γδ T Cells Shape Preimmune Peripheral B Cell Populations

Prospects for γδ T cells and chimeric antigen receptor γδ T cells in cancer immunotherapy

γδ T cells, a type of specialized T cell, differ from alpha-beta T cells due to the presence of γ and δ chain surface T cell receptors. These receptors allow them to directly recognize and bind antigenic molecules without the requirement of attachment to MHC or APC antigen presentation. Given their intrinsic properties and functional versatility, γδ T cells are under intensive investigation as carriers for chimeric antigen receptor (CAR) in the context of cancer therapy. In this regard, γδ CAR-T cells have demonstrated great potential to overcome the limitations of antigen recognition with the help of dual antigen identification mechanisms. However, there are still technological challenges that need to be addressed. This discussion focuses on the research status and future development prospects of γδ T cells and γδ CAR-T cells, aiming to provide valuable insights for the follow-up research and practical application of γδ CAR-T cells.

Uncovering the mysteries of human gamma delta T cells: from origins to novel therapeutics

Gamma delta (γδ) T cells represent a unique and distinct population of lymphocytes that bridge the innate and adaptive immune responses. This functional duality positions them as one of the pivotal elements in the evolution and development of the human body's defense mechanisms. This review aims to provide a comprehensive and in-depth overview of γδ T cells, covering their origins, development, classification, and functional roles in immunology. Special attention is given to their involvement in the pathogenesis of autoimmune and cancer-related diseases-areas that remain subjects of intensive research with many unanswered questions. Additionally, this article explores the therapeutic potential of γδ T cells, which hold promise as a novel approach to treating various difficult-to-manage diseases. The review also presents an analysis of the latest clinical studies utilizing γδ T cells, emphasizing their emerging role in modern medicine. The ultimate goal of this work is to offer a holistic perspective on the current state of research on γδ T cells and their prospective applications in immunotherapy and cancer treatment, highlighting their potential to become a groundbreaking tool in future medical interventions.

Characterization of the Cellular Immune Response to Group B Streptococcal Vaginal Colonization

Introduction

Group B Streptococcus (GBS) asymptomatic colonizes the female genital tract (FGT) but can contribute to adverse pregnancy outcomes including pre-term birth, chorioamnionitis, and neonatal infection. We previously observed that GBS elicits FGT cytokine responses, including IL-17, during murine vaginal colonization; yet the anti-GBS cellular immune response during colonization remained unknown. We hypothesized that GBS may induce cellular immunity, resulting in FGT clearance.

Methods

Herein, we utilize depleting antibodies and knockout mice and performed flow cytometry to investigate cellular immunes responses during GBS colonization.

Results

We found that neutrophils (effectors of the IL-17 response) are important for GBS mucosal control as neutrophil depletion promoted increased GBS burdens in FGT tissues. Flow cytometric analysis of immune populations in the vagina, cervix, and uterus revealed, however, that GBS colonization did not induce a marked increase in FGT CD45+ immune cells. We also found that that Vγ6+ γδ T cells comprise a primary source of FGT IL-17. Finally, using knockout mice, we observed that IL-17-producing γδ T cells are important for the control of GBS in the FGT during murine colonization.

Conclusions

Taken together, this work characterizes FGT cellular immunity and suggests that GBS colonization does not elicit a significant immune response, which may be a bacterial directed adaptive outcome. However, certain FGT immune cells, such as neutrophils and ɣδ T cells, contribute to host defense and control of GBS colonization.

γδ T cell-mediated activation of cDC1 orchestrates CD4+ Th1 cell priming in malaria

γδ T cells facilitate the CD4+ T helper 1 (Th1) cell response against Plasmodium infection by activating conventional dendritic cells (cDCs), although the underlying mechanism remains elusive. Our study revealed that γδ T cells promote the complete maturation and production of interleukin-12 and CXCR3-ligands specifically in type 1 cDCs (cDC1), with minimal impact on cDC2 and monocyte derived DCs (Mo-DCs). During the initial infection phase, γδ T cell activation and temporal accumulation in the splenic white pulp, alongside cDC1, occur via CCR7-signaling. Furthermore, cDC1/γδ T cell interactions in the white pulp are amplified through CXCR3 signaling in γδ T cells, optimizing Th1 cell priming by cDC1. We also demonstrated how transitional Th1 cells arise in the white pulp before establishing their presence in the red pulp as fully differentiated Th1 cells. Additionally, we elucidate the reciprocal activation between γδ T cells and cDC1s. These findings suggest that Th1 cell priming is orchestrated by this reciprocal activation in the splenic white pulp during the early phase of blood-stage Plasmodium infection.

Splenic marginal zone B cells restrict Mycobacterium tuberculosis infection by shaping the cytokine pattern and cell-mediated immunity

Understanding the role of B cells in tuberculosis (TB) is crucial for developing new TB vaccines. However, the changes in B cell immune landscapes during TB and their functional implications remain incompletely explored. Using high-dimensional flow cytometry to map the immune landscape in response to Mycobacterium tuberculosis (Mtb) infection, our results show an accumulation of marginal zone B (MZB) cells and other unconventional B cell subsets in the lungs and spleen, shaping an unconventional B cell landscape. These MZB cells exhibit activated and memory-like phenotypes, distinguishing their functional profiles from those of conventional B cells. Notably, functional studies show that MZB cells produce multiple cytokines and contribute to systemic protection against TB by shaping cytokine patterns and cell-mediated immunity. These changes in the immune landscape are reversible upon successful TB chemotherapy. Our study suggests that, beyond antibody production, targeting the regulatory function of B cells may be a valuable strategy for TB vaccine development.

