The inflammatory Th 17 subset in immunity against self and non-self antigens

Zinc finger protein 189 promotes the differentiation of lamina propria T helper 17.1 cells in dextran sulfate sodium-induced colitis

The factors regulating the heterogeneity of interleukin-17A (IL-17A)-expressing CD4⁺ T cells in inflammatory bowel diseases remain unclear. In the current study, we characterised the expression and function of zinc finger protein 189 (ZFP189) in a murine colitis model. Mice were given dextran sulphate sodium to induce acute colitis. Flow cytometry was applied to recognise and enrich Th17 and Th17.1 cells based on the expression of IL-17A, interferon-γ (IFN-γ), C-X-C motif chemokine receptor 3 (CXCR3), and C-C motif chemokine receptor 4 (CCR4). The expression of ZFP189 in Th17 and Th17.1 cells was determined by Immunoblotting. Lentivirus-mediated ZFP189 knockdown was conducted to evaluate the effect of ZFP189 on the differentiation of Th17 and Th17.1 cells. The adoptive transfer was performed to analyse the pathogenicity of Th17.1 cells in vivo. We found that ZFP189 was mildly up-regulated in IL-17A-expressing CD4⁺ T cells in colonic lamina propria. Lamina propria Th17.1 cells expressed higher ZFP189 than Th17 cells. In vitro ZFP189 knockdown in CD4⁺ T cells did not impact Th17 cell differentiation but suppressed Th17.1 cell differentiation, as evidenced by lower T-box expressed in T cells (T-bet) and IFN-γ. When adoptively transferred into mice, ZFP189-deficient Th17.1 cells produced fewer IFN-γ, tumour necrosis factor-alpha (TNF-α), and granulocyte-macrophage colony-stimulating factor (GM-CSF) than ZFP189-expressing Th17.1 cells. Moreover, ZFP189-deficient Th17.1 cells induced less severe colitis than ZFP189-expressing Th17.1 cells, as evidenced by less body weight loss, a lower disease activity index, and a lower colon histological score. In summary, ZFP189 acts as a positive regulator of the differentiation and pathogenicity of lamina propria Th17.1 cells in colitis.

The association of Treg and Th17 cells development factors and anti-TPO autoantibodies in patients with recurrent pregnancy loss

OBJECTIVES

Thyroid autoimmunity is considered as the most prevalent autoimmune condition in women in fertility age. There are different clinical evidences indicating the association between thyroid autoimmunity and increased risk of RPL. This study aimed to analyze the association of Tregs and Th17 cells development factors and anti-thyroid peroxidase (anti-TPO) antibodies in RPL patients. Healthy controls (n = 36), TPO + controls (n = 25) and TPO + RPL (n = 32) participated in this study. After blood sampling, the frequency of Th17 and Tregs was evaluated using flow cytometry. Real-time PCR and ELISA was used to assess the status of Tregs and Th17 related transcription factors and cytokines in mRNA and protein level, respectively.

RESULTS

TPO + RPL group showed a higher Th17 frequency compared to healthy controls and TPO + controls groups (p = 0.0002 and p = 0.04, respectively). Additionally, mRNA expression levels of RORγT and IL-17 were significantly higher in TPO + RPL compared to healthy controls and TPO + controls groups. In contrast, Foxp3 and TGFβ expression was lower in TPO + RPL. ELISA findings also indicated a significantly higher IL-17 and lower TGFβ secretion in TPO + RPL compared to healthy controls and TPO + controls. Thyroid autoimmunity should intensely be controlled specially in patients with RPL history.

Gene expression of Toll-like receptors, cytokines and a nuclear factor and cytokine secretion in DH82 canine macrophage cells infected with Brucella canis

