Cécile Alanio

PD-1–Expressing Tumor-Infiltrating T Cells Are a Favorable Prognostic Biomarker in HPV-Associated Head and Neck Cancer

Head and neck cancers positive for human papillomavirus (HPV) have a more favorable clinical outcome than HPV-negative cancers, but it is unknown why this is the case. We hypothesized that prognosis was affected by intrinsic features of HPV-infected tumor cells or differences in host immune response. In this study, we focused on a comparison of regulatory Foxp3(+) T cells and programmed death-1 (PD-1)(+) T cells in the microenvironment of tumors that were positive or negative for HPV, in two groups that were matched for various clinical and biologic parameters. HPV-positive head and neck cancers were more heavily infiltrated by regulatory T cells and PD-1(+) T cells and the levels of PD-1(+) cells were positively correlated with a favorable clinical outcome. In explaining this paradoxical result, we showed that these PD-1(+) T cells expressed activation markers and were functional after blockade of the PD-1-PD-L1 axis in vitro. Approximately 50% of PD-1(+) tumor-infiltrating T cells lacked Tim-3 expression and may indeed represent activated T cells. In mice, administration of a cancer vaccine increased PD-1 on T cells with concomitant tumor regression. In this setting, PD-1 blockade synergized with vaccine in eliciting antitumor efficacy. Our findings prompt a need to revisit the significance of PD-1-infiltrating T cells in cancer, where we suggest that PD-1 detection may reflect a previous immune response against tumors that might be reactivated by PD-1/PD-L1 blockade.

Enumeration of human antigen-specific naive CD8 T cells reveals conserved precursor frequencies

The number of antigen-specific naive CD8(+) T cells is believed to be important in the shaping of adaptive immune responses, and is predictive for the magnitude of priming responses in mouse models. Because of extremely low precursor frequencies, knowledge about these cells comes from indirect techniques and estimations. Here, we present a strategy based on the combination of tetramer staining, magnetic-bead enrichment, and multiparametric cytometry, which permitted direct detection and analysis of CD8(+) T cells reactive for 6 different naive epitopes (MART-1(26-35), HIV-1 Gag p17(77-85), hepatitis C virus [HCV] NS3(1406-1415), HCV Core(132-140), NY-ESO-1(157-165), and cytomegalovirus [CMV] pp65(495-503)). Interestingly, we detected higher than 100-fold differences in precursor frequency across these epitopes (from 0.6 x 10(-6) to 1.3 x 10(-4)), but conserved frequencies among humans. Development of a procedure for direct assessment of T-cell precursor frequency in humans has important implications, with particular relevance to vaccine development and monitoring of tumor and self-reactive T cells.

The Milieu Intérieur study — An integrative approach for study of human immunological variance ☆

The Milieu Intérieur Consortium has established a 1000-person healthy population-based study (stratified according to sex and age), creating an unparalleled opportunity for assessing the determinants of human immunologic variance. Herein, we define the criteria utilized for participant enrollment, and highlight the key data that were collected for correlative studies. In this report, we analyzed biological correlates of sex, age, smoking-habits, metabolic score and CMV infection. We characterized and identified unique risk factors among healthy donors, as compared to studies that have focused on the general population or disease cohorts. Finally, we highlight sex-bias in the thresholds used for metabolic score determination and recommend a deeper examination of current guidelines. In sum, our clinical design, standardized sample collection strategies, and epidemiological data analyses have established the foundation for defining variability within human immune responses.

Bystander hyperactivation of preimmune CD8+ T cells in chronic HCV patients

Chronic infection perturbs immune homeostasis. While prior studies have reported dysregulation of effector and memory cells, little is known about the effects on naïve T cell populations. We performed a cross-sectional study of chronic hepatitis C (cHCV) patients using tetramer-associated magnetic enrichment to study antigen-specific inexperienced CD8+ T cells (i.e., tumor or unrelated virus-specific populations in tumor-free and sero-negative individuals). cHCV showed normal precursor frequencies, but increased proportions of memory-phenotype inexperienced cells, as compared to healthy donors or cured HCV patients. These observations could be explained by low surface expression of CD5, a negative regulator of TCR signaling. Accordingly, we demonstrated TCR hyperactivation and generation of potent CD8+ T cell responses from the altered T cell repertoire of cHCV patients. In sum, we provide the first evidence that naïve CD8+ T cells are dysregulated during cHCV infection, and establish a new mechanism of immune perturbation secondary to chronic infection. DOI: http://dx.doi.org/10.7554/eLife.07916.001

