Expression and role of CCR6/CCL20 chemokine axis in pulmonary sarcoidosis

Pro-Fibrotic Effects of CCL18 on Human Lung Fibroblasts Are Mediated via CCR6

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease of unknown origin, with a median patient survival time of ~3 years after diagnosis without anti-fibrotic therapy. It is characterized by progressive fibrosis indicated by increased collagen deposition and high numbers of fibroblasts in the lung. It has been demonstrated that CCL18 induces collagen and αSMA synthesis in fibroblasts. We aimed to identify the CCL18 receptor responsible for its pro-fibrotic activities.

METHODS

We used a random phage display library to screen for potential CCL18-binding peptides, demonstrated its expression in human lungs and fibroblast lines by PCR and immunostaining and verified its function in cell lines.

RESULTS

We identified CCR6 (CD196) as a CCL18 receptor and found its expression in fibrotic lung tissue and lung fibroblast lines derived from fibrotic lungs, but it was almost absent in control lines and tissue. CCL18 induced receptor internalization in a CCR6-overexpressing cell line. CCR6 blockade in primary human lung fibroblasts reduced CCL18-induced FGF2 release as well as collagen-1 and αSMA expression. Knockdown of CCR6 in a mouse fibroblast cell line abolished the induction of collagen and α-smooth muscle actin expression.

CONCLUSION

Our data indicate that CCL18 triggers pro-fibrotic processes via CCR6, highlighting its role in fibrogenesis.

Emerging Therapeutic Options for Refractory Pulmonary Sarcoidosis: The Evidence and Proposed Mechanisms of Action

Sarcoidosis is a systemic disease with heterogenous clinical phenotypes characterized by non-necrotizing granuloma formation in affected organs. Most disease either remits spontaneously or responds to corticosteroids and second-line disease-modifying therapies. These medications are associated with numerous toxicities that can significantly impact patient quality-of-life and often limit their long-term use. Additionally, a minority of patients experience chronic, progressive disease that proves refractory to standard treatments. To date, there are limited data to guide the selection of alternative third-line medications for these patients. This review will outline the pathobiological rationale behind current and emerging therapeutic agents for refractory or drug-intolerant sarcoidosis and summarize the existing clinical evidence in support of their use.

Panel of miR-150 and linc00673, regulators of CCR6/CCL20 may serve as non-invasive diagnostic marker of non-small cell lung cancer

The C-C motif ligand 20 (CCL20) is a chemokine that specifically binds to the chemokine receptor 6 (CCR6) and the CCL20/CCR6 axis has been implicated in the non-small lung cancer (NSCLC) development and progression. Its expression is regulated by mutual interactions of non-coding RNAs (ncRNAs). This goals of presented study was to evaluate the expression level of CCR6/CCL20 mRNA in NSCLC tissue comparative to selected ncRNAs: miR-150, linc00673. The expression level of the studied ncRNAs was also assessed in serum extracellular vesicles (EVs). Thirty patients (n = 30) were enrolled as the study cohort. Total RNA was isolated from tumor tissue, adjacent macroscopically unchanged tissue and serum EVs. The expression level of studied genes and ncRNAs were estimated based on the qPCR method. Higher expression level of CCL20 mRNA but lower expression level of CCR6 mRNA were observed in tumor in comparison to control tissue. Relative to the smoking status, higher CCL20 (p < 0.05) and CCR6 mRNA (p > 0.05) expression levels were observed in current smokers than in never smokers. In serum EVs the expression level of miR-150 has a negative correlation with AJCC tumor staging, whereas the expression level of linc00673 positively correlated (p > 0.05). The lower expression level of miR-150 and higher expression level of linc00673 in serum EVs were observed in NSCLC patients with lymph nodes metastases (p > 0.05). Regarding the histopathological type, significantly lower expression level of miR-150 and higher expression level of linc00673 were observed in the serum EVs of patients with AC compared to patient with SCC. Our findings revealed that smoking significantly changed the expression level of CCL20 mRNA in NSCLC tissue. Changes in expression levels of miR-150 and linc00673 in the serum EVs of NSCLC patients in relation to presence of lymph node metastases and the stage of cancer development may serve as a non-invasive molecular biomarkers of tumor progression. Furthermore, expression levels of miR-150 and linc00673 may serve as non-intrusive diagnostic biomarkers differentiating adenocarcinoma from squamous cell carcinoma.

Phenotypic and functional characterization of pharmacologically expanded Vγ9Vδ2 T cells in pigtail macaques

While gaining interest as treatment for cancer and infectious disease, the clinical efficacy of Vγ9Vδ2 T cell-based immunotherapeutics has to date been limited. An improved understanding of γδ T cell heterogeneity across lymphoid and non-lymphoid tissues, before and after pharmacological expansion, is required. Here, we describe the phenotype and tissue distribution of Vγ9Vδ2 T cells at steady state and following in vivo pharmacological expansion in pigtail macaques. Intravenous phosphoantigen administration with subcutaneous rhIL-2 drove robust expansion of Vγ9Vδ2 T cells in blood and pulmonary mucosa, while expansion was confined to the pulmonary mucosa following intratracheal antigen administration. Peripheral blood Vγ9Vδ2 T cell expansion was polyclonal, and associated with a significant loss of CCR6 expression due to IL-2-mediated receptor downregulation. Overall, we show the tissue distribution and phenotype of in vivo pharmacologically expanded Vγ9Vδ2 T cells can be altered based on the antigen administration route, with implications for tissue trafficking and the clinical efficacy of Vγ9Vδ2 T cell immunotherapeutics.

Single-cell sequencing unveils distinct immune microenvironments with CCR6-CCL20 crosstalk in human chronic pancreatitis

OBJECTIVE

Chronic pancreatitis (CP) is a potentially fatal disease of the exocrine pancreas, with no specific or effective approved therapies. Due to difficulty in accessing pancreas tissues, little is known about local immune responses or pathogenesis in human CP. We sought to characterise pancreatic immune responses using tissues derived from patients with different aetiologies of CP and non-CP organ donors in order to identify key signalling molecules associated with human CP.

DESIGN

We performed single-cell level cellular indexing of transcriptomes and epitopes by sequencing and T-cell receptor (TCR) sequencing of pancreatic immune cells isolated from organ donors, hereditary and idiopathic patients with CP who underwent total pancreatectomy. We validated gene expression data by performing flow cytometry and functional assays in a second patient with CP cohort.

