Can we stop progression of ankylosing spondylitis?

Excessive accumulation of thioredoxin promotes osteogenic differentiation of mesenchymal stem cells of ligament in ankylosing spondylitis by upregulating autophagy levels

BACKGROUND

Ankylosing spondylitis (AS) is an autoimmune disease characterized by dysfunction of the immune system, which leads to chronic inflammation and progressive ossification of spinal ligaments. The precise pathogenesis of this condition remains unclear, thereby impeding the development of effective treatments.

METHODS

We analyzed the GSE25101 dataset and identified the aberrant expression and potential pathogenic role of TXN. This was achieved through a combination of histopathological testing, quantitative PCR (qPCR), Western blotting (WB), and ELISA to elucidate its aberrant expression and distribution. The pathogenic role of TXN was further clarified by employing lentiviral infection, plasmid transfection, electron microscopy, ALP and ARS staining, WB, and qPCR. Finally, the osteogenic role of TXN in the ligaments of AS mice was further elucidated through in vivo plasmid transfection.

RESULTS

Through an analysis of the public database GSE25101, we identified abnormal transcription of thioredoxin (TXN) in peripheral blood mononuclear cells. Subsequent experiments utilizing ELISA, qPCR, immunohistochemistry, and immunofluorescence revealed a potential link between TXN expression and pathological ossification. KEGG and GO analyses, along with the application of lentivirus and plasmid treatments on mesenchymal stem cells (MSCs), indicated that TXN promotes the osteogenic differentiation of MSCs by activating their autophagy levels. Animal experiments further corroborated the role of TXN in facilitating pathological ossification of ligaments in mice.

CONCLUSIONS

Abnormal TXN expression in the immune system is closely associated with the development of pathological ossification in ankylosing spondylitis. Future research should aim to elucidate the underlying mechanisms, with the inhibition of TXN production emerging as a promising strategy for preventing spinal ligament ossification in this condition.

Fabrication of polydopamine-modified cellulose hydrogel for controlled release of α-mangostin

Hydrogels are notable for their outstanding absorbent qualities, satisfactory compatibility with biological systems, ability to degrade, and inherent safety, all of which contribute to their high demand in the field of biomedicine. This study focuses on the fabrication of hydrogels using environmentally friendly cellulosic material. Cellulose hydrogel beads were prepared by physical cross-linking in a NaOH/urea medium. Furthermore, nano polydopamine was integrated into the hydrogel matrix as functional polymers and α-mangostin was employed as an active pharmaceutical ingredient. The physicochemical properties were comprehensively analyzed using Fourier-transform infrared spectrometer, 13C cross-polarization/magic angle spinning nuclear magnetic resonance, thermogravimetric analysis, and scanning electron microscope. The drug delivery properties, including water content, swelling ratio, and drug release profiles, were evaluated. In vitro cytotoxicity against MC3T3-E1 cells was assessed using sulforhodamine B staining. All test hydrogels exhibited inhibitory activity against the growth of MC3T3-E1 cells. These results indicated the potential use of these hydrogels as a drug delivery carrier for α-mangostin in the treatment of ankylosing spondylitis.

CD_99 G1 neutrophils modulate osteogenic differentiation of mesenchymal stem cells in the pathological process of ankylosing spondylitis

OBJECTIVES

This study aimed to identify the types and heterogeneity of cells within the spinal enthesis and investigate the underlying mechanisms of osteogenesis.

METHODS

Single-cell RNA sequencing was used to identify cell populations and their gene signatures in the spinal enthesis of five patients with ankylosing spondylitis (AS) and three healthy individuals. The transcriptomes of 40 065 single cells were profiled and divided into 7 clusters: neutrophils, monocytic cells, granulomonocytic progenitor_erythroblasts, T cells, B cells, plasma cells and stromal cells. Real-time quantitative PCR, immunofluorescence, flow cytometry, osteogenesis induction, alizarin red staining, immunohistochemistry, short hairpin RNA and H&E staining were applied to validate the bioinformatics analysis.

RESULTS

Pseudo-time analysis showed two differentiation directions of stromal cells from the mesenchymal stem cell subpopulation MSC-C2 to two Cxcl12-abundant-reticular (CAR) cell subsets, Osteo-CAR and Adipo-CAR, within which three transcription factors, C-JUN, C-FOS and CAVIN1, were highly expressed in AS and regulated the osteogenesis of mesenchymal stem cells. A novel subcluster of early-stage neutrophils, CD99_G1, was elevated in AS. The proinflammatory characteristics of monocyte dendritic cell progenitor-recombinant adiponectin receptor 2 monocytic cells were explored. Interactions between Adipo-CAR cells, CD99_G1 neutrophils and other cell types were mapped by identifying ligand-receptor pairs, revealing the recruitment characteristics of CD99_G1 neutrophils by Adipo-CAR cells and the pathogenesis of osteogenesis induced in AS.

CONCLUSIONS

Our results revealed the dynamics of cell subpopulations, gene expression and intercellular interactions during AS pathogenesis. These findings provide new insights into the cellular and molecular mechanisms of osteogenesis and will benefit the development of novel therapeutic strategies.

SPI1 Regulates the Progression of Ankylosing Spondylitis by Modulating TLR5 via NF-κB Signaling

Ankylosing spondylitis (AS) is an autoimmune disease which associated with inflammation of the spinal joints. Enhanced osteogenic differentiation was observed in AS; however, the underlying mechanism remains undefined. A cohort of AS (n = 15) and patients with traumatic fracture (n = 15) were recruited to this study. Fibroblasts were isolated, and characterized by H&E and immunocytochemistry (ICC) analysis. The expression and secretion of key molecules were detected by qRT-PCR, western blot, immunofluorescence (IF), and ELISA. Calcium deposition and alkaline phosphatase (ALP) activity were monitored by Alizarin Red S and ALP staining. The direct association between Spi-1 proto-oncogene (SPI1) and toll-like receptor 5 (TLR5) promoter was assessed by ChIP assay. AS fibroblasts was successfully isolated and exhibited osteogenic differentiation potentials. SPI1 was elevated in AS fibroblasts, and silencing of SPI1 inhibited osteogenic differentiation of AS fibroblasts. Mechanistic study showed that SPI1 acted as a transcriptional activator of TLR5. Knockdown of TLR5 suppressed osteogenic differentiation of AS fibroblasts via nuclear factor kappa B (NF-κB) signaling. Rescue experiments revealed that overexpression of TLR5 reversed SPI1 knockdown-suppressed osteogenic differentiation via NF-κB signaling. SPI1 regulated the progression of AS by modulating TLR5 via NF-κB signaling.

Functional mechanism of miR-92b-3p in osteogenic differentiation of fibroblasts in patients with ankylosing spondylitis via the TOB1/BMP/Smad pathway

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis. Upregulation of microRNA (miR)-92b-3p is associated with enhanced osteoblastic differentiation. The current study sought to investigate the functional mechanism of miR-92b-3p in osteogenic differentiation of AS fibroblasts.

METHODS

First, fibroblasts were isolated from AS and non-AS patients and cultured. Next, cell morphology was observed, cell proliferation was assessed and the vimentin expression pattern was determined. Alkaline phosphatase (ALP) activity and levels of osteogenic markers RUNX2, OPN, OSX, and COL I were additionally measured, followed by determination of miR-92b-3p and TOB1 levels. The binding site of miR-92b-3p and TOB1 was predicted, and their target relationship was validated. Lastly, miR-92b-3p inhibitor, si-TOB1, and the BMP/Smad signaling pathway inhibitor LDN193189 were delivered into AS fibroblasts to evaluate the osteogenic differentiation of AS fibroblasts and the activation of the BMP/Smad pathway.

