A review of the pathogenesis of ankylosing spondylitis

Angiogenesis-related immune response may be the prelude to the syndesmophyte formation in Ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a chronic autoimmune arthritis that mainly affects spine joints. To date, the pathogenesis of AS remains unclear, although immune cells and innate immune response cytokines have been suggested to be crucial players.

METHODS

By adopting a single-cell RNA sequencing approach in the AS cynomolgus model, we profiled and characterized PBMC proportions along disease progression.

RESULTS

Here, our primary focus was on the activation of an immune cascade-initiating lymphocyte subtype known as CD4+CXCR5+ T follicular helper (Tfh) cells. These Tfhs demonstrated a localized residence in AS bone lesion as an ectopic lymphoid structure. Moreover, Tfhs would serve as an upstream initiator for a pro-angiogenic cascade. Then, an expansion in CD14+ monocytes and DC cells subsets resulted in enhanced expression of angiogenesis genes in these AS cynomolgus monkeys. With a confirmed higher abundance of TNF-α accompanying H-type vascular invasion in the osteophytic region, pronounced expansion of Tfhs at such lesion site signaling for monocytes and DCs intrusion is considered as the prelude to the characteristic angiogenic bony outgrowth in AS known as syndesmophytes.

CONCLUSIONS

We explored the intimate relationship between local inflammation and bone formation in AS from the perspective of nascent vascularisation. Hence, our study lays the foundation for elucidating a unified AS pathogenesis through the immune-angiogenesis-osteogenesis axis.

Aryl hydrocarbon receptor gene expression in ankylosing spondylitis and its correlation with interleukin-17, RAR-related orphan receptor gamma t expression, and disease activity indices

Objectives

Considering the role of T helper (Th)17 cells in the pathogenesis of ankylosing spondylitis (AS), the aim of this study was to determine the correlation between aryl hydrocarbon receptor (AHR) gene expression and the expression of Th17-related genes including interleukin (IL)-17 and RAR-related orphan receptor gamma t (RORγt) transcription factor.

Patients and methods

Thirty patients with AS (26 males, 4 females; mean age: 36.1±8.1 years) and 30 age- and sex-matched healthy individuals (26 males, 4 females; mean age: 36.2±14.6 years) were recruited for the case-control study between June 2021 and January 2022. Ribonucleic acid (RNA) was extracted from peripheral blood cells and expression levels of AHR, IL-17, RORγt, and AHR repressor (AHRR) genes were evaluated using real-time polymerase chain reaction technique. The serum level of IL-17 was evaluated with enzyme-linked immunosorbent assay.

Results

The results showed a nonsignificant elevation of AHR, IL-17, and RORγt gene expression in the patient group compared to the control. There was a direct correlation between AHR gene expression and IL-17 and RORγt genes and a negative correlation between AHR and AHRR expression. Moreover, AHR gene expression showed a weak correlation with disease activity indices, including Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Metrology Index, Bath Ankylosing Spondylitis Global Score, and Ankylosing Spondylitis Quality of Life. Moreover, the serum level of IL-17 was higher in AS patients compared to the healthy group (p=0.02).

Conclusion

Upregulated expression of the AHR gene in ankylosing spondylitis and its correlation with IL-17 and ROR-γ t gene expression suggests that it could be a potential diagnostic and therapeutic target for AS.

Molecular mechanisms of AMPK/YAP/NLRP3 signaling pathway affecting the occurrence and development of ankylosing spondylitis

BACKGROUND

Investigate the AMPK (protein kinase AMP-activated catalytic subunit alpha 1)/YAP (Yes1 associated transcriptional regulator)/NLRP3 (NLR family pyrin domain containing 3) signaling pathway's role in ankylosing spondylitis (AS) development using public database analysis, in vitro and in vivo experiments.

METHODS

Retrieve AS dataset, analyze differential gene expression in R, conduct functional enrichment analysis, collect 30 AS patient and 30 normal control samples, and construct a mouse model. ELISA, IP, and knockdown experiments were performed to detect expression changes.

RESULTS

NLRP3 was identified as a significant AS-related gene. Caspase-1, IL-1β, IL-17A, IL-18, IL-23, YAP, and NLRP3 were upregulated in AS patients. Overexpressing AMPK inhibited YAP's blockade on NLRP3 ubiquitination, reducing ossification in fibroblasts. Inhibiting AMPK exacerbated AS symptoms in AS mice.

CONCLUSION

AMPK may suppress YAP expression, leading to NLRP3 inflammasome inhibition and AS alleviation.

Analysis of the outcome of bi-vertebral transpedicular wedge osteotomy for correcting severe kyphotic deformity in ankylosing spondylitis

To study the outcomes of bi-vertebral transpedicular wedge osteotomy in correcting severe kyphotic deformity in ankylosing spondylitis (AS). This retrospective study focused on all the patients who underwent thoracic and lumbar bi-vertebra transpedicular wedge osteotomy with pedicle screw internal fixation to treat their severe thoracolumbar kyphotic deformity of AS in our hospital from January 2014 to January 2020. The perioperative and operative data of each patient were collected and analyzed. A total of 21 male AS patients with severe kyphotic deformity were studied with a mean age of 42.2 ± 9.2 years. Intraoperatively, the mean operating time is 5.8 ± 1.6 hour with a mean blood loss of 725.5 ± 140.6 mL. The average postoperative correction of kyphosis reached 60.8o at 1 week after the surgery, which is significantly improved from preoperative presentation (P < .05), and stayed no significant change over the time during longer period of follow-ups (12-24 months) with the overall correction rate of 72.2%. Moreover, the postoperative changes in thoracic kyphosis (TK) angle, thoracolumbar kyphosis (TLK) angle, lumbar lordosis (LL) angle, maxilla-brow angle, as well as C2SVA and C7SVA sagittal balance were also significant, all of which enabled the patients to walk in upright position and sleep in the supine position with the improvements in other clinical symptoms. Bi-vertebral transpedicular wedge osteotomy of thoracic and lumbar vertebrae is a safe and effective method to restore the physiological curvature of the sagittal position of the spine and correct severe ankylosing deformity.

New genomic insights into the conformation of Lipizzan horses

Conformation traits are important selection criteria in equine breeding, as they describe the exterior aspects of the horse (height, joint angles, shape). However, the genetic architecture of conformation is not well understood, as data of these traits mainly consist of subjective evaluation scores. Here, we performed genome-wide association studies on two-dimensional shape data of Lipizzan horses. Based on this data, we identified significant quantitative trait loci (QTL) associated with cresty neck on equine chromosome (ECA)16 within the MAGI1 gene, and with type, hereby differentiating heavy from light horses on ECA5 within the POU2F1 gene. Both genes were previously described to affect growth, muscling and fatty deposits in sheep, cattle and pigs. Furthermore, we pin-pointed another suggestive QTL on ECA21, near the PTGER4 gene, associated with human ankylosing spondylitis, for shape differences in the back and pelvis (roach back vs sway back). Further differences in the shape of the back and abdomen were suggestively associated with the RYR1 gene, involved in core muscle weakness in humans. Therefore, we demonstrated that horse shape space data enhance the genomic investigations of horse conformation.