RESULTS

Deep single-cell sequencing revealed distinct immune characteristics and significantly enriched CCR6⁺ CD4⁺ T cells in hereditary compared with idiopathic CP. In hereditary CP, a reduction in T-cell clonality was observed due to the increased CD4⁺ T (Th) cells that replaced tissue-resident CD8⁺ T cells. Shared TCR clonotype analysis among T-cell lineages also unveiled unique interactions between CCR6⁺ Th and Th1 subsets, and TCR clustering analysis showed unique common antigen binding motifs in hereditary CP. In addition, we observed a significant upregulation of the CCR6 ligand (CCL20) expression among monocytes in hereditary CP as compared with those in idiopathic CP. The functional significance of CCR6 expression in CD4⁺ T cells was confirmed by flow cytometry and chemotaxis assay.

CONCLUSION

Single-cell sequencing with pancreatic immune cells in human CP highlights pancreas-specific immune crosstalk through the CCR6-CCL20 axis, a signalling pathway that might be leveraged as a potential future target in human hereditary CP.

Sarcoid-like Granulomatosis Associated with Immune Checkpoint Inhibitors in Melanoma

We aimed to review the clinical and biological presentation of granulomatosis associated with immune-checkpoint inhibitors (ICI) in patients with melanoma and to explore its association with classical sarcoidosis as well as with cancer response to ICI. To this end, a retrospective study on 18 melanoma patients with histologically proven ICI-induced granulomatosis over a 12-year period in a single center, as well as on 67 similar cases reported in the literature, was conducted. Results indicate ICI-induced granulomatosis is an early side effect (median time to onset: 2 months). Its clinical presentation, with predominant (90%) thoracic involvement, histopathological appearance and supposed underlying biology (involving the mTOR pathway in immune cells, Th17 polarization and TReg dysfunction) are indistinguishable from those of sarcoidosis. Moreover, it appears to be associated with ICI benefit (>65% objective response rate). Evolution is generally favorable, and symptomatic steroid treatment and/or ICI discontinuation are rarely necessary. ICI-associated granulomatosis is critical to explore for several reasons. Practically, it is essential to differentiate it from cancer progression. Secondly, this “experimental” sarcoidosis brings new elements that may help to address sarcoidosis origin and pathophysiology. Its association with ICI efficacy must be confirmed on a larger scale but could have significant impacts on patient management and biomarker definition.

Serum amyloid A/anti-CCL20 induced the rebalance of Th17/regulatory T cells in SodA-induced sarcoidosis

Sarcoidosis is a multisystemic granulomatous inflammation associated with Th17/regulatory T cell (Treg) polarization. As a marker of inflammation, serum amyloid A (SAA) could upregulate the expression of chemokine ligand 20 (CCL20), which induces the migration of Treg cells and Th17 cells by binding and activating thechemokine C-C receptor (CCR) 6. Our goal was to determine whether SAA/anti-CCL20 induces Th17/Treg rebalance in pulmonary sarcoidosis. The deposition of SAA- and Th17/Treg-related proteins in SodA-induced granulomas was tested using immunohistochemistry. Mice with SodA-induced sarcoidosis were treated with SAA or SAA + anti-CCL20, and then Th1/Th2 and Th17/Treg cells were detected by fluorescence-activated cell sorting (FACS) analysis. The expression of SAA/CCL20 and IL-23/IL-17A was detected by enzyme-linked immunosorbent assay (ELISA) and multiplex. Key proteins in the TGF-β/Smad signaling pathway were tested by western blot. SAA mainly plays a pro-inflammatory role by promoting the expression of CCL20 and IL-17A in bronchoalveolar lavage fluid (BALF) and serum, exacerbating this elevation of CD4+/CD8+ T cells in both mediastinal lymph nodes (LNs) and BALF, as well as proliferating Th1 in LNs in SodA-induced pulmonary sarcoidosis. In addition, SAA could also promote the proliferation of Tregs in LNs. Intriguingly, blocking of CCL20 could partially reverse the expression of Th17-related cytokine, ameliorate Th1/Th2 and Treg/Th17 bias in mice with SodA-induced pulmonary sarcoidosis, and rescue the overactivation of the TGF-β/Smad2/Smad3 signaling pathway. Anti-CCL20 may have the potential for therapeutic translation, targeting on the immunopathogenesis of pulmonary sarcoidosis.

Identification of key regulators in Sarcoidosis through multidimensional systems biological approach

Sarcoidosis is a multi-organ disorder where immunology, genetic and environmental factors play a key role in causing Sarcoidosis, but its molecular mechanism remains unclear. Identification of its genetics profiling that regulates the Sarcoidosis network will be one of the main challenges to understand its aetiology. We have identified differentially expressed genes (DEGs) by analyzing the gene expression profiling of Sarcoidosis and compared it with healthy control. Gene set enrichment analysis showed that these DEGs were mainly enriched in the inflammatory response, immune system, and pathways in cancer. Sarcoidosis protein interaction network was constructed by a total of 877 DEGs (up-down) and calculated its network topological properties, which follow hierarchical scale-free fractal nature up to six levels of the organization. We identified a large number of leading hubs that contain six key regulators (KRs) including ICOS, CTLA4, FLT3LG, CD33, GPR29 and ITGA4 are deeply rooted in the network from top to bottom, considering a backbone of the network. We identified the transcriptional factors (TFs) which are closely interacted with KRs. These genes and their TFs regulating the Sarcoidosis network are expected to be the main target for the therapeutic approaches and potential biomarkers. However, experimental validations of KRs needed to confirm their efficacy.

Transcriptomics of bronchoalveolar lavage cells identifies new molecular endotypes of sarcoidosis

BACKGROUND

Sarcoidosis is a multisystem granulomatous disease of unknown origin with a variable and often unpredictable course and pattern of organ involvement. In this study we sought to identify specific bronchoalveolar lavage (BAL) cell gene expression patterns indicative of distinct disease phenotypic traits.