Canine brucellosis caused by Brucella canis infection occurs mainly in dogs, and is a zoonotic disease that also has the possibility of infection in humans. Many studies have been conducted to understand the immunopathological mechanism of B. canis infection. However, the precise immune mechanism remains to be elucidated because compared to other Brucella spp., B. canis has different immune evasion mechanisms. In this study, gene expression levels of Toll-like receptors (TLRs) and TLR-associated molecules and cytokine production were analyzed to figure out the roles of immune-related host factors in B. canis infection. Time-dependent gene expression of TLRs (1-10) and TLR-related molecules (TNF-α, IL-5, IL-23, CCL4, CD40 and NFκ-B) and release of Th1, Th2 and Th17-related cytokines (IFN-γ, IL-1β, IL-4, IL-6, IL-10 and IL-17A) were investigated in DH82 canine macrophages infected with B. canis. Time-dependent induction of TLRs 3, 7 and 8 was observed, and TLR 7 had the highest expression level (p <0.05). The expression levels of all TLR-related genes were significantly increased after infection. In particular, the expression of the CCL4 and IL-23 genes was highly induced. The amounts of IL-1β, IL-6 and IL-10 were significantly increased by B. canis infection, but the amounts of IL-4 and IL-17A were not. The production of IL-1β and IL-6 was the highest at 24 hr after B. canis infection (p <0.05). This study demonstrates that TLRs 3, 7 and 8 are prominent sites of to immune response induction with the production of related cytokines and a nuclear factor in DH82 cells infected with B. canis. These results suggest a sequential immune mechanism of B. canis infection, involving TLRs, cytokines and their associated factors.

IL-17 and related cytokines involved in systemic sclerosis: Perspectives

Systemic sclerosis (SSc) is a multisystemic, complex, and rare disease of connective tissue, with high morbidity and mortality, and without specific treatment. The disease is characterized by three main principles: vascular disease, autoantibody production and inflammation, and fibrosis. Since it is well defined that SSc is characterized by elevated production of TGF-β, IL-6, and IL-1, all of them cytokines related to Th17 differentiation, the hypothesis is that this disease may be strongly related to a polarization of the immune response towards the Th17 pathway. Considering the importance of a better understanding of the pathophysiology of Th17 pathway in SSc, this article aims to propose an update for a better understanding of current knowledge on main cytokines secreted by the Th17 cells (IL-17 A, IL-21, and IL-22) and the future prospects in the current disease.

Serum interleukin-17 in Egyptian children with systemic lupus erythematosus: is it related to pulmonary affection?

Objective Pulmonary involvement in paediatric systemic lupus erythematosus (pSLE) is not an uncommon finding; however, subclinical affection occurs more frequently. Many studies have reported that cytokine dysregulation as interleukin-17 (IL-17) over-expression plays a key role in the pathogenesis of systemic lupus erythematosus (SLE). We aim to assess serum levels of IL-17 A and their association with pulmonary involvement in children with SLE. Methods Serum IL-17A levels - determined by solid phase sandwich ELISA - were assessed in forty-two pSLE patients and compared to 45 age-matched healthy controls. All patients were subjected to pulmonary function tests to detect subclinical pulmonary affection. High-resolution CT (HRCT) chest scan was carried out in patients with abnormal pulmonary function tests (PFTs) and those with chronic respiratory symptoms. Results Abnormal PFTs were found in 73% of patients; of them, only 25% had abnormal findings in HRCT chest. Serum levels of IL-17 A were significantly elevated in pSLE patients as compared to healthy controls ( p < 0.001). The serum levels of IL-17 A had a highly significant positive correlation with SLEDAI ( r = 0.811 and p < 0.001) Strong negative correlation was found between serum levels of IL-17A with both FEV1 and FVC ( p < 0.05). Conclusions Serum IL-17A is elevated in pSLE patients, which correlates with disease activity. IL-17 seems to have a possible role in the pathogenesis of subclinical lung affection. Abnormal PFTS may be found in pSLE patients even with normal radiology.

Early IFN-γ production together with decreased expression of TLR3 and TLR9 characterizes EAE development conditional on the presence of myelin

Experimental autoimmune encephalomyelitis (EAE) is a model for the study of multiple sclerosis, which is an inflammatory and demyelinating disease of the central nervous system (CNS). Despite increased efforts to elucidate the function of toll-like receptors (TLRs) in autoimmune diseases of the CNS, the relative contribution of other factors, including the immunomodulatory properties of TLR signaling, role of the innate response and the presence or absence of myelin peptides remain unclear. The aim was to evaluate TLR expression in the CNS during EAE development by investigating the expression of TLRs in the initial phase of EAE and establishing correlations with the modulation of inflammatory factors. Mice were subcutaneously immunized at the tail base with 100 μg of myelin oligodendrocyte glycoprotein peptide (MOG35-55), emulsified in complete Freund's adjuvant (CFA) supplemented with 400 μg of attenuated Mycobacterium tuberculosis H37RA. Pertussis toxin (300 ng per animal) was intraperitoneally injected on the day of immunization and 48 h later. Another group (MOG(-)) received an equal emulsion of CFA and M. tuberculosis, without MOG35-55, and the same protocol of Pertussis toxin. The immunized mice presented signs of disease with increased IFN-γ production and presence of NK cells on Day 2 postimmunization and reduced the expression of TLR-3 and TLR-9. In the spinal cord, CCL5 and CCL20 were higher in EAE. This study establishes a correlation between TLR-3 and TLR-9 expression with the development of EAE. In addition, evidence of a role for the myelin peptide in targeting the innate inflammatory response to the CNS is presented.