CAR products from novel sources: a new avenue for the breakthrough in cancer immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has transformed cancer immunotherapy. However, significant challenges limit its application beyond B cell-driven malignancies, including limited clinical efficacy, high toxicity, and complex autologous cell product manufacturing. Despite efforts to improve CAR T cell therapy outcomes, there is a growing interest in utilizing alternative immune cells to develop CAR cells. These immune cells offer several advantages, such as major histocompatibility complex (MHC)-independent function, tumor microenvironment (TME) modulation, and increased tissue infiltration capabilities. Currently, CAR products from various T cell subtypes, innate immune cells, hematopoietic progenitor cells, and even exosomes are being explored. These CAR products often show enhanced antitumor efficacy, diminished toxicity, and superior tumor penetration. With these benefits in mind, numerous clinical trials are underway to access the potential of these innovative CAR cells. This review aims to thoroughly examine the advantages, challenges, and existing insights on these new CAR products in cancer treatment.

Adenosine 2A receptor contributes to the facilitation of post-infectious irritable bowel syndrome by γδ T cells via the PKA/CREB/NF-κB signaling pathway

BACKGROUND

Immunological dysfunction-induced low-grade inflammation is regarded as one of the predominant pathogenetic mechanisms in post-infectious irritable bowel syndrome (PI-IBS). γδ T cells play a crucial role in innate and adaptive immunity. Adenosine receptors expressed on the surface of γδ T cells participate in intestinal inflammation and immunity regulation.

AIM

To investigate the role of γδ T cell regulated by adenosine 2A receptor (A2AR) in PI-IBS.

METHODS

The PI-IBS mouse model has been established with Trichinella spiralis (T. spiralis) infection. The intestinal A2AR and A2AR in γδ T cells were detected by immunohistochemistry, and the inflammatory cytokines were measured by western blot. The role of A2AR on the isolated γδ T cells, including proliferation, apoptosis, and cytokine production, were evaluated in vitro. Their A2AR expression was measured by western blot and reverse transcription polymerase chain reaction (RT-PCR). The animals were administered with A2AR agonist, or A2AR antagonist. Besides, γδ T cells were also injected back into the animals, and the parameters described above were examined, as well as the clinical features. Furthermore, the A2AR-associated signaling pathway molecules were assessed by western blot and RT-PCR.

RESULTS

PI-IBS mice exhibited elevated ATP content and A2AR expression (P < 0.05), and suppression of A2AR enhanced PI-IBS clinical characteristics, indicated by the abdominal withdrawal reflex and colon transportation test. PI-IBS was associated with an increase in intestinal T cells, and cytokine levels of interleukin-1 (IL-1), IL-6, IL-17A, and interferon-α (IFN-α). Also, γδ T cells expressed A2AR in vitro and generated IL-1, IL-6, IL-17A, and IFN-α, which can be controlled by A2AR agonist and antagonist. Mechanistic studies demonstrated that the A2AR antagonist improved the function of γδ T cells through the PKA/CREB/NF-κB signaling pathway.

CONCLUSION

Our results revealed that A2AR contributes to the facilitation of PI-IBS by regulating the function of γδ T cells via the PKA/CREB/NF-κB signaling pathway.

The function of γδ T cells in humoral immune responses

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.

A Distinctive γδ T Cell Repertoire in NOD Mice Weakens Immune Regulation and Favors Diabetic Disease

Previous studies in mice and humans suggesting that γδ T cells play a role in the development of type 1 diabetes have been inconsistent and contradictory. We attempted to resolve this for the type 1 diabetes-prone NOD mice by characterizing their γδ T cell populations, and by investigating the functional contributions of particular γδ T cells subsets, using Vγ-gene targeted NOD mice. We found evidence that NOD Vγ4+ γδ T cells inhibit the development of diabetes, and that the process by which they do so involves IL-17 production and/or promotion of regulatory CD4+ αβ T cells (Tregs) in the pancreatic lymph nodes. In contrast, the NOD Vγ1+ cells promote diabetes development. Enhanced Vγ1+ cell numbers in NOD mice, in particular those biased to produce IFNγ, appear to favor diabetic disease. Within NOD mice deficient in particular γδ T cell subsets, we noted that changes in the abundance of non-targeted T cell types also occurred, which varied depending upon the γδ T cells that were missing. Our results indicate that while certain γδ T cell subsets inhibit the development of spontaneous type 1 diabetes, others exacerbate it, and they may do so via mechanisms that include altering the levels of other T cells.

γδ T cells license immature B cells to produce a broad range of polyreactive antibodies

Immature autoreactive B cells are present in all healthy individuals, but it is unclear which signals are required for their maturation into antibody-producing cells. Inducible depletion of γδ T cells show that direct interaction between γδ T cells and immature B cells in the spleen support an "innate" transition to mature B cells with a broad range of antigen specificities. IL-4 production of γδ T cells and cell-to-cell contact via CD30L support B cell maturation and induce genes of the unfolded protein response and mTORC1 signaling. Eight days after in vivo depletion of γδ T cells, increased numbers of B cells are already stuck in the transitional phase and express increased levels of IgD and CD21. Absence of γδ T cells leads also to reduced levels of serum anti-nuclear autoantibodies, making γδ T cells an attractive target to treat autoimmunity.