METHODS

RNA sequencing by Ion Torrent Proton was performed on BAL cells obtained from 215 well-characterised patients with pulmonary sarcoidosis enrolled in the multicentre Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study. Weighted gene co-expression network analysis and nonparametric statistics were used to analyse genome-wide BAL transcriptome. Validation of results was performed using a microarray expression dataset of an independent sarcoidosis cohort (Freiburg, Germany; n=50).

RESULTS

Our supervised analysis found associations between distinct transcriptional programmes and major pulmonary phenotypic manifestations of sarcoidosis including T-helper type 1 (Th1) and Th17 pathways associated with hilar lymphadenopathy, transforming growth factor-β1 (TGFB1) and mechanistic target of rapamycin (MTOR) signalling with parenchymal involvement, and interleukin (IL)-7 and IL-2 with airway involvement. Our unsupervised analysis revealed gene modules that uncovered four potential sarcoidosis endotypes including hilar lymphadenopathy with increased acute T-cell immune response; extraocular organ involvement with PI3K activation pathways; chronic and multiorgan disease with increased immune response pathways; and multiorgan involvement, with increased IL-1 and IL-18 immune and inflammatory responses. We validated the occurrence of these endotypes using gene expression, pulmonary function tests and cell differentials from Freiburg.

CONCLUSION

Taken together, our results identify BAL gene expression programmes that characterise major pulmonary sarcoidosis phenotypes and suggest the presence of distinct disease molecular endotypes.

CCR6-CCL20 axis as a therapeutic target for autoimmune diseases

Chemokine receptor CCR6 is expressed on various cells such as B cells, immature dendritic cells, innate lymphoid cells (ILCs), regulatory CD4 T cells, and Th17 cells. CCL20 is the only known high-affinity ligand that binds to CCR6 and drives CCR6⁺ cells' migration in tissues. CCL20 is mainly produced by epithelial cells, and its expression is increased by several folds under inflammatory conditions. Genome-wide association studies (GWAS) in patients with inflammatory bowel disease (IBD), psoriasis (PS), rheumatoid arthritis (RA), and multiple sclerosis (MS) showed a very strong correlation between the expression of CCR6 and disease severity. It has been shown that disruption of CCR6-CCL20 interaction by using antibodies or antagonists prevents the migration of CCR6 expressing immune cells at the site of inflammation and reduces the severity of the disease. This review discussed the importance of the CCR6-CCL20 axis in IBD, PS, RA, and MS, and recent advances in targeting the CCR6-CCL20 in controlling these autoimmune diseases.

Interleukin-26 activates macrophages and facilitates killing of Mycobacterium tuberculosis

Tuberculosis-causing Mycobacterium tuberculosis (Mtb) is transmitted via airborne droplets followed by a primary infection of macrophages and dendritic cells. During the activation of host defence mechanisms also neutrophils and T helper 1 (T_H1) and T_H17 cells are recruited to the site of infection. The T_H17 cell-derived interleukin (IL)-17 in turn induces the cathelicidin LL37 which shows direct antimycobacterial effects. Here, we investigated the role of IL-26, a T_H1- and T_H17-associated cytokine that exhibits antimicrobial activity. We found that both IL-26 mRNA and protein are strongly increased in tuberculous lymph nodes. Furthermore, IL-26 is able to directly kill Mtb and decrease the infection rate in macrophages. Binding of IL-26 to lipoarabinomannan might be one important mechanism in extracellular killing of Mtb. Macrophages and dendritic cells respond to IL-26 with secretion of tumor necrosis factor (TNF)-α and chemokines such as CCL20, CXCL2 and CXCL8. In dendritic cells but not in macrophages cytokine induction by IL-26 is partly mediated via Toll like receptor (TLR) 2. Taken together, IL-26 strengthens the defense against Mtb in two ways: firstly, directly due to its antimycobacterial properties and secondly indirectly by activating innate immune mechanisms.

Evaluation of Myocardial Gene Expression Profiling for Superior Diagnosis of Idiopathic Giant-Cell Myocarditis and Clinical Feasibility in a Large Cohort of Patients with Acute Cardiac Decompensation

Aims: The diagnostic approach to idiopathic giant-cell myocarditis (IGCM) is based on identifying various patterns of inflammatory cell infiltration and multinucleated giant cells (GCs) in histologic sections taken from endomyocardial biopsies (EMBs). The sampling error for detecting focally located GCs by histopathology is high, however. The aim of this study was to demonstrate the feasibility of gene profiling as a new diagnostic method in clinical practice, namely in a large cohort of patients suffering from acute cardiac decompensation. Methods and Results: In this retrospective multicenter study, EMBs taken from n = 427 patients with clinically acute cardiac decompensation and suspected acute myocarditis were screened (mean age: 47.03 ± 15.69 years). In each patient, the EMBs were analyzed on the basis of histology, immunohistology, molecular virology, and gene-expression profiling. Out of the total of n = 427 patient samples examined, GCs could be detected in 26 cases (6.1%) by histology. An established myocardial gene profile consisting of 27 genes was revealed; this was narrowed down to a specified profile of five genes (CPT1, CCL20, CCR5, CCR6, TLR8) which serve to identify histologically proven IGCM with high specificity in 25 of the 26 patients (96.2%). Once this newly established profiling approach was applied to the remaining patient samples, an additional n = 31 patients (7.3%) could be identified as having IGCM without any histologic proof of myocardial GCs. In a subgroup analysis, patients diagnosed with IGCM using this gene profiling respond in a similar fashion to immunosuppressive therapy as patients diagnosed with IGCM by conventional histology alone. Conclusions: Myocardial gene-expression profiling is a promising new method in clinical practice, one which can predict IGCM even in the absence of any direct histologic proof of GCs in EMB sections. Gene profiling is of great clinical relevance in terms of (a) overcoming the sampling error associated with purely histologic examinations and (b) monitoring the effectiveness of therapy.

IL18 signaling promotes homing of mature Tregs into the thymus

Foxp3+ regulatory T cells (Tregs) are potent suppressor cells, essential for the maintenance of immune homeostasis. Most Tregs develop in the thymus and are then released into the immune periphery. However, some Tregs populate the thymus and constitute a major subset of yet poorly understood cells. Here we describe a subset of thymus recirculating IL18R+ Tregs with molecular characteristics highly reminiscent of tissue-resident effector Tregs. Moreover, we show that IL18R+ Tregs are endowed with higher capacity to populate the thymus than their IL18R- or IL18R-/- counterparts, highlighting the key role of IL18R in this process. Finally, we demonstrate that IL18 signaling is critical for the induction of the key thymus-homing chemokine receptor - CCR6 on Tregs. Collectively, this study provides a detailed characterization of the mature Treg subsets in the mouse thymus and identifies a key role of IL18 signaling in controlling the CCR6-CCL20-dependent migration of Tregs into the thymus.

