Yohann White

Target epitopes of HTLV-1 recognized by class I MHC-restricted cytotoxic T lymphocytes in patients with myelopathy and spastic paraparesis and infected patients with autoimmune disorders†

Human T‐cell lymphotropic virus type I (HTLV‐1) causes adult T‐cell leukemia/lymphoma and HTLV‐1‐associated myelopathy/tropical spastic paraparesis (HAM/TSP). The different patterns of clinical diseases are thought to be linked to immunogenetic host factors. A variety of autoimmune diseases, such as Sjögrens syndrome, have been reported in persons infected with HTLV‐1, although the precise relationship between these disorders and HTLV‐1 infection remains unknown. There is no report on the repertoire of HTLV‐1‐specific CD8+ T‐cells in HAM/TSP patients or carriers with autoimmune diseases, both characterized by an abnormal immune state. In this study, to characterize HTLV‐1‐specific CD8+ T‐cells in asymptomatic HTLV‐1 carriers, HAM/TSP patients and carriers with autoimmune diseases, we examined the frequency and diversity of HTLV‐1‐specific CD8+ T‐cells using HTLV‐1 tetramers. HTLV‐1 Env‐specific CD8+ T‐cells were significantly more frequent in HAM/TSP and carriers with autoimmune diseases compared with asymptomatic HTLV‐1 carriers, while the frequency of HTLV‐1 Tax‐specific CD8+ T‐cells was not significantly different among them. CD8+ cells binding to HTLV‐1 Tax tetramers in carriers with autoimmune diseases were significantly reduced compared with HAM/TSP patients. This study demonstrates the importance of CD8+ T‐cells recognizing HTLV‐1 Env‐tetramers in HAM/TSP patients and carriers with autoimmune diseases, thereby suggesting that the diversity, frequency and repertoire of HTLV‐1 Env‐specific CD8+ T‐cell clones may be related to the hyperimmune response in HAM/TSP and carriers with autoimmune diseases, although different immunological mechanisms may mediate the hyperimmunity in these conditions. J. Med. Virol. 83:501–509, 2011.

Oligomannose‐coated liposomes efficiently induce human T‐cell leukemia virus‐1‐specific cytotoxic T lymphocytes without adjuvant

Human T‐cell leukemia virus‐1 (HTLV‐1) causes adult T‐cell leukemia/lymphoma, which is an aggressive peripheral T‐cell neoplasm. Insufficient T‐cell response to HTLV‐1 is a potential risk factor in adult T‐cell leukemia/lymphoma. Efficient induction of antigen‐specific cytotoxic T lymphocytes is important for immunological suppression of virus‐infected cell proliferation and oncogenesis, but efficient induction of antigen‐specific cytotoxic T lymphocytes has evaded strategies utilizing poorly immunogenic free synthetic peptides. Here, we examined the efficient induction of an HTLV‐1‐specific CD8+ T‐cell response by oligomannose‐coated liposomes (OMLs) encapsulating the human leukocyte antigen (HLA)‐A*0201‐restricted HTLV‐1 Tax‐epitope (OML/Tax). Immunization of HLA‐A*0201 transgenic mice with OML/Tax induced an HTLV‐1‐specific gamma‐interferon reaction, whereas immunization with epitope peptide alone induced no reaction. Upon exposure of dendritic cells to OML/Tax, the levels of CD86, major histocompatibility complex class I, HLA‐A02 and major histocompatibility complex class II expression were increased. In addition, our results showed that HTLV‐1‐specific CD8+ T cells can be efficiently induced by OML/Tax from HTLV‐1 carriers compared with epitope peptide alone, and these HTLV‐1‐specific CD8+ T cells were able to lyse cells presenting the peptide. These results suggest that OML/Tax is capable of inducing antigen‐specific cellular immune responses without adjuvants and may be useful as an effective vaccine carrier for prophylaxis in tumors and infectious diseases by substituting the epitope peptide.

Programmed death-1 (PD-1)/PD-1 ligand pathway-mediated immune responses against human T-lymphotropic virus type 1 (HTLV-1) in HTLV-1-associated myelopathy/tropical spastic paraparesis and carriers with autoimmune disorders.

