BMC - Arthritis Research and Therapy

IntroductionInfrapatellar fat pad (IPFP) is a possible source of stem cells for the repair of articular cartilage defects. In this study adherent proliferative cells were isolated from digests of IPFP tissue. The effects of the expansion of these cells in FGF-2 were tested on their proliferation, characterisation and chondrogenic potential. Methods: IPFP tissue was obtained from six patients undergoing total knee replacement and sections were stained with 3G5, SMA and vWF to identify different cell types in the vasculature. Cells were isolated from IPFP, and both mixed populations and clonal lines derived from them were characterised for cell surface epitopes including 3G5. Cells were expanded with and without FGF-2 and were tested for chondrogenic differentiation in cell aggregate cultures. Results: 3G5 positive cells were present in perivascular regions in tissue section of the IPFP and proliferative adherent cells isolated from the IPFP were also 3G5 positive. However, 3G5 expression was only on a small proportion of cells in all populations and at all passages, including the clonally expanded cells. The cells showed cell surface epitope expression similar to adult stem cells. They stained strongly for CD13, CD29, CD44, CD90 and CD105 and were negative for CD34 and CD56, but also negative for LNGFR and STRO1. The IPFP derived cells showed chondrogenic differentiation in cell aggregate cultures and prior expansion with FGF-2 enhanced chondrogenesis. Expansion in FGF-2 resulted in greater down-regulation of many cartilage-associated genes, but on subsequent chondrogenic differentiation they showed stronger up-regulation of these genes and this resulted in greater matrix production per cell. Conclusions: These results show that these cells express mesenchymal stem cell markers but further work is needed to determine the true origin of these cells. These results suggest that expansion of these cells with FGF-2 has important consequences for facilitating their chondrogenic differentiation.

IntroductionDespite the advent of biological therapies for treatment of rheumatoid arthritis (RA), there is a compelling need to develop alternative therapeutic targets for non-responders to existing treatments. Soluble receptors occur naturally in vivo, such as the splice variant of the cell surface receptor for vascular endothelial growth factor (VEGF), a key regulator of angiogenesis in RA. Bioinformatics analyses predict that the majority of human genes undergo alternative splicing, generating proteins, many of which may have regulatory functions. The goal of this study was to identify alternative splice variants (ASV) from cell surface receptor genes, and to determine whether the novel proteins encoded exert therapeutic activity in an in vivo model of arthritis. Methods: To identify novel splice variants, we performed RT-PCR using an mRNA pool representing major human tissue types and tumors. Novel ASV were identified by alignment of each cloned sequence to its respective genomic sequence in comparison with full-length transcripts. To test whether these ASV have biologic activity, we characterized a subset of them for ligand binding, and for efficacy in an animal model of arthritis. The in vivo study was accomplished using adenoviruses expressing secreted ASV. Results: We cloned 60 novel human ASV from 21 genes, encoding cell surface receptors, many of which are known to be important in the regulation of angiogenesis. The ASV were characterized by exon extension, intron retention and alternative exon utilization. Efficient expression and secretion of selected ASV - corresponding to VEGFR1, VEGFR2, VEGFR3, angiopoietin receptor Tie1, Met (receptor for hepatocyte growth factor), colony stimulating factor (CSF)1R, platelet-derived growth factor (PDGF)R, fibroblast growth factor (FGF)R1, Kit and RAGE - was demonstrated, together with binding to their cognate ligands. Importantly, ASV derived from VEGFR1 and Tie1, and to a lesser extent from VEGFR2 and FGFR1, reduced clinical signs of arthritis in vivo. The reduction was paralleled by decreased joint inflammation and destruction. Conclusions: Our study shows that unique ASV derived from receptors which play key roles in angiogenesis - namely VEGFR1 and, for the first time, Tie1 - can markedly reduce arthritis severity. More broadly, our results demonstrate that ASV are a source of novel proteins with therapeutic potential, in diseases in which angiogenesis and cellular hyperplasia play a central role, such as RA.

