Human T-cell Lymphotrophic Virus Type Research Articles

The Cause and Consequence of Replication Stress in Adult T-Cell Leukemia

EP300 and its homolog CBP are transcriptional co-activators of genes involved in a broad range of cellular processes, including proliferation, differentiation, apoptosis and DNA repair. Inactivating mutations in both EP300 and CBP have been reported in developmental disorders, such as Rubinstein-Taybi Syndrome, and several hematological malignancies. Most recently, somatic hypermutations in EP300 (but not CBP) were identified in Adult T-cell leukemia/lymphoma (ATLL) patients, diagnosed in Northern America. The mechanistic contribution of EP300 dysregulation to NA-ATLL etiology is currently unknown. ATLL is caused by infection by the Human T-cell Lymphotrophic Virus Type-1 (HTLV-1), that is endemic to Japan, the Caribbean basin, South America, southern parts of North America, Eastern Europe and certain areas of Africa. Unlike patients diagnosed in Japan (J-ATLL), NA-ATLL patient display a severe case of chemo-refractory disease with very poor prognosis. While prominent differences in the transcriptional and epigenetic landscape, particularly the p300 mutational status, has been identified between J-ATLL and NA-ATLL patients, the mechanistic contribution of p300 dysregulation to disease severity is yet to be established. Studies have revealed that the independent inhibition of EP300 in human cells results in a unique transcriptional landscape, involving the differential expression of genes involved in regulating the cell cycle, DNA replication and DNA damage response. Here, we show that EP300-mutated ATLL cells display a protracted S-phase, extensive genomic instability, dysregulations in DNA replication and repair dynamics. Using a powerful locus specific single molecule assay and genome-wide DNA fiber analysis, we show that perturbed DNA replication in EP300-mutated ATLL cells is characterized by elevated origin firing, increased replisome pausing and prominent nucleolytic degradation of nascent DNA at collapsed forks. The elevated origin firing in the absence of EP300 is likely driven by the inherent endogenous increase in c-MYC expression, which has been previously seen in EP300-mutated MCF7 cells. The striking replication pausing, fork collapse and nascent strand degradation observed in EP300-deficient NA-ATLL cells results in the persistence of single stranded DNA (ssDNA) genome-wide, resulting in the hyperphosphorylation of RPA at Ser4/8. Inhibition of Mre11 nuclease partially rescued the ssDNA accumulation indicating a dysregulation in downstream mechanisms that restrain nuclease activity at stalled forks. Elevated endogenous genomic instability, observed in ATLL cells during the S-phase is exacerbated by EP300 deficiency, even in the absence of exogenous stress/damage. Analysis of the consequences of S-phase abnormalities and genomic instability revealed elevated micronuclei and cytosolic DNA in ATLL cells exposed to DNA damage. Preliminary studies evaluating the innate immune system activation (cGAS-STING-pIRF3) by immunoblotting, in response to stress, has led to some intriguing results. There is a clear separation in the ability of J-ATLL versus NA-ATLL cells in activating the innate immune system, a response that appears to be EP300 independent. These results raise the possibility of the contribution of a suppressed innate immune response, a phenomenon seen in many fast-progressing cancers, to the etiology of NA-ATLL. In addition to increasing our understanding of the mechanisms contributing to ATLL in general, the results from this study have helped identify new mechanism-based treatment regimens that could target the replicative and innate immune system vulnerabilities observed in North American ATLL patients.

A Review of the Prevention of Mother-to-Child Transmission of Human T-Cell Lymphotrophic Virus Type 1 (HTLV-1) With a Proposed Management Algorithm.