Becoming aware of γδ T cells

The discovery that B cells and αβ T cells exist was predictable: These cells gave themselves away through their products and biological effects. In contrast, there was no reason to anticipate the existence of γδ T cells. Even the accidental discovery of a novel TCR-like gene (later named γ) that did not encode TCR α or β proteins did not immediately change this. TCR-like γ had no obvious function, and its early expression in the thymus encouraged speculation about a possible role in αβ T cell development. However, the identification of human PBL-derived cell-lines which expressed CD3 in complex with the TCR-like γ protein, but not the αβ TCR, first indicated that a second T cell-type might exist, and the TCR-like γ chain was observed to co-precipitate with another protein. Amid speculation about a possible second TCR, this potential dimeric partner was named δ. To determine if the δ protein was indeed TCR-like, we undertook to sequence it. Meanwhile, a fourth TCR-like gene was discovered and provisionally named x. TCR-like x had revealed itself through genomic rearrangements early in T cell development, and was an attractive candidate for the gene encoding δ. The observation that δ protein sequences matched the predicted amino acid sequences encoded by the x gene, as well as serological cross-reactivity, confirmed that the TCR-like x gene indeed encoded the δ protein. Thus, the γδ heterodimer was established as a second TCR, and the cells that express it (the γδ T cells) consequently represented a third lymphocyte-population with the potential of recognizing diverse antigens. Soon, it became clear that γδ T cells are widely distributed and conserved among the vertebrate species, implying biological importance. Consistently, early functional studies revealed their roles in host resistance to pathogens, tissue repair, immune regulation, metabolism, organ physiology and more. Albeit discovered late, γδ T cells have repeatedly proven to play a distinct and often critical immunological role, and now generate much interest.

Properties and Roles of γδT Cells in Plasmodium yoelii nigeriensis NSM Infected C57BL/6 Mice

Background

Many kinds of immune cells are involved in malaria infection. γδT cells represent a special type of immune cell between natural and adaptive immune cells that play critical roles in anti-parasite infection.

Methods

In this study, malaria infection model was constructed. Distribution of γδT cells in various immune organs and dynamic changes of γδT cells in the spleens of C57BL/6 mice after infection were detected by flow cytometry. And activation status of γδT cells was detected by flow cytometry. Then γδT cells in naive and infected mice were sorted and performed single-cell RNA sequencing (scRNA-seq). Finally, γδTCR KO mice model was constructed and the effect of γδT cell depletion on mouse T and B cell immunity against Plasmodium infection was explored.

Results

Here, splenic γδT cells were found to increase significantly on day 14 after Plasmodium yoelii nigeriensis NSM infection in C57BL/6 mice. Higher level of CD69, ICOS and PD-1, lower level of CD62L, and decreased IFN-γ producing after stimulation by PMA and ionomycin were found in γδT cells from infected mice, compared with naive mice. Moreover, 11 clusters were identified in γδT cells by scRNA-seq based t-SNE analysis. Cluster 4, 5, and 7 in γδT cells from infected mice were found the expression of numerous genes involved in immune response. In the same time, the GO enrichment analysis revealed that the marker genes in the infection group were involved in innate and adaptive immunity, pathway enrichment analysis identified the marker genes in the infected group shared many key signalling molecules with other cells or against pathogen infection. Furthermore, increased parasitaemia, decreased numbers of RBC and PLT, and increased numbers of WBC were found in the peripheral blood from γδTCR KO mice. Finally, lower IFN-γ and CD69 expressing CD4⁺ and CD8⁺ T cells, lower B cell percentage and numbers, and less CD69 expressing B cells were found in the spleen from γδTCR KO infected mice, and lower levels of IgG and IgM antibodies in the serum were also observed than WT mice.

Conclusions

Overall, this study demonstrates the diversity of γδT cells in the spleen of Plasmodium yoelii nigeriensis NSM infected C57BL/6 mice at both the protein and RNA levels, and suggests that the expansion of γδT cells in cluster 4, 5 and 7 could promote both cellular and humoral immune responses.

Influence of Consumption of Two Peruvian Cocoa Populations on Mucosal and Systemic Immune Response in an Allergic Asthma Rat Model

Different cocoa populations have demonstrated a protective role in a rat model of allergic asthma by attenuating the immunoglobulin (Ig) E synthesis and partially protecting against anaphylactic response. The aim of this study was to ascertain the effect of diets containing two native Peruvian cocoa populations (“Amazonas Peru” or APC, and “Criollo de Montaña” or CMC) and an ordinary cocoa (OC) on the bronchial compartment and the systemic and mucosal immune system in the same rat model of allergic asthma. Among other variables, cells and IgA content in the bronchoalveolar lavage fluid (BALF) and serum anti-allergen antibody response were analyzed. The three cocoa populations prevented the increase of the serum specific IgG1 (T helper 2 isotype). The three cocoa diets decreased asthma-induced granulocyte increase in the BALF, which was mainly due to the reduction in the proportion of eosinophils. Moreover, both the OC and CMC diets were able to prevent the leukocyte infiltration caused by asthma induction in both the trachea and nasal cavity and decreased the IgA in both fecal and BALF samples. Overall, these results highlight the potential of different cocoa populations in the prevention of allergic asthma.