Activation of the interleukin-23/interleukin-17 signalling pathway in autoinflammatory and autoimmune uveitis

Uveitis is a group of diseases characterized by intraocular inflammation, of which some are driven by autoinflammatory or autoimmune responses, such as Vogt-Koyanagi-Harada disease, Behçet's disease, uveitis associated with spondyloarthritis, ocular sarcoidosis, sympathetic ophthalmia and birdshot chorioretinopathy. These entities have various clinical forms, but genetic and biomarker data suggest that they share a common molecular basis, activation of the Interleukin (IL)-23/IL-17 pathway. Multiple factors including genetic predisposition, various cytokine imbalances, infectious agents and gut alterations are found to trigger an aberrant response of this pathway. The enhanced activity of the IL-23/IL-17 pathway is committed to the expansion and pathogenicity of Th17 cells. Evidence from animal models demonstrates that the development of pathogenic Th17 cells is responsible for the induction of experimental autoimmune uveitis. Further findings indicate that retinal pigment epithelium (RPE) cells may be a target of IL-17. IL-17 triggers downstream inflammatory cascades and causes dysfunction of RPE cells, which may affect retinal barrier function and thereby promote intraocular inflammation. Currently, several emerging drugs blocking the IL-23/IL-17 pathway have been assessed for the treatment of uveitis in pilot studies. The purpose of this is to summarize updated biological knowledge and preliminary clinical data, providing the rationale for further development and evaluation of novel drugs targeting the IL-23/IL-17 pathway in autoinflammatory and autoimmune uveitis. Future studies may focus on translational medicine targeting the IL-23/IL-17 pathway for the improvement of diagnosis and treatment of uveitis. In conclusion, activation of the IL-23/IL-17 pathway is a critical biological event and can be an important target for the treatment of autoinflammatory and autoimmune uveitis.

Sarcoidosis and the mTOR, Rac1, and Autophagy Triad

Sarcoidosis is an enigmatic multisystem disease characterized by the development and accumulation of granulomas: a compact collection of macrophages that have differentiated into epithelioid cells and which are associated with T helper (Th)1 and Th17 cells. Although no single causative factor has been shown to underlie sarcoidosis in humans, its etiology has been related to microbial, environmental, and genetic factors. We examine how these factors play a role in sarcoidosis pathogenesis. Specifically, we propose that dysfunction of mTOR, Rac1, and autophagy-related pathways not only hampers pathogen or nonorganic particle clearance but also participates in T cell and macrophage dysfunction, driving granuloma formation. This concept opens new avenues for potentially treating sarcoidosis and may serve as a blueprint for other granulomatous disorders.

Using evasins to target the chemokine network in inflammation

Inflammation, is driven by a network comprising cytokines, chemokines, their target receptors and leukocytes, and is a major pathologic mechanism that adversely affects organ function in diverse human diseases. Despite being supported by substantial target validation, no successful anti-chemokine therapeutic to treat inflammatory disease has yet been developed. This is in part because of the robustness of the chemokine network, which emerges from a large total chemokine load in disease, promiscuous expression of receptors on leukocytes, promiscuous and synergistic interactions between chemokines and receptors, and feedforward loops created by secretion of chemokines by leukocytes themselves. Many parasites, including viruses, helminths and ticks, evade the chemokine network by producing proteins that bind promiscuously to chemokines or their receptors. Evasins - three small glycoproteins identified in the saliva of the brown dog tick - bind multiple chemokines, and are active in several animal models of inflammatory disease. Over 50 evasin homologs have recently been identified from diverse tick species. Characterization of the chemokine binding patterns of evasins show that several have anti-chemokine activities that extend substantially beyond those previously described. These studies indicate that evasins function at the site of the tick bite by reducing total chemokine load. This not only reduces chemokine signaling to receptors, but also interrupts feedforward loops, thus disabling the chemokine network. Taking the lead from nature, a goal for the development of new anti-chemokine therapeutics would be to reduce the total chemokine load in disease. This could be achieved by administering appropriate evasin combinations or by smaller peptides that mimic evasin action.

CCL20-CCR6 axis modulated traumatic brain injury-induced visual pathologies

BACKGROUND

Traumatic brain injury (TBI) is a major cause of death and disability in the USA and the world; it constitutes 30% of injury-related deaths (Taylor et al., MMWR Surveill Summ 66:1-16, 2017). Contact sports athletes often experience repetitive TBI (rTBI), which exerts a cumulative effect later in life. Visual impairment is a common after-effect of TBI. Previously, we have shown that C-C chemokine 20 (CCL20) plays a critical role in neurodegeneration and inflammation following TBI (Das et al., J Neuroinflammation 8:148, 2011). C-C chemokine receptor 6 (CCR6) is the only receptor that CCL20 interacts with. The objective of the present study was to investigate the role of CCL20-CCR6 axis in mediating rTBI-induced visual dysfunction (TVD).

METHODS

Wild type (WT) or CCR6 knock out (CCR6-/-) mice were subjected to closed head rTBI. Pioglitazone (PG) is a peroxisome proliferator-activated receptor γ (PPARγ) agonist which downregulates CCL20 production. Subsets of WT mice were treated with PG following final rTBI. A subset of mice was also treated with anti-CCL20 antibody to neutralize the CCL20 produced after rTBI. Histopathological assessments were performed to show cerebral pathologies, retinal pathologies, and inflammatory changes induced by rTBI.

RESULTS

rTBI induced cerebral neurodegeneration, retinal degeneration, microgliosis, astrogliosis, and CCL20 expression. CCR6-/- mice showed reduced retinal degeneration, microgliosis, and inflammation. Treatment with CCL20 neutralization antibody or PG showed reduced CCL20 expression along with reduced retinal degeneration and inflammation. rTBI-induced GFAP-positive glial activation in the optic nerve was not affected by knocking out CCR6.