Human T cell lymphotropic virus type 1 (HTLV-1) is a human retrovirus that is endemic in a number of regions across the world. There are an estimated 5–10 million people infected worldwide. Japan is currently the only country with a national antenatal screening programme in place. HTLV-1 is primarily transmitted sexually in adulthood, however it can be transmitted from mother-to-child perinatally. This can occur transplacentally, during the birth process or via breastmilk. If HTLV-1 is transmitted perinatally then the lifetime risk of adult T cell leukemia/lymphoma rises from 5 to 20%, therefore prevention of mother-to-child transmission of HTLV-1 is a public health priority. There are reliable immunological and molecular tests available for HTLV-1 diagnosis during pregnancy and screening should be considered on a country by country basis. Further research on best management is needed particularly for pregnancies in women with high HTLV-1 viral load. A first step would be to establish an international registry of cases and to monitor outcomes for neonates and mothers. We have summarized key risk factors for mother-to-child transmission of HTLV-1 and subsequently propose a pragmatic guideline for management of mothers and infants in pregnancy and the perinatal period to reduce the risk of transmission. This is clinically relevant in order to reduce mother-to-child transmission of HTLV-1 and it's complications.

Epidemiology of Virus Infection and Human Cancer.

Seven viruses including the Epstein-Barr virus (EBV), hepatitis B virus (HBV), hepatitis C virus (HCV), Kaposi's sarcoma herpes virus (KSHV), human immunodeficiency virus, type-1 (HIV-1), human T cell lymphotrophic virus, type-1 (HTLV-1), and human papillomavirus (HPV) have been classified as Group 1 human carcinogens by the International Agency for Research on Cancer (IARC). The conclusions are based on the findings of epidemiological and mechanistic studies. EBV, HPV, HTLV-1, and KSHV are direct carcinogens; HBV and HCV are indirect carcinogens through chronic inflammation; and HIV-1 is an indirect carcinogen through immune suppression. Some viruses may cause more than one cancer, while some cancers may be caused by more than one virus. However, only a proportion of persons infected by these oncogenic viruses will develop specific cancers. A series of studies have been carried out to assess the viral, host, and environmental cofactors of EBV-associated nasopharyngeal carcinoma, HBV/HCV-associated hepatocellular carcinoma, and HPV-associated cervical carcinoma. Persistent infection, high viral load, and viral genotype are important risk predictors of these virus-caused cancers. Risk calculators incorporating host and viral risk predictors have been developed for the prediction of long-term risk of hepatocellular carcinoma, nasopharyngeal carcinoma and cervical cancer. These risk calculators are useful for the triage and clinical management of infected patients. Both clinical trials and national programs of immunization, antiviral therapy and screening have demonstrated a significant reduction in the incidence of cancers caused by HBV, HCV, and HPV. Future research on gene-gene and gene-environment interactions of oncogenic viruses and the human host using large-scale longitudinal studies with serial measurements of biosignatures are in urgent need.

Early and Successful Combination Antiretroviral Therapy Normalizes Survival Time in Patients Coinfected With Human Immunodeficiency Virus and Human T-cell Lymphotrophic Virus Type 1.

Coinfection with human T-cell lymphotrophic virus type 1 (HTLV-1) is associated with shorter survival for adults and children infected with human immunodeficiency virus (HIV), although the reasons remain a matter of debate. We evaluated the factors associated with survival time in a large cohort of HIV/HTLV-1-coinfected and HIV-monoinfected individuals on combination antiretroviral therapy (cART). In a nested, retrospective case-control study (1:1), we reviewed medical records of people with HIV infection on cART in a referral AIDS center in Salvador, Brazil. We matched 149 patients coinfected with HTLV-1 (cases) by age at HIV diagnosis and sex, to an equal number of HTLV-uninfected persons (controls). Death rates, survival time, baseline and current CD4 cell count, last HIV-1 RNA plasma viral load (pVL), and causes of death were compared between groups. The overall mortality rate was 2.1 person-years (76 deaths, 53 among coinfected patients). Survival time for cases (16.7 ± 0.7 years) was significantly shorter than for controls (18.1 ± 0.4 years; P = .001). Among patients with pVL >50 copies/mL, coinfected patients had a shorter survival time (8.4 ± 0.8 years) than monoinfected ones (12.9 ± 1.4 years; P = .02), regardless of pVL magnitude. However, survival time did not differ for HIV-monoinfected (19.0 ± 0.4 years) or coinfected patients (20.2 ± 0.6 years) presenting with pVL <50 copies/mL (P = .5). Deceased coinfected patients had higher initial CD4 count (417 ± 219 cells) than monoinfected ones with the same outcome (177 ± 160 cells; P = .004), while survivors had similar CD4 cell count at baseline, regardless of HTLV status. Successful cART is able to normalize survival for coinfected patients and should be introduced for all coinfected patients, regardless of CD4 cell count.HIV/human T-cell lymphotrophic virus type 1 coinfection is believed to decrease survival of coinfected patients. In this case-control study, we demonstrate that successful combination antiretroviral therapy (last HIV viral load<50 copies/mL) is able to improve survival of coinfected patients to levels observed for those monoinfected.

