare the functioning and health-related quality of life (HRQoL) of patients infected with HTLV-1, HIV, and HIV-HTLV-1. METHODS: We conducted a cross-sectional study of patients older than 18 years who had an HTLV-1 infection (Group A), HIV infection (Group B), or HIV-HTLV-1 coinfection (Group C). The functioning profiles were evaluated using handgrip strength, Berg balance scale (BBS), timed “up and go” (TUG) test, and 5-m walk test (m/s). We used the World Health Organization Disability Assessment Schedule (WHODAS 2.0) questionnaire to measure disability. The HRQoL was evaluated using a 36-item short-form health survey. For data with parametric and non-parametric distribution, we used analysis of variance with Bonferroni correction and the Kruskal-Wallis test, followed by Dunn’s pairwise tests with Bonferroni correction. RESULTS: We enrolled 68 patients in Group A, 39 in Group B, and 29 in Group C. The scores for handgrip strength, BBS, TUG test, all the WHODAS domains, and HRQoL were poorer for Groups A and C than for Group B.CONCLUSIONS: Compared to patients with HIV infection, those with HIV-HTLV-1 coinfection and HTLV-1 infection had poor functioning and HRQoL scores. HTLV-1 infection was associated with reduced functioning and HRQoL in patients with a single HTLV-1 infection and HIV-HTLV-1 coinfection.

Dichotomy in Fatal Outcomes in a Large Cohort of People Living with HTLV-1 in São Paulo, Brazil.

Background: Despite its relatively low incidence of associated diseases, Human T-cell Leukemia Virus-1 (HTLV-1) infection was reported to carry a significant risk of mortality in several endemic areas. HTLV-1-associated diseases, adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraperesis (HAM/TSP), as well as frequent coinfections with human immunodeficiency virus (HIV), hepatitis C virus (HCV), and Strongyloides stercoralis were associated to increased morbidity and mortality of HTLV-1 infection. Objective: To determine the mortality rate and its associated variables from an open cohort started in July 1997 at the HTLV Clinic, Emilio Ribas Institute (IIER), a major infectious disease hospital in São Paulo, Brazil. Methods: Since inception up to September 2018, we admitted 727 HTLV-1-infected individuals, with a rate of 30–50 new admissions per year. All patient data, including clinical and laboratory data, were regularly updated throughout the 21-year period, using a dedicated REDCap database. The Ethical Board of IIER approved the protocol. Results: During 21 years of clinical care to people living with HTLV-1 in the São Paulo region, we recruited 479 asymptomatic HTLV-1-infected individuals and 248 HAM/TSP patients, of which 632 remained under active follow-up. During a total of 3800 person-years of follow-up (maximum follow-up 21.5 years, mean follow-up 6.0 years), 27 individuals died (median age of 51.5 years), of which 12 were asymptomatic, one ATLL patient and 14 HAM/TSP patients. HAM/TSP diagnosis (but neither age nor gender) was a significant predictor of increased mortality by univariate and multivariate (hazard ratio (HR) 5.03, 95% CI [1.96–12.91], p = 0.001) Cox regression models. Coinfection with HIV/HCV was an independent predictor of increased mortality (HR 15.08; 95% CI [5.50–41.32]; p < 0.001), with AIDS-related infections as a more frequent cause of death in asymptomatics (6/13; p = 0.033). HIV/HCV-negative fatal HAM/TSP cases were all female, with urinary tract infection and decubitus ulcer-associated sepsis as the main cause of death (8/14, p = 0.002). Conclusions: All-cause mortality among people living with HTLV-1 in São Paulo differs between asymptomatic (2.9%) and HAM/TSP patients (7.3%), independent of age and gender. We observe a dichotomy in fatal cases, with HAM/TSP and HIV/HCV coinfection as independent risk factors for death. Our findings reveal an urgent need for public health actions, as the major causes of death, infections secondary to decubitus ulcers, and immune deficiency syndrome (AIDS)-related infections, can be targeted by preventive measures.

