EGR2 Deletion Suppresses Anti-DsDNA Autoantibody and IL-17 Production in Autoimmune-Prone B6/lpr Mice: A Differential Immune Regulatory Role of EGR2 in B6/lpr Versus Normal B6 Mice.

Previous studies have reported that deletion of the transcription factor, early growth response protein 2 (EGR2), in normal C57BL/6 (B6) resulted in the development of lupus-like autoimmune disease. However, increased EGR2 expression has been noted in human and murine lupus, which challenges the notion of the autoimmune suppressive role of EGR2 in B6 mice. In this study, we derived both conditional EGR2-/-B6/lpr and EGR2-/-B6 mice to elucidate the immune and autoimmune regulatory roles of EGR2 in autoinflammation (B6/lpr) versus physiologically normal (B6) conditions. We found that conditional EGR2 deletion increased spleen weight, enhanced T cell activation and IFNγ production, and promoted germinal center B cells and LAG3+ regulatory T cells development in both B6/lpr and B6 mice. Nevertheless, EGR2 deletion also showed strikingly differential effects in these two strains on T lymphocyte subsets profile, Foxp3+ Tregs and plasma cell differentiation, anti-dsDNA autoantibodies and immunoglobulins production, and on the induction of IL-17 in in vitro activated splenocytes. Specifically, EGR2 deletion in B6/lpr mice significantly decreased serum levels of anti-dsDNA autoantibodies, total IgG, IgM, IgG1, and IgG2a with reduced plasma cells differentiation. Furthermore, EGR2 deletion in B6/lpr mice had no obvious effect on IgG immunocomplex deposition, medium caliber vessel, and glomeruli inflammation but increased complement C3 immunocomplex deposition and large caliber vessel inflammation in the kidneys. Importantly, we demonstrated that EGR2 deletion in B6/lpr mice significantly reduced pathogenic CD4-CD8-CD3+B220+ double negative T cells, which correlated with the reduced anti-dsDNA autoantibodies in serum and decreased IL-17 production in splenocytes of EGR2-/-B6/lpr mice. Together, our data strongly suggest that the role of EGR2 is complex. The immunoregulatory role of EGR2 varies at normal or autoinflammation conditions and should not be generalized in differential experimental settings.

Activation and increased production of interleukin-17 and tumour necrosis factor-α of mucosal-associated invariant T cells in patients with periodontitis.

AIM: Mucosal-associated invariant T (MAIT) cells are known to be resident in oral mucosal tissue, but their roles in periodontitis are unknown. This study aimed to examine the level and function of MAIT cells in periodontitis patients. MATERIALS AND METHODS: Frequency, activation, and function of MAIT cells from 28 periodontitis patients and 28 healthy controls (HCs) were measured by flow cytometry. RESULTS: Circulating MAIT cells were numerically reduced in periodontitis patients. Moreover, they exhibited higher expression of CD69 and annexin V, together with more increased production of interleukin (IL)-17 and tumour necrosis factor (TNF)-α, in periodontitis patients than in HCs. Interestingly, periodontitis patients had higher frequencies of MAIT cells in gingival tissue than in peripheral blood. In addition, circulating MAIT cells had elevated expression of tissue-homing chemokine receptors such as CCR6 and CXCR6, and the corresponding chemokines (i.e., CCL20 and CXCL16) were more strongly expressed in inflamed gingiva than in healthy gingiva. CONCLUSIONS: This study demonstrates that circulating MAIT cells are numerically deficient with an activated profile toward the production of IL-17 and TNF-α in periodontitis patients. Furthermore, circulating MAIT cells have the potential to migrate to inflamed gingival tissues.

The Purinergic Receptor P2X4 Promotes Th17 Activation and the Development of Arthritis.

