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Developing an effective Staphylococcus aureus (S. aureus) vaccine has been a challenging endeavor, as demonstrated by numerous failed clinical trials over the years. In this study, we formulated a vaccine containing a highly conserved moonlighting protein, the pyruvate dehydrogenase complex E2 subunit (PDHC), and showed that it induced strong protective immunity against epidemiologically relevant staphylococcal strains in various murine disease models. While antibody responses contributed to bacterial control, they were not essential for protective immunity in the bloodstream infection model. Conversely, vaccine-induced systemic immunity relied on γδ T cells. It has been suggested that prior S. aureus exposure may contribute to the reduction of vaccine efficacy. However, PDHC-induced protective immunity still facilitated bacterial clearance in mice previously exposed to S. aureus. Collectively, our findings indicate that PDHC is a promising serotype-independent vaccine candidate effective against both methicillin-sensitive and methicillin-resistant S. aureus isolates. [ABSTRACT FROM AUTHOR]

Cholangiocarcinoma (CCA) is a rare disease characterized by malignant cells derived from the epithelial cells of the biliary duct system. Despite extensive treatments, the prognosis for CCA remains poor, emphasizing the critical need for the development of novel treatments. Considerable attention has been directed towards innate immune effector cells, which can recognize tumor cells independently of the major histocompatibility complex, laying the foundation for the development of off-the-shelf drugs. In this study, we cultured innate immune cells obtained from the peripheral blood of healthy adults and conducted a comparative analysis of the effector functions against CCA cell lines by Vδ2 γδ T cells and NK cells. This analysis was performed using standard short- and long-term cytotoxicity assays, as well as ELISA for IFN-γ. Vδ2 γδ T cells demonstrated cytotoxicity and IFN-γ production in response to CCA cells in a TCR-dependent manner, particularly in the presence of tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino)ethylidene-1,1-bisphosphonate, a bisphosphonate prodrug. In contrast, direct killing and antibody-dependent cellular cytotoxicity were relatively slow and weak. Conversely, NK cells displayed potent, direct cytotoxicity against CCA cells. In summary, both Vδ2 γδ T cells and NK cells show promise as innate immune effector cells for adoptive transfer therapy in the context of CCA. [ABSTRACT FROM AUTHOR]

Background: Currently, there is a lack of effective indicators for predicting the efficacy of immunotherapy in patients with advanced hepatocellular carcinoma (HCC). This study aimed to investigate the expression and prognostic value of peripheral T lymphocyte subsets in advanced HCC. Methods: Patients with advanced HCC who were treated with immune checkpoint inhibitors (ICIs) from December 2021 to December 2023 were included in the study. Flow cytometry was used to detect lymphocyte subsets before treatment. The patients were divided into disease control (DC) and nondisease control (nDC) groups based on treatment efficacy. Relationships between the clinical characteristics/peripheral T lymphocytes and immunotherapy efficacy were analyzed. The effectiveness of peripheral T lymphocyte subsets in predicting immunotherapy efficacy for patients with advanced HCC was analyzed using receiver operating characteristic (ROC) curves. Results: A total of 40 eligible patients were included in this study. Non-DC was significantly associated with higher albumin-bilirubin (ALBI) scores. The percentages of γδ+Vδ2+PD1+ T cells and γδ+Vδ2+Tim3+ T cells were greater in the nDC group than in the DC group. Multivariable regression analysis revealed that the ALBI score and T lymphocytes expressing γδ+Vδ2+PD1+ and γδ+Vδ2+Tim3+ were founded to be independent influencing factors. The area under the ROC curve (AUC) values for these combinations was 0.944 (95% CI, 0.882 ~ 1.000). Conclusions: The calculation of the ALBI score and determination of the percentages CD3+γδ+Vδ2+PD1+ T lymphocytes and CD3+γδ+Vδ2+Tim3+ T lymphocytes in the peripheral blood of patients with advanced HCC are helpful for predicting the patients’ responses to ICIs, helping to screen patients who may clinically benefit from immunotherapy. Retrospectively registered: number: ChiCTR2400080409, date of registration: 2024-01-29. [ABSTRACT FROM AUTHOR]

Human γδ T cells are a subtype of T cells with innate and adaptive characteristics, playing important roles in immune responses, infections, and tumor killing. They have emerged as promising candidates for tumor immunotherapy and adoptive cell therapy in recent years. Umbilical cord blood is rich in various lymphoid progenitor cells, characterized by low immunogenicity, and also contains γδ T cells, making it a potential candidate source for γδ T cell immunotherapy. This review discusses the current research progress on umbilical cord blood γδ T cells. [ABSTRACT FROM AUTHOR]

Infection at barrier sites, e.g., skin, activates local immune defenses that limit pathogen spread, while preserving tissue integrity. Phenotypically distinct γδ T cell populations reside in skin, where they shape immunity to cutaneous infection prior to onset of an adaptive immune response by conventional αβ CD4+ (TCD4+) and CD8+ (TCD8+) T cells. To examine the mechanisms used by γδ T cells to control cutaneous virus replication and tissue pathology, we examined γδ T cells after infection with vaccinia virus (VACV). Resident γδ T cells expanded and combined with recruited γδ T cells to control pathology after VACV infection. However, γδ T cells did not play a role in control of local virus replication or blockade of systemic virus spread. We identified a unique wound healing signature that has features common to, but also features that antagonize, the sterile cutaneous wound healing response. Tissue repair generally occurs after clearance of a pathogen, but viral wound healing started prior to the peak of virus replication in the skin. γδ T cells contributed to wound healing through induction of multiple cytokines/growth factors required for efficient wound closure. Therefore, γδ T cells modulate the wound healing response following cutaneous virus infection, maintaining skin barrier function to prevent secondary bacterial infection. [ABSTRACT FROM AUTHOR]

Immuno-oncology has traditionally focused on conventional MHC-restricted αβ T cells. Yet, unconventional γδ T cells, which kill tumor cells in an MHC-unrestricted manner, display characteristics of effector activity and stemness without exhaustion and are nearly universally observed in human gynecologic malignancies, correlating with improved outcomes. These cells do not have a clear counterpart in mice but are also found in the healthy female reproductive tract. Interventions that modulate their in vivo activity, or cellular therapies utilizing γδ T cells as an allogeneic, "off-the-shelf" platform (e.g., for chimeric antigen receptor expression) hold significant potential against challenging tumors like ovarian cancer, which has been stubbornly resistant to the immune checkpoint inhibitors that change the landscape of other human tumors. Here, we discuss recent discoveries on the specific populations of γδ T cells that infiltrate human gynecologic cancers, their anti-tumor activity, and the prospect of redirecting their effector function against tumor cells to develop a new generation of immunotherapies that extends beyond the traditional αβ T cell-centric view of the field. [ABSTRACT FROM AUTHOR]

γδ T cells and natural killer (NK) cells have attracted much attention as promising effector cell subsets for adoptive transfer for use in the treatment of malignant and infectious diseases, because they exhibit potent cytotoxic activity against a variety of malignant tumors, as well as virus-infected cells, in a major histocompatibility complex (MHC)-unrestricted manner. In addition, γδ T cells and NK cells express a high level of CD16, a receptor required for antibody-dependent cellular cytotoxicity. Adult T-cell leukemia–lymphoma (ATL) is caused by human T-lymphotropic virus type I (HTLV-1) and is characterized by the proliferation of malignant peripheral CD4+ T cells. Although several treatments, such as chemotherapy, monoclonal antibodies, and allogeneic hematopoietic stem cell transplantation, are currently available, their efficacy is limited. In order to develop alternative therapeutic modalities, we considered the possibility of infusion therapy harnessing γδ T cells and NK cells expanded using a novel nitrogen-containing bisphosphonate prodrug (PTA) and interleukin (IL)-2/IL-18, and we examined the efficacy of the cell-based therapy for ATL in vitro. Peripheral blood samples were collected from 55 patients with ATL and peripheral blood mononuclear cells (PBMCs) were stimulated with PTA and IL-2/IL-18 for 11 days to expand γδ T cells and NK cells. To expand NK cells alone, CD3+ T-cell-depleted PBMCs were cultured with IL-2/IL-18 for 10 days. Subsequently, the expanded cells were examined for cytotoxicity against ATL cell lines in vitro. The proportion of γδ T cells in PBMCs was markedly low in elderly ATL patients. The median expansion rate of the γδ T cells was 1998-fold, and it was 12-fold for the NK cells, indicating that γδ T cells derived from ATL patients were efficiently expanded ex vivo, irrespective of aging and HTLV-1 infection status. Anti-CCR4 antibodies enhanced the cytotoxic activity of the γδ T cells and NK cells against HTLV-1-infected CCR4-expressing CD4+ T cells in an antibody concentration-dependent manner. Taken together, the adoptive transfer of γδ T cells and NK cells expanded with PTA/IL-2/IL-18 is a promising alternative therapy for ATL. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that T cell exhaustion is associated with poor clearance of Hepatitis B virus (HBV). However, whether the expression of exhaustion markers on innate‐like circulating γδ T cells derived from patients with HBV infection correlates with the serum level of vitamin D is not completely understood. In this study, we found that the frequency of circulating Vδ2+ T cell and serum levels of vitamin 25(OH)D3 were significantly decreased in patients with HBV. And serum 25(OH)D3 levels in HBV‐infected patients were negatively correlated with HBV DNA load and PD‐1 expression on γδ T cells. Interestingly, 1α,25(OH)2D3 alleviated the exhaustion phenotype of Vδ2 T cells in HBV‐infected patients and promoted IFN‐β expression in human cytotoxic Vδ2 T cells in vitro. Collectively, these findings demonstrate that vitamin D plays a pivotal role in reversing γδ T‐cell exhaustion and is highly promising target for ameliorating HBV infection. [ABSTRACT FROM AUTHOR]

