Interleukin 7 (IL-7) selectively promotes mouse and human IL-17�Cproducing �æ� cells

IL-17–producing CD27⁻ γδ cells (γδ²⁷⁻ cells) are widely viewed as innate immune cells that make critical contributions to host protection and autoimmunity. However, factors that promote them over IFN-γ–producing γδ²⁷⁺ cells are poorly elucidated. Moreover, although human IL-17–producing γδ cells are commonly implicated in inflammation, such cells themselves have proved difficult to isolate and characterize. Here, murine γδ²⁷⁻ T cells and thymocytes are shown to be rapidly and substantially expanded by IL-7 in vitro and in vivo. This selectivity owes in substantial part to the capacity of IL-7 to activate STAT3 in such cells. Additionally, IL-7 promotes strong responses of IL-17–producing γδ cells to TCR agonists, thus reemphasizing the cells’ adaptive and innate potentials. Moreover, human IL-17–producing γδ cells are also substantially expanded by IL-7 plus TCR agonists. Hence, IL-7 has a conserved potential to preferentially regulate IL-17–producing γδ cells, with both biological and clinical implications.     

Conversion of Th2 memory cells into Foxp3+ regulatory T cells suppressing Th2-mediated allergic asthma

Genetic and epigenetic programming of T helper (Th) cell subsets during their polarization from naive Th cells establishes long-lived memory Th cells that stably maintain their lineage signatures. However, whether memory Th cells can be redifferentiated into another Th lineage is unclear. In this study, we show that Ag-specific memory Th cells were redifferentiated into Foxp3⁺ T cells by TGF-β when stimulated in the presence of all-trans retinoic acid and rapamycin. The “converted” Foxp3⁺ T cells that were derived from Th2 memory cells down-regulated GATA-3 and IRF4 and produced little IL-4, IL-5, and IL-13. Instead, the converted Foxp3⁺ T cells suppressed the proliferation and cytokine production of Th2 memory cells. More importantly, the converted Foxp3⁺ T cells efficiently accumulated in the airways and significantly suppressed Th2 memory cell-mediated airway hyperreactivity, eosinophilia, and allergen-specific IgE production. Our findings reveal the plasticity of Th2 memory cells and provide a strategy for adoptive immunotherapy for the treatment of allergic diseases.     

Interleukin-17 plays a critical role in the acute rejection of intestinal transplantation

AIM:To investigate the role of interleukin(IL)-17 in small bowel allograft rejection.METHODS:We detected the expression of helper T cell 17(Th17)cells in biopsy specimens from 3 cases of living small bowel transplantation in our department through immunofluorescence stain.We then established a rat heterotopic small bowel transplantation model.The rats were sacrificed on the 1st,2nd,3rd,5th, and 7th d after small bowel transplantation.The degrees of transplantation rejection in rat intestine graft were examined through hematoxylin eosin(HE)stain, and the expression of Th17 cells in rat intestine graft were detected through immunofluorescence stain. In addition,the recipient rats undergoing intestinal transplantation were administrated with mouse-anti-rat IL-17 monoclonal antibody(mAb),and the survival of rats was analyzed.The recipient rats which received mouse-anti-rat IL-17 mAb treatment were sacrificed on the 1st,2nd,3rd,5th,and 7th d after small bowel transplantation.The degrees of transplantation rejection and the expression of Th17 cells in rat intestine graft were detected through HE and immunofluorescence stain. The expression of IL-17,IL-1β,tumor necroses factor receptor-α(TNF-α),IL-6,and IL-8 in the intestine graft or serum were also detected. RESULTS:The expressions of Th17 cells ran parallel with the degree of acute rejection in human intestine grafts.The intestine graft rejection of rats was aggravated with prolonged duration after intestinal transplantation,and the expressions of Th17 cells were also correlated with the degree of acute rejection in rat intestine grafts.Administration of mouse-anti-rat IL-17 mAb prolonged the survival of rats after small bowel transplantation(P<0.001).Furthermore,we found that the administration of mouse-anti-rat IL-17 mAb significantly decreased the intensity of CD4+IL-17+Th17 cells in intestine grafts on the 2nd,3rd,5th,and the 7th d (97.22±4.05vs 12.45±2.02 on the 7th d,P<0.0001), and suppressed the severity of acute rejection.The expression of IL-17 in     

