Role Of Th17 Research Articles

The imbalance of Th17/Treg in patients with uterine cervical cancer

BackgroundTh17/Treg was reported to play critical roles in immunoregulation, and its imbalance may lead to autoimmune diseases and allergic reactions. Information on Th17/Treg in cancer bearing hosts is still limited. MethodsWe examined the expression of IL-17, Foxp3 and IL-10 in uterine cervical cancer (UCC) patients, cervical intraepithelial neoplasia (CIN) patients and healthy controls by flow cytometry and enzyme-linked immunosorbent assay. Interleukin (IL)-17-producing CD4+ cells as Th17 and CD4+CD25+Foxp3+ cells as Treg were expressed as a percentage of the total CD4+ cells. ResultsCompared with controls, patients with UCC or CIN had a higher proportion of Th17 cells. UCC patients also revealed a significant increase in Treg number and IL-17 and IL-10 concentrations in plasma, while CIN patients did not. Notably, in UCC patients, the increased Th17 prevalence was associated with clinical stage, lymph node metastases and vasoinvasion, while the increased Treg frequency was associated with tumor differentiation. Remarkably, an attractive imbalance of Th17/Treg was observed in UUC and CIN patients. Furthermore, in UCC patients with lymph node metastases or vasoinvasion, the ratio of Th17/Treg was significantly higher than that in negative patients respectively. ConclusionsOur results indicated a possible role of Th17 in UCC patients correlated to Treg cells, and the imbalance of Th17/Treg may be involved in the development and progression of UCC.

T-helper cells in the etiopathogenesis of periodontal disease: A mini review

Our traditional understanding of the T-helper (Th)1/Th2 paradigm in periodontal disease has undergone considerable changes in recent years. This review focuses on the Th subsets, including the recently identified cells of the CD4 lineage, their activation pathways and effector function in periodontal disease. The roles of Th17 and regulatory T (Treg) cells in disease pathogenesis have been explored. Newer Th subsets such as Th9 and Th22 cells and their potential role in periodontal disease have also been outlined.

The Role of Th17 in Neuroimmune Disorders: A Target for CAM Therapy. Part III.

Abundant research has mapped the inflammatory pathways leading to autoimmunity and neuroinflammatory disorders. The latest T helper to be identified, Th17, through its proinflammatory cytokine IL-17, plays a pathogenic role in many inflammatory conditions. Today, healthcare providers have a wealth of anti-inflammatory agents from which to choose. On one hand, pharmaceutical companies market brand-name drugs direct to the public and physicians. Medical botanical knowledge, on the other hand, has been passed down from generation to generation. The demands for natural healing therapies have brought corresponding clinical and laboratory research studies to elucidate the medicinal properties of alternative practices. With a variety of options, it can be difficult to pinpoint the proper anti-inflammatory agent for each case presented. In this review, the authors highlight a vast array of anti-inflammatory medicaments ranging from drugs to vitamins and from botanicals to innate molecules. This compilation may serve as a guide for complimentary and alternative healthcare providers who need to target neuroinflammation driven by Th17 and its inflammatory cytokine IL-17. By understanding the mechanisms of anti-inflammatory agents, CAM practitioners can tailor therapeutic interventions to fit the needs of the patient, thereby providing faster relief from inflammatory complaints.

Possible Role of Th1, Th2 and Th17 CD4+ T Helper Subpopulations on Human Pregnancy Development

Paternal HLA-C antigens expressed by trophoblast, which liken the trophoblast to a semiallograft, could be presented by the maternal APCs to the specific maternal CD4 + T helper cells, which could release various cytokines in response to these alloantigens. On the basis of the cytokines produced the effector CD4 + T helper lymphocytes can be classified in Th1, Th2 and Th17 cells. We focused here the possible role of these 3 human effector CD4 + T helper subpopulations, known to be involved either in allograft rejection (Th1 and Th17 cells) or in allograft tolerance (Th2 cells). Th1 and Th17 cells may compromise pregnancy and be responsible for miscarriage and Th2 cells may be responsible for the success and maintenance of pregnancy. Interestingly, our recent findings showed a beneficial role of Th17 cells, whose major role is the protection against extracellular bacteria and thus may promote adequately the response required to protect the mother against dangerous extracellular pathogens. The chronology of action of Th17 cells remains to be investigated to understand completely the mechanisms by which pregnancy development could or could not be affected by Th17 cells.

