Important immunoregulatory role of interleukin-11 in the inflammatory process in rheumatoid arthritis

An optimized procedure for preparation of conditioned medium from Wharton's jelly mesenchymal stromal cells isolated from umbilical cord

Cell-free therapy based on conditioned medium derived from mesenchymal stromal cells (MSCs) has gained attention in the field of protective and regenerative medicine. However, the exact composition and properties of MSC-derived conditioned media can vary greatly depending on multiple parameters, which hamper standardization. In this study, we have optimized a procedure for preparation of conditioned medium starting from efficient isolation, propagation and characterization of MSCs from human umbilical cord, using a culture medium supplemented with human platelet lysate as an alternative source to fetal bovine serum. Our procedure successfully maximizes the yield of viable MSCs that maintain canonical key features. Importantly, under these conditions, the compositional profile and biological effects elicited by the conditioned medium preparations derived from these MSC populations do not depend on donor individuality. Moreover, approximately 120 L of conditioned medium could be obtained from a single umbilical cord, which provides a suitable framework to produce industrial amounts of toxic-free conditioned medium with predictable composition.

Emerging roles for IL-11 in inflammatory diseases

Interleukin-11 (IL-11) is a cytokine that has been strongly implicated in the pathogenesis of fibrotic diseases and solid malignancies. Elevated IL-11 expression is also associated with several non-malignant inflammatory diseases where its function remains less well-characterized. Here, we summarize current literature surrounding the contribution of IL-11 to the pathogenesis of autoimmune inflammatory diseases, including rheumatoid arthritis, multiple sclerosis, diabetes and systemic sclerosis, as well as other chronic inflammatory conditions such as periodontitis, asthma, chronic obstructive pulmonary disease, psoriasis and colitis.

Expression profiling of genes in rheumatoid fibroblast-like synoviocytes regulated by Fas ligand via cDNA microarray analysis

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in synovial tissues. Hyperplasia of synovial tissues leads to the formation of pannus that invades the joint cartilage and bone, resulting in joint destruction. Fas ligand (FasL), which is a member of the tumor necrosis factor superfamily, contributes to the pathogenesis of autoimmune diseases, including RA. The current study attempted to identify genes whose expressions in rheumatoid fibroblast-like synoviocytes (RA-FLS) were regulated by FasL, using cDNA microarray. A total of four individual lines of primary cultured RA-FLS were incubated either with recombinant human FasL protein or PBS as an unstimulated control for 12 h. Gene expression was detected using a microarray assay. The results revealed the expression profiles of genes in RA-FLS regulated by Fas and investigated the functions of the genes that were regulated. Among the genes in this profile, the mRNA expression changes of the following genes were indicated to be of note using RT-qPCR: Dual specificity phosphatase 6, epiregulin, interleukin 11, angiopoietin-like 7, protein inhibitor of activated STAT 2 and growth differentiation factor 5. These genes may affect the pathogenesis of RA by affecting apoptosis, proliferation, cytokine production, cytokine-induced inflammation, intracellular signaling, angiogenesis, bone destruction and chondrogenesis. To the best of our knowledge, the current study is the first study to reveal the expression profile of genes in RA-FLS regulated by FasL. The data demonstrated that FasL may regulate the expression of a number of key molecules in RA-FLS, thus affecting RA pathogenesis. Further studies of the genes detected may improve the understanding of RA pathogenesis and provide novel treatment targets for RA.

Conditions Mimicking the Cancer Microenvironment Modulate the Functional Outcome of Human Chorionic Villus Mesenchymal Stem/Stromal Cells in vitro

Mesenchymal stem/stromal cells isolated from chorionic villi of human term placentae (CV-MSCs) possess unique biological characters. They exhibit self-renewal, directional migration, differentiation, and immunomodulatory effects on other cell lineages, by virtue of which they can be utilized as therapeutic carriers, for drug targeting, and therapy. Tumors display characteristic features of a damaged tissue microenvironment, which is saturated with conditions such as hypoxia, sustained inflammation, and increased oxidative stress. CV-MSCs function normally in a high oxidative stress environment induced by hydrogen peroxide (H₂O₂) and glucose and also protect endothelial cells from their damaging effects. For their therapeutic applications in a disease like cancer, it is necessary to ascertain the effects of tumor microenvironment on their functional outcome. In this study, we investigated the functional activities, of CV-MSCs in response to conditioned media (CM) obtained from the culture of breast cancer cell line MDA-231 (CM-MDA231). CV-MSCs were exposed to CM-MDA231 for different spatio-temporal conditions, and their biological functions as well as modulation in gene expression were evaluated. Effect of CM-MDA231 on factors responsible for changes in functional outcome were also investigated at the protein levels. CV-MSCs exhibited significant reduction in proliferation but increased adhesion and migration after CM-MDA231 treatment. Interestingly, there was no change in their invasion potential. CM-MDA231 treatment modulated expression of various genes involved in important cellular events including, integration, survival, message delivery and favorable outcome after transplantation. Analysis of pathways related to cell cycle regulation revealed significant changes in the expression of p53, and increased phosphorylation of Retinoblastoma (Rb) and Checkpoint Kinase 2 in CV-MSCs treated with CM-MDA231. To summarize, these data reveal that CV-MSCs retain the ability to survive, adhere, and migrate after sustained treatment with CM-MDA231, a medium that mimics the cancer microenvironment. These properties of CV-MSCs to withstand the inflammatory tumor like microenvironment prove that they may make useful candidate in a stem cell based therapy against cancer. However, further pre-clinical studies are needed to validate their therapeutic usage.

Hiding in Plain Sight: Interleukin-11 Emerges as a Master Regulator of Fibrosis, Tissue Integrity, and Stromal Inflammation

Interleukin (IL)-11 is upregulated in a wide variety of fibro-inflammatory diseases such as systemic sclerosis, rheumatoid arthritis, pulmonary fibrosis, inflammatory bowel disease, kidney disease, drug-induced liver injury, and nonalcoholic steatohepatitis. IL-11 is a member of the IL-6 cytokine family and has several distinct properties that define its unique and nonredundant roles in disease. The IL-11 receptor is highly expressed on stromal, epithelial and polarized cells, where noncanonical IL-11 signaling drives the three pathologies common to all fibro-inflammatory diseases-myofibroblast activation, parenchymal cell dysfunction, and inflammation-while also inhibiting tissue regeneration. This cytokine has been little studied, and publications on IL-11 peaked in the early 1990s, when it was largely misunderstood. Here we describe recent advances in our understanding of IL-11 biology, outline how misconceptions as to its function came about, and highlight the large potential of therapies targeting IL-11 signaling for treating human disease.

Correlations Between Interleukin-11 Expression and Hypertensive Kidney Injury in a Rat Model of Renovascular Hypertension

BACKGROUND

Interleukin-11 (IL-11) is a pleiotropic cytokine of the interleukin-6 family. Recent studies revealed its crucial role in the development of cardiovascular fibrosis. In this study we examined IL-11 expression levels in the heart and the kidney exposed to high blood pressure in renovascular hypertensive rats and their correlations to fibrotic markers and kidney injury.

