Murine CD27(-) Vγ6(+) γδ T cells producing IL-17A promote ovarian cancer growth via mobilization of protumor small peritoneal macrophages

Tumor-associated neutrophils suppress pro-tumoral IL-17+ γδ T cells through induction of oxidative stress

Interleukin 17 (IL-17)-producing γδ T cells (γδ17 T cells) have been recently found to promote tumor growth and metastasis formation. How such γδ17 T-cell responses may be regulated in the tumor microenvironment remains, however, largely unknown. Here, we report that tumor-associated neutrophils can display an overt antitumor role by strongly suppressing γδ17 T cells. Tumor-associated neutrophils inhibited the proliferation of murine CD27- Vγ6+ γδ17 T cells via induction of oxidative stress, thereby preventing them from constituting the major source of pro-tumoral IL-17 in the tumor microenvironment. Mechanistically, we found that low expression of the antioxidant glutathione in CD27- γδ17 T cells renders them particularly susceptible to neutrophil-derived reactive oxygen species (ROS). Consistently, superoxide deficiency, or the administration of a glutathione precursor, rescued CD27- Vγ6+ γδ17 T-cell proliferation in vivo. Moreover, human Vδ1+ γδ T cells, which contain most γδ17 T cells found in cancer patients, also displayed low glutathione levels and were potently inhibited by ROS. This work thus identifies an unanticipated, immunosuppressive yet antitumoral, neutrophil/ROS/γδ17 T-cell axis in the tumor microenvironment.

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.

Vγ4+ T Cells: A Novel IL-17-Producing γδ T Subsets during the Early Phase of Chlamydial Airway Infection in Mice

Our previous studies showed that γδ T cells provided immune protection against Chlamydial muridarum (Cm), an obligate intracellular strain of chlamydia trachomatis, lung infection by producing abundant IL-17. In this study, we investigated the proliferation and activation of lung γδ T cell subsets, specifically the IL-17 and IFNγ production by them following Cm lung infection. Our results found that five γδ T cell subsets, Vγ1+ T, Vγ2+ T, Vγ4+ T, Vγ5+ T, and Vγ6+ T, expressed in lungs of naïve mice, while Cm lung infection mainly induced the proliferation and activation of Vγ4+ T cells at day 3 p.i., following Vγ1+ T cells at day 7 p.i. Cytokine detection showed that Cm lung infection induced IFNγ secretion firstly by Vγ4+ T cells at very early stage (day 3) and changed to Vγ1+ T cells at midstage (day 7). Furthermore, Vγ4+ T cell is the main γδ T cell subset that secretes IL-17 at the very early stage of Cm lung infection and Vγ1+ T cell did not secrete IL-17 during the infection. These findings provide in vivo evidence that Vγ4+T cells are the major IL-17 and IFNγ-producing γδ T cell subsets at the early period of Cm lung infection.

Accumulation of IL-17+ Vγ6+ γδ T cells in pregnant mice is not associated with spontaneous abortion

Introduction

Pregnancy is an immune paradox. While the immune system is required for embryo implantation, placental development and progression of gestation, excessive inflammation is associated with pregnancy failure. Similarly, the cytokine IL‐17A plays an important role in defence against extracellular pathogens, but its dysregulation can lead to pathogenic inflammation and tissue damage. Although expression of IL‐17 has been reported during pregnancy, the cellular source of this cytokine and its relevance to gestation are not clear.

Objectives

Here we define the kinetics and cellular source of IL‐17A in the uterus during healthy and abortion‐prone murine pregnancy.

Methods

The CBA/J x DBA/2J abortion‐prone mating was used and compared to CBA/J x BALB/c control mating.

Results

We demonstrate that, irrespective of gestational health, the number of IL‐17‐producing cells peaks during midterm pregnancy and is largely derived from the γδ T‐cell lineage. We identify γδ T, Th17, CD8 T and NKT cells as the cellular source of IL‐17A in pregnant mice. Furthermore, we positively identify the Vγ6⁺ subset of uterine γδ T cells as the main producer of IL‐17A during both healthy pregnancy and abortive pregnancy.

Conclusions

To conclude, the accumulation of uterine IL‐17⁺ innate‐like T cells appears not to adversely impact the developing foetus. Collectively, our results show that IL‐17⁺ γδ T cells are present in the uterus throughout the course of normal gestation and therefore may play an important role in healthy pregnancy.

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.

Dermal Vγ4+T cells enhance the IMQ-induced psoriasis-like skin inflammatidon in re-challenged mice

To investigate the role of dermal Vγ₄⁺γδ T cells in psoriasis-like skin inflammation induced by a re-challenge with imiquimod (IMQ), we compared the development of dermatitis induced by topical application of IMQ in primary challenged mice and re-challenged mice. We also compared the development of dermatitis induced by IMQ between re-challenged control mice and Vγ₄^- depleted re-challenged mice that had been initially subjected to IMQ-induced dermatitis 30 prior. We found that the IMQ-induced dermatitis was exacerbated in the re-challenged group compared with the primary challenged group and the Vγ₄^- depleted re-challenged group. In addition, the Vγ₄⁺γδ T cells increased in number and secreted more IL-17A, γ-IFN and IL-22 in the re-challenged control group compared with the primary challenged group. However, in the Vγ₄^- depleted re-challenged group, the Vγ₄^-γδ T cells increased in number and produced more IL-17A and IL-22 compared with re-challenged control mice. These findings suggest that dermal Vγ₄⁺γδ T cells enhance relapsing psoriasis-like skin inflammation induced by IMQ in C57BL/6 mice by secreting IL-17A and γ-IFN.

The Peritoneal Macrophages in Inflammatory Diseases and Abdominal Cancers

Peritoneal macrophages (PMs) are the major cell type of peritoneal cells that participate in multiple aspects of innate and acquired immunity in the peritoneal cavity. PMs have an ability to release a large amount of proinflammatory and anti-inflammatory cytokines and therefore play a critical role in regulating the differentiation of innate immune cells and inflammatory T cells. Accumulating studies demonstrate that the immunological reactions and inflammatory responses of PMs are strongly related to the pathogenic processes of various inflammatory diseases and abdominal cancers. Consequently, the regulation of PM activation has gradually emerged as a promising target for immunotherapy, and better understanding of the distinctly biological function of PMs in individual diseases is crucial for designing specific and effective therapeutic agents. This review covers the characterization and immunological function of PMs in hosts with inflammatory diseases and abdominal cancers.