In vivo analysis of helper T cell responses in patients with autoimmune polyendocrinopathy - candidiasis - ectodermal dystrophy provides evidence in support of an IL-22 defect

Autoimmune polyendocrinopathy - candidiasis - ectodermal dystrophy (APECED) is caused by mutations in the Autoimmune regulator (AIRE) gene and is associated with neutralizing anti-cytokine autoantibodies. We have used an in vivo challenge model to analyze antigen-specific CD4(+) T cell responses. Bacille Calmette-Guérin (BCG)-vaccinated patients and controls were injected tuberculin intradermally, skin blisters were induced by suction on the indurations and on unexposed skin, and the infiltrating cells harvested. The patients had a quantitatively normal CD4(+) T cell response and no significant abnormalities in the expression of T helper type (Th) 1- or Th2-related genes. The expression of interleukin (IL)-22, in contrast, was lower in the patients. Two patients, both with a pre-existing ocular keratopathy, experienced a relapse of keratoconjunctivitis, suggesting a possible immunological basis for this APECED component. Our in vivo data are compatible with a selective IL-22 defect in the activated CD4(+) T cells of APECED patients, affecting also unexposed skin in steady-state conditions.

Alteration of Th17 and Treg cells in patients with unexplained recurrent spontaneous abortion before and after lymphocyte immunization therapy

BACKGROUND

Several types of T cells have been associated with the pathogenesis of unexplained recurrent spontaneous abortion (URSA), including Th1/Th2/Th17/Tregs cell. It has been appreciated that immunotherapy with paternal or third party lymphocytes is an effective method of treatment for URSA patients. The balance of Th1/Th2 cells could be maintained and an increase of Treg cells would be beneficial after immunotherapy; however, the mechanism by which the Th17/Treg balance affects URSA has not yet been fully elucidated.

METHODS

Here, we used flow cytometry, liquid chip technology and quantitative real-time PCR (qPCR) methods to characterize Th17/Treg cell populations after immunotherapy. We found that after immunotherapy in URSA patients, the percentage of Th17 cells decreased and the percentage of Treg cells in peripheral blood mononuclear cells (PBMC) increased, as detected by flow cytometry.

RESULTS

Immunotherapy may induce a decrease in the Th17/Treg ratio and the Treg bias, which may be beneficial for the maintenance of pregnancy. The expression level of ROR gamma t, a transcription factor found in Th17 cells, decreased and the expression of the Treg-specific transcription factor Foxp3 increased in peripheral blood as detected by qPCR. Immunotherapy may induce a decrease in the ratio of ROR gamma t to Foxp3 and a Treg cell bias, which would be beneficial for pregnancy maintenance. The secretion of the Treg-associated cytokine TGF-beta, as well as Th2 cytokines, was increased in serum, while the secretion of Th17-associated cytokine IL-17A and Th1 cytokine production was decreased. The Th1/Th2 cytokine ratio significantly decreased. Similarly, the Th17/Treg ratio significantly decreased in the total patient after immunotherapy.

CONCLUSIONS

These results indicate that in patients with URSA, immunotherapy with mononuclear cells derived from the baby's father could affect both Th1/Th2 and Th17/Treg balance, and we found that the Th2 and Treg bias would be beneficial for pregnancy, which may lead to a balancing of the Th17/Treg ratio in URSA patients after immunotherapy.

TH17 cells are increased in the peripheral blood of patients with SAPHO syndrome

To assess whether the immune derangement previously observed in SAPHO syndrome could be linked to variations in blood TH1, TH2 or TH17 lymphocytes frequency. Seven SAPHO patients with a protracted course of the disease were studied ex-vivo for intracellular cytokines production by means of flow-cytometry and compared with matched groups of Psoriatic Arthritis patients and healthy controls. The Kruskal-Wallis test on the median of the three categories showed that there is a significant association between the TH17 levels and the category (p value = 0.02474). The mean and variance for the proportion of IL-17 producing CD4+ cells were compared between groups showing significant differences between SAPHO versus PsA subgroup (p = 0.05) and SAPHO versus healthy controls (p = 0.008). Interestingly, activation of TH17 axis, but not of TH1 and TH2, has been found, and can be observed both in patients with different activity of the disease or treated with different drugs. The TH17 increase in peripheral blood of our SAPHO subjects resembles the one recently found in patients with different AIDs. Novel therapeutic options in these patients may therefore include IL-17 blockade.