Initial human T-cell leukemia virus type 1 infection of the salivary gland epithelial cells requires a biofilm-like structure

The initial phase of the human T cell leukemia virus-1 (HTLV-1) infection of salivary gland epithelial cells (SGECs) was examined. SGECs of patients with Sjögren’s syndrome (SS) and non-SS subjects were co-cultured with the HTLV-1-infected cell line HCT-5 or MOLT-4, then immunofluorescence (IF), scanning and transmission electron microscopy (SEM/TEM) were employed.The extracellular matrix and linker proteins galectin-3, agrin, and tetherin were expressed on the surfaces of both HCT-5 and MOLT-4 cells. HTLV-1 Gag-positive spots were observed on adjacent SGECs after 1 h of co-culture with HCT-5. Both in subjects with and those without SS, agrin and tetherin were co-expressed with HTLV-1 Gag on SGECs after co-culture with HCT-5, although no polarization of HTLV-1 Gag and relevant molecules was observed. SEM showed HTLV-1 virions that were found on HCT-5 were observed in the interfaces between HCT-5 cells and SGECs. TEM imaging showed that HTLV-1 virions were transmitted to SGECs at the interface with thin film-like structure, while HTLV-1 virions were released from the surface of HCT-5 cells. No endogenous retroviruses were observed. These results showed that the initial phase of HTLV-1 infection toward SGECs of SS was mediated not by viral synapses, but by biofilm-like components.

Association between human T cell leukemia virus 1 (HTLV-1) infection and advanced periodontitis in relation to hematopoietic activity among elderly participants: a cross-sectional study

BackgroundWe reported that human T cell leukemia virus 1 (HTLV-1) infection is positively associated with atherosclerosis. Recent evidence has revealed a close association of periodontitis with atherosclerosis, endothelial dysfunction, and disruption of the microcirculation. However, the association between HTLV-1 and advanced periodontitis has not been investigated to date. Since hematopoietic activity is closely linked to endothelial maintenance activity and is known to decline with age, we hypothesized that the state of hematopoietic activity influenced the association between HTLV-1 and advanced periodontitis in elderly participants.MethodsA cross-sectional study was performed including 822 elderly participants aged 60–99 years who participated in a dental health check-up. Advanced periodontitis was defined as a periodontal pocket ≥ 6.0 mm. Participants were classified as having low or high hematopoietic activity according to the median values of reticulocytes.ResultsHTLV-1 infection was positively related to advanced periodontitis among participants with lower hematopoietic activity (lower reticulocyte count), but not among participants with higher hematopoietic activity (higher reticulocyte count). The adjusted odds ratio (95% confidence interval) considering potential confounding factors was 1.92 (1.05–3.49) for participants with a lower reticulocyte count and 0.69 (0.35–1.36) for participants with a higher reticulocyte count.ConclusionsAmong elderly participants, the association between HTLV-1 infection and advanced periodontitis is influenced by hematopoietic activity. Since hematopoietic activity is associated with endothelial maintenance, these findings provide an efficient tool for clarifying the underlying mechanism of the progression of periodontitis among elderly participants.

40 years of the human T-cell leukemia virus: past, present, and future.

It has been nearly 40 years since human T-cell leukemia virus-1 (HTLV-1), the first oncogenic retrovirus in humans and the first demonstrable cause of cancer by an infectious agent, was discovered. Studies indicate that HTLV-1 is arguably one of the most carcinogenic agents to humans. In addition, HTLV-1 causes a diverse array of diseases, including myelopathy and immunodeficiency, which cause morbidity and mortality to many people in the world, including the indigenous population in Australia, a fact that was emphasized only recently. HTLV-1 can be transmitted by infected lymphocytes, from mother to child via breast feeding, by sex, by blood transfusion, and by organ transplant. Therefore, the prevention of HTLV-1 infection is possible but such action has been taken in only a limited part of the world. However, until now it has not been listed by the World Health Organization as a sexually transmitted organism nor, oddly, recognized as an oncogenic virus by the recent list of the National Cancer Institute/National Institutes of Health. Such underestimation of HTLV-1 by health agencies has led to a remarkable lack of funding supporting research and development of treatments and vaccines, causing HTLV-1 to remain a global threat. Nonetheless, there are emerging novel therapeutic and prevention strategies which will help people who have diseases caused by HTLV-1. In this review, we present a brief historic overview of the key events in HTLV-1 research, including its pivotal role in generating ideas of a retrovirus cause of AIDS and in several essential technologies applicable to the discovery of HIV and the unraveling of its genes and their function. This is followed by the status of HTLV-1 research and the preventive and therapeutic developments of today. We also discuss pending issues and remaining challenges to enable the eradication of HTLV-1 in the future.

