Evidence that cytokines play a role in rheumatoid arthritis

Cholecystokinin octapeptide exerts its therapeutic effects on collagen-induced arthritis by suppressing both inflammatory and Th17 responses

The purpose of this study was to evaluate the potential therapeutic effect of cholecystokinin octapeptide (CCK-8) on collagen-induced arthritis (CIA), an accepted murine experimental disease model with diverse histopathological features similar to human rheumatoid arthritis (RA). CIA was induced in DBA/1J mice by immunization with chicken collagen type II (CII). CCK-8 at different doses was intraperitoneally administered daily for 1 week. Mice treated with CCK-8 at doses of 5 and 10 nmol but not 1 nmol displayed much delayed onset of CIA and significantly lower incidence and decreased severity of arthritis. CCK-8 treatment significantly reduced the production of cytokines (IL-17, IL-23, IL-6 and TNF-α) and chemokines monocyte chemoattractant protein 1 in the joints of arthritic mice or in synovial cell culture supernatant, and increased the levels of IFN-γ and TGF-β. T cells from CCK-8 treated mice proliferated much less, produced low level of IL-17 and high levels of IFN-γ and TGF-β. Moreover, CCK-8 treated mice showed lower levels of CII-specific IgG, particularly that of IgG2a, in sera than those from control mice. These results indicate that CCK-8 is effective in suppressing both inflammatory and Th17 responses in CIA. CCK-8 may represent a new therapeutic modality for rheumatoid arthritis.

Anti-inflammatory evaluation of Coronopus didymus in the pleurisy and paw oedema models in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Mastrunço (Coronopus didymus--CD) is currently considered as a medicinal specie often used in Brazil, especially in southeast region, for the treatment of several diseases in which pain and inflammation are common. Treatment with the plant can be done by infusion, decoction, or through food. The aim of this study was: to investigate the anti-inflammatory effect of hydroalcoholic extract obtained from the leaves of CD following the traditional procedure.

MATERIALS AND METHODS

The anti-inflammatory activity was determined using mouse of pleurisy and paw oedema models, both process being induced by different flogistic agents such as: carrageenan (Cg), bradykinin (BK), histamine (HIS), substance P (SP), dextran (DEX) or prostaglandin E(2) (PGE(2)). We evaluated the effect of CD (200-600 mg/kg) administered by oral route (p.o.) upon leukocytes migration, myeloperoxidase (MPO), and adenosine-deaminase (ADA) activities and nitric oxide (NO) levels.

RESULTS

CD (200-600 mg/kg) inhibited the leukocytes by 60.0+/-1.42%, neutrophils by 82.75+/-1.29%, MPO by 42.30+/-4.23%, and ADA activities by 57.89+/-1.94%, as well as NO levels by 64.28+/-2.15% in Cg induced pleurisy. CD also inhibited total and differential leukocytes in the pleurisy induced by BK (1.30+/-0.11/0.29+/-0.02), HIS (1.20+/-0.09/0.42+/-0.05) and SP (0.74+/-0.06/0.14+/-0.01). In addition, CD was effective in reducing paw oedema induced by Cg by 72.79+/-1.13%, SP by 68.26.+/-0.78%, BK by 66.66.+/-0.77%, PGE(2) by 53.346.+/-1.18 and DEX by 65.14+/-2.35%.

CONCLUSION

Several mechanisms, including the inhibition of enzymes (MPO and ADA) and mediators (BK, HIS, SP, NO and PGE(2)) release and/or action, appear to account for the anti-inflammatory effect of Coronopus didymus.

Synoviocyte-derived angiopoietin-like protein 2 contributes to synovial chronic inflammation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by symmetrical polyarticular synovitis of the diarthrodial joints. Several proinflammatory cytokines derived from both infiltrating inflammatory cells and activated resident cells within the RA joint play a fundamental role in the processes that cause inflammation. However, anticytokine treatment is beneficial but not curative, the effects are only partial, and nonresponses are common. Therefore, an effort has been made to identify other key regulators of inflammation in articular structures to develop new therapies to suppress synovial inflammation and joint destruction in RA. Adipose tissue-derived angiopoietin-like protein 2 (Angptl2) activates an inflammatory cascade in endothelial cells and induces chemotaxis of monocytes/macrophages in obesity, resulting in initiation and propagation of inflammation within adipose tissues and obesity-related metabolic diseases. Angptl2 mRNA and protein are abundantly expressed in hyperplastic rheumatoid synovium of RA patients, especially in fibroblast-like and macrophage-like synoviocytes, but not in B and T lymphocytes. Angptl2 concentration in joints of RA patients was also significantly increased in comparison with patients with osteoarthritis, which in comparison with RA represents a significantly lower inflammatory grade form of arthritis. Notably, Angptl2 promoted increased chemotactic activities of CD14+CD16- monocytes from synovial fluid of RA patients. Therefore, Angptl2 acts as an important rheumatoid synovium-derived inflammatory mediator in RA pathogenesis.

Finemapping of the arthritis QTL Pia7 reveals co-localization with Oia2 and the APLEC locus

In this study, we sought to determine the effect of the quantitative trait locus Pia7 on arthritis severity. The regulatory locus derived from the arthritis-resistant E3 rat strain was introgressed into the arthritis-susceptibility DA strain through continuous backcrossing. Congenic rats were studied for their susceptibility to experimental arthritis using pristane and adjuvant oil. In addition, cell number and function of various leukocyte populations were analyzed either under naive or stimulated conditions. We found that the minimal congenic fragment of DA.E3-Pia7 rats overlapped with the minimal fragment in DA.PVG-Oia2 congenic rats, which has been positionally cloned to the antigen-presenting lectin-like receptor complex (APLEC) genes. DA.E3-Pia7 congenic rats were protected from both PIA and OIA, but the protection was more pronounced in OIA. In adoptive transfer experiments we observed that the Pia7 locus controlled the priming of arthritogenic T cells and not the effector phase. In addition, Pia7 congenic rats had a significant higher frequency of B cells and granulocytes as well as TNFalpha production after stimulation, indicating a higher activation state of cells of the innate immune system. In conclusion, this study shows that the APLEC locus is a major locus regulating the severity of experimentally induced arthritis in rats.

Th17 cytokines and arthritis

Th17 cells are implicated in human autoimmune diseases, such as rheumatoid arthritis (RA), although it has not been established whether this persistent destructive arthritis is driven by Th1 and/or Th17 cells. Interleukin-17A (IL-17A) contributes to the pathogenesis of arthritis as has been shown in several experimental arthritis models. Importantly, recent data from first clinical trials with anti-IL-17A antibody treatment in psoriatic arthritis patients and RA patients looks promising. This review summarizes the findings about the role of Th17 cells in arthritis and discusses the impact of the different Th17 cytokines in the pathogenesis of this disease. However, further studies are needed to unravel the interplay between IL-17A and other Th17 cytokines such as IL-17F, IL-22, and IL-21 in the pathoimmunological process of this crippling disease, in particular, whether regulating Th17 cell activity or specific combinations of Th17 cytokines will have additional value compared to neutralizing IL-17A activity alone. Moreover, tumor necrosis factor-positive Th17 cells are discussed as potential dangerous cells in driving persistent arthritis in human early RA.

