A genome-wide analysis identifies a notch-RBP-Jκ-IL-7Rα axis that controls IL-17-producing γδ T cell homeostasis in mice

A RORE-dependent Intronic Enhancer in the IL-7 Receptor-α Locus Controls Glucose Metabolism via Vγ4+ γδT17 Cells

The IL-7R regulates the homeostasis, activation, and distribution of T cells in peripheral tissues. Although several transcriptional enhancers that regulate IL-7Rα expression in αβ T cells have been identified, enhancers active in γδ T cells remain unknown. In this article, we discovered an evolutionarily conserved noncoding sequence (CNS) in intron 2 of the IL-7Rα-chain (IL-7Rα) locus and named this region CNS9. CNS9 contained a conserved retinoic acid receptor-related orphan receptor (ROR)-responsive element (RORE) and exerted RORγt-dependent enhancer activity in vitro. Mice harboring point mutations in the RORE in CNS9 (CNS9-RORmut) showed reduced IL-7Rα expression in IL-17-producing Vγ4+ γδ T cells. In addition, the cell number and IL-17A production of Vγ4+ γδ T cells were reduced in the adipose tissue of CNS9-RORmut mice. Consistent with the reduction in IL-17A, CNS9-RORmut mice exhibited decreased IL-33 expression in the adipose tissue, resulting in fewer regulatory T cells and glucose intolerance. The CNS9-ROR motif was partially responsible for IL-7Rα expression in RORγt+ regulatory T cells, whereas IL-7Rα expression was unaffected in RORγt-expressing Vγ2+ γδ T cells, Th17 cells, type 3 innate lymphoid cells, and invariant NKT cells. Our results indicate that CNS9 is a RORΕ-dependent, Vγ4+ γδ T cell-specific IL-7Rα enhancer that plays a critical role in adipose tissue homeostasis via regulatory T cells, suggesting that the evolutionarily conserved RORΕ in IL-7Rα intron 2 may influence the incidence of type 2 diabetes.

The role of γδ T17 cells in cardiovascular disease

Due to the ability of γδ T cells to bridge adaptive and innate immunity, γδ T cells can respond to a variety of molecular cues and acquire the ability to induce a variety of cytokines such as IL-17 family, IFN-γ, IL-4, and IL-10. IL-17⁺ γδ T cells (γδ T17 cells) populations have recently received considerable interest as they are the major early source of IL-17A in many immune response models. However, the exact mechanism of γδ T17 cells is still poorly understood, especially in the context of cardiovascular disease (CVD). CVD is the leading cause of death in the world, and it tends to be younger. Here, we offer a review of the cardiovascular inflammatory and immune functions of γδ T17 cells in order to understand their role in CVD, which may be the key to developing new clinical applications.

Interleukin-7 receptor signaling is crucial for enhancer-dependent TCRδ germline transcription mediated through STAT5 recruitment

γδ T cells play important roles in immune responses by rapidly producing large quantities of cytokines. Recently, γδ T cells have been found to be involved in tissue homeostatic regulation, playing roles in thermogenesis, bone regeneration and synaptic plasticity. Nonetheless, the mechanisms involved in γδ T-cell development, especially the regulation of TCRδ gene transcription, have not yet been clarified. Previous studies have established that NOTCH1 signaling plays an important role in the Tcrg and Tcrd germline transcriptional regulation induced by enhancer activation, which is mediated through the recruitment of RUNX1 and MYB. In addition, interleukin-7 signaling has been shown to be required for Tcrg germline transcription, VγJγ rearrangement and γδ T-lymphocyte generation as well as for promoting T-cell survival. In this study, we discovered that interleukin-7 is required for the activation of enhancer-dependent Tcrd germline transcription during thymocyte development. These results indicate that the activation of both Tcrg and Tcrd enhancers during γδ T-cell development in the thymus depends on the same NOTCH1- and interleukin-7-mediated signaling pathways. Understanding the regulation of the Tcrd enhancer during thymocyte development might lead to a better understanding of the enhancer-dependent mechanisms involved in the genomic instability and chromosomal translocations that cause leukemia.