Purinergic signaling plays a major role in T cell activation leading to IL-2 production and proliferation. However, it is unclear whether purinergic signaling contributes to the differentiation and activation of effector T cells. In this study, we found that the purinergic receptor P2X4 was associated with human Th17 cells but not with Th1 cells. Inhibition of P2X4 receptor with the specific antagonist 5-BDBD and small interfering RNA inhibited the development of Th17 cells and the production of IL-17 by effector Th17 cells stimulated via the CD3/CD28 pathway. Our results showed that P2X4 was required for the expression of retinoic acid-related orphan receptor C, which is the master regulator of Th17 cells. In contrast, inhibition of P2X4 receptor had no effect on Th1 cells and on the production of IFN-γ and it did not affect the expression of the transcription factor T-bet (T-box transcription factor). Furthermore, inhibition of P2X4 receptor reduced the production of IL-17 but not of IFN-γ by effector/memory CD4+ T cells isolated from patients with rheumatoid arthritis. In contrast to P2X4, inhibition of P2X7 and P2Y11 receptors had no effects on Th17 and Th1 cell activation. Finally, treatment with the P2X4 receptor antagonist 5-BDBD reduced the severity of collagen-induced arthritis in mice by inhibiting Th17 cell expansion and activation. Our findings provide novel insights into the role of purinergic signaling in T cell activation and identify a critical role for the purinergic receptor P2X4 in Th17 activation and in autoimmune arthritis.

The Dual Role of the ß2-Adrenoreceptor in the Modulation of IL-17 and IFN-γ Production by T Cells in Multiple Sclerosis.

Norepinephrine is a neurotransmitter that also has an immunomodulatory effect and is involved in multiple sclerosis (MS) pathogenesis. This study aimed to clarify the role of the ß2-adrenoreceptor in the norepinephrine-mediated modulation of interleukin-17 (IL-17) and interferon-γ (IFN-γ) production, which play a critical pathogenetic role in MS. CD4+ T cells obtained from twenty-five relapsing-remitting MS patients and sixteen healthy subjects were cultured ex vivo with norepinephrine and/or ß2-adrenoreceptor antagonist or agonist, followed by a cytokine production analysis using ELISA. Norepinephrine suppressed IL-17 and IFN-γ production by the anti-CD3/anti-CD28-microbead-stimulated CD4+ T cells in both groups. Blockade of the ß2-adrenoreceptor with the specific antagonist ICI 118.551 enhanced norepinephrine-mediated IL-17 suppression but decreased its inhibitory effect on IFN-γ production in MS patients. In contrast, the ß2-adrenoreceptor agonist formoterol did not influence norepinephrine's inhibitory effect on cytokine production in both groups. The blockade of the ß2-adrenoreceptor, even in the absence of exogenous norepinephrine, suppressed IL-17 production but did not influence IFN-γ production in both groups. Conversely, ß2-adrenoreceptor activation by formoterol decreased IFN-γ production and did not affect IL-17 production in both groups. These data illustrate the inhibitory effect of norepinephrine on IL-17 and IFN-γ production by CD4+ T cells in MS. The inhibitory effect of norepinephrine on IFN-γ production by CD4+ T cells in MS could be mediated via ß2-adrenoreceptor activation.

Calcitonin gene-related peptide upregulates IL-17A and IL-22 in γδ-T cells through the paracrine effect of langerhans cells on LC/γδ-T co-culture model.

Intense mental stimulation and stress often directly induce or exacerbate psoriasis. On the contrary, patients with nerve injury and nervous system dysfunction have psoriasis remission. The nervous system plays an important role in the inflammatory process of psoriasis, and neuropeptides are considered as local mediators of disease maintenance. To examine the molecular mechanism involved in this, first we analyzed calcitonin gene-related peptide (CGRP)-treated langerhans Cells and γδ-T cells separately. CGRP induced IL-23 mRNA and protein expression via PDK1-Rsk signaling pathway. However, CGRP had no effect on secretion of IL-17A and IL-22 in γδ-T cells. Then we treated LCs/γδ-T cells Co-culture Model with CGRP. CGRP upregulated IL-17A and IL-22 expression in co-culture model through the paracrine effect of LCs. IL-17A and IL-22 are key cytokines of psoriasis. These findings provide a potential mechanism by which nerve factors affect the development of psoriasis.

Regulation of Cutaneous Immunity In Vivo by Calcitonin Gene-Related Peptide Signaling through Endothelial Cells.

