The Emerging Complexity of γδT17 Cells

Analysis of the heterogeneity and complexity of murine extraorbital lacrimal gland via single-cell RNA sequencing

PURPOSE

The lacrimal gland is essential for maintaining ocular surface health and avoiding external damage by secreting an aqueous layer of the tear film. However, a healthy lacrimal gland's inventory of cell types and heterogeneity remains understudied.

METHODS

Here, 10X Genome-based single-cell RNA sequencing was used to generate an unbiased classification of cellular diversity in the extraorbital lacrimal gland (ELG) of C57BL/6J mice. From 43,850 high-quality cells, we produced an atlas of cell heterogeneity and defined cell types using classic marker genes. The possible functions of these cells were analyzed through bioinformatics analysis. Additionally, the CellChat was employed for a preliminary analysis of the cell-cell communication network in the ELG.

RESULTS

Over 37 subclasses of cells were identified, including seven types of glandular epithelial cells, three types of fibroblasts, ten types of myeloid-derived immune cells, at least eleven types of lymphoid-derived immune cells, and five types of vascular-associated cell subsets. The cell-cell communication network analysis revealed that fibroblasts and immune cells play a pivotal role in the dense intercellular communication network within the mouse ELG.

CONCLUSIONS

This study provides a comprehensive transcriptome atlas and related database of the mouse ELG.

Landscape of unconventional γδ T cell subsets in cancer

T cells are broadly categorized into two groups, namely conventional and unconventional T cells. Conventional T cells are the most prevalent and well-studied subset of T cells. On the other hand, unconventional T cells exhibit diverse functions shared between innate and adaptive immune cells. During recent decades, γδ T cells have received attention for their roles in cancer immunity. These cells can detect various molecules, such as lipids and metabolites. Also, they are known for their distinctive ability to recognize and target cancer cells in the tumor microenvironment (TME). This feature of γδ T cells could provide a unique therapeutic tool to fight against cancer. Understanding the role of γδ T cells in TME is essential to prepare the groundwork to use γδ T cells for clinical purposes. Here, we provide recent knowledge regarding the role γδ T cell subsets in different cancer types.

RNA-Seq and ATAC-Seq analyses reveal a global transcriptional and chromatin accessibility profiling of γδ T17 differentiation from mouse spleen

IL-17A-producing γδ T cells (γδ T17) are known to play important roles in various autoimmune diseases. However, the molecular mechanisms of γδ T17 differentiation and their functions have not been clarified yet. Here, we sorted IL-17A+ Vγ4, IL-17A- Vγ4, and Vγ1 subsets from mouse spleen by in vitro priming of γδ T17 cells and investigated their differentially expressed genes (DEGs) and differentially accessible regions (DARs) using RNA-seq and ATAC-seq, respectively. Our results showed that DEGs-1 (upregulated genes: 677 and downregulated genes: 821) and DEGs-2 (upregulated genes: 1188 and downregulated genes: 1252) were most closely related to the function and differentiation of peripheral γδ T17. We identified key modules and MCODEs involved in the control of IL-17A+ Vγ4, IL-17A- Vγ4, and Vγ1 subsets using the WGCNA and Metascape analysis. Furthermore, 26 key transcription factors were enriched in three subsets, which contributed to deciphering the potential molecular mechanism driving γδ T17 differentiation. Simultaneously, we conducted chromatin accessibility profiling under γδ T17 differentiation by ATAC-seq. The top six candidate genes were screened for γδ T17 differentiation and function by integrating RNA-seq and ATAC-seq analysis, and the results were further confirmed using RT-qPCR, flow cytometry, and western blot. In addition, the association analysis of candidate genes with the RNA-seq database of psoriasis was performed to elucidate the functional relationship. Our findings provided a novel insight into understanding the molecular mechanisms of γδ T17 differentiation and function and may improve to the development of therapeutic approaches or drugs targeting γδ T17 for autoimmune diseases.