METHODS

Two-kidney, one-clip renovascular hypertension (2K1C) was induced in rats. IL-11 expression was measured by real-time polymerase chain reaction in the left ventricle and the right kidney. The correlation of cardiac IL-11 expression with biomarkers of renal fibrosis was assessed. We further investigated IL-11 expression in 2K1C rats grouped into rats with malignant vs. nonmalignant hypertension (distinguishing criteria: weight loss, number of fibrinoid necrosis, and onion skin lesions).

RESULTS

Thirty-five days after clipping, mean arterial pressure was significantly increased in 2K1C. Renal IL-11 expression was elevated in 2K1C. In the heart there was only a trend toward higher IL-11 expression in 2K1C. IL-11 in the kidney in 2K1C correlated with the expression of transforming growth factor (TGF)-β1/2, collagens, fibronectin, osteopontin, as well as tissue inhibitors of metalloprotease 1/2. There were also correlations of IL-11 with tissue collagen expansion, number of activated fibroblasts and serum creatinine, but no correlation with mean arterial pressure. Renal expression of IL-11 was highest in rats with malignant hypertension.

CONCLUSIONS

Renal IL-11 expression of renovascular hypertensive rats is markedly increased and correlates with profibrotic markers and loss of function and might therefore serve as a biomarker for the severity of hypertensive nephrosclerosis.

Anti-inflammatory and immune-regulatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a failure of spontaneous resolution of inflammation. Although the pro-inflammatory cytokines and mediators that trigger RA have been the focus of intense investigations, the regulatory and anti-inflammatory cytokines responsible for the suppression and resolution of disease in a context-dependent manner have been less well characterized. However, knowledge of the pathways that control the suppression and resolution of inflammation in RA is clinically relevant and conceptually important for understanding the pathophysiology of the disease and for the development of treatments that enable long-term remission. Cytokine-mediated processes such as the activation of T helper 2 cells by IL-4 and IL-13, the resolution of inflammation by IL-9, IL-5-induced eosinophil expansion, IL-33-mediated macrophage polarization, the production of IL-10 by regulatory B cells and IL-27-mediated suppression of lymphoid follicle formation are all involved in governing the regulation and resolution of inflammation in RA. By better understanding these immune-regulatory signalling pathways, new therapeutic strategies for RA can be envisioned that aim to balance and resolve, rather than suppress, inflammation.

Cancer Conditioned Medium Modulates Functional and Phenotypic Properties of Human Decidua Parietalis Mesenchymal Stem/Stromal Cells

Background

Mesenchymal Stem/Stromal Cells (MSCs) from the decidua parietalis (DPMSCs) of human term placenta express several molecules with important biological and immunological properties. DPMSCs induce natural killer cell expression of inflammatory receptors and their cytotoxic activity against cancer cells. These properties make DPMSCs promising therapeutical agent for cancer. The successful development of MSCs as an anti-cancer therapeutic cells rely on their ability to function in a hostile inflammatory and oxidative stress cancer environment. Here, we studied the effects of conditioned medium obtained from the culture of breast cancer cells (CMMDA-231) on the functional and phenotypic properties of DPMSCs.

Methods

DPMSCs were cultured with CMMDA-231 and important functions of DPMSCs were measured. The effect of CMMDA-231 on DPMSC expression of several genes with different functions was also evaluated.

Results

DPMSCs were able to function in response to CMMDA-231, but with reduced proliferative and adhesive potentials. Preconditioning of DPMSCs with CMMDA-231 enhanced their adhesion while reducing their invasion. In addition, CMMDA-231 modulated DPMSC expression of many genes with various functional (i.e., proliferation, adhesion, and invasion) properties. DPMSCs also showed increased expression of genes with anti-cancer property.

Conclusion

These data show the ability of DPMSCs to survive and function in cancer environment. In addition, preconditioning of DPMSCs with CMMDA-231 enhanced their anti-cancer properties and thus demonstrating their potential as an anti-cancer therapeutic agent. However, future studies are essential to reveal the mechanism underlying the effects of MDA-231 on DPMSC functional activities and also to confirm the anti-cancer therapeutic potential of DPMSCs.

Assessment of CCL27 and IL-11 in Multiple Sclerosis Patients Treated with Interferon-β and Glatiramer Acetate

INTRODUCTION

Multiple sclerosis (MS) is a neuroinflammatory autoimmune disease which involves the central nervous -system. Although the primary cause of MS is obscure, effects of some cytokine and chemokine patterns in both innate and adaptive immune systems have been described. -Objectives: Since limited studies have examined the role of interleukin (IL)-11 and chemokine CCL27 in MS, we aimed to identify changes in IL-11 and CCL27 gene expression and serum levels in relapsing-remitting MS (RRMS) patients, treated with interferon (IFN)-β and glatiramer acetate (GA).

METHODS

The serum level and gene expression of IL-11 and CCL27 were measured and compared between treatment-naïve MS patients and RRMS patients who were treated with high-dose IFN-β1a, low-dose IFN-β1a, IFN-β1b, and GA via enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction.

RESULTS

A significant decrease was observed in the serum level of CCL27 in treatment-naïve patients and IFN-β1b-treated patients compared to the healthy controls. On the other hand, a significant increase was found in the protein level of CCL27 in low-dose and high-dose IFN-β1a groups compared to the treatment-naïve group. In addition, CCL27 gene expression was higher in patients treated with GA than in the treatment-naïve group. There were no significant changes in the gene expression or protein level of IL-11 in all experimental groups. Additionally, a positive correlation was found between IL-11 and CCL-27.

CONCLUSION

Our results suggest the inflammatory role of CCL27 in MS patients, while IFN-β1a seems to play a compensatory role for this chemokine.

IL-11 facilitates a novel connection between RA joint fibroblasts and endothelial cells

IL-11 has been detected in inflamed joints; however, its role in the pathogenesis of arthritis is not yet clear. Studies were conducted to characterize the expression and functional significance of IL-11 and IL-11Rα in rheumatoid arthritis (RA). IL-11 levels were elevated in RA synovial fluid (SF) compared to osteoarthritis (OA) SF and plasma from RA, OA and normal individuals (NLs). Morphologic studies established that IL-11 was detected in lining fibroblasts and macrophages in addition to sublining endothelial cells and macrophages at higher levels in RA compared to NL synovial tissues. Since IL-11Rα was exclusively expressed in RA fibroblasts and endothelial cells, macrophages were not involved in IL-11 effector function. Ligation of IL-11 to IL-11Rα strongly provoked fibroblast infiltration into RA joint, while cell proliferation was unaffected by this process. Secretion of IL-8 and VEGF from IL-11 activated RA fibroblasts was responsible for the indirect effect of IL-11 on endothelial cell transmigration and tube formation. Moreover, IL-11 blockade impaired RA SF capacity to elicit endothelial cell transmigration and tube formation. We conclude that IL-11 binding to endothelial IL-11Rα can directly induce RA angiogenesis. In addition, secretion of proangiogenic factors from migrating fibroblasts potentiated by IL-11 can indirectly contribute to RA neovascularization.

