γδ T Lymphocytes as a First Line of Immune Defense: Old and New Ways of Antigen Recognition and Implications for Cancer Immunotherapy

The role of innate immune cells in modulating vascular dynamics in skin malignancies

A developing tumor relies heavily on blood vessels to supply oxygen and nutrients. As a result, angiogenesis, the formation of new blood vessels, supports tumor growth and progression. Similarly, lymphangiogenesis, the formation of new lymphatic vessels, plays a critical role in metastatic dissemination by providing pathways for malignant cells to spread. The tumor microenvironment is crucial for establishing and maintaining these vascular networks, with innate immune cells playing a key regulatory role. Notably, immune cells are specifically enriched in barrier tissues, such as the skin, emphasizing their importance in skin malignancies. Therefore, understanding their role in regulating angiogenesis and lymphangiogenesis is essential for developing novel therapeutic strategies. This review article explores how innate immune cells influence tumor vasculature and highlights the therapeutic potential that may arise from this knowledge.

Participation of T cells in generating immune protection against cancers

T cells are essential to the immune system's reaction. The major job of the immune system is to identify and get rid of any abnormal or malignant cells in the body. White blood cells called T cells coordinate and carry out immunological responses, including identifying and eliminating cancer cells. It mostly consists of two types called helper T-cells and cytotoxic T-cells. Together, they create an efficient reaction against cancer. Both the primary T cell subtype - CD4+ and CD8+ Tcells have specific role to play in our immune system.CD4+ T cells are limited to MHC-II molecules and acts as helper cell by activating and enhancing other immune cells. On the other side CD8+ T cells are called the killer cells as they eradicate the abnormal and contaminated cells and are limited to MHC-I molecules. The malignant cells are destroyed when cytotoxic T cells come into direct contact with them. This happens via number of processes, including TCR recognition, the release of cytotoxic chemicals, and finally the activation of the immune system. T cell receptors on the surface of cytotoxic T cells allow them to identify tumour cells and these T cells release harmful chemicals like perforins and granzymes when they connect to malignant cells. T-cells that have been stimulated release cytokines such as gamma interferon. T-cells can also acquire memory responses that improve their capacity for recognition and response. Helper T-cells contribute to the development of an immune response. It entails coordination and activation as well as the enlistment of additional immune cells, including macrophages and natural killer cells, to assist in the eradication of cancer cells. Despite the fact that the cancer frequently creates defence systems to circumvent their immune response. Together, these activities support the immune surveillance and T-cell-mediated regulation of cancer cells. Treatments like chemotherapy, radiation, and surgery are main ways to treat cancer but immunotherapy has been emerging since last few decades. These immune specific treatments have shown huge positive result. CAR T cell therapy is a promising weapon to fight again blood cancer and it works by focusing on our immune system to fight and eliminate cancer.

Anti-Anisakis antibodies in colon cancer patients and their relationship with γδ T-cells

Many pathogens are related to carcinogenesis. Chronic inflammation, as a result of persistent infection, leads to DNA damage, higher expression of oncogenes, decreased apoptosis and immunosuppression, which are some of the reasons for cancer induction. Among parasites, Schistosoma, Opistorchis and Clonorchis are recognised as infectious agents which contribute to cancer. A relationship between Anisakis and cancer was hypothesised because cellular responses to Anisakis products could result in inflammation and DNA damage. Previous research has shown a decrease in CD8+ γδ T-cells and an increase in αβ and γδ T-cell apoptosis in colon cancer (CC) samples. Ninety-two CC patients and 60 healthy subjects were recruited. γδ and αβ T-cells were analysed, and their apoptosis was evaluated. Anti-Anisakis antibodies were tested in sera from CC patients and controls. Anti-Anisakis IgG, IgM, IgA and IgE antibodies were significantly higher in CC patients. A significant increase in anti-Anisakis IgA levels was observed in patients with angiolymphatic invasion. The number of all γδ T-cells, as well as CD3+ CD4+ αβ T-cells, was significantly lower in CC patients. The apoptosis of all T-cells was significantly increased in patients with CC. We observed a significantly higher percentage of anti-Anisakis IgE positive patients having a deficit of CD3+ γδ T-cells. Our results suggest a relationship between Anisakis and CC.

Controversial role of γδ T cells in colorectal cancer

Colorectal cancer (CRC) is the third most frequent type of cancer, and the second leading cause of cancer-related deaths worldwide. Current treatments for patients with CRC do not substantially improve the survival and quality of life of patients with advanced CRC, thus necessitating the development of new treatment strategies. The emergence of immunotherapy has revitalized the field, showing great potential in advanced CRC treatment. Owing to the ability of tumor cells to evade the immune system through major histocompatibility complex shedding and heterogeneous and low antigen spreading, only a few patients respond to immunotherapy. γδ T cells have heterogeneous structures and functions, and their key roles in immune regulation, tumor immunosurveillance, and specific primary immune responses have increasingly been recognized. γδ T cells recognize and kill CRC cells efficiently, thus inhibiting tumor progress through various mechanisms. However, γδ T cells can potentially promote tumor development and metastasis. Thus, given this dual role in prognosis, these cells can act as either a "friend" or "foe" of CRC. In this review, we explore the characteristics of γδ T cells and their functions in CRC, highlighting their application in immunotherapy.

STAT5 is essential for inducing the suppressive subset and attenuate cytotoxicity of Vδ2+ T cells in acute myeloid leukemia

Under the sustained exposure to tumor microenvironment, effector lymphocytes may transform into the suppressive populations. γδ T cells are recognized as a crucial mediator and effector of immune surveillance and thereby a promising candidate for anti-tumor immunotherapy. Emerging clinical studies implicate that some γδ T subsets play an important role in promoting tumor progression. Our previous study identified an abnormal Vδ2+ T cells subset with regulatory features (Reg-Vδ2) in the patients with newly diagnosed acute myeloid leukemia (AML), and demonstrated that Reg-Vδ2 cells significantly suppressed the anti-AML effects of effector Vδ2 cells (Eff-Vδ2). The molecular mechanism underlying the subset transformation of Vδ2 cells remains unclear. Here, we found that the expression and activity of STAT5 were significantly induced in Reg-Vδ2 cells compared with Eff-Vδ2 cells, which was consistent with the differences found in primary Vδ2 cells between AML patients and healthy donors. In-vitro experiments further indicated that STAT5 was required for the induction of Reg-Vδ2 cells. The combined immunophenotypical and functional assays showed that blockage of STAT5 alleviated the immunosuppressive effect of Reg-Vδ2 cells on Eff-Vδ2 cells and enhanced the anti-AML capacity of Vδ2 cells from health donors and AML patients. Collectively, these results suggest that STAT5 acts as a critical regulator in the transformation of effector Vδ2 cells into a subset with immunosuppressive characteristics, providing a potential target for the improvement the efficacy of γδ T cells-based immunotherapy to treat AML and other hematologic malignancies.

Assessment of immune cells in the uterine fluid at the time of the embryo transfer

PROBLEM

Although endometrial receptivity is a key factor in influencing implantation in both naturally conceived and assisted reproductive technology (ART) cycles, very little is known about the endometrium milieu around the time of implantation. Previous studies have demonstrated the presence of several cytokines in the endometrium that affect implantation. However, there is lacking data about the presence of immune cell subtypes within the endometrium and in the uterine cavity at the time of implantation.

