Immunoactivation in preeclampsia: Vdelta2+ and regulatory T cells during the inflammatory stage of disease

TIM-3 Expression in Endometriosis

PROBLEM

Endometriosis is a prevalent chronic gynecological disease linked to immune dysfunction. The protein T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) plays a crucial role in immune system balance. Malfunction of TIM-3 may result in excessive immune activation and inflammatory tissue damage. Given TIM-3's established role in the development of cancer and autoimmune diseases, we decided to study its role in women suffering from endometriosis.

STUDY METHOD

We included a total of 62 female patients, all of whom had undergone laparoscopic surgery. Of these, 47 had endometriosis and 15 did not. During surgery, we collected peritoneal fluid (PF) and peripheral blood (PB) samples from every patient for analysis using flow cytometry. To mark the samples, we used a panel of monoclonal antibodies and examined TIM-3 expression in their immune cells.

RESULTS

Endometriosis patients in PB demonstrated a significantly lower percentage of CD56+ T cells with TIM-3 expression. As endometriosis progressed through its stages, this expression lessened. This decrease was particularly notable in women with stage III/IV endometriosis. Additionally, both women diagnosed with intestinal endometriosis and those with recent endometriosis diagnoses showed a significantly reduced percentage of CD56+ T cells expressing TIM-3.

CONCLUSIONS

Patients with endometriosis exhibit diminished TIM-3 expression within circulating T cells. This warrants further investigation to discern whether it contributes to the progression of endometriosis, potentially through the amplification of autoreactive T cells and inflammation.

Gamma delta (γδ) T cells in the female reproductive tract: active participants or indifferent bystanders in reproductive success?

The female reproductive tract accommodates and balances the unique immunological challenges of protection from sexually transmitted pathogens and tolerance of the fetus and placenta in pregnancy. Leukocytes in the female reproductive tract actively engage in extensive maternal adaptations that are imperative for embryo implantation, placental development, and fetal growth support. γδ T cells are abundant at many mucosal sites in the body, where they provide protection against pathogens and cancer, and have roles in tissue renewal and homeostasis. In this review, we summarize studies in humans and rodents showing that γδ T cells are prevalent in the female reproductive tract and fluctuate in response to hormone changes across the reproductive cycle. Emerging evidence points to a link between changes in their abundance and molecular repertoire in the uterus and pregnancy disorders including recurrent miscarriage and preterm birth. However, defining the precise functional role of female reproductive tract γδ T cells and understanding their physiological significance in reproduction and pregnancy have remained elusive. Here, we critically analyze whether reproductive tract γδ T cells could be active participants in reproductive events-or whether their principal function is immune defense, in which case they may compromise pregnancy success unless adequately regulated.

Association between Serum 8-Iso-Prostaglandin F2α as an Oxidative Stress Marker and Immunological Markers in a Cohort of Preeclampsia Patients

BACKGROUND

We aimed to analyze the presence and clinical use of serum 8-iso-prostaglandin F2-alpha (8-iso-PGF2α) as an oxidative stress marker and some inflammatory status biomarkers (tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), IL-10, high-sensitivity C-reactive protein (hs-CRP), and pentraxin-3 (PTX3)) for patients with preeclampsia (PE).

METHODS

Sixty pregnant women, including thirty diagnosed with PE and thirty who were healthy (NP), were included in this study. For the assessment of serum levels of biomarkers, we used the Enzyme-Linked Immunosorbent Assay (ELISA) technique.

RESULTS

Our preliminary study showed that the expression level of serum 8-iso-PGF2α in the PE group was higher than in the PE after delivery (PE-AD) group (742.00 vs. 324.00 pg/mL, p < 0.0001). Groups of preeclamptic patients (PE + PE-AD) expressed significantly elevated levels for all of the assessed inflammatory mediators as compared to NP. Significant strong positive correlations with 8-iso-PGF2α levels were found for systolic blood pressure (SBP), and TNF-α (Spearman's rho = 0.622, p-value = 0.020 and rho = 0.645, p-value = 0.002, respectively). Our study demonstrates that 8-iso-PGF2α and PTX3 have the greatest diagnostic value for pregnant women with PE.

CONCLUSIONS

8-iso-PGF2α and PTX3 can be used as independent predictor factors, along with already-known cytokines, that could represent a prophylactic way to help clinicians identify or predict which pregnant women will develop PE.

Functions of LncRNAs, exosomes derived MSCs and immune regulatory molecules in preeclampsia disease

Modulatory signaling pathway such as T cell immunoreceptor with Ig and ITIM domains (TIGIT), Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA-4), P53 signaling and TIM (T-cell immunoglobin and mucin domain) are important in normal pregnancy and loss of their functions or dysregulation of related genes can lead to some disorders. Inflammation is a process by which your body's white blood cells and the things they make protect you from infection from outside invaders, such as bacteria and viruses. Some cellular and molecular signaling have been categorized to demonstrate the mechanism that protects tolerance to antigens. lncRNAs significantly impact physiological processes like immunity and metabolism, and are linked to tumors, cardiovascular diseases, nervous system disorders, and nephropathy.In this review article, we summarized recent studies about the role of TIGIT, CTLA-4, P53 and TIM regulatory molecules and reviewed dysregulation of these pathway in diseases.We will also talk about the role of lncRNAs and mesenchymal stem cells.

Innate and Adaptive Immune Systems in Physiological and Pathological Pregnancy

The dynamic immunological changes occurring throughout pregnancy are well-orchestrated and important for the success of the pregnancy. One of the key immune adaptations is the maternal immune tolerance towards the semi-allogeneic fetus. In this review, we provide a comprehensive overview of what is known about the innate and adaptive immunological changes in pregnancy and the role(s) of specific immune cells during physiological and pathological pregnancy. Alongside this, we provided details of remaining questions and challenges, as well as future perspectives for this growing field of research. Understanding the immunological changes that occur can inform potential strategies on treatments for the optimal health of the neonate and pregnant individual both during and after pregnancy.

