Inflammatory pathways in spondyloarthritis

Association between syndecan-4 and subclinical atherosclerosis in ankylosing spondylitis

BACKGROUND

Despite advances in the diagnosis and treatment of ankylosing spondylitis (AS), the risk of cardiovascular complications in AS patients is still higher than in the general population. Macrophages are at the intersection of the basic pathogenetic processes of AS and atherosclerosis. Although syndecan-4 (SDC4) mediates a variety of biological processes, the role of SDC4 in macrophage-mediated atherogenesis in AS patients remains unclear. Herein, we aimed to investigate the role of SDC4 in subclinical atherosclerosis in AS patients.

METHODS

Subjects were selected from eligible AS patients and control subjects without a prior history of AS who were referred to the rheumatology outpatient clinics. All participants' past medical records and clinical, and demographic characteristics were scanned. In addition, carotid intima-media thickness (CIMT) measurement and disease activity index measurement were applied to all patients.

RESULTS

According to our data, serum SDC4 level was significantly higher among AS patients compared with the control group (6.7 [1.5-35.0] ng/mL vs 5.1 [0.1-12.5] ng/mL, P < .001). The calculated CIMT was also significantly higher in AS patients than in the control group (0.6 [0.3-0.9] mm vs 0.4 (0.2-0.7), P < .001]. Additionally, serum C-reactive protein level and SDC4 level were independent predictors of AS and strongly associated with CIMT. Linear regression analysis showed that serum SDC4 level was the best predictor of CIMT (P = .004).

CONCLUSION

Our data indicate that serum SDC4 levels provide comprehensive information about the clinical activity of the disease and subclinical atherosclerosis in AS patients.

Structural disease modification in axial spondyloarthritis

"Disease modification" in axial spondyloarthritis (axSpA) seeks to not only alleviate clinical symptoms but also alter the disease's natural course by impeding new bone formation. Recent years have witnessed the effectiveness of treatments, including biologics and nonsteroidal anti-inflammatory drugs, in managing axSpA symptoms. Emerging evidence points toward their potential impact on slowing structural disease progression. This comprehensive review centers on the pivotal role of inhibiting new bone formation in axSpA disease modification. It delves into the significance of imaging techniques for assessing disease progression and explores the disease-modifying properties of available axSpA treatments, encompassing NSAIDs, TNF inhibitors, IL-17 inhibitors, and JAK inhibitors. This article offers valuable insights into the evolving landscape of disease modification strategies in axial spondyloarthritis, highlighting the multifaceted approaches used to attain these objectives.

Distinct immune modulatory roles of regulatory T cells in gut versus joint inflammation in TNF-driven spondyloarthritis

OBJECTIVES

Gut and joint inflammation commonly co-occur in spondyloarthritis (SpA) which strongly restricts therapeutic modalities. The immunobiology underlying differences between gut and joint immune regulation, however, is poorly understood. We therefore assessed the immunoregulatory role of CD4+FOXP3+ regulatory T (Treg) cells in a model of Crohn's-like ileitis and concomitant arthritis.

METHODS

RNA-sequencing and flow cytometry was performed on inflamed gut and joint samples and tissue-derived Tregs from tumour necrosis factor (TNF)∆ARE mice. In situ hybridisation of TNF and its receptors (TNFR) was applied to human SpA gut biopsies. Soluble TNFR (sTNFR) levels were measured in serum of mice and patients with SpA and controls. Treg function was explored by in vitro cocultures and in vivo by conditional Treg depletion.

RESULTS

Chronic TNF exposure induced several TNF superfamily (TNFSF) members (4-1BBL, TWEAK and TRAIL) in synovium and ileum in a site-specific manner. Elevated TNFR2 messenger RNA levels were noted in TNF∆ARE/+ mice leading to increased sTNFR2 release. Likewise, sTNFR2 levels were higher in patients with SpA with gut inflammation and distinct from inflammatory and healthy controls. Tregs accumulated at both gut and joints of TNF∆ARE mice, yet their TNFR2 expression and suppressive function was significantly lower in synovium versus ileum. In line herewith, synovial and intestinal Tregs displayed a distinct transcriptional profile with tissue-restricted TNFSF receptor and p38MAPK gene expression.

CONCLUSIONS

These data point to profound differences in immune-regulation between Crohn's ileitis and peripheral arthritis. Whereas Tregs control ileitis they fail to dampen joint inflammation. Synovial resident Tregs are particularly maladapted to chronic TNF exposure.