The Diverse Roles of γδ T Cells in Cancer: From Rapid Immunity to Aggressive Lymphoma

γδ T cells are unique players in shaping immune responses, lying at the intersection between innate and adaptive immunity. Unlike conventional αβ T cells, γδ T cells largely populate non-lymphoid peripheral tissues, demonstrating tissue specificity, and they respond to ligands in an MHC-independent manner. γδ T cells display rapid activation and effector functions, with a capacity for cytotoxic anti-tumour responses and production of inflammatory cytokines such as IFN-γ or IL-17. Their rapid cytotoxic nature makes them attractive cells for use in anti-cancer immunotherapies. However, upon transformation, γδ T cells can give rise to highly aggressive lymphomas. These rare malignancies often display poor patient survival, and no curative therapies exist. In this review, we discuss the diverse roles of γδ T cells in immune surveillance and response, with a particular focus on cancer immunity. We summarise the intriguing dichotomy between pro- and anti-tumour functions of γδ T cells in solid and haematological cancers, highlighting the key subsets involved. Finally, we discuss potential drivers of γδ T-cell transformation, summarising the main γδ T-cell lymphoma/leukaemia entities, their clinical features, recent advances in mapping their molecular and genomic landscapes, current treatment strategies and potential future targeting options.

IL-4-Producing Vγ1+/Vδ6+ γδ T Cells Sustain Germinal Center Reactions in Peyer's Patches of Mice

The mucosal immune system is the first line of defense against pathogens. Germinal centers (GCs) in the Peyer's patches (PPs) of the small intestine are constantly generated through stimulation of the microbiota. In this study, we investigated the role of γδ T cells in the GC reactions in PPs. Most γδ T cells in PPs localized in the GCs and expressed a TCR composed of Vγ1 and Vδ6 chains. By using mice with partial and total γδ T cell deficiencies, we found that Vγ1+/Vδ6+ T cells can produce high amounts of IL-4, which drives the proliferation of GC B cells as well as the switch of GC B cells towards IgA. Therefore, we conclude that γδ T cells play a role in sustaining gut homeostasis and symbiosis via supporting the GC reactions in PPs.

HVEM Promotes the Osteogenesis of allo-MSCs by Inhibiting the Secretion of IL-17 and IFN-γ in Vγ4T Cells

Bone defects are a common orthopaedic concern, and an increasing number of tissue-engineered bones (TEBs) are used to repair bone defects. Allogeneic mesenchymal stem cells (allo-MSCs) are used as seed cells in many approaches to develop TEB constructs, but the immune response caused by allogeneic transplantation may lead to transplant failure. V gamma 4 T (Vγ4T) cells play an important role in mediating the immune response in the early stage after transplantation; therefore, we wanted to verify whether suppressing Vγ4T cells by herpesvirus entry mediator (HVEM)/B and T lymphocyte attenuator (BTLA) signalling can promote MSCs osteogenesis in the transplanted area. In vitro experiments showed that the osteogenic differentiation of MSCs and Vγ4T cells was weakened after co-culture, and an increase in interleukin-17 (IL-17) and interferon-γ (IFN-γ) levels was detected in the culture supernatant. HVEM-transfected MSCs (MSCs-HVEM) still exhibited osteogenic differentiation activity after co-culture with Vγ4T cells, and the levels of IL-17 and IFN-γ in the co-culture supernatant were significantly reduced. In vivo experiments revealed that inflammation in the transplanted area was reduced and osteogenic repair was enhanced after Vγ4T cells were removed. MSCs-HVEM can also consistently contribute to reduced inflammation in the transplanted area and enhanced bone repair in wild-type (WT) mice. Therefore, our experiments verified that HVEM can promote the osteogenesis of allo-MSCs by inhibiting IL-17 and IFN-γ secretion from Vγ4T cells.

T Cells in Systemic Lupus Erythematosus

T-cell dysregulation has been implicated in the loss of tolerance and overactivation of B cells in systemic lupus erythematosus (SLE). Recent studies have identified T-cell subsets and genetic, epigenetic, and environmental factors that contribute to pathogenic T-cell differentiation, as well as disease pathogenesis and clinical phenotypes in SLE. Many therapeutics targeting T-cell pathways are under development, and although many have not progressed in clinical trials, the recent approval of the calcineurin inhibitor voclosporin is encouraging. Further study of T-cell subsets and biomarkers of T-cell action may pave the way for specific targeting of pathogenic T-cell populations in SLE.