METHOD OF STUDY

This study was approved by the Institutional Review Board (# 225589). The study was designed as a prospective observational cohort study between May 2021 and December 2022 at a single academic-based fertility center. All patients underwent at least one In Vitro Fertilization (IVF) cycle and have frozen embryos. Twenty-four participants were recruited for this study which was conducted during the frozen embryo transfer (FET) cycle regardless of the outcome of previous cycles. Two samples were acquired from each subject, denoted as lower and upper. A trial transfer catheter was introduced under ultrasound guidance into the lower uterine segment. Upon removal, the tip was rinsed in IMDM medium containing 10% FBS (lower uterus). A transfer catheter was then loaded with the embryo that was placed in the upper uterus under ultrasound guidance. The tip of the transfer catheter was rinsed in separate aliquot of the above media (upper uterus). After centrifugation, pelleted cells were stained for the following surface markers: CD45, CD3, CD19, CD4, CD8, gamma delta TCR, CD25, CD127, CD66b, CD14, CD16, CD56 and acquired on Sony SP6800 Spectral Analyzer.

RESULTS

Upon staining the pelleted cells, we were able to identify viable leukocytes from samples obtained from both, upper and lower uterus (0.125 × 106 cells ± SD 0.32), (0.123 × 106 cells ± SD 0.12), respectively. Among total viable cells, there was no significant difference in both percent and number of CD45+ cells between the upper and lower uterus (9.88% ± 6.98 SD, 13.67% ± 9.79 SD, p = .198) respectively. However, there was significantly higher expression of CD3+ (p = .006), CD19+ (p = .032) and CD14+ (p = .019) cells in samples collected from upper compared to lower uterus. Within all CD3+ cells, we found that gamma delta T cells (GDT) were the major population of T cells in both upper and lower uterus. In contrast, CD8+ T cells were significantly higher in the lower uterus when compared to the upper uterus (p = .009). There was no statistically significant difference in the expression of CD4+ T cells, T regulatory cells (CD4+CD25+CD127-), NK cells (CD56+), neutrophils (CD66b+) and FcγRIII+ cells (CD16+) between upper and lower uterus.

CONCLUSIONS

We believe the immune milieu at the time of embryo transfer will affect implantation. Understanding the composition of immune cells will guide further research in identifying optimal immune milieus that favor implantation. Comprehensive analysis of endometrium is expected to lead to new diagnostic and therapeutic approaches to improve IVF outcomes.

Innate immune cells: Key players of orchestra in modulating tumor microenvironment (TME)

The tumor microenvironment (TME) with vital role in cancer progression is composed of various cells such as endothelial cells, immune cells, and mesenchymal stem cells. In particular, innate immune cells such as macrophages, dendritic cells, myeloid-derived suppressor cells, neutrophils, innate lymphoid cells, γδT lymphocytes, and natural killer cells can either promote or suppress tumor progression when present in the TME. An increase in research on the cross-talk between the TME and innate immune cells will lead to new approaches for anti-tumoral therapeutic interventions. This review primarily focuses on the biology of innate immune cells and their main functions in the TME. In addition, it summarizes several innate immune-based immunotherapies that are currently tested in clinical trials.

C5a enhances inflammation and chemotaxis of γδ T cells in malignant pleural effusion

BACKGROUND

The inhibitory effect of γδT17 cells on the formation of murine malignant pleural effusions (MPE) has been established. However, there is limited understanding regarding the phenotypic characterization of γδ T cells in MPE patients and their recruitment to the pleural cavity.

METHODS

We quantified γδ T cell prevalence in pleural effusions and corresponding peripheral blood from malignant and benign patients using immunohistochemistry and flow cytometry. The expression of effector memory phenotype, stimulatory/inhibitory/chemokine receptors and cytokines on γδ T cells in MPE was analyzed using multicolor flow cytometry. The infiltration of γδ T cells in MPE was assessed through immunofluorescence, ELISA, flow cytometry and transwell migration assay.

RESULTS

We observed a significant infiltration of γδ T cells in MPE, surpassing the levels found in blood and benign pleural effusion. γδ T cells in MPE exhibited heightened expression of CD56 and an effector memory phenotype, while displaying lower levels of PD-1. Furthermore, γδ T cells in MPE showed higher levels of cytokines (IFN-γ, IL-17A and IL-22) and chemokine receptors (CCR2, CCR5 and CCR6). CCR2 expression was notably higher in the Vδ2 subtype compared to Vδ1 cells. Moreover, the complement C5a enhanced cytokine release by γδ T cells, upregulated CCR2 expression in Vδ2 subsets, and stimulated the production of chemokines (CCL2, CCL7 and CCL20) in MPE. In vitro utilizing CCR2 neutralising and C5aR antagonist significantly reduced the recruitment of γδ T cells.

CONCLUSIONS

γδ T cells infiltrate MPE by overexpressing CCR2 and exhibit hightened inflammation, which is further augmented by C5a.

Function of gamma delta (γδ) T cell in cancer with special emphasis on cervical cancer

Cervical cancer is the second-most prevalent gynecologic cancer in India. It is typically detected in women between the ages of 35 and 44. Cervical cancer is mainly associated with the human papillomavirus (HPV). The report shows that 70 % of cervical cancer is caused by HPV 16 and 18. There are few therapeutic options and vaccines available for cervical cancer treatment and γδ T cell therapy is one of them. This therapy can kill various types of cancers, including cervical cancer. The major γδ T cell subset is the Vγ9Vδ2 T cell, mainly distributed in peripheral blood which recognize non-MHC peptide antigens and can eliminate MHC-downregulated cancer. Moreover, γδ T cells can express different types of receptors that bind to the molecules of stressed cells, often produced on cancerous cells but absent from healthy tissue. γδ T cells possess both direct and indirect cytotoxic capabilities against malignancies and show potential antitumoral responses. However, γδ T cells also encourage the progression of cancer. Cancer immunotherapy using γδ T cells will be a potential cancer treatment, as well as cervical cancer. This review focused on the γδ T cell and its function in cancer, with special emphasis on cervical cancer. It also focused on the ligand recognition site of γδ T cells, galectin-mediated therapy and pamidronate-treated therapy for cervical cancer. Instead of the great potential of γδ T cell for the eradication of cervical cancer, no comprehensive in-depth review is available to date, so there is a need to jot down the various roles and modes of action and different applications of γδ T cells for cancer research, which we believe will be a handy tool for the researchers and the readers.

Comprehensively analysis of immunophenotyping signature in triple-negative breast cancer patients based on machine learning

Immunotherapy is a promising strategy for triple-negative breast cancer (TNBC) patients, however, the overall survival (OS) of 5-years is still not satisfactory. Hence, developing more valuable prognostic signature is urgently needed for clinical practice. This study established and verified an effective risk model based on machine learning methods through a series of publicly available datasets. Furthermore, the correlation between risk signature and chemotherapy drug sensitivity were also performed. The findings showed that comprehensive immune typing is highly effective and accurate in assessing prognosis of TNBC patients. Analysis showed that IL18R1, BTN3A1, CD160, CD226, IL12B, GNLY and PDCD1LG2 are key genes that may affect immune typing of TNBC patients. The risk signature plays a robust ability in prognosis prediction compared with other clinicopathological features in TNBC patients. In addition, the effect of our constructed risk model on immunotherapy response was superior to TIDE results. Finally, high-risk groups were more sensitive to MR-1220, GSK2110183 and temsirolimus, indicating that risk characteristics could predict drug sensitivity in TNBC patients to a certain extent. This study proposes an immunophenotype-based risk assessment model that provides a more accurate prognostic assessment tool for patients with TNBC and also predicts new potential compounds by performing machine learning algorithms.

