Involvement of IL-2/IL-2R system activation by parasite antigen in polyclonal expansion of CD4(+)25(+) HTLV-1-infected T-cells in human carriers of both HTLV-1 and S. stercoralis

The Parasitism and Tumors Carcinogenesis: A Review Subject

BACKGROUND

Multi-factorial reasons are an induction to cause cancer. Different infections and infestations with viruses, bacteria, and parasites have been detected for many years to be related to human carcinogenesis.

PURPOSE

The study aimed to review all ideas of tumor carcinogenesis and its associations with parasitic infections and infestations.

METHODS

We reviewed several articles (published and imprinted) by selecting, extracting, and synthesizing data about the relationship between cancers and parasites.

RESULTS

Several helminths infections as schistosomiasis, are highly carcinogenic agents for bladder cancer, whereas trypanosomiasis has a bi-model role in cancer development. Leishmaniasis may be a cause of hepatocarcinoma, skin cancer, and lymphomas. In addition, malaria appears to be causative in the carcinogenesis of some cancers; as Burkitt lymphoma. Also, data from previous studies suggested that Strongyloides stercoralis may be a relevant co-factor in lymphomas.

CONCLUSION

There are different mechanisms of parasitic infection to be enhancing in carcinogenesis of cancer in human.

Understanding the Immunopathology of HTLV-1-Associated Adult T-Cell Leukemia/Lymphoma: A Comprehensive Review

Human T-cell leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia/lymphoma (ATL). HTLV-1 carriers have a lifelong asymptomatic balance between infected cells and host antiviral immunity; however, 5-10% of carriers lose this balance and develop ATL. Coinfection with Strongyloides promotes ATL development, suggesting that the immunological status of infected individuals is a determinant of HTLV-1 pathogenicity. As CD4+ T cells play a central role in host immunity, the deregulation of their function and differentiation via HTLV-1 promotes the immune evasion of infected T cells. During ATL development, the accumulation of genetic and epigenetic alterations in key host immunity-related genes further disturbs the immunological balance. Various approaches are available for treating these abnormalities; however, hematopoietic stem cell transplantation is currently the only treatment with the potential to cure ATL. The patient's immune state may contribute to the treatment outcome. Additionally, the activity of the anti-CC chemokine receptor 4 antibody, mogamulizumab, depends on immune function, including antibody-dependent cytotoxicity. In this comprehensive review, we summarize the immunopathogenesis of HTLV-1 infection in ATL and discuss the clinical findings that should be considered when developing treatment strategies for ATL.

The Association between Diabetes and Human T-Cell Leukaemia Virus Type-1 (HTLV-1) with Strongyloides stercoralis: Results of a Community-Based, Cross-Sectional Survey in Central Australia

In central Australia, an area that is endemic for the human T-cell leukaemia virus type-1 (HTLV-1), the prevalence of Strongyloides stercoralis and its association with other health conditions are unknown. A cross-sectional community-based survey was conducted in seven remote Aboriginal communities in central Australia, from 2014 to 2018. All residents aged ≥10 years were invited to complete a health survey and to provide blood for Strongyloides serology, HTLV-1 serology and HTLV-1 proviral load (PVL). Risk factors for Strongyloides seropositivity and associations with specific health conditions including diabetes and HTLV-1 were determined using logistic regression. Overall Strongyloides seroprevalence was 27% (156/576) (children, 22% (9/40); adults (≥15 years), 27% (147/536), varied widely between communities (5–42%) and was not associated with an increased risk of gastrointestinal, respiratory or dermatological symptoms. Increasing age, lower HTLV-1 PVL (<1000 copies per 105 peripheral blood leucocytes) compared to the HTLV-1 uninfected group and community of residence were significant risk factors for Strongyloides seropositivity in an adjusted model. A modest reduction in the odds of diabetes among Strongyloides seropositive participants was found (aOR 0.58, 95% CI 0.35, 1.00; p = 0.049); however, this was lost when body mass index was included in the adjusted model (aOR 0.48, 95% CI 0.48, 1.47; p = 0.542). Strongyloides seropositivity had no relationship with anaemia. Exploring social and environmental practices in communities with low Strongyloides seroprevalence may provide useful lessons for similar settings.

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

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

Seropositivity and geographical distribution of Strongyloides stercoralis in Australia: A study of pathology laboratory data from 2012-2016

Background

There are no national prevalence studies of Strongyloides stercoralis infection in Australia, although it is known to be endemic in northern Australia and is reported in high risk groups such as immigrants and returned travellers. We aimed to determine the seropositivity (number positive per 100,000 of population and percent positive of those tested) and geographical distribution of S. stercoralis by using data from pathology laboratories.

Methodology

We contacted all seven Australian laboratories that undertake Strongyloides serological (ELISA antibody) testing to request de-identified data from 2012–2016 inclusive. Six responded. One provided positive data only. The number of people positive, number negative and number tested per 100,000 of population (Australian Bureau of Statistics data) were calculated including for each state/territory, each Australian Bureau of Statistics Statistical Area Level 3 (region), and each suburb/town/community/locality. The data was summarized and expressed as maps of Australia and Greater Capital Cities.

Principal findings

We obtained data for 81,777 people who underwent serological testing for Strongyloides infection, 631 of whom were from a laboratory that provided positive data only. Overall, 32 (95% CI: 31, 33) people per 100,000 of population were seropositive, ranging between 23/100,000 (95% CI: 19, 29) (Tasmania) and 489/100,000 population (95%CI: 462, 517) (Northern Territory). Positive cases were detected across all states and territories, with the highest (260-996/100,000 and 17–40% of those tested) in regions across northern Australia, north-east New South Wales and north-west South Australia. Some regions in Greater Capital Cities also had a high seropositivity (112-188/100,000 and 17–20% of those tested). Relatively more males than females tested positive. Relatively more adults than children tested positive. Children were under-represented in the data.

Conclusions/Significance

The study confirms that substantial numbers of S. stercoralis infections occur in Australia and provides data to inform public health planning.

Strongyloides stercoralis, a parasitic roundworm, is endemic in many countries world-wide. In Australia, groups at risk for strongyloidiasis include Aboriginal and/or Torres Strait Islander people, who acquired this parasite locally, and immigrants and returned travellers who acquired the infection outside Australia. We obtained deidentified results of ELISA IgG antibody tests for Strongyloides from diagnostic pathology laboratories during 2012 to 2016 and calculated the number of people who were positive at least once and the number who never had a positive result. We drew maps showing the number positive per 100,000 of population, the percent positive of those tested, and the number tested/100,000 for each region and the number positive in each suburb of residence according to the Australian Bureau of Statistics. The highest seropositivity (260-996/100,000 of population) was in Northern Australia, north-west South Australia and north-east New South Wales where many Aboriginal and Torres Strait Islander people live in remote communities. There were also some regions in Greater Capital Cities with a high number of people positive per 100,000 of population (112-188/100,000), likely reflecting higher populations of immigrants and returned travellers who were infected outside Australia.