Prevalence and complication of COVID-19 in patients with ankylosing spondylitis (AS) and its relationship with TNF-a inhibitors

INTRODUCTION

Ankylosing spondylitis (AS) is a condition that is treated with nonsteroidal anti-inflammatory drugs and biological drugs such as anti tumor necrosis factor alpha (TNF-α). This study examined the prevalence of COVID-19 among individuals with AS and compare it between those receiving and not receiving TNF-α inhibitors.

METHODS

A cross-sectional study was conducted at the rheumatology clinic of Imam Khomeini Hospital in Tehran, Iran. The study included patients with AS who sought treatment at the clinic. Demographic information, laboratory and radiographic findings, and disease activity were recorded through interviews and examinations using a questionnaire.

RESULTS

A total of 40 patients were studied over the course of 1 year. Among them, 31 patients were administered anti-TNF-α drugs, with 15 patients (48.3%) receiving subcutaneous Altebrel (Etanercept), 3 patients (9.6%) receiving intravenous Infliximab, and 13 patients (41.9%) receiving subcutaneous Cinnora (Adalimumab). Of the total, 7 patients (17.5%) tested positive for COVID-19, 1 of whom was confirmed through both CT scan and polymerase chain reaction (PCR) testing, while the remaining 6 patients were confirmed only through PCR testing. All patients tested positive for COVID-19 were male, and 6 of them had received Altebrel. Among the 9 AS patients who did not receive TNF inhibitors, 1 patient contracted SARS-CoV-2. The clinical symptoms experienced by these patients were mild, and hospitalization was not required. However, 1 patient who had insulin-dependent type 1 diabetes and was receiving Infliximab required hospitalization. This patient exhibited more severe COVID-19 symptoms, including high fever, pulmonary involvement, dyspnea, and decreased oxygen saturation. No cases of COVID-19 were reported in the Cinnora treatment group. The use of any of the drugs did not demonstrate a significant relationship with the occurrence of COVID-19 in patients.

CONCLUSIONS

The use of the TNF-α inhibitors in patients with AS, may be associated with reduced hospitalization and death rate in COVID-19 cases.

Overexpression of Neurogenin 1 Negatively Regulates Osteoclast and Osteoblast Differentiation

Neurogenin 1 (Ngn1) belongs to the basic helix–loop–helix (bHLH) transcription factor family and plays important roles in specifying neuronal differentiation. The present study aimed to determine whether forced Ngn1 expression contributes to bone homeostasis. Ngn1 inhibited the p300/CREB-binding protein-associated factor (PCAF)-induced acetylation of nuclear factor of activated T cells 1 (NFATc1) and runt-related transcription factor 2 (Runx2) through binding to PCAF, which led to the inhibition of osteoclast and osteoblast differentiation, respectively. In addition, Ngn1 overexpression inhibited the TNF-α- and IL-17A-mediated enhancement of osteoclast differentiation and IL-17A-induced osteoblast differentiation. These findings indicate that Ngn1 can serve as a novel therapeutic agent for treating ankylosing spondylitis with abnormally increased bone formation and resorption.

Integrative approach combining Ayurveda, counselling, Yoga and meditation with conventional management of Ankylosing Spondylitis - A case report

Lifelong medications are required for symptomatic relief in Ankylosing Spondylitis (AS). We report the potential of an integrative approach in reducing dependence on steroids and pain medications in chronic AS. A 59-year-old HLA-B27 positive male patient suffering from AS for 40 years sought Ayurvedic treatment for relapse of pain, stiffness, fatigue, intermittent constipation and disturbed sleep. Ayurvedic diagnosis was Amavata (a clinical condition characterised by joint inflammation) The patient was managed as outpatient for eleven days and hospitalised for thirty three days. Internal medicines and external therapies with diet modification, lifestyle adjustments, counselling, Yoga and IAM Technique (Integrated Amrita Meditation Technique ) were administered during the hospital stay. At yearly follow up, C-Reactive Protein was reduced to 15.7 mg/L from the baseline value of 37.5 mg/L, and ESR from 103 mm/h to 8 mm/h indicating reduction in inflammation. The dose of NSAID and DMARD (Disease Modifying Antirheumatic Drug) could be reduced from once in twenty-four hours to once in eighty-four hours and steroids from twice daily to once in a week. There was significant reduction in pain and stiffness. Integration of Ayurveda and Yoga with conventional treatment can reduce drug dependence and improve quality of life in AS.

Extra-Intestinal Manifestations of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is associated with extra-intestinal manifestations (EIMs) that tend to parallel intestinal activity and have a debilitating effect on the quality of life. EIMs primarily affect the joints, skin, and eyes with less frequent involvement of the liver, kidney, and pancreas. This article reviews the prevalence of musculoskeletal, dermatological, ocular, and other manifestations in IBD and their coalition with underlying intestinal inflammation. EIMs occurring independently of intestinal activity are managed by targeted therapies, categorical regimens, and specific treatments. On the other hand, EIMs paralleling the bowel activity are carefully monitored while the IBD is brought under control. Since the etiology of the disease is responsible for the development of the EIMs, the research scrutinizes the identified pathogenic mechanisms that tend to involve genetic susceptibility, aberrant self-recognition, and autoantibodies directed against organ-specific antigens shared by intestinal and extra-intestinal organs. This article also provides an overview of the epidemiology, clinical features, diagnostic modalities, and management of the EIMs associated with IBD.

Altered kynurenine pathway metabolism in patients with ankylosing spondylitis

BACKGROUND

Various studies reported that increased proinflammatory cytokines in patients with ankylosing spondylitis (AS). Proinflammatory cytokines can affect the expression of various kynurenine pathway enzymes and therefore lead to metabolic changes that can affect the inflammatory response and immunity. Our aim was to measure serum levels of kynurenine pathway metabolites in patients with AS.

METHODS

The study included 85 patients with AS and 50 healthy volunteers. Serum tryptophan, kynurenine, kynurenic acid, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, quinolinic acid concentrations were measured with tandem mass spectrometry. In addition, participants were divided into four groups according to the treatment regimen: TNF-α inhibitor group, conventional therapy group, control group and newly diagnosed AS group. These groups were compared in terms of kynurenine pathways metabolites, interleukin 6 (IL-6), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels.

RESULTS

Serum tryptophan, kynurenic acid, 3-hydroxykynurenine levels were significantly decreased (p < 0.05) in both AS groups compared to the control group, while the levels of kynurenine, quinolinic acid, CRP, ESR, and IL-6 were higher (p < 0.05). The Kynurenine/Tryptophan ratio and CRP levels of the conventional therapy and anti-TNF therapy group were significantly lower than the newly diagnosed AS patients (p < 0.05).