Gamma Delta T Cells: Role in Immunotherapy of Hepatocellular Carcinoma

The most typical type of liver cancer or hepatocellular carcinoma (HCC) develops from hepatocyte loss. Non-alcoholic fatty liver disease (NAFLD), viral hepatitis C and cirrhosis are the leading causes of HCC. With the Hepatitis B vaccine and medicines, there are several treatments for HCC, including liver resection, ablation, transplantation, immunotherapy, gene therapy, radiation embolization, and targeted therapy. Currently, a wide range of studies are carried out on gene therapy to identify biomarkers and pathways, which help us identify the exact stage of the disorder and reduce its effects. γδT cells have recently received much interest as a potential cancer treatment method in adaptive immunotherapy. γδT cells can quickly form connections between receptor and ligand activation. They can clonally expand and are a significant source of cytokines and chemokines. The present review provides a comprehensive understanding on the function of γδT cells in immunotherapies and how they are used to treat HCC.

Targeting of colorectal cancer organoids with zoledronic acid conjugated to the anti-EGFR antibody cetuximab

BACKGROUND

Antibody-drug conjugates (ADC) are essential therapeutic options to treat solid and hematological cancers. The anti-epidermal growth factor-receptor (EGFR) antibody cetuximab (Cet) is used for the therapy of colorectal carcinoma (CRC). Anti-CRC Vδ2 cytolytic T lymphocytes can be elicited by the priming of tumor cells with the aminobisphosphonate zoledronic acid (ZA) and consequent presentation of isopentenyl pyrophosphates through butyrophilin (BTN) family members such as BTN3A1 and BTN2A1. A major drawback that impairs the targeting of ZA to CRC is the bone tropism of aminobisphosphonates.

METHODS

The phosphoric group of ZA was linked to free amino groups of Cet in the presence of imidazole following the labeling of phosphoric groups of DNA to amino groups of proteins. The generation of Cet-ZA ADC was confirmed by matrix assisted laser desorption ionization mass spectrometry and inductively coupled plasma-mass spectrometry analysis. Thirteen CRC organoids were obtained with a chemically defined serum-free medium in Geltrex domes. Proliferation and activation of cytolytic activity against CRC organoids by Vδ2 T cells was detected with flow cytometry, crystal violet and cytotoxic probe assays and image analysis. Immunohistochemistry and quantification of BTN3A1 or BTN2A1 expression and the number of tumor infiltrating Vδ2 T cells in CRC were performed by automatic immunostaining, whole slide scanning and computerized analysis of digital pathology imaging.

RESULTS

The novel ADC Cet-ZA was generated with a drug antibody ratio of 4.3 and displayed a reactivity similar to the unconjugated antibody. More importantly, patient-derived CRC organoids, or CRC tumor cell suspensions, could trigger the expansion of Vδ2 T cells from peripheral blood and tumor infiltrating lymphocytes when primed with Cet-ZA. Furthermore, Cet-ZA triggered Vδ2 T cell-mediated killing of CRC organoids. The expression of BTN3A1 and BTN2A1 was detected not only in CRC organoids but also in CRC specimens, together with a considerable amount of tumor infiltrating Vδ2 T cells.

CONCLUSIONS

These findings are proof of concept that the Cet-ZA ADC can be used to target specifically CRC organoids and may suggest a new experimental approach to deliver aminobisphosphonates to EGFR+ solid tumors.

Targeted drug delivery system for ovarian cancer microenvironment: Improving the effects of immunotherapy

Immunotherapies have shown modest benefits in the current clinical trials for ovarian cancer. The tumor microenvironment (TME) in an immunosuppressive phenotype contributes to this “failure” of immunotherapy in ovarian cancer. Many stromal cell types in the TME (e.g., tumor-associated macrophages and fibroblasts) have been identified as having plasticity in pro- and antitumor activities and are responsible for suppressing the antitumor immune response. Thus, the TME is an extremely valuable target for adjuvant interventions to improve the effects of immunotherapy. The current strategies targeting the TME include: 1) eliminating immunosuppressive cells or transforming them into immunostimulatory phenotypes and 2) inhibiting their immunosuppressive or pro-tumor production. Most of the effective agents used in the above strategies are genetic materials (e.g., cDNA, mRNA, or miRNA), proteins, or other small molecules (e.g., peptides), which are limited in their target and instability. Various formulations of drug delivery system (DDS) have been designed to realize the controlled release and targeting delivery of these agents to the tumor sites. Nanoparticles and liposomes are the most frequently exploited materials. Based on current evidence from preclinical and clinical studies, the future of the DDS is promising in cancer immunotherapy since the combination of agents with a DDS has shown increased efficacy and decreased toxicities compared with free agents. In the future, more efforts are needed to further identify the hallmarks and biomarkers in the ovarian TME, which is crucial for the development of more effective, safe, and personalized DDSs.

The role of polyamine metabolism in remodeling immune responses and blocking therapy within the tumor immune microenvironment

The study of metabolism provides important information for understanding the biological basis of cancer cells and the defects of cancer treatment. Disorders of polyamine metabolism is a common metabolic change in cancer. With the deepening of understanding of polyamine metabolism, including molecular functions and changes in cancer, polyamine metabolism as a new anti-cancer strategy has become the focus of attention. There are many kinds of polyamine biosynthesis inhibitors and transport inhibitors, but not many drugs have been put into clinical application. Recent evidence shows that polyamine metabolism plays essential roles in remodeling the tumor immune microenvironment (TIME), particularly treatment of DFMO, an inhibitor of ODC, alters the immune cell population in the tumor microenvironment. Tumor immunosuppression is a major problem in cancer treatment. More and more studies have shown that the immunosuppressive effect of polyamines can help cancer cells to evade immune surveillance and promote tumor development and progression. Therefore, targeting polyamine metabolic pathways is expected to become a new avenue for immunotherapy for cancer.

Immune competence and spleen size scale with colony status in the naked mole-rat

Naked mole-rats (NM-R; Heterocephalus glaber) live in multi-generational colonies with a social hierarchy, and show low cancer incidence and long life-spans. Here we asked if an immune component might underlie such extreme physiology. The largest lymphoid organ is the spleen, which plays an essential role in responding to immunological insults and may participate in combating cancer and slowing ageing. We investigated the anatomy, molecular composition and function of the NM-R spleen using RNA-sequencing and histological analysis in healthy NM-Rs. Spleen size in healthy NM-Rs showed considerable inter-individual variability, with some animals displaying enlarged spleens. In all healthy NM-Rs, the spleen is a major site of adult haematopoiesis under normal physiological conditions. However, myeloid-to-lymphoid cell ratio is increased and splenic marginal zone showed markedly altered morphology when compared to other rodents. Healthy NM-Rs with enlarged spleens showed potentially better anti-microbial profiles and were much more likely to have a high rank within the colony. We propose that the anatomical plasticity of the spleen might be regulated by social interaction and gives immunological advantage to increase the lifespan of higher-ranked animals.