HEB is required for the specification of fetal IL-17-producing γδ T cells

IL-17-producing γδ T (γδT17) cells are critical components of the innate immune system. However, the gene networks that control their development are unclear. Here we show that HEB (HeLa E-box binding protein, encoded by Tcf12) is required for the generation of a newly defined subset of fetal-derived CD73⁻ γδT17 cells. HEB is required in immature CD24⁺CD73⁻ γδ T cells for the expression of Sox4, Sox13, and Rorc, and these genes are repressed by acute expression of the HEB antagonist Id3. HEB-deficiency also affects mature CD73⁺ γδ T cells, which are defective in RORγt expression and IL-17 production. Additionally, the fetal TCRγ chain repertoire is altered, and peripheral Vγ4 γδ T cells are mostly restricted to the IFNγ-producing phenotype in HEB-deficient mice. Therefore, our work identifies HEB-dependent pathways for the development of CD73⁺ and CD73⁻ γδT17 cells, and provides mechanistic evidence for control of the γδT17 gene network by HEB.

The γδ T cell pool includes abundant IL-17-producing cells that protect mucosal surfaces, but the signals that control γδ T cell specification are unclear. Here the authors identify a role for the transcription factor HEB, and antagonistic activity of Id3, in the development of these cells.

γδTCR recruits the Syk/PI3K axis to drive proinflammatory differentiation program

γδT cells produce inflammatory cytokines and have been implicated in the pathogenesis of cancer, infectious diseases, and autoimmunity. The T cell receptor (TCR) signal transduction that specifically regulates the development of IL-17-producing γδT (γδT17) cells largely remains unclear. Here, we showed that the receptor proximal tyrosine kinase Syk is essential for γδTCR signal transduction and development of γδT17 in the mouse thymus. Zap70, another tyrosine kinase essential for the development of αβT cells, failed to functionally substitute for Syk in the development of γδT17. Syk induced the activation of the PI3K/Akt pathway upon γδTCR stimulation. Mice deficient in PI3K signaling exhibited a complete loss of γδT17, without impaired development of IFN-γ-producing γδT cells. Moreover, γδT17-dependent skin inflammation was ameliorated in mice deficient in RhoH, an adaptor known to recruit Syk. Thus, we deciphered lineage-specific TCR signaling and identified the Syk/PI3K pathway as a critical determinant of proinflammatory γδT cell differentiation.

Tumor-associated macrophages (TAMs) depend on ZEB1 for their cancer-promoting roles

Accumulation of tumor-associated macrophages (TAMs) associates with malignant progression in cancer. However, the mechanisms that drive the pro-tumor functions of TAMs are not fully understood. ZEB1 is best known for driving an epithelial-to-mesenchymal transition (EMT) in cancer cells to promote tumor progression. However, a role for ZEB1 in macrophages and TAMs has not been studied. Here we describe that TAMs require ZEB1 for their tumor-promoting and chemotherapy resistance functions in a mouse model of ovarian cancer. Only TAMs that expressed full levels of Zeb1 accelerated tumor growth. Mechanistically, ZEB1 expression in TAMs induced their polarization toward an F4/80low pro-tumor phenotype, including direct activation of Ccr2 In turn, expression of ZEB1 by TAMs induced Ccl2, Cd74, and a mesenchymal/stem-like phenotype in cancer cells. In human ovarian carcinomas, TAM infiltration and CCR2 expression correlated with ZEB1 in tumor cells, where along with CCL2 and CD74 determined poorer prognosis. Importantly, ZEB1 in TAMs was a factor of poorer survival in human ovarian carcinomas. These data establish ZEB1 as a key factor in the tumor microenvironment and for maintaining TAMs' tumor-promoting functions.

Type I IFN Receptor Signaling Controls IL7-Dependent Accumulation and Activity of Protumoral IL17A-Producing γδT Cells in Breast Cancer

The protumoral activity of γδT17 cells has recently emerged in a wide variety of solid malignancies, including breast cancer. These cells exert their detrimental functions by promoting tumor growth, angiogenesis, and subsequent metastasis development. However, the intratumoral factors that regulate the biology of γδT17cells within the tumor microenvironment are less well understood. Here, using two experimental models of breast cancer, we reinforced the concept that tumor-infiltrating γδT17 cells are endowed with protumoral functions, which promote tumor progression and metastasis development. More importantly, we demonstrated a critical role for type I IFN signaling in controlling the preferential accumulation in the tumor bed of a peculiar subset of γδT17 cells displaying a CD27^- CD3^bright phenotype (previously associated with the invariant Vγ6Vδ1⁺ TCR). Interestingly, this effect was indirect and partially relied on the IFNAR1-dependent control of IL7 secretion, a factor that triggers proliferation and activating functions of deleterious γδT17 cells. Our work therefore identifies a key role of the type I IFN/IL7 axis in the regulation of intratumoral γδT17-cell functions and in the development of primary breast tumor growth and metastasis.Significance: Tumor-derived IL7 can represent a therapeutic target to prevent accumulation of immune cells endowed with potent protumoral activities. Cancer Res; 78(1); 195-204. ©2017 AACR.

Human papillomavirus oncoproteins induce a reorganization of epithelial-associated γδ T cells promoting tumor formation

It has been shown that γδ T cells protect against the formation of squamous cell carcinoma (SCC) in several models. However, the role of γδ T cells in human papillomavirus (HPV)-associated uterine cervical SCC, the third-leading cause of death by cancer in women, is unknown. Here, we investigated the impact of γδ T cells in a transgenic mouse model of carcinogenesis induced by HPV16 oncoproteins. Surprisingly, γδ T cells promoted the development of HPV16 oncoprotein-induced lesions. HPV16 oncoproteins induced a decrease in epidermal Skint1 expression and the associated antitumor Vγ5+ γδ T cells, which were replaced by γδ T-cell subsets (mainly Vγ6+ γδlowCCR2+CCR6-) actively producing IL-17A. Consistent with a proangiogenic role, γδ T cells promoted the formation of blood vessels in the dermis underlying the HPV-induced lesions. In human cervical biopsies, IL-17A+ γδ T cells could only be observed at the cancer stage (SCC), where HPV oncoproteins are highly expressed, supporting the clinical relevance of our observations in mice. Overall, our results suggest that HPV16 oncoproteins induce a reorganization of the local epithelial-associated γδ T-cell subpopulations, thereby promoting angiogenesis and cancer development.