Titanium dioxide induced inflammation in the small intestine

AIM: To investigate the effects of titanium dioxide (TiO₂) nanoparticles (NPTiO₂) and microparticles (MPTiO₂) on the inflammatory response in the small intestine of mice.METHODS: Bl 57/6 male mice received distilled water suspensions containing TiO₂ (100 mg/kg body weight) as NPTiO₂ (66 nm), or MPTiO₂ (260 nm) by gavage for 10 d, once a day; the control group received only distilled water. At the end of the treatment the duodenum, jejunum and ileum were extracted for assessment of cytokines, inflammatory cells and titanium content. The cytokines interleukin (IL)-1b, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-23, tumor necrosis factor-α (TNF-α), intracellular interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) were evaluated by enzyme-linked immunosorbent assay in segments of jejunum and ileum (mucosa and underlying muscular tissue). CD4⁺ and CD8⁺ T cells, natural killer cells, and dendritic cells were evaluated in duodenum, jejunum and ileum samples fixed in 10% formalin by immunohistochemistry. The titanium content was determined by inductively coupled plasma atomic emission spectrometry.RESULTS: We found increased levels of T CD4⁺ cells (cells/mm²) in duodenum: NP 1240 ± 139.4, MP 1070 ± 154.7 vs 458 ± 50.39 (P < 0.01); jejunum: NP 908.4 ± 130.3, MP 813.8 ± 103.8 vs 526.6 ± 61.43 (P < 0.05); and ileum: NP 818.60 ± 123.0, MP 640.1 ± 32.75 vs 466.9 ± 22.4 (P < 0.05). In comparison to the control group, the groups receiving TiO₂ showed a statistically significant increase in the levels of the inflammatory cytokines IL-12, IL-4, IL-23, TNF-α, IFN-γ and TGF-β. The cytokine production was more pronounced in the ileum (mean ± SE): IL-12: NP 33.98 ± 11.76, MP 74.11 ± 25.65 vs 19.06 ± 3.92 (P < 0.05); IL-4: NP 17.36 ± 9.96, MP 22.94 ± 7.47 vs 2.19 ± 0.65 (P < 0.05); IL-23: NP 157.20 ± 75.80, MP 134.50 ± 38.31 vs 22.34 ± 5.81 (P < 0.05); TNFα: NP 3.71 ± 1.33, MP 5.44 ± 1.67 vs 0.99 ± 019 (P < 0.05); IFNγ: NP 15.85 ± 9.99, MP 34.08 ± 11.44 vs 2.81 ± 0.69 (P < 0.05); and TGF-β: NP 780.70 ± 318.50, MP 1409.00 ± 502.20 vs 205.50 ± 63.93 (P < 0.05).CONCLUSION: Our findings indicate that TiO₂ particles induce a Th1-mediated inflammatory response in the small bowel in mice.     

Programmed death 1 ligand signaling regulates the generation of adaptive Foxp3+CD4+ regulatory T cells

Although mature dendritic cells (DCs) are potent initiators of adaptive immune response, immature steady-state DCs contribute to immune tolerance. In this study, we show that ex vivo splenic DCs are capable of inducing conversion of naïve CD4⁺ T cells to adaptive Foxp3⁺CD4⁺ regulatory T cells (aTreg) in the presence of TGF-β. In particular, when compared with splenic CD8α⁻ DCs, the CD8α⁺ DC subset were superior in inducing higher frequencies of conversion. This was not attributable to the difference in basal level of costimulation, because deficiency of CD40 or CD80/86 signaling did not diminish the differential induction of Foxp3. Conversion was regulated by DC maturation status. Further insights into the molecular mechanisms of conversion were gained by analyzing the contribution of several costimulatory and coinhibitory receptors. Costimulatory signals through GITR suppressed conversion, whereas coinhibitory signaling via programmed death 1 ligand (PD-L1) but not PD-L2 was required for conversion. Ex vivo PD-L1^−/− DCs failed to support Foxp3 induction in the presence of TGF-β. In vivo blocking PD-L1 signaling abolished conversion in a tumor-induced aTreg conversion model. Collectively, this study highlights the cellular and molecular parameters that might be exploited to control the de novo generation of aTregs and peripheral tolerance.     