Human T-lymphotropic virus-1 (HTLV-1) causes HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia-lymphoma in individuals with dysfunctional immune responses. In this study, to characterize the HTLV-1-specific cytotoxic T lymphocyte (CTL) populations in asymptomatic HTLV-1 carriers (ACs), HAM/TSP patients, and carriers with autoimmune disorders (CAIDs), we examined the role of programmed death-1 and its ligand (PD-1/PD-L1) in HTLV-1-specific CTL functions using an HTLV-1 Tax/HLA-A*0201 tetramer and an HTLV-1 Tax/HLA-A*2402 tetramer. Interestingly, the percentage of HTLV-1 Tax301-309/HLA-A*2402 tetramer(+)CD8(+) cells expressing PD-1 in ACs was significantly higher than the percentage of HTLV-1 Tax11-19/HLA-A*0201 tetramer(+)CD8(+) cells expressing PD-1. PD-1 expression was significantly downregulated on HTLV-1-specific CTLs in HAM/TSP compared with ACs. PD-L1 expression was observed in a small proportion of unstimulated lymphocytes from ACs and was greater in ACs than in HAM/TSP and CAIDs after short-term culture. Furthermore, CTL degranulation was impaired in HAM/TSP, whereas anti-PD-L1 blockade significantly increased CTL function in ACs. Downregulation of PD-1 on HTLV-1-specific CTLs and loss of PD-L1 expression in HAM/TSP and CAIDs, along with impaired function of HTLV-1-specific CTLs in HAM/TSP, may underlie the apparently dysfunctional immune response against HTLV-1.

Prevention of human T-cell lymphotropic virus type 1 infection and adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a highly aggressive peripheral T-cell malignancy that develops after long-term chronic infection with human T-cell lymphotropic virus type-1 (HTLV-1). Despite the recent advances in chemotherapy, allogeneic hematopoietic stem cell transplantation (alloHSCT), and supportive care, the prognosis for patients with ATL is one of the poorest among hematological malignancies; overall survival (OS) at 3 years is only 24 % in the more aggressive subtypes of ATLL. HTLV-1 is a human retrovirus infecting approximately 10-20 million people worldwide, particularly in southern and southeastern Japan, the Caribbean, highlands of South America, Melanesia, and Equatorial Africa. Despite this high frequency of human infection, only 2-5 % of HTLV-1-infected individuals develop ATLL. Three major routes of viral transmission have been established: (1) mother-to-child transmission through breast-feeding; (2) sexual transmission, predominantly from men to women; and (3) cellular blood components. Multiple factors (e.g., virus, host cell, and immune factors) have been implicated in the development of ATLL, although the underlying mechanisms of leukemogenesis have not been fully elucidated. No preventive vaccine against HTLV-1 is currently available, and interrupting the well-recognized primary modes of HTLV-1 transmission is the mainstay of ATLL prevention. Prevention of mother-to-child transmission through the replacement of breast-feeding has been shown to have the most significant impact on the incidence of HTLV-1 infection, and public health policies should consider the risk of malnutrition, especially in developing countries where malnutrition is the significant cause of infant mortality.

Efficient induction of human T-cell leukemia virus-1-specific CTL by chimeric particle without adjuvant as a prophylactic for adult T-cell leukemia

Adult T-cell leukemia-lymphoma (ATL) is an aggressive peripheral T-cell neoplasm that develops after long-term infection with the human T-cell leukemia virus-1 (HTLV-1). HTLV-1-specific cytotoxic T lymphocytes (CTLs) play an important role in suppressing proliferation of HTLV-1-infected or transformed T-cells in vitro. Efficient induction of antigen-specific CTLs is important for immunologic suppression of oncogenesis, but has evaded strategies utilizing poorly immunogenic free synthetic peptides. In the present study, we examined the efficient induction of HTLV-1-specific CD8+ T-cell response by an HTLV-1/hepatitis B virus core (HBc) chimeric particle incorporating the HLA-A*0201-restricted HTLV-1 Tax-epitope. The immunization of HLA-A*0201-transgenic mice with the chimeric particle induced antigen-specific gamma-interferon reaction, whereas immunization with epitope peptide only induced no reaction as assessed by enzyme-linked immunospot assay. Immunization with the chimeric particle also induced HTLV-1-specific CD8+ T-cells in spleen and inguinal lymph nodes. Furthermore, upon exposure of dendritic cells from HLA-A*0201-transgenic mice to the chimeric particle, the expression of CD86, HLA-A02, TLR4 and MHC class II was increased. Additionally, our results show that HTLV-1-specific CD8+ T-cells can be induced by peptide with HTLV-1/HBc particle from ATL patient, but not by peptide only and these HTLV-1-specific CD8+ T-cells were able to lyse cells presenting the peptide. These results suggest that HTLV-1/HBc chimeric particle is capable of inducing strong cellular immune responses without adjuvants via effective maturation of dendritic cells and is potentially useful as an effective carrier for therapeutic vaccines in tumors, or in infectious diseases by substituting the epitope peptide.

