Cutting edge: IL-17F, a novel cytokine selectively expressed in activated T cells and monocytes, regulates angiogenesis and endothelial cell cytokine production

IL-17A and IL-17F genes variants and susceptibility to childhood asthma in Tunisia

OBJECTIVES

IL-17A and IL-17F are new pro-inflammatory cytokines implicated in neutrophilic inflammation and thus, involved in the pathogenesis of asthma. We investigated the possible association among asthma and IL-17A -197G/A (rs2275913), IL-17F 7488A/G (rs763780) and IL-17F 7383A/G (rs2397084).

METHODS

The study was performed in 171 patients with asthma (mean age 9.5 years, 105 boys, and 66 girls) and 171 healthy individuals matched with patients in age and sex. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to detect genes' polymorphisms.

RESULTS

IL-17A -197G/A and IL-17F 7383A/G were associated with asthma in children (p = 0.008, p = 0.001, respectively). No association was found with IL-17F 7488A/G polymorphism. Haplotype analysis revealed a significant association between GA and AG haplotypes and asthma (p = 0.004, p = 0.02). When patients were stratified according to the atopic status, no significant association was detected with any of the three studied variants.

CONCLUSION

Our results suggested that SNPs in IL-17A and IL-17F confer susceptibility to childhood asthma in Tunisia.

The transcriptomic response of rat hepatic stellate cells to endotoxin: implications for hepatic inflammation and immune regulation

With their location in the perisinusoidal space of Disse, hepatic stellate cells (HSCs) communicate with all of the liver cell types both by physical association (cell body as well as cytosolic processes penetrating into sinusoids through the endothelial fenestrations) and by producing several cytokines and chemokines. Bacterial lipopolysaccharide (LPS), circulating levels of which are elevated in liver diseases and transplantation, stimulates HSCs to produce increased amounts of cytokines and chemokines. Although recent research provides strong evidence for the role of HSCs in hepatic inflammation and immune regulation, the number of HSC-elaborated inflammatory and immune regulatory molecules may be much greater then known at the present time. Here we report time-dependent changes in the gene expression profile of inflammatory and immune-regulatory molecules in LPS-stimulated rat HSCs, and their validation by biochemical analyses. LPS strongly up-regulated LPS-response elements (TLR2 and TLR7) but did not affect TLR4 and down-regulated TLR9. LPS also up-regulated genes in the MAPK, NFκB, STAT, SOCS, IRAK and interferon signaling pathways, numerous CC and CXC chemokines and IL17F. Interestingly, LPS modulated genes related to TGFβ and HSC activation in a manner that would limit their activation and fibrogenic activity. The data indicate that LPS-stimulated HSCs become a major cell type in regulating hepatic inflammatory and immunological responses by altering expression of numerous relevant genes, and thus play a prominent role in hepatic pathophysiology including liver diseases and transplantation.

Role of TH17 cytokines in the control of colorectal cancer

Immune/inflammatory cells infiltrate almost all human solid tumors and affect all stages of carcinogenesis as they produce different cytokine subsets. The overproduction of T_H17 cytokines marks the early stages of colorectal carcinoma (CRC) and negatively influences the prognosis of CRC patients. Studies with murine models of CRC have delineated the mechanisms by which T_H17 cytokines, notably, interleukin (IL)-17A, IL-17F, IL-21, and IL-22, regulate oncogenesis and tumor progression, paving the way to the development of novel anticancer drugs. In this review article, we discuss experimental data supporting the role of T_H17 cytokines in the modulation of colorectal tumorigenesis.

Angiogenesis in rheumatoid arthritis is fostered directly by toll-like receptor 5 ligation and indirectly through interleukin-17 induction

OBJECTIVE

To examine the impact of Toll-like receptor 5 (TLR-5) on endothelial cell function in rheumatoid arthritis (RA) and vascularization in collagen-induced arthritis (CIA).

METHODS

Endothelial cell migration and tube formation assays were used to demonstrate the direct role of TLR-5 ligation in angiogenesis. Mice with CIA were treated with the TLR-5 agonist flagellin to document the effect of TLR-5 ligation in RA pathology. Vascularization in CIA was determined by immunohistochemical analysis and determination of cytokine levels in ankle joints. Spleen Th17 cells and joint interleukin-17 (IL-17) were quantified by fluorescence-activated cell sorting analysis and enzyme-linked immunosorbent assay. The development of Th17 cells induced by TLR-5 ligation was validated in RA peripheral blood mononuclear cells.

RESULTS

Ligation of TLR-5 to endogenous ligands expressed in RA synovial fluid contributed to endothelial cell infiltration and tube formation. Furthermore, treatment with flagellin after the onset of CIA exacerbated joint inflammation; in contrast, inflammation in control mice remained at a plateau phase. We showed that TLR-5-enhanced disease severity was attributable to Th17 cell differentiation and joint vascularization in CIA. Examination of the underlying mechanism using RA peripheral blood mononuclear cells documented that ligation of TLR-5 in myeloid cells and production of Th17-promoting cytokines were necessary for Th17 cell polarization. Additionally, we demonstrated that blockade of the IL-17 cascade markedly reduced endothelial cell migration activated by flagellin-conditioned medium, suggesting that TLR-5 ligation can mediate RA angiogenesis either directly by attracting endothelial cells or indirectly by fostering Th17 cell development.

CONCLUSION

Our data demonstrate a novel role for TLR-5 in RA angiogenesis; thus, TLR-5 may be a promising new target for RA treatment.

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.

Regulation of IL-17 family members by adrenal hormones during experimental sepsis in mice

Severe sepsis is a life-threatening disease that causes major morbidity and mortality. Catecholamines and glucocorticoids often have been used for the treatment of sepsis. Several recent studies have suggested a potential role of IL-17 during the development and progression of sepsis in small animal models. In this study, the cross-talk of catecholamines and glucocorticoids with members of the IL-17 family was investigated during sepsis in C57BL/6 mice. The concentrations in plasma of IL-17A, IL-17F, and the IL-17AF heterodimer all were increased greatly in mice after endotoxemia or cecal ligation and puncture as compared with sham mice. Surprisingly, when compared with IL-17A (487 pg/mL), the concentrations of IL-17F (2361 pg/mL) and the heterodimer, IL-17AF (5116 pg/mL), were much higher 12 hours after endotoxemia. After surgical removal of the adrenal glands, mice had much higher mortality after endotoxemia or cecal ligation and puncture. The absence of endogenous adrenal gland hormones (cortical and medullary) was associated with 3- to 10-fold higher concentrations of IL-17A, IL-17F, IL-17AF, and IL-23. The addition of adrenaline, noradrenaline, hydrocortisone, or dexamethasone to lipopolysaccharide-activated peritoneal macrophages dose-dependently suppressed the expression and release of IL-17s. The production of IL-17s required activation of c-Jun-N-terminal kinase, which was antagonized by both catecholamines and glucocorticoids. These data provide novel insights into the molecular mechanisms of immune modulation by catecholamines and glucocorticoids during acute inflammation.

