Herpesvirus Saimiri encodes a new cytokine, IL-17, which binds to a novel cytokine receptor

The effect of proinflammatory cytokines on IL-17RA expression in NSCLC

Interleukin-17 receptor (IL-17RA) is essential for proinflammatory cytokine IL-17-mediated pathogenesis of various tumors. IL-17RA is upregulated by some proinflammatory cytokines such as IL-21 and IL-15 and downregulated by IL-2, while the effect of IL-1β, IL-6, IL-8, TNF-α on IL-17RA expression in non-small cell lung caner (NSCLC) remains unknown. Our findings revealed that IL-17RA mRNA was increased in NSCLC tissues compared with the corresponding peritumor tissues (P = 0.0039) and high expression of IL-17RA protein in human NSCLC tissues was significantly associated with histological subtype, primary tumor size and clinical stages (P = 0.033, 0.033 and 0.011, respectively). IL-17RA mRNA expression was positively related to IL-1β, IL-6, IL-8, TNF-α mRNA expression (P = 0.013, 0.0001, 0.002 and 0.010 respectively) in NSCLC tissues. Furthermore, IL-1β, IL-6, IL-8, TNF-α upregulated IL-17RA mRNA and protein in A549 and H460 cells (all P < 0.05). It is suggested that IL-1β, IL-6, IL-8, TNF-α promoted IL-17RA expression in NSCLC and they may involve in IL-17RA signaling in NSCLC.

Th17 cells and interleukin-17 increase with poor prognosis in patients with acute myeloid leukemia

Although Th17 cells play crucial roles in the pathogenesis of many autoimmune and inflammatory disorders, their roles in malignancies are currently under debate. The role and mechanism of Th17 cells in patients with acute myeloid leukemia (AML) remain poorly understood. Here we demonstrated that the frequency of Th17 cells was significantly increased in peripheral blood mononuclear cells (PBMCs) and bone marrow mononuclear cells from AML patients compared with healthy donors. Plasma levels of interleukin (IL)-17, IL-22, IL-23, IL-1β, IL-6, and transforming growth factor (TGF)-β1 were significantly increased in blood and bone marrow in AML patients compared with healthy donors. The in vitro experiments demonstrated that IL-1β, IL-6, IL-23, but not TGF-β1 promoted the generation and differentiation of Th17 cells from naive CD4(+) T cells in humans. IL-17A, a signature cytokine secreted by Th17 cells, induced the proliferation of IL-17 receptor (IL-17R)-positive AML cells via IL-17R, in which activation of PI3K/Akt and Jak/Stat3 signaling pathway may play important roles. In addition, combination of IL-17A and IL-22 significantly reduced the generation of Th1 cells and the production of interferon (IFN)-γ from healthy donor or AML patient peripheral blood mononuclear cells. Patients with high Th17 cell frequency had poor prognosis, whereas patients with high Th1 cell frequency had prolonged survival. Combined analysis of Th1 and Th17 cell frequencies improved the ability to predict patient outcomes. In conclusion, Th17 cells play a crucial role in the pathogenesis of AML and may be an important therapeutic target and prognostic predictor.

IL-17 genetic and immunophenotypic evaluation in chronic graft-versus-host disease

Although interleukin-17 (IL-17) is a recently discovered cytokine associated with several autoimmune diseases, its role in the pathogenesis of chronic graft-versus-host disease (cGVHD) was not established yet. The objective of this study was to investigate the association of IL17A and IL17F genes polymorphisms and IL-17A and IL-17F levels with cGVHD. IL-17A expression was also investigated in CD4(+) T cells of patients with systemic cGVHD. For Part I of the study, fifty-eight allo-HSCT recipients and donors were prospectively studied. Blood samples were obtained to determine IL17A and IL17F genes polymorphisms. Cytokines levels in blood and saliva were assessed by ELISA at days +35 and +100 after HSCT. In Part II, for the immunophenotypic evaluation, eight patients with systemic cGVHD were selected and the expression of IL-17A was evaluated. We found association between recipient AA genotype with systemic cGVHD. No association was observed between IL-17A levels and cGVHD. Lower IL-17A levels in the blood were associated with AA genotype. In flow cytometry analysis, decreased expression of IL-17A was observed in patients with cGVHD after stimulation. In conclusion, IL-17A may have an important role in the development of systemic cGVHD.

Interleukin-17 enhances immunosuppression by mesenchymal stem cells

IL-17 is one of the most potent and most actively investigated proinflammatory cytokines. In this study, we examined the effect of IL-17 on mesenchymal stem cells (MSCs) under the influence of inflammatory cytokines. Ironically, IL-17 dramatically enhanced the immunosuppressive effect of MSCs induced by IFNγ and TNFα, revealing a novel role of IL-17 in immunosuppression. Interestingly, we found that this action of IL-17 was dependent on the promoted expression of a key immune suppressive molecule, inducible nitric oxide synthase (iNOS), in MSCs. In a concanavalin A (ConA)-induced hepatitis mouse model, we found that IL-17 also enhanced the in vivo immunosuppressive effect of MSCs in an iNOS-dependent manner. Moreover, this promoting effect of IL-17 was found to be exerted through enhancing mRNA stability by modulating the protein level of ARE/poly(U)-binding/degradation factor 1 (AUF1), a well-known factor that promotes mRNA decay. In auf1^−/− MSCs, IFNγ and TNFα could induce maximal immunosuppressive effect, both in vitro and in vivo, without the need for IL-17. Thus, our studies demonstrated that in the presence of MSCs, IL-17 promotes immunosuppression.

Directing traffic: IL-17 and IL-22 coordinate pulmonary immune defense

Respiratory infections and diseases are among the leading causes of death worldwide, and effective treatments probably require manipulating the inflammatory response to pathogenic microbes or allergens. Here, we review mechanisms controlling the production and functions of interleukin-17 (IL-17) and IL-22, cytokines that direct several aspects of lung immunity. Innate lymphocytes (γδ T cells, natural killer cells, innate lymphoid cells) are the major source of IL-17 and IL-22 during acute infections, while CD4(+) T-helper 17 (Th17) cells contribute to vaccine-induced immunity. The characterization of dendritic cell (DC) subsets has revealed their central roles in T-cell activation. CD11b(+) DCs stimulated with bacteria or fungi secrete IL-1β and IL-23, potent inducers of IL-17 and IL-22. On the other hand, recognition of viruses by plasmacytoid DCs inhibits IL-1β and IL-23 release, increasing susceptibility to bacterial superinfections. IL-17 and IL-22 primarily act on the lung epithelium, inducing antimicrobial proteins and neutrophil chemoattractants. Recent studies found that stimulation of macrophages and DCs with IL-17 also contributes to antibacterial immunity, while IL-22 promotes epithelial proliferation and repair following injury. Chronic diseases such as asthma and chronic obstructive pulmonary disease have been associated with IL-17 and IL-22 responses directed against innocuous antigens. Future studies will evaluate the therapeutic efficacy of targeting the IL-17/IL-22 pathway in pulmonary inflammation.

