Mycobacterium tuberculosis-Specific IL-21+IFN-γ+CD4+ T Cells Are Regulated by IL-12

In the current study of Mycobacterium tuberculosis (MTB)-specific T and B cells, we found that MTB-specific peptides from early secreted antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) induced the expression of IL-21 predominantly in CD4⁺ T cells. A fraction of IL-21-expressing CD4⁺ T cells simultaneously expressed Th1 cytokines but did not secrete Th2 or Th17 cytokines, suggesting that MTB-specific IL-21-expressing CD4⁺ T cells were different from Th1, Th2 and Th17 subpopulations. The majority of MTB-specific IL-21-expressing CD4⁺ T cells co-expressed IFN-γ and IL-21⁺IFN-γ⁺CD4⁺ T cells exhibited obviously polyfunctionality. In addition, MTB-specific IL-21-expressing CD4⁺ T cells displayed a CD45RO⁺CD62L^lowCCR7^lowCD40L^highICOS^high phenotype. Bcl-6-expression was significantly higher in IL-21-expressing CD4⁺ T cells than IL-21^-CD4⁺ T cells. Moreover, IL-12 could up-regulate MTB-specific IL-21 expression, especially the frequency of IL-21⁺IFN-γ⁺CD4⁺ T cells. Taken together, our results demonstrated that MTB-specific IL-21⁺IFN-γ⁺CD4⁺ T cells from local sites of tuberculosis (TB) infection could be enhanced by IL-12, which have the features of both Tfh and Th1 cells and may have an important role in local immune responses against TB infection.     

Interferon-β Suppresses Murine Th1 Cell Function in the Absence of Antigen-Presenting Cells

Interferon (IFN)-β is a front-line therapy for the treatment of the relapsing-remitting form of multiple sclerosis. However, its immunosuppressive mechanism of function remains incompletely understood. While it has been proposed that IFN-β suppresses the function of inflammatory myelin antigen-reactive T cells by promoting the release of immunomodulatory cytokines such as IL-27 from antigen-presenting cells (APCs), its direct effects on inflammatory CD4⁺ Th1 cells are less clear. Here, we establish that IFN-β inhibits mouse IFN-γ⁺ Th1 cell function in the absence of APCs. CD4⁺ T cells express the type I interferon receptor, and IFN-β can suppress Th1 cell proliferation under APC-free stimulation conditions. IFN-β-treated myelin antigen-specific Th1 cells are impaired in their ability to induce severe experimental autoimmune encephalomyelitis (EAE) upon transfer to lymphocyte-deficient Rag1^-/- mice. Polarized Th1 cells downregulate IFN-γ and IL-2, and upregulate the negative regulatory receptor Tim-3, when treated with IFN-β in the absence of APCs. Further, IFN-β treatment of Th1 cells upregulates phosphorylation of Stat1, and downregulates phosphorylation of Stat4. Our data indicate that IFN-γ-producing Th1 cells are directly responsive to IFN-β and point to a novel mechanism of IFN-β-mediated T cell suppression that is independent of APC-derived signals.     

Dendritic Cell-Specific Deletion of β-Catenin Results in Fewer Regulatory T-Cells without Exacerbating Autoimmune Collagen-Induced Arthritis

