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

Tianhe Zhuifeng Gao reverses inflammatory response and attenuates bone/cartilage destruction in rheumatoid arthritis via PSMC2-RUNX2-COL1A1 axis based on transcriptional regulatory network analysis and experimental validation

BACKGROUND

Tianhe Zhuifeng Gao (TZG) is an authorized Chinese patent drug with satisfying clinical efficacy, especially for RA patients with cold-dampness syndrome. However, its underlying pharmacological mechanisms remain unclear.

METHOD

Anti-arthritic effects of TZG were evaluated using an adjuvant-induced arthritis (AIA) rat model. Transcriptional regulatory network analysis based on synovial tissues obtained from AIA rats, combining with our previous analysis based on whole blood samples from RA patients with cold-dampness syndrome and co-immunoprecipitation were performed to identify involved dominant pathways, which were experimentally verified using AIA-wind-cold-dampness stimulation modified (AIA-M) animal model.

RESULTS

TZG treatment dramatically attenuated joint injury and inflammatory response in AIA rats, and PSMC2-RUNX2-COL1A1 axis, which was closely associated with bone/cartilage damage, was inferred to be one of therapeutic targets of TZG against RA. Experimentally, TZG displayed obvious pharmacological effects for alleviating the joint inflammation and destruction through reinstating the body weight, reducing the arthritis score, the limbs diameters, the levels of RF and CRP, and the inflammatory cytokines, recovering the thymus and spleen indexes, diminishing bone and cartilage destruction, as well elevating the pain thresholds of AIA-M rats. In addition, TZG markedly reversed the abnormal energy metabolism in AIA-M rats through enhancing articular temperature, daily water consumption, and regulating expression levels of energy metabolism parameters and hormones. Moreover, TZG also significantly modulated the abnormal expression levels of PSMC2, RUNX2 and COL1A1 proteins in the ankle tissues of AIA-M rats.

CONCLUSION

TZG may exert the bone protective effects in RA therapy via regulating bone and cartilage damage-associated PSMC2-RUNX2-COL1A1 axis.

Targeted screening of inflammatory mediators in spontaneous degenerative disc disease in dogs reveals an upregulation of the tumor necrosis superfamily

Background

The regulation of inflammatory mediators in the degenerating intervertebral disc (IVD) and corresponding ligamentum flavum (LF) is a topic of emerging interest. The study aimed to investigate the expression of a broad array of inflammatory mediators in the degenerated LF and IVD using a dog model of spontaneous degenerative disc disease (DDD) to determine potential treatment targets.

Methods

LF and IVD tissues were collected from 22 normal dogs (Pfirrmann grades I and II) and 18 dogs affected by DDD (Pfirrmann grades III and IV). A qPCR gene array was used to investigate the expression of 80 inflammatory genes for LF and IVD tissues, whereafter targets of interest were investigated in additional tissue samples using qPCR, western blot (WB), and immunohistochemistry.

Results

Tumor necrosis factor superfamily (TNFSF) signaling was identified as a regulated pathway in DDD, based on the significant regulation (n-fold ± SD) of various TNFSF members in the degenerated IVD, including nerve growth factor (NGF; -8 ± 10), CD40LG (464 ± 442), CD70 (341 ± 336), TNFSF Ligand 10 (9 ± 8), and RANKL/TNFSF Ligand 11 (85 ± 74). In contrast, TNFSF genes were not significantly affected in the degenerated LF compared to the control LF. Protein expression of NGF (WB) was significantly upregulated in both the degenerated LF (4.4 ± 0.5) and IVD (11.3 ± 5.6) compared to the control group. RANKL immunopositivity was significantly upregulated in advanced stages of degeneration (Thompson grades IV and V) in the nucleus pulposus and annulus fibrosus of the IVD, but not in the LF.

Conclusions

DDD involves a significant upregulation of various TNFSF members, with tissue-specific expression profiles in LF and IVD tissues. The differential involvement of TNFSF members within multiple spinal tissues from the same individual provides new insights into the inflammatory processes involved in DDD and may provide a basis to formulate hypotheses for the determination of potential treatment targets.

Differences of RUNX2 gene promoter methylation and transcription level in ankylosing spondylitis

BACKGROUND AND OBJECTIVE

Ankylosing spondylitis is a refractory immune disease that seriously affects the life and work of patients. Epigenetic modifications, especially DNA methylation, have become a research hotspot in complex diseases. We aim to explore the changes in runt-related transcription factor 2 (RUNX2) gene promoter methylation and transcription level in AS.

METHOD

We detected the RUNX2 gene promoter methylation in 83 AS patients and 83 healthy controls (HCs), then inspected the mRNA difference of RUNX2 between 30 AS patients and 30 HCs by the quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

The RUNX2 gene promoter was hypomethylated in AS patients compared to HCs (p < .001). The research involved 4 CpG regions and 74 CpG sites of RUNX2, of which CpG-2, CpG-4 regions, and 18 CpG sites have been differentially methylated. The CpG-4 island methylation was negatively correlated with C-reactive protein (p < .05) in AS patients. In the qRT-PCR validation phase, the mRNA level of RUNX2 in AS patients was significantly higher than HCs (p < .05), and in AS patients who were treated with biologics, the methylation level of CpG-2 island showed a negative correlation to mRNA (p < .05). ROC results indicated that RUNX2 methylation and its transcription level have good potential to distinguish AS patients from HCs.

CONCLUSION

The RUNX2 gene promoter was hypomethylated in AS patients. Meanwhile, the qRT-PCR verified the up-regulated expression on the transcription level, suggesting the abnormal methylation of RUNX2 contributes to the pathogenesis of AS.

Serum BMP-2 and BMP-4 levels and their relationship with disease activity in patients with rheumatoid arthritis and ankylosing spondylitis

Objectives

This study aims to investigate the levels of bone morphogenic proteins (BMPs), one of the pathways affecting bone turnover in these diseases, and to investigate their relationship with disease activity.

Patients and methods

Between September 2013 and July 2015, a total of 100 ankylosing spondylitis (AS) patients (53 males, 48 females; median age: 40 years; range, 18 to 62 years), 58 rheumatoid arthritis (RA) patients (25 males, 33 females; median age: 40.5 years; range, 26 to 59 years), and 102 age- and sex-matched healthy controls (55 males, 47 females; median age: 38 years; range, 18 to 55 years) were included in the study. In all groups, serum BMP-2 and BMP-4 levels were measured using enzyme-linked immunosorbent assay (ELISA). Demographic data (age, sex, duration of disease) and acute phase reactants of the patients at the final visit were recorded. Disease activity was assessed through the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score C-Reactive Protein (ASDAS-CRP) for AS patients and through the Disease Activity Score-28-CRP (DAS-28-CRP) for RA patients.

