Migration Of Th17 Cells Research Articles

LB1572 Two rat models of psoriasis for drug development

Psoriasis is the most common chronic autoimmune skin condition, impacting roughly 125 million people worldwide. The pathogenesis is not wholly understood, though an assumed complex interplay between environmental factors, immune dysregulation and genetic susceptibility. Data suggests that an environmental/pathogenic insult to the skin precipitates the activation of immune cells in the skin leading to a dysregulated pro-inflammatory response. This response triggers secretion of IL-12 and IL-23, causing migration and differentiation of Th17 and Th1 cells. These cells release cytokines such as IL-22 and IL-17A/F driving proliferation of keratinocytes and epithelial cells. It has become increasingly important to model this disease, in immune competent animals such as rats. To this end, MD Biosciences has optimized two psoriasis models in the rat. IMQ mimics a pathogenic insult to the skin, eliciting a robust Th17 immune response leading to plaque formation. IMQ is applied to the shaved backs and ears of naïve rats, and disease progression and skin thickening is monitored. Diseased animals exhibit erythema and plaque formation shortly after the start of the study and progress through termination accompanied by increased biomarkers, IL-22, IL17A and IL-17F. IL-23 is the main pathogenic cytokine in the initiation of psoriasis disease progression and has become a lead target for the clinical treatment. Exogenous IL-23 can be delivered directly to the dermis of rats to induce a downstream cascade of inflammatory biomarker upregulation, erythema and epidermal hyperplasia, similar to what is seen in human psoriatic plaques. The IMQ- and IL-23-induced psoriasis models are robust pre-clinical models to help develop therapeutics, as both models mimic specific disease pathologies. These models can be used to assess efficacy of candidate drugs for pathogenic pathway targeting such as Th17 and IL-23/IL-17. The versatility of the models and the benefits of the rat as a host organism make these models ideal for pre-clinical drug development for psoriasis or other Th17/IL-17 dependent diseases.

Blockade of MCAM/CD146 impedes CNS infiltration of T cells over the choroid plexus

BackgroundVery late antigen 4 (VLA-4; integrin α4β1) is critical for transmigration of T helper (TH) 1 cells into the central nervous system (CNS) under inflammatory conditions such as multiple sclerosis (MS). We have previously shown that VLA-4 and melanoma cell adhesion molecule (MCAM) are important for trans-endothelial migration of human TH17 cells in vitro and here investigate their contribution to pathogenic CNS inflammation.MethodsAntibody blockade of VLA-4 and MCAM is assessed in murine models of CNS inflammation in conjunction with conditional ablation of α4-integrin expression in T cells. Effects of VLA-4 and MCAM blockade on lymphocyte migration are further investigated in the human system via in vitro T cell transmigration assays.ResultsCompared to the broad effects of VLA-4 blockade on encephalitogenic T cell migration over endothelial barriers, MCAM blockade impeded encephalitogenic T cell migration in murine models of MS that especially depend on CNS migration across the choroid plexus (CP). In transgenic mice lacking T cell α4-integrin expression (CD4::Itga4−/−), MCAM blockade delayed disease onset. Migration of MCAM-expressing T cells through the CP into the CNS was restricted, where laminin 411 (composed of α4, β1, γ1 chains), the proposed major ligand of MCAM, is detected in the endothelial basement membranes of murine CP tissue. This finding was translated to the human system; blockade of MCAM with a therapeutic antibody reduced in vitro transmigration of MCAM-expressing T cells across a human fibroblast-derived extracellular matrix layer and a brain-derived endothelial monolayer, both expressing laminin α4. Laminin α4 was further detected in situ in CP endothelial-basement membranes in MS patients’ brain tissue.ConclusionsOur findings suggest that MCAM-laminin 411 interactions facilitate trans-endothelial migration of MCAM-expressing T cells into the CNS, which seems to be highly relevant to migration via the CP and to potential future clinical applications in neuroinflammatory disorders.

Honokiol and Magnolol Inhibit CXCL10 and CXCL11 Production in IL-27-Stimulated Human Oral Epithelial Cells.

