Migration Of Th17 Cells Research Articles

Recruitment of CCR6-Expressing Th17 Cells by CCL 20 Secreted from IL-1β-, TNF-α-, and IL-17A-Stimulated Endometriotic Stromal Cells

In a novel paradigm of T cell differentiation, type 17 T helper (Th17) cells may play a significant role in endometriosis, a chronic inflammatory disease. However, the mechanism regulating the accumulation of Th17 cells in endometriotic tissues remains unknown. We hypothesized that Th17 cells migrate to endometriotic tissues through an interaction of the chemokine CC chemokine ligand (CCL)20 and its receptor CCR6. Using endometriotic tissues from women with endometriosis, we demonstrated, by flow cytometry, that Th17 cells in endometriotic tissues express CC chemokine receptor (CCR)6. Immunohistochemistry also revealed that CCL20 was expressed in the epithelial cells and stromal cells beneath the epithelium of endometriotic tissues. CCR6+ cells were small and round and scattered in the stroma in which abundant CCL20+ cells were detected. CCL20 caused selective migration of Th17 cells in the peripheral blood in a migration assay. IL-1β, TNF-α, and IL-17A increased the secretion of CCL20 in cultured endometriotic stromal cells. Inhibitors of p38- and p42/44-MAPKs, and stress-activated protein kinase/c-Jun kinase suppressed the secretion of CCL20 increased by IL-1β, TNF-α, and IL-17A. This suggests that the CCL20/CCR6 system is involved in the migration of Th17 cells to endometriotic tissues and that proinflammatory cytokines contribute to the development of endometriosis via up-regulation of CCL20 secretion from endometriotic stromal cells.

1,25-Dihydroxyvitamin D3 Inhibits the Differentiation and Migration of TH17 Cells to Protect against Experimental Autoimmune Encephalomyelitis

BackgroundVitamin D3, the most physiologically relevant form of vitamin D, is an essential organic compound that has been shown to have a crucial effect on the immune responses. Vitamin D3 ameliorates the onset of the experimental autoimmune encephalomyelitis (EAE); however, the direct effect of vitamin D3 on T cells is largely unknown.Methodology/Principal FindingsIn an in vitro system using cells from mice, the active form of vitamin D3 (1,25-dihydroxyvitamin D3) suppresses both interleukin (IL)-17-producing T cells (TH17) and regulatory T cells (Treg) differentiation via a vitamin D receptor signal. The ability of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) to reduce the amount of IL-2 regulates the generation of Treg cells, but not TH17 cells. Under TH17-polarizing conditions, 1,25(OH)2D3 helps to increase the numbers of IL-10-producing T cells, but 1,25(OH)2D3's negative regulation of TH17 development is still defined in the IL-10−/− T cells. Although the STAT1 signal reciprocally affects the secretion of IL-10 and IL-17, 1,25(OH)2D3 inhibits IL-17 production in STAT1−/− T cells. Most interestingly, 1,25(OH)2D3 negatively regulates CCR6 expression which might be essential for TH17 cells to enter the central nervous system and initiate EAE.Conclusions/SignificanceOur present results in an experimental murine model suggest that 1,25(OH)2D3 can directly regulate T cell differentiation and could be applied in preventive and therapeutic strategies for TH17-mediated autoimmune diseases.

Role of Th17 cells in human autoimmune arthritis

To delineate the role of Th17 cells in the pathogenesis of autoimmune arthritides. Th17 cells were analyzed in well-defined homogeneous cohorts of patients with the prototypical autoimmune arthritides rheumatoid arthritis (RA) and psoriatic arthritis (PsA), grouped according to patients who had very early active RA (n = 36; mean disease duration 2.8 months, Disease Activity Score in 28 joints 5.0) and those who had very early active PsA (n = 20; mean disease duration 2.3 months), none of whom had received treatment with glucocorticoids or disease-modifying antirheumatic drugs, as well as patients with established RA (n = 21; mean disease duration 68 months) who were considered either responders or nonresponders to therapy. Groups of healthy individuals and patients with osteoarthritis (a noninflammatory arthritis) were used as control cohorts. Expression of T lineage-specific transcription factors (RORC, T-bet, GATA-3, and FoxP3) and the response of CD4 T cells to Th17 cell-inducing conditions were analyzed in vitro. The frequencies of Th17 cells and levels of interleukin-17 strongly correlated with systemic disease activity at both the onset and the progression of RA or PsA. The values were reduced to control levels in patients with treatment-controlled disease activity. Th17 cells were enriched in the joints, and increased frequencies of synovial Th17 cells expressed CCR4 and CCR6, indicative of selective migration of Th17 cells to the joints. The intrinsically elevated expression of RORC, accompanied by biased Th17 cell development, and the resistance of Th17 cells to a natural cytokine antagonist in patients with RA and patients with PsA were suggestive of the underlying molecular mechanisms of uncontrolled Th17 activity in these patients. Th17 cells play an important role in inflammation in human autoimmune arthritides, both at the onset and in established disease.