Immune cell profiling of preeclamptic pregnant and postpartum women by single-cell RNA sequencing

Preeclampsia (PE), a leading cause of maternal and fetal morbidity and mortality, is closely related to the immune system alterations. However, little is known about the landscape and heterogeneity of maternal immune system at single-cell level among PE patients. In this study, peripheral blood mononuclear cells (PBMCs) were isolated from three early-onset preeclamptic pregnant women and two healthy control, respectively. Single-cell RNA sequencing was performed on 10× genomics platform and single-cell transcriptomes were obtained to characterize immune cell subgroups at the pregnant and postpartum stages. In total, 80,429 single-cell transcriptomes were obtained. 19 cellular compositions were identified, which were categorized into six cell types including T cells, natural killer (NK) cells, B cells, monocytes, plasmacytoid dendritic cells and conventional dendritic cells. There were excessive activation of B cells, monocytes and NK cells in PE patients at the pregnant stage based on comparative analysis. Lower immune response activation was noticed in CD4+ and CD8+ T cells in PE patients, especially the low-activation of memory T cells at the pregnant and postpartum stages. PE patients showed high activation of B cells in pregnancy persisted postpartum and lower activation of memory T cells, indicating their persistent effects on the pathogenesis and recurrence risk of PE. This study provide a broad characterization of the single-cell transcriptome of PBMCs in PE, which contributes to identification of immune imbalance for its monitoring and treatment.

Role of hormones in the pregnancy and sex-specific outcomes to infections with respiratory viruses

Pregnant women infected with pathogenic respiratory viruses, such as influenza A viruses (IAV) and coronaviruses, are at higher risk for mortality, hospitalization, preterm birth, and stillbirth. Several factors are likely to contribute to the susceptibility of pregnant individuals to severe lung disease including changes in pulmonary physiology, immune defenses, and effector functions of some immune cells. Pregnancy is also a physiologic state characterized by higher levels of multiple hormones that may impact the effector functions of immune cells, such as progesterone, estrogen, human chorionic gonadotropin, prolactin, and relaxin. Each of these hormones acts to support a tolerogenic immune state of pregnancy, which helps prevent fetal rejection, but may also contribute to an impaired antiviral response. In this review, we address the unique role of adaptive and innate immune cells in the control of pathogenic respiratory viruses and how pregnancy and specific hormones can impact their effector actions. We highlight viruses with sex-specific differences in infection outcomes and why pregnancy hormones may contribute to fetal protection but aid the virus at the expense of the mother's health.

Medawar's PostEra: Galectins Emerged as Key Players During Fetal-Maternal Glycoimmune Adaptation

Lectin-glycan interactions, in particular those mediated by the galectin family, regulate many processes required for a successful pregnancy. Over the past decades, increasing evidence gathered from in vitro and in vivo experiments indicate that members of the galectin family specifically bind to both intracellular and membrane bound carbohydrate ligands regulating angiogenesis, immune-cell adaptations required to tolerate the fetal semi-allograft and mammalian embryogenesis. Therefore, galectins play important roles in fetal development and placentation contributing to maternal and fetal health. This review discusses the expression and role of galectins during the course of pregnancy, with an emphasis on maternal immune adaptions and galectin-glycan interactions uncovered in the recent years. In addition, we summarize the galectin fingerprints associated with pathological gestation with particular focus on preeclampsia.

Cellular immune responses in the pathophysiology of preeclampsia

Preeclampsia, defined as new-onset hypertension accompanied by proteinuria occurring at 20 weeks of gestation or later, is a leading cause of perinatal morbidity and mortality worldwide. The pathophysiology of this major multi-systemic syndrome includes defective deep placentation, oxidative stress, endothelial dysfunction, the presence of an anti-angiogenic state, and intravascular inflammation, among others. In this review, we provide a comprehensive overview of the cellular immune responses involved in the pathogenesis of preeclampsia. Specifically, we summarize the role of innate and adaptive immune cells in the maternal circulation, reproductive tissues, and at the maternal-fetal interface of women affected by this pregnancy complication. The major cellular subsets involved in the pathogenesis of preeclampsia are regulatory T cells, effector T cells, NK cells, monocytes, macrophages, and neutrophils. We also summarize the literature on those immune cells that have been less characterized in this clinical condition, such as γδ T cells, invariant natural killer T cells, dendritic cells, mast cells, and B cells. Moreover, we discuss in vivo studies utilizing a variety of animal models of preeclampsia to further support the role of immune cells in this disease. Finally, we highlight the existing gaps in knowledge of the immunobiology of preeclampsia that require further investigation. The goal of this review is to promote translational research leading to clinically relevant strategies that can improve adverse perinatal outcomes resulting from the obstetrical syndrome of preeclampsia.

Roles of γδT cells in pregnancy and pregnancy-related complications

A successful pregnancy is a complex and unique process comprised of discrete events, including embryo implantation, placentation, and parturition. To maintain the balance between maternal-fetal immune tolerance and resistance to infections, the maternal immune system must have a high degree of stage-dependent plasticity throughout the period of pregnancy. Innate immunity is the frontline force for the establishment of early anti-infection and tolerance mechanisms in mammals. Belonging to the innate immune system, a subset of T cells called γδT cells (based on γδT cell receptors) are the main participants in immune surveillance and immune defense. Unlike traditional αβT cells, γδT cells are regarded as a bridge between innate immunity and acquired immunity. In this review, we summarize current knowledge on the functional plasticity of γδT cells during pregnancy. Furthermore, we discuss the roles of γδT cells in pathological pregnancies.

Immune checkpoints and reproductive immunology: Pioneers in the future therapy of infertility related Disorders?

As co-stimulatory receptors, immune checkpoint molecules are found on the surface of various immune cells and transduce inhibitory signals following ligand binding. The most studied members in this regard include PD-1, TIM-3, and CTLA-4. The physiological part immune checkpoints possess is the prevention of dangerous immune attacks towards self-antigens throughout an immune response, which takes place through the negative regulation of the effector immune cells, through the induction of T-cell exhaustion, for instance. It has recently been suggested that each checkpoint reduces immunoactivation via distinct intracellular mechanisms of signaling. Regulators of immune checkpoints are supposed to participate actively in immune defense mechanisms against infections, preventing autoimmunity, transplantation, and tumor immune evasion. In pregnancy, as an active immunotolerance mechanism which is also natural, the maternal immune system encounters two simultaneous challenges; in addition to accepting the semi-allogeneic fetus, the maternal immune system should also prevent infections. In this regard, the part immune checkpoint molecules possess is particularly interesting. Herein, the current understanding of such part in reproductive immunology is described.

