The effect of antiretroviral treatment of different durations in primary HIV infection.

OBJECTIVES: To compare immunological, virological and clinical outcomes in persons initiating combination antiretroviral therapy (cART of different durations within 6 months of seroconversion (early treated) with those who deferred therapy (deferred group). DESIGN: CD4 cell and HIV-RNA measurements for 'early treated' individuals following treatment cessation were compared with the corresponding ART-free period for the 'deferred' group using piecewise linear mixed models. Individuals identified during primary HIV infection were included if they seroconverted from 1st January 1996 and were at least 15 years of age at seroconversion. Those with at least 2 CD4 less than 350 cells/microl or AIDS within the first 6 months following seroconversion were excluded. RESULTS: Of 348 'early treated' patients, 147 stopped cART following treatment for at least 6 (n = 38), more than 6-12 (n = 40) or more than 12 months (n = 69). CD4 cell loss was steeper for the first 6 months following cART cessation, but subsequent loss rate was similar to the 'deferred' group (n = 675, P = 0.26). Although those treated for more than 12 months appeared to maintain higher CD4 cell counts following cART cessation, those treated for 12 months or less had CD4 cell counts 6 months after cessation comparable to those in the 'deferred' group. There was no difference in HIV-RNA set points between the 'early' and 'deferred' groups (P = 0.57). AIDS rates were similar but death rates, mainly due to non-AIDS causes, were higher in the 'deferred' group (P = 0.05). CONCLUSION: Transient cART, initiated within 6 months of seroconversion, seems to have no effect on viral load set point and limited beneficial effect on CD4 cell levels in individuals treated for more than 12 months. Its long-term effects remain inconclusive and need further investigation.

Dose-dependent influence of didanosine on immune recovery in HIV-infected patients treated with tenofovir.

BACKGROUND: Antiretroviral therapy (ART) containing tenofovir disoproxil fumarate (TDF) and didanosine (ddI) has been associated with poor immune recovery despite virologic success. This effect might be related to ddI toxicity since ddI exposure is substantially increased by TDF. OBJECTIVE: To analyze whether immune recovery during ART with TDF and ddI is ddI-dose dependent. DESIGN AND METHODS: A retrospective longitudinal analysis of immune recovery measured by the CD4 T-cell slope in 614 patients treated with ART containing TDF with or without ddI. Patients were stratified according to the tertiles of their weight-adjusted ddI dose: low dose (< 3.3 mg/kg), intermediate dose (3.3-4.1 mg/kg) and high dose (> 4.1 mg/kg). Cofactors modifying the degree of immune recovery after starting TDF-containing ART were identified by univariable and multivariable linear regression analyses. RESULTS: CD4 T-cell slopes were comparable between patients treated with TDF and a weight-adjusted ddI-dose of < 4.1 mg/kg per day (n = 143) versus TDF-without-ddI (n = 393). In the multivariable model the slopes differed by -13 CD4 T cells/mul per year [95% confidence interval (CI), -42 to 17; P = 0.40]. In contrast, patients treated with TDF and a higher ddI dose (> 4.1 mg/kg per day, n = 78) experienced a significantly impaired immune recovery (-47 CD4 T cells/microl per year; 95% CI, -82 to -12; P = 0.009). The virologic response was comparable between the different treatment groups. CONCLUSIONS: Immune recovery is impaired, when high doses of ddI (> 4.1 mg/kg) are given in combination with TDF. If the dose of ddI is adjusted to less than 4.1 mg/kg per day, immune recovery is similar to other TDF-containing ART regimen.

Reverse immunology approach for the identification of CD8 T-cell-defined antigens: advantages and hurdles.