Endothelial Notch signaling directly regulates the small GTPase RND1 to facilitate Notch suppression of endothelial migration

To control sprouting angiogenesis, endothelial Notch signaling suppresses tip cell formation, migration, and proliferation while promoting barrier formation. Each of these responses may be regulated by distinct Notch-regulated effectors. Notch activity is highly dynamic in sprouting endothelial cells, while constitutive Notch signaling drives homeostatic endothelial polarization, indicating the need for both rapid and constitutive Notch targets. In contrast to previous screens that focus on genes regulated by constitutively active Notch, we characterized the dynamic response to Notch. We examined transcriptional changes from 1.5 to 6 h after Notch signal activation via ligand-specific or EGTA induction in cultured primary human endothelial cells and neonatal mouse brain. In each combination of endothelial type and Notch manipulation, transcriptomic analysis identified distinct but overlapping sets of rapidly regulated genes and revealed many novel Notch target genes. Among the novel Notch-regulated signaling pathways identified were effectors in GPCR signaling, notably, the constitutively active GTPase RND1. In endothelial cells, RND1 was shown to be a novel direct Notch transcriptional target and required for Notch control of sprouting angiogenesis, endothelial migration, and Ras activity. We conclude that RND1 is directly regulated by endothelial Notch signaling in a rapid fashion in order to suppress endothelial migration.

Ontogenic timing, T cell receptor signal strength, and Notch signaling direct γδ T cell functional differentiation in vivo

γδ T cells form an integral arm of the immune system and are critical during protective and destructive immunity. However, how γδ T cells are functionally programmed in vivo remains unclear. Here, we employ RBPJ-inducible and KN6-transgenic mice to assess the roles of ontogenic timing, T cell receptor (TCR) signal strength, and Notch signaling. We find skewing of Vγ1+ cells toward the PLZF+Lin28b+ lineage at the fetal stage. Generation of interleukin-17 (IL-17)-producing γδ T cells is favored during, although not exclusive to, the fetal stage. Surprisingly, Notch signaling is dispensable for peripheral γδ T cell IL-17 production. Strong TCR signals, together with Notch, promote IL-4 differentiation. Conversely, less strong TCR signals promote Notch-independent IL-17 differentiation. Single-cell transcriptomic analysis reveals differential programming instilled by TCR signal strength and Notch for specific subsets. Thus, our results precisely define the roles of ontogenic timing, TCR signal strength, and Notch signaling in γδ T cell functional programming in vivo.

Alternative splicing and gene co-expression network-based analysis of dizygotic twins with autism-spectrum disorder and their parents

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with high heritability, however, understanding the complexity of the underlying genetic basis has proven to be a challenging task. We hypothesized that dissecting the aberrations in alternative splicing (AS) and their effects on expression networks might provide insight. Therefore, we performed AS and co-expression analyses of total RNA isolated from Peripheral Blood Mononuclear Cells (PBMCs) of two pairs of dizygotic (DZ) twins with non-syndromic autism and their parents. We identified 183 differential AS events in 146 genes, seven of them being Simons Foundation Autism Research Initiative (SFARI) Category 1-3 genes, three of which had previously been reported to be alternatively spliced in ASD post-mortem brains. Gene co-expression analysis identified 7 modules with 513 genes, 5 of which were SFARI Category 1 or Category 2 genes. Among differentially AS genes within the modules, ZNF322 and NR4A1 could be potentially interesting targets for further investigations.

Fatty acid-binding protein 3 controls contact hypersensitivity through regulating skin dermal Vγ4+ γ/δ T cell in a murine model

BACKGROUND

Fatty acid-binding protein 3 (FABP3) is a cytosolic carrier protein of polyunsaturated fatty acids (PUFAs) and regulates cellular metabolism. However, the physiological functions of FABP3 in immune cells and how FABP3 regulates inflammatory responses remain unclear.

METHODS

Contact hypersensitivity (CHS) induced by 2,4-dinitrofluorobenzene (DNFB) and fluorescein isothiocyanate was applied to the skin wild-type and Fabp3-/- mice. Skin inflammation was assessed using FACS, histological, and qPCR analyses. The development of γ/δ T cells was evaluated by a co-culture system with OP9/Dll1 cells in the presence or absence of transgene of FABP3.

RESULTS

Fabp3-deficient mice exhibit a more severe phenotype of contact hypersensitivity (CHS) accompanied by infiltration of IL-17-producing Vγ4+ γ/δ T cells that critically control skin inflammation. In Fabp3-/- mice, we found a larger proportion of Vγ4+ γ/δ T cells in the skin, even though the percentage of total γ/δ T cells did not change at steady state. Similarly, juvenile Fabp3-/- mice also contained a higher amount of Vγ4+ γ/δ T cells not only in the skin but in the thymus when compared with wild-type mice. Furthermore, thymic double-negative (DN) cells expressed FABP3, and FABP3 negatively regulates the development of Vγ4+ γ/δ T cells in the thymus.

