The inhibitory receptor BTLA controls γδ T cell homeostasis and inflammatory responses

Identification of Diagnostic Genes of Aortic Stenosis That Progresses from Aortic Valve Sclerosis

Background

Aortic valve sclerosis (AVS) is a pathological state that can progress to aortic stenosis (AS), which is a high-mortality valvular disease. However, effective medical therapies are not available to prevent this progression. This study aimed to explore potential biomarkers of AVS-AS advancement.

Methods

A microarray dataset and an RNA-sequencing dataset were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened from AS and AVS samples. Functional enrichment analysis, protein-protein interaction (PPI) network construction, and machine learning model construction were conducted to identify diagnostic genes. A receiver operating characteristic (ROC) curve was generated to evaluate diagnostic value. Immune cell infiltration was then used to analyze differences in immune cell proportion between tissues. Finally, immunohistochemistry was applied to further verify protein concentration of diagnostic factors.

Results

A total of 330 DEGs were identified, including 92 downregulated and 238 upregulated genes. The top 5% of DEGs (n = 17) were screened following construction of a PPI network. IL-7 and VCAM-1 were identified as the most significant candidate genes via least absolute shrinkage and selection operator (LASSO) regression. The diagnostic value of the model and each gene were above 0.75. Proportion of anti-inflammatory M2 macrophages was lower, but the fraction of pro-inflammatory gamma-delta T cells was elevated in AS samples. Finally, levels of IL-7 and VCAM-1 were validated to be higher in AS tissue than in AVS tissue using immunohistochemistry.

Conclusion

IL-7 and VCAM-1 were identified as biomarkers during the disease progression. This is the first study to analyze gene expression differences between AVS and AS and could open novel sights for future studies on alleviating or preventing the disease progression.

BTLA contributes to acute-on-chronic liver failure infection and mortality through CD4+ T-cell exhaustion

B- and T-lymphocyte attenuator (BTLA) levels are increased in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF). This condition is characterized by susceptibility to infection and T-cell immune exhaustion. However, whether BTLA can induce T-cell immune exhaustion and increase the risk of infection remains unclear. Here, we report that BTLA levels are significantly increased in the circulating and intrahepatic CD4+ T cells from patients with HBV-ACLF, and are positively correlated with disease severity, prognosis, and infection complications. BTLA levels were upregulated by the IL-6 and TNF signaling pathways. Antibody crosslinking of BTLA activated the PI3K-Akt pathway to inhibit the activation, proliferation, and cytokine production of CD4+ T cells while promoting their apoptosis. In contrast, BTLA knockdown promoted their activation and proliferation. BTLA-/- ACLF mice exhibited increased cytokine secretion, and reduced mortality and bacterial burden. The administration of a neutralizing anti-BTLA antibody reduced Klebsiella pneumoniae load and mortality in mice with ACLF. These data may help elucidate HBV-ACLF pathogenesis and aid in identifying novel drug targets.

γδ T cells: origin and fate, subsets, diseases and immunotherapy

The intricacy of diseases, shaped by intrinsic processes like immune system exhaustion and hyperactivation, highlights the potential of immune renormalization as a promising strategy in disease treatment. In recent years, our primary focus has centered on γδ T cell-based immunotherapy, particularly pioneering the use of allogeneic Vδ2+ γδ T cells for treating late-stage solid tumors and tuberculosis patients. However, we recognize untapped potential and optimization opportunities to fully harness γδ T cell effector functions in immunotherapy. This review aims to thoroughly examine γδ T cell immunology and its role in diseases. Initially, we elucidate functional differences between γδ T cells and their αβ T cell counterparts. We also provide an overview of major milestones in γδ T cell research since their discovery in 1984. Furthermore, we delve into the intricate biological processes governing their origin, development, fate decisions, and T cell receptor (TCR) rearrangement within the thymus. By examining the mechanisms underlying the anti-tumor functions of distinct γδ T cell subtypes based on γδTCR structure or cytokine release, we emphasize the importance of accurate subtyping in understanding γδ T cell function. We also explore the microenvironment-dependent functions of γδ T cell subsets, particularly in infectious diseases, autoimmune conditions, hematological malignancies, and solid tumors. Finally, we propose future strategies for utilizing allogeneic γδ T cells in tumor immunotherapy. Through this comprehensive review, we aim to provide readers with a holistic understanding of the molecular fundamentals and translational research frontiers of γδ T cells, ultimately contributing to further advancements in harnessing the therapeutic potential of γδ T cells.

BTLA and HVEM: Emerging players in the tumor microenvironment and cancer progression

Immunotherapy has emerged as a revolutionary cancer treatment, particularly with the introduction of immune checkpoint inhibitors (ICIs). ICIs target specific proteins that restrain the immune system from attacking cancer cells. Prominent examples of checkpoint proteins that ICIs block include PD-1, PD-L1, and CTLA-4. The success of PD-1/L1 and CTLA-4 blockade has prompted further research on other inhibitory mechanisms that could aid in the treatment of cancer. One such mechanism is the BTLA/HVEM checkpoint, which regulates immune responses in a similar manner to CTLA-4 and PD-1. BTLA, a member of the Ig superfamily, binds to HVEM, a member of the TNF receptor superfamily. While BTLA is essential for maintaining immunological self-tolerance and preventing autoimmune diseases, overexpression of BTLA and HVEM has been observed in various malignancies such as lung, ovarian, glioblastoma, gastric cancer, and non-Hodgkin's lymphoma. The function of the BTLA/HVEM checkpoint in various malignancies has been extensively studied, revealing its significant role in immunotherapy for cancer. This review study aims to explain the BTLA/HVEM checkpoint and its functions in different types of cancers. In conclusion, the development of new immunotherapies such as ICIs has revolutionized cancer treatment. The discovery of the BTLA/HVEM checkpoint and its role in various malignancies provides opportunities for advancing cancer treatment through immunotherapy.

B- and T-lymphocyte attenuator could be a new player in accelerated atherosclerosis associated with chronic kidney disease

BACKGROUND

In chronic kidney disease (CKD), cardiovascular morbi-mortality is higher than in general population. Atherosclerotic cardiovascular disease is accelerated in CKD, but specific CKD-related risk factors for atherosclerosis are unknown.

METHODS

CKD patients from the NEFRONA study were used. We performed mRNA array from blood of patients free from atheroma plaque at baseline, with (n=10) and without (n=10) de novo atherosclerotic plaque development 2 years later. Selected mRNA candidates were validated in a bigger sample (n=148). Validated candidates were investigated in vivo in an experimental model of CKD-accelerated atherosclerosis, and in vitro in murine macrophages.

RESULTS

mRNA array analysis showed 92 up-regulated and 67 down-regulated mRNAs in samples from CKD patients with de novo plaque development. The functional analysis pointed to a paramount role of the immune response. The validation in a bigger sample confirmed that B- and T-lymphocyte co-inhibitory molecule (BTLA) down-regulation was associated with de novo plaque presence after 2 years. However, BTLA down-regulation was not found to be associated with atherosclerotic progression in patients with plaque already present at baseline. In a model of CKD-accelerated atherosclerosis, mRNA and protein expression levels of BTLA were significantly decreased in blood samples and atheroma plaques. Plaques from animals with CKD were bigger, had more infiltration of inflammatory cells, higher expression of IL6 and IL17 and less presence of collagen than plaques from control animals. Incubation of macrophages with rat uremic serum decreased BTLA expression.

CONCLUSIONS

BTLA could be a potential biomarker or therapeutic target for atherosclerosis incidence in CKD patients.