Early HIV infection is associated with reduced proportions of gamma delta T subsets as well as high creatinine and urea levels

Renal dysfunctions are major predictors of co-morbidities and mortality in HIV-infected individuals. Unconventional T cells have been shown to regulate kidney functions. However, there is dearth of information on the effect of HIV-associated nephropathies on γδ and DN T cells. It is also not clear whether γδ T cell perturbations observed during the early stages of HIV infection occur before immune activation. In this study, we investigated the relationship between creatinine and urea on the number of unconventional T cells in HIV-infected individuals at the early and chronic stages of infection. Persons in the chronic stage of infection were divided into treatment naïve and exposed groups. Treatment exposed individuals were further subdivided into groups with undetectable and detectable HIV-1RNA in their blood. Creatinine and urea levels were significantly higher among persons in the early HIV infection compared with the other groups. Proportions of γδ T, γδ + CD8, γδ + CD16 cells were also significantly reduced in the early stage of HIV infection (P < .01). Markers of immune activation, CD4 + HLA-DR and CD8 + HLA-DR, were also significantly reduced during early HIV infection (P < .01). Taken together, our findings suggest that high levels of renal markers as well as reduced proportions of gamma delta T cells are associated with the early stages of HIV infection. This event likely occurs before systemic immune activation reaches peak levels. This study provides evidence for the need for early HIV infection diagnosis and treatment.

Revisiting the Interaction of γδ T-Cells and B-Cells

Right after the discovery of γδ T-cells in 1984, people started asking how γδ T-cells interact with other immune cells such as B-cells. Early reports showed that γδ T-cells are able to help B-cells to produce antibodies and to sustain the production of germinal centers. Interestingly, the presence of γδ T-cells seems to promote the generation of antibodies against "self" and less against challenging pathogens. More recently, these hypotheses were supported using γδ T-cell-deficient mouse strains, in different mouse models of systemic lupus erythematous, and after induction of epithelial cell damage. Together, these studies suggest that the link between γδ T-cells and the production of autoantibodies may be more relevant for the development of autoimmune diseases than generally acknowledged and thus targeting γδ T-cells could represent a new therapeutic strategy. In this review, we focus on what is known about the communication between γδ T-cells and B-cells, and we discuss the importance of this interaction in the context of autoimmunity.

γδ T cells shape memory-phenotype αβ T cell populations in non-immunized mice

Size and composition of γδ T cell populations change dramatically with tissue location, during development, and in disease. Given the functional differentiation of γδ T cell subsets, such shifts might alter the impact of γδ T cells on the immune system. To test this concept, and to determine if γδ T cells can affect other immune cells prior to an immune response, we examined non-immunized mice derived from strains with different genetically induced deficiencies in γδ T cells, for secondary changes in their immune system. We previously saw extensive changes in pre-immune antibodies and B cell populations. Here, we report effects on αβ T cells. Similarly to the B cells, αβ T cells evidently experience the influence of γδ T cells at late stages of their pre-immune differentiation, as single-positive heat stable antigen-low thymocytes. Changes in these and in mature αβ T cells were most prominent with memory-phenotype cells, including both CD8+ and CD4+ populations. As previously observed with B cells, most of the effects on αβ T cells were dependent on IL-4. Unexpectedly, IL-4 seemed to be produced mainly by αβ T cells in the non-immunized mice, albeit strongly regulated by γδ T cells. Similarly to our findings with B cells, changes of αβ T cells were less pronounced in mice lacking all γδ T cells than in mice lacking only some, suggesting that the composition of the γδ T cell population determines the nature of the γδ-influence on the other pre-immune lymphocytes.

Activation of Human CD11b+ B1 B-Cells by Trypanosoma cruzi-Derived Proteins Is Associated With Protective Immune Response in Human Chagas Disease

B-cells mediate humoral adaptive immune response via the production of antibodies and cytokines, and by inducing T-cell activation. These functions can be attributed to distinct B-cell subpopulations. Infection with Trypanosoma cruzi, the causative agent of Chagas disease, induces a polyclonal B-cell activation and lytic antibody production, critical for controlling parasitemia. Individuals within the chronic phase of Chagas disease may remain in an asymptomatic form (indeterminate), or develop severe cardiomyopathy (cardiac form) that can lead to death. Currently, there is no effective vaccine to prevent Chagas disease, and no treatment to halt the development of the cardiomyopathy once it is installed. The pathology associated with cardiac Chagas disease is a result of an inflammatory reaction. Thus, discovering characteristics of the host's immune response that favor the maintenance of favorable heart function may unveil important immunotherapeutic targets. Given the importance of B cells in antibody production and parasite control, we investigated T. cruzi-derived antigenic fractions responsible for B-cell activation and whether frequencies and functional characteristics of B-cell subpopulations are associated with different clinical outcomes of human Chagas disease. We stimulated cells from indeterminate (I) and cardiac (C) Chagas patients, as well as non-infected individuals (NI), with T. cruzi-derived protein- (PRO), glycolipid- (GCL) and lipid (LIP)-enriched fractions and determined functional characteristics of B-cell subpopulations. Our results showed that the frequency of B-cells was similar amongst groups. PRO, but not GCL nor LIP, led to an increased frequency of B1 B-cells in I, but not C nor NI. Although stimulation with PRO induced higher TNF expression by B1 B-cells from C and I, as compared to NI, it induced expression of IL-10 in cells from I, but not C. Stimulation with PRO induced an increased frequency of the CD11b⁺ B1 B-cell subpopulation, which was associated with better cardiac function. Chagas patients displayed increased IgM production, and activation of gamma-delta T-cells, which have been associated with B1 B-cell function. Our data showed that PRO activates CD11b⁺ B1 B-cells, and that this activation is associated with a beneficial clinical status. These findings may have implications in designing new strategies focusing on B-cell activation to prevent Chagas disease cardiomyopathy.

