Human T cell lymphotropic virus-associated leukemia/lymphoma

Targeting NF-κB with Nanotherapy in a Mouse Model of Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive, clonal malignancy of mature T cells caused by human T-cell leukemia virus type 1. Although it is a rare tumor type, it serves as an excellent model of a virus driven process that transforms cells and engenders a highly malignant tumor that is extraordinarily difficult to treat. The viral transcriptional transactivator (Tax) in the HTLV-1 genome directly promotes tumorigenesis, and Tax-induced oncogenesis depends on its ability to constitutively activate NF-κB signaling. Accordingly, we developed and evaluated a nano-delivery system that simultaneously inhibits both canonical (p65) and noncanonical (p100) NF-κB signaling pathways locally in tumors after systemic administration. Our results demonstrate that siRNA is delivered rapidly to ATLL tumors after either i.p. or i.v. injection. The siRNA treatment significantly reduced both p65 and p100 mRNA and protein expression. Anti-NF-κB nanotherapy significantly inhibited tumor growth in two distinct tumor models in mice: a spontaneous Tax-driven tumor model, and a Tax tumor cell transplant model. Moreover, siRNA nanotherapy sensitized late-stage ATLL tumors to the conventional chemotherapeutic agent etoposide, indicating a pleiotropic benefit for localized siRNA nanotherapeutics.

In Vivo Tumorigenesis, Osteolytic Sarcomas, and Tumorigenic Cell Lines from Transgenic Mice Expressing the Human T-Lymphotropic Virus Type 1 (HTLV-1) Tax Viral Oncogene

Human T-lymphotropic virus type 1 (HTLV-1) causes adult T-cell leukemia, a disease commonly associated with hypercalcemia and osteolysis. There is no effective treatment for HTLV-1, and the osteolytic mechanisms are not fully understood. Mice expressing the HTLV-1 oncogene Tax, driven by the human granzyme B promoter (Tax+), develop osteolytic tumors. To investigate the progression of the bone-invasive malignancies, wild-type, Tax+, and Tax+/interferon-γ-/- mice were assessed using necropsy, histologic examination, IHC analysis, flow cytometry, and advanced imaging. Tax+ and Tax+/interferon-γ-/- malignancies of the ear, tail, and foot comprised poorly differentiated, round to spindle-shaped cells with prominent neutrophilic infiltrates. Tail tumors originated from muscle, nerve, and/or tendon sheaths, with frequent invasion into adjacent bone. F4/80+ and anti-mouse CD11b (Mac-1)+ histiocytic cells predominated within the tumors. Three Tax+/interferon-γ-/- cell lines were generated for in vivo allografts, in vitro gene expression and bone resorption assays. Two cell lines were of monocyte/macrophage origin, and tumors formed in vivo in all three. Differences in Pthrp, Il6, Il1a, Il1b, and Csf3 expression in vitro were correlated with differences in in vivo plasma calcium levels, tumor growth, metastasis, and neutrophilic inflammation. Tax+ mouse tumors were classified as bone-invasive histiocytic sarcomas. The cell lines are ideal for further examination of the role of HTLV-1 Tax in osteolytic tumor formation and the development of hypercalcemia and tumor-associated inflammation.

Adult T-cell leukemia/lymphoma

Summary Adult T-cell leukemia/lymphoma (ATL) is a malignancy of mature CD4+ T-cells caused by human T-cell lymphotropic virus type 1 (HTLV-1). Twenty million people are believed to be infected throughout the world, mostly in Japan, Africa, the Caribbean, and South America, particularly in Brazil and Peru. ATL affects about 5% of infected individuals and is classified in the following clinical forms: acute, lymphoma, primary cutaneous tumoral, chronic (favorable and unfavorable), and smoldering (leukemic and non-leukemic). Although it is considered an aggressive disease, there are cases with a long progression. We emphasize the importance of clinical classification as an indispensable element for evaluating prognosis and appropriate therapeutic approach. Since several cases have been published in Brazil and this disease is still poorly known, we decided to make a review paper for dissemination of clinical, hematological and pathological aspects, diagnosis, and therapy. The best way to reduce the occurrence of ATL would be halting the transmission of the virus through breastfeeding.

