More stories on Th17 cells

Increased serum IL-17 and IL-23 in the patient with ankylosing spondylitis

Interleukin 17 (IL-17) is a Th17 cytokine associated with inflammation, autoimmunity, and defense against some bacteria; it has been implicated in many chronic autoimmune diseases including psoriasis, multiple sclerosis, and systemic sclerosis. However, whether IL-17 plays a role in the pathogenesis of ankylosing spondylitis (AS) remains unclear. To analyze the content of IL-17 and IL-23 in the serum from patients with AS compared with health control subject, 50 patients with AS and 43 healthy volunteers were recruited. Serum IL-17 levels were examined by enzyme linked immunosorbent assay (ELISA). Statistic analyses were performed by SPSS 13.0. Results show that the serum IL-17 and IL-23 levels were significantly elevated in AS patients as compared with normal controls. Nevertheless, no associations of serum IL-17 and IL-23 levels with clinical and laboratory parameters were found; no significant difference regarding serum IL-17 and IL-23 levels was found between less active AS and more active AS. However, there was a strong positive association between the serum levels of IL-17 and IL-23 in the AS patients. Our results indicate increased serum IL-17 and IL-23 levels in AS patients, suggesting that this two cytokine may play critical roles in the pathogenesis of AS. Therefore, further studies are required to confirm this preliminary data.

Interactions between immunity and metabolism - contributions from the metabolic profiling of parasite-rodent models

A combined interdisciplinary research strategy is even more crucial in immunology than in many other biological sciences in order to comprehend the closely linked interactions between cell proliferation, molecular signalling and gene rearrangements. Because of the multi-dimensional nature of the immune system, an abundance of different experimental approaches has developed, with a main focus on cellular and molecular mechanisms. The role of metabolism in immunity has been underexplored so far, and yet researchers have made important contributions in describing associations of immune processes and metabolic pathways, such as the central role of the l-arginine pathway in macrophage activation or the immune regulatory functions of the nucleotides. Furthermore, metabolite supplement studies, including nutritional administration and labelled substrates, have opened up new means of manipulating immune mechanisms. Metabolic profiling has introduced a reproducible platform for systemic assessment of changes at the small-molecule level within a host organism, and specific metabolic fingerprints of several parasitic infections have been characterized by 1H NMR spectroscopy. The application of multivariate statistical methods to spectral data has facilitated recovery of biomarkers, such as increased acute phase protein signals, and enabled direct correlation to the relative cytokine levels, which encourages further application of metabolic profiling to explore immune regulatory systems.

Tryptophan catabolism by indoleamine 2,3-dioxygenase 1 alters the balance of TH17 to regulatory T cells in HIV disease

The pathogenesis of human and simian immunodeficiency viruses is characterized by CD4(+) T cell depletion and chronic T cell activation, leading ultimately to AIDS. CD4(+) T helper (T(H)) cells provide protective immunity and immune regulation through different immune cell functional subsets, including T(H)1, T(H)2, T regulatory (T(reg)), and interleukin-17 (IL-17)-secreting T(H)17 cells. Because IL-17 can enhance host defenses against microbial agents, thus maintaining the integrity of the mucosal barrier, loss of T(H)17 cells may foster microbial translocation and sustained inflammation. Here, we study HIV-seropositive subjects and find that progressive disease is associated with the loss of T(H)17 cells and a reciprocal increase in the fraction of the immunosuppressive T(reg) cells both in peripheral blood and in rectosigmoid biopsies. The loss of T(H)17/T(reg) balance is associated with induction of indoleamine 2,3-dioxygenase 1 (IDO1) by myeloid antigen-presenting dendritic cells and with increased plasma concentration of microbial products. In vitro, the loss of T(H)17/T(reg) balance is mediated directly by the proximal tryptophan catabolite from IDO metabolism, 3-hydroxyanthranilic acid. We postulate that induction of IDO may represent a critical initiating event that results in inversion of the T(H)17/T(reg) balance and in the consequent maintenance of a chronic inflammatory state in progressive HIV disease.