IL-27: a double agent in the IL-6 family

The cytokine interleukin (IL)-6 is a major therapeutic target for the treatment of various inflammatory and autoimmune diseases. While IL-6 receives considerable attention in studies of innate and adaptive immunity, the IL-6-related family member IL-27 is recognized increasingly for its effects on cellular proliferation, differentiation and leucocyte effector functions. Both cytokines activate responses in myeloid and stromal tissue cells, where they direct the transition from innate to adaptive immunity. However, they are identified frequently as lymphokines that control responses in T cells and B cells. In this regard, IL-27 often opposes the action of IL-6. Here, we will review the role of IL-6 and IL-27 in inflammation, with a particular focus on inflammatory arthritis, and discuss their importance in the diagnosis, stratification and treatment of autoimmune disease.

Suppression of endotoxin-inducible cytokines in whole blood from human subjects following single dose of recombinant human interleukin-11

To determine whether a single injection of recombinant human interleukin-11 (rhIL-11) to human subjects would affect endotoxin-inducible cytokine production, 6 dialysis-dependent patients with renal failure and 4 healthy volunteers were subcutaneously injected with rhIL-11 (50 µg/kg). The circulating concentrations of rhIL-11 remained at a constant level of approximately 12 ng/ml for 0.25—6 h in healthy volunteers but were 2-fold higher in dialysis-dependent patients. Venous blood obtained before and after rhIL-11 was stimulated with 10 ng/ml of LPS for 24 h at 37°C and production of TNFα, IL-1β, and IL-8 determined. The maximum suppression of IL-1β, TNFα and IL-8 production (66%, 24% and 58%, respectively) was observed 1 h after rhIL-11 administration. After 24 h, when circulating concentration of rhIL-11 had decreased to near pre-injection levels, LPS-induced TNFα and IL-1β production remained suppressed (56 ± 17%, P < 0.05; 46 ± 4.7, P<0.01, respectively) but returned to baseline at 48 h. These findings suggest that there is a therapeutic benefit of single doses of rhIL-11 in reducing LPS-induced IL-1β and TNFα production.

NF-κB and HIF crosstalk in immune responses

Hypoxia and inflammation have been associated with a number of pathological conditions, in particular inflammatory diseases. While hypoxia is mainly associated with the activation of hypoxia‐inducible factors (HIFs), inflammation activates the family of transcription factor called nuclear factor‐kappa B (NF‐κB). An extensive crosstalk between these two main molecular players involved in hypoxia and inflammation has been demonstrated. This crosstalk includes common activating stimuli, shared regulators and targets. In this review, we discuss the current understanding of the role of NF‐κB and HIF in the context of the immune response. We review the crosstalk between HIF and NF‐κB in the control of the immune response in different immune cell types including macrophages, neutrophils and B and T cells. Furthermore the importance of the molecular crosstalk between HIFs and NF‐κB for a variety of medical conditions will be discussed.

Complex pattern of interleukin-11-induced inflammation revealed by mathematically modeling the dynamics of C-reactive protein

Inflammation underlies many diseases and is an undesired effect of several therapy modalities. Biomathematical modeling can help unravel the complex inflammatory processes and the mechanisms triggering their emergence. We developed a model for induction of C-reactive protein (CRP), a clinically reliable marker of inflammation, by interleukin (IL)-11, an approved cytokine for treatment of chemotherapy-induced thrombocytopenia. Due to paucity of information on the mechanisms underlying inflammation-induced CRP dynamics, our model was developed by systematically evaluating several models for their ability to retrieve variable CRP profiles observed in IL-11-treated breast cancer patients. The preliminary semi-mechanistic models were designed by non-linear mixed-effects modeling, and were evaluated by various performance criteria, which test goodness-of-fit, parsimony and uniqueness. The best-performing model, a robust population model with minimal inter-individual variability, uncovers new aspects of inflammation dynamics. It shows that CRP clearance is a nonlinear self-controlled process, indicating an adaptive anti-inflammatory reaction in humans. The model also reveals a dual IL-11 effect on CRP elevation, whereby the drug has not only a potent immediate influence on CRP incline, but also a long-term influence inducing elevated CRP levels for several months. Consistent with this, model simulations suggest that periodic IL-11 therapy may result in prolonged low-grade (chronic) inflammation post treatment. Future application of the model can therefore help design improved IL-11 regimens with minimized long-term CRP toxicity. Our study illuminates the dynamics of inflammation and its control, and provides a prototype for progressive modeling of complex biological processes in the medical realm and beyond.

Bovine lactoferricin-induced anti-inflammation is, in part, via up-regulation of interleukin-11 by secondary activation of STAT3 in human articular cartilage

Bovine lactoferricin (LfcinB), a multifunctional peptide, was recently demonstrated to be anti-catabolic and anti-inflammatory in human articular cartilage. LfcinB blocks IL-1-mediated proteoglycan depletion, matrix-degrading enzyme expression, and pro-inflammatory mediator induction. LfcinB selectively activates ERK1/2, p38 (but not JNK), and Akt signaling. However, the relationship between these pathways and LfcinB target genes has never been explored. In this study, we uncovered the remarkable ability of LfcinB in the induction of an anti-inflammatory cytokine, IL-11. LfcinB binds to cell surface heparan sulfate to initiate ERK1/2 signaling and activate AP-1 complexes composed of c-Fos and JunD, which transactivate the IL-11 gene. The induced IL-11 functions as an anti-inflammatory and chondroprotective cytokine in articular chondrocytes. Our data show that IL-11 directly attenuates IL-1-mediated catabolic and inflammatory processes ex vivo and in vitro. Moreover, IL-11 activates STAT3 signaling pathway to critically up-regulate TIMP-1 expression, as a consecutive secondary cellular response after IL-11 induction by LfcinB-ERK-AP-1 axis in human adult articular chondrocytes. The pathological relevance of IL-11 signaling to osteoarthritis is evidenced by significant down-regulation of its cognate receptor expression in osteoarthritic chondrocytes. Together, our results suggest a two-step mechanism, whereby LfcinB induces TIMP-1 through an IL-11-dependent pathway involving transcription factor AP-1 and STAT3.

What Have We Learned about the Pathogenesis of Rheumatoid Arthritis from TNF-Targeted Therapy?

Studies of cytokine regulation in rheumatoid arthritis led to the development of TNFα inhibitors which are now used for a number of indications, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, psoriatic arthritis, and ankylosing spondylitis. The widespread use of biologics in the clinic offers unique opportunities for probing disease pathogenesis and this paper provides an overview of rheumatoid arthritis, with a particular emphasis on the impact of anti-TNFα therapy on pathogenetic mechanisms. An overview is also provided on the most commonly used animal models that mimic RA, including adjuvant-induced arthritis, collagen-induced arthritis, TNFα-transgenic mice, and the K/BxN and SKG models. These models have led to significant discoveries relating to the importance of pro-inflammatory cytokines in the pathogenesis of rheumatoid arthritis, resulting from disregulation of the normally finely tuned balance of pro- and anti-inflammatory cytokine signalling. In addition, experimental evidence is discussed suggesting how genetic and environmental factors can contribute to disease susceptibility. The role of effector and regulatory T cells is discussed in the light of the relatively disappointing therapeutic effects of T cell modifying agents such as anti-CD4 antibody and cyclosporin. It is concluded that comprehensive analyses of mechanisms of action of biologics and other drugs entering the clinic will be essential to optimise therapy, with the ultimate aim of providing a cure.

