First-in-Human Study in Healthy Subjects with the Noncytotoxic Monoclonal Antibody OSE-127, a Strict Antagonist of IL-7Rα.

OSE-127 is a humanized mAb targeting the IL-7Rα-chain (CD127), under development for inflammatory and autoimmune disease treatment. It is a strict antagonist of the IL-7R pathway, is not internalized by target cells, and is noncytotoxic. In this work, a first-in-human, phase I, randomized, double-blind, placebo-controlled, single-center study was carried out to determine the safety, pharmacokinetics, pharmacodynamics, and immunogenicity of OSE-127 administration. Sixty-three healthy subjects were randomly assigned to nine groups: six single ascending dose groups with i.v. administration (0.002-10 mg/kg), a single s.c. treatment group (1 mg/kg), and two double i.v. injection groups (6 or 10 mg/kg). Subjects were followed during <146 d. OSE-127's pharmacokinetic half-life after a single dose increased from 4.6 (1 mg/kg) to 11.7 d (10 mg/kg) and, after a second dose, from 12.5 (6 mg/kg) to 16.25 d (10 mg/kg). Receptor occupancy was ≥95% at doses ≥0.02 mg/kg, and this saturation level was maintained >100 d after two i.v. infusions at 10 mg/kg. IL-7 consumption was inhibited by OSE-127 administration, as demonstrated by a decreased IL-7 pathway gene signature in peripheral blood cells and by ex vivo T lymphocyte restimulation experiments. OSE-127 was well tolerated, with no evidence of cytokine-release syndrome and no significant alteration of blood lymphocyte counts or subset populations. Altogether, the observed lack of significant lymphopenia or serious adverse events, concomitant with the dose-dependent inhibition of IL-7 consumption by target cells, highlights that OSE-127 may show clinical activity in IL-7R pathway-involved diseases.

eIF4F is a nexus of resistance to anti-BRAF and anti-MEK cancer therapies.

In BRAF(V600)-mutant tumours, most mechanisms of resistance to drugs that target the BRAF and/or MEK kinases rely on reactivation of the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signal transduction pathway, on activation of the alternative, PI(3)K-AKT-mTOR, pathway (which is ERK independent) or on modulation of the caspase-dependent apoptotic cascade. All three pathways converge to regulate the formation of the eIF4F eukaryotic translation initiation complex, which binds to the 7-methylguanylate cap (m(7)G) at the 5' end of messenger RNA, thereby modulating the translation of specific mRNAs. Here we show that the persistent formation of the eIF4F complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, is associated with resistance to anti-BRAF, anti-MEK and anti-BRAF plus anti-MEK drug combinations in BRAF(V600)-mutant melanoma, colon and thyroid cancer cell lines. Resistance to treatment and maintenance of eIF4F complex formation is associated with one of three mechanisms: reactivation of MAPK signalling, persistent ERK-independent phosphorylation of the inhibitory eIF4E-binding protein 4EBP1 or increased pro-apoptotic BCL-2-modifying factor (BMF)-dependent degradation of eIF4G. The development of an in situ method to detect the eIF4E-eIF4G interactions shows that eIF4F complex formation is decreased in tumours that respond to anti-BRAF therapy and increased in resistant metastases compared to tumours before treatment. Strikingly, inhibiting the eIF4F complex, either by blocking the eIF4E-eIF4G interaction or by targeting eIF4A, synergizes with inhibiting BRAF(V600) to kill the cancer cells. eIF4F not only appears to be an indicator of both innate and acquired resistance but also is a promising therapeutic target. Combinations of drugs targeting BRAF (and/or MEK) and eIF4F may overcome most of the resistance mechanisms arising in BRAF(V600)-mutant cancers.

Evaluation of the efficacy of immunotherapy for non-resectable mucosal melanoma.

