Unconventional T-cell Research Articles

Influence of Aerosol Delivered BCG Vaccination on Immunological and Disease Parameters Following SARS-CoV-2 Challenge in Rhesus Macaques.

The tuberculosis vaccine, Bacille Calmette-Guerin (BCG), also affords protection against non-tuberculous diseases attributable to heterologous immune mechanisms such as trained innate immunity, activation of non-conventional T-cells, and cross-reactive adaptive immunity. Aerosol vaccine delivery can target immune responses toward the primary site of infection for a respiratory pathogen. Therefore, we hypothesised that aerosol delivery of BCG would enhance cross-protective action against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and be a deployable intervention against coronavirus disease 2019 (COVID-19). Immune parameters were monitored in vaccinated and unvaccinated rhesus macaques for 28 days following aerosol BCG vaccination. High-dose SARS-CoV-2 challenge was applied by intranasal and intrabronchial instillation and animals culled 6–8 days later for assessment of viral, disease, and immunological parameters. Mycobacteria-specific cell-mediated immune responses were detected following aerosol BCG vaccination, but SARS-CoV-2-specific cellular- and antibody-mediated immunity was only measured following challenge. Early secretion of cytokine and chemokine markers associated with the innate cellular and adaptive antiviral immune response was detected following SARS-CoV-2 challenge in vaccinated animals, at concentrations that exceeded titres measured in unvaccinated macaques. Classical CD14+ monocytes and Vδ2 γδ T-cells quantified by whole-blood immunophenotyping increased rapidly in vaccinated animals following SARS-CoV-2 challenge, indicating a priming of innate immune cells and non-conventional T-cell populations. However, viral RNA quantified in nasal and pharyngeal swabs, bronchoalveolar lavage (BAL), and tissue samples collected at necropsy was equivalent in vaccinated and unvaccinated animals, and in-life CT imaging and histopathology scoring applied to pulmonary tissue sections indicated that the disease induced by SARS-CoV-2 challenge was comparable between vaccinated and unvaccinated groups. Hence, aerosol BCG vaccination did not induce, or enhance the induction of, SARS-CoV-2 cross-reactive adaptive cellular or humoral immunity, although an influence of BCG vaccination on the subsequent immune response to SARS-CoV-2 challenge was apparent in immune signatures indicative of trained innate immune mechanisms and primed unconventional T-cell populations. Nevertheless, aerosol BCG vaccination did not enhance the initial clearance of virus, nor reduce the occurrence of early disease pathology after high dose SARS-CoV-2 challenge. However, the heterologous immune mechanisms primed by BCG vaccination could contribute to the moderation of COVID-19 disease severity in more susceptible species following natural infection.

Imprint of unconventional T-cell response in acute hepatitis C persists despite successful early antiviral treatment.

Unconventional T cells (UTCs) are a heterogeneous group of T cells that typically exhibit rapid responses toward specific antigens from pathogens. Chronic hepatitis C virus (HCV) infection causes dysfunction of several subsets of UTCs. This altered phenotype and function of UTCs can persist over time even after direct-acting antiviral (DAA)-mediated clearance of chronic HCV. However, it is less clear if and how UTCs respond in acute, symptomatic HCV infection, a rare clinical condition, and if rapid DAA treatment of such patients reverses the caused perturbations within UTCs. Here, we comprehensively analyzed the phenotype and reinvigoration capacity of three major UTC populations, mucosal-associated invariant T (MAIT) cells, γδ T cells, and CD4 and CD8 double-negative αβ T cells (DNT cells) before, during, and after DAA-mediated clearance of acute symptomatic HCV infection. Furthermore, MAIT cell functionality was systematically studied. We observed a reduced frequency of MAIT cells. However, remaining cells presented with a near-to-normal phenotype in acute infection, which contrasted with a significant dysfunction upon stimulation that was not restored after viral clearance. Notably, DNT and γδ T cells displayed a strong activation ex-vivo in acute HCV infection, which subsequently normalized during the treatment. In addition, DNT cell activation was specifically associated with liver inflammation and inflammatory cytokines. Altogether, these data provide evidence that UTCs respond in a cell type-specific manner during symptomatic HCV infection. However, even if early treatment is initiated, long-lasting imprints within UTCs remain over time.

