Interleukin 7 stimulates tumour necrosis factor alpha and Th1 cytokine production in joints of patients with rheumatoid arthritis

Upregulation of interferon-γ response genes in monocytes and T cells identified by single-cell transcriptomics in patients with anti-citrullinated peptide antibody-positive early rheumatoid arthritis

Introduction

Our aim was to investigate the insufficiently understood differences in the immune system between anti-citrullinated peptide antibody (ACPA)-positive (ACPA+) and ACPA-negative (ACPA-) early rheumatoid arthritis (eRA) patients.

Methods

We performed multiple cytokine assays using sera from drug-naïve ACPA+ and ACPA- eRA patients. Additionally, we conducted single-cell RNA sequencing of CD45+ cells from peripheral blood samples to analyze and compare the distribution and functional characteristics of the cell subsets based on the ACPA status.

Results

Serum concentrations of interferon-γ (IFN-γ) and interleukin (IL)-12 were higher in ACPA+ eRA than in ACPA- eRA. Single-cell transcriptome analysis of 37,318 cells identified 17 distinct cell types and revealed the expansion of IL1B+ proinflammatory monocytes, IL7R+ T cells, and CD8+ CCL4+ T cells in ACPA+ eRA. Furthermore, we observed an enrichment of IFN-γ response genes in nearly all monocytes and T cells of ACPA+ eRA subsets. Heightened interactions between IFN-γ and IFN-γ receptors were observed in ACPA+ eRA, particularly between monocytes and T cells. We examined IFITM2 and IFITM3 as potential key markers in ACPA+ eRA given their pronounced upregulation and association with the IFN response. Specifically, the expression of these genes was elevated in IL1B+ proinflammatory monocytes (likely M1 monocytes), correlating with serum IFN-γ levels.

Discussion

Compared to ACPA- eRA, ACPA+ eRA showed higher serum IFN-γ and IL-12 levels, upregulated IFN-γ response genes, and enhanced IFN-γ-driven monocyte-T cell interactions. These distinct immune features of the peripheral circulation in ACPA+ eRA suggest a role for type 1 helper T cell-related immunity in its pathogenesis.

Homeostatic signals, including IL-7 and self-MHC recognition, induce the development of peripheral helper T cells, which are enriched in the joints of rheumatoid arthritis

Objective

Dysregulated T cell homeostasis has long been implicated in the pathogenesis of rheumatoid arthritis (RA), in the joint of which peripheral helper T (Tph) cells accumulate and form ectopic lymphoid organs. We examined whether homeostatic signals are involved in the development of Tph cells.

Methods

Human peripheral blood mononuclear cells were cultured with IL-7, the critical cytokine for T cell homeostasis. Development of Tph-like cells was assessed by flow cytometry, gene expression, and functional analysis. Chemotaxis of the Tph-like cells to RA synovial fluid (RASF) and the effect of RASF on the development of Tph-like cells was examined.

Results

PD-1highCXCR5- Tph-like cells developed from human peripheral blood CD4 T cells after proliferation in response to IL-7. Signals from self-MHC recognition and CD28 co-stimulation were also involved. The IL-7-induced Tph-like (IL-7-Tph) cells produced CXCL13 and IL-21 and helped B cells produce IgG. Comprehensive gene expression analysis further supported the similarity with Tph cells in RA joint. IL-7-Tph cells exhibited chemotaxis toward synovial fluid from RA patients (RASF), and RASF promoted the development of IL-7-Tph cells, which were also induced from CD4 T cells residing in non-inflamed joints.

Conclusions

Our results demonstrate an antigen-nonspecific developmental pathway of Tph cells triggered by homeostatic signals and promoted by the local environment of RA, which accounts for the accumulation of Tph cells in inflamed joints.

Analysis of interleukin 7 and platelet-derived growth factor-BB mRNA expression as potential markers in erythema nodosum leprosum

Erythema nodosum leprosum (ENL) is an immunological complication of leprosy characterized by acute inflammation of the skin, nerves, and other organs. Identifying laboratory parameters is important for early diagnosis of leprosy reactions. Various cytokine biomarkers have been examined and only a few studies have reported on angiogenesis in leprosy. This study aims to understand the pathomechanism of ENL by examining IL-7 and platelet-derived growth factor (PDGF)-BB mRNA expression that can be the development and consideration of new effective therapies to prevent reactions, recurrences, and defects in leprosy. The study used a cross-sectional analytic design. Sampling was done by peripheral blood from the patient and measuring mRNA expression with specific primers RT-PCR. The expression of mRNA IL-7 and PDGF-BB was significantly different between multibasilar patients without reaction and with ENL reaction, where there was an increased expression in ENL patients. This could be used as the development of potential biomarkers in ENL and development of new therapeutic intervention pathways in ENL.

Changes in Inflammatory Cytokines in Responders and Non-Responders to TNFα Inhibitor and IL-17A Inhibitor: A Study Examining Psoriatic Arthritis Patients

This study aimed to examine the changes in biomarker levels in responders and non-responders to tumor necrosis factor alpha inhibitor (TNFi) and interleukin-17A inhibitor (IL-17Ai) in psoriatic arthritis (PsA) patients over a 4-month period after treatment initiation. A total of 68 PsA patients initiating either TNFi, IL-17Ai, or methotrexate treatment were included. Blood plasma and clinical outcome measures were collected adjacent to treatment initiation and after four months. A commercially available multiplex immunoassay was included to evaluate 54 biomarkers. Mean changes were used to evaluate change over time. A statistically significant decrease in pro-inflammatory cytokines IL-6 (log-transformed mean change -0.97, 95%CI -4.30; 2.37, [p = 0.032]) and an increase in anti-inflammatory IL-10 (0.38, 95%CI 1.74; 2.50 [p = 0.010]) were seen in TNFi responders. Meanwhile, a statistically significant increase in the target cytokine IL-17A was seen in both IL-17Ai responders (2.49, 95%CI -1.84; 6.85 [p = 0.031]) and non-responders (2.48, 95%CI -1.46; 6.41 [p = 0.001]). This study demonstrated differing changes in cytokine levels when comparing treatment responders and non-responders, highlighting the need to improve the understanding of the different immune response mechanisms explaining different responses to medical treatment in PsA patients.

Serum cytokines MCP-1 and GCS-F as potential biomarkers in pediatric inflammatory bowel disease

BACKGROUND

Inflammatory bowel diseases (IBDs) with the subtypes ulcerative colitis (UC) and Crohn disease (CD), are chronic autoimmune inflammatory disorders of the gastrointestinal tract. Cytokines are associated with the development and progression in pediatric IBD. We measured cytokine levels in pediatric IBD patients to assess their potential function as biomarkers in disease assessment.

METHOD

In this prospective cohort study, we enrolled 33 children with IBD. All patients were in stable remission for 3 months on enrollment. Patients who developed a relapse within six months after enrollment were classified as relapsers. Blood sampling was performed at enrolment and for relapsers in relapse and post-relapse. Serum concentrations of 14 cytokines, chemokines and growth factors (IL-1α, IL-1β, IL-6, IL-12p40, IP-10, TNF-α, IFN-γ, IL-10, IL-8, MIP-1α, MCP-1, MCP-3, G-CSF, GM-CSF) were measured simultaneously using multiplex bead-based sandwich immunoassay on Luminex 100 system.

RESULTS

MCP-1 was significantly higher in CD patients compared to UC patients at each disease stage: stable remission (P<0.048), unstable remission (P<0.013), relapse (P<0.026) and post-relapse (P<0.024). G-CSF was significantly increased in UC patients developing a relapse and in post-relapse stage compared to UC patients in remission (P<0.02 and p<0.03, respectively).

CONCLUSION

MCP-1 showed potential as a diagnostic biomarker in CD patients independent of disease activity as it was able to discriminate between subtypes of pediatric IBD. In UC patients, G-CSF was significantly elevated in relapsers indicating its use and role as a potential prognostic biomarker.

Toll-like receptors and IL-7 as potential biomarkers for immune-mediated necrotizing myopathies

We aimed to verify whether the immune system may represent a source of potential biomarkers for the stratification of immune-mediated necrotizing myopathies (IMNMs) subtypes. A group of 22 patients diagnosed with IMNM [7 with autoantibodies against signal recognition particle (SRP) and 15 against 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR)] and 12 controls were included. A significant preponderance of M1 macrophages was observed in both SRP+ and HMGCR+ muscle samples (p < 0.0001 in SRP+ and p = 0.0316 for HMGCR+ ), with higher values for SRP+ (p = 0.01). Despite the significant increase observed in the expression of TLR4 and all endosomal Toll-like receptors (TLRs) at protein level in IMNM muscle tissue, only TLR7 has been shown considerably upregulated compared to controls at transcript level (p = 0.0026), whereas TLR9 was even decreased (p = 0.0223). Within IMNM subgroups, TLR4 (p = 0.0116) mRNA was significantly increased in SRP+ compared to HMGCR+ patients. Within IMNM group, only IL-7 was differentially expressed between SRP+ and HMGCR+ patients, with higher values in SRP+ patients (p = 0.0468). Overall, innate immunity represents a key player in pathological mechanisms of IMNM. TLR4 and the inflammatory cytokine IL-7 represent potential immune biomarkers able to differentiate between SRP+ and HMGCR+ patients.

