258 results found
Lewin A, Hamilton S, Witkover A, et al., 2019, Free serum haemoglobin is associated with brain atrophy in secondary progressive multiple sclerosis [version 2; peer review: 3 approved], Wellcome Open Research, Vol: 1, ISSN: 2398-502X
Background: A major cause of disability in secondary progressive multiple sclerosis (SPMS) is progressive brain atrophy, whose pathogenesis is not fully understood. The objective of this study was to identify protein biomarkers of brain atrophy in SPMS. Methods: We used surface-enhanced laser desorption-ionization time-of-flight mass spectrometry to carry out an unbiased search for serum proteins whose concentration correlated with the rate of brain atrophy, measured by serial MRI scans over a 2-year period in a well-characterized cohort of 140 patients with SPMS. Protein species were identified by liquid chromatography-electrospray ionization tandem mass spectrometry. Results: There was a significant (p<0.004) correlation between the rate of brain atrophy and a rise in the concentration of proteins at 15.1 kDa and 15.9 kDa in the serum. Tandem mass spectrometry identified these proteins as alpha-haemoglobin and beta-haemoglobin, respectively. The abnormal concentration of free serum haemoglobin was confirmed by ELISA (p<0.001). The serum lactate dehydrogenase activity was also highly significantly raised (p<10-12) in patients with secondary progressive multiple sclerosis. Conclusions: The results are consistent with the following hypothesis. In progressive multiple sclerosis, low-grade chronic intravascular haemolysis releases haemoglobin into the serum; the haemoglobin is subsequently translocated into the central nervous system (CNS) across the damaged blood-brain barrier. In the CNS, the haemoglobin and its breakdown products, including haem and iron, contribute to the neurodegeneration and consequent brain atrophy seen in progressive disease. We postulate that haemoglobin is a source of the iron whose deposition along blood vessels in multiple sclerosis plaques is associated with neurodegeneration. If so, then chelators of haemoglobin, rather than chelators of free serum iron, may be effective in preventing this neurodegeneration.
Araujo A, Bangham CRM, Casseb J, et al., The management of HAM/TSP: Systematic review and consensus-based recommendations 2019, Neurology: Clinical Practice, ISSN: 2163-0402
Purpose of Review: To provide an evidence-based approach to the use of therapies that are prescribed to improve the natural history of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) – a rare disease.Recent Findings: All 41 articles on the clinical outcome of disease-modifying therapy for HAM/TSP were included in a systematic review by members of the International Retrovirology Association; we report here the consensus assessment and recommendations. The quality of available evidence is low, being based for the most part on observational studies, with only one double-masked placebo-controlled randomised trial. Summary: There is evidence to support the use of both high-dose pulsed methyl prednisolone for induction and low-dose (5mg) oral prednisolone as maintenance therapy for progressive disease. There is no evidence to support the use of antiretroviral therapy. There is insufficient evidence to support the use of interferon-α as a first-line therapy.
Miura M, Dey S, Ramanayake S, et al., 2019, Kinetics of HTLV-1 reactivation from latency quantified by single-molecule RNA FISH and stochastic modelling, PLoS Pathogens, Vol: 15, ISSN: 1553-7366
The human T cell leukemia virus HTLV-1 establishes a persistent infection in vivo in which the viral sense-strand transcription is usually silent at a given time in each cell. However, cellular stress responses trigger the reactivation of HTLV-1, enabling the virus to transmit to a new host cell. Using single-molecule RNA FISH, we measured the kinetics of the HTLV-1 transcriptional reactivation in peripheral blood mononuclear cells (PBMCs) isolated from HTLV-1+ individuals. The abundance of the HTLV-1 sense and antisense transcripts was quantified hourly during incubation of the HTLV-1-infected PBMCs ex vivo. We found that, in each cell, the sense-strand transcription occurs in two distinct phases: the initial low-rate transcription is followed by a phase of rapid transcription. The onset of transcription peaked between 1 and 3 hours after the start of in vitro incubation. The variance in the transcription intensity was similar in polyclonal HTLV-1+ PBMCs (with tens of thousands of distinct provirus insertion sites), and in samples with a single dominant HTLV-1+ clone. A stochastic simulation model was developed to estimate the parameters of HTLV-1 proviral transcription kinetics. In PBMCs from a leukemic subject with one dominant T-cell clone, the model indicated that the average duration of HTLV-1 sense-strand activation by Tax (i.e. the rapid transcription) was less than one hour. HTLV-1 antisense transcription was stable during reactivation of the sense-strand. The antisense transcript HBZ was produced at an average rate of ~0.1 molecules per hour per HTLV-1+ cell; however, between 20% and 70% of HTLV-1-infected cells were HBZ-negative at a given time, the percentage depending on the individual subject. HTLV-1-infected cells are exposed to a range of stresses when they are drawn from the host, which initiate the viral reactivation. We conclude that whereas antisense-strand transcription is stable throughout the stress response, the HTLV-1 sense-strand reactivati