The Differential Role of L-Selectin and ICAM-1 in Th1-Type and Th2-Type Contact Hypersensitivity

Sensitization and challenge using DNFB induce contact hypersensitivity (CHS) with predominant type 1 helper (Th1) cell infiltration, whereas those using FITC generate CHS with Th2 cell infiltration. CHS results from inflammatory cell infiltration, a process that is highly regulated by the expression of multiple adhesion molecules. We attempted to determine the role of L-selectin and ICAM-1 in Th1- and Th2-type CHS induced by DNFB or FITC in mice lacking either L-selectin, ICAM-1, or both. Th1-type CHS induced by DNFB was inhibited by L-selectin and/or ICAM-1 deficiency, which was associated with reduced IFN-gamma expression. Similarly, Th2-type CHS induced by FITC was inhibited by L-selectin deficiency. However, Th2-type CHS was increased by ICAM-1 deficiency and accompanied by increased Th2 cytokine expression. Infiltration of in vitro-generated Th1 cells into the FITC-challenged skin decreased in ICAM-1-deficient mice, whereas in vitro-generated Th2 cell infiltration increased, suggesting that ICAM-1 mediates Th1 cell migration and that in the absence of ICAM-1, Th1 cell recruitment decreased, whereas relative Th2 cell migration increased. These results suggest that ICAM-1 mediates Th1 cell recruitment irrespective of DNFB or FITC and that L-selectin recruits Th1 cells in Th1-type CHS, whereas it recruits Th2 cells in Th2-type CHS.

Retinoic Acid Determines the Precise Tissue Tropism of Inflammatory Th17 Cells in the Intestine

Th17 cells are major effector T cells in the intestine, but the regulation of their tissue tropism within the gut is poorly understood. We investigated the roles of vitamin A and retinoic acid in generation of inflammatory Th17 cells with distinct tissue tropisms within the intestine. We found that Th17 cells with distinct tissue tropisms and pathogenic activities are generated depending on the available concentration of retinoic acid (RA). In contrast to the widespread perception that RA would suppress the generation of Th17 cells, we provide evidence that RA is actually required for generation of Th17 cells with specific tissue tropisms within the gut. Th17 cells induced at suboptimal serum concentrations of RA migrated and induced moderate inflammation mainly in the large intestine, whereas the Th17 cells induced with optimal levels of exogenous RA (approximately 10 nM) migrated to the small intestine and induced more severe inflammation. The Th17 cells, induced in the presence or absence of RA, differentially expressed the trafficking receptors CCR9 and alpha4beta7. CCR9 is required for Th17 cell migration to the small intestine, whereas alpha4beta7 is required for the migration of Th17 cells throughout the whole intestine. Our results identified RA as a major signal that regulates the generation of gut Th17 cells with distinct capacities in migration and inflammatory activities. The results indicate also that specific gut tropism of Th17 cells is determined by the combination of trafficking receptors regulated by the RA signal.

CRTH2 mediates the activation of human Th2 cells in response to PGD2 released from IgE/anti‐IgE treated nasal polyp tissue