CONCLUSION

As a result of our study, we found that altered kynurenine pathway metabolism in patients with AS. Conventional therapy and anti-TNF-α therapy are effective in reducing the Kynurenine/Tryptophan ratio and CRP levels, although the effect of both treatments on other metabolites appears to be limited.

Osteoimmunological insights into the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS.

Patients with ankylosing spondylitis suffering from AO Type B3 traumatic thoracolumbar fractures are associated with increased frailty and morbidity when compared with patients with diffuse idiopathic skeletal hyperostosis

Background

AO Type B3 hyperextension thoracolumbar fractures are the commonest fracture subtype in ankylosing spinal disorders. Although often considered together in spinal fractures, ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are distinct spondyloarthropathies with different pathophysiology. Few studies have compared the two entities in the setting of traumatic thoracolumbar fractures. The authors compare demographic metrics, injury profile, clinical and radiographical outcomes between patients with AS and DISH in patients suffering from AO Type B3 traumatic thoracolumbar fractures.

Methods

From January 2008 to December 2018, a retrospective analysis of consecutive surgically-managed patients with AO Type B3 fractures was performed. Demographic metrics, co-morbidity [Charlson-comorbidity index, modified frailty index (mFI), etc.], injury profile (level of injury, mechanism of injury, etc.), clinical (postoperative complication, etc.) and radiographical variables were collected. Differences between patients with AS and DISH were compared.

Results

Fourteen patients were identified. All patients had AS (n=6) or DISH (n=8). The mean age was 72.8±10.2 years and 78.6% of patients were neurologically intact at presentation. Medical and/or surgical complications occurred in 10 of 14 (71.4%) patients. As compared to patients with DISH, patients with AS were more likely to have low falls as the injury mechanism [odds ratio (OR): 35.0, P=0.026], have higher mFI (OR: 30.6, P=0.015), and experience a higher number of postoperative complications per patient (AS: 1.8/patient vs. DISH: 0.5/patient, P=0.024).

Conclusions

In the setting of AO Type B3 fractures, patients with AS are more frail and have higher in-hospital morbidity compared to patients with DISH. Despite both pathologies being ankylosing in nature, further studies are required to fully understand the clinical differences between the two entities to enable clinicians to apply a more targeted and nuanced approach in managing fractures in ankylosing spinal disorders.

Advances in nanomedicine for the treatment of ankylosing spondylitis

Ankylosing spondylitis (AS) is a complex disease characterized by inflammation and ankylosis primarily at the cartilage–bone interface. The disease is more common in young males and risk factors include both genetic and environmental. While the pathogenesis of AS is not completely understood, it is thought to be an immune-mediated disease involving inflammatory cellular infiltrates, and human leukocyte antigen-B27. Currently, there is no specific diagnostic technique available for this disease; therefore conventional diagnostic approaches such as clinical symptoms, laboratory tests and imaging techniques are used. There are various review papers that have been published on conventional treatment approaches, and in this review work, we focus on the more promising nanomedicine-based treatment modalities to move this field forward.

Serum Interleukin-23/17 Levels in Ankylosing Spondylitis Patients Treated with Nonsteroidal Anti-Inflammatory Drugs: A Prospective Cohort Study

Etiopathogenesis of ankylosing spondylitis (AS), a major subtype of a group of chronic inflammatory diseases known as spondyloarthropathies, is not clearly understood yet. In this study, we aimed to investigate the interleukin 23 (IL-23)/interleukin-17 (IL-17) pathway, which is a new cytokine pathway in inflammatory diseases. We evaluated serum IL-17 and IL-23 levels after 1-year follow-up in AS patients using only nonsteroidal anti inflammatory drugs (at need or continue). Forty-four AS patients and 40 healthy controls were included in the study. Clinical evaluations of disease activity were performed. Serum tumor necrosis factor-α (TNF-α), IL-6, IL-17, and IL-23 levels were evaluated. IL-17 and IL-23 levels of the patient group at baseline and 12 months were lower than the control group. There was no significant difference between the baseline and 12th month evaluations of the patient group. TNF-α levels were similar in all groups (in the baseline and 12th month of the patient group and in the control group). Although our results are in contrast to the literature findings, the IL-23/IL-17 pathway is a newly discovered pathway, and there may still be unknowns. New studies involving larger patient groups are needed for the factors affecting serum IL-23/IL-17 levels in patients with AS. We also think that it will be useful to make more comprehensive and long-term studies about which patients will respond well to IL-23/IL-17 blockade.

Targeting inflammatory pathways in axial spondyloarthritis

The triggers and pathogenesis of axial spondyloarthritis (axSpA) are not yet completely understood. However, therapeutic agents targeting tumor necrosis factor-α and interleukin-17 inflammatory pathways have proven successful in suppressing many of the clinical symptoms and signs of axSpA, giving us an indication of which pathways are responsible for initiating and maintaining the inflammation. The mechanisms that eventuate in syndesmophytes and ankyloses are less clear. This review addresses these two critical pathways of inflammation, discussing their nature and these factors that may activate or enhance the pathways in patients with axSpA. In addition, genetic and other markers important to the inflammatory pathways implicated in axSpA are explored, and prognostic biomarkers are discussed. Treatment options available for the management of axSpA and their associated targets are highlighted.

Effect of food intake and ambient air pollution exposure on ankylosing spondylitis disease activity

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by axial arthritis. The genetic-environmental factors seem to be involved in the pathogenesis of the disease and the disease debilitates patients during the most productive stages of their lives. The aim of this study was to examine the relationships between two environmental factors, diet and air pollution with disease activity and functional impairment in AS.

METHODS

A case-control study was carried out. Thirty patients with AS and 30 age and sex-matched healthy controls were included. Disease scores including BASMI, BASDAI, BASFI, and BASG were calculated by means of the international Ankylosing Spondylitis Assessment working group consensus recommendations. The food intake was evaluated by semi-quantitative food frequency questionnaire (147 items FFQ). Level of air pollution indices, PM10 and PM2.5 information was obtained from the Tehran air quality control network.

RESULTS

Total energy and fat intake, some vitamins (A, B1, B2, C) and mineral intake (potassium, calcium, iron, phosphorus, magnesium, zinc, copper and selenium) were significantly higher in patients with AS compared to controls. Fat component consumption especially Saturated Fat of Food was moderately correlated with BASFI score. PM2.5 long term exposure was strongly correlated with BASMI, BASFI and BASDAI scores of patients.

CONCLUSION

High-fat diet and long term exposure to air pollution are associated with worse disease outcomes reported in patients with AS. This is an interesting area of investigation in AS pathogenesis and management.

Expansion and activation of monocytic-myeloid-derived suppressor cell via STAT3/arginase-I signaling in patients with ankylosing spondylitis

Background

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease. The dysregulated immune system plays an important role in the pathogenesis of AS. Myeloid-derived suppressor cells (MDSCs) play a key immunoregulatory role in autoimmune arthritis. The aim of this study was to clarify the underlying immunoregulatory mechanism of MDSCs in patients with AS.