BACKGROUND: Immune checkpoint inhibitors are now standard-of-care treatments for metastatic cutaneous melanoma. However, for rare sub-groups, such as mucosal melanomas, few published data are available, and with no established therapeutic guidelines. Our objective was to assess the response to anti-CTLA4 and anti-PD1 immunotherapy in patients with mucosal melanomas. METHODS: We performed a single-center, prospective cohort analysis of patients with non-surgical locally advanced and/or metastatic mucosal melanoma receiving anti-CTLA4 and/or anti-PD1 immunotherapy from 2010 to 2016. RESULTS: Forty-four patients were enrolled, including 18 (40.9%) with head and neck, 12 (27.3%) with vulvo-vaginal and 14 (31.8%) with ano-rectal primary tumours. Eleven (25%) patients had stage 3 disease, and 11 (25%) had distant metastases. The first-line immunotherapy was ipilimumab in 24 patients and pembrolizumab in 20. The objective response rate (ORR) was 8.2% (one complete response) for ipilimumab and 35% (four complete responses) for pembrolizumab. No significant difference was observed for primary tumour location. The median follow-up was 24 months (range 4-73). The median progression-free survival (PFS) in the first-line ipilimumab and pembrolizumab groups was 3 months [95% confidence interval (CI) 2.5-4.6] and 5 months (95% CI 2.6-33.1), respectively (p = 0.0147). CONCLUSION: In the patients with unresectable and/or metastatic mucosal melanoma, we found ORR and PFS rates comparable to those in patients with cutaneous melanoma, with no significant differences in the types of mucosal surfaces involved. Anti-PD1 therapy has a more favorable benefit-risk ratio than ipilimumab and should be used preferentially.

Both HLA-B*57 and plasma HIV RNA levels contribute to the HIV-specific CD8+ T cell response in HIV controllers.

CD8(+) T cell responses are thought to play an important role during HIV infection, particularly in HIV controllers (HIC) in whom viral replication is spontaneously controlled without any treatment. We have demonstrated that CD8(+) T cells from these subjects are able to suppress viral replication in vitro. In parallel, HIV-specific CD8(+) responses were shown to be strong and of high quality, with proliferative abilities and cytotoxic capacities, in HIC. The HLA-B*57 allele, which is associated with a better clinical outcome in HIV infection, is overrepresented in HIC. However, we showed that these patients constitute a heterogeneous group that includes subjects who present weak suppression of viral replication in vitro and HIV-specific responses. We performed an extensive study of 101 HIC (49 HLA-B*57(+) and 52 HLA-B*57(-)) to determine the impact of HLA-B*57 on the HIV-specific CD8(+) response. The HLA-B*57-restricted response displayed better qualitative features, such as higher functional avidity, higher proliferation capacity, and a higher level of cytokine production, than responses not restricted by HLA-B*57. However, the highest frequencies of HIV-specific CD8(+) T cells were observed only in a subset of HLA-B*57(+) subjects. They were tightly associated with the ability to suppress viral replication in vitro. In contrast, the subset of HLA-B*57(+) subjects with a weak ability to suppress viral replication had significantly lower ultrasensitive viral loads than all the other groups of controllers. In conclusion, both HLA-B*57 and the amount of ultrasensitive viral load seem to play a role in HIV-specific CD8(+) T cell responses in HIC.

Post-treatment HIV-1 controllers with a long-term virological remission after the interruption of early initiated antiretroviral therapy ANRS VISCONTI Study.