RESULTS

miR-92b-3p was highly expressed in AS fibroblasts. AS fibroblasts showed enhanced osteogenic differentiation and proliferation, while inhibition of miR-92b-3p suppressed osteogenic differentiation and proliferation of AS fibroblasts. miR-92b-3p targeted TOB1, and TOB1 was poorly expressed in AS fibroblasts. The concurrent downregulation of TOB1 and inhibition of miR-92b-3p elevated the levels of RUNX2, OPN, OSX, and COL I and ALP activity and further enhanced the proliferation of AS fibroblasts. The BMP/Smad pathway was activated in AS fibroblasts. Silencing miR-92b-3p could inhibit the activation of the BMP/Smad pathway by upregulating TOB1. Inhibition of the BMP/Smad pathway reduced the number of calcified nodules and hindered the osteogenic differentiation and proliferation of AS fibroblasts.

CONCLUSION

Our findings highlighted that silencing miR-92b-3p inhibited the osteogenic differentiation and proliferation of AS fibroblasts by upregulation of TOB1 and inhibition of the BMP/Smad pathway.

Effectiveness of tumor necrosis factor inhibitors in children with enthesitis-related arthritis: a single-center retrospective analysis

Objective

In children with enthesitis-related arthritis (ERA), the hip and sacroiliac joint function might be impaired if not properly treated. We sought to evaluate the effectiveness of anti-tumor necrosis factor-α (TNF-α) therapy using the inflammatory indicators, Juvenile Arthritis Disease Activity Score 27 (JADAS27) and magnetic resonance imaging (MRI).

Methods

We conducted a single-center retrospective study of 134 patients with ERA. We evaluated the effect of anti-TNF therapy on the inflammatory indicators, active joint count, MRI quantitative score, and JADAS27 over 18 months. We used the Spondyloarthritis Research Consortium of Canada (SPARCC) and the Hip Inflammation MRI Scoring System (HIMRISS) scoring systems for hip and sacroiliac joints scoring.

Results

The average age of onset of children with ERA was 11.62 ± 1.95 years, and they were treated with disease-modifying antirheumatic drugs (DMARDs) combined with biologics (n = 87, 64.93%). There were no differences in HLA-B27 positivity between the biologics and non-biologics treatment groups [66 (49.25%) vs. 68 (50.75%), P > 0.05]. Children who received anti-TNF (71 received etanercept, 13 adalimumab, 2 golimumab, and 1 infliximab) therapy improved significantly. Children with ERA used DMARDs and biologics at baseline (Group A) were followed up to 18 months, and their active joint count (4.29 ± 1.99 vs. 0.76 ± 1.33, P = 0.000), JADAS27 (13.70 ± 4.80 vs. 4.53 ± 4.52, P = 0.000) and MRI quantitative scores (P = 0.001) were significantly lower than those at baseline. Some of the patients (n = 13, 9.70%) were treated with DMARDs at the onset of the disease, but did not show significant improvement (Group B). After 6-18 months of switching to anti-TNF therapy, related indicators of the children were significantly lower than at baseline and 1 month (P < 0.013). At 18 months, a total of 33 patients (n = 74, 44.59%) in Group A and 7 (n = 13, 53.85%) in Group B reached inactive state.

Conclusion

Eighteen months after diagnosis, anti-TNF therapy was found to be effective in children diagnosed with ERA. MRI is important for the early diagnosis of juvenile idiopathic arthritis. TNF-α inhibitors can significantly improve the clinical manifestations of sacroiliac joint and hip involvement in patients with ERA. Overall, the real-world study provides more evidence for precision diagnosis and treatment for other hospitals, families and patients.

Ultrasonography of heel entheses in axial spondyloarthritis patients: frequency and assessment of associated factors

PURPOSE

Foot entheses involvement is a common manifestation of spondyloarthritis. The superiority of ultrasonography examination in foot entheses damages detection has been reported. We aimed to compare the ultrasonography findings of foot entheses between spondyloarthritis patients. and healthy controls and to identify factors associated with enthesitic heel involvement.

METHODS

We conducted a cross-sectional study including 37 patients with axial spondyloarthritis (G1) and 37 healthy subjects matched by age and gender (G0). The following pro-inflammatory cytokines were measured: Interleukin (IL-)1, IL-6, IL-17, and IL-23. A blind ultrasonography of foot entheses was performed to examine calcaneal tendon (CT) and plantar fascia (PF).

RESULTS

The mean age was 44.62 ± 12.31 years. Non-steroidal anti-inflammatory drugs were taken in 92% of patients. Clinical heel enthesopathy was noted in 10 patients (27%) of G1. No participant has enthesitic pain in G0. Ultrasonography changes in CT and PF were more frequent in G1 than G0 (p = 0.001 and p = 10-3, respectively). In the PF, tendon thickening was significantly higher in G1 than G0 (p = 0.03). Power Doppler in both enthesitic sites was exclusively observed in G1 (p = 10-3). Regarding associated factors, CT enthesophytes were less frequent in patients taking non-steroidal anti-inflammatory drugs continuously or having regular physical activity. PF structural damages were associated with higher erythrocyte sedimentation rate (p = 0.02), higher IL-23 level (p = 0.01), and higher disease activity (p = 0.04).

CONCLUSION

Ultrasonography lesions of heel entheses were frequent in spondyloarthritis. Disease activity and inflammatory markers were higher in patients with heel enthesitis. Non-steroidal anti-inflammatory drugs intake and regular physical activity may prevent enthesophytes' occurrence.

Spinal radiographic progression is correlated with preclinical atherosclerosis in spondyloarthritis

BACKGROUND

A higher prevalence of cardiovascular risk was observed in spondyloarthritis (SpA). The relationship between disease-related factors structural damage and subclinical atherosclerosis is still unknown.

OBJECTIVE

The aim of our study was to evaluate the association of subclinical atherosclerosis with radiographic structural damage in patients with SpA.

METHODS

Forty-seven SpA patients who fulfilled the ASAS criteria were enrolled in a case-control study conducted over 12 months and compared with 47 age and sex-matched healthy controls. None of the subjects had a previous history of cardiovascular diseases or cardiovascular risk factors. Demographic and disease characteristics were recorded. Structural lesions were evaluated using plain radiography, and two scoring tools were used to spine (BASRI and mSASSS). Subclinical atherosclerosis was assessed using ultrasound measurements of flow-mediated dilation (FMD) and carotid intima-media thickness (cIMT).

RESULTS

The median age of patients was 36 years. The sex ratio was 2.35. The median BASRI total score was 3 (IQR 2-4), median mSASSS score was 10 (IQR 415). cIMT was significantly increased in SpA patients compared to controls (p< 0.0001), and FMD was significantly lower in patients than in healthy subjects (p= 0.008). cIMT was significantly associated with ankylosis of the facet joints (p= 0.035) and Romanus spondylitis (p= 005). FMD was negatively associated with vertebral squaring (p= 0049), bridging syndesmophytes (p= 0031) and mSASSS score (p= 0.047).

CONCLUSION

Our result supports the association of radiographic structural damage and subclinical atherosclerosis assessed using cIMT and FMD. This finding highlights the importance of earlier treatment in order to prevent radiographic damage progression and atherosclerotic events.

Circ_0018168 inhibits the proliferation and osteogenic differentiation of fibroblasts in ankylosing spondylitis via regulating miR-330-3p/DKK1 axis

Background

Circular RNAs (circRNAs) play a crucial regulatory role in human diseases. However, the roles of circRNAs in ankylosing spondylitis (AS) are barely known. In this study, the functions of circ_0018168 in AS were investigated.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assay were used for circ_0018168, microRNA-330-3p (miR-330-3p), dickkopf-1 (DKK1), alkaline phosphatase (ALP), osteocalcin (OCN), Runt-related transcription factor 2 (Runx2) levels. Cell Counting Kit-8 (CCK-8) assay and 5′-ethynyl-2′-deoxyuridine (EdU) assay were conducted to analyze cell proliferation ability. Flow cytometry analysis was manipulated for cell cycle process. ALP activity was examined with a commercial kit. RNA immunoprecipitation (RIP) assay, RNA pull-down assay and dual-luciferase reporter assay were used to analyze the relationships of circ_0018168, miR-330-3p and DKK1.