Tissue-Specific Expression of TIGIT, PD-1, TIM-3, and CD39 by γδ T Cells in Ovarian Cancer

Phenotypic characterization of γδ T cells in the MALs (malignant ascites lymphocytes), TILs (tumor infiltrating lymphocytes), and PBLs (peripheral blood lymphocytes) of ovarian cancer (OvCA) patients is lacking. Therefore, we quantified γδ T cell prevalence in MAL, TIL, and PBL specimens from n = 18 OvCA patients and PBL from age-matched healthy donors (HD, n = 14). Multicolor flow cytometry was performed to evaluate the expression of inhibitory receptors (TIGIT, PD-1 and TIM-3), stimulatory receptors (Ox40), and purinergic ectoenzymes (CD39 and CD73) on γδ T cell subsets. We identified an abundant infiltration of Vδ1 T cells in the MALs and TILs. These cells varied in their differentiation: The majority of Vδ1 TILs displayed an effector memory (EM) phenotype, whereas Vδ1 MALs had a more mature phenotype of terminally differentiated effector memory cells (TEMRA) with high CD45RA expression. TIGIT and TIM-3 were abundantly expressed in both MALs and PBLs, whereas Vδ1 TILs exhibited the highest levels of PD-1, CD39, and Ox40. We also observed specific clusters on mature differentiation stages for the analyzed molecules. Regarding co-expression, Vδ1 TILs showed the highest levels of cells co-expressing TIGIT with PD-1 or CD39 compared to MALs and PBLs. In conclusion, the Vδ1 T cell population showed a high prevalence in the MALs and primary tumors of OvCA patients. Due to their (co-)expression of targetable immune receptors, in particular TIGIT with PD-1 and CD39 in TILs, Vδ1 T cell-based approaches combined with the inhibition of these targets might represent a promising strategy for OvCA.

Bone Marrow-Resident Vδ1 T Cells Co-express TIGIT With PD-1, TIM-3 or CD39 in AML and Myeloma

Background: γδ T cells represent a unique T cell subpopulation due to their ability to recognize cancer cells in a T cell receptor- (TCR) dependent manner, but also in a non-major histocompatibility complex- (MHC) restricted way via natural killer receptors (NKRs). Endowed with these features, they represent attractive effectors for immuno-therapeutic strategies with a better safety profile and a more favorable anti-tumor efficacy in comparison to conventional αβ T cells. Also, remarkable progress has been achieved re-activating exhausted T lymphocytes with inhibitors of co-regulatory receptors e.g., programmed cell death protein 1 (PD-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT) and of the adenosine pathway (CD39, CD73). Regarding γδ T cells, little evidence is available. This study aimed to immunophenotypically characterize γδ T cells from patients with diagnosed acute myeloid leukemia (AML) in comparison to patients with multiple myeloma (MM) and healthy donors (HD).

Methods: The frequency, differentiation, activation, and exhaustion status of bone marrow- (BM) derived γδ T cells from patients with AML (n = 10) and MM (n = 11) were assessed in comparison to corresponding CD4⁺ and CD8⁺ T cells and peripheral blood- (PB) derived γδ T cells from HDs (n = 16) using multiparameter flow cytometry.

Results: BM-infiltrating Vδ1 T cells showed an increased terminally differentiated cell population (TEMRAs) in AML and MM in comparison to HDs with an aberrant subpopulation of CD27⁻CD45RA⁺⁺ cells. TIGIT, PD-1, TIM-3, and CD39 were more frequently expressed by γδ T cells in comparison to the corresponding CD4⁺ T cell population, with expression levels that were similar to that on CD8⁺ effector cells in both hematologic malignancies. In comparison to Vδ2 T cells, the increased frequency of PD-1⁺-, TIGIT⁺-, TIM-3⁺, and CD39⁺ cells was specifically observed on Vδ1 T cells and related to the TEMRA Vδ1 population with a significant co-expression of PD-1 and TIM-3 together with TIGIT.

Conclusion: Our results revealed that BM-resident γδ T cells in AML and MM express TIGIT, PD-1, TIM-3 and CD39. As effector population for autologous and allogeneic strategies, inhibition of co-inhibitory receptors on especially Vδ1 γδ T cells may lead to re-invigoration that could further increase their cytotoxic potential.

Prognostic and Therapeutic Significance of BTN3A Proteins in Tumors

The Butyrophilin 3A (BTN3A) family is a type I transmembrane protein belonging to the immunoglobulin (Ig) superfamily. The family contains three members: BTN3A1, BTN3A2 and BTN3A3, which share 95% homology in the extracellular domain. The expression of BTN3A family members is different in different types of tumors, which plays an important role in tumor prognosis. Among them, there are many studies on tumor immunity of BTN3A1, which shows that it is essential for the activation of Vγ9Vδ2 T cells, while BTN3A3 is expected to become a potential therapeutic target for breast cancer. Recent studies have shown that the BTN3A family is closely related to the occurrence and development of tumors. Now the BTN3A family has become one of the research hotspots and is expected to become new tumor prediction and treatment targets.

The Dual Roles of Human γδ T Cells: Anti-Tumor or Tumor-Promoting

γδ T cells are the unique T cell subgroup with their T cell receptors composed of γ chain and δ chain. Unlike αβ T cells, γδ T cells are non-MHC-restricted in recognizing tumor antigens, and therefore defined as innate immune cells. Activated γδ T cells can promote the anti-tumor function of adaptive immune cells. They are considered as a bridge between adaptive immunity and innate immunity. However, several other studies have shown that γδ T cells can also promote tumor progression by inhibiting anti-tumor response. Therefore, γδ T cells may have both anti-tumor and tumor-promoting effects. In order to clarify this contradiction, in this review, we summarized the functions of the main subsets of human γδ T cells in how they exhibit their respective anti-tumor or pro-tumor effects in cancer. Then, we reviewed recent γδ T cell-based anti-tumor immunotherapy. Finally, we summarized the existing problems and prospect of this immunotherapy.

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.

Transcriptome-Based Network Analysis Unveils Eight Immune-Related Genes as Molecular Signatures in the Immunomodulatory Subtype of Triple-Negative Breast Cancer

Objective: Triple-negative breast cancer (TNBC) is a high heterogeneity cancer. The identification of genomic aberrations that drive each of the TNBC subtypes may predict the prognosis of patients with TNBC and provide novel therapeutic strategies in clinical practice. This study focuses on the transcriptome-based gene expression of TNBC and aims to generate comprehensive gene co-expression networks correlated with the immune-related subtype of TNBC. Methods: The transcriptome profiles of 107 female patients with TNBC were analyzed. Weighted gene co-expression network analysis (WGCNA) was applied to construct related networks and to sort hub-genes associated with the survival of TNBC patients. The data of the transcriptional expression, genomic alteration, survival status, and tumor immune microenvironment, which associated with hub-genes, were extracted, retrieved, and analyzed from Oncomine, UALCAN, TCGA, starBase, Kaplan-Meier Plotter, cBioPortal, and TIMER databases. Results: Immune-related hub-genes, including BIRC3, BTN3A1, CSF2RB, GIMAP7, GZMB, HCLS1, LCP2, and SELL, were found to be associated with clinical features of TNBC evaluated by WGCNA. These hub-genes belonged to the immunomodulatory subtype of TNBC and were upregulated in the TNBC cells. The protein expression of eight immune-related hub-genes was further confirmed to be upregulated in TNBC/CD8+ tissues detected by immunohistochemical staining. Survival analysis revealed that overexpression of eight immune-related hub-genes was in favor of the survival of patients with TNBC. Moreover, a positive correlation between eight immune-related hub-genes and immune cell infiltration was observed in TNBC patients. Furthermore, checkpoint inhibitor genes such as PD-L1, PD-1, and CTLA4 were more enrichment in the immunomodulatory subtype of TNBC and the expression of PD-L1, PD-1, and CTLA4 was positively correlated with eight immune-related hub-genes in the breast cancer dataset of TCGA. Conclusions: Eight immune-related hub-genes were identified to be molecular signatures in the immunomodulatory subtype of TNBC, which may provide therapeutic targets for the treatment of patients with breast cancer.