Combination antiretroviral therapy (cART) reduces HIV-associated morbidities and mortalities but cannot cure the infection. Given the difficulty of eradicating HIV-1, a functional cure for HIV-infected patients appears to be a more reachable short-term goal. We identified 14 HIV patients (post-treatment controllers [PTCs]) whose viremia remained controlled for several years after the interruption of prolonged cART initiated during the primary infection. Most PTCs lacked the protective HLA B alleles that are overrepresented in spontaneous HIV controllers (HICs); instead, they carried risk-associated HLA alleles that were largely absent among the HICs. Accordingly, the PTCs had poorer CD8+ T cell responses and more severe primary infections than the HICs did. Moreover, the incidence of viral control after the interruption of early antiretroviral therapy was higher among the PTCs than has been reported for spontaneous control. Off therapy, the PTCs were able to maintain and, in some cases, further reduce an extremely low viral reservoir. We found that long-lived HIV-infected CD4+ T cells contributed poorly to the total resting HIV reservoir in the PTCs because of a low rate of infection of naïve T cells and a skewed distribution of resting memory CD4+ T cell subsets. Our results show that early and prolonged cART may allow some individuals with a rather unfavorable background to achieve long-term infection control and may have important implications in the search for a functional HIV cure.

Early and long-lasting alteration of effector CD45RA(-)Foxp3(high) regulatory T-cell homeostasis during HIV infection.

Regulatory T-cell (Treg) quantification in human immunodeficiency virus (HIV) infection remains ill defined because of the lack of reliable specific markers to identify human Tregs and the diversity of clinical stages of HIV infection. Using a recently described Treg identification strategy based on CD45RA and Foxp3 expression, we performed an extensive quantification of total, naive (CD45RA(+)Foxp3(low)), and effector (CD45RA(-)Foxp3(high)) Tregs in different contexts of HIV infection: primary HIV infection, long-term viremic patients, aviremic patients treated with highly active antiretroviral therapy, and HIV controllers. We showed that although total Treg percentages were mildly affected by HIV infection, Treg absolute numbers were significantly reduced in all groups studied. We demonstrated that although naive Treg numbers were essentially preserved, effector Tregs were consistently affected during HIV infection. Finally, we demonstrated that effector but not total or naive Treg numbers were negatively correlated with the magnitude of HIV-specific CD8 T-cell responses.

ChemR23 activation reprograms macrophages toward a less inflammatory phenotype and dampens carcinoma progression.

Introduction: Tumor Associated Macrophages (TAM) are a major component of the tumor environment and their accumulation often correlates with poor prognosis by contributing to local inflammation, inhibition of anti-tumor immune response and resistance to anticancer treatments. In this study, we thus investigated the anti-cancer therapeutic interest to target ChemR23, a receptor of the resolution of inflammation expressed by macrophages, using an agonist monoclonal antibody, αChemR23. Methods: Human GM-CSF, M-CSF and Tumor Associated Macrophage (TAM)-like macrophages were obtained by incubation of monocytes from healthy donors with GM-CSF, M-CSF or tumor cell supernatants (Breast cancer (BC) or malignant pleural mesothelioma (MPM) cells). The effects of αChemR23 on macrophages were studied at the transcriptomic, protein and functional level. Datasets from The Cancer Genome Atlas (TCGA) were used to study CMKLR1 expression, coding for ChemR23, in BC and MPM tumors. In vivo, αChemR23 was evaluated on overall survival, metastasis development and transcriptomic modification of the metastatic niche using a model of resected triple negative breast cancer. Results: We show that ChemR23 is expressed at higher levels in M-CSF and tumor cell supernatant differentiated macrophages (TAM-like) than in GM-CSF-differentiated macrophages. ChemR23 activation triggered by αChemR23 deeply modulates M-CSF and TAM-like macrophages including profile of cell surface markers, cytokine secretion, gene mRNA expression and immune functions. The expression of ChemR23 coding gene (CMKLR1) strongly correlates to TAM markers in human BC tumors and MPM and its histological detection in these tumors mainly corresponds to TAM expression. In vivo, treatment with αChemR23 agonist increased mouse survival and decreased metastasis occurrence in a model of triple-negative BC in correlation with modulation of TAM phenotype in the metastatic niche. Conclusion: These results open an attractive opportunity to target TAM and the resolution of inflammation pathways through ChemR23 to circumvent TAM pro-tumoral effects.

A PD-1/PD-L1 Proximity Assay as a Theranostic Marker for PD-1 Blockade in Patients with Metastatic Melanoma.