IL-7 Deficiency Exacerbates Atopic Dermatitis in NC/Nga Mice

Interleukin-7 (IL-7) plays a vital role in the homeostasis of CD4⁺ and CD8⁺ T cells. Although IL-7 has been implicated in T helper (Th)1- and Th17-mediated autoinflammatory diseases, its role in Th2-type allergic disorders, such as atopic dermatitis (AD), remains unclear. Thus, to elucidate the effects of IL-7 deficiency on AD development, we generated IL-7-deficient AD-prone mice by backcrossing IL-7 knockout (KO) B6 mice onto the NC/Nga (NC) mouse strain, a model for human AD. As expected, IL-7 KO NC mice displayed defective development of conventional CD4⁺ and CD8⁺ T cells compared with wild type (WT) NC mice. However, IL-7 KO NC mice presented with enhanced AD clinical scores, IgE hyperproduction, and increased epidermal thickness compared with WT NC mice. Moreover, IL-7 deficiency decreased Th1, Th17, and IFN-γ-producing CD8⁺ T cells but increased Th2 cells in the spleen of NC mice, indicating that a reduced Th1/Th2 ratio correlates with severity of AD pathogenesis. Furthermore, significantly more basophils and mast cells infiltrated the skin lesions of IL-7 KO NC mice. Taken together, our findings suggest that IL-7 could be a useful therapeutic target for treating Th2-mediated skin inflammations, such as AD.

Cytokine Signatures in Psoriatic Arthritis Patients Indicate Different Phenotypic Traits Comparing Responders and Non-Responders of IL-17A and TNFα Inhibitors

This study aimed to explore the dynamic interactions between 32 cytokines and biomarkers in Psoriatic Arthritis (PsA) patients to compare cytokine signatures of treatment responders and non-responders. Biomarkers were measured before and after four months of treatment in 39 PsA patients initiating either Tumor Necrosis Factor alpha inhibitor (TNFi) or Interleukin-17A inhibitor (IL-17Ai). Response to treatment was defined by the composite measure, Disease Activity in Psoriatic Arthritis (DAPSA). A two-component principal component analysis (PCA) was implemented to describe cytokine signatures comparing DAPSA50 responders and non-responders. The cytokine signature of TNFi responders was driven by the correlated cytokines interferon γ (IFNγ) and IL-6, additionally associated with IL-12/IL-23p40, TNFα, and CRP, while the cytokine signature of TNFi non-responders was driven by the correlated cytokines IL-15, IL-8, and IFNγ. IL-17Ai responders were characterized by contributions of strongly correlated Th17 inflammatory cytokines, IL-17A, IL-12/IL-23p40, IL-22 to the cytokine signature, whereas IL-17A and IL-12/IL-23p40 did not demonstrate significant contribution in IL-17Ai non-responders. Based on PCA results it was possible to differentiate DAPSA50 responders and non-responders to treatment, endorsing additional examination of cytokine interaction models in PsA patients and supporting further PsA patient immune stratification to improve individualized treatment of PsA patients.

In patients with primary Sjögren's syndrome innate-like MAIT cells display upregulated IL-7R, IFN-γ, and IL-21 expression and have increased proportions of CCR9 and CXCR5-expressing cells

Introduction

Mucosal-associated invariant T (MAIT) cells might play a role in B cell hyperactivity and local inflammation in primary Sjögren's syndrome (pSS), just like previously studied mucosa-associated CCR9+ and CXCR5+ T helper cells. Here, we investigated expression of CCR9, CXCR5, IL-18R and IL-7R on MAIT cells in pSS, and assessed the capacity of DMARDs to inhibit the activity of MAIT cells.

Methods

Circulating CD161+ and IL-18Rα+ TCRVα7.2+ MAIT cells from pSS patients and healthy controls (HC) were assessed using flow cytometry, and expression of CCR9, CXCR5, and IL-7R on MAIT cells was studied. Production of IFN-γ and IL-21 by MAIT cells was measured upon IL-7 stimulation in the presence of leflunomide (LEF) and hydroxychloroquine (HCQ).

Results

The numbers of CD161+ and IL-18Rα+ MAIT cells were decreased in pSS patients compared to HC. Relative increased percentages of CD4 MAIT cells in pSS patients caused significantly higher CD4/CD8 ratios in MAIT cells. The numbers of CCR9 and CXCR5-expressing MAIT cells were significantly higher in pSS patients. IL-7R expression was higher in CD8 MAIT cells as compared to all CD8 T cells, and changes in IL-7R expression correlated to several clinical parameters. The elevated production of IL-21 by MAIT cells was significantly inhibited by LEF/HCQ treatment.

Conclusion

Circulating CD161+ and IL-18Rα+ MAIT cell numbers are decreased in pSS patients. Given their enriched CCR9/CXCR5 expression this may facilitate migration to inflamed salivary glands known to overexpress CCL25/CXCL13. Given the pivotal role of IL-7 and IL-21 in inflammation in pSS this indicates a potential role for MAIT cells in driving pSS immunopathology.

Effect of Human Synovial Fluid From Osteoarthritis Patients and Healthy Individuals on Lymphatic Contractile Activity

The lymphatic system has been proposed to play a crucial role in preventing the development and progression of osteoarthritis (OA). As OA develops and progresses, inflammatory cytokines and degradation by-products of joint tissues build up in the synovial fluid (SF) providing a feedback system to exacerbate disease. The lymphatic system plays a critical role in resolving inflammation and maintaining overall joint homeostasis; however, there is some evidence that the lymphatics can become dysfunctional during OA. We hypothesized that the functional mechanics of lymphatic vessels (LVs) draining the joint could be directly compromised due to factors within SF derived from osteoarthritis patients (OASF). Here, we utilized OASF and SF derived from healthy (non-OA) individuals (healthy SF (HSF)) to investigate potential effects of SF entering the draining lymph on migration of lymphatic endothelial cells (LECs) in vitro, and lymphatic contractile activity of rat femoral LVs (RFLVs) ex vivo. Dilutions of both OASF and HSF containing serum resulted in a similar LEC migratory response to the physiologically endothelial basal medium-treated LECs (endothelial basal medium containing serum) in vitro. Ex vivo, OASF and HSF treatments were administered within the lumen of isolated LVs under controlled pressures. OASF treatment transiently enhanced the RFLVs tonic contractions while phasic contractions were significantly reduced after 1 h of treatment and complete ceased after overnight treatment. HSF treatment on the other hand displayed a gradual decrease in lymphatic contractile activity (both tonic and phasic contractions). The observed variations after SF treatments suggest that the pump function of lymphatic vessel draining the joint could be directly compromised in OA and thus might present a new therapeutic target.

Significance of IL-7 and IL-7R in RA and autoimmunity

While physiological levels of IL-7 are essential for T cell proliferation, survival and co-stimulation, its escalated concentration has been associated with autoimmune diseases such as Rheumatoid arthritis (RA). Expression of IL-7 and IL-7R in RA monocytes is linked to disease activity score and TNF transcription. TNF stimulation can modulate IL-7 secretion and IL-7R frequency in myeloid cells, however, only IL-7R transcription levels are downregulated in anti-TNF responsive patients. Elevated levels of IL-7 in RA synovial tissue and fluid are involved in attracting RA monocytes into the inflammatory joints and remodeling them into proinflammatory macrophages and mature osteoclasts. Further, IL-7 amplification of RA Th1 cell differentiation and IFNγ secretion, can directly prime myeloid IL-7R expression and thereby exacerbate IL-7-mediated joint inflammatory and erosive imprints. In parallel, IL-7 accentuates joint angiogenesis by expanding the production of proangiogenic factors from RA macrophages and endothelial cells. In preclinical models, blockade of IL-7 or IL-7R can effectively impair joint inflammation, osteoclast formation, and neovascularization primarily by impeding monocyte and endothelial cell infiltration as well as inhibition of pro-inflammatory macrophage and Th1/Th17 cell differentiation. In conclusion, disruption of IL-7/IL-7R signaling can uniquely intercept the crosstalk between RA myeloid and lymphoid cells in their ability to trigger neovascularization.

The decidual expression of Interleukin-7 is upregulated in early pregnancy loss

BACKGROUND

Maternal immunological rejection of the semi-allogenic fetus is discussed as one of the significant factors involved in early pregnancy loss. An array of cytokines secreted by both maternal and fetal cells is involved in generating a delicate maternal immune tolerance. Interleukin-7 (IL-7) is discussed to play a key role in pro-inflammatory processes, but there is still limited insight into the pathophysiological input on placentation and embryonic development in early pregnancy loss.

PATIENTS AND METHODS

Cytokine level differences were identified with quantitative real-time PCR in placental tissue from spontaneous abortions (SA) (n = 18), recurrent spontaneous abortions (RSA) (n = 15), and healthy pregnancies (n = 15) at gestational weeks 7 to 14. Protein expression of IL-7 in the decidua was investigated by immunohistochemistry. IL-7-expressing cells were identified with double-immunofluorescence.