Immune Effects of γδ T Cells in Colorectal Cancer: A Review

Gamma delta (γδ) T cells can effectively recognize and kill colorectal cancer (CRC) cells, thereby suppressing tumor progression via multiple mechanisms. They also have abilities to exert a protumor effect via secreting interleukin-17 (IL-17). γδ T cells have been selected as potential immunocytes for antitumor treatment because of their significant cytotoxic activity. Immunotherapy is another potential anti-CRC strategy after an operation, chemotherapy, and radiotherapy. γδ T cell-based immunotherapy for CRC shows fewer side effects and better toleration. This review will outline the immune functions and the mechanisms of γδ T cells in the growth and progression of CRC in recent years, and summarize the immunotherapies based on γδ T cells, thus providing a direction for future γδ T cells in CRC research.

Valproic acid enhances pamidronate-sensitized cytotoxicity of Vδ2+ T cells against EBV-related lymphoproliferative cells

Therapeutic options for Epstein-Barr virus (EBV)-associated post-transplantation lymphoproliferative diseases (PTLD) are currently limited, accompanying with some off-target toxicities. We previously demonstrated that early recovery of Vδ2⁺ T cells inversely correlated to EBV reactivation after allogeneic hematopoietic cell transplantation. Studies in vitro and in the mouse models showed the cytotoxic activity of Vδ2⁺ T cells on EBV-transformed lymphoproliferative cells, but the efficacy was moderate. Bisphosphonate, such as pamidronate (PAM), have been reported as a sensitizer to trigger tumor cells for Vδ2⁺ T cells recognition. Valproic acid (VPA) has attracted attentions due to its adjuvant anti-tumor effect with chemotherapy or immunotherapy. Whether PAM and VPA facilitate the immunogenicity of EBV-infected cells towards Vδ2⁺ T cells cytotoxicity remains unknown. Herein, we demonstrated that lower dosage of VPA and/or PAM did not induce apoptosis of EBV-transformed B lymphoblastoid cell lines (EBV-LCLs) or Vδ2⁺ T cells. Notably, pre-treatment with PAM significantly increased the cell death of EBV-LCLs after co-culture with Vδ2⁺ T cells at different ratios. Combining treatment with VPA reinforced the sensitizing effect of PAM. This efficacy was through inducing the accumulation of mevalonate pathway intermediates and dependent on the γδ T cell receptor of Vδ2⁺ T cells. Similar sensitizing effects of PAM and PAM plus VPA were also demonstrated on the primary PTLD cells. These results highlight the roles of PAM and VPA in the enhancement of immune surveillance and expand the fields of these two drugs in the treatment of different types of malignancies.

The Role of Human γδ T Cells in Anti-Tumor Immunity and Their Potential for Cancer Immunotherapy

γδ T cells are a distinct subset of T cells whose T cell receptors consist of γ chains and δ chains, different from conventional αβ T cells. γδ T cells are considered as a member of the innate immunity because of their non-MHC restricted antigen recognition, rapid response to invading pathogens and sense early changes of malignant cells. Upon activation, they can further promote the activation of adaptive immune cells, such as T cells and B cells, by secreting various cytokines. Thus, γδ T cells are regarded as a bridge between innate immunity and acquired immunity. γδ T cells are involved in a variety of immune response processes, including immune defense and immune surveillance against infection and tumorigenesis. γδ T cells recognize multiple tumor-associated antigens or molecules in T cell receptors (TCRs)-dependent and natural killer cell receptors (NKRs)-dependent ways. γδ T cells not only display a direct killing capacity on a variety of tumors, but also exert anti-tumor immune responses indirectly by facilitating the function of other immune cells, such as dendritic cells (DCs), B cells and CD8⁺ T cells. In this review, we summarize the major subpopulations, the tumor recognition mechanisms, and the anti-tumor effects of human γδ T cells, particularly the potential of γδ T cells for cancer immunotherapy.

Gut Microbiota-Derived Short-Chain Fatty Acids Promote Poststroke Recovery in Aged Mice

RATIONALE

The elderly experience profound systemic responses after stroke, which contribute to higher mortality and more severe long-term disability. Recent studies have revealed that stroke outcomes can be influenced by the composition of gut microbiome. However, the potential benefits of manipulating the gut microbiome after injury is unknown.

OBJECTIVE

To determine if restoring youthful gut microbiota after stroke aids in recovery in aged subjects, we altered the gut microbiome through young fecal transplant gavage in aged mice after experimental stroke. Further, the effect of direct enrichment of selective bacteria producing short-chain fatty acids (SCFAs) was tested as a more targeted and refined microbiome therapy.

METHODS AND RESULTS

Aged male mice (18-20 months) were subjected to ischemic stroke by middle cerebral artery occlusion. We performed fecal transplant gavage 3 days after middle cerebral artery occlusion using young donor biome (2-3 months) or aged biome (18-20 months). At day 14 after stroke, aged stroke mice receiving young fecal transplant gavage had less behavioral impairment, and reduced brain and gut inflammation. Based on data from microbial sequencing and metabolomics analysis demonstrating that young fecal transplants contained much higher SCFA levels and related bacterial strains, we selected 4 SCFA-producers (Bifidobacterium longum, Clostridium symbiosum, Faecalibacterium prausnitzii, and Lactobacillus fermentum) for transplantation. These SCFA-producers alleviated poststroke neurological deficits and inflammation, and elevated gut, brain and plasma SCFA concentrations in aged stroke mice.

CONCLUSIONS

This is the first study suggesting that the poor stroke recovery in aged mice can be reversed via poststroke bacteriotherapy following the replenishment of youthful gut microbiome via modulation of immunologic, microbial, and metabolomic profiles in the host.

The Ovarian Cancer Tumor Immune Microenvironment (TIME) as Target for Therapy: A Focus on Innate Immunity Cells as Therapeutic Effectors

Ovarian cancer (OvCA) accounts for one of the leading causes of death from gynecologic malignancy. Despite progress in therapy improvements in OvCA, most patients develop a recurrence after first-line treatments, dependent on the tumor and non-tumor complexity/heterogeneity of the neoplasm and its surrounding tumor microenvironment (TME). The TME has gained greater attention in the design of specific therapies within the new era of immunotherapy. It is now clear that the immune contexture in OvCA, here referred as tumor immune microenvironment (TIME), acts as a crucial orchestrator of OvCA progression, thus representing a necessary target for combined therapies. Currently, several advancements of antitumor immune responses in OvCA are based on the characterization of tumor-infiltrating lymphocytes, which have been shown to correlate with a significantly improved clinical outcome. Here, we reviewed the literature on selected TIME components of OvCA, such as macrophages, neutrophils, γδ T lymphocytes, and natural killer (NK) cells; these cells can have a role in either supporting or limiting OvCA, depending on the TIME stimuli. We also reviewed and discussed the major (immune)-therapeutic approaches currently employed to target and/or potentiate macrophages, neutrophils, γδ T lymphocytes, and NK cells in the OvCA context.