Calcitonin gene-related peptide (CGRP) can bias the outcome of Ag presentation to responsive T cells in vitro away from Th1-type immunity and toward the Th2 and Th17 poles through actions on endothelial cells (ECs). To test the in vivo significance of this observation, we engineered a mouse lacking functional CGRP receptors on ECs (EC receptor activity modifying protein 1 [RAMP1] knockout mice). On percutaneous immunization to 1-fluoro-2,4-dinitrobenzene, stimulated CD4+ T cells from draining lymph nodes showed significantly reduced IL-17A expression with significantly increased IFN-γ, IL-4, and IL-22 expression at the protein and mRNA levels compared with control mice. Retinoic acid receptor-related orphan receptor γ t mRNA was significantly reduced, while mRNAs for T-box expressed in T cells and GATA binding protein 3 were significantly increased. In addition, EC RAMP1 knockout mice had significantly reduced contact hypersensitivity responses, and systemic administration of a CGRP receptor antagonist similarly inhibited contact hypersensitivity in wild-type mice. These observations provide compelling evidence that CGRP is a key regulator of cutaneous immunity through effects on ECs and suggest a novel pathway for potential therapeutic manipulation.

IL-17A-producing sinonasal MAIT cells in patients with chronic rhinosinusitis with nasal polyps.

BACKGROUND: Diverse immune cells contribute to the pathogenesis of chronic rhinosinusitis (CRS), an inflammatory disease of the nasal cavity and paranasal sinuses. However, whether mucosal-associated invariant T (MAIT) cells are present in human sinonasal tissues remains unclear. Furthermore, the characteristics of sinonasal MAIT cells have not been studied in patients with CRS. OBJECTIVE: We investigated the phenotype, function, and clinical implications of MAIT cells in patients with CRS. METHODS: Peripheral blood and sinonasal tissue were obtained from patients with CRS with (CRSwNP) or without nasal polyps (CRSsNP) and healthy controls. MAIT cells were analyzed by flow cytometry. RESULTS: We found that MAIT cells are present in human sinonasal tissues from healthy controls and patients with CRS. The sinonasal MAIT cell population, but not peripheral blood MAIT cells, from patients with CRSsNP, noneosinophilic CRSwNP (NE-NP), or eosinophilic CRSwNP (E-NP) had a significantly higher frequency of activated cells marked by CD38 expression. In functional analysis, the sinonasal MAIT cell population from NE-NP and E-NP had a significantly higher frequency of IL-17A+ cells but lower frequency of IFN-γ+ or TNF+ cells than control sinonasal tissues. Furthermore, CD38 expression and IL-17A production by sinonasal MAIT cells significantly correlated with disease extent evaluated by the Lund-Mackay computed tomography score in patients with E-NP. CONCLUSIONS: Sinonasal MAIT cells exhibit an activated phenotype and produce higher levels of IL-17A in patients with CRSwNP. These alterations are associated with the extent of disease in patients with E-NP.

The Effect of IL-35 on the Expression of Nasal Epithelial-Derived Proinflammatory Cytokines.

BACKGROUND: Airway epithelium plays an important role during the development of allergic rhinitis (AR), which is characterized by production of thymic stromal lymphopoietin (TSLP), interleukin 33 (IL-33), and interleukin 25 (IL-25). IL-35, mainly expressed by Treg cells, have negative regulation in Th2, Th17, and ILC2 inflammation. However, the effect of IL-35 on human nasal epithelial cells (HNECs) especially the secretion of nasal epithelial-derived proinflammatory cytokines as well as the possible mechanism is still unclear. METHODS: HNECs were cultured and stimulated by various stimulators. The expression of IL-33, IL-25, TSLP, eotaxin-1, eotaxin-2, and eotaxin-3 from supernatant was measured using real-time reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). AR mice were developed to verify the effect of IL-35 on nasal epithelial cells in vivo. RESULTS: After Poly I:C stimulation, IL-35 inhibited the production of IL-25, and TSLP from HNECs increased significantly compared with baseline levels (P < 0.05). After Dermatophagoides pteronyssinus or Aspergillus fumigatus stimulation, IL-35 inhibited the production of IL-25, IL-33, and TSLP from HNECs increased significantly compared with baseline levels (P < 0.05). After Dermatophagoides pteronyssinus, IL-35 inhibited the production of eotaxin-1, eotaxin-2, and eotaxin-3 released from HNECs increased significantly compared with baseline levels (P < 0.05). Similarly, IL-35-treated AR mice presented with decreased expression of IL-33, IL-25, TSLP, eotaxin-1, eotaxin-2, and eotaxin-3 in nasal lavage fluid. CONCLUSION: IL-35 suppressed both type 2 inflammation-inducing cytokines and eosinophil chemotactic factor from HNECs, suggesting the important role of IL-35 during the development of AR.