High-mobility group box protein 1 (HMGB1) is a non-histone nuclear protein that has a dual function. Inside the cell, HMGB1 binds DNA, regulating transcription and determining chromosomal architecture. Outside the cell, HMGB1 can serve as an alarmin to activate the innate system and mediate a wide range of physiological and pathological responses. To function as an alarmin, HMGB1 translocates from the nucleus of the cell to the extra-cellular milieu, a process that can take place with cell activation as well as cell death. HMGB1 can interact with receptors that include RAGE (receptor for advanced glycation endproducts) as well as Toll-like receptor-2 (TLR-2) and TLR-4 and function in a synergistic fashion with other proinflammatory mediators to induce responses. As shown in studies on patients as well as animal models, HMGB1 can play an important role in the pathogenesis of rheumatic disease, including rheumatoid arthritis, systemic lupus erythematosus, and polymyositis among others. New approaches to therapy for these diseases may involve strategies to inhibit HMGB1 release from cells, its interaction with receptors, and downstream signaling.

IntroductionTNFalpha and HMGB1 are two potent pro-inflammatory cytokines implicated as important mediators of arthritis. Increased levels of these cytokines are found in the joints of RA patients and they trigger arthritis when applied into the joints of naive mice. HMGB1 is actively released from immune cells in response to TNFalpha and once released, it induces in turn production of several pro-inflammatory cytokines including IL-6 and TNFalpha by macrophages. However, it is unknown whether HMGB1-induced arthritis is mediated via TNFalpha pathway. The purpose of this study was to investigate whether the arthritis-inducing effect of HMGB1 is dependent on TNFalpha expression in vivo and to assess whether TNFalpha deficiency affects a pro-inflammatory cytokine response to HMGB1 in vitro. Methods: TNFalpha knockout (KO) mice and backcrossed control animals on C57Bl6 background were injected intra-articularly (i.a.) with 5 micrograms of HMGB1. Joints were dissected three days after i.a. injection and evaluated histologically by scoring the frequency and severity of arthritis. For in vitro studies, mouse spleen cultures from TNFalpha KO and control mice were incubated with different doses of HMGB1and cell culture supernatants were collected at different time points for analysis of IL-6. Results: I.a. injection of HMGB1 into healthy mouse joints resulted in overall frequency of 32-39 % arthritic animals. No significant differences were found with respect to severity and incidence of synovitis between mice deficient for TNFalpha (7 out of 18 mice with arthritis) in comparison with control TNFalpha+/+ animals (6 out of 19). No significant differences were detected between spleen cells from TNFalpha+/+ versus TNFalpha-/- mice regarding IL-6 production upon stimulation with highly purified HMGB1 following 24 and 48 hours. However, upon stimulation with suboptimal dose of recombinant HMGB1, the splenocytes from TNFalpha+/+ animals released significantly more IL-6 than cells from the knockout mice (602 +/- 112 and 304 +/- 50 pg/ml, respectively, p

IntroductionSubchondral bone alterations represent an essential component of osteoarthritis (OA). Modifying the abnormal subchondral bone metabolism may be indicated to treat OA. We investigated the effect of diacerein and rhein on the changes occurring in subchondral bone during OA. To this end, we determined the drugs' effects on MMP-13 synthesis on subchondral bone and on the osteoblast signalling pathways. In osteoclasts, we studied MMP-13 and cathepsin K production, as well as cell differentiation, proliferation and survival. Methods: The effect of diacerein/rhein on the production of subchondral bone MMP-13 was determined by ELISA. Signalling pathways were evaluated on osteoblasts by Western blot. Osteoclast experiments were performed using the pre-osteoclastic cells, Raw 264.7. Osteoclast MMP-13 and cathepsin K activities were determined by specific bioassays and differentiation of these cells quantified by TRAP staining. Results: Diacerein and rhein reduced in a dose-dependent manner the IL-1beta-induced MMP-13 production in OA subchondral bone. This effect occurred through the inhibition of ERK1/2 and p38. In osteoclasts, they significantly reduced the activity of MMP-13 and cathepsin K. Moreover, these drugs effectively blocked the IL-1beta effect on the osteoclast differentiation process and the survival of mature osteoclasts. Conclusions: Altogether these data suggest that diacerein/rhein could impact the abnormal subchondral bone metabolism in OA by reducing the synthesis of resorptive factors and osteoclast formation.