HLA-G 3'-untranslated region polymorphisms are associated with HTLV-1 infection, proviral load and HTLV-associated myelopathy/tropical spastic paraparesis development

Most human T-lymphotropic virus type 1 (HTLV-1)-infected patients remain asymptomatic throughout life. The factors associated with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) development have not been fully elucidated; immunological and genetic factors may be involved. The association of 14 bp INS/DEL HLA-G polymorphism with HTLV-1 infection susceptibility has been reported previously. Here, other polymorphic sites at the HLA-G 3'-UTR (14-bp D/I, +3003C/T, +3010C/G, +3027A/C, +3035C/T, +3142C/G, +3187A/G and +3196C/G) were evaluated in 37 HTLV-1-infected individuals exhibiting HAM/TSP, 45 HTLV-1 asymptomatic carriers (HAC) and 153 uninfected individuals, followed up at University Hospital of the Faculty of Medicine of Ribeirão Preto, University of São Paulo, Brazil. It was observed that: (i) 14bpDI genotype is a risk factor for HTLV-1 infection, while the 14bpDD and +3142CC genotypes were associated with protection against infection; (ii) the +3142C allele and the +3003CT and +3142CC genotypes were associated with susceptibility, while 14bpII and +3003TT genotypes were associated with protection against HAM/TSP development; and (iii) the 14bpII, +3010CC, +3142GG and +3187AA genotypes were associated with lower HTLV-1 proviral load compared to respective counterpart genotypes. Findings that HLA-G has a well-recognized immunomodulatory role and that the genetic variability at HLA-G 3'-UTR may post-transcriptionally modify HLA-G production indicate a differential genetic susceptibility to: (i) the development of HTLV-1 infection, (ii) the magnitude of HTLV-1 proviral load and (iii) HAM/TSP development.

Adult T-Cell Leukemia/Lymphoma

Adult T-cell leukemia/lymphoma is a rare mature CD4+ T-cell neoplasm caused by the retrovirus human T-lymphotrophic virus type 1. At present there are approximately 20 million people infected globally with this virus, and most of these individuals belong to the endemic areas in southern Japan, Africa, the Caribbean basin, and Latin America. In the United States, it is usually seen in immigrants from these endemic regions. Adult T-cell leukemia/lymphoma predominantly affects the adult population and is rare in children. Adult T-cell leukemia/lymphoma has 4 subtypes: acute, lymphomatous, chronic, and smoldering. Clinically, the first 2 variants are classified as aggressive, and the latter two are classified as indolent. Given the rare occurrence and diagnostic challenges associated with adult T-cell leukemia/lymphoma, this review will highlight its salient features to aid in recognition of this entity and perform a comprehensive diagnostic workup.

Transfusion-transmitted human T-lymphotropic virus Type I infection in a United States military emergency whole blood transfusion recipient in Afghanistan, 2010

BACKGROUND

The United States introduced human T-lymphotropic virus Type I (HTLV-I) screening of blood donors in 1988. The US military uses freshly collected blood products for life-threatening injuries when available stored blood components in theater have been exhausted or when these components are unsuccessful for resuscitation. These donors are screened after donation by the Department of Defense (DoD) retrospective testing program. All recipients of blood collected in combat are tested according to policy soon after and at 3, 6, and 12 months after transfusion.

CASE REPORT

A 31-year-old US Army soldier tested positive for HTLV-I 44 days after receipt of emergency blood transfusions for severe improvised explosive device blast injuries. One donor's unit tested HTLV-I positive on the DoD-mandated retrospective testing. Both the donor and the recipient tested reactive with enzyme immunoassay and supplemental confirmation by HTLV-I Western blot. The donor and recipient reported no major risk factors for HTLV-I. Phylogenetic analysis of HTLV-I sequences indicated Cosmopolitan subtype, Subgroup B infections. Comparison of long terminal repeat and env sequences revealed molecular genetic linkage of the viruses from the donor and recipient.

CONCLUSION

This case is the first report of transfusion transmission of HTLV-I in the US military during combat operations. The emergency fresh whole blood policy enabled both the donor and the recipient to be notified of their HTLV-I infection. While difficult in combat, predonation screening of potential emergency blood donors with Food and Drug Administration-mandated infectious disease testing as stated by the DoD Health Affairs policy should be the goal of every facility engaged with emergency blood collection in theater.