HTLV-1 Specific CD8+ T Cell Function Augmented by Blockade of 2B4/CD48 Interaction in HTLV-1 Infection

CD8+ T cell response is important in the response to viral infections; this response though is regulated by inhibitory receptors. Expression of inhibitory receptors has been positively correlated with CD8+ T cell exhaustion; the consequent effect of simultaneous blockade of these inhibitory receptors on CD8+ T cell response in viral infections have been studied, however, the role of individual blockade of receptor-ligand pair is unclear. 2B4/CD48 interaction is involved in CD8+T cell regulation, its signal transducer SAP (signaling lymphocyte activation molecule (SLAM)-associated protein) is required for stimulatory function of 2B4/CD244 on lymphocytes hence, we analyzed 2B4/CD244 (natural killer cell receptor) and SAP (signaling lymphocyte activation molecule(SLAM)-associated protein) on total CD8+ and HTLV-1 specific CD8+T cells in HTLV-1 infection and the effect of blockade of interaction with ligand CD48 on HTLV-1 specific CD8+ T cell function. We observed a high expression of 2B4/CD244 on CD8+ T cells relative to uninfected and further upregulation on HTLV-1 specific CD8+ T cells. 2B4+ CD8+ T cells exhibited more of an effector and terminally differentiated memory phenotype. Blockade of 2B4/CD48 interaction resulted in improvement in function via perforin expression and degranulation as measured by CD107a surface mobilization on HTLV-1 specific CD8+ T cells. In the light of these findings, we thus propose an inhibitory role for 2B4/CD48 interaction on CD8+T cell function.

Mental health needs of sexual minorities in Jamaica.

ABSTRACT This study examined the prevalence of Axis I disorders and associated risk factors in a sample of sexual minority men and women in Jamaica, a country that is widely known for its high societal rejection of homosexuality. Poor relationships with family, negative or abusive experiences related to ones sexual orientation, and greater openness about ones sexual orientation were independent risk factors for Axis I disorders. Prevention of mental disorders in sexual minorities in Jamaica should focus on rebuilding family support and promoting social acceptance of sexual minorities.

The Bioassay-Guided Isolation of Growth Inhibitors of Adult T-Cell Leukemia (ATL), from the Jamaican Plant Hyptis verticillata, and NMR Characterization of Hyptoside

Through bioassay-guided isolation, five compounds with growth inhibitory activity on S1T, an adult T-cell leukemia (ATL) cell line, were isolated from the crude methanol extract of the aerial parts of Hyptis verticillata.

Aggressive NK cell leukaemia after splenectomy: association with CD95‐resistant memory T‐cell proliferation and recalcitrant clinical course of haemophagocytic syndrome

We describe a 44‐yr‐old Japanese woman with persistent polyclonal T‐cell proliferation and recalcitrant clinical course of haemophagocytic syndrome (HPS). T cells bearing αβ T‐cell receptors (TCR) expressed increased amounts of CD95 and of CD45RO, which are phenotypically memory T cells. The TCR repertoire was broad and diverse. Regardless of CD95 expression, these cells were resistant to CD95‐mediated apoptosis. Aggressive natural killer cell leukaemia (ANKL) without an association with Epstein–Barr virus was detected 1 month after therapeutic splenectomy that followed 3 yr of immunosuppressive therapy against HPS. The immunophenotype of these leukaemia cells was CD56, CD16dim, CD7, CD45RA and they expressed some CD2, CD8 and HLA‐DR. Moreover, hyperdiploid clones with complex chromosomal abnormalities were also detected. Latent NK‐cell malignancy seemed to cause the CD95‐resistant memory T‐cell proliferation and splenectomy resulted in overt ANKL progression. There should be careful consideration of the risks versus benefits of splenectomy in HPS, in light of the possibility of fatal leukaemia/lymphoma progression.

Effects of exogenous interleukin-7 on CD8(+) T-cell survival and function in human T-cell lymphotropic virus type 1 infection

Abstract Interleukin-7 (IL-7) mediates T-cell homeostasis through its effects on T-cell development, survival and function. In human T-cell lymphotropic virus type 1 (HTLV-1) infection, which is causally implicated in adult T-cell leukemia (ATL), the efficiency with which CD8(+) cytotoxic T-lymphocytes (CTLs) clear HTLV-1-infected cells mediates viral control and may be related to disease progression. We report here that CD127 expression in CD8(+) T-cells is independently related to disease status, and that exogenous IL-7 enhances CD8(+) T-cell survival and clearance of HTLV-1 infected cells in vitro. We conclude that CD127 down-regulation may be associated with disease status in HTLV-1 infection, and propose that exogenous IL-7 may be useful immunotherapy or cytokine adjuvant for an anti-ATL therapeutic vaccine.