The Role of Th17 in Neuroimmune Disorders: Target for CAM Therapy. Part II

Decades of research went into understanding the role that Th1 autoreactive T-cells play in neuroinflammation. Here we describe another effector population, the IL-17-producing T-helper lineage (Th17), which drives the inflammatory process. Through the recruitment of inflammatory infiltration neutrophils and the activation of matrix metalloproteinases, IL-17, a cytokine secreted by Th17 cells, contributes to blood-brain barrier breakdown and the subsequent attraction of macrophages and monocytes into the nervous system. The entry of cells along with the local production of inflammatory cytokines leads to myelin and axonal damage. This activation of the inflammatory response system is induced by different pathogenic factors, such as gut bacterial endotoxins resulting in progressive neurodegeneration by Th17 cells. Through the understanding of the role of bacterial endotoxins and other pathogenic factors in the induction of autoimmune diseases by Th17 cells, CAM practitioners will be able to design CAM therapies targeting IL-17 activity. Targeted therapy can restore the integrity of the intestinal and blood-brain barriers using probiotics, N-acetyl-cysteine, α-lipoic acid, resveratrol and others for their patients with autoimmunities, in particular those with neuroinflammation and neurodegeneration.

The Role of Th17 in Neuroimmune Disorders: Target for CAM Therapy. Part I

CD4+ effector cells, based on cytokine production, nuclear receptors and signaling pathways, have been categorized into four subsets. T-helper-1 cells produce IFN-γ, TNF-β, lymphotoxin and IL-10; T-helper-2 cells produce IL-4, IL-5, IL-10, IL-13, IL-21 and IL-31; T-helper-3, or regulatory T-cells, produce IL-10, TGF-β and IL-35; and the recently discovered T-helper-17 cell produces IL-17, IL-17A, IL-17F, IL-21, IL-26 and CCL20. By producing IL-17 and other signaling molecules, Th17 contributes to the pathogenesis of multiple autoimmune diseases including allergic inflammation, rheumatoid arthritis, autoimmune gastritis, inflammatory bowel disease, psoriasis and multiple sclerosis. In this article, we review the differential regulation of inflammation in different tissues with a major emphasis on enhancement of neuroinflammation by local production of IL-17 in the brain. By understanding the role of pathogenic factors in the induction of autoimmune diseases by Th17 cells, CAM practitioners will be able to design CAM therapies targeting Th17 and associated cytokine activities and signaling pathways to repair the intestinal and blood-brain barriers for their patients with autoimmunities, in particular, those with neuroinflammation and neurodegeneration.

Association of Interleukin-18 Gene Polymorphism with Severity of Chronic Immune Thrombocytopenia (ITP).