Mast cells release mediators upon stimulation that contribute to the pathogenesis of chronic airway disease, including the recruitment and activation of Th2 lymphocytes. The objective was to determine the involvement of prostaglandin D(2) (PGD(2)) and its receptors in the chemotaxis of Th2 cells, using nasal polyp tissue. Tissue explants from ten patients with nasal polyposis were incubated with RPMI alone or RPMI containing IgE/anti-IgE for 30 min. Some samples were treated with diclofenac to inhibit the production of PGD(2). Supernatants were assayed for PGD(2) content and for their ability to promote human Th2 cell chemotaxis in the presence and absence of a CRTH2 antagonist. Transcript levels of D protanoid receptor type 1 (DP(1)), chemoattractant receptor-homologous receptor expressed on Th2 cells (CRTH2) and PGD(2) synthase were analysed by real time PCR. Increased release of PGD(2) by nasal polyp tissue treated with IgE/anti-IgE was significantly inhibited by preincubation of the tissue with diclofenac. Transcript levels of PGD(2) synthase, DP(1) and CRTH2 receptors increased after stimulation with IgE/anti-IgE. Supernatants from IgE/anti-IgE-stimulated nasal polyp tissue caused significantly increased chemotaxis of Th2 cells. The levels of PGD(2) produced and the degree of Th2 cell chemotaxis were highly correlated. Diclofenac inhibited the production of Th2 cell chemotactic activity, and the chemotactic effect of the supernatant on Th2 cells was inhibited by the CRTH2 antagonist ramatroban. These data suggest that in immunologically activated nasal polyp tissue, PGD(2) produced by mast cells promotes the migration of Th2 cells through a CRTH2 dependent mechanism.

CD69 Controls the Pathogenesis of Allergic Airway Inflammation

Airway inflammation and airway hyperresponsiveness are central issues in the pathogenesis of asthma. CD69 is a membrane molecule transiently expressed on activated lymphocytes, and its selective expression in inflammatory infiltrates suggests that it plays a role in the pathogenesis of inflammatory diseases. In CD69-deficient mice, OVA-induced eosinophilic airway inflammation, mucus hyperproduction, and airway hyperresponsiveness were attenuated. Cell transfer of Ag-primed wild-type but not CD69-deficient CD4 T cells restored the induction of allergic inflammation in CD69-deficient mice, indicating a critical role of CD69 expressed on CD4 T cells. Th2 responses induced by CD69-deficient CD4 T cells in the lung were attenuated, and the migration of CD4 T cells into the asthmatic lung was severely compromised. The expression of VCAM-1 was also substantially altered, suggesting the involvement of VCAM-1 in the CD69-dependent migration of Th2 cells into the asthmatic lung. Interestingly, the administration of anti-CD69 Ab inhibited the induction of the OVA-induced airway inflammation and hyperresponsiveness. This inhibitory effect induced by the CD69 mAb was observed even after the airway challenge with OVA. These results indicate that CD69 plays a crucial role in the pathogenesis of allergen-induced eosinophilic airway inflammation and hyperresponsiveness and that CD69 could be a possible therapeutic target for asthmatic patients.

Exacerbation of Facial Motoneuron Loss after Facial Nerve Axotomy in CCR3-Deficient Mice

We have previously demonstrated a neuroprotective mechanism of FMN (facial motoneuron) survival after facial nerve axotomy that is dependent on CD4+ Th2 cell interaction with peripheral antigen-presenting cells, as well as CNS (central nervous system)-resident microglia. PACAP (pituitary adenylate cyclase-activating polypeptide) is expressed by injured FMN and increases Th2-associated chemokine expression in cultured murine microglia. Collectively, these results suggest a model involving CD4+ Th2 cell migration to the facial motor nucleus after injury via microglial expression of Th2-associated chemokines. However, to respond to Th2-associated chemokines, Th2 cells must express the appropriate Th2-associated chemokine receptors. In the present study, we tested the hypothesis that Th2-associated chemokine receptors increase in the facial motor nucleus after facial nerve axotomy at timepoints consistent with significant T-cell infiltration. Microarray analysis of Th2-associated chemokine receptors was followed up with real-time PCR for CCR3, which indicated that facial nerve injury increases CCR3 mRNA levels in mouse facial motor nucleus. Unexpectedly, quantitative- and co-immunofluorescence revealed increased CCR3 expression localizing to FMN in the facial motor nucleus after facial nerve axotomy. Compared with WT (wild-type), a significant decrease in FMN survival 4 weeks after axotomy was observed in CCR3−/− mice. Additionally, compared with WT, a significant decrease in FMN survival 4 weeks after axotomy was observed in Rag2−/− (recombination activating gene-2-deficient) mice adoptively transferred CD4+ T-cells isolated from CCR3−/− mice, but not in CCR3−/− mice adoptively transferred CD4+ T-cells derived from WT mice. These results provide a basis for further investigation into the co-operation between CD4+ T-cell- and CCR3-mediated neuroprotection after FMN injury.