Deciphering the Contribution of γδ T Cells to Outcomes in Transplantation

γδ T cells are a subpopulation of lymphocytes expressing heterodimeric T-cell receptors composed of γ and δ chains. They are morphologically and functionally heterogeneous, innate yet also adaptive in behavior, and exhibit diverse activities spanning immunosurveillance, immunomodulation, and direct cytotoxicity. The specific responses of γδ T cells to allografts are yet to be fully elucidated with evidence of both detrimental and tolerogenic roles in different settings. Here we present an overview of γδ T-cell literature, consider ways in which their functional heterogeneity contributes to the outcomes after transplantation, and reflect on methods to harness their beneficial properties.

Genetic models reveal origin, persistence and non-redundant functions of IL-17-producing γδ T cells

The authors present a genetic mouse model for conditional depletion of γδ T cells, confirming the fetal origin and persistence of Tγδ17 cells. They show differential phenotypes after acute depletion versus constitutive γδ T cell deficiency in imiquimod-induced psoriasis.

γδ T cells are highly conserved in jawed vertebrates, suggesting an essential role in the immune system. However, γδ T cell–deficient Tcrd^−/− mice display surprisingly mild phenotypes. We hypothesized that the lack of γδ T cells in constitutive Tcrd^−/− mice is functionally compensated by other lymphocytes taking over genuine γδ T cell functions. To test this, we generated a knock-in model for diphtheria toxin–mediated conditional γδ T cell depletion. In contrast to IFN-γ–producing γδ T cells, IL-17–producing γδ T cells (Tγδ17 cells) recovered inefficiently after depletion, and their niches were filled by expanding Th17 cells and ILC3s. Complementary genetic fate mapping further demonstrated that Tγδ17 cells are long-lived and persisting lymphocytes. Investigating the function of γδ T cells, conditional depletion but not constitutive deficiency protected from imiquimod-induced psoriasis. Together, we clarify that fetal thymus-derived Tγδ17 cells are nonredundant local effector cells in IL-17–driven skin pathology.

γδ T cells modulate humoral immunity against Plasmodium berghei infection

It is unclear whether γδ T cells are involved in humoral immunity against Plasmodium infection. Here, we show that B-cell-immunodeficient mice and γδ T-cell-deficient mice were incapable of protecting against Plasmodium berghei XAT parasites. γδ T-cell-deficient mice developed reduced levels of antigen-specific antibodies during the late phase of infection. The numbers of follicular helper T cells and germinal centre B cells in γδ T-cell-deficient mice were lower than in wild-type mice during the late phase of infection. Expression profiling of humoral immunity-related cytokines in γδ T cells showed that interleukin-21 (IL-21) and interferon-γ (IFN-γ) are increased during the early stage of infection. Furthermore, blockade of IL-21 and IFN-γ signalling during the early stage of infection led to reduction in follicular helper T cells and germinal centre B cells. γδ T-cell production of IL-21 and IFN-γ is crucial for the development and maintenance of follicular helper T cells and germinal centre B cells during the late phase of infection. Our data suggest that γδ T cells modulate humoral immunity against Plasmodium infection.

γδ T cells control humoral immune response by inducing T follicular helper cell differentiation

γδ T cells have many known functions, including the regulation of antibody responses. However, how γδ T cells control humoral immunity remains elusive. Here we show that complete Freund's adjuvant (CFA), but not alum, immunization induces a subpopulation of CXCR5-expressing γδ T cells in the draining lymph nodes. TCRγδ⁺CXCR5⁺ cells present antigens to, and induce CXCR5 on, CD4 T cells by releasing Wnt ligands to initiate the T follicular helper (Tfh) cell program. Accordingly, TCRδ^-/- mice have impaired germinal center formation, inefficient Tfh cell differentiation, and reduced serum levels of chicken ovalbumin (OVA)-specific antibodies after CFA/OVA immunization. In a mouse model of lupus, TCRδ^-/- mice develop milder glomerulonephritis, consistent with decreased serum levels of lupus-related autoantibodies, when compared with wild type mice. Thus, modulation of the γδ T cell-dependent humoral immune response may provide a novel therapy approach for the treatment of antibody-mediated autoimmunity.

Human Vγ9Vδ2-T Cells Synergize CD4+ T Follicular Helper Cells to Produce Influenza Virus-Specific Antibody

Human Vγ9Vδ2-T cells recognize nonpeptidic antigens and exert effector functions against microorganisms and tumors, but little is known about their roles in humoral immune response against influenza virus infection. Herein, in the coculture of autologous human B cells, dendritic cells and/or naïve CD4 T cells, and Vγ9Vδ2-T cells, we demonstrated that Vγ9Vδ2-T cells could facilitate H9N2 influenza virus-specific IgG and IgM productions in a CD4 T cell-dependent manner. Vγ9Vδ2-T cells promoted the differentiation of CXCR5⁺PD1⁺CD4⁺ T follicular helper (Tfh) cells, CD19⁺IgD⁻CD38⁺⁺ plasma cells (PCs), and drove B cell proliferation as well as immunoglobulin class switching. Interestingly, Vγ9Vδ2-T cells acquired Tfh-associated molecules such as CXCR5, PD1, CD40L, and ICOS during influenza virus stimulation, especially in the presence of CD4 T cells. Moreover, Vγ9Vδ2-T cells promoted CD4 T cells to secrete IL-13 and IL-21, and neutralizing IL-13 and IL-21 significantly reduced the number of CD19⁺IgD⁻CD38⁺⁺ PCs. Using humanized mice, we further demonstrated that Vγ9Vδ2-T cells could synergize CD4 T cells to produce influenza virus-specific antibody. Our findings provide a greater scope for Vγ9Vδ2-T cells in adaptive immunity, especially for the Tfh development and humoral immune responses against influenza virus infection.