Honokiol and magnolol, which are lignans isolated from Magnolia quinquepeta, have some pharmacological effects. However, the anti-inflammatory effects of honokiol and magnolol on periodontal disease are still uncertain. The aim of this study was to examine the effect of honokiol and magnolol on CXC chemokine receptor 3 (CXCR3) ligands, which are related with Th1 cell migration, production in interleukin (IL)-27-stimulated human oral epithelial cells (TR146 cells). Honokiol and magnolol inhibited CXC chemokine ligand (CXCL)10 and CXCL11 production in IL-27-stimulated TR146 cells in a dose-dependent manner. Moreover, we revealed that honokiol and magnolol could suppress signal transducer and activator of transcription (STAT)3 and protein kinase B (Akt) phosphorylation in IL-27-stimulated TR146 cells though STAT1 phosphorylation was not suppressed by honokiol and magnolol treatment. Furthermore, STAT3 and Akt inhibitors could suppress CXCR3 ligand production in TR146 cells. In summary, honokiol and magnolol could reduce CXCR3 ligand production in oral epithelial cell by inhibiting STAT3 and Akt activation.

CCR2 mediates transendothelial migration of human pathogenic Th17 cells

Abstract Leukocyte extravasation is a multistep process characterized by rolling and arrest on the endothelium followed by transendothelial migration (TEM). Arrest and TEM by T cells typically requires the activities of chemokines and their receptors. Previously, we showed that CCR2 identifies highly differentiated, readily activated CD4+ memory T cells in human blood with diverse effector capabilities, and we showed that CCR6 is the signature chemokine receptor for Th17 cells. Here we describe studies of the migratory capabilities and effector profiles of CD4+ CCR6+ CCR2+ as compared with CD4+ CCR6+ CCR2− and CD4+ CCR6− CCR2− T cells from human blood. Using flow chamber assays with TNFa-activated human umbilical vein endothelial cells, we found that among the CCR6+ cells, only the CCR2+ subset was able to cross the endothelial monolayer efficiently. Using antibodies against the CCR6 ligand, CCL20, and a specific inhibitor of CCR2, we found that CCR6 was important for arrest and that CCR2 was critical for subsequent TEM. Using intracellular staining of cells activated ex vivo, we found that although IL-17-expressing cells were found within all CCR6+ subsets, the CCR6+CCR2+ cells were distinguished by their production of IFNg, GM-CSF, and TNFa, thereby demonstrating the cytokine profile of pathogenic Th17 cells as identified in mouse models of autoimmune disease. Taken together, our studies suggest that chemokine receptors on memory Th cells play non-redundant roles in the egress from blood, that providing T cells with CCR6 and CCR2 could enhance their trafficking into tissue, and that, on the other hand, blocking CCR2 alone could prevent the extravasation of pathogenic Th17 cells and ameliorate tissue damage in Th17-cell driven disease.

The RORγt-CCR6-CCL20 axis augments Th17 cells invasion into the synovia of rheumatoid arthritis patients

Objectives: To clarify the pathogenic role of transcription factor expression of CD4 + T helper (Th) cell subsets in the development of rheumatoid arthritis (RA).Methods: We collected CD4 + T cells from peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) by magnetic cell sorting. The proportion of Th cell subsets were classified from cell surface markers (CD45RA, CXCR5, CXCR3, CCR6) and the expression of their transcription factors (T-bet, GATA3, RORγt) were analyzed by flow cytometry before and at 24 weeks after anti-rheumatic treatment. Chemotaxis assays quantified migratory ability.Results: The expression of CCR6 and RORγt in Th17 cells from PBMC of RA patients was significantly higher than in healthy control volunteers and osteoarthritis patients. The proportion of Th17 cells in SFMCs of RA patients was significantly higher than that in PBMCs. Chemotaxis assays revealed that the migration index of Th17 cells towards CCL20 was remarkably enhanced in RA patients. The expression of CCR6 and RORγt in Th17 cells at 24 weeks post-therapeutic intervention was significantly decreased compared to before treatment.Conclusion: The high expression of RORγt might facilitate the migration of Th17 cells to inflamed joints via the enhanced expression of CCR6 and contribute to the pathology of RA.

