This study examined the contribution of cysteine-cysteinyl chemokine receptor 6 (CCR6) to the innate pulmonary antimycobacterial immune response. Using a mouse model of Mycobacterium bovis BCG airway infection, we detected maximal induction of the CCR6 agonist CCL20 in lungs at 1 week after infection. Infected CCR6 knockout (CCR6-/-) mice displayed an early impairment of bacterial clearance, but ultimately eliminated the attenuated organisms with the onset of adaptive immunity. Flow-cytometric analyses of bronchoalveolar lavages and dispersed lungs revealed a 60% reduction in TCR-α/β+ T cells in airways but no compromise of TCR-γ/δ+ T cells. The subset of CD1d-restricted, CD8-TCR-α/β+ natural killer cells, which mediate innate mycobacterial resistance, was profoundly reduced (90%). Analysis of the adaptive response using ovalbumin-specific transgenic TCR T cell (OT-II) transfer combined with infection with recombinant M. bovis BCG producing ovalbumin peptide indicated no impairment of adaptive T cell activation in CCR6-/- mice. There was also no impairment of the induction of cytokine-producing cells in draining lymphoid tissue of CCR6-/- mice. Taken together, our findings indicate that CCR6 is not required for induction of the adaptive antimycobacterial response, but is likely critical to airway compartment mobilization of TCR-α/β+CCR6+ innate and adaptive effector T cells.

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.

BACKGROUND

The incidence and progression of many autoimmune diseases are sex-biased, which might be explained by the immunomodulating properties of endocrine hormones. Treatment with estradiol potently inhibits experimental autoimmune arthritis. Interleukin-17-producing T helper cells (Th17) are key players in several autoimmune diseases, particularly in rheumatoid arthritis. The aim of this study was to investigate the effects of estrogen on Th17 cells in experimental arthritis.

METHODS

Ovariectomized DBA/1 mice treated with 17β-estradiol (E2) or placebo were subjected to collagen-induced arthritis (CIA), and arthritis development was assessed. Th17 cells in joints and lymph nodes were studied by flow cytometry. Lymph node Th17 cells were also examined in ovariectomized estrogen receptor α-knockout mice (ERα-/-) and wild-type littermates, treated with E2 or placebo and subjected to antigen-induced arthritis.

RESULTS

E2-treated mice with established CIA showed reduced severity of arthritis and fewer Th17 cells in joints compared with controls. Interestingly, E2-treated mice displayed increased Th17 cells in lymph nodes during the early phase of the disease, dependent on ERα. E2 increased the expression of C-C chemokine receptor 6 (CCR6) on lymph node Th17 cells as well as the expression of the corresponding C-C chemokine ligand 20 (CCL20) within lymph nodes.

CONCLUSIONS

This is the first study in which the effects of E2 on Th17 cells have been characterized in experimental autoimmune arthritis. We report that E2 treatment results in an increase of Th17 cells in lymph nodes during the early phase of arthritis development, but leads to a decrease of Th17 in joints during established arthritis. Our data suggest that this may be caused by interference with the CCR6-CCL20 pathway, which is important for Th17 cell migration. This study contributes to the understanding of the role of estrogen in the development of autoimmune arthritis and opens up new fields for research concerning the sex bias in autoimmune disease.

Subchondral bone remodeling in osteoarthritis (OA) and rheumatoid arthritis (RA) is mainly characterized by the formation of osteophytes/fibrosis and by the presence of infiltrating cells associated to bone resorption. In this study we analyzed CC (cysteine cysteine motif) chemokine ligand (CCL)20 and CC chemokine receptor (CCR)6 function in subchondral bone tissue and osteoblasts isolated from OA and RA patients. CCL20/CCR6 expression was evaluated by immunohistochemical techniques in bone tissue from OA and RA patients. CCL20-functional tests were performed on osteoblasts isolated from OA and RA patients to evaluate enzymatic response and cell proliferation. Moreover, we assessed Akt phosphorylation as the major signaling pathway for CCL20. In bone tissue biopsies we found that osteoblasts from both OA and RA patients expressed CCR6 while CCL20 was expressed only by RA osteoblasts. Both CCR6 and CCL20 were highly expressed in osteocytes and mononuclear cells from only RA patients. CCL20-stimulated OA osteoblasts showed a significant increase in beta-N-acetylhexosaminidase release compared to RA. Conversely, a significant increase in cellular proliferation was found only in CCL20-stimulated RA osteoblasts associated to Akt phosphorylation. These data were confirmed in bone tissue biopsies. This study demonstrates a different expression of CCL20-positive osteoblasts in OA versus RA disease that seem to be associated with the presence of infiltrating mononuclear cells. Moreover, CCL20 stimulation resulted in a greater proliferative response in RA osteoblasts compared to OA osteoblasts, mediated by Akt signaling, while OA osteoblasts showed increased enzymatic activity, thus suggesting a differential role of this chemokine in OA and RA.