Simvastatin inhibits cytokine-stimulated Cyr61 expression in osteoblastic cells: a therapeutic benefit for arthritis

OBJECTIVE

To examine the effects of proinflammatory cytokines on Cyr61 expression in osteoblastic cells and the modulatory action of simvastatin, to assess the role of CREB in Cyr61 induction, and to investigate the relationship of osteoblastic expression of Cyr61 to disease progression in experimental arthritis.

METHODS

Cyr61 expression and CREB phosphorylation at serine 133 were examined by Western blotting. Promoter activity of Cyr61 was assessed by luciferase assay with promoter deletion/mutagenesis and forced expression/gene silencing of CREB. Interaction between CREB and the Cyr61 promoter was evaluated by electrophoretic mobility shift assay and chromatin immunoprecipitation. CCL2 expression was examined by Northern blotting and enzyme-linked immunosorbent assay. In rats with collagen-induced arthritis (CIA), osteoblastic expression of Cyr61 was examined by immunohistochemistry, and disease progression was assessed by clinical, radiographic, and histologic examination.

RESULTS

In primary human osteoblasts and U2OS cells, Cyr61 expression stimulated by tumor necrosis factor α, interleukin-1β (IL-1β), oncostatin M (OSM), and other IL-6-family cytokines was suppressed by simvastatin. In U2OS cells, simvastatin inhibited OSM-induced CREB phosphorylation and CREB-DNA binding. Knockdown of CREB by short hairpin RNA reduced Cyr61 synthesis. OSM-induced Cyr61 promoter activation was dependent on CRE-CREB interaction and inhibited by simvastatin. Cyr61 enhanced CCL2 expression by U2OS cells. Intraarticular injection of simvastatin inhibited CIA progression and diminished the number of Cyr61+ osteoblasts and infiltrating macrophages.

CONCLUSION

Simvastatin inhibited cytokine-stimulated Cyr61 expression in osteoblastic cells and suppressed disease progression and osteoblastic expression of Cyr61 in inflammatory arthritis. This finding indicates that simvastatin may have potential as a therapeutic agent for inflammatory arthritis.

Vascular Function and Inflammation in Rheumatoid Arthritis: the Role of Physical Activity

Inflammation disturbs biochemical pathways involved in homeostasis of the endothelium. Research has established clear links between inflammatory mediators, particularly C-reactive protein and tumour necrosis factor alpha, endothelial dysfunction, and atherosclerosis. Endothelial dysfunction and atherosclerosis may be subclinical at early stages, and thus the ability to detect them with non-invasive techniques is crucially important, particularly in populations at increased risk for cardiovascular disease, such as those with rheumatoid arthritis. This may allow the identification of interventions that may reverse these processes early on. One of the best non-pharmacological interventions that may achieve this is physical activity. This review explores the associations between inflammation, endothelial dysfunction, and atherosclerosis and discusses the role of exercise in blocking specific pathways in the inflammation, endothelial dysfunction - atherosclerosis network.

Vascular function and inflammation in rheumatoid arthritis: the role of physical activity

Inflammation disturbs biochemical pathways involved in homeostasis of the endothelium. Research has established clear links between inflammatory mediators, particularly C-reactive protein and tumour necrosis factor alpha, endothelial dysfunction, and atherosclerosis. Endothelial dysfunction and atherosclerosis may be subclinical at early stages, and thus the ability to detect them with non-invasive techniques is crucially important, particularly in populations at increased risk for cardiovascular disease, such as those with rheumatoid arthritis. This may allow the identification of interventions that may reverse these processes early on. One of the best non-pharmacological interventions that may achieve this is physical activity. This review explores the associations between inflammation, endothelial dysfunction, and atherosclerosis and discusses the role of exercise in blocking specific pathways in the inflammation, endothelial dysfunction - atherosclerosis network.

Promotion of arthritis and allergy in mice by aminoglycoglycerophospholipid, a membrane antigen specific to Mycoplasma fermentans

Mycoplasmas, which lack a cell wall and are the smallest self-replicating bacteria, have been linked to some chronic diseases, such as AIDS, rheumatoid arthritis (RA), and oncogenic transformation of cells. Their membrane components (lipoproteins and glycolipids) have been identified as possible causative factors in such diseases. Glycoglycerophospholipid (GGPL)-III, a unique phosphocholine-containing aminoglycoglycerophospholipid, is a major specific antigen of Mycoplasma fermentans, and has been detected in 38% of RA patients. Unlike those of lipoproteins, which induce inflammation via Toll-like receptor 2 (TLR2), the pathologic effects of GGPL-III are poorly understood. RA and metal allergies are chronic inflammatory diseases in which autoantigens have been implicated. Here, we examined the effects of chemically synthesized GGPL-III in murine arthritis and allergy models. GGPL-III alone exhibited little inflammatory effect, but promoted both collagen-induced arthritis and nickel (Ni) allergy, although less powerfully than Escherichia coli lipopolysaccharide. The augmenting effect of GGPL-III on Ni allergy was present in mice deficient in either T cells or active TLR4, but it was markedly weaker in mice deficient in macrophages, interleukin-1, or the histamine-forming enzyme histidine decarboxylase than in their control strains. These results suggest that GGPL-III may play roles in some types of chronic diseases via the innate immune system.

Th17 cytokines and arthritis

Th17 cells are implicated in human autoimmune diseases, such as rheumatoid arthritis (RA), although it has not been established whether this persistent destructive arthritis is driven by Th1 and/or Th17 cells. Interleukin-17A (IL-17A) contributes to the pathogenesis of arthritis as has been shown in several experimental arthritis models. Importantly, recent data from first clinical trials with anti-IL-17A antibody treatment in psoriatic arthritis patients and RA patients looks promising. This review summarizes the findings about the role of Th17 cells in arthritis and discusses the impact of the different Th17 cytokines in the pathogenesis of this disease. However, further studies are needed to unravel the interplay between IL-17A and other Th17 cytokines such as IL-17F, IL-22, and IL-21 in the pathoimmunological process of this crippling disease, in particular, whether regulating Th17 cell activity or specific combinations of Th17 cytokines will have additional value compared to neutralizing IL-17A activity alone. Moreover, tumor necrosis factor-positive Th17 cells are discussed as potential dangerous cells in driving persistent arthritis in human early RA.

RNA interference-based gene therapy for successful treatment of rheumatoid arthritis

BACKGROUND

RNA interference (RNAi) is a powerful endogenous process initiated by short double-stranded RNAs, which results in sequence-specific posttranscriptional gene silencing. The possibility of blocking the expression of any protein carries huge expectations for potential therapeutic applications in a wide range of diseases. For clinical development, however, the use of RNAi-based therapeutics has to overcome major obstacles, mainly targeted delivery and safety issues.

OBJECTIVE/METHODS

In this short review, we provide an overview of specifications for RNAi-based gene therapy in rheumatoid arthritis (RA) and discuss recent progresses in the development of efficient silencing, focusing on expression of short hairpin RNAs.

RESULTS/CONCLUSIONS

Combining advances in RNAi methodology with gene therapy technology opens avenues for rapid applications to RA.

Golimumab for rheumatoid arthritis

BACKGROUND

Golimumab is a humanized inhibitor of Tumor necrosis factor-alpha, recently approved by the Food and Drug Administration (FDA) for the treatment of Rheumatoid arthritis (RA).