γδ T cells, especially Vγ9Vδ2 T cells, play an important role in mycobacterial infection. We have identified some Vγ9Vδ2 T cells that recognize protein/peptide antigens derived from mycobacteria, which may induce protective immune responses to mycobacterial infection. To clarify the structural basis of the molecular recognition mechanism, we tried many methods to express the Vγ9Vδ2 T-cell receptor (TCR). The Vγ9Vδ2 TCR was not expressed well in a prokaryotic expression system or a baculovirus expression system, even after extensive optimization. In a mammalian cell expression system, the Vγ9Vδ2 TCR was expressed in the form of a soluble heterodimer, which was suitable for crystal screening. Reduced-temperature cultivation (cold shock) increased the yield of the recombinant TCR. The recombinant purified TCR was used for crystal trials, and crystals that could be used for X-ray diffraction were obtained. Although we have not yet determined the crystal structure of the Vγ9Vδ2 TCR, we have established a procedure for Vγ9Vδ2 TCR expression and purification, which is useful for basic research and potentially for clinical application. [ABSTRACT FROM AUTHOR]

T cells, which are derived from hematopoietic stem cells (HSCs), are the most important components of adaptive immune system. Based on the expression of αβ and γδ receptors, T cells are mainly divided into αβ and γδ T cells. In the thymus, they share common progenitor cells, while undergoing a series of well‐characterized and different developmental processes. N6‐Methyladenosine (m6A), one of the most abundant modifications in mRNAs, plays critical roles in cell development and maintenance of function. Recently, we have demonstrated that the depletion of m6A demethylase ALKBH5 in lymphocytes specifically induces an expansion of γδ T cells through the regulation of Jag1/Notch2 signaling, but not αβ T cells, indicating a checkpoint role of ALKBH5 and m6A modification in the early development of γδ T cells. Based on previous studies, many key pathway molecules, which exert dominant roles in γδ T cell fate determination, have been identified as the targets regulated by m6A modification. In this review, we mainly summarize the potential regulation between m6A modification and these key signaling molecules in the γδ T cell lineage commitment, to provide new perspectives in the checkpoint of γδ T cell development. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this review is to discuss the role of γδ T cells played in humoral immune responses. Background: The γδ T cell receptor (γδ TCR) recognizes antigens, including haptens and proteins, in an MHC-independent manner. The recognition of these antigens by γδ TCRs crosses antigen recognition by the B cell receptors (BCRs), suggesting that γδ T cells may be involved in the process of antigen recognition and activation of B cells. However, the role of γδ T cells in humoral immune responses is still less clear. Methods: The kinds of literature about the γδ T cell-B cell interaction were searched on PubMed with search terms, such as γδ T cells, antibody, B cell responses, antigen recognition, and infection. Results: Accumulating evidence indicates that γδ T cells, independent of αβ T cells, participate in multiple steps of humoral immunity, including B cell maturation, activation and differentiation, antibody production and class switching. Mechanically, γδ T cells affect B cell function by directly interacting with B cells, secreting cytokines, or modulating αβ T cells. Conclusion: In this review, we summarize current knowledge on how γδ T cells take part in the humoral immune response, which may assist future vaccine design. [ABSTRACT FROM AUTHOR]

Background: γδ T cells for tumor cell immunotherapy has recently become a hot topic. Objective: To investigate the stimulation of expanded γδ T cells in vitro to kill liver cancer cells and its mechanism, and in vivo validation. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated and amplified. The proportion of γδ T cells in T cells was determined using flow cytometry. γδ T cells were selected as effector cells, and HepG2 cells as target cells in the cytotoxicity experiment. NKG2D blocker was used to block effector cells from identifying target cells, and PD98059 was used to block intracellular signaling pathways. The nude mice tumor model was established in two batches, the tumor growth curve was drawn, and the tumor formation effect was tested using small animal imager to verify the killing effect of γδ T cells. Results: The γδ T cells in the three experimental groups exhibited a large amount of amplification (P < 0.01). In the killing experiment, the killing rate of γδ T cells stimulated by zoledronate (ZOL) in the experimental group was significantly higher than that in the HDMAPP group and the Mycobacterium tuberculosis H37Ra strain (Mtb‑Hag) group (P < 0.05). The blocking effect of PD98059 is stronger than that of the NKG2D blocker (P < 0.05). Among them, in the HDMAPP group, when the target ratio was 40:1, the NKG2D blocker exhibited a significant blocking effect (P < 0.05). Alternatively, in the ZOL group, when the effect ratio was 10:1, the effector cells were blocked significantly after treatment using PD98059 (P < 0.05). In vivo experiments verified the killing effect of γδ T cells. According to the tumor growth curve, there was a difference between the experimental and control groups after cell treatment (P < 0.05). Conclusion: ZOL has high amplification efficiency and a positive effect on killing tumor cells. [ABSTRACT FROM AUTHOR]

Background: γδ T cells for tumor cell immunotherapy has recently become a hot topic. Objective: To investigate the stimulation of expanded γδ T cells in vitro to kill liver cancer cells and its mechanism, and in vivo validation. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated and amplified. The proportion of γδ T cells in T cells was determined using flow cytometry. γδ T cells were selected as effector cells, and HepG2 cells as target cells in the cytotoxicity experiment. NKG2D blocker was used to block effector cells from identifying target cells, and PD98059 was used to block intracellular signaling pathways. The nude mice tumor model was established in two batches, the tumor growth curve was drawn, and the tumor formation effect was tested using small animal imager to verify the killing effect of γδ T cells. Results: The γδ T cells in the three experimental groups exhibited a large amount of amplification (P < 0.01). In the killing experiment, the killing rate of γδ T cells stimulated by zoledronate (ZOL) in the experimental group was significantly higher than that in the HDMAPP group and the Mycobacterium tuberculosis H37Ra strain (Mtb-Hag) group (P < 0.05). The blocking effect of PD98059 is stronger than that of the NKG2D blocker (P < 0.05). Among them, in the HDMAPP group, when the target ratio was 40:1, the NKG2D blocker exhibited a significant blocking effect (P < 0.05). Alternatively, in the ZOL group, when the effect ratio was 10:1, the effector cells were blocked significantly after treatment using PD98059 (P < 0.05). In vivo experiments verified the killing effect of γδ T cells. According to the tumor growth curve, there was a difference between the experimental and control groups after cell treatment (P < 0.05). Conclusion: ZOL has high amplification efficiency and a positive effect on killing tumor cells. [ABSTRACT FROM AUTHOR]

Gamma delta (γδ) T cells play a significant role in the prevention of viral infection and tumor surveillance in mammals. Although the involvement of γδ T cells in Marek's disease virus (MDV) infection has been suggested, their detailed contribution to immunity against MDV or the progression of Marek's disease (MD) remains unknown. In the current study, T cell receptor (TCR)γδ-activated peripheral blood mononuclear cells (PBMCs) were infused into recipient chickens and their effects were examined in the context of tumor formation by MDV and immunity against MDV. We demonstrated that the adoptive transfer of TCRγδ-activated PBMCs reduced virus replication in the lungs and tumor incidence in MDV-challenged chickens. Infusion of TCRγδ-activated PBMCs induced IFN-γ-producing γδ T cells at 10 days post-infection (dpi), and degranulation activity in circulating γδ T cell and CD8α+ γδ T cells at 10 and 21 dpi in MDV-challenged chickens. Additionally, the upregulation of IFN-γ and granzyme A gene expression at 10 dpi was significant in the spleen of the TCRγδ-activated PBMCs-infused and MDV-challenged group compared to the control group. Taken together, our results revealed that TCRγδ stimulation promotes the effector function of chicken γδ T cells, and these effector γδ T cells may be involved in protection against MD. [ABSTRACT FROM AUTHOR]

Simple Summary: Patients with relapsed and refractory T-cell malignancies have poor outlook and limited treatment options. Recently, adoptive cell therapy has emerged as a promising therapy for patients with T-cell malignancies. In this review, we examine the current progress on adoptive cell therapy for T-cell malignancies and discuss the potential future directions. T-cell malignancies are often aggressive and associated with poor prognoses. Adoptive cell therapy has recently shown promise as a new line of therapy for patients with hematological malignancies. However, there are currently challenges in applying adoptive cell therapy to T-cell malignancies. Various approaches have been examined in preclinical and clinical studies to overcome these obstacles. This review aims to provide an overview of the recent progress on adoptive cell therapy for T-cell malignancies. The benefits and drawbacks of different types of adoptive cell therapy are discussed. The potential advantages and current applications of innate immune cell-based adoptive cell therapy for T cell malignancies are emphasized. [ABSTRACT FROM AUTHOR]