Signal transducer and activator of transcription 1 in T cells plays an indispensable role in immunity to Leishmania major by mediating Th1 cell homing to the site of infection

The signal transducer and activator of transcription 1 (STAT1) signaling pathway mediates the biological functions of IFN-gamma. We have previously shown that the STAT1 pathway is indispensable for host resistance against Leishmania major infection. In this study, we examined the role of STAT1 in lymphocytes and specifically CD4(+) and CD8(+) T cells in mediating immunity against L. major by transferring T cells from wild-type (WT) and STAT1(-/-) C57BL/6 mice into Rag2(-/-) C57BL/6 mice. Rag2(-/-) mice reconstituted with unfractionated STAT1(-/-) splenocytes (B cells and T cells) failed to mount an efficient Th1 response after L. major infection, produced more IL-4, and developed large lesions full of parasites. In contrast, Rag2(-/-) mice reconstituted with WT (STAT1(+/+)) splenocytes mounted a Th1 response and developed self-resolving lesions. Studies using Rag2(-/-) recipients that received a combination of purified CD4(+) and CD8(+) T cells from WT or STAT1(-/-) mice revealed that STAT1 deficiency in CD4(+) T cells, but not in CD8(+) T cells, leads to development of chronic, nonhealing lesions and systemic dissemination of parasites into the spleen after L. major infection. Further studies using Rag2(-/-) recipients of WT Thy1.1(+) and STAT1(-/-) Thy1.2(+) T cells showed that STAT1 in CD4(+) T cells was not required for Th1 differentiation during L. major infection. However, it was critical for up-regulation of CXCR3 on CD4(+) T cells and their migration to the regional lymph node and the cutaneous site of infection. Together, these studies indicate that the STAT1 pathway in CD4(+) T cells plays a critical role in immunity against L. major by controlling the migration of Th1 cells to the site of infection rather than their generation. Further, they reveal an essential role for CD4(+) T cell STAT1 in preventing systemic dissemination of L. major infection.

Migration and Function of Th17 Cells

T cells play central roles in regulation of the immune system in mammals. T cell receptor alphabeta T cells that can produce the cytokine IL-17 are called Th17 cells and form a lineage of effector T cells that are distinct from Th1, Th2 and FoxP3(+) T cells. The primary function of Th17 cells is to fight infection by bacterial and fungal pathogens. Autoreactive Th17 cells are implicated in mediating inflammation in the central nerves system, joints and other tissues. Th17 cells express a number of chemokine receptors including a secondary lymphoid tissue homing receptor (CCR7), the B follicle homing receptor (CXCR5), and non-lymphoid tissue homing receptors (CCR4, CCR5, and CXCR6). While these receptors are heterogeneously expressed by Th17 cells and have the potential to guide the migration of Th17 cell subsets into various tissues, CCR6 is uniformly expressed by most Th17 cells regardless of their tissue tropism. CCR6 plays an important role in migration of Th17 cells to inflamed tissues. Another function of CCR6 is to localize Th17 cells close to CCL20 expressing cells in the intestine, which would be important for the homeostasis of Th17 cells. Thus, chemokine receptors appear to play complex roles in the biology of Th17 cells.