Combination with methotrexate and cyclophosphamide attenuated maturation of dendritic cells: inducing Treg skewing and Th17 suppression in vivo

Immune disorder is considered the main pathogenesis of autoimmune diseases, such as rheumatoid arthritis (RA). The balance of the two special subsets of CD4⁺T cells, T helper cell 17 (Th17), and Regulator T cell (Treg) is the key factor of maintaining a normal immune response. Dendritic cells (DCs), which are the most powerful antigen-presenting cells, play an important role in regulating the balance of Th17 and Treg. The combination of disease modifying antirheumatic drugs (DMARDs) is an important strategy of RA therapy. In this study, we investigated the effect of MTX and CTX on DC maturation in ovalbumin (OVA) immunized mice. Th17 inflammatory response is stronger, while the level of DCs maturity is higher. In contrast, the immunosuppression of Treg is stronger. We found that MTX combined with CTX significantly inhibited the DCs maturity and downregulated the antigen presenting capacity of DCs. As a result, it reestablished a balance of Th17 and Treg. Our study adds a novel mechanism and therapeutic target of MTX combined with CTX for autoimmune disease treatment.

Mitochondrial damage-associated molecular patterns activate γδ T-cells

Gamma delta T-cells have been shown to be important in the early immunoinflammatory response to injury, which can be independent of infection. This sterile inflammatory response is believed to be, in part, associated with danger-associated molecular patterns (DAMPs). Mitochondrial DAMPs (MTDs) have been shown to be important in trauma-induced neutrophil activation, but it is unknown whether MTDs activate other innate immune cells, such as γδ T-cells. To study this, splenic CD3(+) γδ T-cells were isolated from αβ T-cell-deficient C57BL/6 mice and mitochondria isolated from wild type mouse livers. MTDs were isolated from mitochondria by sonication and centrifugation. Gamma delta T-cells were incubated with various concentrations of MTDs (0-500 µg/ml) for 24 h. T-cells were phenotyped for TLR expression by flow cytometry and the supernatants assayed for cytokine and growth factor content. MTDs caused a dose-dependent increase in TLR2 and TLR4 expression by γδ T-cells. Both the percentage of cells positive for TLRs and the degree of expression increased. MTDs also induced the production of IL-1β, IL-6, IL-10, RANTES, fibroblast growth factor-basic and vascular endothelial growth factor by γδ T-cells. These findings support the concept that the MTDs released after tissue/cellular injury are capable of activating γδ T-cells, thus initiating sterile inflammation, as well as subsequent healing processes.

Tregs: application for solid-organ transplantation

PURPOSE OF REVIEW

Transfer of human regulatory T cells (Tregs) has become an attractive therapeutic alternative to improve the long-term outcome in transplantation and thus reduce the side-effects of conventional immunosuppressive drugs. Here, we summarize the recent findings on human Treg subsets, their phenotype and in-vivo function.

RECENT FINDINGS

In the last 2 years, it has become apparent that several Treg subsets exist that specifically regulate Th1-driven, Th2-driven, or Th17-driven immune responses; these subsets are very unstable and rapidly change their phenotype, for example, there is loss of Foxp3 expression upon extensive ex-vivo expansion and only the administration of rapamycin has been shown to be able to interfere reproducibly. New humanized mouse models incorporating human solid-organ grafts have been developed, which have been used to test the human Treg in-vivo function, and the first human Treg-cell products have been tested for safety and efficacy in stem cell transplantation.

SUMMARY

With the recent findings, we have gained a better understanding of Treg heterogeneity, plasticity and function. Using the outcomes of clinical trials in stem cell transplantation, we have learned that adoptive therapy of Tregs is well tolerated and we are now awaiting the first result in solid-organ transplantation from the 'ONE Study'.