One of the challenges of tumour immunology remains the identification of strongly immunogenic tumour antigens for vaccination. Reverse immunology, that is, the procedure to predict and identify immunogenic peptides from the sequence of a gene product of interest, has been postulated to be a particularly efficient, high-throughput approach for tumour antigen discovery. Over one decade after this concept was born, we discuss the reverse immunology approach in terms of costs and efficacy: data mining with bioinformatic algorithms, molecular methods to identify tumour-specific transcripts, prediction and determination of proteasomal cleavage sites, peptide-binding prediction to HLA molecules and experimental validation, assessment of the in vitro and in vivo immunogenic potential of selected peptide antigens, isolation of specific cytolytic T lymphocyte clones and final validation in functional assays of tumour cell recognition. We conclude that the overall low sensitivity and yield of every prediction step often requires a compensatory up-scaling of the initial number of candidate sequences to be screened, rendering reverse immunology an unexpectedly complex approach.

Cancers du sein : comment associer l'hormonothérapie et la radiothérapie en situation adjuvante [How to combine hormonotherapy and radiation treatment in adjuvant breast cancer?]

Combined radiation and hormone therapies have become common clinical practice in recent years for locally-advanced prostate cancers. The use of such concomitant therapy in the treatment of breast disease has been infrequently reported in the literature, but seems justified given the common hormonal dependence of breast cancer and the potential synergistic effect of these two treatment modalities. As adjuvant therapy, two strategies are used in daily clinical practice: upfront aromatase inhibitors or sequentially after a variable delay of tamoxifen. These molecules may, thus, interact with radiotherapy. Retrospectives studies recently published did not show any differences in terms of locoregional recurrences between concurrent or sequential radiohormonotherapy. Lung and skin fibroses due to concurrent treatment are still under debate. Nevertheless, late side effects appeared to be increased by such a treatment, particularly in hypersensitive patients identified at risk by the lymphocyte predictive test. Concurrent radiohormonotherapy should, thus, be delivered cautiously at least for these patients. This article details the potent advantages and risks of concurrent use of adjuvant hormonotherapy and radiotherapy in localized breast cancers.

Selective inhibition of CTL activation by a dipalmitoyl-phospholipid that prevents the recruitment of signaling molecules to lipid rafts.

Antigen-specific T-cell activation implicates a redistribution of plasma membrane-bound molecules in lipid rafts, such as the coreceptors CD8 and CD4, the Src kinases Lek and Fyn, and the linker for activation of T cells (LAT), that results in the formation of signaling complexes. These molecules partition in lipid rafts because of palmitoylation of cytoplasmic, membrane proximal cysteines, which is essential for their functional integrity in T-cell activation. Here, we show that exogenous dipalmitoyl-phosphatidylethanolamine (DPPE), but not the related unsaturated dioleoyl-phosphatidylethanolamine (DOPE), partitions in lipid rafts. DPPE inhibits activation of CD8(+) T lymphocytes by sensitized syngeneic antigen-presenting cells or specific major histocompatibility complex (MHC) peptide tetramers, as indicated by esterase release and intracellular calcium mobilization. Cytotoxic, T lymphocyte (CTL)-target cell conjugate formation is not affected by DPPE, indicating that engagement of the T-cell receptor by its cognate ligand is intact in lipid-treated cells. In contrast to other agents known to block raft-dependent signaling, DPPE efficiently inhibits the MHC peptide-induced recruitment of palmitoylated signaling molecules to lipid rafts and CTL activation without affecting cell viability or lipid raft integrity.

Modalities and future prospects of gene therapy in heart transplantation.

Heart transplantation is the treatment of choice for many patients with end-stage heart failure. Its success, however, is limited by organ shortage, side effects of immunosuppressive drugs, and chronic rejection. Gene therapy is conceptually appealing for applications in transplantation, as the donor organ is genetically manipulated ex vivo before transplantation. Localised expression of immunomodulatory genes aims to create a state of immune privilege within the graft, which could eliminate the need for systemic immunosuppression. In this review, recent advances in the development of gene therapy in heart transplantation are discussed. Studies in animal models have demonstrated that genetic modification of the donor heart with immunomodulatory genes attenuates ischaemia-reperfusion injury and rejection. Alternatively, bone marrow-derived cells genetically engineered with donor-type major histocompatibility complex (MHC) class I or II promote donor-specific hyporesponsiveness. Genetic engineering of naïve T cells or dendritic cells may induce regulatory T cells and regulatory dendritic cells. Despite encouraging results in animal models, however, clinical gene therapy trials in heart transplantation have not yet been started. The best vector and gene to be delivered remain to be identified. Pre-clinical studies in non-human primates are needed. Nonetheless, the potential of gene therapy as an adjunct therapy in transplantation is essentially intact.