IntroductionDisease activity in patients with rheumatoid arthritis (RA) is associated with increased cardiovascular morbidity and mortality of which N-terminal pro-brain natriuretic peptide (NT-proBNP) is a predictor. Our objective was to examine the cross-sectional and longitudinal associations between markers of inflammation, measures of RA disease activity, medication used in the treatment of RA and NT-proBNP levels (dependent variable). Methods: Two hundred and thirty-eight patients with RA of less than 4 years duration were followed longitudinally with three comprehensive assessments of clinical and radiographic data over a 10-year period. Serum samples were frozen and later batch-analyzed for NT-proBNP levels and other biomarkers. Bivariate, multivariate and repeated analyses were performed. Results: C-reactive protein (CRP) levels at baseline were cross-sectionally associated to NT-proBNP levels after adjustment for age and sex (r^2 adjusted = 0.23; p

IntroductionIn the nonobese diabetic (NOD) mouse model for Sjogren's Syndrome, lymphocytic infiltration is preceded by an accumulation of dendritic cells (DC) in the submandibular glands (SMG). NOD mice also display an increased frequency of mature, fractalkine receptor (CX3CR1) expressing monocytes, which are considered to be precursors for tissue DC. To further unravel the role of fractalkine-CX3CR1 interactions in the salivary gland inflammation, we studied the expression of fractalkine in NOD SMG. Methods: Protein expression was studied by Western blot analysis of whole tissue lysates. Protease activity was measured in salivary gland tissue lysates using fluorimetric substrates. Digestive capacity of enzymes was determined by in vitro incubation of recombinant enzyme and fractalkine, followed by protein staining and Western Blot. Results: Fractalkine was detected in salivary glands of both NOD and control mice at all ages. Western blot analysis showed fractalkine cleavage with increasing age, which was more pronounced in NOD mice. This cleavage resulted in a decrease of the 31 kDa form of the protein, and the generation of a ~19 kDa band. Furthermore, NOD animals over 15 weeks of age showed the presence of a unique ~17 kDa fragment. This cleavage was organ specific, as it did not occur in brain or pancreas. Increased gelatinase and alpha-secretase activity were detected in NOD SMG and contribute to the cleavage of the 31 kDa protein. Since aberrant cleavage products may induce autoimmunity, we studied the presence of autoantibodies against fractalkine. Indeed, NOD mice showed significantly more antibodies against fractalkine than control animals. Conclusions: This data indicates that aberrant proteolytic activity in the NOD SMG results in increased fractalkine cleavage and the generation of a unique fractalkine fragment. This specific cleavage may contribute to autoimmunity.

IntroductionIn the nonobese diabetic (NOD) mouse model for Sjogren's Syndrome, lymphocytic infiltration is preceded by an accumulation of dendritic cells (DC) in the submandibular glands (SMG). NOD mice also display an increased frequency of mature, fractalkine receptor (CX3CR1) expressing monocytes, which are considered to be precursors for tissue DC. To further unravel the role of fractalkine-CX3CR1 interactions in the salivary gland inflammation, we studied the expression of fractalkine in NOD SMG. Methods: Protein expression was studied by Western blot analysis of whole tissue lysates. Protease activity was measured in salivary gland tissue lysates using fluorimetric substrates. Digestive capacity of enzymes was determined by in vitro incubation of recombinant enzyme and fractalkine, followed by protein staining and Western Blot. Results: Fractalkine was detected in salivary glands of both NOD and control mice at all ages. Western blot analysis showed fractalkine cleavage with increasing age, which was more pronounced in NOD mice. This cleavage resulted in a decrease of the 31 kDa form of the protein, and the generation of a ~19 kDa band. Furthermore, NOD animals over 15 weeks of age showed the presence of a unique ~17 kDa fragment. This cleavage was organ specific, as it did not occur in brain or pancreas. Increased gelatinase and alpha-secretase activity were detected in NOD SMG and contribute to the cleavage of the 31 kDa protein. Since aberrant cleavage products may induce autoimmunity, we studied the presence of autoantibodies against fractalkine. Indeed, NOD mice showed significantly more antibodies against fractalkine than control animals. Conclusions: This data indicates that aberrant proteolytic activity in the NOD SMG results in increased fractalkine cleavage and the generation of a unique fractalkine fragment. This specific cleavage may contribute to autoimmunity.