Results

The median BMP-2 values were found to be significantly higher in the RA group compared to the other groups and in the control group compared to the AS group (p<0.001 for both). There was no significant difference between the groups in terms of median BMP-4 values (p>0.05). No significant relationship was found between serum BMP-2 and BMP-4 levels and disease activity in both AS and RA patients, while there was a weak positive correlation between erythrocyte sedimentation rate and CRP levels with BMP-2 level in RA patients (p=0.014, r=0.320 and p=0.029, r=0.287, respectively).

Conclusion

Our study results suggest that the BMP pathway may have different dual effects in AS and RA patients depending on the underlying pathogenesis, and that local effects are more prominent than serum levels.

Applying precision medicine to unmet clinical needs in psoriatic disease

Psoriatic disease (PsD) is a heterogeneous condition that can affect peripheral and axial joints (arthritis), entheses, skin (psoriasis) and other structures. Over the past decade, considerable advances have been made both in our understanding of the pathogenesis of PsD and in the treatment of its diverse manifestations. However, several major areas of continued unmet need in the care of patients with PsD have been identified. One of these areas is the prediction of poor outcome, notably radiographic outcome in patients with psoriatic arthritis, so that stratified medicine approaches can be taken; another is predicting response to the numerous current and emerging therapies for PsD, so that precision medicine can be applied to rapidly improve clinical outcome and reduce the risk of toxicity. In order to address these needs, novel approaches, including imaging, tissue analysis and the application of proteogenomic technologies, are proposed as methodological solutions that will assist the dissection of the critical immune-metabolic pathways in this complex disease. Learning from advances made in other inflammatory diseases, it is time to address these unmet needs in a multi-centre partnership aimed at improving short-term and long-term outcomes for patients with PsD.

What do we know about bone morphogenetic proteins and osteochondroprogenitors in inflammatory conditions?

Osteochondroprogenitors are crucial for embryonic bone development and postnatal processes such as bone repair in response to fracture injury, and their dysfunction may contribute to insufficient repair of structural damage in inflammatory arthritides. In the fracture healing, the early inflammatory phase is crucial for normal callus development and new bone formation. This process involves a complex interplay of many molecules and cell types, responsible for recruitment, expansion and differentiation of osteochondroprogenitor populations. In inflammatory arthritides, inflammation induces bone resorption and causes insufficient bone formation, which leads to local and systemic bone loss. While bone loss is a predominant feature in rheumatoid arthritis, inflammation also induces pathologic bone formation at enthesial sites in seronegative spondyloarthropathies. Bone morphogenetic proteins (BMP) are involved in cell proliferation, differentiation and apoptosis, and have fundamental roles in maintenance of postnatal bone homeostasis. They are crucial regulators of the osteochondroprogenitor pool and drive their proliferation, differentiation, and lifespan during bone regeneration. In this review, we summarize the effects of inflammation on osteochondroprogenitor populations during fracture repair and in inflammatory arthritides, with special focus on inflammation-mediated modulation of BMP signaling. We also present data in which we describe a population of murine synovial osteochondroprogenitor cells, which are reduced in arthritis, and characterize their expression of genes involved in regulation of bone homeostasis, emphasizing the up-regulation of BMP pathways in early progenitor subset. Based on the presented data, it may be concluded that during an inflammatory response, innate immune cells induce osteochondroprogenitors by providing signals for their recruitment, by producing BMPs and other osteogenic factors for paracrine effects, and by secreting inflammatory cytokines that may positively regulate osteogenic pathways. On the other hand, inflammatory cells may secrete cytokines that interfere with osteogenic pathways, proapoptotic factors that reduce the pool of osteochondroprogenitor cells, as well as BMP and Wnt antagonists. The net effect is strongly context-dependent and influenced by the local milieu of cells, cytokines, and growth factors. Further elucidation of the interplay between inflammatory signals and BMP-mediated bone formation may provide valuable tools for therapeutic targeting.

Psoriatic Arthritis: What is Happening at the Joint?

Psoriatic arthritis (PsA) is a heterogeneous and inflammatory disease with diverse clinical manifestations, including psoriasis, nail psoriasis, peripheral joint disease, axial joint disease, enthesitis, and dactylitis. Typically, this varied clinical presentation complicates the clinician's ability to distinguish PsA from other forms of arthritis. In the synovium of individuals with PsA, upregulation of the genes WNT3A, BMPR2, and TGFBR1 results in bone erosion and new bone formation, a pattern unique to the disease. Additionally, genes associated with angiogenesis and vascularization such as VEGF and TGFB1 facilitate inflammation and joint damage. Gross pathogenesis of PsA is driven by proinflammatory cytokines, and key cytokines affecting joint structures include tumor necrosis factor-α, interleukin (IL)-6, IL-17A, IL-21, IL-22, and IL-23. Early diagnosis is critical for providing treatment that prevents irreversible disease progression and function loss. This narrative review discusses differentiation of PsA from other forms of arthritis. Additionally, we detail the role of cytokines at the joint in mediating PsA pathogenesis.Funding: Novartis Pharmaceuticals Corporation.

Infection of Rat Osteoblasts with Junin Virus Promotes the Expression of Bone Morphogenetic Protein 6, an Osteogenic Differentiation Inducer

BACKGROUND

The arenavirus Junin virus (JUNV), causative agent of the argentine hemorrhagic fever, is able to modulate several signaling pathways involved in cell survival and multiplication.

OBJECTIVES

We aimed to characterize the infection of rat osteoblasts (OBCs) with JUNV and its consequence on the modulation of osteogenic genes expression, thus studying the ability of this virus to induce cell differentiation. In addition, we evaluated the effect of purinergic agonists on viral replication.

METHOD

Quantification of infectivity by plaque forming unit (PFU) assay, synthesis of viral proteins by western blot and immunofluorescence, and expression of osteogenic differentiation markers (ODM) by quantitative real-time polymerase chain reaction were employed.

RESULTS

Infection of OBCs with JUNV (MOI 0.01 PFU/cell) showed a peak of infectivity, reaching 1.5 × 105 PFU/mL at the second day post-infection (p.i.). A marked restriction in multiplication was detected at day 7 p.i. that did not impair the establishment of a persistent stage of infection in OBCs. Analysis of mRNAs corresponding to ODM such as alkaline phosphatase, bone sialo-protein, and bone morphogenetic proteins (BMPs) 4 and 6 revealed that only the levels of BMP-6 were significantly higher in infected cells. Treatment with the purinergic agonists ATPγS, UTP, ADP, or UDP diminished viral titer and reduced the expression of the viral nucleoprotein. Also, treatment with 10 μM ATPγS reduced the stimulation of BMP-6 expression induced by the infection.