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.

Barriers to preclinical investigations of anti-dengue immunity and dengue pathogenesis

Dengue virus (DENV) is a human pathogen that causes severe and potentially fatal disease in millions of individuals each year. Immune-mediated pathology is thought to underlie many of the complications of DENV infection in humans, but the notable limitations of the available animal models have impeded our knowledge of the interactions between DENV and the immune system. In this Opinion article, we discuss some of the controversies in the field of dengue research relating to the interaction between DENV and the mammalian host. We highlight key barriers hindering our understanding of the molecular pathogenesis of DENV and offer suggestions for the most effective ways in which the role of the immune system in the protection from, and pathology of, DENV infection can be addressed experimentally.

Genetic polymorphisms of interleukin 17A and interleukin 17F and their association with inflammatory bowel disease in a Chinese Han population

OBJECTIVE

Interleukin-17A and interleukin-17F (IL-17A and IL-17F) are candidate genes for chronic inflammatory disease. We investigated the association between IL17A/F gene polymorphisms and susceptibility to and clinical features of inflammatory bowel disease (IBD).

METHODS

A total of 270 ulcerative colitis (UC) patients, 82 Crohn's disease (CD) patients and 268 healthy controls were recruited in this study. Genomic DNA was extracted and analyzed for IL17A/F gene polymorphisms using ligase detection reaction allelic technology.

RESULTS

Compared to the controls, the mutant allele C for IL17F rs763780 was significantly more common in CD patients [14.0 vs 8.4 %, P = 0.033, odds ratio (OR) 1.18, 95 % confidence interval (CI) 1.41-3.04] and was associated with the disease lesion location. This variant of IL17F rs763780 also had a weak correlation with the age of UC onset (P = 0.05, OR 0.97, 95 % CI 0.94-1.00). The IL17A (rs2275913, G-197A) variant had a weak association with the severity of disease: patients with the mutant allele A tended to suffer mild active UC. The haplotype (GGTT) of IL17A formed with four single nucleotide polymorphisms (rs2275913, rs8193037, rs8193038, and rs3804513) was associated with an increased risk of UC (P = 0.034, OR 4.58, 95 % CI 1.54-13.64).

CONCLUSIONS

The IL17F (rs763780, 7488T/C) variant was associated with an increased risk for the development of CD, and affected some clinical features of UC and CD. The IL17A (rs2275913, G-197A) variant had a weak association with the severity of UC. There was a risk haplotype in IL17A which could increase the risk of UC.

Th17 cytokines induce pro-fibrotic cytokines release from human eosinophils

Background

Subepithelial fibrosis is one of the most critical structural changes affecting bronchial airway function during asthma. Eosinophils have been shown to contribute to the production of pro-fibrotic cytokines, TGF-β and IL-11, however, the mechanism regulating this process is not fully understood.

Objective

In this report, we investigated whether cytokines associated with inflammation during asthma may induce eosinophils to produce pro-fibrotic cytokines.

Methods

Eosinophils were isolated from peripheral blood of 10 asthmatics and 10 normal control subjects. Eosinophils were stimulated with Th1, Th2 and Th17 cytokines and the production of TGF-β and IL-11 was determined using real time PCR and ELISA assays.

Results

The basal expression levels of eosinophil derived TGF-β and IL-11 cytokines were comparable between asthmatic and healthy individuals. Stimulating eosinophils with Th1 and Th2 cytokines did not induce expression of pro-fibrotic cytokines. However, stimulating eosinophils with Th17 cytokines resulted in the enhancement of TGF-β and IL-11 expression in asthmatic but not healthy individuals. This effect of IL-17 on eosinophils was dependent on p38 MAPK activation as inhibiting the phosphorylation of p38 MAPK, but not other kinases, inhibited IL-17 induced pro-fibrotic cytokine release.

Conclusions

Th17 cytokines might contribute to airway fibrosis during asthma by enhancing production of eosinophil derived pro-fibrotic cytokines. Preventing the release of pro-fibrotic cytokines by blocking the effect of Th17 cytokines on eosinophils may prove to be beneficial in controlling fibrosis for disorders with IL-17 driven inflammation such as allergic and autoimmune diseases.

TH17 and TH22 cells: a confusion of antimicrobial response with tissue inflammation versus protection

Substantial progress in understanding mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumors, organ transplantation, chronic infections, and pregnancy is in an exciting developmental phase that might lead to a variety of targeted therapeutic approaches. Recent progress in the interaction between immune/inflammatory cell subsets through cytokines, particularly the extension of the knowledge on reciprocal regulation and counterbalance between subsets of T(H)1, T(H)2, T(H)9, T(H)17, T(H)22, T follicular helper cells and different subsets of regulatory T cells, as well as corresponding and co-orchestrating B-cell, natural killer cell, dendritic cell, and innate lymphoid cell subsets, offers new possibilities for immune intervention. Studies on new subsets confirm the important role of T cells in the instruction of tissue cells and also demonstrate the important role of feedback regulation for the polarization toward distinct T-cell subsets. T(H)17 and T(H)22 cells are 2 emerging T(H) cell subsets that link the immune response to tissue inflammation; IL-17A and IL-17F and IL-22 are their respective prototype cytokines. Although both cytokines play roles in immune defense to extracellular bacteria, IL-17 augments inflammation, whereas IL-22 plays a tissue-protective role. This review focuses on current knowledge on T(H)17 and T(H)22 cells and their role in inflammation, with special focus on the mechanisms of their generation and driving and effector cytokines, as well as their role in host defense, autoimmunity, and allergic diseases.

IL-17A in human respiratory diseases: innate or adaptive immunity? Clinical implications

Since the discovery of IL-17 in 1995 as a T-cell cytokine, inducing IL-6 and IL-8 production by fibroblasts, and the report of a separate T-cell lineage producing IL-17(A), called Th17 cells, in 2005, the role of IL-17 has been studied in several inflammatory diseases. By inducing IL-8 production and subsequent neutrophil attraction towards the site of inflammation, IL-17A can link adaptive and innate immune responses. More specifically, its role in respiratory diseases has intensively been investigated. We here review its role in human respiratory diseases and try to unravel the question whether IL-17A only provides a link between the adaptive and innate respiratory immunity or whether this cytokine might also be locally produced by innate immune cells. We furthermore briefly discuss the possibility to reduce local IL-17A production as a treatment option for respiratory diseases.

Interleukin-17 causes Rho-kinase-mediated endothelial dysfunction and hypertension

AIMS

Elevated levels of pro-inflammatory cytokine interleukin-17A (IL-17) are associated with hypertensive autoimmune diseases; however, the connection between IL-17 and hypertension is unknown. We hypothesized that IL-17 increases blood pressure by decreasing endothelial nitric oxide production.