Development of a T Cell Receptor Targeting an HLA-A*0201 Restricted Epitope from the Cancer-Testis Antigen SSX2 for Adoptive Immunotherapy of Cancer.

The clinical success of adoptive immunotherapy of cancer relies on the selection of target antigens that are highly expressed in tumor cells but absent in essential normal tissues. A group of genes that encode the cancer/testis or cancer germline antigens have been proposed as ideal targets for immunotherapy due to their high expression in multiple cancer types and their restricted expression in immunoprivileged normal tissues. In the present work we report the isolation and characterization of human T cell receptors (TCRs) with specificity for synovial sarcoma X breakpoint 2 (SSX2), a cancer/testis antigen expressed in melanoma, prostate cancer, lymphoma, multiple myeloma and pancreatic cancer, among other tumors. We isolated seven HLA-A2 restricted T cell receptors from natural T cell clones derived from tumor-infiltrated lymph nodes of two SSX2-seropositive melanoma patients, and selected four TCRs for cloning into retroviral vectors. Peripheral blood lymphocytes (PBL) transduced with three of four SSX2 TCRs showed SSX241-49 (KASEKIFYV) peptide specific reactivity, tumor cell recognition and tetramer binding. One of these, TCR-5, exhibited tetramer binding in both CD4 and CD8 cells and was selected for further studies. Antigen-specific and HLA-A*0201-restricted interferon-γ release, cell lysis and lymphocyte proliferation was observed following culture of TCR engineered human PBL with relevant tumor cell lines. Codon optimization was found to increase TCR-5 expression in transduced T cells, and this construct has been selected for development of clinical grade viral vector producing cells. The tumor-specific pattern of expression of SSX2, along with the potent and selective activity of TCR-5, makes this TCR an attractive candidate for potential TCR gene therapy to treat multiple cancer histologies.

Genetically resistant mice lacking interleukin-12 are susceptible to infection with Leishmania major and mount a polarized Th2 cell response.

Mice with homologous disruption of the gene coding for either the p35 subunit or the p40 subunit of interleukin-12 (IL-12) and derived from a strain genetically resistant to infection with Leishmania major have been used to study further the role of this cytokine in resistance to infection and the differentiation of functional CD4+ T cell subsets in vivo. Wild-type 129/Sv/Ev mice are resistant to infection with L. major showing only small lesions which resolve spontaneously within a few weeks and develop a type 1 CD4+ T cell response. In contrast, mice lacking bioactive IL-12 (IL-12p35-/- and IL-12p40-/-) developed large, progressing lesions. Whereas resistant mice were able to mount a delayed-type hypersensitivity (DTH) response to Leishmania antigen, susceptible BALB/c mice as well as IL-12-deficient 129/Sv/Ev mice did not show any DTH reaction. To characterize the functional phenotype of CD4+ T cells triggered in infected wild-type mice and IL-12-deficient mice, the expression of mRNA for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in purified CD4+ lymph node cells was analyzed. Wild-type 129/Sv/Ev mice showed high levels of mRNA for IFN-gamma and low levels of mRNA for IL-4 which is indicative of a Th1 response. In contrast, IL-12- deficient mice and susceptible BALB/c mice developed a strong Th2 response with high levels of IL-4 mRNA and low levels of IFN-gamma mRNA in CD4+ T cells. Similarly, lymph node cells from infected wild-type 129 mice produced predominantly IFN-gamma in response to stimulation with Leishmania antigen in vitro whereas lymph node cells from IL-12-deficient mice and susceptible BALB/c mice produced preferentially IL-4. Taken together, these results confirm in vivo the importance of IL-12 in induction of Th1 responses and protective immunity against L. major.