Abstract 1535: Allogenic CAR iNKT as a cell therapy platform targeting tumor antigen Isomesothelin

Abstract Effective chimeric antigen receptor (CAR) T-cell therapy targeting B-cell malignancies has paved the way for alternate strategies targeting cancer. Current active research is directed towards development of safe, allogeneic off the shelf cell (OTS) therapy products. This could be potentially a step forward in the targeted cancer immunotherapy field. Invariant NKT cells (iNKT) are deemed as one of the unconventional T-cell populations with semi invariantly re-arranged TCR. They recognize lipid antigens Via CD1d, an MHC Class 1 like molecule. Recognition of CD1d expressed on various hematopoietic cells is important for targeted tumor specific iNKT cytotoxicity in various leukemia, lymphoma malignancies. Through the recent years, CAR-iNKT adoptive cell therapy has drawn excitement and interest because of their intrinsic anti-tumor property. More specifically CAR-iNKTs have been shown to target solid tumors such as neuroblastoma in preclinical studies and proceeded to phase 1 clinical trials. The innate ability of iNKT cells to kill tumor cells and also cause very less GVHD provides an extremely attractive platform for developing OTS product. Allogeneic CAR iNKT cells have been less explored for cancer immunotherapy. Although the relative percentage of iNKTs are very low in peripheral blood (~0.01% of T-lymphocytes), we report an efficient method of enrichment and expanding a large and pure population of iNKTs and genetically modify them for targeting solid tumor antigens such as Isomesothelin (IsoMSLN), an alternative splice variant of mesothelin. Many pre-clinical studies have been assessed targeting mesothelin, a tumor associated antigen overexpressed in malignant cells. A safe allogenic CAR targeted therapy for IsoMSLN has yet to be demonstrated. iNKTs expanded and transduced with our novel protocol targeting IsoMSLN, are highly cytotoxic and suggests a central memory phenotype that could potentially persist longer in vivo. Citation Format: Anupama Gopisetty, Yibin Chen, Quynh Nguyen, Maurizio Chiriva-Internati. Allogenic CAR iNKT as a cell therapy platform targeting tumor antigen Isomesothelin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1535.

Human skin mucosal associated invariant T (MAIT) cells show increased pro-inflammatory cytokine expression following burn trauma

Abstract The role of T cells in burn trauma is an understudied research area explored primarily in mice, with sparse data in humans. Patients surviving an initial burn injury are at a high risk of infection, sepsis, and death. Unconventional T-cells such as mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes that respond rapidly to pathogens. Circulating MAIT cells are primarily interferon (IFN)-gamma and tumor necrosis factor (TNF) producing when presented with a microbial-derived ligand on MHC class-1 related protein (MR1) or activated by cytokines interleukin (IL)-12 & IL-18. In this study, we obtained discarded burn (n=6) and normal (from discarded autograft, n=4) skin tissue from burn patients and compared unconventional T cell functionality by flow cytometry and single-cell RNA-sequencing (scRNA-seq). We did not find any significant differences between the frequency of total MAIT cells between burn injury or normal skin, 1.51 ± 1.42 and 2.98 ± 4.40, respectively. There is a significant higher level of CD38 expression in MAIT cells from burn injury tissue and a significant higher level of CD69 expression in MAIT cells from normal skin tissue. Skin MAIT cells in a burn injury show significantly higher levels of IFN-g and TNF before and after PMA-ionomycin stimulation compared to normal skin MAIT cells, which mainly produce IL-6 & IL-17A, suggesting that skin MAIT cells of burn patients show a MAIT cell phenotype that is more responsive to infection. We are characterizing these MAIT cell subtypes in further detail with scRNA-seq and anticipate presentation of that data at time of the conference. Our findings provide the means towards an understanding of the role that skin MAIT cells play in skin of patients with burn trauma.

Does exercise attenuate age- and disease-associated dysfunction in unconventional T cells? Shining a light on overlooked cells in exercise immunology.