CONCLUSIONS

These findings suggest that FABP3 functions as a negative regulator of skin inflammation through limiting pathogenic Vγ4+ γ/δ T-cell generation in the thymus.

Gut γδ T cells as guardians, disruptors, and instigators of cancer

Colorectal cancer is the third most common cancer worldwide with nearly 2 million cases per year. Immune cells and inflammation are a critical component of colorectal cancer progression, and they are used as reliable prognostic indicators of patient outcome. With the growing appreciation for immunology in colorectal cancer, interest is growing on the role γδ T cells have to play, as they represent one of the most prominent immune cell populations in gut tissue. This group of cells consists of both resident populations-γδ intraepithelial lymphocytes (γδ IELs)-and transient populations that each has unique functions. The homeostatic role of these γδ T cell subsets is to maintain barrier integrity and prevent microorganisms from breaching the mucosal layer, which is accomplished through crosstalk with enterocytes and other immune cells. Recent years have seen a surge in discoveries regarding the regulation of γδ IELs in the intestine and the colon with particular new insights into the butyrophilin family. In this review, we discuss the development, specialities, and functions of γδ T cell subsets during cancer progression. We discuss how these cells may be used to predict patient outcome, as well as how to exploit their behavior for cancer immunotherapy.

γδ T Cell Update: Adaptate Orchestrators of Immune Surveillance

As interest in γδ T cells grows rapidly, what key points are emerging, and where is caution warranted? γδ T cells fulfill critical functions, as reflected in associations with vaccine responsiveness and cancer survival in humans and ever more phenotypes of γδ T cell-deficient mice, including basic physiological deficiencies. Such phenotypes reflect activities of distinct γδ T cell subsets, whose origins offer interesting insights into lymphocyte development but whose variable evolutionary conservation can obfuscate translation of knowledge from mice to humans. By contrast, an emerging and conserved feature of γδ T cells is their "adaptate" biology: an integration of adaptive clonally-restricted specificities, innate tissue-sensing, and unconventional recall responses that collectively strengthen host resistance to myriad challenges. Central to adaptate biology are butyrophilins and other γδ cell regulators, the study of which should greatly enhance our understanding of tissue immunogenicity and immunosurveillance and guide intensifying clinical interest in γδ cells and other unconventional lymphocytes.

Regulation of γδ T Cell Effector Diversification in the Thymus

γδ T cells are the first T cell lineage to develop in the thymus and take up residence in a wide variety of tissues where they can provide fast, innate-like sources of effector cytokines for barrier defense. In contrast to conventional αβ T cells that egress the thymus as naïve cells, γδ T cells can be programmed for effector function during development in the thymus. Understanding the molecular mechanisms that determine γδ T cell effector fate is of great interest due to the wide-spread tissue distribution of γδ T cells and their roles in pathogen clearance, immunosurveillance, cancer, and autoimmune diseases. In this review, we will integrate the current understanding of the role of the T cell receptor, environmental signals, and transcription factor networks in controlling mouse innate-like γδ T cell effector commitment.

Developmental origins of murine γδ T-cell subsets

Murine γδ T cells display diverse responses to pathogens and tumours through early provision of pro-inflammatory cytokines such as interleukin-17A (IL-17) and interferon-γ (IFN-γ). Although it is now clear that acquisition of these cytokine-secreting effector fates is to a great extent developmentally pre-programmed in the thymus, the stages through which γδ progenitor cells transition, and the underlying mechanistic processes that govern these commitment events, are still largely unclear. Here, we review recent progress in the field, with particular consideration of how TCR-γδ signalling impacts on developmental programmes initiated before TCR-γδ expression.

The oncogene KRAS promotes cancer cell dissemination by stabilizing spheroid formation via the MEK pathway

Background

Peritoneal dissemination is a critical prognostic factor in ovarian cancer. Although stabilized spheroid formation promotes cancer cell peritoneal dissemination in ovarian cancer, the associated oncogenes are unknown. In this study, we assessed the role of the KRAS oncogene in ovarian cancer cell dissemination, focusing on the stability of cells in spheroid condition, as well as the modulation of intracellular signaling following spheroid transformation.