METHODS AND RESULTS

Acute treatment of endothelial cells with IL-17 caused a significant increase in phosphorylation of the inhibitory endothelial nitric oxide (NO) synthase residue threonine 495 (eNOS Thr495). Of the kinases known to phosphorylate eNOS Thr495, only inhibition of Rho-kinase prevented the IL-17-induced increase. IL-17 caused a threefold increase in the Rho-kinase activator RhoA, and this was prevented by an IL-17 neutralizing antibody. In isolated mouse aortas, IL-17 significantly increased eNOS Thr495 phosphorylation, induced RhoA expression, and decreased NO-dependent relaxation responses, all of which were prevented by either an IL-17 neutralizing antibody or inhibition of Rho-kinase. In mice, IL-17 treatment for 1 week significantly increased systolic blood pressure and this was associated with decreased aortic NO-dependent relaxation responses, increased eNOS Thr495 phosphorylation, and increased RhoA expression. Inhibition of Rho-kinase prevented the hypertension caused by IL-17.

CONCLUSION

These data demonstrate that IL-17 activates RhoA/Rho-kinase leading to endothelial dysfunction and hypertension. Inhibitors of IL-17 or Rho-kinase may prove useful as anti-hypertensive drugs in IL-17-associated autoimmune diseases.

Cloning and characterization of rainbow trout interleukin-17A/F2 (IL-17A/F2) and IL-17 receptor A: expression during infection and bioactivity of recombinant IL-17A/F2

Lower vertebrates have been found to possess genes that have similar homology to both interleukin (IL)-17A and IL-17F, which have been termed IL-17A/F. In fish species, several of these genes can be present, but, to date, very little is known about their functional activity. This article describes the discovery and sequence analysis of a rainbow trout (Oncorhynchus mykiss) IL-17A/F2 molecule and an IL-17RA receptor. In addition, the bioactivity of the trout IL-17A/F2 is investigated for the first time in any species. The predicted IL-17A/F2 and IL-17RA proteins consist of 146 and 966 amino acids (aa), respectively, with both molecules containing conserved family motifs. Expression analysis revealed high constitutive expression of trout IL-17A/F2 in mucosal tissues from healthy fish, suggesting a potential role in mucosal immunity. When the modulation of IL-17A/F2 and IL-17RA in vitro was analyzed, it was observed that the two molecules were similarly affected. The expression of IL-17A/F2 was also induced in head kidney during bacterial, parasitic, and viral infections, revealing a possible function in defense against such pathogens. However, downregulation of IL-17RA was seen in some tissues and infections. The recombinant IL-17A/F2 protein was produced in Escherichia coli and was found to affect the expression of an antimicrobial peptide and the proinflammatory cytokines IL-6 and IL-8 in splenocytes. Consistent with mammalian IL-17 homologues, our expression and bioactivity results imply that trout IL-17A/F2 plays an important role in promoting inflammatory and host innate immune responses directed against different pathogen groups.

Chicken IL-17F: identification and comparative expression analysis in Eimeria-infected chickens

Interleukin-17F (IL-17F) is a proinflammatory cytokine, which plays an important role in gut homeostasis. A full-length chicken IL-17F (chIL-17F) cDNA with a 510-bp coding region was identified from ConA-activated chicken splenic lymphocytes. ChIL-17F shares 53% amino acid sequence identity with the previously described chicken IL-17 (chIL-17A) and 38-43% with mammalian homologues. The locus harboring chIL-17 and chIL-17F displayed inverted order compared to those of mammals. ChIL-17F transcript expression was high in lymphoblast cell line CU205 and at moderate levels in small and large intestines and liver. ChIL-17F and chIL-17 expression profiles were examined by quantitative real-time RT-PCR in mitogen-stimulated splenic lymphocytes and intestinal areas affected by Eimeria maxima and Eimeria tenella infections. Expression levels of chIL-17F, like chIL-17, were elevated in mitogen-activated splenic lymphocytes. ChIL-17F, but not chIL-17, expression was upregulated in intestinal tissues affected by E. maxima and E. tenella infections. Recombinant chIL-17F biological activities were similar to that of chIL-17 in primary chicken embryonic fibroblasts. These results suggest that chIL-17F is a unique member of the IL-17 family of cytokines.

Epigenetics, autoimmunity and hematologic malignancies: a comprehensive review

The relationships between immunological dysfunction, loss of tolerance and hematologic malignancies have been a focus of attention in attempts to understand the appearance of a higher degree of autoimmune disease and lymphoma in children with congenital immunodeficiency. Although multiple hypotheses have been offered, it is clear that stochastic processes play an important role in the immunopathology of these issues. In particular, accumulating evidence is defining a role of epigenetic mechanisms as being critical in this continuous spectrum between autoimmunity and lymphoma. In this review, we focus attention predominantly on the relationships between T helper 17 (Th17) and T regulatory populations that alter local microenvironments and ultimately the expression or transcription factors involved in cell activation and differentiation. Abnormal expression in any of the molecules involved in Th17 and/or Treg development alter immune homeostasis and in genetically susceptible hosts may lead to the appearance of autoimmunity and/or lymphoma. These observations have clinical significance in explaining the discordance of autoimmunity in identical twins. They are also particularly important in the relationships between primary immune deficiency syndromes, immune dysregulation and an increased risk of lymphoma. Indeed, defining the factors that determine epigenetic alterations and their relationships to immune homeostasis will be a challenge greater or even equal to the human genome project.

A distinct regulatory role of Th17 cytokines IL-17A and IL-17F in chemokine secretion from lung microvascular endothelial cells

Th17 cytokines IL-17A and IL-17F play a critical role in the activation and recruitment of neutrophils at airway inflammation mainly through the induction of CXC chemokines in the lungs. Vascular endothelial cells belong to the category of major CXC chemokine-producing cells. However, until now, the precise role of Th17 cytokines in CXC chemokine secretion in lung microvascular endothelial cells (LMVECs) has not been fully elucidated. In this study, we examined the biological effects of Th17 cytokines IL-17A and IL-17F on CXCL1, CXCL5, and CXCL8 release in LMVECs. Both IL-17 receptor A (IL-17RA) and IL-17RC are expressed on the surface of LMVECs. In contrast to IL-17F, IL-17A significantly upregulated CXCL1 mRNA expression and protein release, whereas both IL-17A and IL-17F did not have the ability to induce CXCL5 and CXCL8 secretion in LMVECs. IL-17A and IL-17F displayed positive regulatory effects on IL-1β-induced CXCL1, CXCL5, and CXCL8 secretion. On the other hand, IL-17A enhanced the upregulating effect of TNF-α on CXCL1, CXCL5, and CXCL8 release, whereas IL-17F had a negative regulatory effect on TNF-α-mediated secretion. Th2 cytokines IL-4 and IL-13 showed an inhibitory effect on IL-1β plus IL-17A-induced CXCL1, CXCL5, and CXCL8 secretion, but displayed a positive regulatory effect on TNF-α plus IL-17A-induced secretion. These results provide evidence that Th17 cytokines IL-17A and IL-17F have a distinct regulatory role in CXCL1, CXCL5, and CXCL8 expression in LMVECs stimulated either with IL-1β or with TNF-α. Our findings also suggest that CXC chemokine secretion in LMVECs may be complicatedly regulated by Th17 cytokines, Th2 cytokines, and macrophage-associated cytokines in pathological conditions such as bronchial asthma.