Integrated cytokine and metabolic analysis of pathological responses to parasite exposure in rodents

Parasitic infections cause a myriad of responses in their mammalian hosts, on immune as well as on metabolic level. A multiplex panel of cytokines and metabolites derived from four parasite-rodent models, namely, Plasmodium berghei−mouse, Trypanosoma brucei brucei−mouse, Schistosoma mansoni−mouse, and Fasciola hepatica−rat were statistically coanalyzed. ¹H NMR spectroscopy and multivariate statistical analysis were used to characterize the urine and plasma metabolite profiles in infected and noninfected animals. Each parasite generated a unique metabolic signature in the host. Plasma cytokine concentrations were obtained using the ‘Meso Scale Discovery’ multi cytokine assay platform. Multivariate data integration methods were subsequently used to elucidate the component of the metabolic signature which is associated with inflammation and to determine specific metabolic correlates with parasite-induced changes in plasma cytokine levels. For example, the relative levels of acetyl glycoproteins extracted from the plasma metabolite profile in the P. berghei-infected mice were statistically correlated with IFN-γ, whereas the same cytokine was anticorrelated with glucose levels. Both the metabolic and the cytokine data showed a similar spatial distribution in principal component analysis scores plots constructed for the combined murine data, with samples from all infected animals clustering according to the parasite species and whereby the protozoan infections (P. berghei and T. b. brucei) grouped separately from the helminth infection (S. mansoni). For S. mansoni, the main infection-responsive cytokines were IL-4 and IL-5, which covaried with lactate, choline, and d-3-hydroxybutyrate. This study demonstrates that the inherently differential immune response to single- and multicellular parasites not only manifests in the cytokine expression, but also consequently imprints on the metabolic signature, and calls for in-depth analysis to further explore direct links between immune features and biochemical pathways.

Parasitic infections cause a myriad of responses in their mammalian hosts, including a range of immune reactions and metabolic perturbations. Here, a multiplex panel of cytokines and metabolites derived from four parasite-rodent models, namely, Plasmodium berghei−mouse, Trypanosoma brucei brucei−mouse, Schistosoma mansoni−mouse, and Fasciola hepatica−rat were statistically coanalyzed. ¹H NMR spectroscopy and multivariate statistical analysis were used to characterize the urine and plasma metabolite profiles in infected and noninfected control animals.

Altered signaling through IL-12 receptor in children with very high serum IgE levels

An alteration of Th1/Th2 homeostasis may lead to diseases in humans. In this study, we investigated whether an impaired IL-12R signaling occurred in children with elevated serum IgE levels divided on the basis of the IgE levels (group A: >2000kU/l; group B: <2000kU/l). We evaluated the integrity of the IL-12R signaling through the analysis of phosphorylation/activation of STAT4, and mRNA expression and membrane assembly of the receptor chains. At a functional level, a proliferative defect of lymphocytes from group A patients was observed. In these patients, an abnormal IL-12R signaling was documented, and this finding was associated with abnormal expression of the IL-12Rbeta2 chain. Our data indicate that in patients with very high IgE levels the generation of Th1 response is impaired, and that this abnormality associates with abnormal IL-12R signaling.

Mucopolysaccharidosis IIIB, a lysosomal storage disease, triggers a pathogenic CNS autoimmune response

Background

Recently, using a mouse model of mucopolysaccharidosis (MPS) IIIB, a lysosomal storage disease with severe neurological deterioration, we showed that MPS IIIB neuropathology is accompanied by a robust neuroinflammatory response of unknown consequence. This study was to assess whether MPS IIIB lymphocytes are pathogenic.

Methods

Lymphocytes from MPS IIIB mice were adoptively transferred to naïve wild-type mice. The recipient animals were then evaluated for signs of disease and inflammation in the central nervous system.