Results

Circ_0018168 and DKK1 levels were lowly expressed in AS hip capsule specimens. Circ_0018168 overexpression repressed cell proliferation, cell cycle process as well as reduced ALP activity and ALP, OCN and Runx2 protein levels in AS fibroblasts. DKK1 silencing ameliorated the impact of circ_0018168 on AS progression. In addition, circ_0018168 served as the sponge for miR-330-3p, which could target DKK1. MiR-330-3p inhibition suppressed the proliferation, cell cycle and osteogenic differentiation in AS fibroblasts, but DKK1 silencing reversed the impacts. Besides, the effect of circ_0018168 on AS development was abolished by miR-330-3p upregulation.

Conclusion

Circ_0018168 overexpression restrained fibroblast proliferation and osteogenic differentiation in AS by elevating DKK1 through adsorbing miR-330-3p.

Bone Involvement in Patients with Spondyloarthropathies

Spondyloarthropathies (SpA) are common systemic inflammatory rheumatic diseases, in which, as in other rheumatic diseases, levels of markers of bone resorption are elevated, leading to bone loss and elevated risk of vertebral fractures. However, the diseases are also associated with new bone formation in the spine, the so-called syndesmophytes. We tried to unravel the pathogenesis of formation and growth of syndesmophytes and evaluated new diagnostic and treatment options. After a successful meeting of the Working Group on Rheumatic Diseases at the ECTS 2020, we (WL and CR) were excited about the quality of the speakers (CM, JH, AG, and GL) and their complimentary lectures. Given the relative lack of reviews on spondyloarthropathies and bone, we decided to work together on a comprehensive review that might be interesting for basic scientists and clinically relevant for clinicians. Radiographic progression in axSpA is linked to several risk factors, like male sex, smoking, HLA-B-27, increased levels of CRP, presence of syndesmophytes, and marked inflammation on MRI. The potential role of mechanical stress in the context of physically demanding jobs has been also suggested to promote structural damages. Different treatment options from NSAIDs to biologic agents like TNF inhibitors (TNFi) or IL-17inhibitors (IL-17i) result in a reduction of inflammation and symptoms. However, all these different treatment options failed to show clear and reproducible results on inhibition on syndesmophyte formation. The majority of data are available on TNFi, and some studies suggested an effect in subgroups of patients with ankylosing spondylitis. Less information is available on NSAIDs and IL-17i. Since IL-17i have been introduced quite recently, more studies are expected. IL-17 inhibitors (Il-17i) potently reduce signs and symptoms, but serum level of IL-17 is not elevated, therefore, IL-17 probably has mainly a local effect. The failure of anti-IL-23 in axSpA suggests that IL-17A production could be independent from IL-23. It may be upregulated by TNFα, resulting in lower expression of DKK1 and RANKL and an increase in osteogenesis. In active AS markers of bone resorption are increased, while bone formation markers can be increased or decreased. Bone Turnover markers and additional markers related to Wnt such as DKK1, sclerostin, and RANKL are valuable for elucidating bone metabolism on a group level and they are not (yet) able to predict individual patient outcomes. The gold standard for detection of structural lesions in clinical practice is the use of conventional radiographics. However, the resolution is low compared to the change over time and the interval for detecting changes are 2 years or more. Modern techniques offer substantial advantages such as the early detection of bone marrow edema with MRI, the fivefold increased detection rate of new or growing syndesmophytes with low-dose CT, and the decrease in 18F-fluoride uptake during treatment with TNFα-inhibitors (TNFi) in a pilot study in 12 AS patients. Detection of bone involvement by new techniques, such as low-dose CT, MRI and 18-Fluoride PET-scans, and bone turnover markers, in combination with focusing on high-risk groups such as patients with early disease, elevated CRP, syndesmophytes at baseline, male patients and patients with HLA-B27 + are promising options for the near future. However, for optimal prevention of formation of syndesmophytes we need more detailed insight in the pathogenesis of bone formation in axSpA and probably more targeted therapies.

Therapeutic potential of triptolide in autoimmune diseases and strategies to reduce its toxicity

With the increasing epidemiology of autoimmune disease worldwide, there is an urgent need for effective drugs with low cost in clinical treatment. Triptolide, the most potent bioactive compound from traditional Chinese herb Tripterygium Wilfordii Hook F, possesses immunosuppression and anti-inflammatory activity. It is a potential drug for the treatment of various autoimmune diseases, but its clinical application is still restricted due to severe toxicity. In this review, the pharmacodynamic effects and pharmacological mechanisms of triptolide in autoimmune diseases are summarized. Triptolide exerts therapeutic effect by regulating the function of immune cells and the expression of cytokines through inflammatory signaling pathways, as well as maintaining redox balance and gut microbiota homeostasis. Meanwhile, the research progress on toxicity of triptolide to liver, kidney, reproductive system, heart, spleen, lung and gastrointestinal tract has been systematically reviewed. In vivo experiments on different animals and clinical trials demonstrate the dose- and time- dependent toxicity of triptolide through different administration routes. Furthermore, we focus on the strategies to reduce toxicity of triptolide, including chemical structural modification, novel drug delivery systems, and combination pharmacotherapy. This review aims to reveal the potential therapeutic prospect and limitations of triptolide in treating autoimmune diseases, thus providing guiding suggestions for further study and promoting its clinical translation.

Chondrogenesis mediates progression of ankylosing spondylitis through heterotopic ossification

Ankylosing spondylitis (AS) is chronic inflammatory arthritis with a progressive fusion of axial joints. Anti-inflammatory treatments such as anti-TNF-α antibody therapy suppress inflammation but do not effectively halt the progression of spine fusion in AS patients. Here we report that the autoimmune inflammation of AS generates a microenvironment that promotes chondrogenesis in spine ligaments as the process of spine fusion. Chondrocyte differentiation was observed in the ligaments of patients with early-stage AS, and cartilage formation was followed by calcification. Moreover, a large number of giant osteoclasts were found in the inflammatory environment of ligaments and on bony surfaces of calcified cartilage. Resorption activity by these giant osteoclasts generated marrow with high levels of active TGF-β, which induced new bone formation in the ligaments. Notably, no Osterix+ osteoprogenitors were found in osteoclast resorption areas, indicating uncoupled bone resorption and formation. Even at the late and maturation stages, the uncoupled osteoclast resorption in bony interspinous ligament activates TGF-β to induce the progression of ossification in AS patients. Osteoclast resorption of calcified cartilage-initiated ossification in the progression of AS is a similar pathologic process of acquired heterotopic ossification (HO). Our finding of cartilage formation in the ligaments of AS patients revealed that the pathogenesis of spinal fusion is a process of HO and explained why anti-inflammatory treatments do not slow ankylosing once there is new bone formation in spinal soft tissues. Thus, inhibition of HO formation, such as osteoclast activity, cartilage formation, or TGF-β activity could be a potential therapy for AS.