CONCLUSIONS

These data demonstrate that JUNV is capable of infecting OBCs and point out BMP-6 as a key factor during this process.

Association study of copy number variation in BMP8A gene with the risk of ankylosing spondylitis in Iranian population

BACKGROUND

Copy number variation (CNV) of DNA segments has been considered as an important component of genetic variation, affecting the quality and quantity of gene expression. Bone morphogenic protein 8A (BMP8A) has been reported to function in bone formation. With respect to the bone and joint complications in ankylosing spondylitis (AS), this investigation aimed to study the role of BMP8A gene CNV in impressing the gene expression as well as the disease risk.

METHODS

A total of 900 individuals, including 450 patients with AS and 450 healthy controls were enrolled. The copy numbers of BMP8A gene were detected by TaqMan real-time polymerase chain reaction (PCR) method. BMP8A messenger RNA (mRNA) transcript level in peripheral blood mononuclear cells (PBMCs) was also measured by SYBR Green real-time gene expression PCR method.

RESULTS

No significant association of BMP8A copy number was detected with the risk of AS. BMP8A mRNA expression level was significantly downregulated in patients compared with controls. mRNA expression level of BMP8A in both AS patients with and without syndesmophyte was significantly lower than the healthy control group. There was no correlation between the mRNA expression level of BMP8A and both demographic and clinical data of the patients.

CONCLUSIONS

Although BMP8A gene expression was downregulated in patients with AS, its copy number could not affect the transcript level of BMP8A gene in PBMCs and was not associated with susceptibility to AS in Iranian population. BMP8a may take into account as an indicator of bone formation process in AS, but it seems that mechanisms other than CNV may regulate this protein.

[Upcoming value of gene expression analysis in rheumatology]

Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown etiology, which involves disturbance in immune system signaling pathway functions, damage of other tissues, pain and joint destruction. Modern treatment attempts to improve pathophysiological and biochemical mechanisms damaged by the disease. However, due to the RA patient heterogeneity personalized approach to treatment is required; the choice of personalized treatment is complicated by the variability of patient's response to treatment. Gene expression analysis might serve a tool for the disease control and therapy personification for inhibition of inflammation and pain as well as for prevention of joint destruction.

Bone morphogenetic protein-2 exhibits therapeutic benefits for osteonecrosis of the femoral head through induction of cartilage and bone cells

Osteonecrosis of the femoral head is an orthopedic disease caused by femoral head damage or insufficient blood supply, which leads to the death of bone cells and bone marrow. Osteonecrosis of the femoral head leads to changes in the structure of the femoral head, femoral head collapse and joint dysfunction. Bone morphogenetic protein-2 (BMP-2) exhibits beneficial effects on bone formation, repair and angiogenesis at the femoral head. In the present study, the therapeutic effects of recombinant human BMP-2 containing an Fc fragment (rBMP-2/Fc) were investigated on a steroid induced mouse model of osteonecrosis of the femoral head. Bone cell viability was used to determine the in vitro effects of rBMP-2/Fc. The therapeutic efficacies of rBMP-2/Fc on mice with osteonecrosis of the femoral head were evaluated using clinical arthritis scores. The expression levels of inflammatory factors in the mice were analyzed by reverse transcription-quantitative polymerase chain reaction. Histological analysis was used to evaluate the effects of rBMP-2/Fc on the femoral head. The results revealed that rBMP-2/Fc treatment significantly increased the IL-6, IL-10, vascular endothelial growth factor and macrophage colony-stimulating factor expression levels in synovial cells compared with the control group (P<0.01). Furthermore, it was observed that rBMP-2/Fc significantly improved the viability and growth of synovial cells (P<0.01) through the nuclear factor (NF)-κB signaling pathway. Treatment with rBMP-2/Fc significantly decreased receptor activator of NF-κB ligand expression levels. Furthermore, in vivo experiments demonstrated that rBMP-2/Fc treatment markedly relieved the arthralgia and damage caused by osteonecrosis of the femoral head. In conclusion, rBMP-2/Fc treatment may be beneficial for articular cartilage repair by the upregulation of angiogenesis factors through the down regulation of the NF-κB signaling pathway in mice with osteonecrosis of the femoral head. This preclinical data suggests that rBMP-2/Fc may be a promising novel agent for treatment of osteonecrosis of the femoral head.

Hepatocyte growth factor improves bone regeneration via the bone morphogenetic protein‑2‑mediated NF‑κB signaling pathway

Bone regeneration is an important process associated with the treatment of osteonecrosis, which is caused by various factors. Hepatocyte growth factor (HGF) is an active biological factor that has multifunctional roles in cell biology, life sciences and clinical medicine. It has previously been suggested that bone morphogenetic protein (BMP)‑2 exerts beneficial roles in bone formation, repair and angiogenesis in the femoral head. The present study aimed to investigate the benefits and molecular mechanisms of HGF in bone regeneration. The viability of osteoblasts and osteoclasts were studied in vitro. In addition, the expression levels of tumor necrosis factor (TNF)‑α, monocyte chemotactic protein (MCP)‑1, interleukin (IL)‑1 and IL‑6 were detected in a mouse fracture model following treatment with HGF. The expression and activity of nuclear factor (NF)‑κB were also analyzed in osteocytes post‑treatment with HGF. Histological analysis was used to determine the therapeutic effects of HGF on mice with fractures. The migration and differentiation of osteoblasts and osteoclasts were investigated in HGF‑incubated cells. Furthermore, angiogenesis and BMP‑2 expression were analyzed in the mouse fracture model post‑treatment with HGF. The results indicated that HGF regulates the cell viability of osteoblasts and osteoclasts, and also balanced the ratio between osteoblasts and osteoclasts. In addition, HGF decreased the serum expression levels of TNF‑α, MCP‑1, IL‑1 and IL‑6 in experimental mice. The results of a mechanistic analysis demonstrated that HGF upregulated p65, IκB kinase‑β and IκBα expression in osteoblasts from experimental mice. In addition, the expression levels of vascular endothelial growth factor, BMP‑2 receptor, receptor activator of NF‑κB ligand and macrophage colony‑stimulating factor were upregulated by HGF, which may effectively promote blood vessel regeneration, and contribute to the formation and revascularization of tissue‑engineered bone. Furthermore, HGF promoted BMP‑2 expression and enhanced angiogenesis at the fracture location. These results suggested that HGF treatment may significantly promote bone regeneration in a mouse fracture model. In conclusion, these results indicated that HGF is involved in bone regeneration, angiogenesis and the balance between osteoblasts and osteoclasts, thus suggesting that HGF may be considered a potential agent for the treatment of fractures via the promotion of bone regeneration through regulation of the BMP‑2‑mediated NF‑κB signaling pathway.