IL-17 Production from T Helper 17, Mucosal-Associated Invariant T, and γδ Cells in Tuberculosis Infection and Disease

IL-17-producing cells have been shown to be important in the early stages of Mycobacterium tuberculosis (Mtb) infection in animal models. However, there are very little data on the role of IL-17 in human studies of tuberculosis (TB). We recruited TB patients and their highly exposed contacts who were further categorized based on results from an IFN-γ-release assay (IGRA): (1) IGRA positive (IGRA+) at recruitment (latently TB infected), (2) IGRA negative (IGRA-) at recruitment and 6 months [non-converters (NC)], and (3) IGRA- at recruitment and IGRA+ at 6 months (converters). Whole blood was stimulated with mycobacterial antigens and analyzed using T helper (Th) 17 multiplex cytokine assays. Th17, Vγ9Vδ2+, and CD161++Vα7.2+ mucosal-associated invariant T (MAIT) cells were analyzed by flow cytometry. The majority of IL-17 was produced by CD26+CD4+ Th17 cells (median 71%) followed by γδ T cells (6.4%) and MAIT cells (5.8%). TB patients had a significantly lower proportion of Th17 cells and CD4+CD161+Vα7.2+ cells producing both IL-17 and IFN-γ compared to LTBI subjects. IGRA NC had significantly lower levels of CD26-CD4+ and CD8+ MAIT cells producing IL-17 compared to IGRA C but had significantly higher levels of IL-17A, IL-17F, IL-21, and IL-23 in ESAT-6/CFP-10-stimulated supernatants compared to IGRA C. These data provide new insights into the role of IL-17 and IL-17-producing cells at three key stages of the Mtb infection spectrum.

IL-21 promotes the development of a CD73-positive Vγ9Vδ2 T cell regulatory population

Vγ9Vδ2 T cells contribute to the immune response against many tumor types through their direct cytotoxic activity and capacity to regulate the biological functions of other immune cells, such as dendritic cells and IFN-γ-producing CD8⁺ T cells. However, their presence in the tumor microenvironment has also been associated with poor prognosis in breast, colon and pancreatic cancers. Additionally, recent studies demonstrated that cytokines can confer some plasticity to Vγ9Vδ2 T cells and promote their differentiation into cells with regulatory functions. Here, we demonstrated that activation of Vγ9Vδ2 T cells isolated from healthy donors and cultured in the presence of IL-21 favors the emergence of a subpopulation of Vγ9Vδ2 T cells that express the ectonucleotidase CD73 and inhibits T cell proliferation in a CD73/adenosine-dependent manner. This subpopulation produces IL-10 and IL-8 and displays lower effector functions and cytotoxic activity than CD73-negative Vγ9Vδ2 T cells. We also showed, in a syngeneic mouse tumor model, the existence of a tumor-infiltrating γδ T cell subpopulation that produces IL-10 and strongly expresses CD73. Moreover, maturation, IL-12 production and induction of antigen-specific T cell proliferation are impaired in DC co-cultured with IL-21-amplified Vγ9Vδ2 T cells. Altogether, these data indicate that IL-21 promotes Vγ9Vδ2 T cell regulatory functions by favoring the development of an immunosuppressive CD73⁺ subpopulation. Thus, when present in the tumor microenvironment, IL-21 might negatively impact γδ T cell anti-tumor functions.

Immune Cell Population in Ovarian Tumor Microenvironment

Ovarian cancer, the third most common with highest mortality rates gynecological malignancy among women in China, is characterized by a unique tumor immune microenvironment. Immune-cell population infiltrated into the tumor tissue among patients with ovarian cancer are associated positively or negatively with antitumor activity. The imbalance between immune activation and immune suppression can result in oncogenesis and cancer progression. Therefore, intense investigation of the immunologic mechanism of ovarian cancer is urgently needed, and a comprehensive understanding of the network in which immune cells interact with the microenvironment, tumor cells and each other will greatly promote the development of more effective immunotherapies for ovarian cancer. In this review, we will focus on the main immune-cell population in ovarian tumor microenvironment, discuss their role in tumor progression and try to give the readers a new perspective in finding more promising therapeutic targets for cancers.

γδ T Cells: Unexpected Regulators of Cancer Development and Progression

Accumulating evidence suggests a role for gamma delta (γδ) T cells as unexpected drivers of tumor development and progression. These protumoral γδ T cells are abundant in the tumor microenvironment in both mouse and human. They promote tumor progression by: (i) inducing an immunosuppressive tumor microenvironment and angiogenesis via cytokine production; (ii) functioning as regulatory T (Treg)/T helper 2 (Th2)-like cells; (iii) interfering with dendritic cell (DC) effector function; and (iv) inhibiting antitumor adaptive T cell immunity via the programmed death-1 (PD-1)-programmed death ligand-1 (PD-L1) pathway. Understanding how these cells are regulated and what their specific role in cancer is will provide insight for the development of approaches that specifically target these cells and can thereby improve the efficacy of cancer immunotherapies.

IL-17-producing γδ T cells switch migratory patterns between resting and activated states

Interleukin 17-producing γδ T (γδT17) cells have unconventional trafficking characteristics, residing in mucocutaneous tissues but also homing into inflamed tissues via circulation. Despite being fundamental to γδT17-driven early protective immunity and exacerbation of autoimmunity and cancer, migratory cues controlling γδT17 cell positioning in barrier tissues and recruitment to inflammatory sites are still unclear. Here we show that γδT17 cells constitutively express chemokine receptors CCR6 and CCR2. While CCR6 recruits resting γδT17 cells to the dermis, CCR2 drives rapid γδT17 cell recruitment to inflamed tissues during autoimmunity, cancer and infection. Downregulation of CCR6 by IRF4 and BATF upon γδT17 activation is required for optimal recruitment of γδT17 cells to inflamed tissue by preventing their sequestration into uninflamed dermis. These findings establish a lymphocyte trafficking model whereby a hierarchy of homing signals is prioritized by dynamic receptor expression to drive both tissue surveillance and rapid recruitment of γδT17 cells to inflammatory lesions.

IL-17-producing γδ T (γδT17) cells position in barrier tissues but also home to inflammatory sites. How this trafficking is regulated is unclear. Here the authors show that the dynamic expression of chemokine receptors CCR2 and CCR6 differentiates γδT17 cell trafficking patterns at homeostasis and in inflammatory scenarios.

Increased frequencies of circulating and tumor-resident Vδ1+ T cells in patients with diffuse large B-cell lymphoma

Gamma-delta (γδ) T cells contribute to the innate immune response against cancer. In samples of 20 patients upon DLBCL diagnosis, we found that Vδ1⁺ T cells were the major γδ T cell subset in tumors and PBMCs of patients, while Vδ2 T cells were preponderant in PBMCs of healthy subjects. Interestingly, the germinal center (GC) subtype was associated with an increase in Vδ1⁺ T cells in tumors, whereas the non-GC subtype was associated with a lower frequency of γδ T cells. While circulating Vδ1⁺ T cells of patients or HSs mostly exhibited a naïve phenotype, the majority of tumor Vδ1⁺ T cells showed a central memory phenotype. Resident or circulating γδ T cells from patients were not functionally impaired since they produced high levels of IFN-γ. Collectively, our findings are in favor of γδ T cell activation in tumors and open new perspectives for their modulation in DLBCL immunotherapy.