CONCLUSION

The present data indicate that rTBI-induced retinal pathology is mediated at least in part by CCL20 in a CCR6-dependent manner.

Role of imbalance between Th17 and regulatory T-cells in sarcoidosis

PURPOSE OF REVIEW

A relatively new class of CD4 expressing T cells that also express and release interleukin-17 (Th17 cells) is gaining attention based on their capacity to regulate inflammatory responses in a spectrum of chronic autoimmune diseases. The purpose of this review is to consider recent studies relating to the critical role played by Th17 cells in the pathogenesis of sarcoidosis.

RECENT FINDINGS

Th17 cells are unique in their capacity to adapt to local molecular cues to variably promote or suppress inflammation. On the basis of knowledge established originally in the context of autoimmune disorders, recent investigations indicate that Th17 cells are instrumental in all stages of granuloma evolution, including granuloma formation, maintenance and resolution. Recent research shed light on the mechanisms regulating Th17 cell plasticity and the implications for sarcoidosis disease progression, such as the mechanisms by which regulatory T cells (Tregs) promote resolution of Th17-mediated inflammation.

SUMMARY

The balance between Th17 cells and Tregs in sarcoidosis patients has important implications for clinicians and clinical researchers seeking more reliable prognostic markers and more targeted therapeutic agents.

Pleiotropic Immune Functions of Chemokine Receptor 6 in Health and Disease

C-C chemoattractant cytokine (chemokine) receptor 6 (CCR6) and its exclusive binding molecule CCL20 is an extremely important chemokine receptor-ligand pair which controls cell migration and immune induction during inflammatory disease. Not many scientific studies have been undertaken to study its immune mechanisms in detail, but its unique contribution to steady state cell chemotaxis in upholding immune tolerance and regulating immune homeostasis during inflammation is evident in multiple systems in the human body, including skin, liver, lung, kidney, brain, eye, joints, gonads and the gut. The role of CCR6 is constitutively expressed as a series of much debilitating severe inflammatory and autoimmune diseases, Human Immunodeficiency Virus (HIV) and cancer metastasis. CD4⁺ T cells, the central organizers of adaptive immunity, are stringently mobilized by the CCR6/CCL20 axis also induced by cytokines and a host of other factors in a carefully executed immune modulation scenario, to bring about a delicate balance between inflammation inducing T_H17 cells and regulatory T_reg cells. Although the exact immune regulatory role is not elucidated as yet, the CCR6/CCL20 axis is implicated as a front runner which determines the polarization of T_H17 and regulatory T_reg cells, upon which depends the resolution or progression of many debilitating disorders. This review therefore aims at emphasizing the pleiotropic significance of the chemokines CCR6 and CCL20 in immunologic function in multiple organ systems, thereby hoping to accentuate its value in future therapeutic modalities.

Increased T-helper 17.1 cells in sarcoidosis mediastinal lymph nodes

The lung-draining mediastinal lymph nodes (MLNs) are currently widely used to diagnose sarcoidosis. We previously reported that T-helper (Th) 17.1 cells are responsible for the exaggerated interferon-γ production in sarcoidosis lungs. In this study, we aimed to investigate 1) whether Th17.1 cells are also increased in the MLNs of sarcoidosis patients and 2) whether frequencies of the Th17.1 cells at diagnosis may correlate with disease progression.

MLN cells from treatment-naive pulmonary sarcoidosis patients (n=17) and healthy controls (n=22) and peripheral blood mononuclear cells (n=34) and bronchoalveolar lavage fluid (BALF) (n=36) from sarcoidosis patients were examined for CD4+ T-cell subset proportions using flow cytometry.

Higher proportions of Th17.1 cells were detected in sarcoidosis MLNs than in control MLNs. Higher Th17.1 cell proportions were found in sarcoidosis BALF compared with MLNs and peripheral blood. Furthermore, BALF Th17.1 cell proportions were significantly higher in patients developing chronic disease than in patients undergoing resolution within 2 years of clinical follow-up.

These data suggest that Th17.1 cell proportions in pulmonary sarcoidosis can be evaluated as a diagnostic and/or prognostic marker in clinical practice and could serve as a new therapeutic target.

IFN-γ-Producing T-Helper 17.1 Cells Are Increased in Sarcoidosis and Are More Prevalent than T-Helper Type 1 Cells

RATIONALE

Pulmonary sarcoidosis is classically defined by T-helper (Th) cell type 1 inflammation (e.g., IFN-γ production by CD4(+) effector T cells). Recently, IL-17A-secreting cells have been found in lung lavage, invoking Th17 immunity in sarcoidosis. Studies also identified IL-17A-secreting cells that expressed IFN-γ, but their abundance as a percentage of total CD4(+) cells was either low or undetermined.

OBJECTIVES

Based on evidence that Th17 cells can be polarized to Th17.1 cells to produce only IFN-γ, our goal was to determine whether Th17.1 cells are a prominent source of IFN-γ in sarcoidosis.

METHODS

We developed a single-cell approach to define and isolate major Th-cell subsets using combinations of chemokine receptors and fluorescence-activated cell sorting. We subsequently confirmed the accuracy of subset enrichment by measuring cytokine production.

MEASUREMENTS AND MAIN RESULTS

Discrimination between Th17 and Th17.1 cells revealed very high percentages of Th17.1 cells in lung lavage in sarcoidosis compared with controls in two separate cohorts. No differences in Th17 or Th1 lavage cells were found compared with controls. Lung lavage Th17.1-cell percentages were also higher than Th1-cell percentages, and approximately 60% of Th17.1-enriched cells produced only IFN-γ.

CONCLUSIONS

Combined use of surface markers and functional assays to study CD4(+) T cells in sarcoidosis revealed a marked expansion of Th17.1 cells that only produce IFN-γ. These results suggest that Th17.1 cells could be misclassified as Th1 cells and may be the predominant producer of IFN-γ in pulmonary sarcoidosis, challenging the Th1 paradigm of pathogenesis.