Human Peripheral Blood Gamma Delta T Cells: Report on a Series of Healthy Caucasian Portuguese Adults and Comprehensive Review of the Literature

Gamma delta T cells (Tc) are divided according to the type of Vδ and Vγ chains they express, with two major γδ Tc subsets being recognized in humans: Vδ2Vγ9 and Vδ1. Despite many studies in pathological conditions, only a few have quantified the γδ Tc subsets in healthy adults, and a comprehensive review of the factors influencing its representation in the blood is missing. Here we quantified the total γδ Tc and the Vδ2/Vγ9 and Vδ1 Tc subsets in the blood from 30 healthy, Caucasian, Portuguese adults, we characterized their immunophenotype by 8-color flow cytometry, focusing in a few relevant Tc markers (CD3/TCR-γδ, CD5, CD8), and costimulatory (CD28), cytotoxic (CD16) and adhesion (CD56) molecules, and we examined the impacts of age and gender. Additionally, we reviewed the literature on the influences of race/ethnicity, age, gender, special periods of life, past infections, diet, medications and concomitant diseases on γδ Tc and their subsets. Given the multitude of factors influencing the γδ Tc repertoire and immunophenotype and the high variation observed, caution should be taken in interpreting “abnormal” γδ Tc values and repertoire deviations, and the clinical significance of small populations of “phenotypically abnormal” γδ Tc in the blood.

Chitosan Nanoparticles Strengthen Vγ9Vδ2 T-Cell Cytotoxicity Through Upregulation Of Killing Molecules And Cytoskeleton Polarization

Background

During the past few years, immune cell therapy for malignant cancer has benefited a considerable amount of patients worldwide. As one of several promising candidates for immunotherapy, Vγ9Vδ2 γδ T cells have many unique biological advantages, such as non-MHC restriction and have been noted as the earliest source of IFN-γ. However, potentiating anti-tumor functions of γδ T cells has become of particular interest to researchers studying γδ T cell applications.

Purpose

In this study, we proposed a nanotechnology-based methodology for strengthening γδ T cell functions.

Methods

As a type of reliable, biocompatible material, chitosan nanoparticles (CSNPs) were used to enhance anti-tumor immunity of γδ T cells.

Results

First, we found that the size of prepared CSNPs distributed 50 to 100 nm, and that CSNPs had optimal immunocompatibility. Then, we observed that CSNPs could induce α-tubulin cytoskeleton polarization and rearrangement, correlating with a higher killing ability of γδ T cells. Furthermore, we revealed that CSNPs could enhance Vγ9Vδ2 T cell anti-tumor functions by upregulating killing of related receptors, including NKG2D, CD56, FasL, and perforin secretion.

Conclusion

Our work provided evidence of application for CSNPs based bio-carrier in immunotherapy. More importantly, we proposed a new strategy for enhancing γδ T cell anti-tumor activity using nanobiomaterial, which could benefit future clinical applications of γδ T cells.

Vδ2 T-Cells Kill ZIKV-Infected Cells by NKG2D-Mediated Cytotoxicity

An expansion of effector/activated Vδ2 T-cells was recently described in acute Zika virus (ZIKV)-infected patients, but their role in the protective immune response was not clarified. The aim of this study was to define the antiviral activity of Vδ2 T-cells against ZIKV-infected cells. The Vδ2 T-cells expansion and their cytotoxic activity against ZIKV-infected cells were tested in vitro and analyzed by RT-PCR and flow cytometry. We found that ZIKV infection was able to induce Vδ2 T-cells expansion and sensitized A549 cells to Vδ2-mediated killing. Indeed, expanded Vδ2 T-cells killed ZIKV-infected cells through degranulation and perforin release. Moreover, ZIKV infection was able to increase the expression on A549 cells of NKG2D ligands (NKG2DLs), namely MICA, MICB, and ULBP2, at both the mRNA and protein levels, suggesting the possible involvement of these molecules in the recognition by NKG2D-expressing Vδ2 T-cells. Indeed, the killing of ZIKV-infected cells by expanded Vδ2 T-cells was mediated by NKG2D/NKG2DL interaction as NKG2D neutralization abrogated Vδ2 cytotoxicity. Our data showed a strong antiviral activity of Vδ2 T-cells against ZIKV-infected cells, suggesting their involvement in the protective immune response. Other studies are necessary to investigate whether the lack of Vδ2 T-cells expansion in vivo may be associated with disease complications.

γδ T-cell subsets in HIV controllers: potential role of Tγδ17 cells in the regulation of chronic immune activation

OBJECTIVES

HIV controllers (HICs) are rare HIV-infected individuals able to maintain undetectable viremia in the absence of antiretroviral treatment. Although HIV-specific cytotoxic T cells have been well deciphered in HIC, γδ T lymphocytes remain largely uncharacterized. The aim of this study was to analyse phenotypic and functional characteristics of γδ T cells and their relationship with immune activation, which remains abnormally elevated and associated with comorbidities in HICs.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from 16 HICs, 16 patients with untreated chronic HIV infection (UT-CHI) and 20 healthy donors. Surface marker expression and cytokine production by γδ T cells were analysed by flow cytometry.

RESULTS

Despite normal frequencies of total γδ T cells, the Vδ2/Vδ2 ratio was significantly reduced in HIC, albeit to a lesser extent than UT-CHI patients. Of note, nine HICs showed elevated Vδ2 γδ T cells, as patients with UT-CHI, which was associated with higher CD8 T-cell activation. Interleukin (IL)-17-production by γδ T cells (Tγδ17) was better preserved in HIC than in UT-CHI patients. Proportion of total γδ T cells positively correlated with CD8 T-cell activation and HIV-DNA, IP-10 and sCD14 levels. Conversely, Tγδ17 cells negatively correlated with CD8 T-cell activation and plasma sCD14 levels. Moreover, transforming growth factor (TGF)-β producing Vδ2 T cells were as dramatically depleted in HIC as in UT-CHI patients.

CONCLUSION

The relative preservation of IL-17-producing γδ T cells in HIC and their negative association with immune activation raise the hypothesis that Tγδ17 cells - potentially through prevention of microbial translocation - may participate in the control of chronic systemic immune activation.

Immune precision medicine for cancer: a novel insight based on the efficiency of immune effector cells

Cancer cell growth is associated with immune surveillance failure. Nowadays, restoring the desired immune response against cancer cells remains a major therapeutic strategy. Due to the recent advances in biological knowledge, efficient therapeutic tools have been developed to support the best bio-clinical approaches for immune precision therapy. One of the most important successes in immune therapy is represented by the applicational use of monoclonal antibodies, particularly the use of rituximab for B-cell lymphoproliferative disorders. More recently, other monoclonal antibodies have been developed, to inhibit immune checkpoints within the tumor microenvironment that limit immune suppression, or to enhance some immune functions with immune adjuvants through different targets such as Toll-receptor agonists. The aim is to inhibit cancer proliferation by the diminishing/elimination of cancer residual cells and clinically improving the response duration with no or few adverse effects. This effect is supported by enhancing the number, functions, and activity of the immune effector cells, including the natural killer (NK) lymphocytes, NKT-lymphocytes, γδ T-lymphocytes, cytotoxic T-lymphocytes, directly or indirectly through vaccines particularly with neoantigens, and by lowering the functions of the immune suppressive cells. Beyond these new therapeutics and their personalized usage, new considerations have to be taken into account, such as epigenetic regulation particularly from microbiota, evaluation of transversal functions, particularly cellular metabolism, and consideration to the clinical consequences at the body level. The aim of this review is to discuss some practical aspects of immune therapy, giving to clinicians the concept of immune effector cells balancing between control and tolerance. Immunological precision medicine is a combination of modern biological knowledge and clinical therapeutic decisions in a global vision of the patient.