Laydon DJ, Sunkara V, Boelen L, et al., 2019, The relative contributions of infectious and mitotic spread to HTLV-1 persistence
<jats:title>Abstract</jats:title><jats:p>Human T-lymphotropic virus type-1 (HTLV-1) persists within hosts via infectious spread (<jats:italic>de novo</jats:italic>infection) and mitotic spread (infected cell proliferation), creating a population structure of multiple clones (infected cell populations with identical genomic proviral integration sites). The relative contributions of infectious and mitotic spread to HTLV-1 persistence are unknown, and will determine the efficacy of different approaches to treatment.</jats:p><jats:p>The prevailing view is that infectious spread is negligible in HTLV-1 proviral load maintenance beyond early infection. However, in light of recent high-throughput data on the abundance of HTLV-1 clones, and recent estimates of HTLV-1 clonal diversity that are substantially higher than previously thought (typically between 10<jats:sup>4</jats:sup>and 10<jats:sup>5</jats:sup>HTLV-1<jats:sup>+</jats:sup>T cell clones in the body of an asymptomatic carrier or patient with HAM/TSP), ongoing infectious spread during chronic infection remains possible.</jats:p><jats:p>We estimate the ratio of infectious to mitotic spread using a hybrid model of deterministic and stochastic processes, fitted to previously published HTLV-1 clonal diversity estimates. We investigate the robustness of our estimates using two alternative methods. We find that, contrary to previous belief, infectious spread persists during chronic infection, even after HTLV-1 proviral load has reached its set point, and we estimate that between 100 and 200 new HTLV-1 clones are created and killed every day. We find broad agreement between all three methods.</jats:p><jats:p>The risk of HTLV-1-associated malignancy and inflammatory disease is strongly correlated with proviral load, which in turn is correlated with the number of HTLV-1-infected clones, which are created by de novo infectio
Bangham CRM, Miura M, Kulkarni A, et al., Regulation of Latency in the Human T Cell Leukemia Virus, HTLV-1., Annu Rev Virol
The human T cell leukemia virus persists in vivo in 103 to 106 clones of T lymphocytes that appear to survive for the lifetime of the host. The plus strand of the provirus is typically transcriptionally silent in freshly isolated lymphocytes, but the strong, persistently activated cytotoxic T lymphocyte (CTL) response to the viral antigens indicates that the virus is not constantly latent in vivo. There is now evidence that the plus strand is transcribed in intense intermittent bursts that are triggered by cellular stress, modulated by hypoxia and glycolysis, and inhibited by polycomb repressive complex 1 (PRC1). The minus-strand gene hbz is transcribed at a lower, more constant level but is silent in a proportion of infected cells at a given time. Viral genes in the sense and antisense strands of the provirus play different respective roles in latency and de novo infection: Expression of the plus-strand gene tax is essential for de novo infection, whereas hbz appears to facilitate survival of the infected T cell clone in vivo. Expected final online publication date for the Annual Review of Virology Volume 6 is September 30, 2019. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Cook L, Demontis MA, Sagawe S, et al., 2019, Molecular remissions are observed in chronic adult T cell leukemia/lymphoma in patients treated with mogamulizumab, Haematologica, ISSN: 0390-6078
Cook L, Demontis MA, Sagawe S, et al., 2019, Molecular remissions are observed in chronic adult T-cell leukaemia/lymphoma in patients treated with mogamulizumab, 59th Annual Scientific Meeting of the British-Society-for-Hematology, Publisher: WILEY, Pages: 172-173, ISSN: 0007-1048
Turpin J, Yurick D, Khoury G, et al., 2019, Impact of Hepatitis B virus coinfection on human T-lymphotropic virus type 1 clonality in an indigenous population of central Australia, Journal of Infectious Diseases, Vol: 219, Pages: 562-567, ISSN: 0022-1899
The prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and hepatitis B virus (HBV) coinfection is high in certain Indigenous Australian populations, but its impact on HTLV-1 has not been described. We compared 2 groups of Indigenous adults infected with HTLV-1, either alone or coinfected with HBV. The 2 groups had a similar HTLV-1 proviral load, but there was a significant increase in clonal expansion of HTLV-1–infected lymphocytes in coinfected asymptomatic individuals. The degree of clonal expansion was correlated with the titer of HBV surface antigen. We conclude that HTLV-1/HBV coinfection may predispose to HTLV-1–associated malignant disease.
