Microbial lipopeptides induce the production of IL-17 in Th cells

The antimicrobial protein REG3A regulates keratinocyte proliferation and differentiation after skin injury

Epithelial keratinocyte proliferation is an essential element of wound repair, and abnormal epithelial proliferation is an intrinsic element in the skin disorder psoriasis. The factors that trigger epithelial proliferation in these inflammatory processes are incompletely understood. Here we have shown that regenerating islet-derived protein 3-alpha (REG3A) is highly expressed in keratinocytes during psoriasis and wound repair and in imiquimod-induced psoriatic skin lesions. The expression of REG3A by keratinocytes is induced by interleukin-17 (IL-17) via activation of keratinocyte-encoded IL-17 receptor A (IL-17RA) and feeds back on keratinocytes to inhibit terminal differentiation and increase cell proliferation by binding to exostosin-like 3 (EXTL3) followed by activation of phosphatidylinositol 3 kinase (PI3K) and the kinase AKT. These findings reveal that REG3A, a secreted intestinal antimicrobial protein, can promote skin keratinocyte proliferation and can be induced by IL-17. This observation suggests that REG3A may mediate the epidermal hyperproliferation observed in normal wound repair and in psoriasis.

ssICAM-1, IL-21 and IL-23 in patients with tick borne encephalitis and neuroborreliosis

Objective

There have been few reports on the role of Intercellular Adhesion Molecule 1 (ICAM-1), but not interleukin-21 (IL-21) and interleukin-23 (IL-23) in tick-borne encephalitis (TBE) and neuroborreliosis (NB). We postulate that these two interleukins may participate in the early phase of TBE and NB.

The aim of the study was to measure serum and cerebrospinal fluid (CSF) concentration of ICAM-1, IL-21 and IL-23 in patients with TBE and NB before treatment and to assess their usefulness in the diagnosis and monitoring of inflammatory process in TBE and NB.

Methods

Forty-three patients hospitalized in The Department of Infectious Diseases and Neuroinfections of Medical University in Bialystok, Poland, were included in the study. Patients were divided into three groups: TBE, NB and CG. Pre-treatment blood and CSF samples were obtained from all patients. ELISA kits (DRG Instruments, Germany) were used to measure the concentration of IL-21, IL-23 and sICAM-1.

Results

Significant differences between TBE/CG and NB/CG concentration of sICAM-1 were found only in the CSF. CSF IL-21 levels in NB were lower than in TBE.

In TBE, a strong negative correlation between CSF concentration of IL-21 and IL-23 and monocyte count in CSF was observed. Negative correlation between IL-21 in CSF and neutrophil count was also noted. Serum IL-23 correlated positively with leukocytes and platelet count in serum.

In NB, a strong positive correlation between serum IL-21 and platelet count and negative correlation between IL-21 in serum and CSF with pleocytosis was observed.

Conclusions

Increased sICAM-1 concentration in TBE and NB may be a proof of brain–blood barrier disturbances in the early phase of these diseases. IL-21 and IL-23 do not appear to play an important role in the pathogenesis of the early stages of TBE and NB.

Heterogeneity of multifunctional IL-17A producing S. Typhi-specific CD8+ T cells in volunteers following Ty21a typhoid immunization

Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever, continues to cause significant morbidity and mortality world-wide. CD8+ T cells are an important component of the cell mediated immune (CMI) response against S. Typhi. Recently, interleukin (IL)-17A has been shown to contribute to mucosal immunity and protection against intracellular pathogens. To investigate multifunctional IL-17A responses against S. Typhi antigens in T memory subsets, we developed multiparametric flow cytometry methods to detect up to 6 cytokines/chemokines (IL-10, IL-17A, IL-2, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and macrophage inflammatory protein-1β (MIP-1β)) simultaneously. Five volunteers were immunized with a 4 dose regimen of live-attenuated S. Typhi vaccine (Ty21a), peripheral blood mononuclear cells (PBMC) were isolated before and at 11 time points after immunization, and CMI responses were evaluated. Of the 5 immunized volunteers studied, 3 produced detectable CD8+ T cell responses following stimulation with S. Typhi-infected autologous B lymphoblastoid cell lines (B-LCL). Additionally, 2 volunteers had detectable levels of intracellular cytokines in response to stimulation with S. Typhi-infected HLA-E restricted cells. Although the kinetics of the responses differed among volunteers, all of the responses were bi- or tri-phasic and included multifunctional CD8+ T cells. Virtually all of the IL-17A detected was derived from multifunctional CD8+ T cells. The presence of these multifunctional IL-17A+ CD8+ T cells was confirmed using an unsupervised analysis program, flow cytometry clustering without K (FLOCK). This is the first report of IL-17A production in response to S. Typhi in humans, indicating the presence of a Tc17 response which may be important in protection. The presence of IL-17A in multifunctional cells co-producing Tc1 cytokines (IL-2, IFN-γ and TNF-α) may also indicate that the distinction between Tc17 and Tc1 responses in humans is not as clearly delineated as suggested by in vitro experiments and animal models.

Possible involvement of cytokines, chemokines and chemokine receptors in the initiation and progression of chronic GVHD

Chronic GVHD (cGVHD) after allogeneic hematopoietic SCT (HSCT) is characterized by an infiltration of T cells into target organs including the oral mucosa and salivary glands. This study was designed to clarify the molecular mechanism of the local accumulation of pathogenic T cells in cGVHD. The expression of cytokines, chemokines and chemokine receptors in the buccal mucosa (BM), labial salivary glands (LSG) and PBMC from 16 patients with cGVHD after allogeneic HSCT was examined. The mRNA expression of T helper 1 (Th1) and Th2 cytokines, and several chemokines and chemokine receptors was significantly increased in the BM and LSG from cGVHD patients, in comparison with both those in the BM and LSG from controls, respectively, and also with those in the PBMC from cGVHD patients. Furthermore, the mRNA expression of Th2 cytokines, macrophage-derived chemokine and CC chemokine receptor 4 was closely associated with a strong T-cell infiltration in the BM and LSG from cGVHD patients. These results suggest that cGVHD might be initiated and/or maintained by Th1/Th0 cells and thereafter progresses in association with Th2 cell accumulation via the interaction of particular chemokine and chemokine receptors.

Expression of IL-17 in inflammatory bowel disease and synergistic action of IL-17 and LPS on IL-8 expression in intestinal epithelial cells

AIM: To investigate the expression of interleukin-17 (IL-17) in inflammatory bowel disease (IBD) in a mouse model and to examine the synergistic reaction of IL-17 and lipopolysaccharide (LPS) on interleukin-8 (IL-8) expression in intestinal epithelial cells (HT-29 cells).

METHODS: A mouse model of inflammatory bowel disease was induced with TNBS to detect the expression of IL-17 and its receptor IL-17Ra in IBD. HT-29 cells were treated with IL-17 and/or different concentrations of LPS to examine their synergistic action on the expression of IL-8 mRNA and protein by FACS, real-time PCR, ELISA, and Western blot.