Downregulation of chicken interleukin-17 receptor A during Eimeria infection

Both interleukin-17A (IL-17A) and IL-17F are proinflammatory cytokines that have an important role in intestinal homeostasis via receptor signaling. These cytokines have been characterized in chickens, but very little is known about their receptors and their functional activity. We provide here the first description of the sequence analysis, bioactivity, and comparative expression analysis of chicken IL-17RA (chIL-17RA) in chickens infected with Salmonella and Eimeria, two major infectious agents of gastrointestinal diseases of poultry of economic importance. A full-length chIL-17RA cDNA with a 2,568-bp coding region was identified from chicken thymus cDNA. chIL-17RA shares ca. 46% identity with mammalian homologues and 29.2 to 31.5% identity with its piscine counterparts. chIL-17RA transcript expression was relatively high in the thymus and in the chicken macrophage cell line HD11. The chIL-17RA-specific small interfering RNA inhibits interleukin-6 (IL-6), IL-8, and IL-1β mRNA expression in chicken embryo fibroblast cells (but not in DF-1 cells) stimulated with chIL-17A or chIL-17F. Interaction between chIL-17RA and chIL-17A was confirmed by coimmunoprecipitation. Downregulation of chIL-17RA occurred in concanavalin A- or lipopolysaccharide-activated splenic lymphocytes but not in poly(I·C)-activated splenic lymphocytes. In Salmonella- and Eimeria-infected chickens, the expression levels of the chIL-17RA transcript were downregulated in intestinal tissues from chickens infected with two Eimeria species, E. tenella or E. maxima, that preferentially infect the cecum and jejunum, respectively. However, chIL-17RA expression was generally unchanged in Salmonella infection. These results suggest that chIL-17RA has an important role in mucosal immunity to intestinal intracellular parasite infections such as Eimeria infection.

Idiopathic pulmonary fibrosis is strongly associated with productive infection by herpesvirus saimiri

Idiopathic pulmonary fibrosis is a fatal disease without effective therapy or diagnostic test. To investigate a potential role for γ-herpesviruses in this disease, 21 paraffin-embedded lung biopsies from patients diagnosed with idiopathic pulmonary fibrosis and 21 lung biopsies from age-matched controls with pulmonary fibrosis of known etiology were examined for a series of γ-herpesviruses' DNA/RNA and related proteins using in situ hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR)-based methods. We detected four proteins known to be in the genome of several γ-herpesviruses (cyclin D, thymidylate synthase, dihydrofolate reductase, and interleukin-17) that were strongly co-expressed in the regenerating epithelial cells of each of the 21 idiopathic pulmonary fibrosis cases and not in the benign epithelia of the controls. Among the γ-herpesviruses, only herpesvirus saimiri expresses all four of these 'pirated' mammalian proteins. We found herpesvirus saimiri DNA in the regenerating epithelial cells of 21/21 idiopathic pulmonary fibrosis cases using four separate probe sets but not in the 21 controls. RT-PCR showed that the source of the cyclin D RNA in active idiopathic pulmonary fibrosis was herpesvirus saimiri and not human. We cloned and sequenced part of genome corresponding to the DNA polymerase herpesvirus saimiri gene from an idiopathic pulmonary fibrosis sample and it matched 100% with the published viral sequence. These data are consistent with idiopathic pulmonary fibrosis representing herpesvirus saimiri-induced pulmonary fibrosis. Thus, treatment directed against viral proliferation and/or viral-associated proteins may halt disease progression. Further, demonstration of the viral nucleic acids or proteins may help diagnose the disease.

Absence of interleukin-17 receptor a signaling prevents autoimmune inflammation of the joint and leads to a Th2-like phenotype in collagen-induced arthritis

OBJECTIVE

Interleukin-17A (IL-17A) signals through the IL-17 receptor (IL-17R) A/C heterodimer. IL-17RA serves as a common receptor subunit for several IL-17 cytokine family members. Lack of IL-17RA signaling may therefore have additional effects beyond those of lack of IL-17A alone. The present study was undertaken to determine the role of IL-17RA signaling in autoimmune arthritis.

METHODS

Disease incidence and severity were scored in type II collagen-treated wild-type, IL-17RA-deficient, and IL-23p19-deficient mice. T helper cell profiles and humoral immune responses were analyzed at several time points. Pathogenicity of T cells and total splenocytes was determined by in vitro functional assay. IL-17RA signaling was blocked in vivo in mice with antigen-induced arthritis (AIA).

RESULTS

Comparable to the findings in IL-23p19-deficient mice, IL-17RA-deficient mice were completely protected against the development of collagen-induced arthritis (CIA). However, IL-17RA-deficient mice exhibited an increased number of IL-4-producing CD4+ T cells, distinct from IL-17A+CD4+ T cells. This was associated with fewer plasma cells, lower production of pathogenic IgG2c antibody, and increased production of IgG1 antibody. Both isolated CD4+ T cells and total splenocytes from IL-17RA-deficient mice had a reduced ability to induce IL-6 production by synovial fibroblasts in the setting of CIA, in a functional in vitro assay. Furthermore, blocking of IL-17RA signaling in AIA reduced synovial inflammation.

CONCLUSION

These results demonstrate that absence of IL-17RA leads to a Th2-like phenotype characterized by IL-4 production and suggest that IL-17RA signaling plays a critical role in the regulation of IL-4 in CIA and the development of autoimmune inflammation of the joint.

The transmembrane proteins contribute to immunodeficiencies induced by HIV-1 and other retroviruses

Many microorganisms including retroviruses suppress the immune system of the infected host in order to maintain infection. Unfortunately, it is still unclear how retroviruses induce immunosuppression. There is increasing evidence of a common mechanism based on their transmembrane envelope proteins. This review therefore summarizes evidence of the involvement of the transmembrane envelope proteins in the immunopathogenesis of different retroviruses including HIV-1. Mutations in the immunosuppressive (isu) domain of the transmembrane envelope protein of several retroviruses abrogate the immunosuppressive activities in vitro and in vivo. Most importantly, virus sequences with such abrogating mutations were never found in HIV-1-infected individuals despite the fact that the mutated viruses are replication-competent. However, there is also evidence for additional, perhaps even divergent, strategies for each retrovirus. For example, in contrast to many other retroviruses, the HIV directly interacts with immune cells and infects them. In addition, HIV uses several accessory proteins to evade the immune response. Furthermore, the possible contribution of the transmembrane envelope proteins of endogenous retroviruses to immunosuppression when expressed on tumor cells or in the placenta is analyzed.