Miura M, Miyazato P, Satou Y, et al., 2018, Epigenetic changes around the pX region and spontaneous HTLV-1 transcription are CTCF-independent [version 2; approved 2], Wellcome Open Research, Vol: 3, ISSN: 2398-502X
Background: The human retrovirus HTLV-1 inserts the viral complementary DNA of 9 kb into the host genome. Both plus- and minus-strands of the provirus are transcribed, respectively from the 5' and 3' long terminal repeats (LTR). Plus-strand expression is rapid and intense once activated, whereas the minus-strand is transcribed at a lower, more constant level. To identify how HTLV-1 transcription is regulated, we investigated the epigenetic modifications associated with the onset of spontaneous plus-strand expression and the potential impact of the host factor CTCF. Methods: Patient-derived peripheral blood mononuclear cells (PBMCs) and in vitro HTLV-1-infected T cell clones were examined. Cells were stained for the plus-strand-encoded viral protein Tax, and sorted into Tax + and Tax - populations. Chromatin immunoprecipitation and methylated DNA immunoprecipitation were performed to identify epigenetic modifications in the provirus. Bisulfite-treated DNA fragments from the HTLV-1 LTRs were sequenced. Single-molecule RNA-FISH was performed, targeting HTLV-1 transcripts, for the estimation of transcription kinetics. The CRISPR/Cas9 technique was applied to alter the CTCF-binding site in the provirus, to test the impact of CTCF on the epigenetic modifications. Results: Changes in the histone modifications H3K4me3, H3K9Ac and H3K27Ac were strongly correlated with plus-strand expression. DNA in the body of the provirus was largely methylated except for the pX and 3' LTR regions, regardless of Tax expression. The plus-strand promoter was hypomethylated when Tax was expressed. Removal of CTCF had no discernible impact on the viral transcription or epigenetic modifications. Conclusions: The histone modifications H3K4me3, H3K9Ac and H3K27Ac are highly dynamic in the HTLV-1 provirus: they show rapid change with the onset of Tax expression, and are reversible. The HTLV-1 provirus has an intrinsic pattern of epigenetic modifications that is independent of both the provirus inse
Bangham CRM, Taylor GP, Klose RJ, et al., 2018, Histone H2A mono-ubiquitylation and p38-MAP Kinases regulate immediate-early gene-like reactivation of latent retrovirus HTLV-1, Journal of Clinical Investigation, Vol: 3, ISSN: 0021-9738
It is not understood how the human T cell leukemia virus human T-lymphotropic virus-1 (HTLV-1), a retrovirus, regulates the in vivo balance between transcriptional latency and reactivation. The HTLV-1 proviral plus-strand is typically transcriptionally silent in freshly isolated peripheral blood mononuclear cells from infected individuals, but after short-term ex vivo culture, there is a strong, spontaneous burst of proviral plus-strand transcription. Here, we demonstrate that proviral reactivation in freshly isolated, naturally infected primary CD4+ T cells has 3 key attributes characteristic of an immediate-early gene. Plus-strand transcription is p38-MAPK dependent and is not inhibited by protein synthesis inhibitors. Ubiquitylation of histone H2A (H2AK119ub1), a signature of polycomb repressive complex-1 (PRC1), is enriched at the latent HTLV-1 provirus, and immediate-early proviral reactivation is associated with rapid deubiquitylation of H2A at the provirus. Inhibition of deubiquitylation by the deubiquitinase (DUB) inhibitor PR619 reverses H2AK119ub1 depletion and strongly inhibits plus-strand transcription. We conclude that the HTLV-1 proviral plus-strand is regulated with characteristics of a cellular immediate-early gene, with a PRC1-dependent bivalent promoter sensitive to p38-MAPK signaling. Finally, we compare the epigenetic signatures of p38-MAPK inhibition, DUB inhibition, and glucose deprivation at the HTLV-1 provirus, and we show that these pathways act as independent checkpoints regulating proviral reactivation from latency.