Epitope topography of agonist antibodies to the checkpoint inhibitory receptor BTLA

B and T lymphocyte attenuator (BTLA) is an attractive target for a new class of therapeutics that attempt to rebalance the immune system by agonizing checkpoint inhibitory receptors (CIRs). Herpesvirus entry mediator (HVEM) binds BTLA in both trans- and cis-orientations. We report here the development and structural characterization of three humanized BTLA agonist antibodies, 22B3, 25F7, and 23C8. We determined the crystal structures of the antibody-BTLA complexes, showing that these antibodies bind distinct and non-overlapping epitopes of BTLA. While all three antibodies activate BTLA, 22B3 mimics HVEM binding to BTLA and shows the strongest agonistic activity in functional cell assays and in an imiquimod-induced mouse model of psoriasis. 22B3 is also capable of modulating HVEM signaling through the BTLA-HVEM cis-interaction. The data obtained from crystal structures, biochemical assays, and functional studies provide a mechanistic model of HVEM and BTLA organization on the cell surface and informed the discovery of a highly active BTLA agonist.

Stimulation of Immune Checkpoint Molecule B and T-Lymphocyte Attenuator Alleviates Experimental Crescentic Glomerulonephritis

SIGNIFICANCE STATEMENT

Treatment of acute, crescentic glomerulonephritis (GN) consists of unspecific and potentially toxic immunosuppression. T cells are central in the pathogenesis of GN, and various checkpoint molecules control their activation. The immune checkpoint molecule B and T-lymphocyte attenuator (BTLA) has shown potential for restraining inflammation in other T-cell-mediated disease models. To investigate its role in GN in a murine model of crescentic nephritis, the authors induced nephrotoxic nephritis in BTLA-deficient mice and wild-type mice. They found that BTLA has a renoprotective role through suppression of local Th1-driven inflammation and expansion of T regulatory cells and that administration of an agonistic anti-BTLA antibody attenuated experimental GN. These findings suggest that antibody-based modulation of BTLA may represent a treatment strategy in human glomerular disease.

BACKGROUND

Modulating T-lymphocytes represents a promising targeted therapeutic option for glomerulonephritis (GN) because these cells mediate damage in various experimental and human GN types. The immune checkpoint molecule B and T-lymphocyte attenuator (BTLA) has shown its potential to restrain inflammation in other T-cell-mediated disease models. Its role in GN, however, has not been investigated.

METHODS

We induced nephrotoxic nephritis (NTN), a mouse model of crescentic GN, in Btla -deficient ( BtlaKO ) mice and wild-type littermate controls and assessed disease severity using functional and histologic parameters at different time points after disease induction. Immunologic changes were comprehensively evaluated by flow cytometry, RNA sequencing, and in vitro assays for dendritic cell and T-cell function. Transfer experiments into Rag1KO mice confirmed the observed in vitro findings. In addition, we evaluated the potential of an agonistic anti-BTLA antibody to treat NTN in vivo .

RESULTS

The BtlaKO mice developed aggravated NTN, driven by an increase of infiltrating renal Th1 cells. Single-cell RNA sequencing showed increased renal T-cell activation and positive regulation of the immune response. Although BTLA-deficient regulatory T cells (Tregs) exhibited preserved suppressive function in vitro and in vivo , BtlaKO T effector cells evaded Treg suppression. Administration of an agonistic anti-BTLA antibody robustly attenuated NTN by suppressing nephritogenic T effector cells and promoting Treg expansion.

CONCLUSIONS

In a model of crescentic GN, BTLA signaling effectively restrained nephritogenic Th1 cells and promoted regulatory T cells. Suppression of T-cell-mediated inflammation by BTLA stimulation may prove relevant for a broad range of conditions involving acute GN.

Prognostic Immune Effector Signature in Adult Acute Lymphoblastic Leukemia Patients Is Dominated by γδ T Cells

The success of immunotherapy has highlighted the critical role of the immune microenvironment in acute lymphoblastic leukemia (ALL); however, the immune landscape in ALL remains incompletely understood and most studies have focused on conventional T cells or NK cells. This study investigated the prognostic impact of circulating γδ T-cell alterations using high-dimensional analysis in a cohort of newly diagnosed adult ALL patients (10 B-ALL; 9 Philadelphia+ ALL; 9 T-ALL). Our analysis revealed common alterations in CD8+ T cells and γδ T cells of relapsed patients, including accumulation of early stage differentiation and increased expression of BTLA and CD73. We demonstrated that the circulating γδ T-cell signature was the most discriminating between relapsed and disease-free groups. In addition, Vδ2 T-cell alterations strongly discriminated patients by relapse status. Taken together, these data highlight the role of ɣδ T cells in adult ALL patients, among whom Vδ2 T cells may be a pivotal contributor to T-cell immunity in ALL. Our findings provide a strong rationale for further monitoring and potentiating Vδ2 T cells in ALL, including in the autologous setting.

Thymic expression of immune checkpoint molecules and their implication for response to immunotherapies

The thymus is responsible for generating a diverse T cell repertoire that is tolerant to self, but capable of responding to various immunologic insults, including cancer. Checkpoint blockade has changed the face of cancer treatment by targeting inhibitory molecules, which are known to regulate peripheral T cell responses. However, these inhibitory molecules and their ligands are expressed during T cell development in the thymus. In this review, we describe the underappreciated role of checkpoint molecule expression during the formation of the T cell repertoire and detail the importance of inhibitory molecules in regulating T cell lineage commitment. Understanding how these molecules function in the thymus may inform therapeutic strategies for better patient outcomes.

PD-1 and TIM-3 differentially regulate subsets of mouse IL-17A-producing γδ T cells

IL-17A-producing γδ T cells in mice consist primarily of Vγ6+ tissue-resident cells and Vγ4+ circulating cells. How these γδ T cell subsets are regulated during homeostasis and cancer remains poorly understood. Using single-cell RNA sequencing and flow cytommetry, we show that lung Vγ4+ and Vγ6+ cells from tumor-free and tumor-bearing mice express contrasting cell surface molecules as well as distinct co-inhibitory molecules, which function to suppress their expansion. Vγ6+ cells express constitutively high levels of PD-1, whereas Vγ4+ cells upregulate TIM-3 in response to tumor-derived IL-1β and IL-23. Inhibition of either PD-1 or TIM-3 in mammary tumor-bearing mice increased Vγ6+ and Vγ4+ cell numbers, respectively. We found that genetic deletion of γδ T cells elicits responsiveness to anti-PD-1 and anti-TIM-3 immunotherapy in a mammary tumor model that is refractory to T cell checkpoint inhibitors, indicating that IL-17A-producing γδ T cells instigate resistance to immunotherapy. Together, these data demonstrate how lung IL-17A-producing γδ T cell subsets are differentially controlled by PD-1 and TIM-3 in steady-state and cancer.

Releasing the restraints of Vγ9Vδ2 T-cells in cancer immunotherapy

Objectives

Vγ9Vδ2 T-cells are a subset of T-cells with a crucial role in immunosurveillance which can be activated and expanded by multiple means to stimulate effector responses. Little is known about the expression of checkpoint molecules on this cell population and whether the ligation of these molecules can regulate their activity. The aim of this study was to assess the expression of both activatory and inhibitory receptors on Vγ9Vδ2 T-cells to assess potential avenues of regulation to target with immunotherapy.

Methods

Expression of various activatory and inhibitory receptors was assessed on Vγ9Vδ2 T-cells by flow cytometry following activation and expansion using zoledronic acid (ZA) and Bacillus Calmette-Guérin (BCG). Expression of these markers and production of effector molecules was also examined following co-culture with various tumour cell targets. The effect of immune checkpoint blockade on Vγ9Vδ2 T-cells was also explored.