PURPOSE: Less than 50% of patients with melanoma respond to anti-programmed cell death protein 1 (anti-PD-1), and this treatment can induce severe toxicity. Predictive markers are thus needed to improve the benefit/risk ratio of immune checkpoint inhibitors (ICI). Baseline tumor parameters such as programmed death ligand 1 (PD-L1) expression, CD8+ T-cell infiltration, mutational burden, and various transcriptomic signatures are associated with response to ICI, but their predictive values are not sufficient. Interaction between PD-1 and its main ligand, PD-L1, appears as a valuable target of anti-PD-1 therapy. Thus, instead of looking at PD-L1 expression only, we evaluated the predictive value of the proximity between PD-1 and its neighboring PD-L1 molecules in terms of response to anti-PD-1 therapy. EXPERIMENTAL DESIGN: PD-1/PD-L1 proximity was assessed by proximity ligation assay (PLA) on 137 samples from two cohorts (exploratory n = 66 and validation n = 71) of samples from patients with melanoma treated with anti-PD-1±anti-CTLA-4. Additional predictive biomarkers, such as PD-L1 expression (MELscore), CD8+ cells density, and NanoString RNA signature, were also evaluated. RESULTS: A PD-1/PD-L1 PLA model was developed to predict tumor response in an exploratory cohort and further evaluated in an independent validation cohort. This score showed higher predictive ability (AUC = 0.85 and 0.79 in the two cohorts, respectively) for PD-1/PD-L1 PLA as compared with other parameters (AUC = 0.71-0.77). Progression-free and overall survival were significantly longer in patients with high PLA values (P = 0.00019 and P < 0.0001, respectively). CONCLUSIONS: The proximity between PD-1 and PD-L1, easily assessed by this PLA on one formalin-fixed paraffin-embedded section, appears as a new biomarker of anti-PD-1 efficacy.

Tumor-associated high endothelial venules mediate lymphocyte entry into tumors and predict response to PD-1 plus CTLA-4 combination immunotherapy.

Recruitment of lymphocytes into tumors is critical for anti-tumor immunity and efficacious immunotherapy. We show in murine models that tumor-associated high endothelial venules (TA-HEVs) are major sites of lymphocyte entry into tumors at baseline and upon treatment with anti-PD-1/anti-CTLA-4 immune checkpoint blockade (ICB). TA-HEV endothelial cells (TA-HECs) derive from post-capillary venules, co-express MECA-79+ HEV sialomucins and E/P-selectins, and are associated with homing and infiltration into tumors of various T cell subsets. Intravital microscopy further shows that TA-HEVs are the main sites of lymphocyte arrest and extravasation into ICB-treated tumors. Increasing TA-HEC frequency and maturation increases the proportion of tumor-infiltrating stem-like CD8+ T cells, and ameliorates ICB efficacy. Analysis of tumor biopsies from 93 patients with metastatic melanoma reveals that TA-HEVs are predictive of better response and survival upon treatment with anti-PD-1/anti-CTLA-4 combination. These studies provide critical insights into the mechanisms governing lymphocyte trafficking in cancer immunity and immunotherapy.

CLEC-1 is a death sensor that limits antigen cross-presentation by dendritic cells and represents a target for cancer immunotherapy.

Tumors exploit numerous immune checkpoints, including those deployed by myeloid cells to curtail antitumor immunity. Here, we show that the C-type lectin receptor CLEC-1 expressed by myeloid cells senses dead cells killed by programmed necrosis. Moreover, we identified Tripartite Motif Containing 21 (TRIM21) as an endogenous ligand overexpressed in various cancers. We observed that the combination of CLEC-1 blockade with chemotherapy prolonged mouse survival in tumor models. Loss of CLEC-1 reduced the accumulation of immunosuppressive myeloid cells in tumors and invigorated the activation state of dendritic cells (DCs), thereby increasing T cell responses. Mechanistically, we found that the absence of CLEC-1 increased the cross-presentation of dead cell-associated antigens by conventional type-1 DCs. We identified antihuman CLEC-1 antagonist antibodies able to enhance antitumor immunity in CLEC-1 humanized mice. Together, our results demonstrate that CLEC-1 acts as an immune checkpoint in myeloid cells and support CLEC-1 as a novel target for cancer immunotherapy.