Characterization and mucosal responses of interleukin 17 family ligand and receptor genes in channel catfish Ictalurus punctatus

Interleukin (IL) 17 family cytokines are important mediators of mucosal immune responses, tightly regulated by signals from the complex milieu of pathogenic and commensal microbes, epithelial cells and innate and adaptive leukocytes found at tissue barriers. In mammals, IL17 ligand expression has been linked not only to protective immunity but also excessive tissue inflammation and damage in the gut and lungs. To better understand the scope and action of the IL17 family in channel catfish Ictalurus punctatus, we identified and characterized seven IL17 ligands and four IL17 receptor (IL17R) homologues from transcriptomic and genomic databases. To gain insight into the mucosal actions of the IL17A/Fs-associated pathway in inflammatory processes, the expression profiles of three IL17A/Fs and their putative receptors IL17RA and IL17RC in mucosal tissues of catfish following experimental challenge with Edwardsiella ictaluri and Flavobacterium columnare were investigated. Bacterial challenge induced higher expression of the catfish IL17A/Fs as early at 4 h post-infection, particularly in gill tissue. In contrast, in the catfish intestine, where IL17 function is best understood in mouse models, IL17A/F expression showed minimal early responses to E. ictaluri infection. Instead, a significant up-regulation of IL17 ligands and receptors was observed in the intestine at 7 d, highlighting species and tissue-specific regulation of the IL17 family.

Potential involvement of IL-17F in asthma

The expression of IL-17F is seen in the airway of asthmatics and its level is correlated with disease severity. Several studies have demonstrated that IL-17F plays a pivotal role in allergic airway inflammation and induces several asthma-related molecules such as CCL20. IL-17F-induced CCL20 may attract Th17 cells into the airway resulting in the recruitment of additional Th17 cells to enhance allergic airway inflammation. We have recently identified, for the first time, that bronchial epithelial cells are its novel cell source in response to IL-33 via ST2-ERK1/2-MSK1 signaling pathway. The receptor for IL-17F is the heterodimeric complex of IL-17RA and IL-17RC, and IL-17F activates many signaling pathways. In a case-control study of 867 unrelated Japanese subjects, a His161 to Arg161 (H161R) substitution in the third exon of the IL-17F gene was associated with asthma. In atopic patients with asthma, prebronchodilator baseline FEV1/FVC values showed a significant association with the H161R variant. Moreover, this variant is a natural antagonist for the wild-type IL-17F. Moreover, IL-17F is involved in airway remodeling and steroid resistance. Hence, IL-17F may play an orchestrating role in the pathogenesis of asthma and may provide a valuable therapeutic target for development of novel strategies.

Helper T-cell differentiation in graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective therapeutic option for many malignant diseases. However, the efficacy of allo-HSCT is limited by the occurrence of destructive graft-versus-host disease (GVHD). Since allogeneic T cells are the driving force in the development of GVHD, their activation, proliferation, and differentiation are key factors to understanding GVHD pathogenesis. This review focuses on one critical aspect: the differentiation and function of helper T (Th) cells in acute GVHD. We first summarize well-established subsets including Th1, Th2, Th17, and T-regulatory cells; their flexibility, plasticity, and epigenetic modification; and newly identified subsets including Th9, Th22, and T follicular helper cells. Next, we extensively discuss preclinical findings of Th-cell lineages in GVHD: the networks of transcription factors involved in differentiation, the cytokine and signaling requirements for development, the reciprocal differentiation features, and the regulation of microRNAs on T-cell differentiation. Finally, we briefly summarize the recent findings on the roles of T-cell subsets in clinical GVHD and ongoing strategies to modify T-cell differentiation for controlling GVHD in patients. We believe further exploration and understanding of the immunobiology of T-cell differentiation in GVHD will expand therapeutic options for the continuing success of allo-HSCT.

Virus-induced transcriptional changes in the brain include the differential expression of genes associated with interferon, apoptosis, interleukin 17 receptor A, and glutamate signaling as well as flavivirus-specific upregulation of tRNA synthetases

Flaviviruses, particularly Japanese encephalitis virus (JEV) and West Nile virus (WNV), are important causes of virus-induced central nervous system (CNS) disease in humans. We used microarray analysis to identify cellular genes that are differentially regulated following infection of the brain with JEV (P3) or WNV (New York 99). Gene expression data for these flaviviruses were compared to those obtained following infection of the brain with reovirus (type 3 Dearing), an unrelated neurotropic virus. We found that a large number of genes were up-regulated by all three viruses (using the criteria of a change of >2-fold and a P value of <0.001), including genes associated with interferon signaling, the immune system, inflammation, and cell death/survival signaling. In addition, genes associated with glutamate signaling were down-regulated in infections with all three viruses (criteria, a >2-fold change and a P value of <0.001). These genes may serve as broad-spectrum therapeutic targets for virus-induced CNS disease. A distinct set of genes were up-regulated following flavivirus infection but not following infection with reovirus. These genes were associated with tRNA charging and may serve as therapeutic targets for flavivirus-induced CNS disease. IMPORTANCE Viral infections of the central nervous system (CNS) are an important cause of morbidity and mortality. Treatment options for virus-induced CNS disease are limited, and for many clinically important neurotropic viruses, no specific therapy of proven benefit is currently available. We performed microarray analysis to identify genes that are differentially regulated in the brain following virus infection in order to identify pathways that might provide novel therapeutic targets for virus-induced CNS disease. Although several studies have described gene expression changes following virus infection of the brain, this report is the first to directly compare large-scale gene expression data from different viruses. We identified genes that are differentially regulated in infection of the brain with viruses from different families and those which appear to be specific to flavivirus infections.

The expression profile of miR-23b is not altered in peripheral blood mononuclear cells of patients with idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) belong to a group of autoimmune disorders, primarily characterized by chronic inflammation of human skeletal muscle tissue. The etiology of these diseases is unknown, however, genetic predisposition plays a significant role in disease onset. Beside the known genetic risk located in the MHC complex, the epigenetic modifications including changes in miRNAs expression profiles have been recently implicated recently in many autoimmune diseases. Micro RNA molecules are involved in many physiological processes, including the regulation of the immune response. In our study we have focused on the miR-23b, as it represents a novel promising autoimmunity regulator molecule. Downregulation of miR-23b was recently described in patients with rheumatoid arthritis and systemic lupus erythematosus. We have measured the expression miR-23b peripheral blood mononuclear cells of patients with dermatomyositis and polymyositis. No meaningful difference was found in comparison with healthy controls.