Development of a High-Throughput Cell-Based Assay for Identification of IL-17 Inhibitors

Human interleukin 17 (IL-17) is a proinflammatory cytokine derived mainly from activated T cells. Extensive evidence points to a significant role of IL-17 in many autoimmune and infectious diseases, as well as tumorigenesis and transplant rejection, and suggests that targeting IL-17 could be a promising therapeutic strategy. Robust cell-based assays would thus be essential for lead identification and the optimization of therapeutic candidates. Herein, we report a well-characterized two-step assay, consisting of (a) in vitro activation and stimulation of CD4+ T lymphocytes by a defined complex of antibodies and cytokines, leading to T helper 17 (Th17) cell differentiation and IL-17 production, and (b) IL-17 quantification in cell supernatants using a homogeneous time-resolved fluorescence (HTRF) assay. The system was optimized for and shown to be reliable in high-throughput compatible 96- and 384-well plate formats. The assay is robust (Z′ > 0.5) and simple to perform, yields a stable response, and allows for sufficient discrimination of positive (IL-17–producing cells) and negative controls (uninduced cells). The assay was validated by performing dose-response testing of rapamycin and cyclosporine A, which had previously been reported to inhibit IL-17, and determining, for the first time, their in vitro potencies (IC50s of 80 ± 23 pM and 223 ± 52 nM, respectively). Also, IKK 16, a selective small-molecule inhibitor of IκB kinase, was found to inhibit IL-17 production, with an IC50 of 315 ± 79 nM.

Modulation of innate host factors by Mycobacterium avium complex in human macrophages includes interleukin 17

BACKGROUND

Although opportunistic infections due to Mycobacterium avium complex (MAC) have been less common since the introduction of highly active antiretroviral therapy, globally, human immunodeficiency virus-1 (HIV-1)-positive patients remain predisposed to these infections. Absence of a properly functioning acquired immune response allows MAC persistence within macrophages localized in lymph nodes coinfected with HIV and MAC. Although a deficiency in interferon γ appears to play a part in the ability of MAC to deflect the macrophage-associated antimicrobial attack, questions about this process remain. Our study examines the ability of MAC to regulate interleukin 17 (IL-17), a proinflammatory cytokine involved in host cell recruitment.

METHODS

Coinfected lymph nodes were examined for IL-17 by immunohistochemical analysis. In vitro, macrophages exposed to mycobacteria were evaluated for transcription activities, proteins, and signaling pathways responsible for IL-17 expression. Infected macrophages were also analyzed for expression of interleukin 21 (IL-21) and negative regulators of immune responses.

RESULTS

Infection of macrophages triggered synthesis of IL-17, correlating with IL-17 expression by macrophages in coinfected lymph nodes. Infected macrophages exposed to exogenous IL-17 expressed CXCL10, which favors recruitment of new macrophages as targets for infection. Blockade of nuclear factor κ-light-chain-enhancer of activated B cells and mitogen-activated protein kinase pathways suppressed mycobacteria-induced IL-17 expression. MAC triggered expression of IL-21, IRF4, and STAT3 genes related to IL-17 regulation, as well as expression of the negative immunoregulators CD274(PD-L1) and suppressors of cytokine signaling.

CONCLUSIONS

MAC-infected macrophages can provide an alternative source for IL-17 that favors accumulation of new targets for perpetuating bacterial and viral infection while suppressing host antimicrobial immune responses.

Differential effects of interleukin-17 receptor signaling on innate and adaptive immunity during central nervous system bacterial infection

Although IL-17A (commonly referred to as IL-17) has been implicated in the pathogenesis of central nervous system (CNS) autoimmune disease, its role during CNS bacterial infections remains unclear. To evaluate the broader impact of IL-17 family members in the context of CNS infection, we utilized IL-17 receptor (IL-17R) knockout (KO) mice that lack the ability to respond to IL-17, IL-17F and IL-17E (IL-25). In this article, we demonstrate that IL-17R signaling regulates bacterial clearance as well as natural killer T (NKT) cell and gamma-delta (γδ) T cell infiltrates during Staphylococcus aureus-induced brain abscess formation. Specifically, when compared with wild-type (WT) animals, IL-17R KO mice exhibited elevated bacterial burdens at days 7 and 14 following S. aureus infection. Additionally, IL-17R KO animals displayed elevated neutrophil chemokine production, revealing the ability to compensate for the lack of IL-17R activity. Despite these differences, innate immune cell recruitment into brain abscesses was similar in IL-17R KO and WT mice, whereas IL-17R signaling exerted a greater influence on adaptive immune cell recruitment. In particular, γδ T cell influx was increased in IL-17R KO mice at day 7 post-infection. In addition, NK1.1^high infiltrates were absent in brain abscesses of IL-17R KO animals and, surprisingly, were rarely detected in the livers of uninfected IL-17R KO mice. Although IL-17 is a key regulator of neutrophils in other infection models, our data implicate an important role for IL-17R signaling in regulating adaptive immunity during CNS bacterial infection.

Interleukin-33 induces interleukin-17F in bronchial epithelial cells

BACKGROUND

IL-33 is clearly expressed in the airway of patients with asthma, but its role in asthma has not yet been fully understood. IL-17F is also involved in the pathogenesis of asthma. However, the regulatory mechanisms of IL-17F expression remain to be defined. To further indentify the role of IL-33 in asthma, we investigated the expression of IL-17F by IL-33 in bronchial epithelial cells and its signaling mechanisms.

METHODS

Bronchial epithelial cells were stimulated with IL-33. The levels of IL-17F expression were analyzed using real-time PCR and ELISA. Next, the involvement of ST2, MAP kinases, and mitogen- and stress-activated protein kinase1 (MSK1) was determined by Western blot analyses. Various kinase inhibitors and anti-ST2 neutralizing Abs were added to the culture to identify the key signaling events leading to the expression of IL-17F, in conjunction with the use of short interfering RNAs (siRNAs) targeting MSK1.

RESULTS

IL-33 significantly induced IL-17F gene and protein expression. The receptor for IL-33, ST2, was expressed in bronchial epithelial cells. Among MAP kinases, IL-33 phosphorylated ERK1/2, but not p38MAPK and JNK. It was inhibited by the pretreatment of anti-ST2 neutralizing (blocking) Abs. MEK inhibitor significantly blocked IL-17F production. Moreover, IL-33 phosphorylated MSK1, and MEK inhibitor diminished its phosphorylation. Finally, MSK1 inhibitors and transfection of the siRNAs targeting MSK1 significantly blocked the IL-17F expression.