RESULTS: The expression of IL-17 and IL-17Ra in IBD was significantly increased (both P < 0.05). IL-17 and low doses of LPS showed a synergistic action on IL-8 expression in HT-29 cells (2187.61 ± 132.42 vs 2634.27 ± 134.63, P = 0.01) by activating NF-κB and promoting inflammation. However, high doses of LPS reduced the levels of IL-8, and their synergistic action with IL-17 disappeared (1841.43 ± 50.38 vs 1685.67 ± 71.47, P = 0.03).

CONCLUSION: IL-17 has a synergistic action with low, but not high doses of LPS on the expression of inflammatory mediators in HT-29 cells.

Coexpression of CCR6 and CD146 (MCAM) is a marker of effector memory T-helper 17 cells

Effector memory T (T(EM)) cells are a subpopulation of memory T cells that express receptors mediating migration to inflamed tissues and produce various cytokines. Effector memory T-helper (Th)17 (Th17(EM)) cells are thought to be essential for inflammation in Th17-mediated diseases, but have not been studied in detail. To identify superior surface markers to isolate a homogeneous population of Th17(EM) cells from peripheral blood, CD4(+) T cells were isolated from the peripheral blood of healthy donors based on the expression of CCR7, CCR6 and CD146 using six-color flow cytometry. After 4days of culture in the presence of anti-CD3/28 beads, intracellular cytokines were determined by flow cytometric analysis. To investigate the relevance of Th17(EM) cells in Th17-mediated disease, the frequencies of T(EM) -cell subsets in psoriasis were quantified using six-color flow cytometry. An enzyme-linked immunosorbent assay was performed to confirm the interleukin (IL)-17-producing capacity of T(EM) -cell subsets from the peripheral blood of a patient with psoriasis. CCR6(+) CD146(+) T(EM) (CD4(+) CD45RA(-) CCR7(-)) cells had a greater capacity to produce IL-17 than CCR6(+) CD146(-) or CCR6(-) CD146(+) T(EM) cells. Although the percentage of CCR6(+) CD146(+) cells in T(EM) cells was not significantly different between patients with psoriasis and controls, three of eight patients had a higher percentage of CCR6(+) CD146(+) T(EM) cells than the mean +5 standard deviations of the controls. Coexpression of CCR6 and CD146 is a useful marker for Th17(EM) cells. Increasing the number of CCR6(+) CD146(+) Th17(EM) cells in peripheral blood may facilitate estimation of systemic Th17-cell activity in Th17-mediated diseases.

Innate immunity in the central nervous system

Immune responses in the CNS are common, despite its perception as a site of immune privilege. These responses can be mediated by resident microglia and astrocytes, which are innate immune cells without direct counterparts in the periphery. Furthermore, CNS immune reactions often take place in virtual isolation from the innate/adaptive immune interplay that characterizes peripheral immunity. However, microglia and astrocytes also engage in significant cross-talk with CNS-infiltrating T cells and other components of the innate immune system. Here we review the cellular and molecular basis of innate immunity in the CNS and discuss what is known about how outcomes of these interactions can lead to resolution of infection, neurodegeneration, or neural repair depending on the context.

The Th17/IL-23 Axis and Natural Immunity in Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory skin disease that causes enthesitis and destructive arthritis and significantly lowers patient quality of life. Recognition of the two target organs (the skin and joints) involved in the immunopathophysiology of PsA helped in elucidating the pathology of various systemic autoimmune diseases targeting multiple organs. Recent advances in immunology and genetics have made it clear that acquired immunity, especially that mediated by the Th17/IL-23 axis, plays an important role in the inflammatory pathology observed in psoriasis and PsA. Additionally, involvement of natural immunity has also been suggested. Microbial infection has been known to trigger psoriasis and PsA. Recent clinical studies using biopharmaceuticals, such as tumor-necrosis-factor- (TNF-) α inhibitors and IL-12/23 p40 antibodies, indicate that studies need not be based only on the immunological phenomena observed in PsA pathology since disease pathology can now be verified using human-based science. Considering this aspect, this paper discusses the immunopathology of PsA compared to psoriasis (cutaneous) and rheumatoid arthritis in humans and immunopathology of PsA with respect to the Th17/IL-23 axis and microbial infection.

Th2 and regulatory immune reactions contribute to IgG4 production and the initiation of Mikulicz disease

OBJECTIVE

Mikulicz disease has been considered to be a subtype of Sjögren's syndrome (SS). However, recent studies have suggested that Mikulicz disease is an IgG4-related disease and is distinguishable from SS. In addition, it has been reported that both interleukin-4 (IL-4) and IL-10 induce IgG4 production and inhibit IgE. This study was undertaken to examine the expression of these cytokines in patients with Mikulicz disease and patients with SS.

METHODS

Labial salivary gland (LSG) sections from 15 patients with Mikulicz disease and 18 patients with SS were examined for subsets of the infiltrating lymphocytes, expression patterns of messenger RNA (mRNA) for cytokines/chemokines, and relationships between the IgG4:IgG ratio and the expression of mRNA for IL-4 or IL-10.

RESULTS

Immunohistochemical analysis showed lymphocyte infiltration of various subsets in the LSGs of SS patients, and the selective infiltration of IgG4-positive plasma cells and Treg cells in the LSGs of Mikulicz disease patients. The levels of mRNA for both Th1 and Th2 cytokines and chemokines in LSGs from patients with SS were significantly higher than in controls, while the expression of both Th2 and Treg cells was significantly higher in the patients with Mikulicz disease than in controls. Furthermore, the expression of IL-4 or IL-10 in the LSGs was correlated with the IgG4:IgG ratio.

CONCLUSION

These results suggest that the pathogenesis of Mikulicz disease is different from that of SS. Mikulicz disease is a unique inflammatory disorder characterized by Th2 and regulatory immune reactions that might play key roles in IgG4 production.

In Vivo Peripheral Blood Proinflammatory T Cells in Patients with Ankylosing Spondylitis

Objective.

Previous reports have shown an increase in peripheral blood mononuclear cells’ (PBMC) Th17 cell subpopulation and tumor necrosis factor-α (TNF-α) secretion after in vitro stimulation with anti-CD3/CD28 or phorbol myristate acetate/ionomycin in ankylosing spondylitis (AS). The aim of our study was to determine whether there is a Th17 polarization not subjected to in vitro stimulation in patients with AS.

Methods.

Nonstimulated PBMC were analyzed from 46 patients with AS, including 7 (15.2%) receiving tumor necrosis factor-α (TNF-α) inhibitors, 20 patients with rheumatoid arthritis, and 25 healthy controls. The surface phenotype of freshly isolated PBMC was determined by flow cytometry. Th1, Th2, Th17, and Treg subsets were defined as CD3+CD4+IFN-γ+, CD3+CD4+IL-4+, CD3+CD4+IL-17A+, and CD3+CD4+FoxP3+, respectively. Serum cytokines and interleukin 8 (IL-8) levels were quantified by Luminex technology.