MYELOPATHY ASSOCIATED WITH HTLV-1 IN A PATIENT WITH CHRONIC RENAL INSUFFICIENCY. REPORT OF A CASE

A case of human T-cell lymphotrophic virus type I (HTLV-1)-associated myelopathy (HAM) occurring in a 60-year-old Peruvian female with a history of hemodialysis due to chronic renal failure (CRF) is reported. The patient was a lifelong resident of Lima, Peru, an endemic area for HTLV-1 infections1,2,3. The clinical course was characterized by abrupt onset and rapid progression of neurological signs and symptoms: paraparesia end neurogenic bladder. There are reports in Latin America with similar prevalence with B and C hepatitis on hemodialysis group4,5,6. There are no reports in Peru, also no screening in kidney transplantation (receptor and donors). Key words: Myelopathy; HTLV-1; Chronic renal failure. (source: MeSH NLM) &nbsp; DOI: 10.25176/RFMH.v18.n2.1292 &nbsp

FoxP3-positive T cell lymphoma arising in non-HTLV1 carrier: clinicopathological analysis of 11 cases of PTCL-NOS and 2 cases of mycosis fungoides.

Forkhead box protein 3-positive (FoxP3(+) ) T cell lymphoma, in the absence of human T cell lymphotrophic virus type 1 (HTLV-1) infection, is rare and its clinicopathological characteristics still remain unclear. The aim of this study was to elucidate its characteristics. We describe here 11 cases of peripheral T cell lymphoma not otherwise specified (PTCL-NOS) and two cases of mycosis fingoides (MF) which were positive for FoxP3. The median age of the 11 PTCL-NOS cases was 65 years (range: 48-80 years), and all the patients were male. Eight patients (80%) showed stages III/IV disease, and six (60%) were categorized as high-intermediate/high-risk groups according to the International Prognostic Index. Two cases of MF were 57- and 59-year-old males. Both cases were categorized as stage IA, according to International Society for Cutaneous Lymphomas/European Organization of Research and Treatment of Cancer (ISCL/EORTC) classification. Immunohistochemically, all the cases were negative for cytotoxic molecule marker, and nine (75%) were αβ T cell type. Scattered Epstein-Barr virus (EBV)-infected cells were detected in four cases of PTCL-NOS, implying the reactivation of EBV caused by the immunodeficient status of the patients. FoxP3(+) PTCL-NOS constitute a minor phenotypical subtype with poor prognosis and EBV reactivation in some. Conversely, two cases of MF showed an indolent clinical course which was different from previously reported cutaneous T cell lymphoma (CTCL) cases.

Viral Co-infection and Leprosy Outcomes: A Cohort Study.