Decidual RANKL/RANK interaction promotes the residence and polarization of TGF-β1-producing regulatory γδ T cells

ABSTACT

Decidual γδΤ (dγδΤ) cells play an essential role during successful pregnancy; however, the residence and polarization of γδΤ cells in decidua remain unclear. In this study, we observed higher levels of receptor activator for nuclear factor-κ B ligand (RANKL) on decidual stromal cells (DSCs), and its receptor RANK on dγδΤ cells in decidua from normal pregnancy compared with patients with recurrent spontaneous abortion (RSA). RANKL expressed by DSCs can induce the polarization of peripheral blood γδΤ (pγδΤ) and dγδΤ cells to Foxp3 + γδΤ cells, and upregulate the expression of transforming growth factor (TGF)-β1. This process is mediated through activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). In addition, RANKL promotes the adhesion of dγδΤ cells to DSCs in vitro, which is associated with the upregulation of ICAM-1 and VCAM-1 on DSCs and integrins on dγδΤ cells. RANKL knockout leads to the decreased numbers of uterus total γδΤ cells, Foxp3+γδΤ cells and the expression of TGF-β1, and the increased pregnancy loss in mice. These results suggest that RANKL is a pivotal regulator of maternal-fetal tolerance by triggering the polarization and residence of TGF-β1-producing Foxp3+γδΤ cells in early pregnancy. The abnormal low level of RANKL/RANK results in pregnancy loss because of the dialogue disorder between DSCs and dγδΤ cells. This observation provides a scientific basis on which a potential marker can be detected to early warning of pregnancy loss.

Protective Role of γδ T Cells in Different Pathogen Infections and Its Potential Clinical Application

γδ T cells, a subgroup of T cells based on the γδ TCR, when compared with conventional T cells (αβ T cells), make up a very small proportion of T cells. However, its various subgroups are widely distributed in different parts of the human body and are attractive effectors for infectious disease immunity. γδ T cells are activated and expanded by nonpeptidic antigens (P-Ags), major histocompatibility complex (MHC) molecules, and lipids which are associated with different kinds of pathogen infections. Activation and proliferation of γδ T cells play a significant role in diverse infectious diseases induced by viruses, bacteria, and parasites and exert their potential effector function to effectively eliminate infection. It is well known that many types of infectious diseases are detrimental to human life and health and give rise to high incidence of illnesses and death rate all over the world. To date, there is no comprehensive understanding of the correlation between γδ T cells and infectious diseases. In this review, we will focus on the various subgroups of γδ T cells (mainly Vδ1 T cells and Vδ2 T cells) which can induce multiple immune responses or effective functions to fight against common pathogen infections, such as Mycobacterium tuberculosis, Listeria monocytogenes, influenza viruses, HIV, EBV, and HBV. Hopefully, the gamma-delta T cell study will provide a novel effective way to treat infectious diseases.

How to Hit Mesenchymal Stromal Cells and Make the Tumor Microenvironment Immunostimulant Rather Than Immunosuppressive

Experimental evidence indicates that mesenchymal stromal cells (MSCs) may regulate tumor microenvironment (TME). It is conceivable that the interaction with MSC can influence neoplastic cell functional behavior, remodeling TME and generating a tumor cell niche that supports tissue neovascularization, tumor invasion and metastasization. In addition, MSC can release transforming growth factor-beta that is involved in the epithelial-mesenchymal transition of carcinoma cells; this transition is essential to give rise to aggressive tumor cells and favor cancer progression. Also, MSC can both affect the anti-tumor immune response and limit drug availability surrounding tumor cells, thus creating a sort of barrier. This mechanism, in principle, should limit tumor expansion but, on the contrary, often leads to the impairment of the immune system-mediated recognition of tumor cells. Furthermore, the cross-talk between MSC and anti-tumor lymphocytes of the innate and adaptive arms of the immune system strongly drives TME to become immunosuppressive. Indeed, MSC can trigger the generation of several types of regulatory cells which block immune response and eventually impair the elimination of tumor cells. Based on these considerations, it should be possible to favor the anti-tumor immune response acting on TME. First, we will review the molecular mechanisms involved in MSC-mediated regulation of immune response. Second, we will focus on the experimental data supporting that it is possible to convert TME from immunosuppressive to immunostimulant, specifically targeting MSC.

Direct and Intestinal Epithelial Cell-Mediated Effects of TLR8 Triggering on Human Dendritic Cells, CD14+CD16+ Monocytes and γδ T Lymphocytes

Toll-like receptor (TLR)7/8 plays a crucial role in host recognition/response to viruses and its mucosal expression directly correlates with intestinal inflammation. The aim of this study was to investigate the role of TLR7/8 stimulation of intestinal epithelium in shaping the phenotype and functions of innate immunity cell subsets, and to define direct and/or epithelial cell-mediated mechanisms of the TLR7/8 agonist R848 immunomodulatory activity. We describe novel, TLR8-mediated, pro- and anti-inflammatory effects of R848 on ex vivo cultured human blood monocytes and γδ T lymphocytes, either induced by direct immune cell stimulation or mediated by intestinal epithelial cells (IEC). Apical stimulation with R848 led to its transport across normal polarized epithelial cell monolayer and resulted in the inhibition of monocyte differentiation toward immunostimulatory dendritic cells and Th1 type response. Furthermore, γδ T lymphocyte activation was promoted following direct exposure of these cells to the agonist. Conversely, a selective enrichment of the CD14⁺CD16⁺ monocyte subpopulation was observed, which required a CCL2-mediated inflammatory response of normal epithelial cells to R848. Of note, a TLR-mediated activation of control γδ T lymphocytes was promoted by inflamed intestinal epithelium from active Crohn's disease patients. This study unravels a novel regulatory mechanism linking the activation of the TLR8 pathway in IEC to the monocyte-mediated inflammatory response, and highlights the capacity of the TLR7/8 agonist R848 to directly enhance the activation of γδ T lymphocytes. Overall these results expand the range of cell targets and immune responses controlled by TLR8 triggering that may contribute to the antiviral response, to chronic inflammation, as well as to the adjuvant activity of TLR8 agonists, highlighting the role of intestinal epithelium microenvironment in shaping TLR agonist-induced responses.