Characterization of γδ T cells in patients with non-small cell lung cancer

Systemic immune defects that are associated with disease progression exist in a variety of malignancies. γδ T cells are innate-like lymphocytes that do not require self-major histocompatibility complex-restricted priming. Ex vivo-expanded circulating γδ T cells exhibit promising antitumor activity and are a potential candidate for the treatment of various malignancies, including non-small cell lung cancer (NSCLC). In the present study, flow cytometry was used as a method to study the phenotypes and characteristics of γδ T cells. A lower frequency of circulating γδ T cells was observed in NSCLC patients than in healthy controls. In advanced NSCLC patients, γδ T cells were also detected in the pleural effusion, but the frequency of γδ T cells here was significantly lower than in the peripheral blood. Vδ1⁺and Vδ1^-Vδ2^- T cells represented the most enriched subsets in the pleural effusion. Moreover, the present study demonstrated that Vδ1⁺ T cells are a type of γδ T cells characterized by a cluster of differentiation (CD)3^dim T-cell receptor (TCR)γδ^bright phenotype, whereas Vδ2⁺ T cells represent a CD3^brightTCRγδ^dim phenotype, according to the fluorescence intensity of CD3 and γδTCR using flow cytometry. Finally, the present study reported a decrease in the expression of CD27 and CD28 molecules on the surface of circulating γδ T cells in NSCLC. The present data suggest the existence of a dysregulated repertoire of γδ T cells in NSCLC, which exhibit impaired activation and a reformed cytokine-releasing profile. Although the ex vivo expansion of γδ T cells may be a prospective therapeutic strategy in NSCLC patients, it remains necessary to clarify which subsets (Vδ1 or Vδ2) should be expanded and the sources from which γδ T cells should be generated.

In vivo photolabeling of tumor-infiltrating cells reveals highly regulated egress of T-cell subsets from tumors

Immune therapy is rapidly gaining prominence in the clinic as a major weapon against cancer. Whereas much attention has been focused on the infiltration of tumors by immune cells, the subsequent fate of these infiltrates remains largely unexplored. We therefore established a photoconversion-based model that allowed us to label tumor-infiltrating immune cells and follow their migration. Using this system, we identified a population of tumor-experienced cells that emigrate from primary tumors to draining lymph nodes via afferent lymphatic vessels. Although the majority of tumor-infiltrating cells were myeloid, T cells made up the largest population of tumor-egressing leukocytes. Strikingly, the subset composition of tumor-egressing T cells was greatly skewed compared with those that had infiltrated the tumor and those resident in the draining lymph node. Some T-cell subsets such as CD8⁺ T cells emigrated more readily; others including CD4^-CD8^- T cells were preferentially retained, suggesting that specific mechanisms guide immune cell egress from tumors. Furthermore, tumor-egressing T cells were more activated and displayed enhanced effector function in comparison with their lymph node counterparts. Finally, we demonstrated that tumor-infiltrating T cells migrate to distant secondary tumors and draining lymph nodes, highlighting a mechanism whereby tumor-experienced effector T cells may mediate antitumor immunity at metastatic sites. Thus, our results provide insights into migration and function of tumor-infiltrating immune cells and the role of these cells in tumor immunity outside of primary tumor deposits.

Microbiota-activated CD103+ DCs stemming from microbiota adaptation specifically drive γδT17 proliferation and activation

BACKGROUND

IL-17-producing γδT cells (γδT17) promote autoinflammatory diseases and cancers. Yet, γδT17 peripheral regulation has not been thoroughly explored especially in the context of microbiota-host interaction. The potent antigen-presenting CD103⁺ dendritic cell (DC) is a key immune player in close contact with both γδT17 cells and microbiota. This study presents a novel cellular network among microbiota, CD103⁺ DCs, and γδT17 cells.

METHODS

Immunophenotyping of IL-17r^-/- mice and IL-17r^-/- IRF8^-/- mice were performed by ex vivo immunostaining and flow cytometric analysis. We observed striking microbiome differences in the oral cavity and gut of IL-17r^-/- mice by sequencing 16S rRNA gene (v1-v3 region) and analyzed using QIIME 1.9.0 software platform. Principal coordinate analysis of unweighted UniFrac distance matrix showed differential clustering for WT and IL-17r^-/- mice.

RESULTS

We found drastic homeostatic expansion of γδT17 in all major tissues, most prominently in cervical lymph nodes (cLNs) with monoclonal expansion of Vγ6 γδT17 in IL-17r^-/- mice. Ki-67 staining and in vitro CFSE assays showed cellular proliferation due to cell-to-cell contact stimulation with microbiota-activated CD103⁺ DCs. A newly developed double knockout mice model for IL-17r and CD103⁺ DCs (IL-17r^-/-IRF8^-/-) showed a specific reduction in Vγ6 γδT17. Vγ6 γδT17 expansion is inhibited in germ-free mice and antibiotic-treated specific pathogen-free (SPF) mice. Microbiota transfer using cohousing of IL-17r^-/- mice with wildtype mice induces γδT17 expansion in the wildtype mice with increased activated CD103⁺ DCs in cLNs. However, microbiota transfer using fecal transplant through oral gavage to bypass the oral cavity showed no difference in colon or systemic γδT17 expansion.

CONCLUSIONS

These findings reveal for the first time that γδT17 cells are regulated by microbiota dysbiosis through cell-to-cell contact with activated CD103⁺ DCs leading to drastic systemic, monoclonal expansion. Microbiota dysbiosis, as indicated by drastic bacterial population changes at the phylum and genus levels especially in the oral cavity, was discovered in mice lacking IL-17r. This network could be very important in regulating both microbiota and immune players. This critical regulatory pathway for γδT17 could play a major role in IL-17-driven inflammatory diseases and needs further investigation to determine specific targets for future therapeutic intervention.