A novel signature of interleukins 36α, 37, 38, 39 and 40 in ankylosing spondylitis

The current study examined five cytokines, three belong to interleukin (IL)-1 family (IL-36α, IL-37 and IL-38), one belongs to IL-12 family (IL-39) and one has not been assigned to a family (IL-40), in the serum of 110 male patients with ankylosing spondylitis (AS) and 103 male controls. Studies regarding these cytokines in AS are very limited. Therefore, the significance of IL-36α, IL-37, IL-38, IL-39 and IL-40 as biomarkers of AS was evaluated. Cytokine levels were measured using enzyme-linked immunosorbent assay kits. Results revealed that serum levels (median and interquartile range) of IL-36α (90.7; 53.7-166.2 vs 39.7; 31.3-59.2 pg/mL; probability [p] < 0.001), IL-37 (161.3; 62.8-236.6 vs 58.4; 46.8-80.7 ng/mL; p < 0.001), IL-38 (135.8; 78.2-213.5 vs 65.8; 51.1-87.1 pg/mL; p < 0.001), IL-39 (57.7; 34.1-92.3 vs 29.1; 19.3-58.6 ng/L; p < 0.001) and IL-40 (3.89; 2.99-6.19 vs 2.10; 1.75-2.68 ng/L; p < 0.001) were significantly higher in AS patients than in controls. Besides, they were of value in distinguishing between AS patients and controls as evidenced by the receiver operating characteristic curve analysis: area under the curve = 0.797 (IL-36α), 0.75 (IL-37), 0.797 (IL-38), 0.728 (IL-39) and 0.886 (IL-40). Some of these cytokines were significantly correlated, but no correlation with AS activity was found. In conclusion, the levels of IL-36α, IL-37, IL-38, IL-39 and IL-40 were up-regulated in the serum of AS patients regardless of age, age at disease onset, disease duration, disease activity or HLA-B27.

Increased serum interleukin 22 levels in patients with axial spondyloarthritis

OBJECTIVES

The role of IL-22 in radiographic axial spondyloarthritis is not fully elucidated. Thus, there is a need for new insights into this cytokine in this disease. We aimed to compare interleukin (IL)-22 level between spondyloarthritis, nonspecific-low back pain patients, and pain-free controls, and to evaluate associations between this cytokine and spondyloarthritis characteristics.

METHODS

We conducted a case-control study including 62 patients with radiographic axial spondyloarthritis (G1), 46 with nonspecific low back pain (G2), and 42 healthy volunteers (G3). IL-22 was measured using Enzyme-linked immunosorbent assay. We evaluate disease activity and structural damage of spondyloarthritis.

RESULTS

IL-22 level was higher in G1 than in G2 and G3 (38±40 versus14.42±8.17 versus14.3±18.67 pg/mL, p<0.01). IL-22 discriminated patients in G1 from G2 with a cutoff of 22.28pg/mL (Sensitivity: 62.9%, Specificity: 97.8%, area under the curve (AUC): 0.808). IL-22 cutoff of 19.27pg/mL discriminated patients in G1 from G3 (Sensitivity: 67%, Specificity: 94.3%, AUC: 0.855). No associations were found between IL-22 levels and disease activity and structural damage.

CONCLUSIONS

Our study showed that IL-22 level was higher in radiographic axial spondyloarthritis patients compared to controls. It was also able to differentiate G1 patients from G2 and G3. This finding suggests that the IL-22 pathway showed to play a pathological role in spondyloarthritis.

Association of Serum Interleukin-17 and Interleukin-23 Levels with Disease Activity, Function, Mobility, Enthesitis Index in Patients with Ankylosing Spondylitis