OBJECTIVES

The objective of this systematic review was to compare the efficacy and safety of golimumab (alone or in combination with DMARDs or biologics) to placebo (alone or in combination with DMARDs or biologics) in randomized or quasi-randomized clinical trials in adults with RA.

SEARCH STRATEGY

An expert librarian searched six databases for any clinical trials of golimumab in RA, including the Cochrane Central Register of Controlled Trials (CENTRAL), OVID MEDLINE, CINAHL, EMBASE, Science Citation Index (Web of Science) and Current Controlled Trials databases.

SELECTION CRITERIA

Studies were included if they used golimumab in adults with RA, were randomized or quasi-randomized and provided clinical outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors (JS, SN) independently reviewed all titles and abstracts, selected appropriate studies for full review and reviewed the full-text articles for the final selection of included studies. For each study, they independently abstracted study characteristics, safety and efficacy data and performed risk of bias assessment. Disagreements were resolved by consensus. For continuous measures, we calculated mean differences or standardized mean differences and for categorical measures, relative risks. 95% confidence intervals were calculated.

MAIN RESULTS

Four RCTs with 1,231 patients treated with golimumab and 483 patients treated with placebo were included. Of these, 436 were treated with the FDA-approved dose of golimumab 50 mg every four weeks. Compared to patients treated with placebo+methotrexate, patients treated with the FDA-approved dose of golimumab+methotrexate were 2.6 times more likely to reach ACR50 (95% confidence interval (CI) 1.3 to 4.9; P=0.005 and NNT= 5, 95% confidence interval 2 to 20), no more likely to have any adverse event (relative risk 1.1, 95% Cl 0.9 to 1.2; P=0.44), and 0.5 times as likely to have overall withdrawals (95% Cl 0.3 to 0.8; P=0.005). Golimumab-treated patients were significantly more likely to achieve remission, low disease activity and improvement in functional ability compared to placebo (all statistically significant). No significant differences were noted between golimumab and placebo regarding serious adverse events, infections, serious infections, lung infections, tuberculosis, cancer, withdrawals due to adverse events and inefficacy and deaths. No radiographic data were reported.

AUTHORS' CONCLUSIONS

With an overall high grade of evidence, at the FDA-approved dose, golimumab is significantly more efficacious than placebo in treatment of patients with active RA , when used in combination with methotrexate. The short-term safety profile, based on short-term RCTs, is reasonable with no differences in total adverse events, serious infections, cancer, tuberculosis or deaths. Long-term surveillance studies are needed for safety assessment.

Mechanism by which HLA-DR4 regulates sex-bias of arthritis in humanized mice

HLA class II allele DRB1*0401 is associated with predisposition to Rheumatoid Arthritis in humans as well as collagen-induced arthritis in mice. Predominantly females develop arthritis in humans and DR4 transgenic mice; however the mechanism of sex-bias is still unknown. We have investigated the molecular basis by which DR4 is associated with sex-bias of arthritis. Here we show that differential antigen-specific immune mechanisms in DR4 male and female mice lead to increased susceptibility in female mice. B cells are hyperactive and present DR-restricted peptides robustly in females compared to males. Antigen-specific response showed that females produced B cell modulating cytokines like IL-13 while males produced IFNgamma. Male transgenic mice have higher number of T and B regulatory cells. An exogenous supply of 17beta estradiol in male mice led to enhanced expression of DR4 and antigen-specific response to DR4-restricted peptides. On the other hand, castration increased the incidence of arthritis. We propose that sex-bias in arthritis involves B cells and presentation of antigen by HLA-DR4 leading to activation of autoreactive cells and autoantibodies production in females, while regulatory B cells in males protect them from pathogenesis. The transgenic mice expressing RA susceptible haplotype simulate human RA and may be valuable to study gender differences observed in patients.

New understanding and approaches to treatment in rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common autoimmune inflammatory polyarthritis. Significant advances in the understanding of its pathogenesis have led in the past two decades to major advancement in its therapy. We used data from articles in Cochrane Database of Systematic Reviews on 'rheumatoid arthritis', meta-analyses and randomized controlled trials on adult RA (age >19 years) published in English within the past 5 years and identified in PubMed, and other key papers on management of RA. Appropriate, early and aggressive therapy is required for confirmed active cases of RA. The choice of disease-modifying drugs and different combinations, especially the newer biologic agents in regards of their early and long-term usage remains debated because of high costs and long-term safety concerns. Development of newer biologic agents working on different pathways of inflammation is underway in different stages. It remains to be determined how and when each of these agents will fit in the overall management of RA. Furthermore, post-marketing surveillance of the safety and response sustainability of these drugs is warranted.

Active immunization to tumor necrosis factor-alpha is effective in treating chronic established inflammatory disease: a long-term study in a transgenic model of arthritis

INTRODUCTION

Passive blockade of tumor necrosis factor-alpha (TNF-alpha) has demonstrated high therapeutic efficiency in chronic inflammatory diseases, such as rheumatoid arthritis, although some concerns remain such as occurrence of resistance and high cost. These limitations prompted investigations of an alternative strategy to target TNF-alpha. This study sought to demonstrate a long-lasting therapeutic effect on established arthritis of an active immunotherapy to human (h) TNF-alpha and to evaluate the long-term consequences of an endogenous anti-TNF-alpha response.

METHODS

hTNF-alpha transgenic mice, which spontaneously develop arthritides from 8 weeks of age, were immunized with a heterocomplex (TNF kinoid, or TNF-K) composed of hTNF-alpha and keyhole limpet hemocyanin after disease onset. We evaluated arthritides by clinical and histological assessment, and titers of neutralizing anti-hTNF-alpha antibody by enzyme-linked immunosorbent assay and L929 assay.

RESULTS

Arthritides were dramatically improved compared to control mice at week 27. TNF-K-treated mice exhibited high levels of neutralizing anti-hTNF-alpha antibodies. Between weeks 27 and 45, all immunized mice exhibited symptoms of clinical deterioration and a parallel decrease in anti-hTNF-alpha neutralizing antibodies. A maintenance dose of TNF-K reversed the clinical deterioration and increased the anti-hTNF-alpha antibody titer. At 45 weeks, TNF-K long-term efficacy was confirmed by low clinical and mild histological scores for the TNF-K-treated mice. Injections of unmodified hTNF-alpha did not induce a recall response to hTNF-alpha in TNF-K immunized mice.

CONCLUSIONS

Anti-TNF-alpha immunotherapy with TNF-K has a sustained but reversible therapeutic efficacy in an established disease model, supporting the potential suitability of this approach in treating human disease.

G-CSF and GM-CSF as therapeutic targets in rheumatoid arthritis

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are well-recognized regulators of hematopoiesis and have an established role as growth factors in clinical practice. G-CSF and GM-CSF regulate myeloid cell production, differentiation and activation, and might also be important for driving inflammatory responses. Inappropriate engagement of this pathway could be a critical amplification mechanism when maladaptive immune responses predispose to autoimmunity and sterile tissue inflammation. We postulate that antagonism of G-CSF or GM-CSF could represent a novel therapeutic approach for a variety of autoimmune-mediated inflammatory diseases, including rheumatoid arthritis.