Evaluation of the oral administration of α-l-guluronic acid on COX-1 and COX-2 gene expression profile in ankylosing spondylitis patients

Ankylosing spondylitis (AS) is a chronic autoimmune arthritis disease with a genetic background, affecting the skeletal axis, sacroiliac, and peripheral joints. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first-line treatment for AS to alleviate the inflammation and pain. Despite the beneficial effect, their use is accompanied by a wide variety of possible side effects in the gastrointestinal and kidneys. The α-l-guluronic acid (G2013) is a new nonsteroidal anti-inflammatory patented (PCT/EP2017/067920) drug, which has shown its anti-inflammatory properties in the previous investigations. The present study revealed the oral administration effect of G2013 on COX-1 and COX-2 gene expression in AS patients. The blood samples of twelve 18-45 years old patients suffering AS and BASDAI >4, and BASFI >4, before and after 12 weeks of treatment with G2013 and 12 blood samples of healthy volunteers were collected and the effect of G2013 on the gene expression of COX-1 and COX-2 enzymes were assessed by Real-Time PCR. The results indicate that G2013 is able to reduce the gene expression level of COX-1 and COX-2 enzymes in treated AS patients compared to healthy control. Statistically significant differences were not observed between the treatment and the healthy control groups. According to the findings, G2013 might be categorized and introduced as a novel NSAID for the treatment of AS.

Association of Regional Bone Synthetic Activities of Vertebral Corners and Vertebral Bodies Quantified Using 18F-Fluoride Positron Emission Tomography with Bone Mineral Density on Dual Energy X-ray Absorptiometry in Patients with Ankylosing Spondylitis

We investigated whether the bone-synthetic activities of vertebral bodies or vertebral corners quantified using ¹⁸F-fluoride positron emission tomography (PET) was associated with bone mineral density (BMD) at the corresponding lumbar vertebrae in ankylosing spondylitis (AS) at each vertebra level. We analyzed 48 lumbar vertebrae in 12 AS patients who underwent ¹⁸F-fluoride PET and dual energy X-ray absorptiometry (DXA). The mean standardized uptake values (SUVmean) of the vertebral body and corners from L1 to L4 were measured using the spatially separated region of interest (ROI). The L1–L4 BMDs were calculated based on the DXA (“conventional BMD”). The BMD of the internal vertebral bodies was measured by manually drawing ROIs to represent the trabecular BMD (“alternative BMD”). After adjusting the within-patient correlation, the ¹⁸F-fluoride SUVmean of the vertebral corners but not that of vertebral bodies was significantly related with the conventional BMD of the vertebra. Otherwise, the ¹⁸F-fluoride uptake of both the vertebral and vertebral bodies was significantly related with the alternative BMD. The bone-synthetic activities of the vertebral corners may be more closely related with BMD than those of the vertebral bodies, suggesting that the effects of regional bone metabolism at the vertebral corners and bodies on BMD differ in AS.

Comparison of the Effects of Secukinumab and Adalimumab Biosimilar on Radiographic Progression in Patients with Ankylosing Spondylitis: Design of a Randomized, Phase IIIb Study (SURPASS)

BACKGROUND AND OBJECTIVE

Secukinumab, an anti-interleukin (IL)-17A monoclonal antibody, has demonstrated low radiographic progression over 4 years in patients with ankylosing spondylitis (AS). An adalimumab (tumor necrosis factor [TNF] inhibitor) biosimilar, GP2017 (SDZ-ADL; Sandoz), has been approved by the European Medicines Agency (July 2018) for use in all same indications as adalimumab, including AS. Adalimumab has also shown low long-term radiographic progression in patients with AS. Direct comparison of radiographic progression in AS between IL-17A and TNF inhibitors has not been studied. SURPASS is the first head-to-head, Phase IIIb, randomized, biologic-controlled study in AS to compare effects of secukinumab versus SDZ-ADL on spinal radiographic progression.

METHODS

Overall, 858 biologic-naïve patients with AS with elevated high-sensitivity C-reactive protein (≥ 5 mg/L) and/or at least one syndesmophyte in the cervical/lumbar spine at baseline (without total ankylosis) were randomized (1:1:1) to subcutaneous (sc) secukinumab (300 or 150 mg) or SDZ-ADL (40 mg). Secukinumab will be administered at baseline, weeks 1, 2, 3, and 4, and then every 4 weeks until week 100. SDZ-ADL will be administered every 2 weeks from baseline until week 102. Patients and investigators will be unblinded to drug but blinded to secukinumab doses. Spinal X-rays will be obtained at baseline, and weeks 52 and 104, sacroiliac joint (SIJ) X-rays at baseline and week 104, and magnetic resonance imaging (MRI) of SIJs and spine at baseline, weeks 16, 52, and 104. The primary endpoint is to demonstrate superiority of secukinumab (300 or 150 mg) treatment versus SDZ-ADL regarding proportion of patients with no radiographic progression (change from baseline in modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS] ≤ 0.5) at week 104. Secondary endpoints include change from baseline in mSASSS, proportion of patients with syndesmophyte at baseline who develop no new syndesmophytes, reduction of osteitis on MRI of SIJs and spine (Berlin method). Assessment of SpondyloArthritis International Society (ASAS) 20/40 responses, ASAS partial remission, and AS Disease Activity Score (ASDAS) inactive disease (ASDAS < 1.3) in secukinumab- versus SDZ-ADL-treated patients at week 104.

CONCLUSION

This is the first study designed to evaluate superiority of an IL-17A inhibitor, secukinumab, over a TNF inhibitor, SDZ-ADL, in reducing spinal radiographic progression in AS.

STUDY REGISTRATION

ClinicalTrials.gov, NCT03259074.

microRNA-214-3p Suppresses Ankylosing Spondylitis Fibroblast Osteogenesis via BMP-TGFβ Axis and BMP2

Recent investigations suggest microRNAs (miRs) exert functions in fibroblast osteogenesis in ankylosing spondylitis (AS), an inflammatory rheumatic disease. But the mechanism of miR-214-3p in osteogenic differentiation in AS is not clearly understood yet. In this study, fibroblasts were obtained from the capsular ligament of patients with AS and femoral neck fracture and cultured for osteogenic induction and identified. The roles of miR-214-3p and bone morphogenic protein 2 (BMP2) in AS fibroblast osteogenesis were assessed via gain- and loss-of-function, alizarin red S staining, and alkaline phosphatase (ALP) detection. Levels of miR-214-3p, BMP2, osteogenic differentiation-related proteins, and BMP-TGFβ axis-related proteins were further measured. Consequently, miR-214-3p was downregulated in AS fibroblasts, with enhanced ALP activity and calcium nodules, which were reversed by miR-214-3p overexpression. BMP2 was a target gene of miR-214-3p and promoted AS fibroblast osteogenesis by activating BMP-TGFβ axis, while miR-214-3p inhibited AS fibroblast osteogenesis by targeting BMP2. Together, miR-214-3p could prevent AS fibroblast osteogenic differentiation by targeting BMP2 and blocking BMP-TGFβ axis. This study may offer a novel insight for AS treatment.

Role of IL-32 Gamma on Bone Metabolism in Autoimmune Arthritis

IL-32 acts as a pro-inflammatory cytokine by inducing the synthesis of inflammatory molecules as well as promoting the morphological changes involved in the transformation of monocytes into osteoclasts (OCs). Evaluation of the functions of IL-32 has mainly focused on its inflammatory properties, such as involvement in the pathogenesis of various autoimmune diseases. Recently, IL-32 was shown to be involved in bone metabolism, in which it promotes the differentiation and activation of OCs and plays a key role in bone resorption in inflammatory conditions. IL-32γ also regulates bone formation in conditions such as ankylosing spondylitis and osteoporosis. In this review, we summarize the results of recent studies on the role of IL-32γ in bone metabolism in inflammatory arthritis.

Serum Sclerostin as a Possible Biomarker in Ankylosing Spondylitis: A Case-Control Study

Objective

Several molecules are involved in the pathogenesis of a new bone formation in ankylosing spondylitis (AS). The aim of this study was to evaluate the serum levels of sclerostin in patients with AS as a possible biomarker and to investigate any correlations with radiographic damage, disease activity, and function.