Aim: More and more studies have demonstrated that the interleukin (IL)-23/IL-17 axis is highly associated with immune dysfunction and activated autoimmune inflammation. The purposes of this study were to determine the serum levels of IL-17 and IL-23 in ankylosing spondylitis (AS) patients compared with healthy controls and evaluate these cytokine levels based on disease-related characteristics. Material and Methods: Eighty-six consecutive AS patients and 70 sex and age-matched healthy controls were included in the study. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Ankylosing Spondylitis Disease Activity Score (ASDAS)-erythrocyte sedimentation rate (ESR), ASDAS-C reactive protein, the Bath Ankylosing Spondylitis Functional Index (BASFI), the Spondyloarthritis Research Consortium of Canada (SPARCC) enthesitis index, the Bath Ankylosing Spondylitis Metrology Index (BASMI), the Ankylosing Spondylitis Quality of Life Questionnaire (ASQoL) and Achilles pain VAS scores were recorded. Serum IL-17 and IL-23 levels were examined by enzyme-linked immunosorbent assay. Results: The serum levels of IL-17, IL-23 and CRP as well as ESR values were significantly increased in AS patients compared with controls (1.94 vs. 0.28 pg/mL p ˂ 0.001; 82.9 vs. 44.3 pg/mL p ˂ 0.001; 0.48 vs. 0.30 mg/dL, p=0.001; 12±13.9 vs. 8±6.8 mm/h, p=0.003, respectively). In AS patients, serum IL-17 levels were significantly correlated with the ASDAS-ESR and ASDAS-CRP (r=0.244, p=0.024; r=0.258, p=0.017), but not with ESR, CRP, BASDAI, function, mobility, quality of life, enthesitis index or Achilles pain scores (all p>0.05). Serum IL-23 levels demonstrated a significant correlation with Achilles pain VAS, but not with other disease-related parameters (all p>0.05). Conclusions: AS patients had increased serum IL-17 and IL-23 levels compared with healthy controls, and serum IL-17 levels were associated with disease activity. Our study results support the hypothesis that the IL17/23 pathway plays an important role in the pathogenesis of AS.

The Effects of Crocin on Bone and Cartilage Diseases

Crocin, the main biologically active carotenoid of saffron, generally is derived from the dried trifid stigma of Crocus sativus L. Many studies have demonstrated that crocin has several therapeutic effects on biological systems through its anti-oxidant and anti-inflammatory properties. The wide range of crocin activities is believed to be because of its ability to anchor to many proteins, triggering some cellular pathways responsible for cell proliferation and differentiation. It also has therapeutic potentials in arthritis, osteoarthritis, rheumatoid arthritis, and articular pain probably due to its anti-inflammatory properties. Anti-apoptotic effects, as well as osteoclast inhibition effects of crocin, have suggested it as a natural substance to treat osteoporosis and degenerative disease of bone and cartilage. Different mechanisms underlying crocin effects on bone and cartilage repair have been investigated, but remain to be fully elucidated. The present review aims to undertake current knowledge on the effects of crocin on bone and cartilage degenerative diseases with an emphasis on its proliferative and differentiative properties in mesenchymal stem cells.

An update on the pathogenic role of IL-6 in rheumatic diseases

Interleukin (IL)-6 is a pleiotropic cytokine that is involved in the pathogenesis of various rheumatic diseases. Direct inhibition of the IL-6 pathway by an anti-IL-6 receptor or inhibiting the ligand itself has proved to be efficacious in the treatment of these diseases. Juvenile idiopathic arthritis, adult-onset Still's disease, large vessel vasculitis including giant cell arteritis and Takayasu disease, systemic sclerosis, and polymyalgia rheumatica respond well to IL-6 inhibition as expected. However, no clinically meaningful effect has been observed with regard to IL-6 blockade in ankylosing spondylitis, psoriatic arthritis, and systemic lupus erythematosus. This review discusses the current state of IL-6 targeting approaches in various rheumatic diseases other than rheumatoid arthritis.

A double-blind placebo-controlled randomized trial of oral saffron in the treatment of rheumatoid arthritis

OBJECTIVE

Recently, saffron (Crocus sativus L. from the Iridaceae family) has been characterized by its antioxidant, anti-inflammatory and analgesic effects. This study aimed to evaluate the effect of saffron on disease activity in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

This is a double-blind, placebo-controlled, randomized clinical trial (RCT) performed on 55 newly- diagnosed RA patients without previous treatment, who were randomly divided into intervention (included 28 cases) and control groups (consisted of 27 individuals). Standard therapy including prednisolone, oral methotrexate, folic acid, vitamin D, calcium, and alendronate, was administered similarly in both groups. Patients received a 100 mg saffron pill/day (pure saffron powder) or placebo besides the standard protocol. The placebo had the same shape as the saffron pills. Follow up of DAS28ESR disease activity score was done on the 30th, 45th and 90th day of the study.

RESULTS

There was no difference between the intervention and control groups regarding to the DAS28ESR at the end of the study. However, a significant decrease in DAS28-ESR was observed in each group compared to the first visit (p=0.001). The results also showed no significant difference in the incidence of side effects in both groups.

CONCLUSION

In summary, patients who received pure saffron pills (100 mg/day) in addition to standard therapy did not have a significant difference in improvement of disease activity from the patients on standard therapy.