IntroductionLarge osteochondral defects of the weightbearing zones of femoral condyles in young and active patients were treated by autologus transfer of the posterior femoral condyle (MegaOATS). The technique presented is a sound and feasible salvage procedure to address large osteochondral defects in weightbearing zones. Methods: 36 patients between 07/1996 and 12/2000 were included. 33 (10 female, 23 male) patients were evaluated by Lysholm score and X-rays. A random test of 16 individuals underwent MRI analysis. The average age at the date of surgery was 34.3 (15 to 59) years, the mean followup 66.4 (46 to 98) months. The mean defect size was 6.2 cm^2 (2 to 10.5), in 27 patients affecting the medial femoral condyle, in 6 the lateral femoral condyle. Trauma or osteochondrosis dissecans were pathogenetic in 82%. Results: The Lysholm score in all 33 individuals showed highly significant increase from preoperatively median 49.0 points to median 86.0 points (p[less than or equal to]0.001). 27 patients returned to recreational sports. X-ray showed a rounding of the osteotomy edge in 24, interpreted as a partial remodelling of the posterior femoral condyle. Preoperative osteoarthritis in 17 individuals was related to significant lower Lysholm scores (p=0.014), but progression in 17 patients did not significantly influence score results (p=0.143). All 16 MRI examinations showed vital and congruent grafts. Conclusions: Patients significantly improve in Lysholm score, daily life activity levels and come back to recreational sports. 31 out of 33 patients were comfortable with the results and would undergo the procedure again. Thus MegaOATS is recommended as a salvage procedure for young individuals with large osteochondral defects in the weight bearing zone of the femoral condyle.

Anti-tumour necrosis factor (TNF)? therapy is highly effective in rheumatoid arthritis and it is surprising, therefore, that a recent study showed that intraperitoneal administration of recombinant TNF? reduced the severity of adjuvant-induced arthritis and decreased IFN? expression in cultured draining lymph node cells. Furthermore, in untreated arthritic rats, maximal TNF? expression in draining lymph node cells coincided with spontaneous disease remission, suggesting a role for endogenous TNF? in recovery from arthritis. If confirmed in further studies, these findings suggest that, in addition to its well-established pro-inflammatory properties, TNF? may also play a disease-limiting role in this model of rheumatoid arthritis by suppressing effector T cell responses.

Understanding how uric acid crystals provoke inflammation is crucial to improving our management of acute gout. It is well known that urate crystals stimulate monocytes and macrophages to elaborate inflammatory cytokines, but the tissue response of the synovium is less well understood. Microarray analysis of mRNA expression by these lining cells may help to delineate the genes that are modulated. Employing a murine air-pouch model, a number of genes expressed by innate immune cells were found to be rapidly upregulated by monosodium urate crystals. These findings provide new research avenues to investigate the physiopathology of gouty inflammation, and may eventually lead to new therapeutic targets in acute gout.