Rejuvenating the immune system in rheumatoid arthritis

In rheumatoid arthritis (RA), the aging process of the immune system is accelerated. Formerly, this phenomenon was suspected to be a consequence of chronic inflammatory activity. However, newer data strongly suggest that deficiencies in maintaining telomeres and overall DNA stability cause excessive apoptosis of RA T cells, imposing proliferative pressure and premature aging on the system. Already during the early stages of their life cycle, and long before they participate in the inflammatory process, RA T cells are lost owing to increased apoptotic susceptibility. A search for underlying mechanisms has led to the discovery of defective pathways of repairing broken DNA and elongating and protecting telomeric sequences at the chromosomal ends. Two enzymatic machineries devoted to DNA repair and maintenance have been implicated. RA T cells fail to induce sufficient amounts of the telomeric repair enzyme telomerase, leaving telomeric ends uncapped and thus susceptible to damage. Of equal importance, RA T cells produce low levels of the DNA repair enzyme ataxia telangiectasia mutated and the complex of nucleoproteins that sense and fix DNA double-strand breaks. The inability to repair damaged DNA renders naive T cells vulnerable to apoptosis, exhausts T-cell regeneration and reshapes the T cell repertoire. Therapeutic attempts to reset the immune systems of patients with RA and prevent premature immunosenescence should include restoration of DNA repair capability.

CD40 and autoimmunity: the dark side of a great activator

CD40 is a tumor necrosis factor receptor superfamily member expressed by immune and non-immune cells. CD40:CD154 interactions mediate T-dependent B cell responses and efficient T cell priming. Thus, CD40 is a likely candidate to play roles in autoimmune diseases in which activated T and B cells cause pathology. Diseases in which CD40 plays a pathogenic role include autoimmune thyroiditis, type 1 diabetes, inflammatory bowel disease, psoriasis, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus. This review discusses the role of CD40:CD154 interaction in human and mouse autoimmunity, human polymorphisms associated with disease incidence, and disrupting CD40:CD154 interactions as an autoimmune therapy.

Peripheral blood expression profiles of bone morphogenetic proteins, tumor necrosis factor-superfamily molecules, and transcription factor Runx2 could be used as markers of the form of arthritis, disease activity, and therapeutic responsiveness

OBJECTIVE

To assess whether different forms of arthritis and disease activity could be distinguished by peripheral blood expression profiles of bone-regulatory factors including tumor necrosis factor (TNF)-superfamily [TNF-related apoptosis-inducing ligand (TRAIL), the Fas ligand (FasL), and the ligand for herpesvirus entry mediator (LIGHT)] and bone morphogenetic protein (BMP)-family members (BMP-2, BMP-4, BMP-6) as well as osteoblast differentiation gene Runx2.

METHODS

Blood cells from healthy controls (n = 25) and patients at different disease stages with rheumatoid arthritis (RA; n = 49), osteoarthritis (OA; n = 17), or spondyloarthritis, including ankylosing spondylitis (AS; n = 27) or psoriatic arthritis (PsA; n = 23), were processed for quantitative polymerase chain reaction. Gene expression was assessed in comparison with control samples, correlated with clinical data of different forms of arthritis, and analyzed for discriminative efficacy between groups by receiver-operation characteristic (ROC) curves. Results were confirmed on diagnostic RA (n = 5) and AS (n = 8) samples.

RESULTS

BMP-4, BMP-6, and Runx2 expressions were significantly decreased in patients with RA and OA versus controls. Patients with RA also had decreased FasL and LIGHT expression, while patients with AS had increased Runx2 expression. Negative correlation with disease activity was found for BMP-4, FasL, and Runx2 in RA and for Runx2 in PsA, while positive correlation was found for BMP-4 in PsA. Gene expression was higher in the therapy-resistant form of AS (for BMP-4, LIGHT, and Runx2) and in methotrexate-treated patients in RA (for BMP-2 and LIGHT). ROC curve analysis confirmed discrimination between groups, particularly decreased LIGHT and Runx2 for RA and increased Runx2 for AS.

CONCLUSION

Our study identified BMP and Runx2 as possible biomarkers of bone metabolism in several forms of arthritis, while lower FasL and LIGHT were associated with RA. Correlation between gene expression and disease activity may be clinically useful in assessing therapeutic effectiveness and disease monitoring.

IL-17 mediates articular hypernociception in antigen-induced arthritis in mice

IL-17 is an important cytokine in the physiopathology of rheumatoid arthritis (RA). However, its participation in the genesis of nociception during RA remains undetermined. In this study, we evaluated the role of IL-17 in the genesis of articular nociception in a model of antigen (mBSA)-induced arthritis. We found that mBSA challenge in the femur-tibial joint of immunized mice induced a dose- and time-dependent mechanical hypernociception. The local IL-17 concentration within the mBSA-injected joints increased significantly over time. Moreover, co-treatment of mBSA challenged mice with an antibody against IL-17 inhibited hypernociception and neutrophil recruitment. In agreement, intraarticular injection of IL-17 induced hypernociception and neutrophil migration, which were reduced by the pre-treatment with fucoidin, a leukocyte adhesion inhibitor. The hypernociceptive effect of IL-17 was also reduced in TNFR1(-/-) mice and by pre-treatment with infliximab (anti-TNF antibody), a CXCR1/2 antagonist or by an IL-1 receptor antagonist. Consistent with these findings, we found that IL-17 injection into joints increased the production of TNF-alpha, IL-1beta and CXCL1/KC. Treatment with doxycycline (non-specific MMPs inhibitor), bosentan (ET(A)/ET(B) antagonist), indomethacin (COX inhibitor) or guanethidine (sympathetic blocker) inhibited IL-17-induced hypernociception. IL-17 injection also increased PGE(2) production, MMP-9 activity and COX-2, MMP-9 and PPET-1 mRNA expression in synovial membrane. These results suggest that IL-17 is a novel pro-nociceptive cytokine in mBSA-induced arthritis, whose effect depends on both neutrophil migration and various pro-inflammatory mediators, as TNF-alpha, IL-1beta, CXCR1/2 chemokines ligands, MMPs, endothelins, prostaglandins and sympathetic amines. Therefore, it is reasonable to propose IL-17 targeting therapies to control this important RA symptom.

CTLA4-Ig interacts with cultured synovial macrophages from rheumatoid arthritis patients and downregulates cytokine production

Introduction

Co-stimulatory signal B7(CD80/CD86):CD28 is needed in order to activate T cells in immune response. Cytotoxic T lymphocyte-associated antigen-4-immunoglobulin (CTLA4-Ig) binding to the B7 molecules on antigen-presenting cells downregulates this activation and represents a recent biological treatment in rheumatoid arthritis (RA). Objectives of the study were to investigate the presence of the B7.2 (CD86) molecule and its masking by CTLA4-Ig on cultures of both RA synovial macrophages (RA SM), and of macrophages differentiated from THP-1 cells (M). In addition, the anti-inflammatory effects of CTLA4-Ig on co-cultures of RA SM and M with activated T cells were tested.

Methods

All macrophages were co-cultured for 24 hours with activated T cells, without or with CTLA4-Ig (10, 100, 500 μg/ml for 1 hour, 3 hours and overnight, respectively). Immunofluorescence (IF) staining for B7.2, and an analysis of inflammatory cytokine expression (interleukin (IL) -6, tumor necrosis factor (TNF) α, IL-1β, transforming growth factor (TGF) β) by immunocytochemistry (ICC), western blot (WB) and reverse transcriptase-polymerase chain reaction (RT-PCR) were performed.