Neuropilin-1 cooperates with PD-1 in CD8+ T cells predicting outcomes in melanoma patients treated with anti-PD1.

Targeting immune checkpoints, such as Programmed cell Death 1 (PD1), has improved survival in cancer patients by restoring antitumor immune responses. Most patients, however, relapse or are refractory to immune checkpoint blocking therapies. Neuropilin-1 (NRP1) is a transmembrane glycoprotein required for nervous system and angiogenesis embryonic development, also expressed in immune cells. We hypothesized that NRP1 could be an immune checkpoint co-receptor modulating CD8+ T cells activity in the context of the antitumor immune response. Here, we show that NRP1 is recruited in the cytolytic synapse of PD1+CD8+ T cells, cooperates and enhances PD-1 activity. In mice, CD8+ T cells specific deletion of Nrp1 improves anti-PD1 antibody antitumor immune responses. Likewise, in human metastatic melanoma, the expression of NRP1 in tumor infiltrating CD8+ T cells predicts poor outcome of patients treated with anti-PD1. NRP1 is a promising target to overcome resistance to anti-PD1 therapies.

Increased CD127 expression on activated FOXP3+CD4+ regulatory T cells.

Regulatory T cells (Treg) are commonly identified by CD25 (IL-2R alpha) surface expression and/or intracellular expression of the FOXP3 transcription factor. In addition, Treg are also characterized by low CD127 (IL-7R alpha) expression when compared to conventional T cells and their biology in the periphery is considered essentially independent of IL-7. We further investigated CD127 expression on Treg and we demonstrated differential CD127 expression depending on Treg subsets considered. Notably, we observed high CD127 expression on inducible costimulatory molecule (ICOS)- and CD103-expressing Treg subsets. Since these two markers reflect activation status, we addressed whether Treg activation modulated CD127 expression. We demonstrated that in contrast to conventional T cells, Treg significantly upregulated CD127 expression during in vitro and in vivo activation using adoptive transfer and contact dermatitis models. High CD127 expression on Treg was also predominantly detected ex vivo in some specific sites, notably bone marrow and skin. Importantly, higher CD127 expression on Treg correlated with higher phosphorylation of STAT5 upon IL-7 exposure. High CD127 expression on Treg also provided survival advantage upon in vitro incubation with IL-7. We thus demonstrated that low CD127 expression is not an intrinsic characteristic of Treg and we identified activated Treg as a potential target of endogenous or therapeutic IL-7.

Identification of a particular HIV-specific CD8+ T-cell subset with a CD27+ CD45RO-/RA+ phenotype and memory characteristics after initiation of HAART during acute primary HIV infection.

CD8(+) T cells play an important role in controlling viral infections. Defective CD8(+) T-cell responses during HIV infection could contribute to viral persistence. Early initiation of highly active antiretroviral therapy during acute primary HIV infection helps to preserve HIV-specific immune responses. Here, we describe a particular CD27(+) CD45RO(-)/RA(+) HIV-specific CD8(+) T cell in participants treated early during the primary infection. These cells, which were present at a very low frequency during primary HIV infection, increased markedly after early treatment, whereas their frequency remained unchanged in untreated participants and in participants treated later. These nonnaive antigen-experienced cells are in a resting state and have characteristics of long-lived memory cells. They also possess direct effector capabilities, such as cytokine production, and are able to proliferate and to acquire cytotoxic functions on reactivation. Our results suggest that these HIV-specific CD27(+) CD45RO(-)/RA(+) CD8(+) T cells, observed when early viral replication is inhibited, form a pool of resting cells with memory characteristics.