Reduction of IL-17A might suppress the Th1 response and promote the Th2 response by boosting the function of Treg cells during silica-induced inflammatory response in vitro

Silica inhalation can induce chronic lung inflammation and fibrosis. Upon silica stimulation, activated macrophages trigger the T-lymphocyte which can differentiate into many different types of Th cells, including the recently discovered Th17 cells. IL-17A, the typical Th17 cytokine, is reported in some inflammatory diseases. However, the role of IL-17A in silica-induced inflammatory response is still not clear. The regulatory mechanism of silica-induced Th17 response also needs to be investigated. So we established a mice primary cell coculture system (macrophage and lymphocyte) to investigate the role of IL-17A in silica-induced inflammatory response in vitro, by using anti-IL-17A mAb and IL-1Ra. Both anti-IL-17A mAb and IL-1Ra decreased the level of IL-17A and increased the function of Treg cells. The Th1 response was suppressed and the Th2 response was promoted by the addition of anti-IL-17A mAb or IL-1Ra. IL-1Ra treatment decreased the level of IL-6, whereas the levels of IL-23 and ROR- γ t were increased. Our study demonstrated that IL-17A reduction altered the pattern of silica-induced Th responses by boosting the function of Treg cells in vitro. Blocking the function of IL-1 signal pathway could suppress the level of IL-17A, which played the major role in modulating silica-induced Th responses in vitro.

Current data on IL-17 and Th17 cells and implications for graft versus host disease

Human interleukin 17 was first described in 1995 as a new cytokine produced primarily by activated T CD4+ cells that stimulate the secretion of IL-6 and IL-8 by human fibroblasts, besides increasing the expression of ICAM-1. Various authors have reported that IL-17A has a role in the protection of organisms against extracellular bacteria and fungi due to the capacity of IL-17A to recruit neutrophils to the areas of infection, evidencing a pathological role in various models of autoimmune diseases, such as experimental autoimmune encephalitis and arthritis. The participation of IL-17A has also been described in the acute rejection of organ transplants and graft versus host disease. However, the greatest revolution in research with IL-17 happened in 2000, when it was proposed that IL-17 cannot be classified as Th1 or Th2, but rather, simply as a new lineage of IL-17-producing T-cells. These findings modified the previously established Th1/Th2 paradigm, leading to the definition of the CD3+ CD4+ Th17 cellular subtype and establishment of a new model to explain the origin of various immune events, as well as its implication in the graft versus host disease that is discussed in depth in this article.

Analysis of the cell surface expression of cytokine receptors using the surface protein biotinylation method

Cytokines are pleiotropic, low-molecular-weight proteins that regulate the immune responses to infection and inflammation. They stimulate the immune responses by binding to cytokine receptors on the cell plasma membrane. Thus, knowledge of the expression level of particular cytokine receptors on cell surface is crucial for understanding the cytokine function and regulation. One of the techniques to explore the membrane embedded cytokine receptors is cell surface biotinylation. Biotinylated surface proteins can be rapidly purified through the strong interaction between biotin and streptavidin. Here, we describe the procedure for surface biotinylation and purification of biotinylated cytokine receptors for further downstream analysis.

The role of interchain disulfide bond in a recombinant human interleukin-17A variant

Interleukin-17A (IL-17A) is the prototype of IL-17 family and has been implicated in the pathogenesis of a variety of autoimmune diseases. Therefore its structural and functional properties are of great medical interest. During our research on a recombinant human IL-17A (rhIL-17A) variant, four isoforms were obtained when it was refolded. While isoforms 1 and 2 represented non-covalent dimers, isoforms 3 and 4 were determined to be covalent dimers. All four isoforms were structurally similar by Circular Dichroism and fluorescence spectroscopy studies, but differential scanning calorimetry demonstrated thermal stability in the order of isoform 1=isoform 2<isoform 4<isoform 3. In addition, compared to covalent dimers (isoform 3 and 4), the non-covalent dimers (isoforms 1 and 2) are slightly less active in a receptor-binding assay but at least 5-fold less active in a cell-based assay.

[Role of Th17 cells and innate immunnity for the induction of autoimmune arthritis]

IL-17 secreting helper CD4 T cells (Th17 cells) contribute to a variety of autoimmune diseases such as rheumatoid arthritis. IL-17 acts on neutrophils, macrophages, fibroblasts, or osteocalsts to mediate chronic inflammation and destroy the cartilage. Recently, studies of the spontaneous models of arthritis revealed that activation of innate immunity, such as Toll like receptors, C-type lectin receptors, complement, or ATP induce IL-6 or IL-23 production from macrophages or dendritic cells, which triggers the differentiation of Th17 cells and induces autoimmune arthritis. Although the role of Th17 cells in human rheumatoid arthritis is still controversial, activation of innate immunity and induction of Th17 cells should be associated with the induction of arthritis at least in a part of RA patients. These studies will help elucidate the mechanism of arthritis induction and discover the therapeutic method to prevent it.

The role of glycogen synthase kinase 3-β in immunity and cell cycle: implications in esophageal cancer

Esophageal cancer (EC) is one of the most aggressive gastrointestinal malignancies, possessing an insidious onset and a poor prognosis. Numerous transcription factors and inflammatory mediators have been reported to play a pivotal role in the initiation and progression of this cancer. However, the specifics of the signaling network responsible for said factors, especially which elements are the critical regulators, are still being elucidated. Glycogen synthesis kinases 3 (GSK3)β was originally regarded as a kinase regulating glucose metabolism. Accumulating evidence demonstrated that it also played an essential role in a variety of cellular processes including proliferation, differentiation, inflammation, motility, and survival by regulating various transcription factors such as c-Jun, AP-1, β-catenin, CREB, and NF-κB. Aberrant regulation of GSK3β has been shown to promote cell growth in some cancers, while suppressing it in others, and thus may play an important role in the development of EC. This review will discuss our current understanding of GSK3β signaling, and its control of the expression and activation of various transcription factors that mediate the inflammatory response. We will also explore some of the known mediators of EC progression, and based on current literature, elucidate the potential roles and implications of GSK3 in this disease.

Recent progress in host immunity to avian coccidiosis: IL-17 family cytokines as sentinels of the intestinal mucosa

The molecular and cellular mechanisms leading to immune protection against coccidiosis are complex and include multiple aspects of innate and adaptive immunities. Innate immunity is mediated by various subpopulations of immune cells that recognize pathogen associated molecular patterns (PAMPs) through their pattern recognition receptors (PRRs) leading to the secretion of soluble factors with diverse functions. Adaptive immunity, which is important in conferring protection against subsequent reinfections, involves subtypes of T and B lymphocytes that mediate antigen-specific immune responses. Recently, global gene expression microarray analysis has been used in an attempt to dissect this complex network of immune cells and molecules during avian coccidiosis. These new studies emphasized the uniqueness of the innate immune response to Eimeria infection, and directly led to the discovery of previously uncharacterized host genes and proteins whose expression levels were modulated following parasite infection. Among these is the IL-17 family of cytokines. This review highlights recent progress in IL-17 research in the context of host immunity to avian coccidiosis.