RESULTS

Decidua of women with RSA expressed almost 51-times higher values of IL-7 in gene expression analysis. Immunohistochemistry identified a significant upregulation of IL-7 in the decidua of RSA specimens (p = .013) and in the decidua of women with SA (p = .004). Double-immunofluorescence confirmed decidual stroma cells as IL-7-expressing cells.

CONCLUSION

Significantly elevated IL-7 values in the decidua of spontaneous and recurrent miscarriages imply a crucial role of the cytokine in the signaling at the feto-maternal interface of the placenta. An overexpression of IL-7 could result in early pregnancy loss by inducing a pro-inflammatory environment. Proven to be valuable in other autoimmune diseases, targeting IL-7 signaling therapeutically may prove to be a very beneficial treatment option for RSA patients.

Interleukin-7/Interferon Axis Drives T Cell and Salivary Gland Epithelial Cell Interactions in Sjögren's Syndrome

OBJECTIVE

Primary Sjögren's syndrome (SS) is characterized by a lymphocytic infiltration of salivary glands (SGs) and the presence of an interferon (IFN) signature. SG epithelial cells (SGECs) play an active role in primary SS pathophysiology. We undertook this study to examine the interactions between SGECs and T cells in primary SS and the role of the interleukin-7 (IL-7)/IFN axis.

METHODS

Primary cultured SGECs from control subjects and patients with primary SS were stimulated with poly(I-C), IFNα, or IFNγ. T cells were sorted from blood and stimulated with IL-7. CD25 expression was assessed by flow cytometry. SG explants were cultured for 4 days with anti-IL-7 receptor (IL-7R) antagonist antibody (OSE-127), and transcriptomic analysis was performed using the NanoString platform.

RESULTS

Serum IL-7 level was increased in patients with primary SS compared to controls and was associated with B cell biomarkers. IL7R expression was decreased in T cells from patients with primary SS compared to controls. SGECs stimulated with poly(I-C), IFNα, or IFNγ secreted IL-7. IL-7 stimulation increased the activation of T cells, as well as IFNγ secretion. Transcriptomic analysis of SG explants showed a correlation between IL7 and IFN expression. Finally, explants cultured with anti-IL-7R antibody showed decreased IFN-stimulated gene expression.

CONCLUSION

These results suggest the presence of an IL-7/IFNγ amplification loop involving SGECs and T cells in primary SS. IL-7 was secreted by SGECs stimulated with type I or type II IFN and, in turn, activated T cells that secrete type II IFN. An anti-IL-7R antibody decreased the IFN signature in T cells in primary SS and could be of therapeutic interest.

Identification of New Soluble Factors Correlated With the Development of Graft Failure After Haploidentical Hematopoietic Stem Cell Transplantation

Graft failure is a severe complication of allogeneic hematopoietic stem cell transplantation (HSCT). The mechanisms involved in this phenomenon are still not completely understood; data available suggest that recipient T lymphocytes surviving the conditioning regimen are the main mediators of immune-mediated graft failure. So far, no predictive marker or early detection method is available. In order to identify a non-invasive and efficient strategy to diagnose this complication, as well as to find possible targets to prevent/treat it, we performed a detailed analysis of serum of eight patients experiencing graft failure after T-cell depleted HLA-haploidentical HSCT. In this study, we confirm data describing graft failure to be a complex phenomenon involving different components of the immune system, mainly driven by the IFNγ pathway. We observed a significant modulation of IL7, IL8, IL18, IL27, CCL2, CCL5 (Rantes), CCL7, CCL20 (MIP3a), CCL24 (Eotaxin2), and CXCL11 in patients experiencing graft failure, as compared to matched patients not developing this complication. For some of these factors, the difference was already present at the time of infusion of the graft, thus allowing early risk stratification. Moreover, these cytokines/chemokines could represent possible targets, providing the rationale for exploring new therapeutic/preventive strategies.

Associations of clinical and inflammatory biomarker clusters with juvenile idiopathic arthritis categories

OBJECTIVE

To identify discrete clusters comprising clinical features and inflammatory biomarkers in children with JIA and to determine cluster alignment with JIA categories.

METHODS

A Canadian prospective inception cohort comprising 150 children with JIA was evaluated at baseline (visit 1) and after six months (visit 2). Data included clinical manifestations and inflammation-related biomarkers. Probabilistic principal component analysis identified sets of composite variables, or principal components, from 191 original variables. To discern new clinical-biomarker clusters (clusters), Gaussian mixture models were fit to the data. Newly-defined clusters and JIA categories were compared. Agreement between the two was assessed using Kruskal-Wallis analyses and contingency plots.

RESULTS

Three principal components recovered 35% (three clusters) and 40% (five clusters) of the variance in patient profiles in visits 1 and 2, respectively. None of the clusters aligned precisely with any of the seven JIA categories but rather spanned multiple categories. Results demonstrated that the newly defined clinical-biomarker lustres are more homogeneous than JIA categories.

CONCLUSION

Applying unsupervised data mining to clinical and inflammatory biomarker data discerns discrete clusters that intersect multiple JIA categories. Results suggest that certain groups of patients within different JIA categories are more aligned pathobiologically than their separate clinical categorizations suggest. Applying data mining analyses to complex datasets can generate insights into JIA pathogenesis and could contribute to biologically based refinements in JIA classification.

Differential CpG DNA methylation in peripheral naïve CD4+ T-cells in early rheumatoid arthritis patients

Background

The genetic risk associated with rheumatoid arthritis (RA) includes genes regulating DNA methylation, one of the hallmarks of epigenetic re-programing, as well as many T-cell genes, with a strong MHC association, pointing to immunogenetic mechanisms as disease triggers leading to chronicity. The aim of our study was to explore DNA methylation in early, drug-naïve RA patients, towards a better understanding of early events in pathogenesis.

Result

Monocytes, naïve and memory CD4⁺ T-cells were sorted from 6 healthy controls and 10 RA patients. DNA methylation was assessed using a genome-wide Illumina 450K CpG promoter array. Differential methylation was confirmed using bisulfite sequencing for a specific gene promoter, ELISA for several cytokines and flow cytometry for cell surface markers. Differentially methylated (DM) CpGs were observed in 1047 genes in naïve CD4⁺ T-cells, 913 in memory cells and was minimal in monocytes with only 177 genes. Naive CD4⁺ T-cells were further investigated as presenting differential methylation in the promoter of > 500 genes associated with several disease-relevant pathways, including many cytokines and their receptors. We confirmed hypomethylation of a region of the TNF-alpha gene in early RA and differential expression of 3 cytokines (IL21, IL34 and RANKL). Using a bioinformatics package (DMRcate) and an in-house analysis based on differences in β values, we established lists of DM genes between health and RA. Publicly available gene expression data were interrogated to confirm differential expression of over 70 DM genes. The lists of DM genes were further investigated based on a functional relationship database analysis, which pointed to an IL6/JAK1/STAT3 node, related to TNF-signalling and engagement in Th17 cell differentiation amongst many pathways. Five DM genes for cell surface markers (CD4, IL6R, IL2RA/CD25, CD62L, CXCR4) were investigated towards identifying subpopulations of CD4⁺ T-cells undergoing these modifications and pointed to a subset of naïve T-cells, with high levels of CD4, IL2R, and CXCR4, but reduction and loss of IL6R and CD62L, respectively.

Conclusion

Our data provided novel conceptual advances in the understanding of early RA pathogenesis, with implications for early treatment and prevention.

IL-7 is a Key Driver Cytokine in Spondyloarthritis?

The rationale for a type 17 signature in the pathogenesis of spondyloarthritis (SpA) has been increasing and being ratified in studies recently. IL-7 is a cytokine whose ability to stimulate IL-17 production in both innate and adaptive immunity cells has made it a promising target not only for a better understanding of the disease as well as an important potential therapeutic target in patients with SpA.

Modulation of parietal cytokine and chemokine gene profiles by mesenchymal stem cell as a basis for neurotrauma recovery

BACKGROUND & PURPOSE

Following traumatic brain injury (TBI), primary mechanical injury to the brain may cause blood-brain-barrier damage followed by secondary injury, ultimately culminating in cell death. We aimed to test whether one injection of mesenchymal stem cells (MSC) derived from the human umbilical cord can modulate brain cytokine and chemokine gene profiles and attenuate neurological injury in rats with TBI.

METHODS

One-day post-TBI, the injured rats were treated with one injection of MSC (4 × 10⁶/rat, i.v.). Three days later, immediately after assessment of neurobehavioral function, animals were sacrificed for analysis of neurological injury (evidenced by both brain contusion volume and neurological deficits) and parietal genes encoding 84 cytokines and chemokines in the injured brain by qPCR methods.