Atopic dermatitis is a common pruritic and chronically relapsing inflammatory skin disease. Atopic dermatitis patients show disturbed skin barrier functions, frequent allergic responses against allergens, defects in the antimicrobial immune defense, and a genetic predisposition. Clinical and experimental evidence points to a role for staphylococcal superantigens during the initiation and amplification of atopic skin inflammation. In the past decade, numerous studies identified chemokines including CCL1, CCL2, CCL3, CCL4, CCL5, CCL11, CCL13, CCL17, CCL18, CCL20, CCL22, CCL26, CCL27 and CX3CL1 to be associated with atopic dermatitis. Here we summarize recent findings suggesting a role for staphylococcal superantigens in the production of chemokines during the development of atopic skin inflammation.

Atopic dermatitis (AD) is a chronic inflammatory skin disease, which is accompanied by marked increases in the levels of inflammatory cells, including mast cells and eosinophils as well as T cells and macrophages. To investigate the expression pattern of chemokines in AD, a house dust mite, Dermatophagoides farinae extracts (DfE)-induced NC/Nga AD model was developed in mice, and this model was used to determine the expression levels of chemokines in atopic lesions using DNA microarrays and RT-PCR. When NC/Nga mice were repeatedly treated with DfE for 4 to 7 weeks on the back skin, the mRNA expression levels of CCL20/LARC, CCL24/eotaxin-2, CCL17/TARC, and CCL11/eotaxin-1 were markedly induced and lesser of CCL2/MCP-1, within the inflammatory lesion of the back skin. Immunohistochemical staining revealed the expression of these chemokines in the epidermis and dermis of DfE-treated NC/Nga mice. Interestingly, repeated application of tacrolimus ointment potently inhibited DfE-induced atopic dermatitis in NC/Nga mice concomitant with the inhibition of these changes in chemokine gene and protein expression levels particularly of CCL20/LARC, CCL17/TARC, and CCL11/eotaxin-1. These data indicate that severe atopic dermatitis induced by DfE accompanies elevated chemokine levels, and it was proposed that tacrolimus ointment is beneficial for the treatment of severe AD.

Protease-activated receptors (PARs) are G-protein-coupled receptors with an active role in host defense. The two most highly expressed members of the PAR family in gingival epithelial cells (GECs) are PAR1 and PAR2. The major virulence factors of periodontal pathogen Porphyromonas gingivalis are its proteases which can activate PAR2. However, little is known about the function of PARs in GECs when they are activated by their endogenous agonist enzymes. The purpose of this study was to characterize how the expression of innate immune markers is modulated when PAR1 and PAR2 are activated by their agonist enzymes, thrombin and trypsin, respectively. Here, we report that activation of PAR1 and PAR2 induces cell proliferation at low concentration. Activation of PAR via proteolytic activity of thrombin and trypsin induces expression of CXCL5/ENA-78 and CCL20/MIP3alpha in a concentration-dependent manner. Induction of CXCL5 via PAR1 was inhibited in the presence of PAR1 cleavage blocking antibodies and by PAR1 siRNA. The induction of CXCL5 and CCL20 via PAR2 was inhibited by PAR2 siRNA. These findings indicate an active role in innate immune responses by PAR1 and PAR2 in GECs. Modulation of innate immunity by PARs may contribute to co-ordinated and balanced immunosurveillance in GECs.