Interleukin-17 enhanced immunoinflammatory lesions in a mouse model of recurrent herpetic keratitis

Interleukin-17 (IL-17), mainly produced by activated (memory) T cells, has been found in the corneas from herpetic stromal keratitis (HSK) patients. To better understand the role of IL-17 and to optimize fidelity to human recurrent HSK, in this study, we utilized a mouse model of recurrent HSK, examined the expression of IL-17 and Th17 cells, and determine the alterability of virus-induced corneal inflammation after anti-IL-17 antibody treatment during murine recurrent HSK. We found that Th17 cells were obviously up-regulated in both cornea and DLNs of recurrent mice. Peak IL-17 protein present in recurrent cornea in conjunction with peak opacity mediated by CD4(+) T cells. Systemic administration of anti-IL-17 antibody resulted in a diminished severity of corneal opacity, neovascularization, and CD4(+) T cells infiltration compared to control. Anti-IL-17 treatment down-regulated the mRNA and protein levels of TNF-α expression in recurrent corneas, and decreased HSV-specific DTH responses. Our results indicate that elevated IL-17 expression may be involved in the development of recurrent HSK. The likely mechanisms of action for IL-17 are through up-regulating TNF-α expression and promoting HSV-specific DTH responses. Thus, IL-17 might constitute a useful target for therapeutic intervention in recurrent HSK.

Critical role of proinflammatory cytokine IL-6 in allograft rejection and tolerance

The proinflammatory cytokine IL-6 plays an important role in controlling T-cell differentiation, especially the development of Th17 and regulatory T cells. To determine the function of IL-6 in regulating allograft rejection and tolerance, BALB/c cardiac grafts were transplanted into wild-type or IL-6-deficient C57BL/6 mice. We observed that production of IL-6 and IFN-γ was upregulated during allograft rejection in untreated wild-type mice. In IL-6-deficient mice, IFN-γ production was greater than that observed in wild-type controls, suggesting that IL-6 production affects Th1/Th2 balance during allograft rejection. CD28-B7 blockade by CTLA4-Ig inhibited IFN-γ production in C57BL/6 recipients, but had no effect on the production of IL-6. Although wild-type C57BL/6 recipients treated with CTLA4-Ig rejected fully MHC-mismatched BALB/c heart transplants, treatment of IL-6-deficient mice with CTLA4-Ig resulted in graft acceptance. Allograft acceptance appeared to result from the combined effect of costimulatory molecule blockade and IL-6-deficiency, which limited the differentiation of effector cells and promoted the migration of regulatory T cells into the grafts. These data suggest that the blockade of IL-6, or its signaling pathway, when combined with strategies that inhibit Th1 responses, has a synergistic effect on the promotion of allograft acceptance. Thus, targeting the effects of IL-6 production may represent an important part of costimulation blockade-based strategies to promote allograft acceptance and tolerance.

Melatonin synthesized by T lymphocytes as a ligand of the retinoic acid-related orphan receptor

Melatonin modulates a wide array of physiological events with pleiotropic effects on the immune system. While the relevance of specific melatonin membrane receptors has been well established for several biological functions, retinoic acid-related orphan receptor alpha (RORα) has been suggested as a mediator of nuclear melatonin signalling by results obtained from pharmacological approaches. However, a melatonin-mediated downstream effect cannot be ruled out, and further evidence is needed to support a direct interaction between melatonin and RORα. Here, we show that RORα is mainly located in human Jurkat T-cell nucleus, and it is co-immunoprecipitated with melatonin. Moreover, immunocytochemistry studies confirmed the co-localization of melatonin and RORα. Melatonin promoted a time-dependent decrease in nuclear RORα levels, suggesting a role in the RORα transcriptional activity. Interestingly, RORα acts as a molecular switch implicated in the mutually exclusive generation of Th17 and Treg cells, both involved in the harm/protection balance of immune conditions such as autoimmunity or acute transplant rejection. Therefore, the identification of melatonin as a natural modulator of RORα gives it a tremendous therapeutic potential for a variety of clinical disorders.

Collagen induced arthritis increases secondary metastasis in MMTV-PyV MT mouse model of mammary cancer

Background

Several studies have demonstrated that sites of chronic inflammation are often associated with the establishment and growth of various malignancies. A common inflammatory condition in humans is autoimmune arthritis (AA). Although AA and cancer are different diseases, many of the underlying processes that contribute to the disorders of the joints and connective tissue that characterize AA also affect cancer progression and metastasis. Systemically, AA can lead to cellular infiltration and inflammation of the lungs. Several studies have reported statistically significant risk ratios between AA and breast cancer. Despite this knowledge being available, there has been minimal research linking breast cancer, arthritis, and metastasis associated with breast cancer. Notably both diseases are extremely prevalent in older post-menopausal women.