Results.

The percentages of Th17 and Th1 cells in AS were higher than in healthy controls (7.4% ± 1.8% vs 0.7% ± 0.2% and 4.0% ± 1.3% vs 1.1% ± 0.3%, respectively; p < 0.0001). Th17 and Th1 cell subsets in patients taking TNF-α inhibitors were lower than in those naive to such therapeutics and similar to healthy controls. Serum levels of IL-6, IL-17A, TNF-α, and IL-8 were significantly higher in patients with AS compared to controls.

Conclusion.

The percentages of Th17 and Th1 cells in PBMC without in vitro stimulation, as well as cytokine and IL-8 levels, were significantly increased in patients with AS compared with healthy controls. These T cell subsets and cytokine profiles of patients with AS taking TNF-α inhibitors were similar to those of healthy controls.

Dysregulation of melanocyte function by Th17-related cytokines: significance of Th17 cell infiltration in autoimmune vitiligo vulgaris

The aim of this study was to determine whether CD4(+) IL-17A(+) Th17 cells infiltrate vitiligo skin and to investigate whether the proinflammatory cytokines related to Th17 cell influence melanocyte enzymatic activity and cell fate. An immunohistochemical analysis showed Th17 cell infiltration in 21 of 23 vitiligo skin samples in addition to CD8(+) cells on the reticular dermis. An in vitro analysis showed that the expression of MITF and downstream genes was downregulated in melanocytes by treatment with interleukin (IL)-17A, IL-1β, IL-6, and tumor necrosis factor (TNF)-α. Treatment with these cytokines also induced morphological shrinking in melanocytes, resulting in decreased melanin production. In terms of local cytokine network in the skin, IL-17A dramatically induced IL-1β, IL-6, and TNF-α production in skin-resident cells such as keratinocytes and fibroblasts. Our results provide evidence of the influence of a complex Th17 cell-related cytokine environment in local depigmentation in addition to CD8(+) cell-mediated melanocyte destruction in autoimmune vitiligo.

Respiratory syncytial virus vaccine development

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract viral disease in infants and young children. Presently, there are no explicit recommendations for RSV treatment apart from supportive care. The virus is therefore responsible for an estimated 160,000 deaths per year worldwide. Despite half a century of dedicated research, there remains no licensed vaccine product. Herein are described past and current efforts to harness innate and adaptive immune potentials to combat RSV. A plethora of candidate vaccine products and strategies are reviewed. The development of a successful RSV vaccine may ultimately stem from attention to historical lessons, in concert with an integral partnering of immunology and virology research fields.

Electrostatically Stabilized Magnetic Nanoparticles - An Optimized Protocol to Label Murine T Cells for in vivo MRI

We present a novel highly efficient protocol to magnetically label T cells applying electrostatically stabilized very small superparamagnetic iron oxide particles (VSOP). Our long-term aim is to use magnetic resonance imaging (MRI) to investigate T cell dynamics in vivo during the course of neuroinflammatory disorders such as experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Encephalitogenic T cells were co-incubated with VSOP, or with protamine-complexed VSOP (VProt), respectively, at different conditions, optimizing concentrations and incubation times. Labeling efficacy was determined by atomic absorption spectrometry as well as histologically, and evaluated on a 7 T MR system. Furthermore, we investigated possible alterations of T cell physiology caused by the labeling procedure. T cell co-incubation with VSOP resulted in an efficient cellular iron uptake. T2 times of labeled cells dropped significantly, resulting in prominent hypointensity on T2*-weighted scans. Optimal labeling efficacy was achieved by VProt (1 mM Fe/ml, 8 h incubation; T2 time shortening of ∼80% compared to untreated cells). Although VSOP promoted T cell proliferation and altered the ratio of T cell subpopulations toward a CD4⁺ phenotype, no effects on CD4 T cell proliferation or phenotypic stability were observed by labeling in vitro differentiated Th17 cells with VProt. Yet, high concentrations of intracellular iron oxide might induce alterations in T cell function, which should be considered in cell tagging studies. Moreover, we demonstrated that labeling of encephalitogenic T cells did not affect pathogenicity; labeled T cells were still capable of inducing EAE in susceptible recipient mice.

Aldosterone as a modulator of immunity: implications in the organ damage

High plasmatic levels of aldosterone cause hypertension and contribute to progressive organ damage to the heart, vasculature, and kidneys. Recent studies have demonstrated a role for the immune system in these pathological processes. Aldosterone promotes an inflammatory state characterized by vascular infiltration of immune cells, reactive oxidative stress, and proinflammatory cytokine production. Further, cells of the adaptive immune system, such as T cells, seem to participate in the genesis of mineralocorticoid hormone-induced hypertension. In addition, the observation that aldosterone can promote CD4⁺ T-cell activation and Th17 polarization suggests that this hormone could contribute to the onset of autoimmunity. Here we discuss recent evidence supporting a significant involvement of the immune system, especially adaptive immunity, in the genesis of hypertension and organ damage induced by primary aldosteronism. In addition, possible new therapeutic approaches consisting of immunomodulator drugs to control exacerbated immune responses triggered by elevated aldosterone concentrations will be described.

[Th1, Th17 and Th1+17 cells]

T helper cells contribute to the induction and maintenance of rheumatic inflammation through the secretion of cytokines. The analysis of Th1 cells expressing interferon-γ, Th17 cells expressing interleukin-17 and the newly described Th1+17 cells could give insight into the pathophysiological mechanisms of rheumatic diseases. This could lead to the development of novel, targeted therapeutic strategies.

Th1 responses are more susceptible to infliximab-mediated immunosuppression than Th17 responses

BACKGROUND

Treatment with infliximab, a chimeric anti-tumor necrosis factor (TNF)-α antibody, is highly efficient in patients with inflammatory bowel disease (IBD). It neutralizes soluble TNF-α and induces the apoptosis of transmembrane TNF-α-positive macrophages and T cells in the gut. Recently, T helper (Th)17, as well as Th1, responses have been implicated in the pathogenesis of IBD.

AIMS

To clarify the effects of infliximab on Th1 and Th17 responses in vitro.

METHODS

Naive CD4(+) T cells isolated from the peripheral blood of healthy volunteers were stimulated under Th1- or Th17-inducing conditions in the presence of 10 μg/ml of infliximab or control immunoglobulin (Ig)G1. The concentrations of interferon (IFN)-γ, interleukin (IL)-17, and TNF-α in the culture supernatants were determined by enzyme-linked immunosorbent assay (ELISA). Th1 and Th17 cells were immunostained with infliximab or control IgG1 and transmembrane TNF-α-positive cells were analyzed by flow cytometry. Annexin V staining and terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) assays were conducted in order to analyze the percentage of apoptotic cells.