AbstractAbstract 3693 Introduction:Immune thrombocytopenia (ITP) is a chronic acquired organ-specific autoimmune disorder characterized by the production of antibodies against antigens on the membranes of platelets. Several cytokine studies have shown Th1 polarization in ITP patients. Interleukin-18 (IL-18) plays an important role in Th1 and Th2 immune response. Recent studies showed that single-nucleotide promoter polymorphisms influence the transcriptions of IL-18 mRNA. IL-18 polymorphism has been implicated in autoimmunity, including Crohn's disease, rheumatoid arthritis, and asthma. We examined the single nucleotide polymorphisms (SNPs) in the promoter regions of the IL-18 genes in patients with ITP, and analyzed the relationship between IL-18 SNPs and clinical features. Patients and Methods:One hundred patients (male/female; 22/78, median age; 54.5) diagnosed as chronic ITP and 151 healthy controls were included. Chronic ITP was defined as thrombocytopenia (platelet count < 100×109/L) persisting greater than 12 months, normal or increased marrow megakaryocytes, and no secondary immune or non-immune abnormality that could account for the thrombocytopenic state. ITP with severe thrombocytopenia was defined as thrombocytopenia (platelet count < 10×109/L) at presentation of ITP. The response criteria of the ITP International Working Group was used. A complete response (CR) is defined as any platelet count of at least 100×109/L, and a response (R) was defined as any platelet count between 30 and 100×109/L and at least doubling of the baseline count. Allparticipants gave written informed consent about the study. Genomic DNA was isolated from peripheral blood using the DNA Kit (QIAGEN, Hilden, Germany). An allele-specific polymerase chain reaction was used to analyze polymorphism in IL-18 –607A/C and -137G/C. Genotype and allele frequencies were compared between the study groups using Χ2-test. The characteristics and laboratory features of the ITP patients with each IL-10 promoter polymorphism were compared using X2-tests and student t-tests. Probability values <0.05 were considered statistically significant. Results:The platelet count was at an initial diagnosis ranged from 1×109/L to 98 ×109/L, with a median of platelet count of 15×109/L. Thirty-five patients (35%) had severe thrombocytopenia. Steroid treatment was given to 68 patients (68%), while splenectomy was used in 11 patients (11%).The frequencies of the genotypes were as follows: AA (34%), AC (57%), and CC (9%) for -607; GG (77%), GC (21%), and CC (2%) for -137 loci. The frequencies of each haplotype were as follows: C-G/C-G haplotype (9%), A-G/C-G haplotype (47%), A-C/C-G haplotype (10%), A-G/A-G haplotype (21%), A-G/A-C haplotype (11%) and A-C/A-C haplotype (2%). No significant differences in the genotype or haplotype frequencies demonstrated between chronic ITP patients and control group. However, patients with -137CC genotypes showed severe thrombocytopenia at initial diagnosis compared to those with -137GG/GC genotypes (5×109/L vs. 22×109/L, p=0.002). Furthermore, patients with A-C/A-C haplotype showed severe thrombocytopenic state (5×109/L vs. 22×109/L, p=0.002) compared to those without A-C/A-C haplotype. No significant difference of treatment response was observed according to IL-18 polymorphism. Conclusion:No significant differences in the genotype or haplotype frequencies demonstrated between chronic ITP patients and control. However, -137CC genotypes or AA/CC haplotype was associated with severity of chronic ITP. Our data suggest that the group with low IL-18 inducibility (i.e. -137CC genotype, A-C/A-C haplotype) may have more severe thrombocytopenia. Disclosures:No relevant conflicts of interest to declare.

Interleukin-17: friend or foe in atherosclerosis?

To summarize the current knowledge on the origin and physiological function of T helper 17 (Th17) and discuss the contrasting results pertaining to the role of Th17 and interleukin-17 (IL-17) in atherosclerosis. Atherosclerosis is a chronic inflammatory arterial disease driven by both innate and adaptive immune responses to modified lipoproteins. Although initial studies have focused on the role of Th1 and Th2 responses in atherosclerosis, more recent findings identified atheroprotective roles for several subsets of regulatory T cells. Th17 represents a new T-cell lineage with important roles in the clearance of pathogenic bacteria and fungi. The increase of Th17 and IL-17 has been recently linked to the pathogenesis of several autoimmune diseases. However, its role in chronic inflammatory diseases such as atherosclerosis remains poorly understood. The few studies available on this topic have generated contrasting results, which could be attributed to different approaches used on various mouse models. IL-17 seems to have a modulatory role in atherosclerosis. Future studies are needed to better determine the molecular mechanisms involved in this regulation and examine whether targeting IL-17 pathway will be useful to treat cardiovascular diseases.

IPF: new insight on pathogenesis and treatment

Recent years have seen a robust influx of exciting new observations regarding the mechanisms that regulate the initiation and progression of pulmonary fibrosis but the pathogenesis remains poorly understood. The search for an alternative hypothesis to unremitting, chronic inflammation as the primary explanation for the pathophysiology of idiopathic pulmonary fibrosis (IPF) derives, in part, from the lack of therapeutic efficacy of high-dose immunosuppressive therapy in patients with IPF. The inflammatory hypothesis of IPF has since been challenged by the epithelial injury hypothesis, in which fibrosis is believed to result from epithelial injury, activation, and/or apoptosis with abnormal wound healing. This hypothesis suggests that recurrent unknown injury to distal pulmonary parenchyma causes repeated epithelial injury and apoptosis. The resultant loss of alveolar epithelium exposes the underlying basement membrane to oxidative damage and degradation. Emerging concepts suggest that IPF is the result of epithelial-mesenchymal interaction. The initiation of this fibrotic response may depend upon genetic factors and environmental triggers; the role of Th1 or Th2 cell-derived cytokines may also be important. This process appears to be unique to usual interstitial pneumonia/IPF. It is clear that IPF is a heterogeneous disease with variations in pathology, high-resolution computed tomography findings, and patterns of progression. Idiopathic pulmonary fibrosis is a complex disorder, and no unifying hypothesis has been identified at present that explains all the abnormalities.