RESULTS

Three days post-TBI, rats displayed both neurological injury and upgrade of 11 parietal genes in the ipsilateral brain. One set of 8 parietal genes (e.g., chemokine [C-X-C motif] ligand 12, platelet factor 4, interleukin-7, chemokine [C-C motif] ligand (CCL)19, CCL 22, secreted phosphoprotein 1, pro-platelet basic protein 1, and CCL 2) differentially upgraded by TBI was related to pro-inflammatory and/or neurodegenerative processes. Another set of 3 parietal genes up-graded by TBI (e.g., glucose-6-phosphate isomerase, bone morphogenetic protein (BMP) 2, and BMP 4) was related to anti-inflammatory/neuroregenerative events. Administration of MSC attenuated neurological injury, down-regulated these 8 parietal pro-inflammatory genes, and up-regulated these 3 parietal anti-inflammatory genes in the rats with TBI.

CONCLUSION

Our data suggest that modulation of parietal cytokines and chemokines gene profiles by MSC as a basis for neurotrauma recovery.

Anti-IL-7 receptor α monoclonal antibody (GSK2618960) in healthy subjects - a randomized, double-blind, placebo-controlled study

Aim

Interleukin (IL)‐7 signalling modulates T cell activity and is implicated in numerous autoimmune diseases. The present study investigated the safety, pharmacokinetics, target engagement, pharmacodynamics and immunogenicity of GSK2618960, an IL‐7 receptor‐α subunit (CD127) monoclonal antibody.

Methods

A double‐blind (sponsor‐unblind) study of a single intravenous infusion of either GSK2618960 (0.6 mg kg^–1 or 2.0 mg kg^–1) or placebo was carried out in 18 healthy subjects over 24 weeks.

Results

GSK2618960 was well tolerated; there were no serious or significant adverse events. The observed half‐life was 5 (±1) days (2.0 mg kg^–1), with nonlinear pharmacokinetics. Full receptor occupancy (>95%) was observed until day 8 (0.6 mg kg^–1) and day 22 (2.0 mg kg^–1). Maximal inhibition of IL‐7‐mediated signal transducer and activator of transcription 5 (STAT5) phosphorylation was observed in 5/6 subjects until day 22 (2.0 mg kg^–1). Mean circulating IL‐7 and soluble receptor (CD127) levels were increased above baseline during days 2 and 15 (0.6 mg kg^–1) and days 2 and 22 (2.0 mg kg^–1). No meaningful changes were observed in absolute numbers or proportions of immune cell populations or inflammatory cytokine profiles (IL‐6, tumour necrosis factor‐α, interferon‐γ, IL‐2). Persistent antidrug antibodies (ADAs) were detected in 5/6 subjects administered a dose of 0.6 mg kg^–1 (neutralizing in 2/6) and in 6/6 subjects administered 2.0 mg kg^–1 (neutralizing in 5/6).

Conclusion

GSK2618960 was well tolerated and blocked IL‐7 receptor signalling upon full target engagement. Although there was no discernible impact on peripheral T cell subsets in healthy subjects, GSK2618960 may effectively modulate the autoinflammatory activity of pathogenic T cells in diseased tissue. A relatively short half‐life is likely the result of target‐mediated rather than ADA‐mediated clearance.

Interleukin-7 Induces Osteoclast Formation via STAT5, Independent of Receptor Activator of NF-kappaB Ligand

Interleukin-7 (IL-7), which is required for the development and survival of T cells in the thymus and periphery, plays a role in joint destruction. However, it remains unclear how IL-7 affects osteoclast formation. Thus, we investigated the mechanism by which IL-7 induced osteoclast formation through IL-7 receptor α (IL-7Rα) in osteoclast precursors. We cultured peripheral blood mononuclear cells or synovial fluid mononuclear cells with IL-7 in the presence or absence of an appropriate inhibitor to analyze osteoclast formation. We also constructed IL-7Rα-expressing RAW264.7 cells to uncover the mechanism(s) by which IL-7 induced osteoclast formation differed from that of receptor activator of nuclear factor κB ligand (RANKL). We found that IL-7 induced osteoclast formation of human monocytes from peripheral blood or synovial fluid in a RANKL-independent and a signal transducer and activator of transcription 5 (STAT5)-dependent manner. IL-7-induced osteoclasts had unique characteristics, such as small, multinucleated tartrate-resistant acid phosphatase positive cells and no alterations even when RANKL was added after IL-7 pretreatment. RAW264.7 cells, if overexpressing IL-7Rα, also were able to differentiate into osteoclasts by IL-7 through a STAT5 signaling pathway. Furthermore, IL-7-induced osteoclast formation was repressed by inhibitors of the IL-7R signaling molecules Janus kinase and STAT5. Our findings demonstrate that IL-7 is a truly osteoclastogenic factor, which may induce osteoclast formation via activation of STAT5, independent of RANKL. We also suggest the possibility that an IL-7R pathway blocker could alleviate joint damage by inhibiting osteoclast formation, especially in inflammatory conditions.

Developing anti-inflammatory therapeutics for patients with osteoarthritis

OA is the most common joint disorder in the world, but there are no approved therapeutics to prevent disease progression. Historically, OA has been considered a wear-and-tear joint disease, and efforts to identify and develop disease-modifying therapeutics have predominantly focused on direct inhibition of cartilage degeneration. However, there is now increasing evidence that inflammation is a key mediator of OA joint pathology, and also that the link between obesity and OA is not solely due to excessive load-bearing, suggesting therefore that targeting inflammation in OA could be a rewarding therapeutic strategy. In this review we therefore re-evaluate historical clinical trial data on anti-inflammatory therapeutics in OA patients, highlight some of the more promising emerging therapeutic targets and discuss the implications for future clinical trial design.

Improving Chimeric Antigen Receptor-Modified T Cell Function by Reversing the Immunosuppressive Tumor Microenvironment of Pancreatic Cancer

The adoptive transfer of T cells redirected to tumor-associated antigens via transgenic expression of chimeric antigen receptors (CARs) has produced tumor responses, even in patients with refractory diseases. To target pancreatic cancer, we generated CAR T cells directed against prostate stem cell antigen (PSCA) and demonstrated specific tumor lysis. However, pancreatic tumors employ immune evasion strategies such as the production of inhibitory cytokines, which limit CAR T cell persistence and function. Thus, to protect our cells from the immunosuppressive cytokine IL-4, we generated an inverted cytokine receptor in which the IL-4 receptor exodomain was fused to the IL-7 receptor endodomain (4/7 ICR). Transgenic expression of this molecule in CAR-PSCA T cells should invert the inhibitory effects of tumor-derived IL-4 and instead promote T cell proliferation. We now demonstrate the suppressed activity of CAR T cells in tumor-milieu conditions and the ability of CAR/ICR T cells to thrive in an IL-4-rich microenvironment, resulting in enhanced antitumor activity. Importantly, CAR/ICR T cells remained both antigen and cytokine dependent. These findings support the benefit of combining the 4/7 ICR with CAR-PSCA to treat pancreatic cancer, a PSCA-expressing tumor characterized by a dense immunosuppressive environment rich in IL-4.

Variants of Interleukin-7/Interleukin-7 Receptor Alpha are Associated with Both Neuromyelitis Optica and Multiple Sclerosis Among Chinese Han Population in Southeastern China

BACKGROUND

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune demyelinating diseases of the central nerve system. Interleukin-7 (IL-7) and interleukin-7 receptor alpha (IL-7Rα) were proved to be important in the pathogenesis of both diseases because of the roles they played in the differentiations of autoimmune lymphocytes. The variants of both genes had been identified to be associated with MS susceptibility in Caucasian, Japanese and Korean populations. However, the association of these variants with NMO and MS has not been well studied in Chinese Southeastern Han population. Here, we aimed to evaluate the association of six IL-7 variants (rs1520333, rs1545298, rs4739140, rs6993386, rs7816065, and rs2887502) and one variant of IL-7RA (rs6897932) with NMO and MS among Chinese Han population in southeastern China.

METHODS

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MassARRAY system) and Sanger sequencing were used to determine the variants of IL-7 and IL-7RA in 167 NMO patients, 159 MS patients and 479 healthy controls among Chinese Han population in southeastern China. Samples were excluded if the genotyping success rate <90%.

RESULTS

Statistical differences were observed in the genotypes of IL-7 rs1520333 in MS patients and IL-7RA rs6897932 in NMO patients, compared with healthy controls (P = 0.035 and 0.034, respectively). There was a statistically significant difference in the genotypes of IL-7 rs2887502 between MS and NMO patients (P = 0.014). And there were statistically significant differences in the rs6897932 genotypes (P = 0.004) and alleles (P = 0.042) between NMO-IgG positive patients and healthy controls.

CONCLUSIONS

The study suggested that among Chinese Han population in southeastern China, the variant of IL-7RA (rs6897932) was associated with NMO especially NMO-IgG positive patients while the variant of IL-7 (rs1520333) with MS patients. And the genotypic differences of IL-7 rs2887502 between MS and NMO indicated the different genetic backgrounds of these two diseases.