The role of γδ T17 cells in cardiovascular disease

Due to the ability of γδ T cells to bridge adaptive and innate immunity, γδ T cells can respond to a variety of molecular cues and acquire the ability to induce a variety of cytokines such as IL-17 family, IFN-γ, IL-4, and IL-10. IL-17⁺ γδ T cells (γδ T17 cells) populations have recently received considerable interest as they are the major early source of IL-17A in many immune response models. However, the exact mechanism of γδ T17 cells is still poorly understood, especially in the context of cardiovascular disease (CVD). CVD is the leading cause of death in the world, and it tends to be younger. Here, we offer a review of the cardiovascular inflammatory and immune functions of γδ T17 cells in order to understand their role in CVD, which may be the key to developing new clinical applications.

Differential metabolic requirement governed by transcription factor c-Maf dictates innate γδT17 effector functionality in mice and humans

Cellular metabolism has been proposed to govern distinct γδ T cell effector functions, but the underlying molecular mechanisms remain unclear. We show that interleukin-17 (IL-17)-producing γδ T (γδT17) and interferon-γ (IFN-γ)-producing γδ T (γδT1) cells have differential metabolic requirements and that the rate-limiting enzyme isocitrate dehydrogenase 2 (IDH2) acts as a metabolic checkpoint for their effector functions. Intriguingly, the transcription factor c-Maf regulates γδT17 effector function through direct regulation of IDH2 promoter activity. Moreover, mTORC2 affects the expression of c-Maf and IDH2 and subsequent IL-17 production in γδ T cells. Deletion of c-Maf in γδ T cells reduces metastatic lung cancer development, suggesting c-Maf as a potential target for cancer immune therapy. We show that c-Maf also controls IL-17 production in human γδ T cells from peripheral blood and in oral cancers. These results demonstrate a critical role of the transcription factor c-Maf in regulating γδT17 effector function through IDH2-mediated metabolic reprogramming.

A blend of broadly-reactive and pathogen-selected Vγ4 Vδ1 T cell receptors confer broad bacterial reactivity of resident memory γδ T cells

Although murine γδ T cells are largely considered innate immune cells, they have recently been reported to form long-lived memory populations. Much remains unknown about the biology and specificity of memory γδ T cells. Here, we interrogated intestinal memory Vγ4 Vδ1 T cells generated after foodborne Listeria monocytogenes (Lm) infection to uncover an unanticipated complexity in the specificity of these cells. Deep TCR sequencing revealed that a subset of non-canonical Vδ1 clones are selected by Lm infection, consistent with antigen-specific clonal expansion. Ex vivo stimulations and in vivo heterologous challenge infections with diverse pathogenic bacteria revealed that Lm-elicited memory Vγ4 Vδ1 T cells are broadly reactive. The Vγ4 Vδ1 T cell recall response to Lm, Salmonella enterica serovar Typhimurium (STm) and Citrobacter rodentium was largely mediated by the γδTCR as internalizing the γδTCR prevented T cell expansion. Both broadly-reactive canonical and pathogen-selected non-canonical Vδ1 clones contributed to memory responses to Lm and STm. Interestingly, some non-canonical γδ T cell clones selected by Lm infection also responded after STm infection, suggesting some level of cross-reactivity. These findings underscore the promiscuous nature of memory γδ T cells and suggest that pathogen-elicited memory γδ T cells are potential targets for broad-spectrum anti-infective vaccines.