Dendritic cells (DCs) are professional antigen presenting cells that have the dual ability to stimulate immunity and maintain tolerance. However, the signalling pathways mediating tolerogenic DC function in vivo remain largely unknown. The β-catenin pathway has been suggested to promote a regulatory DC phenotype. The aim of this study was to unravel the role of β-catenin signalling to control DC function in the autoimmune collagen-induced arthritis model (CIA). Deletion of β-catenin specifically in DCs was achieved by crossing conditional knockout mice with a CD11c-Cre transgenic mouse line. Bone marrow-derived DCs (BMDCs) were generated and used to study the maturation profile of these cells in response to a TLR2 or TLR4 ligand stimulation. CIA was induced by intra-dermal immunization with 100 μg chicken type II collagen in complete Freund’s adjuvant on days 0 and 21. CIA incidence and severity was monitored macroscopically and by histology. The T cell profile as well as their cytokine production were analysed by flow cytometry. Lack of β-catenin specifically in DCs did not affect the spontaneous, TLR2- or TLR4-induced maturation and activation of BMDCs or their cytokine production. Moreover, no effect on the incidence and severity of CIA was observed in mice lacking β-catenin in CD11c⁺ cells. A decreased frequency of splenic CD3⁺CD8⁺ T cells and of regulatory T cells (Tregs) (CD4⁺CD25^highFoxP3⁺), but no changes in the frequency of splenic Th17 (CCR6⁺CXCR3^-CCR4⁺), Th2 (CCR6^-CXCR3^-CCR4⁺) and Th1 (CCR6^-CXCR3⁺CCR4^-) cells were observed in these mice under CIA condition. Furthermore, the expression of IL-17A, IL-17F, IL-22, IL-4 or IFNγ was also not affected. Our data indicate that ablation of β-catenin expression in DCs did not alter the course and severity of CIA. We conclude that although deletion of β-catenin resulted in a lower frequency of Tregs, this decrease was not sufficient to aggravate the onset and severity of CIA.     

Th1 and Th17 Responses to Helicobacter pylori in Bangladeshi Infants,Children and Adults

Both Th1 and Th17 cells are important components of the immune response to Helicobacter pylori (Hp) in adults, but less is known about T cell responses to Hp during early childhood, when the infection is often acquired. We investigated Th1 and Th17 type responses to Hp in adults, children and infants in Bangladesh, where Hp is highly endemic. IL-17 and IFN-γ mRNA levels in gastric biopsies from Hp-infected Bangladeshi adults were analyzed and compared to levels in infected and uninfected Swedish controls. Since biopsies could not be collected from infants and children, cytokine responses in Bangladeshi infants (6–12 months), children (3–5 years) and adults (>19 years) were instead compared by stimulating peripheral blood mononuclear cells (PBMCs) with a Hp membrane preparation (MP) and analyzing culture supernatants by ELISA and cytometric bead array. We found significantly higher expression of IL-17 and IFN-γ mRNA in gastric mucosa of Hp-infected Bangladeshi and Swedish adults compared to uninfected Swedish controls. PBMCs from all age groups produced IL-17 and IFN-γ after MP stimulation, but little Th2 cytokines. IL-17 and IFN-γ were primarily produced by CD4⁺ T cells, since CD4⁺ T cell depleted PBMCs produced reduced amounts of these cytokines. Infant cells produced significantly more IL-17, but similar levels of IFN-γ, compared to adult cells after MP stimulation. In contrast, polyclonal stimulation induced lower levels IL-17 and IFN-γ in infant compared to adult PBMCs and CD4⁺ T cells. The strong IL-17 production in infants after MP stimulation was paralleled by significantly higher production of the IL-17 promoting cytokine IL-1β from infant compared to adult PBMCs and monocytes. In conclusion, these results show that T cells can produce high levels of IL-17 and IFN-γ in response to Hp from an early age and indicate a potential role for IL-1β in promoting Th17 responses to Hp during infancy.     

B7-H3 Promotes Pathogenesis of Autoimmune Disease and Inflammation by Regulating the Activity of Different T Cell Subsets

B7-H3 is a cell surface molecule in the immunoglobulin superfamily that is frequently upregulated in response to autoantigens and pathogens during host T cell immune responses. However, B7-H3''s role in the differential regulation of T cell subsets remains largely unknown. Therefore, we constructed a new B7-H3 deficient mouse strain (B7-H3 KO) and evaluated the functions of B7-H3 in the regulation of Th1, Th2, and Th17 subsets in experimental autoimmune encephalomyelitis (EAE), experimental asthma, and collagen-induced arthritis (CIA); these mouse models were used to predict human immune responses in multiple sclerosis, asthma, and rheumatoid arthritis, respectively. Here, we demonstrate that B7-H3 KO mice have significantly less inflammation, decreased pathogenesis, and limited disease progression in both EAE and CIA mouse models when compared with littermates; these results were accompanied by a decrease in IFN-γ and IL-17 production. In sharp contrast, B7-H3 KO mice developed severe ovalbumin (OVA)-induced asthma with characteristic infiltrations of eosinophils in the lung, increased IL-5 and IL-13 in lavage fluid, and elevated IgE anti-OVA antibodies in the blood. Our results suggest B7-H3 has a costimulatory function on Th1/Th17 but a coinhibitory function on Th2 responses. Our studies reveal that B7-H3 could affect different T cell subsets which have important implications for regulating pathogenesis and disease progression in human autoimmune disease.     