Increased baseline RUNX2, caspase 3 and p21 gene expressions in the peripheral blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis patients are associated with improved clinical response to methotrexate therapy

OBJECTIVE

To investigate the potential of the baseline gene expression in the whole blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis (RA) patients for predicting the response to methotrexate (MTX) treatment.

METHODS

Twenty-six control subjects and 40 RA patients were examined. Clinical, immunological and radiographic parameters were assessed before and after 24 months of follow-up. The gene expressions in the whole blood were measured using real-time reverse transcription polymerase chain reaction. The protein concentrations in peripheral blood mononuclear cells were quantified using enzyme-linked immunosorbent assay. Receiver operating characteristic curve analyses were used to suggest thresholds that were associated with the prediction of the response.

RESULTS

Decreases in the disease activity at the end of the study were accompanied by significant increases in joint space narrowing score (JSN). Positive correlations between the expressions of the Unc-51-like kinase 1 (ULK1) and matrix metalloproteinase 9 (MMP-9) genes with the level of C-reactive protein and MMP-9 expression with Disease Activity Score of 28 joints (DAS28) and swollen joint count were noted at baseline. The baseline tumor necrosis factor (TNF)α gene expression was positively correlated with JSN at the end of the follow-up, whereas p21, caspase 3, and runt-related transcription factor (RUNX)2 were correlated with the ΔDAS28 values.

CONCLUSIONS

Our results suggest that the expressions of MMP-9 and ULK1 might be associated with disease activity. Increased baseline gene expressions of RUNX2, p21 and caspase 3 in the peripheral blood might predict better responses to MTX therapy.

Osteoarthritis in the Knee Joints of Göttingen Minipigs after Resection of the Anterior Cruciate Ligament? Missing Correlation of MRI, Gene and Protein Expression with Histological Scoring

Introduction

The Göttingen Minipig (GM) is used as large animal model in articular cartilage research. The aim of the study was to introduce osteoarthritis (OA) in the GM by resecting the anterior cruciate ligament (ACLR) according to Pond and Nuki, verified by histological and magnetic resonance imaging (MRI) scoring as well as analysis of gene and protein expression.

Materials and Methods

The eight included skeletally mature female GM were assessed after ACLR in the left and a sham operation in the right knee, which served as control. 26 weeks after surgery the knee joints were scanned using a 3-Tesla high-field MR tomography unit with a 3 T CP Large Flex Coil. Standard proton-density weighted fat saturated sequences in coronal and sagittal direction with a slice thickness of 3 mm were used. The MRI scans were assessed by two radiologists according to a modified WORMS-score, the X-rays of the knee joints by two evaluators. Osteochondral plugs with a diameter of 4mm were taken for histological examination from either the main loading zone or the macroscopic most degenerated parts of the tibia plateau or condyle respectively. The histological sections were blinded and scored by three experts according to Little et al. Gene expression analysis was performed from surrounding cartilage. Expression of adamts4, adamts5, acan, col1A1, col2, il-1ß, mmp1, mmp3, mmp13, vegf was determined by qRT-PCR. Immunohistochemical staining (IH) of Col I and II was performed. IH was scored using a 4 point grading (0—no staining; 3-intense staining).

Results and Discussion

Similar signs of OA were evident both in ACLR and sham operated knee joints with the histological scoring result of the ACLR joints with 6.48 ± 5.67 points and the sham joints with 6.86 ± 5.84 points (p = 0.7953) The MRI scoring yielded 0.34 ± 0.89 points for the ACLR and 0.03 ± 0.17 for the sham knee joints. There was no correlation between the histological and MRI scores (r = 0.10021). The gene expression profiles as well as the immunohistochemical findings showed no significant differences between ACLR and sham knee joints. In conclusion, both knee joints showed histological signs of OA after 26 weeks irrespective of whether the ACL was resected or not. As MRI results did not match the histological findings, MRI was obviously unsuitable to diagnose the OA in GM. The analysis of the expression patterns of the 10 genes could not shed light on the question, whether sham operation also induced cartilage erosion or if the degeneration was spontaneous. The modified Pond-Nuki model may be used with reservation in the adult minipig to induce an isolated osteoarthritis.

Expression of osteoprotegerin and its ligands, RANKL and TRAIL, in rheumatoid arthritis

Osteoprotegerin (OPG), receptor activator of nuclear factor-ΚB ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) have been involved in rheumatoid arthritis (RA) pathophysiology. In this study, we assessed messenger RNA (mRNA) expression of these molecules by qPCR in peripheral blood from 26 patients with RA (12 of them with ischemic heart disease –IHD) and 10 healthy controls. Correlation coefficients between OPG, RANKL and TRAIL expression levels in RA patients and their clinical and demographic characteristics were also evaluated. Whereas OPG and OPG/TRAIL ratio expression were significantly increased in RA patients compared to controls (fold change = 1.79, p = 0.013 and 2.07, p = 0.030, respectively), RANKL/OPG ratio was significantly decreased (fold change = 0.50, p = 0.020). No significant differences were found between patients and controls in RANKL and TRAIL expression. Interestingly, TRAIL expression was significantly higher in RA patients with IHD compared to those without IHD (fold change = 1.46, p = 0.033). Moreover, biologic disease-modifying antirheumatic drugs (DMARDs) significantly decreased RANKL expression in RA patients (p = 0.016). Our study supports an important role of OPG and TRAIL in RA. Furthermore, it highlights an effect of biologic DMARDs in the modulation of RANKL.