T lymphocytes and preeclampsia: The potential role of T-cell subsets and related MicroRNAs in the pathogenesis of preeclampsia

Innate and adaptive immune systems have a crucial role in initiating and progressing some pregnancy disorders such as preeclampsia (PE), which is one of the pregnancy-specific disorders that could result in neonatal and maternal morbidity and mortality. The dysregulation of the spiral artery and inadequate trophoblast invasion lead to PE symptoms through producing various inflammatory cytokines and anti-angiogenic factors from the placenta. T lymphocytes play a special role in the epithelium and stroma of the human endometrium. CD4+ T helper (Th) cells, Th1/Th2, and Th17/T regulatory (Treg) balance mainly contribute to the establishment of a pregnancy-favorable environment. This review examined the dysregulation of some cytokines produced from T cells, the dysregulation of the transcription factors of Th cells, the expression of chemokine receptors on T cells, as well as the effects of some factors including vitamin D on the activity of T cells, and finally, the dysregulation of various miRNAs related to T cells, which could cause PE.

NKG2D as a Cell Surface Marker on γδ-T Cells for Predicting Pregnancy Outcomes in Patients With Unexplained Repeated Implantation Failure

Maternal immune tolerance to semi-allogeneic fetus is essential for a successful implantation and pregnancy. Growing evidence indicated that low cytotoxic activity of γδ-T cells, which is mediated by activation and inhibitory receptors, is important for establishment of maternal immune tolerant microenvironment. However, the correlation between receptors on peripheral blood γδ-T cells, such as NKG2D, CD158a, and CD158b, and pregnancy outcome in patients with unexplained repeated implantation failure (uRIF) remains unclear. In this study, the association between the expression level of these receptors and pregnancy outcome in patients with uRIF was investigated. Thirty-eight women with uRIF were enrolled and divided into two groups: successful group and failed group, according to the pregnancy outcome on different gestational periods. The percentage of NKG2D⁺ γδ-T cells in lymphocytes was significantly higher in uRIF patients who had failed clinical pregnancy in subsequent cycle, compared with those who had successful clinical pregnancy. However, there were no differences about the frequencies of CD158a⁺ and CD158b⁺ γδ-T cells between the successful and failed groups. The receiver operating characteristic curve exhibited that the optimal cut-off value of NKG2D⁺ γδ-T cells was 3.24%, with 92.3% sensitivity and 66.7% specificity in predicting clinical pregnancy failure in uRIF patients. The patients with uRIF were further divided into two groups, group 1 (NKG2D⁺ γδ-T cells <3.24%) and group 2 (NKG2D⁺ γδ-T cells ≥3.24%), based on the cut-off value. The live birth rate of patients in the group 1 and group 2 were 61.5 and 28.0%, respectively. Kaplan-Meier survival curve further suggested that the frequency of NKG2D⁺ γδ-T cells in lymphocytes negatively correlated with live birth rate in patients with uRIF. In conclusion, our study demonstrated that the frequency of peripheral blood NKG2D⁺ γδ-T cells among lymphocytes is a potential predictor for pregnancy outcome in uRIF patients.

Immune and Apoptosis Mechanisms Regulating Placental Development and Vascularization in Preeclampsia

Preeclampsia is the most severe type of hypertensive disorder of pregnancy, affecting one in 10 pregnancies worldwide and increasing significantly maternal and neonatal morbidity and mortality. Women developing preeclampsia display an array of symptoms encompassing uncontrolled hypertension and proteinuria, with neurological symptoms including seizures at the end of pregnancy. The main causes of preeclampsia are still unknown. However, abnormal placentation and placenta vascularization seem to be common features in preeclampsia, also leading to fetal growth restriction mainly due to reduced placental blood flow and chronic hypoxia. An over activation of maternal immunity cells against the trophoblasts, the main cells forming the placenta, has been recently shown as an important mechanism triggering trophoblast apoptosis and death. This response will further disrupt the remodeling of maternal uterine arteries, in a first stage, and the formation of new placental vessels in a later stage. A consequent chronic hypoxia stress will further contribute to increase placental stress and exacerbate systemic circulatory changes in the mother. The molecular mechanisms driving these processes of apoptosis and anti-angiogenesis are also not well-understood. In this review, we group main evidences suggesting potential targets and molecules that should be better investigated in preeclampsia. This knowledge will contribute to improve therapies targeting a better placenta formation, having a positive impact on maternal disease prevention and on fetal development.

Immune checkpoint molecules in pregnancy: Focus on regulatory T cells

Regulatory T (Treg) cells are a specialized subpopulation of T cells that plays critical roles in the maintenance of immune homeostasis. Although efforts have been done, their role in human pregnancy is not fully understood. Numerous studies reported the presence of Treg cells throughout gestation by promoting maternal-fetal tolerance and fetal development. Furthermore, Treg population is heterogeneous as it is expressing different immune checkpoint molecules favoring immune suppressive function. Therefore, better understanding of the heterogeneity and function of Treg cells during pregnancy is critical for an effective immune intervention. Latest evidence has shown that several immune checkpoint molecules are closely associated with pregnancy outcome via multiple inhibitory mechanisms. Majority of these studies demonstrated the modulatory effects of immune checkpoint molecules on effector T-cell immunity, but their effects on Treg activation and function are still an enigma. In this review, we emphasize the potential influence of multiple immune checkpoint molecules, including CTLA-4, PD-1, Tim-3, LAG-3, and TIGIT, either in membrane or soluble form, on the function of decidual and peripheral Treg cells during pregnancy. Additionally, we discuss the promising future of targeting Treg cells via immune checkpoint molecules for pregnancy maintenance and prevention of complicated pregnancies.

Vδ2 T cell subsets, defined by PD-1 and TIM-3 expression, present varied cytokine responses in acute myeloid leukemia patients

Vδ2 T cells represent the major γδ T cell subset in humans and can serve as an important early source of TNF-α and IFN-γ during inflammatory responses. In acute myeloid leukemia (AML) patients receiving allogeneic stem cell transplantation, higher γδ T cell count predicted better prognosis. The impact of PD-1 and TIM-3 expression on the function of Vδ2 T cells is yet unclear. In this study, we showed that the frequencies of PD-1⁺TIM-3^- Vδ2 T cells were comparable between healthy controls and AML patients, but the frequencies of PD-1^-TIM-3⁺ Vδ2 T cells and of PD-1⁺TIM-3⁺ Vδ2 T cells were significantly higher in AML patients than in healthy controls. Both PD-1 and TIM-3 were upregulated upon phosphoantigen + IL-2 activation, but the relative differences in the frequencies of various PD-1 vs. TIM-3 subsets between AML patients and healthy controls remained. Interestingly, among all PD-1 vs. TIM-3 subsets, the PD-1⁺TIM-3^- subset presented the highest TNF-α and IFN-γ expression, while the PD-1⁺TIM-3⁺ subset presented the lowest TNF-α and IFN-γ expression. Anti-PD-1 inhibition did not significantly affect the production of TNF-α or IFN-γ, but anti-TIM-3 inhibition and anti-PD-1/TIM-3 dual inhibition significantly elevated the production of TNF-α and IFN-γ. Interestingly, anti-PD-1 blocking antibodies had significantly increased the frequency of TIM-3⁺ cells in Vδ2 T cells, suggesting a compensatory TIM-3 upregulation. In addition, the levels of PD-L1 and HMGB-1 were significantly higher in AML patients than in healthy subjects. In summary, this study provides knowledge on the cytokine expression patterns by PD-1 and/or TIM-3-expressing Vδ2 T cells in AML patients, and indicates that the upregulation of PD-1 alone is insufficient to indicate functional impairment, and Vδ2 T cells may require anti-TIM-3 inhibition for functional revival.