Results

Vγ9Vδ2 T-cells expressed high levels of activatory markers both at baseline and following stimulation. Vγ9Vδ2 T-cells expressed variable levels of inhibitory checkpoint receptors with many being upregulated following stimulation. Expression of these markers is further modulated upon co-culture with tumour cells with changes reflecting activation and effector functions. Despite their high expression of inhibitory receptors when cultured with tumour cells expressing cognate ligands there was no effect on Vδ2+ T-cell cytotoxic capacity or cytokine production with immune checkpoint blockade.

Conclusions

Our work suggests the expression of checkpoint receptors present on Vγ9Vδ2 T-cells which may provide a mechanism with the potential to be utilised by tumour cells to subvert Vγ9Vδ2 T-cell cytotoxicity. This work suggests important candidates for blockade by ICI therapy in order to increase the successful use of Vγ9Vδ2 T-cells in immunotherapy.

Btla signaling in conventional and regulatory lymphocytes coordinately tempers humoral immunity in the intestinal mucosa

The Btla inhibitory receptor limits innate and adaptive immune responses, both preventing the development of autoimmune disease and restraining anti-viral and anti-tumor responses. It remains unclear how the functions of Btla in diverse lymphocytes contribute to immunoregulation. Here, we show that Btla inhibits activation of genes regulating metabolism and cytokine signaling, including Il6 and Hif1a, indicating a regulatory role in humoral immunity. Within mucosal Peyer's patches, we find T-cell-expressed Btla-regulated Tfh cells, while Btla in T or B cells regulates GC B cell numbers. Treg-expressed Btla is required for cell-intrinsic Treg homeostasis that subsequently controls GC B cells. Loss of Btla in lymphocytes results in increased IgA bound to intestinal bacteria, correlating with altered microbial homeostasis and elevations in commensal and pathogenic bacteria. Together our studies provide important insights into how Btla functions as a checkpoint in diverse conventional and regulatory lymphocyte subsets to influence systemic immune responses.

Comparison of Immune Checkpoint Molecules PD-1 and PD-L1 in Paired Primary and Recurrent Glioma: Increasing Trend When Recurrence

Purpose: This study aims to investigate PD-1/PD-L1 expression patterns in paired primary and recurrent gliomas. Methods: From January 2008 to December 2014, 42 patients who underwent surgical resections of primary and recurrent gliomas were retrospectively included. PD-1/PD-L1 protein expression in tumors was evaluated through immunohistochemistry. Results: In primary gliomas, PD-1 and PD-L1 expression was evident in 9 (22.0%) and 14 (33.3%) patients. In the paired recurrent glioma, PD-1 and PD-L1 expression was evident in 25 (61.0%) and 31 (74.0%) lesions. Both PD-1 and PD-L1 showed significantly enhanced expression after recurrence (p < 0.005; p < 0.005). For PD-L1 expression in recurrent gliomas, the adjuvant therapy group showed significantly increased expression compared to primary gliomas (p < 0.005). For PD-1- primary gliomas, if the matched recurrent gliomas showed PD-1+, the PFS became worse than the remaining recurrent gliomas PD-1- (12.7 vs. 25.9 months, p = 0.032). Interestingly, for PD-L1- primary gliomas, if the matched recurrent gliomas showed PD-L1+, the OS became better than the remaining recurrent gliomas PD-L1- (33.8 vs. 17.5 months, p < 0.001). Conclusions: In the study, we found the expression of PD-1/PD-L1 increased significantly in recurrent gliomas and the elevated level of PD-L1 was tightly associated with adjuvant treatment, suggesting the potential therapeutic and predictive value of PD-1 and PD-L1 in the treatment of recurrent gliomas.

Interleukin-10 improves stroke outcome by controlling the detrimental Interleukin-17A response

Background

Lymphocytes have dichotomous functions in ischemic stroke. Regulatory T cells are protective, while IL-17A from innate lymphocytes promotes the infarct growth. With recent advances of T cell-subtype specific transgenic mouse models it now has become possible to study the complex interplay of T cell subpopulations in ischemic stroke.

Methods

In a murine model of experimental stroke we analyzed the effects of IL-10 on the functional outcome for up to 14 days post-ischemia and defined the source of IL-10 in ischemic brains based on immunohistochemistry, flow cytometry, and bone-marrow chimeric mice. We used neutralizing IL-17A antibodies, intrathecal IL-10 injections, and transgenic mouse models which harbor a deletion of the IL-10R on distinct T cell subpopulations to further explore the interplay between IL-10 and IL-17A pathways in the ischemic brain.

Results

We demonstrate that IL-10 deficient mice exhibit significantly increased infarct sizes on days 3 and 7 and enlarged brain atrophy and impaired neurological outcome on day 14 following tMCAO. In ischemic brains IL-10 producing immune cells included regulatory T cells, macrophages, and microglia. Neutralization of IL-17A following stroke reversed the worse outcome in IL-10 deficient mice and intracerebral treatment with recombinant IL-10 revealed that IL-10 controlled IL-17A positive lymphocytes in ischemic brains. Importantly, IL-10 acted differentially on αβ and γδ T cells. IL-17A producing CD4⁺ αβ T cells were directly controlled via their IL-10-receptor (IL-10R), whereas IL-10 by itself had no direct effect on the IL-17A production in γδ T cells. The control of the IL-17A production in γδ T cells depended on an intact IL10R signaling in regulatory T cells (Tregs).

Conclusions

Taken together, our data indicate a key function of IL-10 in restricting the detrimental IL-17A-signaling in stroke and further supports that IL-17A is a therapeutic opportunity for stroke treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02316-7.

γδT17/γδTreg cell subsets: a new paradigm for asthma treatment

Bronchial asthma (abbreviated as asthma), is a heterogeneous disease characterized by chronic airway inflammation and airway hyperresponsiveness. The main characteristics of asthma include variable reversible airflow limitation and airway remodeling. The pathogenesis of asthma is still unclear. Th1/Th2 imbalance, Th1 deficiency and Th2 hyperfunction are classic pathophysiological mechanisms of asthma. Some studies have shown that the imbalance of the Th1/Th2 cellular immune model and Th17/Treg imbalance play a key role in the occurrence and development of asthma; however, these imbalances do not fully explain the disease. In recent years, studies have shown that γδT and γδT17 cells are involved in the pathogenesis of asthma. γδTreg has a potential immunosuppressive function, but its regulatory mechanisms have not been fully elucidated. In this paper, we reviewed the role of γδT17/γδTreg cells in bronchial asthma, including the mechanisms of their development and activation. Here we propose that γδT17/Treg cell subsets contribute to the occurrence and development of asthma, constituting a novel potential target for asthma treatment.

γδ T Cells for Leukemia Immunotherapy: New and Expanding Trends

Recently, many discoveries have elucidated the cellular and molecular diversity in the leukemic microenvironment and improved our knowledge regarding their complex nature. This has allowed the development of new therapeutic strategies against leukemia. Advances in biotechnology and the current understanding of T cell-engineering have led to new approaches in this fight, thus improving cell-mediated immune response against cancer. However, most of the investigations focus only on conventional cytotoxic cells, while ignoring the potential of unconventional T cells that until now have been little studied. γδ T cells are a unique lymphocyte subpopulation that has an extensive repertoire of tumor sensing and may have new immunotherapeutic applications in a wide range of tumors. The ability to respond regardless of human leukocyte antigen (HLA) expression, the secretion of antitumor mediators and high functional plasticity are hallmarks of γδ T cells, and are ones that make them a promising alternative in the field of cell therapy. Despite this situation, in particular cases, the leukemic microenvironment can adopt strategies to circumvent the antitumor response of these lymphocytes, causing their exhaustion or polarization to a tumor-promoting phenotype. Intervening in this crosstalk can improve their capabilities and clinical applications and can make them key components in new therapeutic antileukemic approaches. In this review, we highlight several characteristics of γδ T cells and their interactions in leukemia. Furthermore, we explore strategies for maximizing their antitumor functions, aiming to illustrate the findings destined for a better mobilization of γδ T cells against the tumor. Finally, we outline our perspectives on their therapeutic applicability and indicate outstanding issues for future basic and clinical leukemia research, in the hope of contributing to the advancement of studies on γδ T cells in cancer immunotherapy.