Amoebiasis caused by Entamoebahistolytica triggers an acute inflammatory response at early stages of intestinal infection. The patho-physiological study of intestinal amoebiasis requires the development of powerful animal models. Swine provide robust model for human diseases and they could be used to study intestinal amoebiasis. Here, we introduce an in vitro model of swine intestinal epithelial cell (IPI-2I) co-cultured with E. histolytica. Intestinal epithelial cells (IECs) have crucial roles in sensing pathogens and initiating innate immune response, which qualitatively influence adaptive immune response against them. The contact between the two cells induces marked macroscopic lesions of IEC monolayer and striking alteration of the IPI-2I cell phenotype including blebbing, such as loss of attachment before to be phagocyte by the trophozoite. Increase in Lactate Dehydrogenase (LDH) levels in the culture supernatant of IECs was observed when ameba is present and could reflect the cellular cytotoxicity exerted by the parasite. Using quantitative real-time PCR, we identified the up-regulation of cytokines/chemokines implicated in neutrophil chemoattraction and inflammation, such as CCL2, CCL20, CXCL2, CXCL3, GM-CSF, IL1 alpha, IL6 and IL8, in response to the parasite that can further regulate the immunoregulatory functions of the immune cells of the host. The study points a cardinal role of these pro-inflammatory compounds as central mediators in the interaction IECs/ameba and suggests mechanisms by which they coordinate intestinal immune response. This will focus future efforts on delineating the molecular and cellular mechanisms of other cell partners by the way of in vivo infection of swine.

BACKGROUND

β-Agonists are used for relief and control of asthma symptoms by reversing bronchoconstriction. They might also have anti-inflammatory properties, but the underpinning mechanisms remain poorly understood. Recently, a direct interaction between formoterol and protein phosphatase 2A (PP2A) has been described in vitro.

OBJECTIVE

We sought to elucidate the molecular mechanisms by which β-agonists exert anti-inflammatory effects in allergen-driven and rhinovirus 1B-exacerbated allergic airways disease (AAD).

METHODS

Mice were sensitized and then challenged with house dust mite to induce AAD while receiving treatment with salmeterol, formoterol, or salbutamol. Mice were also infected with rhinovirus 1B to exacerbate lung inflammation and therapeutically administered salmeterol, dexamethasone, or the PP2A-activating drug (S)-2-amino-4-(4-[heptyloxy]phenyl)-2-methylbutan-1-ol (AAL[S]).

RESULTS

Systemic or intranasal administration of salmeterol protected against the development of allergen- and rhinovirus-induced airway hyperreactivity and decreased eosinophil recruitment to the lungs as effectively as dexamethasone. Formoterol and salbutamol also showed anti-inflammatory properties. Salmeterol, but not dexamethasone, increased PP2A activity, which reduced CCL11, CCL20, and CXCL2 expression and reduced levels of phosphorylated extracellular signal-regulated kinase 1 and active nuclear factor κB subunits in the lungs. The anti-inflammatory effect of salmeterol was blocked by targeting the catalytic subunit of PP2A with small RNA interference. Conversely, increasing PP2A activity with AAL(S) abolished rhinovirus-induced airway hyperreactivity, eosinophil influx, and CCL11, CCL20, and CXCL2 expression. Salmeterol also directly activated immunoprecipitated PP2A in vitro isolated from human airway epithelial cells.

CONCLUSIONS

Salmeterol exerts anti-inflammatory effects by increasing PP2A activity in AAD and rhinovirus-induced lung inflammation, which might potentially account for some of its clinical benefits.

Recent clinical data have led to the consideration of sexual steroids as new potential therapeutic tools for multiple sclerosis. Selective estrogen receptor modulators can exhibit neuroprotective effects like estrogen, with fewer systemic estrogen side effects than estrogen, offering a more promising therapeutic modality for multiple sclerosis. The important role of astrocytes in a proinflammatory effect mediated by CCL20 signaling on inflammatory cells has been documented. Their potential contribution to selective estrogen receptor modulator-mediated protection is still unknown. Using a mouse model of chronic neuroinflammation, we report that raloxifene, a selective estrogen receptor modulator, alleviated experimental autoimmune encephalomyelitis-an animal model of multiple sclerosis-and decreased astrocytic production of CCL20. Enzyme-linked immunosorbent assay, immunohistochemistry imaging and transwell migration assays revealed that reactive astrocytes express CCL20, which promotes Th17 cell migration. In cultured rodent astrocytes, raloxifene inhibited IL-1β-induced CCL20 expression and chemotaxis ability for Th17 migration, whereas the estrogen receptor antagonist ICI 182,780 blocked this effect. Western blotting further indicated that raloxifene suppresses IL-1β-induced NF-κB activation (phosphorylation of p65) and translocation but does not affect phosphorylation of IκB. In conclusion, these data demonstrate that raloxifene provides robust neuroprotection against experimental autoimmune encephalomyelitis, partially via an inhibitory action on CCL20 expression and NF-κB pathways in reactive astrocytes. Our results contribute to a better understanding of the critical roles of raloxifene in treating experimental autoimmune encephalomyelitis and uncover reactive astrocytes as a new target for the inhibitory action of estrogen receptors on chemokine CCL20 expression.