Sunitinib Indirectly Enhanced Anti-Tumor Cytotoxicity of Cytokine-Induced Killer Cells and CD3+CD56+ Subset through the Co-Culturing Dendritic Cells

Cytokine-induced killer (CIK) cells have reached clinical trials for leukemia and solid tumors. Their anti-tumor cytotoxicity had earlier been shown to be intensified after the co-culture with dendritic cells (DCs). We observed markedly enhanced anti-tumor cytotoxicity activity of CIK cells after the co-culture with sunitinib-pretreated DCs over that of untreated DCs. This cytotoxicity was reliant upon DC modulation by sunitinib because the direct exposure of CIK cells to sunitinib had no significant effect. Sunitinib promoted Th1-inducing and pro-inflammatory phenotypes (IL-12, IFN-γ and IL-6) in DCs at the expense of Th2 inducing phenotype (IL-13) and regulatory phenotype (PD-L1, IDO). Sunitinib-treated DCs subsequently induced the upregulation of Th1 phenotypic markers (IFN-γ and T-bet) and the downregulation of the Th2 signature (GATA-3) and the Th17 marker (RORC) on the CD3⁺CD56⁺ subset of CIK cells. It concluded that sunitinib-pretreated DCs drove the CD3⁺CD56⁺ subset toward Th1 phenotype with increased anti-tumor cytotoxicity.     

Differential Modulation by IL-17A of Cholangitis versus Colitis in IL-2Rα Deleted Mice

IFN-γ is a signature Th1 cell associated cytokine critical for the inflammatory response in autoimmunity with both pro-inflammatory and potentially protective functions. IL-17A is the hallmark of T helper 17 (Th17) cell subsets, produced by γδT, CD8+ T, NK and NKT cells. We have taken advantage of our colony of IL-2Rα^−/− mice that spontaneously develop both autoimmune cholangitis and inflammatory bowel disease. In this model CD8+ T cells mediate biliary ductular damage, whereas CD4+ T cells mediate induction of colon-specific autoimmunity. Importantly, IL-2Rα^−/− mice have high levels of interferon γ (IFN-γ), and interleukin-17A (IL-17A). We produced unique double deletions of mice that were either IL-17A^−/−IL-2Rα^−/− or IFN-γ^−/−IL-2Rα^−/− to specifically address the precise role of these two cytokines in the natural history of autoimmune cholangitis and colitis. Of note, deletion of IL-17A in IL-2Rα^−/− mice led to more severe liver inflammation, but ameliorated colitis. In contrast, there were no significant changes in the immunopathology of double knock-out IFN-γ^−/− IL-2Rα^−/− mice, compared to single knock-out IL-2Rα^−/− mice with respect to cholangitis or colitis. Furthermore, there was a significant increase in pathogenetic CD8+ T cells in the liver of IL-17A^−/−IL-2Rα^−/− mice. Our data suggest that while IL-17A plays a protective role in autoimmune cholangitis, it has a pro-inflammatory role in inflammatory bowel disease. These data take on particular significance in the potential use of anti-IL-17A therapy in humans with primary biliary cirrhosis.     

γδT Cells Are Prevalent in the Proximal Aorta and Drive Nascent Atherosclerotic Lesion Progression and Neutrophilia in Hypercholesterolemic Mice