Inhibiting the Unconventionals: Importance of Immune Checkpoint Receptors in γδ T, MAIT, and NKT Cells

Simple Summary

All conventional major histocompatibility complex (MHC)-restricted T cells transiently express immune checkpoint/inhibitory receptors (ICRs) following activation as a means to counter-regulate overactivation. However, tumors promote chronic ICR expression rendering T cells chronically unresponsive or “exhausted”. Checkpoint inhibitor (CPI) therapy targets and blocks ICRs, restoring T cell activation and anti-tumor immunity. However, CPI therapy often fails, partly because of the tumor’s many abilities to inhibit MHC-driven T cell responses. In this regard, our immune system contains an arsenal of unconventional non-MHC-restricted T cells, whose importance in anti-tumor immunity is rapidly gaining momentum. There is currently little knowledge as to whether unconventional T cells can get exhausted and how CPI therapy affects them. In this article we review the current understanding of the role of ICRs in unconventional T cell biology and discuss the importance of targeting these unique immune cell populations for CPI therapy.

Abstract

In recent years, checkpoint inhibitor (CPI) therapy has shown promising clinical responses across a broad range of cancers. However, many patients remain unresponsive and there is need for improvement. CPI therapy relies on antibody-mediated neutralization of immune inhibitory or checkpoint receptors (ICRs) that constitutively suppress leukocytes. In this regard, the clinical outcome of CPI therapy has primarily been attributed to modulating classical MHC-restricted αβ T cell responses, yet, it will inevitably target most lymphoid (and many myeloid) populations. As such, unconventional non-MHC-restricted gamma delta (γδ) T, mucosal associated invariant T (MAIT) and natural killer T (NKT) cells express ICRs at steady-state and after activation and may thus be affected by CPI therapies. To which extent, however, remains unclear. These unconventional T cells are polyfunctional innate-like lymphocytes that play a key role in tumor immune surveillance and have a plethora of protective and pathogenic immune responses. The robust anti-tumor potential of γδ T, MAIT, and NKT cells has been established in a variety of preclinical cancer models and in clinical reports. In contrast, recent studies have documented a pro-tumor effect of innate-like T cell subsets that secrete pro-inflammatory cytokines. Consequently, understanding the mechanisms that regulate such T cells and their response to CPI is critical in designing effective cancer immunotherapies that favor anti-tumor immunity. In this Review, we will discuss the current understanding regarding the role of immune checkpoint regulation in γδ T, MAIT, and NKT cells and its importance in anti-cancer immunity.

Soluble B7-CD28 Family Inhibitory Immune Checkpoint Proteins and Anti-Cancer Immunotherapy

Co-inhibitory B7-CD28 family member proteins negatively regulate T cell responses and are extensively involved in tumor immune evasion. Blockade of classical CTLA-4 (cytotoxic T lymphocyte-associated antigen-4) and PD-1 (programmed cell death protein-1) checkpoint pathways have become the cornerstone of anti-cancer immunotherapy. New inhibitory checkpoint proteins such as B7-H3, B7-H4, and BTLA (B and T lymphocyte attenuator) are being discovered and investigated for their potential in anti-cancer immunotherapy. In addition, soluble forms of these molecules also exist in sera of healthy individuals and elevated levels are found in chronic infections, autoimmune diseases, and cancers. Soluble forms are generated by proteolytic shedding or alternative splicing. Elevated circulating levels of these inhibitory soluble checkpoint molecules in cancer have been correlated with advance stage, metastatic status, and prognosis which underscore their broader involvement in immune regulation. In addition to their potential as biomarker, understanding their mechanism of production, biological activity, and pathological interactions may also pave the way for their clinical use as a therapeutic target. Here we review these aspects of soluble checkpoint molecules and elucidate on their potential for anti-cancer immunotherapy.

Evolved to protect, designed to destroy: IL-17-producing γδ T cells in infection, inflammation, and cancer

T cells of the gamma delta (γδ) lineage are evolutionary conserved from jawless to cartilaginous and bony fish to mammals and represent the "swiss army knife" of the immune system capable of antigen-dependent or independent responses, memory, antigen presentation, regulation of other lymphocytes, tissue homeostasis, and mucosal barrier maintenance, to list a few. Over the last 10 years, γδ T cells that produce the cytokine IL-17 (γδT17) have taken a leading position in our understanding of how our immune system battles infection, inflicts tissue damage during inflammation, and gets rewired by the tumor microenvironment. A lot of what we know about γδT17 cells stems from mouse models, however, increasing evidence implicates these cells in numerous human diseases. Herein, we aim to give an overview of the most common mouse models that have been used to study the role of γδT17 cells in infection, inflammation, and cancer, while at the same time we will evaluate evidence for their importance in humans. We hope and believe that in the next 10 years, means to take advantage of the protective and destructive properties of γδ T and in particular γδT17 cells will be part of our standard immunotherapy toolkit.

The Role of B and T Lymphocyte Attenuator in Respiratory System Diseases

B and T lymphocyte attenuator (BTLA), an immunomodulatory molecule widely expressed on the surface of immune cells, can influence various signaling pathways and negatively regulate the activation and proliferation of immune cells by binding to its ligand herpes virus entry mediator (HVEM). BTLA plays an important role in immunoregulation and is involved in the pathogenesis of various respiratory diseases, including airway inflammation, asthma, infection, pneumonia, acute respiratory distress syndrome and lung cancer. In recent years, some studies have found that BTLA also has played a positive regulatory effect on immunity system in the occurrence and development of respiratory diseases. Since severe pulmonary infection is a risk factor for sepsis, this review also summarized the new findings on the role of BTLA in sepsis.

Immune Checkpoints in Pediatric Solid Tumors: Targetable Pathways for Advanced Therapeutic Purposes

The tumor microenvironment (TME) represents a complex network between tumor cells and a variety of components including immune, stromal and vascular endothelial cells as well as the extracellular matrix. A wide panel of signals and interactions here take place, resulting in a bi-directional modulation of cellular functions. Many stimuli, on one hand, induce tumor growth and the spread of metastatic cells and, on the other hand, contribute to the establishment of an immunosuppressive environment. The latter feature is achieved by soothing immune effector cells, mainly cytotoxic T lymphocytes and B and NK cells, and/or through expansion of regulatory cell populations, including regulatory T and B cells, tumor-associated macrophages and myeloid-derived suppressor cells. In this context, immune checkpoints (IC) are key players in the control of T cell activation and anti-cancer activities, leading to the inhibition of tumor cell lysis and of pro-inflammatory cytokine production. Thus, these pathways represent promising targets for the development of effective and innovative therapies both in adults and children. Here, we address the role of different cell populations homing the TME and of well-known and recently characterized IC in the context of pediatric solid tumors. We also discuss preclinical and clinical data available using IC inhibitors alone, in combination with each other or administered with standard therapies.

Roles of BTLA in Immunity and Immune Disorders

B and T lymphocyte attenuator (BTLA) is one of the most important cosignaling molecules. It belongs to the CD28 superfamily and is similar to programmed cell death-1 (PD-1) and cytotoxic T lymphocyte associated antigen-4 (CTLA-4) in terms of its structure and function. BTLA can be detected in most lymphocytes and induces immunosuppression by inhibiting B and T cell activation and proliferation. The BTLA ligand, herpesvirus entry mediator (HVEM), does not belong to the classic B7 family. Instead, it is a member of the tumor necrosis factor receptor (TNFR) superfamily. The association of BTLA with HVEM directly bridges the CD28 and TNFR families and mediates broad and powerful immune effects. Recently, a large number of studies have found that BTLA participates in numerous physiopathological processes, such as tumor, inflammatory diseases, autoimmune diseases, infectious diseases, and transplantation rejection. Therefore, the present work aimed to review the existing knowledge about BTLA in immunity and summarize the diverse functions of BTLA in various immune disorders.