Similarities and Differences Between Juvenile and Adult Spondyloarthropathies

Spondyloarthritis (SpA) encompasses a broad spectrum of conditions occurring from childhood to middle age. Key features of SpA include axial and peripheral arthritis, enthesitis, extra-articular manifestations, and a strong association with HLA-B27. These features are common across the ages but there are important differences between juvenile and adult onset disease. Juvenile SpA predominantly affects the peripheral joints and the incidence of axial arthritis increases with age. Enthesitis is important in early disease. This review article highlights the similarities and differences between juvenile and adult SpA including classification, pathogenesis, clinical features, imaging, therapeutic strategies, and disease outcomes. In addition, the impact of the biological transition from childhood to adulthood is explored including the importance of musculoskeletal and immunological maturation. We discuss how the changes associated with adolescence may be important in explaining age-related differences in the clinical phenotype between juvenile and adult SpA and their implications for the treatment of juvenile SpA.

Haptoglobin and Its Related Protein, Zonulin-What Is Their Role in Spondyloarthropathy?

Haptoglobin (Hp) is an acute phase protein which supports the immune response and protects tissues from free radicals. Its concentration correlates with disease activity in spondyloarthropathies (SpAs). The Hp polymorphism determines the functional differences between Hp1 and Hp2 protein products. The role of the Hp polymorphism has been demonstrated in many diseases. In particular, the Hp 2-2 phenotype has been associated with the unfavorable course of some inflammatory and autoimmune disorders. Its potential role in modulating the immune system in SpA is still unknown. This article contains pathophysiological considerations on the potential relationship between Hp, its polymorphism and SpA.

Impact of secukinumab on patient-reported outcomes in moderate to severe plaque psoriasis: a review of clinical studies

Introduction: Perception of illness varies among individuals and psoriasis of the same severity can be perceived in different ways by patients, making it essential to evaluate quality of life (QoL) since it can provide information on the impact of the disease on the patient's overall well-being. The use of patient-reported outcomes in clinical trials provides the ability to integrate objective clinical assessment with the patient's perception of their own state of health. Areas covered: The introduction of anti-IL17 agents in clinical practice has given patients the possibility to achieve a PASI90 response (almost clear skin) or even higher (complete clear skin) in the majority of patients. There is accumulating evidence in support of PASI90 response as the new standard goal for therapy based on its greater correlation with health-related QoL. The present review summarizes current knowledge of the effects of secukinumab on the QoL of patients with psoriasis using patient-reported outcome measures. Expert Opinion: Secukinumab, the first approved drug of this new class, has fully reached a new therapeutic paradigm not only in terms of clinical efficacy, but also in terms of patient satisfaction and self-rated health.

The relationship of ischemia-modified albumin levels to disease activity scores and HLA-B27 in patients with ankylosing spondylitis

OBJECTIVE:

Recent studies have implicated increased oxidative stress in the pathogenesis of Ankylosing spondylitis (AS). Ischemia-modified albumin (IMA), an altered form of albumin, increases oxidative stress. This study aimed to investigate the relationship between IMA levels and other indicators of disease severity in AS.

METHODS:

This study included 63 AS patients and 48 healthy controls. Patients were examined for serum lipid profile, C-reactive protein (CRP), complete blood count, Bath Ankylosing Spondylitis Disease Activity Index, human leukocyte antigen (HLA) B27, and treatment regimen. They were categorized based on disease activity, HLA-B27 status, and the drug treatment and compared for IMA levels.

RESULTS:

The patients had significantly higher IMA levels than controls (p=0.020); among patients, the levels were higher in those with active disease (p=0.001) and positively correlated with the CRP levels. No significant difference was found between the IMA levels of the patients with different HLA-B27 status or treatment method.

CONCLUSION:

The IMA levels were higher in patients than controls and further increased in patients with active AS. IMA was associated with disease activity and can be used as an inflammatory marker in AS. More comprehensive future studies with a larger sample size may help understand the relationship in greater detail.