We recently demonstrated that upregulation of a chemokine receptor CCR6 and its ligand CCL20 led to metastasis of advanced cutaneous T-cell lymphoma (CTCL) cells, suggesting the involvement of CCL20-CCR6 interaction in initiating CTCL cell metastasis. In this study, we determined whether this interaction is functional in metastatic CTCL cells. We first demonstrated increased STAT3 expression during the progression of primary CTCL. STAT3 was spontaneously activated and mediated the transcription of CCL20 in CTCL cell lines. Next, to determine whether the transient knockdown of STAT3, CCL20, or CCR6 or treatment with neutralizing antibody against CCL20 (neutralizing CCL20 antibody) could reduce the migration ability of CTCL cells, we conducted an in vitro migration assay. All treatments reduced the nutrition-dependent migration activity of CTCL cells. Notably, treatment with neutralizing CCL20 antibody reduced the migration ability of the cells without decreasing the expression of CCL20 and CCR6. This demonstrated that the CCL20-CCR6 interaction is actually functional in metastatic CTCL cells. Finally, to examine the in vivo effect of neutralizing CCL20 antibody, we used NOD/Shi-scid IL-2γnul mice inoculated with CTCL cells. These mice were expected to die due to metastasis of CTCL cells into multiple organs. However, administration of neutralizing CCL20 antibody significantly prolonged the survival of the xenografted mice. These findings suggested that automatic activation of the STAT3/CCL20/CCR6 cascade was involved in CTCL lymphomagenesis and that disruption of CCL20-CCR6 interaction could be a key therapeutic strategy against advanced CTCL.

Chemokines represent central players of the innate and adaptive immunity and are involved in the regulation of inflammatory events occurring during infectious complications or during graft vs. host disease (GvHD). Patients after allogeneic stem cell transplantation (alloSCT) are at a high risk for the development of acute GvHD or to suffer from fungal infections. Susceptibility to fungal infections and the course of GvHD can be genetically influenced by single nucleotide polymorphisms (SNPs), which regulate expression or biological activity of chemokines, and therefore have an impact on the outcome of invasive aspergillosis and GvHD. High lightened studies of abetting factors for GvHD revealed SNPs in TNFA, IL-6, IL-10, INF-γ, CCL2, CCL5 (RANTES), IL-1Ra, IL-23R, IL-7Ralpha, IL-10RB, and CCR9 genes as prevalent considerable. Furthermore, additional SNPs were described to be significantly associated with fungal infections (Aspergillus fumigatus, Candida albicans), including markers in CCL3, CCL4, CCL20, CXCL2, CXCL8, CXCL10, CCR1, and CCR2. This review summarizes the current knowledge about the growing number of genetic markers in chemokine genes and their relevance for patients after alloSCT.

BACKGROUND

Maculopapular exanthema (MPE) is the most frequent clinical manifestation of nonimmediate allergic reactions to drugs and T helper 1 (Th1) cytokines and CD4(+) T cells have been shown to play an important role in its pathogenesis. We assessed the role of cytokines and chemokines and their receptors in the pathogenesis of MPE.

METHODS

We evaluated skin biopsies and peripheral CD4(+) and CD8(+) T cells from 27 patients during the acute phase of the reaction and 26 exposed controls. Semiquantitative real-time PCR was performed to determine the expression of cytokines and chemokines and their receptors and immunohistochemistry was used to determine the same chemokines and their receptor proteins in skin.