Exploration of the Prognostic and Immunotherapeutic Value of B and T Lymphocyte Attenuator in Skin Cutaneous Melanoma

B and T lymphocyte attenuator (BTLA) is a newly identified immune checkpoint molecular belonging to the CD28 immunoglobulin superfamily. However, the expression and clinical value of BTLA in skin cutaneous melanoma (SKCM) has not been widely characterized. We found that BTLA levels were upregulated in metastatic melanoma compared to normal skin tissues and primary melanoma. Higher BTLA was also correlated with improved prognosis in SKCM based on several datasets. The multivariate Cox regression model revealed that BTLA was an independent survival indicator in metastatic melanoma. Tumor microenvironment analysis indicated BTLA was positively associated with the infiltrating levels of different immune cells and the activity of the anti-cancer immunity cycle. Importantly, BTLA accurately predicted the outcome of melanoma patients treated with MAGE-A3 blocker or first-line anti-PD-1. The present findings disclose that BTLA is a reliable biomarker for prognosis and immunotherapeutic response and might contribute to developing novel SKCM immunological treatment strategies.

Gamma Delta T Cells and Their Pathogenic Role in Psoriasis

γδT cells are an unconventional population of T lymphocytes that play an indispensable role in host defense, immune surveillance, and homeostasis of the immune system. They display unique developmental, distributional, and functional patterns and rapidly respond to various insults and contribute to diverse diseases. Although γδT cells make up only a small portion of the total T cell pool, emerging evidence suggest that aberrantly activated γδT cells may play a role in the pathogenesis of psoriasis. Dermal γδT cells are the major IL-17-producing cells in the skin that respond to IL-23 stimulation. Furthermore, γδT cells exhibit memory-cell-like characteristics that mediate repeated episodes of psoriatic inflammation. This review discusses the differentiation, development, distribution, and biological function of γδT cells and the mechanisms by which they contribute to psoriasis. Potential therapeutic approaches targeting these cells in psoriasis have also been detailed.

Innate Cells: The Alternative Source of IL-17 in Axial and Peripheral Spondyloarthritis?

Spondyloarthritis (SpA) is a chronic inflammatory rheumatism characterized by inflammation of sacroiliac joints, peripheral joints, and spine. The Assessment of SpondyloArthritis Society describes three disease forms: axial (axSpA), peripheral, and enthesitic SpA. Each may be associated with extra-articular manifestations: psoriasis, inflammatory bowel disease, and acute anterior uveitis. Genome-wide association studies performed in axSpA and psoriatic arthritis (PsA) have shown a shared genetic background, especially the interleukin 23 (IL-23)/IL-17 pathway, which suggests pathophysiological similarities. The convincing positive results of clinical trials assessing the effect of secukinumab and ixekizumab (anti-IL-17A monoclonal antibodies) in axSpA and PsA have reinforced the speculated crucial role of IL-17 in SpA. Nevertheless, and obviously unexpectedly, the differential efficacy of anti-IL-23–targeted treatments between axSpA (failure) and PsA (success) has profoundly disrupted our presumed knowledge of disease pathogeny. The cells able to secrete IL-17, their dependence on IL-23, and their respective role according to the clinical form of the disease is at the heart of the current debate to potentially explain these observed differences in efficacy of IL-23/IL-17–targeted therapy. In fact, IL-17 secretion is usually mainly related to T helper 17 lymphocytes. Nevertheless, several innate immune cells express IL-23 receptor and can produce IL-17. To what extent these alternative cell populations can produce IL-17 independent of IL-23 and their respective involvement in axSpA and PsA are the crucial scientific questions in SpA. From this viewpoint, this is a nice example of a reverse path from bedside to bench, in which the results of therapeutic trials allow for reflecting more in depth on the pathophysiology of a disease. Here we provide an overview of each innate immunity-producing IL-17 cell subset and their respective role in disease pathogeny at the current level of our knowledge.

The BTLA and PD-1 signaling pathways independently regulate the proliferation and cytotoxicity of human peripheral blood γδ T cells

Background

B‐ and T‐lymphocyte attenuator (BTLA) and programmed cell death‐1 (PD‐1) inhibit γδ T cell homeostasis and activation. This study aimed to determine whether BTLA and PD‐1 signaling pathways were convergent or independent in human peripheral blood γδ T cells. Herein we demonstrate that the signalings of BTLA and PD‐1 regulated proliferation and cytotoxicity of human γδ T cells, respectively.

Methods

Human peripheral blood γδ T cells were cultured with inactivated Jurkat cells in the presence of interleukin‐2 and zoledronate (Zol) for 14 days. Flow cytometry was performed to evaluate the phenotypes and functions of γδ T cells.

Results

The proliferation of the γδ T cells was increased when PBMCs were cocultured with inactivated herpes virus entry mediator (HVEM)^low Jurkat cells. The cytotoxicity of the expanded γδ T cells was not affected by coculture with inactivated HVEM^low Jurkat cells and was further increased in the presence of anti‐PD‐L1 mAb. These results suggest that the inactivation of the BTLA signaling pathway during expansion could help produce more γδ T cells without compromising γδ T cell function. The inhibition of BTLA or PD‐1 signaling repressed phosphorylation of the src homology region 2‐containing protein tyrosine phosphatase 2 and increased the phosphorylation of protein kinase B in γδ T cells. However, there were no synergistic or additive effects by a combination of BTLA and PD‐1 blockade.

Conclusion

These results suggest that BTLA signaling is crucial in regulating γδ T cell proliferation and function and that the BTLA and PD‐1 signaling pathways act independently on the proliferation and cytotoxicity of human peripheral γδ T cells.

Novel human immunomodulatory T cell receptors and their double-edged potential in autoimmunity, cardiovascular disease and cancer

In the last decade, approaches based on T cells and their immunomodulatory receptors have emerged as a solid improvement in treatments for various types of cancer. However, the roles of these molecules in the therapeutic context of autoimmune and cardiovascular diseases are still relatively unexplored. Here, we review the best known and most commonly used immunomodulatory T cell receptors in clinical practice (PD-1 and CTLA-4), along with the rest of the receptors with known functions in animal models, which have great potential as modulators in human pathologies in the medium term. Among these other receptors is the receptor CD69, which has recently been described to be expressed in mouse and human T cells in autoimmune and cardiovascular diseases and cancer. However, inhibition of these receptors individually or in combination by drugs or monoclonal antibodies generates a loss of immunological tolerance and can trigger multiple autoimmune disorders in different organs and immune-related adverse effects. In the coming decades, knowledge on the functions of different immunomodulatory receptors will be pivotal for the development of new and better therapies with less harmful side effects. In this review, we discuss the roles of these receptors in the control of immunity from a perspective focused on therapeutic potential in not only cancer but also autoimmune diseases, such as systemic lupus erythematosus, autoimmune diabetes and rheumatoid arthritis, and cardiovascular diseases, such as atherosclerosis, acute myocardial infarction, and myocarditis.