BackgroundThe role of the host immunity in determining leprosy clinical forms and complications is well recognized, implying that changes in the immune status may interfere with several aspects of the disease. Therefore, we hypothesized that the presence of viral co-infections and associated immunological changes will have a clinical impact on leprosy outcomes. The aim of our study was to determine the clinical impact of human immunodeficiency virus (HIV), human T cell lymphotrophic virus type 1 (HTLV-1), hepatitis B virus (HBV) and hepatitis C virus (HCV) co-infection on the development of reactions, neuritis, neuropathy and relapses.Methodology/Principal FindingsCohort study in 245 leprosy subjects from Bahia, Brazil. Patients were followed from the time of diagnosis until at least the end of multidrug therapy. Viral co-infection was detected in 36 out of the 245 patients (14.7%). Specific co-infection rates were 10.6% for HBV, 2.9% for HIV, 2.5% for HTLV-1 and 0.8% for HCV. All four groups of co-infected patients had higher rates of neuritis and nerve function impairment compared to non co-infected leprosy subjects. The relapse rate was also higher in the co-infected group (8.3%) versus patients without co-infection (1.9%); relative risk 4.37, 95% confidence interval 1.02–18.74.Conclusions/SignificanceLeprosy patients should be screened for HBV, HCV, HIV and HTLV-1 co-infections. Besides contributing to better health care, this measure will facilitate the early detection of severe complications through targeting of higher risk patients.

Molecular Detection and Clinical Implications of HTLV-1 Infections among Antiretroviral Therapy-Naïve HIV-1-Infected Individuals in Abuja, Nigeria

BACKGROUNDIndividuals with human T-cell lymphotrophic virus type-1 (HTLV-1)/HIV-1 coinfection have been demonstrated to undergo CD4+ lymphocytosis even in the face of immunodeficiency and increased vulnerability to opportunistic pathogens that can lead to poor prognosis.OBJECTIVEThis study investigated the prevalence as well as the effects of HIV-1/HTLV-1 coinfection on CD4+ cell counts, routine hematology, and biochemical parameters of study participants.MATERIALS AND METHODSThis prospective cross-sectional study involved 184 blood samples collected from HIV-1-seropositive individuals attending HIV-special clinic of the University of Abuja Teaching Hospital, Gwagwalada, Nigeria. These samples were analyzed for anti-HTLV-1/2 IgM antibodies using enzyme-linked immunosorbent assay, CD4+ cell counts, and some routine hematological and biochemical parameters. All samples were also tested for HTLV-1 provirus DNA using real-time polymerase chain reaction (PCR) assay.RESULTSOf the 184 subjects studied, 9 (4.9%) were anti-HTLV-1/2 IgM seropositive; however, upon real-time PCR testing, 12 (6.5%) had detectable HTLV-1 provirus DNA. The CD4+ cell count was significantly high in HTLV-1-positive (742 ± 40.2) subjects compared to their HTLV-1-negative (380 ± 28.5) counterpart (P-value = 0.025). However, there was no significant association between HTLV-1 positivity with other hematology and biochemical parameters studied (P > 0.05).CONCLUSIONAll subjects (100%) who were HTLV-1/HIV-1-coinfected had normal CD4+ counts. This gives contrasting finding on the true extent of immunodeficiency of subjects. So it is suggested to be very careful in using only CD4+ counts to monitor disease progression and as indicators for antiretroviral therapy (ART) in resource-limited settings. In such conditions, there may be a need to test for HTLV-1 alongside HIV viral loads in order to begin appropriate ART regimens that contain both pathogens.

Opportunistic Infections in Patients with HTLV-1 Infection.