RESULTS

There was a high expression of the Th1 cytokines interferon-gamma (P = 0.006) and tumor necrosis factor-alpha (P = 0.022) in skin and CD4(+) T cells (P = 0.007 and P = 0.005, respectively); and of the Th1 chemokines CXCL9 (P = 0.005) and CXCL10 (P = 0.028) in the skin, while their receptor CXCR3 was increased in skin (P = 0.006) and CD4(+) T cells (P = 0.03). Homing chemokine receptors were also increased: CCR6 in skin (P = 0.026) and CD4(+) T cells (P = 0.016), and CCR10 only in CD4(+) T cells (P = 0.016), as well as their ligands, CCL20 and CCL27, in skin alone. Immunohistochemistry confirmed these results.

CONCLUSIONS

These data show significant differences in the expression of chemokines and chemokine receptors, related with a Th1 profile, in both skin biopsies and peripheral CD4(+) T cells in patients with drug-induced MPE.

We assessed the effect of voriconazole (VRC) on the expression and release of selected cytokines and chemokines in the THP-1 human monocytic cell line in response to Aspergillus fumigatus hyphal fragments (HF) by cDNA microarray analysis, reverse transcriptase (RT) PCR, and enzyme-linked immunosorbent assay. Stimulation of THP-1 cells by HF alone caused a significant up-regulation of CCL4 (MIP1B) and CCL16, while CCL2 (MCP1) was down-regulated. By comparison, in the presence of VRC, a large number of genes such as CCL3 (MIP1A), CCL4 (MIP1B), CCL5 (RANTES), CCL7 (MCP3), CCL11 (EOTAXIN), CCL15 (MIP1Delta), CXCL6, and CXCL13 were strongly up-regulated in THP-1 cells challenged by HF, whereas CCL20 (MIP3A) and CCL21 (MIP2) were down-regulated. Among five genes differentially expressed in THP-1 cells, IL12A, IL12B, and IL-16 were down-regulated whereas IL-11 and TGFB1 were significantly up-regulated in the presence of VRC. The inflammation-related genes IFNgamma, IL1R1, and TNFA were also up-regulated in THP-1 cells exposed to HF only in the presence of VRC. RT-PCR of four selected genes validated the results of microarrays. The release of interleukin 1beta (IL-1beta) and IL-12 was significantly increased from monocytes stimulated either by HF alone (P < 0.05) or in the presence of VRC (P < 0.01 and P < 0.05, respectively). In contrast, tumor necrosis factor alpha release from monocytes was enhanced only in the presence of VRC (P < 0.01). The chemokines monocyte chemoattractant protein 1 and macrophage inflammatory protein 1beta were decreased under both conditions (P < 0.01). These results demonstrate that in the presence of VRC, HF induces a more pronounced profile of gene expression in THP-1 cells than HF alone, potentially leading to more-efficient host resistance to A. fumigatus.

Psoriasis is a chronic IL-23/Th17 pathway-associated skin disease. An increased expression of lesional CCL20 can recruit CCR6+ Th17, and lesional cytokine milieu persistently activates keratinocytes to produce CCL20. Lipid-lowering drugs, statins, are known to possess immune-modulating functions. In this study, we explored an inhibitory effect of statins on CCL20/CCR6 interaction. We demonstrated that IL-1β, TNF-α, and IL-17A significantly increased CCL20 production from HaCaT cells. However, these increments were markedly inhibited by fluvastatin and simvastatin, but not by pravastatin. In the chemotaxis migration assay, pretreatment with fluvastatin and simvastatin inhibited the migration of human CD4+ T cells towards CCL20. However, the level of CCR6 surface expression in memory CD4+ T cells was not affected. Our results suggest that not all, but specific types of statins may be of benefit in alleviating psoriasis partially via interrupting CCL20/CCR6 chemotactic interaction, the mechanism which may eventually lessen the infiltration of Th17 cells.