Current views on the roles of Th1 and Th17 cells in experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune demyelinating diseases of the central nervous system (CNS). Interferon-gamma-producing Th1 and interleukin-17-producing Th17 CD4(+) T helper (Th) cells mediate disease pathogenesis in EAE and likely in MS as well. However, the relative contribution of each Th subset to autoimmune processes in the CNS remains unclear. Emerging data suggest that both Th1 and Th17 cells contribute to CNS autoimmunity, albeit through different mechanisms. A better understanding of the roles that Th1 and Th17 cells play in autoimmune inflammation will be helpful in developing new therapeutic approaches. In this review, we discuss recent findings on the roles of Th1 and Th17 cells in the pathogenesis of EAE.

Mesenchymal Stem Cells Inhibit Th17 Differentiation through PGE2 Production.

Abstract 3633Poster Board III-569Mesenchymal stem cells (MSCs) possess an immunomodulatory function and show promise as a cell therapy for graft-versus-host disease (GVHD). In a phase II study in Europe, injections of MSCs caused 60-70% overall response rate, with longer survival of complete responder. In contrast to its clinical efficacy, the molecular mechanism(s) underlying immunomodulation by MSCs has not been fully established. Prostaglandin E2 (PGE2), tumor growth factor-b1 (TGF-b1), and indoleamine-2,3-dioxygenase have been reported to mediate the immunomodulatory function of MSCs, and we reported evidence that nitric oxide is also a mediator (Blood 2007, 109, 228). Th17 is a recently recognized differentiation category, in which CD4 cells produce IL-17. It has been reported that Th17 is crucial for experimental autoimmune encephalomyelitis (a model of the human disease, multiple sclerosis) and is also thought to be important in other autoimmune diseases. Regulatory T cells (Treg) are another newly recognized differentiation category, in which CD4 T cells have high levels of Foxp3 expression and suppress T cell proliferation. It has been reported that Th17 and Treg can be induced by incubation with TGF-b1 and IL-6 or IL-21, and TGF-b1 and IL-2, respectively, and that these two differentiations are in a reciprocal relationship. Whereas the role of Th17 in GVHD is still controversial, Treg has been reported to suppress GVHD in a mouse model.To elucidate the molecular mechanism(s) of the immunomodulatory function of MSCs, we herein sought to identify the effects of MSCs on these relatively new differentiations. MSCs inhibit Th17 differentiation even in conditions in which growth is not completely inhibited. Interestingly, an inhibitor of prostaglandin production, indomethacin, and an inhibitor of indoleamine 2,3-dioxygenase, 1-methyltryptophan, partially restore Th17 differentiation, whereas inhibitors of nitric oxide synthase do not. These results suggest that PGE2 and depletion of tryptophan, but not nitric oxide, mediate inhibitory effects of MSCs on Th17. Additionally, we found that MSCs produced PGE2 when co-cultured with CD4 T cells in Th17 differentiation condition and PGE2 per se suppresses Th17 differentiation. Thus, our results suggest that MSCs block Th17 differentiation through PGE2 prodction. In contrast to Th17 differentiation, Treg differentiation was not significantly inhibited by MSCs. However, MSCs still inhibited proliferation of T cells under these conditions, and T cell proliferation was restored by the addition of indomethacin. These results suggest that MSCs inhibit proliferation but not Treg differentiation through PGE2 production. The mechanism by which PGE2 differentially regulates these differentiations is unknown and remains an area for further investigation. Disclosures:Ozawa:Alexion: Research Funding.

Understanding autoimmune disease: new targets for drug discovery

A more complete understanding of the mechanisms that drive autoimmune diseases has begun to be translated into therapeutic options with significant clinical consequences. A clear example of this is the introduction of biological therapies, which have provided new therapeutic avenues, as well as validated the mediators (TNFalpha, IL-6), mechanisms (T cell costimulation, leukocyte migration), and cellular players (T and B lymphocytes) of the disease process itself. New discoveries into the role of Th17 and regulatory T cells and the epigenetic regulation of cytokine expression may offer novel intervention strategies to satisfy the unmet medical needs that still exist in these diseases.