Depression in patients with spondyloarthritis: prevalence, incidence, risk factors, mechanisms and management

Depression is a major neuropsychiatric disorder common in patients with rheumatological conditions including spondyloarthritis (SpA). It is associated with higher disease activity, functional impairment, poor treatment response and quality of life in patients with musculoskeletal disorders. Using ankylosing spondylitis (AS) and psoriatic arthritis (PsA) as examples, we have reviewed the evidence regarding the burden, risk factors, potential mechanisms and clinical management of depression in spondyloarthritis. The prevalence of depression is higher in patients with AS and PsA compared with the general population, with evidence of moderate/severe depression in about 15% of patients with AS or PsA. Mild depression is even more common and estimated to be present in about 40% of patients with AS. In addition to conventional risk factors such as stressful life events and socioeconomic deprivation, increased risk of depression in SpA may be associated with disease-related factors, such as disease activity, poor quality of life, fatigue, and sleep disturbances. Emerging evidence implicates inflammation in the aetiology of depression, which could also be a shared mechanism for depression and chronic inflammatory conditions such as AS and PsA. It is imperative for clinicians to actively assess and treat depression in SpA, as this could improve treatment adherence, quality of life, and overall long-term clinical and occupational outcomes. The use of validated tools can aid recognition and management of depression in rheumatology clinics. Management of depression in SpA, especially when to refer to specialist mental health services, are discussed.

Ectopic bone formation and systemic bone loss in a transmembrane TNF-driven model of human spondyloarthritis

BACKGROUND

The transmembrane-TNF transgenic mouse, TgA86, has been shown to develop spontaneously peripheral arthritis with signs of axial involvement. To assess similarity to human spondyloarthritis, we performed detailed characterization of the axial, peripheral, and comorbid pathologies of this model.

METHODS

TgA86 bone pathologies were assessed at different ages using CT imaging of the spine, tail vertebrae, and hind limbs and characterized in detail by histopathological and immunohistochemical analysis. Cardiac function was examined by echocardiography and electrocardiography and bone structural parameters by μCT analysis. The response of TgA86 mice to either early or late anti-TNF treatment was evaluated clinically, histopathologically, and by μCT analysis.

RESULTS

TgA86 mice developed with 100% penetrance spontaneous axial and peripheral pathology which progressed with time and manifested as reduced body weight and body length, kyphosis, tail bendings, as well as swollen and distorted hind joints. Whole-body CT analysis at advanced ages revealed bone erosions of sacral and caudal vertebrae as well as of sacroiliac joints and hind limbs and, also, new ectopic bone formation and eventually vertebral fusion. The pathology of these mice highly resembled that of SpA patients, as it evolved through an early inflammatory phase, evident as enthesitis and synovitis in the affected joints, characterized by mesenchymal cell accumulation, and neutrophilic infiltration. Subsequently, regression of inflammation was accompanied by ectopic bone formation, leading to ankylosis. In addition, both systemic bone loss and comorbid heart valve pathology were evident. Importantly, early anti-TNF treatment, similar to clinical treatment protocols, significantly reduced the inflammatory phase of both the axial and peripheral pathology of TgA86 mice.

CONCLUSIONS

The TgA86 mice develop a spontaneous peripheral and axial biphasic pathology accompanied by comorbid heart valvular dysfunction and osteoporosis, overall reproducing the progression of pathognomonic features of human spondyloarthritis. Therefore, the TgA86 mouse represents a valuable model for deciphering the role of transmembrane TNF in the pathogenic mechanisms of spondyloarthritis and for assessing the efficacy of human therapeutics targeting different phases of the disease.

Punicalagin Exerts Protective Effects against Ankylosing Spondylitis by Regulating NF-κB-TH17/JAK2/STAT3 Signaling and Oxidative Stress

Background

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by sacroiliitis and spinal rigidity of the axial joints. The role of oxidative stress and increased proinflammatory cytokines is well documented in AS pathogenesis. Punicalagin (2,3-hexahydroxydiphenoyl-gallagyl-D-glucose), an ellagitannin widely present in pomegranates, is found to exhibit potent anti-inflammatory, antiproliferative, and antioxidative effects. The present study was undertaken to investigate the effects of punicalagin in a rodent model of AS.

Methods

BALB/c mice induced spondylitis were sacrificed 24 h after the last injection of proteoglycan extract. Histological scoring was done to assess the degree of the disease. The expression of JAK2/STAT3 proteins and proteins of the nuclear factor-κB (NF-κB) pathway was determined by immunoblotting. Serum levels of inflammatory mediators—TNF-α, IL-1β, IL-6, IL-17A, and IL-23—were assessed. Levels of lipid peroxidation and reactive oxygen species (ROS) were quantified. Antioxidant status as a measure of activities of antioxidant enzymes—catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)—was determined.

Results

Punicalagin effectively improved antioxidant status and decreased lipid peroxidation, ROS production, and serum levels of inflammatory mediators. NF-κB pathway and JAK2/STAT3 signaling were significantly (p < 0.05) downregulated. Punicalagin effectively regulated the production of cytokines by the Th17 cells and the IL-17A/IL-23 axis.