Results

Macrophages showed intense B7.2 expression. CTLA4-Ig/B7.2 masking was evident for all macrophages, even after only 1 hour of cell culture (range from 10 to 100 μg/ml). ICC of co-cultures showed a dose-dependent decrease in inflammatory cytokines (P < 0.001 for IL-6, TNFα, IL-1β and TGFβ). Data were confirmed by WB and RT-PCR analysis.

Conclusions

Optimal concentrations of CTLA4-Ig for the CTLA4-Ig/B7.2 masking on activated macrophages were identified and were found to induce significant downregulation in the cell production of IL-6, TNFα, IL1-β and TGFβ. In conclusion, macrophages would appear to be a sensitive target for CTLA4-Ig treatment in RA.

Local interleukin-1-driven joint pathology is dependent on toll-like receptor 4 activation

Toll-like receptors (TLRs) may contribute to the pathogenesis of chronic inflammatory destructive diseases through the recognition of endogenous ligands produced on either inflammation or degeneration of the extracellular matrix. The presence of endogenous TLR agonists has been reported in rheumatoid joints. In the present study, we investigated the significance of TLR2 and TLR4 activation by locally- produced endogenous ligands in the severity of joint inflammation and destruction. Local joint pathology independent of systemic immune activation was induced by overexpression of interleukin (IL)-1 and TNF in naive joints using adenoviral gene transfer. Here, we report that at certain doses, IL-1-induced local joint inflammation, cartilage proteoglycan depletion, and bone erosion are dependent on TLR4 activation, whereas TLR2 activation is not significantly involved. In comparison, tumor necrosis factor alpha-driven joint pathology seemed to be less dependent on TLR2 and TLR4. The severity of IL-1-induced bone erosion and irreversible cartilage destruction was markedly reduced in TLR4(-/-) mice, even though the degree of inflammation was similar, suggesting uncoupled processes. Furthermore, the expression of cathepsin K, a marker for osteoclast activity, induced by IL-1beta was dependent on TLR4. Overexpression of IL-1beta in the joint as well as ex vivo IL-1 stimulation of patellae provoked the release of endogenous TLR4 agonists capable of inducing TLR4-mediated cytokine production. These data emphasize the potential relevance of TLR4 activation in rheumatoid arthritis, particularly with respect to IL-1-mediated joint pathology.

Cytokines in chronic rheumatic diseases: is everything lack of homeostatic balance?

Biological systems have powerful inbuilt mechanisms of control intended to maintain homeostasis. Cytokines are no exception to this rule, and imbalance in cytokine activities may lead to inflammation with subsequent tissue and organ damage, altered function, and death. Balance is achieved through multiple, not mutually exclusive, mechanisms including the simultaneous production of agonist and antagonistic cytokines, expression of soluble receptors or membrane-bound nonsignaling receptors, priming and/or reprogramming of signaling, and uncoupling of ligand/receptor pairing from signal transduction. Insight into cytokine balance is leading to novel therapeutic approaches particularly in autoimmune conditions, which are intimately linked to a dysregulated cytokine production.

Developments in the scientific understanding of rheumatoid arthritis

Rheumatoid arthritis (RA) is recognized to be an autoimmune disease that causes preclinical systemic abnormalities and eventually leads to synovial inflammation and destruction of the joint architecture. Recently identified genetic risk factors and novel insights from animal models of spontaneous arthritis have lent support to the concept that thymic selection of an autoreactive T-cell repertoire is an important risk factor for this disease. With advancing age, defects in the homeostatic control of the T-cell pool and in the setting of signaling thresholds lead to the accumulation of pro-inflammatory T-effector cell populations and loss of tolerance to neo-antigens, such as citrullinated peptides. As the breakdown of tolerance to modified self-antigens can precede synovitis by decades, repair of homeostatic defects may open a unique window of opportunity for preventive interventions in RA. The end result of RA, destruction of cartilage and bone, appears to be driven by cytokine- and cell contact-induced activation of synoviocytes and monocytic cells, some of which differentiate into tissue-destructive osteoclasts. Targeting mediators involved in this process has greatly improved the management of this chronic inflammatory syndrome.

Unexpected matrix diseases and novel therapeutic strategies

Within the framework of a broad definition of the extracellular matrix (ECM), this review discusses three genetic disorders in which major pathogenetic features have been traced back to alterations in the levels/activities of matrix components. In each case, disease-associated alterations are found both intra- and extracellularly. The nature of the ECM involvement is surprising, offers an exciting therapeutic opportunity, and deepens our understanding of ECM-cell interactions. The first of these disorders, cherubism, is a case of inflammatory bone loss in the jaws of children for reasons that are surprisingly systemic in nature, considering the local nature of the disease. The primary defect involves an intracellular signaling molecule, but a major pathogenetic component and therapeutic target of the disease is the extracellular cytokine tumor necrosis factor alpha. The second disorder, Knobloch syndrome, is caused by recessive mutations in collagen XVIII. Although this protein has been classified as belonging to a group of structural macromolecules, the consequence of the mutations is impairment of cellular metabolism. The third disorder, infantile hemangioma, is a common tumor of capillary endothelial cells in infancy. The tumor appears within a few days/weeks after birth, grows rapidly over several months, and regresses over several years. The proliferative phase is the result of constitutively high levels of vascular endothelial cell growth factor (VEGF)-dependent signaling through VEGF receptor 2 (VEGFR2), but recent studies have led to the surprising conclusion that abnormalities in a cell-surface receptor complex controlling expression of the VEGF decoy receptor VEGFR1 is the underlying cause.

Biologics for rheumatoid arthritis: an overview of Cochrane reviews

BACKGROUND

The biologic disease-modifying anti-rheumatic drugs (DMARDs) are very effective in treating rheumatoid arthritis (RA), however there is a lack of head-to-head comparison studies.

OBJECTIVES

To compare the efficacy and safety of abatacept, adalimumab, anakinra, etanercept, infliximab, and rituximab in patients with RA.

METHODS

This 'Overview of Reviews' was done by including all Cochrane Reviews on Biologics for RA available in The Cochrane Library. We included only data on standard dosing regimens for these biologic DMARDs from placebo-controlled trials. The primary efficacy and safety outcomes were ACR50 and withdrawals due to adverse events. We calculated Risk Ratios (RR) for efficacy, Odds Ratio (OR) for safety and combined estimates of events across the placebo groups as the expected Control Event Rate (CER). Indirect comparisons of biologics were performed for efficacy and safety using a hierarchical linear mixed model incorporating the most important study-level characteristic (i.e. type of biologic) as a fixed factor and study as a random factor; reducing the between study heterogeneity by adjusting for the interaction between the proportion of patients responding on placebo and the duration of the trial.

MAIN RESULTS

From the six available Cochrane reviews, we obtained data from seven studies on abatacept, eight on adalimumab, five on anakinra, four on etanercept, four on infliximab, and three on rituximab.The indirect comparison estimates showed similar efficacy for the primary efficacy outcome for all biologics with three exceptions. Anakinra was less efficacious than etanercept with a ratio of RRs (95% CI; P value) of 0.44 (0.23 to 0.85; P = 0.014); anakinra was less efficacious than rituximab, 0.45 (0.22 to 0.90; P = 0.023); and likewise adalimumab was more efficacious than anakinra, 2.34 (1.32 to 4.13; P = 0.003).In terms of safety, adalimumab was more likely to lead to withdrawals compared to etanercept, with a ratio of ORs of 1.89 (1.18 to 3.04; P = 0.009); anakinra more likely than etanercept, 2.05 (1.27 to 3.29; P = 0.003); and likewise etanercept less likely than infliximab, 0.37 (0.19 to 0.70; P = 0.002).