Gamma-delta (γδ) T cells: friend or foe in cancer development?

BACKGROUND

γδ T cells are a distinct subgroup of T cells containing T cell receptors (TCRs) γ and TCR δ chains with diverse structural and functional heterogeneity. As a bridge between the innate and adaptive immune systems, γδ T cells participate in various immune responses during cancer progression. Because of their direct/indirect antitumor cytotoxicity and strong cytokine production ability, the use of γδ T cells in cancer immunotherapy has received a lot of attention over the past decade.

MAIN TEXT

Despite the promising potential of γδ T cells, the efficacy of γδ T cell immunotherapy is limited, with an average response ratio of only 21%. In addition, research over the past 2 years has shown that γδ T cells could also promote cancer progression by inhibiting antitumor responses, and enhancing cancer angiogenesis. As a result, γδ T cells have a dual effect and can therefore be considered as being both "friends" and "foes" of cancer. In order to solve the sub-optimal efficiency problem of γδ T cell immunotherapy, we review recent observations regarding the antitumor and protumor activities of major structural and functional subsets of human γδ T cells, describing how these subsets are activated and polarized, and how these events relate to subsequent effects in cancer immunity. A mixture of both antitumor or protumor γδ T cells used in adoptive immunotherapy, coupled with the fact that γδ T cells can be polarized from antitumor cells to protumor cells appear to be the likely reasons for the mild efficacy seen with γδ T cells.

CONCLUSION

The future holds the promise of depleting the specific protumor γδ T cell subgroup before therapy, choosing multi-immunocyte adoptive therapy, modifying the cytokine balance in the cancer microenvironment, and using a combination of γδ T cells adoptive immunotherapy with immune checkpoint inhibitors.

Cocoa Diet and Antibody Immune Response in Preclinical Studies

The ability of cocoa to interact with the immune system in vitro and in vivo has been described. In the latter context, a cocoa-enriched diet in healthy rats was able to modify the immune system's functionality. This fact could be observed in the composition and functionality of lymphoid tissues, such as the thymus, spleen, and lymph nodes. Consequently, immune effector mechanisms, such as antibody synthesis, were modified. A cocoa-enriched diet in young rats was able to attenuate the serum levels of immunoglobulin (Ig) G, IgM, and IgA and also the intestinal IgM and IgA secretion. Moreover, in immunized rats, the intake of cocoa decreased specific IgG1, IgG2a, IgG2c, and IgM concentrations in serum. This immune-regulator potential was then tested in disease models in which antibodies play a pathogenic role. A cocoa-enriched diet was able to partially prevent the synthesis of autoantibodies in a model of autoimmune arthritis in rats and was also able to protect against IgE and T helper 2-related antibody synthesis in two rat models of allergy. Likewise, a cocoa-enriched diet prevented an oral sensitization process in young rats. In this review, we will focus on the influence of cocoa on the acquired branch of the immune function. Therefore, we will focus on how a cocoa diet influences lymphocyte function both in the systemic and intestinal immune system. Likewise, its potential role in preventing some antibody-induced immune diseases is also included. Although further studies must characterize the particular cocoa components responsible for such effects and nutritional studies in humans need to be carried out, cocoa has potential as a nutraceutical agent in some hypersensitivity status.

Occludin Expression in Epidermal γδ T Cells in Response to Epidermal Stress Causes Them To Migrate into Draining Lymph Nodes

Epidermal γδ T cells that reside in the front line of the skin play a pivotal role in stress immune surveillance. However, it is not clear whether these cells are involved in further induction of immune responses after they are activated in dysregulated epidermis. In this study, we found that activated γδ T cells expressed occludin and migrated into draining lymph nodes in an occludin-dependent manner. Epidermal γδ T cells in occludin-deficient mice exhibited impairments in morphology changes and motility, although they expressed activation markers at levels comparable to those in wild-type cells. Occludin deficiency weakened the induction of allergen-induced contact hypersensitivity, primarily as the result of the impaired migration of epidermal γδ T cells. Thus, occludin expression by epidermal γδ T cells upon activation in response to epidermal stress allows them to move, which could be important for augmentation of immune responses via collaboration with other cells.

Role of Mast Cells in Dengue Virus Pathogenesis

Dengue is currently regarded as the most common arthropod-borne viral disease in tropical and subtropical areas, with an estimated 50-100 million infections occurring each year. Nearly all patients experience a self-limiting clinical course; however, the illness ranges from undifferentiated fever to severe hemorrhagic fever with or without shock syndrome complications. There are several immune cells associated with the pathogenesis of dengue virus (DENV) infection and systemic spread, including dendritic cells, macrophages, and mast cells (MCs). MCs are widely recognized for their immune functions and as cellular regulators of vascular integrity in human skin. Furthermore, these cells are able to detect DENV, which results in activation and degranulation of potent vasoactive mediators prestored in the granules. These mediators can act directly on vascular endothelium, increasing permeability and inducing vascular leakage. This review is designed to present an insight into the role of MCs during DENV infection and the dual functions in immune protection and contribution to the most severe forms of dengue.