Methods

To establish the novel link between arthritis induced inflammation and secondary metastasis associated with breast cancer, PyV MT mice that spontaneously develop mammary gland carcinoma were injected with Type II collagen (CII) to induce arthritis at 9 and 18 weeks of age for pre-metastatic and metastatic condition. The sites of secondary metastasis and the associated inflammatory microenvironment were evaluated.

Results

A significant increase in breast cancer-associated secondary metastasis to the lungs and bones was observed in the arthritic versus the non-arthritic PyV MT mice along with an increase in primary tumor burden. We report significant increases in the levels of interstitial cellular infiltrates and pro-inflammatory cytokines such as interleukin-17 (IL-17), interleukin-6 (IL-6), Pro- Matrix metallopeptidase 9 (Pro-MMP9), insulin like growth factor-II (GF-II) and macrophage colony stimulating factor (M-CSF) in the arthritic lung and bone milieu as well as in the circulation. These pro-inflammatory cytokines along with the inflammatory microenvironment may be the underlying factors facilitating tumor progression and metastasis in arthritic PyV MT mice. This was further substantiated by treatment with celecoxib, an anti-inflammatory drug + αIL-17 antibody that significantly reduced the secondary metastasis to lung and bone.

Conclusions

The data generated not only reveal the underlying mechanism of high susceptibility to bone and lung metastasis in an arthritic condition but our combination therapies may lead to treatment modalities that will be capable of reducing tumor burden, and preventing relapse and metastasis in arthritic patients with breast cancer.

ANCA-associated vasculitides--advances in pathogenesis and treatment

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) include Wegener granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome and renal-limited vasculitis. This Review highlights the progress that has been made in our understanding of AAV pathogenesis and discusses new developments in the treatment of these diseases. Evidence from clinical studies, and both in vitro and in vivo experiments, supports a pathogenic role for ANCAs in the development of AAV; evidence is stronger for myeloperoxidase-ANCAs than for proteinase-3-ANCAs. Neutrophils, complement and effector T cells are also involved in AAV pathogenesis. With respect to treatment of AAV, glucocorticoids, cyclophosphamide and other conventional therapies are commonly used to induce remission in generalized disease. Pulse intravenous cyclophosphamide is equivalent in efficacy to oral cyclophosphamide but seems to be associated with less adverse effects. Nevertheless, alternatives to cyclophosphamide therapy have been investigated, such as the use of methotrexate as a less-toxic alternative to cyclophosphamide to induce remission in non-organ-threatening or non-life-threatening AAV. Furthermore, rituximab is equally as effective as cyclophosphamide for induction of remission in AAV and might become the standard of therapy in the near future. Controlled trials in which specific immune effector cells and molecules are being therapeutically targeted have been initiated or are currently being planned.

Regulation of IL-17 expression by the developmental pathway of CD4 T cells in the thymus

CD4 T cells selected by MHC class II expressing thymocytes (T-CD4 T cells) have distinct effector functions compared to that of epithelial cell-selected CD4 T cells (E-CD4 T cells). T-CD4 T cells produce both Th1 and Th2 effector cytokines immediately after stimulation and also express IL-4 in addition to IFN-gamma under the Th1 differentiation condition. In the present study, we investigated the capability of T-CD4 T cells to become IL-17-producing cells. We found that T-CD4 T cells express reduced IL-17 under Th17-inducing conditions. T-CD4 T cells express very low levels of receptor for TGF-beta and IL-21 that are essential to induce IL-17 expression. In addition, the induction of RORgammat, a key transcription factor for IL-17 gene expression, was compromised in T-CD4 T cells under Th17 skewing conditions and ectopic expression of RORgammat restored IL-17 expression. The defect of IL-17 and RORgammat expression in T-CD4 T cells is cell intrinsic and not due to effects of a secreted factor. Thus, the developmental pathway of CD4 T cells in the thymus plays a critical role in controlling an immune response by suppressing the generation of the Th17 lineage.