In situ detection of the eIF4F translation initiation complex in mammalian cells and tissues.

The eukaryotic translation initiation complex eIF4F plays an important role in gene expression. The methods that are used to monitor the formation of the eIF4F complex are usually indirect and provide no information on its subcellular localization. This protocol describes a proximity ligation assay-based procedure allowing the direct in situ visualization of the eIF4F complex, as well as its absolute quantification per cell using adapted image analysis software. For complete details on the use and execution of this protocol, please refer to Boussemart et al. (2014).

Selective SIRPα blockade reverses tumor T cell exclusion and overcomes cancer immunotherapy resistance.

T cell exclusion causes resistance to cancer immunotherapies via immune checkpoint blockade (ICB). Myeloid cells contribute to resistance by expressing signal regulatory protein-α (SIRPα), an inhibitory membrane receptor that interacts with ubiquitous receptor CD47 to control macrophage phagocytosis in the tumor microenvironment. Although CD47/SIRPα-targeting drugs have been assessed in preclinical models, the therapeutic benefit of selectively blocking SIRPα, and not SIRPγ/CD47, in humans remains unknown. We report a potent synergy between selective SIRPα blockade and ICB in increasing memory T cell responses and reverting exclusion in syngeneic and orthotopic tumor models. Selective SIRPα blockade stimulated tumor nest T cell recruitment by restoring murine and human macrophage chemokine secretion and increased anti-tumor T cell responses by promoting tumor-antigen crosspresentation by dendritic cells. However, nonselective SIRPα/SIRPγ blockade targeting CD47 impaired human T cell activation, proliferation, and endothelial transmigration. Selective SIRPα inhibition opens an attractive avenue to overcoming ICB resistance in patients with elevated myeloid cell infiltration in solid tumors.

Translational control of tumor immune escape via the eIF4F-STAT1-PD-L1 axis in melanoma.

Preventing the immune escape of tumor cells by blocking inhibitory checkpoints, such as the interaction between programmed death ligand-1 (PD-L1) and programmed death-1 (PD-1) receptor, is a powerful anticancer approach. However, many patients do not respond to checkpoint blockade. Tumor PD-L1 expression is a potential efficacy biomarker, but the complex mechanisms underlying its regulation are not completely understood. Here, we show that the eukaryotic translation initiation complex, eIF4F, which binds the 5' cap of mRNAs, regulates the surface expression of interferon-γ-induced PD-L1 on cancer cells by regulating translation of the mRNA encoding the signal transducer and activator of transcription 1 (STAT1) transcription factor. eIF4F complex formation correlates with response to immunotherapy in human melanoma. Pharmacological inhibition of eIF4A, the RNA helicase component of eIF4F, elicits powerful antitumor immune-mediated effects via PD-L1 downregulation. Thus, eIF4A inhibitors, in development as anticancer drugs, may also act as cancer immunotherapies.

Synergistic effects of eIF4A and MEK inhibitors on proliferation of NRAS-mutant melanoma cell lines.

Activating mutations of the NRAS (neuroblastoma rat sarcoma viral oncogene) protein kinase, present in many cancers, induce a constitutive activation of both the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signal transduction pathway and the PI(3)K-AKT-mTOR, pathway. This in turn regulates the formation of the eIF4F eukaryotic translation initiation complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, which binds to the 7-methylguanylate cap (m(7)G) at the 5' end of messenger RNAs. Small molecules targeting MEK (MEKi: MEK inhibitors) have demonstrated activity in NRAS-mutant cell lines and tumors, but resistance sets in most cases within months of treatment. Using proximity ligation assays, that allows visualization of the binding of eIF4E to the scaffold protein eIF4G, generating the active eIF4F complex, we have found that resistance to MEKi is associated with the persistent formation of the eIF4F complex in MEKi-treated NRAS-mutant cell lines. Furthermore, inhibiting the eIF4A component of the eIF4F complex, with a small molecule of the flavagline/rocaglate family, synergizes with inhibiting MEK to kill NRAS-mutant cancer cell lines.