Unique innate immunity-linked γδT cells have been seen in early human artery lesions, but their role in lesion development has received little attention. Here we investigated whether γδT cells modulate atherogenesis in apolipoprotein E-deficient (ApoE KO) mice. We found that γδT cell numbers were markedly increased in the proximal aorta of ApoE-deficient vs. wild-type mice during early atherogenesis, particularly in the aortic root and arch, where they comprised most of the T cells and lesion progression is most rapid. γδT cells infiltrated intimal lesions in ApoE KO mice, but only the adventitia in wild-type mice, and were more prevalent than CD4⁺ T cells in early nascent lesions, as evaluated by en face confocal microscopy. These aortic γδT cells produced IL-17, but not IFN-γ, analyzed by ex vivo FACS. Furthermore, aortic arch lipid accumulation correlated strongly with abundance of IL-17-expressing splenic γδT cells in individual ApoE KO mice. To investigate the role of these γδT cells in early atherogenesis, we analyzed ApoE/γδT double knockout (DKO) compared to ApoE KO mice. We observed reduced early intimal lipid accumulation at sites of nascent lesion formation, both in chow-fed (by 40%) and Western diet-fed (by 44%) ApoE/γδT DKO mice. In addition, circulating neutrophils were drastically reduced in these DKO mice on Western diet, while expansion of inflammatory monocytes and splenic Th1 or Th17 lymphocytes was not affected. These data reveal, for the first time, a pathogenic role of γδT cells in early atherogenesis in ApoE KO mice, by mechanisms likely to involve their IL-17 production and induction of neutrophilia. Targeting γδT cells thus might offer therapeutic benefit in atherosclerosis or other inflammatory vascular diseases.     

IFN-β Inhibits the Increased Expression of IL-9 during Experimental Autoimmune Uveoretinitis

Purpose

It has been shown that IL-9 plays a proinflammatory role in the pathogenesis of certain autoimmune diseases. This study was designed to investigate the possible role of IL-9 in the development of experimental autoimmune uveoretinitis (EAU) and the effect of IFN-β on its expression.

Methods

EAU was induced in B10RIII mice by immunization with interphotoreceptor retinoid-binding protein peptide 161–180 (IRBP_161–180). IFN-β was administered subcutaneously to IRBP_161–180 immunized mice every other day from day one before immunization to the end of the study. Splenocytes and draining lymph node (DLN) cells from EAU mice or control mice or EAU mice treated with IFN-β or PBS were stimulated with anti-CD3/CD28 or IRBP_161–180 for 3 days. Naïve T cells cultured under Th1 or Th17 polarizing conditions were incubated in the presence or absence of IFN-β for 4 days. Effector/memory T cells were activated by anti-CD3/CD28 in the presence or absence of IFN-β for 3 days. IFN-β-treated monocytes were cocultured with naïve T cells or effector/memory T cells for 3 days. Culture supernatants were collected and IL-9 was detected by ELISA.

Results

IL-9 expression in splenocytes and DLN cells was increased in EAU mice during the inflammatory phase and returned back to lower levels during the recovery phase. IFN-β in vivo treatment significantly inhibited EAU activity in association with a down-regulated expression of IL-9. In vitro polarized Th1 and Th17 cells both secreted IL-9 and the addition of IFN-β suppressed production of IL-9 by both Th subsets. Beside its effect on polarized Th cells, IFN-β also suppressed the secretion of IL-9 by effector/memory T cells. However, IFN-β-treated monocytes had no effect on the production of IL-9 when cocultured with naïve or effector/memory T cells.

Conclusion

IL-9 expression is increased during EAU which could be suppressed by IFN-β.     

Activation of Invariant NKT Cells with Glycolipid Ligand α-Galactosylceramide Ameliorates Glucose-6-Phosphate Isomerase Peptide-Induced Arthritis

Objective

Invariant natural killer T (iNKT) cells regulate collagen-induced arthritis (CIA) when activated by their potent glycolipid ligand, alpha-galactosylceramide (α-GalCer). Glucose-6-phosphate isomerase (GPI)-induced arthritis is a closer model of human rheumatoid arthritis based on its association with CD4+ T cells and cytokines such as TNF-α and IL-6 than CIA. Dominant T cell epitope peptide of GPI (GPI325-339) can induce arthritis similar to GPI-induced arthritis. In this study, we investigated the roles of activation of iNKT cells by α-GalCer in GPI peptide-induced arthritis.

Methods

Arthritis was induced in susceptible DBA1 mice with GPI peptide and its severity was assessed clinically. The arthritic mice were treated with either the vehicle (DMSO) or α-GalCer. iNKT cells were detected in draining lymph nodes (dLNs) by flow cytometry, while serum anti-GPI antibody levels were measured by enzyme-linked immunosorbent assay. To evaluate GPI peptide-specific cytokine production from CD4+ T cells, immunized mice were euthanized and dLN CD4+ cells were re-stimulated by GPI-peptide in the presence of antigen-presenting cells.