As an acquired immunodeficiency, human immunodeficiency virus (HIV) infection is primarily responsible for opportunistic infections in infected patients. However, opportunistic infections also occur in individuals with human T cell lymphotrophic virus type 1 (HTLV-1) infection. Here, we report opportunistic infections in two Japanese HTLV-1-seropositive patients. The first patient was a 67-year-old male, who had cytomegalovirus infection associated with esophagogastritis and terminal ileitis. The patient was HTLV-1-positive and was diagnosed with smoldering adult T cell leukemia (ATL). High levels of serum soluble IL-2 receptor (sIL-2R; 4,304 U/mL) and an increased percentage of CD4+CD25+ T cells (75.5%) in peripheral blood were also detected. The second patient was a 78-year-old female, a known asymptomatic HTLV-1 carrier, who presented with persistent herpes zoster, followed by Pneumocystis jirovecii pneumonia. Disease progression of smoldering ATL along opportunistic infections was observed with very high levels of serum sIL-2R (14,058 U/mL) and an increased percentage of CD4+CD25+ T cells (87.2%) in peripheral blood. In patients with suspected opportunistic infections, both HTLV-1 and HIV should be considered. In HTLV-1-positive patients, an increase in the CD4+CD25+ T cell subset may have its value as a prognostic marker.

CADM1 Expression and Stepwise Downregulation of CD7 Are Closely Associated with Clonal Expansion of HTLV-I–Infected Cells in Adult T-cell Leukemia/Lymphoma

Cell adhesion molecule 1 (CADM1), initially identified as a tumor suppressor gene, has recently been reported to be ectopically expressed in primary adult T-cell leukemia-lymphoma (ATL) cells. We incorporated CADM1 into flow-cytometric analysis to reveal oncogenic mechanisms in human T-cell lymphotrophic virus type I (HTLV-I) infection by purifying cells from the intermediate stages of ATL development. We isolated CADM1- and CD7-expressing peripheral blood mononuclear cells of asymptomatic carriers and ATLs using multicolor flow cytometry. Fluorescence-activated cell sorted (FACS) subpopulations were subjected to clonal expansion and gene expression analysis. HTLV-I-infected cells were efficiently enriched in CADM1(+) subpopulations (D, CADM1(pos)CD7(dim) and N, CADM1(pos)CD7(neg)). Clonally expanding cells were detected exclusively in these subpopulations in asymptomatic carriers with high proviral load, suggesting that the appearance of D and N could be a surrogate marker of progression from asymptomatic carrier to early ATL. Further disease progression was accompanied by an increase in N with a reciprocal decrease in D, indicating clonal evolution from D to N. The gene expression profiles of D and N in asymptomatic carriers showed similarities to those of indolent ATLs, suggesting that these subpopulations represent premalignant cells. This is further supported by the molecular hallmarks of ATL, that is, drastic downregulation of miR-31 and upregulation of abnormal Helios transcripts. The CADM1 versus CD7 plot accurately reflects disease progression in HTLV-I infection, and CADM1(+) cells with downregulated CD7 in asymptomatic carriers have common properties with those in indolent ATLs.

Lack of Evidence for Human T-Lymphotropic Virus Type 1 and Mouse Mammary Tumor–Like Virus Involvement in the Genesis of Childhood Acute Lymphoblastic Leukemia

In Mexico City, the incidence of childhood acute lymphoblastic leukemia (ALL) is one of the highest in the world; epidemiologic evidence suggests that infectious agents could be involved in the genesis of this disease. Early transmitted oncogenic retroviruses infecting lymphocytes are important candidates. PCR-based assays were used to screen viral genomic sequences of human T-cell lymphotrophic virus, type 1 (HTLV1) and mouse mammary tumor virus (MMTV)-like virus (MMTV-LV) in leukemic cells from 67 pediatric patients with ALL. Viral genomic sequences were not detected in any sample by neither standard nor nested PCR. Because of the methodologic strictness and high statistical power of the study, these results suggest that HTLV1 and MMTV-LV are not involved in the genesis of childhood ALL in Mexican children. To our knowledge, this is the first work exploring the direct participation of HTLV1 and MMTV-LV retroviruses in childhood ALL development.