Blockade of IL-7Rα alleviates collagen-induced arthritis via inhibiting Th1 cell differentiation and CD4+ T cell migration

T cell response is crucial to the pathogenesis and progression of rheumatoid arthritis (RA). IL-7/IL-7R axis has significant effect on CD4⁺ T cell response, including proliferation, differentiation, survival and migration. However, whether blockade of IL-7/IL-7R axis signaling can relieve RA and what is the potential treatment mechanisms are still remaining unclear. In this paper, we established collagen-induced arthritis (CIA) model and observed the effect of IL-7Rα antibody in the treatment of CIA mice. It is demonstrated that IL-7Rα antibody significantly alleviated clinical symptoms of CIA mice, accompanied with reduced CD4⁺ T cell number in both spleen and joints. Decreased CII-specific CD4⁺ T cell proliferation and reduced mRNA expression of inflammatory cytokines in IL-7Rα antibody-treated mice were observed. Subsequently, IL-7Rα antibody treatment in vivo downregulated the percentages of Th1 and Th17 cells and the mRNA expression of T-bet and RORγt gene. Moreover, it was found that IL-7 promoted Th1 cell differentiation in vitro, while having no effect on Th17 cell differentiation. In addition, administration of IL-7Rα antibody reduced the mRNA expression of chemokine receptors (CCR7, CXCR3, CXCR6 and XCR1) on CD4⁺ T cells and chemokine CXCL2 in joints. The results suggested that IL-7Rα antibody treated CIA mice via the inhibition of CII-specific CD4⁺ T cell proliferation, the reduction of Th1 cell differentiation and the restrain of CD4⁺ T cell migration to joint lesion site. This investigation indicates that IL-7Rα is a potential therapeutic target for RA.

Long Intergenic Noncoding RNAs Mediate the Human Chondrocyte Inflammatory Response and Are Differentially Expressed in Osteoarthritis Cartilage

OBJECTIVE

To identify long noncoding RNAs (lncRNAs), including long intergenic noncoding RNAs (lincRNAs), antisense RNAs, and pseudogenes, associated with the inflammatory response in human primary osteoarthritis (OA) chondrocytes and to explore their expression and function in OA.

METHODS

OA cartilage was obtained from patients with hip or knee OA following joint replacement surgery. Non-OA cartilage was obtained from postmortem donors and patients with fracture of the neck of the femur. Primary OA chondrocytes were isolated by collagenase digestion. LncRNA expression analysis was performed by RNA sequencing (RNAseq) and quantitative reverse transcriptase-polymerase chain reaction. Modulation of lncRNA chondrocyte expression was achieved using LNA longRNA GapmeRs (Exiqon). Cytokine production was measured with Luminex.

RESULTS

RNAseq identified 983 lncRNAs in primary human hip OA chondrocytes, 183 of which had not previously been identified. Following interleukin-1β (IL-1β) stimulation, we identified 125 lincRNAs that were differentially expressed. The lincRNA p50-associated cyclooxygenase 2-extragenic RNA (PACER) and 2 novel chondrocyte inflammation-associated lincRNAs (CILinc01 and CILinc02) were differentially expressed in both knee and hip OA cartilage compared to non-OA cartilage. In primary OA chondrocytes, these lincRNAs were rapidly and transiently induced in response to multiple proinflammatory cytokines. Knockdown of CILinc01 and CILinc02 expression in human chondrocytes significantly enhanced the IL-1-stimulated secretion of proinflammatory cytokines.

CONCLUSION

The inflammatory response in human OA chondrocytes is associated with widespread changes in the profile of lncRNAs, including PACER, CILinc01, and CILinc02. Differential expression of CILinc01 and CIinc02 in hip and knee OA cartilage, and their role in modulating cytokine production during the chondrocyte inflammatory response, suggest that they may play an important role in mediating inflammation-driven cartilage degeneration in OA.

Association of interleukin 7 receptor (rs1494555 and rs6897932) gene polymorphisms with asthma in a north Indian population

Background:

Interleukin 7R (IL-7R), a cytokine receptor gene, plays an important role in the development of innate and adaptive inflammatory response in asthma etiology.

Objective:

IL-7R is a heterodimeric protein composed of α chain and γ chain. The α chain of IL-7R has a range of single nucleotide polymorphisms, which give rise to nonsynonymous amino-acid substitutions that might result in an increased production of inflammatory cytokines and cause asthma.

Methods:

A case-control study was conducted with a total of 964 subjects, including 483 healthy controls and 481 patients with asthma. DNA samples were extracted from blood, and genotyping was done by using sequence-specific-primer–polymerase chain reaction.

Results:

Statistical analysis revealed that IL-7R + 1237A/G (rs1494555) gene polymorphism shows a highly protective association toward asthma (odds ratio [OR] 0.56, p < 0.001) in AG genotype as well as in mutant GG genotype (OR 0.64, p = 0.029). However, IL-7R + 2087T/C (rs6897932) polymorphism showed an increased risk toward asthma in TC genotype (OR 1.70, p = 0.002) as well as in the CC genotype (OR 1.68, p = 0.002). Furthermore, the GT and AC haplotypes in the IL-7R polymorphisms were also found to be significantly associated with asthma (p < 0.001 and p = 0.037, respectively).

Conclusions:

The study conducted in a north Indian population indicated that the protective association was observed for the +1237A/G position, and a significant risk was observed for the +2087T/C position in asthma.

Lymphopenia in early arthritis: Impact on diagnosis and 3-year outcomes (ESPOIR cohort)

OBJECTIVES

In patients with early arthritis naive to disease-modifying antirheumatic drugs, we evaluated the prevalence of initial and persistent lymphopenia, underlying diagnoses, and risk of infection or malignancy.

METHODS

Eight hundred and thirteen patients with early arthritis included in the ESPOIR cohort had a clinical examination, laboratory tests (viral serology, immunological tests, and cytokine profile), and radiographs. We determined the prevalence of lymphopenia at baseline and after 3 years, associated factors, diagnoses, and risk of infection or malignancy.

RESULTS

At baseline, 50/813 (6.2%) patients had lymphopenia. Lymphopenia was associated with positive rheumatoid factor (P=0.02), cytopenia (P≤0.05), hepatitis C (P=0.05), higher C-reactive protein and DAS28 (P≤0.05 for both). Cytokine profile and radiological progression were not significantly different between patients with and without lymphopenia. Suspected diagnoses at inclusion were rheumatoid arthritis (RA, n=27), unclassified arthritis (n=15), systemic lupus erythematosus (SLE, n=3), spondyloarthritis (n=2), Sjögren's syndrome (n=1), hematologic disease (n=1), and fibromyalgia (n=1). Fifteen patients out of 42 (35.7%) with initial lymphopenia had persistent lymphopenia after 3 years, including 5 with documented causes (lupus, hepatitis C, undernutrition, azathioprine, and tamoxifen); none had PVB19, HIV, or HBV infection and none experienced infections, solid or hematologic malignancies during follow-up. Final diagnoses in these 15 patients were RA (n=6), unclassified arthritis (n=6), SLE (n=1), spondyloarthritis (n=1), and fibromyalgia (n=1).

CONCLUSIONS

Lymphopenia is rare in early arthritis. The most common rheumatic cause is RA, in which marked inflammation and other cytopenias are common. Lymphopenia in early arthritis is often short-lived, even when methotrexate is prescribed.

The Additive Inflammatory In Vivo and In Vitro Effects of IL-7 and TSLP in Arthritis Underscore the Therapeutic Rationale for Dual Blockade

INTRODUCTION

The cytokines interleukin (IL)-7 and thymic stromal lymphopoietin (TSLP) signal through the IL-7R subunit and play proinflammatory roles in experimental arthritis and rheumatoid arthritis (RA). We evaluated the effect of inhibition of IL-7R- and TSLPR-signalling as well as simultaneous inhibition of IL-7R- and TSLPR-signalling in murine experimental arthritis. In addition, the effects of IL-7 and TSLP in human RA dendritic cell (DC)/T-cell co-cultures were studied.

METHODS

Arthritis was induced with proteoglycan in wildtype mice (WT) and in mice deficient for the TSLP receptor subunit (TSLPR-/-). Both mice genotypes were treated with anti-IL-7R or phosphate buffered saline. Arthritis severity was assessed and local and circulating cytokines were measured. Autologous CD1c-positive DCs and CD4 T-cells were isolated from peripheral blood of RA patients and were co-cultured in the presence of IL-7, TSLP or both and proliferation and cytokine production were assessed.

RESULTS

Arthritis severity and immunopathology were decreased in WT mice treated with anti-IL-7R, in TSLPR-/- mice, and the most robustly in TSLPR-/- mice treated with anti-IL-7R. This was associated with strongly decreased levels of IL-17, IL-6 and CD40L. In human DC/T-cell co-cultures, TSLP and IL-7 additively increased T-cell proliferation and production of Th17-associated cytokines, chemokines and tissue destruction factors.

CONCLUSION

TSLP and IL-7 have an additive effect on the production of Th17-cytokines in a human in vitro model, and enhance arthritis in mice linked with enhanced inflammation and immunopathology. As both cytokines signal via the IL-7R, these data urge for IL-7R-targeting to prevent the activity of both cytokines in RA.