Katsuya H, Cook LB, Rowan A, et al., 2018, Phosphatidylinositol 3-kinase-delta (PI3K-delta) is a potential therapeutic target in adult T-cell leukemia-lymphoma, Biomarker Research, Vol: 6, ISSN: 2050-7771
The prognosis of adult T-cell leukemia-lymphoma (ATL) remains very poor, and there is an urgent clinical need to investigate novel therapies for ATL. The expression of phosphatidylinositol 3-kinase-δ (PI3k-δ) is normally restricted to hematopoietic cells and is known as a key determinant of cell survival in certain cancers. The inhibitor of PI3k-δ, idelalisib, has been shown to be effective in the treatment of chronic lymphocytic leukemia. Here, we report the expression of PI3k-δ and the ability of idelalisib to promote apoptosis in ex vivo ATL samples. The activity of PI3K was quantified by a PI3-Kinase Activity ELISA kit. Although there was no significant difference in mean PI3K activity between healthy donors and patients with ATL, certain cases of ATL showed extremely high PI3K activities. The expression of PI3k-δ protein was detectable in most ATL cases. The freshly isolated cells from ATL patients were cultured with or without idelalisib for 0–10 days, and cell survival was then quantified. Idelalisib induced apoptosis in ATL cells in a time-dependent manner, and significantly reduced the frequency of viable ATL cells at 10 days. No time-dependent effects of idelalisib were observed in non-malignant T cells from the same patients. CCL22 has been reported to promote survival of ATL cells in part through the PI3K-AKT pathway. Idelalisib blocked this CCL22-induced phosphorylation of AKT and significantly inhibited the proliferation of ATL cells. These results validate the PI3K-AKT pathway as a potential therapeutic target in ATL.
Bangham CRM, Melamed A, Yaguchi H, et al., 2018, The human leukemia virus HTLV-1 alters the structure and transcription of host chromatin in cis, eLife, Vol: 7, ISSN: 2050-084X
Chromatin looping controls gene expression by regulating promoter-enhancer contacts, the spread of epigenetic modifications, and the segregation of the genome into transcriptionally active and inactive compartments. We studied the impact on the structure and expression of host chromatin by the human retrovirus HTLV-1. We show that HTLV-1 disrupts host chromatin structure by forming loops between the provirus and the host genome; certain loops depend on the critical chromatin architectural protein CTCF, which we recently discovered binds to the HTLV-1 provirus. We show that the provirus causes two distinct patterns of abnormal transcription of the host genome in cis: bidirectional transcription in the host genome immediately flanking the provirus, and clone-specific transcription in cis at non-contiguous loci up to >300 kb from the integration site. We conclude that HTLV-1 causes insertional mutagenesis up to the megabase range in the host genome in >104 persistently-maintained HTLV-1+ T-cell clones in vivo.
Melamed A, Yaguchi H, Miura M, et al., 2018, The human leukemia virus HTLV-1 alters the structure and transcription of host chromatin in cis, Publisher: Cold Spring Harbor Laboratory
<jats:title>Abstract</jats:title><jats:p>Chromatin looping controls gene expression by regulating promoter-enhancer contacts, the spread of epigenetic modifications, and the segregation of the genome into transcriptionally active and inactive compartments. We studied the impact on the structure and expression of host chromatin by the human retrovirus HTLV-1. We show that HTLV-1 disrupts host chromatin structure by forming loops between the provirus and the host genome; certain loops depend on the critical chromatin architectural protein CTCF, which we recently showed binds to the HTLV-1 provirus. Finally, we show that the provirus causes two distinct patterns of abnormal transcription of the host genome <jats:italic>in cis</jats:italic>: bidirectional transcription in the host genome immediately flanking the provirus, and clone-specific transcription <jats:italic>in cis</jats:italic> at non-contiguous loci up to >300 kb from the integration site. We conclude that HTLV-1 causes insertional mutagenesis up to the megabase range in the host genome in >10<jats:sup>4</jats:sup> persistently-maintained HTLV-1<jats:sup>+</jats:sup> T-cell clones in vivo.</jats:p>
Satou Y, Katsuya H, Fukuda A, et al., 2018, Dynamics and mechanisms of clonal expansion of HIV-1-infected cells in a humanized mouse model (vol 7, 6913, 2017), SCIENTIFIC REPORTS, Vol: 8, ISSN: 2045-2322
Kulkarni A, Bangham CRM, 2018, HTLV-1: Regulating the Balance Between Proviral Latency and Reactivation, FRONTIERS IN MICROBIOLOGY, Vol: 9, ISSN: 1664-302X
HTLV-1 plus-strand transcription begins with the production of doubly-spliced tax/rex transcripts, the levels of which are usually undetectable in freshly isolated peripheral blood mononuclear cells (PBMCs) from HTLV-1-infected individuals. However, the presence of a sustained chronically active cytotoxic T-cell response to HTLV-1 antigens in virtually all HTLV-1-infected individuals, regardless of their proviral load, argues against complete latency of the virus in vivo. There is an immediate burst of plus-strand transcription when blood from infected individuals is cultured ex vivo. How is the HTLV-1 plus strand silenced in PBMCs? Is it silenced in other anatomical compartments within the host? What reactivates the latent provirus in fresh PBMCs? While plus-strand transcription of the provirus appears to be intermittent, the minus-strand hbz transcripts are present in a majority of cells, albeit at low levels. What regulates the difference between the 5′- and 3′-LTR promoter activities and thereby the tax-hbz interplay? Finally, T lymphocytes are a migratory population of cells that encounter variable environments in different compartments of the body. Could these micro-environment changes influence the reactivation kinetics of the provirus? In this review we discuss the questions raised above, focusing on the early events leading to HTLV-1 reactivation from latency, and suggest future research directions.