The role of human T cell lymphotrophic virus type 1, hepatitis B virus and hepatitis C virus coinfections in leprosy

Leprosy spectrum and outcome is associated with the host immune response against Mycobacterium leprae. The role of coinfections in leprosy patients may be related to a depression of cellular immunity or amplification of inflammatory responses. Leprosy remains endemic in several regions where human T cell lymphotrophic virus type 1 (HTLV-1), hepatitis B virus (HBV) or hepatitis C virus (HCV) are also endemic. We have evaluated the evidence for the possible role of these viruses in the clinical manifestations and outcomes of leprosy. HTLV-1, HBV and HCV are associated with leprosy in some regions and institutionalization is an important risk factor for these viral coinfections. Some studies show a higher prevalence of viral coinfection in lepromatous cases. Although HBV and HCV coinfection were associated with reversal reaction in one study, there is a lack of information about the consequences of viral coinfections in leprosy. It is not known whether clinical outcomes associated with leprosy, such as development of reactions or relapses could be attributed to a specific viral coinfection. Furthermore, whether the leprosy subtype may influence the progression of the viral coinfection is unknown. All of these important and intriguing questions await prospective studies to definitively establish the actual relationship between these entities.

Comparison of Two Htlv-I/Ii Small Platform Assays Potentially Suitable for Tissue Donor Screening in the United States

Background: Human T-cell lymphotrophic virus (HTLV) type I has been linked to adult T-cell leukemia/lymphoma (ATL) and HTLV-I associated myelopathy (HAM). Transmission of HTLV by blood and organ transplantation has been documented, with some infections leading to clinical disease. Since December 31, 2009 organ donors in the US are no longer tested for anti-HTLV antibodies. This decision was prompted, at least in part, by discontinuation of Abbott HTLV-I/II EIA and absence of a suitable FDA-approved replacement. However, tissue donors are still being tested for HTLV-I/II using a combination of validated research assays or large platform test (PRIZM). Confirmatory testing is not routinely performed, and the number of false positive organ donors is unknown. Aim: To share our experience with 2 HTLV-I/II EIAs currently in FDA application process. Method: We evaluated multiple lots of Avioq HTLV-I/II (RUO) EIA (Avioq, Inc., Research Triangle Park, NC) and MP Diagnostics HTLV I/II 4.1 ELISA System (IUO) (MP Biomedicals, Irwine, CA). The Avioq EIA (RUO) utilizes antigens derived from purified and inactivated HTLV-I viral lysate, a purified HTLV-II viral lysate, and a recombinant HTLV-I p21E antigen. The MP Bio EIA (IUO) uses recombinant proteins gp46-I, gp46-II, GD21 and MGK. The recombinant envelope proteins are derived from the central region of the external glycoprotein of the respective HTLV-I and HTLV-II gp46. We tested at least 3 lots of each assay using a panel of well pedigreed specimens with known HTLV-I/II status including 11 specimens with false positive or indeterminate HTLV-I/II reactivity. We also tested “in real time” 1700 tissue donors' specimens by Avioq and 4811 tissue donors by MP Bio EIA. Results: Both assays passed and performed comparably with our evaluation panel. In contrast to the discontinued Abbott EIA that incorrectly identified 10/11 difficult specimens both Avioq and MPBio EIAs correctly called 10/11 false positive and indeterminate specimens (see Table below). However, during “real time” testing we observed that the Avioq assay consistently detected HTLV-I/II reactive donors 4 times (1.53% v. 0.37% respectively, p< 0.0001) more often as the MP Bio assay. When we tested randomly chosen subset of Avioq reactive specimens with HTLV Western Blot none of the specimens were confirmed.Table: [Assays Performance with Evaluation Panel]Conclusions: Both prospective HTLV-I/II assays performed better than the discontinued Abbott HTLV-I/II EIA and offer significantly improved performance for anti-HTLV-I/II antibodies screening. Only one company (MP Bio) offers HTLV-I/II EIA and HTLV-I/II WB with subtyping. Careful consideration of screening HTLV-I/II assay will prevent unnecessary donor loss.