Re-epithelialization is an important part in mucosal wound healing. Surprisingly little is known about the impact of diabetes on the molecular events of mucosal healing. We examined the role of the transcription factor forkhead box O1 (Foxo1) in oral wounds of diabetic and normoglycemic mice with keratinocyte-specific Foxo1 deletion. Diabetic mucosal wounds had significantly delayed healing with reduced cell migration and proliferation. Foxo1 deletion rescued the negative impact of diabetes on healing but had the opposite effect in normoglycemic mice. Diabetes in vivo and in high glucose conditions in vitro enhanced expression of chemokine (C-C motif) ligand 20 (CCL20) and interleukin-36γ (IL-36γ) in a Foxo1-dependent manner. High glucose-stimulated Foxo1 binding to CCL20 and IL-36γ promoters and CCL20 and IL-36γ significantly inhibited migration of these cells in high glucose conditions. In normal healing, Foxo1 was needed for transforming growth factor-β1 (TGF-β1) expression, and in standard glucose conditions, TGF-β1 rescued the negative effect of Foxo1 silencing on migration in vitro. We propose that Foxo1 under diabetic or high glucose conditions impairs healing by promoting high levels of CCL20 and IL-36γ expression but under normal conditions, enhances it by inducing TGF-β1. This finding provides mechanistic insight into how Foxo1 mediates the impact of diabetes on mucosal wound healing.

OBJECTIVE

To identify changes in gene expression in human corneal fibroblasts after exposure to interleukin-1alpha.

METHODS

RNA was isolated from cultured human corneal fibroblasts after treatment with interleukin-1alpha and subjected to DNA microarray analysis. Changes in gene expression were determined by comparison with untreated cells in three independent experiments after a Bayesian statistical analysis of variance.

RESULTS

Changes in gene expression were reproducibly observed in 165 genes representing previously identified and novel chemokines, matrix molecules, membrane receptors, angiogenic mediators, and transcription factors that correlated with pathophysiological responses to inflammation. Dramatic increases in gene expression were observed with exodus-1 (CCL20), MMP-12, and RhoA.

CONCLUSIONS

DNA microarray analysis of the corneal fibroblast response to interleukin-1alpha provides important insight into modeling changes in gene expression and suggests novel therapeutic targets for the control of corneal inflammation.

Toll-like receptors (TLRs) are involved in the production of inflammatory mediators upon specific ligands stimuli. Chemokines are important inflammatory mediators capable of chemoattracting diverse immune cells. In addition to normal immune cells, the expression of TLRs and chemokines has been detected in various tumor cells. However, the roles of TLRs and chemokines expressed by tumor cells in the processes of tumor progression and immune escape have not been fully elucidated. Here we report that TLR4 ligation by lipopolysaccharide (LPS) significantly promotes CT-26 colon cancer cells to produce chemokine CCL20 via activation of TLR4 signaling pathways. We find that LPS treatment of CT-26 cells can significantly increase the chemoattraction of immature dendritic cells (DC) by the autocrine CCL20. Our studies suggest that TLR4 expressed by tumor cells may be involved in the induction of chemokines like CCL20, providing a potential linkage between chronic inflammation and tumor immune escape.

Kidney dendritic cells (DCs) regulate nephritogenic T cell responses. Most kidney DCs belong to the CD11b+ subset and promote crescentic GN (cGN). The function of the CD103+ subset, which represents <5% of kidney DCs, is poorly understood. We studied the role of CD103+ DCs in cGN using several lines of genetically modified mice that allowed us to reduce the number of these cells. In all lines, we detected a reduction of FoxP3+ intrarenal regulatory T cells (Tregs), which protect against cGN. Mice lacking the transcription factor Batf3 had a more profound reduction of CD103+ DCs and Tregs than did the other lines used, and showed the most profound aggravation of cGN. The conditional reduction of CD103+ DC numbers by 50% in Langerin-DTR mice halved Treg numbers, which did not suffice to significantly aggravate cGN. Mice lacking the cytokine Flt3L had fewer CD103+ DCs and Tregs than Langerin-DTR mice but exhibited milder cGN than did Batf3-/- mice presumably because proinflammatory CD11b+ DCs were somewhat depleted as well. Conversely, Flt3L supplementation increased the number of CD103+ DCs and Tregs, but also of proinflammatory CD11b+ DCs. On antibody-mediated removal of CD11b+ DCs, Flt3L supplementation ameliorated cGN. Mechanistically, CD103+ DCs caused cocultured T cells to differentiate into Tregs and produced the chemokine CCL20, which is known to attract Tregs into the kidney. Our findings show that CD103+ DCs foster intrarenal FoxP3+ Treg accumulation, thereby antagonizing proinflammatory CD11b+ DCs. Thus, increasing CD103+ DC numbers or functionality might be advantageous in cGN.