Results

α-GalCer induced iNKT cell expansion in dLNs and significantly decreased the severity of GPI peptide-induced arthritis. In α-GalCer-treated mice, anti-GPI antibody production (total IgG, IgG1, IgG2b) and IL-17, IFN-γ, IL-2, and TNF-α produced by GPI peptide-specific T cells were significantly suppressed at day 10. Moreover, GPI-reactive T cells from mice immunized with GPI and α-GalCer did not generate any cytokines even when these cells were co-cultured with APC from mice immunized with GPI alone. In vitro depletion of iNKT cells did not alter the suppressive effect of α-GalCer on CD4+ T cells.

Conclusion

α-GalCer significantly suppressed GPI peptide-induced arthritis through the suppression of GPI-specific CD4+ T cells.     

Effector mechanisms of interleukin-17 in collagen-induced arthritis in the absence of interferon-γ and counteraction by interferon-γ

Introduction  

Interleukin (IL)-17 is a pro-inflammatory cytokine in rheumatoid arthritis (RA) and collagen-induced arthritis (CIA). Since interferon (IFN)-γ inhibits Th17 cell development, IFN-γ receptor knockout (IFN-γR KO) mice develop CIA more readily. We took advantage of this model to analyse the mechanisms of action of IL-17 in arthritis. The role of IFN-γ on the effector mechanisms of IL-17 in an in vitro system was also investigated.     

Anti-Chlamydial Th17 Responses Are Controlled by the Inducible Costimulator Partially through Phosphoinositide 3-Kinase Signaling

We previously showed that mice deficient in the Inducible Costimulator ligand (ICOSL-KO) develop more severe disease and lung pathology with delayed bacterial clearance upon respiratory infection of Chlamydia muridarum. Importantly, the exacerbation of disease in ICOSL-KO mice was seen despite heightened IFN-γ/Th1 responses, the major defense mechanisms against Chlamydia. To gain insight into the mechanism of ICOS function in this model, we presently analyzed anti-Chlamydia immune responses in mice lacking the entire ICOS (ICOS-KO) versus knock-in mice expressing a mutant ICOS (ICOS-Y181F) that has selectively lost the ability to activate phosphoinositide 3-kinase (PI3K). Like ICOSL-KO mice, ICOS-KO mice showed worse disease with elevated IFN-γ/Th1 responses compared to wild-type (WT) mice. ICOS-Y181F mice developed much milder disease compared to ICOS-KO mice, yet they were still not fully protected to the WT level. This partial protection in ICOS-Y181F mice could not be explained by the magnitude of IFN-γ/Th1 responses since these mice developed a similar level of IFN-γ response compared to WT mice. It was rather IL-17/Th17 responses that reflected disease severity: IL-17/Th17 response was partially impaired in ICOS-Y181F mice compared to WT, but was substantially stronger than that of ICOS-KO mice. Consistently, we found that both polarization and expansion of Th17 cells were partially impaired in ICOS-Y181F CD4 T cells, and was further reduced in ICOS-KO CD4 T cells in vitro. Our results indicate that once the IFN-γ/Th1 response is above a threshold level, the IL-17/Th17 response becomes a limiting factor in controlling Chlamydia lung infection, and that ICOS plays an important role in promoting Th17 responses in part through the activation of PI3K.     

Estradiol Enhances CD4+ T-Cell Anti-Viral Immunity by Priming Vaginal DCs to Induce Th17 Responses via an IL-1-Dependent Pathway