IntroductionIL-1? is a proinflammatory cytokine driving joint inflammation as well as systemic signs of inflammation, such as fever and acute phase protein production. Methods: ACZ885, a fully human monoclonal antibody that neutralizes the bioactivity of human IL-1?, was generated to study the potent and long-lasting neutralization of IL-1? in mechanistic animal models as well as in a proof-of-concept study in patients with rheumatoid arthritis (RA). Results: The mouse IL-1 receptor cross-reacts with human IL-1?, and it was demonstrated that ACZ885 can completely suppress IL-1?-mediated joint inflammation and cartilage destruction in mice. This observation prompted us to study the safety, tolerability and pharmacodynamic activity of ACZ885 in RA patients in a small proof-of-concept study – the first to be conducted in humans. Patients with active RA despite treatment with stable doses of methotrexate were enrolled in this dose escalation study. The first 32 patients were split into four cohorts of eight patients each (six were randomly assigned to active treatment and two to placebo). ACZ885 doses were 0.3, 1, 3 and 10 mg/kg, administered intravenously on days 1 and 15. To explore efficacy within 6 weeks of treatment, an additional 21 patients were randomly assigned to the 10 mg/kg cohort, resulting in a total of 20 patients dosed with 10 mg/kg and 15 patients treated with placebo. There was clinical improvement (American College of Rheumatology 20% improvement criteria) at week 6 in the 10 mg/kg treatment group; however, this did not reach statistical significance (P = 0.085). A statistically significant reduction in disease activity score was observed after 4 weeks in the 10 mg/kg group. Onset of action was rapid, because most responders exhibited improvement in their symptoms within the first 3 weeks. C-reactive protein levels decreased in patients treated with ACZ885 within 1 week. ACZ885 was well tolerated. Three patients receiving ACZ885 developed infectious episodes that required treatment. No anti-ACZ885 antibodies were detected during the study. Conclusion: ACZ885 administration to methotrexate-refractory patients resulted in clinical improvement in a subset of patients. Additional studies to characterize efficacy in RA and to determine the optimal dose regimen appear warranted.Trial RegistrationClinicalTrials.gov identifier NCT00619905.

IntroductionImmunization with glucose-6-phosphate isomerase (GPI) induces severe arthritis in DBA/1 mice. The present study was designed to identify the cytokines and co-stimulatory molecules involved in the development of GPI-induced arthritis. Methods: Arthritis was induced in DBA/1 mice with 300 ?g human recombinant GPI. CD4+ T cells and antigen-presenting cells from splenocytes of arthritic mice were cultured in the presence of GPI. Tumor necrosis factor (TNF)-?, IFN-?, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-12 levels were assessed using cytometric bead array. Monoclonal antibodies to TNF-?, IFN-?, IL-12, CD40L, inducible co-stimulator (ICOS), and cytotoxic T-lymphocyte antigen 4 immunoglobulin (CTLA-4Ig) were used to block TNF-? and IFN-? production, examine clinical index in mice with GPI-induced arthritis, and determine anti-GPI antibody production. Results: Large amounts of TNF-? and IFN-? and small amounts of IL-2 and IL-6 were produced by splenocytes from mice with GPI-induced arthritis. Anti-TNF-? mAbs and CTLA-4Ig suppressed TNF-? production, whereas anti-IFN-? mAbs, anti-IL-12 mAbs, and CTLA-4 Ig inhibited IFN-? production. A single injection of anti-TNF-? and anti-IL-6 mAbs and two injections of CTLA-4Ig reduced the severity of arthritis in mice, whereas injections of anti-IFN-? and anti-IL-12 mAbs tended to exacerbate arthritis. Therapeutic efficacy tended to correlate with reduction in anti-GPI antibodies. Conclusion: TNF-? and IL-6 play an important role in GPI-induced arthritis, whereas IFN-? appears to function as a regulator of arthritis. Because the therapeutic effects of the tested molecules used in this study are similar to those in patients with rheumatoid arthritis, GPI-induced arthritis appears to be a suitable tool with which to examine the effect of various therapies on rheumatoid arthritis.

IntroductionBone morphogenetic proteins (BMPs) are critical growth factors in the osteogenic differentiation of progenitor cells during development in embryos and fracture repair in adults. Although recombinant BMPs are in use clinically, their clinical efficiency needs to be improved. The biological activities of BMPs are naturally regulated by extracellular binding proteins. The specific hypotheses tested in this study were as follows: the BMP inhibitor chordin is produced endogenously during the osteogenic differentiation of human mesenchymal stem cells (MSCs); and blockade of the activity of the BMP inhibitor increases the rate of osteogenic differentiation of human MSCs in vitro. Methods: Human MSCs were derived from bone marrow from an iliac crest aspirate and from patients undergoing hip hemiarthroplasty. The MSCs were induced down the osteogenic pathway using standard osteogenic differentiation media, and expressions of BMP-2 and chordin were determined by gene expression analysis. During osteogenic differentiation, chordin knockdown was induced using RNA interference. Osteogenic differentiation was assessed by measuring the expression of alkaline phosphatase and calcium deposition. The differences in expression of osteogenic makers between groups were compared by analysis of variance, followed by Gabriel post hoc test. Results: We demonstrate the expression of BMP-2 and chordin in human MSCs during osteogenic differentiation. Knockdown of chordin by RNA interference in vitro resulted in a significant increase in the expression of the osteogenic marker alkaline phosphatase and the deposition of extracellular mineral, in response to osteogenic stimulation. Conclusion: We conclude that endogenously produced chordin constrains the osteogenic differentiation of human MSCs. The targeting of BMP inhibitors, such as chordin, may provide a novel strategy for enhancing bone regeneration.