Methods

Flow cytometry was used to analyze the phenotype of MDSCs among peripheral blood mononuclear cells (PBMCs) from 46 patients with AS and 46 healthy control subjects. The correlation between MDSC frequency and the disease index of patients with AS was evaluated. A T cell proliferation experiment was used to evaluate the immunosuppressive function of MDSCs.

Results

Polymorphonuclear (PMN) and monocytic (M)-MDSCs were significantly elevated in the PBMCs of patients with AS, when compared with levels in healthy controls. Additionally, M-MDSC levels correlated positively with the clinical index of AS, including the Bath ankylosing spondylitis disease activity index (BASDAI) score, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. M-MDSCs derived from patients with AS suppressed T cell responses, and this effect was dependent on the induction of arginase-I. Furthermore, AS-derived M-MDSCs showed high levels of phosphorylated STAT3. Stattic, a STAT3-specific inhibitor, and STAT3-targeted siRNA abrogated the immunosuppressive function of M-MDSCs. Inhibition of STAT3 signaling also resulted in decreased arginase-I activity.

Conclusions

STAT3/arginase-I signaling plays an important role in both the expansion and activation of M-MDSCs in patients with AS. This information may be beneficial in developing novel therapeutic strategies for preventing AS.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1654-4) contains supplementary material, which is available to authorized users.

Serum IL-6 correlates with axial mobility index (Bath Ankylosing Spondylitis Metrology Index) in Brazilian patients with ankylosing spondylitis

Introduction

Ankylosing spondylitis (AS) is a chronic disease featuring axial changes, peripheral arthritis and systemic involvement. Proinflammatory cytokines are probably involved in AS pathogenesis. The relationship of circulating cytokines with instruments of AS evaluation is an open field of research.

Objective

The aim of this study was to compare serum levels of cytokines in AS patients and healthy controls, and search for correlations of cytokines with indexes of disease activity and quality of life.

Patients and methods

In this cross-sectional study, 32 AS patients and 32 age- and sex- matched controls were evaluated. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Funcional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Ankylosing Spondylitis Disease Activity Score-C reactive protein (ASDAS-CRP), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Ankylosing Spondylitis Quality of Life (ASQol) and Patient Global Assessment score were measured in AS patients. The soluble cytokines IL-6, IL-8, IL-1, IL-10, TNF-α, IL-12p70 and IL-17 were quantified by flow cytometry. IL-23 concentrations were measured using an enzyme-linked immunosorbent assay.

Results

Overall, AS patients were predominantly males (59.4%) and Caucasians (96.9%). Mean age was 46.9±10.7 years. Human leukocyte antigen B27 was present in 70% of cases. Concentrations of IL-6, IL-8, IL-10 and TNF-α were higher in AS cases than controls (p<0.05). Mean concentration of IL-6 correlated with the BASMI, an index of axial mobility (r=0.354, p=0.047). Anti-TNF intake (present in 21 patients, 65.6%) associated with a high BASMI (p=0.042) and lower quality of life as measured using the ASQol scale (p=0.009).

Conclusion

A proinflammatory cytokine profile predominated in AS patients, but interestingly, the IL-10 concentrations were also elevated, pointing to a suppressive control of inflammation. A defined correlation of serum IL-6 with the BASMI suggests a role for this cytokine in axial disease. Anti-TNF users showed more axial activity and lower quality of life.

Axial Spondyloarthritis and Autosomal Dominant Polycystic Kidney Disease in Two Siblings: A Rare Cooccurrence

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequently occurring hereditary kidney disease, and axial spondyloarthritis (SpA) is one of the most frequently occurring rheumatic diseases. Treatment-related decisions for axial SpA may pose a challenge in case of renal involvement. The authors describe two siblings with cooccurrence of these two diseases. The association of these two diseases is not well known. Practitioners should monitor renal function in SpA patients and take treatment-related decisions regarding renal involvement. Antitumor necrosis factor-alpha (anti-TNF-α) agents may be used in case nonsteroidal anti-inflammatory drugs (NSAIDs) cannot be utilized.

Osteotomies in ankylosing spondylitis: where, how many, and how much?

INTRODUCTION

This article presents the current concepts of correction of spinal deformity in ankylosing spondylitis (AS) patients. Untreated AS can be a debilitating disease. In a few patients, disease progression results in severe spinal deformity affecting not only the thoracolumbar, but also the cervical spine. Surgery for correction in AS patients has a long history. With the advent of modern instrumentation, standardization of surgical and anesthesiologic techniques, surgical safety and corrective results could be improved and experiences from lumbar osteotomies could be transferred to the cervical spine.

METHODS

This article presents the current concepts of correction of spinal deformity in AS patients. In particular, questions regarding the localization and number of osteotomies, the optimal surgical target angle as well as planning and prediction of postoperative alignment are discussed.

RESULTS

Insight into recent technical developments, current challenges with correction and geometric analysis of center of rotation (COR) in cervical 3-column osteotomies (3CO) will be presented.

CONCLUSION

The article should encourage readers to improve surgical correction efficacy and provide a better understanding of correction geometry in 3CO for thoracolumbar and cervical spinal deformities.

Screening for key genes and transcription factors in ankylosing spondylitis by RNA-Seq

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis and autoimmune disease, the etiology and pathogenesis of which remain largely unknown. In the present study, blood samples were harvested from patients with AS and from healthy volunteers as a normal control (NC) for RNA-sequencing. Differentially expressed genes (DEGs) in the AS group compared with the NC group were identified, and gene ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were subsequently performed. Protein-protein interaction (PPI) network and AS-specific transcriptional regulatory network construction was performed for the DEGs. A total of 503 DEGs, including 338 upregulated and 165 downregulated DEGs, were identified in patients with AS compared with the NC group. Three upregulated DEGs identified, interferon-induced protein with tetratricopeptide repeats (IFIT)1, IFIT3 and radical S-adenosyl methionine domain containing (RSAD)2, are interferon (IFN)-stimulated genes that serve a role in the IFN signaling pathway. The most significantly enriched GO term was response to other organisms. Osteoclast differentiation was a significantly enriched pathway for eight DEGs [High affinity immunoglobulin gamma Fc receptor (FCGR)1A, FCGR2B, four and a half LIM domains 2, integrin β3, signal transducer and activator of transcription 2 (STAT2), suppressor of cytokine signaling 3 (SOCS3), leukocyte immunoglobulin like receptor (LILR)A4 and LILRA6]. The six hub genes in the PPI network constructed were interferon-stimulated gene 15, heat shock protein β1, microtubule-associated proteins 1A/1B light chain 3A, IFIT1, IFIT3 and SOCS3. POU domain class 2 transcription factor 1 (1-Oct) and ecotropic virus integration site-1 (Evi-1) were identified as two important transcription factors (TFs) in AS according to the AS-specific transcriptional regulatory network constructed. In addition, IFIT1 and IFIT3 were identified as targets of 1-Oct. The results of the present study indicate that osteoclast differentiation, the IFN signaling pathway and genes associated with these two signaling pathways, particularly FCGR2B, STAT2, SOCS3, IFIT1 and IFIT3, may serve a role in AS. In addition, Evi-1 and 1-Oct may be two important TFs associated with AS. These results may provide a basis for elucidating the underlying mechanisms of and developing novel treatments for AS.