Effectors of Th1 and Th17 cells act on astrocytes and augment their neuroinflammatory properties

BackgroundAutoreactive Th1 and Th17 cells are believed to mediate the pathology of multiple sclerosis in the central nervous system (CNS). Their interaction with microglia and astrocytes in the CNS is crucial for the regulation of the neuroinflammation. Previously, we have shown that only Th1 but not Th17 effectors activate microglia. However, it is not clear which cells are targets of Th17 effectors in the CNS.MethodsTo understand the effects driven by Th17 cells in the CNS, we induced experimental autoimmune encephalomyelitis in wild-type mice and CD4+ T cell-specific integrin α4-deficient mice where trafficking of Th1 cells into the CNS was affected. We compared microglial and astrocyte response in the brain and spinal cord of these mice. We further treated astrocytes with supernatants from highly pure Th1 and Th17 cultures and assessed the messenger RNA expression of neurotrophic factors, cytokines and chemokines, using real-time PCR. Data obtained was analyzed using the Kruskal-Wallis test.ResultsWe observed in α4-deficient mice weak microglial activation but comparable astrogliosis to that of wild-type mice in the regions of the brain populated with Th17 infiltrates, suggesting that Th17 cells target astrocytes and not microglia. In vitro, in response to supernatants from Th1 and Th17 cultures, astrocytes showed altered expression of neurotrophic factors, pro-inflammatory cytokines and chemokines. Furthermore, increased expression of chemokines in Th1- and Th17-treated astrocytes enhanced recruitment of microglia and transendothelial migration of Th17 cells in vitro.ConclusionOur results demonstrate the delicate interaction between T cell subsets and glial cells and how they communicate to mediate their effects. Effectors of Th1 act on both microglia and astrocytes whereas Th17 effectors preferentially target astrocytes to promote neuroinflammation.

A fully humanized IgG-like bispecific antibody for effective dual targeting of CXCR3 and CCR6.

Chemokines and their receptors are pivotal for the trafficking of leukocytes during immune responses, and host defense. However, immune cell migration also contributes to a wide variety of autoimmune and chronic inflammatory diseases. Compelling evidence suggests that both CXCR3 and CCR6 chemokine receptors play crucial roles in the migration of pathological Th1 and Th17 cells during the course of certain inflammatory diseases. The use of two or more receptors by pathogenic cells may explain why targeting of individual receptors has proven disappointing in the clinic. We therefore hypothesized that simultaneous targeting of both CXCR3 and CCR6 with a bispecific antibody (BsAb) might result in decreased chemotaxis and/or specific depletion of pro-inflammatory T cell subsets. In this study, we designed and characterized a fully humanized BsAb. We show that the BsAb binds to both chemokine receptors, as demonstrated by Flow Cytometry and Surface Plasmon Resonance analysis. Furthermore, we demonstrate that the BsAb effectively blocks cell chemotaxis and induces specific antibody-dependent cell-mediated cytotoxicity (ADCC) in vitro. Therefore, we propose that dual targeting of CXCR3 and CCR6 with a fully humanized BsAb may display a potent interventional approach for the treatment of inflammatory and autoimmune diseases.

The RNA-binding protein HuR contributes to neuroinflammation by promoting C-C chemokine receptor 6 (CCR6) expression on Th17 cells

In both multiple sclerosis and experimental autoimmune encephalomyelitis (EAE), the C-C chemokine receptor 6 (CCR6) is critical for pathogenic T helper 17 (Th17) cell migration to the central nervous system (CNS). Whereas many cytokines and their receptors are potently regulated via post-transcriptional mechanisms in response to various stimuli, how CCR6 expression is post-transcriptionally regulated in Th17 cells is unknown. Here, using RNA-binding protein HuR conditional knock-out (KO) and wild-type (WT) mice, we present evidence that HuR post-transcriptionally regulates CCR6 expression by binding to and stabilizing Ccr6 mRNA and by promoting CCR6 translation. We also found that HuR down-regulates several microRNA expressions, which could target the 3′-UTR of Ccr6 mRNA for decay. Accordingly, knock-out of HuR reduced CCR6 expression on Th17 cells and impaired their migration to CNS compared with the response of WT Th17 cells and thereby ameliorated EAE. Together, these findings highlight how HuR contributes to Th17 cell-mediated autoimmune neuroinflammation and support the notion that targeting HuR might be a potential therapeutic intervention for managing autoimmune disorders of the CNS.