RESULTS

Both Th1 and Th17 cells expressed soluble and transmembrane TNF-α abundantly. Although infliximab suppressed IFN-γ secretion by Th1 cells and IL-17 secretion by Th17 cells, the level of the former was more profound than the latter. Infliximab increased annexin V- and TUNEL-positive apoptotic cells under Th1-inducing conditions, but not under Th17-inducing conditions.

CONCLUSIONS

Infliximab suppressed Th1 and Th17 differentiation in vitro; however, IFN-γ production by Th1 cells was more profoundly suppressed than IL-17 secretion by Th17 cells. Th1 responses were more susceptible to infliximab-mediated apoptosis than Th17 responses. Our results clarify a new mechanism of action of infliximab.

Expansion of T helper type 17 lymphocytes in patients with chronic granulomatous disease

Hyper-immunoglobulin (Ig)E syndrome (HIES) is a primary immunodeficiency associated with mutations in STAT3 resulting in impaired development of T helper type 17 (Th17) lymphocytes. HIES patients with a reduced frequency of Th17 cells present with infections caused by Staphylococcus aureus and/or Candida strains. The same spectrum of pathogens is present in patients with chronic granulomatous disease (CGD).We analysed the characteristics of the Th17 compartment in HIES and CGD. HIES patients showed very low numbers of Th17 cells. By contrast, the frequency of Th17 cells and production of Th17-derived cytokines was significantly higher among CGD patients when compared to both control samples and HIES. Naive CD4(+) cells in CGD patients had a normal capacity to differentiate into IL-17-producing cells and the numbers of Th17 cells in the CGD patients normalized following successful bone marrow transplantation. Our findings complement recent data on the importance of Th17 cells for elimination of infections with C. albicans and S. aureus.

Role of interleukin-23 (IL-23) receptor signaling for IL-17 responses in human Lyme disease

Interleukin-23 (IL-23) is known to play a crucial role in the development and maintenance of T helper 17 cells. It has been previously demonstrated that IL-17 is involved in experimental Lyme arthritis, caused by Borrelia burgdorferi bacteria. However, the precise role of the IL-23 receptor (IL-23R) for the B. burgdorferi-induced IL-17 responses or human Lyme disease has not yet been elucidated. IL-23R single nucleotide polymorphism (SNP) rs11209026 was genotyped using the TaqMan assay. Functional studies were performed using peripheral blood mononuclear cells, and cytokines were measured using enzyme-linked immunosorbent assay (ELISA). Dose-dependent production of IL-23 and IL-17 by B. burgdorferi could be observed. Interestingly, when IL-23 bioactivity was inhibited by a specific antibody against IL-23p19, IL-17 production was significantly downregulated. In contrast, production of gamma interferon (IFN-γ) was not affected after the blockade of IL-23 activity. Moreover, individuals bearing a single nucleotide polymorphism in the IL-23R gene (Arg381Gln) produced significantly less IL-17 after B. burgdorferi stimulation compared with that of the individuals bearing the wild type. Despite lower IL-17 production, the IL-23R gene polymorphism did not influence the development of chronic Lyme disease in a cohort of patients with Lyme disease. This study demonstrates that IL-23R signaling is needed for B. burgdorferi-induced IL-17 production in vitro and that an IL-23R gene SNP leads to impaired IL-17 production. However, the IL-23R gene polymorphism is not crucial for the pathogenesis of chronic Lyme.

Polymerized-type I collagen induces upregulation of Foxp3-expressing CD4 regulatory T cells and downregulation of IL-17-producing CD4⁺ T cells (Th17) cells in collagen-induced arthritis

Previous studies showed that polymerized-type I collagen (polymerized collagen) exhibits potent immunoregulatory properties. This work evaluated the effect of intramuscular administration of polymerized collagen in early and established collagen-induced arthritis (CIA) in mice and analyzed changes in Th subsets following therapy. Incidence of CIA was of 100% in mice challenged with type II collagen. Clinimorphometric analysis showed a downregulation of inflammation after administration of all treatments (P < 0.05). Histological analysis showed that the CIA-mice group had extensive bone erosion, pannus and severe focal inflammatory infiltrates. In contrast, there was a remarkable reduction in the severity of arthritis in mice under polymerized collagen, methotrexate or methotrexate/polymerized collagen treatment. Polymerized Collagen but not methotrexate induced tissue joint regeneration. Polymerized Collagen and methotrexate/polymerized collagen but not methotrexate alone induces downregulation of CD4⁺/IL17A⁺ T cells and upregulation of Tregs and CD4⁺/IFN-γ⁺ T cells. Thus, Polymerized Collagen could be an effective therapeutic agent in early and established rheumatoid arthritis by exerting downregulation of autoimmune inflammation.

TLR1/TLR2 heterodimers play an important role in the recognition of Borrelia spirochetes

After infection with Borrelia species, the risk for developing Lyme disease varies significantly between individuals. Recognition of Borrelia by the immune system is mediated by pattern recognition receptors (PRRs), such as TLRs. While TLR2 is the main recognition receptor for Borrelia spp., little is known about the role of TLR1 and TLR6, which both can form functionally active heterodimers with TLR2. Here we investigated the recognition of Borrelia by both murine and human TLR1 and TLR6. Peritoneal macrophages from TLR1- and TLR6- gene deficient mice were isolated and exposed to Borrelia. Human PBMCs were stimulated with Borrelia with or without specific TLR1 and TLR6 blocking using specific antibodies. Finally, the functional consequences of TLR polymorphisms on Borrelia-induced cytokine production were assessed. Splenocytes isolated from both TLR1−/− and TLR6−/− mice displayed a distorted Th1/Th2 cytokine balance after stimulation with B.burgdorferi, while no differences in pro-inflammatory cytokine production were observed. In contrast, blockade of TLR1 with specific neutralizing antibodies led to decreased cytokine production by human PBMCs after exposure to B.burgdorferi. Blockade of human TLR6 did not lead to suppression of cytokine production. When PBMCs from healthy individuals bearing polymorphisms in TLR1 were exposed to B.burgdorferi, a remarkably decreased in vitro cytokine production was observed in comparison to wild-type controls. TLR6 polymorphisms lead to a minor modified cytokine production. This study indicates a dominant role for TLR1/TLR2 heterodimers in the induction of the early inflammatory response by Borrelia spirochetes in humans.

Potential role of Mycoplasma hominis in interleukin (IL)-17-producing CD4+ T-cell generation via induction of IL-23 secretion by human dendritic cells

BACKGROUND

Mycoplasma hominis, a human urogenital pathogen, is involved in genital and extragenital infections and arthritis, particularly in immunocompromised patients. The interleukin (IL) 23/T helper (Th) 17 axis is associated with inflammatory and autoimmune diseases. The aim of this study was to assess the IL-23 response to M. hominis in human dendritic cells (DCs) and the CD4(+) T-cell differentiation in response to M. hominis-infected DCs.