Idiopathic pulmonary fibrosis is a chronic intractable lung disease, leading to respiratory failure and death. Although anti-fibrotic agents delay disease progression, they are not considered curative treatments, and alternative modalities have attracted attention. We examined the effect of human γδ T cells on collagen type I in lung fibroblasts. Collagen type I was markedly reduced in a γδ T cell number-dependent manner following treatment with γδ T cells expanded with tetrakis-pivaloxymethyl 2-(thiazole-2-ylamino) ethylidene-1,1-bisphosphonate (PTA) and interleukin-2. Collagen type I levels remained unchanged on addition of γδ T cells to the culture system through a trans-well culture membrane, suggesting that cell–cell contact is essential for reducing its levels in lung fibroblasts. Re-stimulating γδ T cells with (E)-4-hydroxy-3-methylbut-2-enyl diphosphate (HMBPP) reduced collagen type I levels without cell–cell contact, indicating the existence of HMBPP-induced soluble anti-fibrotic factors in γδ T cells. Adding anti-interferon-γ (IFN-γ)-neutralizing mAb restored collagen type I levels, demonstrating that human γδ T cell-derived IFN-γ reduces collagen type I levels. Conversely, interleukin-18 augmented γδ T cell-induced suppression of collagen type I. Therefore, human γδ T cells reduce collagen levels in lung fibroblasts via two distinct mechanisms; adoptive γδ T cell transfer is potentially a new therapeutic candidate. [ABSTRACT FROM AUTHOR]

γδ T cells expressing Vγ5Vδ1 TCR originally develop in the embryonic thymus and migrate to the epidermis, forming dendritic epidermal T cells (DETCs) throughout life. It is thought that a TCR signal is essential for their development; e.g. lack of TCR signal-transducer ZAP70 significantly decreases DETC numbers. On the other hand, lack of ZAP70 does not affect Vγ5Vδ1+ T cells in the embryonic thymus; thus, the involvement of TCR signaling remains elusive. Here, we used SKG mice with attenuated TCR signaling rather than gene-knockout mice. In SKG mice, Vγ5+ T cells showed a marked decrease [10% of wild-type (WT)] in adult epidermis; however, there was just a moderate decrease (50% of WT) in the embryonic thymus. In early postnatal epidermis in SKG mice, substantial numbers of Vγ5+ T cells were observed (50% of WT). Their activation markers including CD122, a component of the IL-15 receptor indispensable for DETC proliferation, were comparable to those of WT. However, the Vγ5+ T cells in SKG mice did not proliferate and form DETCs thereafter. Furthermore, in SKG/+ mice, the number of thymic Vγ5Vδ1+ T cells increased, compared to SKG mice; however, the number of DETCs remained significantly lower than in WT, similar to SKG mice. Our results suggest that signaling via Vγ5Vδ1 TCR is indispensable for DETC development, with distinct contributions to embryonic development and postnatal proliferation. [ABSTRACT FROM AUTHOR]

In hepatocellular carcinoma (HCC), γδ T cells participate in mediating the anti‐tumour response and are linked with a positive prognosis. However, these cells can become pro‐tumoural in the tumour microenvironment (TME). We aimed to decipher the immune landscape and functional states of HCC‐infiltrating γδ T cells to provide fundamental evidence for the adoptive transfer of allogeneic Vδ2+ γδ T cells in HCC immunotherapy. We performed single‐cell RNA sequencing (scRNA‐seq) on γδ T cells derived from HCC tumours and healthy donor livers. Confocal microscopy, flow cytometry and a Luminex assay were applied to validate the scRNA‐seq findings. The γδ T cells in the HCC TME entered G2/M cell cycle arrest, and expressed cytotoxic molecules such as interferon‐gamma and granzyme B, but were functionally exhausted as indicated by upregulated gene and protein LAG3 expression. The γδ T cells in the HCC TME were dominated by the LAG3+Vδ1+ population, whereas the Vδ2+ γδ T population was greatly depleted. Moreover, glutamine metabolism of γδ T cells was markedly upregulated in the glutamine‐deficient TME. Both in vitro and in vivo experiments showed that glutamine deficiency upregulated LAG3 expression. Finally, our results indicated that ex vivo‐expanded Vδ2+ γδ T cells from healthy donor could complement the loss of T cell receptor clonality and effector functions of HCC‐derived γδ T cells. This work deciphered the dysfunctional signatures of HCC‐infiltrating γδ T cells in the HCC TME, providing scientific support for the use of allogeneic Vδ2+ γδ T cells in HCC cellular therapy. [ABSTRACT FROM AUTHOR]

Marek's disease (MD) vaccines reduce the incidence of MD but cannot control virus shedding. To develop new vaccines, it is essential to elucidate mechanisms of immunity to Marek's disease virus (MDV) infection. In this regard, gamma delta (γδ) T cells may play a significant role in prevention of viral spread and tumor surveillance. Here we demonstrated that MDV vaccination induced interferon (IFN)-γ+CD8α+ γδ T cells and transforming growth factor (TGF)-β+ γδ T cells in lungs. γδ T cells from MDV-infected chickens exhibited cytotoxic activity. Importantly, γδ T cells from the vaccinated/challenged group exhibited maximum cytotoxic activity following ex vivo stimulation. These results suggest that MDV vaccines activate effector γδ T cells which may be involved in the development of protective immune responses against MD. Further, it was demonstrated that MDV infection increases the frequency of a subpopulation of γδ T cells expressing membrane-bound TGF-β in MDV-infected birds. • Marek's disease vaccination induced IFN-γ+CD8α+ and TGF-β+ γδ T cells in lungs, spleen, and skin. • γδ T cells from the vaccinated/challenged chickens exhibited cytotoxic activity following ex vivo stimulation. • MDV vaccines activate effector γδ T cells which may be involved in the development of protective immune responses against MD. [ABSTRACT FROM AUTHOR]

Standard treatment of colorectal cancer (CRC) improves the prognosis of CRC patients, but it is still intractable to control the progression of metastatic CRC. Immune microenvironment and immunotherapies of CRC have received extensive attention in recent years, but present immunotherapies of CRC have mainly focused on T cells and therapeutic response is only observed in a small proportion of patients. Innate immune cells are the first-line of defense in the development of malignancies. Natural killer (NK) cells, NKT cells and γδT cells are three types of innate cells of lymphoid origin and show cytotoxicity against various tumor cells including CRC. Besides, in the development of CRC, they can also be inhibited or express regulatory type, promoting tumor progression. Researches about anti-tumorigenic and pro-tumorigenic mechanisms of these cells are ongoing and regulation of these cells is also being unearthed. Meanwhile, immunotherapies using these cells more or less have shown efficacy in animal models and some of them are under exploration in clinical trials. This review provides an overview of intrinsic properties of NK cell, NKT cell and γδT cell, and summarizes current related promising treatment strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] The distinct characteristics of γδ T cells determine their vital roles in the formation of local immune responses and contribute to tissue homeostasis. However, the heterogeneity of γδ T cells across tissues remains unclear. By combining transcriptional and chromatin analyses with a truly unbiased fashion, we constructed a single-cell transcriptome and chromatin accessibility landscape of mouse γδ T cells in the lymph, spleen, and thymus. We also revealed the heterogeneity of γδ T1 and γδ T17 cells across these tissues and inferred their potential regulatory mechanisms. In the thymus, we reconstructed the developmental trajectory and gained further insights into the signature genes from the mature stage, intermediate stage, and immature stage of γδ T cells on the basis of single-cell RNA sequencing and single-cell assay for transposase-accessible chromatin sequencing data. Notably, a novel Gzma + γδ T cell subset was identified with immature properties and only localized to the thymus. Finally, NR1D1, a circadian transcription factor (TF), was validated as a key and negative regulator of γδ T17 cell differentiation by performing a combined analysis of TF motif enrichment, regulon enrichment, and Nr1d1 knockout mice. In summary, our data represent a comprehensive mapping on the transcriptome and chromatin accessibility dynamics of mouse γδ T cells, providing a valuable resource and reference for future studies on γδ T cells. [ABSTRACT FROM AUTHOR]

γδ T cells are a highly versatile immune lineage involved in host defense and homeostasis, but questions remain around their heterogeneity, precise function and role during health and disease. We used multi−parametric flow cytometry, dimensionality reduction, unsupervised clustering, and self-organizing maps (SOM) to identify novel γδ T cell naïve/memory subsets chiefly defined by CD161 expression levels, a surface membrane receptor that can be activating or suppressive. We used middle-to-old age individuals given immune blockade is commonly used in this population. Whilst most Vδ1+subset cells exhibited a terminal differentiation phenotype, Vδ1− subset cells showed an early memory phenotype. Dimensionality reduction revealed eight γδ T cell clusters chiefly diverging through CD161 expression with CD4 and CD8 expression limited to specific subpopulations. Comparison of matched healthy elderly individuals to bronchiectasis patients revealed elevated Vδ1+ terminally differentiated effector memory cells in patients potentially linking this population with chronic proinflammatory disease. [ABSTRACT FROM AUTHOR]