Gingival crevicular fluid and plasma acute-phase cytokine levels in different periodontal diseases

BACKGROUND

The aim of the present study is to investigate gingival crevicular fluid (GCF) and plasma acute-phase cytokines, interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-11 (IL-11), oncostatin M (OSM), and leukemia inhibitory factor (LIF) levels in patients with different periodontal diseases.

METHODS

Eighty individuals were included in this study; 20 with chronic periodontitis (CP), 20 with generalized aggressive periodontitis (GAgP), 20 with gingivitis, and 20 classified as healthy (H). Probing depth, clinical attachment level, plaque index, and papilla bleeding index were recorded. Plasma and GCF IL-1β, IL-6, IL-11, OSM, and LIF levels were analyzed by enzyme-linked immunosorbent assay.

RESULTS

CP and GAgP groups had significantly higher GCF IL-1β, IL-6, and IL-11 levels when compared with the H group (P <0.05). Conversely, GCF LIF levels of the CP and GAgP groups were lower than those of the H group (P <0.05). GCF OSM levels did not differ significantly among study groups. Plasma levels of all the cytokines studied were not significantly different among the study groups.

CONCLUSIONS

Based on the present data, elevated IL-1β, IL-6, and IL-11 GCF levels, but not plasma levels, are suggested as reliable inflammatory biomarkers in periodontal diseases. Decreased LIF levels in diseased groups might reflect the possible beneficial effects of LIF in the modulation of inflammatory response in gingiva.

Therapeutic strategies for the clinical blockade of IL-6/gp130 signaling

The successful treatment of certain autoimmune conditions with the humanized anti-IL-6 receptor (IL-6R) antibody tocilizumab has emphasized the clinical importance of cytokines that signal through the β-receptor subunit glycoprotein 130 (gp130). In this Review, we explore how gp130 signaling controls disease progression and examine why IL-6 has a special role among these cytokines as an inflammatory regulator. Attention will be given to the role of the soluble IL-6R, and we will provide a perspective into the clinical blockade of IL-6 activity in autoimmunity, inflammation, and cancer.

The correlation between increased serum concentrations of interleukin-6 family cytokines and disease activity in rheumatoid arthritis patients

PURPOSE

This study was performed to determine whether the serum concentrations of interleukin (IL)-6 family cytokines are elevated in patients with rheumatoid arthritis (RA) and to investigate the relationship between IL-6 family cytokine levels and disease activity in RA patients.

MATERIALS AND METHODS

We obtained serum samples from 40 patients with RA and 40 age- and sex- matched healthy controls, and we assessed the clinical parameters of disease activity, including the 28-joint disease activity score (DAS28) and C-reactive protein (CRP) levels. Serum samples from five patients with high disease activity (DAS28 > 5.1) were also collected at the eighth week of treatment. Serum concentrations of IL-6, IL-11, and leukemia inhibitory factor (LIF) were measured using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum concentrations of IL-6 family cytokines, including IL-6, IL-11, and LIF, were significantly elevated in patients with RA compared to those of healthy controls. Although there was no significant relationship between IL-6 family cytokine levels and DAS28, the IL-6 levels of patients with RA showed a significant correlation with CRP levels. After eight weeks of medical treatment in patients with high disease activity, a decrease in DAS28 was associated with a significant decrease in the serum concentrations of IL-6 and IL-11.

CONCLUSION

The serum concentrations of IL-6 family cytokines were significantly elevated in patients with RA, and they decreased with medical treatment. These findings suggest a possible role for IL-6 family cytokines in the pathogenesis of RA.

Monocyte activation by apoptotic cells removal in systemic lupus erythematosus patients

Decreased apoptotic cells (ACs) removal has been described as relevant in systemic lupus erythematosus (SLE) pathogenesis. Binding/phagocytosis of ACs was decreased in SLE patients. Blocking experiments suggested a role for CD36 in ACs clearance in healthy controls, not observed in SLE patients. Binding/phagocytosis of ACs induced the production of IL-6, CXCL8 and CCL22 in patients and controls and IL-1β, TNF-α and CCL3 only in healthy controls. ACs clearance induced an increase in CD80 and a decrease in CD86 expression in healthy controls and atherosclerotic patients. However, SLE patients did not up-regulate CD80 expression. The number and expression of CD36 and CD163 in monocytes was not different between the groups. ACs removal induced a down-regulation of CD36 expression in adherent HLA-DR(+) cells in SLE patients but not healthy controls. The decreased binding/phagocytosis of ACs observed in SLE patients, induces a distinct immune response compared with healthy controls.

SIGIRR/TIR-8 is an inhibitor of Toll-like receptor signaling in primary human cells and regulates inflammation in models of rheumatoid arthritis

OBJECTIVE

Single-immunoglobulin interleukin-1 receptor-related (SIGIRR), which is also known as Toll/interleukin-1 receptor 8 (TIR-8), is a member of the TIR domain-containing family of receptors and was first characterized as an inhibitor of interleukin-1 receptor (IL-1R) and Toll-like receptor (TLR) signaling. In the Dextran sulfate sodium-induced colitis model, SIGIRR(-/-) mice were shown to have increased inflammation and to be more susceptible to endotoxin challenge. Increasing evidence implicates TLR and IL-1R signaling in the pathology of rheumatoid arthritis (RA). Therefore, the purpose of this study was to investigate the involvement of SIGIRR in regulating inflammation in disease-relevant models.

METHODS

Primary human monocyte-derived macrophages and dendritic cells (DCs) were used to overexpress SIGIRR as well as to knock down endogenously expressed SIGIRR using small interfering RNAs. SIGIRR was also overexpressed in synovial cells derived from RA patients. To investigate the role of SIGIRR in vivo, zymosan-induced arthritis (ZIA) and collagen antibody-induced arthritis (CAIA) were induced in SIGIRR-knockout mice.

RESULTS

SIGIRR overexpression inhibited TLR-induced cytokine production in macrophages and DCs, while SIGIRR knockdown resulted in increased cytokine production following TLR stimulation. Moreover, SIGIRR overexpression inhibited the spontaneous release of cytokines by human RA synovial cells. The role of SIGIRR as an inhibitor of inflammation was confirmed in vivo, since SIGIRR(-/-) mice developed a more severe disease in both the ZIA and CAIA models.

CONCLUSION

Our study is the first to show the expression pattern and function of SIGIRR in primary human cells. Furthermore, this investigation defines the role of SIGIRR in disease-relevant cell types and demonstrates that SIGIRR is a potential therapeutic target for RA.