Immune Checkpoint Molecules in Reproductive Immunology

Immune checkpoint molecules, like CTLA-4, TIM-3, PD-1, are negative regulators of immune responses to avoid immune injury. Checkpoint regulators are thought to actively participate in the immune defense of infections, prevention of autoimmunity, transplantation, and tumor immune evasion. Maternal-fetal immunotolerance represents a real immunological challenge for the immune system of the mother: beside acceptance of the semiallogeneic fetus, the maternal immune system has to be prepared for immune defense mostly against infections. In this particular situation, the role of immune checkpoint molecules could be of special interest. In this review, we describe current knowledge on the role of immune checkpoint molecules in reproductive immunology.

New Paradigm in the Role of Regulatory T Cells During Pregnancy

Semi-allogenic fetuses are not rejected by the maternal immune system because feto-maternal tolerance induced by CD4⁺CD25⁺FoxP3⁺ regulatory T (Treg) cells is established during pregnancy. Paternal antigen-specific Treg cells accumulate during pregnancy, and seminal plasma priming plays an important role in expanding paternal antigen-specific Treg cells in mouse models. Although paternal-antigen specific Treg cells have not been identified in humans, recent studies suggest that antigen-specific Treg cells exist and expand at the feto-maternal interface in humans. Studies have also revealed that reduction of decidual functional Treg cells occurs during miscarriage with normal fetal chromosomal content, whereas insufficient clonal expansion of decidual Treg cells is observed in preeclampsia. In this review, we will discuss the recent advances in the investigation of mechanisms underlying Treg cell-dependent maintenance of feto-maternal tolerance.

Involvement of the PD-1/PD-L1 Co-Inhibitory Pathway in the Pathogenesis of the Inflammatory Stage of Early-Onset Preeclampsia

The programmed cell death protein 1 (PD-1) receptor has been reported to downregulate T cell activation effectively via binding to its ligands PD-L1 or PD-L2 in a negative co-stimulatory manner. Little is known about the involvement of PD-1 mediated immunoregulation in pregnancy and in pregnancy-related disorders. In this work, we investigated the possible role of the PD-1 co-stimulatory pathway in the pathogenesis of the clinical phase of early-onset preeclampsia characterized by a systemic maternal inflammatory response. We performed a cross-sectional study for comparative analysis of phenotypic and functional characteristics of peripheral blood mononuclear cells in women with early-onset preeclampsia and third-trimester healthy pregnant controls. According to our findings, enhanced expression of either PD-1 or its ligand PD-L1, or both, on the cell surface of effector cells (T cells, natural killer (NK) cells, natural killer T (NKT)-like cells) and Tregs could be observed, but PD-1 expression did not correlate with effector cells exhaustion. These results suggest the failure of the axis to downregulate Th1 responses, contributing thereby to the exaggerated immunoactivation observed in early-onset preeclampsia.

FAS A-670G and Fas ligand IVS2nt A 124G polymorphisms are significantly increased in women with pre-eclampsia and may contribute to HELLP syndrome: a case-controlled study

OBJECTIVE

We evaluated the association between the Fas-670A/G and the Fas ligand FasL IVS2nt 124 A/G polymorphisms and the risk of pre-eclampsia and its complications.

DESIGN

A case-controlled study.

SETTING

University Hospitals in most areas of Tunisia.

POPULATION

We recruited 300 pregnant women who developed pre-eclampsia and 300 age-matched healthy pregnant women from the same hospital.

METHODS

Genotyping of Fas-670A/G and the FasL IVS2nt 124A/G gene polymorphisms were conducted using polymerase chain reaction-restriction fragment length polymorphism among our cohort.

MAIN OUTCOME MEASURES

Fisher's exact test was used to compare the statistical differences between groups for categorical variables and Student t tests were used for continuous variables.

RESULTS

The frequency of the Fas-670G gene variant was significantly increased in women with pre-eclampsia (42%) compared with control women (30%; P < 0.001). Also, a statistically significant difference was obtained in the distribution of the FasL IVS2nt 124G gene variant when comparing women with pre-eclampsia (43%) with controls (30%; P < 0.001). Interestingly, we found that the carriage of Fas-670G was associated with increased liver enzymes, suggesting an increased prevalence of the haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome, a pre-eclampsia complication.

CONCLUSION

The Fas-670G and FasL IVS2nt 124G polymorphisms are associated with a higher risk of pre-eclampsia and its complications.

TWEETABLE ABSTRACT

Polymorphisms in the Fas and FasL genes are associated with increased risk of pre-eclampsia and HELLP syndrome.

Improving the Efficiency of Vγ9Vδ2 T-Cell Immunotherapy in Cancer

Increasing immunological knowledge and advances in techniques lay the ground for more efficient and broader application of immunotherapies. gamma delta (γδ) T-cells possess multiple favorable anti-tumor characteristics, making them promising candidates to be used in cellular and combination therapies of cancer. They recognize malignant cells, infiltrate tumors, and depict strong cytotoxic and pro-inflammatory activity. Here, we focus on human Vγ9Vδ2 T-cells, the most abundant γδ T-cell subpopulation in the blood, which are able to inhibit cancer progression in various models in vitro and in vivo. For therapeutic use they can be cultured and manipulated ex vivo and in the following adoptively transferred to patients, as well as directly stimulated to propagate in vivo. In clinical studies, Vγ9Vδ2 T-cells repeatedly demonstrated a low toxicity profile but hitherto only the modest therapeutic efficacy. This review provides a comprehensive summary of established and newer strategies for the enhancement of Vγ9Vδ2 T-cell anti-tumor functions. We discuss data of studies exploring methods for the sensitization of malignant cells, the improvement of recognition mechanisms and cytotoxic activity of Vγ9Vδ2 T-cells. Main aspects are the tumor cell metabolism, antibody-dependent cell-mediated cytotoxicity, antibody constructs, as well as activating and inhibitory receptors like NKG2D and immune checkpoint molecules. Several concepts show promising results in vitro, now awaiting translation to in vivo models and clinical studies. Given the array of research and encouraging findings in this area, this review aims at optimizing future investigations, specifically targeting the unanswered questions.