• IFN-γ, IL-17A and IL-22 related to γδ T cells are evaluated in Behçet's disease (BD) • Functional states of both CD4+ and γδ T cells are compared in ex vivo samples • Only IFN-γ production was increased in γδ T cells of active BD patients • IL-17A and IL-17A/IFN-γ double producer CD4+ T cells were increased in active BD • Along with CD4+ T cells, γδ T cells have complementary roles in BD Involvement of γδ T cells is implicated in the pathogenesis of Behçet's disease (BD) as a bridge between innate and adaptive responses. IL-17 and IL-22 have also been shown to participate in the BD pathogenesis in addition to IFN-γ. Mainly CD4+ T cells are investigated previously for the production of these inflammatory cytokines. In this study, the role of γδ T cells in cytokine-related mechanisms was evaluated in BD in comparison to CD4+ T cells. Surface expression of markers for functional states of both CD4+ and γδ T cells were compared in ex vivo samples collected from patients with BD and healthy controls (HC). Sixteen active BD (a-BD), 9 inactive BD (i-BD) patients and 25 HC were investigated. The expression of CD161, CCR6 as markers for IL-17 producing cells were analyzed on γδ and CD4+ T cells. IFN-γ, IL-17A, IL-22, as well as CD107a (LAMP1) and CD16 (FcγRIII) were evaluated in both cell subtypes after in vitro stimulation. Only IFN-γ production was increased in γδ T cells of a-BD patients. There was no difference in increase of CD107a or decrease of CD16 surface expression on γδ T cells upon stimulation between the groups. Ex vivo IL-17A and both IL-17A/IFN-γ production and expression of CD161, CCR6 by CD4+ T cells were increased in a-BD. Along with CD4+ T cells, γδ T cells have complementary roles in cytokine production in BD. Higher IFN-γ production of γδ T cells suggests the role of an environmental triggers in BD pathogenesis, whereas IL-17 related activity is mainly provided by CD4+ T cells. [ABSTRACT FROM AUTHOR]

Impairment of antigen-presenting functions is a key mechanism contributing to sepsis-induced immunosuppression. Recently, γδ T cells have been demonstrated as professional antigen-presenting cells (APCs); however, their role in sepsis remains unknown. In this in vitro study, the APC function of human peripheral γδ T cells was assessed using samples collected from 42 patients with sepsis and 27 age-matched healthy controls. The APC-related markers HLA-DR, CD27, CD80, and CCR7 on fresh γδT cells were significantly higher in patients with sepsis compared with matched controls; however, they responded poorly to 4-hydroxy-3-methyl-2-butenyl pyrophosphate (HMBPP) stimulation, characterized by the deactivation of these APC markers and impaired proliferation. Furthermore, the adhesion function of γδ T cells, essential for antigen presentation, was greatly reduced in patients with sepsis; for instance, in co-cultures with green fluorescent protein-expressing Escherichia coli, HMBPP-activated γδT cells from healthy individuals adhered to E. coli efficiently, whereas no such phenomenon was observed with respect to γδT cells from patients with sepsis. In line with these results, in co-cultures with isolated CD4+ αβ T cells, HMBPP-activated γδT cells of healthy individuals promoted the efficient proliferation of CD4+ αβ T cells, whereas γδT cells from patients with sepsis did not do so. In conclusion, our findings show that the antigen-presenting function of γδT cells is severely impaired in patients with sepsis and the mechanisms behind need further study. The APC-related markers on fresh γδT cells were significantly higher in patients with sepsis compared with matched controls; however, they responded poorly to 4-hydroxy-3-methyl-2-butenyl pyrophosphate (HMBPP) stimulation, characterized by the deactivation of these APC markers and impaired proliferation. HMBPP-activated γδT cells from healthy individuals adhered to E. coliefficiently and promoted the efficient proliferation of CD4+ aß T cells, whereas γδT cells from patients with sepsis did not do so. In conclusion, our findings show that the antigen-presenting function of γδT cells is severely impaired in patients with sepsis. [ABSTRACT FROM AUTHOR]

Behcet’s disease （BD） is a systemic inflammatory disorder characterized by orogenital ulcerations and uveitis. Pathology of BD suggests a vasculitis with mixed-cellular perivascular infiltrates and thrombotic tendency. Its pathogenesis is obscure. Environmental agent，genetic predisposition and immune-dysregulation involving T cells are reported to have a role in the pathogenesis of BD，which includes γδT cells featuring innate immunity，recognition of specific antigens，antigen presenting，CD4+ T cells and CD8+ T cells featuring adaptive immunity. Th1/Th17 expansion and Treg impairment are the central futures of altered T-cell homeostasis. All of those have been suggested to be responsible for inducing and/or maintaining the proinflammatory environment characteristic of BD. Here，we review the features of the phenotypes of T cell subsets in BD，by which modify the immune conducted inflammation，and the transformation of treatment and future target therapy. [ABSTRACT FROM AUTHOR]

Background: The precancerous disease of breast cancer is an inevitable stage in the tumorigenesis and development of breast neoplasms. Quercetin (Que) has shown great potential in breast cancer treatment by inhibiting cell proliferation and regulating T cell function. γδ T cells are a class of nontraditional T cells that have long attracted attention due to their potential in immunotherapy. In this study, we revealed the immunomodulatory function of Que through regulation of the JAK/STAT1 signaling pathway, which was followed by the synergistic killing of breast cancer cells. Methods: In the experimental design, we first screened target genes with or without Que treatment, and we intersected the Que target with the disease target by functional enrichment analysis. Second, MCF-10A, MCF-10AT, MCF-7 and MDA-MB-231 breast cancer cell lines were treated with Que for 0 h, 24 h and 48 h. Then, we observed the expression of its subsets by coculturing Que and γδ T cells and coculturing Que and γδ T cells with breast tumor cells to investigate their synergistic killing effect on tumor cells. Finally, Western blotting was used to reveal the changes in proteins related to the JAK/STAT1 signaling pathway after Que treatment in MCF-10AT and MCF-7 cells for 48 h. Results: The pathway affected by Que treatment was the JAK/STAT1 signaling pathway and was associated with precancerous breast cancer, as shown by network pharmacology analysis. Que induced apoptosis of MCF-10AT, MCF-7 and MDA-MB-231 cells in a time- and concentration-dependent manner (P < 0.05). Most importantly, Que promoted the differentiation of γδ T cells into the Vδ2 T cell subpopulation. The best ratio of effector cells to target cells (E/T) was 10:1, the killing percentages of γδ T cells against MCF-10A, MCF-10AT, MCF-7, and MDA-MB-231 were 61.44 ± 4.70, 55.52 ± 3.10, 53.94 ± 2.74, and 53.28 ± 1.73 (P = 0.114, P = 0.486, and P = 0.343, respectively), and the strongest killing effect on precancerous breast cancer cells and breast cancer cells was found when the Que concentration was 5 μM and the E/T ratio was 10:1 (64.94 ± 3.61, 64.96 ± 5.45, 55.59 ± 5.98, and 59.04 ± 5.67, respectively). In addition, our results showed that Que increased the protein levels of IFNγ-R, p-JAK2 and p-STAT1 while decreasing the protein levels of PD-L1 (P < 0.0001). Conclusions: In conclusion, Que plays a synergistic role in killing breast cancer cells and promoting apoptosis by regulating the expression of IFNγ-R, p-JAK2, p-STAT1 and PD-L1 in the JAK/STAT1 signaling pathway and promoting the regulation of γδ T cells. Que may be a potential drug for the prevention of precancerous breast cancer and adjuvant treatment of breast cancer. [ABSTRACT FROM AUTHOR]