Human T-cell Leukemia Virus Type 1 and Strongyloides stercoralis: Partners in Pathogenesis

Infection with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) has been associated with various clinical syndromes including co-infection with Strongyloides stercoralis, which is an intestinal parasitic nematode and the leading cause of strongyloidiasis in humans. Interestingly, HTLV-1 endemic areas coincide with regions citing high prevalence of S. stercoralis infection, making these communities optimal for elucidating the pathogenesis of co-infection and its clinical significance. HTLV-1 co-infection with S. stercoralis has been observed for decades in a number of published patient cases and case series; however, the implications of this co-infection remain elusive. Thus far, data suggest that S. stercoralis increases proviral load in patients co-infected with HTLV-1 compared to HTLV-1 infection alone. Furthermore, co-infection with HTLV-1 has been associated with shifting the immune response from Th2 to Th1, affecting the ability of the immune system to address the helminth infection. Thus, despite this well-known association, further research is required to fully elucidate the impact of each pathogen on disease manifestations in co-infected patients. This review provides an analytical view of studies that have evaluated the variation within HTLV-1 patients in susceptibility to S. stercoralis infection, as well as the effects of strongyloidiasis on HTLV-1 pathogenesis. Further, it provides a compilation of available clinical reports on the epidemiology and pathology of HTLV-1 with parasitic co-infection as well as data from mechanistic studies suggesting possible immunopathogenic mechanisms. Furthermore, specific areas of potential future research have been highlighted to facilitate advancing understanding of the complex interactions between these two pathogens.

Colorectal Cancer Related to Chronic Strongyloides stercoralis Infection

The majority of individuals with Strongyloides stercoralis (S. stercoralis) colitis are clinically asymptomatic. Symptomatic individuals may complain of nonspecific gastrointestinal symptoms, such as abdominal pain, intermittent or persistent diarrhea, nausea, or loss of appetite. In addition, skin manifestations such as recurrent urticaria can occur. If infection is not diagnosed and left untreated, it can lead to chronic inflammation of the gastrointestinal tract. It is well documented that chronic colitis such as inflammatory bowel disease can predispose individuals to colorectal cancer. Additionally, there is evidence of chronic parasitic infections inducing the development of cancers in other organs within the gastrointestinal tract. In this case vignette, we describe a case of chronic Strongyloides stercoralis infection in a Peruvian woman presenting with colorectal cancer.

Regulatory T cell expansion resolves after effective strongyloidiasis treatment in subjects with HTLV-1 co-infection

BACKGROUND

Regulatory T-cells (Tregs) are increased in patients with HTLV-1/Strongyloides stercoralis co-infection, and they may modify otherwise protective antigen-specific cytokine production. We hypothesized that effective anti-helminthic treatment would decrease Tregs and restore antigen-specific cytokine responses.

METHODS/RESULTS

We enrolled 19 patients with Strongyloides larvae in their stool by Baerman's test. Six were positive and 13 negative for antibody to HTLV-1 by ELISA, with positive tests confirmed by immunoblot. Before treatment, co-infected subjects had higher Tregs percentages and lower antigen-stimulated IL-5 levels compared to subjects with Strongyloides without HTLV-1. All patients were treated with ivermectin. After effective treatment, Tregs percentages decreased in patients with HTLV-1; however, antigen-specific IL-5 production remained blunted in co-infected subjects.

CONCLUSION

These results suggest that treating strongyloidiasis infection decreases circulating Tregs, but antigen-specific cytokine remains altered. This may reflect blunting of sensitization by Tregs.

Epidemiology of HTLV-1 Infection and ATL in Japan: An Update

Adult T-cell leukemia-lymphoma (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1) infection that often occurs in HTLV-1-endemic areas, such as Japan, the Caribbean islands, Central and South America, Intertropical Africa, and the Middle East. In Japan, the nationwide estimation of the number of HTLV-1 carriers was at least 1.08 million in 2006–2007. Furthermore, in 2016, the nationwide annual incidence of newly infected with HTLV-1 was first estimated to be 3.8 per 100,000 person-years based on the age-specific seroconversion rates of blood donors in almost all areas of Japan. The incidence rate was three times higher in women than in men, and it was estimated that at least 4,000 new HTLV-1 infections occur yearly among adolescents and adults in Japan. As well known that HTLV-1 infection alone is not a sufficient condition for ATL to develop. To date, a variety of molecular abnormalities and host susceptibilities have been reported as candidate progression factors for the development of ATL in HTLV-1-carriers. In particular, quite recently in Japan, a variety of immunosuppressive conditions have been recognized as the most important host susceptibilities associated with the development of ATL from HTLV-1-carrier status. Furthermore, in 2013–2016 in Japan, a new nationwide epidemiological study of ATL was conducted targeting patients newly diagnosed with ATL in 2010–2011, from which the most current knowledge about the epidemiological characteristics of Japanese patients with ATL was updated as follows: (1) continuing regional unevenness of the distribution of people with HTLV-1, (2) further aging, with the mean age at diagnosis being 67.5 years, (3) declining M/F ratio, (4) increase of the lymphoma subtype, (5) sex differences in subtype distribution, (6) age differences in subtype distribution, and (7) comorbidity condition. In particular, 32.2% of ATL patients had comorbid malignancies other than ATL. However, the number of deaths due to ATL in Japan has been relatively stable, at around 1,000 patients annually, without significant decline from 1999 to 2017. Because the current epidemiological evidence about HTLV-1 and ATL is insufficient, further epidemiological studies are required.

Prevalence and Molecular Epidemiology of Human T-Lymphotropic Virus Type 1 among Women Attending Antenatal Clinics in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Human T-cell lymphotropic virus type 1 (HTLV-1) imposes a substantial disease burden in sub-Saharan Africa (SSA), which is arguably the world's largest endemic area for HTLV-1. Evidence that mother-to-child transmission persists as a major mode of transmission in SSA prompted us to estimate the pooled prevalence of HTLV-1 among pregnant women throughout the region. We systematically reviewed databases including EMBASE, MEDLINE, Web of Science, and the Cochrane Database of Systemic Reviews from their inception to November 2018. We selected studies with data on HTLV-1 prevalence among pregnant women in SSA. A random effect meta-analysis was conducted on all eligible data and heterogeneity was assessed through subgroup analyses. A total of 18 studies, covering 14,079 pregnant women, were selected. The evidence base was high to moderate in quality. The pooled prevalence, per 100 women, of the 18 studies that screened HTLV-1 was 1.67 (95% CI: 1.00-2.50), a figure that masks regional variations. In Western, Central, Southern, and Eastern Africa, the numbers were 2.34 (1.68-3.09), 2.00 (0.75-3.79), 0.30 (0.10-0.57), and 0.00 (0.00-0.21), respectively. The prevalence of HTLV-1 infection among pregnant women in SSA, especially in Western and Central Africa, strengthens the case for action to implement routine screening of pregnant women for HTLV-1. Rigorous studies using confirmatory testing and molecular analysis would characterize more accurately the prevalence of this infection, consolidate the evidence base, and further guide beneficial interventions.

Epidemiology, clinical features, and outcome of HTLV-1-related ATLL in an area of prevalence in the United States

Adult T-cell leukemia/lymphoma (ATLL) is a fatal disease caused by human T-cell leukemia virus type 1 (HTLV-1). We retrospectively analyzed 195 patients with ATLL (lymphomatous n = 96, acute n = 80, unfavorable chronic n = 7, chronic n = 5, smoldering n = 3, and unclassified n = 4) diagnosed between 1987 and 2016 (median age 52 years, 77% Afro-Caribbean). Hypercalcemia was associated with acute ATLL (65%, vs 23% lymphomatous) (P = .012). The median survival for patients treated with modern therapies between 2000 and 2016 was 4.1 months for acute, 10.2 months for lymphomatous, 72 months for chronic/smoldering, and not reached for unfavorable chronic type, with 4-year survival rates of 10%, 4%, 60%, and 83%, respectively. The overall response rate (ORR) after first-line multiagent chemotherapy was 78% (complete response [CR] 39%) for acute vs 67% (CR 33%) for lymphomatous ATLL. First-line zidovudine interferon-α (AZT-IFN) resulted in ORR of 56% (CR 23%) for acute (n = 43), 33% (CR 16.5%) for lymphomatous (n = 6), and 86% (CR 29%) for unfavorable chronic ATLL. The median progression-free survival (PFS) in patients with aggressive ATLL who achieved CR after AZT-IFN was 48 months vs 11 months after chemotherapy (P = .003). Allogeneic hematopoietic stem cell transplant (allo-HSCT) resulted in a PFS of 24 and 28 months in 2 patients with lymphomatous ATLL. Our results suggest high-dose AZT-IFN is a reasonable up-front option for patients with aggressive leukemic ATLL followed by chemotherapy switch in nonresponders, whereas chemotherapy should be used in lymphomatous type followed by allo-HSCT when feasible.