IntroductionThe murine air pouch is a bursa-like space with important properties of the human synovial membrane. Injecting monosodium urate (MSU) crystals into the pouch elicits an acute inflammatory response that resembles human gout. We intended to identify mRNAs that were highly regulated by MSU crystals in the pouch membrane. Methods: Air pouch membranes were meticulously dissected away from the overlying skin. Gene expression differences between MSU crystal-stimulated and control membranes were determined by oligonucleotide microarray analysis 9 hours after injection of MSU crystals or buffer only. Differential regulation of selected targets was validated by relative quantitative PCR (qPCR) in time course experiments with dissected air pouch membranes and murine peritoneal macrophages. Results: Eleven of the 12 most highly upregulated mRNAs related to innate immunity and inflammation. They included mRNAs encoding histidine decarboxylase (the enzyme that synthesizes histamine), interleukin (IL)-6, the cell surface receptors PUMA-g and TREM-1, and the polypeptides Irg1 and PROK-2. IL-6 mRNA rose 108-fold one hour after crystal injection, coinciding with a surge in mRNAs encoding IL-1beta, TNF-alpha and the immediate early transcription factor Egr-1. The other mRNAs rose up to 200-fold within the subsequent 3-8 hours. MSU crystals induced these mRNAs in a dose-dependent manner in cultured macrophages with similar kinetics but lower x-fold changes. Among the downregulated mRNAs, qPCR confirmed significant decreases in mRNAs encoding TREM-2 (an inhibitor of macrophage activation) and granzyme D (a constituent of NK and cytotoxic T cells) within 50 hours after crystal injection. Conclusions: This analysis disclosed several genes previously not implicated in MSU crystal inflammation. The dramatic rise of the upregulated mRNAs after the early surge in cytokine and Egr-1 mRNAs suggests that they may be part of a "second wave" of factors that amplify or perpetuate inflammation. Transcript profiling of the isolated air pouch membrane promises to be a powerful tool to identify genes acting at different stages of inflammation.

Rheumatoid arthritis (RA) remains a prevalent disease worldwide that causes significant morbidity and mortality despite recent therapeutics. High mobility group box-1 (HMGB1) protein, originally appreciated as an intranuclear DNA binding protein, has been implicated as an integral mediator in the pathogenesis of animal arthritides and RA disease in humans. Our current understanding of HMGB1 has promoted the development of targeting therapies that have improved outcomes in animal models of inflammation. In the previous issue of Arthritis Research & Therapy, Sundberg and colleagues address, for the first time in a prospective cohort study, whether HMGB1 expression is dependent upon tumor necrosis factor activity in patients with RA.

IntroductionPhysiological and pathophysiological cartilage turnover may coexist in articular cartilage. The distinct enzymatic processes leading to irreversible cartilage damage, compared with those needed for continuous self-repair and regeneration, remain to be identified. We investigated the capacity of repair of chondrocytes by analyzing their ability to initiate an anabolic response subsequent to three different levels of catabolic stimulation. Methods: Cartilage degradation was induced by oncostatin M and tumour necrosis factor in articular cartilage explants for 7, 11, or 17 days. The catabolic period was followed by 2 weeks of anabolic stimulation (insulin growth factor-I). Cartilage formation was assessed by collagen type II formation (PIINP). Cartilage degradation was measured by matrix metalloproteinase (MMP) mediated type II collagen degradation (CTX-II), and MMP and aggrecanase mediated aggrecan degradation by detecting the 342FFGVG and 374ARGSV neoepitopes. Proteoglycan turnover, content, and localization were assessed by Alcian blue. Results: Catabolic stimulation resulted in increased levels of cartilage degradation, with maximal levels of 374ARGSV (20-fold induction), CTX-II (150-fold induction), and 342FFGVG (30-fold induction) (P