Incident osteoarthritis and osteoarthritis-related joint replacement surgery in patients with ankylosing spondylitis: A secondary cohort analysis of a nationwide, population-based health claims database

BACKGROUND

Ankylosing spondylitis (AS) might be associated with an increased risk of secondary osteoarthritis. However, there is a lack of studies assessing its impact on osteoarthritis-related surgery. The aim of this secondary cohort study was to investigate the risk of symptomatic osteoarthritis and osteoarthritis-related surgery, including total hip replacement surgery (THRS) and total knee replacement surgery (TKRS) in patients with AS.

METHODS

Using the Taiwan's National Health Insurance Research Database, we identified 3,462 patients with AS between 2000 and 2012. A comparison cohort was assembled consisting of five patients without AS, based on frequency matching for sex, 10-year age interval, and index year, for each patient with AS. Both groups were followed until diagnosis of the study outcomes or the end of the follow-up period.

RESULTS

Male patients with AS exhibited a significantly higher incidence of osteoarthritis (adjusted incidence rate ratio [IRR] 1.43; P < 0.001), THRS (adjusted IRR 12.59; P < 0.001), and TKRS (adjusted IRR 1.89; P = 0.036). Moreover, analyses stratified by age group (20-39 years versus 40-80 years) indicated a high IRR (adjusted IRR 27.66; P <0.001) for THRS among younger patients with AS.

CONCLUSIONS

Male patients with AS had a significant higher risk of developing osteoarthritis, and receiving THRS and TKRS. Young patients with AS also showed a significant higher risk of receiving THRS.

Effect of metformin on ossification and inflammation of fibroblasts in ankylosing spondylitis: An in vitro study

Ankylosing spondylitis (AS) is an autoimmune disease characterized by fibroblasts ossification. However, effective drug therapy for AS is lacking. As an antidiabetic drug, metformin has demonstrated an antiosteogenic effect on osteoblasts in vitro. And it is also a kind of specific agonists for adenosine 5'-monophosphate activated protein kinase (AMPK), which is blocked in the process of AS. Given the role in antiosteogenesis and AMPK activating, metformin was investigated of its effect on fibroblasts harvested from capsular ligament of patients with femoral neck fracture and AS. Osteogenic specific makers (Alp, Bglap, Runx2, Bmp2, and Col1) in fibroblasts administered with metformin (20 μg/mL) were detected by ALP staining, alizarin red staining, qPCR, and Western blotting after 7 and 14 days of culture. Inflammation genes (il1-β and il6) and pathway (Pi3k, Akt, and Ampk) associated markers were also evaluated. Our results showed that osteogenic specific markers were greatly downregulated and ossification was effectively inhibited in AS fibroblasts after addition of metformin. Levels of inflammation markers were also decreased by metformin. Thus, metformin exerts potent effect on suppression of ossification and inflammation in AS fibroblasts via the activation of Pi3k/Akt and AMPK pathways, which may be developed as a potential agent for treatment of AS.

Ankylosing spondylitis: beyond genome-wide association studies

PURPOSE OF REVIEW

This article discusses genomic investigations in ankylosing spondylitis (AS) beyond genome-wide association (GWA) studies, but prior to this, genetic variants achieving genome-wide significance will be summarized highlighting key pathways contributing to disease pathogenesis.

RECENT FINDINGS

Evidence suggests that disease pathogenesis is attributed to a complex interplay of genetic, environmental and immunological factors. GWA studies have greatly enhanced our understanding of AS pathogenesis by illuminating distinct immunomodulatory pathways affecting innate and acquired immunity, most notably the interleukin-23/interleukin-17 pathway. However, despite the wealth of new information gleaned from such studies, a fraction of the heritability (24.4%) has been explained. This review will focus on investigations beyond GWA studies including copy number variants, gene expression profiling, including microRNA (miRNA), epigenetics, rare variants and gene-gene interactions.

SUMMARY

To address the 'missing heritability' and advance beyond GWA studies, a concerted effort involving rethinking of study design and implementation of newer technologies will be required. The coming of age of next-generation sequencing and advancements in epigenetic and miRNA technologies, combined with familial-focused investigations using well-characterized cohorts, is likely to reveal some of the hidden genomic mysteries associated with AS.

Higher risk of incident ankylosing spondylitis in patients with uveitis: a secondary cohort analysis of a nationwide, population-based health claims database

OBJECTIVES

Ankylosing spondylitis (AS) is a progressive, systemic, inflammatory autoimmune disease that typically affects young adults. Uveitis is a common extra-articular manifestation of AS. Nevertheless, the magnitude of the risk of AS among patients with uveitis is not clear. The aim of this secondary retrospective cohort study was to investigate the risk of incident AS in patients with uveitis using data from a nationwide, population-based health claims research database.

METHOD

Using Taiwan's National Health Insurance Research Database, we identified 6637 patients with uveitis between 2000 and 2012. A comparison cohort was assembled, which consisted of five patients without uveitis, based on frequency matching for gender, 10 year age interval, and index year, for each patient with uveitis. Both groups were followed until diagnosis of AS or the end of the follow-up period. A Poisson regression model was used to calculate the incidence rate ratio for AS between the uveitis cohort and the comparison cohort.

RESULTS

Patients with uveitis exhibited a significantly higher incidence of AS than the comparison cohort (adjusted incidence rate ratio = 2.57, p < 0.001). Subgroup analysis with stratification by the interval between the diagnosis of uveitis and AS indicated that the adjusted incidence rates were significantly higher in the uveitis cohort with an interval of up to 7.9 years.

CONCLUSION

A significant increased risk in AS among patients with uveitis was observed, with a time lag of up to 7.9 years between the diagnosis of uveitis and subsequent diagnosis of AS.

Genetic association between TAP1 and TAP2 polymorphisms and ankylosing spondylitis: a systematic review and meta-analysis

OBJECTIVES

Ankylosing spondylitis (AS) is a chronic inflammatory joint disease. The transporter associated with antigen processing (TAP) has been identified to play an important role in immune response as well as the HLA-associated diseases. The aim of our meta-analysis was to investigate the contribution of TAP (TAP1 and TAP2) polymorphisms to the risk of AS.

METHODS

Meta-analyses were performed between 2 polymorphisms in TAP1 (TAP1-333, -637) and 3 polymorphisms in TAP2 (TAP2-379, -565, and -665) and AS.