Evaluation of two prognostic indices for adult T-cell leukemia/lymphoma in the subtropical endemic area, Okinawa, Japan

Aggressive adult T-cell leukemia/lymphoma (ATL) has an extremely poor prognosis and is hyperendemic in Okinawa, Japan. This study evaluated two prognostic indices (PIs) for aggressive ATL, the ATL-PI and Japan Clinical Oncology Group (JCOG)-PI, in a cohort from Okinawa. The PIs were originally developed using two different Japanese cohorts that included few patients from Okinawa. The endpoint was overall survival (OS). Multivariable Cox regression analyses in the cohort of 433 patients revealed that all seven factors for calculating each PI were statistically significant prognostic predictors. Three-year OS rates for ATL-PI were 35.9% (low-risk, n = 66), 10.4% (intermediate-risk, n = 256), and 1.6% (high-risk, n = 111), and those for JCOG-PI were 22.4% (moderate-risk, n = 176) and 5.3% (high-risk, n = 257). The JCOG-PI moderate-risk group included both the ATL-PI low- and intermediate-risk groups. ATL-PI more clearly identified the low-risk patient subgroup than JCOG-PI. To evaluate the external validity of the two PIs, we also assessed prognostic discriminability among 159 patients who loosely met the eligibility criteria of a previous clinical trial. Three-year OS rates for ATL-PI were 34.5% (low-risk, n = 42), 9.2% (intermediate-risk, n = 109), and 12.5% (high-risk, n = 8). Those for JCOG-PI were 22.4% (moderate-risk, n = 95) and 7.6% (high-risk, n = 64). The low-risk ATL-PI group had a better prognosis than the JCOG-PI moderate-risk group, suggesting that ATL-PI would be more useful than JCOG-PI for establishing and examining novel treatment strategies for ATL patients with a better prognosis. In addition, strongyloidiasis, previously suggested to be associated with ATL-related deaths in Okinawa, was not a prognostic factor in this study.

Seroprevalence of Strongyloides stercoralis infection among HTLV-I infected blood donors in Barcelona, Spain: A cross-sectional study

Strongyloides stercoralis infection in patients with HTLV-I infection may lead to severe clinical manifestations. The aim of the present study is to determine the seroprevalence of S. stercoralis infection among blood donors who tested positive for HTLV-I infection. A cross-sectional study was performed at the Vall d'Hebron University Hospital (Barcelona, Spain) in 2016. Serum samples from HTLV-I positive patients diagnosed from 2008 to 2015 were retrieved from the Blood Bank, and S. stercoralis serology was performed. Thirty six serum samples from HTLV-I positive patients were retrieved from the Blood Bank. The blood samples came from 36 blood donors, and most of them were born in Latin America (75%), being Peru the most frequent country (11 participants). S. stercoralis serology was positive in one patient, corresponding to a prevalence of 2.8% (3.4% if we exclude donors coming from European countries, where the risk of S. stercoralis infection is highly unlikely).

Parasite Infection, Carcinogenesis and Human Malignancy

Cancer may be induced by many environmental and physiological conditions. Infections with viruses, bacteria and parasites have been recognized for years to be associated with human carcinogenicity. Here we review current concepts of carcinogenicity and its associations with parasitic infections. The helminth diseases schistosomiasis, opisthorchiasis, and clonorchiasis are highly carcinogenic while the protozoan Trypanosoma cruzi, the causing agent of Chagas disease, has a dual role in the development of cancer, including both carcinogenic and anticancer properties. Although malaria per se does not appear to be causative in carcinogenesis, it is strongly associated with the occurrence of endemic Burkitt lymphoma in areas holoendemic for malaria. The initiation of Plasmodium falciparum related endemic Burkitt lymphoma requires additional transforming events induced by the Epstein-Barr virus. Observations suggest that Strongyloides stercoralis may be a relevant co-factor in HTLV-1-related T cell lymphomas. This review provides an overview of the mechanisms of parasitic infection-induced carcinogenicity.

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The helminth diseases schistosomiasis, opisthorchiasis, and clonorchiasis are highly carcinogenic.

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Trypanosoma cruzi has a dual role in cancer development including both carcinogenic and anticancer properties.

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Initiation of Plasmodium falciparum related endemic Burkitt lymphoma requires additional transforming events induced by EBV.

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Strongyloides stercoralis may be a relevant co-factor in HTLV-1-related T cell lymphomas.

We searched MEDLINE database and PubMed for articles from 1970 through June 30, 2016. Search terms used in various combinations were “parasite infection”, “carcinogenesis”, “cancer”, “human malignancy”, “parasite and cancer”, “infection-associated cancer”, “parasite-associated cancer” “schistosomiasis”, “opisthorchiasis”, “malaria”, “Chagas disease”, and “strongyloidiasis”. Articles resulting from these searches and relevant references cited in those articles were selected based on their related topics and were reviewed. Abstracts and reports from meetings were also included. Articles published in English were included.

STAT1: A Novel Target of miR-150 and miR-223 Is Involved in the Proliferation of HTLV-I-Transformed and ATL Cells

We have previously reported on the deregulation of cellular microRNAs involved in hematopoiesis and inflammation in human T-cell lymphotropic virus type 1 (HTLV-I)–transformed cells. In this study, we demonstrate that miR-150 and miR-223 specifically target the signal transducer and activator of transcription 1 (STAT1) 3′ untranslated region, reducing STAT1 expression and dampening STAT1-dependent signaling in human T cells. The effects of miR-150 and miR-223 on endogenous STAT1 were confirmed using inducible cell lines. Our studies also showed that miR-150 expression is upregulated by interleukin-2 signaling in adult T cell leukemia/lymphoma (ATL) cells. HTLV-I–transformed and ATL-derived cells have reduced levels of miR150 and miR223 expression, which coincide with increased STAT1 expression and STAT1-dependent signaling. Knockdown of STAT1 by short hairpin RNA demonstrated that the constitutive activation of STAT1 is required for the continuous proliferation of HTLV-I–transformed cells. Our studies further demonstrate that increased expression of STAT1 in ATL cells is associated with higher levels of major histocompatibility complex class I expression. Previous studies have demonstrated that the pressure exerted by natural killer (NK) cells in vivo can edit leukemic tumor cells by forcing an increased expression of major histocompatibility complex class I to escape immune clearance. STAT1-expressing tumor cells produce more aggressive tumors because they cannot be eliminated by NK cells. Our results suggest that therapeutic approaches using combined targeting of STAT1 and MHC class I may be an effective approach to activate NK cell–mediated clearance of ATL tumor cells.

Neurological Manifestations in Human T-Cell Lymphotropic Virus Type 1 (HTLV-1)-Infected Individuals Without HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis: A Longitudinal Cohort Study

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is the agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), observed in up to 5% of infected individuals. Despite low prevalence, many HTLV-1-infected patients who do not fulfill criteria for HAM/TSP present with neurological complaints related to sensory, motor, urinary, or autonomic manifestations. The aim of this study was to determine the incidence of neurologic manifestations and risk factors associated with these outcomes.

METHODS

The incidence of HAM/TSP and new signs and neurologic symptoms were computed in a group of patients enrolled in a cohort study.