CONCLUSIONS

IL-33 induces IL-17F via ST2-ERK1/2-MSK1 signaling pathway in bronchial epithelial cells. These data suggest that the IL-33/IL-17F axis is involved in allergic airway inflammation and may be a novel therapeutic target.

A protective role by interleukin-17F in colon tumorigenesis

Interleukin-17F (IL-17F), produced by Th17 cells and other immune cells, is a member of IL-17 cytokine family with highest homology to IL-17A. IL-17F has been shown to have multiple functions in inflammatory responses. While IL-17A plays important roles in cancer development, the function of IL-17F in tumorigenesis has not yet been elucidated. In the current study, we found that IL-17F is expressed in normal human colonic epithelial cells, but this expression is greatly decreased in colon cancer tissues. To examine the roles of IL-17F in colon cancer, we have used IL-17F over-expressing colon cancer cell lines and IL-17F-deficient mice. Our data showed decreased tumor growth of IL-17F-transfected HCT116 cells comparing to mock transfectants when transplanted in nude mice. Conversely, there were increased colonic tumor numbers and tumor areas in Il-17f(-/-) mice than those from wild-type controls after colon cancer induction. These results indicate that IL-17F plays an inhibitory role in colon tumorigenesis in vivo. In IL-17F over-expressing tumors, there was no significant change in leukocyte infiltration; instead, we found decreased VEGF levels and CD31(+) cells. While the VEGF levels were increased in the colon tissues of Il-17f(-/-) mice with colon cancer. Together, our findings demonstrate a protective role for IL-17F in colon cancer development, possibly via inhibiting tumor angiogenesis.

MicroRNAs and other mechanisms regulate interleukin-17 cytokines and receptors

Interleukin-17 cytokines are a family of pro-inflammatory cytokines. Our current studies found: i) IL-17 cytokines are not ubiquitously expressed, but several receptors and TRAF3IP2 are ubiquitously expressed in tissues with a few exceptions; ii) heart and vascular tissue are in the second tier of readiness to respond to IL-17 cytokine stimulation; iii) alternative transcription starting sites and alternative spliced isoforms are found in IL-17 cytokine and receptor transcripts; iv) higher hypomethylation status is associated with higher expressions of IL-17 receptors; v) the binding sites of several RNA binding proteins are found in the 3'UTRs of the mRNAs of IL-17 cytokines and receptors; and vi) numerous microRNA binding sites are statistically equivalent to that of experimentally verified microRNAs-mRNA interactions in the 3'UTRs of IL-17 cytokine and receptor mRNAs. These results suggest that mechanisms including alternative promoters, alternative splicing, RNA binding proteins, and microRNAs regulate the structures and expressions of IL-17 cytokines and receptors. These results provide an insight into the roles of IL-17 in mediating inflammation and immunity.

The potential role of interleukin-17 in severe asthma

Asthma has long been characterized as a disease of dysregulated T-helper type 2 immune responses to environmental allergens. Clinical studies suggest that asthma is a heterogeneous disorder with distinct types of inflammatory processes. Accumulating evidence suggests that aberrant interleukin (IL)-17 production is a key determinant of severe forms of asthma. However, the identity of IL-17-producing cells and the factors regulating IL-17 production during the course of allergic inflammation remain elusive. In this review, we summarize the potential IL-17-producing cells and their involvement in the inflammatory responses that mediate distinct features of asthma. The role of proinflammatory cytokines and the complement pathway in regulating the generation of IL-17-producing T cells is also discussed. Understanding the biology of IL-17 in the context of allergic inflammation may be informative in the development of novel approaches to the diagnosis and treatment of asthma.

A genome-wide association study of overall survival in pancreatic cancer patients treated with gemcitabine in CALGB 80303

BACKGROUND AND AIMS

Cancer and Leukemia Group B 80303 was a randomized, phase III study in patients with advanced pancreatic cancer treated with gemcitabine plus either bevacizumab or placebo. We prospectively collected germline DNA and conducted a genome-wide association study (GWAS) using overall survival (OS) as the endpoint.

EXPERIMENTAL DESIGN

DNA from 351 patients was genotyped for more than 550,000 single-nucleotide polymorphisms (SNP). Associations between OS and SNPs were investigated using the log-linear 2-way multiplicative Cox proportional hazards model. The subset of 294 genetically European patients was used for the primary analysis.

RESULTS

A nonsynonymous SNP in interleukin (IL)17F (rs763780, H161R) and an intronic SNP in strong linkage disequilibrium (rs7771466) were associated with OS using genome-wide criteria (P ≤ 10(-7)). Median OS was significantly shorter (P = 2.61 × 10(-8)) for the rs763780 heterozygotes [3.1 months; 95% confidence interval (CI), 2.3-4.3] than for the patients without this variant (6.8 months; 95% CI, 5.8-7.3). After adjustment by stratification factors, the P value for the association was 9.51 × 10(-7).

CONCLUSIONS

The variant 161R form of IL-17F is a natural antagonist of the antiangiogenic effects of wild-type 161H IL-17F, and angiogenesis may play an important role in the metastatic spread of pancreatic cancer. In this preliminary study, we hypothesize that the angiogenetic potential of pancreatic cancers in patients with variant IL-17F is higher than that of tumors in patients with wild-type IL-17F, conferring worse prognosis. This exploratory GWAS may provide the foundation for testing the biology and clinical effects of novel genes and their heritable variants through mechanistic and confirmatory studies in pancreatic cancer.

IL-17A and IL-17F expression in B lymphocytes

BACKGROUND

Recent evidence suggests that cells other than Th-17 lymphocytes express interleukin (IL)-17A and IL-17F and contribute to the production of these cytokines in immunologically mediated diseases. B lymphocytes are known to be an important source of cytokines in chronic inflammatory diseases. We therefore investigated the potential of human B lymphocytes to produce IL-17A and IL-17F.

METHODS

Highly purified B cells were obtained using a multiple-step separation procedure which included rosette depletion, adherence depletion, CD3+ cell magnetic activated depletion and CD19+ magnetic activated positive cell selection. In these CD19+ B cell fractions, CD3+/CD4+ and CD14+ cells were negligible (<0.2%), and CD8 and CD161 mRNAs were undetectable. The CD19+/CD20+ B cells were stimulated with IL-4, interferon-γ, IL-6, IL-23 and transforming growth factor (TGF)-β, and the expression of IL-17A and IL-17F in response to stimulation was determined by quantitative reverse transcription (RT)-PCR, Western blot, immunocytochemistry and ELISA.

RESULTS

Evidence of expression of IL-17A and IL-17F in purified B cells was obtained using RT-PCR, flow cytometry, immunofluorescence microscopy, Western immunoblotting and ELISA. Stimulation of B cells with IL-6, IL-23 or TGF-β upregulated the expression of both IL-17A and F cytokines.

CONCLUSIONS

These novel findings provide evidence that cytokine-stimulated B lymphocytes could be a significant source of IL-17A and IL-17F and support the notion that these cells actively participate in immune responses via alternative mechanisms in addition to the classic release of antibodies.