Human γδ T cells expressing Vγ9Vδ2 T cell receptors play a crucial role in the innate immune system and have an attracted interest as effector cells in adoptive cellular immunotherapy. However, the efficacy of adoptive cellular immunotherapy for the treatment of tumors requires overcoming the immunosuppressive microenvironment. αβ T cell inhibition in the tumor microenvironment is associated with programmed death-ligand 1 (PD-L1) expression level. Vγ9Vδ2 T cells (abbreviated as γδ T cells here) exert potent cytotoxic effects in various cancers; however, γδ T cell activity in relation to the level of PD-L1 expression in cancer cells remains unclear, and the association between the PD-1/PD-L1 axis and γδ T cell cytotoxicity needs to be investigated. In this study, PD-1 blockade did not increase the cytotoxicity of γδ T cells against PD-L1high cancer cells. However, the anti-PD-L1 monoclonal antibody (mAb) enhanced the cytotoxicity of γδ T cells against a subset of cancer cells, whereas PD-L1 knockdown did not increase the cytotoxicity of γδ T cells. We also found that the expression levels of PD-L1 were positively correlated with the changes of γδ T cells cytotoxicity induced by anti-PD-L1 mAb. These observations suggest that anti-PD-L1 mAb treatment adds ADCC activity to the cytotoxicity of γδ T cells itself against PD-L1high cancer cells. The present results suggest that ex vivo expanded γδ T cells have antitumor activity independently of PD-L1 expression and may be promising effector cells for γδ T cell immunotherapy. • PD-1 blockade by anti-PD-1 mAb did not increase the cytotoxicity of γδ T cells. • PD-L1 knockdown did not increase the cytotoxicity of γδ T cells. • γδ T cells have antitumor activity independently of PD-L1 expression. • Anti -PD-L1 mAb enhanced γδ T cell cytotoxicity against a subset of cancer cells. • Anti -PD-L1 mAb treatment adds ADCC activity to the cytotoxicity of γδ T cells. [ABSTRACT FROM AUTHOR]

Gamma‐delta (γδ) T cells are the bridge between natural and adaptive immunity. In the present study, peripheral blood was collected from 13 patients with advanced schistosomiasis (schistosomiasis group) and 13 uninfected people (control group) to investigate the γδ T cells and their subtypes in human schistosomiasis. Compared with the control group, the proportion of Vδ1 cells and CD27+Vδ1+ cells in the schistosomiasis group increased significantly, while CD27− cells and CD27−Vδ1− cells decreased. Only the level of IL‐17A differed between the groups, being significantly decreased in the schistosomiasis group. In the schistosomiasis group, there were no correlations between the liver fibrosis and subsets of γδ T cells, or the level of cytokines. Additionally, the level of IL‐17A correlated positively with the proportion of CD27− Vδ1− cells. Thus, there was a higher frequency of circulating Vδ1 γδT cells in patients with advanced schistosomiasis. The decreased IL‐17A might be related to the reduction in CD27−Vδ1− cell. [ABSTRACT FROM AUTHOR]

Background: Immune cell infiltration and neuroinflammation are heavily associated with spinal cord injury (SCI). C-C motif chemokine ligand 2/C-C chemokine receptor type 2 (CCL2/CCR2) axis has been identified as a critical role player during the invasion of immune cells to lesions in many diseases. γδ T cells, a subgroup of T cells, manage the course of inflammation response in various diseases; however, it remains unknown whether γδ T cells are recruited to injury site through CCL2/CCR2 signaling and exert the regulation effect on neuroinflammation after SCI.Methods: Basso Mouse Scale (BMS), regularity index, cadence, max contact area, and motor-evoked potential testing (MEP) were measured to determine the neurological function recovery after spinal cord injury. Nissl staining was performed to identify the number of surviving motor neurons at lesion epicenter. Immunofluorescence, Western blot, enzyme-linked immunosorbent assays (ELISA), and quantitative real-time polymerase chain reaction (QRT-PCR) also were employed to evaluate the expression of associated proteins and genes.Results: In this study, we demonstrated that TCRδ-/- mice present improved neurological recovery after SCI. γδ T cell recruitment to the SCI site was significantly reduced and motor functional improvement enhanced in CCL2-/- and CCR2-/- mouse strains. Furthermore, reconstitution of TCRδ-/- mice with γδ T cells extracted from CCR2-/- mice also showed similar results to CCL2 and CCR2 deficient mice.Conclusions: In conclusion, γδ T cell recruitment to SCI site promotes inflammatory response and exacerbates neurological impairment. CCL2/CCR2 signaling is a vital recruitment mechanism of γδ T cells to the SCI site, and it may be taken as a novel therapeutic target for future SCI. [ABSTRACT FROM AUTHOR]

Our previous study reveals that gamma delta (γδ) T cells were activated and dendritic cells (DCs) underwent maturation during the inflammation phase in experimental autoimmune uveitis (EAU) mice, and the interaction between DCs and γδ T cells may significantly exacerbate the development of EAU. However, the interactions between DCs and γδ T cells that can affect DCs maturation to influence EAU development must be further addressed. In this study we showed that mature DC numbers in TCR-δ−/− (KO) EAU mice were lower than those in wild-type (WT) C57BL/6 (B6) mice. The γδ T cells harvested from WT EAU mice secreted more interferon-γ (IFN-γ), however, after blocking IFN-γ, the maturation of DCs was significantly downregulated. By contrast, the percentage of IFN-γ- and IL-17-producing CD4+ T cells in KO EAU mice decreased to a greater extent than that in WT EAU mice during the inflammatory phase. Additionally, the levels of IFN-γ/IL-17 in serum were in agreement with those of CD4+ T cells. Furthermore, after activated γδ T cells injection, the inflammatory symptoms of EAU mice were more aggravated. In vitro co-cultures of both cell types showed that activated γδ T cells may induce DCs to generate higher levels of intracellular cell adhesion molecule-1 (ICAM-1/CD54), CD80, CD83, and CD86. Moreover, co-culture of the two cells may induce the activation of CD4+ T cells. Taken together, our results demonstrated that activated γδ T cells may promote DCs maturation and further enhance the generation of Th1/Th17 cells in EAU mice, resulting in exacerbated EAU. [ABSTRACT FROM AUTHOR]

Intensive worldwide efforts are underway to determine both the pathogenesis of SARS-CoV-2 infection and the immune responses in COVID-19 patients in order to develop effective therapeutics and vaccines. One type of cell that may contribute to these immune responses is the γδ T lymphocyte, which plays a key role in immunosurveillance of the mucosal and epithelial barriers by rapidly responding to pathogens. Although found in low numbers in blood, γδ T cells consist the majority of tissue-resident T cells and participate in the front line of the host immune defense. Previous studies have demonstrated the critical protective role of γδ T cells in immune responses to other respiratory viruses, including SARS-CoV-1. However, no studies have profoundly investigated these cells in COVID-19 patients to date. γδ T cells can be safely expanded in vivo using existing inexpensive FDA-approved drugs such as bisphosphonate, in order to test its protective immune response to SARS-CoV-2. To support this line of research, we review insights gained from previous coronavirus research, along with recent findings, discussing the potential role of γδ T cells in controlling SARS-CoV-2. We conclude by proposing several strategies to enhance γδ T cell's antiviral function, which may be used in developing therapies for COVID-19. [ABSTRACT FROM AUTHOR]

Objectives: Haploidentical haematopoietic cell transplantation (Haplo‐HCT) using peripheral blood stem cell (PBSC) grafts and post‐transplant cyclophosphamide (PTCy) is being increasingly used; however, data on immunological reconstitution (IR) are still scarce. Methods: This retrospective study evaluated T‐cell immunological reconstitution in 106 adult patients who underwent allogeneic haematopoietic cell transplantation for haematologic malignancies between 2013 and 2016. Results: At D30, while conventional T cells reached similar median counts in Haplo‐HCT recipients (n = 19) and controls (n = 87), γδ and Vδ2+ T‐cell median counts were significantly lower in Haplo‐HCT recipients and it persists at least until D360 for Vδ2+ T cells. PTCy induces a significant reduction in early γδ and Vδ2+ T‐cell proliferation at D 7. At one year, the rate of increase in Epstein–Barr virus (EBV) viral load was significantly higher in Haplo‐HCT recipients as compared to controls (61% versus 34%, P = 0.02). In multivariate analysis, a higher γδ T‐cell count (> 4.63 μL−1) at D30 was the only independent parameter significantly associated with a reduced risk of increase in EBV viral load (RR 0.34; 95% CI, 0.15–0.76, P = 0.009). Conclusion: Immunological reconstitution of γδ T cells is significantly delayed after Haplo‐HCT using PTCy and low‐dose ATG and is associated with an increased risk of increase in EBV viral load. [ABSTRACT FROM AUTHOR]

• Performance of an atlas of immune cell clusters for production of different cytokines in severe aplastic anemia with single-cell mass cytometry analysis. • IL-17A production by γδ T cells is associated with T-cell activation in severe aplastic anemia patients. • Performance of a diagnostic indicator for monitoring autoreactive T-cell activation status in the clinical treatment of severe aplastic anemia. Severe aplastic anemia (SAA) is a bone marrow failure syndrome characterized by activated T cells. Features of T-cell activation in the pathophysiology of SAA remain unknown. To understand T cell activation states, we investigated the atlas of peripheral immune cells and the secreted cytokine network with single cell mass cytometry analysis. We found decreased γδ T-cell frequencies in all patients with SAA, together with a significantly increased proportion of interleukin (IL)-17A-producing cell subsets. Cytokine network analysis of immune cells showed significant positive relationship between IL and 17A production from immune cells and disease severity of severe aplastic anemia. On separating SAA into two distinct subgroups based on T-cell activation stage, the proportion of γδ T cells tended to decrease in the T-cell-activated SAA group compared with non-T-cell-activated group. And the proportion of IL-17A-producing γδ T cells (γδT17) within γδ T cells was newly found to be significantly higher in the T-cell-activated SAA group, implying that IL-17A production by γδ T cells was associated with T-cell activation. Overall, our study revealed a role of γδT17 cells in mediating autoreactive T-cell activation in SAA and provided a novel diagnostic indicator for monitoring autoreactive T-cell activation status during the progression of aplastic anemia in the clinic. [ABSTRACT FROM AUTHOR]