Unconventional T Cells (UTCs) are a unique population of immune cells that links innate and adaptive immunity. Following activation, UTCs contribute to a host of immunological activities, rapidly responding to microbial and viral infections and playing key roles in tumor suppression. Aging and chronic disease both have been shown to adversely affect UTC numbers and function, with increased inflammation, change in body composition, and physical inactivity potentially contributing to the decline. One possibility to augment circulating UTCs is through increased physical activity. Acute exercise is a potent stimulus leading to the mobilization of immune cells while the benefits of exercise training may include anti-inflammatory effects, reductions in fat mass, and improved fitness. We provide an overview of age-related changes in UTCs, along with chronic diseases that are associated with altered UTC number and function. We summarize how UTCs respond to acute exercise and exercise training and discuss potential mechanisms that may lead to improved frequency and function.

Phenotypical and Functional Characterization of Cytotoxic Unconventional T-Cells.

During the last two decades, the immunology field has been focused on the study of conventional T-cells, leading to important advances in identification of specific subsets involved in promoting and suppressing immune response in patients with cancer, autoimmune disease or transplanted patients. In these recent years, the research on unconventional subset of CD4-CD8- double-negative T-cells is growing. DNTs are a unique subset of T-cells characterized by being CD4-CD8-CD3+ and express either ß or α T-cell receptors (TCR). In this chapter, we describe the methods used to phenotypically characterize and isolate these cells in order to study their functional profile.

Development of a 43 color panel for the characterization of conventional and unconventional T-cell subsets, B cells, NK cells, monocytes, dendritic cells, and innate lymphoid cells using spectral flow cytometry.

Although many flow cytometers can analyze 30-50 parameters, it is still challenging to develop a 40+ color panel for the phenotyping of immune cells using fluorochrome conjugated antibodies due to limitations in the availability of spectrally unique fluorochromes that can be excited by the commonly used laser lines (UV, Violet, Blue, Green/Yellow-green, and Red). Spectral flowcytometry is capable of differentiating fluorochromes with significant overlap in the emission spectra, enabling the use of spectrally similar fluorochrome pairs such as Brilliant Blue 515 and FITC in a single panel. We have developed a 43 color panel to characterize most of the immune subsets within the peripheral immune system, including conventional T cells, unconventional T cells such as invariant natural killer T cells (iNKT), Gamma delta (γδ) T-cell subsets (TCR Vδ2, TCR Vγ9) and mucosal-associated invariant T cells (MAIT), B-cell subsets, natural killer (NK) cells, plasmacytoid dendritic cells, dendritic cell subsets, hematopoietic progenitor cells, basophils, and innate lymphoid cell (ILC) subsets (CD117, CRTH2). The panel includes surface markers to analyze activation (CD38, HLA-DR, ICOS/CD278), differentiation (CD45RA, CD27, CD28, CD57), expression of cytokine and chemokine receptors (CD25, CD127, CCR10, CCR6, CCR4, CXCR3, CXCR5, CRTH2/CD294), and co-inhibitory molecules and exhaustion (PD-1, CD223/LAG-3, TIGIT), which enables a deep characterization of PBMCs from peripheral blood. Cells were analyzed on a 5-laser Cytek Aurora and data analysis was done using FlowJo. This panel can help to make a thorough interpretation of immune system, specifically when specimen quantity is low. The panel has not been completely optimized but would rather act as a guide toward the development of a workflow for optimized multicolor immunophenotyping panel.

Age-Dependent Differences in T-Cell Responses to Influenza A Virus

Respiratory infections from influenza A virus (IAV) cause substantial morbidity and mortality in children relative to adults. T cells play a critical role in the host response to IAV by supporting the innate and humoral responses, mediating cytotoxic activity, and promoting recovery. There are age-dependent differences in the number, subsets, and localization of T cells, which impact the host response to pathogens. In this article, we first review how T cells recognize IAV and examine differences in the resting T-cell populations between juveniles and adults. Next, we describe how the juvenile CD4+, CD8+, and regulatory T-cell responses compare with those in adults and discuss the potential physiologic and clinical consequences of the differences. Finally, we explore the roles of two unconventional T-cell types in the juvenile response to influenza, natural-killer T cells and γδ T cells. A clear understanding of age-dependent differences in the T-cell response is essential to developing therapies to prevent or reverse the deleterious effects of IAV in children.

Unbiased Profiling Reveals Compartmentalization of Unconventional T-Cells Within the Intestinal Mucosa Irrespective of HIV Infection.