Serum Heme Oxygenase-1 and BMP-7 Are Potential Biomarkers for Bone Metabolism in Patients with Rheumatoid Arthritis and Ankylosing Spondylitis

Backgrounds. Heme oxygenase-1 (HO-1) has been reported to play a regulatory role in osteoclastogenesis. Bone morphogenetic protein (BMP) pathways induce osteoblastic differentiation and bone remodeling. Aims. To identify serum levels of HO-1, BMP-7, and Runt related-transcription factor 2 (Runx2) in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS) and to investigate the relationships between HO-1, BMP-7, Runx2, and other common biomarkers for bone metabolism. Results. Serum levels of HO-1 and BMP-7 were revealed to be significantly higher in patients with RA or AS than in healthy controls (p < 0.01). In RA group, HO-1 was positively correlated with BMP-7, Runx2, and tartrate-resistant acid phosphatase-5b (TRAP-5b) (p < 0.05, resp.), BMP-7 was positively correlated with Runx2 and TRAP-5b (p < 0.05, resp.), and Runx2 was negatively correlated with N-terminal midfragment of osteocalcin (NMID) (p < 0.05). In AS group, we observed identical correlation between HO-1 and BMP-7, but opposite correlations between BMP-7 and TRAP-5b and between Runx2 and NMID, when comparing with the RA cohort. Conclusion. Our findings suggest that HO-1 and BMP-7 are potential biomarkers for bone metabolism in patients with RA and AS. The different correlations between the bone markers point to distinct differences in bone remodeling pathways in the two types of arthritis.

Abnormal expression of key genes and proteins in the canonical Wnt/β-catenin pathway of articular cartilage in a rat model of exercise-induced osteoarthritis

To investigate the molecular pathogenesis of the canonical Wnt/β-catenin pathway in exercise-induced osteoarthritis (OA), 30 male healthy Sprague Dawley rats were divided into three groups (control, normal exercise‑induced OA and injured exercise‑induced OA groups) in order to establish the exercise‑induced OA rat model. The mRNA and protein expression levels of Runx‑2, BMP‑2, Ctnnb1, Sox‑9, collagen Ⅱ, Mmp‑13, Wnt‑3a and β‑catenin in chondrocytes were detected by reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemical staining. The mRNA levels of Runx‑2, BMP‑2 and Ctnnb1 were upregulated in the normal exercise‑induced OA and injured exercise‑induced OA groups; while Runx‑2 and BMP‑2 were upregulated in the injured exercise‑induced OA group when compared with the normal exercise‑induced OA group. The protein levels of Mmp‑13, Wnt‑3a and β‑catenin were increased and collagen Ⅱ was reduced in the normal exercise‑induced OA and injured exercise‑induced OA groups. Ctnnb1, Wnt‑3a and β‑catenin, which are key genes and proteins in the canonical Wnt/β‑catenin pathway, were abnormally expressed in chondrocytes of the exercise‑induced OA rat model. Ctnnb1, β‑catenin and Wnt‑3a were suggested to participate in the pathogenesis of exercise‑induced OA by abnormally activating the Wnt/β‑catenin pathway during physical exercise due to excessive pressure. The results of the present study may provide an improved understanding of the pathogenesis of exercise-induced OA.

Bone morphogenetic proteins in inflammation, glucose homeostasis and adipose tissue energy metabolism

Bore morphogenetic proteins (BMPs) are members of the transforming growth factor (TGF)-β superfamily, a group of secreted proteins that regulate embryonic development. This review summarizes the effects of BMPs on physiological processes not exclusively linked to the musculoskeletal system. Specifically, we focus on the involvement of BMPs in inflammatory disorders, e.g. fibrosis, inflammatory bowel disease, anchylosing spondylitis, rheumatoid arthritis. Moreover, we discuss the role of BMPs in the context of vascular disorders, and explore the role of these signalling proteins in iron homeostasis (anaemia, hemochromatosis) and oxidative damage. The second and third parts of this review focus on BMPs in the development of metabolic pathologies such as type-2 diabetes mellitus and obesity. The pancreatic beta cells are the sole source of the hormone insulin and BMPs have recently been implicated in pancreas development as well as control of adult glucose homeostasis. Lastly, we review the recently recognized role of BMPs in brown adipose tissue formation and their consequences for energy expenditure and adiposity. In summary, BMPs play a pivotal role in metabolism beyond their role in skeletal homeostasis. However, increased understanding of these pleiotropic functions also highlights the necessity of tissue-specific strategies when harnessing BMP action as a therapeutic target.

Serum soluble bone turnover biomarkers in psoriatic arthritis and psoriatic spondyloarthropathy

Because psoriatic arthritis (PsA) is an inflammatory disease of joints, serum soluble biomarkers specific for chronic joint and bone inflammation may predict future disease severity and response to therapy, thereby informing stratified medicine approaches. The objectives of our systematic review were to determine whether serum soluble bone and cartilage turnover biomarkers are (1) associated with PsA or psoriatic spondyloarthropathy; and (2) associated with disease activity, disease severity, or clinical phenotype. Ten studies met eligibility criteria. Matrix metalloproteinase (MMP)-3, Dickkopf (DKK)-1, macrophage colony-stimulating factor (M-CSF), crosslinked telopeptide of collagen-1, and tumor necrosis factor-related apoptosis-inducing ligand were associated with PsA, with equivocal results for osteoprotegerin (OPG) and bone alkaline phosphatase (ALP). MMP-3, DKK-1, M-CSF, CPII:C2C (ratio of cartilage degradation vs byproduct formation), and possibly OPG were associated with PsA independently of psoriasis. C1-2C (a neoepitope released when type 2 cartilage is degraded by collagenases) was associated with both tender and swollen joint counts, and bone morphogenetic protein-4 with patient global assessment of disease, pain score, and the Bath Ankylosing Spondylitis Disease Activity Index. Bone ALP was associated with disease activity. M-CSF and receptor activator of nuclear factor-κB ligand were associated with several plain radiographic features. No studies have investigated biomarker associations specifically with axial PsA.

Temporal and spatial expression patterns of bone morphogenetic protein 3 in developing zebrafish

Bone morphogenetic proteins (BMPs) are important elements in bone biology. We herein report the expression profiles of zebrafish bmp3 (zbmp3) as demonstrated by real-time PCR and in situ hybridization. The expression of zbmp3 was highly detectable by real-time PCR from 1 day post-fertilization (1 dpf) to 2 weeks post-fertilization (2 wpf) and peaked at 1 wpf. For in situ hybridization experiments, zbmp3 was expressed in the otic vesicle at 1 dpf, 2 dpf, 3 dpf, and 5 dpf. It was also expressed in the pharyngeal arches, including the opercle, branchiostegal ray, and pectoral fins, at 2 dpf. Our results suggest that zbmp3 may play an important role in the skeletal biology of developing zebrafish.