In this issue

AbstractCover imageThe cover image depicts immunofluorescence histology of OT‐II cells within the popliteal draining lymph nodes. The image was taken from the article by Serre et al. (pp.1573–1586), in which the authors assess the complexity of Th2 responses in vivo. The authors show that early central‐memory‐like cells induced by immunization re‐enter the cell cycle and migrate to B‐cell follicles, where the induction and survival of memory cells are independent of the starting frequency of antigen‐specific CD4+ T cells. magnified imageMicro‐RNA and the control of human natural Treg functionpp. 1608–1619A micro‐RNA signature for human Treg had not been described before. In this issue, Rouas et al. show, using T cells purified from unifected cord blood mononuclear cells, a novel signature for the CD4+CD25+ population. This is composed of five micro‐RNA (miR‐21, miR‐31, miR‐21, miR‐125a, miR‐181c and miR‐374). Among those, the authors show that miR‐21 and miR‐31 play a role in the control of FOXP3 expression. While the three other micro‐RNA did not influence FOXP3 expression, it remains to be determined if they are involved in regulating other genes critical for Treg function. A comprehensive understanding of the control of natural Treg function, as well as of induced Treg, could potentially lead to clinical interventions for various immune‐related diseases. magnified imageHow CD11c+CD8+ Treg go about suppressing CD4+ T cellspp. 1552–1563CD11c expression on CD8+ T cells defines a novel subset of Treg. These CD11c+ CD8+ T cells have been shown to possess therapeutic activitiy in arthritis; what is less known, is how these cells go about their business of suppression. In this issue Vinay et al. demonstrate that in vivo anti‐4‐1BB mAb expand a novel immunoregulatory CD11c+CD8+ T‐cell subset from CD11c−CD8+ T‐cell precursors in an Ag‐specific manner. Increased IFN‐γ as a result of anti‐4‐1BB treatment, upregulates IDO in DC, which in turn suppresses CD4+ T cells. Further supporting this regulatory loop is the observation that mice deficient in GCN2, a transcription factor downstream of IDO, do not exhibit inhibited CD4+ T cell response when treated with anti‐4‐1BB. Thus, we now have a better understanding of how CD11c+CD8+ Treg work. magnified imageThe when and where of CTLA‐4 function on Tregpp. 1544–1551Despite constitutive expression of CTLA‐4 by Treg, its role in Treg suppression remains elusive. CTLA‐4‐deficient Treg do retain regulatory function in a number of settings suggesting that either CTLA‐4 is not essential or that such Treg develop compensatory suppressive mechanisms. In vivo measures of Treg activity often rely on the transfer of non‐regulatory CD4+CD25− T cells with or without CD4+CD25+ Treg to lymphopenic hosts. In these systems, Treg can modulate T‐cell activity during homeostatic expansion as well as regulate T‐cell effector function and likely control these two stages using distinct mechanisms. In this issue, Sojka et al. identify a non‐redundant role for CTLA‐4 in Treg suppression of lymphopenia‐induced homeostatic expansion. In the absence of CTLA‐4, Treg were unable to limit early CD4+ T‐cell expansion and unchecked colitis ensued. Understanding when and where Treg use specific immunosuppressive tools is key to our ability to manipulate their activity. magnified imageγδ T cells set the stage for autoimmune demyelinationpp. 1516–1526EAE is a T‐cell‐mediated autoimmune disease that shares many features of the human disease multiple sclerosis. γδ T cells contribute to the pathogenesis of EAE; however the mechanisms behind this contribution are still unclear. In this issue, Wohler et al. track bioluminescent γδ T cells during EAE development and show these cells initially localize at the sites of immunization. γδ T cells then rapidly infiltrate the CNS prior to clinical disease onset, peaking in number during acute disease and then rapidly recede at the peak phase of disease. γδ T cells appear to be activated at the site of antigen exposure and then prime the CNS for disease development, in part, through the production of IFN‐γ and TNF‐α. The authors show γδ T cells to be critical in setting the stage for the development of EAE and thus suggesting a potential therapeutic target in demyelinating disease. magnified imageCCR6 in EAE: Help or hindrance?pp. 1671–1681Continuing along the EAE theme, chemokines are also critically important for disease development. The CCR6 chemokine receptor is expressed by certain tissue‐homing Treg and Th17 cells, which show functional dichotomy in inflammatory processes. By mediating Th17 cell migration to target tissues, CCR6 drives CNS inflammation. In this issue, Villares et al. demonstrate that CCR6 are necessary for CD4+ Treg to downregulate the inflammatory process in the CNS and reduce EAE‐associated neurological symptoms. While CCR6 deficiency leads to delayed onset of clinical symptoms, it is nevertheless accompanied by more persistent neurological damage. This dichotomy in CCR6 function strongly suggests that more needs to be done before considering CCR6 as a therapeutic target in human CNS disease. magnified image

CD152 (CTLA-4) determines CD4 T cell migration in vitro and in vivo.