Tetracyclines Diminish In Vitro IFN-γ and IL-17-Producing Adaptive and Innate Immune Cells in Multiple Sclerosis.

Introduction: Limited data from clinical trials in multiple sclerosis (MS) reported that minocycline, a widely used antibiotic belonging to the family of tetracyclines (TCs), exerts a beneficial short-lived clinical effect A similar anti-inflammatory effect of minocycline attributed to a deviation from Th1 to Th2 immune response has been reported in experimental models of MS. Whether such an immunomodulatory mechanism is operated in the human disease remains largely unknown. Aim: To assess the in vitro immunomodulatory effect of tetracyclines, and in particular minocycline and doxycycline, in naïve and treated patients with MS. Material and Methods: Peripheral blood mononuclear cells from 45 individuals (35 MS patients, amongst which 15 naïve patients and 10 healthy controls, HCs) were cultured with minocycline or doxycycline and conventional stimulants (PMA/Ionomycin or IL-12/IL-18). IFN-γ and IL-17 producing T-, NK- and NKT cells were assessed by flow cytometry. The effect of TCs on cell viability and apoptosis was further assessed by flow cytometry with Annexin V staining. Results: Both tetracyclines significantly decreased, in a dose dependent manner, IFN-γ production in NKT and CD4+ T lymphocytes from MS patients (naïve or treated) stimulated with IL-12/IL-18 but did not decrease IFN-γ producing CD8+ T cells from naive MS or treated RRMS patients. They also decreased IL-17+ T and NKT cells following PMA and Ionomycin-stimulation. Tetracyclines did not affect the viability of cell subsets. Conclusion: Tetracyclines can in vitro suppress IFN-γ and IL-17- producing cells from MS patients, and this may explain their potential therapeutic effect in vivo.

T-bet represses collagen-induced arthritis by suppressing Th17 lineage commitment through inhibition of RORγt expression and function.

T-bet is a key transcription factor for the T helper 1 lineage and its expression level is negatively correlated to inflammation in patients with rheumatoid arthritis (RA). Our previous study using T-bet transgenic mice revealed over-expression of T-bet completely suppressed collagen-induced arthritis (CIA), a murine model of RA, indicating a potential suppressive role of T-bet in the pathogenesis of autoimmune arthritis. Here, we show T-bet-deficiency exacerbated CIA. T-bet in CD4 + T cells, but not in CD11c + dendritic cells, was critical for regulating the production of IL-17A, IL-17F, IL-22, and TNFα from CD4 + T cells. T-bet-deficient CD4 + T cells showed higher RORγt expression and increased IL-17A production in RORγt-positive cells after CII immunization. In addition, T-bet-deficient naïve CD4 + T cells showed accelerated Th17 differentiation in vitro. CIA induced in CD4-Cre T-betfl/fl (cKO) mice was more severe and T-bet-deficient CD4 + T cells in the arthritic joints of cKO mice showed higher RORγt expression and increased IL-17A production. Transcriptome analysis of T-bet-deficient CD4 + T cells revealed that expression levels of Th17-related genes were selectively increased. Our results indicate that T-bet in CD4 + T cells repressed RORγt expression and function resulting in suppression of arthritogenic Th17 cells and CIA.

ILC1s and ILC3s Exhibit Inflammatory Phenotype in Periodontal Ligament of Periodontitis Patients.

Innate lymphoid cells (ILCs) are emerging as important players in inflammatory diseases. The oral mucosal barrier harbors all ILC subsets, but how these cells regulate the immune responses in periodontal ligament tissue during periodontitis remains undefined. Here, we show that total ILCs are markedly increased in periodontal ligament of periodontitis patients compared with healthy controls. Among them, ILC1s and ILC3s, particularly NKp44+ILC3 subset, are the predominant subsets accumulated in the periodontal ligament. Remarkably, ILC1s and ILC3s from periodontitis patients produce more IL-17A and IFN-γ than that from healthy controls. Collectively, our results highlight the role of ILCs in regulating oral immunity and periodontal ligament inflammation and provide insights into targeting ILCs for the treatment of periodontitis.

Tuhuaiyin alleviates imiquimod-induced psoriasis via inhibiting the properties of IL-17-producing cells and remodels the gut microbiota.