RESULTS

Of 414 subjects, 76 had definite HAM/TSP, 87 had possible or probable HAM/TSP, and 251 subjects had no neurologic manifestation and were selected for analysis. Definite HAM/TSP developed in 5 (1.47%) patients. Follow-up of at least 3 years was achieved in 51% of patients. The incidence rate was computed in 1000 person-years (206 for hand numbness, 187 for feet numbness, 130 for nocturia, and 127 for urgency). Average incidence rate in neurological exam was 76 for leg hyperreflexia, 53 for leg weakness, and 37 for Babinski sign. In the applied Expanded Disability Status Scale, the incidence rate of worsening 1 point was 134 per 1000 person-years. Kaplan-Meier curves stratified by sex and proviral load showed that females and patients with proviral load >50,000 copies/10(6) peripheral blood mononuclear cells had a higher risk of progression.

CONCLUSIONS

Development of neurological symptoms or signs occurred in up to 30% of asymptomatic subjects during 8 years of follow-up.

Strongyloides stercoralis: systematic review of barriers to controlling strongyloidiasis for Australian indigenous communities

Background

Strongyloides stercoralis infects human hosts mainly through skin contact with contaminated soil. The result is strongyloidiasis, a parasitic disease, with a unique cycle of auto-infection causing a variety of symptoms and signs, with possible fatality from hyper-infection. Australian Indigenous community members, often living in rural and remote settings, are exposed to and infected with S. stercoralis. The aim of this review is to determine barriers to control of strongyloidiasis. The purpose is to contribute to the development of initiatives for prevention, early detection and effective treatment of strongyloidiasis.

Methodology/Principle Findings

Systematic search reviewing research published 2012 and earlier was conducted. Research articles discussing aspects of strongyloidiasis, context of infection and overall health in Indigenous Australians were reviewed. Based on the PRISMA statement, the systematic search of health databases, Academic Search Premier, Informit, Medline, PubMed, AMED, CINAHL, Health Source Nursing and Academic was conducted. Key search terms included strongyloidiasis, Indigenous, Australia, health, and community. 340 articles were retrieved with 16 original research articles published between 1969 and 2006 meeting criteria. Review found barriers to control defined across three key themes, (1) health status, (2) socioeconomic status, and (3) health care literacy and procedures.

Conclusions/Significance

This study identifies five points of intervention: (1) develop reporting protocols between health care system and communities; (2) test all Indigenous Australian patients, immunocompromised patients and those exposed to areas with S. stercoralis; (3) health professionals require detailed information on strongyloidiasis and potential for exposure to Indigenous Australian people; (4) to establish testing and treatment initiatives within communities; and (5) to measure and report prevalence rates specific to communities and to act with initiatives based on these results. By defining barriers to control of strongyloidiasis in Australian Indigenous people, improved outcomes of prevention, treatment of strongyloidiasis and increased health overall are attainable.

Strongyloides stercoralis, a nematode parasite, has a well-documented history of infecting human hosts in tropic and subtropic regions mainly through skin contact with inhabited soil. The result is strongyloidiasis, a human parasitic disease, with a unique cycle of auto-infection contributing to a variety of symptoms, of which, hyper-infection causing fatality may occur. In Australia, Indigenous community members often located in rural and remote settings, are exposed to and infected with strongyloides. Previous researchers report strongyloidiasis as a recurrent health issue for Indigenous Australians. This is a systematic review to determine the barriers to control for this pernicious pathogen. Barriers to control can be defined across three key themes: (1) health status, (2) socioeconomic status, and (3) health care literacy and procedure. By conceptualizing these barriers and addressing steps to control as outlined in this study, there is potential for improvement in prevention and treatment outcomes of strongyloidiasis and subsequently, overall health for Australian Indigenous people. This study contributes to furthering prevention and treatment of strongyloidiasis, increasing exposure to the issue of strongyloidiasis in Australian Indigenous people. It is the intent of this paper to express the need to have continued research and further health policy directed specifically to eradicate strongyloidiasis in Australian Indigenous communities.

Development and validation of a new high-throughput method to investigate the clonality of HTLV-1-infected cells based on provirus integration sites

Transformation and clonal proliferation of T-cells infected with human T-cell leukemia virus type-I (HTLV-1) cause adult T-cell leukemia. We took advantage of next-generation sequencing technology to develop and internally validate a new methodology for isolating integration sites and estimating the number of cells in each HTLV-1-infected clone (clone size). Initial analysis was performed with DNA samples from infected individuals. We then used appropriate controls with known integration sites and clonality status to confirm the accuracy of our system, which indeed had the least errors among the currently available techniques. Results suggest potential clinical and biological applications of the new method.

Treatment of strongyloidiasis in HTLV-1 and Strongyloides stercoralis coinfected patients is associated with increased TNFα and decreased soluble IL2 receptor levels

BACKGROUND

Human T cell lymphotropic virus type 1 (HTLV-1) infection has been associated with recurrent and disseminated strongyloidiasis and adult T cell leukemia/lymphoma (ATLL).

METHODS

We compared immunological aspects and markers for ATLL in HTLV-1 patients with or without strongyloidiasis, and evaluated the influence of Strongyloides stercoralis treatment on the immune response and clinical outcomes of HTLV-1 infection.

RESULTS

Levels of TNFα and IFNγ were lower in patients coinfected with HTLV-1 and S. stercoralis than in patients with HTLV-1 only (p < 0.05), and there was an increase in TNFα levels after anthelmintic treatment. Levels of sIL-2R were higher in patients with HTLV-1 coinfected with S. stercoralis and anthelmintic treatment decreased sIL-2R levels (p < 0.05). The one patient who developed ATLL was coinfected with S. stercoralis.

CONCLUSION

These data show that helminthic infection has a modulatory role in HTLV-1 infection and that S. stercoralis may be a cofactor in the development of ATLL.

Strongyloidiasis and infective dermatitis alter human T lymphotropic virus-1 clonality in vivo

Human T-lymphotropic Virus-1 (HTLV-1) is a retrovirus that persists lifelong by driving clonal proliferation of infected T-cells. HTLV-1 causes a neuroinflammatory disease and adult T-cell leukemia/lymphoma. Strongyloidiasis, a gastrointestinal infection by the helminth Strongyloides stercoralis, and Infective Dermatitis associated with HTLV-1 (IDH), appear to be risk factors for the development of HTLV-1 related diseases. We used high-throughput sequencing to map and quantify the insertion sites of the provirus in order to monitor the clonality of the HTLV-1-infected T-cell population (i.e. the number of distinct clones and abundance of each clone). A newly developed biodiversity estimator called “DivE” was used to estimate the total number of clones in the blood. We found that the major determinant of proviral load in all subjects without leukemia/lymphoma was the total number of HTLV-1-infected clones. Nevertheless, the significantly higher proviral load in patients with strongyloidiasis or IDH was due to an increase in the mean clone abundance, not to an increase in the number of infected clones. These patients appear to be less capable of restricting clone abundance than those with HTLV-1 alone. In patients co-infected with Strongyloides there was an increased degree of oligoclonal expansion and a higher rate of turnover (i.e. appearance and disappearance) of HTLV-1-infected clones. In Strongyloides co-infected patients and those with IDH, proliferation of the most abundant HTLV-1⁺ T-cell clones is independent of the genomic environment of the provirus, in sharp contrast to patients with HTLV-1 infection alone. This implies that new selection forces are driving oligoclonal proliferation in Strongyloides co-infection and IDH. We conclude that strongyloidiasis and IDH increase the risk of development of HTLV-1-associated diseases by increasing the rate of infection of new clones and the abundance of existing HTLV-1⁺ clones.