NF-κB1 Contributes to Imiquimod-Induced Psoriasis-Like Skin Inflammation by Inducing Vγ4+Vδ4+γδT17 Cells

Recent studies have identified NF-κB1 as a new disease susceptibility gene for psoriasis. Although accumulating evidence has shown the importance of NF-κB signaling in various cell types in the pathogenesis of psoriasis, it remains unclear how NF-κB1 contributes to the pathogenesis of psoriasis. In this study, we examined psoriasis-like skin diseases induced by topical administration of imiquimod in Nf-κb1‒deficient (Nf-κb1^-/-) mice and littermate wild-type (WT) mice. Compared with WT mice, Nf-κb1^-/- mice exhibited attenuated skin inflammation. The numbers of Vγ4⁺Vδ4⁺γδT17 cells, which cause skin inflammation in this model, were significantly reduced in the skin and draining lymph nodes in imiquimod-treated Nf-κb1^-/- mice. Nf-κb1 is preferentially phosphorylated in Vγ4⁺Vδ4⁺γδT17 cells in WT mice. In vitro proliferation of Vγ4⁺Vδ4⁺γδT17 cells but not conventional CD4⁺ T cells was significantly impaired in Nf-κb1^-/- mice compared with that in WT mice. RNA-sequencing analyses revealed that the expression of E2 factor target genes was decreased in Vγ4⁺Vδ4⁺γδT cells by the absence of NF-κB1. Consistently, the cell cycle progression of Vγ4⁺Vδ4⁺γδT cells was reduced in Nf-κb1^-/- mice compared with that in WT mice. These results suggest that Nf-κb1 plays a crucial role in the pathogenesis of imiquimod-induced psoriasis-like skin inflammation by promoting the proliferation of Vγ4⁺Vδ4⁺γδT17 cells.

Activated γδ T Cells With Higher CD107a Expression and Inflammatory Potential During Early Pregnancy in Patients With Recurrent Spontaneous Abortion

Previous studies have reported the involvement of γδ T cells in recurrent spontaneous abortion (RSA); however, both pathogenic and protective effects were suggested. To interrogate the role of γδ T cells in RSA, peripheral blood from RSA patients and healthy women with or without pregnancy were analyzed for γδ T cells by flow cytometry (n = 9–11 for each group). Moreover, the decidua from pregnant RSA patients and healthy controls (RSA-P and HC-P group, respectively) was simultaneously stained for γδ T cells by immunohistochemistry (IHC) and bulk sequenced for gene expression. Our results demonstrated that the frequencies of peripheral γδ T cells and their subpopulations in RSA patients were comparable to that in healthy subjects, but the PD1 expression on Vδ2⁺ cells was increased in pregnant patients. Furthermore, peripheral Vδ2⁺ cells in RSA-P patients demonstrated significantly increased expression of CD107a, as compared to that in pregnant healthy controls. In addition, RSA-P patients had higher proportion of IL-17A-secreting but not IL-4-secreting Vδ2⁺ cells compared to the control groups. In decidua, an inflammatory microenvironment was also evident in RSA-P patients, in which CCL8 expression and the infiltration of certain immune cells were higher than that in the HC-P group, as revealed by transcriptional analysis. Finally, although the presence of γδ T cells in decidua could be detected during pregnancy in both RSA patients and healthy subjects by multicolor IHC analysis, the expression of CD107a on γδ T cells was markedly higher in the RSA-P group. Collectively, our results indicated that the increased activation, cytotoxicity, and inflammatory potential of peripheral and/or local γδ T cells might be responsible for the pathogenesis of RSA. These findings could provide a better understanding of the role of γδ T cells in RSA and shed light on novel treatment strategies by targeting γδ T cells for RSA patients.

Increased interleukin-17A-producing γδT cells predict favorable survival in elderly patients with LUAD and LUSC

PURPOSE

Aging is closely related to the occurrence of many diseases, including cancer, and involves changes in the immune microenvironment. γδT cells are important components of resident lymphocytes in mucosal tissues. However, little is known about the effects that the aged lung has on γδT cells and their prognostic significance in non-small cell lung cancer.

METHODS

In the current study, the expression of γδTCR and IL-17A was measured by immunohistochemistry in paraffin-embedded lung tissues from 168 patients with adenocarcinoma (LUAD) and 144 patients with squamous cell carcinoma (LUSC). Furthermore, gene transcription patterns in LUAD and LUSC tumors and normal controls were extracted from TCGA and GTEx databases and were analyzed.