Murine J774 macrophages recognize LPS/IFN-g, non-CpG DNA or two-CpG DNA-containing sequences as immunologically distinct

Specific bacterial lipopolysaccharides (LPS), IFN-gamma, and unmethylated cytosine or guanosine-phosphorothioate containing DNAs (CpG) activate host immunity, influencing infectious responses. Macrophages detect, inactivate and destroy infectious particles, and synthetic CpG sequences invoke similar responses of the innate immune system. Previously, murine macrophage J774 cells treated with CpG induced the expression of nitric oxide synthase 2 (NOS2) and cyclo-oxygenase 2 (COX2) mRNA and protein. In this study murine J774 macrophages were exposed to vehicle, interferon gamma+lipopolysaccharide (IFN-g/LPS), non-CpG (SAK1), or two-CpG sequence-containing DNA (SAK2) for 0-18h and gene expression changes measured. A large number of immunostimulatory and inflammatory changes were observed. SAK2 was a stronger activator of TNFalpha- and chemokine expression-related changes than LPS/IFN-g. Up regulation included tumor necrosis factor receptor superfamily genes (TNFRSF's), IL-1 receptor signaling via stress-activated protein kinase (SAPK), NF-kappaB activation, hemopoietic maturation factors and sonic hedgehog/wingless integration site (SHH/Wnt) pathway genes. Genes of the TGF-beta pathway were down regulated. In contrast, LPS/IFN-g-treated cells showed increased levels for TGF-beta signaling genes, which may be linked to the observed up regulation of numerous collagens and down regulation of Wnt pathway genes. SAK1 produced distinct changes from LPS/IFN-g or SAK2. Therefore, J774 macrophages recognize LPS/IFN-g, non-CpG DNA or two-CpG DNA-containing sequences as immunologically distinct.

Immunobiology of asthma

Asthma is characterized by chronic inflammation of the airways in which there is an overabundance of eosinophils, mast cells, and activated T helper lymphocytes. These inflammatory cells release mediators that then trigger bronchoconstriction, mucus secretion, and remodeling. The inflammatory mediators that drive this process include cytokines, chemokines, growth factors, lipid mediators, immunoglobulins, and histamine. The inflammation in allergic asthma can be difficult to control. This is mainly due to the development of an adaptive immunity to an allergen, leading to immunological memory. This leads to recall reactions to the allergen, causing persistent inflammation and damage to the airways. Generally, in asthma inflammation is directed by Th2 cytokines, which can act by positive feedback mechanisms to promote the production of more inflammatory mediators including other cytokines and chemokines. This review discusses the role of cytokines and chemokines in the immunobiology of asthma and attempts to relate their expression to morphological and functional abnormalities in the lungs of asthmatic subjects. We also discuss new concepts in asthma immunology, in particular the role of cytokines in airway remodeling and the interaction between cytokines and infection.

Interleukin-10 regulates TNF-alpha-converting enzyme (TACE/ADAM-17) involving a TIMP-3 dependent and independent mechanism

IL-10 is a potent anti-inflammatory molecule, which regulates TNF-alpha at multiple levels. We investigated whether IL-10 also modulated the activity of the TNF-alpha-converting enzyme (TACE). Using an ex vivo fluorogenic assay we observed that LPS rapidly induced TACE activity in monocytes coinciding with release of soluble TNF-alpha. In the presence of IL-10, TNF-alpha production and activation of surface TACE was significantly inhibited. Paradoxically, both LPS with or without IL-10 led to accumulation of surface TACE (albeit catalytically inactive) over a 24 h period. We investigated whether this was mediated through induction of endogenous tissue inhibitor metalloproteinase-3 (TIMP-3). We found that the inhibition of TACE activity at 2 h by IL-10 was not TIMP-3 dependent but that the late accumulation of surface TACE was prevented with TIMP-3 antibodies. Furthermore, induction of endogenous TIMP-3 was observed by western blotting in both LPS- and in LPS with IL-10-treated monocytes from 6 to 8 h of culture. These results indicate that IL-10 further regulates TNF-alpha by modulating TACE activation at early time points and by contributing to the induction of TIMP-3, the natural inhibitor of active TACE, at later time points. These observations add to our understanding of inflammation and the importance of homeostatic regulators of these events.

Fish oil decreases matrix metalloproteinases in knee synovia of dogs with inflammatory joint disease

This study was designed to determine whether dietary fish oil affects the expression and activity of matrix metalloproteinases (MMP), tissue inhibitors of MMP-2 (TIMP-2) and urokinase plasminogen activator (uPA) in synovial fluid from dogs with spontaneously occurring stifle (knee) instability in a single hind limb resulting from acute cranial cruciate ligament (CCL) injury. Two groups of 12 dogs were fed diets from 1 week prior to surgery on the affected knee to 56 days post-surgery. The fish oil and control diets provided 90 and 4.5 mg, respectively, of combined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)/kg body weight per day. Plasma and synovial fluid, from both surgical and nonsurgical knee joints, were obtained at start of the diet (-7), surgery day (0) and 7, 14, 28 and 56 days post-surgery. Plasma total EPA and DHA were significantly increased, and plasma total arachidonic acid (AA) was significantly decreased by the fish oil diet. In synovial fluid from the nonsurgical knee, fish oil treatment significantly decreased proMMP-2 expression at Days 7 and 14, and proMMP-9 expression at Day 56, and uPA activity at 28 days and significantly increased TIMP-2 expression at Days 7 and 28. There were no differences in MMP expression or activity, TIMP-2 expression and uPA activity in the surgical joint synovial fluid at any time throughout the study. These results suggest that dietary fish oil may exert beneficial effects on synovial fluid MMP and TIMP-2 equilibrium in the uninjured stifle of dogs with unilateral CCL injury.

Pathogenesis and therapy of rheumatoid arthritis

Rheumatoid arthritis is a chronic disabling disease affecting at least 1% of the population on a worldwide basis. Research aimed at understanding the pathogenesis of this disease led to the identification of TNFalpha as a major pro-inflammatory cytokine expressed in the inflamed joints of patients with rheumatoid arthritis. Subsequently, in vitro studies provided evidence to suggest that TNFalpha played an important role in driving the expression of additional pro-inflammatory cytokines, such as IL-1, GM-CSF, IL-6, and IL-8, in synovial cell cultures. Another important finding that confirmed the pathological significance of TNFalpha was that mice genetically engineered to overexpress TNFalpha spontaneously developed arthritis. Subsequently, the therapeutic effect TNFalpha blockade was tested in animal models prior to clinical trials in human patients, which provided unequivocal verification of the validity of TNFalpha as a therapeutic target. Anti-TNFalpha therapy is now accepted as a fully-validated treatment modality for rheumatoid arthritis.

[Cytokines]

Cytokine driven inflammation is a common feature in autoimmune diseases. Cytokines are needed under physiological conditions within the innate and adaptive immune systems to control infectious diseases and neoplastic disorders by regulation of the cell cycle and apoptosis. Cytokines can also be found in persistently increased concentrations in inflamed tissues within autoimmune diseases. Therefore, the modulation of cytokines seems to be a worthwhile therapeutic approach. With TNFalpha and Il-1, two key cytokines in rheumatoid arthritis have been identified. Their inhibition leads to a convincing clinical benefit. In the near future, inhibition of additional cytokines, such as Il-6 or Il-15, will likely open new beneficial strategies.