Mls: a link between immunology and retrovirology.

The nature of the mysterious minor lymphocyte stimulating (Mls) antigens has recently been clarified. These molecules which were key elements for our current understanding of immune tolerance, have a strong influence on the mouse immune system and are encoded by the open reading frame (orf) of endogenous and exogenous mouse mammary tumor viruses (MMTV's). The knowledge that these antigens are encoded by cancerogenic retroviruses opens an interdisciplinary approach for understanding the mechanisms of immune responses and immune tolerance, retroviral carcinogenesis, and retroviral strategies for infection.

Retrovirus-mediated gene transfer in polyclonal T cells results in lower apoptosis and enhanced ex vivo cell expansion of CMV-reactive CD8 T cells as compared with EBV-reactive CD8 T cells.

To modulate alloreactivity after hematopoietic stem cell transplantation, "suicide" gene-modified donor T cells (GMCs) have been administered with an allogeneic T-cell-depleted marrow graft. We previously demonstrated that such GMCs, generated after CD3 activation, retrovirus-mediated transduction, and G418 selection, had an impaired Epstein-Barr virus (EBV) reactivity, likely to result in an altered control of EBV-induced lymphoproliferative disease. To further characterize the antiviral potential of GMCs, we compared the frequencies of cytomegalovirus (CMV)-specific CD8+ T (CMV-T) cells and EBV-specific CD8+ T (EBV-T) cells within GMCs from CMV- and EBV-double seropositive donors. Unlike anti-EBV responses, the anti-CMV responses were not altered by GMC preparation. During the first days of culture, CMV-T cells exhibited a lower level of CD3-induced apoptosis than did EBV-T cells. In addition, the CMV-T cells escaping initial apoptosis subsequently underwent a higher expansion rate than EBV-T cells. The differential early sensitivity to apoptosis could be in relation to the "recent activation" phenotype of EBV-T cells as evidenced by a higher level of CD69 expression. Furthermore, EBV-T cells were found to have a CD45RA-CD27+CCR7- effector memory phenotype, whereas CMV-T cells had a CD45RA+CD27-CCR7- terminal effector phenotype. Such differences could be contributive, because bulk CD8+CD27- cells had a higher expansion than did bulk CD8+CD27+ cells. Overall, ex vivo T-cell culture differentially affects apoptosis, long-term proliferation, and overall survival of CMV-T and EBV-T cells. Such functional differences need to be taken into account when designing cell and/or gene therapy protocols involving ex vivo T-cell manipulation.

One naive T cell, multiple fates in CD8+ T cell differentiation.

The mechanism by which the immune system produces effector and memory T cells is largely unclear. To allow a large-scale assessment of the development of single naive T cells into different subsets, we have developed a technology that introduces unique genetic tags (barcodes) into naive T cells. By comparing the barcodes present in antigen-specific effector and memory T cell populations in systemic and local infection models, at different anatomical sites, and for TCR-pMHC interactions of different avidities, we demonstrate that under all conditions tested, individual naive T cells yield both effector and memory CD8+ T cell progeny. This indicates that effector and memory fate decisions are not determined by the nature of the priming antigen-presenting cell or the time of T cell priming. Instead, for both low and high avidity T cells, individual naive T cells have multiple fates and can differentiate into effector and memory T cell subsets.

BAFF, a novel ligand of the tumor necrosis factor family, stimulates B cell growth.

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M-stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center-like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function.

Delayed diagnosis of HIV infection and late initiation of antiretroviral therapy in the Swiss HIV Cohort Study.