Conclusion

The observations suggest that punicalagin exerts a protective role in AS via reducing oxidative stress and regulating NF-κB/TH17/JAK2/STAT3 signal. Punicalagin thus could be explored further as a potent candidate compound in the treatment of AS.

HLA-B27-mediated activation of TNAP phosphatase promotes pathogenic syndesmophyte formation in ankylosing spondylitis

Ankylosing spondylitis (AS) is a type of axial inflammation. Over time, some patients develop spinal ankylosis and permanent disability; however, current treatment strategies cannot arrest syndesmophyte formation completely. Here, we used mesenchymal stem cells (MSCs) from AS patients (AS MSCs) within the enthesis involved in spinal ankylosis to delineate that the HLA-B27-mediated spliced X-box-binding protein 1 (sXBP1)/retinoic acid receptor-β (RARB)/tissue-nonspecific alkaline phosphatase (TNAP) axis accelerated the mineralization of AS MSCs, which was independent of Runt-related transcription factor 2 (Runx2). An animal model mimicking AS pathological bony appositions was established by implantation of AS MSCs into the lumbar spine of NOD-SCID mice. We found that TNAP inhibitors, including levamisole and pamidronate, inhibited AS MSC mineralization in vitro and blocked bony appositions in vivo. Furthermore, we demonstrated that the serum bone-specific TNAP (BAP) level was a potential prognostic biomarker to predict AS patients with a high risk for radiographic progression. Our study highlights the importance of the HLA-B27-mediated activation of the sXBP1/RARB/TNAP axis in AS syndesmophyte pathogenesis and provides a new strategy for the diagnosis and prevention of radiographic progression of AS.

Efficacy of guselkumab in a subpopulation with pustulotic arthro-osteitis through week 52: an exploratory analysis of a phase 3, randomized, double-blind, placebo-controlled study in Japanese patients with palmoplantar pustulosis

Background

Previous studies of guselkumab have demonstrated clinical benefits in patients with plaque‐type psoriasis, generalized pustular psoriasis, erythrodermic psoriasis and palmoplantar pustulosis (PPP).

Objective

The aim of this exploratory analysis of a double‐blind, multicenter, placebo‐controlled, phase 3 study in Japanese patients with PPP was to evaluate the efficacy of guselkumab in the subset of patients with pustulotic arthro‐osteitis (PAO).

Methods

Patients were randomized to receive guselkumab 100 or 200 mg at weeks 0, 4, 12 and every 8 weeks, or placebo with cross‐over to guselkumab 100 or 200 mg at week 16 (placebo group). Efficacy endpoints were changes from baseline in magnetic resonance imaging (MRI) score, EuroQOL‐5 dimensions (EQ‐5D) index score, EQ‐5D pain/discomfort dimension score and C‐reactive protein (CRP, mg/L) level in all PAO patients through week 52. Data from both guselkumab groups were combined and presented as results for a single overall guselkumab group.

Results

Among 159 patients with PPP, 66 with PAO were randomized across treatment groups. For patients with MRI data for all regions assessed, the proportion of patients in the guselkumab group with PAO characterized as severe decreased from 23.8% (10/42) at baseline to 5.4% (2/42) at week 52. The mean (SD) change from baseline at week 52 in EQ‐5D index score was 0.20 (0.17) among PPP patients with PAO and 0.15 (0.17) among those without PAO in the guselkumab group. Among all PAO patients, the proportions with an EQ‐5D pain/discomfort dimension score of no or slight pain/discomfort in the guselkumab group increased from baseline to week 52 [33.3% (7/21) vs. 87.5% (35/40)]. The mean (SD) CRP levels decreased in all PAO patients in the guselkumab group at week 52 compared to baseline [−1.71 (8.16) mg/L].

Conclusion

Guselkumab treatment showed beneficial outcomes for PAO signs and symptoms in Japanese patients with PPP.