IL-17F Induces CCL20 in Bronchial Epithelial Cells

IL-17F plays a crucial role in airway inflammatory diseases including asthma, but its function has not been fully elucidated. CCL20 is also involved in allergic airway inflammation, while its regulatory mechanisms remain to be defined. To further identify a novel role of IL-17F, the expression of CCL20 by IL-17F in bronchial epithelial cells and the signaling mechanisms involved were investigated. Bronchial epithelial cells were stimulated with IL-17F, and the levels of CCL20 gene and protein measured, with the effects of the addition of various kinase inhibitors and siRNAs also investigated. IL-17F significantly induced the expression of CCL20 gene and protein. Pretreatment with inhibitors for MEK1/2, Raf1 and MSK1, and overexpression of a Raf1 dominant-negative mutant significantly diminished IL-17F-induced CCL20 production. Moreover, transfection of the siRNAs targeting MSK1, p90RSK, and CREB blocked CCL20 expression. These findings suggest that IL-17F is able to induce CCL20 via Raf1-MEK1/2-ERK1/2-MSK1/p90RSK-CREB signaling pathway in bronchial epithelial cells. The IL-17F/CCL20 axis may be a novel pharmacological target for asthma.

IL-17A stimulates granulocyte colony-stimulating factor production via ERK1/2 but not p38 or JNK in human renal proximal tubular epithelial cells

We investigated the potential role of IL-17A in the induction of granulocyte colony-stimulating factor (G-CSF), a critical granulopoietic growth factor, in human renal proximal tubular epithelial cells. Human renal proximal tubular cells (HK-2, ATCC) were used to characterize the effects of IL-17A or IL-17F on G-CSF production, using ELISA, real-time RT-PCR, and immunoblotting. The cell surface expression of IL-17 receptors (IL-17Rs) was analyzed by flow cytometry. IL-17A stimulation of proximal tubular cells led to a dose- and time-dependent increase in secreted G-CSF. This effect was dependent on mRNA transcription and protein translation. Real-time RT-PCR demonstrated that G-CSF mRNA expression reached a maximum level at 6 h following IL-17A stimulation and that this increase was dose dependent. Both IL-17RA and IL-17RC were expressed on proximal tubular cells. IL-17A also enhanced TNF-α- or IL-1β-mediated G-CSF secretion from cells. Additionally, IL-17A induced MAPK (ERK1/2 but not p38 MAPK or JNK) activation, and pharmacological inhibitors of MEK1/2 (U0126) but not of p38 MAPK (SB203580) or JNK (SP600125), significantly blocked the IL-17A-mediated G-CSF release. We demonstrated the potential ability of IL-17A to induce G-CSF in renal proximal tubular cells. It is proposed that IL-17A may play an important role in neutrophil transmigration and activation via stimulation of G-CSF in tubular injury.

Clinical and immunological responses in ocular demodecosis

The purpose of this study was to investigate clinical and immunological responses to Demodex on the ocular surface. Thirteen eyes in 10 patients with Demodex blepharitis and chronic ocular surface disorders were included in this study and treated by lid scrubbing with tea tree oil for the eradication of Demodex. We evaluated ocular surface manifestations and Demodex counts, and analyzed IL-1β, IL-5, IL-7, IL-12, IL-13, IL-17, granulocyte colony-stimulating factor, and macrophage inflammatory protein-1β in tear samples before and after the treatment. All patients exhibited ocular surface manifestations including corneal nodular opacity, peripheral corneal vascularization, refractory corneal erosion and infiltration, or chronic conjunctival inflammatory signs before treatment. After treatment, Demodex was nearly eradicated, tear concentrations of IL-1β and IL-17 were significantly reduced and substantial clinical improvement was observed in all patients. In conclusion, we believe that Demodex plays an aggravating role in inflammatory ocular surface disorders.

Interleukin-17F affects cartilage matrix turnover by increasing the expression of collagenases and stromelysin-1 and by decreasing the expression of their inhibitors and extracellular matrix components in chondrocytes

Interleukin (IL)-17, a proinflammatory cytokine, is produced primarily by activated Th17 cells. IL-17 consists of six ligands that signal through five receptors (IL-17Rs); IL-17A and IL-17F share the highest homology in the family. Matrix metalloproteinases (MMPs) degrade the extracellular matrix during cartilage remodeling whereas tissue inhibitor of metalloproteinases (TIMPs) inhibit the action of MMPs. In the present study, we examined the effect of IL-17F on the degradation and synthesis of the extracellular matrix in cartilage using human articular chondrocytes. We examined the effect of IL-17F on the expression of IL-17Rs, MMPs, TIMPs, type II collagen, aggrecan, link protein, and cyclooxygenases (COXs), as well as on prostaglandin E2 (PGE2) production. We also examined the indirect effect of PGE2 on the above IL-17F-induced/reduced components using NS-398, a specific inhibitor of COX-2. Cells were cultured with or without IL-17F in the presence or absence of either an IL-17R antibody or NS-398 for up to 28 days. Expression of IL-17Rs, MMPs, TIMPs, type II collagen, aggrecan, link protein, and COXs at mRNA and protein levels was determined using real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. PGE2 production was determined by ELISA. The expression of all types of IL-17Rs was detected in chondrocytes. However, IL-17RE expression was extremely low, compared with other IL-17Rs. The expression of MMP-1, MMP-3, MMP-13, and COX-2 as well as PGE2 production were increased by addition of IL-17F, whereas the expression of IL-17RD, TIMP-2, TIMP-4, type II collagen, aggrecan, link protein, and COX-1 was decreased. The expression of IL-17RA, IL-17RB, IL-17RC, MMP-2, MMP-14, TIMP-1, and TIMP-3 was unaffected by addition of IL-17F. The IL-17R antibody blocked the stimulating/reducing effect of IL-17F on the expression of MMP-1, MMP-3, MMP-13, TIMP-2, TIMP-4, type II collagen, aggrecan, and link protein. NS-398 blocked the reducing effect of IL-17F on aggrecan expression, whereas it did not completely block the stimulating/reducing effects of IL-17F on the expression of MMP-1, MMP-3, MMP-13, TIMP-2, TIMP-4, type II collagen, and link protein. Our results suggest that IL-17F stimulates cartilage degradation by increasing the expression of collagenases (MMP-1 and -13) and stromelysin-1 (MMP-3) and by decreasing expression of their inhibitors (TIMP-2 and -4), type II collagen, aggrecan, and link protein in chondrocytes. Furthermore, our results suggest that the expression of aggrecan, link protein, and TIMP-4 decrease through the autocrine action of PGE2 in chondrocytes.