BackgroundMigration of antigen-experienced T cells to secondary lymphoid organs and the site of antigenic-challenge is a mandatory prerequisite for the precise functioning of adaptive immune responses. The surface molecule CD152 (CTLA-4) is mostly considered as a negative regulator of T cell activation during immune responses. It is currently unknown whether CD152 can also influence chemokine-driven T cell migration.Methodology/Principal FindingsWe analyzed the consequences of CD152 signaling on Th cell migration using chemotaxis assays in vitro and radioactive cell tracking in vivo. We show here that the genetic and serological inactivation of CD152 in Th1 cells reduced migration towards CCL4, CXCL12 and CCL19, but not CXCL9, in a G-protein dependent manner. In addition, retroviral transduction of CD152 cDNA into CD152 negative cells restored Th1 cell migration. Crosslinking of CD152 together with CD3 and CD28 stimulation on activated Th1 cells increased expression of the chemokine receptors CCR5 and CCR7, which in turn enhanced cell migration. Using sensitive liposome technology, we show that mature dendritic cells but not activated B cells were potent at inducing surface CD152 expression and the CD152-mediated migration-enhancing signals. Importantly, migration of CD152 positive Th1 lymphocytes in in vivo experiments increased more than 200% as compared to CD152 negative counterparts showing that indeed CD152 orchestrates specific migration of selected Th1 cells to sites of inflammation and antigenic challenge in vivo.Conclusions/SignificanceWe show here, that CD152 signaling does not just silence cells, but selects individual ones for migration. This novel activity of CD152 adds to the already significant role of CD152 in controlling peripheral immune responses by allowing T cells to localize correctly during infection. It also suggests that interference with CD152 signaling provides a tool for altering the cellular composition at sites of inflammation and antigenic challenge.

Serum amyloid A protein stimulates CCL20 production in rheumatoid synoviocytes

Although serum amyloid A (SAA) has been used as a marker of inflammation, its role in leucocyte recruitment and angiogenesis has not been well established in RA. CCL20 is a chemokine involved in the migration of CCR6-expressing Th17 cells. To study the contribution of SAA to the recruitment of Th17 cells, we investigated the effects of SAA on CCL20 production by RA synoviotytes. Synoviocytes isolated from RA patients were stimulated with recombinant SAA and cellular supernatants were analysed by CCL20-specific ELISA. CCL-20 mRNA expression was analysed by RT-PCR. SAA is a most potent inducer of CCL20 secretion in RA synoviocytes compared with other inflammatory cytokines (IL-1beta, TNF-alpha and IL-17A). SAA stimulation induced CCL20 mRNA expression in RA synoviocytes, which was not affected by polymyxin B pre-treatment. SAA-induced CCL20 production was down-regulated by NF-kappaB inhibition and partially by c-jun N-terminal kinase (JNK) inhibition. SAA-induced CCL20 production was also suppressed by dexamethasone or FK506. These findings suggest that SAA may be implicated in the recruitment of lymphocytes, including CCR6-expressing Th17 cells, in RA synovium by up-regulating CCL20 production in synoviocytes.

CCR6 regulates the migration and effector function of Th17 cells in the gut (96.2)

Abstract T helper cells that produce IL-17 (Th17 cells) play important roles in regulation of immunity to bacteria and fungi and can cause organ-specific inflammation. The intestine is a tissue where Th17 cells are highly enriched, but migration and trafficking receptors of Th17 cells to the intestine have been unclear. It has been established that CCR6 is the signature chemokine receptor for Th17 cells but the role of this trafficking receptor in Th17 cell trafficking to the intestine has not been determined. We report here that Th17 cells preferentially migrate to the intestine and associated-lymphoid tissues, and CCR6 is the homing receptor important for Th17 cell migration to certain tissue microenvironments of the intestine where its ligand CCL20 is highly expressed. We determined the function of CCR6 of Th17 cells by comparing the migration and effector function of Th17 cells derived from wild type and CCR6-deficient mice. CCR6-deficient Th17 cells were defective in migration to Peyer's patches and small intestine but their migration to the large intestine was normal. Surprisingly, administration of CCR6-deficient Th17 cells into severe combined immunodeficiency (SCID) mice led to excessive intestinal inflammation. Following the administration of Th17 cells, we found that Th17 cells fail to propagate in the gut in the absence of CCR6 and transdifferentiate into inflammatory Th1 cells. In addition, CCR6 deficiency led to aberrantly wide-spread effector T cells in the inflamed intestine of the SCID mice. Finally, we found that the expression of CCR6 by Th17 cells is induced by TGF-β1 but suppressed by IL-2 in vitro and in vivo. Taken together, we conclude that CCR6 is a key trafficking receptor that regulates the migration and effector function of Th17 cells in the intestine.