METHODS

Human monocyte-derived DCs were cultured with phosphate-buffered saline, lipopolysaccharide, or M. hominis PG21. Cocultures with heterologous T cells were performed. Extracts from M. hominis were separated and incubated with DCs. Isolates from different clinical syndromes were tested.

RESULTS

M. hominis induced the maturation of human DCs with predominant IL-23 secretion in a Toll-like receptor 2-dependent manner. The in vitro immunomodulatory capacity of M. hominis was contained in a lipoprotein-enriched fraction from the mycoplasma. M. hominis-activated DCs induced IL-17-producing CD4(+) T cells. Interestingly, clinical isolates differed in their ability to promote IL-23 secretion by DCs.

CONCLUSIONS

Taken together, our findings demonstrate a major role for the IL-23/Th17 axis in the defense against M. hominis and indicate a potential role for these bacteria in inflammatory and autoimmune diseases.

The active contribution of Toll-like receptors to allergic airway inflammation

Epithelia lining the respiratory tract represent a major portal of entry for microorganisms and allergens and are equipped with innate and adaptive immune signaling receptors for host protection. These include Toll-like receptors (TLRs) that recognize microbial components and evoke diverse responses in cells of the respiratory system. TLR stimulation by microorganism-derived molecules activates antigen presenting cells, control T helper (Th) 1, Th2, and Th17 immune cell differentiation, cytokine production by mast cells, and activation of eosinophils. It is clear that TLR are involved in the pathophysiology of allergic airway diseases such as asthma. Dendritic cells (DCs), a kind of antigen presenting cells, which play a key role in the induction of allergic airway inflammation, are privileged targets for pathogen associated molecular patterns (PAMPs). During the allergic responses, engagement of TLRs on DCs determines the Th2 polarization of the T cells. TLR signaling in mast cells increases the release of IL-5, and TLR activation of airway epithelial cells forces the generation of proallergic Th2 type of cytokines. Although these responses aim to protect the host, they may also result in inflammatory tissue damage in the airway. Under certain conditions, stimulation of TLRs, in particular, TLR9, may reduce Th2-dependent allergic inflammation by induction of Th1 responses. Therefore, understanding the complex regulatory roles of TLRs in the pathogenesis of allergic airway inflammation should facilitate the development of preventive and therapeutic measures for asthmatic patients.

Circulating IL-17 levels during the peri-transplant period as a predictor for early leukemia relapse after myeloablative allogeneic stem cell transplantation

IL-17 is involved in inducing and mediating pro-inflammatory responses. The association of IL-17 with tumor growth or graft-versus-host disease (GVHD) has become a subject of controversy. We hypothesized that serum IL-17 (sIL-17) levels during the peri-transplant period may affect alloreactive responses after allogeneic stem cell transplantation (SCT). sIL-17 levels of 95 patients with leukemia who had undergone myeloablative allogeneic SCT were measured using ELISA before conditioning and on day 0, +7, and +14 after transplantation. With a median follow-up of 17 months, the overall survival, disease-free survival, non-relapse mortality, and relapse incidence were 70.9%, 66.3%, 10.3%, and 23.4%, respectively. Ten patients relapsed within 180 days (early relapse, 10.5%) post-transplant. The cumulative incidence of acute GVHD over grade II and chronic GVHD was 55.8% and 69.0%, respectively. Analyses using repeated measures of ANOVA and mean values of sIL-17 revealed that patients relapsed within 180 days had higher sIL-17 levels, whereas no association existed between sIL-17 levels and other clinical outcomes, including acute GVHD. Receiver operating characteristic curve analyses also revealed that sIL-17 levels were available for the prediction of early relapse and that patients with higher sIL-17 levels at each time point had a significantly higher early relapse. Multivariate analyses and subgroup analyses with only standard disease status suggest the association of sIL-17 levels with subsequent early relapse independent of disease status at transplantation. This study is the first one demonstrating the early change in sIL-17 during the peri-transplant period and the association with early relapse in humans.

Diagnostic value of interleukin 22 and carcinoembryonic antigen in tuberculous and malignant pleural effusions

The aim of this study was to investigate the diagnostic value of interleukin 22 (IL-22) and carcinoembryonic antigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleural effusion samples from 56 patients were classified on the basis of diagnosis as TPE (n=28) and MPE (n=28). The concentration of IL-22 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase (ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levels of ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration of IL-22 in TPE was significantly higher compared to MPE (P<0.01). With a threshold value of 49 pg/ml, IL-22 had a sensitivity of 82.14% (23/28) and a specificity of 96.43% (27/28) for differential diagnosis. The combined detection of IL-22 and CEA had a sensitivity of 100% (28/28) and a specificity of 96.43% (27/28) to distinguish TPE from MPE. TPEs showed significantly higher levels of IL-22 compared to MPEs. The combined detection of IL-22 and CEA may be more valuable in the differential diagnosis between TPE and MPE.

Th17 cell, the new player of neuroinflammatory process in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by recurrent episodes of demyelination and axonal lesion mediated by CD4(+) T cells with a proinflammatory Th1 and Th17 phenotype, macrophages, and soluble inflammatory mediators. Identification of Th17 cells led to breaking the dichotomy of Th1/Th2 axis in immunopathogenesis of autoimmune diseases such as MS, and its experimental model, experimental autoimmune encephalomyelitis (EAE). Th17 cells are characterized by expression of retinoic acid-related orphan receptor (ROR)γt and signal transducer and activator of transcription 3 (STAT3) factors. Th17-produced cytokine profile including interleukin (IL)-17, IL-6, IL-21, IL-22, IL-23 and tumour necrosis factor (TNF)-α, which have proinflammatory functions, suggests it as an important factor in immunopathogenesis of MS, because the main feature of MS pathophysiology is the neuroinflammatory reaction. The blood brain barrier (BBB) disruption is an early and central event in MS pathogenesis. Autoreactive Th17 cells can migrate through the BBB by the production of cytokines such as IL-17 and IL-22, which disrupt tight junction proteins in the central nervous system (CNS) endothelial cells. Consistent with this observation and regarding the wide range production of proinflammatory cytokines and chemokines by Th17 cells, it is expected that Th17 cell to be as a potent pathogenic factor in disease immunopathophysiology. Th17-mediated inflammation is characterized by neutrophil recruitment into the CNS and neurons killing. However, the majority of our knowledge about the role of Th17 in MS pathogenesis is resulted in investigation into EAE animal models. In this review, we intend to focus on the newest information regarding the precise role of Th17 cells in immunopathogenesis of MS, and its animal model, EAE.

Prior or coinstantaneous oral exposure to environmental immunosuppressive agents aggravates mite allergen-induced atopic dermatitis-like immunoreaction in NC/Nga mice

BACKGROUND

Immunosuppressive environmental chemicals may increase the potency of allergens and thereby play a role in the development of allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (AD).