Methods

AS patients fulfilled the modified New York criteria, and healthy controls were enrolled for this study. BASDAI, ASDAS-CRP, BASMI, BASFI, patient and physician VAS, and C-reactive protein were evaluated at baseline visit. Spinal damage was assessed using the mSASSS on radiographs performed within 3 months from baseline. Serum concentrations of sclerostin were assessed at baseline and after four months of therapy in patients who started an anti-TNF.

Results

Twenty healthy subjects and 40 AS patients were enrolled in the study. In our group, serum sclerostin levels (median (25th–75th percentile)) were significantly higher in healthy controls (18.04 (13.6–24) pg/ml) than in AS patients (6.46 (4.5–11.1) pg/ml; P value < 0.01). However, no significant correlations were found between serum sclerostin levels and radiographic damage, assessed by mSASSS, and between serum sclerostin levels and clinical indices of activity and disability or with laboratory parameters. Sclerostin levels did not show significant changes after 4 months of anti-TNF therapy.

Conclusions

The results of our study suggest a possible role of sclerostin in the identification of AS patients. Further studies are needed to prove the role of sclerostin as a disease activity biomarker and progression of disease in AS.

Triptolide inhibits proliferation, differentiation and induces apoptosis of osteoblastic MC3T3‑E1 cells

Ankylosing spondylitis (AS) is characterized by the formation of bony spurs. Treatment of the resulting ankylosis, excessive bone formation and associated functional impairment, remain the primary therapeutic aims in research regarding this condition. Triptolide is the primary active component of the perennial vine Tripterygium wilfordii Hook. f., and has previously been demonstrated to exert anti-tumor activities including inhibition of cell growth and the induction of apoptosis, however, the effect of triptolide on osteoblasts remains to be elucidated. In the present study, the MC3T3-E1 mouse osteoblast cell line was treated with differing concentrations of triptolide for various intervals. Cell proliferation was detected using the bromodeoxyuridine assay, cell cycle and apoptosis were measured by flow cytometry, nuclear apoptosis was observed by Hoechst staining and associated proteins were determined via western blot analysis. The cells were then further incubated with osteogenic induction medium supplemented with triptolide for 7 or 12 days and the differentiation to osteoblasts was examined by picrosirius staining, observation of alkaline phosphatase activity and a calcium deposition assay. It was demonstrated that treatment with triptolide significantly inhibited osteoblast proliferation and induced cell cycle arrest and apoptosis of the osteoblasts. Furthermore, treatment with triptolide reduced collagen formation, alkaline phosphatase activity and calcium deposition. The present study demonstrated an inhibitory effect of triptolide on osteoblast proliferation and differentiation, and therefore suggests a potential therapeutic agent for the treatment of AS in the future.

Macrophage Migration Inhibitory Factor Induces Inflammation and Predicts Spinal Progression in Ankylosing Spondylitis

OBJECTIVE

To investigate the role of macrophage migration inhibitory factor (MIF) in the pathogenesis of ankylosing spondylitis (AS).

METHODS

Patients who met the modified New York criteria for AS were recruited for the study. Healthy volunteers, rheumatoid arthritis patients, and osteoarthritis patients were included as controls. Based on the annual rate of increase in modified Stoke AS Spine Score (mSASSS), AS patients were classified as progressors or nonprogressors. MIF levels in serum and synovial fluid were quantitated by enzyme-linked immunosorbent assay. Predictors of AS progression were evaluated using logistic regression analysis. Immunohistochemical analysis of ileal tissue was performed to identify MIF-producing cells. Flow cytometry was used to identify MIF-producing subsets, expression patterns of the MIF receptor (CD74), and MIF-induced tumor necrosis factor (TNF) production in the peripheral blood. MIF-induced mineralization of osteoblast cells (SaOS-2) was analyzed by alizarin red S staining, and Western blotting was used to quantify active β-catenin levels.

RESULTS

Baseline serum MIF levels were significantly elevated in AS patients compared to healthy controls and were found to independently predict AS progression. MIF levels were higher in the synovial fluid of AS patients, and MIF-producing macrophages and Paneth cells were enriched in their gut. MIF induced TNF production in monocytes, activated β-catenin in osteoblasts, and promoted the mineralization of osteoblasts.

CONCLUSION

Our findings indicate an unexplored pathogenic role of MIF in AS and a link between inflammation and new bone formation.

Association Between Dentin Matrix Protein 1 (rs10019009) Polymorphism and Ankylosing Spondylitis in a Chinese Han Population from Shandong Province

Background:

Ankylosing spondylitis (AS) is the most common rheumatic condition that is slowly progressive and predominantly affects adolescents. Pathological bone formation associated with AS is an important cause of disability. The aim of the study was to investigate the possible involvement of the genes related to endochondral ossification and ectopia ossification in genetic susceptibility to AS in a Chinese Han population.

Methods:

Sixty-eight single nucleotide polymorphisms (SNPs) from 13 genes were genotyped in discovery cohorts including 300 AS patients and 180 healthy controls. The rs10019009 in dentin matrix protein 1 (DMP1) gene shown as association with AS after multiple testing corrections in discovery cohorts was replicated in a validation independent cohort of 620 AS patients and 683 healthy controls. The rs10019009 was assessed with bioinformatics including phylogenetic context, F-SNP and FastSNP functional predictions, secondary structure prediction, and molecular modeling. We performed a functional analysis of rs10019009 via reverse transcription-polymerase chain reaction, alkaline phosphatase (ALP) activity in human osteosarcoma U₂OS cells.

Results:

Interestingly, the SNP rs10019009 was associated with AS in both the discovery cohort (P = 0.0012) and validation cohort (P = 0.0349), as well as overall (P = 0.0004) in genetic case–control association analysis. After a multivariate logistic regression analysis, the effect of this genetic variant was observed to be independent of linkage disequilibrium. Via bioinformatics analysis, it was found that the amino acid change of the rs10019009 led to changes of SNP function, secondary structure, tertiary conformation, and splice mode. Finally, functional analysis of rs10019009 in U₂OS cells demonstrated that the risk T allele of the rs10019009 increased enzymatic activity of ALP, compared to that of the nonrisk allele (P = 0.0080).

Conclusions:

These results suggested that the DMP1 gene seems to be involved in genetic predisposition to AS, which may contribute to the ectopic mineralization or ossification in AS. In addition, DMP1 gene may be a promising intervention target for AS in the future.

Bushen Qiangji Granule () medicated serum inhibits osteogenic differentiation of fibroblasts in ankylosing spondylitis by inhibiting the BMP/Smads signal pathway in vitro

OBJECTIVE

To explore the mechanism of Bushen Qiangji Granule (, BSQJ) in restraining the osteogenic differentiation of ankylosing spondylitis (AS) fifibroblasts.

METHODS

Hip joint capsules were obtained from AS patients (n=10) receiving total hip replacement and healthy hip joint capsules from patients with hip fracture (n=10) receiving surgery as a control. Finite fifibroblast lines were established from these tissue samples to observe the effect of BSQJ on suppressing osteogenic differentiation of fifibroblasts. The expression of osteogenic marker gene corebinding factor a1 (Cbfa1) and Smad family proteins were examined by Western blot and real-time quantitative polymerase chain reaction (qPCR).

RESULTS

The mRNA expression level of Cbfa1 was significantly higher in AS fibroblasts than that in normal fibroblasts and the expression of pSmad1, pSmad5, Smad4 and Cbfa1 in AS fibroblasts was also higher, demonstrating the activation of the BMP/Smads signal pathway in AS fifibroblasts. BSQJ-medicated serum not only restrained the mRNA and protein expression levels of Cbfa1 and inhibited protein expression level of Smad4 but also decreased the expression quantities of pSmad1 and pSmad5.

CONCLUSIONS

BSQJ can inhibit osteogenic differentiation of AS fifibroblasts in vitro by suppressing the activation of the BMP/Smads signal pathway. This may be the important molecular mechanism of BSQJ in regulating AS ossifification.