Selective deficiency of STAT1 in CD4+ T cells enhances susceptibility to Leishmania major infection not by preventing induction of Th1 response, but by impairing CD4+ T cell homing (44.26)

Abstract We previously reported that STAT1 signaling is indispensable for host resistance against Leishmania major. In this study, we examined the role of STAT1 in lymphocytes as well as CD4+ versus CD8+ T cells in mediating immunity to L. major by performing adoptive transfers of T cells from WT and STAT1-/- C57BL/6 mice to Rag2-/- C57BL/6 mice. Rag2-/- mice reconstituted with STAT1-/- splenocytes (B cells and T cells) failed to mount an efficient Th1 response following L. major infection, produced more IL-4 and developed large lesions full of parasites. In contrast, Rag2-/- mice reconstituted with WT (STAT1+/+) splenocytes mounted a Th1 response and developed self-resolving lesions. Studies using Rag2-/- recipients that received a combination of purified CD4+ and CD8+ T cells from WT or STAT1-/- mice revealed that STAT1 in CD4+, but not CD8+ T cells was indispensable for immunity against L. major. Further studies using Thy1.1+ congenic recipients receiving WT or STAT1 Thy1.2+ CD4+ cells showed that STAT1 in CD4+ T cells was not required for Th1 differentiation and IFN-γ production during L. major infection, but was critical for migration to regional lymph nodes and the cutaneous site of infection. Together these studies indicate that STAT1 signaling in CD4+ T cells plays a critical role in immunity against L. major by controlling migration of Th1 cells to the site of infection rather than their generation. Research Support: NIH

The roles of CCR6 in migration of Th17 cells and regulation of effector T-cell balance in the gut

Migration and trafficking receptors of Th17 cells to mucosal tissues have been unclear. We report that Th17 cells preferentially migrate to the intestine and associated lymphoid tissues, and CCR6 is the homing receptor important for Th17 cell migration to certain tissue microenvironments of the intestine such as Peyer's patches and other sites where its ligand CCL20 is expressed. We found the cytokine transforming growth factor-β1 is required for CCR6 expression whereas IL-2 suppresses it. CCR6-deficient Th17 cells aberrantly migrate to different compartments of the intestine. Surprisingly, administration of CCR6-deficient Th17 cells into severe combined immunodeficiency (SCID) mice led to excessive intestinal inflammation with increased Th1 but decreased Th17 cells and FoxP3+ T cells. In addition, CCR6 deficiency led to aberrantly widespread effector T cells in the inflamed intestine of the SCID mice. We conclude that CCR6 regulates Th17 cell migration to the gut and effector T-cell balance/distribution in inflamed intestine.

Roxithromycin inhibits chemokine-induced chemotaxis of Th1 and Th2 cells but regulatory T cells

Roxithromycin (RXM), a 14-member macrolide antibiotic, has a variety of bioregulatory functions such as anti-inflammatory effects, anti-oxidant effects, and modulation of immune responses. In this study, we analyzed the effect of RXM on chemokine-induced chemotaxis of Th1, Th2, and regulatory T (Treg) cells established from three normal human peripheral blood lymphocytes by the reported methods. Incubation with 10 microM RXM for 18 h did not alter the expression profile of CXCR3 on Th1 cells and CCR4 on Th2 and Treg cells. However, upon RXM preincubation, the migration of Th1 cells to IP-10 and Th2 cells to TARC was partially suppressed, although RXM did not influence Treg cell migration. Erythromycin and clarithromycin at the same concentration did not exert such effects. F-actin polymerization and Ca(++) influx induced by IP-10 and TARC in Th1 and Th2 cells, respectively, was down-regulated by RXM pretreatment. These results imply that RXM exhibits bioregulatory function by influencing chemotaxis of Th1 and Th2 cells while leaving Treg cell migration unaffected.