Depletion of MHC class II invariant chain peptide or γ–δ T-cells ameliorates experimental preeclampsia

Excessive innate immune system activation and inflammation during pregnancy can lead to organ injury and dysfunction and preeclampsia (PE); however, the molecular mechanisms involved are unknown. We tested the hypothesis that Toll-like receptor (TLR) activation induces major histocompatibility complex (MHC) class II invariant chain peptide (CLIP) expression on immune cells, makes them pro-inflammatory, and are necessary to cause PE-like features in mice. Treatment with VG1177, a competitive antagonist peptide for CLIP in the groove of MHC class II, was able to both prevent and treat PE-like features in mice. We then determined that γ–δ T cells are critical for the development of PE-like features in mice since γ–δ T-cell knockout mice, like CLIP deficient mice, are resistant to developing PE-like features. Placentas from women with PE exhibit significantly increased levels of γ–δ T cells. These preclinical data demonstrate that CLIP expression and activated γ–δ T cells are responsible for the development of immunologic PE-like features and that temporarily antagonizing CLIP and/or γ–δ T cells may be a therapeutic strategy for PE.

Recent Advances in Immunity and Hypertension

Persistent immune system activation plays an important role in the development of various forms of hypertension. Activation of the innate immune system, inflammation, and subsequent adaptive immune system response causing end-organ injury and dysfunction ultimately leads to hypertension and its associated sequelae including coronary artery disease, heart failure, stroke, and chronic kidney disease. In this review, we will provide updates on the innate and adaptive immune cells involved in hypertension, the current understanding of how the immune system gets activated, and examine the recently discovered mechanisms involved in several forms of experimental hypertension.

Synergistic effect of IL-12 and IL-18 induces TIM3 regulation of γδ T cell function and decreases the risk of clinical malaria in children living in Papua New Guinea

BACKGROUND

γδ T cells are important for both protective immunity and immunopathogenesis during malaria infection. However, the immunological processes determining beneficial or detrimental effects on disease outcome remain elusive. The aim of this study was to examine expression and regulatory effect of the inhibitory receptor T-cell immunoglobulin domain and mucin domain 3 (TIM3) on γδ T cells. While TIM3 expression and function on conventional αβ T cells have been clearly defined, the equivalent characterization on γδ T cells and associations with disease outcomes is limited. This study investigated the functional capacity of TIM3+ γδ T cells and the underlying mechanisms contributing to TIM3 upregulation and established an association with malaria disease outcomes.

METHODS

We analyzed TIM3 expression on γδ T cells in 132 children aged 5-10 years living in malaria endemic areas of Papua New Guinea. TIM3 upregulation and effector functions of TIM3+ γδ T cells were assessed following in vitro stimulation with parasite-infected erythrocytes, phosphoantigen and/or cytokines. Associations between the proportion of TIM3-expressing cells and the molecular force of infection were tested using negative binomial regression and in a Cox proportional hazards model for time to first clinical episode. Multivariable analyses to determine the association of TIM3 and IL-18 levels were conducted using general linear models. Malaria infection mouse models were utilized to experimentally investigate the relationship between repeated exposure and TIM3 upregulation.

RESULTS

This study demonstrates that even in the absence of an active malaria infection, children of malaria endemic areas have an atypical population of TIM3-expressing γδ T cells (mean frequency TIM3+ of total γδ T cells 15.2% ± 12). Crucial factors required for γδ T cell TIM3 upregulation include IL-12/IL-18, and plasma IL-18 was associated with TIM3 expression (P = 0.002). Additionally, we show a relationship between TIM3 expression and infection with distinct parasite clones during repeated exposure. TIM3+ γδ T cells were functionally impaired and were associated with asymptomatic malaria infection (hazard ratio 0.54, P = 0.032).

CONCLUSIONS

Collectively our data demonstrate a novel role for IL-12/IL-18 in shaping the innate immune response and provide fundamental insight into aspects of γδ T cell immunoregulation. Furthermore, we show that TIM3 represents an important γδ T cell regulatory component involved in minimizing malaria symptoms.

Dysregulation of the Fas/FasL system in an experimental animal model of HELLP syndrome

INTRODUCTION

Placental FasL is up-regulated in women with HELLP (hemolysis elevated liver enzyme and low platelet) syndrome and has been proposed to contribute to the liver damage seen in these patients.

OBJECTIVE

This study aimed to determine if an experimental rodent model of HELLP also had dysregulation of Fas/FasL compared to normal pregnant (NP) rats. We also set out to determine if blockade of the endothelin system regulated Fas/FasL expression in HELLP rats.

STUDY DESIGN

On gestational day (GD) 12, sEng (7ug/kg) and sFlt-1 (4.7ug/kg) infusion began via mini-osmotic pump into NP rats. On GD19 plasma and tissue were collected and FasL and Fas were measured via enzyme linked immunosorbent assay and gene expression via real-time PCR.

RESULTS

HELLP rats had significantly more circulating and placental FasL compared to NP rats, whereas hepatic FasL was decreased and placental Fas was increased compared to NP rats. Administration of an endothelin A receptor antagonist (ET_A) beginning on GD12 significantly decreased placental expression of Fas in HELLP rats. Liver mRNA transcript of Fas was significantly increased in HELLP rats compared to NP rats.

CONCLUSION

These data suggest that rats in this experimental model of HELLP syndrome have abnormal expression of the Fas/FasL system. Future studies will examine the sources of Fas/FasL dysregulation in this model and if blockade could reduce some of the inflammation and hypertension associated with HELLP syndrome.