Cells of the synovium in rheumatoid arthritis. Macrophages

The multitude and abundance of macrophage-derived mediators in rheumatoid arthritis and their paracrine/autocrine effects identify macrophages as local and systemic amplifiers of disease. Although uncovering the etiology of rheumatoid arthritis remains the ultimate means to silence the pathogenetic process, efforts in understanding how activated macrophages influence disease have led to optimization strategies to selectively target macrophages by agents tailored to specific features of macrophage activation. This approach has two advantages: (a) striking the cell population that mediates/amplifies most of the irreversible tissue destruction and (b) sparing other cells that have no (or only marginal) effects on joint damage.

Regulation of pre-B cell colony-enhancing factor by STAT-3-dependent interleukin-6 trans-signaling: implications in the pathogenesis of rheumatoid arthritis

OBJECTIVE

To determine whether interleukin-6 (IL-6) trans-signaling directs the expression of pre-B cell colony-enhancing factor (PBEF) in vitro and in vivo.

METHODS

Complementary DNA from rheumatoid arthritis (RA) synovial fibroblasts treated with IL-6 and soluble IL-6 receptor (sIL-6R) was used to probe a cytokine microarray. PBEF regulation by the IL-6-related cytokines, IL-6, sIL-6R, oncostatin M (OSM), IL-11, and leukemia inhibitory factor (LIF) was determined by reverse transcription-polymerase chain reaction analysis. IL-6-mediated STAT-3 regulation of PBEF was determined using a cell-permeable STAT-3 inhibitor peptide. Antigen-induced arthritis (AIA) was induced in wild-type (IL-6(+/+)) and IL-6-deficient (IL-6(-/-)) mice. PBEF and STAT were detected by immunohistochemistry, immunoblotting, and electrophoretic mobility shift assay. Synovial levels of PBEF were quantified by enzyme immunoassay.

RESULTS

IL-6 trans-signaling regulated PBEF in a STAT-3-dependent manner. In addition, PBEF was regulated by the IL-6-related cytokine OSM, but not IL-11 or LIF. Flow cytometric analysis of the IL-6-related cognate receptors suggested that OSM regulates PBEF via its OSM receptor beta and not its LIF receptor. The involvement of PBEF in arthritis progression was confirmed in vivo, where induction of AIA resulted in a 4-fold increase in the synovial expression of PBEF. In contrast, little or no change was observed in IL-6(-/-) mice, in which the inflammatory infiltrate was markedly reduced and synovial STAT-1/3 activity was also impaired. Analysis of human RA synovial tissue confirmed that PBEF immunolocalized in apical synovial membrane cells, endothelial cells, adipocytes, and lymphoid aggregates. Synovial fluid levels of PBEF were significantly higher in RA patients than in osteoarthritis patients.

CONCLUSION

Experiments presented herein demonstrate that PBEF is regulated via IL-6 trans-signaling and the IL-6-related cytokine OSM. PBEF is also actively expressed during arthritis. Although these data confirm an involvement of PBEF in disease progression, the consequence of its action remains to be determined.

The role of megakaryocytes in skeletal homeostasis and rheumatoid arthritis

PURPOSE OF REVIEW

This review provides an update on the role of megakaryocytes in skeletal homeostasis, and discusses these findings in the context of rheumatoid arthritis.

RECENT FINDINGS

Thrombocytosis is a common complication of rheumatoid arthritis, and is presumably caused by an up-regulation in megakaryocytopoiesis. In general, patients with rheumatoid arthritis exhibit localized joint bone erosion with systemic bone loss, and rheumatoid arthritis patients with thrombocytosis tend to have more severe disease. Interestingly, in addition to their role in rheumatoid arthritis with thrombocytosis, it has been demonstrated recently that megakaryocytes play a dual role in regulating skeletal mass by inhibiting bone resorption while simultaneously stimulating bone formation. This seeming contradiction in the putative role of megakaryocytes in skeletal regulation and rheumatoid arthritis is the focus of this review.

SUMMARY

In rheumatoid arthritis there are substantial increases in the levels of several pro-inflammatory pleiotropic cytokines. As would be expected, in addition to their role in inflammation, these cytokines play a critical role in the megakaryocytopoiesis seen in patients who develop reactive thrombocytosis, and these cytokines also are known to regulate osteoclastogenesis. Thus, it appears that in rheumatoid arthritis with reactive thrombocytosis, the ability of the cytokines to enhance osteoclastogenesis outweighs the ability of megakaryocytes to inhibit osteoclastogenesis.

STAT3: a potential therapeutic target in dendritic cells for the induction of transplant tolerance

Dendritic cells (DCs) control the segue from innate to adaptive immunity. Moreover, depending upon their milieu, DCs can either induce or inhibit immune responses. Whether DCs are immune stimulatory or tolerogenic apparently rests with whether or not the DCs express activated signal transducer and activator of transcription-3 (STAT3), the transcription factor induced by IL-6-like cytokines and IL-10. DCs expressing activated STAT3 produce less IL-12, which results in less effector T cell development. Moreover, DCs expressing activated STAT3 also express the tryptophan-catabolising enzyme indoleamine 2,3-dioxygenase. The kynurenine products of tryptophan catabolism induce T cell apoptosis; this area is of major interest to researchers working on tolerogenic DCs. In various disease models ranging from tumours to autoimmune diseases, administration of STAT3-activating cytokines resulted in attenuation of immune responses. Other corroborating evidence was obtained using conditional STAT3-deficient mice, or mice defective in cytokine signalling. Thus, persistently activating STAT3 in DCs may be a feasible strategy for controlling allograft rejection.

Is there a role for TNF-alpha in anti-neutrophil cytoplasmic antibody-associated vasculitis? Lessons from other chronic inflammatory diseases

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is the most common cause of rapidly progressive glomerulonephritis and immune-mediated pulmonary renal syndrome. Now that the acute manifestations of the disease generally can be controlled with immunosuppressive drugs, ANCA-associated vasculitis has become a chronic and relapsing inflammatory disorder. The need to develop safer and more effective treatment has led to great interest in the mediators of chronic inflammation. There are many lessons to be learned from studies of other chronic inflammatory diseases, particularly rheumatoid arthritis (RA). The identification of a TNF-alpha-dependent cytokine cascade in the in vitro cultures of synovium in joints of patients with RA led to studies of TNF blockade in experimental models of arthritis and subsequently to clinical trials. These have culminated in the widespread introduction of anti-TNF therapy not only in RA but also in Crohn disease, ankylosing spondylitis, and several other chronic inflammatory disorders. Following a similar investigative pathway, studies that show the importance of TNF production by leukocytes and intrinsic renal cells in glomerulonephritis have been followed by the demonstration of the effectiveness of TNF blockade in several experimental models of glomerulonephritis and vasculitis. In experimental autoimmune vasculitis, improvement in disease was paralleled by a reduction in leukocyte transmigration, as demonstrated by intravital microscopy. The benefit of infliximab (a mAb to TNF) in ANCA-associated vasculitis was recently reported in a prospective open-label study. However, the use of etanercept (a soluble TNF receptor fusion protein) was not found to be of significant benefit in a randomized, controlled trial in patients with Wegener granulomatosis. Therefore, there is a need for further evaluation of the use of anti-TNF antibodies in patients with ANCA-associated glomerulonephritis.