Squamous Cell Tumors Recruit γδ T Cells Producing either IL17 or IFNγ Depending on the Tumor Stage

The identification of reciprocal interactions between tumor-infiltrating immune cells and the microenviroment may help us understand mechanisms of tumor growth inhibition or progression. We have assessed the frequencies of tumor-infiltrating and circulating γδ T cells and regulatory T cells (Treg) from 47 patients with squamous cell carcinoma (SCC), to determine if they correlated with progression or survival. Vδ1 T cells infiltrated SSC tissue to a greater extent than normal skin, but SCC patients and healthy subjects had similar amounts circulating. However, Vδ2 T cells were present at higher frequencies in circulation than in the tissue of either cancer patients or healthy donors. Tregs were decreased in the peripheral blood of SCC patients, but were significantly increased in the tumor compartment of these patients. Tumor-infiltrating γδ T cells preferentially showed an effector memory phenotype and made either IL17 or IFNγ depending on the tumor stage, whereas circulating γδ T cells of SCC patients preferentially made IFNγ. Different cell types in the tumor microenvironment produced chemokines that could recruit circulating γδ T cells to the tumor site and other cytokines that could reprogram γδ T cells to produce IL17. These findings suggest the possibility that γδ T cells in SCC are recruited from the periphery and their features are then affected by the tumor microenvironment. Elevated frequencies of infiltrating Vδ2 T cells and Tregs differently correlated with early and advanced tumor stages, respectively. Our results provide insights into the functions of tumor-infiltrating γδ T cells and define potential tools for tumor immunotherapy. Cancer Immunol Res; 5(5); 397-407. ©2017 AACR.

Human γδT-cell subsets and their involvement in tumor immunity

γδT cells are a conserved population of innate lymphocytes with diverse structural and functional heterogeneity that participate in various immune responses during tumor progression. γδT cells perform potent immunosurveillance by exerting direct cytotoxicity, strong cytokine production and indirect antitumor immune responses. However, certain γδT-cell subsets also contribute to tumor progression by facilitating cancer-related inflammation and immunosuppression. Here, we review recent observations regarding the antitumor and protumor roles of major structural and functional subsets of human γδT cells, describing how these subsets are activated and polarized, and how these events relate to subsequent function in tumor immunity. These studies provide insights into the manipulation of γδT-cell function to facilitate more targeted approaches for tumor therapy.

Aire Inhibits the Generation of a Perinatal Population of Interleukin-17A-Producing γδ T Cells to Promote Immunologic Tolerance

Aire's primary mechanism of action is to regulate transcription of a battery of genes in medullary thymic epithelial cells (mTECs) and, consequently, negative selection of effector T cells and positive selection of regulatory T cells. We found that Aire-deficient mice had expanded thymic and peripheral populations of perinatally generated IL-17A+Vγ6+Vδ1+ T cells, considered to be "early responders" to tissue stress and drivers of inflammatory reactions. Aire-dependent control of Il7 expression in mTECs regulated the size of thymic IL-17A+Vγ6+Vδ1+ compartments. In mice lacking Aire and γδ T cells, certain tissues typically targeted in the "Aire-less" disease, notably the retina, were only minimally infiltrated. IL-17A+Vγ6+Vδ1+ cells were present in the retina of wild-type mice and expanded very early in Aire-deficient mice. A putatively parallel population of IL-17A+Vγ9+Vδ2+ T cells was increased in humans lacking Aire. Thus, Aire exerts multi-faceted autoimmune control that extends to a population of innate-like T cells.

Characterization of γδ regulatory T cells from peripheral blood in patients with multiple myeloma

γδ regulatory T cells are able to inhibit the activation and function of T cells involved in antigen-specific immune responses. This study aimed to investigate the potential role of γδ regulatory T cells in inhibiting anti-tumor immune responses in patients diagnosed as multiple myeloma (MM). We measured the levels of γδ T cells, the distribution and clonally amplified TCR Vγ and VδT cells in peripheral blood of healthy donors, patients recently diagnosed with MM, and MM patients in remission cohorts. In addition, we evaluated the ability of γδ regulatory T cells to inhibit the proliferation of CD4+CD25- T cells and detected the expression of immunoregulatory-associated molecules. We found that the levels of γδ regulatory T cells from the peripheral blood in patients of MM were significantly higher than those in healthy donors. Comparison of γδT regulatory cells function in MM and healthy donors showed similarly inhibitory effects on the proliferation of T cells. Additionally, TLR8 expression level increased significantly in MM patients compared to healthy donors, while the expression levels of Foxp3, CD25, CTLA4, GITR, GATA3 and Tbet in MM patients and healthy donors showed no significant difference. Taken together, our study reveals the potential role of γδ regulatory T cells in inhibiting anti-tumor immune responses in MM patients.

Memory γδ T Cells-Newly Appreciated Protagonists in Infection and Immunity

Despite the potential for diversity in their T cell receptor, γδ T cells are primarily considered to be innate immune cells. Recently, memory-like γδ T cell responses have been identified in murine models of infection and autoimmunity. Similar memory responses have also been described in human and non-human primate γδ T cells. It has thus become clear that subpopulations of γδ T cells can develop long-lasting memory akin to conventional αβ T cells, with protective and pathogenic consequences. Hence, a re-evaluation of their true capabilities and role in infection and immunity is required. This review discusses recent reports of memory-type responses attributed to γδ T cells and assesses this underappreciated facet of these enigmatic cells.

Beneficial Effects of Sodium Phenylbutyrate Administration during Infection with Salmonella enterica Serovar Typhimurium

Sodium phenylbutyrate (PBA) is a derivative of the short-chain fatty acid butyrate and is approved for treatment of urea cycle disorders and progressive familial intrahepatic cholestasis type 2. Previously known functions include histone deacetylase inhibitor, endoplasmic reticulum stress inhibitor, ammonia sink, and chemical chaperone. Here, we show that PBA has a previously undiscovered protective role in host mucosal defense during infection. Administration of PBA to Taconic mice resulted in the increase of intestinal Lactobacillales and segmented filamentous bacteria (SFB), as well as an increase of interleukin 17 (IL-17) production by intestinal cells. This effect was not observed in Jackson Laboratory mice, which are not colonized with SFB. Because previous studies showed that IL-17 plays a protective role during infection with mucosal pathogens, we hypothesized that Taconic mice treated with PBA would be more resistant to infection with Salmonella enterica serovar Typhimurium (S Typhimurium). By using the streptomycin-treated mouse model, we found that Taconic mice treated with PBA exhibited significantly lower S Typhimurium intestinal colonization and dissemination to the reticuloendothelial system, as well as lower levels of inflammation. The lower levels of S Typhimurium gut colonization and intestinal inflammation were not observed in Jackson Laboratory mice. Although PBA had no direct effect on bacterial replication, its administration reduced S Typhimurium epithelial cell invasion and lowered the induction of the proinflammatory cytokine IL-23 in macrophage-like cells. These effects likely contributed to the better outcome of infection in PBA-treated mice. Overall, our results suggest that PBA induces changes in the microbiota and in the mucosal immune response that can be beneficial to the host during infection with S Typhimurium and possibly other enteric pathogens.