The intestinal mucosa is enriched for unconventional T-cells, including mucosal associated invariant T-cells (MAIT), invariant natural killer T-cells (iNKT) and γδ T-cells. These cells are activated by bacterial metabolites, lipid antigens and cytokines, and are important for intestinal barrier integrity. The loss of gut homeostasis observed in HIV infection is central to disease pathogenesis, and studies have highlighted impairment of particular unconventional T-cell subsets within a specific gut compartment. However, although the small and large intestine are distinct niches, the overall impact of HIV on unconventional T-cells across the gut mucosal has not been well-studied. We hypothesized that compartment specific differences in the unconventional T-cell repertoire would exist between the small and large intestine, due to increasing bacterial loads and microbial diversity; and that the impact of HIV infection might differ depending on the compartment examined. We used mass cytometry, flow cytometry and unbiased T-cell receptor profiling to quantify unconventional T-cells in blood and tissue from the small (duodenum) and large (colon) intestine in HIV infected and uninfected participants undergoing examination for a range of intestinal conditions. Overall, we find distinct compartmentalisation of T-cells between blood, duodenum and colon, with iNKT cells significantly enriched in the duodenum and δ-1 expressing γδ T-cells in the colon. In addition, we observe greater clonal expansion of conventional TCRs in the duodenum, suggestive of stronger adaptive immunity in this compartment. Conversely, we find evidence of an expanded unconventional TCR repertoire in the colon, which contained far more overlapping “donor unrestricted” sequences than the duodenum. Twelve of these TCRs were highly “MAIT-like” and 3 were unique to the colon, suggesting an enrichment of donor unrestricted T-cells (DURTs) in this compartment. Unexpectedly, however, no significant impact of HIV infection on any of the unconventional T-cell subsets measured was observed in either mucosal site in terms of frequency or TCR repertoire. Further studies are required to investigate the importance of these unconventional T-cell subsets to intestinal homeostasis within the different gut compartments and determine if they are functionally impaired during HIV infection.

Untangling iNKT Cell Function in Adipose Tissue Homeostasis

iNKT cells are important regulatory cells in metabolic health and disease. In this issue of Cell Metabolism, LaMarche etal. (2020) clarify the origin and heterogeneity of these unconventional Tcells and identify the specific signals in adipose tissues that direct their function.

Immunological effects of nivolumab immunotherapy in patients with oral cavity squamous cell carcinoma

BackgroundAlthough checkpoint blockades have become widely used, the immunological impact in cancer patients, especially those with oral cavity squamous cell carcinoma (OCSCC), has not been well studied.MethodsThe present study assessed the immunological impact of anti-PD-1 (nivolumab) treatment in 10 patients with OCSCC. This involved phenotypic analyses of peripheral blood T-cell subpopulations and their expression of immune mediators prior to and following nivolumab treatment. The focus was on immunological effects of treatment without regard to possible clinical responses.ResultsNivolumab caused a decline in the frequency of blood CD4+ cells but did not affect their expression of IFN-γ. However, nivolumab increased the proportion of CD4+ cells expressing the Treg-supporting factor Foxp3. Nivolumab treatment caused an increase in the proportion of CD8+ cells. While their expression of granzyme B increased, it did not attain significance. Analyses of CD8+ cell subpopulations showed nivolumab caused an increase in levels of unconventional CD8dimCD3+ T-cells. It also caused an increase in expression of granzyme B by these unconventional T-cells as well as by the conventional CD8hiCD3+ cells. The CD8hiCD3+ subpopulation also had a near-significant increase in IFN-γ expression. Treatment with nivolumab had no effect on the levels of the NK containing CD8dimCD3− subpopulation of cells or their expression of IFN-γ or granzyme B.ConclusionsThese results show nivolumab causes opposing effects on CD4+ and CD8+ cell populations, with CD4+ cell levels declining but increasing the proportion of Treg cells, and unconventional CD8+ T-cell levels increasing with increased expression of immune mediators by CD8+ T-cell subpopulations.