Evolution of the IL17 receptor family in chordates: a new subfamily IL17REL

The human interleukin 17 receptor (IL17R) family plays a critical role in inflammatory responses and contributes to the pathology of many autoimmune diseases. So far, five members, IL17RA to IL17RE, have been identified. Recently, some IL17R genes have been identified in non-mammalian species, such as zebrafish IL17RD; however, there are no reports on the evolutionary history of this complex gene family through comparative phylogenetic approaches. Here, we concentrated on the IL17R evolution in chordates. There are two IL17Rs in the genome of the basal chordate amphioxus: IL17RA and IL17RD. After two rounds of whole genome duplications, these two IL17R genes expanded into five early vertebrate IL17R genes, IL17RA to IL17RE. IL17RA and IL17RD are found in most vertebrates, whereas the other three, IL17RB, ILR17RC, and IL17RE, underwent some loss in vertebrates during evolution. Our sequence and structure analyses reveal functional similarities and distinctions between the different IL17Rs. Based on similarity searches for IL17R-like proteins within chordate sequences, a group of IL17RE-like (IL17REL) proteins were identified from mammalians to lower vertebrates. In silico and expression analyses on the novel IL17RELs showed that this group of receptors is highly conserved across species, indicating that IL17REL may represent a unique subfamily of IL17Rs.

The interleukin-17 cytokine family: critical players in host defence and inflammatory diseases

The interleukin-17 (IL-17) cytokines, IL-17A to IL-17F, are emerging as critical players in host defence responses and inflammatory diseases. Substantial data support the role of these proteins in innate and adaptive immunity. Of these family members, IL-17A, IL-17F and IL-17E have been the best studied. Both IL-17A and IL-17F contribute to the host response to extracellular bacteria and fungi, and IL-17E has been shown to play a role in parasitic infections. In addition, numerous pre-clinical and clinical studies link these proteins to the pathogenesis of inflammatory diseases, and a number of therapeutic programmes targeting these family members are in clinical development. This review will highlight the cellular sources, receptors/target cells, and role in inflammation of these and the less-characterized family members, IL-17B, IL-17C and IL-17D.

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

Interleukin-17F increases the secretion of interleukin-8 and the expression of cyclooxygenase 2 in endometriosis

OBJECTIVE

To examine the effects of interleukin (IL)-17F on the secretion of IL-8 and the gene expression of cyclooxygenase 2 (COX2) in endometriotic stromal cells.

DESIGN

In vitro experimental study using human samples.

SETTING

University hospital.

PATIENT(S)

Endometriotic tissues were obtained from women with ovarian endometriomas undergoing laparoscopic surgery.

INTERVENTION(S)

Endometriotic stromal cells (ESCs) were cultured with IL-17F.

MAIN OUTCOME MEASURE(S)

Concentrations of IL-8 were measured by a specific ELISA, and messenger RNA levels of IL-8 and COX2 were measured by real-time reverse transcription-polymerase chain reaction (PCR).

RESULT(S)

IL-17F increased the secretion of IL-8 from ESCs, and the effect was inhibited by antibodies for IL-17 receptor A and IL-17 receptor C. Tumor necrosis factor α (TNF-α) synergistically enhanced IL-17F-induced increase in IL-8 secretion from ESCs. The IL-17F increased the gene expression of IL-8 and COX2 in ESCs.

CONCLUSION(S)

These findings suggest that IL-17F may stimulate the development of endometriosis by up-regulation of IL-8 and COX2.

The use of genomic information to optimize cancer chemotherapy

The field of pharmacogenomics is focused on the characterization of genetic factors contributing to the response of patients to pharmacological interventions. Drug response and toxicity are complex traits; therefore the effects are likely influenced by multiple genes. The investigation of the genetic basis of drug response has evolved from a focus on single genes to relevant pathways to the entire genome. Preclinical (cell-based models) and clinical genome-wide association studies (GWAS) in oncology provide an unprecedented opportunity for a comprehensive and unbiased assessment of the heritable factors associated with drug response. The primary challenge with attempting to identify pharmacogenomic markers from clinical studies is that they require a homogeneous population of patients treated with the same dosage regimen and minimal confounding variables. Therefore, the development of cell-based models for pharmacogenomic marker identification has utility for the field since performing these types of studies in humans is difficult and costly. This review intends to provide a current report on the status of genomic studies in oncology, the methods for discovery, and implications for patient care. We present a perspective and summary of the challenges and opportunities in translating heritable genomic discoveries to patients.

Evolutionary divergence and functions of the human interleukin (IL) gene family

Cytokines play a very important role in nearly all aspects of inflammation and immunity. The term 'interleukin' (IL) has been used to describe a group of cytokines with complex immunomodulatory functions -- including cell proliferation, maturation, migration and adhesion. These cytokines also play an important role in immune cell differentiation and activation. Determining the exact function of a particular cytokine is complicated by the influence of the producing cell type, the responding cell type and the phase of the immune response. ILs can also have pro- and anti-inflammatory effects, further complicating their characterisation. These molecules are under constant pressure to evolve due to continual competition between the host's immune system and infecting organisms; as such, ILs have undergone significant evolution. This has resulted in little amino acid conservation between orthologous proteins, which further complicates the gene family organisation. Within the literature there are a number of overlapping nomenclature and classification systems derived from biological function, receptor-binding properties and originating cell type. Determining evolutionary relationships between ILs therefore can be confusing. More recently, crystallographic data and the identification of common structural motifs have led to a more accurate classification system. To date, the known ILs can be divided into four major groups based on distinguishing structural features. These groups include the genes encoding the IL1-like cytokines, the class I helical cytokines (IL4-like, γ-chain and IL6/12-like), the class II helical cytokines (IL10-like and IL28-like) and the IL17-like cytokines. In addition, there are a number of ILs that do not fit into any of the above groups, due either to their unique structural features or lack of structural information. This suggests that the gene family organisation may be subject to further change in the near future.

Structure and function of interleukin-17 family cytokines

The recently identified interleukin-17 (IL-17) cytokines family, which comprises six members in mammals (IL-17A-F), plays essential roles in the host immunity against infectious diseases and chronic inflammatory diseases. The three-dimensional structures containing IL-17A or IL-17F have become available and revealed the unique structural features of IL-17s as well as their receptors. Molecular modeling in this review shows that IL-17s may adopt a "cysteine knot" fold commonly seen in nerve growth factor (NGF) and other neurotrophins. Further modeling analysis unmasks a signature interaction feature of the IL-17F/IL-17RA complex, where a small loop of IL-17RA slots into the deep groove of the interface of IL-17F homodimer. This is quite different from the interaction between the best known four-helix cytokines and their cognate receptors. On the other hand, structure of IL-17A and its monoclonal antibody (CAT-2200) shows that, albeit that the antigenic epitope of IL-17A resides outside of the IL-17A homodimer interface, its physical proximity to the receptor binding groove may explain that antibody blockage would be achieved by interfering with the ligand-receptor interaction. This review is to summarize the advance in understanding the structure and function of IL-17 family cytokines, focusing mainly on IL-17A, IL-17F and IL-17E, in the hope of gaining better knowledge of immunotherapeutic strategies against various inflammatory diseases.