AUTHORS' CONCLUSIONS

Based upon indirect comparisons, anakinra seemed less efficacious than etanercept, adalimumab and rituximab and etanercept seemed to cause fewer withdrawals due to adverse events than adalimumab, anakinra and infliximab. Significant heterogeneity in characteristics of trial populations imply that these finding must be interpreted with caution. These findings can inform physicians and patients regarding their choice of biologic for treatment of RA.

Recent advances in neutralizing the IL-6 pathway in arthritis

Recent advances in understanding the mechanism(s) of how IL-6 trans-signaling regulates immune cell function and promotes inflammation in autoimmune arthritis are critically reviewed. Serum and/or synovial fluid (SF) IL-6 is markedly elevated in adult and juvenile rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS) and osteoarthritis (OA). IL-6, in concert with IL-17, determines the fate of CD4⁺ lymphocytes and therefore TH₁₇ cell differentiation. IL-6 also plays a critical role in modulating B-lymphocyte activity. The recognition that IL-6 trans-signaling regulates inflammation resulted in the development of tocilizumab, a fully humanized monoclonal antibody that neutralizes the biological activity of the IL-6-receptor (IL-6R). Significant clinical benefit was demonstrated as well as reduced serum IL-6 levels with suppression of X-ray progression of disease in several clinical trials in which juvenile or adult RA patients were treated with tocilizumab monotherapy or tocilizumab plus methotrexate. However, levels of serum and/or SF IL-6 cytokine protein superfamily members, adiponectin, oncostatin M, pre-B-cell colony enhancing factor/visfatin and leukemia inhibitory factor are also elevated in RA. Additional studies will be required to determine if anti-IL-6 trans-signaling inhibition strategies with tocilizumab or recombinant soluble IL-6R reduce the level of these cytokines.

Anti-inflammatory effect of Inonotus obliquus, Polygala senega L., and Viburnum trilobum in a cell screening assay

AIM OF THE STUDY

The purpose of the study was to assess the anti-inflammatory effects of the mushroom Inonotus obliquus (Chaga), Polygala senega (Senega) and Viburnum trilobum (Cranberry) bark extract fractions from locally produced materials in lipopolysaccharide (LPS) induced murine macrophage RAW 164.7 cells.

MATERIALS AND METHODS

Four fractions from each of the three extracts were obtained: (80% ethanol extracted; Fa), (water-soluble polysaccharide fraction; Fb), (Polyphenolic fraction; Fc) and (ETOAc/H(2)O extracted fraction; Fd). These extract fractions were tested in the cell screening system at 50,100 and 500 microg/ml for their ability to inhibit LPS induced inflammatory cytokines IL-1beta, TNFalpha and IL-6. Supernatants from LPS alone treated cells were used as control. The cytokines in the cell culture supernatants following treatments with extract fractions were quantified by ELISA method, using 96 well ELISA plates.

RESULTS

All fractions of the extracts significantly inhibited (p<0.05) the levels of IL-1beta, IL-6 and TNFalpha except the polyphenolic Fc fraction of Senega which showed an increased production of IL-6. Furthermore, each fraction showed a dose-dependant anti-inflammatory effect. Nitric oxide production was not affected by cranberry and senega, while Chaga significantly reduced NO production in murine macrophage cell assay.

CONCLUSIONS

These results demonstrate that the extracts obtained from the root of Polygala senega L., bark of Viburnum trilobum, and the mushroom Inonotus obliquus possess anti-inflammatory properties when tested in a RAW 264.7 macrophage cell system.

Tumour necrosis factor gene polymorphism: a predictive factor for the development of post-transplant lymphoproliferative disease

Background:

Epstein–Barr virus-positive post-transplant lymphoproliferative disease (PTLD) is a potentially lethal complication of iatrogenic immunosupression after transplantation. Predicting the development of PTLD allowing early and effective intervention is therefore of importance. Polymorphisms within cytokine genes are implicated in susceptibility to, and progression of, disease however the published data are often conflicting. We undertook investigation of polymorphic alleles within cytokine genes in PTLD and non-PTLD transplant cohorts to determine risk factors for disease.

Methods:

SSP-PCR was used to analyse single nucleotide polymorphism within tumour necrosis factor (TNF)-α, interleukin- 1, -6, -10 and lymphotoxin-α genes. The TNF-α levels were measured by standard enzyme-linked immuno-absorbant assay.

Results:

We show an association between variant alleles within the TNF-α promoter (−1031C (P=0.005)); −863A (P=0.0001) and TNF receptor I promoter regions (−201T (P=0.02)); −1135C (P=0.03) with the development of PTLD. We also show an association with TNF-α promoter haplotypes with haplotype-3 significantly increased (P=0.0001) and haplotype-1 decreased (P=0.02) in PTLD patients compared to transplant controls. Furthermore, we show a significant increase (P=0.02) in the level of TNF-α in PTLD patient plasma (range 0–97.97 pg ml⁻¹) compared to transplant controls (0–8.147 pg ml⁻¹), with the highest levels found in individuals carrying the variant alleles.

Conclusion:

We suggest that genetic variation within TNF-α loci and the level of plasma cytokine could be used as a predictive risk factor for the development of PTLD.

[Visualizing arterial macrophage warfare with nuclear magnetic resonance, positron-emission tomography and computerized tomography]

The macrophage is the principal immune cell found in atherosclerotic plaque. Although its function is to phagocytose foreign bodies present in the vascular endothelium, it can undergo a process of sustained activation that gives rise to a pattern of chronic inflammation, which may even trigger an acute coronary syndrome. The cellular response underlying this disease process is mediated by a complex molecular signaling cascade. Cytokines released by activated macrophages ultimately produce significant tissue damage by perpetuating the ongoing inflammatory response. Recent studies have shown that a defective interaction between the macrophage and its substrate could provide a mechanism for destabilizing atherosclerotic plaque by stimulating digestion of the artery and promoting plaque rupture. A key element in the life cycle of macrophages is that, when they cannot effectively remove the foreign bodies that have resulted in their activation, they initiate cell death (i.e., apoptosis), thereby releasing substances into the extracellular milieu that are even more toxic than inflammatory mediators. The significant advances in noninvasive molecular imaging techniques that have taken place in recent years have helped to unravel fundamental features of macrophage biology and have made it possible to explore the potential benefits of specific therapeutic interventions. Nanomarkers designed to home in on specific molecular targets have enabled imaging techniques to be used not only to study the pathophysiological mechanisms of atherosclerotic disease but also to diagnose such disease, and have made it possible to imagine the development of a form of nanomedicine based on administering treatment that can target a single cell type.

Dichloroacetate alleviates development of collagen II-induced arthritis in female DBA/1 mice

INTRODUCTION

Dichloroacetate (DCA) has been in clinical use for the treatment of lactacidosis and inherited mitochondrial disorders. It has potent anti-tumor effects both in vivo and in vitro, facilitating apoptosis and inhibiting proliferation. The pro-apoptotic and anti-proliferative properties of DCA prompted us to investigate the effects of this compound in arthritis.