Methods

We used ID8, a murine ovarian cancer cell line, and ID8-KRAS, an oncogenic KRAS (G12 V)-transduced ID8 cell line in this study. Spheroid-forming (3D) culture and cell proliferation assays were performed to evaluate the growth characteristics of these cells. cDNA microarray analysis was performed to identify genes involved in KRAS-associated signal transduction in floating condition. A MEK inhibitor was used to evaluate the effect on cancer peritoneal dissemination.

Results

Cell viability and proliferation in monolayer (2D) cultures did not differ between ID8 and ID8-KRAS cells. However, the proportions of viable and proliferating ID8-KRAS cells in 3D culture were approximately 2-fold and 5-fold higher than that of ID8, respectively. Spheroid-formation was increased in ID8-KRAS cells. Analysis of peritoneal floating cells obtained from mice intra-peritoneally injected with cancer cells revealed that the proportion of proliferating cancer cells was approximately 2-fold higher with ID8-KRAS than with ID8 cells. Comprehensive cDNA microarray analysis revealed that pathways related to cell proliferation, and cell cycle checkpoint and regulation were upregulated specifically in ID8-KRAS cells in 3D culture, and that some genes partially regulated by the MEK-ERK pathway were upregulated only in ID8-KRAS cells in 3D culture. Furthermore, a MEK inhibitor, trametinib, suppressed spheroid formation in 3D culture of ID8-KRAS cells, although trametinib did not affect 2D-culture cell proliferation. Finally, we demonstrated that trametinib dramatically improved the prognosis for mice with ID8-KRAS tumors in an in vivo mouse model.

Conclusions

Our data indicated that KRAS promoted ovarian cancer dissemination by stabilizing spheroid formation and that the MEK pathway is important for stabilized spheroid formation. Disruption of spheroid formation by a MEK inhibitor could be a therapeutic target for cancer peritoneal dissemination.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4922-4) contains supplementary material, which is available to authorized users.

Integration of T-cell receptor, Notch and cytokine signals programs mouse γδ T-cell effector differentiation

γδ T‐cells perform a wide range of tissue‐ and disease‐specific functions that are dependent on the effector cytokines produced by these cells. However, the aggregate signals required for the development of interferon‐γ (IFNγ) and interleukin‐17 (IL‐17) producing γδ T‐cells remain unknown. Here, we define the cues involved in the functional programming of γδ T‐cells, by examining the roles of T‐cell receptor (TCR), Notch, and cytokine‐receptor signaling. KN6 γδTCR‐transduced Rag2^−/− T‐cell progenitors were cultured on stromal cells variably expressing TCR and Notch ligands, supplemented with different cytokines. We found that distinct combinations of these signals are required to program IFNγ versus IL‐17 producing γδ T‐cell subsets, with Notch and weak TCR ligands optimally enabling development of γδ17 cells in the presence of IL‐1β, IL‐21 and IL‐23. Notably, these cytokines were also shown to be required for the intrathymic development of γδ17 cells. Together, this work provides a framework of how signals downstream of TCR, Notch and cytokine receptors integrate to program the effector function of IFNγ and IL‐17 producing γδ T‐cell subsets.

The role of the common gamma-chain family cytokines in γδ T cell-based anti-cancer immunotherapy

Cytokines of the common gamma-chain receptor family, comprising interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15 and IL-21, are vital with respect to organizing and sustaining healthy immune cell functions. Supporting the anti-cancer immune response, these cytokines inspire great interest for their use as vaccine adjuvants and cancer immunotherapies. It is against this background that gamma delta (γδ) T cells, as special-force soldiers and natural contributors of the tumor immunosurveillance, also received a lot of attention the last decade. As γδ T cell-based cancer trials are coming of age, this present review focusses on the effects of the different cytokines of the common gamma-chain receptor family on γδ T cells with respect to boosting γδ T cells as a therapeutic target in cancer immunotherapy. This review also gathers data that IL-15 in particular exhibits key features for augmenting the anti-tumor activity of effector killer γδ T cells whilst overcoming the myriad of immune escape mechanisms used by cancer cells.

Thymic Program Directing the Functional Development of γδT17 Cells

γδT cells comprise a unique T cell sublineage endowed with a wide functional repertoire, which allow them to play important—sometimes opposite—roles in many immune responses associated with infection, cancer, and inflammatory processes. This is largely dependent on the existence of pre-programmed discrete functional subsets that differentiate within the thymus at specific temporal windows of life. Since they represent a major early source of interleukin-17A in many models of immune responses, the γδT17 cell population has recently gained considerable interest. Thus, a better dissection of the developmental program of this effector γδT subset appears critical in understanding their associated immune functions. Several recent reports have provided new exciting insights into the developmental mechanisms that control γδT cell lineage commitment and differentiation. Here, we review the importance of thymic cues and intrinsic factors that shape the developmental program of γδT17 cells. We also discuss the potential future areas of research in γδT17 cell development especially in regards to the recently provided data from deep RNA sequencing technology. Pursuing our understanding into this complex mechanism will undoubtedly provide important clues into the biology of this particular T cell sublineage.