Potential Role of Vδ2+ γδ T Cells in Regulation of Immune Activation in Primary HIV Infection

Although conventional regulatory T cells (Tregs) are sufficient in controlling low residual T-cell activation in ART-treated patients, they are not efficient in controlling exaggerated immune activation associated with high levels of HIV replication in primary HIV infection (PHI). Our previous data suggested that double negative (DN) T cells including mainly γδ DN T cells play a role in the control of immune activation in PHI. Since γδ T cells are capable of exerting regulatory functions, we investigated their implication as Tregs in PHI as well as chronic HIV infection (CHI). In a cross-sectional study of 58 HIV-infected patients, in the primary and the chronic phase either ART-treated or untreated (UT), we analyzed phenotype and cytokine production of γδ T cells using flow cytometry. Cytokine production was assessed following in vitro stimulation with isopentenyl pyrophosphate or plate-bound anti-CD3/anti-CD28 monoclonal antibodies. We found that the proportion of γδ T cells negatively correlated with CD8 T-cell activation in PHI patients. Furthermore, we found that in these patients, the Vδ2 receptor bearing (Vδ2⁺) γδ T cells were strongly activated, exhibited low terminal differentiation, and produced the anti-inflammatory cytokine, TGF-β. In contrast, in UT-CHI, we observed a remarkable expansion of γδ T cells, where the Vδ2⁺ γδ T cells comprised of an elevated proportion of terminally differentiated cells producing high levels of IFN-γ but very low levels of TGF-β. We also found that this loss of regulatory feature of γδ T cells in CHI was a lasting impairment as we did not find recovery of TGF-β production even in ART-CHI patients successfully treated for more than 5 years. Our data therefore suggest that during the primary HIV infection, Vδ2⁺ γδ T cells may act as Tregs controlling immune activation through production of TGF-β. However, in CHI, γδ T cells transform from an anti-inflammatory into pro-inflammatory cytokine profile and participate in sustenance of immune activation.

Dual Face of Vγ9Vδ2-T Cells in Tumor Immunology: Anti- versus Pro-Tumoral Activities

Vγ9Vδ2-T cells are considered as potent effector cells for tumor immunotherapy through directly killing tumor cells and indirectly regulating other innate and adaptive immune cells to establish antitumoral immunity. The antitumoral activity of Vγ9Vδ2-T cells is governed by a complicated set of activating and inhibitory cell receptors. In addition, cytokine milieu in tumor microenvironment can also induce the pro-tumoral activities and functional plasticity of Vγ9Vδ2-T cells. Here, we review the anti- versus pro-tumoral activities of Vγ9Vδ2-T cells and discuss the mechanisms underlying the recognition, activation, differentiation and regulation of Vγ9Vδ2-T cells in tumor immunosurveillance. The comprehensive understanding of the dual face of Vγ9Vδ2-T cells in tumor immunology may improve the therapeutic efficacy and clinical outcomes of Vγ9Vδ2-T cell-based tumor immunotherapy.

Lung-resident γδ T cells and their roles in lung diseases

γδ T cells are greatly enriched in mucosal and epithelial sites, such as the skin, respiratory, digestive and reproductive tracts, and they are defined as tissue-resident immune cells. In these tissues, the characteristics and biological roles of γδ T cells are distinguished from each other. The lungs represent the most challenging immunological dilemma for the host, and they have their own effective immune system. The abundance of γδ T cells, an estimated 8-20% of resident pulmonary lymphocytes in the lung, maintains lung tissue homeostasis. In this review, we summarize the recent research progress regarding lung-resident γδ T cells, including their development, residency and immune characteristics, and discuss the involvement of γδ T cells in infectious diseases of the lung, including bacterial, viral and fungal infections; lung allergic disease; lung inflammation and fibrosis; and lung cancer.

Immunosurveillance by human γδ T lymphocytes: the emerging role of butyrophilins

In contrast to conventional T lymphocytes, which carry an αβ T-cell receptor and recognize antigens as peptides presented by major histocompatibility complex class I or class II molecules, human γδ T cells recognize different metabolites such as non-peptidic pyrophosphate molecules that are secreted by microbes or overproduced by tumor cells. Hence, γδ T cells play a role in immunosurveillance of infection and cellular transformation. Until recently, it has been unknown how the γδ T-cell receptor senses such pyrophosphates in the absence of known antigen-presenting molecules. Recent studies from several groups have identified a unique role of butyrophilin (BTN) protein family members in this process, notably of BTN3A1. BTNs are a large family of transmembrane proteins with diverse functions in lipid secretion and innate and adaptive immunity. Here we discuss current models of how BTN molecules regulate γδ T-cell activation. We also address the implications of these recent findings on the design of novel immunotherapeutic strategies based on the activation of γδ T cells.

Zoledronate can induce colorectal cancer microenvironment expressing BTN3A1 to stimulate effector γδ T cells with antitumor activity

Amino-bis-phosphonates (N-BPs) such as zoledronate (Zol) have been used in anticancer clinical trials due to their ability to upregulate pyrophosphate accumulation promoting antitumor Vγ9Vδ2 T cells. The butyrophilin 3A (BTN3A, CD277) family, mainly the BTN3A1 isoform, has emerged as an important structure contributing to Vγ9Vδ2 T cells stimulation. It has been demonstrated that the B30.2 domain of BTN3A1 can bind phosphoantigens (PAg) and drive the activation of Vγ9Vδ2 T cells through conformational changes of the extracellular domains. Moreover, BTN3A1 binding to the cytoskeleton, and its consequent membrane stabilization, is crucial to stimulate the PAg-induced tumor cell reactivity by human Vγ9Vδ2 T cells. Aim of this study was to investigate the relevance of BTN3A1 in N-BPs-induced antitumor response in colorectal cancer (CRC) and the cell types involved in the tumor microenvironment. In this paper, we show that (i) CRC, exposed to Zol, stimulates the expansion of Vδ2 T lymphocytes with effector memory phenotype and antitumor cytotoxic activity, besides sensitizing cancer cells to γδ T cell-mediated cytotoxicity; (ii) this effect is partially related to BTN3A1 expression and in particular with its cellular re-distribution in the membrane and cytoskeleton-associated fraction; (iii) BTN3A1 is detected in CRC at the tumor site, both on epithelial cells and on tumor-associated fibroblasts (TAF), close to areas infiltrated by Vδ2 T lymphocytes; (iv) Zol is effective in stimulating antitumor effector Vδ2 T cells from ex-vivo CRC cell suspensions; and (v) both CRC cells and TAF can be primed by Zol to trigger Vδ2 T cells.

CD8αβ+ γδ T Cells: A Novel T Cell Subset with a Potential Role in Inflammatory Bowel Disease

γδ T cells have been attributed a wide variety of functions, which in some cases may appear as contradictory. To better understand the enigmatic biology of γδ T cells it is crucial to define the constituting subpopulations. γδ T cells have previously been categorized into two subpopulations: CD8αα⁺ and CD8^- cells. In this study we have defined and characterized a novel subset of human γδ T-cells expressing CD8αβ. These CD8αβ⁺ γδ T cells differed from the previously described γδ T cell subsets in several aspects, including the degree of enrichment within the gut mucosa, the activation status in blood, the type of TCRδ variant used in blood, and small but significant differences in their response to IL-2 stimulation. Furthermore, the novel subset expressed cytotoxic mediators and CD69, and produced IFN-γ and TNF-α. In patients with active inflammatory bowel disease the mucosal frequencies of CD8αβ⁺ γδ T cells were significantly lower as compared with healthy controls, correlated negatively with the degree of disease activity, and increased to normal levels as a result of anti-TNF-α therapy. In conclusion, our results demonstrate that CD8αβ⁺ γδ T cells constitute a novel lymphocyte subset, which is strongly enriched within the gut and may play an important role in gut homeostasis and mucosal healing in inflammatory bowel disease.