MyD88 is essential to sustain mTOR activation necessary to promote T helper 17 cell proliferation by linking IL-1 and IL-23 signaling

Myeloid differentiation primary response protein 88 (MyD88) is classically known as an adaptor, linking TLR and IL-1R to downstream signaling pathways in the innate immune system. In addition to its role in innate immune cells, MyD88 has been shown to play an important role in T cells. How MyD88 regulates helper T-cell differentiation remains largely unknown, however. Here we demonstrate that MyD88 is an important regulator of IL-17-producing CD4⁺ T helper cells (Th17) cell proliferation. MyD88-deficient CD4⁺ T cells showed a defect in Th17 cell differentiation, but not in Th1 cell or Th2 cell differentiation. The impaired IL-17 production from MyD88-deficient CD4⁺ T cells is not a result of defective RAR-related orphan receptor γt (RORγt) expression. Instead, MyD88 is essential for sustaining the mammalian target of rapamycin (mTOR) activation necessary to promote Th17 cell proliferation by linking IL-1 and IL-23 signaling. MyD88-deficient CD4⁺ T cells showed impaired mTOR activation and, consequently, reduced Th17 cell proliferation. Importantly, the absence of MyD88 in T cells ameliorated disease in the experimental autoimmune encephalomyelitis model. Taken together, our results demonstrate that MyD88 has a dual function in Th17 cells by delivering IL-1 signaling during the early differentiation stage and integrating IL-23 signaling to the mTOR complex to expand committed Th17 cells.Myeloid differentiation primary response protein 88 (MyD88) was originally isolated as a cloned cDNA that was induced in M1 myeloblastic leukemia cells on activation with IL-6 (1). The function of MyD88 was then uncovered, because the C-terminal portion of MyD88 was found to be similar to the Drosophila Toll receptor and the mammalian IL-1 receptor (IL-1R) (2). This conserved region in the cytoplasmic tails of IL-1R and Toll-like receptor (TLR) is referred to as the Toll/IL-1R (TIR) domain. MyD88 is now known to play an essential role in the innate immune response by linking members of the TLR and IL-1R superfamily to the downstream activation of NF-κB and MAPKs (3).Among cytokines produced by activated innate immune cells, IL-23 has been shown to promote production of the proinflammatory cytokine IL-17 in activated T cells (4). IL-17–producing CD4⁺ T helper (Th17) cells were identified after the discovery that IL-23 is linked to traditionally Th1-associated autoimmune disorders, such as experimental autoimmune encephalitis (EAE). Il23a^−/− mice, but not Il12a^−/− mice, were shown to be autoimmune-resistant (5). IL-23 is required for Th17 cell-mediated autoimmune disorders in vivo, but the role of IL-23 in Th17 cell differentiation remains controversial (6). Previous studies support the idea that IL-23 helps expand or maintain Th17 cells (7–9). In addition, a recent study reemphasized the importance of IL-23 in the generation of pathogenic Th17 cells, showing that they can be generated with IL-23, IL-6, and IL-1β (10).In addition to IL-23, other cytokines, including TGF-β, IL-6, and IL-1, play roles in Th17 cell development. TGF-β with proinflammatory cytokines was shown to be critical in the support of Th17 cell differentiation (8, 11, 12). In particular, an inflammatory cytokine, IL-6, favors Th17 cell development by inhibiting regulatory T cells (13). The role of IL-1 in Th17 cell differentiation has been investigated as well. IL-1 receptor type 1-deficient (Il1r1^−/−) mice showed a lower incidence of EAE and severe defects in the induction of IL-17–producing T cells (14). IL-1 signaling in T cells was further shown to be involved in early Th17 cell differentiation by regulating IFN regulatory factor 4 and RAR-related orphan receptor γt (RORγt) (15).Although roles for MyD88 in the innate immune system are well established, little is known about their potential function in the adaptive immune system. Several studies have demonstrated important roles of MyD88 in T cells. For instance, T-cell expression of MyD88 is required for resistance to Toxoplasma gondii (16); the MyD88-dependent signaling pathway in CD4⁺ T cells has been shown to enhance proliferation and augment humoral immune responses (17); and MyD88 is required for T-cell effector function in the development of inflammatory bowel disease (18). Interestingly, although Myd88^−/− T cells were found to exhibit decreased IL-17 production (18), how T-cell differentiation could be regulated by MyD88 was not clear in that study.Here we investigated the molecular mechanism by which MyD88 regulates CD4⁺ T-cell differentiation. Our results demonstrate that MyD88 contributes to Th17 cell differentiation, but not to Th1 or Th2 cell differentiation. Both IL-1 and IL-23 signaling depend on MyD88 and result in up-regulation of IL-23R. MyD88-deficient Th17 cells show reduced IL-23R expression and mTOR activation, leading to impaired Th17 cell proliferation. Furthermore, MyD88 is crucial for proper Th17 cell differentiation in vivo. Thus, our findings reveal a unique role for the innate adaptor MyD88 in the regulation of Th17 cell differentiation.     