The efficacy of abatacept in reducing synovial T cell activation by CD1c myeloid dendritic cells is overruled by the stimulatory effects of T cell-activating cytokines

OBJECTIVE

To investigate whether the potential of abatacept to inhibit vigorous CD1c myeloid dendritic cell (MDC)-driven activation of naive and memory CD4 T cells is abrogated in the presence of T cell-activating cytokines.

METHODS

CD4 T cell subsets (naive [Tn], central memory [Tcm], and effector memory [Tem] T cells) were isolated from the peripheral blood (PB) of healthy controls and the PB and synovial fluid (SF) of rheumatoid arthritis (RA) patients. CD4 T cells were cocultured with autologous, thymic stromal lymphopoietin (TSLP)-primed CD1c MDCs in the presence or absence of abatacept (CTLA-4Ig) and/or interleukin-7 (IL-7) or IL-15. Subsequently, T cell proliferation and cytokine production were measured.

RESULTS

The percentages of each CD4 T cell subset from the circulation of healthy controls and RA patients were comparable and mainly consisted of Tn and Tcm cells, whereas the SF of RA patients mainly consisted of Tcm and Tem cells. Activation of CD4 T cell subsets by TSLP-primed MDCs from the RA PB was completely blocked by abatacept. Addition of IL-7 or IL-15 to the cocultures strongly increased CD4 T cell activation and overruled the inhibitory capacity of abatacept. IL-7-induced reversal was associated with robust induction of interferon-γ, tumor necrosis factor α, and IL-17 secretion. Similarly, CD4 T cell proliferation induced by TSLP-primed MDCs from the SF of RA patients was strongly blocked by abatacept, but this inhibitory effect was vigorously overruled in the presence of IL-7.

CONCLUSION

These findings indicate that the presence of T cell-activating cytokines such as IL-7 or IL-15 in the joints of RA patients reduces the capacity of abatacept to inhibit MDC-driven CD4 T cell activation. This mechanism may be one explanation for the partial, and sometimes absent, response to abatacept therapy in a subset of patients.

T-cells and B-cells in osteoporosis

PURPOSE OF REVIEW

Bone disease is a leading cause of fractures and continues to be a source of significant morbidity and mortality worldwide. As the underlying mechanisms of osteoporosis are elucidated, immune dysfunction continues to emerge as a key precipitating factor in multiple bone disease contexts. This review examines recent findings in the osteoimmunology field and their implications for bone disease and for novel future therapeutic approaches to rejuvenate the skeleton.

RECENT FINDINGS

T-cells and B-cells have long been recognized to play important roles in the etiology of inflammatory bone disease; however, new findings continue to challenge our understanding of the depth of the immuno-skeletal interface. In this review, we examine recent evidence for new roles of B-cells in oestrogen deficiency bone loss; central actions of interleukin-7 in the cause of T-cell mediated tissue destruction in rheumatoid arthritis; novel RANKL-independent alveolar bone loss in periodontal infection; and a putative role for γδ T-cells in bisphosphonate-associated osteonecrosis of the jaw. Finally, evidence for novel bone anabolic activities mediated through T-cells by the CD28 antagonist CTLA-4Ig and by intermittently administered parathyroid hormone are examined.

SUMMARY

As the field of osteoimmunology continues to mature, new interrelationships between immune cells and bone turnover continue to emerge.

Clinical biomarkers and pathogenic-related cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common autoimmune disease with unknown etiology and pathogenesis. Although major therapeutic advances have been made in recent years, there is no cure for the disease. Current medications mainly reduce inflammation in order to relieve pain and slow joint damage, but many have potentially serious side effects. Therefore, to find specific biomarkers will benefit both RA patients to find relief from the disease and physicians to monitor the disease development. A number of biomarkers have been discovered and used clinically, and others are still under investigation. The autoantibodies, which are widely used in diagnosis and prognosis, novel biomarkers, which reflect clinical disease activity, and newly found biomarkers and pathogenic-related cytokines are discussed in this review.

Th17 cells and IL-17 a--focus on immunopathogenesis and immunotherapeutics

IMPORTANCE

Accumulating evidence suggests that IL-17 A has broad pathogenic roles in multiple autoimmune and immune-mediated inflammatory diseases, including psoriasis and rheumatoid arthritis (RA). The development of new therapies that inhibit IL-17 pathway signaling is of clinical significance.

OBJECTIVES

This review aims to summarize the current preclinical evidence on the role of Th17 cells and IL-17 and related cytokines in immune-mediated disease pathophysiology, with a focus on psoriasis and rheumatoid arthritis, as well as to summarize recent clinical trials in these indications with newly developed IL-17 pathway inhibitors.

METHODS

A systematic literature search was conducted of PubMed using relevant keywords. Studies were assessed according to recent relevance to IL-17-mediated pathophysiology and clinical IL-17 inhibition. Experimental animal models of autoimmune disease and clinical studies that focused on IL-17 pathway inhibitors were included.

RESULTS

Preclinical studies suggest that IL-17A is an attractive therapeutic target. Several IL-17A inhibitors have advanced into clinical trials, including the anti-IL-17A monoclonal antibodies, secukinumab and ixekizumab, and the anti-17RA monoclonal antibody brodalumab. Each has shown variable and sometimes favorable results in proof-of-concept and phase II clinical trials and is currently undergoing further clinical evaluation in a range of immune-mediated diseases.

CONCLUSION

Targeting the IL-17 pathway shows promise as strategy to treat immune-mediated diseases ranging from skin to joints.

Interferon (IFN)-γ-mediated inflammation and the kynurenine pathway in relation to bone mineral density: the Hordaland Health Study

The risk of osteoporosis increases in inflammatory disorders. In cell-mediated immune activation, interferon (IFN)-γ stimulates macrophage release of neopterin and increases the activity of indoleamine 2,3-dioxygenase (IDO), thereby stimulating tryptophan degradation along the kynurenine pathway. Plasma levels of neopterin and the kynurenine/tryptophan ratio (KTR) are thus markers of IFN-γ-mediated inflammation. Several kynurenine pathway metabolites (kynurenines) possess immunomodulatory properties. The aim of this study was to investigate associations between markers of IFN-γ-mediated inflammation and kynurenines with bone mineral density (BMD). The community-based Hordaland Health Study (HUSK), with middle-aged (46–49 years) and older (71–74 years) participants, was conducted from 1998 to 2000 (n = 5312). Hip BMD in relation to neopterin, KTR and kynurenines were investigated, using linear and logistic regression analyses. In the oldest group, neopterin (P ≤ 0·019) and KTR (P ≤ 0·001) were associated inversely with BMD after multiple adjustment. Comparing the highest to the lowest quartiles, the odds ratios of low BMD (being in the lowest quintile of BMD) in the oldest cohort were for neopterin 2·01 among men and 2·34 among women (P ≤ 0·007) and for KTR 1·80 for men and 2·04 for women (P ≤ 0·022). Xanthurenic acid was associated positively with BMD in all sex and age groups while 3-hydroxyanthranilic acid was associated positively with BMD among women only (P ≤ 0·010). In conclusion, we found an inverse association between BMD and markers of IFN-γ-mediated inflammation in the oldest participants. BMD was also associated with two kynurenines in both age groups. These results may support a role of cell-mediated inflammation in bone metabolism.

Cytokines in common variable immunodeficiency as signs of immune dysregulation and potential therapeutic targets - a review of the current knowledge

Common variable immunodeficiency (CVID) is characterized by low levels of circulating immunoglobulins and compromised specific antibody response leading to frequent infections. Cytokines play an important role in the orchestration of the antibody response. Several previous studies have attempted to identify distinct cytokines responsible for the inflammatory changes and different manifestations of CVID, but there are conflicting results regarding the cytokine profiles in CVID patients. In light of this, an extensive review regarding the level of various cytokines and their potential therapeutic role in CVID patients was performed. This review delineates the contribution of interleukin (IL)-1, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12, IL-21, interferons, tumor necrosis factor (TNF)-α, IL-17, APRIL (a proliferation inducing ligand) and BAFF (B cell activating factor) in CVID disease and outline their potential therapeutic implications in these patients.

Interleukin-12 (IL-12), but not IL-23, induces the expression of IL-7 in microglia and macrophages: implications for multiple sclerosis

Interleukin-12 (IL-12) p70 and IL-23 are bioactive cytokines and their biological functions are becoming clear. Increased expression of IL-7 in the central nervous system as well as in peripheral immune cells is associated with multiple sclerosis and experimental allergic encephalomyelitis. Here, we describe the induction of IL-7 in primary mouse and human microglia, BV-2 microglial cells, mouse peritoneal macrophages and astrocytes by IL-12p70. Interestingly, IL-12 strongly induced the expression of IL-7 whereas IL-23 and other p40 family members remained weak inducers of IL-7 in these cell types. Consistently, IL-12, but not IL-23 and other p40 family members, induced IL-7 promoter-driven luciferase activity in microglial cells. Among various stimuli tested, IL-12 emerged as the most potent stimulus followed by bacterial lipopolysaccharide and HIV-1 gp120 in inducing the activation of IL-7 promoter in microglial cells. Furthermore, increase in IL-7 mRNA expression by over-expression of IL-12p35 subunit, but not p40 and IL-23 p19 subunit, confirm that p35, but not p40 and p19, is responsible for the induction of IL-7. Finally, by using primary microglia from IL-12 receptor β1-deficient (IL-12Rβ1(-/-)) and IL-12Rβ2(-/-) mice, we demonstrate that IL-12 induces the expression of IL-7 in microglia and macrophages via both IL-12Rβ2 and IL-12Rβ1. These studies delineate a novel biological function of IL-12 that is absent in IL-23 and other p40 family members.