METHODS

In the present study, we used DCA to treat murine collagen type II (CII)-induced arthritis (CIA), an experimental model of rheumatoid arthritis. DBA/1 mice were treated with DCA given in drinking water.

RESULTS

Mice treated with DCA displayed much slower onset of CIA and significantly lower severity (P < 0.0001) and much lower frequency (36% in DCA group vs. 86% in control group) of arthritis. Also, cartilage and joint destruction was significantly decreased following DCA treatment (P = 0.005). Moreover, DCA prevented arthritis-induced cortical bone mineral loss. This clinical picture was also reflected by lower levels of anti-CII antibodies in DCA-treated versus control mice, indicating that DCA affected the humoral response. In contrast, DCA had no effect on T cell- or granulocyte-mediated responses. The beneficial effect of DCA was present in female DBA/1 mice only. This was due in part to the effect of estrogen, since ovariectomized mice did not benefit from DCA treatment to the same extent as sham-operated controls (day 30, 38.7% of ovarectomized mice had arthritis vs. only 3.4% in sham-operated group).

CONCLUSION

Our results indicate that DCA delays the onset and alleviates the progression of CIA in an estrogen-dependent manner.

Sex hormones and leflunomide treatment of human macrophage cultures: effects on apoptosis

In order to establish the possible gender influence on the activity of leflunomide (LEF) in rheumatoid arthritis (RA), we evaluated the proapoptotic activity of the active LEF metabolite A77 1726 (LEF-M), in combination with sex hormones, on cultures of human macrophages. In particular, we focussed our investigation on the triggering phase of the apoptosis. Cultures of macrophages from activated THP-1 cells and from RA synovial tissues were treated with LEF-M alone [30muM] or in presence of 17beta-estradiol (E2) (10(-9)M) or testosterone (T) (10-(8)M) for 24 hours. FAS, FAS-L, FADD (Fas-Associated via Death Domain) and FLICE (FADD-Like Interleukin-1 beta Converting Enzyme) were evaluated by immunocytochemistry (ICC), Western blot (WB) and reverse transcriptase-multiplex polymerase chain reaction (RT-MPCR). Regarding macrophages from THP-1 cells (M), the ICC showed that LEF-M exerted a significant up-regulation on all investigated apoptotic proteins, when compared to untreated cells (control) (p<0.001). On the contrary, E2 significantly increased FAS-L positivity (p<0.05) and down-regulated FADD (p<0.01), while others apoptotic proteins were not modulated when compared to control. Regarding RA synovial macrophages (SM), the ICC showed that LEF-M exerted a significant up-regulation on FAS and FAS-L when compared to control (p<0.001). On the contrary, E2 down-regulated significantly FAS-L (p<0.001), while FAS was not modulated respect to control. T significantly increased the apoptotic proteins in all conditions. The results of the present study suggests a less efficient therapeutic effect of LEF in female patients, due to the contrasting action of estrogens on LEF- induced apoptosis.

Clinical efficacy of tocilizumab in patients with active rheumatoid arthritis in real clinical practice

The previous clinical studies have demonstrated tocilizumab monotherapy to be highly effective in rheumatoid arthritis (RA). The objectives of the present article are to report the efficacy and safety of tocilizumab in patients with active RA in real clinical practice. In total, 61 patients with RA were treated with tocilizumab. Any comorbidities they had, especially infections, were treated thoroughly before they were given the drug. We provided guidance on infection control and prevention. Mean age of the patients was 60.9 +/- 12.4 years, and their mean disease duration 10.9 +/- 9.2 years. The patients remained on steroids, methotrexate, and tacrolimus as before, but were taken off any other drugs they had been using prior to the treatment. Mean of the 28-joint disease activity score using erythrocyte sedimentation rate was 4.75 +/- 1.15 initially and fell to 2.21 +/- 0.97 after two doses (n = 50). After four doses, the remission rate was 83.8% (31/37). All patients responded well to the therapy and there was no decrease in the efficacy of tocilizumab during the treatment. Even in the real clinical setting, treatment with tocilizumab can rapidly induce remission in RA in a high proportion of patients and is generally safe and well tolerated. Tocilizumab would seem to be promising as a first-line choice for the treatment of RA.

Site-specific production of IL-6 in the central nervous system retargets and enhances the inflammatory response in experimental autoimmune encephalomyelitis

IL-6 is crucial for the induction of many murine models of autoimmunity including experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. To establish the role of site-specific production of IL-6 in autoimmunity, we examined myelin oligodendrocyte glycoprotein immunization-induced EAE in transgenic mice (GFAP-IL6) with IL-6 production restricted to the cerebellum. Myelin oligodendrocyte glycoprotein-immunized (Mi-) GFAP-IL6 mice developed severe ataxia but no physical signs of spinal cord involvement, which was in sharp contrast to Mi-wild type (WT) animals that developed classical EAE with ascending paralysis. Immune pathology and demyelination were nearly absent from the spinal cord, but significantly increased in the cerebellum of Mi-GFAP-IL6 mice. Tissue damage in the cerebellum in the Mi-GFAP-IL6 mice was accompanied by increased total numbers of infiltrating leukocytes and increased proportions of both neutrophils and B-cells. With the exception of IL-17 mRNA, which was elevated in both control immunized and Mi-GFAP-IL6 cerebellum, the level of other cytokine and chemokine mRNAs were comparable with Mi-WT cerebellum whereas significantly higher levels of IFN-gamma and TNF-alpha mRNA were found in Mi-WT spinal cord. Thus, site-specific production of IL-6 in the cerebellum redirects trafficking away from the normally preferred antigenic site the spinal cord and acts as a leukocyte "sink" that markedly enhances the inflammatory cell accumulation and disease. The mechanisms underlying this process likely include the induction of specific chemokines, activation of microglia, and activation and loss of integrity of the blood-brain barrier present in the cerebellum of the GFAP-IL6 mice before the induction of EAE.

Distinct roles of sphingosine kinase 1 and 2 in murine collagen-induced arthritis

Sphingosine kinase (SphK) phosphorylates sphingosine into sphingosine-1-phosphate (S1P). S1P plays a critical role in angiogenesis, inflammation, and various pathologic conditions. To date, two mammalian isoenzymes, SphK1 and SphK2, have been identified. Although both SphK1 and SphK2 share overall homology and produce the common product, S1P, it has been proposed they display different unique and separate functions. In this study, we examined the role of SphK1 and SphK2 in a murine collagen-induced arthritis model by down-regulating each isoenzyme via specific small interfering RNA (siRNA). Prophylactic i.p. administration of SphK1 siRNA significantly reduced the incidence, disease severity, and articular inflammation compared with control siRNA recipients. Treatment of SphK1 siRNA also down-regulated serum levels of S1P, IL-6, TNF-alpha, IFN-gamma, and IgG2a anti-collagen Ab. Ex vivo analysis demonstrated significant suppression of collagen-specific proinflammatory/Th1 cytokine (IL-6, TNF-alpha, IFN-gamma) release in SphK siRNA-treated mice. Interestingly, mice received with SphK2 siRNA develop more aggressive disease; higher serum levels of IL-6, TNF-alpha, and IFN-gamma; and proinflammatory cytokine production to collagen in vitro when compared with control siRNA recipients. Together, these results demonstrate the distinct immunomodulatory roles of SphK1 and SphK2 in the development of inflammatory arthritis by regulating the release of proinflammatory cytokines and T cell responses. These findings raise the possibility that drugs which specifically target SphK1 activity may play a beneficial role in the treatment of inflammatory arthritis.