Hearing loss, uveomeningitis, and stroke in a 55‐year‐old man

Hearing loss, uveomeningitis, and stroke in a 55‐year‐old man

A Case of Cytomegalovirus Colitis in Chronic Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a malignancy of mature T-cells caused by the human T-cell lymphotrophic virus type I (HTLV-D. HTLV-I is endemic in some areas in Japan, the Caribbean basin, and Africa but has low prevalence in South Korea. Patients with ATLL are susceptible to opportunistic infections such as cytomegalovirus (CMV) infection, but CMV infection in chronic ATLL is uncommon. Reported herein is a case involving a 44-year-old woman with chronic ATLL who presented the symptoms of fever and diarrhea. She was suspected to have acute-type ATLL but was later diagnosed with CMV colitis.

High HTLV-1 proviral load, a marker for HTLV-1 associated myelopathy/tropical spastic paraparesis, is also detected in patients with infective dermatitis associated with HTLV-1

Salvador (BA, Brazil) is an endemic area for human T-cell lymphotrophic virus type 1 (HTLV-1). The overall prevalence of HTLV-1 infection in the general population has been estimated to be 1.76%. HTLV-1 carriers may develop a variety of diseases such as adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and infective dermatitis associated with HTLV-1 (IDH). IDH is a chronic and severe form of childhood exudative and infective dermatitis involving mainly the scalp, neck and ears. It has recently been observed that 30% of patients with IDH develop juvenile HAM/TSP. The replication of HTLV-1 has been reported to be greater in adult HAM/TSP patients than in asymptomatic HTLV-1 carriers. In the current study, the proviral load of 28 children and adolescents with IDH not associated with HAM/TSP was determined and the results were compared to those obtained in 28 HTLV-1 adult carriers and 28 adult patients with HAM/TSP. The proviral load in IDH patients was similar to that of patients with HAM/TSP and much higher than that found in HTLV-1 carriers. The high levels of proviral load in IDH patients were not associated with age, duration of illness, duration of breast-feeding, or activity status of the skin disease. Since proviral load is associated with neurological disability, these data support the view that IDH patients are at high risk of developing HAM/TSP.

Abnormal spinal MRI findings in human T-cell lymphotrophic virus type I-associated myelopathy

We describe three cases of HTLV-I-associated myelopathy (HAM) with abnormal spinal magnetic resonance imaging (MRI) findings. The serum and cerebrospinal fluid (CSF) of all 3 patients tested positive for anti-HTLV-I antibody. Swelling of the spinal cord with high-intensity lesions on T2-weighted images was observed. Corticosteroid treatment in the case of two patients gradually improved the symptoms, decreased the protein and IgG levels as well as the cell count, and reduced the abnormal MRI findings. To confirm the assumption that abnormal spinal MRI findings are reflective of active inflammation, we compared the clinical parameters, namely, the protein content, IgG level, and cell count, in the CSF of patients exhibiting abnormal spinal MRI findings with those in the case of patients without spinal MRI lesions. The protein contents, IgG levels, and number of cells in the CSF of patients with MRI lesions were significantly higher than those in the CSF of patients without lesions. These findings support the fact that abnormal MRI findings in the spinal cord may be reflective of active inflammation in the early stages of rapidly progressive HAM.

C-terminal residues of mature human T-lymphotropic virus type 1 protease are critical for dimerization and catalytic activity.

HTLV-1 [HTLV (human T-cell lymphotrophic virus) type 1] is associated with a number of human diseases. HTLV-1 protease is essential for virus replication, and similarly to HIV-1 protease, it is a potential target for chemotherapy. The primary sequence of HTLV-1 protease is substantially longer compared with that of HIV-1 protease, and the role of the ten C-terminal residues is controversial. We have expressed C-terminally-truncated forms of HTLV-1 protease with and without N-terminal His tags. Removal of five of the C-terminal residues caused a 4-40-fold decrease in specificity constants, whereas the removal of an additional five C-terminal residues rendered the protease completely inactive. The addition of the N-terminal His tag dramatically decreased the activity of HTLV-1 protease forms. Pull-down experiments carried out with His-tagged forms, gel-filtration experiments and dimerization assays provided the first unequivocal experimental results for the role of the C-terminal residues in dimerization of the enzyme. There is a hydrophobic tunnel on the surface of HTLV-1 protease close to the C-terminal ends that is absent in the HIV-1 protease. This hydrophobic tunnel can accommodate the extra C-terminal residues of HTLV-1 protease, which was predicted to stabilize the dimer of the full-length enzyme and provides an alternative target site for protease inhibition.