Interleukin-7 and Toll-like receptor 7 induce synergistic B cell and T cell activation

Objectives

To investigate the potential synergy of IL-7-driven T cell-dependent and TLR7-mediated B cell activation and to assess the additive effects of monocyte/macrophages in this respect.

Methods

Isolated CD19 B cells and CD4 T cells from healthy donors were co-cultured with TLR7 agonist (TLR7A, Gardiquimod), IL-7, or their combination with or without CD14 monocytes/macrophages (T/B/mono; 1 : 1 : 0,1). Proliferation was measured using ³H-thymidine incorporation and Ki67 expression. Activation marker (CD19, HLA-DR, CD25) expression was measured by FACS analysis. Immunoglobulins were measured by ELISA and release of cytokines was measured by Luminex assay.

Results

TLR7-induced B cell activation was not associated with T cell activation. IL-7-induced T cell activation alone and together with TLR7A synergistically increased numbers of both proliferating (Ki67⁺) B cells and T cells, which was further increased in the presence of monocytes/macrophages. This was associated by up regulation of activation markers on B cells and T cells. Additive or synergistic induction of production of immunoglobulins by TLR7 and IL-7 was associated by synergistic induction of T cell cytokines (IFNγ, IL-17A, IL-22), which was only evident in the presence of monocytes/macrophages.

Conclusions

IL-7-induced CD4 T cell activation and TLR7-induced B cell activation synergistically induce T helper cell cytokine and B cell immunoglobulin production, which is critically dependent on monocytes/macrophages. Our results indicate that previously described increased expression of IL-7 and TLR7 together with increased numbers of macrophages at sites of inflammation in autoimmune diseases like RA and pSS significantly contributes to enhanced lymphocyte activation.

IL7RA haplotype-associated alterations in cellular immune function and gene expression patterns in multiple sclerosis

Interleukin-7 receptor alpha (IL7RA) is among the top listed candidate genes influencing the risk to develop multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system. Soluble IL-7RA (sIL-7RA) protein and mRNA levels vary among the four common IL7RA haplotypes. Here we show and confirm that protective haplotype carriers have three times lower sIL-7RA serum levels than the other three haplotypes. High sIL-7RA concentrations significantly decrease IL-7-mediated STAT5 phosphorylation in CD4(+) T cells. Transcriptome analysis of unstimulated and stimulated CD4(+) T cells of MS patients carrying the different IL7RA haplotypes revealed complex and overlapping patterns in genes participating in cytokine signaling networks, apoptosis, cell cycle progression and cell differentiation. Our findings indicate that genetic variants of IL7RA result in haplotype-associated differential responsiveness to immunological stimuli that influence MS susceptibility not exclusively by varying levels of sIL-7RA.

Perspectives of the relationship between IL-7 and autoimmune diseases

Interleukin (IL)-7 is one of the IL-2 family cytokines comprised of IL-2, IL-4, IL-7, IL-9, IL-15, as well as IL-21. IL-7 is mainly secreted by stroma cells in primary lymphoid tissues, playing an essential role in the program of T cell development. Recently, studies have revealed that physiological function exerted by immunocytes can be influenced by aberrant IL-7 signaling, which is common in abnormal autoimmunity regulation. There is also increasing evidence that IL-7 is involved in several autoimmune diseases, such as rheumatoid arthritis, type I diabetes, multiple sclerosis and systemic lupus erythematosus, etc. Targeting components in IL-7 signaling pathways may have potential significance for treating numerous autoimmune diseases. In this review, we therefore summarize our current understandings regarding the relationship between IL-7 and autoimmune diseases so as to render more valuable information on this kind of research.

Interleukin-7: Fuel for the autoimmune attack

Interleukin-7 (IL-7) is a critical survival factor for lymphocytes and recent studies suggest targeting the IL-7/IL-7Rα pathway holds promise for the treatment of autoimmune diseases. Several lines of evidence, genetic as well as functional, indicate an important role for this cytokine in autoimmune inflammation: polymorphisms in the IL-7Rα have been associated with increased risk for autoimmune disease and blocking IL-7/IL-7Rα with antibodies showed therapeutic efficacy in several autoimmune mouse models. Insights are starting to emerge about the mechanisms underlying IL-7's role in autoimmunity and tolerance, revealing surprising novel functions beyond its traditional activity as a T cell survival factor. In the first part of this review, the functions of IL-7 in the immune system are concisely described, providing a basis for understanding their potential role in promoting autoimmune responses. In the second part, current knowledge about the role of IL-7 in various autoimmune conditions is reviewed.

Osteoimmunology and the influence of pro-inflammatory cytokines on osteoclasts

Bone and immune system are functionally interconnected. Immune and bone cells derive from same progenitors in the bone marrow, they share a common microenvironment and are being influenced by similar mediators. The evidence on increased bone resorption associated with inappropriate activation of T cells such as during inflammation, is well established. However, the molecular mechanisms beyond this clinical observation have begun to be intensively studied with the advancement of osteoimmunology. Now days, we have firm evidence on the influence of numerous proinflammatory cytokines on bone cells, with the majority of data focused on osteoclasts, the bone resorbing cells. It has been shown that some proinflammatory cytokines could possess osteoclastogenic and/or anti-osteoclastogenic properties and can target osteoclasts directly or via receptor activator of nuclear factor κB (RANK)/RANK ligand(RANKL)/osteoprotegerin (OPG) system. Several studies have reported opposing data regarding (anti)osteoclastogenic properties of these cytokines.

Therefore, the first part of this review is summarizing current evidence on the influence of pro-inflammatory cytokines on osteoclasts and thus on bone resorption. In the second part, the evidence on the role of pro-inflammatory cytokines in osteoporosis and osteoarthritis is reviewed to show that unravelling the mechanisms beyond such complex bone diseases, is almost impossible without considering skeletal and immune systems as an indivisible integrated system.

IL-7 receptor α expressing B cells act proinflammatory in collagen-induced arthritis and are inhibited by sympathetic neurotransmitters

OBJECTIVES

The sympathetic nervous system (SNS) as well as the interleukin (IL)-7/IL-7 receptor (IL-7R) system play a role in the pathogenesis of arthritis. However, the target cells and mechanisms involved are not fully resolved. The goal of this study was to determine if B cells are influenced by IL-7 and to investigate the possible interplay between the SNS and the IL-7/IL-7R system on B cells in arthritis.

METHODS

Collagen type II-induced arthritis (CIA) in DBA1 mice. ELISA to determine specific anti-CII antibodies. Fluorescence activated cell sorting (FACS) analysis to determine IL-7R+ cells and intracellular phosphorylated signal transducer and activator of transcription 5 (pSTAT5). Immunohistochemistry to show IL-7R+ B cells in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissue.

RESULTS

IL-7 stimulated IL-7R+ mature B cells act proinflammatory (increased clinical score, increased anticollagen type II antibodies) after cell transfer in CIA. The sympathetic neurotransmitter norepinephrine abrogates this effect. Expression of IL-7Rα is increased when B cells are activated (anti-CD40 or lipopolysaccharide) in vitro and stimulating the IL-7R induces intracellular accumulation of pSTAT5. α- And β-adrenergic agonists show no influence on expression levels of IL-7R on activated B cells; however, intracellular IL-7R downstream signalling is abrogated via the β2-adreonceptor (β2AR) agonist terbutaline. IL-7R and β2AR are also expressed on B cells in synovial tissue from RA and OA patients.

CONCLUSIONS

These data indicate that IL7R+ B cells have a proinflammatory role in arthritis which can be inhibited by the sympathetic neurotransmitter norepinephrine via inhibition of IL-7R signalling.

Characterization of interleukin-7 and interleukin-7 receptor in the pathogenesis of rheumatoid arthritis

OBJECTIVE

To characterize the expression of interleukin-7 (IL-7) and IL-7 receptor (IL-7R) in rheumatoid arthritis (RA) synovial tissue and to examine their regulation and pathogenic role in macrophages, endothelial cells, and synovial tissue fibroblasts in RA.

METHODS

Expression of IL-7 and IL-7R in RA and normal synovial tissue was demonstrated by immunohistochemistry. Expression and regulation of IL-7 and IL-7R in RA peripheral blood in vitro-differentiated macrophages, RA synovial tissue fibroblasts, and human microvascular endothelial cells (HMVECs) were determined by real-time reverse transcription-polymerase chain reaction and/or flow cytometry. Enzyme-linked immunosorbent assay was used to examine production of proangiogenic factors by IL-7-activated macrophages, RA fibroblasts, and endothelial cells.