Correlation Network Analysis Reveals Relationships between MicroRNAs, Transcription Factor T-bet, and Deregulated Cytokine/Chemokine-Receptor Network in Pulmonary Sarcoidosis

Sarcoidosis is an inflammatory granulomatous disease with unknown etiology driven by cytokines and chemokines. There is limited information regarding the regulation of cytokine/chemokine-receptor network in bronchoalveolar lavage (BAL) cells in pulmonary sarcoidosis, suggesting contribution of miRNAs and transcription factors. We therefore investigated gene expression of 25 inflammation-related miRNAs, 27 cytokines/chemokines/receptors, and a Th1-transcription factor T-bet in unseparated BAL cells obtained from 48 sarcoidosis patients and 14 control subjects using quantitative RT-PCR. We then examined both miRNA-mRNA expressions to enrich relevant relationships. This first study on miRNAs in sarcoid BAL cells detected deregulation of miR-146a, miR-150, miR-202, miR-204, and miR-222 expression comparing to controls. Subanalysis revealed higher number of miR-155, let-7c transcripts in progressing (n = 20) comparing to regressing (n = 28) disease as assessed by 2-year follow-up. Correlation network analysis revealed relationships between microRNAs, transcription factor T-bet, and deregulated cytokine/chemokine-receptor network in sarcoid BAL cells. Furthermore, T-bet showed more pronounced regulatory capability to sarcoidosis-associated cytokines/chemokines/receptors than miRNAs, which may function rather as “fine-tuners” of cytokine/chemokine expression. Our correlation network study implies contribution of both microRNAs and Th1-transcription factor T-bet to the regulation of cytokine/chemokine-receptor network in BAL cells in sarcoidosis. Functional studies are needed to confirm biological relevance of the obtained relationships.

TL1A/DR3 axis involvement in the inflammatory cytokine network during pulmonary sarcoidosis

Background

TNF-like ligand 1A (TL1A), a recently recognized member of the TNF superfamily, and its death domain receptor 3 (DR3), firstly identified for their relevant role in T lymphocyte homeostasis, are now well-known mediators of several immune-inflammatory diseases, ranging from rheumatoid arthritis to inflammatory bowel diseases to psoriasis, whereas no data are available on their involvement in sarcoidosis, a multisystemic granulomatous disease where a deregulated T helper (Th)1/Th17 response takes place.

Methods

In this study, by flow cytometry, real-time PCR, confocal microscopy and immunohistochemistry analyses, TL1A and DR3 were investigated in the pulmonary cells and the peripheral blood of 43 patients affected by sarcoidosis in different phases of the disease (29 patients with active sarcoidosis, 14 with the inactive form) and in 8 control subjects.

Results

Our results demonstrated a significant higher expression, both at protein and mRNA levels, of TL1A and DR3 in pulmonary T cells and alveolar macrophages of patients with active sarcoidosis as compared to patients with the inactive form of the disease and to controls. In patients with sarcoidosis TL1A was strongly more expressed in the lung than the blood, i.e., at the site of the involved organ. Additionally, zymography assays showed that TL1A is able to increase the production of matrix metalloproteinase 9 by sarcoid alveolar macrophages characterized, in patients with the active form of the disease, by reduced mRNA levels of the tissue inhibitor of metalloproteinase (TIMP)-1.

Conclusions

These data suggest that TL1A/DR3 interactions are part of the extended and complex immune-inflammatory network that characterizes sarcoidosis during its active phase and may contribute to the pathogenesis and to the progression of the disease.

Granuloma formation in pulmonary sarcoidosis

Sarcoidosis is a granulomatous disorder of unknown cause, affecting multiple organs, but mainly the lungs. The exact order of immunological events remains obscure. Reviewing current literature, combined with careful clinical observations, we propose a model for granuloma formation in pulmonary sarcoidosis. A tight collaboration between macrophages, dendritic cells, and lymphocyte subsets, initiates the first steps toward granuloma formation, orchestrated by cytokines and chemokines. In a substantial part of pulmonary sarcoidosis patients, granuloma formation becomes an on-going process, leading to debilitating disease, and sometimes death. The immunological response, determining granuloma sustainment is not well understood. An impaired immunosuppressive function of regulatory T cells has been suggested to contribute to the exaggerated response. Interestingly, therapeutical agents commonly used in sarcoidosis, such as glucocorticosteroids and anti-TNF agents, interfere with granuloma integrity and restore the immune homeostasis in autoimmune disorders. Increasing insight into their mechanisms of action may contribute to the search for new therapeutical targets in pulmonary sarcoidosis.

The expression of chemokine receptors CCR6, CXCR2 and CXCR4 is not organ-specific for distant metastasis in colorectal cancer: a comparative study

AIMS

The liver and lung are the organs most commonly affected by metastasis in colorectal cancer (CRC), and the interaction of chemokines and chemokine receptors (CKRs) plays an important role in the metastatic process. The aim of this study was to investigate the organ specificity of CKRs in CRC distant metastasis.

METHODS AND RESULTS

Surgical specimens of primary tumours from 46 patients with metachronous distant metastases were retrieved retrospectively (20 lung metastases; 26 liver metastases). As a control, the records of 29 patients without distant metastases were randomly retrieved from our database, and their specimens were reassessed. The expression rates of CKRs, including CCR6, CXCR2, and CXCR4, were determined by immunohistochemistry, and were compared among the groups. The expression rates of CCR6 and CXCR2 were both significantly higher in the metastasis group than in the non-metastasis group (P < 0.05), but there was no statistical difference between the lung metastasis and liver metastasis subgroups. The expression of CXCR4 was not significantly different between the metastasis and non-metastasis groups. Multivariable analysis suggested that preoperative serum carcinoembryonic antigen level, CCR6 and CXCR2 were independent factors associated with distant metastasis.

CONCLUSIONS

The expression of CCR6 and CXCR2 in CRC could predict metachronous distant metastasis, but they have no organ specificity for metastasis.