Correlations between skin lesions induced by anti-tumor necrosis factor-α and selected cytokines in Crohn’s disease patients

AIM:To investigate the correlation between the appearance of skin lesions and concentration of interleukin(IL)-17A,IL-23 and interferon-γ(IFN-γ)in Crohn’s disease(CD)patients during anti-tumor necrosis factor-α(TNF-α)therapy METHODS:A prospective study included 30 adult patients with CD of Caucasian origin(19 men and 11women;mean age±SD 32.0±8.6 years)during biological therapy with anti-TNF-αantibodies from January2012 to March 2013.Eighteen patients were treated with infliximab,seven with adalimumab and five withcertolizumab.Inclusion criteria were exacerbation of the underlying disease,Crohn’s Disease Activity Index over 300 and the ineffectiveness of previously used non-biological therapies.Patients with a history of psoriasis,atopic dermatitis and other autoimmune skin lesions were excluded from the study.The control group consisted of 12 healthy subjects.A diagnostic survey was carried out,blood tests and careful skin examination were performed,and the serum levels of IL-17,IL-23 and IFN-γwere measured using an enzyme-linked immunosorbent assays technique.Dermatoses that have developed in the course of biological therapy in patients who had no pre-existing skin lesions of similar character were qualified as skin lesions induced by antiTNF-αtherapy.RESULTS:Skin manifestations occurred in 18 of CD patients during the anti-TNF-αtherapy(60%),in the average time of 10.16±3.42 mo following the beginning of the 52-wk treatment cycle.Skin lesions observed in CD patients during biological therapy included psoriasiform lesions(44.4%),and eczema forms lesions(22.2%).In CD patients with drug induced skin lesions significantly higher levels of hemoglobin(13.3±1.5 g/dL vs 10.8±1.9 g/dL,P=0.018)and hematocrit(39.9%±4.5%vs 34.3%±5.4%,P=0.01),as well as a significantly lower level of platelets(268±62×103/μL vs 408±239×103/μL,P=0.046)was observed compared with CD patients without skin manifestations.The concentrations of IL-17A and IL-23in CD patients with skin lesions developed under antiTNF-αtherapy were significantly higher compared to those in patients without lesions(IL-17A:39.01±7.03pg/mL vs 25.71±4.90 pg/mL,P=0.00004;IL-23:408.78±94.13 pg/mL vs 312.15±76.24 pg/mL,P=0.00556).CONCLUSION:Skin lesions in CD patients during bio-logical therapy may result from significantly increased concentrations of IL-17A and IL-23,which are strongly associated with TNF-α/Th1 immune pathways.     

Generation and regulation of human CD4+ IL-17-producing T cells in ovarian cancer

Despite the important role of Th17 cells in the pathogenesis of many autoimmune diseases, their prevalence and the mechanisms by which they are generated and regulated in cancer remain unclear. Here, we report the presence of a high percentage of CD4⁺ Th17 cells at sites of ovarian cancer, compared with a low percentage of Th17 cells in peripheral blood mononuclear cells from healthy donors and cancer patients. Analysis of cytokine production profiles revealed that ovarian tumor cells, tumor-derived fibroblasts, and antigen-presenting cells (APCs) secreted several key cytokines including IL-1β, IL-6, TNF-α and TGF-β, which formed a cytokine milieu that regulated and expanded human IL-17-producing T-helper (Th17) cells. We further show that IL-1β was critically required for the differentiation and expansion of human Th17 cells, whereas IL-6 and IL-23 may also play a role in the expansion of memory Th17 cells, even though IL-23 levels are low or undetectable in ovarian cancer. Further experiments demonstrated that coculture of naïve or memory CD4⁺ T cells with tumor cells, APCs, or both could generate high percentages of Th17 cells. Treatment with anti-IL-1 alone or a combination of anti-IL-1 and anti-IL-6 reduced the ability of tumor cells to expand memory Th17 cells. Thus, we have identified a set of key cytokines secreted by ovarian tumor cells and tumor-associated APCs that favor the generation and expansion of human Th17 cells. These findings should accelerate efforts to define the function of this important subset of CD4⁺ T cells in the human immune response to cancer.