Bangham CRM, 2018, Human T Cell Leukemia Virus Type 1: Persistence and Pathogenesis, ANNUAL REVIEW OF IMMUNOLOGY, VOL 36, Vol: 36, Pages: 43-71, ISSN: 0732-0582
Billman MR, Rueda D, Bangham CRM, 2017, Single-cell heterogeneity and cell-cycle-related viral gene bursts in the human leukaemia virus HTLV-1 [version 2; peer review: 2 approved, 1 approved with reservations], Wellcome Open Research, Vol: 2, ISSN: 2398-502X
Background: The human leukaemia virus HTLV-1 expresses essential accessory genes that manipulate the expression, splicing and transport of viral mRNAs. Two of these genes, tax and hbz, also promote proliferation of the infected cell, and both genes are thought to contribute to oncogenesis in adult T-cell leukaemia/lymphoma. The regulation of HTLV-1 proviral latency is not understood. tax, on the proviral plus strand, is usually silent in freshly-isolated cells, whereas the minus-strand-encoded hbz gene is persistently expressed at a low level. However, the persistently activated host immune response to Tax indicates frequent expression of tax in vivo. Methods: We used single-molecule RNA-FISH to quantify the expression of HTLV-1 transcripts at the single-cell level in a total of >19,000 cells from five T-cell clones, naturally infected with HTLV-1, isolated by limiting dilution from peripheral blood of HTLV-1-infected subjects. Results: We found strong heterogeneity both within and between clones in the expression of the proviral plus-strand (detected by hybridization to the tax gene) and the minus-strand (hbz gene). Both genes are transcribed in bursts; tax expression is enhanced in the absence of hbz, while hbz expression increased in cells with high tax expression. Surprisingly, we found that hbz expression is strongly associated with the S and G 2/M phases of the cell cycle, independent of tax expression. Contrary to current belief, hbz is not expressed in all cells at all times, even within one clone. In hbz-positive cells, the abundance of hbz transcripts showed a very strong positive linear correlation with nuclear volume.Conclusions: The occurrence of intense, intermittent plus-strand gene bursts in independent primary HTLV-1-infected T-cell clones from unrelated individuals strongly suggests that the HTLV-1 plus-strand is expressed in bursts in vivo. Our results offer an explanation for the paradoxical correlations observed between the host immune
Furuta R, Yasunaga J-I, Miura M, et al., 2017, Human T-cell leukemia virus type 1 infects multiple lineage hematopoietic cells in vivo., PLoS Pathogens, Vol: 13, ISSN: 1553-7366
Human T-cell leukemia virus type 1 (HTLV-1) infects mainly CD4+CCR4+ effector/memory T cells in vivo. However, it remains unknown whether HTLV-1 preferentially infects these T cells or this virus converts infected precursor cells to specialized T cells. Expression of viral genes in vivo is critical to study viral replication and proliferation of infected cells. Therefore, we first analyzed viral gene expression in non-human primates naturally infected with simian T-cell leukemia virus type 1 (STLV-1), whose virological attributes closely resemble those of HTLV-1. Although the tax transcript was detected only in certain tissues, Tax expression was much higher in the bone marrow, indicating the possibility of de novo infection. Furthermore, Tax expression of non-T cells was suspected in bone marrow. These data suggest that HTLV-1 infects hematopoietic cells in the bone marrow. To explore the possibility that HTLV-1 infects hematopoietic stem cells (HSCs), we analyzed integration sites of HTLV-1 provirus in various lineages of hematopoietic cells in patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a HTLV-1 carrier using the high-throughput sequencing method. Identical integration sites were detected in neutrophils, monocytes, B cells, CD8+ T cells and CD4+ T cells, indicating that HTLV-1 infects HSCs in vivo. We also detected Tax protein in myeloperoxidase positive neutrophils. Furthermore, dendritic cells differentiated from HTLV-1 infected monocytes caused de novo infection to T cells, indicating that infected monocytes are implicated in viral spreading in vivo. Certain integration sites were re-detected in neutrophils from HAM/TSP patients at different time points, indicating that infected HSCs persist and differentiate in vivo. This study demonstrates that HTLV-1 infects HSCs, and infected stem cells differentiate into diverse cell lineages. These data indicate that infection of HSCs can contribute to the persistence and spread
Cook LB, Rowan A, Demontis M, et al., 2017, Long-term clinical remission maintained after cessation of zidovudine and interferon-α therapy in chronic adult T-cell leukemia/lymphoma, International Journal of Hematology, Vol: 107, Pages: 378-382, ISSN: 0925-5710
Globally, > 5–10 million people are estimated to be infected with Human T-lymphotropic virus type 1 (HTLV-1), of whom ~ 5% develop adult T-cell leukemia/lymphoma (ATL). Despite advances in chemotherapy, overall survival (OS) has not improved in the 35 years since HTLV-1 was first described. In Europe/USA, combination treatment with zidovudine and interferon-α (ZDV/IFN-α) has substantially changed the management of patients with the leukemic subtypes of ATL (acute or unfavorable chronic ATL) and is under clinical trial evaluation in Japan. However, there is only a single published report of long-term clinical remission on discontinuing ZDV/IFN-α therapy and the optimal duration of treatment is unknown. Anecdotal cases where therapy is discontinued due to side effects or compliance have been associated with rapid disease relapse, and it has been widely accepted that the majority of patients will require life-long therapy. The development of molecular methods to quantify minimal residual disease is essential to potentially guide therapy for individual patients. Here, for the first time, we report molecular evidence that supports long-term clinical remission in a patient who was previously treated with ZDV/IFN-α for 5 years, and who has now been off all therapy for over 6 years.