IntroductionGreater trochanteric pain syndrome (GTPS) is a common condition, the pathogenesis of which is incompletely understood. Although leg-length inequality has been suggested as a potential risk factor for GTPS, this widely held assumption has not been tested. Methods: A cross-sectional analysis of greater trochanteric tenderness to palpation was performed in subjects with complaints of hip pain and no signs of hip osteoarthritis or generalized myofascial tenderness. Subjects were recruited from one clinical center of the Multicenter Osteoarthritis Study, a multicenter population-based study of community-dwelling adults aged 50 to 79 years. Diagnosis of GTPS was based on a standardized physical examination performed by trained examiners, and technicians measured leg length on full-limb anteroposterior radiographs. Results: A total of 1,482 subjects were eligible for analysis of GTPS and leg length. Subjects' mean ± standard deviation age was 62.4 ± 8.2 years, and 59.8% were female. A total of 372 lower limbs from 271 subjects met the definition for having GTPS. Leg-length inequality (difference ? 1 cm) was present in 37 subjects with GTPS and in 163 subjects without GTPS (P = 0.86). Using a variety of definitions of leg-length inequality, including categorical and continuous measures, there was no association of this parameter with the occurrence of GTPS (for example, for ? 1 cm leg-length inequality, odds ratio = 1.17 (95% confidence interval = 0.79 to 1.73)). In adjusted analyses, female sex was significantly associated with the presence of GTPS, with an adjusted odds ratio of 3.04 (95% confidence interval = 2.07 to 4.47). Conclusion: The present study found no evidence to support an association between leg-length inequality and greater trochanteric pain syndrome.

Rheumatoid arthritis is a heterogeneous disease with respect to clinical manifestations, serologic abnormalities, joint damage and functional impairment. Predicting outcome in a reliable way to allow for strategic therapeutic decision-making as well as for prediction of the response to the various therapeutic modalities available today, especially biological agents, would provide means for optimization of care. In the present article, the current information on biological and clinical markers related to disease activity and joint damage as well as for predictive purposes is reviewed. It will be shown that the relationship of many biomarkers with disease characteristics is confounded by factors unrelated to the disease, and that only few biomarkers exist with some predictive value. Moreover, clinical markers appear of equal value as biomarkers for this purpose, although they likewise have limited capacity in these regards. The analysis suggests the search for better markers to predict outcomes and therapeutic responsiveness in rheumatoid arthritis needs to be intensified.

IntroductionChanges in sulfation of cartilage glycosaminoglycans as mediated by sulfatases can regulate growth factor signaling. The aim of this study was to analyze expression patterns of recently identified extracellular sulfatases Sulf-1 and Sulf-2 in articular cartilage and chondrocytes. Methods: Sulf-1 and Sulf-2 expression in human articular cartilage from normal donors and patients with osteoarthritis (OA), and in normal and aged mouse joints were analyzed by real-time PCR, immunohistochemistry and western blotting. Results: In normal articular cartilage, Sulf-1 and Sulf-2 were expressed predominantly in the superficial zone. OA cartilage showed significantly higher Sulf-1 and Sulf-2 mRNA expression as compared to normal human articular cartilage. Sulf protein expression in OA cartilage was prominent in the cell clusters. Western blotting revealed a profound increase in Sulf protein levels in human OA cartilage. In normal mouse joints, Sulf expression was similar to human cartilage and with increasing age, there was a marked upregulation of Sulf. Conclusions: The results show low levels of Sulf expression, restricted to the superficial zone in normal articular cartilage. Sulf mRNA and protein levels are increased in aging and OA cartilage. This increased Sulf expression may change the sulfation patterns of heparan sulfate proteglycans and growth factor activities and thus contribute to abnormal chondrocyte activation and cartilage degradation in OA.