BACKGROUND: psoriasis is a chronic inflammatory skin disease. The accumulation of IL-17 cytokines in the lesions leads to epidermis proliferation. Traditional Chinese medicine has a significant effect on psoriasis treatment. Among them, Tuhuaiyin is a representative prescription, which has an outstanding curative effect in acute and remission stage. METHODS: To reveal the target and molecular mechanism of Tuhuaiyin, systematic pharmacology platform and database screening were used to construct the Tuhuaiyin interaction network with compounds, targets and diseases. The intervention of Tuhuaiyin on keratinocyte proliferation and inflammation was verified in the model of psoriasis-like lesions induced by imiquimod. The effect on the number and function of IL-17-producing cells was detected, and the regulatory effect of Tuhuaiyin on gut microbial was explored. RESULTS: 32 selected active molecules in Tuhuaiyin acted on psoriasis biological processes. Tuhuaiyin significantly alleviates erythema and scales in the psoriasis like mouse model induced by imiquimod. Excessive proliferation of keratinocytes and infiltration of inflammatory cells were restrained in the dermis by using Tuhuaiyin. The expression of IL-17 was down-regulated in skin and peripheral blood. The proportion of IL-17-producing cells was decreased in immune organs. And phosphorylation of JNK inhibited in skin lesions. At the same time, the change of gut microbial diversity in the psoriasis-like model was improved. CONCLUSION: our study predicted and verified the molecular immunological mechanism of Tuhuaiyin, alleviated the abnormal proliferation of keratinocytes by inhibiting the proportion of IL-17-producing cells and the expression of IL-17 cytokines. Taken together, our data identify the therapeutic potential of Tuhuaiyin for psoriasis.

Clostridium butyricum enhances colonization resistance against Clostridioides difficile by metabolic and immune modulation.

Clostridioides difficile infection (CDI) represents the leading cause of nosocomial diarrhea worldwide and is associated with gut dysbiosis and intestinal damage. Clostridium butyricum MIYAIRI 588 (CBM 588) contributes significantly to reduce epithelial damage. However, the impacts of CBM 588 on antibacterial therapy for CDI are not clear. Here we show that CBM 588 enhanced the antibacterial activity of fidaxomicin against C. difficile and negatively modulated gut succinate levels to prevent C. difficile proliferation and downregulate tumor necrosis factor-α (TNF-α) producing macrophages in the colon lumina propria (cLP), resulting in a significant decrease in colon epithelial damage. Additionally, CBM 588 upregulated T cell-dependent pathogen specific immunoglobulin A (IgA) via interleukin (IL)-17A producing CD4+ cells and plasma B cells in the cLP, and Th17 cells in the cLP enhanced the gut epithelial barrier function. IL-17A and succinic acid modulations with CBM 588 enhance gut colonization resistance to C. difficile and protect the colon tissue from CDI.

Gut microbiota-derived short-chain fatty acids regulate IL-17 production by mouse and human intestinal γδ T cells.

Gut interleukin-17A (IL-17)-producing γδ T cells are tissue-resident cells that are involved in both host defense and regulation of intestinal inflammation. However, factors that regulate their functions are poorly understood. In this study, we find that the gut microbiota represses IL-17 production by cecal γδ T cells. Treatment with vancomycin, a Gram-positive bacterium-targeting antibiotic, leads to decreased production of short-chain fatty acids (SCFAs) by the gut microbiota. Our data reveal that these microbiota-derived metabolites, particularly propionate, reduce IL-17 and IL-22 production by intestinal γδ T cells. Propionate acts directly on γδ T cells to inhibit their production of IL-17 in a histone deacetylase-dependent manner. Moreover, the production of IL-17 by human IL-17-producing γδ T cells from patients with inflammatory bowel disease (IBD) is regulated by propionate. These data contribute to a better understanding of the mechanisms regulating gut γδ T cell functions and offer therapeutic perspectives of these cells.

Increased interleukin-17A-producing γδT cells predict favorable survival in elderly patients with LUAD and LUSC.