From thymus to periphery: Molecular basis of effector γδ-T cell differentiation

The contributions of γδ T cells to immune (patho)physiology in many pre-clinical mouse models have been associated with their rapid and abundant provision of two critical cytokines, interferon-γ (IFN-γ) and interleukin-17A (IL-17). These are typically produced by distinct effector γδ T cell subsets that can be segregated on the basis of surface expression levels of receptors such as CD27, CD44 or CD45RB, among others. Unlike conventional T cells that egress the thymus as naïve lymphocytes awaiting further differentiation upon activation, a large fraction of murine γδ T cells commits to either IFN-γ or IL-17 expression during thymic development. However, extrathymic signals can both regulate pre-programmed γδ T cells; and induce peripheral differentiation of naïve γδ T cells into effectors. Here we review the key cellular events of "developmental pre-programming" in the mouse thymus; and the molecular basis for effector function maintenance vs plasticity in the periphery. We highlight some of our contributions towards elucidating the role of T cell receptor, co-receptors (like CD27 and CD28) and cytokine signals (such as IL-1β and IL-23) in these processes, and the various levels of gene regulation involved, from the chromatin landscape to microRNA-based post-transcriptional control of γδ T cell functional plasticity.

The Role of Gamma-Delta T Cells in Diseases of the Central Nervous System

Gamma-delta (γδ) T cells are a subset of T cells that promote the inflammatory responses of lymphoid and myeloid lineages, and are especially vital to the initial inflammatory and immune responses. Given the capability to connect crux inflammations of adaptive and innate immunity, γδ T cells are responsive to multiple molecular cues and can acquire the capacity to induce various cytokines, such as GM-CSF, IL-4, IL-17, IL-21, IL-22, and IFN-γ. Nevertheless, the exact mechanisms responsible for γδ T cell proinflammatory functions remain poorly understood, particularly in the context of the central nervous system (CNS) diseases. CNS disease, usually leading to irreversible cognitive and physical disability, is becoming a worldwide public health problem. Here, we offer a review of the neuro-inflammatory and immune functions of γδ T cells, intending to understand their roles in CNS diseases, which may be crucial for the development of novel clinical applications.

Friend or Foe: Prognostic and Immunotherapy Roles of BTLA in Colorectal Cancer

Background

B and T lymphocyte attenuator (BTLA) is a co-signaling protein belonging to the CD28 immunoglobulin superfamily. However, the role of BTLA in prognosis and immunotherapy of colorectal cancer (CRC) remains unclear.

Methods

We evaluated the expression of BTLA via the Oncomine and the cancer genome atlas (TCGA) database. We research the outcome among different BTLA expression patients by Kaplan–Meier curve. We used the Chi-Squared test and Cox regression analysis to identify potential risk factors. Besides, the correlations between BTLA and cancer immune infiltration were investigated via CIBERSORT.

Results

Various cohorts showed that BTLA expression was lower in CRC compared to corresponding normal tissue. Moreover, low BTLA expression was correlated with poor overall survival in TCGA cohorts and Gene Expression Omnibus cohorts (GSE29623 and GSE17536). Low BTLA expression was associated with less lymph node metastasis (p = 0.0123). In the Cox proportional hazards model, BTLA was identified as a favorable prognostic factor. Naive B cells, memory B cells, CD8 T cells, CD4 memory resting T cells, follicular helper T (Tfh) cells, monocytes, resting natural killing (NK) cells, M0 macrophages, M1 macrophages, resting mast cells, and activated mast cells were affected by BTLA expression (all p < 0.01). Correlated immune markers and functional enrichment analysis revealed BTLA functioned in the T cell receptor signaling pathway, B cell receptor signaling pathway, and NK cell-mediated cytotoxicity pathway.

Conclusion

These analyses suggest BTLA is a potential factor for extended survival and closely related to CD8 T cells, Tfh cells, B cells, and NK cells in CRC. We summarize these results that BTLA can be used as a prognostic biomarker and might contribute to developing novel CRC immunological treatment strategies.

Targeting the interleukin-17 immune axis for cancer immunotherapy

IL-17 plays versatile roles during tumorigenesis. Here, Vitiello and Miller summarize current knowledge in harnessing IL-17–producing γδ and Th17 cells for successful cancer immunotherapy.

The role of IL-17 in cancer remains controversial. Emerging evidence suggests that during early oncogenesis IL-17 supports tumor growth, whereas in established tumors IL-17 production by γδ and Th17 cells potentiates antitumor immunity. Consequently, γδ and Th17 cells are attractive targets for immunotherapy in the IL-17 immune axis. To optimize IL-17–based immunotherapy, a deeper understanding of the cytokines dictating IL-17 production and the polarity of γδ and Th17 cells is critical. Here, we delve into the dichotomous roles of IL-17 in cancer and provide insight into the tumor microenvironment conducive for successful IL-17–based γδ and Th17 cell immunotherapy.

γδ T Cells: The Ideal Tool for Cancer Immunotherapy

γδ T cells have recently gained considerable attention as an attractive tool for cancer adoptive immunotherapy due to their potent anti-tumor activity and unique role in immunosurveillance. The remarkable success of engineered T cells for the treatment of hematological malignancies has revolutionized the field of adoptive cell immunotherapy. Accordingly, major efforts are underway to translate this exciting technology to the treatment of solid tumors and the development of allogeneic therapies. The unique features of γδ T cells, including their major histocompatibility complex (MHC)-independent anti-cancer activity, tissue tropism, and multivalent response against a broad spectrum of the tumors, render them ideal for designing universal 'third-party' cell products, with the potential to overcome the challenges of allogeneic cell therapy. In this review, we describe the crucial role of γδ T cells in anti-tumor immunosurveillance and we summarize the different approaches used for the ex vivo and in vivo expansion of γδ T cells suitable for the development of novel strategies for cancer therapy. We further discuss the different transduction strategies aiming at redirecting or improving the function of γδ T cells, as well as, the considerations for the clinical applications.

The neonatal microenvironment programs innate γδ T cells through the transcription factor STAT5

IL-17-producing RORγt+ γδ T cells (γδT17 cells) are innate lymphocytes that participate in type 3 immune responses during infection and inflammation. Herein, we show that γδT17 cells rapidly proliferate within neonatal lymph nodes and gut, where, upon entry, they upregulate T-bet and coexpress IL-17, IL-22, and IFN-γ in a STAT3- and retinoic acid-dependent manner. Neonatal expansion was halted in mice conditionally deficient in STAT5, and its loss resulted in γδT17 cell depletion from all adult organs. Hyperactive STAT5 mutant mice showed that the STAT5A homolog had a dominant role over STAT5B in promoting γδT17 cell expansion and downregulating gut-associated T-bet. In contrast, STAT5B preferentially expanded IFN-γ-producing γδ populations, implying a previously unknown differential role of STAT5 gene products in lymphocyte lineage regulation. Importantly, mice lacking γδT17 cells as a result of STAT5 deficiency displayed a profound resistance to experimental autoimmune encephalomyelitis. Our data identify that the neonatal microenvironment in combination with STAT5 is critical for post-thymic γδT17 development and tissue-specific imprinting, which is essential for infection and autoimmunity.

The immune checkpoint receptor associated phosphatases SHP-1 and SHP-2 are not required for γδT17 cell development, activation, or skin inflammation

IL-17-producing gamma delta (γδT17) cells are innate lymphocytes critical for antibacterial protection at barrier surfaces such as the skin but also highly pathogenic during inflammation. It is therefore important to understand the cellular and molecular mechanisms that could counter-balance overt γδT17 cell activation. Immune checkpoint receptors (ICRs) deliver inhibitory signals to activated lymphocytes and have been implicated as negative regulators of mouse γδT17 cells. In this report, we investigated the cytokine signals that induce ICR expression on γδT17 cells and studied the in vivo role of the Src-homology-2 phosphatases 1 and 2 (SHP-1 and SHP-2) in the context of γδT17-induced psoriasis. We found that surface expression of ICRs can be induced by cytokines; however, SHP-1 or SHP-2 could not inhibit γδT17 responses. In this regard, conditional deletion of SHP-1, SHP-2, or both did no impact γδT17 cell development, expansion, cytokine production, or skin pathology.