Insulin and IGF1 enhance IL-17-induced chemokine expression through a GSK3B-dependent mechanism: a new target for melatonin's anti-inflammatory action

Obesity is a chronic inflammation with increased serum levels of insulin, insulin-like growth factor 1 (IGF1), and interleukin-17 (IL-17). The objective of this study was to test a hypothesis that insulin and IGF1 enhance IL-17-induced expression of inflammatory chemokines/cytokines through a glycogen synthase kinase 3β (GSK3B)-dependent mechanism, which can be inhibited by melatonin. We found that insulin/IGF1 and lithium chloride enhanced IL-17-induced expression of C-X-C motif ligand 1 (Cxcl1) and C-C motif ligand 20 (Ccl20) in the Gsk3b(+/+) , but not in Gsk3b(-/-) mouse embryonic fibroblast (MEF) cells. IL-17 induced higher levels of Cxcl1 and Ccl20 in the Gsk3b(-/-) MEF cells, compared with the Gsk3b(+/+) MEF cells. Insulin and IGF1 activated Akt to phosphorylate GSK3B at serine 9, thus inhibiting GSK3B activity. Melatonin inhibited Akt activation, thus decreasing P-GSK3B at serine 9 (i.e., increasing GSK3B activity) and subsequently inhibiting expression of Cxcl1 and Ccl20 that was induced either by IL-17 alone or by a combination of insulin and IL-17. Melatonin's inhibitory effects were only observed in the Gsk3b(+/+) , but in not Gsk3b(-/-) MEF cells. Melatonin also inhibited expression of Cxcl1, Ccl20, and Il-6 that was induced by a combination of insulin and IL-17 in the mouse prostatic tissues. Further, nighttime human blood, which contained high physiologic levels of melatonin, decreased expression of Cxcl1, Ccl20, and Il-6 in the PC3 human prostate cancer xenograft tumors. Our data support our hypothesis and suggest that melatonin may be used to dampen IL-17-mediated inflammation that is enhanced by the increased levels of insulin and IGF1 in obesity.

Cloning and characterization of goose interleukin-17A cDNA

Interleukin-17 (IL-17 or IL-17A) is a proinflammatory cytokine produced by activated T cells. IL-17A plays important roles in inflammation and host defense. In this study, the cDNA of the goose IL-17A (GoIL-17A) gene was cloned from thymocytes. Recombinant GoIL-17A (rGoIL-17A) was expressed using a baculovirus expression system and then biologically characterized. The complete open reading frame (ORF) of GoIL-17A contains 510 base pairs that encode 169 amino acid residues, including a 29-amino acid signal peptide and a single potential N-linked glycosylation site. This protein has a molecular weight of 18.9kDa. The amino acid sequence showed 95.9%, 84.6%, 45.0% and 38.4% similarity with the corresponding duck, chicken, rat, and human IL-17A sequences, respectively. The six conserved cysteine residues were also observed in GoIL-17A. A recombinant, mature form of GoIL-17A was produced and its biological activities in goose embryonic fibroblasts were investigated. RT-PCR analysis revealed a marked up-regulation of IL-6 and IL-8 mRNA expression in goose embryonic fibroblasts treated with 1-50 μg of rGoIL-17A for 12h. The GoIL-17A gene sequence and the biologically active recombinant protein may be useful for understanding the role of IL-17A in immune regulation.

Multiplex analyses of cytokine and chemokine release from the cultured fibroblast of nasal polyps: the effect of IL-17A

CONCLUSION

Our results demonstrate for the first time a potentially enhanced basal secretion of monocyte chemoattractant protein-1 (MCP-1) and interleukin (IL)-17A-stimulated secretion of IL-6 from nasal polyp fibroblasts, enhanced basal secretion of IL-6 from eosinophilic nasal polyp fibroblasts, and a remarkable up-regulation of IL-9 and granulocyte colony-stimulating factor (G-CSF) from nasal fibroblasts by IL-17A stimulation.

OBJECTIVES

The fibroblast, one of the main cell types making up nasal polyps, is thought to be a target cell of various cytokines.

METHODS

Subcultured fibroblasts were established from human polyp biopsy tissues. Simultaneous quantification of 27 kinds of cytokines and chemokines in culture supernatants in unstimulated and IL-17A-stimulated conditions was performed with a human multiplex cytokine assay system.

RESULTS

The IL-17A receptor was expressed at similar levels in all three groups. In the eosinophilic group, basal secretion levels of IL-6 were significantly higher than those in the control and non-eosinophilic groups. Basal secretion of MCP-1 in both the non-eosinophilic and eosinophilic groups was also higher than that of the control group. Both IL-9 and G-CSF secretion were remarkably enhanced by IL-17A stimulation in all three groups. The receptor-mediated response by IL-17A significantly up-regulated IL-6 release alone in the non-eosinophilic and eosinophilic groups as compared with the control group.

Identification of a soluble isoform of human IL-17RA generated by alternative splicing

IL-17RA, a member of the interleukin (IL)-17 receptor family, is a single membrane-spanning protein that ubiquitously expressed on the cell surface. IL-17RA transduces IL-17A, IL-17F, and IL-17A/F heterodimer-mediated signals by forming a complex with IL-17RC, and also signals the IL-17E (also known as IL-25) response in combination with IL-17RB (also known as IL-25R). Previously, soluble isoforms of human IL-17RC and IL-17RB have been reported, but the existence of a soluble isoform of human IL-17RA has remained unclear. Here, we report the identification of a soluble isoform of human IL-17RA at the mRNA and protein levels. Reverse transcribed PCR experiments showed that the IL-17RA variant is generated by spliced out of exon 11 encoding the transmembrane region in a variety of human tissues. The soluble IL-17RA isoform was detected in the culture media of human cell lines by Western blotting. The existence of the soluble IL-17RA isoform sheds new light on the regulation of IL-17RA mediated responses.

Molecular mechanisms and cell targets of Th17 cells in the gastrointestinal tract: an innate sense of adaptivity

T-helper (TH) 17 activation is crucial for protective immune responses against bacteria and fungi at mucosal surfaces, but it can also be implicated in the pathogenesis of several autoimmune and chronic inflammatory diseases, such as inflammatory bowel diseases (IBD). Although rapid progress was made elucidating induction and functional heterogeneity of Th17 responses, the underlying molecular effects of Th17 response including the most relevant different cell targets of Th17 cytokines remain poorly understood. Cytokines produced by Th17 cells have broad effects on both hematopoietic and nonhematopoietic cells and can act in synergy with various inflammatory factors. In this review, we will focus on the effects of Th17-derived cytokines in the gastrointestinal tract and discuss how Th17 responses can affect both innate and adaptive immunity and may contribute to the pathogenesis of inflammatory GI processes.

IL-17 cytokines in immunity and inflammation

Interleukin 17 (IL-17) and its closest relative, IL-17F, have recently drawn much attention in the field of immunology. IL-17 and IL-17F are expressed by a distinct type of T cells, T helper 17 cells and certain other lymphocytes. These cytokines play key regulatory roles in host defense and inflammatory diseases. In this review, we summarize the recent findings in IL-17 biology and the progress towards understanding the regulatory mechanisms of IL-17 expression and signaling mechanisms. This knowledge will benefit the development of novel immune modulators that enhance immunity to various infections and reduce inflammatory damage in infected patients.