DOP70 High-dimensional analysis reveals a novel signature for IL-17 producing CD8 T cells in inflammatory bowel disease

Abstract Background The pathogenesis of IBD has previously mainly been associated with a dysregulation of CD4 T-cell responses, and active disease is linked to induction of pathogenic IL-17 producing T helper cells. Importantly, CD8 T cells can also produce IL-17 and demonstrate a significant increase in active IBD. However, it remains unclear whether this is due to conventional or unconventional T-cell responses and whether these CD8 responses could play a role as novel biomarkers or therapeutic targets of active IBD. Methods We isolated lymphocytes from the peripheral blood and intestinal tissue of IBD patients (n = 56) and performed a detailed analysis of CD8 T-cell phenotype and function using high-parametric flow cytometry and mass cytometry in combination with algorithm-aided bioinformatic analysis. Results We observe a significant increase in IL-17 production by CD8 T cells in active IBD, primarily produced by conventional CD8 T cells. Unconventional T-cell subsets (e.g. MAIT cells, γδ T cells and NKT cells) represented only ~30% (peripheral blood) or ~25% (intestinal tissue) of IL-17 producing CD8 T cells (Tc17). The mass cytometric analysis identified Tc17 cells as a distinct cell population within the intestinal CD8 T-cell compartment that can be further subdivided into 3 subsets which share expression of phenotypic markers such as CD6, CD39, CD69 and PD1 and a low expression of CD27. This novel signature was validated in a separate cohort of IBD patients. Moreover, at initial IBD diagnosis, the IL-17 signature is associated with flare-free survival in a retrospective cohort analysis based on published transcriptome data. Conclusion Our data indicate that conventional IL-17 producing CD8 T cells are a very distinct cell population that is linked to IBD activity. The identification of a novel IL-17 CD8 signature may help guide treatment decisions as a biomarker and for immunotherapeutic approaches.

Promising Cytomegalovirus-Based Vaccine Vector Induces Robust CD8+ T-Cell Response.

Vaccination has had great success in combating diseases, especially infectious diseases. However, traditional vaccination strategies are ineffective for several life-threatening diseases, including acquired immunodeficiency syndrome (AIDS), tuberculosis, malaria, and cancer. Viral vaccine vectors represent a promising strategy because they can efficiently deliver foreign genes and enhance antigen presentation in vivo. However, several limitations, including pre-existing immunity and packaging capacity, block the application of viral vectors. Cytomegalovirus (CMV) has been demonstrated as a new type of viral vector with additional advantages. CMV could systematically elicit and maintain high frequencies of effector memory T cells through the “memory inflation” mechanism. Studies have shown that CMV can be genetically modified to induce distinct patterns of CD8+ T-cell responses, while some unconventional CD8+ T-cell responses are rarely induced through conventional vaccine strategies. CMV has been used as a vaccine vector to deliver many disease-specific antigens, and the efficacy of these vaccines was tested in different animal models. Promising results demonstrated that the robust and unconventional T-cell responses elicited by the CMV-based vaccine vector are essential to control these diseases. These accumulated data and evidence strongly suggest that a CMV-based vaccine vector represents a promising approach to develop novel prophylactic and therapeutic vaccines against some epidemic pathogens and tumors.

Pneumonies sévères et syndrome de détresse respiratoire aiguë : implication des lymphocytes T non conventionnels

Pneumonia is frequently complicated by occurrence of acute respiratory distress syndrome (ARDS), consequently to dysregulated inflammatory response. However, mechanisms driving this dysregulation are poorly understood. To address this, "unconventional T-cells (UTC)" -γδT, NKT and MAIT cells- appear to be relevant targets due to their key role in orchestrating anti-microbial immune response in the lung. Thus, using an experimental and translational approach, we test the hypothesis that a tight regulation of UTC is mandatory to fine-tune host response, and, subsequently to prevent emergence of an aberrant response leading to excessive tissue damages, and eventually, ARDS.

Casting a wider net: Immunosurveillance by nonclassical MHC molecules.

Most studies of T lymphocytes focus on recognition of classical major histocompatibility complex (MHC) class I or II molecules presenting oligopeptides, yet there are numerous variations and exceptions of biological significance based on recognition of a wide variety of nonclassical MHC molecules. These include αβ and γδ T cells that recognize different class Ib molecules (CD1, MR-1, HLA-E, G, F, et al.) that are nearly monomorphic within a given species. Collectively, these T cells can be considered “unconventional,” in part because they recognize lipids, metabolites, and modified peptides. Unlike classical MHC-specific cells, unconventional T cells generally exhibit limited T-cell antigen receptor (TCR) repertoires and often produce innate immune cell-like rapid effector responses. Exploiting this system in new generation vaccines for human immunodeficiency virus (HIV), tuberculosis (TB), other infectious agents, and cancer was the focus of a recent workshop, “Immune Surveillance by Non-classical MHC Molecules: Improving Diversity for Antigens,” sponsored by the National Institute of Allergy and Infectious Diseases. Here, we summarize salient points presented regarding the basic immunobiology of unconventional T cells, recent advances in methodologies to measure unconventional T-cell activity in diseases, and approaches to harness their considerable clinical potential.