Clinical and experimental studies have shown that estradiol (E2) confers protection against HIV and other sexually transmitted infections. Here, we investigated the underlying mechanism. Better protection in E2-treated mice, immunized against genital HSV-2, coincided with earlier recruitment and higher proportions of T_h1 and T_h17 effector cells in the vagina post-challenge, compared to placebo-treated controls. Vaginal APCs isolated from E2-treated mice induced 10-fold higher T_h17 and T_h1 responses, compared to APCs from progesterone-treated, placebo-treated, and estradiol-receptor knockout mice in APC-T cell co-cultures. CD11c⁺ DCs in the vagina were the predominant APC population responsible for priming these T_h17 responses, and a potent source of IL-6 and IL-1β, important factors for T_h17 differentiation. T_h17 responses were abrogated in APC-T cell co-cultures containing IL-1β KO, but not IL-6 KO vaginal DCs, showing that IL-1β is a critical factor for T_h17 induction in the genital tract. E2 treatment in vivo directly induced high expression of IL-1β in vaginal DCs, and addition of IL-1β restored T_h17 induction by IL-1β KO APCs in co-cultures. Finally, we examined the role of IL-17 in anti-HSV-2 memory T cell responses. IL-17 KO mice were more susceptible to intravaginal HSV-2 challenge, compared to WT controls, and vaginal DCs from these mice were defective at priming efficient T_h1 responses in vitro, indicating that IL-17 is important for the generation of efficient anti-viral memory responses. We conclude that the genital mucosa has a unique microenvironment whereby E2 enhances CD4⁺ T cell anti-viral immunity by priming vaginal DCs to induce T_h17 responses through an IL-1-dependent pathway.     

Th1-Th17 Cells Contribute to the Development of Uropathogenic Escherichia coli-Induced Chronic Pelvic Pain

The etiology of chronic prostatitis/chronic pelvic pain syndrome in men is unknown but may involve microbes and autoimmune mechanisms. We developed an infection model of chronic pelvic pain in NOD/ShiLtJ (NOD) mice with a clinical Escherichia coli isolate (CP-1) from a patient with chronic pelvic pain. We investigated pain mechanisms in NOD mice and compared it to C57BL/6 (B6) mice, a strain resistant to CP-1-induced pain. Adoptive transfer of CD4+ T cells, but not serum, from CP-1-infected NOD mice was sufficient to induce chronic pelvic pain. CD4+ T cells in CP-1-infected NOD mice expressed IFN-γ and IL-17A but not IL-4, consistent with a Th1/Th17 immune signature. Adoptive transfer of ex-vivo expanded IFN-γ or IL-17A-expressing cells was sufficient to induce pelvic pain in naïve NOD recipients. Pelvic pain was not abolished in NOD-IFN-γ-KO mice but was associated with an enhanced IL-17A immune response to CP1 infection. These findings demonstrate a novel role for Th1 and Th17-mediated adaptive immune mechanisms in chronic pelvic pain.     

CD8low T cells expanded following acute Trypanosoma cruzi infection and benznidazole treatment are a relevant subset of IFN-γ producers

CD8 T cells are regarded as pivotal players in both immunoprotection and immunopathology following Trypanosoma cruzi infection. Previously, we demonstrated the expansion of CD8⁺ T lymphocytes in the spleen of T. cruzi-infected mice under treatment with benznidazole (N-benzyl-2-nitroimidazole acetamide; Bz), a drug available for clinical therapy. This finding underlies the concept that the beneficial effects of Bz on controlling acute T. cruzi infection are related to a synergistic process between intrinsic trypanocidal effect and indirect triggering of the active immune response. In the present study, we particularly investigated the effect of Bz treatment on the CD8⁺ T cell subset following T. cruzi infection. Herein we demonstrated that, during acute T. cruzi infection, Bz treatment reduces and abbreviates the parasitemia, but maintains elevated expansion of CD8⁺ T cells. Within this subset, a remarkable group of CD8^low cells was found in both Bz-treated and non-treated infected mice. In Bz-treated mice, early pathogen control paralleled the lower frequency of recently activated CD8^low cells, as ascertained by CD69 expression. However, the CD8^low subset sustains significant levels of CD44^highCD62L^low and CD62L^lowT-bet^high effector memory T cells, in both Bz-treated and non-treated infected mice. These CD8^low cells also comprise the main group of spontaneous interferon (IFN)-γ-producing CD8⁺ T cells. Interestingly, following in vitro anti-CD3/CD28 stimulation, CD8⁺ T cells from Bz-treated T. cruzi-infected mice exhibited higher frequency of IFN-γ⁺ cells, which bear mostly a CD8^low phenotype. Altogether, our results point to the marked presence of CD8^low T cells that arise during acute T. cruzi infection, with Bz treatment promoting their significant expansion along with a potential effector program for high IFN-γ production.