Results

Our results show for the first time, that lymphocytes isolated from MPS IIIB mice caused a mild paralytic disease when they were injected systemically into naïve wild-type mice. This disease is characterized by mild tail and lower trunk weakness with delayed weight gain. The MPS IIIB lymphocytes also trigger neuroinflammation within the CNS of recipient mice characterized by an increase in transcripts of IL2, IL4, IL5, IL17, TNFα, IFNα and Ifi30, and intraparenchymal lymphocyte infiltration.

Conclusions

Our data suggest that an autoimmune response directed at CNS components contributes to MPS IIIB neuropathology independent of lysosomal storage pathology. Adoptive transfer of purified T-cells will be needed in future studies to identify specific effector T-cells in MPS IIIB neuroimmune pathogenesis.

Lymphocyte activation in type 1 diabetes mellitus: the increased significance of Kv1.3 potassium channels

Kv1.3 and IKCa1 potassium channels participate in the maintenance of calcium-influx during lymphocyte activation. Kv1.3 channels have a prominent role in specific T cell subsets, presenting a possible target for selective immunomodulation. We investigated the impact of Kv1.3 and IKCa1 channel inhibitors on calcium-influx characteristics in human T cells in type 1 diabetes mellitus. We isolated lymphocytes from 9 healthy and 9 type 1 diabetic individuals and measured the alteration of calcium-influx with flow cytometry in the Th1, Th2, CD4 and CD8 subsets after treatment of samples with specific channel inhibitors. Our results indicate an increased reactivity of type 1 diabetes lymphocytes, which is correlated to their increased sensitivity to Kv1.3 channel inhibition. However, the contribution of Kv1.3 channels to calcium flux is not exclusive for a specific lymphocyte subset as previous reports suggest, but is characteristic for each subset investigated. Therefore, the proposed inhibition of Kv1.3 channels as a novel therapeutic approach for the treatment of type 1 diabetes mellitus may have a major effect on overall lymphocyte function in this disease.

Th 17 cells interplay with Foxp3+ Tregs in regulation of inflammation and autoimmunity

T helper 17 cells (Th17) are a new CD4+ T helper subset that has been implicated in inflammatory and autoimmune diseases. Th17, along with CD4(+)CD25(high) Foxp3(+) regulatory T cells (Tregs) and other new T helper subsets, have expanded the Th1-Th2 paradigm. Although this new eight-subset paradigm significantly improved our understanding on the differentiation and regulation of CD4+ T helper subsets, many questions remain to be answered. Here we will briefly review the following issues: a) Old Th1-Th2 paradigm versus new multi-subset paradigm; b) Structural features of IL-17 family cytokines; c) Th17 cells; d) Effects of IL-17 on various cell types and tissues; e) IL-17 receptor and signaling pathways; f) Th17-mediated inflammations; and g) Protective mechanisms of IL-17 in infections. Lastly, we will examine the interactions of Th17 and Treg in autoimmune diseases and inflammation: Th17 cells interplay with Tregs. Regulation of autoimmunity and inflammation lies in the interplays of the different T helper subsets, therefore, better understanding of these subsets' interactions would greatly improve our approaches in developing therapy to combat inflammatory and autoimmune diseases.

Th17 and regulatory T cells: implications for AIDS pathogenesis

PURPOSE OF REVIEW

The present review discusses recent reports showing that reciprocal changes in T helper interleukin-17-secreting CD4 Th17 cells and CD4CD25FoxP3 regulatory T cells (Tregs) may play a role in the progressive disease caused by the HIV and by simian immunodeficiency virus.

RECENT FINDINGS

Studies in nonhuman primate models of lentiviral infection and in HIV-infected human individuals have shown that pathogenic infection is associated with loss of Th17 cells and an increase in the frequency of Tregs. Because interleukin-17 serves to maintain the integrity of the mucosal barrier, loss of Th17 cells may permit the increase in microbial translocation across the gastrointestinal mucosa that is observed in pathogenic lentiviral disease. It remains unclear, however, whether Th17 cells are preferentially infected or if, instead, their loss is induced by bystander effects of lentiviral infection, for example, the induction of indoleamine 2,3-dioxygenase.