Insulin-Like Growth Factor I Does Not Drive New Bone Formation in Experimental Arthritis

Introduction

Insulin like growth factor (IGF)-I can act on a variety of cells involved in cartilage and bone repair, yet IGF-I has not been studied extensively in the context of inflammatory arthritis. The objective of this study was to investigate whether IGF-I overexpression in the osteoblast lineage could lead to increased reparative or pathological bone formation in rheumatoid arthritis and/or spondyloarthritis respectively.

Methods

Mice overexpressing IGF-I in the osteoblast lineage (Ob-IGF-I^+/-) line 324–7 were studied during collagen induced arthritis and in the DBA/1 aging model for ankylosing enthesitis. Mice were scored clinically and peripheral joints were analysed histologically for the presence of hypertrophic chondrocytes and osteocalcin positive osteoblasts.

Results

90–100% of the mice developed CIA with no differences between the Ob-IGF-I^+/- and non-transgenic littermates. Histological analysis revealed similar levels of hypertrophic chondrocytes and osteocalcin positive osteoblasts in the ankle joints. In the DBA/1 aging model for ankylosing enthesitis 60% of the mice in both groups had a clinical score 1<. Severity was similar between both groups. Histological analysis revealed the presence of hypertrophic chondrocytes and osteocalcin positive osteoblasts in the toes in equal levels.

Conclusion

Overexpression of IGF-I in the osteoblast lineage does not contribute to an increase in repair of erosions or syndesmophyte formation in mouse models for destructive and remodeling arthritis.

Insight on Bone Morphogenetic Protein 7 in Ankylosing Spondylitis and its association with disease activity and radiographic damage

Introduction

Fusion of joints as well as intervertebral spaces by the formation of bony spurs appearing as syndesmophytes and osteophytes are the hallmark of spondyloarthropathies which accounts for disability. The aim of this study was to assess the serum level of bone morphogenetic protein (BMP)-7 in ankylosing spondylitis and its relationship with disease activity and the radiographic damage.

Methods

This longitudinal case control study was conducted in Ain Shams University Hospitals (Egypt). A total of 55 subjects were included in two case groups and one control group. Group I included 20 patients with Ankylosing Spondylitis (AS) assessed at baseline (defined as Ia and after 18 months defined as Ib). Group II included 20 patients with Rheumatoid Arthritis (RA) and Group III included 15 healthy subjects as controls. Patients with other forms of seronegative spondyloarthropathies, bone forming diseases were excluded from the study. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Bath Ankylosing Spondylitis Metrology Index (BASMI) were used to assess disease activity in AS patients. RA disease activity was assessed using the disease activity score 28 (DAS28). Radiographic changes were assessed using the Bath AS Radiographic Index (BASRI) in AS and Larsen scores in RA. Laboratory investigations included: Complete blood picture (CBC), Erythrocyte sedimentation rate (ESR), quantitative CRP, serum calcium, phosphorus and alkaline phosphatase. Determination of serum bone morphogenetic protein-7 level (BMP-7) was done using enzyme linked immunosorbent assay (ELISA). Sample collections, clinical and radiological assessments were performed at baseline for all groups and after a mean follow-up of 18 months for Group I. Data were analyzed by SPSS 17, using t-test, Kruskal-Wallis, Mann-Whitney, Fischer exact test, Chi square, and Pearson Product-Moment Correlation Coefficient.

Results

There were statistically significant differences between the 3 groups as regard baseline BMP-7 levels; the mean BMP-7 level of AS patients was significantly higher than that of RA patients and controls and significantly higher in the RA group than that of controls. BMP-7 levels were not associated with any of the clinical or drug related variables either in AS or RA. In AS BMP-7 levels showed significant increase after follow up and significant positive correlation with serum alkaline phosphatase (both at baseline and after follow up) and BASDAI score (after follow up) respectively. Despite the parallel increase of BMP7 and BASRI score during the follow-up period no statistically significant correlation was detected. There were no significant correlations between BMP7 level and patient’s age or any disease related characteristics in the RA group.

Conclusion

A significant progressive increase in serum BMP-7 was noted in AS patients that correlated with serum markers of bone formation. Such a biomarker measurement may not only act as a surrogate marker for the disease but has the potential to contribute to the pathogenesis of AS that may provide a complementary or alternative therapeutic approach.

High level of interleukin-32 gamma in the joint of ankylosing spondylitis is associated with osteoblast differentiation

Backgound

The formation of bony spurs and ankylosis is a key pathognomic feature in ankylosing spondylitis (AS) and results in functional impairment. The aim of this study was to investigate the role of IL-32γ in osteoblast (OB) differentiation and its association with the pathogenesis of AS.

Methods

The concentration and expression of IL-32γ were evaluated in synovial fluid and tissue from patients with AS, rheumatoid arthritis (RA) and osteoarthritis (OA), using enzyme-linked immunosorbent assay and immunohistochemistry. To establish whether IL-32γ affects OB differentiation, we used calvarial cells of IL-32γ transgenic (TG) mice or wild-type (WT) mice. To elucidate the mechanism of osteoblastogenesis, levels of regulators were assayed in IL-32γ TG mice and in primary OBs after IL-32γ stimulation.

Results

The IL-32γ levels were higher in the synovial fluid of AS patients compared with RA or OA patients and the expression of IL-32 was higher in AS synovia than in RA or OA synovia. Additional IL-32γ stimulation in precursor cells enhanced OB differentiation potentially and IL-32γ TG mice showed higher rates of OB differentiation than WT mice. IL-32γ reduced the expression of DKK-1, a negative regulator, in both WT precursor cells and human OBs and the constitutive expression of DKK-1 was suppressed in calvarial cells from IL-32γ TG mice.

Conclusions

The elevated level of IL-32γ in AS joint could enhance OB differentiation via DKK-1 suppression. Therefore, IL-32γ might be a putative molecular target to prevent the abnormal bone formation in AS.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0870-4) contains supplementary material, which is available to authorized users.

Wnt5a is expressed in spondyloarthritis and exerts opposite effects on enthesis and bone in murine organ and cell cultures

Spondyloarthritis (SpA) is a chronic inflammatory joint disorder that initiates at the enthesis, where tendons attach to bone through a fibrocartilage zone. At late stages, excessive bone apposition appears within the diseased enthesis. Because Wnt5a participates to normal bone formation and appears related to inflammatory processes, we investigated the role of this Wnt growth factor in inflammation-associated ossification in SpA. The concentration of Wnt5a assessed by enzyme-linked immunosorbent assay in synovial fluids of patients with SpA (2.58 ± 0.98 ng/mL) was higher than in osteoarthritic patients (1.33 ± 0.71 ng/mL). In murine primary cultures of tendon cells, chondrocytes, and osteoblasts and in an organotypic model of mouse ankle, we showed that tumor necrosis factor α reversibly diminished Wnt5a expression and secretion, respectively. Wnt5a decreased gene expression of differentiation markers and mineralization in cultured chondrocytes and reduced alkaline phosphatase activity in Achilles tendon enthesis (-14%) and osteocalcin protein levels released by ankle explants (-36%). On the contrary, Wnt5a stimulated ossification markers' expression in cultured osteoblasts and increased the bone volume of the tibial plateau of the cultured explants (+19%). In conclusion, our results suggest that Wnt5a is expressed locally in the joints of patients with SpA. Wnt5a appears more associated with ossification than with inflammation and tends to inhibit mineralization in chondrocytes and enthesis, whereas it seems to favor the ossification process in osteoblasts and bone. Further studies are needed to decipher the opposing effects observed locally in enthesis and systemically in bone in SpA.