CCR6 Regulates the Migration of Inflammatory and Regulatory T Cells

Th17 and regulatory T (Treg) cells play opposite roles in autoimmune diseases. However, the mechanisms underlying their proper migration to inflammatory tissues are unclear. In this study, we report that these two T cell subsets both express CCR6. CCR6 expression in Th17 cells is regulated by TGF-beta and requires two nuclear receptors, RORalpha and RORgamma. Th17 cells also express the CCR6 ligand CCL20, which is induced synergistically by TGF-beta and IL-6, which requires STAT3, RORgamma and IL-21. Th17 cells, by producing CCL20, promote migration of Th17 and Treg cells in vitro in a CCR6-dependent manner. Lack of CCR6 in Th17 cells reduces the severity of experimental autoimmune encephalomyelitis and Th17 and Treg recruitment into inflammatory tissues. Similarly, CCR6 on Treg cells is also important for their recruitment into inflammatory tissues. Our data indicate an important role of CCR6 in Treg and Th17 cell migration.

Inhibitory Effect of the New Orally Active CCR4 Antagonist K327 on CCR4+CD4+ T Cell Migration into the Lung of Mice with Ovalbumin-Induced Lung Allergic Inflammation

CC chemokine receptor 4 (CCR4) is expressed on Th2 cells, found in inflamed tissues of allergic diseases, and is therefore suspected to be involved in the pathogenesis of allergic diseases by controlling Th2 cell migration into inflamed tissues. The aim of the present study was to investigate the inhibitory effect of a selective CCR4 antagonist, K327 [6-cyclopropancarbonyl-4-(2,4-dichlorobenzylamino)-2-(4-[2-(piperidin-1-yl)ethyl] piperazin-1-yl)-7,8-dihydro-5H-pyrido (4,3-d)pyrimidine], on the recruitment of CCR4+CD4+ T cells to the airway of mice with ovalbumin-induced allergic airway inflammation. K327 was administered to mice in which CCR4+CD4+ T cell accumulation was elicited by multiple inhalations of aerosolized ovalbumin. K327 significantly and dose-dependently inhibited the recruitment of CCR4+CD4+ T cells with an ID₅₀value of 44 mg/kg, p.o. twice daily. The antiasthmatic potential of K327 was also demonstrated by the fact that K327 suppressed the elevation of Th2 cytokines and airway eosinophilia. These results indicate that CCR4 antagonists can control in vivo migration of Th2 cells which express CCR4 and, presumably, serve as a new class of therapeutic agent for allergy.

CC Chemokine ligand 17 in periodontal diseases: expression in diseased tissues and production by human gingival fibroblasts

It has been reported that T helper 2 (Th2) cells are related to exacerbation of periodontal disease. However, it is uncertain how the migration of Th2 cells is controlled. In this study, we examined the expression of CC chemokine ligand 17 (CCL17), which is a Th2 chemokine, in periodontal tissues. Moreover, we investigated the effects of cytokines and toll-like receptor (TLR) ligands on the production of CCL17 by human gingival fibroblasts (HGFs). We used immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) to detect CCL17 in periodontal tissues. HGFs were exposed to cytokines and TLR ligands. Expression of CCL17 was examined by RT-PCR and enzyme-linked immunosorbent assay. We used signal transduction inhibitors in some experiments. Both CCL17 and its receptor, CC chemokine receptor 4 (CCR4), were expressed in diseased periodontal tissues. A combination of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-4/IL-13 increased CCL17 expression. Moreover, treatment of HGFs with a low dose of interferon-gamma (IFN-gamma) in combination with TNF-alpha and IL-4 or IL-13 had synergistic effects on the production of CCL17, whereas a high dose of IFN-gamma inhibited CCL17 production. Furthermore, Escherichia coli (E. coli) lipopolysaccharide (TLR4 ligand) and Pam3CSK4 (TLR2 ligand) inhibited CCL17 production by TNF-alpha + IL-4-stimulated HGFs, while CpG DNA (TLR9 ligand) enhanced TNF-alpha + IL-4 induced-CCL17 production by HGFs. Furthermore, a c-Jun NH2 terminal kinase (JNK) inhibitor, a phosphatidylinositol-3-kinase (PI3K) inhibitor and a nuclear factor kappa B (NF-kappa B) inhibitor inhibited CCL17 production by HGFs. These results suggest that the CCL17 produced by HGFs may be involved in the migration of Th2 cells into inflamed tissues, and provide evidence that CCL17 production is controlled by cytokines and TLR ligands in periodontal disease.