Blood cells transcriptomics as source of potential biomarkers of articular health improvement: effects of oral intake of a rooster combs extract rich in hyaluronic acid

The aim of the study was to explore peripheral blood gene expression as a source of biomarkers of joint health improvement related to glycosaminoglycan (GAG) intake in humans. Healthy individuals with joint discomfort were enrolled in a randomized, double-blind, placebo-controlled intervention study in humans. Subjects ate control yoghurt or yoghurt supplemented with a recently authorized novel food in Europe containing hyaluronic acid (65 %) from rooster comb (Mobilee™ as commercial name) for 90 days. Effects on functional quality-of-life parameters related to joint health were assessed. Whole-genome microarray analysis of peripheral blood samples from a subset of 20 subjects (10 placebo and 10 supplemented) collected pre- and post-intervention was performed. Mobilee™ supplementation reduced articular pain intensity and synovial effusion and improved knee muscular strength indicators as compared to placebo. About 157 coding genes were differentially expressed in blood cells between supplemented and placebo groups post-intervention, but not pre-intervention (p < 0.05; fold change ≥1.2). Among them, a reduced gene expression of glucuronidase-beta (GUSB), matrix metallopeptidase 23B (MMP23B), xylosyltransferase II (XYLT2), and heparan sulfate 6-O-sulfotransferase 1 (HS6ST1) was found in the supplemented group. Correlation analysis indicated a direct relationship between blood cell gene expression of MMP23B, involved in the breakdown of the extracellular matrix, and pain intensity, and an inverse relationship between blood cell gene expression of HS6ST1, responsible for 6-O-sulfation of heparan sulfate, and indicators of knee muscular strength. Expression levels of specific genes in blood cells, in particular genes related to GAG metabolism and extracellular matrix dynamics, are potential biomarkers of beneficial effects on articular health.

Gene expression analysis in RA: towards personalized medicine

Gene expression has recently been at the forefront of advance in personalized medicine, notably in the field of cancer and transplantation, providing a rational for a similar approach in rheumatoid arthritis (RA). RA is a prototypic inflammatory autoimmune disease with a poorly understood etiopathogenesis. Inflammation is the main feature of RA; however, many biological processes are involved at different stages of the disease. Gene expression signatures offer management tools to meet the current needs for personalization of RA patients' care. This review analyses currently available information with respect to RA diagnostic, prognostic and prediction of response to therapy with a view to highlight the abundance of data, whose comparison is often inconclusive due to the mixed use of material source, experimental methodologies and analysis tools, reinforcing the need for harmonization if gene expression signatures are to become a useful clinical tool in personalized medicine for RA patients.

Identification of rheumatoid arthritis and osteoarthritis patients by transcriptome-based rule set generation

INTRODUCTION

Discrimination of rheumatoid arthritis (RA) patients from patients with other inflammatory or degenerative joint diseases or healthy individuals purely on the basis of genes differentially expressed in high-throughput data has proven very difficult. Thus, the present study sought to achieve such discrimination by employing a novel unbiased approach using rule-based classifiers.

METHODS

Three multi-center genome-wide transcriptomic data sets (Affymetrix HG-U133 A/B) from a total of 79 individuals, including 20 healthy controls (control group - CG), as well as 26 osteoarthritis (OA) and 33 RA patients, were used to infer rule-based classifiers to discriminate the disease groups. The rules were ranked with respect to Kiendl's statistical relevance index, and the resulting rule set was optimized by pruning. The rule sets were inferred separately from data of one of three centers and applied to the two remaining centers for validation. All rules from the optimized rule sets of all centers were used to analyze their biological relevance applying the software Pathway Studio.

RESULTS

The optimized rule sets for the three centers contained a total of 29, 20, and 8 rules (including 10, 8, and 4 rules for 'RA'), respectively. The mean sensitivity for the prediction of RA based on six center-to-center tests was 96% (range 90% to 100%), that for OA 86% (range 40% to 100%). The mean specificity for RA prediction was 94% (range 80% to 100%), that for OA 96% (range 83.3% to 100%). The average overall accuracy of the three different rule-based classifiers was 91% (range 80% to 100%). Unbiased analyses by Pathway Studio of the gene sets obtained by discrimination of RA from OA and CG with rule-based classifiers resulted in the identification of the pathogenetically and/or therapeutically relevant interferon-gamma and GM-CSF pathways.

CONCLUSION

First-time application of rule-based classifiers for the discrimination of RA resulted in high performance, with means for all assessment parameters close to or higher than 90%. In addition, this unbiased, new approach resulted in the identification not only of pathways known to be critical to RA, but also of novel molecules such as serine/threonine kinase 10.

Rheumatoid factor positivity is associated with increased joint destruction and upregulation of matrix metalloproteinase 9 and cathepsin k gene expression in the peripheral blood in rheumatoid arthritic patients treated with methotrexate

We evaluated changes in gene expression of mTOR, p21, caspase-3, ULK1, TNFα, matrix metalloproteinase (MMP)-9, and cathepsin K in the whole blood of rheumatoid arthritic (RA) patients treated with methotrexate (MTX) in relation to their rheumatoid factor status, clinical, immunological, and radiological parameters, and therapeutic response after a 24-month follow-up. The study group consisted of 35 control subjects and 33 RA patients without previous history of MTX treatment. Gene expression was measured using real-time RT-PCR. Decreased disease activity in patients at the end of the study was associated with significant downregulation of TNFα expression. Downregulation of mTOR was observed in seronegative patients, while no significant changes in the expression of p21, ULK1, or caspase-3 were noted in any RA patients at the end of the study. The increase in erosion numbers observed in the seropositive patients at the end of the follow-up was accompanied by upregulation of MMP-9 and cathepsin K, while seronegative patients demonstrated an absence of significant changes in MMP-9 and cathepsin K expression and no increase in the erosion score. Our results suggest that increased expression of MMP-9 and cathepsin K genes in the peripheral blood might indicate higher bone tissue destruction activity in RA patients treated with methotrexate. The clinical study registration number is 0120.0810610.

Association of systemic and intra-articular osteoclastogenic potential, pro-inflammatory mediators and disease activity with the form of inflammatory arthritis

PURPOSE

We aimed to assess osteoclastogenic potential of peripheral blood mononuclear cells (PBMC) and synovial fluid-derived mononuclear cells (SFMC) in different forms of arthritis and to correlate it with inflammatory mediators within intra-articular and circulatory compartments.

METHODS

Paired PBMC and SFMC samples of patients with rheumatoid arthritis (RA; n = 10) and psoriatic arthritis (PsA; n = 10), and PBMC of healthy controls were cultured to assess osteoclastogenic potential by the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts (OCs) and expression of OC-related genes (receptor activator of nuclear factor-κΒ (RANK), cFMS, and TRAP). Osteoclastogenesis was correlated with the arthritis-related inflammatory indicators in serum and synovial fluid (SF).