Expression of Prostaglandin E2 Enzymes in the Synovium of Arthralgia Patients at Risk of Developing Rheumatoid Arthritis and in Early Arthritis Patients

Objective

Arthralgia may precede the development of synovial inflammation in autoantibody-positive individuals at risk of developing rheumatoid arthritis (RA). A major pathway involved in pain is the prostaglandin (PG) E₂ pathway. We investigated this pathway in the synovium of individuals with RA-specific autoantibodies and in early arthritis patients.

Methods

Nineteen autoantibody-positive individuals (IgM-rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies) with arthralgia (n=15) and/or a positive family history of RA (n=8), who had been prospectively followed for at least 2 years, were included. In addition, we included early arthritis patients (disease-modifying antirheumatic drug naïve) who after 2 years follow up fulfilled classification criteria for RA (n=63), spondyloarthritis (SpA; n=14), or had unclassified arthritis (UA; n=27). In all subjects we assessed pain and performed synovial biopsy sampling by mini-arthroscopy at baseline. Tissue sections were examined by immunohistochemistry to detect and quantify PGE₂ pathway enzymes expression levels (mPGES-1; COX-1 and -2; 15-PGDH).

Results

In both study groups synovial expression of PGE₂ enzymes was not clearly related to pain sensation. Expression levels at baseline were not associated with the development of arthritis after follow up (6 out of 19 autoantibody-positive individuals). However, in early SpA patients the expression levels of mPGES-1 and COX-1 were significantly increased compared to RA and UA patients.

Conclusion

Pain in autoantibody-positive individuals without synovial inflammation who are at risk of developing RA and in early arthritis patients may be regulated by pathways other than the PGE₂ pathway or originate at sites other than the synovium. In contrast, in SpA, the PGE2 pathway may be inherently linked to the pathophysiology/etiology of the disease.

Enthesopathies and enthesitis. Part 1. Etiopathogenesis

The pathologies of tendon and ligament attachments are called enthesopathies. One of its types is enthesitis which is a characteristic sign of peripheral spondyloarthropathy. Clinical diagnosis of enthesitis is based on rather non-specific clinical signs and results of laboratory tests. Imaging examinations are highly promising. Numerous publications prove that enthesitis can be differentiated from other enthesopathic processes in an ultrasound examination or magnetic resonance imaging. However, some reports indicate the lack of histological criteria, specific immunological changes and features in imaging examinations that would allow the clinical diagnosis of enthesitis to be confirmed. The first part of the publication presents theories on the etiopathogenesis of enthesopathies: inflammatory, mechanical, autoimmune, genetic and associated with the synovio-entheseal complex, as well as theories on the formation of enthesophytes: inflammatory, molecular and mechanical. The second part of the paper is a review of the state-of-the-art on the ability of imaging examinations to diagnose enthesitis. It indicates that none of the criteria of inflammation used in imaging medicine is specific for this pathology. As enthesitis may be the only symptom of early spondyloarthropathy (particularly in patients with absent HLA-B27 receptor), the lack of its unambiguous picture in ultrasound and magnetic resonance scans prompts the search for other signs characteristic of this disease and more specific markers in imaging in order to establish diagnosis as early as possible.

Fetuin-A is related to syndesmophytes in patients with ankylosing spondylitis: a case control study

OBJECTIVES

New bone formation is one of the hallmark characteristics of ankylosing spondylitis, which is thereby associated with syndesmophytes. Fetuin-A is a molecule that is abundantly found in calcified tissues and it shows high affinity for calcium phosphate minerals and related compounds. Considering the role of fetuin-A in the regulation of calcified matrix metabolism, we compared the fetuin-A levels in ankylosing spondylitis patients with syndesmophytes with those in patients without syndesmophytes and in healthy controls. We also studied other biomarkers that are thought to be related to syndesmophytes.

METHODS

Ninety-four patients (49 patients without syndesmophytes, 67.3% male, 40.7±8.7 years; 45 patients with syndesmophytes, 71.1% M, 43.9±9.9 years) and 68 healthy controls (44.2±10.6 years and 70.6% male) were included in this study. Syndesmophytes were assessed on the lateral radiographs of the cervical and lumbar spine. The serum levels of fetuin-A, dickkopf-1, sclerostin, IL-6, high-sensitivity C-reactive protein and bone morphogenetic protein-7 were measured with an enzyme-linked immunosorbent assay.

RESULTS

Patients with syndesmophytes had significantly higher levels of fetuin-A compared with patients without syndesmophytes and controls (1.16±0.13, 1.05±0.09 and 1.08±0.13 mg/ml, respectively). However, fetuin-A was not different between the patients without syndesmophytes and controls. Bone morphogenetic protein-7 was significantly lower; dickkopf-1 was significantly higher in patients with ankylosing spondylitis compared with controls. The sclerostin concentrations were not different between the groups. In regression analysis, fetuin-A was an independent, significant predictor of syndesmophytes.

CONCLUSION

Our results suggest that fetuin-A may a role in the pathogenesis of bony proliferation in ankylosing spondylitis.

Role of protein phosphatase magnesium-dependent 1A and anti-protein phosphatase magnesium-dependent 1A autoantibodies in ankylosing spondylitis

OBJECTIVE

Although ankylosing spondylitis (AS) is driven by immune-mediated processes, little is known about the presence and role of autoantibodies in this disease. This study was undertaken to investigate whether autoantibodies occur in and are involved in AS.

METHODS

We performed human protein microarray analysis of sera derived from patients with AS or other autoimmune disorders to identify autoantibodies associated specifically with AS, and identified autoantibody targeting of protein phosphatase magnesium-dependent 1A (PPM1A) in AS. We performed enzyme-linked immunosorbent assay (ELISA) analysis of sera from 2 independent AS cohorts to confirm autoantibody targeting of PPM1A, and to assess associations between levels of anti-PPM1A antibodies and AS disease severity or response to anti-tumor necrosis factor (anti-TNF) therapy (as measured by Bath AS Disease Activity Index [BASDAI] score). Levels of anti-PPM1A antibodies were also evaluated in sera from rats transgenic for HLA-B27 and human β2 -microglobulin. The expression of PPM1A was assessed by immunohistochemistry in synovial tissue samples from patients with AS, rheumatoid arthritis, or osteoarthritis. The role of PPM1A in osteoblast differentiation was investigated by gene knockdown and overexpression.

RESULTS

AS was associated with autoantibody targeting of PPM1A, and levels of anti-PPM1A autoantibodies were significantly higher in patients with more advanced sacroiliitis and correlated positively with BASDAI score after treatment with anti-TNF agents. The levels of anti-PPM1A autoantibodies were also higher in the sera of transgenic rats that are prone to develop spondyloarthritis than in those that are not. PPM1A was expressed in AS synovial tissue, and PPM1A overexpression promoted osteoblast differentiation, whereas PPM1A knockdown suppressed it.

CONCLUSION

Anti-PPM1A autoantibodies are present in AS, and our findings suggest that PPM1A may contribute to the pathogenic bone ankylosis characteristic of AS.

Current concepts in the pathogenesis of traumatic temporomandibular joint ankylosis

Traumatic temporomandibular joint (TMJ) ankylosis can be classified into fibrous, fibro-osseous and bony ankylosis. It is still a huge challenge for oral and maxillofacial surgeons due to the technical difficulty and high incidence of recurrence. The poor outcome of disease may be partially attributed to the limited understanding of its pathogenesis. The purpose of this article was to comprehensively review the literature and summarise results from both human and animal studies related to the genesis of TMJ ankylosis.

Bone morphogenetic protein 6 polymorphisms are associated with radiographic progression in ankylosing spondylitis

BACKGROUND AND OBJECT

Nearly 25 genetic loci associated with susceptibility to ankylosing spondylitis (AS) have been identified by several large studies. However, there have been limited studies to identify the genes associated with radiographic severity of the disease. Thus we investigated which genes involved in bone formation pathways might be associated with radiographic severity in AS.