Immunotargeting and eradication of orthotopic melanoma using a chemokine-enhanced DNA vaccine

DNA vaccines are attractive candidates for tumor immunotherapy. However, the potential of DNA vaccines in treating established malignant lesions has yet to be demonstrated. Here we demonstrate that transient alteration of either intratumoral or intradermal (ID) chemotactic gradients provide a favorable milieu for DNA vaccine-mediated activation of tumor-specific immune response in both prophylactic and therapeutic settings. Specifically, we show that priming of established B16 ID melanoma lesions via forced intratumoral expression of CCL21 boosted DNA vaccination-dependent systemic cytotoxic immune response leading to the regression of tumor nodules. In this setting, application of CCL20 was not effective likely due to the engagement of the regulatory T cells. However, priming of the skin at DNA vaccine administration sites outside the tumor bed with both CCL20 and CCL21 chemokines along with structural modifications of the DNA vaccine significantly improved vaccine efficacy. This optimized ID vaccination regimen led to the inhibition of distant established melanomas and prolonged tumor-free survival of mice observed in 60% of vaccinated animals with complete tumor remission in 30%. These effects were mediated by extranodal priming and activation of T cells at vaccine administration sites and progressive accumulation of systemic antigen-specific cytotoxic T cells (CTLs) on successive vaccinations. These results underscore the potential of chemokine-enhanced DNA vaccination to mount therapeutic immune response against established tumors.

BTNL2 gene polymorphism associations with susceptibility and phenotype expression in sarcoidosis

A functional polymorphism within butyrophilin-like 2 (BTNL2) gene has been described as a potential risk factor for sarcoidosis. The association between chronicity and the rs2076530 SNP A allele has also been reported. This study evaluates the BTNL2 rs2076530 G/A allele associations with sarcoidosis susceptibility and disease evolution in a Portuguese cohort of patients. A case-control study of 151 patients and 150 controls was performed. Allele frequencies were compared with Chi-square test in a univariate analysis and with logistic regression in a multivariate analysis. BTNL2 rs206530 A allele frequencies were significantly higher in sarcoidosis with no linkage disequilibrium with HLA-DRB1 alleles, except in the subgroup of patients with Löfgren syndrome where the determinant allele was HLA-DRB1*03. The A allele was also increased in those with isolated thoracic disease, with no differences regarding radiological stages or disease evolution. HLA-DRB1*03, besides the association with Löfgren syndrome was significantly related with disease resolution. Our data confirms the association of BTNL2 rs2076530 A allele with sarcoidosis susceptibility in a Portuguese population. We found independent genetic risk factors in clinically distinct disease phenotypes: BTNL2 rs2076530 A allele in patients without Löfgren syndrome or with isolated thoracic disease, and HLA-DRB1*03 in Löfgren syndrome or disease resolution.

Reduced T(H)1/T(H)17 CD4 T-cell numbers are associated with impaired purified protein derivative-specific cytokine responses in patients with HIV-1 infection

BACKGROUND

In HIV-1-infected patients impaired IFN-γ responses to purified protein derivative (PPD) are associated with an increased risk of active tuberculosis. Tuberculosis antigen-specific cells are found in the T(H)1/T(H)17 subset of CD4 T cells, which support HIV-1 replication. Selective loss of T(H)1/T(H)17 cells in patients with HIV-1 infection might contribute to reduced tuberculosis-induced immune responses and an increased susceptibility to active tuberculosis.

OBJECTIVES

We sought to investigate the association between T(H)1/T(H)17 cells and PPD-specific cytokine responses in HIV-1-infected patients.

METHODS

A cross-sectional study was performed on healthy control subjects, HIV-1-infected patients receiving successful antiretroviral therapy (ART(+)), and ART-naive HIV-1-infected patients (ART(-)). All patients studied had evidence of BCG vaccination. Four discrete CD4 T-cell subsets were assessed by flow cytometry: T(H)1/T(H)17 cells (CXCR3(+)CCR6(+)CCR4(-)), T(H)1 cells (CXCR3(+)CCR6(-)CCR4(-)), T(H)17 cells (CXCR3(-)CCR6(+)CCR4(+)), and T(H)2 cells (CXCR3(-)CCR6(-)CCR4(+)). IFN-γ and IL-2 PPD-specific cytokine responses were assessed in PBMCs by using the enzyme-linked immunospot assay.

RESULTS

Twenty-nine healthy control subjects, 34 ART(+) patients, and 26 ART(-) patients were recruited. The number and frequency of T(H)1/T(H)17 and T(H)1/T(H)17 CCR5(+) CD4 T cells were significantly reduced in HIV-1-infected patients. IFN-γ and IL-2 PPD responses were significantly lower in ART(-) patients and were partially reconstituted with successful ART. Loss of T(H)1/T(H)17 CCR5(+) cells was associated with reduced IFN-γ and IL-2 PPD responses.

CONCLUSIONS

Selective loss of T(H)1/T(H)17 cells may be a risk factor for the development of active tuberculosis in patients with HIV-1 infection and might be a useful biomarker in the development of tuberculosis vaccines.

Cysteine-cysteinyl chemokine receptor 6 mediates invariant natural killer T cell airway recruitment and innate stage resistance during mycobacterial infection

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.

No evidence of altered alveolar macrophage polarization, but reduced expression of TLR2, in bronchoalveolar lavage cells in sarcoidosis

Background

Sarcoidosis is a granulomatous inflammatory disease, possibly of infectious aetiology. We aimed to investigate whether the degree of functional polarization of alveolar macrophages (AMs), or Toll-like receptor (TLR) expression, is associated with sarcoidosis or with distinct clinical manifestations of this disease.

Methods

Total BAL cells (cultured four or 24 h in medium, or stimulated 24 h with LPS) from 14 patients and six healthy subjects, sorted AMs from 22 patients (Löfgren's syndrome n = 11) and 11 healthy subjects, and sorted CD4+ T cells from 26 patients (Löfgren's syndrome n = 13) and seven healthy subjects, were included. Using real-time PCR, the relative gene expression of IL-10, IL-12p35, IL-12p40, IL-23p19, CCR2, CCR7, iNOS, CXCL10, CXCL11, CXCL16, CCL18, CCL20, CD80, and CD86, and innate immune receptors TLR2, TLR4, and TLR9, was quantified in sorted AMs, and for selected genes in total BAL cells, while IL-17A was quantified in T cells.

Results

We did not find evidence of a difference with regard to alveolar macrophage M1/M2 polarization between sarcoidosis patients and healthy controls. TLR2 gene expression was significantly lower in sorted AMs from patients, particular in Löfgren's patients. CCL18 gene expression in AMs was significantly higher in patients compared to controls. Additionally, the IL-17A expression was lower in Löfgren's patients' CD4+ T cells.

Conclusions

Overall, there was no evidence for alveolar macrophage polarization in sarcoidosis. However, there was a reduced TLR2 mRNA expression in patients with Löfgren's syndrome, which may be of relevance for macrophage interactions with a postulated sarcoidosis pathogen, and for the characteristics of the ensuing T cell response.