Human T-Cell Leukemia Virus-1 Infection Is Associated With Atherosclerosis as Measured by Carotid Intima-Media Thickness in Japanese Community-Dwelling Older People.

The association between human T-cell leukemia virus-1 (HTLV-1) and atherosclerosis remains to be determined. This case-control study aimed to investigate this association as measured by carotid intima-media thickness (CIMT). HTLV-1 infection was positively associated with CIMT, independent of atherosclerotic risks.

Identification of a Subset of Peripheral T-Cell Lymphoma, Not Otherwise Specified, Characterized By FOXP3-Positive Regulatory T-Cell Phenotype, HTLV-1 Negativity and Poor Outcome

Background: T-cell malignancies originating from regulatory T (Treg) cells are almost exclusively confined to human T-cell leukemia virus 1 (HTLV-1) associated adult T-cell leukemia/lymphoma (ATLL), although sporadic cases of other peripheral T-cell lymphomas (PTCLs) with hypothesized Treg derivation have been reported.Patients and methods: We investigated a series of 169 well characterized PTCLs for the expression of Treg-cell phenotypic markers FOXP3, CD25 and CD4 by immunohistochemistry (IHC) using tissue microarray on formalin-fixed paraffin embedded tissue. Clinico-pathological data for patients enrolled were retrieved from the Danish Lymphoma Registry and medical records. Treg tumors were further invetsigated by Affymetrix OncoScan analysis and Illumina Infinium HumanMethylation450 BeadChips.Results: Variable amounts of FOXP3-positive Treg cells were often (99% of the cases) found as part of the non-neoplastic cellular infiltrate. However, in five cases (3%) classified as PTCL, not otherwise specified (PTCL-NOS) the vast majority of what morphologically appeared to be the neoplastic cell population displayed a strong positivity for FOXP3, CD4, CD25 and CD3 suggesting a probable Treg origin of these cells. Cases were HTLV-1 negative and showed monoclonal rearrangements of the T-cell receptor genes. All cases were male older than 60 years and showed an aggressive clinical course with overall survival less than two years, despite all patients had low IPI-risk profile at the time of diagnosis. The PTCL with Treg phenotype showed a complex pattern of chromosomal imbalances. Moreover, as compared to normal T-cell subsets their DNA methylation profiles were mostly related to that of normal Treg cells but significantly differed from that.Conclusions: We suggest that FOXP3-positve PTCL, in the absence of HTLV-1 infection, constitute a distinct entity separated from PTCL-NOS, occurring predominantly in elderly male patients and characterized by a highly aggressive clinical behavior. Further genomic analyses are ongoing. The identification and characterization of these cases may be useful to guide upfront therapeutic strategies. DisclosuresNo relevant conflicts of interest to declare.

Role of protein arginine methyltransferase 5 over-expression in HTLV-1-driven cellular transformation and leukemia

Human T-cell leukemia virus-1 (HTLV-1) is a retrovirus that infects an estimated 15-25 million people worldwide. HTLV-1 is the causative infectious agent of adult T-cell leukemia/lymphoma (ATL) and a neurodegenerative disease (HAM/TSP). While the probability of presenting any symptoms related to HTLV-1 infection is relatively low (5-10% for the lifetime of an infected individual), the disease progression and prognosis of those infected individuals who develop ATL is fatal, with a median survival range of 8-10 months. Unfortunately, ATL is highly chemotherapy resistant and while many current therapies improve ATL patient survival, the patients consistently relapse. Therefore, a need exists to develop treatments that improve ATL outcome. We have recently identified PRMT5 (protein arginine methyltransferase 5) as a potential target to modulate HTLV-1 gene expression. We find that PRMT5 levels are elevated in T-cell leukemia/lymphoma cell lines compared to freshly isolated naive T-cells. Likewise, PRMT5 levels are elevated in total PBMCs isolated from ATL patients. However, PRMT5 RNA levels do not correlate to PRMT5 protein levels, suggesting a possible post-transcriptional method of regulation. Furthermore, we also show that PRMT5 levels are elevated during T-cell transformation by using HTLV-1 short-term immortalization assays. Utilizing shRNA vectors, we demonstrate that knockdown of endogenous PRMT5 results in decreased cellular proliferation and increased HTLV-1 viral gene expression. In addition, we observe a decrease in cell proliferation and an increase in viral gene expression when HTLV-1-infected/-transformed cells are treated with a novel small molecule inhibitor of PRMT5 (PRMT5i). Conversely, PRMT5i does not induce re-activation from HIV-1 chronically infected cells. We previously reported a protein-protein interaction between the HTLV-1 accessory protein, p30, and PRMT5. We further show PRMT5 enhances the ability of p30 to inhibit viral gene expression. In conclusion, we find PRMT5 to be a negative regulator of HTLV-1 and a potential target in HTLV-1-mediated disease.