STAT3 but not STAT4 is critical for γδT17 cell responses and skin inflammation

The transcription factors STAT3 and STAT4 are essential for lymphocyte differentiation and function. Interleukin (IL)-17 producing γδ T (γδT17) cells are innate lymphocytes important for anti-bacterial and inflammatory responses at barrier surfaces. Herein, we examine the role of STAT3 and STAT4 in regulating the homeostasis, activation, and pathogenicity of γδT17 cells. We show that STAT3 sustains γδT17 numbers in the skin but not in the lymph nodes, while STAT4 deficiency does not affect their homeostasis. Similarly, STAT3 but not STAT4 is essential for IL-23-induced IL-22 production by γδT17 cells. Concomitantly, mice lacking STAT3 expression in γδT17 cells develop significantly reduced psoriasis-like inflammation. STAT3-deficient γδT17 cells fail to expand and to upregulate IL-17A, IL-17F, and IL-22 in response to psoriatic stimuli. Although STAT4-deficient animals develop psoriasis-like disease, γδT17 cells in these mice are defective in IL-17F production. Collectively, our data demonstrate for the first time a critical role for STAT3 in orchestrating the homeostasis and pathogenicity of γδT17 cells and provide evidence for the requirement of STAT4 for optimal cytokine responses during inflammation.

SMAC mimetics promote NIK-dependent inhibition of CD4+ TH17 cell differentiation

Second mitochondria-derived activator of caspase (SMAC) mimetics (SMs) are selective antagonists of the inhibitor of apoptosis proteins (IAPs), which activate noncanonical NF-κB signaling and promote tumor cell death. Through gene expression analysis, we found that treatment of CD4+ T cells with SMs during T helper 17 (TH17) cell differentiation disrupted the balance between two antagonistic transcription factor modules. Moreover, proteomics analysis revealed that SMs altered the abundance of proteins associated with cell cycle, mitochondrial activity, and the balance between canonical and noncanonical NF-κB signaling. Whereas SMs inhibited interleukin-17 (IL-17) production and ameliorated TH17 cell-driven inflammation, they stimulated IL-22 secretion. Mechanistically, SM-mediated activation of NF-κB-inducing kinase (NIK) and the transcription factors RelB and p52 directly suppressed Il17a expression and IL-17A protein production, as well as the expression of a number of other immune genes. Induction of IL-22 production correlated with the NIK-dependent reduction in cMAF protein abundance and the enhanced activity of the aryl hydrocarbon receptor. Last, SMs also increased IL-9 and IL-13 production and, under competing conditions, favored the differentiation of naïve CD4+ T cells into TH2 cells rather than TH17 cells. These results demonstrate that SMs shape the gene expression and protein profiles of TH17 cells and inhibit TH17 cell-driven autoimmunity.

The Cancer Genome Atlas dataset-based analysis of aberrantly expressed genes by GeneAnalytics in thymoma associated myasthenia gravis: focusing on T cells

Background

Myasthenia gravis (MG) is a group of autoimmune disease which could be accompanied by thymoma. Many differences have been observed between thymoma-associated MG (TAMG) and non-MG thymoma (NMG). However, the molecular difference between them remained unknown. This study aimed to explore the differentially expressed genes (DEGs) between the two categories and to elucidate the possible pathogenesis of TAMG further.

Methods

DEGs were calculated using the RNA-Sequencing data from 11 TAMG and 10 NMG in The Cancer Genome Atlas (TCGA) database. GeneAnalytics was performed to characterize the associations between DEGs and tissues and cells, diseases, gene ontology (GO) terms, pathways, phenotypes, and drug/compounds, respectively. Genes related to T cells were sorted out using LifeMapDiscovery Cells and Tissues Database. Genes directly related to the phenotype of autoimmune diseases that were identified by VarElect were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

Results

The expression level of 169 genes showed a significant difference between the two groups, with 94 up-regulated and 75 down-regulated. Overexpression of six genes (ATM, SFTPB, ANKRD55, BTLA, CCR7, TNFRSF25), which are expressed in T cells and directly related to autoimmune disease through VarElect, was identified. The overexpression of soluble BTLA (sBTLA) (P=0.027), CCR7 (P=0.0018), TNFRSF25 (P=0.0013) and ANKRD55 (P=0.0026) was validated by RT-qPCR in thymoma tissues from our center.

Conclusions

Overexpression of sBTLA, CCR7, TNFRSF25 and ANKRD55 was identified and validated by RT-qPCR, which could partly explain the underlying pathogenesis in TAMG.

BTLA/HVEM Signaling: Milestones in Research and Role in Chronic Hepatitis B Virus Infection

B- and T-lymphocyte attenuator (BTLA) is an immune-regulatory receptor, similar to CTLA-4 and PD-1, and is mainly expressed on B-, T-, and all mature lymphocyte cells. Herpes virus entry mediator (HVEM)-BTLA plays a critical role in immune tolerance and immune responses which are areas of intense research. However, the mechanisms of the BTLA and the BTLA/HVEM signaling pathway in human diseases remain unclear. This review describes the research milestones of BTLA and HVEM in chronological order and their role in chronic HBV infection.

Aberrant Expressions of Co-stimulatory and Co-inhibitory Molecules in Autoimmune Diseases

Co-signaling molecules include co-stimulatory and co-inhibitory molecules and play important roles in modulating immune responses. The roles of co-signaling molecules in autoimmune diseases have not been clearly defined. We assessed the expressions of co-stimulatory and co-inhibitory molecules in autoimmune diseases through a bioinformatics-based study. By using datasets of whole-genome transcriptome, the expressions of 54 co-stimulatory or co-inhibitory genes in common autoimmune diseases were analyzed using Robust rank aggregation (RRA) method. Nineteen array datasets and 6 RNA-seq datasets were included in the RRA discovery study and RRA validation study, respectively. Significant genes were further validated in several autoimmune diseases including Graves' disease (GD). RRA discovery study suggested that CD160 was the most significant gene aberrantly expressed in autoimmune diseases (Adjusted P = 5.9E-12), followed by CD58 (Adjusted P = 5.7E-06) and CD244 (Adjusted P = 9.5E-05). RRA validation study also identified CD160 as the most significant gene aberrantly expressed in autoimmune diseases (Adjusted P = 5.9E-09). We further found that the aberrant expression of CD160 was statistically significant in multiple autoimmune diseases including GD (P < 0.05), and CD160 had a moderate role in diagnosing those autoimmune diseases. Flow cytometry confirmed that CD160 was differentially expressed on the surface of CD8⁺ T cells between GD patients and healthy controls (P = 0.002), which proved the aberrant expression of CD160 in GD at the protein level. This study suggests that CD160 is the most significant co-signaling gene aberrantly expressed in autoimmune diseases. Treatment strategy targeting CD160-related pathway may be promising for the therapy of autoimmune diseases.

Expression of B and T lymphocyte attenuator, retinoid-related orphan receptor gamma-isoform-t and interleukin 7 in psoriasis vulgaris

BACKGROUND/OBJECTIVES

Psoriasis is one of the immune-mediated inflammatory diseases where CD4+ T lymphocytes, mainly Th1 cells, and B lymphocytes contribute in their pathogenesis through a pro-inflammatory effect, production of antibodies, activation of T cells and cytokine synthesis. B and T lymphocyte attenuator (BTLA) is a co-inhibitory molecule expressed on T and B lymphocytes as well as other immune cells, and it is necessary to inhibit homoeostatic expansion and activation of lymph node and skin-resident γδ T cells. BTLA expression is regulated by RORγt and IL-7. The study aimed at adding more insight on the role played by co-inhibitory molecule BTLA in psoriasis vulgaris and its inter-relation with RORγt and IL-7 to establish a basis for novel treatment strategies.

METHODS

This case-control study included 25 patients and 25 controls examined for gene expression of BTLA, RORγt and IL-7.