The importance of T cell interactions with macrophages in rheumatoid cytokine production

The analysis of suppression of cytokines in rheumatoid synovial tissue and fluid pioneered the studies of human cytokines in diseased tissue due to the relative ease of staining samples, even at the height of the inflammatory process. These studies led to the study of synovial cytokine regulation, and the identification of TNF as a therapeutic target, which has been amply validated in clinical trials and now routine therapy. The next key question was how is TNF disregulated in synovium. Are there differences between the mechanisms of synovial TNF production compared to the production of protective TNF during an immune response? Are there differences between the induction of the pro-inflammatory TNF and the anti inflammatory IL-10? The analysis of the interaction of the two most abundant synovial cells, T lymphocytes and macrophages has provided interesting clues to new therapeutic approaches based on disrupting T-macrophage interaction.

Host response modulation in the management of periodontal diseases

OBJECTIVE

To review the biological mechanisms and clinical utility of therapeutic modulation of the host response in the management of periodontal diseases.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed up to and including December 2004. The search was limited to in vitro, experimental animal and clinical studies published in English. The selection criteria included all levels of available evidence: systematic reviews, randomised-controlled clinical trials, controlled clinical trials, prospective and retrospective cohort studies and case reports of human and experimental animal studies.

RESULTS

Six targets for non-microbial chemotherapeutic intervention were identified. Clinical trials have demonstrated the ability of non-steroidal anti-inflammatory drugs to slow periodontal disease progression. However, recently reported serious adverse effects preclude the use of cyclooxygenase-2 inhibitors as an adjunct to periodontal therapy. Adjunctive use of subantimicrobial dose doxycycline to non-surgical periodontal therapy is beneficial in the management of chronic periodontitis over 12 months. Controversial data exist on the effects of bisphosphonate administration as an adjunct to periodontal therapy. Evidence on modulation of other host mediators including lipoxins, cytokines and nitric oxide synthase is limited to animal research.

CONCLUSION

After validation in long-term clinical trials, adjunctive host modulation therapy may prove advantageous in the management of periodontal diseases.

Differential regulation of gastric tumor growth by cytokines that signal exclusively through the coreceptor gp130

BACKGROUND & AIMS

We have shown that mice with a mutation in gp130 (gp130(757F/F)), the signal transducing receptor for interleukin (IL)-6 family cytokines, have chronic gastric inflammation and develop distal stomach tumors associated with deregulated phosphorylated STAT3 expression. This model recapitulates many characteristics of intestinal-type gastric cancer in humans.

METHODS

To evaluate the role of IL-6 and IL-11 as ligands regulating tumor growth and submucosal invasion, we compared tumor characteristics of gp130(757F/F) mice with gp130(757F/F) mice lacking IL-6 or mature T and B cells.

RESULTS

As a result of the gp130(757F/F) mutation, expression of IL-6 and IL-11 was greatly up-regulated concomitant with activation of STAT3 and development of tumors. However, the lack of IL-6 or T and B cells did not impact on tumor growth. While IL-6 did not regulate tumor growth or tumor vascularization, gp130(757F/F)/IL-6(-/-) mice showed approximately 10-20-fold more submucosal tumor invasion, reduced mononuclear inflammatory cell infiltrate, and greater IL-11 and matrix metalloproteinase (MMP)-13 and MMP-9 synthesis than gp130(757F/F) mice. Expression of MMP-13 was largely restricted to tumor-associated stroma, but MMP-9 was also expressed in polymorphonuclear cells and a subset of epithelial cells. In addition, treatment with recombinant IL-11 stimulated expression of MMP-13 and MMP-9 in stomachs of wild-type mice.

CONCLUSIONS

Increased submucosal invasion in gp130(757F/F)/IL-6(-/-) mice could not be explained by increased vascularization or reduced immunosurveillance but was most likely facilitated by augmented metalloproteinase activity driven by elevated IL-11 levels.

Purification and Characterization of Recombinant Truncated Human Interleukin-11 Expressed as Fusion Protein in Escherichia coli

Mature human interleukin-11 (HuIL-11) is a cytokine consisting of 178 amino acid residues that results from scission of the N-terminal signal peptide, consisting of 21 amino acid residaues, from the corresponding nascent polypeptide. A DNA fragment encoding a truncated HuIL-11 (trHuIL-11), with an additional 5 amino acid residues removed from the N-terminus, was cloned into vector pGEX-2T between the BamHI site and the EcoRI site. Upon transformation with Escherichia coli BL21, the construct over-produced a glutathione S-transferase (GST)-fused protein in a soluble form after IPTG induction. The fusion protein was initially fractionated with butyl-Sepharose 4 fast flow column and by affinity chromatography using a GSH-Sepharose 4B column. On-site enzymatic release with thrombin gave the target protein at 96% purity as judged by SDS-PAGE and HPLC. Expression of the interleukin as a GST-fused protein thus greatly improved downstream processing. Subsequent biological activity assay suggested that trHuIL-11 had similar activity profile to the naturally produced sample and may be a promising candidate for further development as biopharmaceutical.

Endogenous IL-11 is pro-inflammatory in acute methylated bovine serum albumin/interleukin-1-induced (mBSA/IL-1)arthritis

OBJECTIVE

To evaluate the role of interleukin-11 (IL-11) in acute mBSA/IL-1-induced inflammatory arthritis.

METHODS

IL-11 was administered via intra-articular (IA) injection into knee joints of C57BL/6 mice and joint histology was assessed. The mitogenic response to IL-11 was measured in wild-type (WT) synovial fibroblasts. IL-1 was used as a comparator in both the studies. The severity of acute methylated bovine serum albumin (mBSA)/IL-1 arthritis was determined in WT and IL-11 receptor null (IL-11Ra1-/-) mice. In parallel experiments, a neutralising antibody to IL-11 was administered to WT mice throughout this model.

RESULTS

IA injections of IL-11 resulted in mild-to-moderate joint inflammation which was less than that due to IA IL-1. IL-11 had a dose-dependent mitogenic effect on WT synovial fibroblasts (P<0.01). mBSA/IL-1 acute arthritis was reduced in IL-11Ra1-/- versus WT mice (histological arthritis score: 10.1+/-0.5 versus 12.8+/-0.7, respectively; P=0.01). Administration of an IL-11 neutralising antibody to WT mice reduced mBSA/IL-1 acute arthritis scores compared to control antibody (10.6+/-0.7 versus 13.3+/-0.6, respectively; P=0.02).

CONCLUSIONS

These data demonstrate that endogenous IL-11 exerts relatively mild but consistent pro-inflammatory effects in acute inflammatory arthritis.