Secondary Tumors Arising in Patients Undergoing BRAF Inhibitor Therapy Exhibit Increased BRAF-CRAF Heterodimerization.

BRAF inhibitors (BRAFi) elicit therapeutic responses in metastatic melanoma, but alarmingly, also induce the formation of secondary benign and malignant skin tumors. Here, we report the emergence and molecular characterization of 73 skin and extracutaneous tumors in 31 patients who underwent BRAFi therapy. The majority of patients presented with classic epidermal tumors such as verrucous papillomas, keratoacanthomas, and squamous cell carcinomas (SCC). However, 15 patients exhibited new or rapidly progressing tumors distinct from these classic subtypes, such as lymph node metastasis, new melanomas, and genital and oral mucosal SCCs. Genotyping of the tumors revealed that oncogenic RAS mutations were found in 58% of the evaluable tumor samples (38/66) and 49% of the control tumors from patients not treated with BRAFi (30/62). Notably, proximity ligation assays demonstrated that BRAF-CRAF heterodimerization was increased in fixed tumor samples from BRAFi-treated patients compared with untreated patients. Our findings reveal that BRAF-CRAF complex formation is significantly associated with BRAFi treatment, and may therefore serve as a useful biomarker of BRAFi-induced cutaneous and extracutaneous tumor formation.

Potential role for HIV-specific CD38-/HLA-DR+ CD8+ T cells in viral suppression and cytotoxicity in HIV controllers.

BACKGROUND: HIV controllers (HIC) are rare HIV-1-infected patients who exhibit spontaneous viral control. HIC have high frequency of CD38-/HLA-DR+ HIV-specific CD8+ T cells. Here we examined the role of this subset in HIC status. MATERIALS AND METHODS: We compared CD38-/HLA-DR+ CD8+ T cells with the classical CD38+/HLA-DR+ activated phenotype in terms of 1) their activation status, reflected by CD69, CD25, CD71, CD40 and Ki67 expression, 2) functional parameters: Bcl-2 expression, proliferative capacity, and IFN-γ and IL-2 production, and 3) cytotoxic activity. We also investigated how this particular profile is generated. RESULTS: Compared to CD38+/HLA-DR+ cells, CD38-/HLA-DR+ cells exhibited lower expression of several activation markers, better survival capacity (Bcl-2 MFI, 367 [134-462] vs 638 [307-747], P = 0.001), higher frequency of polyfunctional cells (15% [7%-33%] vs 21% [16%-43%], P = 0.0003), greater proliferative capacity (0-fold [0-2] vs 3-fold [2]-[11], P = 0.007), and higher cytotoxicity in vitro (7% [3%-11%] vs 13% [6%-22%], P = 0.02). The CD38-/HLA-DR+ profile was preferentially generated in response to low viral antigen concentrations. CONCLUSIONS: These data highlight the role of CD38-/HLA-DR+ HIV-specific CD8+ T cell cytotoxicity in HIC status and provide insights into the mechanism by which they are generated. Induction of this protective CD8+ subset may be important for vaccine strategies.

NKG2D expression on HIV-specific CD8+ T cells is reduced in viremic HIV-1-infected patients but maintained in HIV controllers.

NKG2D mediates an important costimulatory pathway in CD8 T cells. In HIV infection, the authors found that NKG2D expression on both total CD8 and HIV-specific CD8 T cells was significantly lower in viremic patients than in HIV controllers. Antiretroviral therapy partially restored NKG2D expression on HIV-specific CD8 T cells. The authors observed a negative correlation between the respective expression levels of CD38 and NKG2D on total CD8 and HIV-specific CD8 T cells. The maintenance of NKG2D expression on CD8 T cells in HIV controllers may contribute to better cell function.