Bangham CRM, Matsuoka M, 2017, Human T-cell leukaemia virus type 1: parasitism and pathogenesis, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 372, ISSN: 0962-8436
Human T-cell leukaemia virus type 1 (HTLV-1) causes not only adult T-cell leukaemia-lymphoma (ATL), but also inflammatory diseases including HTLV-1-associated myelopathy/tropical spastic paraparesis. HTLV-1 transmits primarily through cell-to-cell contact, and generates abundant infected cells in the host in order to survive and transmit to a new host. The resulting high proviral load is closely associated with the development of ATL and inflammatory diseases. To increase the number of infected cells, HTLV-1 changes the immunophenotype of infected cells, induces proliferation and inhibits apoptosis through the cooperative actions of two viral genes, tax and HTLV-1 bZIP factor (HBZ). As a result, infected cells survive, proliferate and infiltrate into the tissues, which is critical for transmission of the virus. Thus, the strategy of this virus is indivisibly linked with its pathogenesis, providing a clue for prevention and treatment of HTLV-1-induced diseases.
Kulkarni A, Mateus M, Thinnes CC, et al., 2017, Glucose metabolism and oxygen availability govern reactivation from latency of the human retrovirus HTLV-1, Cell Chemical Biology, Vol: 24, Pages: 1377-1387.e3, ISSN: 2451-9456
The human retrovirus HTLV-1 causes a hematological malignancy or neuroinflammatory disease in ∼10% of infected individuals. HTLV-1 primarily infects CD4+ T lymphocytes and persists as a provirus integrated in their genome. HTLV-1 appears transcriptionally latent in freshly isolated cells; however, the chronically active anti-HTLV-1 cytotoxic T cell response observed in infected individuals indicates frequent proviral expression in vivo. The kinetics and regulation of HTLV-1 proviral expression in vivo are poorly understood. By using hypoxia, small-molecule hypoxia mimics, and inhibitors of specific metabolic pathways, we show that physiologically relevant levels of hypoxia, as routinely encountered by circulating T cells in the lymphoid organs and bone marrow, significantly enhance HTLV-1 reactivation from latency. Furthermore, culturing naturally infected CD4+ T cells in glucose-free medium or chemical inhibition of glycolysis or the mitochondrial electron transport chain strongly suppresses HTLV-1 plus-strand transcription. We conclude that glucose metabolism and oxygen tension regulate HTLV-1 proviral latency and reactivation in vivo.