PURPOSE: Aging is closely related to the occurrence of many diseases, including cancer, and involves changes in the immune microenvironment. γδT cells are important components of resident lymphocytes in mucosal tissues. However, little is known about the effects that the aged lung has on γδT cells and their prognostic significance in non-small cell lung cancer. METHODS: In the current study, the expression of γδTCR and IL-17A was measured by immunohistochemistry in paraffin-embedded lung tissues from 168 patients with adenocarcinoma (LUAD) and 144 patients with squamous cell carcinoma (LUSC). Furthermore, gene transcription patterns in LUAD and LUSC tumors and normal controls were extracted from TCGA and GTEx databases and were analyzed. RESULTS: High frequency of γδT cells was observed in patients with LUAD and LUSC, whereas the levels of CD4 + T cells, CD8 + T cells and CD56 + cells were decreased. Elevated γδT cells in tumors were mainly IL-17A-releasing γδT17 cells, which were found to be enriched in aged patients. High γδT cell levels positively corelated with the overall survival (OS) of patients, especially the 5-year OS in the elderly. Further analysis of gene transcription patterns indicated that increased expression of LTBR, HES1, RORC, CCR6, IL1, and IL23A may contribute to the transformation of the tumor microenvironment in a manner conducive to γδT17 cell development and differentiation. Finally, gene analysis between different age groups revealed that the expression of CCR6 and IL7 in LUAD, as well as Hes1, IL7, and IL23A in LUSC, were remarkably higher in elderly (age ≥ 60 years) than in younger individuals (age < 60 years). CONCLUSION: Our findings suggest that intrinsic alterations in the aging lung lead to γδT17 cell enrichment, which subsequently may exert anti-tumor effects in the elderly.

Prostaglandin E2 amplifies IL-17 production by γδ T cells during barrier inflammation.

Interleukin-17 (IL-17)-producing γδ (γδ17) T cells are innate-like lymphocytes that contribute to protective anti-microbial responses but are also implicated in pathogenic inflammation at barrier sites. Understanding tissue-specific signals that regulate this subset is important to boost host defense mechanisms, but also to mitigate immunopathology. Here, we demonstrate that prostaglandin E2 (PGE2), a cyclooxygenase-dependent member of the eicosanoid family, directly enhances cytokine production by circulating and tissue-specific γδ17 T cells in vitro. Gain- and loss-of-function in vivo approaches further reveal that although provision of PGE2 amplifies psoriasiform inflammation, ablation of host mPGES1-dependent PGE2 synthesis is dispensable for cutaneous γδ17 T cell activation. By contrast, loss of endogenous PGE2 production or depletion of the gut microbiota compromises intestinal γδ17 T cell responses and increases disease severity during experimental colitis. Together, our results demonstrate how a lipid mediator can synergize with tissue-specific signals to enhance innate lymphocyte production of IL-17 during barrier inflammation.

Granzyme B prevents aberrant IL-17 production and intestinal pathogenicity in CD4+ T cells.

CD4+ T cell activation and differentiation are important events that set the stage for proper immune responses. Many factors are involved in the activation and differentiation of T cells, and these events are tightly controlled to prevent unwanted and/or exacerbated immune responses that may harm the host. It has been well-documented that granzyme B, a potent serine protease involved in cell-mediated cytotoxicity, is readily expressed by certain CD4+ T cells, such as regulatory T cells and CD4+CD8αα+ intestinal intraepithelial lymphocytes, both of which display cytotoxicity associated with granzyme B. However, because not all CD4+ T cells expressing granzyme B are cytotoxic, additional roles for this protease in CD4+ T cell biology remain unknown. Here, using a combination of in vivo and in vitro approaches, we report that granzyme B-deficient CD4+ T cells display increased IL-17 production. In the adoptive transfer model of intestinal inflammation, granzyme B-deficient CD4+ T cells triggered a more rapid disease onset than their WT counterparts, and presented a differential transcription profile. Similar results were also observed in granzyme B-deficient mice infected with Citrobacter rodentium. Our results suggest that granzyme B modulates CD4+ T cell differentiation, providing a new perspective into the biology of this enzyme.

Vγ4 T cell-derived IL-17A is essential for amplification of inflammatory cascades in ischemic brain tissue after stroke.