IL-17 promotes neutrophil entry into tumor-draining lymph nodes following induction of sterile inflammation

Blood-borne neutrophils are excluded from entering lymph nodes across vascular portals termed high endothelial venules (HEVs) because of lack of expression of the CCR7 homeostatic chemokine receptor. Induction of sterile inflammation increases neutrophil entry into tumor-draining lymph nodes (TDLNs), which is critical for induction of antitumor adaptive immunity following treatments such as photodynamic therapy (PDT). However, the mechanisms controlling neutrophil entry into TDLNs remain unclear. Prior evidence that IL-17 promotes neutrophil emigration to sites of infection via induction of CXCL2 and CXCL1 inflammatory chemokines raised the question of whether IL-17 contributes to chemokine-dependent trafficking in TDLNs. In this article, we demonstrate rapid accumulation of IL-17-producing Th17 cells in the TDLNs following induction of sterile inflammation by PDT. We further report that nonhematopoietic expression of IL-17RA regulates neutrophil accumulation in TDLNs following induction of sterile inflammation by PDT. We show that HEVs are the major route of entry of blood-borne neutrophils into TDLNs through interactions of l-selectin with HEV-expressed peripheral lymph node addressin and by preferential interactions between CXCR2 and CXCL2 but not CXCL1. CXCL2 induction in TDLNs was mapped in a linear pathway downstream of IL-17RA-dependent induction of IL-1β. These results define a novel IL-17-dependent mechanism promoting neutrophil delivery across HEVs in TDLNs during acute inflammatory responses.

Pathological niche environment transforms dermal stem cells to keloid stem cells: a hypothesis of keloid formation and development

Keloid is a disease that is difficult to cure because of its high recurrence rate after chemotherapy or radiotherapy, therefore it is considered as a benign skin tumor. Tumor stem cells are proposed as the source for tumor development and post-therapy recurrence. Interestingly, keloid stem cells have also been discovered, which share some characters with those of skin progenitor cells. Keloid patients possess specific diathesis including genetic predisposition and gene mutation, abnormal levels of hormones, growth factors and cytokines, and strong inflammatory response. This article reviews related literatures and hypothesizes that keloid stem cells might be transformed from normal dermal progenitor cells in the pathological niche of keloid tissues. These keloid stem cells are highly self-renewal and drug resistant, and can sustain themselves by asymmetric division, and continually generate new keloid cells to replenish the cells killed by drugs or radiation, thus leading to over growth of keloid and high post-therapy recurrence rate.

IL-17 family: cytokines, receptors and signaling

The interleukin 17 (IL-17) family, a subset of cytokines consisting of IL-17A-F, plays crucial roles in host defense against microbial organisms and in the development of inflammatory diseases. Although IL-17A is the signature cytokine produced by T helper 17 (Th17) cells, IL-17A and other IL-17 family cytokines have multiple sources ranging from immune cells to non-immune cells. The IL-17 family signals via their correspondent receptors and activates downstream pathways that include NFκB, MAPKs and C/EBPs to induce the expression of anti-microbial peptides, cytokines and chemokines. The proximal adaptor Act1 is a common mediator during the signaling of all IL-17 cytokines so far and is thus involved in IL-17 mediated host defense and IL-17-driven autoimmune conditions. This review will give an overview and recent updates on the IL-17 family, the activation and regulation of IL-17 signaling as well as diseases associated with this cytokine family.

IL-17 family cytokines mediated signaling in the pathogenesis of inflammatory diseases

Inflammation is the immediate protective response of the body to pathogen invasions, allergen challenges, chemical exposures or physical injuries. Acute inflammation usually accompanies with transient infiltration of leukocytes, removal of danger signals and eventually tissue repair, while persistent and uncontrolled inflammation becomes a major stimulator in the progression of many chronic diseases in human, including autoimmune diseases, metabolic disorders and cancer. Interleukin (IL)-17 family is a recent classified subset of cytokines, playing critical roles in both acute and chronic inflammatory responses. In this review, we will summarize recent progresses on the signalings of this family cytokines and their impacts on the inflammatory responses or disorders.

The anaphase-promoting complex protein 5 (AnapC5) associates with A20 and inhibits IL-17-mediated signal transduction

IL-17 is the founding member of a family of cytokines and receptors with unique structures and signaling properties. IL-17 is the signature cytokine of Th17 cells, a relatively new T cell population that promotes inflammation in settings of infection and autoimmunity. Despite advances in understanding Th17 cells, mechanisms of IL-17-mediated signal transduction are less well defined. IL-17 signaling requires contributions from two receptor subunits, IL-17RA and IL-17RC. Mutants of IL-17RC lacking the cytoplasmic domain are nonfunctional, indicating that IL-17RC provides essential but poorly understood signaling contributions to IL-17-mediated signaling. To better understand the role of IL-17RC in signaling, we performed a yeast 2-hybrid screen to identify novel proteins associated with the IL-17RC cytoplasmic tail. One of the most frequent candidates was the anaphase promoting complex protein 7 (APC7 or AnapC7), which interacted with both IL-17RC and IL-17RA. Knockdown of AnapC7 by siRNA silencing exerted no detectable impact on IL-17 signaling. However, AnapC5, which associates with AnapC7, was also able to bind IL-17RA and IL-17RC. Moreover, AnapC5 silencing enhanced IL-17-induced gene expression, suggesting an inhibitory activity. Strikingly, AnapC5 also associated with A20 (TNFAIP3), a recently-identified negative feedback regulator of IL-17 signal transduction. IL-17 signaling was not impacted by knockdown of Itch or TAXBP1, scaffolding proteins that mediate A20 inhibition in the TNFα and IL-1 signaling pathways. These data suggest a model in which AnapC5, rather than TAX1BP1 and Itch, is a novel adaptor and negative regulator of IL-17 signaling pathways.

IL-17 in the rheumatologist's line of sight

Over the past decades, the identification of several new cytokines, including interleukin (IL)-17 and IL-23, and of new T helper cell subsets, including Th17 cells, has changed the vision of immunological processes. The IL-17/Th17 pathway plays a critical role during the development of inflammation and autoimmunity, and targeting this pathway has become an attractive strategy for a number of diseases. This review aims to describe the effects of IL-17 in the joint and its roles in the development of autoimmune and inflammatory arthritis. Furthermore, biotherapies targeting directly or indirectly IL-17 in inflammatory rheumatisms will be developed.