HTLV-1 is a human retrovirus estimated to infect 20 million people world-wide and is causing in a small proportion of the infected individuals an inflammatory disease or a leukemia/lymphoma. HTLV-1 persists lifelong by driving clonal proliferation of infected T-cells. Strongyloidiasis, a gastrointestinal infection by an helminth (Strongyloides stercoralis) and Infective Dermatitis associated with HTLV-1 (IDH), a skin inflammation with bacterial infection, appear to increase the risk of developing HTLV-1-related diseases. It is well known that the chance of developing HTLV-1-related diseases increases with the number of cells infected by the virus (also called proviral load). It is also known that HTLV-1-infected individuals co-infected by Strongyloides or affected by IDH have a higher proviral load, but the mechanism is still unclear. Consequently, the aim of this study was to test if co-infection increases the total number and/or the abundance (or size) of HTLV-1-infected T-cell clones. We have shown that the significantly increased proviral load in HTLV-1-infected individuals with IDH or strongyloidiasis is due to an increase in the mean clone abundance (bigger clones), not to an increase in the number of infected clones. These patients appear to be less capable of restricting clone abundance than those with HTLV-1 alone.

Hyperinfection with Strongyloides stercoralis

Strongyloidiasis is caused by Strongyloides stercoralis, which commonly produces gastrointestinal problems. If immune systems are compromised, the nematode larvae may spread and produce Strongyloides hyperinfection. Diagnosis of strongyloidiasis is based on the observation of larvae in coproparasitological studies. We present a case of a 49-year-oldman, VIH, who developed Strongyloides hyperinfection, diagnosed postmortem. Our patient reached the dissemination stage, which resulted in severe damage to the stomach and intestine, perforation of the intestinal wall, as well as sepsis due to the dissemination of bacteria. The diagnosis is difficult because of the low larvae excretion in stools. It is usually performed by the microscopic examination of fresh and fixed enriched stool samples. Serology was reported to be useful for screening and follow-up after treatment. This case reaffirms that HIV immunosuppression favours the dissemination of S stercoralis larvae. Thus, a search for intestinal parasites should be considered in similar cases.

Adult T-cell leukemia: a review of epidemiological evidence

Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type I (HTLV-1) infection and often occurs in HTLV-1-endemic areas, such as southwestern Japan, the Caribbean islands, Central and South America, Intertropical Africa, and Middle East. To date, many epidemiological studies have been conducted to investigate the incidence of ATL among general population or HTLV-1 carriers and to identify a variety of laboratory, molecular, and host-specific markers to be possible predictive factors for developing ATL because HTLV-1 infection alone is not sufficient to develop ATL. This literature review focuses on the epidemiology of ATL and the risk factors for the development of ATL from HTLV-1 carriers, while keeping information on the epidemiology of HTLV-1 to a minimum. The main lines of epidemiological evidence are: (1) ATL occurs mostly in adults, at least 20-30 years after the HTLV-1 infection, (2) age at onset differs across geographic areas: the average age in the Central and South America (around 40 years old) is younger than that in Japan (around 60 years old), (3) ATL occurs in those infected in childhood, but seldom occurs in those infected in adulthood, (4) male carriers have about a three- to fivefold higher risk of developing ATL than female, (5) the estimated lifetime risk of developing ATL in HTLV-1 carriers is 6-7% for men and 2-3% for women in Japan, (6) a low anti-Tax reactivity, a high soluble interleukin-2 receptor level, a high anti-HTLV-1 titer, and high levels of circulating abnormal lymphocytes and white blood cell count are accepted risk factors for the development of ATL, and (7) a higher proviral load (more than 4 copies/100 peripheral blood mononuclear cells) is an independent risk factor for progression of ATL. Nevertheless, the current epidemiological evidence is insufficient to fully understand the oncogenesis of ATL. Further well-designed epidemiological studies are needed.

Adult T cell leukemia/lymphoma: FoxP3(+) cells and the cell-mediated immune response to HTLV-1

Human T-lymphotropic virus type 1 (HTLV-1) causes adult T-cell leukaemia/lymphoma (ATLL) in ∼5% of HTLV-1-infected people. ATLL cells frequently express several molecules that are characteristic of regulatory T cells (Tregs), notably CD4, CD25 and the transcription factor FoxP3. It has therefore recently been suggested that HTLV-1 selectively infects and transforms Tregs. We show that HTLV-1 induces and maintains a high frequency of FoxP3+ T cells by inducing expression of the chemokine CCL22; the frequency is especially high in patients with chronic ATLL. In turn, the FoxP3+ T cells exert both potentially beneficial and harmful effects: they suppress the growth of autologous ATLL clones and may also suppress the host's cytotoxic T lymphocyte response, which normally limits HTLV-1 replication and reduces the risk of HTLV-1-associated diseases. Although ATLL cells may exert immune suppressive effects, we conclude that ATLL is not necessarily a tumour of classical FoxP3+ Tregs.

[Combined infection with HTLV-1 and Strongyloides stercoralis]

Infection of carriers of strongyloides by the human oncogenic retrovirus HTLV-1 significantly augments the number of larval parasites in the stools and impairs the action of anti-helminthic agents, resulting in an increase in immediate and longer term failure of therapy. The proliferation of cytokine type 1 secreting lymphocytes, the preferred target for viral infection, shifts the Th1/Th2 balance in favour of a Th1 response with a consequent increase in the production of gamma interferon (INF-γ). In addition to other effects, this causes a decrease in the secretion of cytokines IL-4, IL-5 and IL-13, which results in substantial reduction in total and specific IgE; failure of activation of eosinophils or stagnation in or reduction of their numbers; and an increased risk of development of a severe form of strongyloidiasis. This risk is clearly correlated with the level of anti-HTLV-1 antibodies and the amplitude of the proviral load of peripheral lymphocytes. The polyclonal expansion of infected CD4 cells might be partly due to the activation of the IL-2/IL-2R system by parasite antigens together with the action of the virus type 1 Tax protein. The fact that adult T cell leukaemia arises significantly earlier and more often in individuals with combined infection is an argument in favour of the parasite's role as a leukaemogenic co-factor. In practice it is, therefore, appropriate to initiate all available measures to eliminate parasites from co-infected hosts although this does present difficulties, and one should not reject the possibility of a diagnosis of strongyloidiasis in the absence of hypereosinophilia. In all cases of chronic strongyloidiasis without hypereosinophilia, co-infection with HTLV-1 should be looked for routinely. The same applies to carriers of strongyloides with repeated treatment failures. Finally, corticosteroids and immunosuppressants should be used only with care in HTLV-1-positive patients who seem not to be co-infected, even if they have received precautionary therapy.

Detection of HTLV-1 by means of HBZ gene in situ hybridization in formalin-fixed and paraffin-embedded tissues

Adult T-cell leukemia/lymphoma (ATLL) is a T-cell malignancy associated with HTLV-1. The HTLV-1 provirus genome has the pX region that encodes tax and HTLV-1 basic leucine zipper factor (HBZ). Previous studies have reported that the tax gene is expressed in few ATLL cases, but the HBZ gene in all ATLL cases. In this study, we used HBZ gene in situ hybridization (HBZ-ISH) for detection of the HBZ gene in formalin-fixed paraffin-embedded tissues. This method showed that all cases (n = 19) were positive for the ATLL cell line (MT-1, MT-2, and MT-4) and ATLL mouse model (HBZ-Tg mice and NOD/SCID/β2-microglobulin(null) mice with ATLL transplanted), and the HBZ gene was also detected in all human ATLL cases (n = 16). The percentage of positive cells in HBZ-ISH was 5-70%. Immunohistochemical staining for Tax protein showed positivity in seven of 11 cases in NOD/SCID/β2-microglobulin(null) mice with ATLL transplanted and in six of eight human ATLL cases, but the percentage of positive cells was very low (range, 1-5%). Although HBZ-ISH is unsuitable to detect HTLV-1 clonality, this method is convenient and can be useful for the histological diagnosis of ATLL in HTLV-1 sero-indeterminate patients.