Tim-3: Expression on immune cells and roles at the maternal-fetal interface

Successful pregnancy relies on the accurate regulation of the maternal-fetal immune system. Without enough tolerance in the uterine microenvironment, the mother and the hemiallogeneic fetus could not peacefully coexist. T cell immunoglobulin and mucin domain (Tim)-3 is a molecule originally regarded as to be expressed on terminally differentiated IFN-γ expressing CD4⁺ T cells (Th1). The engagement of Tim-3 with its ligand, galectin-9 (Gal-9) could induce the exhaustion or apoptosis of effector T cells, and thus might regulate the tolerance. Tim-3 pathway also participates in regulating the activities of CD4⁺ regulatory T cells, monocyte-macrophages, dendritic cells and natural killer cells. Dysregulation of Tim-3 expression can elicit excessive or inhibited inflammatory responses and ultimately result in autoimmune diseases, viral or tumor evasion and pregnancy complications. In this review, we will mainly focus on the expression of Tim-3 on local immune cells and its function in pregnancy. In addition, meaningful questions that need further investigation and the potential roles of Tim-3 in fetal tolerance will be discussed. Deeper understanding of the immune checkpoint receptor Tim-3 will shed new light on exploring the pathogenesis of some pregnancy complications, including pre-eclampsia, intrauterine growth restriction, recurrent spontaneous abortion and preterm birth. Tim-3 pathway might be a new target of immune therapy for pregnancy complications in the future.

Reduced pro-inflammatory profile of γδT cells in pregnant patients with rheumatoid arthritis

Background

During pregnancy, many patients with rheumatoid arthritis (RA) experience disease improvement, whereas patients with ankylosing spondylitis often suffer from persistent active disease. Here we investigated whether pregnancy-related changes in disease activity were associated with changes in the proportion and function of γδT cells.

Methods

The study population comprised 55 patients with RA, 31 patients with ankylosing spondylitis, and 35 healthy controls. Among these participants, 28 RA patients, 21 ankylosing spondylitis patients, and 23 healthy controls were investigated once before conception when possible, at each trimester of pregnancy, and at 8 weeks postpartum. Data were compared with age-matched non-pregnant patients to obtain disease-related background. In all subjects, peripheral Vδ1 and Vδ2 T cells were analyzed for cell frequencies, the activation marker CD69, the cytotoxicity markers NKG2D and NKG2A, and the intracellular cytokines tumor necrosis factor (TNF)α, interferon (IFN)γ, interleukin (IL)-17 and IL-10.

Results

Pregnant patients showed a decreased Vδ2/Vδ1 ratio in the third trimester, which resulted from a slightly reduced proportion of Vδ2 cells. Changes in RA disease activity during pregnancy and postpartum were not associated with numerical proportions of γδT cells but with changes of the cell activation marker CD69 on Vδ1 and Vδ2 cells. Only RA patients showed reduced proportions of TNFα-positive Vδ1and Vδ2 cells and IFNγ-positive Vδ2 cells at the third trimester of pregnancy, a finding that was not apparent in the entire population of CD3 T cells. The proportions of IL-17-positive γδT cells and IL-10-positive γδT cells did not differ between pregnant and non-pregnant women of the different groups.

Conclusions

Changes of disease activity in pregnant RA patients were associated with functional changes in both γδT cell subsets. This reduced pro-inflammatory profile of γδT cells might contribute to the immunomodulation resulting in pregnancy-induced improvement of RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0925-1) contains supplementary material, which is available to authorized users.

Regulatory T-cells and preeclampsia: an overview of literature

Regulatory T-cells (Tregs) are key players in successful pregnancy and their deficiencies are implicated in pregnancy complications such as preeclampsia (PE), but the results are inconsistent among studies. This study aims to compile an overview of the studies about the associations of Tregs and PE risk and to provide recommendations for future research. A sensitive search of three databases including PubMed, Scopus and Google scholar (from 1995 to January 9, 2015) identified 636 unique titles. An accurate process of study selection, data extraction and method qualification were independently conducted by authors on retrieved papers. Seventeen papers met the inclusion criteria and were included in quality assessment. Regarding the source of Tregs, 14 studies assessed Tregs in peripheral blood, 2 studies in peripheral blood and decidua and one study in peripheral blood and umbilical cord blood. Despite variation in the combinations of markers and other aspects of the studies designs, remarkable constancy in the results of studies that measured Tregs as CD4+FoxP3+ or CD4+CD25+FoxP3+ cells (but not CD4+CD25(high/low)FoxP3+ markers) was found, which in broad terms showed a shift towards fewer Treg cells in PE. This review revealed an association between lower percentage of circulating CD4+FoxP3+ or CD4+CD25+FoxP3+ Tregs and the risk of PE. Given the above issue and regarding the high consistency of studies on reduction of suppressive activity of Tregs in PE, we have proposed a model in which the Tregs deficiency is a reflection of immune endocrine imbalance, which reverses maternal tolerance and results in development of preeclampsia.

Four Pathways Involving Innate Immunity in the Pathogenesis of Preeclampsia

The maternal innate immune system plays an important role both in normal pregnancy as well as hypertensive disorders of pregnancy including preeclampsia (PE). We propose four pathways that involve excessive innate immunity that lead to most forms of PE. Pre-existing endothelial dysfunction plus pregnancy leads to an excessive innate immune response resulting in widespread inflammation, placental and renal dysfunction, vasoconstriction, and PE. Placental dysfunction due to shallow trophoblast invasion, inadequate spiral artery remodeling, and/or low placental perfusion initiates an innate immune response leading to excessive inflammation, endothelial and renal dysfunction, and PE. A heightened innate immune system due to pre-existing or acquired infections plus the presence of a paternally derived placenta and semi-allogeneic fetus cause an excessive innate immune response which manifests as PE. Lastly, an abnormal and excessive maternal immune response to pregnancy leads to widespread inflammation, organ dysfunction, and PE. We discuss the potential role of innate immunity in each of these scenarios, as well as the overlap, and how targeting the innate immune system might lead to therapies for the treatment of PE.

Regulatory T cells: new keys for further unlocking the enigma of fetal tolerance and pregnancy complications

The immunological alterations required for successful pregnancy in eutherian placental mammals have remained a scientific enigma since the discovery of MHC haplotype diversity and unique immune signatures among individuals. Within the past 10 years, accumulating data suggest that immune-suppressive regulatory T cells (Tregs) confer essential protective benefits in sustaining tolerance to the semiallogeneic fetus during pregnancy, along with their more established roles in maintaining tolerance to self and "extended self" commensal Ags that averts autoimmunity. Reciprocally, many human pregnancy complications stemming from inadequacies in fetal tolerance have been associated with defects in maternal Tregs. Thus, further elucidating the immunological shifts during pregnancy not only have direct translational implications for improving perinatal health, they have enormous potential for unveiling new clues about how Tregs work in other biological contexts. In this article, epidemiological data in human pregnancy and complementary animal studies implicating a pivotal protective role for maternal Tregs are summarized.