Abstract Hepatocellular carcinoma (HCC) is the most common primary liver carcinoma and has one of the highest mortality rates of all cancers. The γδ T cells could infiltrate HCC and have demonstrated potent tumor-killing capacity. Here, we found that in peripheral blood, the vast majority of γδ T cells were Vδ2 T cells. In HCC patients, the frequency of Vδ2 T cells was significantly lower than in controls. γδ T cells that were harvested directly ex vivo possessed very limited capacity to eliminate Zol-loaded HCC cell lines, even at a high effector to target ratio. In vitro expansion with Zol could significantly increase the capacity of γδ T cells to eliminate HCC cell lines. But even with in vitro expansion, the γδ T cells from HCC patients presented significantly lower cytotoxic capacity than the γδ T cells from healthy individuals. The expression of IL-2 and IL-21 by γδ T cells was significantly lower in HCC patients than in control volunteers. Supplementing recombinant human IL-2 and IL-21 in the in vitro expansion culture increased the cytotoxic capacity of γδ T cells. In addition, the frequency of PD-1+ γδ T cells was significantly higher in HCC patients than in controls ex vivo , and was significantly elevated after in vitro expansion. Hep3B and HepG2 did not express PD-L1, while a small fraction of SNU-398 expressed PD-L1. Interestingly, co-incubation with γδ T cell elevated PD-L1 expression in HCC cell lines. Blocking PD-1 during in vitro expansion stage significantly elevated cytotoxicity toward all the HCC cell lines, while blocking PD-1 during the cytotoxicity assay significantly elevated cytotoxicity toward HepG2 and SNU-398, but not toward Hep3B. Overall, these results demonstrated that the circulating γδ T cells in HCC patients were reduced in cytotoxic capacity, possibly associated with the lack of IL-2 and IL-21 production and PD-1 upregulation. Highlights • γδ T cells possessed limited capacity to eliminate Zol-loaded HCC cell lines. • γδ T cells from HCC patients presented lower cytotoxic capacity than healthy individuals. • Low proportion of γδ T cells expressed IL-2 and IL-21 in HCC patients. • IL-2 and IL-21 increased the cytotoxic capacity of γδ T cells from HCC patients. • PD-1/PD-L1 mediated inhibition of γδ T cell cytotoxicity toward HCC cell lines. [ABSTRACT FROM AUTHOR]

• Summarized the γδ T cells play both pro-carcinogenic and anti-tumor roles in colorectal cancer. • Revealed the γδ T cells' different roles related to different activation pathways. • Discussed the specific mechanism of γδ T cells in pro-carcinogenic and anti-tumor functions. • Revealed the interaction between intestinal flora and γδ T cells. The occurrence of colorectal cancer (CRC) is highly prevalent and severely affects human health, with the third-greatest occurrence and the second-greatest rate of death globally. Current CRC treatments, including surgery, radiotherapy, and chemotherapy, do not significantly improve CRC patients' survival rate and quality of life, so it is essential to develop new treatment strategies. Adoptive cell therapy and other immunotherapy came into being. Currently, there has been an especially significant emphasis on γδ T cells as being the primary recipient of adoptive cell therapy. The present investigation found that γδ T cells possess the capability to trigger cytotoxicity in CRC cells, secrete cytokines, recruit immune cells for the purpose of destroying cancer cells, and inhibit the progress of CRC indirectly. Nevertheless, It is possible for γδ T cells to initiate a storm of inflammatory factors and inhibit the immune response to promote the advancement of CRC. This review demonstrates a close association between the γδ T cell initiation pathway and their close association with the intestinal flora. It has been observed that the intestinal flora performs a vital function in facilitating the stimulation and functioning of γδ T cells. The tumor-fighting effect is mainly regulated by desulphurizing Vibrio and lactic acid bacteria. In contrast, the regulation of tumor-promoting impact is closely related to Clostridia and ETBF. This review systematically combs γδ T cell dual function and their relationship to intestinal flora, which offers a conceptual framework for the γδ T cell application for CRC therapies. [ABSTRACT FROM AUTHOR]

The tumor microenvironment (TME) is generated by the cross-talk among tumor cells, immune system cells, and stromal cells. The TME generated by Marek's disease virus (MDV) is suggested to display an immunosuppressive milieu due to immune inhibitory molecules and cytokines which are possibly induced by MDV-transformed cells and regulatory T cells. Both anti-tumor and pro-tumor gamma delta (γδ) T cells are reported in human cancer. Although anti-tumor like and pro-tumor like γδ T cells are found in MDV-infected chickens at the later phase of infection, how the TME affects circulating and tissue-resident γδ T cells has not been investigated. Here, we demonstrated that the supernatant of the cultured splenocytes derived from MDV-challenegd chickens inhibited interferon (IFN)-γ production and CD25 expression by T cell receptor (TCR)γδ-stimulated tissue-resident γδ T cells, but the supernatant of the cultured MDV-transformed cell line did not affect γδ T cell activation. TCRγδ-stimulated circulating γδ T cells were influenced neither by the supernatant of the cultured splenocytes derived from MDV-challenegd chickens nor by the supernatant of the cultured MDV-transformed cell line. Taken together, activation and IFN-γ production by tissue-resident γδ T cells can be inhibited in the TME generated by MDV while tumor attracted circulating γδ T cells may not be influenced in activation and IFN-γ production by the TME generated by MDV. • A reduction of IFN-γ-producing γδ T cells derived from spleen was observed in the MDV supernatant treated condition. • Circulating γδ T cells was not influenced by the MDV supernatant. • The MSB-1 supernatant did not induce a decrease of IFN-γ-producing γδ T cells. • The MDV supernatant downregulated CD25 expression on γδ T cells derived from spleen and PBMCs. • The inhibition of activated γδ T cells might be caused by immunosuppressive cytokines produced in the TME generated by MDV. [ABSTRACT FROM AUTHOR]

• Celiac disease is an organ-specific autoimmune disorder leads to the development of enteropathy. • Only available management option for celiac disease is a lifelong gluten-free diet. • Unconventional T cells play a pivotal and distinct role in celiac disease settings and are a viable candidate for clinical application. Celiac disease (CD) is an organ-specific autoimmune disorder that occurs in genetically predisposed individuals when exposed to exogenous dietary gluten. This exposure to wheat gluten and related proteins from rye and barley triggers an immune response which leads to the development of enteropathy associated with symptoms of bloating, diarrhea, or malabsorption. The sole current treatment is to follow a gluten-free diet for the rest of one's life. Intestinal barriers are enriched with Unconventional T cells such as iNKT, MAIT, and γδ T cells, which lack or express only a limited range of rearranged antigen receptors. Unconventional T cells play a crucial role in regulating mucosal barrier function and microbial colonization. Unconventional T cell populations are widely represented in diseased conditions, where changes in disease activity related to iNKT and MAIT cell reduction, as well as γδ T cell expansion, are demonstrated. In this review, we discuss the role and potential employment of Unconventional T cells as a therapeutic target in the pathophysiology of celiac disease. [ABSTRACT FROM AUTHOR]

Objectives Zoledronate (ZOL) is usually used for prevention of skeletal-related events in cancer patients with bone metastases. The first administration of ZOL is occasionally associated with development of acute-phase reaction (APR), which is due to activation of γδ T cells. ZOL-related APR was associated with better overall survival (OS) of patients with non-small cell lung cancer (NSCLC) in our previous retrospective study. However, it remains to be clarified whether γδ T cells are more activated in patients who experienced ZOL-related APR, and whether γδ T cell activation is involved in prolongation of OS. Materials and Methods Twenty-three patients with advanced NSCLC were recruited between 2012 and 2014 in this study. We administered ZOL to participants with standard care. The patient characteristics, change in γδ T cell counts and cytokines, OS, and skeletal-related event-free survival were compared between patients with APR (APR group) and those without APR (non-APR group). Results Ten patients (43.5%) experienced a ZOL-related APR. The number of γδ T cells at baseline in the APR group was significantly higher than that in the non-APR group. Serum interleukin-6 and tumor necrosis factor-α in the APR group were significantly increased, but no change in the number of γδ T cells was observed after the first administration of ZOL in both groups. OS in the APR group was significantly longer than that in the non-APR group (median survival time: 23.1 vs. 14.5 months, p < 0.01). Conclusion We showed that APR is related to higher numbers of γδ T cells at baseline and increased cytokines after the first ZOL administration, but not to proliferative responses of γδ T cells. In addition, better OS was observed in the APR group. Therefore, the number of γδ T cells might be a prognostic marker in patients with NSCLC. [ABSTRACT FROM AUTHOR]