BACKGROUND

Innate lymphoid cells (ILC) have been implicated in the initiation of inflammation and fibrosis in mice. However, ILC have not been characterized in inflamed human liver tissue.

METHODS

Human intrahepatic lymphocytes were isolated by mechanical digestion and phenotyped by flow cytometry. Conditioned medium from cultures of primary human biliary epithelial cells, stellate cells, fibroblasts and inflamed human liver tissue was used to model the effects of the inflammatory liver environment of ILC phenotype and function.

RESULTS

All three ILC subsets were present in the human liver, with the ILC1 (CRTH2negCD117neg) subset constituting around 70% of intrahepatic ILCs. Both NCRpos (NKp44+) and NCRneg ILC3 (CRTH2negCD117pos) subsets were also detected. ILC2 (CRTH2pos) frequency correlated with disease severity measured by model of end stage liver disease (MELD) scoring leading us to study this subset in more detail. ILC2 displayed a tissue resident CD69+ CD161++ phenotype and expressed chemokine receptor CCR6 allowing them to respond to CCL20 secreted by cholangiocytes and stellate cells. ILC2 expressed integrins VLA-5 and VLA-6 and the IL-2 and IL-7 cytokine receptors CD25 and CD127 although IL-2 and IL-7 were barely detectable in inflamed liver tissue. Although biliary epithelial cells secrete IL-33, intrahepatic ILC2 had low expression of the ST2 receptor. Intrahepatic ILC2 secreted the immunoregulatory and repair cytokines IL-13 and amphiregulin.

CONCLUSIONS

Intrahepatic ILC2 express receptors allowing them to be recruited to bile ducts in inflamed portal tracts. Their frequencies increased with worsening liver function. Their secretion of IL-13 and amphiregulin suggests they may be recruited to promote resolution and repair and thereby they may contribute to ongoing fibrogenesis in liver disease.

The chemokine receptor CCR6 is expressed by various cell subsets implicated in atherogenesis, such as monocytes, Th17 and regulatory T cells. In order to further define the role of CCR6 in atherosclerosis, CCR6-deficient (Ccr6-/-) mice were crossed with low-density lipoprotein receptor-deficient (Ldlr-/-) mice to generate atherosclerosis-prone mice deficient in CCR6. Compared to Ldlr-/- controls, atherosclerotic burden in the aortic sinus and aorta were reduced in Ccr6-/-Ldlr-/- mice fed a high fat diet, associated with a profound depression in lesional macrophage accumulation. Local and systemic distributions of T cells, including frequencies of Th1, Th17 and regulatory T cells were unaltered. In contrast, circulating counts of both Gr-1(high) and Gr1(low) monocytes were reduced in Ccr6-/-Ldlr-/- mice. Moreover, CCR6 was revealed to promote monocyte adhesion to inflamed endothelium in vitro and leukocyte adhesion to carotid arteries in vivo. Finally, CCR6 selectively recruited monocytes but not T cells in an acute inflammatory air pouch model. We here show that CCR6 functions on multiple levels and regulates the mobilisation, adhesion and recruitment of monocytes/macrophages to the inflamed vessel, thereby promoting atherosclerosis, but is dispensable for hypercholesterolaemia-associated adaptive immune priming. Targeting CCR6 or its ligand CCL20 may therefore be a promising therapeutic strategy to alleviate atherosclerosis.