IFN-γ promotes transendothelial migration of CD4+ T cells across the blood-brain barrier.

Transendothelial migration (TEM) of Th1 and Th17 cells across the blood-brain barrier (BBB) has a critical role in the development of experimental autoimmune encephalomyelitis (EAE). How cytokines produced by inflammatory Th1 and Th17 cells damage the endothelial BBB and promote transendothelial migration of immune cells into the central nervous system (CNS) during autoimmunity is not understood. We therefore investigated the effect of various cytokines on brain endothelial cells. Among the various cytokines tested, such as Th1 (IFN-γ, IL-1α, IL-1β, TNF-α, IL-12), Th2 (IL-3, IL-4, IL-6 and IL-13), Th17 (IL-17A, IL-17F, IL-21, IL-22, IL-23, GM-CSF) and Treg-specific cytokines (IL-10 and TGF-β), IFN-γ predominantly showed increased expression of ICAM-1, VCAM-1, MAdCAM-1, H2-Kb and I-Ab molecules on brain endothelial cells. Furthermore, IFN-γ induced transendothelial migration of CD4+ T cells from the apical (luminal side) to the basal side (abluminal side) of the endothelial monolayer to chemokine CCL21 in a STAT-1-dependent manner. IFN-γ also favored the transcellular route of TEM of CD4+ T cells. Multicolor immunofluorescence and confocal microscopic analysis showed that IFN-γ induced relocalization of ICAM-1, PECAM-1, ZO-1 and VE-cadherin in the endothelial cells, which affected the migration of CD4+ T cells. These findings reveal that the IFN-γ produced during inflammation could contribute towards disrupting the BBB and promoting TEM of CD4+ T cells. Our findings also indicate that strategies that interfere with the activation of CNS endothelial cells may help in controlling neuroinflammation and autoimmunity.

Upregulated KAT7 in synovial fibroblasts promotes Th17 cell differentiation and infiltration in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease involving multiple cellular participants, of which synovial fibroblasts (SFs) are tightly connected with the development and progression of RA. Here, we provide evidence confirming that KAT7, an H4-specific histone acetylase, is upregulated in SFs of RA patients, which is at least attributed to the stimulation by RA-associated proinflammatory cytokines, such as TNF-α, IL-1β or IFN-γ. In addition, KAT7 overexpression in cultured human fibroblast-like synoviocytes (HFLSs) induces IL-6 and TGF-β expression through an epigenetic mechanism, and in vitro T helper 17 (Th17) cell polarization cultured in these supernatants shows promoted cell differentiation. Moreover, KAT7 overexpression in HFLSs induces CCL20 expression via p44/42 MAPK pathway, whereby promoting Th17 cell migration. These two activities of KAT7 in RA SFs indicate its potential roles in accelerating RA pathology. Overall, these results demonstrate some connections between KAT7 upregulated in RA SFs and RA progression and present the inhibition of KAT7 activity as a novel therapeutic target for interfering RA disease.

Interleukin 17A Promotes Lymphocytes Adhesion and Induces CCL2 and CXCL1 Release from Brain Endothelial Cells.

The nature of the interaction between Th17 cells and the blood–brain barrier (BBB) is critical for the development of autoimmune inflammation in the central nervous system (CNS). Tumor necrosis factor alpha (TNF-α) or interleukin 17 (IL-17) stimulation is known to enhance the adherence of Th17 cells to the brain endothelium. The brain endothelial cells (bEnd.3) express Vascular cell adhesion molecule 1 (VCAM-1), the receptor responsible for inflammatory cell adhesion, which binds very late antigen 4 (VLA-4) on migrating effector lymphocytes at the early stage of brain inflammation. The present study examines the effect of the pro-inflammatory cytokines TNF-α and IL-17 on the adherence of Th17 cells to bEnd.3. The bEnd.3 cells were found to increase production of CCL2 and CXCL1 after stimulation by pro-inflammatory cytokines, while CCL2, CCL5, CCL20 and IL17 induced Th17 cell migration through a bEnd.3 monolayer. This observation may suggest potential therapeutic targets for the prevention of autoimmune neuroinflammation development in the CNS.