Natural variation in the parameters of innate immune cells is preferentially driven by genetic factors

The quantification and characterization of circulating immune cells provide key indicators of human health and disease. To identify the relative effects of environmental and genetic factors on variation in the parameters of innate and adaptive immune cells in homeostatic conditions, we combined standardized flow cytometry of blood leukocytes and genome-wide DNA genotyping of 1,000 healthy, unrelated people of Western European ancestry. We found that smoking, together with age, sex and latent infection with cytomegalovirus, were the main non-genetic factors that affected variation in parameters of human immune cells. Genome-wide association studies of 166 immunophenotypes identified 15 loci that showed enrichment for disease-associated variants. Finally, we demonstrated that the parameters of innate cells were more strongly controlled by genetic variation than were those of adaptive cells, which were driven by mainly environmental exposure. Our data establish a resource that will generate new hypotheses in immunology and highlight the role of innate immunity in susceptibility to common autoimmune diseases.Both environmental factors and genetic factors influence human immunity. Albert and colleagues leverage data from the Milieu Intérieur Consortium to comprehensively describe the effects of lifestyle, environment and genetics on human innate and adaptive immunity.

Hepatitis E virus-induced primary cutaneous CD30(+) T cell lymphoproliferative disorder

BACKGROUND & AIM Several types of unexplained extra-hepatic manifestations, including haematological disorders, have been reported in the context of hepatitis E virus (HEV) infection. However, the underlying mechanism(s) of these manifestations are unknown. We provide evidence that HEV has an extra-hepatic endothelial tropism that can engage cutaneous T cells towards clonality. METHODS A patient with a CD30(+) cutaneous T cell lymphoproliferative disorder (T-LPD) and biopsy-proven chronic HEV infection received three rounds of oral ribavirin treatment, administered either without or with interferon, and eventually achieved a sustained virologic response (SVR). Pathologic, virologic and immunologic investigations were carried out on biopsied skin lesion, and peripheral blood mononuclear cells between the 2nd and 3rd round of antiviral treatment and biopsied liver. RESULTS Remission of T-LPD was observed upon antiviral treatment, and the patient remained in complete remission after achieving SVR. The T cell analysis showed large CD30(+) lymphocytes surrounding the blood vessels within the CD8(+) T cell infiltrate. HEV was detected within dermal microvascular endothelial cells using immunofluorescence staining, in situ hybridisation and electron microscopy. Infiltrating T cells mostly comprised memory CD8(+) T cells with a tissue-resident memory T cell phenotype. Overall, 98% of extracted T cells were CD8(+) T cells with aVβ signature skewed towards Vβ4 and with an oligoclonal profile. T cell clones from T-LPD were more like T cells in the liver than T cells in the blood [odds ratio=4.55, (3.70-5.60), p<0.0001]. No somatic mutations were found in the T-LPD exomes. CONCLUSION HEV has an extra-hepatic tissue tropism in humans, including dermal endothelium, and can induce CD30(+) T-LPD that is sensitive to antivirals. LAY SUMMARY Hepatitis E virus (HEV) has an extra-hepatic tissue tropism and should be added to the list of viruses associated with lymphoproliferative disorders. As such, HEV should be part of the laboratory workup of any lymphoproliferation, particularly those of the T cell phenotype that involve the skin. In the context of HEV-associated cutaneous T cell lymphoproliferative disorders, antiviral treatment could be considered a first-line treatment instead of chemotherapy.

Human genetic variants and age are the strongest predictors of humoral immune responses to common pathogens and vaccines