Innate immune system and preeclampsia

Normal pregnancy is considered as a Th2 type immunological state that favors an immune-tolerance environment in order to prevent fetal rejection. Preeclampsia (PE) has been classically described as a Th1/Th2 imbalance; however, the Th1/Th2 paradigm has proven insufficient to fully explain the functional and molecular changes observed during normal/pathological pregnancies. Recent studies have expanded the Th1/Th2 into a Th1/Th2/Th17 and regulatory T-cells paradigm and where dendritic cells could have a crucial role. Recently, some evidence has emerged supporting the idea that mesenchymal stem cells might be part of the feto-maternal tolerance environment. This review will discuss the involvement of the innate immune system in the establishment of a physiological environment that favors pregnancy and possible alterations related to the development of PE.

Tim-3: an activation marker and activation limiter of innate immune cells

Tim-3 was initially identified on activated Th1, Th17, and Tc1 cells and induces T cell death or exhaustion after binding to its ligand, Gal-9. The observed relationship between dysregulated Tim-3 expression on T cells and the progression of many clinical diseases has identified this molecule as an important target for intervention in adaptive immunity. Recent data have shown that it also plays critical roles in regulating the activities of macrophages, monocytes, dendritic cells, mast cells, natural killer cells, and endothelial cells. Although the underlying mechanisms remain unclear, dysregulation of Tim-3 expression on these innate immune cells leads to an excessive or inhibited inflammatory response and subsequent autoimmune damage or viral or tumor evasion. In this review, we focus on the expression and function of Tim-3 on innate immune cells and discuss (1) how Tim-3 is expressed and regulated on different innate immune cells; (2) how it affects the activity of different innate immune cells; and (3) how dysregulated Tim-3 expression on innate immune cells affects adaptive immunity and disease progression. Tim-3 is involved in the optimal activation of innate immune cells through its varied expression. A better understanding of the physiopathological role of the Tim-3 pathway in innate immunity will shed new light on the pathogenesis of clinical diseases, such as autoimmune diseases, chronic viral infections, and cancer, and suggest new approaches to intervention.

Is the prevalence of pre-eclampsia affected by HIV/AIDS? A retrospective case-control study

OBJECTIVE

To evaluate the rate of HIV/AIDS (and CD4 levels) in women with pre-eclampsia compared to that of a control group.

METHODS

This was a retrospective case-control study in a tertiary and regional hospital in South Africa. We reviewed the hospital records of women who had delivered in these hospitals between 1 January 2008 and 30 June 2010. The records of women with pre-eclampsia during the study period were analysed. Their HIV infection rate was compared to that of a control group consisting of normotensive healthy pregnant women.

RESULTS

Among 492 cases of pre-eclampsia, 130 (26.4%) were HIV infected. In the control group, 183/500 (36.6%) were HIV infected (p = 0.001, OR = 0.62, 95% CI: 0.47-0.82). After adjustment to match the difference in maternal age and parity, the rate of HIV/AIDS was lower in the pre-eclamptic group than in the control group (p = 0.005, OR = 0.658).

CONCLUSION

The rate of HIV/AIDS was significantly lower in women with pre-eclampsia than in normotensive healthy pregnant women.

Anergic pulmonary tuberculosis is associated with contraction of the Vd2+T cell population, apoptosis and enhanced inhibitory cytokine production

Objective

To study the association of anergic pulmonary tuberculosis with Vδ2⁺ T cells and related cytokine levels.

Methods

82 pulmonary tuberculosis patients were divided into two groups according to their purified protein derivative tuberculin skin test (TST) results: 39 with TST-negative anergic pulmonary tuberculosis and 43 with TST-positive pulmonary tuberculosis, while 40 healthy volunteers were used as control. Based on chest X-ray results, the tuberculosis lesions were scored according to their severity, with a score of ≤ 2.5 ranking as mild, 2.5-6 as moderate and ≥ 6 as severe. The Vδ2⁺ T cell percentage and their expression levels of the apoptosis-related membrane surface molecule FasL in peripheral blood and bronchoalveolar lavage fluids (BALF) were analyzed by flow cytometry, while IL-2, IL-4, IL-6 and IL-10 cytokine and γ-interferon (γ-IFN) concentrations in peripheral blood were determined by ELISA.

Results

Most of the patients with chest X-ray lesion scores higher than 6 belonged to the anergic tuberculosis group (P<0.05). Anergic pulmonary tuberculosis patients displayed reduced peripheral blood Vδ2⁺ T cell counts (P<0.05) and higher FasL expression in peripheral blood Vδ2 ⁺ T cells (P <0.05). The Vδ2⁺ T cell percentages in the BALF of all tuberculosis patients were lower than in their peripheral blood (P <0.05), and IL-4 and IL-10 concentrations in peripheral blood of anergic tuberculosis patients were higher than in TST-positive tuberculosis patients and healthy controls (P <0.05).

Conclusion

Anergic pulmonary tuberculosis is accompanied by reduced Vδ2⁺ T cell percentage, and elevated Vδ2⁺ T cell FasL expression as well as enhanced IL-4 and IL-10 levels in peripheral blood.

Involvement of Galectin-9/TIM-3 pathway in the systemic inflammatory response in early-onset preeclampsia

BACKGROUND

Preeclampsia is a common obstetrical disease affecting 3-5% of pregnancies and representing one of the leading causes of both maternal and fetal mortality. Maternal symptoms occur as an excessive systemic inflammatory reaction in response to the placental factors released by the oxidatively stressed and functional impaired placenta. The T-cell immunoglobulin domain and mucin domain (TIM) family is a relatively newly described group of molecules with a conserved structure and important immunological functions. Identification of Galectin-9 as a ligand for TIM-3 has established the Galectin-9/TIM-3 pathway as an important regulator of Th1 immunity and tolerance induction.

METHODS

The aim of our study was to investigate the expression and function of Galectin-9 and TIM-3 molecules by peripheral blood mononuclear cells and the possible role of Galectin-9/TIM-3 pathway in the immunoregulation of healthy pregnancy and early-onset preeclampsia. We determined TIM-3 and Gal-9 expression and cytotoxicicty of peripheral lymphocytes of early-onset preeclamptic women and healthy pregnant woman using flow cytometry.