Role of Schlafen 2 (SLFN2) in the generation of interferon alpha-induced growth inhibitory responses

The precise STAT-regulated gene targets that inhibit cell growth and generate the antitumor effects of Type I interferons (IFNs) remain unknown. We provide evidence that Type I IFNs regulate expression of Schlafens (SLFNs), a group of genes involved in the control of cell cycle progression and growth inhibitory responses. Using cells with targeted disruption of different STAT proteins and/or the p38 MAP kinase, we demonstrate that the IFN-dependent expression of distinct Schlafen genes is differentially regulated by STAT complexes and the p38 MAP kinase pathway. We also provide evidence for a key functional role of a member of the SLFN family, SLFN2, in the induction of the growth-suppressive effects of IFNs. This is shown in studies demonstrating that knockdown of SLFN2 enhances hematopoietic progenitor colony formation and reverses the growth-suppressive effects of IFNalpha on normal hematopoietic progenitors. Importantly, NIH3T3 or L929 cells with stable knockdown of SLFN2 form more colonies in soft agar, implicating this protein in the regulation of anchorage-independent growth. Altogether, our data implicate SLFN2 as a negative regulator of the metastatic and growth potential of malignant cells and strongly suggest a role for the SLFN family of proteins in the generation of the antiproliferative effects of Type I IFNs.

Molecular construction and optimization of anti-human IL-1alpha/beta dual variable domain immunoglobulin (DVD-Ig) molecules

Signal transduction through the interleukin-1 receptor (IL-1R) pathway mediates a strong pro-inflammatory response, which contributes to a number of human diseases such as rheumatoid arthritis. Within the IL-1 family, IL-1alpha and IL-1beta are both agonistic ligands for IL-1R, whereas IL-1 receptor antagonist (IL-1ra) is an endogenous antagonist that binds to IL-R, but does not signal. Therefore, the ideal therapeutic strategy would be blocking both IL-1alpha and IL-1beta, but not IL-1ra. However, due to low sequence homology between the three members of the family, it has been exceedingly difficult to identify potent therapeutic agents, e.g., monoclonal antibodies (mAbs), that selectively recognize both IL-1alpha and IL-1beta, but not IL-1ra. Currently, several anti-IL-1 therapeutic agents in clinical development either inhibit only IL-1beta (i.e., anti-IL-1beta mAb), or recognize all three ligands (i.e., anti-IL-1R mAb or IL-1R Trap). We have recently developed a novel dual variable domain immunoglobulin (or DVD-Ig) technology that enables engineering the distinct specificities of two mAbs into a single functional, dual-specific, tetravalent IgG-like molecule. Based on this approach, we have developed anti-human IL-1alpha/beta DVD-Ig molecules using several pairs of monoclonal antibodies with therapeutic potential, and present a case study for optimal design of a DVD-Ig agent for a specific target pair combination.

Alpha9 integrin and its ligands constitute critical joint microenvironments for development of autoimmune arthritis

Osteopontin is critically involved in rheumatoid arthritis; however, the molecular cross-talk between osteopontin and joint cell components that leads to the inflammatory joint destruction is largely unknown. We found that not only osteopontin but also tenascin-C and their common receptor, alpha(9) integrin, are expressed at arthritic joints. The local production of osteopontin and tenascin-C is mainly due to synovial fibroblasts and, to a lesser extent, synovial macrophages. Synovial fibroblasts and macrophages express alpha(9) integrin, and autocrine and paracrine interactions of alpha(9) integrin on synovial fibroblasts and macrophages and its ligands contribute differently to the production of proinflammatory cytokines and chemokines. alpha(9) integrin is also involved in the recruitment and accumulation of inflammatory cells. Inhibition of alpha(9) integrin function with an anti-alpha(9) integrin Ab significantly reduces the production of arthrogenic cytokines and chemokines and ameliorates ongoing arthritis. Thus, we identified alpha(9) integrin as a critical intrinsic regulator that controls the development of autoimmune arthritis.

Myelodysplasia and acute leukemia as late complications of marrow failure: future prospects for leukemia prevention

Patients who have acquired and inherited bone marrow failure syndromes are at risk for the development of clonal neoplasms including acute myeloid leukemia, myelodysplastic syndrome, and paroxysmal nocturnal hemoglobinuria. This article reviews the evidence supporting a model of clonal selection, a paradigm that provides a reasonable expectation that these often fatal complications might be prevented in the future.

Many cytokines are very useful therapeutic targets in disease

Cytokines are a large family of more than 100 small proteins that function as short-range mediators involved in essentially all biological processes. They have been found to be important rate-limiting signals, and it is now known that blocking some cytokines, e.g., TNF-alpha, and cytokine receptors, such as human EGFR 1 (HER1) or HER2, yields effective therapeutics that address unmet needs. This Review Series surveys three chronic inflammatory disease areas and two forms of cancer and discusses the important role of cytokines and their receptors in these disease processes. Their role as potential therapeutic targets is also highlighted.

Epitope spreading initiates in the CNS in two mouse models of multiple sclerosis

Introduction

Mouse models of rheumatoid arthritis (RA) have proven critical for identifying genetic and cellular mechanisms of the disease. Upon discovering mice in our breeding colony that had spontaneously developed inflamed joints reminiscent of RA, we established the novel IIJ (inherited inflamed joints) strain. The purpose of this study was to characterize the histopathological, clinical, genetic and immunological properties of the disease.

Methods

To begin the IIJ strain, an arthritic male mouse was crossed with SJL/J females. Inheritance of the phenotype was then tracked by intercrossing, backcrossing and outcrossing to other inbred strains. The histopathology of the joints and extraarticular organ systems was examined. Serum cytokines and immunoglobulins (Igs) were measured by ELISA and cytometric bead array. Transfer experiments tested whether disease could be mediated by serum alone. Finally, the cellular joint infiltrate and the composition of secondary lymphoid organs were examined by immunohistochemistry and flow cytometry.

Results

After nine generations of intercrossing, the total incidence of arthritis was 33% (304 of 932 mice), with females being affected more than males (38% vs. 28%; P < 0.001). Swelling, most notably in the large distal joints, typically became evident at an early age (mean age of 52 days). In addition to the joint pathology, which included bone and cartilage erosion, synovial hyperproliferation and a robust cellular infiltration of mostly Gr-1⁺ neutrophils, there was also evidence of systemic inflammation. IL-6 was elevated in the sera of recently arthritic mice, and extraarticular inflammation was observed histologically in multiple organs. Total serum Ig and IgG1 levels were significantly elevated in arthritic mice, and autoantibodies such as rheumatoid factor and Ig reactive to joint components (collagen type II and joint homogenate) were also detected. Nevertheless, serum failed to transfer disease. A high percentage of double-negative (CD4^-CD8^-) CD3⁺ TCRα/β⁺ T cells in the lymphoid organs of arthritic IIJ mice suggested significant disruption in the T-cell compartment.

Conclusions

Overall, these data identify the IIJ strain as a new murine model of inflammatory, possibly autoimmune, arthritis. The IIJ strain is similar, both histologically and serologically, to RA and other murine models of autoimmune arthritis. It may prove particularly useful for understanding the female bias in autoimmune diseases.