Abstract PR16: Mucosal-associated invariant T-cells respond to the cutaneous microbiota and promote skin immunity

Abstract Infectious agents are estimated to cause approximately 18% of cancers worldwide, supporting a link between microbial products and carcinogenesis. The diverse array of commensal microorganisms that reside at barrier sites of the human body, collectively termed the microbiome, provide the primary source of constitutive microbial stimulation and promote immune homeostasis through their release of microbial products, including derivatives of vitamin synthesis. Mucosal-associated invariant T (MAIT) cells are unconventional T-cells that recognize microbial-derived metabolites and provide an initial defense to pathogens through their rapid production of type-1 or type-17 cytokines. While MAIT-cells have been shown to infiltrate colorectal tumors, it remains to be determined how MAIT-cells contribute to tumorigenesis and whether commensals regulate MAIT-cell function. Here we show that MAIT-cells are a substantial skin-resident population capable of producing IL-17A. IL-23 signaling promotes the accumulation of cutaneous MAIT-cells and skin commensals induce local MAIT-cell proliferation and IL-1-dependent IL-17A production. In the absence of commensals, MAIT-cells are dramatically decreased, indicating that the microbiota is necessary for the development of this population. Utilizing MAIT-cell-deficient mice, we demonstrate that cutaneous MAIT-cells promote wound healing and inhibit the colonization of pathogens. This work identifies MAIT-cells as the only cell population that is entirely dependent on the microbiota and reveals the mechanism by which these cells respond to the commensal microbial community. Since IL-17A promotes tumor vascularization and neutrophil recruitment, the high frequency of MAIT-cells in human skin suggests that modulation of the skin-resident bacteria may have clinical applications for the progression of melanoma, and current studies are exploring this possibility using the B16 melanoma model in mice.This work was supported by the NIH Intramural Research Program. MGC is a Cancer Research Institute Irvington Fellow supported by the Cancer Research Institute. Citation Format: Michael G. Constantinides, Samira Tamoutounour, Jonathan L. Linehan, Shurjo Sen, Jahangheer Shaik, Sobhan Roy, Erin J. Adams, Yasmine Belkaid. Mucosal-associated invariant T-cells respond to the cutaneous microbiota and promote skin immunity [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr PR16.

Unconventional T cells in chronic hepatitis B patients on long-term suppressive therapy with tenofovir followed by a Peg-IFN add-on strategy: A randomized study.

HBV eradication in chronic hepatitis B (CHB) subjects is rarely achieved with either nucleos(t)ide analogues (NA) or pegylated interferon (Peg-IFN), which both have a limited effect in restoring immune responses. Thirty CHB subjects on long-term treatment with tenofovir (TDF) and HBV suppression were enrolled and randomized 1:2 to either receive Peg-IFN-α-2a add-on therapy or continue TDF alone. We studied γδ T and iNKT frequency and function (by flow cytometry) at baseline, at 12weeks and 12weeks after the end of treatment. A higher reduction in qHBsAg occurred in the add-on group compared with the NA group at W12 (P=.016) and at W24 (P=.012). A decline of qHBsAg ≥0.5 log10 at week 24 occurred in 4 of 10 patients in the add-on arm and 1 of 20 in the NA arm, respectively (P=.03). HBsAg loss was seen in 20% of subjects in the add-on group and in none of the NA group. Compared to HBV negative, CHB on TDF showed lower frequency of iNKT (P=.03) and γδ T cells (P=.03) as well as fewer γδ T cells expressing Vδ2 T-cell receptors (P=.005). No changes in unconventional T-cell frequency and function were shown in both add-on and NA patients nor were differences detected between the two treatment groups. We report persistent impairment of unconventional T cells in CHB. Despite a greater qHBsAg decline of add-on patients, our data failed to detect any effect of Peg-IFN treatment on unconventional T cells.