OBJECTIVES

This study's primary objective was to examine the mechanisms behind the development of allergic diseases and immunosuppression induced by some environmental chemicals. We focused on the aggravation of AD by the organophosphorus pesticide O,O-diethyl-O-4-nitro-phenylthiophosphate (parathion) and the organochlorine pesticide 1,1,1-trichloro-2,2-bis(4-methoxyphenyl)ethane (methoxychlor), in NC/Nga mice sensitized with extract of Dermatophagoides farinae (Df).

METHODS

NC/Nga mice were exposed orally to parathion or methoxychlor prior or coinstantaneous with sensitization with Df. The mice were subsequently challenged with Df. One day after the last challenge with Df, we analyzed dermatitis severity and expression of genes in the ear auricle, immunoglobulin (Ig) E and IgG(2a) levels in serum, and in auricular lymph nodes, T- or B-cell numbers and cytokine production.

RESULTS

Prior exposure to parathion or methoxychlor induced marked increases in the following: dermatitis severity and gene expression in the ear auricle, IgE and IgG(2a) levels in serum, expression of surface antigens on helper T-cell and IgE-positive B-cell, production of Th1 and Th2 cytokines, and production of IgE in auricular lymph-node cells. In contrast, coinstantaneous exposure to parathion or methoxychlor yielded, at most, small but significant decreases in all parameters.

CONCLUSIONS

Our results indicate that atopic dermatitis can be aggravated by prior exposure to immunosuppressive environmental chemicals.

Induction of proinflammatory cytokines in human osteoblastic cells by Chlamydia pneumoniae

Chlamydia pneumoniae is an obligate intracellular Gram-negative bacterium that causes recurrent pharyngitis, pneumonia and chronic inflammation induced by cycles of persistence and productive infection that might also explain the association with chronic diseases. The aim of this study was to determine whether C. pneumoniae can invade and survive within human osteoblasts and whether this infection elicits the secretion of proinflammatory cytokines. Our results demonstrated that C. pneumoniae was able to infect the SaOS-2 osteoblastic cell line and to replicate in the osteoblasts in a time-dependent manner and was associated to an increase in the cell number and cell viability. In addition, infection of the SaOS-2 cell line with C. pneumoniae at MOI of 4 is correlated to a proinflammatory response. Infected osteoblasts produced increased levels of cytokines IL-6, IL-8, IL-17, and IL-23. The production of cytokines increased with subsequent interaction between osteoblasts and monocytes and the maximum levels of cytokines released were detected 72 h after infection with C. pneumoniae. Thus, controlling the release of chemokines, e.g., IL-23, may be a therapeutic strategy for preventing inflammatory bone disease and counteract inflammation and bone destruction.

TGF-β function in immune suppression

Transforming growth factor-β (TGF-β) has been shown to play an essential role in establishing immunological tolerance, yet recent studies have revealed the pro-inflammatory roles of TGF-β in inflammatory responses. TGF-β induces Foxp3-positive regulatory T cells (iTregs), while in the presence of IL-6, it induces pathogenic IL-17 producing Th17 cells. TGF-β inhibits the proliferation of T cells as well as cytokine production via Foxp3-dependent and independent mechanisms. On the one hand, little is known about molecular mechanisms involved in immune suppression via TGF-β; however, recent studies suggest that Smad2 as well as Smad3 play essential roles in Foxp3 induction and cytokine suppression, whereas Th17 differentiation is promoted via the Smad-independent pathway. Mutual suppression of signaling between TGF-β and inflammatory cytokines has been shown to be necessary for the balance of immunity and tolerance.

Protective live oral brucellosis vaccines stimulate Th1 and th17 cell responses

Zoonotic transmission of brucellosis often results from exposure to Brucella-infected livestock, feral animals, or wildlife or frequently via consumption of unpasteurized milk products or raw meat. Since natural infection of humans often occurs by the oral route, mucosal vaccination may offer a means to confer protection for both mucosal and systemic tissues. Significant efforts have focused on developing a live brucellosis vaccine, and deletion of the znuA gene involved in zinc transport has been found to attenuate Brucella abortus. A similar mutation has been adapted for Brucella melitensis and tested to determine whether oral administration of ΔznuA B. melitensis can confer protection against nasal B. melitensis challenge. A single oral vaccination with ΔznuA B. melitensis rapidly cleared from mice within 2 weeks and effectively protected mice upon nasal challenge with wild-type B. melitensis 16M. In 83% of the vaccinated mice, no detectable brucellae were found in their spleens, unlike with phosphate-buffered saline (PBS)-dosed mice, and vaccination also enhanced the clearance of brucellae from the lungs. Moreover, vaccinated gamma interferon-deficient (IFN-γ(-/-)) mice also showed protection in both spleens and lungs, albeit protection that was not as effective as in immunocompetent mice. Although IFN-γ, interleukin 17 (IL-17), and IL-22 were stimulated by these live vaccines, only RB51-mediated protection was codependent upon IL-17 in BALB/c mice. These data suggest that oral immunization with the live, attenuated ΔznuA B. melitensis vaccine provides an attractive strategy to protect against inhalational infection with virulent B. melitensis.

IL-17-expressing cells as a potential therapeutic target for treatment of immunological disorders

IL-17 is a multifunctional cytokine produced by activated CD4+ and CD8+ lymphocytes as well as stimulated unconventional Tγδ and natural killer T cells. IL-17 induces expression of chemokines, proinflammatory cytokines and metalloproteinases, thereby stimulating the inflammation and chemotaxis of neutrophils. Elevation of proinflammatory cytokines is associated with asthma and autoimmune disorders, such as multiple sclerosis, rheumatoid arthritis and psoriasis. Although the role of IL-17 in these disorders is not always easy to define, extensive research has demonstrated an aggravating influence of IL-17 in some animal models. Thus, the development of therapeutics to reduce IL-17 levels is a promising strategy for ameliorating inflammatory diseases. This review briefly summarizes recent knowledge about stimulants and intracellular signaling pathways that induce development and maturation of IL-17-expressing cells. Its positive and negative roles on disease progression and its importance in vaccine-induced memory are also discussed. Finally, recent literature describing potential therapeutic approaches for targeting IL-17 is presented.

Targeting IL-23: insights into the pathogenesis and the treatment of psoriasis

Therapeutic experience strongly supports the use of TNF antagonists as important modalities in the treatment of psoriatic arthritis and plaque psoriasis. Studies with anti-IL-12/23 therapeutic agents, which act in different steps of the psoriatic inflammatory cascade, have also shown demonstrable efficacy. Here, we discuss this approach and its potential within the armamentarium for the treatment of psoriasis. Evidences that the selective blocking of IL-23 may be effective and safe therapy are also addressed.

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.