Newer developments in adult T-cell leukemia/lymphoma therapeutics

INTRODUCTION

Adult T-cell leukemia/lymphoma (ATL) is a rare disease with a unique geographic distribution. Conducting controlled randomized trials to assess the effective therapeutic strategies has therefore been a significant challenge to date.

AREAS COVERED

This review explores the natural history and diagnostic evaluation of ATL, followed by a focused review of existing studies on the most potent individual pharmaceutical agents and combinations used in the therapy of this malignancy. Readers will acquire considerable insights about the clinical subsets, diagnosis and the most effective therapies used in various ATL types.

EXPERT OPINION

International, multicenter, randomized clinical trials are essential to design optimal therapeutic strategies for various ATL subsets. It appears that patients with acute ATL type benefit considerably from the first-line combined antiviral therapy with zidovudine and interferon alpha, whereas patients with ATL of the lymphoma type may experience a better outcome with intensive chemotherapy. The role of therapy in smoldering and chronic disease types remains to be clarified. In addition, the results of allogeneic stem-cell transplantation in ATL appear promising, as up to 40% of patients who achieve remission and have suitable donors can now become long-term survivors. Prospective evaluation of novel effective agents and their incorporation into various therapeutic algorithms is stringently needed.

Disseminated Strongyloides stercoralis infection in HTLV-1-associated adult T-cell leukemia/lymphoma

A 55-year-old woman with human T-cell lymphotropic virus type-1 (HTLV-1)-associated adult T-cell leukemia (ATL) and a history of previously treated Strongyloides stercoralis infection received anti-CD52 monoclonal antibody therapy with alemtuzumab on a clinical trial. After an initial response, she developed ocular involvement by ATL. Alemtuzumab was stopped and high-dose corticosteroid therapy was started to palliate her ocular symptoms. Ten days later, the patient developed diarrhea, vomiting, fever, cough, skin rash, and a deteriorating mental status. She was diagnosed with disseminated S. stercoralis. Corticosteroids were discontinued and the patient received anthelmintic therapy with ivermectin and albendazole with complete clinical recovery.

Update on strongyloidiasis in the immunocompromised host

Immunocompromised persons are the most vulnerable population at risk for developing life-threatening clinical syndromes associated with strongyloidiasis, such as hyperinfection syndrome (HS) or dissemination. This review focuses on describing Strongyloides infection in the immunocompromised host, including immune response against this infection, analyzing the cases with HS published during the past 4 years in the United States, and describing the most sensitive diagnostic tools and the most effective treatment for each clinical syndrome. Strongyloidiasis is becoming an important parasitic disease in the United States, especially in the immunocompromised immigrant population. Because the transplant population is particularly at risk for developing HS, both recipients and donors should be screened for Strongyloides. Clinicians should also be aware that the development of HS can follow unexpectedly a few days after appropriate anthelminthic therapy. Highly sensitive screening tests are still not available in the major tertiary medical centers. Parenteral ivermectin has been used in some severe cases. Further therapy developments and improving diagnostic tools are warranted.

Route of primary HTLV-1 infection regulates HTLV-1 distribution in reservoir organs of infected mice

Human T-cell leukemia virus type-1 (HTLV-1) causes adult T-cell leukemia and HTLV-1-associated myelo-pathy/tropical spastic paraparesis. HTLV-1 is mainly transmitted through blood transfusion and breastfeeding, but viral proliferation in the body in vivo shortly after transmission is not well understood. To investigate whether the route of infection influences the early stages of viral proliferation, we inoculated BALB/c mice with MT-2 cells, an HTLV-1-producing human T-cell line, via different routes, and evaluated the proviral load and humoral immune responses. One month after infection, the provirus was detected in most organs of the mice infected intraperitoneally, and substantial proviral loads were detected in the peripheral blood and secondary lymphoid organs. In contrast, the mice infected intravenously and orally showed low proviral loads, and the provirus distribution was limited to the spinal cord among the intravenously inoculated mice and to the liver among the perorally inoculated mice. Mice infected intraperitoneally also exhibited higher interleukin-2 production than the mice infected intravenously or orally, or than the uninfected control mice, while anti-HTLV-1 antibody titers were comparable between the mice infected intraperitoneally and intravenously. These results demonstrate that the route of primary HTLV-1 infection influences the establishment of HTLV-1-infected cell proliferation and the cell reservoir in mice.

Human T-cell leukemia virus type I (HTLV-1) proviral load and disease progression in asymptomatic HTLV-1 carriers: a nationwide prospective study in Japan

Definitive risk factors for the development of adult T-cell leukemia (ATL) among asymptomatic human T-cell leukemia virus type I (HTLV-1) carriers remain unclear. Recently, HTLV-1 proviral loads have been evaluated as important predictors of ATL, but a few small prospective studies have been conducted. We prospectively evaluated 1218 asymptomatic HTLV-1 carriers (426 males and 792 females) who were enrolled during 2002 to 2008. The proviral load at enrollment was significantly higher in males than females (median, 2.10 vs 1.39 copies/100 peripheral blood mononuclear cells [PBMCs]; P < .001), in those 40 to 49 and 50 to 59 years of age than that of those 40 years of age and younger (P = .02 and .007, respectively), and in those with a family history of ATL than those without the history (median, 2.32 vs 1.33 copies/100 PBMCs; P = .005). During follow-up, 14 participants progressed to overt ATL. Their baseline proviral load was high (range, 4.17-28.58 copies/100 PBMCs). None developed ATL among those with a baseline proviral load lower than approximately 4 copies. Multivariate Cox analyses indicated that not only a higher proviral load, advanced age, family history of ATL, and first opportunity for HTLV-1 testing during treatment for other diseases were independent risk factors for progression of ATL.

High human T cell leukemia virus type-1(HTLV-1) provirus load in patients with HTLV-1 carriers complicated with HTLV-1-unrelated disorders

Background

To address the clinical and virological significance of a high HTLV-1 proviral load (VL) in practical blood samples from asymptomatic and symptomatic carriers, we simultaneously examined VL and clonal expansion status using polymerase chain reaction (PCR) quantification (infected cell % of peripheral mononuclear cells) and Southern blotting hybridization (SBH) methods.

Results

The present study disclosed extremely high VL with highly dense smears with or without oligoclonal bands in SBH. A high VL of 10% or more was observed in 16 (43.2%) of a total of 33 samples (one of 13 asymptomatic carriers, 8 of 12 symptomatic carriers, and 7 of 8 patients with lymphoma-type ATL without circulating ATL cells). In particular, an extremely high VL of 50% or more was limited to symptomatic carriers whose band findings always contained at least dense smears derived from polyclonally expanded cells infected with HTLV-1. Sequential samples revealed that the VL value was synchronized with the presence or absence of dense smears, and declined at the same time as disappearing dense smears. Dense smears transiently emerged at the active stage of the underlying disease. After disappearance of the smears, several clonal bands became visible and were persistently retained, explaining the process by which the clonality of HTLV-1-infected cells is established. The cases with only oligoclonal bands tended to maintain a stable VL of around 20% for a long time. Two of such cases developed ATL 4 and 3.5 years later, suggesting that a high VL with oligoclonal bands may be a predisposing risk to ATL.

Conclusion

The main contributor to extremely high VL seems to be transient emergence of dense smears detected by the sensitivity level of SBH, corresponding to polyclonal expansion of HTLV-1-infected cells including abundant small clones. Major clones retained after disappearance of dense smears stably persist and acquire various malignant characteristics step by step.