IL-17RA is essential for optimal localization of follicular Th cells in the germinal center light zone to promote autoantibody-producing B cells

Germinal centers (GCs) provide a microenvironment that promotes and regulates the interactions of B cells with follicular Th (TFH) cells. In this study, we show that there are significantly higher frequencies of CXCR5(+)ICOS(+) TFH cells in autoimmune BXD2 mice, and these cells express both IL-21R and IL-17RA. Although IL-17 and IL-21 are both important for the formation of spontaneous GCs and development of pathogenic autoantibodies, IL-21, but not IL-17, is required for the proper development of TFH cells in BXD2 mice. The total numbers of TFH cells and their ability to induce B cell responses in vitro were not affected by a deficiency of IL-17RA in BXD2-Il17ra(-/-) mice, the majority of CXCR5(+) TFH cells from BXD2-Il17ra(-/-) mice were, however, not localized in the GC light zone (LZ). Interruption of IL-17 signaling, either acutely by AdIL-17R:Fc or chronically by Il17ra(-/-), disrupted TFH-B interactions and abrogated the generation of autoantibody-forming B cells in BXD2 mice. IL-17 upregulated the expression of regulator of G-protein signaling 16 (RGS16) to promote the ability of TFH to form conjugates with B cells, which was abolished in TFH cells from BXD2-Rgs16(-/-) mice. The results suggests that IL-17 is an extrinsic stop signal that it acts on postdifferentiated IL-17RA(+) TFH to enable its interaction with responder B cells in the LZ niche. These data suggest a novel concept that TFH differentiation and its stabilization in the LZ are two separate checkpoints and that IL-21 and IL-17 act at each checkpoint to enable pathogenic GC development.

T helper 17 cells in airway diseases: from laboratory bench to bedside

T helper 17 (Th17) cytokines are now widely believed to be critical for the regulation of various chronic immune diseases. Investigations have revealed a significant role for IL-17 cytokines in regulating inflammation and modulating lung and airway structural cells in asthma and COPD. In this review, our current understanding of the role of Th17-associated cytokines in airway diseases is summarized. Therapeutic approaches targeting IL-17 during asthma and COPD are also discussed.

Galectin-1-mediated suppression of Pseudomonas aeruginosa-induced corneal immunopathology

Corneal infection with Pseudomonas aeruginosa leads to a severe immunoinflammatory lesion, often causing vision impairment and blindness. Although past studies have indicated a critical role for CD4(+) T cells, particularly Th1 cells, in corneal immunopathology, the relative contribution of recently discovered Th17 and regulatory T cells is undefined. In this study, we demonstrate that after corneal P. aeruginosa infection, both Th1 and Th17 cells infiltrate the cornea with increased representation of Th17 cells. In addition to Th1 and Th17 cells, regulatory T cells also migrate into the cornea during early as well as late stages of corneal pathology. Moreover, using galectin-1 (Gal-1), an immunomodulatory carbohydrate-binding molecule, we investigated whether shifting the balance among various CD4(+) T cell subsets can modulate P. aeruginosa-induced corneal immunopathology. We demonstrate in this study that local recombinant Gal-1 (rGal-1) treatment by subconjunctival injections significantly diminishes P. aeruginosa-mediated corneal inflammation through multiple mechanisms. Specifically, in our study, rGal-1 treatment significantly diminished corneal infiltration of total CD45(+) T cells, neutrophils, and CD4(+) T cells. Furthermore, rGal-1 treatment significantly reduced proinflammatory Th17 cell response in the cornea as well as local draining lymph nodes. Also, rGal-1 therapy promoted anti-inflammatory Th2 and IL-10 response in secondary lymphoid organs. Collectively, our results indicate that corneal P. aeruginosa infection induces a strong Th17-mediated corneal pathology, and treatment with endogenously derived protein such as Gal-1 may be of therapeutic value for the management of bacterial keratitis, a prevalent cause of vision loss and blindness in humans worldwide.

The deubiquitinase A20 mediates feedback inhibition of interleukin-17 receptor signaling

The proinflammatory cytokine interleukin-17 (IL-17) is the signature cytokine of the T helper 17 (TH17) subset of CD4(+) T cells, and antibodies targeting IL-17 or the IL-17 receptor (IL-17R) show clinical efficacy in several autoimmune diseases. Although important for protective immunity against microorganisms, IL-17 causes collateral damage in inflammatory settings. TNFAIP3 encodes the deubiquitinase A20 and is genetically linked to numerous autoimmune syndromes. A20, a potent inhibitor of tumor necrosis factor-α signaling, removes ubiquitin from signaling intermediates upstream of nuclear factor κB (NF-κB), thereby dampening NF-κB-mediated inflammation. We demonstrated that IL-17 stimulates TNFAIP3 expression. Enhanced IL-17-mediated induction of genes encoding proinflammatory factors, including IL-6 and various chemokines, occurred upon knockdown of A20 with short inhibitory RNA or in A20(-/-) cells. A20 associated with the E3 ubiquitin ligase TRAF6 (tumor necrosis factor receptor-associated factor 6) in an IL-17-dependent manner and restricted the IL-17-dependent activation of NF-κB and mitogen-activated protein kinases. A20 interacted directly with the distal domain of IL-17RA, a previously defined inhibitory domain. Together, these data describe a mechanism of restraining IL-17 signaling and reveal an aspect of A20 activity that may help to explain its role in autoimmunity in humans.

Targeting interleukin-17 in patients with active rheumatoid arthritis: rationale and clinical potential

Clinical and experimental evidence suggest that interleukin-17A (IL-17A; also known as IL-17) is an attractive therapeutic target in rheumatoid arthritis (RA). Rheumatoid synovial tissue produces IL-17A, which causes cartilage and bone degradation in synovial and bone explants. Overexpression of IL-17A induces synovial inflammation and joint destruction in animal RA models. These effects are attenuated in IL-17A-deficient animals and by agents that block IL-17A. Serum IL-17A levels and, to a greater extent, synovial fluid IL-17A levels are elevated in many patients with RA. In some RA cohorts, higher IL-17A levels have been associated with a more severe clinical course. Several IL-17A blockers, including the anti-IL-17A monoclonal antibodies secukinumab and ixekizumab, and the anti-IL-17 receptor subunit A monoclonal antibody brodalumab have been evaluated in phase II clinical trials. Of these, secukinumab is the most advanced with respect to clinical evaluation in RA, with phase III trials ongoing in patients on background methotrexate who had inadequate responses to previous tumor necrosis factor blocker therapy.

Neutrophils are essential as a source of IL-17 in the effector phase of arthritis

OBJECTIVE

Th17 has been shown to have a pivotal role in the development of arthritis. However, the role of IL-17 in the T cell-independent effector phase has not fully been examined. We investigated whether IL-17 is involved in the effector phase of arthritis by using K/BxN serum-induced arthritis model.

METHODS

K/BxN serum was transferred into IL-17 knockout (KO) mice, SCID mice and their control mice, and arthritis was evaluated over time. In order to clarify the source of IL-17 in the effector phase, neutrophils or CD4+ T cells collected from IL-17 KO or control mice were injected into IL-17 KO recipient mice together with K/BxN serum. To examine if neutrophils secrete IL-17 upon stimulation, neutrophils were stimulated with immune complex in vitro and IL-17 in the supernatant was measured by ELISA.