SUMMARY

Progressive lentiviral disease is associated with preferential depletion of Th17 cells and loss of Th17/Treg balance. Further analysis of such changes in the composition of subset CD4 T helper and Tregs may shed new light on the immunopathology of HIV disease and suggest new strategies for therapeutic and preventive interventions.

The cannabinoid R+ methanandamide induces IL-6 secretion by prostate cancer PC3 cells

In the present study, we have investigated the effect of the cannabinoid R+ methanandamide (MET) in the androgen-resistant prostate cancer PC3 cells. MET induced a dose-dependent decrease in PC3 cell viability as well as a dose-dependent increase in the secretion of the cytokine IL-6. Looking deeper into the mechanisms involved, we found that MET-induced de novo synthesis of the lipid mediator ceramide that was blocked by the ceramide synthase inhibitor Fumonisin B1. Pre-incubation of cells with the cannabinoid receptor CB2 antagonist SR 144528 (SR2), but not the CB1 antagonist Rimonabant or the TRPV1 antagonist capsazepine, partially prevented the anti-proliferative effect, the ceramide accumulation, and the IL-6-induced secretion, suggesting a CB2 receptor-dependent mechanism. Fumonisin B1 did not have any effect in the IL-6 secretion increase induced by MET. However, even an incomplete down-regulation of (i.e., not a total silencing of) ceramide kinase expression by specific siRNA prevented the MET-induced IL-6 secretion. These results suggest that MET regulates ceramide metabolism in prostate PC3 cells which is involved in cell death as well as in IL-6 secretion. Our findings also suggest that CB2 agonists may offer a novel approach in the treatment of prostate cancer by decreasing cancer epithelial cell proliferation. However, the interaction of prostate cancer cells with their surrounding, and in particular with the immune system in vivo, needs to be further explored.

The many face-lifts of CD4 T helper cells

Recent advances in stem cell research have redefined previous concepts of hematopoietic hierarchy, lineage commitment, and cell fate. The immune system is comprised of several well-defined cell lineages of which many exhibit high levels of plasticity or capacity in changing their phenotype. The CD4 T helper cells provide a peculiar example of apparently defined cell subsets, at times described as lineages, but also highly sensitive to tissue environmental cues that may change their fate. The classical Th1/Th2 CD4 T cell differentiation referred to for many years as the main CD4 T cell fate dichotomy and the later additions of CD4 helper T cell variants, such as T helper 17 (Th17) and induced regulatory T cells (iTreg), have added complexity but also doubts on the accuracy of defining CD4 T cell subsets as fixed T cell lineages.

Potential role of interleukin-17 in the pathogenesis of bullous pemphigoid

Bullous pemphigoid is an autoimmune blistering disease of the skin caused by autoantibodies directed against basement membrane zone adhesion molecules. Autoantibodies cannot fully explain several important features of the disease such as the difficulty transferring with the pathogenic autoantibodies, or the presence of heavy lesional infiltration of eosinophils and neutrophils that is necessary for disease production. There is increasing evidence that Th17 cells and the cytokines they release such as interleukin-17 are important regulators of innate and adaptive immune responses in many Th1 and/or Th2 mediated autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, and allergic asthma. There is also evidence that Th17 cells have a role in pathogenesis of blistering skin diseases. Interleukin-17 is important in initiation and maintenance of many autoimmune reactions and it is involved in production of pro-inflammatory cytokines, matrix metalloproteinases, neutrophils, and eosinophils, all of which are important pathogenic factors in bullous pemphigoid. The hypothesis is that interleukin-17 has an important pathogenic role in BP and can describe features of the disease not explained by the autoantibody theory. This cytokine can be assessed in the blister fluid and sera of patients, and can be used as a marker of disease activity and response to therapy. The information obtained could also lead to the development of novel therapeutic strategies for this and other autoimmune blistering diseases.