RESULTS

The meta-analyses were involved with 6 studies with 415 cases and 659 controls. Significant association was found between TAP1-333Val, TAP1-637Gly, and TAP2-565Thr and AS compared with combined control group (TAP1-333Val: p = 0.009, OR = 1.40, 95% CI 1.09-1.80; TAP1-637Gly: p = 0.002, OR = 1.48, 95% CI 1.15-1.91; p = 0.03, OR = 1.38, 95% CI 1.04-1.84). Subgroup analysis shown that significant association was only found in AS when compared with HLA-B27-negative controls (TAP1-333Val: p = 0.004, OR = 1.53, 95% CI 1.14-2.06; TAP1-637Gly: p = 0.004, OR = 1.52, 95% CI 1.15-2.02; p = 0.02, OR = 1.56, 95% CI 1.09-2.24), but not in AS when compared with HLA-B27-positive controls (p > 0.05). Moreover, no significant associations were found between haplotypes in TAP1 and TAP2 in both the combined and the subgroup analyses (p > 0.05).

CONCLUSIONS

TAP1-333Val, TAP1-637Gly, and TAP2-565Thr were likely to be associated with AS.

Role of HLA-B27 in the pathogenesis of ankylosing spondylitis (Review)

The study of ankylosing spondylitis (AS) has made significant progress over the last decade. Genome-wide association studies have identified and further substantiated the role of susceptibility genes outside the major histocompatibility complex locus. However, human leukocyte antigen (HLA)-B27 has been suggested to be important in the pathogenesis of AS, contributing to ~20.1% of AS heritability. The current review will present the classical and non-classical forms of HLA-B27, as well as their pathogenic roles, and further discuss the hypotheses regarding the potential pathogenesis of AS. In addition, the association between the pathogenic role of HLA-B27 and inflammatory indexes, including the interleukin-23/−17 axis will be investigated to provide novel insights into the pathogenesis of AS. The aim of the present review is to provide an update of the current research into the pathogenesis of AS, and provide a comprehensive description of the pathogenic role of HLA-B27 in AS.

Chronic bowel inflammation and inflammatory joint disease: Pathophysiology

Bowel inflammation is closely linked to chronic joint inflammation. Research reported in the 1980s demonstrated bowel inflammation with gross and microscopic pathological features identical to those of Crohn's disease in over 60% of patients with spondyloarthritis (SpA). Numerous prospective studies have evidenced joint involvement in patients with chronic inflammatory bowel disease (IBD) and bowel inflammation in patients with SpA. Nevertheless, the interactions of joint disease and chronic bowel inflammation remain incompletely elucidated. Two main hypotheses have been suggested to explain potential links between inflammation of the mucosal immune system and peripheral arthritis: one identifies gut bacteria as potentially implicated in the development of joint inflammation and the other involves the recruitment of gut lymphocytes or activated macrophages to the joints. Pathophysiological investigations have established that HLA-B27 is a pivotal pathogenic factor. Here, we review current data on links between chronic bowel inflammation and inflammatory joint disease.

Network Meta-Analysis and Cost Per Responder of Tumor Necrosis Factor-α and Interleukin Inhibitors in the Treatment of Active Ankylosing Spondylitis

INTRODUCTION

Biologic therapies have improved the clinical management of ankylosing spondylitis (AS). Few head-to-head studies have directly compared the efficacy of these agents. This study was conducted to indirectly compare the efficacy of biologic agents for treatment of active AS.

METHODS

A targeted literature review was conducted to identify randomized clinical trials for adalimumab, infliximab, golimumab, certolizumab pegol, etanercept, and secukinumab for the treatment of active AS. The clinical efficacy was evaluated using ASAS20 and ASAS40 and synthesized via a Bayesian network meta-analysis. Number needed to treat (NNT) was calculated as the reciprocal of incremental response rate of each biologic versus placebo. Comparisons were also made in terms of cost per incremental ASAS20 or ASAS40 responder.

RESULTS

Fifteen studies were identified, which included ASAS20 and/or ASAS40 response rates at Week 12 to Week 16. Patients with AS treated with infliximab had the lowest NNT for ASAS20 of 2.3, followed by those treated with adalimumab (2.8) and etanercept (2.9). Adalimumab had the lowest 12-week cost per additional ASAS20 responder at $26,888, followed by infliximab at $28,175 and golimumab at $28,199. Patients treated with infliximab also had the lowest NNT for ASAS40 (2.6), followed by those treated with adalimumab (2.8) and secukinumab (3.5). Adalimumab had the lowest cost per additional ASAS40 responder at $26,898, followed by infliximab at $32,508 and etanercept at $34,406.

CONCLUSION

Infliximab had the lowest NNT to achieve an additional ASAS20/40 response, and adalimumab had the lowest cost per ASAS20/40 responder among biologic agents for the treatment of active AS.

FUNDING

AbbVie.

Serum HMGB1 Serves as a Novel Laboratory Indicator Reflecting Disease Activity and Treatment Response in Ankylosing Spondylitis Patients

Objective. High mobility group box 1 (HMGB1) is a late inflammatory factor participating in the pathogenesis of various autoimmune and inflammatory diseases. In the current study, we analyzed the association between serum levels of HMGB1 and clinical features of AS patients before and during treatment. Methods. Serum HMGB1 was detected in 147 AS patients and 61 healthy controls using ELISA. We evaluated the association between HMGB1 and extra-articular manifestations as well as disease severity indices. Among these AS patients, 41 patients received close follow-up at 1, 3, and 6 months after treatment. This group comprised 25 patients treated with anti-TNF-α biologics and 16 patients receiving oral NSAIDs plus sulfasalazine. Results. The serum HMGB1 of AS patients was significantly higher than in healthy controls and positively correlated with BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, ESR, and CRP, but not with HLA-B27, anterior uveitis, and recurrent diarrhea. There was no significant difference between patients with radiographic damage of hip joints and those without. We observed that serum HMGB1 paralleled disease activity after treatment. Conclusion. Serum level of HMGB1 is higher in AS patients, and to some extent, HMGB1 can reflect the activity of AS and be used as a laboratory indicator to reflect the therapeutic response.

Inhibition of Complement Retards Ankylosing Spondylitis Progression

Ankylosing spondylitis (AS) is a chronic axial spondyloarthritis (SpA) resulting in back pain and progressive spinal ankyloses. Currently, there are no effective therapeutics targeting AS largely due to elusive pathogenesis mechanisms, even as potential candidates such as HLA-B27 autoantigen have been identified. Herein, we employed a proteoglycan (PG)-induced AS mouse model together with clinical specimens, and found that the complement system was substantially activated in the spinal bone marrow, accompanied by a remarkable proportion alteration of neutrophils and macrophage in bone marrow and spleen, and by the significant increase of TGF-β1 in serum. The combined treatment with a bacteria-derived complement inhibitor Efb-C (C-terminal of extracellular fibrinogen-binding protein of Staphylococcus aureus) remarkably retarded the progression of mouse AS by reducing osteoblast differentiation. Furthermore, we demonstrated that two important modulators involved in AS disease, TGF-β1 and RANKL, were elevated upon in vitro complement attack in osteoblast and/or osteoclast cells. These findings further unravel that complement activation is closely related with the pathogenesis of AS, and suggest that complement inhibition may hold great potential for AS therapy.