Antimycobacterial immune responses in patients with pulmonary sarcoidosis

INTRODUCTION

Sarcoidosis is a multisystem granulomatous disease of unknown origin. Pathogenetic involvement of Mycobacterium tuberculosis has frequently been discussed in the aetiology of sarcoidosis; however, studies still remain contradictory.

OBJECTIVE

We addressed the question of mycobacterial involvement in the pathogenesis of sarcoidosis by analysing cellular immune responses to mycobacterial antigens.

METHODS

We examined the interferon (IFN)-gamma production by enzyme-linked immunospot in response to purified protein derivate (PPD) mycobacterial-specific antigen early secretory antigenic target (ESAT)-6 and culture filtrate protein (CFP)-10 by peripheral blood mononuclear cells (PBMCs) and bronchoalveolar-lavage mononuclear cells (BALMCs) of patients with pulmonary sarcoidosis, smear-negative tuberculosis and controls.

RESULTS

Release of IFN-gamma in response to ex vivo contact with PPD, ESAT-6 or CFP-10 by BALMC and PBMC were comparable among patients with sarcoidosis and controls (PBMC P = 0.2326; BALMC P = 0.1767) and were less frequently observed in both groups compared to patients with tuberculosis (BALMC P < 0.05; PBMC P < 0.0001). Within PBMC, the immunophenotype of sarcoidosis patients differed from that of patients with tuberculosis, as well as from that of controls, while within BALMC it resembled that of patients with tuberculosis.

CONCLUSION

In contrast to patients with tuberculosis, the frequency of mycobacteria-specific local and systemic immune responses is not elevated in patients with sarcoidosis when compared to controls. The immunophenotype represents the local resemblance of the granulomatous reaction underlying tuberculosis and sarcoidosis while showing systemical difference. These observations do not support a role of an infection with M. tuberculosis in the pathogenesis of sarcoidosis.

Chemokine receptors in a regulation of interstitial lung fibrosis and inflammation

Sarcoidosis and extrinsic allergic alveolitis (EAA) are granulomatous lung diseases with predominantly Th1 immune response. In this prospective study, the authors analyzed the expression of chemokine receptors CXCR2, CXCR3, and CCR3 on bronchoalveolar lavage fluid (BALF) CD4 T cells of patients either with EAA or sarcoidosis. The authors investigated the correlation of chemokine receptors expression, lymphocyte and neutrophil counts in BALF, and high-resolution tomography (HRCT) pattern. Thirteen sarcoidosis and 6 EAA patients were enrolled in the study. The expression of chemokine receptors on BALF CD4 T cells were analyzed by flow cytometry. HRCT scoring system according to Kazerooni was used for evaluation of the disease extent. The authors have found positive correlation between BALF CD4 T-cell CXCR3 expression and HRCT alveolar score in EAA patients (P <. 01). CXCR2 expression on BALF CD4 T cells and interstitial HRCT score did not show a correlation either in the EAA or the sarcoidosis group. Positive correlation between CCR3 expression on CD4+ T cells and HRCT interstitial score was proven in the EAA group (P <. 05). The authors conclude that Th2 predominant immune response may play an important role in chronic EAA pathogenesis. The role of chemokine receptors in the pathogenesis of EAA and sarcoidosis should be presumed and investigated.

Childhood sarcoidosis: A rare but fascinating disorder

Childhood sarcoidosis is a rare multisystemic granulomatous disorder of unknown etiology. In the pediatric series reported from the southeastern United States, sarcoidosis had a higher incidence among African Americans. Most reported childhood cases have occurred in patients aged 13-15 years. Macrophages bearing an increased expression of major histocompatibility class (MHC) II molecules most likely initiate the inflammatory response of sarcoidosis by presenting an unidentified antigen to CD4+ Th (helper-inducer) lymphocytes. A persistent, poorly degradable antigen driven cell-mediated immune response leads to a cytokine cascade, to granuloma formation, and eventually to fibrosis. Frequently observed immunologic features include depression of cutaneous delayed-type hypersensitivity and a heightened helper T cell type 1 (Th1) immune response at sites of disease. Circulating immune complexes, along with signs of B cell hyperactivity, may also be found. The clinical presentation can vary greatly depending upon the organs involved and age of the patient. Two distinct forms of sarcoidosis exist in children. Older children usually present with a multisystem disease similar to the adult manifestations, with frequent hilar lymphadenopathy and pulmonary infiltrations. Early-onset sarcoidosis is a unique form of the disease characterized by the triad of rash, uveitis, and arthritis in children presenting before four years of age. The diagnosis of sarcoidosis is confirmed by demonstrating a typical noncaseating granuloma on a biopsy specimen. Other granulmatous diseases should be reasonably excluded. The current therapy of choice for sarcoidosis in children with multisystem involvement is oral corticosteroids. Methotrexate given orally in low doses has been effective, safe and steroid sparing in some patients. Alternative immunosuppressive agents, such as azathioprine, cyclophosphamide, chlorambucil, and cyclosporine, have been tried in adult cases of sarcoidosis with questionable efficacy. The high toxicity profile of these agents, including an increased risk of lymphoproliferative disorders and carcinomas, has limited their use to patients with severe disease refractory to other agents. Successful steroid sparing treatment with mycophenolate mofetil was described in an adolescent with renal-limited sarcoidosis complicated by renal failure. Novel treatment strategies for sarcoidosis have been developed including the use of TNF-alpha inhibitors, such as infliximab. The long-term course and prognosis is not well established in childhood sarcoidosis, but it appears to be poorer in early-onset disease.

Genome-wide association defines more than 30 distinct susceptibility loci for Crohn's disease

Several risk factors for Crohn's disease have been identified in recent genome-wide association studies. To advance gene discovery further, we combined data from three studies on Crohn's disease (a total of 3,230 cases and 4,829 controls) and carried out replication in 3,664 independent cases with a mixture of population-based and family-based controls. The results strongly confirm 11 previously reported loci and provide genome-wide significant evidence for 21 additional loci, including the regions containing STAT3, JAK2, ICOSLG, CDKAL1 and ITLN1. The expanded molecular understanding of the basis of this disease offers promise for informed therapeutic development.