Definition, prognostic factors, treatment, and response criteria of adult T-cell leukemia-lymphoma: a proposal from an international consensus meeting

Adult T-cell leukemia-lymphoma (ATL) is a distinct peripheral T-lymphocytic malignancy associated with a retrovirus designated human T-cell lymphotropic virus type I (HTLV-1). The diversity in clinical features and prognosis of patients with this disease has led to its subclassification into the following four categories: acute, lymphoma, chronic, and smoldering types. The chronic and smoldering subtypes are considered indolent and are usually managed with watchful waiting until disease progression, analogous to the management of some patients with chronic lymphoid leukemia (CLL) or other indolent histology lymphomas. Patients with aggressive ATL generally have a poor prognosis because of multidrug resistance of malignant cells, a large tumor burden with multiorgan failure, hypercalcemia, and/or frequent infectious complications as a result of a profound T-cell immunodeficiency. Under the sponsorship of the 13th International Conference on Human Retrovirology: HTLV, a group of ATL researchers joined to form a consensus statement based on established data to define prognostic factors, clinical subclassifications, and treatment strategies. A set of response criteria specific for ATL reflecting a combination of those for lymphoma and CLL was proposed. Clinical subclassification is useful but is limited because of the diverse prognosis among each subtype. Molecular abnormalities within the host genome, such as tumor suppressor genes, may account for these diversities. A treatment strategy based on the clinical subclassification and prognostic factors is suggested, including watchful waiting approach, chemotherapy, antiviral therapy, allogeneic hematopoietic stem-cell transplantation (alloHSCT), and targeted therapies.

Reduction of human T-cell leukemia virus type-1 infection in mice lacking nuclear factor-kappaB-inducing kinase

Human T-cell lymphotropic virus type 1 (HTLV-1) causes adult T-cell leukemia and inflammatory disorders. Aberrant activation of nuclear factor-kappaB (NF-kappaB) has been linked to HTLV-1 pathogenesis and to various kinds of cancers, including adult T-cell leukemia. NF-kappaB-inducing kinase (NIK) is critical for non-canonical activation of NF-kappaB and for the development of lymphoid organs. HTLV-1 activates NF-kappaB by the non-canonical pathway, but examination of the role of NIK in proliferation of HTLV-1-infected cells in vivo has been hindered by lack of a suitable animal model. Alymphoplasia (aly/aly) mice bear a mutation of NIK, resulting in defects in the development of lymphoid organs and severe deficiencies in both humoral and cell-mediated immunity. In the present study we therefore used a mouse model of HTLV-1 infection with aly/aly mice. The number of HTLV-1-infected cells in the reservoir organs in aly/aly mice was significantly smaller than in the control group 1 month after infection. In addition, aly/aly mice did not maintain provirus for 1 year and antibodies against HTLV-1 were undetectable. These results demonstrate that the absence of functional NIK impairs primary HTLV-1 proliferation and abolishes the maintenance of provirus. Interestingly, clonal proliferation of HTLV-1-infected mouse cells was not detected in aly/aly mice, which is consistent with the lack of HTLV-1 persistence. These observations imply that the clonal proliferation of HTLV-1-infected cells in secondary lymphoid organs might be important for HTLV-1 persistence.

Effect of treatment of Strongyloides infection on HTLV-1 expression in a patient with adult T-cell leukemia

Human T-cell leukemia virus type 1 (HTLV-1) is associated with adult T-cell leukemia-lymphoma (ATLL) in about 5% of infected individuals. Coinfection by Strongyloides stercoralis has been suggested to be a cofactor for development of ATLL. We describe a patient who presented with HTLV-1-associated chronic ATLL and Strongyloides infection. Studies of this patient's viral RNA levels demonstrated stimulation of HTLV-1 replication by Strongyloides, which resolved with anti-helminthic therapy. This case provides support for the hypothesis that Strongyloides is a cofactor for ATLL via T-cell stimulation.

Human T-cell leukaemia virus type 1 (HTLV-1) infectivity and cellular transformation

It has been 30 years since a 'new' leukaemia termed adult T-cell leukaemia (ATL) was described in Japan, and more than 25 years since the isolation of the retrovirus, human T-cell leukaemia virus type 1 (HTLV-1), that causes this disease. We discuss HTLV-1 infectivity and how the HTLV-1 Tax oncoprotein initiates transformation by creating a cellular environment favouring aneuploidy and clastogenic DNA damage. We also explore the contribution of a newly discovered protein and RNA on the HTLV-1 minus strand, HTLV-1 basic leucine zipper factor (HBZ), to the maintenance of virus-induced leukaemia.

A rare intestinal manifestation in a patient with common variable immunodeficiency and strongyloidiasis

We report an immunodeficient patient with a rare gastrointestinal manifestation. A 26-year-old male with common variable immunodeficiency (CVID) and bronchiolitis obliterans, who was on intravenous gamma-globulin and prednisone, presented diffuse abdominal pain, nausea, vomiting and constipation of 3 days' duration. He reported 5 years of recurrent respiratory infections and diarrhea with negative stool tests, including tests for Strongyloides stercoralis. A physical exam revealed a poor general condition, anemia, dehydration and a distended painful abdomen with guarding, without abdominal sounds. The radiological study showed marked dilation of the small bowel that was edematous. Resection of the affected loop was performed and the histopathologic study showed transmural infection with S. stercoralis and hemorrhagic necrosis of the muscular layer, without mucosal destruction. The patient developed malabsorption syndrome and septic shock; he was treated with antibiotics and thiabendazole and was finally discharged in a good general condition. CVID is a rare disease and its association with systemic strongyloidiasis is very uncommon, but it has been reported in patients on corticosteroids. Hemorrhagic necrosis of the muscular layer without mucosal destruction was not found in the literature studied.

Increased TGF-beta, Cbl-b and CTLA-4 levels and immunosuppression in association with chronic immune activation

In this study we investigated the mechanisms mediating T-cell hyporesponsiveness in chronically immune-activated individuals. We analyzed in healthy and persistently helminth-infected individuals the relationship between immune activation and general T-cell hyporesponsiveness, Th3/regulatory T-cell expression, transforming growth factor-beta (TGF-beta) secretion, CTL-associated antigen 4 (CTLA-4) levels, Casitas B-cell lymphoma-b (Cbl-b) (a negative regulator of T-cell activation) levels and phosphorylation of mitogen-activated protein kinases/extracellular signal-regulated kinase (ERK)-1 and -2. We found a very significant increase in plasma levels of TGF-beta and intracellular pools of CTLA-4 and Cbl-b in association with immune activation, which correlates with decreased T-cell responses to anti-CD3 stimulation. We demonstrate that the impaired activity of ERK of peripheral T cells in highly immune-activated individuals is associated with increased levels of CTLA-4 and Cbl-b. Interestingly, in some, but not in all, of these immune-activated individuals, induction of Cbl-b intracellular pools occurs by TGF-beta or CTLA-4 stimulation. We suggest that the higher levels of CTLA-4 and TGF-beta, both involved in the induction of Cbl-b, point at potential mechanisms underlying general and antigen-specific immune hyporesponsiveness in chronically infected individuals.