BACKGROUND: Through amplifying inflammatory cascades, IL-17A produced by γδ T cells potently attracts neutrophils to the site of injury for exacerbating ischemic tissue damage. Our goal was to identify the precise role of γδ T cell subsets in ischemic brain tissue damage of stroke. METHODS: In a model of experimental stroke, we analyzed the functions of Vγ1 and Vγ4 T cells on γδ T cell-mediated ischemic brain tissue damage of stroke. RESULTS: We identified that, in stroke, Vγ4 T cells are essential for γδ T cell-mediated ischemic brain tissue damage through providing an early source of IL-17A. Both CCL20 and IL-1ß/IL-23 are deeply involved in Vγ4 T cell-mediated amplification of inflammatory responses: CCL20 might promote Vγ4 T cells recruit to infract hemisphere, and IL-1ß/IL-23 powerfully enhance IL-17A production mediated by the infiltrating Vγ4 T cells. Moreover, Vγ4 T cell-derived IL-17A enhances both CCL20 and IL-1ß, and conversely, CCL20 and IL-1ß further enhance both recruitment and IL-17A production of IL-17A-positive cells, in a classic positive feedback loop. CONCLUSION: Our data suggest that in the setting of ischemic stroke, Vγ4 T cell-derived IL-17A, CCL20 and IL-1ß/IL-23 in infract hemisphere coordinately to amplify inflammatory cascades and exacerbate ischemic tissue damage.

Nuclear factor erythroid 2-related factor 2 potentiates the generation of inflammatory cytokines by intestinal epithelial cells during hyperoxia by inducing the expression of interleukin 17D.

Prolonged exposure to therapeutic hyperoxia can induce severe side effects on intestinal epithelial cells. Meanwhile, interleukin (IL)-17D secreted by intestinal epithelial cells, plays an important role in the mucosal immune system. Therefore, this study aimed to investigate the changes of IL-17D, IL-4 and IL-6 and the regulatory effect of nuclear factor erythroid 2-related factor 2 (Nrf2) on IL-17D, IL-4 and IL-6 under hyperoxia in human intestinal epithelial cells. To achieve this, NCM460 cells were exposed to an atmosphere containing 85 % oxygen (hyperoxia) for 24 h, 48 h, or 72 h; tert-butylhydroquinone (tBHQ) and ML385 were used as an Nrf2 activator and inhibitor, respectively. Immunohistochemical staining, western blot, and reverse transcription-quantitative polymerase chain reaction were performed to detect the expression levels of IL-17D, Nrf2, Kelch-like ECH-associated protein 1 (Keap1), IL-6, and IL-4 in NCM460 cells. Results showed that hyperoxia significantly increased the expression of IL-17D, Nrf2, IL-6, and IL-4, while decreasing that of Keap1. tBHQ further activated Nrf2 and promoted the expression of IL-17D, IL-6, and IL-4. Additionally, tBHQ aggravated hyperoxia-induced inflammation caused by hyperoxia. In contrast, ML385 completely inhibited the expression of Nrf2 and IL-17D, transiently inhibited IL-6 and IL-4 expression, and did not influence Keap1 expression. These results cumulatively demonstrate that hyperoxia aggravates the inflammatory response in intestinal epithelial cells by activating the Nrf2/IL-17D axis.

Staphylococcus aureus-Specific Tissue-Resident Memory CD4+ T Cells Are Abundant in Healthy Human Skin.

The skin is an immunocompetent tissue that harbors several kinds of immune cells and a plethora of commensal microbes constituting the skin microbiome. Staphylococcus aureus is a prominent skin pathogen that colonizes a large proportion of the human population. We currently have an incomplete understanding of the correlates of protection against S. aureus infection, however genetic and experimental evidence has shown that CD4+ T cells play a key role in orchestrating a protective anti-S. aureus immune response. A high S. aureus-specific memory CD4+ T cell response has been reported in the blood of healthy subjects. Since T cells are more abundant in the skin than in blood, we hypothesized that S. aureus-specific CD4+ T cells could be present in the skin of healthy individuals. Indeed, we observed proliferation of tissue-resident memory CD4+ T cells and production of IL-17A, IL-22, IFN-γ and TNF-ß by cells isolated from abdominal skin explants in response to heat-killed S. aureus. Remarkably, these cytokines were produced also during an ex vivo epicutaneous S. aureus infection of human skin explants. These findings highlight the importance of tissue-resident memory CD4+ T cells present at barrier sites such as the skin, a primary entry site for S. aureus. Further phenotypical and functional characterization of these cells will ultimately aid in the development of novel vaccine strategies against this elusive pathogen.