METHODS

A total of 417 Korean AS patients were classified into two groups based on the radiographic severity as defined by the modified Stoke' Ankylosing Spondylitis Spinal Score (mSASSS) system. Severe AS was defined by the presence of syndesmophytes and/or fusion in the lumbar or cervical spine (n = 195). Mild AS was defined by the absence of any syndesmophyte or fusion (n = 170). A total of 251 single nucleotide polymorphisms (SNPs) within 52 genes related to bone formation were selected and genotyped. Odds ratios (OR) and 95% confidence interval (95% CI) were analysed by multivariate logistic regression controlling for age at onset of symptoms, sex, disease duration, and smoking status as covariates.

RESULTS

We identified new loci of bone morphogenetic protein 6 (BMP6) associated with radiographic severity in patients with AS that passed false discovery rate threshold. Two SNPs in BMP6 were significantly associated with radiologic severity [rs270378 (OR 1.97, p = 6.74 × 10(-4)) and rs1235192 [OR 1.92, p = 1.17 × 10(-3)]) adjusted by covariates.

CONCLUSION

This is the first study to demonstrate that BMP6 is associated with radiographic severity in AS, supporting the role wingless-type like/BMP pathway on radiographic progression in AS.

Systematic review of association between vitamin D levels and susceptibility and disease activity of ankylosing spondylitis

OBJECTIVES

Vitamin D appears to have significant effects on both innate and acquired immunity and deficiency may be associated with both susceptibility and disease severity in some autoimmune conditions. There has been little focus on the potential immunomodulatory role of vitamin D in AS. This study systematically reviews the evidence for an association between vitamin D deficiency and disease susceptibility and severity in AS.

METHODS

A systematic review was conducted using Medline, EMBASE, Web of Science and conference abstracts of the European League Against Rheumatism (2002-13), British Society for Rheumatology (1993-2013) and ACR (2006-13).

RESULTS

Fifteen original articles and five conference abstracts met the criteria for inclusion. All were cross-sectional in design. Seven of 11 studies identified lower concentrations of 25-hydroxyvitamin D (25OHD) in AS patients compared with healthy controls. A significant inverse correlation between 25OHD and disease activity was observed in 5 of 11 studies. The majority of studies that failed to demonstrate significant findings used inappropriate statistical methods.

CONCLUSION

Cross-sectional studies using appropriate statistical analyses have highlighted that AS is associated with lower vitamin D concentrations. Within groups of AS patients there is some evidence that low vitamin D concentrations are associated with higher disease activity. However, there are insufficient published data to support an immunomodulatory role for vitamin D in AS. Further study with a longitudinal design is required to understand whether optimizing vitamin D in AS has potential as a disease-modifying intervention.

A pilot trial on the molecular pathophysiology of traumatic temporomandibular joint bony ankylosis in a sheep model. Part I: Expression of Wnt signaling

OBJECTIVE

To preliminarily investigate the temporal patterns of the endogenous mRNA expression for members of the Wnt signaling and a series of genes regulating bone formation during the development of traumatic temporomandibular joint (TMJ) bony ankylosis in a sheep model.

METHODS

Six sheep were used for the induction of bony ankylosis of TMJ. We performed a condylar fracture, excision of the lateral 2/3 disc and serious injury to the glenoid fossa to induce bony ankylosis on the right TMJ. An isolated condylar fracture was performed on the left side. Two sheep were sacrificed at 1 month, 3 months, and 6 months after surgery, respectively. The specimens from the ankylosed joint and the condylar fracture were harvested for RNA extraction respectively. In this report (Part I), only the bony ankylosed samples were used for analysis of gene expressions. The specimens 1 month postoperatively were taken as the control, and the changes of expression of target genes over time were examined by real-time PCR.

RESULTS

mRNA expression of Wnt1, Wnt2b, Wnt3a, β-catenin, Sfrp1, Lrp6, Lef1, CyclinD1, and Runx2 was up-regulated at 3 and 6 months compared with 1 month. The expression of Wnt5a, Sox9, and Osterix was up-regulated with a peak at 3 months, and then fell back to the basal levels at 6 months. The expression of Ocn began to up-regulate until 6 month postoperatively.

CONCLUSION

Our findings suggested that Wnt signaling was involved in the formation of traumatic TMJ bony ankylosis and thus may be a potential therapeutic target for the treatment of the disease in the future.

Autocrine stimulation of osteoblast activity by Wnt5a in response to TNF-α in human mesenchymal stem cells

Although anti-tumor necrosis factor (TNF)-α treatments efficiently block inflammation in ankylosing spondylitis (AS), they are inefficient to prevent excessive bone formation. In AS, ossification seems more prone to develop in sites where inflammation has resolved following anti-TNF therapy, suggesting that TNF-α indirectly stimulates ossification. In this context, our objectives were to determine and compare the involvement of Wnt proteins, which are potent growth factors of bone formation, in the effects of TNF-α on osteoblast function. In human mesenchymal stem cells (MSCs), TNF-α significantly increased the levels of Wnt10b and Wnt5a. Associated with this effect, TNF-α stimulated tissue-non specific alkaline phosphatase (TNAP) and mineralization. This effect was mimicked by activation of the canonical β-catenin pathway with either anti-Dkk1 antibodies, lithium chloride (LiCl) or SB216763. TNF-α reduced, and activation of β-catenin had little effect on expression of osteocalcin, a late marker of osteoblast differentiation. Surprisingly, TNF-α failed to stabilize β-catenin and Dkk1 did not inhibit TNF-α effects. In fact, Dkk1 expression was also enhanced in response to TNF-α, perhaps explaining why canonical signaling by Wnt10b was not activated by TNF-α. However, we found that Wnt5a also stimulated TNAP in MSCs cultured in osteogenic conditions, and increased the levels of inflammatory markers such as COX-2. Interestingly, treatment with anti-Wnt5a antibodies reduced endogenous TNAP expression and activity. Collectively, these data suggest that increased levels of Dkk1 may blunt the autocrine effects of Wnt10b, but not that of Wnt5a, acting through non-canonical signaling. Thus, Wnt5a may be potentially involved in the effects of inflammation on bone formation.

Baseline radiographic damage, elevated acute-phase reactant levels, and cigarette smoking status predict spinal radiographic progression in early axial spondylarthritis

OBJECTIVE

To assess prospectively the rates and to explore predictors of spinal radiographic progression over 2 years in a cohort of patients with early axial spondylarthritis (SpA).

METHODS

Two hundred ten patients with axial SpA from the German Spondyloarthritis Inception Cohort were selected for this analysis based on the availability of radiographs at baseline and after 2 years of followup. Spinal radiographs were scored by 2 trained readers in a blinded, randomly selected order according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). Spinal radiographic progression was defined as worsening of the mean mSASSS by ≥2 units over 2 years.

RESULTS

Among the patients with axial SpA, 14.3% showed spinal radiographic progression after 2 years (20% of those with AS and 7.4% of those with nonradiographic axial SpA). The following parameters were independently associated with spinal radiographic progression: presence of syndesmophytes at baseline (odds ratio [OR] 6.29, P < 0.001), elevated levels of markers of systemic inflammation (for the erythrocyte sedimentation rate, OR 4.04, P = 0.001; for C-reactive protein level time-averaged over 2 years, OR 3.81, P = 0.001), and cigarette smoking (OR 2.75, P = 0.012). These associations were confirmed by multivariate logistic regression analysis. No clear association with spinal radiographic progression was observed for HLA-B27 status, sex, age, disease duration, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, presence of peripheral arthritis, enthesitis, psoriasis, treatment with nonsteroidal antiinflammatory drugs, or treatment with disease-modifying antirheumatic drugs at baseline.

CONCLUSION

The presence of radiographic damage at baseline (syndesmophytes), elevated levels of acute-phase reactants, and cigarette smoking were all independently associated with spinal radiographic progression in patients with early axial SpA.