Partial role of CXCR3 in the migration of CD4 T cells into the lung of TB infected mice

Abstract Mycobacterium tuberculosis (Mtb) is the leading cause of death by infectious disease worldwide. In order to develop effective vaccination strategies for Mtb, it is critical to understand the properties of host-protective CD4 T cells. We have shown that various subsets of Mtb-specific Th1 cells display dramatically different lung migratory abilities. CXCR3+ Th1 cells migrate into the lung and control Mtb infection, while CX3CR1+ Th1 cells are retained in the lung-associated blood vasculature and do not suppress bacterial growth in vivo. However, little is know about the precise role of different chemokine receptors in the entry of Mtb-specific Th1 cells into the lung. Here we quantify the individual contributions of several chemokine receptors in the pulmonary migration of Th1 cells by performing in vivo migration experiments after adoptive transfer of WT and CCR KO Mtb-specific lung effector T cells into infection matched WT recipients. Firstly, we find that Th1 cells migration into the lung is pertussis toxin sensitive, indicating that G-protein coupled receptors are required. We find that while CXCR6 is highly expressed in Th1 cells capable of migrating into the lung, it has no role in their entry. Likewise, CCR2 had no role in Th1 cell migration into Mtb infected lungs. Interestingly, CXCR3−/− CD4 T cells displayed only a ~30% reduction compared to WT cells 16 hours after transfer. Although CXCR3 and CXCR6 are defining markers expressed on all lung-homing Mtb-specific Th1 cells, our results indicate that additional chemokine receptors are involved in their migration. Identification of new mechanisms governing the migration of Mtb-specific Th1 cells into the lung may give important insight into T cell dependent immunity to Mtb infection.

Th17 cells modulate the LN microenvironment through IL-17 dependent regulation of fibroblastic reticular cells

Abstract Integrins play a critical role in the function and migration of Th17 cells in CNS, and blockade of inflammatory T cell migration is used therapeutically in multiple sclerosis. Our previously published data demonstrated a critical role for αvβ3 in driving encephalitogenic Th17 cell migration in experimental autoimmune encephalomyelitis (EAE), in an IL-23R-dependent manner. Herein, we show that fibronectin, a ligand for integrin αvβ3, is significantly upregulated in the dLNs of EAE mice. Strikingly, the expression of fibronectin in dLN was significantly reduced in IL23R−/− mice following immunization. Fibronectin expression increased in dLNs during the progression of EAE with similar kinetics but delayed peak compared to IL-17. Since IL23R regulates IL-17 production, we analyzed LN from IL-17−/− and IL17Ra−/− mice immunized for EAE, and observed a similar defect in fibronectin expression in the absence of IL-17 signaling. CD45−gp38+CD31− fibroblastic reticular cells (FRCs) in the T cell zone are the major producers of fibronectin in the dLNs, and these stromal cells expand during EAE. Although IL-17RA−/− LN appeared similarly enlarged following immunization, indicating an inflammatory response, the number of FRCs was decreased in immunized IL17Ra−/− LN, corresponding to decreased fibronectin. Taken together, our data suggests that during priming of the immune response, and before migrating to their peripheral target tissue, Th17 cells modulate the local LN environment in which they are activated through production of IL-17 to promote FRCs expansion and induction of ECM. This could have long-term consequences in the host upon future infectious challenge, as well as influencing chronicity of Th17-mediated autoimmune disease.

Human Th17 Migration in Three-Dimensional Collagen Involves p38 MAPK.