Cytokine Regulation of Metastasis and Tumorigenicity

The human body combats infection and promotes wound healing through the remarkable process of inflammation. Inflammation is characterized by the recruitment of stromal cell activity including recruitment of immune cells and induction of angiogenesis. These cellular processes are regulated by a class of soluble molecules called cytokines. Based on function, cell target, and structure, cytokines are subdivided into several classes including: interleukins, chemokines, and lymphokines. While cytokines regulate normal physiological processes, chronic deregulation of cytokine expression and activity contributes to cancer in many ways. Gene polymorphisms of all types of cytokines are associated with risk of disease development. Deregulation RNA and protein expression of interleukins, chemokines, and lymphokines have been detected in many solid tumors and hematopoetic malignancies, correlating with poor patient prognosis. The current body of literature suggests that in some tumor types, interleukins and chemokines work against the human body by signaling to cancer cells and remodeling the local microenvironment to support the growth, survival, and invasion of primary tumors and enhance metastatic colonization. Some lymphokines are downregulated to suppress tumor progression by enhancing cytotoxic T cell activity and inhibiting tumor cell survival. In this review, we will describe the structure/function of several cytokine families and review our current understanding on the roles and mechanisms of cytokines in tumor progression. In addition, we will also discuss strategies for exploiting the expression and activity of cytokines in therapeutic intervention.

The majority of murine γδ T cells at the maternal-fetal interface in pregnancy produce IL-17

Compared with lymphoid tissues, the immune cell compartment at mucosal sites is enriched with T cells bearing the γδ T-cell receptor (TCR). The female reproductive tract, along with the placenta and uterine decidua during pregnancy, are populated by γδ T cells predominantly expressing the invariant Vγ6(+)Vδ1(+) receptor. Surprisingly little is understood about the function of these cells. We found that the majority of γδ T cells in the non-pregnant uterus, pregnant uterus, decidua and placenta of mice express the transcription factor RORγt and produce interleukin-17 (IL-17). In contrast, IFNγ-producing γδ T cells were markedly reduced in gestational tissues compared with uterine-draining lymph nodes and spleen. Both uterine-resident invariant Vγ6(+) and Vγ4(+) γδ T cells which are more typically found in lymphoid tissues and circulating blood, were found to express IL-17. Vγ4(+) γδ T cells were particularly enriched in the placenta, suggesting a pregnancy-specific recruitment or expansion of these cells. A small increase in IL-17-producing γδ T cells was observed in allogeneic compared with syngeneic pregnancy, suggesting a contribution to regulating the maternal response to paternally-derived alloantigens. However, their high proportions also in non-pregnant uteri and gestational tissues of syngeneic pregnancy imply a role in the prevention of intrauterine infection or quality control of fetal development. These data suggest the need for a more rigorous evaluation of the role of IL-17 in sustaining normal pregnancy, particularly as emerging data points to a pathogenic role for IL-17 in pre-eclampsia, pre-term birth, miscarriage and maternal immune activation-induced behavioral abnormalities in offspring.

IL-17A-producing T cells are associated with the progression of lung adenocarcinoma

Accumulating evidence has shown that T cells are crucial in shaping the tumor microenvironment and regulating tumor development. However, the roles of IL-17A-producing T cells (IL-17A⁺CD4⁺ Th17, IL-17A⁺CD8⁺ Tc17 and IL-17A⁺ γδT17 cells) and related cytokines in the progression of lung cancer (LC) remain uncertain. Here, we found that the frequencies of both Th17 and γδT17 cells in the peripheral blood of patients with lung adenocarcinoma (LA) were higher than those in healthy controls (HCs), whereas the frequency of Tc17 cells in the patients with LA was decreased. In addition, the frequencies of circulating Th17 and γδT17 cells, but not Tc17 cells, were positively associated with tumor invasion and metastasis. Furthermore, the major source of IL-17A production was Th17 cells, followed by Tc17 and γδT17 cells, in peripheral blood from patients with LA and HCs; but the percentages of Th17 and γδT17 cells in total intracellular IL-17A⁺ cells obtained from the patients with LC were higher than those from HCs. Moreover, the protein and corresponding mRNA levels of IL-17A, IL-23, IL-1β, and TGF-β1 were much higher in the patients with LA than those in HCs, and the levels of IL-17A in patients were positively correlated with numbers of both Th17 and γδT17 cells, but not Tc17 cells. Finally, the frequencies of circulating Th17 and γδT17 cells, along with the levels of IL-17A, IL-23, IL-1β, and TGF-β1 were decreased in the patients with LA after tumor resection, whereas the frequency of circulating Tc17 cells was inversely increased in these patients. Our findings indicate that Th17, Tc17, γδT17 cells, and IL-17A-associated cytokines contribute to the development of LA and thus represent promising targets for therapeutic strategies.

Effector γδ T Cell Differentiation Relies on Master but Not Auxiliary Th Cell Transcription Factors

γδ T lymphocytes are programmed into distinct IFN-γ-producing CD27(+) (γδ27(+)) and IL-17-producing CD27(-) (γδ27(-)) subsets that play key roles in protective or pathogenic immune responses. Although the signature cytokines are shared with their αβ Th1 (for γδ27(+)) and Th17 (for γδ27(-)) cell counterparts, we dissect in this study similarities and differences in the transcriptional requirements of murine effector γδ27(+), γδ27(-)CCR6(-), and γδ27(-)CCR6(+) γδ T cell subsets and αβ T cells. We found they share dependence on the master transcription factors T-bet and RORγt for IFN-γ and IL-17 production, respectively. However, Eomes is fully dispensable for IFN-γ production by γδ T cells. Furthermore, the Th17 cell auxiliary transcription factors RORα and BATF are not required for IL-17 production by γδ27(-) cell subsets. We also show that γδ27(-) (but not γδ27(+)) cells become polyfunctional upon IL-1β plus IL-23 stimulation, cosecreting IL-17A, IL-17F, IL-22, GM-CSF, and IFN-γ. Collectively, our in vitro and in vivo data firmly establish the molecular segregation between γδ27(+) and γδ27(-) T cell subsets and provide novel insight on the nonoverlapping transcriptional networks that control the differentiation of effector γδ versus αβ T cell subsets.