OBJECTIVES: To investigate delayed HIV diagnosis and late initiation of antiretroviral therapy (ART) in the Swiss HIV Cohort Study. METHODS: Two sub-populations were included: 1915 patients with HIV diagnosis from 1998 to 2007 and within 3 months of cohort registration (group A), and 1730 treatment-naïve patients with CD4>or=200 cells/microL before their second cohort visit (group B). In group A, predictors for low initial CD4 cell counts were examined with a median regression. In group B, we studied predictors for CD4<200 cells/microL without ART despite cohort follow-up. RESULTS: Median initial CD4 cell count in group A was 331 cells/microL; 31% and 10% were <200 and <50 cells/microL, respectively. Risk factors for low CD4 count were age and non-White race. Homosexual transmission, intravenous drug use and living alone were protective. In group B, 30% initiated ART with CD4>or=200 cells/microL; 18% and 2% dropped to CD4 <200 and <50 cells/microL without ART, respectively. Sub-Saharan origin was associated with lower probability of CD4 <200 cells/microL without ART during follow-up. Median CD4 count at ART initiation was 207 and 253 cells/microL in groups A and B, respectively. CONCLUSIONS: CD4<200 cells/microL and, particularly, CD4<50 cells/microL before starting ART are predominantly caused by late presentation. Earlier HIV diagnosis is paramount.

Zymosan induced arthritis in mice is biphasic and acts through the TLR2 pathway

Zymosan induced arthritis is thought to be dependent on activation of the alternative pathway of complement and is short lived. Recently it has been demonstrated that zymosan is capable of activating the innate immune system via toll-like receptor 2 (TLR2) and TLR6. These receptors play a role in linking the innate to the adaptive immune response. We have therefore reinvestigated the mechanisms by which zymosan induces arthritis by analyzing the kinetic of inflammation, the joint histology, lymphocyte proliferation in wild type and TLR2 deficient mice.

When to initiate combined antiretroviral therapy to reduce mortality and AIDS-defining illness in HIV-infected persons in developed countries: an observational study.

BACKGROUND: Most clinical guidelines recommend that AIDS-free, HIV-infected persons with CD4 cell counts below 0.350 × 10(9) cells/L initiate combined antiretroviral therapy (cART), but the optimal CD4 cell count at which cART should be initiated remains a matter of debate. OBJECTIVE: To identify the optimal CD4 cell count at which cART should be initiated. DESIGN: Prospective observational data from the HIV-CAUSAL Collaboration and dynamic marginal structural models were used to compare cART initiation strategies for CD4 thresholds between 0.200 and 0.500 × 10(9) cells/L. SETTING: HIV clinics in Europe and the Veterans Health Administration system in the United States. PATIENTS: 20, 971 HIV-infected, therapy-naive persons with baseline CD4 cell counts at or above 0.500 × 10(9) cells/L and no previous AIDS-defining illnesses, of whom 8392 had a CD4 cell count that decreased into the range of 0.200 to 0.499 × 10(9) cells/L and were included in the analysis. MEASUREMENTS: Hazard ratios and survival proportions for all-cause mortality and a combined end point of AIDS-defining illness or death. RESULTS: Compared with initiating cART at the CD4 cell count threshold of 0.500 × 10(9) cells/L, the mortality hazard ratio was 1.01 (95% CI, 0.84 to 1.22) for the 0.350 threshold and 1.20 (CI, 0.97 to 1.48) for the 0.200 threshold. The corresponding hazard ratios were 1.38 (CI, 1.23 to 1.56) and 1.90 (CI, 1.67 to 2.15), respectively, for the combined end point of AIDS-defining illness or death. Limitations: CD4 cell count at cART initiation was not randomized. Residual confounding may exist. CONCLUSION: Initiation of cART at a threshold CD4 count of 0.500 × 10(9) cells/L increases AIDS-free survival. However, mortality did not vary substantially with the use of CD4 thresholds between 0.300 and 0.500 × 10(9) cells/L.