New Genome-Wide Algorithm Identifies Novel In-Vivo Expressed Mycobacterium Tuberculosis Antigens Inducing Human T-Cell Responses with Classical and Unconventional Cytokine Profiles.

New strategies are needed to develop better tools to control TB, including identification of novel antigens for vaccination. Such Mtb antigens must be expressed during Mtb infection in the major target organ, the lung, and must be capable of eliciting human immune responses. Using genome-wide transcriptomics of Mtb infected lungs we developed data sets and methods to identify IVE-TB (in-vivo expressed Mtb) antigens expressed in the lung. Quantitative expression analysis of 2,068 Mtb genes from the predicted first operons identified the most upregulated IVE-TB genes during in-vivo pulmonary infection. By further analysing high-level conservation among whole-genome sequenced Mtb-complex strains (n = 219) and algorithms predicting HLA-class-Ia and II presented epitopes, we selected the most promising IVE-TB candidate antigens. Several of these were recognized by T-cells from in-vitro Mtb-PPD and ESAT6/CFP10-positive donors by proliferation and multi-cytokine production. This was validated in an independent cohort of latently Mtb-infected individuals. Significant T-cell responses were observed in the absence of IFN-γ-production. Collectively, the results underscore the power of our novel antigen discovery approach in identifying Mtb antigens, including those that induce unconventional T-cell responses, which may provide important novel tools for TB vaccination and biomarker profiling. Our generic approach is applicable to other infectious diseases.

CCR6 Is Required for Epidermal Trafficking of γδ-T Cells in an IL-23-Induced Model of Psoriasiform Dermatitis

A subset of CCR6+, γδ-low (GDL) T cells that express Th17 cytokines in mouse skin participates in IL-23-induced psoriasisform dermatitis. We use CCR6-deficient (KO) and wildtype (WT) mice to analyze skin trafficking patterns of GDL T cells and function-blocking mAbs to determine the role of CCR6 in IL-23-mediated dermatitis. Herein, CCL20 was highly upregulated in IL-23-injected WT mouse ear skin as early as 24 hours after initial treatment, and large numbers of CCR6+ cells were observed in the epidermis of IL-23-injected WT mice. Anti-CCL20 mAbs reduced psoriasiform dermatitis and blocked recruitment of GDL T cells to the epidermis. In CCR6 KO mice, GDL T cells failed to accumulate in the epidermis after IL-23 treatment, but total numbers of GDL T cells in the dermis of WT and CCR6 KO mice were equivalent. There was a ~70% reduction in the proportion of IL-22+ GDL T cells in the dermis of CCR6 KO mice (vs. WT mice), suggesting that effector function as well as epidermal recruitment of GDL T cells are impaired in CCR6-deficient mice. Thus, these data show CCR6 regulates epidermal trafficking of γδ T cell subsets in skin and suggest the potential of CCR6 as a therapeutic target for psoriasis.

Role of Hedgehog signalling at the transition from double‐positive to single‐positive thymocyte

In the thymus, developing T cells receive signals that determine lineage choice, specificity, MHC restriction and tolerance to self-antigen. One way in which thymocytes receive instruction is by secretion of Sonic hedgehog (Shh) from thymic epithelial cells. We have previously shown that Hedgehog (Hh) signalling in the thymus decreases the CD4:CD8 single-positive (SP) thymocyte ratio. Here, we present data indicating that double-positive (DP) thymocytes are Hh-responsive and that thymocyte-intrinsic Hh signalling plays a role in modulating the production of CD4+ (SP4), CD8+ (SP8) and unconventional T-cell subsets. Repression of physiological Hh signalling in thymocytes altered the proportions of DP and SP4 cells. Thymocyte-intrinsic Hh-dependent transcription also attenuated both the production of mature SP4 and SP8 cells, and the establishment of peripheral T-cell compartments in TCR-transgenic mice. Additionally, stimulation or withdrawal of Hh signals in the WT foetal thymus impaired or enhanced upregulation of the CD4 lineage-specific transcription factor Gata3 respectively. These data together suggest that Hh signalling may play a role in influencing the later stages of thymocyte development.