γδ T Cells and B Cells

γδ T cells constitute the third arm of a tripartite adaptive immune system in jawed vertebrates, besides αβ T cells and B cells. Like the other two lymphocyte-types, they express diverse antigen receptors, capable of specific ligand recognition. Functionally, γδ T cells represent a system of differentiated subsets, sometimes engaged in cross-regulation, which ultimately determines their effect on other components of the immune system, including B cells and antibodies. γδ T cells are capable of providing help to B cells in antibody production. More recently it became clear that γδ T cells influence B cell differentiation during the peripheral stages of B cell development, control levels of circulating immunoglobulin (all subclasses), and affect production of autoantibodies. Because of this relationship between γδ T cells and B cells, the extensive variation of γδ T cells among human individuals might be expected to modulate their humoral responsiveness.

Primary/Congenital Immunodeficiency: 2015 SH/EAHP Workshop Report-Part 5

OBJECTIVES

The 2015 Workshop of the Society for Hematopathology/European Association for Haematopathology aimed to review primary immunodeficiency and related lymphoproliferations.

METHODS

Primary immunodeficiencies were divided into immune dysregulation, DNA repair defects, low immunoglobulins, and combined immunodeficiencies.

RESULTS

Autoimmune lymphoproliferative syndrome (ALPS) is a prototypical immune dysregulation-type immunodeficiency, with defects in T-cell signaling or apoptosis, expansion of T-cell subsets, and predisposition to hemophagocytic lymphohistiocytosis. DNA repair defects directly predispose to malignancy. Low immunoglobulin immunodeficiencies such as common variable immunodeficiency (CVID) have underlying T-cell repertoire abnormalities predisposing to autoimmunity and B-cell lymphoproliferations. The full spectrum of B-cell lymphoproliferative disorders occurs in primary immunodeficiency.

CONCLUSIONS

Lymphoproliferations in primary immunodeficiency mirror those in other immunodeficiency settings, with monomorphic B- and sometimes T lymphoproliferative disorders enriched in DNA repair defects. Distinctive T-cell subset expansions in ALPS, CVID, and related entities can mimic lymphoma, and recognition of double-negative T-cell or cytotoxic T-cell expansions is key to avoid overdiagnosis.

Mucosal and Systemic γδ+ T Cells Associated with Control of Simian Immunodeficiency Virus Infection

γδ T cells act as a first line of defense against invading pathogens. However, despite their abundance in mucosal tissue, little information is available about their functionality in this compartment in the context of HIV/SIV infection. In this study, we evaluated the frequency, phenotype, and functionality of Vδ1 and Vδ2 T cells from blood, rectum, and the female reproductive tract (FRT) of rhesus macaques to determine whether these cells contribute to control of SIV infection. No alteration in the peripheral Vδ1/Vδ2 ratio in SIV-infected macaques was observed. However, CD8⁺ and CD4⁺CD8⁺ Vδ1 T cells were expanded along with upregulation of NKG2D, CD107, and granzyme B, suggesting cytotoxic function. In contrast, Vδ2 T cells showed a reduced ability to produce the inflammatory cytokine IFN-γ. In the FRT of SIV⁺ macaques, Vδ1 and Vδ2 showed comparable levels across vaginal, ectocervical, and endocervical tissues; however, endocervical Vδ2 T cells showed higher inflammatory profiles than the two other regions. No sex difference was seen in the rectal Vδ1/Vδ2 ratio. Several peripheral Vδ1 and/or Vδ2 T cell subpopulations expressing IFN-γ and/or NKG2D were positively correlated with decreased plasma viremia. Notably, Vδ2 CD8⁺ T cells of the endocervix were negatively correlated with chronic viremia. Overall, our results suggest that a robust Vδ1 and Vδ2 T cell response in blood and the FRT of SIV-infected macaques contribute to control of viremia.

Cocoa Diet Prevents Antibody Synthesis and Modifies Lymph Node Composition and Functionality in a Rat Oral Sensitization Model

Cocoa powder, a rich source of polyphenols, has shown immunomodulatory properties in both the intestinal and systemic immune compartments of rats. The aim of the current study was to establish the effect of a cocoa diet in a rat oral sensitization model and also to gain insight into the mesenteric lymph nodes (MLN) activities induced by this diet. To achieve this, three-week-old Lewis rats were fed either a standard diet or a diet with 10% cocoa and were orally sensitized with ovalbumin (OVA) and with cholera toxin as a mucosal adjuvant. Specific antibodies were quantified, and lymphocyte composition, gene expression, and cytokine release were established in MLN. The development of anti-OVA antibodies was almost totally prevented in cocoa-fed rats. In addition, this diet increased the proportion of TCRγδ+ and CD103+CD8+ cells and decreased the proportion of CD62L+CD4+ and CD62L+CD8+ cells in MLN, whereas it upregulated the gene expression of OX40L, CD11c, and IL-1β and downregulated the gene expression of IL-17α. In conclusion, the cocoa diet induced tolerance in an oral sensitization model accompanied by changes in MLN that could contribute to this effect, suggesting its potential implication in the prevention of food allergies.