IL-21 inhibits IL-17A-producing γδ T-cell response after infection with Bacillus Calmette-Guérin via induction of apoptosis

Innate γδ T cells expressing Vγ6 produce IL-17A at an early stage following infection with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). In this study, we used IL-21 receptor knockout (IL-21R KO) mice and IL-21-producing recombinant BCG mice (rBCG-Ag85B-IL-21) to examine the role of IL-21 in the regulation of IL-17A-producing innate γδ T-cell response following BCG infection. IL-17A-producing Vγ6⁺ γδ T cells increased in the peritoneal cavity of IL-21R KO mice more than in wild type mice after BCG infection. In contrast, the number of IL-17A-producing Vγ6⁺ γδ T cells was significantly lower after inoculation with rBCG-Ag85B-IL-21 compared with control rBCG-Ag85B. Notably, exogenous IL-21 selectively induced apoptosis of IL-17A-producing Vγ6⁺ γδ T cells via Bim. Thus, these results suggest that IL-21 acts as a potent inhibitor of a IL-17A-producing γδ T-cell subset during BCG infection.

Two Types of Interleukin 17A-Producing γδ T Cells in Protection Against Pulmonary Infection With Klebsiella pneumoniae

BACKGROUND

 Klebsiella pneumoniae frequently causes life-threatening infection in children. Interleukin 17A (IL-17A) is known to be involved in protection against K. pneumoniae infection through activation of neutrophils.

METHODS AND RESULTS

 We found that IL-17A-producing γδ T cells existed more frequently in younger mice on examination of IL-17A-producing lymphocytes in the lung of naive mice at various ages. We hence compared the protective role of IL-17A-producing γδ T cells against pulmonary K. pneumoniae infection in young (3 weeks old) and adult (8-12 weeks old) mice. IL-17A-deficient mice were susceptible to K. pneumonia regardless of age. Cγ-, Vγ4/6-, or Vδ1-deficient mice were susceptible to K. pneumonia at young age, while interleukin 23p19 (IL-23p19)-deficient mice were susceptible at adult age. IL-17A-producing Vγ1^-Vγ4^- γδ T cells expressing canonical Vγ6/Vδ1 genes were dominant over IL-17A-producing Vγ4⁺ γδ T cells in the lungs of young mice after infection. The IL-17A-producing Vγ1^-Vγ4^- γδ T cells expressed an activation marker, CD69, and proliferated in an IL-23-independent manner, while the IL-17A-producing Vγ4⁺ γδ T cells expressing IL-23 receptor but no CD69 proliferated in IL-23-dependent manner.

CONCLUSIONS

 These results suggest that 2 types of IL-17A-producing γδ T cells are activated for host defense against K. pneumoniae infection by IL-23-dependent or independent mechanism.

Recombinant Mycobacterium bovis bacillus Calmette-Guérin expressing Ag85B-IL-7 fusion protein enhances IL-17A-producing innate γδ T cells

Interleukin 7 (IL-7) has an important function in the development and maintenance of IL-17A+ γδ T cells. We here constructed a recombinant Mycobacterium bovis bacillus Calmette-Guérin expressing antigen 85B (Ag85B)-IL-7 fusion protein (rBCG-Ag85B-IL-7). The Ag85B-IL-7 fusion protein and IL-7 were detected in the bacterial lysate of rBCG-Ag85B-IL-7. rBCG-Ag85B-IL-7 was the same in number as control rBCG expressing Ag85B (rBCG-Ag85B) in the lung at the early stage after intravenous inoculation, whereas the numbers of IL-17A+ γδ T cells and Ag-specific Th1 cells were significantly higher in the lungs of mice inoculated with rBCG-Ag85B-IL-7 than those inoculated with rBCG-Ag85B. The Ag-specific Th1 cell response was impaired in mice lacking IL-17A+ γδ T cells after inoculation with rBCG-Ag85B-IL-7. Thus, rBCG-Ag85B-IL-7 increases the pool size of IL-17A+ γδ T cells, which subsequently augment the Th1 response to mycobacterial infection.