T1778 Reciprocal Modulation of Smooth Muscle Cell Contractility in TH1 and Th2 Dominant Environments Using Murine Model of Early Post Inflammatory Gut Dysfunction

Background & Aim: In the enteric-infection-induced model of inflammation, Th1 and Th2 cytokines have opposing effect on intestinal muscle function and 5-HT signaling (Motomura et al. Gut 2008; Gastroenterology 128;Suppl A 626,2005), but the role of Th1 and Th2 dominant environments for non-infective post-inflammatory (PI) gut dysfunction remains to be determined. Here we investigated the mechanism for gut dysfunction that persists after acute inflammation in Th1 and Th2 dominant environments utilizing mouse model of T cell-induced enteropathy. Methods: BALB/c (Th2 dominant response) and AKR (Th1 dominant response) mice were treated with an anti-CD3 antibody (100 μg), and sacrificed at days 0, 1, 3, 7, and 14 post-treatment to investigate the histological changes, longitudinal smooth muscle cell contraction, various cytokines (Th1, Th2, Th17 cytokines), chemokines, and mediators mRNA /protein expressions and 5-HT-expressing enterochromaffin (EC) cells numbers in the small intestine. Results: In BALB/c mice small intestinal tissue damage was observed from 24 hours after the anti-CD3 antibody injection, but had resolved by day 5. Carbachol-induced smooth muscle cell contractility was significantly increased (p<0.05) from 4 hours after injection, and this muscle hypercontractility was evident (p<0.05) in the early PI phase (at day 7). Th2 cytokines (IL-4, IL-13) were significantly increased (p<0.05) from 4 hours to day 7 in the small intestine. EC cells in the intestine were significantly increased from day 1 to day 7 (p<0.05). On the contrary in AKR mice carbachol-induced smooth muscle cell contractility was significantly decreased from 4 hours after injection (p<0.05), and this muscle hypocontractility was evident until day 14. Th1 cytokines (IFNγ) were increased from 4 hours to day 7 in the small intestine. Conclusions: Intestinal muscle dysfunction in the early PI phase is maintained at the smooth muscle cell level. Th1 and Th2 cytokines have opposing effect on intestinal muscle contraction via 5-HT signaling in the early PI phase in this model. The gut dysfunctions in the early PI phase are influenced by Th1 or Th2 cytokine predominance environments.

Differential Expression of Nuclear Receptors in T Helper Cells

Steroid hormones have long been known to have a profound influence on the immune system. Although the functions of these nuclear receptors in the development of T cells are fairly well studied, the differential expression of these receptors in T helper cells is poorly understood. Here, we investigated the differential expression of nuclear receptors and coregulators in Th1 and Th2 cells by genomewide microarray analysis. The result showed that several nuclear receptors and coregulators are differentially expressed in these cells. The result was confirmed by RT-PCR. The result showed that RXRalpha is highly expressed in Th2 cells. Overexpression of RXRalpha in a Jurkat human T cell line induced IL4 but not IFN-gamma gene expression, suggesting that RXRalpha plays a selective role in Th1 and Th2 differentiation. In summary, these results suggest that Th1/Th2 differentiation may be influenced by differential regulation of nuclear receptors and coregulators.

Donor T Cell Production of IL-21 Accelerates Graft-Versus-Host Disease Lethality.