T-cell activation promotes tumorigenesis in inflammation-associated cancer

Chronic inflammation has long been associated with a wide range of malignancies, is now widely accepted as a risk factor for development of cancer, and has been implicated as a promoter of a variety of cancers including hematopoietic malignancies. We have described a mouse model uniquely suited to examine the link between inflammation and lymphoma in which the Tax oncogene, expressed in activated T and NK cells, perpetuates chronic inflammation that begins as microscopic intraepithelial lesions and develops into inflammatory nodules, subcutaneous tumors, and large granular lymphocytic leukemia. The use of bioluminescent imaging in these mice has expanded our ability to interrogate aspects of inflammation and tumorigenesis non-invasively. Here we demonstrate that bioluminescence induction in these mice correlated with inflammation resulting from wounding, T cell activation, and exposure to chemical agents. In experiments in which long-term effects of inflammation on disease outcome were monitored, the development of lymphoma was promoted by an inflammatory stimulus. Finally we demonstrated that activation of T-cells in T-cell receptor (TCR) transgenic TAX-LUC animals dramatically exacerbated the development of subcutaneous TCR^- CD16⁺ LGL tumors. The role of activated T-cells and acquired immunity in inflammation-associated cancers is broadly applicable to hematopoietic malignancies, and we propose these mice will be of use in dissecting mechanisms by which activated T-cells promote lymphomagenesis in vivo.

Can antigen-specific regulatory T cells protect against graft versus host disease and spare anti-malignancy alloresponse?

Allogeneic hematopoietic cell transplantation provides effective control of hematopoietic malignancies, but with an associated risk of graft-versus-host disease (GVHD) related morbidity and mortality. Several advances in hematopoietic cell transplantation including high resolution HLA typing, development of reduced intensity conditioning regimens, infectious prophylaxis and treatment, and novel immunosuppressive agents have resulted in improved outcomes and improved access to transplantation, but GVHD remains a major obstacle. This clinico-pathological syndrome, mediated by donor alloreactive T cells, occurs often despite prophylactic immunosuppressive therapy. Regulatory T cells, a suppressive subset of the T-cell repertoire, may offer promise as a novel cellular therapy for more effective prevention of GVHD. While advances have been made in pre-clinical experimental animals, several challenges remain in the translation of this work to human trials. Strategies to effectively produce ex vivo expanded alloantigen-specific regulatory T cells specific for ubiquitous alloantigens but sparing hematopoietic- or tumor-associated antigens hold promise to prevent GVHD while allowing a preserved graft versus malignancy effect.

The pleiotropy of dioxin toxicity--xenobiotic misappropriation of the aryl hydrocarbon receptor's alternative physiological roles

The aryl hydrocarbon receptor is a signal regulated transcription factor that has best been characterised as regulating the xenobiotic response to a variety of planar aromatic hydrocarbons. There is compelling evidence that it mediates most, if not all, of the toxic effects of dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin). Dioxin exposure results in a wide variety of toxic outcomes including severe wasting syndrome, chloracne, thymic involution, severe immune suppression, reduced fertility, hepatotoxicity, teratogenicity, tumour promotion and death. The pleiotropy of toxic outcomes implies the disruption of a wide range of normal physiological functions. The aryl hydrocarbon receptor has developmentally restricted expression as well as developmental defects in gene-targeted mice. It has a wide range of target genes that do not fit into the classical xenobiotic metabolising gene battery and has recently been shown to interact with NF-kappa B and the estrogen receptor. There is also evidence for its activation in the absence of exogenous ligand, all of which point to various roles outside xenobiotic metabolism. Ligands so far identified display differential activation potential with respect to receptor activity. This article addresses activities of the aryl hydrocarbon receptor that are outside the xenobiotic response. Known physiological roles are discussed as well as how their disruption contributes to the pleiotropic toxicity of TCDD.

Breast-cancer-associated metastasis is significantly increased in a model of autoimmune arthritis

Introduction

Sites of chronic inflammation are often associated with the establishment and growth of various malignancies including breast cancer. A common inflammatory condition in humans is autoimmune arthritis (AA) that causes inflammation and deformity of the joints. Other systemic effects associated with arthritis include increased cellular infiltration and inflammation of the lungs. Several studies have reported statistically significant risk ratios between AA and breast cancer. Despite this knowledge, available for a decade, it has never been questioned if the site of chronic inflammation linked to AA creates a milieu that attracts tumor cells to home and grow in the inflamed bones and lungs which are frequent sites of breast cancer metastasis.

Methods

To determine if chronic inflammation induced by autoimmune arthritis contributes to increased breast cancer-associated metastasis, we generated mammary gland tumors in SKG mice that were genetically prone to develop AA. Two breast cancer cell lines, one highly metastatic (4T1) and the other non-metastatic (TUBO) were used to generate the tumors in the mammary fat pad. Lung and bone metastasis and the associated inflammatory milieu were evaluated in the arthritic versus the non-arthritic mice.