T cell migration across extracellular matrix (ECM) is an important step of the adaptive immune response but is also involved in the development of inflammatory autoimmune diseases. Currently, the molecular mechanisms regulating the motility of effector T cells in ECM are not fully understood. Activation of p38 MAPK has been implicated in T cell activation and is critical to the development of immune and inflammatory responses. In this study, we examined the implication of p38 MAPK in regulating the migration of human Th17 cells through collagen. Using specific inhibitor and siRNA, we found that p38 is necessary for human Th17 migration in three-dimensional (3D) collagen and that 3D collagen increases p38 phosphorylation. We also provide evidence that the collagen receptor, discoidin domain receptor 1 (DDR1), which promotes Th17 migration in 3D collagen, is involved in p38 activation. Together, our findings suggest that targeting DDR1/p38 MAPK pathway could be beneficial for the treatment of Th17-mediated inflammatory diseases. J. Cell. Biochem. 118: 2819-2827, 2017. © 2017 Wiley Periodicals, Inc.

Differential Contribution of Adhesion Molecules to Th1 and Th2 Cell-Mediated Lung and Bowel Inflammation.

CD4+ T cells play a critical role in the development of allergic inflammation in several target organs. Various adhesion molecules are involved in the local recruitment of T cells and other inflammatory cells. We investigated the differential contribution of adhesion molecules to T helper 1 (Th1) and Th2 cell-mediated allergic lung and bowel inflammation by employing their neutralizing antibodies. BALB/c mice transferred with in vitro-differentiated antigen-specific Th1 and Th2 cells were intratracheally or intrarectally challenged with a relevant antigen. Infiltration of infused T cells occurred, along with the accumulation of neutrophils and eosinophils in the lungs of Th1 and Th2 cell-transferred recipients, respectively. Th1-mediated neutrophil and Th2-mediated eosinophil accumulation in the large intestine, which occurred after intrarectal challenge with the antigen, was indicated by the significant elevation of myeloperoxidase (MPO) and eosinophil peroxidase (EPO) activity. Blocking experiments with neutralizing antibodies indicated that intercellular cell adhesion molecule (ICAM)-1; vascular cell adhesion molecule (VCAM)-1; and αL, β2, and β7 integrins participate in the accumulation of Th2 cells and eosinophils in the lungs. In contrast, the migration of Th1 cells and neutrophils was diminished by blockage of αL/β2-integrin and ICAM-1, respectively. Mucosal addressin cell adhesion molecule (MadCAM)-1, vascular cell adhesion molecule (VCAM)-1, α4, β1, and β7 contributed to Th1-mediated neutrophilic inflammation in the bowel, though only MadCAM-1, α4, αL, and β2 were involved in Th2-mediated eosinophilic inflammation. We conclude that distinct sets of adhesion molecules are involved in Th1- and Th2-mediated allergic lung and bowel inflammation.

398 - Caveolin-1 is Critical for Lymphocyte Trafficking into Central Nervous System during Experimental Autoimmune Encephalomyelitis

In the present study, we tested the hypothesis that caveolin-1 plays a critical role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a laboratory murine model of Multiple Sclerosis (MS). After active EAE induction, the increased caveolin-1 in serum and CNS tissues was associated with disease incidence and severity in immunized wild-type (WT) mice. After immunization, Cav-1knockout (KO) mice showed remarkable disease resistance with alleviated incidences and clinical symptoms. Cav-1 KO mice had diminished infiltration of encephalitogenic T cells into CNS parenchyma with compromised expressions of adhesion molecules ICAM-1 and VCAM-1 in the white matter of CNS tissues. Consistently, in vitro knockdown of caveolin-1 impaired the up-regulation of ICAM-1 in endothelial cells, and ameliorated trans-endothelial migration of pathogenic TH1 and TH17 cells. Therefore, caveolin-1 serves as an active modulator of lymphocyte trafficking into CNS and could be a therapeutic target for multiple sclerosis.

Th2 Cells and Th17 Cells in the Development of Endometriosis – Possible Roles of Interleukin-4 and Interleukin-17A