Bromodomain and Extraterminal (BET) Protein Inhibition Suppresses Human T Cell Leukemia Virus 1 (HTLV-1) Tax Protein-mediated Tumorigenesis by Inhibiting Nuclear Factor κB (NF-κB) Signaling

The etiology of human T cell leukemia virus 1 (HTLV-1)-mediated adult T cell leukemia is associated with the ability of viral oncoprotein Tax to induce sustained NF-κB activation and the expression of many NF-κB target genes. Acetylation of the RelA subunit of NF-κB and the subsequent recruitment of bromodomain-containing factor Brd4 are important for the expression of NF-κB target genes in response to various stimuli. However, their contributions to Tax-mediated NF-κB target gene expression and tumorigenesis remain unclear. Here we report that Tax induced the acetylation of lysine 310 of RelA and the binding of Brd4 to acetylated RelA to facilitate Tax-mediated transcriptional activation of NF-κB. Depletion of Brd4 down-regulated Tax-mediated NF-κB target gene expression and cell proliferation. Inhibiting the interaction of Brd4 and acetylated RelA with the bromodomain extraterminal protein inhibitor JQ1 suppressed the proliferation of Tax-expressing rat fibroblasts and Tax-positive HTLV-1-infected cells and Tax-mediated cell transformation and tumorigenesis. Moreover, JQ1 attenuated the Tax-mediated transcriptional activation of NF-κB, triggering the polyubiquitination and proteasome-mediated degradation of constitutively active nuclear RelA. Our results identify Brd4 as a key regulator for Tax-mediated NF-κB gene expression and suggest that targeting epigenetic regulators such as Brd4 with the bromodomain extraterminal protein inhibitor might be a potential therapeutic strategy for cancers and other diseases associated with HTLV-1 infection.

Protective Roles of Epithelial Cells in the Survival of Adult T-Cell Leukemia/Lymphoma Cells

Adult T-cell leukemia/lymphoma (ATL) is a highly invasive and intractable T-cell malignancy caused by human T-cell leukemia virus-1 infection. We demonstrate herein that normal tissue-derived epithelial cells (NECs) exert protective effects on the survival of leukemic cells, which may partially account for high resistance to antileukemic therapies in patients with ATL. Viral gene-silenced, ATL-derived cell lines (ATL cells) dramatically escaped from histone deacetylase inhibitor-induced apoptosis by direct co-culture with NECs. Adhesions to NECs suppressed p21(Cip1) expression and increased a proportion of resting G0/G1 phase cells in trichostatin A (TSA)-treated ATL cells. ATL cells adhering to NECs down-regulated CD25 expression and enhanced vimentin expression, suggesting that most ATL cells acquired a quiescent state by cell-cell interactions with NECs. ATL cells adhering to NECs displayed highly elevated expression of the cancer stem cell marker CD44. Blockade of CD44 signaling diminished the NEC-conferred resistance of ATL cells to TSA-induced apoptosis. Co-culture with NECs also suppressed the expression of NKG2D ligands on TSA-treated ATL cells, resulting in decreased natural killer cell-mediated cytotoxicity. Combined evidence suggests that interactions with normal epithelial cells augment the resistance of ATL cells to TSA-induced apoptosis and facilitate immune evasion by ATL cells.