Billman MR, Rueda D, Bangham CRM, 2017, Single-cell heterogeneity and cell-cycle-related viral gene bursts in the human leukaemia virus HTLV-1 [version 1; peer review: 2 approved, 1 approved with reservations], Wellcome Open Research, Vol: 2, Pages: 87-87, ISSN: 2398-502X
Background: The human leukaemia virus HTLV-1 expresses essential accessory genes that manipulate the expression, splicing and transport of viral mRNAs. Two of these genes, tax and hbz, also promote proliferation of the infected cell, and both genes are thought to contribute to oncogenesis in adult T-cell leukaemia/lymphoma. The regulation of HTLV-1 proviral latency is not understood. tax, on the proviral plus strand, is usually silent in freshly-isolated cells, whereas the minus-strand-encoded hbz gene is persistently expressed at a low level. However, the persistently activated host immune response to Tax indicates frequent expression of tax in vivo. Methods: We used single-molecule RNA-FISH to quantify the expression of HTLV-1 transcripts at the single-cell level in a total of >19,000 cells from five T-cell clones, naturally infected with HTLV-1, isolated by limiting dilution from peripheral blood of HTLV-1-infected subjects. Results: We found strong heterogeneity both within and between clones in the expression of the proviral plus-strand (detected by hybridization to the tax gene) and the minus-strand ( hbz gene). Both genes are transcribed in bursts; tax expression is enhanced in the absence of hbz, while hbz expression increased in cells with high tax expression. Surprisingly, we found that hbz expression is strongly associated with the S and G 2/M phases of the cell cycle, independent of tax expression. Contrary to current belief, hbz is not expressed in all cells at all times, even within one clone. In hbz-positive cells, the abundance of hbz transcripts showed a very strong positive linear correlation with nuclear volume. Conclusions: The occurrence of intense, intermittent plus-strand gene bursts in independent primary HTLV-1-infected T-cell clones from unrelated individuals strongly suggests that the HTLV-1 plus-strand is expressed in bursts in vivo. Our results offer an explanat
Human T-lymphotropic virus type-1 (HTLV-1) is the causative agent of adult T-cell leukaemia/lymphoma (ATL), an aggressive CD4+ T-cell malignancy. The mechanisms of leukaemogenesis in ATL are incompletely understood. Insertional mutagenesis has not previously been thought to contribute to the pathogenesis of ATL. However, the recent discovery that HTLV-1 binds the key chromatin architectural protein CTCF raises the hypothesis that HTLV-1 deregulates host gene expression by causing abnormal chromatin looping, bringing the strong HTLV-1 promoter-enhancer near to host genes that lie up to 2Mb from the integrated provirus. Here we review current opinion on the mechanisms of oncogenesis in ATL, with particular emphasis on the local and distant impact of HTLV-1 on the structure and expression of the host genome.
Satou Y, Katsuya H, Fukuda A, et al., 2017, Dynamics and mechanisms of clonal expansion of HIV-1-infected cells in a humanized mouse model., Scientific Reports, Vol: 7, ISSN: 2045-2322
Combination anti-retroviral therapy (cART) has drastically improved the clinical outcome of HIV-1 infection. Nonetheless, despite effective cART, HIV-1 persists indefinitely in infected individuals. Clonal expansion of HIV-1-infected cells in peripheral blood has been reported recently. cART is effective in stopping the retroviral replication cycle, but not in inhibiting clonal expansion of the infected host cells. Thus, the proliferation of HIV-1-infected cells may play a role in viral persistence, but little is known about the kinetics of the generation, the tissue distribution or the underlying mechanism of clonal expansion in vivo. Here we analyzed the clonality of HIV-1-infected cells using high-throughput integration site analysis in a hematopoietic stem cell-transplanted humanized mouse model. Clonally expanded, HIV-1-infected cells were detectable at two weeks post infection, their abundance increased with time, and certain clones were present in multiple organs. Expansion of HIV-1-infected clones was significantly more frequent when the provirus was integrated near host genes in specific gene ontological classes, including cell activation and chromatin regulation. These results identify potential drivers of clonal expansion of HIV-1-infected cells in vivo.
Zhyvoloup A, Melamed A, Anderson I, et al., 2017, Digoxin reveals a functional connection between HIV-1 integration preference and T-cell activation, PLOS PATHOGENS, Vol: 13, ISSN: 1553-7366
HIV-1 integrates more frequently into transcribed genes, however the biological significance of HIV-1 integration targeting has remained elusive. Using a selective high-throughput chemical screen, we discovered that the cardiac glycoside digoxin inhibits wild-type HIV-1 infection more potently than HIV-1 bearing a single point mutation (N74D) in the capsid protein. We confirmed that digoxin repressed viral gene expression by targeting the cellular Na+/K+ ATPase, but this did not explain its selectivity. Parallel RNAseq and integration mapping in infected cells demonstrated that digoxin inhibited expression of genes involved in T-cell activation and cell metabolism. Analysis of >400,000 unique integration sites showed that WT virus integrated more frequently than N74D mutant within or near genes susceptible to repression by digoxin and involved in T-cell activation and cell metabolism. Two main gene networks down-regulated by the drug were CD40L and CD38. Blocking CD40L by neutralizing antibodies selectively inhibited WT virus infection, phenocopying digoxin. Thus the selectivity of digoxin depends on a combination of integration targeting and repression of specific gene networks. The drug unmasked a functional connection between HIV-1 integration and T-cell activation. Our results suggest that HIV-1 evolved integration site selection to couple its early gene expression with the status of target CD4+ T-cells, which may affect latency and viral reactivation.