RESULTS

IL-7 and IL-7R were coexpressed on RA synovial tissue lining and sublining macrophages and endothelial cells. Expression of IL-7 and its receptor was significantly elevated in RA synovial fluid and peripheral blood macrophages as well as RA fibroblasts, compared to normal cells. Toll-like receptor 4 ligation (with lipopolysaccharide) and tumor necrosis factor α (TNFα) stimulation modulated expression of IL-7 and IL-7R on RA macrophages and HMVECs. However, in RA fibroblasts, lipopolysaccharide and TNFα activation increased expression of IL-7R only. IL-7 also mediated RA pathogenesis by inducing production of potent proangiogenic factors from macrophages and endothelial cells.

CONCLUSION

We have identified, for the first time, regulators of IL-7 and IL-7R expression in RA fibroblasts, RA peripheral blood in vitro-differentiated macrophages, and endothelial cells. Our results document a novel role of IL-7 in RA angiogenesis.

IL-7- and IL-15-mediated TCR sensitization enables T cell responses to self-antigens

Regulation of the ERK pathway is intimately involved in determining whether TCR stimulation is productive or induces anergy. T cells from patients with rheumatoid arthritis (RA) have increased ERK responsiveness, which may be relevant for disease pathogenesis. Inflammatory cytokines such as TNF-α did not reproduce the TCR hypersensitivity typical for RA in T cells from healthy individuals. In contrast, priming with the homeostatic cytokines (HCs) IL-7 and IL-15 amplified ERK phosphorylation to TCR stimulation 2- to 3-fold. The underlying mechanism involved a priming of the SOS-dependent amplification loop of RAS activation. The sensitization of the TCR signaling pathway has downstream consequences, such as increased proliferation and preferential Th1 differentiation. Importantly, priming with IL-7 or IL-15 enabled T cell responses to autoantigens associated with RA. Production of HCs is induced in lymphopenic conditions, which have been shown to predispose for autoimmunity and which appear to be present in the preclinical stages of RA. We propose that HCs, possibly induced by lymphopenia, decrease the signaling threshold for TCR activation and are thereby partly responsible for autoimmunity in RA.

Interleukin-7-aggravated joint inflammation and tissue destruction in collagen-induced arthritis is associated with T-cell and B-cell activation

Introduction

We sought to investigate the capacity of interleukin (IL)-7 to enhance collagen-induced arthritis and to study by what mechanisms this is achieved.

Methods

Mice received multiple injections with IL-7 or phosphate-buffered saline (PBS) as a control. Arthritis severity and incidence were determined by visual examination of the paws. Joint destruction was determined by assessing radiographs and immunohistochemistry of the ankle joints. Total cellularity and numbers of T-cell and B-cell subsets were assessed, as well as ex vivo production of interferon-γ (IFN-γ), IL-17, and IL-4. Proinflammatory mediators were measured in serum with multianalyte profiling.

Results

IL-7 increased arthritis severity and radiology-assessed joint destruction. This was consistent with IL-7-increased intensity of cell infiltrates, bone erosions, and cartilage damage. Splenic CD19⁺ B cells and CD19⁺/GL7⁺ germinal center B cells, as well as CD4 and CD8 numbers, were increased by IL-7. IL-7 expanded memory T cells, associated with increased percentages of IFN-γ-, IL-4-, and IL-17-producing CD4⁺ T cells. On antigen restimulation of draining lymph node cells in vitro IL-7 treatment was found to increase IFN-γ and IL-17 production, whereas IL-4 was reduced. IL-7 also increased concentrations of proinflammatory mediators, indicative of T-cell activation (sCD40L), vascular activation (VCAM-1, VEGF), tissue destruction (fibroblast growth factor-basic (FGF-b), LIF), and chemotaxis (MIP-1γ, MIP-3β, lymphotactin, MDC, and MCP-5).

Conclusions

In arthritic mice, IL-7 causes expansion of T and B cells, associated with increased levels of proinflammatory mediators. IL-7 intensifies arthritis severity and joint destruction, accompanied by increased Th1 and Th17 activity. These data indicate that IL-7 could be an important mediator in arthritic conditions and that targeting IL-7 or its receptor represent novel therapeutic strategies.

The human IL-7 receptor gene: deletions, polymorphisms and mutations

Most T cell subsets depend on IL-7 for survival. IL-7 binds to IL-7Rα and γc, initiating the signaling cascade. Deletion of IL-7Ra in humans has, for some time, been known to cause severe combined immunodeficiency. More recently, polymorphisms in IL-7R have been shown be a risk factor for a number of diseases that are autoimmune or involve excess immune and inflammatory responses including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, primary biliary cirrhosis, inflammatory bowel disease, atopic dermatitis, inhalation allergy, sarcoidosis and graft-versus host disease. The polymorphism that affects risk to most of these immunopathologies is T244I at the border of the extracellular domain and the transmembrane region. The same region has recently been shown to harbor gain-of-function mutations in acute lymphoblastic leukemia. These studies have suggested new therapies that target the IL-7 pathway.

New factors controlling the balance between osteoblastogenesis and adipogenesis

The majority of conditions associated with bone loss, including aging, are accompanied by increased marrow adiposity possibly due to shifting of the balance between osteoblast and adipocyte differentiation in bone marrow stromal (skeletal) stem cells (MSC). In order to study the relationship between osteoblastogenesis and adipogenesis in bone marrow, we have characterized cellular models of multipotent MSC as well as pre-osteoblastic and pre-adipocytic cell populations. Using these models, we identified two secreted factors in the bone marrow microenviroment: secreted frizzled-related protein 1 (sFRP-1) and delta-like1 (preadipocyte factor 1) (Dlk1/Pref-1). Both exert regulatory effects on osteoblastogenesis and adipogenesis. Our studies suggest a model for lineage fate determination of MSC that is regulated through secreted factors in the bone marrow microenvironment that mediate a cross-talk between lineage committed cell populations in addition to controlling differentiation choices of multipotent MSC.

Interleukin 7 receptor gene polymorphisms and haplotypes are associated with susceptibility to IgA nephropathy in Korean children

An abnormal T-cell response is involved in the pathogenesis of various renal diseases. Survival of naïve T cells is dependent on interleukin 7 (IL7) and its receptor (IL7R). Thus, we investigated the association between IL7R single nucleotide polymorphisms (SNPs) and childhood IgA nephropathy (IgAN). We analyzed the genotypic distributions of two missense SNPs of IL7R, rs1494558 (Ile66Thr) and rs1494555 (Val138Ile), among 198 pediatric IgAN patients and 288 healthy controls. Haplotype analysis and measurement of pair-wise linkage disequilibrium were performed. In addition, the genotypes of patient subgroups, determined by the presence of nephrotic range proteinuria (>40 mg/m(2)/h) and pathological advancement, were analyzed. The genotyping data of IgAN patients and controls showed significant differences in rs1494558 (codominant, P=0.0003; dominant, P=0.0003) and rs1494555 (codominant, P=0.0038; dominant, P=0.0099). In the haplotype analysis, AC (codominant, P=0.0066) and GT (codominant, P=0.0005; dominant, P=0.0006) were significantly associated with susceptibility to IgAN. Furthermore, in the analysis of clinical subgroups of IgAN patients, rs1494558 was associated with nephrotic range proteinuria (codominant, P=0.027; recessive, P=0.023). Our results suggest that IL7R may be associated with disease susceptibility and proteinuria in childhood IgAN.

DLK1 is a novel regulator of bone mass that mediates estrogen deficiency-induced bone loss in mice

Delta-like 1/fetal antigen 1 (DLK1/FA-1) is a transmembrane protein belonging to the Notch/Delta family that acts as a membrane-associated or a soluble protein to regulate regeneration of a number of adult tissues. Here we examined the role of DLK1/FA-1 in bone biology using osteoblast-specific Dlk1-overexpressing mice (Col1-Dlk1). Col1-Dlk1 mice displayed growth retardation and significantly reduced total body weight and bone mineral density (BMD). Micro-computed tomographis (µCT) scanning revealed a reduced trabecular and cortical bone volume fraction. Tissue-level histomorphometric analysis demonstrated decreased bone-formation rate and enhanced bone resorption in Col1-Dlk1 mice compared with wild-type mice. At a cellular level, Dlk1 markedly reduced the total number of bone marrow (BM)-derived colony-forming units fibroblasts (CFU-Fs), as well as their osteogenic capacity. In a number of in vitro culture systems, Dlk1 stimulated osteoclastogenesis indirectly through osteoblast-dependent increased production of proinflammatory bone-resorbing cytokines (eg, Il7, Tnfa, and Ccl3). We found that ovariectomy (ovx)-induced bone loss was associated with increased production of Dlk1 in the bone marrow by activated T cells. Interestingly, Dlk1(-/-) mice were significantly protected from ovx-induced bone loss compared with wild-type mice. Thus we identified Dlk1 as a novel regulator of bone mass that functions to inhibit bone formation and to stimulate bone resorption. Increasing DLK1 production by T cells under estrogen deficiency suggests its possible use as a therapeutic target for preventing postmenopausal bone loss.