Aberrant distribution and function of plasmacytoid dendritic cells in patients with ankylosing spondylitis are associated with unfolded protein response

Although human leucocyte antigen (HLA)-B27 is strongly associated with ankylosing spondylitis (AS), the association of unfolded protein response (UPR) induced by HLA-B27 misfolding in AS remains controversial. Since dendritic cells (DCs) are crucial in induction of AS in HLA-B27-transgenic rats, and plasmacytoid DCs (pDCs) belong to one type of DCs, we here aim to study the relevance of pDCs and UPR in AS. Peripheral pDCs were isolated from 27 HLA-B27(+) AS patients and 37 controls. The bone marrow (BM) and synovium of inflamed hips from AS patients and controls were obtained. We found a significantly higher frequency of pDCs in the peripheral blood, BM, or inflamed synovium of hips, which is associated with the enhanced expression of pDC trafficking molecules, CCR6 and CCL20 in the synovium of AS patients. Functional analysis further revealed that several inflammatory cytokines, including TNFα, IL-6, and IL-23, secreted by pDCs were significantly increased in AS patients as compared with those in controls. Remarkably, protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway in UPR was up-regulated in pDCs of AS patients. Notably, PERK inhibitor treatment significantly inhibited the enhanced cytokine production by pDCs of AS patients. Further, the extent of PERK activation was significantly associated with the increased disease severity of AS patients. Our data uncover the aberrant distribution and function of pDCs in AS patients. The up-regulated PERK pathway in UPR of pDCs not only contributes to enhanced cytokine production of pDCs, but also is associated with increased disease activity of AS patients.

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.

Therapies in ankylosing spondylitis-from clinical trials to clinical practice

Until recently, the therapeutic options for patients suffering from active AS comprised NSAIDs and TNF inhibitor therapy. Although these are effective in a significant proportion of patients, not all patients respond and some are intolerant to these therapies. Therefore, there is a clear unmet treatment need in AS patients. This article reviews the evidence for targets currently being studied in AS. This includes the IL-12/23 inhibitor ustekinumab, the pan-Janus kinase inhibitor tofacitinib and the anti-IL-17A antibody secukinumab.

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.

Histologic evidence that mast cells contribute to local tissue inflammation in peripheral spondyloarthritis by regulating interleukin-17A content

Objectives

Synovial mast cells contain IL-17A, a key driver of tissue inflammation in SpA. A recent in vitro study showed that tissue-derived mast cells can capture and release exogenous IL-17A. The present study aimed to investigate if this mechanism could contribute to tissue inflammation in SpA.

Methods

Potential activation of mast cells by IL-17A was assessed by gene expression analysis of the Laboratory of Allergic Diseases 2 (LAD2) mast cell line. The presence of IL-17A-positive mast cells was assessed by immunohistochemistry in synovial tissue obtained before and after secukinumab treatment, as well as in skin and gut tissues from SpA-related conditions.

Results

IL-17A did not induce a pro-inflammatory response in human LAD2 mast cells according to the canonical IL-17A signalling pathway. In SpA synovial tissue, the percentage of IL-17A-positive mast cells increased upon treatment with secukinumab. IL-17A-positive mast cells were also readily detectable in non-inflamed barrier tissues such as skin and gut. In non-inflamed dermis and gut submucosa, IL-17A-positive mast cells are the most prevalent IL-17A-positive cells in situ. Compared with non-inflamed tissues, both total mast cells and IL-17A-positive mast cells were increased in psoriatic skin dermis and in submucosa from inflammatory bowel disease gut. In contrast, the proportion of IL-17A-positive mast cells was strikingly lower in the inflamed compared with non-inflamed gut lamina propria.

Conclusion

IL-17A-positive mast cells are present across SpA target tissues and correlate inversely with inflammation, indicating that their IL-17A content can be regulated. Tissue-resident mast cells may act as IL-17A-loaded sentinel cells, which release IL-17A to amplify tissue inflammation.

The antifibrotic drug pirfenidone inhibits spondyloarthritis fibroblast-like synoviocytes and osteoblasts in vitro

Background

The pathogenesis of spondyloarthritis (SpA) involves both inflammation and new bone formation in the spine. In line with this, the disease has been characterized as both inflammatory and fibrotic. The current treatment dampens inflammation while new bone formation can progress. Therefore, there is an unmet therapeutic need for the treatment of new bone formation in SpA. Fibrosis is mediated by myofibroblasts and new bone formation is the result of increased osteoblast mineralization and decreased osteoclast resorption. Here, we evaluate the potential effect of the newly approved anti-fibrotic agent pirfenidone (PFD) on fibrosis and new bone formation in cell culture models of SpA.

Methods

Fibroblast-like synoviocytes (FLSs) were isolated from SpA patients (n = 6) while the osteoblast cell line Saos-2 was purchased. The cells were cultured with PFD at 0.25 0.5, or 1.0 mg/ml. The proliferation of FLSs was analyzed with light microscopy and flow cytometry. The differentiation and activation of FLSs was assessed with flow cytometry, a membrane-based antibody array and enzyme-linked immunosorbant assays. The mineralization capacity of osteoblasts was studied with an assay measuring deposition of hydroxyapatite.