Is targeting Toll-like receptors and their signaling pathway a useful therapeutic approach to modulating cytokine-driven inflammation?

Cytokine-driven inflammation and tissue destruction is a common theme of chronic inflammatory diseases such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, psoriasis, chronic obstructive pulmonary disease, and atherosclerosis. Research over the last two decades demonstrated the importance of cytokines that are not only expressed chronically but also are capable of signaling at sites of chronic inflammation. Cytokines thus regulate major pathological processes that include inflammation, angiogenesis, tissue remodeling, and fibrosis. This research led to the identification of key cytokines involved in these processes, two of which, tumor necrosis factor-alpha and interleukin-1, have also been successfully targeted in the clinic. However, what triggers and maintains cytokine gene expression in chronic inflammation remains a mystery. In this article, we review current progress in the understanding of cytokine-driven inflammation and discuss current evidence implicating Toll-like receptors (TLRs), recently identified as the receptors recognizing self versus non-self molecular patterns, in the regulation of cytokine-driven inflammation. Whether targeting TLRs and their downstream signaling pathway will prove to be a successful approach for the treatment of these devastating diseases remains to be determined.

Uterine extracellular matrix components are altered during defective decidualization in interleukin-11 receptor alpha deficient mice

BACKGROUND

Implantation of the embryo and successful pregnancy are dependent on the differentiation of endometrial stromal cells into decidual cells. Female interleukin-11 receptor alpha (IL-11Ralpha) deficient mice are infertile due to disrupted decidualization, suggesting a critical role for IL-11 and its target genes in implantation. The molecular targets of IL-11 in the uterus are unknown, but it is likely that IL-11 signaling modifies the expression of other genes important in decidualization. This study aimed to identify genes regulated by IL-11 during decidualization in mouse uterus, and to examine their expression and localization as an indication of functional significance during early pregnancy.

METHODS

Decidualization was artificially induced in pseudopregnant wild type (IL11Ra+/+) and IL-11Ralpha deficient (IL11Ra-/-) littermates by oil injection into the uterine lumen, and gene expression analyzed by NIA 15K cDNA microarray analysis at subsequent time points. Quantitative real-time RT-PCR was used as an alternative mRNA quantitation method and the expression and cellular localization of the protein products was examined by immunohistochemistry.

RESULTS

Among 15,247 DNA probes, 13 showed increased and 4 decreased expression in IL11Ra-/- uterus at 48 h of decidualization. These included 4 genes encoding extracellular matrix proteins; collagen III alpha1, secreted acidic cysteine-rich glycoprotein (SPARC), biglycan and nidogen-1 (entactin). Immunohistochemistry confirmed increased collagen III and biglycan protein expression in IL11Ra-/- uterus at this time. In both IL11Ra-/- and wild type uterus, collagen III and biglycan were primarily localized to the outer connective tissue and smooth muscle cells of the myometrium, with diffuse staining in the cytoplasm of decidualized stromal cells.

CONCLUSION

These data suggest that IL-11 regulates changes in the uterine extracellular matrix that are necessary for decidualization.

Endogenous interleukin-11 (IL-11) levels in newly diagnosed children with acquired severe aplastic anemia (SAA)

BACKGROUND

Impaired hematopoietic growth factor production is a hypothetical contributing factor to the development of acquired severe aplastic anemia (SAA). The serum levels of most hematopoietic cytokines in SAA patients are elevated.

OBJECTIVE

To measure interleukin-11 levels in newly diagnosed SAA children and attempt to correlate levels with disease severity and response to therapy.

DESIGN/METHODS

Following enrollment into a clinical study but prior to treatment, serum samples were obtained from 11 newly diagnosed children with acquired SAA. These samples were collected between May 2000 and September 2002. IL-11 levels were quantified utilizing an ELISA technique.

RESULTS

Ten of the 11 patients had low or normal levels of IL-11 (<85 pg/mL) and one had an elevated level of 409 pg/mL (normal range 15-200 pg/mL).

CONCLUSIONS

The production of IL-11 does not increase in response to thrombocytopenia in most children with SAA. The significance of this laboratory observation is not clear at this time. Further studies are warranted to determine what, if any, role this plays in the development of this disorder and if the administration of recombinant human IL-11 might be beneficial in the treatment of acquired SAA.

Interleukin-11 and IL-17 and the Pathogenesis of Periodontal Disease

BACKGROUND

Interleukin (IL)-11 and IL-17 are cytokines that modulate the inflammatory process and have not been assessed within normal or inflamed gingival tissues. Our purpose was to compare concentrations of human IL-11 and IL-17 within healthy and diseased human gingiva to determine their possible role in the initiation or progression of periodontal diseases.

METHODS

Biopsies from healthy (non-hemorrhagic gingiva adjacent to a < or = 3 mm gingival sulcus) and diseased gingiva (hemorrhagic gingiva adjacent to a > or = 3 mm periodontal pocket) were studied. IL-11, IL-17, RANTES, and IL-6 concentrations were assessed within solubilized gingival biopsies by enzyme-linked immunosorbent assay. Data were compared by factorial analysis of variance and a post-hoc Tukey honestly significant difference (HSD) test. Regression analysis and partial correlation analysis (adjusted for sample weight) were also used to determine correlations between the variables.

RESULTS

Interleukin-11 concentrations were highest within gingiva adjacent to 3 mm diseased pockets (P < 0.001), and IL-17 concentrations were highest at 4 to 5 mm sites compared to other sites (P < 0.001). Gingival concentrations of both cytokines were significantly lower in gingiva adjacent to a > or = 6 mm pocket. RANTES concentrations were significantly greater in gingiva adjacent to > or = 6 mm pockets than in tissues derived from other sites (P < 0.001). IL-11, IL-6, and RANTES concentrations were significantly correlated with sulcular depth.

CONCLUSIONS

Gingival concentrations of IL-11 and IL-17 are different in diseased gingiva adjacent to 3, 4 to 5, and > or = 6 mm pockets, suggesting that their concentrations change as a consequence of the progression of gingivitis to periodontitis and that both cytokines could have a significant role in this progression. These data may be useful for the design of procedures for prevention of periodontal disease.

Functional characterization of W147A: a high-affinity interleukin-11 antagonist

IL-11 is a member of the gp130 family of cytokines, which signal via assembly of multisubunit receptor complexes containing at least one molecule of the transmembrane signaling receptor gp130. IL-11 forms a high-affinity complex, thereby inducing gp130-dependent signaling. Previous studies have identified three distinct receptor binding sites, I, II, and III, crucial for the binding of murine IL-11 (mIL-11) to both the IL-11R and gp130. In this study, we have further characterized the role of the mIL-11 site III mutant W147A. We show that W147A is a high-affinity specific antagonist of mIL-11-mediated signaling in gp130/IL-11R-transfected Ba/F3 cells. The antagonistic action of W147A is due to its ability to competitively disrupt multimeric gp130/IL-11R signaling complex formation. We also show that W147A inhibits IL-11-mediated signaling in primary human endometrial cells, thus demonstrating the potential utility of W147A in suppressing IL-11 responses in vivo.