Risk factors of uveitis in ankylosing spondylitis: An observational study

BACKGROUND

Uveitis is the most common extra-articular manifestation in patients with ankylosing spondylitis (AS). The prevalence and characteristics of uveitis in AS have been studied in previous literatures, whereas its associated risk factors have not been clarified. Therefore, this study analyzed the risk factors of uveitis in patients with AS.

METHODS

A total of 390 patients with AS who fulfilled the modified New York criteria were enrolled from January to December in 2015. The history of uveitis was accepted only if diagnosed by ophthalmologists. The medical records of the patients were retrospectively reviewed and associated information was collected, such as disease duration, HLA-B27, and the number of peripheral arthritis. Hip-joint lesion was identified by imaging examination. Meanwhile, biochemical examinations were performed to determine the patient's physical function.

RESULTS

Of 390 patients with AS (80.5% male, mean age 33.3 years), 38 (9.7%) had experienced 1 or more episodes of uveitis. The incidence rate for hip-joint lesion was obviously higher for patients with uveitis than the nonuveitis group (44.7% vs 22.2%; P < 0.01). The number of peripheral arthritis was also larger for the uveitis group than nonuveitis group (2.18 ± 0.23 vs 0.55 ± 0.04; P < 0.001). Meanwhile, patients with uveitis had a significantly higher level of antistreptolysin O (ASO) and circulating immune complex (CIC) than those without (P < 0.05 and P < 0.0001, respectively). However, there were no significant differences in disease duration, HLA-B27, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) between the 2 groups. Binary logistic regression results showed that ASO (OR = 12.2, 95% CI:3.6-41.3, P < 0.01) and the number of peripheral arthritis (OR = 4.1, 95%CI:2.6-6.3, P < 0.01) are significantly associated with uveitis in AS.

CONCLUSTION

This study provides some evidence that hip-joint lesion, the number of peripheral arthritis, ASO, and CIC may be associated with higher rates of uveitis in AS. The results of this comprehensive analysis suggest that the possible occurrence of uveitis in AS should not be neglected if the patients have those concomitant risk factors.

[Acupuncture Therapy versus Disease-modifying Antirheumatic Drugs for the Treatment of Ankylosing Spondylitis--a Meta-analysis]

BACKGROUND

We conducted a meta-analysis evaluating the efficacy and safety of acupuncture compared to disease-modifying antirheumatic drugs in patients with ankylosing spondylitis.

METHODS

Four databases including Pubmed, EMBASE, Cochrane library, and ISI Web of Science were searched in December 2014, taking also the reference section into account. Randomized controlled trials that aimed to assess the efficacy of acupuncture therapy were identified. The inclusion criteria for the outcome measurements were the clinical effect, ESR, occipital wall test, chest expansion, CRP and finger ground distance. Finally, six studies met these inclusion criteria. Two reviewers screened each article independently and were blinded to the findings of each other.

RESULTS

We analyzed data from 6 RCTs involving 541 participants. Acupuncture therapy could further improve the clinical effect (OR = 3.01; 95% CI, 1.48-6.13; P = 0.002) and reduce ESR level (SMD = -0.77; 95% CI, -1.46 to -0.08; P = 0.03) compared to DMARDs; a combination of acupuncture and DMARDs could further improve clinical effect (OR = 3.20, 95% CI, 1.36-7.54; P = 0.008), occipital-wall distance (SMD = -0.84; 95% CI, -1.37 to -0.31; P = 0.002), chest expansion (SMD = 0.38; 95% CI, 0.16-0.60; P = 0.0009), and finger-ground distance (SMD = -0.48; 95% CI, -0.87 to -0.09; P = 0.02) as compared to DMARDs treatment alone.

CONCLUSIONS

Our findings support that acupuncture therapy could be an option to relieve symptoms associated with AS. These results should be interpreted cautiously due to the generally poor methodological qualities of the included trials.

Death Receptor 3 (TNFRSF25) Increases Mineral Apposition by Osteoblasts and Region Specific New Bone Formation in the Axial Skeleton of Male DBA/1 Mice

Objectives. Genome wide association studies identified TNFSF member TNF-like protein 1A (TL1A, TNFSF15) as a potential modulator of ankylosing spondylitis (AS). TL1A is the only confirmed TNFSF ligand of death receptor 3 (DR3, TNFRSF25); however, its role in disease pathology is not characterised. We evaluated DR3's role in controlling osteoblast- (OB-) dependent bone formation in vitro and in vivo. Methods. Osteoprogenitor cells and OB were cultured from male DR3-deficient (DR3(ko)) and wild-type (DR3(wt)) DBA/1 mice. DR3 and RANKL expression were tested by flow cytometry. Alkaline phosphatase and mineralization were quantified. Osteopontin, osteoprotegerin, and pro MMP-9 were measured by ELISA. A fluorescent probe (BoneTag) was used to measure in vivo mineralization in 10-month-old mice. Results. DR3 was expressed on osteoprogenitors and OB from DR3(wt) mice. Alkaline phosphatase, osteopontin, and mineral apposition were significantly elevated in DR3(wt) cultures. Levels of RANKL were comparable whilst osteoprotegerin was significantly increased in DR3(wt) cultures. In vivo incorporation of BoneTag was significantly lower in the thoracic vertebrae of 10-month-old DR3(ko) mice. Conclusions. These data identify new roles for DR3 in regulating OB-dependent bone mineral apposition. They potentially begin to explain the atypical pattern of new bone formation observed in the axial skeleton of grouped, aging DBA/1 mice.

The risk of ischemic stroke in major rheumatic disorders

Rheumatic disorders (RD) are a range of conditions associated with inflammation of joints and connective tissue. They can manifest beyond the musculoskeletal system. Recent focus has been placed on the association of ischemic stroke with these conditions. Traditional vascular risk factors seem to be more prevalent in patients with certain types of RD than in the general population, but these factors do not fully explain the enhanced vascular risk in this population. Four major RD will be discussed in terms of their relationship with ischemic stroke: rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, and psoriatic arthritis.