Kaposi sarcoma-associated herpesvirus-encoded viral FLICE inhibitory protein (vFLIP) K13 cooperates with Myc to promote lymphoma in mice

Primary effusion lymphoma (PEL) is an aggressive form of lymphoma that is associated with infection by Kaposi's sarcoma-associated herpesvirus (KSHV). One of the KSHV genes expressed in PEL cells is K13, a potent activator of the NF-κB pathway. K13 transgenic mice develop lymphomas, but after a long period of latency. A possible candidate that could cooperate with K13 in the development of PEL is c-Myc, whose expression is frequently dysregulated in PEL cells. To study the cooperative interaction between K13 and c-Myc in the pathogenesis of PEL, we crossed the K13 transgenic mice to iMyc(Eμ) transgenic mice that overexpress Myc. We report that lymphomas in the K13/iMyc(Eμ) double transgenic mice developed with shorter latency and were histologically distinct from those observed in the iMyc(Eμ) mice. Lymphomas in the K13/iMyc(Eμ) mice also lacked the expression of B- and T-cell markers, thus resembling the immunophenotype of PEL. The accelerated development of lymphoma in the K13/iMyc(Eμ) mice was associated with increased expression of K13, elevated NF-κB activity and decrease in apoptosis. Taken collectively, our results demonstrate a cooperative interaction between the NF-κB and Myc pathways in lymphomagenesis.

Leucemia/linfoma de células T do adulto

A leucemia/linfoma de células T do adulto (ATL) é tipo agressivo de doença linfoproliferativa causada pelo vírus linfotrópico para células T humanas (HTLV-I), geralmente fatal e que não responde a quimioterapia. Classifica-se em formas aguda, crônica, linfomatosa e indolente (smoldering). Outra forma clínica, a tumoral primária de pele, com características diferentes, foi sugerida recentemente. As formas aguda, linfomatosa e tumoral primária de pele são as de pior prognóstico. Os critérios diagnósticos de ATL são: sorologia positiva para o HTLV-I; diagnóstico citológico ou histológico de leucemia/linfoma de células T, CD4+/CD25+; presença de linfócitos T anormais em sangue periférico; confirmação de integração monoclonal do DNA proviral do HTLV-I. Há lesões de pele em cerca de 70% dos casos,que podem ser primários (formas indolente e tumoral primária da pele) ou secundários. As lesões cutâneas são múltiplas, sendo as mais freqüentes a eritrodermia, as pápulas e as placas. A ATL não tem aspecto histológico característico, podendo apresentar padrões superponíveis ao linfoma periférico T não especificado, à micose fungóide ou ao linfoma anaplásico de grandes células. O padrão imuno-histoquímico pode também simular o de outros tipos de linfoma T. Por esse motivo, é muito importante que no Brasil seja solicitada sorologia para o HTLV-I em todos os casos de leucemia e/ou linfoma de células T maduras.

Transmission of tropical and geographically restricted infections during solid-organ transplantation

In recent years, the increasing number of donors from different regions of the world is providing a new challenge for the management and selection of suitable donors. This is a worldwide problem in most countries with transplantation programs, especially due to the increase in immigration and international travel. This paper elaborates recommendations regarding the selection criteria for donors from foreign countries who could potentially transmit tropical or geographically restricted infections to solid-organ transplant recipients. For this purpose, an extensive review of the medical literature focusing on viral, fungal, and parasitic infections that could be transmitted during transplantation from donors who have lived or traveled in countries where these infections are endemic has been performed, with special emphasis on tropical and imported infections. The review also includes cases described in the literature as well as risks of transmission during transplantation, microbiological tests available, and recommendations for each infection. A table listing different infectious agents with their geographic distributions and specific recommendations is included.

Tax interacts with P-TEFb in a novel manner to stimulate human T-lymphotropic virus type 1 transcription

Human T-lymphotropic virus type 1 (HTLV-1) encodes a transcriptional activator, Tax, whose function is essential for viral transcription and replication. Tax transactivates the viral long-terminal repeat through a series of protein-protein interactions which facilitate CREB and CBP/p300 binding. In addition, Tax dissociates transcription repressor histone deacetylase 1 interaction with the CREB response element. The subsequent events through which Tax interacts and communicates with RNA polymerase II and cyclin-dependent kinases (CDKs) are not clearly understood. Here we present evidence that Tax recruits positive transcription elongation factor b (P-TEFb) (CDK9/cyclin T1) to the viral promoter. This recruitment likely involves protein-protein interactions since Tax associates with P-TEFb in vitro as demonstrated by glutathione S-transferase fusion protein pull-down assays and in vivo as shown by co-immunoprecipitation assays. Functionally, small interfering RNA directed toward CDK9 inhibited Tax transactivation in transient assays. Consistent with these findings, the depletion of CDK9 from nuclear extracts inhibited Tax transactivation in vitro. Reconstitution of the reaction with wild-type P-TEFb, but not a kinase-dead mutant, recovered HTLV-1 transcription. Moreover, the addition of the CDK9 inhibitor flavopiridol blocked Tax transactivation in vitro and in vivo. Interestingly, we found that Tax regulates CDK9 kinase activity through a novel autophosphorylation pathway.