RESULTS

Number of OCs differentiated from PBMC was significantly higher in RA and PsA compared with control, with RA having more OCs compared with PsA. There was no difference in SFMC OC number between arthritic patients, but RANK expression in OCs differentiated from SFMC was higher in PsA compared with RA. SF of PsA patients more potently induced OC differentiation from control CD3(-)CD19(-)CD56(-)CD11b(+)CD115(+) PBMC compared with RA, paralleled with higher RANK-ligand expression in PsA SFMC. Positive correlations of OC number with erythrocyte sedimentation rate, serum level of CCL2, and PBMC gene expression of interleukin-18 and Fas-ligand were observed.

CONCLUSION

Osteoclastogenic potential is systemically enhanced in patients with RA, paralleled by disordered systemic and local expression of proinflammatory mediators, whereas PsA involves specific deregulation in RANKL/RANK axis. Our study reveals arthritis-specific mediators associated with the form of arthritis, indicating clinical relevance for diagnosis and treatment.

Advances in osteoarthritis genetics

Osteoarthritis (OA), the most common form of arthritis, is a highly debilitating disease of the joints and can lead to severe pain and disability. There is no cure for OA. Current treatments often fail to alleviate its symptoms leading to an increased demand for joint replacement surgery. Previous epidemiological and genetic research has established that OA is a multifactorial disease with both environmental and genetic components. Over the past 6 years, a candidate gene study and several genome-wide association scans (GWAS) in populations of Asian and European descent have collectively established 15 loci associated with knee or hip OA that have been replicated with genome-wide significance, shedding some light on the aetiogenesis of the disease. All OA associated variants to date are common in frequency and appear to confer moderate to small effect sizes. Some of the associated variants are found within or near genes with clear roles in OA pathogenesis, whereas others point to unsuspected, less characterised pathways. These studies have also provided further evidence in support of the existence of ethnic, sex, and joint specific effects in OA and have highlighted the importance of expanded and more homogeneous phenotype definitions in genetic studies of OA.

Differences in Mammalian target of rapamycin gene expression in the peripheral blood and articular cartilages of osteoarthritic patients and disease activity

The gene expression of mTOR, autophagy-related ULK1, caspase 3, CDK-inhibitor p21, and TNF α was measured in the peripheral blood of osteoarthritic (OA) patients at different stages of the disease aiming to establish a gene expression profile that might indicate the activity of the disease and joint destruction. Whole blood of 65 OA outpatients, 27 end-stage OA patients, 27 healthy volunteers, and knee articular cartilages of 28 end-stage OA patients and 26 healthy subjects were examined. OA outpatients were subjected to clinical testing, ultrasonography, and radiographic and WOMAC scoring. Protein levels of p70-S6K, p21, and caspase 3 were quantified by ELISA. Gene expression was measured using real-time RT-PCR. Upregulation of mTOR gene expression was observed in PBMCs of 42 OA outpatients ("High mTOR expression subset") and in PBMCs and articular cartilages of all end-stage OA patients. A positive correlation between mTOR gene expression in PBMCs and cartilage was observed in the end-stage OA patients. 23 OA outpatients in the "Low mTOR expression subset" exhibited significantly lower mTOR gene expression in PBMCs compared to healthy controls. These "Low mTOR" subset subjects experienced significantly more pain upon walking, and standing and increased total joint stiffness versus "High mTOR" subset, while the latter more often exhibited synovitis. The protein concentrations of p70-S6K, p21, and caspase 3 in PBMCs were significantly lower in the "Low" subset versus "High" subset and end-stage subjects. Increases in the expression of mTOR in PBMCs of OA patients are related to disease activity, being associated with synovitis more than with pain.

BAFF and TACI gene expression are increased in patients with untreated very early rheumatoid arthritis

OBJECTIVE

B cells play important roles in rheumatoid arthritis (RA). Given the beneficial effect of B cell depletion therapy in RA as well as the observed alterations in B cell subpopulations in this disease, we evaluated whether changes in the expression of genes related to B cell survival and activation were already present in patients with untreated very early RA (VERA; < 6 weeks of disease duration).

METHODS

The expression of a group of B cell-related activation and survival genes was quantified in peripheral blood mononuclear cells from patients with VERA by real-time PCR and compared with untreated early RA (< 1 year), established treated RA, and other untreated early arthritis conditions. Serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) was quantified by ELISA.

RESULTS

BAFF gene expression and serum levels were highest in patients with VERA. The expression of BAFF receptor (BAFF-R) increased with disease progression, while transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) was elevated since the first weeks of RA onset. Paired box 5 gene expression was also increased at all RA stages. Chemokine (C-X-C motif) receptor 5 was elevated only in established RA. No differences were observed in B cell maturation antigen, activation-induced cytidine deaminase, B lymphocyte-induced maturation protein, and B cell lymphoma 2 expression.

CONCLUSION

Disturbances in the expression of B cell-related activation and survival genes, particularly BAFF and TACI, occur from the onset of RA and precede changes in BAFF-R. These alterations can lead to the development of autoreactive B cells from the first weeks of RA onset.

Identification of new susceptibility loci for osteoarthritis (arcOGEN): a genome-wide association study

BACKGROUND

Osteoarthritis is the most common form of arthritis worldwide and is a major cause of pain and disability in elderly people. The health economic burden of osteoarthritis is increasing commensurate with obesity prevalence and longevity. Osteoarthritis has a strong genetic component but the success of previous genetic studies has been restricted due to insufficient sample sizes and phenotype heterogeneity.

METHODS

We undertook a large genome-wide association study (GWAS) in 7410 unrelated and retrospectively and prospectively selected patients with severe osteoarthritis in the arcOGEN study, 80% of whom had undergone total joint replacement, and 11,009 unrelated controls from the UK. We replicated the most promising signals in an independent set of up to 7473 cases and 42,938 controls, from studies in Iceland, Estonia, the Netherlands, and the UK. All patients and controls were of European descent.

FINDINGS

We identified five genome-wide significant loci (binomial test p≤5·0×10(-8)) for association with osteoarthritis and three loci just below this threshold. The strongest association was on chromosome 3 with rs6976 (odds ratio 1·12 [95% CI 1·08-1·16]; p=7·24×10(-11)), which is in perfect linkage disequilibrium with rs11177. This SNP encodes a missense polymorphism within the nucleostemin-encoding gene GNL3. Levels of nucleostemin were raised in chondrocytes from patients with osteoarthritis in functional studies. Other significant loci were on chromosome 9 close to ASTN2, chromosome 6 between FILIP1 and SENP6, chromosome 12 close to KLHDC5 and PTHLH, and in another region of chromosome 12 close to CHST11. One of the signals close to genome-wide significance was within the FTO gene, which is involved in regulation of bodyweight-a strong risk factor for osteoarthritis. All risk variants were common in frequency and exerted small effects.