In the present study, we evaluated expression of IFN-γ, IL-17, TNF-α, IL-10 and TGF-β by mucosal cells, including WC1 + γδ T cells, in ileal tissues taken from non-infected cattle and cattle naturally infected with Mycobacterium avium subsp paratuberculosis (MAP). Infected cattle were either in the subclinical or clinical stage of infection. We hypothesized that the cytokine profile of the WC1 + γδ T cell subset would be different between subclinical and clinical cattle. Our data indicate a significant increase in the numbers of WC1 + γδ T cells expressing IL-10 in clinical cattle compared to subclinical and non-infected cattle. We observed a significant increase in TGF-β expression by non-WC1 + cells in clinically infected cattle. Expression of IFN-γ, IL-17 and TNF-α in mucosal cells, including the WC1 + γδ T cell subset, was identified in all examined groups. However, our data indicate that the stage of infection did not significantly influence expression of these proinflammatory cytokines. This study demonstrates changes in the cytokine mRNA expression profile of mucosal cells in the ileum, and specifically WC1 + γδ T cells, as cattle progress to the clinical disease. The change is characterized by an increase in expression of anti-inflammatory cytokines. [ABSTRACT FROM AUTHOR]

Emerging evidence from graft manipulations and immunotherapeutic treatments has highlighted a favorable effect of γδ T cells in the setting of allogeneic hematopoietic stem cell transplantation (alloHSCT). However, γδ T cell subsets and their distinct features in the allograft have not been characterized. Additionally, whether homeostatic γδ T cell fractions are influenced by treatment with granulocyte colony-stimulating factor (G-CSF) remains elusive. We initially compared the phenotypes of γδ T cell subsets, including CD27 + , CD27 - , Vδ1 + , Vδ2 + , Vδ1 + CD27 + , Vδ1 + CD27 - , Vδ2 + CD27 + , and Vδ2 + CD27 - cells, in the peripheral blood of 20 healthy donors before and after G-CSF mobilization. The effects of G-CSF on the cytokine production capacities of γδ T cell subsets were also detected. Moreover, the correlation between donor homeostatic γδ T cell content and the early recoveries of γδ T cell subgroups after haploidentical HSCT was investigated in 40 pairs of donors and recipients. We found that both the proportions and IFN-γ secretion capacities of peripheral γδ T cell subsets were preserved in G-CSF–primed grafts. Homeostatic Vδ1 and Vδ2 proportions of donors significantly correlated with the early recoveries of Vδ1 and Vδ2 cells after haploidentical HSCT. Interestingly, a higher day 30 Vδ1 concentration was associated with a lower incidence of cytomegalovirus reactivation in recipients. These results not only clarify the preservation of γδ T cell phenotypes and functional features by G-CSF mobilization but also suggest the importance of homeostatic γδ T cell content for immune recovery after alloHSCT. [ABSTRACT FROM AUTHOR]

Abstract: To investigate reconstitution of T and NK cells after αβ T lymphocyte–depleted haploidentical hematopoietic cell transplantation (HHCT) and the clinical implications of γδ T cells, we analyzed 50 pediatric patients who received 55 HHCTs using αβ T cell–depleted grafts. The number of CD3+ T cells and CD8+ T cells recovered rapidly and reached donor levels at days 180 and 60, respectively. Recovery of NK cells was rapid, and the median of NK cells at day 14 was comparable to the donor level. At day 14, median percentage of γδ T lymphocytes was 70.5%. After day 14, the percentage of γδ T cells gradually decreased, while the percentage of αβ T cells gradually increased. Patients with a low percentage (≤21%) of γδ T cells at day 30 had significantly higher incidence of cytomegalovirus (CMV) reactivation compared to patients with a high percentage (>70%) of γδ T cells (P < .01). In patients with acute leukemia, patients with high percentage of γδ T cells at day 30 showed significantly higher relapse‐free survival compared to those with low percentage of γδ T cells (P = .02). Data suggest that early recovery of γδ T cells decreases the risk of CMV reactivation and leukemia relapse. [ABSTRACT FROM AUTHOR]

Bovine γδ T cells are amongst the first cells to accumulate at the site of Mycobacterium bovis infection; however, their role in the developing lesion remains unclear. We utilized transcriptomics analysis, in situ hybridization, and a macrophage/γδ T cell co-culture system to elucidate the role of γδ T cells in local immunity to M. bovis infection. Transcriptomics analysis revealed that γδ T cells upregulated expression of several novel, immune-associated genes in response to stimulation with M. bovis antigen. BCG-infected macrophage/γδ T cell co-cultures confirmed the results of our RNAseq analysis, and revealed that γδ T cells from M. bovis- infected animals had a significant impact on bacterial viability. Analysis of γδ T cells within late-stage M. bovis granulomas revealed significant expression of IFN-γ and CCL2, but not IL-10, IL-22, or IL-17. Our results suggest γδ T cells influence local immunity to M. bovis through cytokine secretion and direct effects on bacterial burden. [ABSTRACT FROM AUTHOR]

Obesity is a major risk factor for psoriasis, but how obesity disrupts the regulatory mechanisms that keep skin inflammation in check is unclear. Here, we found that skin was enriched with a unique population of CD4+Foxp3+ regulatory T (Treg) cells expressing the nuclear receptor peroxisome proliferation-activated receptor gamma (PPARγ). PPARγ drove a distinctive transcriptional program and functional suppression of IL-17A+ γδ T cell-mediated psoriatic inflammation. Diet-induced obesity, however, resulted in a reduction of PPARγ+ skin Treg cells and a corresponding loss of control over IL-17A+ γδ T cell-mediated inflammation. Mechanistically, PPARγ+ skin Treg cells preferentially took up elevated levels of long-chain free fatty acids in obese mice, which led to cellular lipotoxicity, oxidative stress, and mitochondrial dysfunction. Harnessing the anti-inflammatory properties of these PPARγ+ skin Treg cells could have therapeutic potential for obesity-associated inflammatory skin diseases. [Display omitted] • Skin is enriched with a distinct subset of PPARγ+ Treg subpopulation • PPARγ+ Tregs suppress IL-17A+ γδ T cell-mediated psoriatic inflammation • Diet-induced obesity reduces PPARγ+ skin Tregs and increases IL-17A+ γδ T cells • The accumulation of long-chain FFAs drive PPARγ+ skin Treg loss in obesity Obesity is a major risk factor for inflammatory skin diseases, in particular psoriasis. Sivasami et al. demonstrate that diet-induced obesity dysregulates a distinct subset of PPARγ+ Tregs in the skin via fatty-acid-induced lipotoxicity, which results in loss of control over IL-17A+ γδ T cell-mediated inflammation and exacerbated psoriasis. [ABSTRACT FROM AUTHOR]

Vδ2 T cells are a subpopulation of γδ T cells in humans that are cytotoxic towards cells which accumulate isopentenyl pyrophosphate. The nitrogen-containing bisphosphonate, zoledronic acid (ZA), can induce tumour cell lines to accumulate isopentenyl pyrophosphate, thus rendering them more susceptible to Vδ2 T cell cytotoxicity. However, little is known about whether ZA renders other, non-malignant cell types susceptible. In this study we focussed on macrophages (Mϕs), as these cells have been shown to take up ZA. We differentiated peripheral blood monocytes from healthy donors into Mϕs and then treated them with IFN-γ or IL-4 to generate M1 and M2 Mϕs, respectively. We characterised these Mϕs based on their phenotype and cytokine production and then tested whether ZA rendered them susceptible to Vδ2 T cell cytotoxicity. Consistent with the literature, IFN-γ-treated Mϕs expressed higher levels of the M1 markers CD64 and IL-12p70, whereas IL-4-treated Mϕs expressed higher levels of the M2 markers CD206 and chemokine (C-C motif) ligand 18. When treated with ZA, both M1 and M2 Mϕs became susceptible to Vδ2 T cell cytotoxicity. Vδ2 T cells expressed perforin and degranulated in response to ZA-treated Mϕs as shown by mobilisation of CD107a and CD107b to the cell surface. Furthermore, cytotoxicity towards ZA-treated Mϕs was sensitive-at least in part-to the perforin inhibitor concanamycin A. These findings suggest that ZA can render M1 and M2 Mϕs susceptible to Vδ2 T cell cytotoxicity in a perforin-dependent manner, which has important implications regarding the use of ZA in cancer immunotherapy. [ABSTRACT FROM AUTHOR]