RESULTS

High frequency of γδT cells was observed in patients with LUAD and LUSC, whereas the levels of CD4 + T cells, CD8 + T cells and CD56 + cells were decreased. Elevated γδT cells in tumors were mainly IL-17A-releasing γδT17 cells, which were found to be enriched in aged patients. High γδT cell levels positively corelated with the overall survival (OS) of patients, especially the 5-year OS in the elderly. Further analysis of gene transcription patterns indicated that increased expression of LTBR, HES1, RORC, CCR6, IL1, and IL23A may contribute to the transformation of the tumor microenvironment in a manner conducive to γδT17 cell development and differentiation. Finally, gene analysis between different age groups revealed that the expression of CCR6 and IL7 in LUAD, as well as Hes1, IL7, and IL23A in LUSC, were remarkably higher in elderly (age ≥ 60 years) than in younger individuals (age < 60 years).

CONCLUSION

Our findings suggest that intrinsic alterations in the aging lung lead to γδT17 cell enrichment, which subsequently may exert anti-tumor effects in the elderly.

Innate Immune Cells in the Esophageal Tumor Microenvironment

Esophageal cancer (EC) is one of the most common mucosa-associated tumors, and is characterized by aggressiveness, poor prognosis, and unfavorable patient survival rates. As an organ directly exposed to the risk of foodborne infection, the esophageal mucosa harbors distinct populations of innate immune cells, which play vital roles in both maintenance of esophageal homeostasis and immune defense and surveillance during mucosal anti-infection and anti-tumor responses. In this review, we highlight recent progress in research into innate immune cells in the microenvironment of EC, including lymphatic lineages, such as natural killer and γδT cells, and myeloid lineages, including macrophages, dendritic cells, neutrophils, myeloid-derived suppressor cells, mast cells and eosinophils. Further, putative innate immune cellular and molecular mechanisms involved in tumor occurrence and progression are discussed, to highlight potential directions for the development of new biomarkers and effective intervention targets, which can hopefully be applied in long-term multilevel clinical EC treatment. Fully understanding the innate immunological mechanisms involved in esophageal mucosa carcinogenesis is of great significance for clinical immunotherapy and prognosis prediction for patients with EC.

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.

Inhibition of the activation of γδT17 cells through PPARγ-PTEN/Akt/GSK3β/NFAT pathway contributes to the anti-colitis effect of madecassic acid

Type-17 immune response, mediated mainly by IL-17, plays a critical role in ulcerative colitis. Previously, we showed that madecassic acid (MA), the main active ingredient of Centella asiatica herbs for anti-colitis effect, ameliorated dextran sulfate sodium (DSS)-induced mouse colitis through reducing the level of IL-17. Here, we explore the effect of MA on the activation of γδT17 cells, an alternative source of IL-17 in colitis. In DSS-induced colitis mice, oral administration of MA decreased the number of γδT17 cells and attenuated the inflammation in the colon, and the anti-colitis effect of MA was significantly counteracted by redundant γδT17 cells, suggesting that the decrease in γδT17 cells is important for the anti-colitis effect of MA. In vitro, MA could inhibit the activation but not the proliferation of γδT17 cells at concentrations without evident cytotoxicity. Antibody microarray profiling showed that the inhibition of MA on the activation of γδT17 cells involved PPARγ–PTEN/Akt/GSK3β/NFAT signals. In γδT17 cells, MA could reduce the nuclear localization of NFATc1 through inhibiting Akt phosphorylation to promote GSK3β activation. Moreover, it was confirmed that MA inhibited the Akt/GSK3β/NFATc1 pathway and the activation of γδT17 cells through activating PPARγ to increase PTEN expression and phosphorylation. The correlation between activation of PPARγ, decrease in γδT17 cell number, and amelioration of colitis by MA was validated in mice with DSS-induced colitis. In summary, these findings reveal that MA inhibits the activation of γδT17 cells through PPARγ–PTEN/Akt/GSK3β/NFAT pathway, which contributes to the amelioration of colitis.