Interleukin-23 and T helper 17-type responses in intestinal inflammation: from cytokines to T-cell plasticity

Interleukin-23 (IL-23) plays an essential role in driving intestinal pathology in experimental models of both T-cell-dependent and innate colitis. Furthermore, genome-wide association studies have identified several single-nucleotide polymorphisms in the IL-23 receptor (IL-23R) gene that are associated with either susceptibility or resistance to inflammatory bowel disease in humans. Although initially found to support the expansion and maintenance of CD4(+) T helper 17 (Th17) cells, IL-23 is now recognized as having multiple effects on the immune response, including restraining Foxp3(+) regulatory T-cell activity and inducing the expression of Th17-type cytokines from non-T-cell sources. Here we focus on Th17 cells and their associated cytokines IL-17A, IL-17F, IL-21 and IL-22. We review studies performed in mouse models of colitis where these effector cytokines have been shown to have either a pathogenic or a tissue-protective function. We also discuss the heterogeneity found within the Th17 population and the phenomenon of plasticity of Th17 cells, in particular the ability of these lymphocytes to extinguish IL-17 expression and turn on interferon-γ production to become Th1-like 'ex-Th17' cells. Interleukin-23 has been identified as a key driver in this process, and this may be an additional mechanism by which IL-23 promotes pathology in the intestinal tract. These 'ex-Th17' cells may contribute to disease pathogenesis through their secretion of pro-inflammatory mediators.

Interleukin-35 enhances Lyme arthritis in Borrelia-vaccinated and -infected mice

Interleukin-35 (IL-35) has been reported to inhibit the production of interleukin-17 (IL-17) as a means of preventing arthritis and other inflammatory diseases. We previously showed that treatment of Borrelia-vaccinated and -infected mice with anti-IL-17 antibody at the time of infection prevented the development of arthritis. The anti-IL-17 antibody-treated mice lacked the extensive tissue damage, such as bone and cartilage erosion, that occurred in the tibiotarsal joints of untreated Borrelia-vaccinated and -infected control mice. We hypothesized that IL-35 would reduce the severity of arthritis by suppressing the production of IL-17 in Borrelia-vaccinated and -infected mice. Here, we show that administration of recombinant IL-35 (rIL-35) to Borrelia-vaccinated and -infected mice augments the development of severe arthritis compared to the results seen with untreated control mice. Borrelia-vaccinated and -infected mice treated with rIL-35 had significantly (P < 0.05) greater hind paw swelling and histopathological changes from day 4 through day 10 than non-rIL-35-treated Borrelia-vaccinated and -infected mice. In addition, the treatment with IL-35 only slightly decreased the production of IL-17 in Borrelia-primed immune cells and did not prevent the development of borreliacidal antibody. Our data do not support a role for IL-35 as a potential therapeutic agent to reduce inflammation in Lyme arthritis.

The encephalitogenicity of T(H)17 cells is dependent on IL-1- and IL-23-induced production of the cytokine GM-CSF

Interleukin 17 (IL-17)-producing helper T cells (T(H)17 cells) require exposure to IL-23 to become encephalitogenic, but the mechanism by which IL-23 promotes their pathogenicity is not known. Here we found that IL-23 induced production of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) in T(H)17 cells and that GM-CSF had an essential role in their encephalitogenicity. Our findings identify a chief mechanism that underlies the important role of IL-23 in autoimmune diseases. IL-23 induced a positive feedback loop whereby GM-CSF secreted by T(H)17 cells stimulated the production of IL-23 by antigen-presenting cells. Such cross-regulation of IL-23 and GM-CSF explains the similar pattern of resistance to autoimmunity when either of the two cytokines is absent and identifies T(H)17 cells as a crucial source of GM-CSF in autoimmune inflammation.

Diversity and flexibility of Th17 effector functions

IL-17-producing CD4+ T-helper cells (Th17 cells) have been recognised as important drivers of pathogenesis in a multitude of inflammatory diseases, including arthritis. The cytokines and transcription factors that instruct and execute Th17 lineage differentiation have been identified. This has induced hopes that targeting Th17 cells might yield a magic bullet against autoimmune diseases. A new wave of published reports shows that matters are more complicated: Th cells can coexpress IL-17 with a variety of other cytokines, including IFNγ, IL-4, or IL-10, with different functional consequences. Moreover, IL-17 memory is not stable--Th17 cells can be instructed to express other lineage-defining cytokines and to halt IL-17 expression. Finally, Th17 cells may exert tissue-protective effects, even in the context of some inflammatory diseases. Manipulating Th17 cells or IL-17 effects may be more difficult than initially appreciated. Notwithstanding these facts, IL-17 remains a valuable and even more interesting therapeutic target.

IL-17A induces CCL28, supporting the chemotaxis of IgE-secreting B cells

BACKGROUND

Atopic asthma is an allergic disease typically associated with T(H)2 cytokines. IL-17A is also associated with asthma, through the induction of chemokines. Mucosal CCL28 concentrations correlate with cellular recruitment to inflamed airways and support migration of IgA(+) B cells. Here, a link between IL-17A, CCL28 and IgE-secreting B cell chemotaxis is examined.

METHODS

Primary human airway cells and the airway epithelial line A549 were used to characterize IL-17A receptor expression and the effect of IL-17A on CCL28 transcription and translation. B cells, differentiated to IgE+ cells ex vivo, were assessed for CCR10 surface expression and chemotaxis to CCL28 by flow cytometry, transwell migration and ELISpot.

RESULTS

Human airway epithelium expressed both IL-17RA and IL-17RC, and was responsive to IL-17A stimulation. Cultured human IgE+ B cells expressed surface CCR10 and displayed CCR10-dependent chemotaxis towards recombinant CCL28. Enhanced levels of CCL28 were observed upon A549 cell incubation with IL-17A, and this up-regulation significantly increased the migration of IgE+ antibody-secreting B cells. The specificity of chemotaxis was confirmed by migration blockade in the presence of anti-CCL28 or anti-CCR10.

CONCLUSIONS

This work identifies a novel chemokine for the migration of IgE+ B cells, in addition to characterizing induction of CCL28 by IL-17A. Taken together the results presented here propose a new role for IL-17A in the allergic airways, linking this cytokine with the recruitment of IgE+ antibody-secreting B cells, via the induction of CCL28. These observations justify further in vivo studies of larger cohorts.

Effect of non-surgical periodontal therapy on the levels of Th17/Th1/Th2 cytokines and their transcription factors in Chinese chronic periodontitis patients

AIM

A new subset of CD4(+) T cells, Th17, has been recently discovered independent from Th1/Th2 paradigm. The aim of this study was to investigate the effects of non-surgical periodontal therapy on the expression of Th17/Th1/Th2 cytokines and transcription factors, and Th17 cell vibration in Chinese chronic periodontitis patients.

MATERIALS AND METHODS

The levels of Th17/Th1/Th2 cytokines (IL-17, IL-21/IFN-γ/IL-4) in gingival crevicular fluid from 30 chronic periodontitis patients before and after treatment were determined by ELISA. The expression of transcription factors (RORC, T-bet and GATA-3) in peripheral blood was measured by real-time PCR, and the levels of Th17 cells in CD4(+) T cells were determined by flow cytometry.