RESULTS

B and T lymphocyte attenuator was significantly lower in psoriasis patients, whereas both RORγt and IL-7 were higher in comparison with controls. A significant positive correlation between disease severity (PASI) and both RORγt and IL-7 as well as between RORγt and IL-7 was found. A significant negative correlation between BTLA and both RORγt and IL-7 was found. Neither the age nor the duration of disease had any correlation with BTLA, RORγt or IL-7. BTLA had no correlation with PASI. Regarding the control group, a significant negative correlation between RORγt and IL-7 was found.

CONCLUSION

B and T lymphocyte attenuator, RORγt and IL-7 play an important role in psoriasis.

HVEM network signaling in cancer

Somatic mutations in cancer cells may influence tumor growth, survival, or immune interactions in their microenvironment. The tumor necrosis factor receptor family member HVEM (TNFRSF14) is frequently mutated in cancers and has been attributed a tumor suppressive role in some cancer contexts. HVEM functions both as a ligand for the lymphocyte checkpoint proteins BTLA and CD160, and as a receptor that activates NF-κB signaling pathways in response to BTLA and CD160 and the TNF ligands LIGHT and LTα. BTLA functions to inhibit lymphocyte activation, but has also been ascribed a role in stimulating cell survival. CD160 functions to co-stimulate lymphocyte function, but has also been shown to activate inhibitory signaling in CD4⁺ T cells. Thus, the role of HVEM within diverse cancers and in regulating the immune responses to these tumors is likely context specific. Additionally, development of therapeutics that target proteins within this network of interacting proteins will require a deeper understanding of how these proteins function in a cancer-specific manner. However, the prominent role of the HVEM network in anti-cancer immune responses indicates a promising area for drug development.

Tipping the balance: inhibitory checkpoints in intestinal homeostasis

The small intestinal and colonic lamina propria are populated with forkhead box P3 (FOXP3)⁺CD4⁺ regulatory T cells (Tregs) and interleukin-10-producing T cells that orchestrate intestinal tolerance to harmless microbial and food antigens. Expression of co-inhibitory receptors such as CTLA-4 and PD-1 serve as checkpoints to these cells controlling their T-cell receptor (TCR)-mediated and CD28-mediated activation and modulating the phenotype of neighboring antigen presenting cells. Recent discoveries on the diversity of co-inhibitory receptors and their selective cellular expression has shed new light on their tissue-dependent function. In this review, we provide an overview of the co-inhibitory pathways and checkpoints of Treg and effector T cells and their mechanisms of action in intestinal homeostasis. Better understanding of these inhibitory checkpoints is desired as their blockade harbors clinical potential for the treatment of cancer and their stimulation may offer new opportunities to treat chronic intestinal inflammation such as inflammatory bowel disease.

Functions of Vγ4 T Cells and Dendritic Epidermal T Cells on Skin Wound Healing

Wound healing is a complex and dynamic process that progresses through the distinct phases of hemostasis, inflammation, proliferation, and remodeling. Both inflammation and re-epithelialization, in which skin γδ T cells are heavily involved, are required for efficient skin wound healing. Dendritic epidermal T cells (DETCs), which reside in murine epidermis, are activated to secrete epidermal cell growth factors, such as IGF-1 and KGF-1/2, to promote re-epithelialization after skin injury. Epidermal IL-15 is not only required for DETC homeostasis in the intact epidermis but it also facilitates the activation and IGF-1 production of DETC after skin injury. Further, the epidermal expression of IL-15 and IGF-1 constitutes a feedback regulatory loop to promote wound repair. Dermis-resident Vγ4 T cells infiltrate into the epidermis at the wound edges through the CCR6-CCL20 pathway after skin injury and provide a major source of IL-17A, which enhances the production of IL-1β and IL-23 in the epidermis to form a positive feedback loop for the initiation and amplification of local inflammation at the early stages of wound healing. IL-1β and IL-23 suppress the production of IGF-1 by DETCs and, therefore, impede wound healing. A functional loop may exist among Vγ4 T cells, epidermal cells, and DETCs to regulate wound repair.

The role of the common gamma-chain family cytokines in γδ T cell-based anti-cancer immunotherapy

Cytokines of the common gamma-chain receptor family, comprising interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15 and IL-21, are vital with respect to organizing and sustaining healthy immune cell functions. Supporting the anti-cancer immune response, these cytokines inspire great interest for their use as vaccine adjuvants and cancer immunotherapies. It is against this background that gamma delta (γδ) T cells, as special-force soldiers and natural contributors of the tumor immunosurveillance, also received a lot of attention the last decade. As γδ T cell-based cancer trials are coming of age, this present review focusses on the effects of the different cytokines of the common gamma-chain receptor family on γδ T cells with respect to boosting γδ T cells as a therapeutic target in cancer immunotherapy. This review also gathers data that IL-15 in particular exhibits key features for augmenting the anti-tumor activity of effector killer γδ T cells whilst overcoming the myriad of immune escape mechanisms used by cancer cells.

Minority stress and leukocyte gene expression in sexual minority men living with treated HIV infection

Sexual minority (i.e., non-heterosexual) individuals experience poorer mental and physical health, accounted for in part by the additional burden of sexual minority stress occurring from being situated in a culture favoring heteronormativity. Informed by previous research, the purpose of this study was to identify the relationship between sexual minority stress and leukocyte gene expression related to inflammation, cancer, immune function, and cardiovascular function. Sexual minority men living with HIV who were on anti-retroviral medication, had viral load < 200 copies/mL, and had biologically confirmed, recent methamphetamine use completed minority stress measures and submitted blood samples for RNA sequencing on leukocytes. Differential gene expression and pathway analyses were conducted comparing those with clinically elevated minority stress (n = 18) and those who did not meet the clinical cutoff (n = 20), covarying reactive urine toxicology results for very recent stimulant use. In total, 90 differentially expressed genes and 138 gene set pathways evidencing 2-directional perturbation were observed at false discovery rate (FDR) < 0.10. Of these, 41 of the differentially expressed genes and 35 of the 2-directionally perturbed pathways were identified as functionally related to hypothesized mechanisms of inflammation, cancer, immune function, and cardiovascular function. The neuroactive-ligand receptor pathway (implicated in cancer development) was identified using signaling pathway impact analysis. Our results suggest several potential biological pathways for future work investigating the relationship between sexual minority stress and health.

Downregulation of BTLA on NKT Cells Promotes Tumor Immune Control in a Mouse Model of Mammary Carcinoma

Natural Killer T cells (NKT cells) are emerging as critical regulators of pro- and anti-tumor immunity, both at baseline and in therapeutic settings. While type I NKT cells can promote anti-tumor immunity, their activity in the tumor microenvironment may be limited by negative regulators such as inhibitory immune checkpoints. We observed dominant expression of B- and T-lymphocyte attenuator (BTLA) on type I NKT cells in polyoma middle T oncogene-driven (PyMT) murine autochthonous mammary tumors. Other immune checkpoint receptors, such as programmed cell death 1 (PD-1) were equally distributed among T cell populations. Interference with BTLA using neutralizing antibodies limited tumor growth and pulmonary metastasis in the PyMT model in a therapeutic setting, correlating with an increase in type I NKT cells and expression of cytotoxic marker genes. While therapeutic application of an anti-PD-1 antibody increased the number of CD8+ cytotoxic T cells and elevated IL-12 expression, tumor control was not established. Expression of ZBTB16, the lineage-determining transcription factor of type I NKT cells, was correlated with a favorable patient prognosis in the METABRIC dataset, and BTLA levels were instrumental to further distinguish prognosis in patents with high ZBTB16 expression. Taken together, these data support a role of BTLA on type I NKT cells in limiting anti-tumor immunity.