Topical Estrogen Treatment Augments the Vaginal Response to Escherichia coli Flagellin

The female climacteric or menopausal process characterised by reduced estrogen, associates with an increased risk of recurrent urinary tract infections (rUTIs) linked to uropathogenic Escherichia coli (UPEC). Clinically, topical vaginal estrogen treatment has a prophylactic effect against such infections. The aim of this study was to investigate, in vitro, the effects of a topical estrogen treatment on vaginal epithelial responses following challenge with E.coli flagellin mimicking an UPEC challenge. Immortalised vaginal epithelial cells (VK2 E6/E7), modelling the vaginal epithelium were treated with either 4 nM 17β-estradiol (E) for seven days, 50 ng/ml E.coli flagellin (F) for 12 h, or 4 nM 17β-estradiol plus 50 ng/ml flagellin (E + F(12 h)). RNA was analysed by microarray gene profiling using the Illumina HumanHT-12 v 4 Expression Beadchip. Following E + F treatments expression of genes encoding host defence molecules including DEFβ4A, DEFB103A, LCN2 as well as those associated with keratinisation eg CNFN and SPRR family genes were significantly enhanced (P < 0.05) compared to either E or F treatments alone. Mutation of estrogen responsive elements (EREs) identified in the DEFβ4 gene promoter abolished the augmented gene expression suggesting estrogen functioned directly through a regulatory mechanism involving ESR1/2. Ingenuity pathway analyses also suggested the pro-inflammatory cytokine IL-17A to regulate the vaginal host defences during infection. Pre-treating VK2 E6/E7 cells with estrogen (4 nM) and challenging with 1L-17A & F (12 h) significantly enhanced DEFβ4, DEF103A and S100A7 expression (P < 0.05). Origins of vaginal IL-17 in vivo remain unclear, but patient biopsies support γδ T cells located within the vaginal epithelium. These data suggest that the vaginal antimicrobial response induced by flagellin activation of Toll-like Receptor 5 cell signalling is augmented following topical estrogen application.

IL-17-producing γδ T cells protect against Clostridium difficile infection

Colitis caused by Clostridium difficile infection is a growing cause of human morbidity and mortality, especially after antibiotic use in health care settings. The natural immunity of newborn infants and protective host immune mediators against C. difficile infection are not fully understood, with data suggesting that inflammation can be either protective or pathogenic. Here, we show an essential role for IL-17A produced by γδ T cells in host defense against C. difficile infection. Fecal extracts from children with C. difficile infection showed increased IL-17A and T cell receptor γ chain expression, and IL-17 production by intestinal γδ T cells was efficiently induced after infection in mice. C. difficile-induced tissue inflammation and mortality were markedly increased in mice deficient in IL-17A or γδ T cells. Neonatal mice, with naturally expanded RORγt+ γδ T cells poised for IL-17 production were resistant to C. difficile infection, whereas elimination of γδ T cells or IL-17A each efficiently overturned neonatal resistance against infection. These results reveal an expanded role for IL-17-producing γδ T cells in neonatal host defense against infection and provide a mechanistic explanation for the clinically observed resistance of infants to C. difficile colitis.

Critical Role for SLAM/SAP Signaling in the Thymic Developmental Programming of IL-17- and IFN-γ-Producing γδ T Cells