RESULTS

After treatment, the levels of IL-17 and IL-21 were down-regulated (P<0.05), and IL-4 was increased (P<0.05), but there were no differences in the level of IFN-γ (P>0.05). Correspondingly, the expression of RORC was decreased 1.99-fold (P<0.05), and GATA-3 was increased 1.76-fold (P<0.05). However, there were no differences in the level of T-bet (P>0.05). Moreover, the quantity of Th17 cells in peripheral blood was decreased (P<0.05), especially IL-17(+) IFN-γ(+) subgroup.

CONCLUSIONS

These results suggest that Th17 cells play a destructive role in the immune balance of periodontitis, and the effect of Th1 cells is not significant, while Th2 cells have a protective effect.

Significant differences between the Borrelia-infection and Borrelia-vaccination and -infection models of Lyme arthritis in C3H/HeN mice

The immunological events leading to the development of Lyme arthritis in humans are partially understood. Much of this information has been gained by studying the course of infection of naïve or vaccinated mice with Borrelia burgdorferi. However, the Borrelia-vaccination and -infection model has not been described using the organismal parameters commonly used in the widely accepted Borrelia-infection model. This is the first comparison between the Borrelia-infection and the Borrelia-vaccination and -infection models of arthritis. Borrelia-vaccinated and -infected C3H/HeN mice develop acute inflammation comparable to that of nonvaccinated, Borrelia-infected C3H/HeN mice. The duration and severity of arthritis in Borrelia-vaccinated and -infected mice was slightly increased compared with Borrelia-infected mice. Significantly, Borrelia-vaccinated and -infected C3H/HeN mice produce interleukin-17 (IL-17), while Borrelia-infected mice that had not been previously vaccinated do not. Neutralization of IL-17 in Borrelia-vaccinated and -infected C3H/HeN mice decreased the severity of arthritis, although not to the degree we observed previously in C57BL/6 mice. Collectively, these findings show that the Borrelia-vaccination and -infection model of Lyme arthritis incorporates elements of adaptive immunity that likely have relevance to human disease, but may not be observed in Borrelia-infected C3H/HeN mice.

Interleukin-17A is required to suppress invasion of Salmonella enterica serovar Typhimurium to enteric mucosa

Salmonella enterica serovar Typhimurium (S. typhimurium) causes a localized enteric infection and its elimination is dependent on a T helper type 1 immune response. However, the mechanism of the protective immune response against the pathogen in gut-associated lymphoid tissue (GALT) at an early stage of the infection is not yet clarified. Here, we show that interleukin-17A (IL-17A) was constitutively expressed in GALT; it was also detected on crypt and epithelial cells of the small intestine. Neutralization of the IL-17A in the intestinal lumen exacerbated epithelial damage induced by intestinal S. typhimurium infection at an early stage of the infection. The result suggests that IL-17A has a pivotal role in the immediate early stage of protection against bacterial infection at the intestinal mucosa. As IL-17A neutralization also suppressed the constitutive localization of β-defensin 3 (BD3), an IL-17A-induced antimicrobial peptide, at the apical site of the intestinal mucosa, it is estimated that IL-17A constitutively induces the expression of the antimicrobial peptide to kill invading pathogens at the epithelial surface immediately after the infection. In contrast, interferon-γ is induced around 3 days after S. typhimurium infection, and its expression level increases thereafter. Taken together, the findings lead to the hypothesis that IL-17A participates in the immediate early stage of protection against S. typhimurium intestinal infection whereas interferon-γ is important at a later stage of the infection.

CD4+CD25+ regulatory T cells suppress Th17-responses in an experimental colitis model

BACKGROUND

After the recent discovery of Th17 cells, it was proposed that Th17 responses are involved in the pathogenesis of inflammatory bowel diseases (IBD). CD4(+)CD25(+) regulatory T cells (Treg) are considered to be an attractive tool for the treatment of IBD. Here, we investigated whether Treg are capable of suppressing Th17-mediated colitis.

METHODS

Naive CD4(+) T cells were transferred into SCID mice with or without Treg. In some experiments, Treg were transferred into recipient mice with established colitis. Mice treated with Treg were injected with an anti-transforming growth factor (TGF)-β mAb or control IgG. Clinical symptoms of colitis, histological changes and cytokine expressions were investigated.

RESULTS

SCID mice transferred with naive CD4(+) T cells developed chronic colitis with significant increases in Th1 and Th17 cytokine expressions in the colon. When Treg were co-transferred with naive CD4(+) T cells, development of colitis was prevented, and Th17 cytokine expressions were markedly reduced. Similarly, when Treg were transferred into mice with established colitis, the colitis was significantly ameliorated in association with dramatic reductions in Th17 cytokine expressions. Injection of anti-TGF-β mAb abolished the Treg-mediated suppression with significant elevations in Th17 cytokine productions.

CONCLUSION

This adoptive transfer model of colitis was associated with augmented Th1 and Th17 responses, and Treg were capable of suppressing colonic inflammation by downregulating Th17 responses as well as Th1 responses via TGF-β. Consequently, Treg transfer therapy is expected to be efficacious for IBD even if Th17 is involved in the pathogenesis.

Effects of AIN457, a fully human antibody to interleukin-17A, on psoriasis, rheumatoid arthritis, and uveitis

Interleukin-17A (IL-17A) is elaborated by the T helper 17 (T(H)17) subset of T(H) cells and exhibits potent proinflammatory properties in animal models of autoimmunity, including collagen-induced arthritis, experimental autoimmune encephalomyelitis, and experimental autoimmune uveitis. To determine whether IL-17A mediates human inflammatory diseases, we investigated the efficacy and safety of AIN457, a human antibody to IL-17A, in patients with psoriasis, rheumatoid arthritis, and chronic noninfectious uveitis. Patients with chronic plaque-type psoriasis (n = 36), rheumatoid arthritis (n = 52), or chronic noninfectious uveitis (n = 16) were enrolled in clinical trials to evaluate the effects of neutralizing IL-17A by AIN457 at doses of 3 to 10 mg/kg, given intravenously. We evaluated efficacy by measuring the psoriasis area and severity index (PASI), the American College of Rheumatology 20% response (ACR20) for rheumatoid arthritis, or the number of responders for uveitis, as defined by either vision improvement or reduction in ocular inflammation or corticosteroid dose. AIN457 treatment induced clinically relevant responses of variable magnitude in patients suffering from each of these diverse immune-mediated diseases. Variable response rates may be due to heterogeneity in small patient populations, differential pathogenic roles of IL-17A in these diseases, and the different involvement or activation of IL-17A-producing cells. The rates of adverse events, including infections, were similar in the AIN457 and placebo groups. These results support a role for IL-17A in the pathophysiology of diverse inflammatory diseases including psoriasis, rheumatoid arthritis, and noninfectious uveitis.