Results

We report a three-fold increase in lung metastasis and a significant increase in the incidence of bone metastasis in the pro-arthritic and arthritic mice compared to non-arthritic control mice. We also report that the metastatic breast cancer cells augment the severity of arthritis resulting in a vicious cycle that increases both bone destruction and metastasis. Enhanced neutrophilic and granulocytic infiltration in lungs and bone of the pro-arthritic and arthritic mice and subsequent increase in circulating levels of proinflammatory cytokines, such as macrophage colony stimulating factor (M-CSF), interleukin-17 (IL-17), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and tumor necrosis factor-alpha (TNF-alpha) may contribute to the increased metastasis. Treatment with anti-IL17 + celecoxib, an anti-inflammatory drug completely abrogated the development of metastasis and significantly reduced the primary tumor burden.

Conclusions

The data clearly has important clinical implications for patients diagnosed with metastatic breast cancer, especially with regards to the prognosis and treatment options.

T-bet inhibits the in vivo differentiation of parasite-specific CD4+ Th17 cells in a T cell-intrinsic manner

CD4(+) Th17 cells have emerged as a new T cell subset in the Th1/Th2 paradigm, and efforts have shifted toward understanding the factors that regulate their development in vivo. To analyze the role of the transcription factor T-bet in regulation of Th17 cells, we used a murine model of Trypanosoma cruzi infection, a protozoan parasite that causes Chagas disease in humans. Infection of Tbx21(-/-) mice led to normal, unimpaired development of Ag-specific CD4(+) T cells producing IFN-gamma. However, a robust Th17 response developed concomitant with Th1 responses. Despite significant IFN-gamma production, the physiological effects of Th17 responses prevailed as there was a sharp increase in Gr-1(+)Ly6G(+) neutrophils. Adoptive transfer of T cells from infected Tbx21(-/-) mice into Rag-2(-/-) mice (Tbx21(+/+)) revealed that CD4(+) T cells maintained their IL-17-producing phenotype, including those cells capable of producing both IFN-gamma and IL-17. Furthermore, and in contrast to the effects of IL-2 on Th17 development, IL-2 had no effect on IL-17 production by primed T cells. Importantly, adoptive transfer of T cells from naive Tbx21(-/-) mice into infected Rag-2(-/-) mice recapitulated the differentiation of T. cruzi-specific Th17 cells observed in infected Tbx21(-/-) mice. Conversely, transfer of wild-type T cells into infected Tbx21(-/-) mice did not reveal an increase in Th17 development. These results demonstrate that T-bet regulates the differentiation of T. cruzi-specific Th17 cells in vivo in a T cell-intrinsic manner. These data provide important insight into the role of T-bet in regulation of parasite-specific Th17 responses.

CTLA4 blockade increases Th17 cells in patients with metastatic melanoma

Background

Th17 cells are CD4+ cells that produce interleukin 17 (IL-17) and are potent inducers of tissue inflammation and autoimmunity. We studied the levels of this T cell subset in peripheral blood of patients treated with the anti-CTLA4 antibody tremelimumab since its major dose limiting toxicities are inflammatory and autoimmune in nature.

Methods

Peripheral blood mononuclear cells (PBMC) were collected before and after receiving tremelimumab within two clinical trials, one with tremelimumab alone (21 patients) and another together with autologous dendritic cells (DC) pulsed with the melanoma epitope MART-1_26–35 (6 patients). Cytokines were quantified directly in plasma from patients and after in vitro stimulation of PBMC. We also quantified IL-17 cytokine-producing cells by intracellular cytokine staining (ICS).

Results

There were no significant changes in 13 assayed cytokines, including IL-17, when analyzing plasma samples obtained from patients before and after administration of tremelimumab. However, when PBMC were activated in vitro, IL-17 cytokine in cell culture supernatant and Th17 cells, detected as IL-17-producing CD4 cells by ICS, significantly increased in post-dosing samples. There were no differences in the levels of Th17 cells between patients with or without an objective tumor response, but samples from patients with inflammatory and autoimmune toxicities during the first cycle of therapy had a significant increase in Th17 cells.

Conclusion

The anti-CTLA4 blocking antibody tremelimumab increases Th17 cells in peripheral blood of patients with metastatic melanoma. The relation between increases in Th17 cells and severe autoimmune toxicity after CTLA4 blockade may provide insights into the pathogenesis of anti-CTLA4-induced toxicities.

Trial Registration

Clinical trial registration numbers: NCT0090896 and NCT00471887