During thymic development, mouse γδ T cells commit to either an IFN-γ- or an IL-17-producing phenotype through mechanisms that remain unclear. In this study, we investigated the extent to which the SLAM/SAP signaling pathway regulates the functional programming of γδ T cells. Characterization of SLAM family receptor expression revealed that thymic γδ T cell subsets were each marked by distinct coexpression profiles of SLAMF1, SLAMF4, and SLAMF6. In the thymus, Vγ1 and Vγ4 T cells that exhibited an SLAMF1+SLAMF6+ double positive phenotype were largely contained within immature CD24+CD73- and CD24+CD73+ subsets, whereas SLAMF1 single positive, SLAMF6 single positive, or SLAMF1SLAMF6 double negative cells were found within mature CD24-CD73+ and CD24-CD73- subsets. In the periphery, SLAMF1 and SLAMF6 expression distinguished IL-17- and IFN-γ-producing γδ T cells, respectively. Disruption of SLAM family receptor signaling through deletion of SAP resulted in impaired thymic Vγ1 and Vγ4 T cell maturation at the CD24+CD73-SLAMF1+SLAMF6+ double positive stage that was associated with a decreased frequency of CD44+RORγt+ γδ T cells. Impaired development was in turn associated with decreased γδ T cell IL-17 and IFN-γ production in the thymus as well as in peripheral tissues. The role for SAP was subset-specific, as Vγ1Vδ6.3, Vγ4, Vγ5, but not Vγ6 subsets were SAP-dependent. Together, these data suggest that the SLAM/SAP signaling pathway plays a larger role in γδ T cell development than previously appreciated and represents a critical checkpoint in the functional programming of both IL-17- and IFN-γ-producing γδ T cell subsets.

Innate Lymphocytes in Psoriasis

Skin is a fundamental component of our host defense system that provides a dynamic physical and chemical barrier against pathogen invasion and environmental insults. Cutaneous barrier function is mediated by complex interactions between structural cells such as keratinocytes and diverse lineages of immune cells. In contrast to the protective role of these intercellular interactions, uncontrolled immune activation can lead to keratinocyte dysfunction and psoriasis, a chronic inflammatory disease affecting 2% of the global population. Despite some differences between human and murine skin, animal models of psoriasiform inflammation have greatly informed clinical approaches to disease. These studies have helped to identify the interleukin (IL)-23-IL-17 axis as a central cytokine network that drives disease. In addition, they have led to the recent description of long-lived, skin-resident innate lymphocyte and lymphoid cells that accumulate in psoriatic lesions. Although not completely defined, these populations have both overlapping and unique functions compared to antigen-restricted αβ T lymphocytes, the latter of which are well-known to contribute to disease pathogenesis. In this review, we describe the diversity of innate lymphocytes and lymphoid cells found in mammalian skin with a special focus on αβ T cells, Natural Killer T cells and Innate Lymphoid cells. In addition, we discuss the effector functions of these unique leukocyte subsets and how each may contribute to different stages of psoriasis. A more complete understanding of these cell types that bridge the innate and adaptive immune system will hopefully lead to more targeted therapies that mitigate or prevent disease progression.

Resolving the mystery-How TCR transgenic mouse models shed light on the elusive case of gamma delta T cells

Cutting-edge questions in αβ T cell biology were addressed by investigating a range of different genetically modified mouse models. In comparison, the γδ T cell field lacks behind on the availability of such models. Nevertheless, transgenic mouse models proved useful for the investigation of γδ T cell biology and their stepwise development in the thymus. In general, animal models and especially mouse models give access to a wide range of opportunities of modulating γδ T cells, which is unachievable in human beings. Because of their complex biology and specific tissue tropism, it is especially challenging to investigate γδ T cells in in vitro experiments since they might not reliably reflect their behavior and phenotype under physiologic conditions. This review aims to provide a comprehensive historical overview about how different transgenic mouse models contributed in regards of the understanding of γδ T cell biology, whereby a special focus is set on studies including the elusive role of the γδTCR. Furthermore, evolutionary and translational remarks are discussed under the aspect of future implications for the field. The ultimate full understanding of γδ T cells will pave the way for their usage as a powerful new tool in immunotherapy.