Seminal plasma induces inflammation in the uterus through the γδ T/IL-17 pathway

After insemination, a large number of leukocytes migrate into the uterus, which is accompanied by intense inflammation. However, the details of how seminal plasma interacts with the uterus are still not very clear. Here, we present that neutrophils migrate and accumulate around the uterine epithelium following insemination, which is accompanied by an increase in interleukin (IL) 17A levels. Additionally, we find that γδ T cells are the major source of IL-17A, and the seminal plasma could induce the γδ T cells to secret IL-17A. Blocking IL-17A could reduce the number of neutrophils in the uterus and prevent them from migrating to the epithelium by decreasing the chemokines CXCL1, CXCL2 and CXCL5. Blocking IL-17A did not affect the Th1/Th2 balance but actually diminished the inflammation in the uterus by reducing the expression of IL-1β and TNF-α. In summary, we found a new mechanism by which seminal plasma could influence the inflammation in the uterus through the γδ T/IL-17 pathway to regulate the expression of various chemokines and cytokines.

Regulatory and effector functions of gamma-delta (γδ) T cells and their therapeutic potential in adoptive cellular therapy for cancer

γδ T cells are an important innate immune component of the tumor microenvironment and are known to affect the immune response in a wide variety of tumors. Unlike αβ T cells, γδ T cells are capable of spontaneous secretion of IL-17A and IFN-γ without undergoing clonal expansion. Although γδ T cells do not require self-MHC-restricted priming, they can distinguish "foreign" or transformed cells from healthy self-cells by using activating and inhibitory killer Ig-like receptors. γδ T cells were used in several clinical trials to treat cancer patient due to their MHC-unrestricted cytotoxicity, ability to distinguish transformed cells from normal cells, the capacity to secrete inflammatory cytokines and also their ability to enhance the generation of antigen-specific CD8(+) and CD4(+) T cell response. In this review, we discuss the effector and regulatory function of γδ T cells in the tumor microenvironment with special emphasis on the potential for their use in adoptive cellular immunotherapy.

TCR signal strength controls thymic differentiation of discrete proinflammatory γδ T cell subsets

The murine thymus produces discrete γδ T cell subsets making either interferon-γ (IFN--γ) or interleukin 17 (IL-17), but the role of the TCR in this developmental process remains controversial. Here we show that mice haploinsufficient for both Cd3g and Cd3d (CD3DH, for CD3 double haploinsufficient) have reduced TCR expression and signaling strength selectively on γδ T cells. CD3DH mice had normal numbers and phenotype of αβ thymocyte subsets but impaired differentiation of fetal Vγ6⁺ (but not Vγ4⁺) IL-17-producing γδ T cells and a marked depletion of IFN-γ-producing CD122⁺ NK1.1⁺ γδ T cells throughout ontogeny. Adult CD3DH mice showed reduced peripheral IFN-γ⁺ γδ T cells and were resistant to experimental cerebral malaria. Thus, TCR signal strength within specific thymic developmental windows is a major determinant of the generation of proinflammatory γδ T cell subsets and their impact on pathophysiology.

The cells that mediate innate immune memory and their functional significance in inflammatory and infectious diseases

Immunological memory mediated by antigen-specific T and B cells is the foundation of adaptive immunity and is fundamental to the heightened and rapid protective immune response induced by vaccination or following re-infection with the same pathogen. While the innate immune system has classically been considered to be non-specific and devoid of memory, it now appears that it can be trained following exposure to microbes or their products and that this may confer a form of memory on innate immune cells. The evidence for immunological memory outside of T and B cells has been best established for natural killer (NK) cells, where it has been known for decades that NK cells have heighten responses following immunological re-challenge. Furthermore, recent studies have demonstrated that monocyte/macrophages, and probably dendritic cells, can be re-programmed through epigenetic modification, following exposure to pathogens or their products, resulting in heighted responses following a second stimulation. Unlike antigen-specific memory of the adaptive immune system, the second stimulation does not have to be with the same pathogen or antigen. Indirect evidence for this comes from reports on the non-specific beneficial effect of certain live vaccines, such as Bacillus Calmette Guerin (BCG) against unrelated childhood infectious diseases. It also appears that certain pathogen or pathogen-derived molecules can prime immune cells, especially macrophages, to secrete more anti-inflammatory and less pro-inflammatory cyokines, thus opening up the possibility of exploiting innate immune training as a new therapeutic approach for inflammatory diseases.

Redundant Innate and Adaptive Sources of IL17 Production Drive Colon Tumorigenesis

IL17-producing Th17 cells, generated through a STAT3-dependent mechanism, have been shown to promote carcinogenesis in many systems, including microbe-driven colon cancer. Additional sources of IL17, such as γδ T cells, become available under inflammatory conditions, but their contributions to cancer development are unclear. In this study, we modeled Th17-driven colon tumorigenesis by colonizing Min(Ap) (c+/-) mice with the human gut bacterium, enterotoxigenic Bacteroides fragilis (ETBF), to investigate the link between inflammation and colorectal cancer. We found that ablating Th17 cells by knocking out Stat3 in CD4(+) T cells delayed tumorigenesis, but failed to suppress the eventual formation of colonic tumors. However, IL17 blockade significantly attenuated tumor formation, indicating a critical requirement for IL17 in tumorigenesis, but from a source other than Th17 cells. Notably, genetic ablation of γδ T cells in ETBF-colonized Th17-deficient Min mice prevented the late emergence of colonic tumors. Taken together, these findings support a redundant role for adaptive Th17 cell- and innate γδT17 cell-derived IL17 in bacteria-induced colon carcinogenesis, stressing the importance of therapeutically targeting the cytokine itself rather than its cellular sources. Cancer Res; 76(8); 2115-24. ©2016 AACR.

γδT Cells and Related Diseases

Discovered 30 years ago, γδT cells remain an enigmatic T-cell subset. Although they account for a small portion of the total human circulating T-cell pool, their associations with other immune cells and their potential regulatory roles in related diseases have been explored but still require further investigation. γδT cells which are MHC-unrestricted innate-like lymphocytes with more unique antigen receptors than αβT cells and B cells are considered to bridge innate and adaptive immunity. They have APC functions and initiate adaptive immunity. Due to their distribution in specific tissues, secretion of Th1-, Th2-, and Th17-type cytokines, and other characteristics, they are involved in a variety of physiology and pathology processes. They are barometers in HIV infection. However, different γδT cell subsets play opposing roles in HBV infections, autoimmune diseases, and several types of tumors. Moreover, decidual γδT cells have protective roles during pregnancies by synthesizing several cytokines. This emerging evidence provides an improved understanding of the immune mechanism of infection, autoimmunity, cancer, and other related disorders and better insights regarding the potential roles of γδT cells in immunological therapeutic strategies.