The magnitude of the cellular adaptive immune response is critical for the control of Mycobacterium tuberculosis infection in the chronic phase. In addition, the genetic background is equally important for resistance or susceptibility to tuberculosis. In this study, we addressed whether lung populations of dendritic cells, obtained from genetically different hosts, would play a role in the magnitude and function of CD4(+) populations generated after M. tuberculosis infection. Thirty days post-infection, C57BL/6 mice, which generate a stronger interferon-γ (IFN-γ)-mediated immune response than BALB/c mice, exhibited a higher number and frequency of lung CD11c(+) CD11b(-) CD103(+) cells compared with BALB/c mice, which exhibited a high frequency of lung CD11c(+) CD11b(+) CD103(-) cells. CD11c(+) CD11b(-) CD103(+) cells, purified from lungs of infected C57BL/6 mice, but not from infected BALB/c mice, induced a higher frequency of IFN-γ-producing or interleukin-17 (IL-17)-producing CD4(+) cells. Moreover, CD4(+) cells also arrive at the lung of C57BL/6 mice faster than in BALB/c mice. This pattern of immune response seems to be associated with higher gene expression for CCL4, CCL19, CCL20 and CCR5 in the lungs of infected C57BL/6 mice compared with infected BALB/c mice. The results described here show that the magnitude of IFN-γ-producing or IL-17-producing CD4(+) cells is dependent on CD11c(+) CD11b(-) CD103(+) cells, and this pattern of immune response is directly associated with the host genetic background. Therefore, differences in the genetic background contribute to the identification of immunological biomarkers that can be used to design human assays to predict progression of M. tuberculosis infection.

The chemokine receptor CCR6, selectively bound by CCL20, is involved in the metastatic spread of cancer cells. Tumor necrosis factor-α (TNF-α) displays a complex pro-tumorigenic actions, but it is unknown whether this cytokine could modulate the expression of chemokine receptors in thyroid tumors. The membrane expression of CCR6 was assessed by flow cytometry and immunofluorescence, in primary cultures of normal human thyroid (NHT) cells and in thyroid cancer cell lines (TPC-1 and BCPAP), both in basal conditions and after stimulation with TNF-α. In basal conditions, CCR6+ cells were virtually absent in NHT cells (0.4 ± 0.4 %), while they were detected in TPC-1 (23.6 ± 6.6 %) and in BCPAP (12.9 ± 9.4 %) tumor cells (ANOVA F: 10.534; p < 0.005). The incubation with TNF-α significantly increased the percentage of CCR6+ cells in TPC-1 (23.6 ± 6.6 % vs. 33.1 ± 8.7; p < 0.033) and in BCPAP (12.9 ± 9.4 % vs. 18.1 ± 11.5; p < 0.030), but not in NHT (0.4 ± 0.4 % vs. 0.2 ± 0.3; NS) cells. The magnitude of the TNF-α effect was similar for TPC-1 and BCPAP (∼40 % vs. baseline) cells. TPC-1 cells were characterized by a greater amount of CCR6 per cell as compared with BCPAP cells, both in basal conditions (148.3 ± 33.7 fluorescence intensity vs. 102.5 ± 22.1 p < 0.016) and after TNF-α stimulation (147.8 ± 46.3 fluorescence intensity vs. 95.3 ± 18.5; p < 0.025). Cell migration assays showed that TNF-α treatment significantly increased the rate of migrated cells in those cells in which it also increased the membrane expression of CCR6 (TPC-1 and BCPAP) as compared to basal condition (p < 0.05 for both TPC-1 and BCPAP cells). No effect was observed in NHT cells in which TNF-α stimulation had no effect in terms of CCR6 expression. We first report that TNF-α enhances the expression of CCR6 in thyroid tumor cells, thus providing evidence that TNF-α increases the metastatic potential of thyroid tumors.

Lung epithelial cells (LECs) are strategically positioned in the airway mucosa to provide barrier defense. LECs also express pattern recognition receptors and a myriad of immune genes, but their role in immunity is often concealed by the activities of "professional" immune cells, particularly in the context of fungal infection. Here, we demonstrate that NF-κB signaling in LECs is essential for immunity against the pulmonary fungal pathogen Blastomyces dermatitidis. LECs orchestrate innate antifungal immunity by augmenting the numbers of interleukin-17A (IL-17A)- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing innate lymphocytes, specifically "natural" Th17 (nTh17) cells. Innate lymphocyte-derived IL-17A and GM-CSF in turn enable phagocyte-driven fungal killing. LECs regulate the numbers of nTh17 cells via the production of chemokines such as CCL20, a process dependent on IL-1α-IL-1 receptor (IL-1R) signaling on LECs. Therefore, LECs orchestrate IL-17A- and GM-CSF-mediated immunity in an IL-1R-dependent manner and represent an essential component of innate immunity to pulmonary fungal pathogens.