A Promising Therapeutic Implication of a Novel Bcl-2 Family Inhibitor ABT-737 for Adult T-Cell Leukemia/Lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell malignancy caused by human T-cell lymphotrophic virus type I. Conventional chemotherapeutic regimens used against other malignant lymphoma have been administered to ATLL patients, but the treatment outcome of acute and lymphoma type ATLL remains very poor. Therefore, new therapeutic strategies are needed to improve patient outcome. Anti-apoptotic proteins, Bcl-2 and Bcl-XL have been reported to be highly expressed in ATLL cells, and confer resistance to chemotherapy. The aim of this study is to elucidate the therapeutic implication of ABT-737 (Abbott Laboratories, Abbott Park, IL, USA), a potent small-molecule inhibitor of Bcl-2, Bcl-XL and Bcl-w for ATLL. We first examined the direct toxicity of ABT-737 against tumor cell lines in vitro. ABT-737 significantly inhibited growth of ATLL cell lines (MT-1, MT-2 and HuT102) and an acute T-cell leukemia cell line, Jurkat with IC50 values at 72h of 2.5μM, 0.4μM, 0.01μM and 0.75μM, respectively. In contrast, Burkitt lymphoma cell lines, Raji and Ramos were resistant to ABT-737 with IC50 values at 72h of 24μM and 7.0μM, respectively. Importantly, Bcl-2 protein was highly expressed in MT-1, MT-2, HuT102 and Jurkat cells, but not in Raji and Ramos cells. We next examined the mechanism of ABT-737 induced growth inhibition using MT-1 and MT-2 cells. ABT-737 induced apoptosis with cleavage of caspase 9 and caspase 3 without modulating cell cycle distribution. Furthermore, ABT-737 significantly induced apoptosis in fresh tumor cells obtained from ATLL patients. We finally elucidated the potential of ABT-737 to enhance the apoptosis induced by anti-Fas monoclonal antibody (mAb), and cytotoxicity induced by conventional chemotherapeutics. ABT-737 enhanced apoptosis induced by anti-Fas mAb in MT-1 and MT-2 cells. Most importantly, ABT-737 synergistically enhanced the cytotoxicity induced by either of doxorubicin, vincristine or etoposide. These results suggest that ABT-737, used either alone or in combination with other conventional cytotoxic drugs, represents a promising novel targeted approach to overcome drug resistance and improve patient outcome in ATLL.

Adult T-cell leukemia/lymphoma: report of two cases

Adult T-cell leukemia/lymphoma is a lymphoproliferative disorder of mature T lymphocytes associated with infection with human T-cell lymphotrophic virus type I (HTLV-I). Adult T-cell leukemia/lymphoma is characterized by clinical and laboratory polymorphism that allows it to be classified into four distinct subgroups: smoldering, chronic, acute and lymphomatous types. We present here two cases of adult T-cell leukemia/lymphoma, respectively in the acute and lymphomatous forms of the disease. Case 1 was a 35-year-old woman who presented abdominal distension accompanied by hepatosplenomegaly, adenomegaly, skin lesions, positivity for anti-HTLV-I antibodies and leukocytosis with the presence of flower cells. Case 2 was a 38-year-old man who was admitted with generalized lymphadenomegaly, positivity for anti-HTLV-I antibodies, hypercalcemia and osteolytic lesions. In this paper, we correlate the clinical-laboratory findings of these two cases with data in the literature.