BackgroundHumoral immune responses to infectious agents or vaccination vary substantially among individuals, and many of the factors responsible for this variability remain to be defined. Current evidence suggests that human genetic variation influences (i) serum immunoglobulin levels, (ii) seroconversion rates, and (iii) intensity of antigen-specific immune responses. Here, we evaluated the impact of intrinsic (age and sex), environmental, and genetic factors on the variability of humoral response to common pathogens and vaccines.MethodsWe characterized the serological response to 15 antigens from common human pathogens or vaccines, in an age- and sex-stratified cohort of 1000 healthy individuals (Milieu Intérieur cohort). Using clinical-grade serological assays, we measured total IgA, IgE, IgG, and IgM levels, as well as qualitative (serostatus) and quantitative IgG responses to cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1 and 2, varicella zoster virus, Helicobacter pylori, Toxoplasma gondii, influenza A virus, measles, mumps, rubella, and hepatitis B virus. Following genome-wide genotyping of single nucleotide polymorphisms and imputation, we examined associations between ~ 5 million genetic variants and antibody responses using single marker and gene burden tests.ResultsWe identified age and sex as important determinants of humoral immunity, with older individuals and women having higher rates of seropositivity for most antigens. Genome-wide association studies revealed significant associations between variants in the human leukocyte antigen (HLA) class II region on chromosome 6 and anti-EBV and anti-rubella IgG levels. We used HLA imputation to fine map these associations to amino acid variants in the peptide-binding groove of HLA-DRβ1 and HLA-DPβ1, respectively. We also observed significant associations for total IgA levels with two loci on chromosome 2 and with specific KIR-HLA combinations.ConclusionsUsing extensive serological testing and genome-wide association analyses in a well-characterized cohort of healthy individuals, we demonstrated that age, sex, and specific human genetic variants contribute to inter-individual variability in humoral immunity. By highlighting genes and pathways implicated in the normal antibody response to frequently encountered antigens, these findings provide a basis to better understand disease pathogenesis.Trials registrationClinicalTrials.gov, NCT01699893

CXCR3/CXCL10 Axis Shapes Tissue Distribution of Memory Phenotype CD8+ T Cells in Nonimmunized Mice

The preimmune repertoire consists of mature T lymphocytes that have not yet been stimulated in the periphery. Memory phenotype (MP) cells have been reported as part of the preimmune repertoire (i.e., T cells bearing memory markers despite lack of engagement with cognate Ag); however, little is known about their trafficking and function. In this study, we hypothesized that MP cells, naive to TCR stimulation, constitute a transient population that traffics to tissues during development. Using mutant and transgenic animals with a monospecific TCR, we discovered increased numbers of MP CD8+ T cells circulating in nonimmunized Cxcr3−/− and Cxcl10−/− mice compared with wild-type animals. Phenotypic differences included decreased numbers of preimmune MP Ag-specific T cells in the skin and thymus and a distinct pattern of activation upon TCR engagement. Our results show for the first time, to our knowledge, an important role for CXCR3 and CXCL10 in the tissue distribution of preimmune MP cells.

Tracking Antigen-Specific CD8 + T Cells Using MHC Class I Multimers

The tracking of epitope-specific T cells is a useful approach for the study of adaptive immune responses. This protocol describes how Major Histocompatibility Complex Class I (MHC-I) multimers can be used to stain, enrich, and enumerate (rare) populations of CD8(+) T cells specific for a given antigen. It provides the detailed steps for multimer labeling, magnetic enrichment, and cytometric analysis. Additionally, it provides informations for multiplexing experiments in order to achieve simultaneous detection of multiple antigenic specificities, and strategies for coupling the protocol with functional assays (e.g., intracellular cytokine staining). Future developments in cytometric systems (e.g., mass spectroscopy-based cytometry) and gene expression studies (e.g., single cell PCR) will extend these approaches and provide an unprecedented assessment of the immune repertoire.

Baseline sensitivity of T cells to alpha-IFN correlates with sustained virological response to IFN-based triple therapy in HCV infection

Chronic infection with HCV is a public health problem with approximately 170 million people infected worldwide. Interferon alpha (IFNα) sensitivity in liver and IL28B genotype has been identified as important determinants of HCV clearance in the setting of pegylated interferon/ribavirin treatment. Herein, we explored IFNα sensitivity in PBMC from 21 healthy donors and 21 HCV‐infected patients treated with pegylated interferon/ribavirin and HCV nonstructural protein‐3 inhibitors (i.e. telaprevir/boceprevir). We explored phospho‐STAT1 level as read‐out for IFN signalling pathway activation in PBMC, T cells and monocytes and correlated results with virological response. We found that PBMC from healthy donors are desensitized to IFNα after priming and challenged with IFNα, with a subsequent decrease of phospho‐STAT1 and interferon‐stimulated genes. Furthermore, we show that CD3+ T cells, but not monocytes, become desensitized after 4 weeks of treatment, with a significant decrease of phospho‐STAT1 after ex vivo IFNα stimulation. Finally, we identified baseline phospho‐STAT1 level in CD3+ T cells as a potential biomarker of sustained virological response, regardless of the IL28B genotype. In the upcoming costly era of IFN‐sparing regimen, baseline IFNα sensitivity could act as biomarker to define cost‐effectiveness strategies of treatment by identifying patients who will or will not respond to IFN‐based treatments.