RESULTS

Investigating peripheral lymphocytes of women with early-onset preeclampsia, our results showed a decreased TIM-3 expression by T cells, cytotoxic T cells, NK cells and CD56(dim) NK cells compared to healthy pregnant women. Interestingly, we found a notably increased frequency of Galectin-9 positive cells in each investigated lymphocyte population in the case of early-onset preeclamptic patients. We further demonstrated increased cytotoxic activity by cytotoxic T and CD56(dim) NK cells in women with early-onset preeclampsia. Our findings showed that the strongest cellular cytotoxic response of lymphocytes occurred in the TIM-3 positive subpopulations of different lymphocytes subsets in early-onset preeclampsia.

CONCLUSION

These data suggest that Gal-9/TIM-3 pathway could play an important role in the immune regulation during pregnancy and the altered Galectin-9 and TIM-3 expression could result an enhanced systemic inflammatory response including the activation of Th1 lymphocytes in preeclampsia.

HIV infection deregulates Tim-3 expression on innate cells: combination antiretroviral therapy results in partial restoration

BACKGROUND

The Tim-3 receptor has been implicated as a negative regulator of adaptive immune responses and has been linked to T-cell dysfunction in chronic viral infections, such as HIV. Blocking Tim-3 has been proposed as a potential therapeutic intervention in HIV infection. However, a more detailed characterization of Tim-3 expression in the presence of HIV is required before such strategies can be considered.

METHODS

In this study, we investigate Tim-3 expression on innate immune cell subsets in chronic HIV-infected individuals pretherapy and posttherapy.

RESULTS

We report that, pretherapy, HIV infection is associated with elevated levels of Tim-3 on resting innate lymphocytes (NK, NKT, and γδ T cells), but not resting monocytes. In the absence of HIV infection, stimulation with an inflammatory stimulus resulted in decreased Tim-3 on monocytes and increased Tim-3 on NK, NKT, and γδ T cells. However, innate cells from HIV-infected donors were significantly less responsive to stimulation. Six months of combination antiretroviral therapy (cART) restored Tim-3 levels on resting NK cells but not NKT or γδ T cells. The responses of all subsets to inflammatory stimuli were restored to some extent with cART but only reached HIV-negative control levels in monocytes and NK cells.

DISCUSSION

These results demonstrate that, during HIV infection, Tim-3 expression on innate cells is dysregulated and that this dysregulation is only partially restored after 6 months of cART. Our findings suggest that Tim-3 is differentially regulated on innate immune effector cells, and have direct implications for strategies designed to block Tim-3-ligand interactions.

γδ-T cells: an unpolished sword in human anti-infection immunity

γδ-T cells represent a small population of immune cells, but play an indispensable role in host defenses against exogenous pathogens, immune surveillance of endogenous pathogenesis and even homeostasis of the immune system. Activation and expansion of γδ-T cells are generally observed in diverse human infectious diseases and correlate with their progression and prognosis. γδ-T cells have both 'innate' and 'adaptive' characteristics in the immune response, and their anti-infection activities are mediated by multiple pathways that are under elaborate regulation by other immune components. In this review, we summarize the current state of the literature and the recent advancements in γδ-T cell-mediated immune responses against common human infectious pathogens. Although further investigation is needed to improve our understanding of the characteristics of different γδ-T cell subpopulations under specific conditions, γδ-T cell-based therapy has great potential for the treatment of infectious diseases.

ADP-ribosylation factor 6 expression and activation are reduced in myometrium in complicated pregnancies

Background

ARF6 (ADP-ribosylation factor 6) small GTP binding protein plays critical roles in actin cytoskeleton rearrangements and membrane trafficking, including internalisation of G protein coupled receptors (GPCR). ARF6 operates by cycling between GDP-bound (inactive) and GTP-bound (active) forms and is a potential regulator of GPCR-mediated uterine activity during pregnancy and labour. ARF6 contains very low intrinsic GTP binding activity and depends on GEFs (guanine nucleotide exchange factors) such as CYTH3 (cytohesin 3) to bind GTP. ARF6 and CYTH3 were originally cloned from human placenta, but there is no information on their expression in other reproductive tissues.

Methods

The expression of ARF6, ARF1, and CYTH1-4 was investigated by measuring mRNA (using RT-PCR) and protein levels (using immunoblotting) in samples of myometrium obtained from non-pregnant women, and women with normal pregnancies, before or after the spontaneous onset of labour. We also analysed myometrial samples from women with spontaneous preterm labour and from women with complicated pregnancies requiring emergency preterm delivery. The GST)-effector pull down assay was used to study the presence of active ARF6 and ARF1 in all myometrial extracts.

Results

ARF6, ARF1 and CYTH3 but not CYTH1, CYTH2 and CYTH4 were expressed in all samples and the levels did not change with pregnancy or labour. However, ARF6 and CYTH3 but not ARF1 levels were significantly reduced in complicated pregnancies. The alterations in the expression of ARF6 and its GEF in human myometrium indicate a potential involvement of this signalling system in modulating the response of myometrial smooth muscle in complicated pregnancies. The levels of ARF6-GTP or ARF1-GTP did not change with pregnancy or labour but ARF6-GTP levels were significantly decreased in women with severe complications of pregnancy.

Conclusions

We have demonstrated a functional ARF6 system in human myometrium and a correlation between ARF6 level and activity in uterine and abnormal pregnancy.

γδ T lymphocytes kill T regulatory cells through CD1d

Coxsackievirus B3 (CVB3) induces myocarditis, an inflammation of the myocardium, in C57Bl/6 male mice but not in mice lacking γδ+ T cells [γδ knockout (γδKO)]. Suppression of myocarditis in γδKO mice corresponds to an increase in CD4(+) CD25(+) FoxP3(+) T regulatory cells. A subpopulation of the T regulatory cells in infected γδKO mice expressed high levels of CD1d, a non-classical major histocompatibility complex class 1-like molecule. Adoptive transfer of CD1d(+) and CD1d(-) CD4(+) CD25(+) cells into infected C57Bl/6 recipients showed that the CD1d(+) subpopulation is substantially more suppressive than the CD1d(-) subpopulation. T cells expressing the γδ T-cell receptor comprised approximately 30-50% of the infiltrating lymphoid cells in the hearts of myocarditic C57Bl/6 mice and approximately half of the γδ+ cells expressed the Vγ4 T-cell receptor. The Vγ4+ cells lysed T regulatory cells from γδKO mice but not from wild-type (C57Bl/6) animals. Lysis was inhibited by antibody to CD1d and zVAD-fmk, a pan-caspase inhibitor. The Vγ4-γδ+ cells were not lytic to T regulatory cells and did not promote myocarditis. These results demonstrate that Vγ4+ cells selectively abrogate T regulatory cells through recognition of CD1d expressed on the regulatory cells and caspase-dependent apoptosis.