IL-21, produced by T-cells, binds to the common gamma chain family member, IL21R, expressed on immune and colonic epithelial cells. IL-21 signaling results in the maturation, activation and proliferation of T, B, NK-cells and DCs. IL-21 has been implicated in Th17 generation/amplification and also modulating Treg differentiation. However, the relevance of this in disease is unclear. Therefore, we wanted to study the effects of IL-21 depletion and the role of Th17 and Treg cells in the context of GVHD. A lethally irradiated, complete MHC disparate model (B6 to B10.BR) using donor bone marrow cells alone or with the addition of wild-type (wt) CD4+CD25- Effector T-cells and irrelevant or anti-IL-21 Ab from days 0 to 25 twice per week. The administration of anti-IL-21Ab lead to a significant delay of weight loss and mortality (P<0.0001). To determine whether IL-21 deficiency accelerates or inhibits GVHD, studies were performed comparing GVHD-inducing ability of wt or IL-21 knockout (IL21−/−) donor CD4+CD25- T cells. A striking survival advantage of recipients of IL-21−/− vs wt CD4+CD25- T cells was observed (100% vs 0% surviving, P < 0.0001). Subsequent studies were performed using whole T cells, a more clinically relevant donor T cell graft source. Whereas recipients of wt T-cells all died of GvHD within 50 days of GvHD, recipients of IL-21 −/− T-cells showed significantly less weight loss and superior long-term survival (P < 0.0001). Histopathological examination of recipients of CD25-depleted T-cells on d14 revealed significantly reduced GvHD scores of the colonic mucosa and a trend towards lower GvHD scores in the small intestine, liver and the spleen in recipients of IL-21−/− cells. Although flow cytometry analysis of mononuclear cells showed no changes in the frequency of IL-17 producing cells in spleen, liver and colon, the frequency of interferon gamma producing CD4+ T- (Th1) cells was significantly lower in the spleen and the colon of recipients of IL-21−/− vs. wt T-cells. Moreover, increased Treg frequencies were seen in the colon of IL-21−/− vs wt CD25-depleted T cells (mean values: 7.5% vs. 2.1%; P < 0.003). We conclude that IL-21 production by either CD25- depleted T-cells or CD4+CD25- T cells is sufficient to increase GVHD mortality and that Treg inhibition, rather than Th17 generation or amplification, are likely contributing to GVHD lethality acceleration. We also conclude that IL-21 neutralization represents a novel approach for GVHD inhibition that warrants further investigation.

The interleukin-23/interleukin-17 axis in spondyloarthritis

To inform readers of recent advances in our understanding of the development and function of Th17 T cells and emerging data suggesting that the interleukin-23/interleukin-17 axis may be involved in the pathogenesis of spondyloarthritis. The discovery of CD4+ Th17 T cells and the interleukin-23/interleukin-17 axis has challenged existing paradigms and the role of Th1 T cells in many autoimmune diseases. The development and cytokine profile of Th17 T cells differs in mice and humans. In humans, interleukin-23 synergizes with interleukin-6 and interleukin-1 to promote Th17 development. In mice, transforming growth factor-beta and interleukin-6 are critical, whereas interleukin-23 is more important at later stages promoting interleukin-17 production. In mice, CD4+ cells producing interferon-gamma appear to be distinct from interleukin-17-producing cells, while in humans cells secreting both cytokines have been observed. Growing evidence from animal models, cytokine analyses of patient fluids, and whole-genome association studies suggest that the interleukin-23/interleukin-17 axis plays an important role in spondyloarthritis pathogenesis. Possible links between an HLA-B27-induced unfolded protein response and activation of the interleukin-23/interleukin-17 axis have been observed in animal models and may contribute to the development of the spondyloarthritis phenotype. Activation of the interleukin-23/interleukin-17 axis in spondyloarthritis has important therapeutic implications.

Role of Th1 and Th2 lymphocytes and cytokines produced by these cells in suppression of immune reactions during subacute poisoning with anticholinesterase toxicants

Experiments on Wistar rats showed that subacute poisoning with anticholinesterase toxicants zarin and agent VX (daily subcutaneous injections in 1/7 LD50 for 6 days) led to suppression of cellular and humoral immune reactions and to a decrease in blood concentrations of cytokines (IL-2, IL-4, IFN-gamma) with a reduction of the IFN-gamma/IL-4 and IL-2/IL-4 ratios, which attests to more pronounced decrease in Th1 lymphocyte function in comparison with Th2 cells.

Role of IL-18 on phosphorylation of STAT-6 in monocyte/macrophages (94.11)

Abstract Cytokine interactions in health &amp; disease are very complex. There are conflicting reports on the cytokine IL-18 and its role in Th1 versus Th2 shift. The hypothesis that STAT-6 is expressed in monocyte/macrophages and that cytokine IL-18 has an effect on the phosphorylation of STAT-6 is addressed. Monocyte/macrophages were isolated by negative selection. The data indicates that the optimum concentration of IL-18 required for stimulation is 10μg/1x106 cells and 72 hour culture period is the optimum time for the induction of maximum levels of STAT-6 phosphorylation. We also observed total tyrosine phosphorylation of several intracellular proteins. Based on these studies, we propose that macrophages respond to IL-18 via STAT-6 phosphorylation and that IL-18 induces mitotic activity in monocyte/macrophages. Our data suggest that IL-18 actsin a more subtle manner as a costimulatory factor in the activation of STAT-6 in monocytes and provides evidence for a new immunoregulatoryeffect of the proinflammatory cytokine IL-18 on monocytes. Grant from C.W.Post Campus Research Committee of Long Island University, New York supported this work.