INTERPRETATION

Our findings provide insight into the genetics of arthritis and identify new pathways that might be amenable to future therapeutic intervention.

FUNDING

arcOGEN was funded by a special purpose grant from Arthritis Research UK.

Markers of treatment response to methotrexate in rheumatoid arthritis: where do we stand?

Methotrexate (MTX) is the most commonly used disease-modifying antirheumatic drug (DMARD) for the treatment of rheumatoid arthritis (RA). However, despite its efficacy and affordability, additional DMARDs or biologic agents are often required in order to achieve the recommended goals of low disease activity or remission. Although well tolerated by most, some patients develop important side effects such as cytopenias, gastrointestinal adverse events (stomatitis, nausea), or abnormal liver function tests, which may limit its use and may result in additional health care costs. Given the clinical implications of widespread use of MTX in RA, various studies have evaluated the role of potential biomarkers in predicting treatment effectiveness of MTX. These biomarkers include RBC MTX polyglutamate (PG) levels; genetic variation in genes from relevant biological and metabolic pathways; gene expression profiles; serum proteins. This paper provides an update on the current data regarding biomarkers of treatment response to MTX.

The "bone morphogenic proteins" pathways in bone and joint diseases: translational perspectives from physiopathology to therapeutic targets

A large body of evidence supports an important role of bone morphogenic proteins (BMPs) pathways in skeletal development in the embryo. BMPs are also involved in skeletal homeostasis and diseases in the adult. They were first identified as major bone anabolic agents and recent advances indicate that they also regulate osteoclastogenesis and joint components via multiple cross-talks with other signaling pathways. This review attempts to integrate these data in the pathogenesis of bone and joints diseases, such as osteoporosis, fracture healing, osteoarthritis, inflammatory arthritis, or bone metastasis. The use of recombinant BMPs in bone tissue engineering and in the treatment of skeletal diseases, or future therapeutic strategies targeting BMPs signal and its regulators, will be discussed based on these considerations.

Soluble and tissue biomarkers in ankylosing spondylitis

The study of biomarkers has become a very important field of research in spondyloarthropathy. Biomarkers are useful for different aspects of the disease such as diagnosis, assessment of disease activity and outcome, including damage. The most commonly used biomarkers in spondyloarthropathies are HLA-B27 for diagnosis and erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) for disease activity. HLA-B27 is very sensitive but has a low specificity. ESR and CRP have both low sensitivity and specificity. The introduction of new and very expensive therapies is another reason for analysis of biomarkers. Clinicians need tools to predict more accurately disease activity, disease progression and response to therapy. This article focusses on the several known and new biomarkers of promise, including markers for cartilage and bone damage, and discusses some of the problems encountered during the search and development of new biomarkers. Biomarkers, soluble and tissue-related, reflecting structural damage and disease activity, constitute a high priority for the drug discovery process and the understanding of the pathogenesis of a particular disease. The identification of relevant tools to evaluate the natural course, disease activity, treatment response and outcome of ankylosing spondylitis is of increasing relevance since the raised awareness and development of new therapeutic options. Until now these different aspects are monitored by artificial patient-centred or physician-centred constructs. Very often, their approach is indirect and is not free from disease-unrelated influences. The Outcome Measures in Rheumatology Soluble Biomarker Working Group has taken several major steps towards the development and implementation of such assessment methods. The major drawback is that these tools do not directly reflect biological and pathological processes. Serological biomarkers objectively measure different aspects of the biological and pathological process and may contribute to a major advance in the assessments of patients. The ultimate goal is the use of biomarkers in a personalised approach for disease management in clinical practice.

Emerging drugs for psoriatic arthritis

IMPORTANCE OF THE FIELD

The socioeconomic burden of psoriatic arthritis (PsA) is considerable and not different from that of rheumatoid arthritis. Current treatment options do not always allow reaching the therapeutic objectives consisting of the remission of symptoms and prevention of the appearance of damage in the early stage of PsA or the blocking of PsA progression in the established cases.

AREAS COVERED IN THIS REVIEW

After reviewing the current treatment choices, we examine the new drugs in clinical Phase II and III trials for PsA up to January 2010. Information was mainly obtained from the network of international clinical trial registries.

WHAT THE READER WILL GAIN

The current management of PsA includes NSAIDs, corticosteroids, disease-modifying antirheumatic drugs (DMARDs) and anti-TNF-alpha blocking agents. These last drugs are more effective than traditional DMARDs on symptoms/signs of inflammation, quality of life and function and can inhibit the progression of the structural joint damage. Recent advancement in the knowledge of the immunopathogenesis of PsA has permitted the development of novel drugs including new TNF-alpha blockers, IL-1, -6, -12, -23 and -17 inhibitors, co-stimulator modulation inhibitors, B-cell depleting agents, small molecules and receptor activator of NF-kappaB/receptor activator of NF-kappaB ligand inhibitors.

TAKE HOME MESSAGE

The currently available anti-TNF-alpha blocking agents have revolutionized the management of PsA. However, there is a need for more effective and safer drugs.

Targeting Fas in osteoresorptive disorders

IMPORTANCE OF THE FIELD

Fas receptor is a mediator of the external apoptotic pathway in many cells and tissues. It is proposed that Fas receptor mediates osteoresorptive effects of estrogen deficiency and local/systemic inflammation.

AREAS COVERED IN THIS REVIEW

This review covers the past two decades of research on the expression and function of the Fas-Fas ligand system on bone cells, involvement in the pathogenesis of osteoresorption and potential therapeutic modulation.

WHAT THE READER WILL GAIN

We review the structure, biological function and intracellular signaling pathways of the Fas-Fas ligand system emphasizing the role of the non-apoptotic signaling pathways in bone cells, particularly osteoblast differentiation. We also present data on the in vitro expression and function of the Fas-Fas ligand system on osteoblast/osteoclast lineage cells, animal and human studies confirming its involvement in osteoresorptive disorders and potential therapeutic approaches to modulate its function.

TAKE HOME MESSAGE

Tissue specific therapeutic approaches need to be established to modify the Fas-Fas ligand system in osteoresorptive disorders as systemic targeting has many side effects. The most promising approach would be to target Fas signaling molecules coupled with osteoblast/osteoclast differentiation pathways, but a precise definition of these targets is still needed.