The genetic basis of ankylosing spondylitis: new insights into disease pathogenesis

Ankylosing spondylitis (AS) is a complex disease involving multiple risk factors, both genetic and environmental. AS patients are predominantly young men, and the disease is characterized by inflammation and ankylosis, mainly at the cartilage–bone interface and enthesis. HLA-B27 has been known to be the major AS-susceptibility gene for more than 40 years. Despite advances made in the past few years, progress in the search for non-human leukocyte antigen susceptibility genes has been hampered by the heterogeneity of the disease. Compared to other complex diseases, such as inflammatory bowel disease (IBD), fewer susceptibility loci have been identified in AS. Furthermore, non-major histocompatibility-complex susceptibility loci discovered, such as ERAP1 and IL23R, are likely contributors to joint inflammation. Identification and confirmation of functional variants remains a significant challenge of investigations involving genome-wide association studies (GWAS). It remains unclear why none of the AS-susceptibility genes identified in GWAS appear to be directly involved in the ankylosing process. Numerous reviews have recently been published on the genetics of AS. Therefore, aside from a brief summary of what AS GWAS has successfully achieved thus far, this review will focus on directions that could address unanswered questions raised by GWAS.

Thoracolumbar fracture dislocation sustained during childbirth in a patient with ankylosing spondylitis

BACKGROUND CONTEXT

Ankylosing spondylitis (AS) is a major subtype of the spondyloarthropathies. Uncoupling of bone formation and resorption along with ectopic ossification of paraspinal soft-tissue structures alters the biomechanics of the spine and leads to an increased susceptibility to fracture.

PURPOSE

To report on a thoracolumbar fracture dislocation sustained in a 33-year-old Gravida 2/Para 2 woman, which occurred during labor. Although there are several reports in the literature of thoracolumbar fracture dislocations sustained in patients with AS, none have been reported during childbirth.

STUDY DESIGN

Case report.

CONCLUSIONS

An elevated suspicion for injury should be maintained when patients with AS present with back or neck pain even without a history of significant trauma.

Aberrant axial mineralization precedes spinal ankylosis: a molecular imaging study in ank/ank mice

INTRODUCTION

The diagnosis of ankylosing spondylitis is made from a combination of clinical features and the presence of radiographic evidence that may be detected only after many years of inflammatory back pain. It is not uncommon to have a diagnosis confirmed 5 to 10 years after the initial onset of symptoms. Development of a more-sensitive molecular imaging technology to detect structural changes in the joints would lead to earlier diagnosis and quantitative tracking of ankylosis progression. Progressive ankylosis (ank/ank) mice have a loss of function in the Ank gene, which codes for a regulator of PPi transport. In this study, we used these ank/ank mutant mice to assess a noninvasive, quantitative measure of joint ankylosis with near-infrared (NIR) molecular imaging in vivo.

METHODS

Three age groups (8, 12, and 18 weeks) of ank/ank (15 mice) and wild-type littermates (12 +/+ mice) were assessed histologically and radiographically. Before imaging, OsteoSense 750 (bisphosphonate pamidronate) was injected i.v. Whole-body images were analyzed by using the multispectral Maestro imaging system.

RESULTS

OsteoSense 750 signals in the paw joints were higher in ank/ank mice in all three age groups compared with controls. In the spine, significantly higher OsteoSense 750 signals were detected early, in 8-week-old ank/ank mice compared with controls, although minimal radiographic differences were noted at this time point. The molecular imaging changes in the ank/ank spine (8 weeks) were supported by histologic changes, including calcium apatite crystals at the edge of the vertebral bodies and new syndesmophyte formation.

CONCLUSIONS

Changes in joint pathology of ank/ank mice, as evaluated by histologic and radiographic means, are qualitative, but only semiquantitative. In contrast, molecular imaging provides a quantitative assessment. Ankylosis in ank/ank mice developed simultaneously in distal and axial joints, contrary to the previous notion that it is a centripetal process. NIR imaging might be feasible for early disease diagnosis and for monitoring disease progression in ankylosing spondylitis.

HLA-B35 upregulates endothelin-1 and downregulates endothelial nitric oxide synthase via endoplasmic reticulum stress response in endothelial cells

The presence of the HLA-B35 allele has emerged as an important risk factor for the development of isolated pulmonary hypertension in patients with scleroderma, however the mechanisms underlying this association have not been fully elucidated. The goal of our study was to determine the molecular mechanisms that mediate the biological effects of HLA-B35 in endothelial cells (ECs). Our data demonstrate that HLA-B35 expression at physiological levels via adenoviral vector resulted in significantly increased endothelin-1 (ET-1) and a significantly decreased endothelial NO synthase (eNOS), mRNA, and protein levels. Furthermore, HLA-B35 greatly upregulated expression of chaperones, including heat shock proteins (HSPs) HSP70 (HSPA1A and HSPA1B) and HSP40 (DNAJB1 and DNAJB9), suggesting that HLA-B35 induces the endoplasmic reticulum (ER) stress and unfolded protein response in ECs. Examination of selected mediators of the unfolded protein response, including H chain binding protein (BiP; GRP78), C/Ebp homologous protein (CHOP; GADD153), endoplasmic reticulum oxidase, and protein disulfide isomerase has revealed a consistent increase of BiP expression levels. Accordingly, thapsigargin, a known ER stress inducer, stimulated ET-1 mRNA and protein levels in ECs. This study suggests that HLA-B35 could contribute to EC dysfunction via ER stress-mediated induction of ET-1 in patients with pulmonary hypertension.

Hip resurfacing arthroplasty for ankylosing spondylitis

We compared the results of the metal-on-metal hip resurfacing with the ceramic-on-ceramic total hip arthroplasty (THA) in 2 groups. The preoperative and postoperative ranges of motion (ROMs) were recorded. At the latest follow-up, both of the groups make satisfactory clinical and radiographic results. There was no significant difference in Harris hip score of the 2 groups, but the ROM of the hips in hip resurfacing group was significantly wider than THA group (P < .01). Hip resurfacing has better ROM improvement than THA, with the same pain relief. Its high stability and low dislocation rate allow patients to do early function exercises, which is important for ankylosing spondylitis (AS) patients to avoid reankylosis. Hip resurfacing may be a reasonable option for young AS population.

Clinical features and epidemiology of spondyloarthritides associated with inflammatory bowel disease

Inflammation of axial and/or peripheral joints is one of the most frequent extra-intestinal manifestations complicating the clinical course and therapeutic approach in inflammatory bowel diseases (IBD). The frequency of these complications seems to be similar for both diseases, Crohn's disease and ulcerative colitis. Arthritis associated with IBD belongs to the category of spondyloarthropathies. Axial involvement ranges from isolated inflammatory back pain to ankylosing spondylitis, whereas peripheral arthritis is noted in pauciarticular and in polyarticular disease. Asymptomatic radiological involvement of the sacroiliac joints is reported to occur in up to 50% of patients. Other musculoskeletal manifestations such as buttock pain, dactylitis, calcaneal enthesitis, and thoracic pain are frequently underdiagnosed and, consequently, are not treated appropriately. Several diagnostic approaches and criteria have been proposed over the past 40 years in an attempt to correctly classify and diagnose such manifestations. The correct recognition of spondylarthropathies needs an integrated multidisciplinary approach in order to identify common therapeutic strategies, especially in the era of the new biologic therapies.