Effective treatment of psoriasis with etanercept is linked to suppression of IL-17 signaling, not immediate response TNF genes

BACKGROUND

TNF inhibitors have revolutionized the treatment of psoriasis vulgaris as well as psoriatic and rheumatoid arthritis and Crohn disease. Despite our understanding that these agents block TNF, their complex mechanism of action in disease resolution is still unclear.

OBJECTIVE

To analyze globally the genomic effects of TNF inhibition in patients with psoriasis, and to compare genomic profiles of patients who responded or did not respond to treatment.

METHODS

In a clinical trial using etanercept TNF inhibitor to treat psoriasis vulgaris (n = 15), Affymetrix gene arrays were used to analyze gene profiles in lesional skin at multiple time points during drug treatment (baseline and weeks 1, 2, 4, and 12) compared with nonlesional skin. Patients were stratified as responders (n = 11) or nonresponders (n = 4) on the basis of histologic disease resolution. Cluster analysis was used to define gene sets that were modulated with similar magnitude and velocity over time.

RESULTS

In responders, 4 clusters of downregulated genes and 3 clusters of upregulated genes were identified. Genes downmodulated most rapidly reflected direct inhibition of myeloid lineage immune genes. Upregulated genes included the stable dendritic cell population genes CD1c and CD207 (langerin). Comparison of responders and nonresponders revealed rapid downmodulation of innate IL-1beta and IL-8 sepsis cascade cytokines in both groups, but only responders downregulated IL-17 pathway genes to baseline levels.

CONCLUSION

Although both responders and nonresponders to etanercept inactivated sepsis cascade cytokines, response to etanercept is dependent on inactivation of myeloid dendritic cell genes and inactivation of the T(H)17 immune response.

In vitro cytokine responses of peripheral blood mononuclear cells from healthy dogs to distemper virus, Malassezia and Toxocara

Naïve CD4+ T cells may differentiate into a number of subsets including T helper 1 (Th1) Th2, Th3, Th17 and T regulatory (Treg) cells depending on the type of antigen they encounter. These CD4+ families have been defined based on the array of cytokines they produce and the effects they have on adaptive immune responses. CD4+ subsets are cross regulatory and at times cooperative. The study of these adaptive immune modulators has revealed the important role that cytokines play in mounting effective as well as detrimental immune responses to pathogens. Examining the cytokine responses of lymphocytes in culture can provide important understanding of how immune responses to pathogens are orchestrated. For this purpose the in vitro cytokine production of peripheral blood mononuclear cells (PBMC) from healthy dogs was examined in response to stimulation with antigens from a common canine virus (canine distemper virus, CDV), a commensal skin yeast of dogs (Malassezia pachydermatis) and a common canine helminth (Toxocara canis (T. canis)). Cell culture supernatants were removed from antigen stimulated and unstimulated control PBMC after 4, 24, 48 and 72 h and the concentration of Th1 type cytokines (IL-2, IFN-gamma, TNF-alpha) and Th2 type cytokines (IL-4, IL-5, IL-10) was determined using sandwich ELISA assays. CDV induced low levels of cytokine production initially with a predominance of IL-10 at 24h and a balanced response at 48 h of incubation. Malassezia antigen stimulated an early type 2 cytokine response with dramatic production of IL-4 at 24h of incubation compared to the other stimulants examined. By 48 h of incubation, however, the cytokine mix in response to Malassezia had also moved toward a Th1 type response. T. canis induced early production of Th2 type cytokines with IL-5 predominating; however, with longer incubation (48-72 h) there was a switch to a balanced Th1/Th2 response. In conclusion, the cytokines produced in vitro by canine PBMC in response to prototypical Th1 and Th2 type pathogens were not clearly polarized and shifted over time. While the in vitro study of PBMC cytokine responses cannot be directly extrapolated to in vivo responses to the same antigens, the results do highlight the dynamic and fluctuating nature of cytokine production.