148: The IL-23/IL-17 axis in human cardiac allograft vasculopathy

Purpose: Cardiac Allograft Vasculopathy (CAV) after heart-transplantation is a major factor limiting the long-term patient survival. CAV is characterized by a concentric intima proliferation, which is induced by a mononuclear cell infiltrate (MNC). This process is often compared with a proliferative autoimmune disease in which IL-17 producing T-helper cells (Th17) play a central role. In this study the role of Th17 in the development of CAV was analyzed. Methods and Materials: Coronary arteries (CA) were obtained from CAV patients (n 6) and compared to CA from non-CAV patients (n 5). Q-PCR analysis was performed using a low density array on cDNA prepared from 5 microdissected areas: 1) luminal layer of the intima (LL), 2) smooth muscle cell layer of the intima, 3) tunica media, 4) adventitia (AD), and 5) lymphoid clusters outside the vessel. Genes (50) were selected for Th1/Th2/Th17 characterization. Positive gene expression by Q-PCR analysis was confirmed and localized by in situ hybridization and immunohistochemistry. Results: Tand B-cells were mainly detected in the LL and the AD of CAV and were absent in control CA. Cytokine expression in CAV was generally low, probably due to the immunosuppression. IFN, known to inhibit Th17, was however, significantly expressed, mainly in LL and AD of CAV but not in control CA. TGF, which induces Th17, was detected in both CAV and control CA, and was localized in macrophages. Th1 markers were abundantly present, but Th17 markers such as IL17, IL-23, and IL23R were weakly expressed or absent. Likewise, regulatory T-cells (FoxP3) were not detected in CAV and control CA, and Th2 markers only on a minority of MNC. Conclusions: In autoimmunity, a dichotomy between inducing Th17 and inhibiting regulatory T-cells has been described. In CAV, both are absent. This is suggestive of a different mechanism driving the proliferative response, possibly due to the low cytokine response under immunosuppression. Therefore, we suggest that the Th1-cells, which are predominant in the MNC, are responsible for the direct or indirect induction of the proliferative response.

Serum proinflammatory cytokines directing T helper 1 polarization in patients with familial Mediterranean fever

Th1 type polarization has been implicated in the pathogenesis of familial Mediterranean fever (FMF). Interleukin-12 (IL-12) and IL-10 are proinflammatory cytokines, which play crucial role in Th1 and Th2 type immune response, respectively. IL-18 has a dual effect on T cell response: it was recognized as an IFN-gamma-inducing factor in T cells; acting in synergy with IL-12, leading to the development of Th1 type immune responses. But, in the absence of IL-12, IL-18 can promote the production of Th2 cytokines and take part in allergic inflammation. The aim of this study is to measure serum levels of IL-10, IL-12, and IL-18 in patients with FMF, and to investigate the relationship of their expressions with FMF attacks. Serum IL-10, IL-12, and IL-18 levels from patients with FMF were investigated. Thirty-one FMF patients with attack-free, 24 FMF patients with attack and 20 healthy controls were enrolled in the study. The levels of IL-10, IL-12p70 and IL-18 were measured by ELISA. Serum IL-10 levels were not different in FMF patients with attack and attack-free, and healthy controls. Serum IL-12 levels in FMF patients both with attack and attack-free were significantly higher than healthy controls (P = 0.002 and P = 0.047, respectively). There were no differences between FMF patients with attack and attack-free with regard to serum IL-12 levels. Serum IL-18 levels in FMF patients with attack and attack-free were significantly higher than healthy controls (P < 0.001 for both groups). With respect to serum IL-18 levels, no difference was found between FMF patients with attack and attack-free. Our results suggest that IL-12 and IL-18 contribute to the establishment of Th1 polarization seen in FMF and play a part in its pathogenesis. Detection of increased levels of IL-12 and IL-18 in patients with inactive disease implies that they seem to assist Th1 activation and subclinical inflammation persisting during the attack-free period of the disease.