Macchi B, Balestrieri E, Frezza C, et al., 2017, Quantification of HTLV-1 reverse transcriptase activity in ATL patients treated with zidovudine and interferon-α, Blood Advances, Vol: 1, Pages: 748-752, ISSN: 2473-9529
Bangham CRM, Gillet N, Melamed A, 2017, High-throughput mapping and clonal quantification of retroviral integration sites, Methods in Molecular Biology
Kagdi HH, taylor GPT, DEMONTIS MA, et al., 2016, Risk stratification of adult T cell leukemia/lymphoma using immunophenotyping, Cancer Medicine, Vol: 6, Pages: 298-309, ISSN: 2045-7634
Adult T cell leukemia/lymphoma (ATL), a human T lymphotropic virus type 1 (HTLV-1) –associated disease, has a highly variable clinical course and four subtypes with therapeutic and prognostic implications. However, there are overlapping features between ATL subtypes and between ATL and non-malignant (non-ATL) HTLV-1 infection complicating diagnosis and prognostication. To further refine the diagnosis and prognosis of ATL we characterized the immunophenotype of HTLV-1-infected cells in ATL and non-ATL. A retrospective study of peripheral blood samples from ten HTLV-1-uninfected subjects (UI), 54 HTLV-1infected patients with non-ATL and 22 with ATL was performed using flow cytometry. All patients with ATL had CD4+CCR4+CD26- immunophenotype and the frequency of CD4+CCR4+CD26- T cells correlated highly significantly with the proviral load in non-ATL suggesting CD4+CCR4+CD26- as a marker of HTLV-1 infected cells. Further immunophenotyping of CD4+CCR4+CD26- cells revealed that 95% patients with ATL had a CD7- (≤ 30% CD7+ cells) whereas 95% HTLV+ non-ATL had CD7+ (>30% CD7+ cells) immunophenotype. All patients with aggressive ATL had a CCR7+ (≥30%), whereas 92 % with indolent ATL and 100% non-ATL had a CCR7- (<30%) immunophenotype. Patients with non-progressing indolent ATL were CD127+ but those with progressive lymphocytosis requiring systemic therapy had a CD127- (≤ 30%) immunophenotype. In summary, HTLV-1-infected cells have a CD4+CCR4+CD26- immunophenotype. Within this population, CD7- phenotype suggests a diagnosis of ATL, CCR7+ phenotype identifies aggressive ATL, while CCR7- CD127- phenotype identifies progressive indolent ATL.
Human T-cell leukemia virus-1 (HTLV-1) is the first pathogenic human retrovirus discovered in 1980.1 HTLV-1 causes 2 devastating diseases: adult T-cell leukemia/lymphoma (ATL) and a neurological disorder, HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP or, more briefly, HAM). ATL becomes apparent in 2% to 5% of those infected with HTLV-1; another 1% to 2% will develop HAM.2 There are usually 2 to 3 decades of latency after the infection before the onset of symptoms. A second HTLV (HTLV-2) isolated in 1982 has been causally linked to HAM, but not ATL.3In other cases, HTLV-1 and HTLV-2 infection may remain asymptomatic for years while being transmitted from person-to-person through host cells in body fluids and breast milk, blood cell transfusions, and solid organ transplantation. There are no licensed vaccines to prevent HTLV-1 or HTLV-2 infections.
Turpin J, Alais S, Marcais A, et al., 2016, Whole body clonality analysis in an aggressive STLV-1 associated leukemia (ATLL) reveals an unexpected clonal complexity, CANCER LETTERS, Vol: 389, Pages: 78-85, ISSN: 0304-3835
HTLV-1 causes Adult T cell Leukemia/Lymphoma (ATLL) in humans. We describe an ATL-like disease in a 9 year-old female baboon naturally infected with STLV-1 (the simian counterpart of HTLV-1), with a lymphocyte count over 1010/L, lymphocytes with abnormal nuclear morphology, and pulmonary and skin lesions. The animal was treated with a combination of AZT and alpha interferon. Proviral load (PVL) was measured every week. Because the disease continued to progress, the animal was euthanized. Abnormal infiltrates of CD3+CD25+ lymphocytes and Tax-positive cells were found by histological analyses in both lymphoid and non-lymphoid organs. PVL was measured and clonal diversity was assessed by LM-PCR (Ligation-Mediated Polymerase Chain Reaction) and high throughput sequencing, in blood during treatment and in 14 different organs. The highest PVL was found in lymph nodes, spleen and lungs. One major clone and a number of intermediate abundance clones were present in blood throughout the course of treatment, and in organs. These results represent the first multi-organ clonality study in ATLL. We demonstrate a previously undescribed clonal complexity in ATLL. Our data reinforce the usefulness of natural STLV-1 infection as a model of ATLL.
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