A role for γδ T cells in protection against mycobacterial infections including Johne’s disease (JD) has been suggested. In neonatal calves where the risk to infection with Mycobacterium avium subsp. paratuberculosis (MAP) is high, the majority of circulating CD3 + lymphocytes are γδ TCR + . Bovine γδ T cells are divided into two major subsets based on the surface expression of workshop cluster 1 (WC1). The WC1 + subset, the predominant subset in periphery, is further divided into WC1.1 + and WC1.2 + subpopulations. The ability of γδ T cells to produce IFN-γ prior to CD4 + αβ T cell activation could be crucial to the outcome of MAP infection. In the current study, cattle were naturally infected with MAP and were classified as either in the subclinical or clinical stage of infection. Compared to the control non-infected group, γδ T cell frequency in circulating lymphocytes was significantly lower in the clinical group. The observed decline in frequency was restricted to the WC1.2 + subset, and was not associated with preferential migration to infection sites (distal-ileum). γδ T cells proliferated significantly in recall responses to stimulation with purified protein derivative from MAP (PPD-J) only in subclinically infected cattle. These responses were a heterogeneous mixture of WC1.1 and WC1.2 subsets. Proliferation and IFN-γ production by the WC1.1 + γδ T cell subset was significantly higher in the subclinical group compared to the control and clinical groups. Our data indicates differences in MAP-specific ex-vivo responses of peripheral WC1 + γδ T cells of cattle with the subclinical or clinical form of JD. [ABSTRACT FROM AUTHOR]

Natural killer cells in the chicken are mainly confined to the intestine, while only small frequencies are detectable in spleen, lung and blood. Here, we compared the spontaneous cytotoxicity of lymphocytes isolated from blood, spleen and intestine using a flow cytometric based cytotoxicity assay. There was no spontaneous cytotoxicity detected in chicken blood preparations. In contrast, freshly prepared splenocytes exhibited a spontaneous cytotoxicity of up to 50% and intestinal epithelial lymphocytes of up to 85%. This cytotoxicity was observed against the RP9 but not against the chicken CU24 target cell line. The observed cytotoxicity was MHC unrestricted since B 2 B 2 derived effector cells killed RP9 target cells (B 2 B 15 ) equally well compared to MHC mismatched 2D8 targets (B 19 B 19 ). The cytotoxicity of splenocytes was enhanced by preincubation with IL-2 or strongly increased with IL-2 plus IL-12. By cell sorting, we identified the CD8 + γδ T cell subset as the major effectors, whereas both CD8 − γδ T cells and CD8 + αβ T cells had only low cytolytic potential. Within intestinal lymphocyte CD45 + cells displayed cytotoxicity as well as sorted γδ T cells and NK cell. In conclusion, the chicken γδ T cells represent a major cytotoxic lymphocyte subset that can lyse target cells in a MHC unrestricted manner. [ABSTRACT FROM AUTHOR]

The study aimed to identify an immunoregulatory factor that restores the phosphoantigen response of Vγ9Vδ2+ T cells from HIV-positive individuals on antiretroviral therapy. It was designed to characterize the effects of interleukin-18 (IL-18) on proliferation and effector function in Vγ9Vδ2 T cells from HIV-negative individuals and test whether exogenous IL-18 reconstitutes the Vγ9Vδ2 T-cell response to phosphoantigen from HIV-positive donors. Vγ9Vδ2 T cells from HIV-negative individuals responded strongly to phosphoantigen or aminobisphosphonate stimulation of peripheral blood mononuclear cells (PBMC), whereas cells with similar T-cell receptor profiles from HIV-positive individuals only responded to aminobisphosphonate. Interleukin-18 was higher after aminobisphosphonate stimulation due to activation of the inflammasome pathway. Both IL-18 and IL-18 receptor levels were measured and the activity of exogenous IL-18 on HIV-negative and HIV-positive PBMC was evaluated in terms of Vγ9Vδ2 T-cell proliferation, memory subsets, cytokine expression and CD107a expression. Interleukin-18 stimulation increased proliferation, enhanced the accumulation of effector memory cells, and increased expression of cytotoxic markers in HIV-negative controls. When Vγ9Vδ2 T cells from HIV-positive individuals were stimulated with isopentenyl pyrophosphate in the presence of IL-18, there was increased proliferation, accumulation of memory cells, and higher expression of CD56, NKG2D and CD107a (markers of cytotoxic effector phenotype). Interleukin-18 stimulation specifically expanded the Vγ9-JγP+ subset of Vγ9Vδ2 T cells, as was expected for normal responses to phosphoantigen. Interleukin-18 is a potent stimulator of Vγ9Vδ2 T-cell proliferation and effector function. Therapies directed at reconstituting Vγ9Vδ2 T-cell activity in HIV-positive individuals should include stimulators of IL-18 or direct cytokine supplementation. [ABSTRACT FROM AUTHOR]

Background aims. The outcome for pancreatic cancer after surgery remains highly unsatisfactory, and development of more effective therapies is urgently needed. Therefore, we conducted a phase I clinical study of a novel combination of gemcitabine (GEM) and autologous γδ T-cell therapy for patients with curatively resected pancreatic cancer (University Hospital Medical Information Clinical Trials Registry identifier 000000931). Methods. From July 2008 to December 2012, 56 consenting patients were recruited. After preliminary testing of γδ T-cell proliferative capacity, 28 patients were eligible to receive combined GEM plus γδ T-cell therapy. Results. During treatment, most of the adverse events observed were due to GEM, including myelosuppression and gastrointestinal disorders. No severe adverse events were obviously related to the γδ T-cell therapy. To evaluate clinical efficacy, patients receiving combined therapy (Group A, n = 28) were compared with those receiving GEM alone (Group B, n = 20). No significant differences were observed between the two groups in recurrence-free survival or overall survival. However, we found that, relative to progressing patients, more γδ T-cells were detectable in the blood of recurrence-free patients after only two injections (P < .0388) and more so five injections (P < .0175). Patients with >15% peripheral γδ T-cells after two injections and >20% after five injections had a chance of a more favorable clinical outcome. Accumulation of γδ T cells was positively related to the quality of the infused products, with those having >80% γδ T cells being optimal. Discussion. High quality of the γδ T-cell product is crucial to achieve a high percentage of γδ T cells in the blood and to achieve better clinical outcome. [ABSTRACT FROM AUTHOR]

We investigated the effect of gemcitabine (GEM), a key drug for pancreatic cancer treatment, on the expression of cell surface MICA/B in pancreatic cancer cells and resulting cytotoxicity of γδ T cells. We assessed the effect of GEM on the upregulation of cell surface MICA/B expression by flow cytometry, utilizing six pancreatic cancer cell lines. MICA and CD16 expressions from resected pancreatic cancer patient specimens, which received neoadjuvant chemotherapy (NAC) with GEM, were analyzed by immunohistochemistry. GEM could increase MICA/B expression on cell surface in pancreatic cancer cell lines (in 2 of 6 cell lines). This effect was most effectively at concentration not affecting cell growth of GEM (0.001 μM), because MICA/B negative population was appeared at concentration at cytostatic and cytotoxic effect to cell growth (0.1 and 10 μM). The cytotoxic activity of γδ T cells against PANC-1 was detected and functions through interactions between NKG2D and MICA/B. However, the enhancement of NKG2D-dependent cytotoxicity with increased MICA/B expression, by GEM treatment, was not observed. In addition, soluble MIC molecules were released from pancreatic cancer cell lines in culture supernatant with GEM treatment. Immunohistochemical staining demonstrated that MICA expression in tumor cells and CD16 positive cells surrounding tumors were significantly higher in the NAC group compared to that of the control group. There was a significant correlation between NAC and MICA expression, as well as NAC and CD16 positive cell expression. The present results indicate that low-dose GEM-induced MICA/B expression enhances innate immune function rather than cytotoxicity in pancreatic cancer. In addition, our result suggests that the inhibition of cleavage and release of MIC molecules from the tumor surface could potentially improve NKG2D-dependent cytotoxicity. [ABSTRACT FROM AUTHOR]

Topical use of ginsenosides, the major bioactive substances in Panax ginseng , has been used for the treatment of irritated skin complaints. However, the protective mechanisms of ginsenosides remain unclear. In the present study, we investigated the anti-inflammatory role of ginsenoside F2 (GF2) on the skin inflammation. To induce irritant dermatitis, 12- O -tetradecanoylphorbol-13-acetate (TPA) was applied on the surface of the mouse ears with or without treatments of GF2 and dexamethasone for 24 h. Protective effects of GF2 on edema and inflammation were assessed by measuring ear thickness, weights of skin punch, and inflammatory responses. In gross findings, treatments with GF2 significantly decreased skin thickness and weight compared to those of TPA-treated groups, which was comparable with the protective effects of dexamethasone. In addition, expression of inflammatory mediators was remarkably reduced in GF2-treated ears compared to that of vehicle-treated ears of mice. Interestingly, immunohistochemistry and flow cytometry analyses revealed that TPA treatment significantly increased infiltration of interleukin-17 (IL-17) producing dermal γδ T cells, while frequencies of γδ T cells was decreased by GF2 treatment, subsequently ameliorating inflammation in skin. Concomitantly, TPA-mediated skin inflammation was significantly ameliorated in IL-17A knock out mice. Furthermore, GF2 treatment inhibited infiltration and generation of reactive oxygen species (ROS) of neutrophils in damaged ears compared with vehicle-treated mice. These results clearly suggest that GF2 treatment ameliorates TPA-induced dermal inflammation by inhibiting production of IL-17 and ROS in γδ T cells and neutrophils, respectively. Therefore, as a natural compound, application of GF2 may be a novel therapeutic approach for treating skin inflammation. [ABSTRACT FROM AUTHOR]