Oncolytic activity of vesicular stomatitis virus in primary adult T-cell leukemia

Treatments for hematological malignancies have improved considerably over the past decade, but the growing therapeutic arsenal has not benefited adult T-cell leukemia (ATL) patients. Oncolytic viruses such as vesicular stomatitis virus (VSV) have recently emerged as a potential treatment of solid tumors and leukemias in vitro and in vivo. In the current study, we investigated the ability of VSV to lyse primary human T-lymphotropic virus type 1 (HTLV-1)-infected T-lymphocytes from patients with ATL. Ex vivo primary ATL cells were permissive for VSV and underwent rapid oncolysis in a time-dependent manner. Importantly, VSV infection showed neither viral replication nor oncolysis in HTLV-1-infected, nonleukemic cells from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and in naive CD4(+) T-lymphocytes from normal individuals or in ex vivo cell samples from patients with chronic lymphocytic leukemia (CLL). Interestingly, activation of primary CD4(+) T-lymphocytes with anti-CD3/CD28 monoclonal antibody, and specifically with anti-CD3, was sufficient to induce limited viral replication and oncolysis. However, at a similar level of T-cell activation, VSV replication was increased fourfold in ATL cells compared to activated CD4(+) T-lymphocytes, emphasizing the concept that VSV targets genetic defects unique to tumor cells to facilitate its replication. In conclusion, our findings provide the first essential information for the development of a VSV-based treatment for ATL.

The human T-cell leukemia virus type 1 (HTLV-1): New insights into the clinical aspects and molecular pathogenesis of adult t-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-associated myelopathy (TSP/HAM)

Human T-cell leukemia virus type 1 (HTLV-1) was the first human retrovirus to be identified in the early 1980s. The isolation and identification of a related virus, HTLV-2, and the distantly related human immunodeficiency virus (HIV) immediately followed. Of the three retroviruses, two are associated definitively with specific diseases, HIV, with acquired immune deficiency syndrome (AIDS) and HTLV-1, with adult T-cell leukemia/lymphoma (ATLL) and tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). While an estimated 10-20 million people worldwide are infected with HTLV-I, infection is endemic in the Caribbean, parts of Africa, southwestern Japan, and Italy. Approximately 4% of HTLV-I infected individuals develop ATLL, a disease with a poor prognosis. The clinical manifestations of infection and the current biology of HTLV viruses with emphasis on HTLV-1 are discussed in detail. The implications for improvements in diagnosis, treatment, intervention, and vaccination are included, as well as a discussion of the emergence of HTLV-1 and -2 as copathogens among HIV-1-infected individuals.

Global epidemiology of HTLV-I infection and associated diseases

Epidemiologic aspects of human T-lymphotropic virus type I (HTLV-I) infection have been thoroughly studied over the course of approximately 25 years since its first description. The geographic distribution of the virus has been defined, with Japan, Africa, Caribbean islands and South America emerging as the areas of highest prevalence. The reasons for HTLV-I clustering, such as the high ubiquity in southwestern Japan but low prevalence in neighboring regions of Korea, China and eastern Russia are still unknown. The major modes of transmission are well understood, although better quantitative data on the incidence of transmission, and on promoting/inhibiting factors, are needed. Epidemiologic proof has been obtained for HTLV-I's causative role in major disease associations: adult T-cell leukemia (ATL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-associated uveitis and infective dermatitis. However, more and better studies are needed for other apparent disease outcomes such as rheumatologic, psychiatric and infectious diseases. Since curative treatment of ATL and HAM/TSP is lacking and a vaccine is unavailable, the social and financial cost for the individual, his/her family and the health system is immense. For this reason, public health interventions aimed at counseling and educating high-risk individuals and populations are of paramount importance.

Activation of human T cell leukemia virus type 1 LTR promoter and cellular promoter elements by T cell receptor signaling and HTLV-1 Tax expression

Human T cell leukemia virus 1 (HTLV-1) gene expression is regulated by both the viral Tax protein and by cellular transcriptional factors. We have previously shown that immune activation stimuli such as phorbol esters (PMA) and phytohemagglutinin (PHA) cooperate with HTLV-1 Tax expression to enhance HTLV-1 gene expression in infected T cells through increased activity of the HTLV-1 LTR. We now extend these studies to demonstrate roles for the T cell receptor complex, Lck, and Ras molecules in the coactivation of the HTLV-1 LTR by Tax and T cell activation stimuli. We also observe coactivation of Tax-responsive cellular promoter elements containing NF-kappaB and serum response factor (SRF) binding sites by Tax and T cell activation stimuli. These results suggest a model whereby T cell receptor stimulation and Tax expression coactivate HTLV-1 gene expression and cellular gene expression, enhancing activation of latent HTLV-1 and expression of cellular genes involved in disease pathogenesis.

A tax on luxury: HTLV-I infection of CD4+CD25+ Tregs

Almost a quarter of a century ago, Oldstone and colleagues proposed that infection of cells by noncytopathic viruses may lead to an alteration of the cells' ability to produce certain products or perform certain tasks, i.e., inhibition of "luxury function." In this issue of the JCI, this topic has been revisited by Yamano et al., who demonstrate that human T cell lymphotropic virus type I (HTLV-I) infection of CD4(+)CD25(+) Tregs in patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) results in a decrease in FOXP3 mRNA and protein expression. This leads to the inability of HTLV-I-infected CD4(+)CD25(+) Tregs to inhibit the proliferation of CD4(+)CD25(-) Tregs, due to the effect of the HTLV-I tax gene. Defects in the Treg population could be responsible for the large numbers of virus-specific T cells and occurrence of lymphoproliferation and inflammatory autoimmune disease in HAM/TSP patients.

Epidemiological and clinical interaction between HTLV-1 and Strongyloides stercoralis

Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.

Complicated and fatal Strongyloides infection in Canadians: risk factors, diagnosis and management

Strongyloidiasis, which is caused by the nematode Strongyloides stercoralis, is a common and persistent infection, particularly in developing countries. In the setting of compromised cellular immunity, it can result in fulminant dissemination with case-fatality rates of over 70%. The majority of new Canadian immigrants come from countries where Strongyloides is highly endemic; therefore, the burden of Strongyloides may be underappreciated in Canada. Because early diagnosis and therapy can have a marked impact on disease outcome, screening for this infection should be considered mandatory for patients who have a history of travel or residence in a disease-endemic area and risk factors for disseminated disease (e.g., corticosteroid use and human T-lymphotropic virus type I infection).

Role of accessory proteins of HTLV-1 in viral replication, T cell activation, and cellular gene expression

Human T-cell lymphotropic virus type 1 (HTLV-1), causes adult T cell leukemia/lymphoma (ATLL), and initiates a variety of immune mediated disorders. The viral genome encodes common structural and enzymatic proteins characteristic of all retroviruses and utilizes alternative splicing and alternate codon usage to make several regulatory and accessory proteins encoded in the pX region (pX ORF I to IV). Recent studies indicate that the accessory proteins p12I, p27I, p13II, and p30II, encoded by pX ORF I and II, contribute to viral replication and the ability of the virus to maintain typical in vivo expression levels. Proviral clones that are mutated in either pX ORF I or II, while fully competent in cell culture, are severely limited in their replicative capacity in a rabbit model. These HTLV-1 accessory proteins are critical for establishment of viral infectivity, enhance T-lymphocyte activation and potentially alter gene transcription and mitochondrial function. HTLV-1 pX ORF I expression is critical to the viral infectivity in resting primary lymphocytes suggesting a role for the calcineurin-binding protein p12I in lymphocyte activation. The endoplasmic reticulum and cis-Golgi localizing p12I activates NFAT, a key T cell transcription factor, through calcium-mediated signaling pathways and may lower the threshold of lymphocyte activation via the JAK/STAT pathway. In contrast p30II localizes to the nucleus and represses viral promoter activity, but may regulate cellular gene expression through p300/CBP or related co-activators of transcription. The mitochondrial localizing p13II induces morphologic changes in the organelle and may influence energy metabolism infected cells. Future studies of the molecular details HTLV-1 "accessory" proteins interactions will provide important new directions for investigations of HTLV-1 and related viruses associated with lymphoproliferative diseases. Thus, the accessory proteins of HTLV-1, once thought to be dispensable for viral replication, have proven to be directly involved in viral spread in vivo and represent potential targets for therapeutic intervention against HTLV-1 infection and disease.