Leukocytes recruited by tumor-derived HMGB1 sustain peritoneal carcinomatosis

The factors that determine whether disseminated transformed cells in vivo yield neoplastic lesions have only been partially identified. We established an ad hoc model of peritoneal carcinomatosis by injecting colon carcinoma cells in mice. Tumor cells recruit inflammatory leukocytes, mostly macrophages, and generate neoplastic peritoneal lesions. Phagocyte depletion via clodronate treatment reduces neoplastic growth. Colon carcinoma cells release a prototypic damage-associated molecular pattern (DAMP)/alarmin, High Mobility Group Box1 (HMGB1), which attracts leukocytes. Exogenous HMGB1 accelerates leukocyte recruitment, macrophage infiltration, tumor growth and vascularization. Lentiviral-based HMGB1 knockdown or pharmacological interference with its extracellular impair macrophage recruitment and tumor growth. Our findings provide a preclinical proof of principle that strategies based on preventing HMGB1-driven recruitment of leukocytes could be used for treating peritoneal carcinomatosis.

γδ T cells in cancer

With the promise of T cell-based therapy for cancer finally becoming reality, this Review focuses on the less-studied γδ T cell lineage and its diverse responses to tumours. γδ T cells have well-established protective roles in cancer, largely on the basis of their potent cytotoxicity and interferon-γ production. Besides this, recent studies have revealed a series of tumour-promoting functions that are linked to interleukin-17-producing γδ T cells. Here, we integrate the current knowledge from both human and mouse studies to highlight the potential of γδ T cell modulation to improve cancer immunotherapy.

Immunity and immune modulation in Trypanosoma cruzi infection

Chagas disease is caused by the protozoan Trypanosoma cruzi. The parasite reaches the secondary lymphoid organs, the heart, skeletal muscles, neurons in the intestine and esophagus among other tissues. The disease is characterized by mega syndromes, which may affect the esophagus, the colon and the heart, in about 30% of infected people. The clinical manifestations associated with T. cruzi infection during the chronic phase of the disease are dependent on complex interactions between the parasite and the host tissues, particularly the lymphoid system that may either result in a balanced relationship with no disease or in an unbalanced relationship that follows an inflammatory response to parasite antigens and associated tissues in some of the host organs and/or by an autoimmune response to host antigens. This review discusses the findings that support the notion of an integrated immune response, considering the innate and adaptive arms of the immune system in the control of parasite numbers and also the mechanisms proposed to regulate the immune response in order to tolerate the remaining parasite load, during the chronic phase of infection. This knowledge is fundamental to the understanding of the disease progression and is essential for the development of novel therapies and vaccine strategies.

IL-17A Contributes to the Pathogenesis of Endometriosis by Triggering Proinflammatory Cytokines and Angiogenic Growth Factors

Endometriosis is a chronic, inflammatory disease characterized by the growth of endometrial tissue in aberrant locations outside the uterus. Neoangiogenesis or establishment of new blood supply is one of the fundamental requirements of endometriotic lesion survival in the peritoneal cavity. IL-17A is emerging as a potent angiogenic and proinflammatory cytokine involved in the pathophysiology of several chronic inflammatory diseases such as rheumatoid arthritis and psoriasis. However, sparse information is available in the context of endometriosis. In this study, we demonstrate the potential importance of IL-17A in the pathogenesis and pathophysiology of endometriosis. The data show a differential expression of IL-17A in human ectopic endometriotic lesions and matched eutopic endometrium from women with endometriosis. Importantly, surgical removal of lesions resulted in significantly reduced plasma IL-17A concentrations. Immunohistochemistry revealed localization of IL-17A primarily in the stroma of matched ectopic and eutopic tissue samples. In vitro stimulation of endometrial epithelial carcinoma cells, Ishikawa cells, and HUVECs with IL-17A revealed significant increase in angiogenic (vascular endothelial growth factor and IL-8), proinflammatory (IL-6 and IL-1β), and chemotactic cytokines (G-CSF, CXCL12, CXCL1, and CX3CL1). Furthermore, IL-17A promoted tubulogenesis of HUVECs plated on Matrigel in a dose-dependent manner. Thus, we provide the first evidence, to our knowledge, that endometriotic lesions produce IL-17A and that the removal of the lesion via laparoscopic surgery leads to the significant reduction in the systemic levels of IL-17A. Taken together, our data show a likely important role of IL-17A in promoting angiogenesis and proinflammatory environment in the peritoneal cavity for the establishment and maintenance of endometriosis lesions.

Murine IL-17+ Vγ4 T lymphocytes accumulate in the lungs and play a protective role during severe sepsis

Background

Lung inflammation is a major consequence of the systemic inflammatory response caused by severe sepsis. Increased migration of γδ T lymphocytes into the lungs has been previously demonstrated during experimental sepsis; however, the involvement of the γδ T cell subtype Vγ4 has not been previously described.

Methods

Severe sepsis was induced by cecal ligation and puncture (CLP; 9 punctures, 21G needle) in male C57BL/6 mice. γδ and Vγ4 T lymphocyte depletion was performed by 3A10 and UC3-10A6 mAb i.p. administration, respectively. Lung infiltrating T lymphocytes, IL-17 production and mortality rate were evaluated.

Results

Severe sepsis induced by CLP in C57BL/6 mice led to an intense lung inflammatory response, marked by the accumulation of γδ T lymphocytes (comprising the Vγ4 subtype). γδ T lymphocytes present in the lungs of CLP mice were likely to be originated from peripheral lymphoid organs and migrated towards CCL2, CCL3 and CCL5, which were highly produced in response to CLP-induced sepsis. Increased expression of CD25 by Vγ4 T lymphocytes was observed in spleen earlier than that by αβ T cells, suggesting the early activation of Vγ4 T cells. The Vγ4 T lymphocyte subset predominated among the IL-17⁺ cell populations present in the lungs of CLP mice (unlike Vγ1 and αβ T lymphocytes) and was strongly biased toward IL-17 rather than toward IFN-γ production. Accordingly, the in vivo administration of anti-Vγ4 mAb abrogated CLP-induced IL-17 production in mouse lungs. Furthermore, anti-Vγ4 mAb treatment accelerated mortality rate in severe septic mice, demonstrating that Vγ4 T lymphocyte play a beneficial role in host defense.

Conclusions

Overall, our findings provide evidence that early-activated Vγ4 T lymphocytes are the main responsible cells for IL-17 production in inflamed lungs during the course of sepsis and delay mortality of septic mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0098-8) contains supplementary material, which is available to authorized users.