RESULTS

K/BxN serum-induced arthritis was much less severe in IL-17 KO mice than in WT mice. Since K/BxN serum-transferred SCID mice developed severe arthritis with high serum IL-17 concentration, we speculated neutrophils are the responsible player as an IL-17 source. When wild type (WT) but not IL-17 KO neutrophils were co-injected with K/BxN serum into IL-17 KO mice, arthritis was exacerbated, whereas co-injection of WT CD4+ T cells had no effect. In vitro, stimulation of neutrophils with immune complex caused IL-17 secretion.

CONCLUSIONS

Neutrophils are essential as a source of IL-17 in the effector phase of arthritis. The trigger of secreting IL-17 from neutrophils may be immune complex.

IL-22 exacerbates the severity of CVB3-induced acute viral myocarditis in IL-17A-deficient mice

Interleukin (IL)-22 has either proinflammatory or tissue‑protective properties, depending on the nature of the affected tissue and the local cytokine milieu, including the presence or absence of IL-17A co-expression. We have previously demonstrated that IL-22 has critical anti-inflammatory and antiviral roles in mice with coxsackievirus B3 (CVB3)‑induced acute viral myocarditis (AVMC) in the presence of IL-17A. However, whether IL-17A determines the function of IL-22 in AVMC remains unknown. Therefore, the present study, in continuation of our previous investigations, aimed to determine whether IL-22 plays a distinctly different role in the absence of IL-17A in AVMC by using IL-17A-deficient mice. Results demonstrated that the neutralization of IL-22 in IL-17A‑deficient mice alleviated the severity of myocarditis. This was demonstrated by the lower pathological scores of heart sections and ratios of heart weight/body weight (HW/BW), reduced production of activator of transcription 3 (STAT3) and proinflammatory cytokines TNF-α and IL-6, followed by increased viral replication and decreased levels of the antiviral cytokine IFN-γ. Furthermore, the correlation between cardiac CVB3 RNA and IL-22 mRNA or IFN-γ mRNA was negative. In conclusion, IL-22 exacerbated the severity of AVMC and restrained viral replication in the absence of IL-17A. Spleen lymphocytes cultured with recombinant IL-17 (rIL-17) increased the production of IL-22. Combined with our previous data, these results indicate that IL-17A is not involved in regulating the antiviral role, however, may mediate the tissue-protective versus pathogenic properties of IL-22 in CVB3-induced AVMC in mice.

Patients with cystic fibrosis have inducible IL-17+IL-22+ memory cells in lung draining lymph nodes

BACKGROUND

IL-17 is an important cytokine signature of the TH differentiation pathway TH17. This T-cell subset is crucial in mediating autoimmune disease or antimicrobial immunity in animal models, but its presence and role in human disease remain to be completely characterized.

OBJECTIVE

We set out to determine the frequency of TH17 cells in patients with cystic fibrosis (CF), a disease in which there is recurrent infection with known pathogens.

METHODS

Explanted lungs from patients undergoing transplantation or organ donors (CF samples=18; non-CF, nonbronchiectatic samples=10) were collected. Hilar nodes and parenchymal lung tissue were processed and examined for TH17 signature by using immunofluorescence and quantitative real-time PCR. T cells were isolated and stimulated with antigens from Pseudomonas aeruginosa and Aspergillus species. Cytokine profiles and staining with flow cytometry were used to assess the reactivity of these cells to antigen stimulation.

RESULTS

We found a strong IL-17 phenotype in patients with CF compared with that seen in control subjects without CF. Within this tissue, we found pathogenic antigen-responsive CD4+IL-17+ cells. There were double-positive IL-17+IL-22+ cells [TH17(22)], and the IL-22+ population had a higher proportion of memory characteristics. Antigen-specific TH17 responses were stronger in the draining lymph nodes compared with those seen in matched parenchymal lungs.

CONCLUSION

Inducible proliferation of TH17(22) with memory cell characteristics is seen in the lungs of patients with CF. The function of these individual subpopulations will require further study regarding their development. T cells are likely not the exclusive producers of IL-17 and IL-22, and this will require further characterization.

Biologic agents in experimental autoimmune uveitis

Experimental uveitis models were developed in an effort to elucidate the pathogenesis of human uveitis. The therapeutic effects of numerous anti-inflammatory agents including corticosteroids and immunomodulatory agents including biologic response modifiers have been investigated in both experimental and human uveitis. Monoclonal antibodies to tumor necrosis factor alpha and anti-interleukins, among others, demonstrate efficacy and are employed in the treatment of uveitis refractory to conventional immunomodulatory agents.

IL-23/IL-17A axis correlates with the nitric oxide pathway in inflammatory bowel disease: immunomodulatory effect of retinoic acid

Inflammatory bowel diseases (IBDs) are chronic inflammatory diseases of the gastrointestinal tract, which are clinically present as 1 of the 2 disorders, Crohn's disease (CD) or ulcerative colitis (UC) (Rogler 2004). The immune dysregulation in the intestine plays a critical role in the pathogenesis of IBD, involving a wide range of molecules, including cytokines. The aim of this work was to study the involvement of T-helper 17 (Th17) subset in the bowel disease pathogenesis by the nitric oxide (NO) pathway in Algerian patients with IBD. We investigated the correlation between the proinflammatory cytokines [(interleukin (IL)-17, IL-23, and IL-6] and NO production in 2 groups of patients. We analyzed the expression of messenger RNAs (mRNAs) encoding Th17 cytokines, cytokine receptors, and NO synthase 2 (NOS2) in plasma of the patients. In the same way, the expression of p-signal transducer and activator of transcription 3 (STAT3) and NOS2 was measured by immunofluorescence and immunohistochemistry. We also studied NO modulation by proinflammatory cytokines (IL-17A, IL-6, tumor necrosis factor α, or IL-1β) in the presence or absence of all-trans retinoic acid (At RA) in peripheral blood mononuclear cells (PBMCs), monocytes, and in colonic mucosa cultures. Analysis of cytokines, cytokine receptors, and NOS2 transcripts revealed that the levels of mRNA transcripts of the indicated genes are elevated in all IBD groups. Our study shows a significant positive correlation between the NO and IL-17A, IL-23, and IL-6 levels in plasma of the patients with IBD. Interestingly, the correlation is significantly higher in patients with active CD. Our study shows that both p-STAT3 and inducible NOS expression was upregulated in PBMCs and colonic mucosa, especially in patients with active CD. At RA downregulates NO production in the presence of proinflammatory cytokines for the 2 groups of patients. Collectively, our study indicates that the IL-23/IL-17A axis plays a pivotal role in IBD pathogenesis through the NO pathway.