Improved survival, vascular differentiation and wound healing potential of stem cells co-cultured with endothelial cells

In this study, we developed a methodology to improve the survival, vascular differentiation and regenerative potential of umbilical cord blood (UCB)-derived hematopoietic stem cells (CD34(+) cells), by co-culturing the stem cells in a 3D fibrin gel with CD34(+)-derived endothelial cells (ECs). ECs differentiated from CD34(+) cells appear to have superior angiogenic properties to fully differentiated ECs, such as human umbilical vein endothelial cells (HUVECs). Our results indicate that the pro-survival effect of CD34(+)-derived ECs on CD34(+) cells is mediated, at least in part, by bioactive factors released from ECs. This effect likely involves the secretion of novel cytokines, including interleukin-17 (IL-17) and interleukin-10 (IL-10), and the activation of the ERK 1/2 pathway in CD34(+) cells. We also show that the endothelial differentiation of CD34(+) cells in co-culture with CD34(+)-derived ECs is mediated by a combination of soluble and insoluble factors. The regenerative potential of this co-culture system was demonstrated in a chronic wound diabetic animal model. The co-transplantation of CD34(+) cells with CD34(+)-derived ECs improved the wound healing relatively to controls, by decreasing the inflammatory reaction and increasing the neovascularization of the wound.

Induction of insulin-like growth factor-I by interleukin-17F in bronchial epithelial cells

BACKGROUND

Increased expression of IL-17F has been noted in the airway of asthmatic patients, but its role in asthma has not been fully elucidated. Insulin-like growth FACTOR-I (IGF-I) is known to be involved in airway remodelling and inflammation, while its regulatory mechanisms remain to be defined.

OBJECTIVE

To further clarify the biological function of IL-17F, we investigated whether IL-17F is able to regulate the expression of IGF-I in bronchial epithelial cells.

METHODS

Bronchial epithelial cells were stimulated with IL-17F in the presence or absence of T-helper type 2 cytokines. Various kinase inhibitors were added to the culture to identify the key signalling events leading to the expression of IGF-I, in conjunction with the use of short interfering RNAs (siRNAs) targeting mitogen- and stress-activated protein kinase (MSK) 1, p90 ribosomal S6 kinase (p90RSK), and cyclic AMP response element-binding protein (CREB).

RESULTS

IL-17F significantly induced IGF-I gene and protein expression, and co-stimulation with IL-4 and IL-13 augmented its production. MAP kinase kinase (MEK) inhibitors and the Raf1 kinase inhibitor significantly inhibited IGF-I production, and the combination of PD98059 and Raf1 kinase inhibitor showed further inhibition. Overexpression of Raf1 and Ras dominant-negative mutants inhibited its expression. MSK1 inhibitors significantly blocked IL17F-induced IGF-I expression. Moreover, transfection of the siRNAs targeting MSK1, p90RSK, and CREB blocked its expression.

CONCLUSIONS

In bronchial epithelial cells, IL-17F is able to induce the expression of IGF-I via the Raf1-MEK1/2-ERK1/2-MSK1/p90RSK-CREB pathway in vitro.

IL-17E but not IL-17A is associated with allergic sensitization: results from the LISA study

Functional studies have provided evidence for the importance of IL-17A and IL-17E in the regulation of immune responses. IL-17A is involved in inflammation and IL-17E is able to induce Th2 cytokine production and eosinophilia. By now it is not clear whether these cytokines correlate with specific IgE levels. The aim of our investigation was to analyse the relationship of these two cytokines to allergic sensitization in context of an epidemiological study. Within the Life style Immune System Allergy study (LISA), we analysed phytohemagglutinin (PHA)-stimulated blood samples of 6 yr old children for the concentration of IL-17A and IL-17E and sera for levels of specific IgE. In total, data from 293 children were available for blood analysis and for the analysis of confounding factors for the allergic sensitization. Among the investigated children, 29% reacted against inhalant and 13.6% against food allergens, whereas 33.1% of children were sensitized to any allergen.IL-17E was associated with high levels of any specific IgE (adjusted odds ratio (OR) 1.45, 95% confidence interval (CI) 1.11–1.90). Furthermore, children with high IL-17E responses (>208.8 pg/ml) were sensitized to food and inhalant allergens (OR 1.45, 95% CI 1.02–2.07 and OR 1.35, 95% CI 1.03–1.77, respectively) and to Der p 1 (OR 1.55, 95% CI 1.12–2.15). In contrast, IL-17A, in trend, was negatively associated to sensitization to timothy (p for trend=0.013) and rye (p for trend=0.026). Concluding IL-17E production is linked to the amount of specific IgE antibodies in blood samples of 6 yr old children.

A novel subset of CD4(+) T(H)2 memory/effector cells that produce inflammatory IL-17 cytokine and promote the exacerbation of chronic allergic asthma

The inflammatory cytokine interleukin (IL)-17 is involved in the pathogenesis of allergic diseases. However, the identity and functions of IL-17-producing T cells during the pathogenesis of allergic diseases remain unclear. Here, we report a novel subset of T(H)2 memory/effector cells that coexpress the transcription factors GATA3 and RORγt and coproduce T(H)17 and T(H)2 cytokines. Classical T(H)2 memory/effector cells had the potential to produce IL-17 after stimulation with proinflammatory cytokines IL-1β, IL-6, and IL-21. The number of IL-17-T(H)2 cells was significantly increased in blood of patients with atopic asthma. In a mouse model of allergic lung diseases, IL-17-producing CD4(+) T(H)2 cells were induced in the inflamed lung and persisted as the dominant IL-17-producing T cell population during the chronic stage of asthma. Treating cultured bronchial epithelial cells with IL-17 plus T(H)2 cytokines induced strong up-regulation of chemokine eotaxin-3, Il8, Mip1b, and Groa gene expression. Compared with classical T(H)17 and T(H)2 cells, antigen-specific IL-17-producing T(H)2 cells induced a profound influx of heterogeneous inflammatory leukocytes and exacerbated asthma. Our findings highlight the plasticity of T(H)2 memory cells and suggest that IL-17-producing T(H)2 cells may represent the key pathogenic T(H)2 cells promoting the exacerbation of allergic asthma.

Anti-inflammatory treatment of uveitis with biologicals: new treatment options that reflect pathogenetic knowledge of the disease

BACKGROUND

Endogenous uveitis is a sight-threatening disease. In addition to corticosteroids, immunosuppressive agents are commonly used to treat patients with severe course. Immunosuppressive drugs act nonspecifically, rather than providing a specific interaction with the critical pathogenetic pathways of uveitis. Better knowledge of the basic mechanisms underlying uveitis and of the molecules that are important for regulating inflammation has helped to create new and more specific treatment approaches. Biological therapy for inflammatory diseases employs substances that interfere with specific molecules or pathways induced in the body during the inflammatory process.

METHODS

This review gives an overview on molecules that play a critical role in the pathogenetic process of uveitis, as has been observed in patients or the respective animal models, and summarizes the current experience with biologicals for the treatment of uveitis refractive to conventional immunosuppressives.