Novel Insight Into the Molecular and Metabolic Mechanisms Orchestrating IL-17 Production in γδ T Cells

Increasing evidence has demonstrated that IL-17-producing γδ T cells (γδ T17) play a tumor-promoting role in a series of cancers via various mechanisms in mice and human cancers, though the relationship between γδ T17 and human tumors has yet to be extensively characterized and established. Molecular signals such as intrinsic cascade, environmental cues and cellular metabolic pathways including nutrient uptake and utilization in γδ T17 cells are significantly important for their activation, differentiation, and function. Understanding the molecular mechanisms and metabolic pathways of γδ T17 cells in both the physiological setting and tumor environment would contribute to the development of therapeutic approaches or drugs targeting γδ T17 for immunotherapy in cancers.

Targeting cell signaling in allergic asthma

Asthma is chronic inflammation of the airways characterized by airway hyper-responsiveness, wheezing, cough, and dyspnea. Asthma affects >350 million people worldwide. The Th2 immune response is a major contributor to the pathophysiology of asthma. Targeted therapy modulating cell signaling pathways can be a powerful strategy to design new drugs to treat asthma. The potential molecular pathways that can be targeted include IL-4-IL-13-JAK-STAT-MAP kinases, adiponectin-iNOS-NF-κB, PGD2-CRTH2, IFNs-RIG, Wnt/β-catenin-FAM13A, FOXC1-miR-PI3K/AKT, JNK-Gal-7, Nrf2-ROS, Foxp3-RORγt, CysLTR, AMP, Fas-FasL, PTHrP/PPARγ, PAI-1, FcɛRI-LAT-SLP-76, Tim-3-Gal-9, TLRs-MyD88, PAR2, and Keap1/Nrf2/ARE. Therapeutic drugs can be designed to target one or more of these pathways to treat asthma.

IL-7-dependent compositional changes within the γδ T cell pool in lymph nodes during ageing lead to an unbalanced anti-tumour response

How the age-associated decline of immune function leads to increased cancer incidence is poorly understood. Here, we have characterised the cellular composition of the γδ T-cell pool in peripheral lymph nodes (pLNs) upon ageing. We find that ageing has minimal cell-intrinsic effects on function and global gene expression of γδ T cells, and γδTCR diversity remains stable. However, ageing alters TCRδ chain usage and clonal structure of γδ T-cell subsets. Importantly, IL-17-producing γδ17 T cells dominate the γδ T-cell pool of aged mice-mainly due to the selective expansion of Vγ6+ γδ17 T cells and augmented γδ17 polarisation of Vγ4+ T cells. Expansion of the γδ17 T-cell compartment is mediated by increased IL-7 expression in the T-cell zone of old mice. In a Lewis lung cancer model, pro-tumourigenic Vγ6+ γδ17 T cells are exclusively activated in the tumour-draining LN and their infiltration into the tumour correlates with increased tumour size in aged mice. Thus, upon ageing, substantial compositional changes in γδ T-cell pool in the pLN lead to an unbalanced γδ T-cell response in the tumour that is associated with accelerated tumour growth.

The role of gamma delta T lymphocytes in breast cancer: a review

Gammadelta T (γδT) lymphocytes have provoked interest in oncology, particularly as regards their potential use in immunotherapy, because of their unique ability to recognise antigens without a requirement for major histocompatibility complex antigen presentation, and to quickly activate an anti-tumour response. However, work in some cancers has suggested that they also have pro-tumourigenic activity. Their role in breast cancer is unclear. This review outlines the evidence to date in in vitro studies, in vivo mouse models and in human studies regarding the role of γδT lymphocytes in breast cancer. We describe the seemingly opposing roles of the predominantly circulating Vγ9Vδ2⁺ subtype, which can suppress tumour growth through direct cytotoxicity, induction of apoptosis and inhibition of angiogenesis, and the predominantly tumour-infiltrating γδ1⁺ subtype which can promote tumour growth and spread through immunosuppressant effects. We summarise the evidence in breast cancer for the mechanisms of action of γδT lymphocytes and describe how factors in the tumour microenvironment may affect their function, polarising them towards a pro-tumourigenic, immune-suppressing role. We also describe the experience to date of γδT lymphocytes in immunotherapy for breast cancer and suggest the direction of work going forward, particularly as regards different breast cancer subtypes.