Endometriosis is recognized as an inflammatory disease in which inflammatory cytokines, such as interleukin (IL)-1β and TNFα, play important roles. Immunological factors are also suggested to be involved in the pathogenesis of endometriosis. This review provides comprehensive knowledge about helper T cell (Th cell) and its specific cytokines in endometriosis. A series of our studies demonstrated the presence of Th2 cells and Th17 cells in endometriotic tissues and revealed multiple effects of IL-4 and IL-17A, cytokines secreted from respective Th cells. IL-1β induces secretion of thymic stromal lymphopoietin (TSLP), a regulator for differentiation of inflammatory Th2 cells, in endometriotic stromal cells (ESCs). IL-4 stimulates proliferation of ESCs and production of 3β-hydroxysteroid dehydrogenase Type 2, an enzyme in an estrogen production pathway, in ESCs. IL-17A stimulates IL-8 and Gro-α secretion from ESCs and proliferation of ESCs. IL-17A-induced Gro-α promotes neutrophil migration, which may contribute to the presence of neutrophils in endometriotic tissues. IL-17A also increases secretion of CCL20, a chemokine for Th17 cells, from ESCs, which seems to induce migration of Th17 cells to the endometriotic tissues and enhance the effects of IL-17A further. TNFα in combination with IL-17A synergistically enhances secretion of IL-8 and CCL-20, suggesting cooperation of inflammation and Th17 immune response. These findings suggest that IL-4 and IL-17A promote the development of endometriosis through induction of cell proliferation, inflammation, and estrogen production. It is thus also suggested that IL-4 and IL-17A would be a target of treatment of the disease.

Discoidin domain receptor 1 promotes Th17 cell migration by activating the RhoA/ROCK/MAPK/ERK signaling pathway.

Effector T cell migration through the tissue extracellular matrix (ECM) is an important step of the adaptive immune response and in the development of inflammatory diseases. However, the mechanisms involved in this process are still poorly understood. In this study, we addressed the role of a collagen receptor, the discoidin domain receptor 1 (DDR1), in the migration of Th17 cells. We showed that the vast majority of human Th17 cells express DDR1 and that silencing DDR1 or using the blocking recombinant receptor DDR1:Fc significantly reduced their motility and invasion in three-dimensional (3D) collagen. DDR1 promoted Th17 migration by activating RhoA/ROCK and MAPK/ERK signaling pathways. Interestingly, the RhoA/ROCK signaling module was required for MAPK/ERK activation. Finally, we showed that DDR1 is important for the recruitment of Th17 cells into the mouse dorsal air pouch containing the chemoattractant CCL20. Collectively, our results indicate that DDR1, via the activation of RhoA/ROCK/MAPK/ERK signaling axis, is a key pathway of effector T cell migration through collagen of perivascular tissues. As such, DDR1 can contribute to the development of Th17-dependent inflammatory diseases.

Melatonin Inhibits CXCL10 and MMP-1 Production in IL-1β-Stimulated Human Periodontal Ligament Cells.

Melatonin is a hormone that is mainly secreted by the pineal gland and exhibits a wide spectrum of activities, including antioxidant functions. Melatonin has been detected in gingival crevicular fluid. However, the role of melatonin in periodontal tissue is still uncertain. The aim of this study was to examine the effects of melatonin on inflammatory mediator expression in human periodontal ligament cells (HPDLC). Interleukin (IL)-1β induced CXC chemokine ligand (CXCL)10, matrix metalloproteinase (MMP)-1, and tissue inhibitors of metalloproteinase (TIMP)-1 production in HPDLC. Melatonin decreased CXCL10 and MMP-1 production and increased TIMP-1 production in IL-1β-stimulated HPDLC. Western blot analysis showed that melatonin inhibited p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK) phosphorylation, and IkB-α degradation and phosphorylation in IL-1β-stimulated HPDLC. These results suggest that melatonin might inhibit Th1 cell migration by reducing CXCL10 production. Moreover, melatonin might inhibit soft tissue destruction by decreasing MMP-1 production in periodontal lesions.

T-bet promotes the accumulation of encephalitogenic Th17 cells in the CNS

T-bet enhances the encephalitogenicity of myelin-reactive CD4+ T cells, however its mechanism of action is unknown. In this study we show that T-bet confers a competitive advantage for the accumulation of IL-23 conditioned Th17 effector cells in the central nervous system (CNS). Impaired migration of T-bet deficient Th17 cells to the CNS is associated with altered expression of adhesion molecules and chemokine receptors on their cell surface. Our data suggest that therapeutic targeting of T-bet in individuals with Th17-mediated autoimmune demyelinating disease may inhibit inflammatory infiltration of the CNS and, hence, clinical exacerbations.