Results

PFD reduced the Ki67 expression 7.1-fold in untreated FLSs (p = 0.001) and 11.0-fold in FLSs stimulated with transforming growth factor beta (TGFβ), tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) (p = 0.022). There were no statistically significant changes in membrane expression of alpha smooth muscle actin (αSMA), intercellular adhesion molecule 1 (ICAM-1), or human leukocyte antigen DR (HLA-DR). In supernatants from FLSs stimulated with TGFβ, TNFα, and IFNγ, PFD decreased the secretion of 3 of 12 proteins more than 2-fold in the membrane-based antibody array. The changes in secretion of monocyte chemoattractant protein 1 (MCP-1) and chitinase-3-like protein 1 (CHI3L1, YKL-40) were validated with ELISA. PFD decreased the secretion of both Dickkopf-related protein 1 (DKK1) (p = 0.006) and osteoprotegerin (OPG) (p = 0.02) by SpA FLSs stimulated with TGFβ, TNFα, and IFNγ. Finally, PFD inhibited the deposition of hydroxyapatite by osteoblasts in a dose-dependent manner (p = 0.0001).

Conclusions

PFD inhibited SpA FLS proliferation and function and osteoblast mineralization in vitro. This encourages studies of the in vivo effect of PFD in SpA.

Silencing SOCS3 Markedly Deteriorates Spondyloarthritis in Mice Induced by Minicircle DNA Expressing IL23

Objective: Despite extensive studies, the precise mechanism underlying spondyloarthritis, especially ankylosing spondylitis, remains elusive. This study aimed to develop an ideal animal model for an insight into mechanism of spondyloarthritis and functional relevance of SOCS3 in spondyloarthritis.

Methods: Since SOCS3 is a major regulator of IL23-STAT3 signaling, we generated SOCS3 knockdown transgenic (TG) mice for development of an animal model of spondyloarthritis. A hydrodynamic delivery method was employed to deliver minicircle DNA expressing IL23 (mc-IL23) into wild-type (WT) and the TG mice. Knockdown/overexpression systems mediated by lentivirus and retrovirus were used to determine whether SOCS3 regulated osteoblast differentiation.

Results: Forced expression of IL23 induced severe joint destruction and extensive bone loss in SOCS3 knockdown TG mice, while this treatment only caused moderate symptoms in WT mice. Furthermore, severe spondyloarthritis was found in IL23-injected TG mice as compared to mild disease observed in WT controls under same condition. Moreover, our studies showed that IL23 promoted osteoblast differentiation via activation of STAT3 pathway and disruption of SOCS3 expression greatly increased phosphorylation of STAT3. In addition, silencing SOCS3 resulted in enhanced osteoblast differentiation through activation of Smad1/5/9 signaling, as evidenced by elevated phosphorylation level of Smad1/5/9. Experiments further demonstrated that SOCS3 interacted with Smad1 and thus suppressed the BMP2-Smad signaling.

Conclusions: The results reveal that SOCS3 is involved in IL23-induced spondyloarthritis and acts as a key regulator of osteoblast differentiation, and suggest that SOCS3 knockdown TG mice may be an ideal animal model for further studies of spondyloarthritis.

Translating GWAS in rheumatic disease: approaches to establishing mechanism and function for genetic associations with ankylosing spondylitis

Ankylosing spondylitis (AS) is a highly heritable chronic inflammatory arthritis characterized by osteoproliferation, fusion of affected joints and systemic manifestations. Many disease associations for AS have been reported through genome-wide association studies; however, identifying modulated genes and functional mechanism remains challenging. This review summarizes current genetic associations involving AS and describes strategic approaches for functional follow-up of disease-associated variants. Fine mapping using methods leveraging Bayesian approaches are outlined. Evidence highlighting the importance of context specificity for regulatory variants is reviewed, noting current evidence in AS for the relevant cell and tissue type to conduct such analyses. Technological advances for understanding the regulatory landscape within which functional variants may act are discussed using exemplars. Approaches include defining regulatory elements based on chromatin accessibility, effects of variants on genes at a distance through evidence of physical interactions (chromatin conformation capture), expression quantitative trait loci mapping and single-cell methodologies. Opportunities for mechanistic studies to investigate the function of specific variants, regulatory elements and genes enabled by genome editing using clustered regularly interspaced short palindromic repeats/Cas9 are also described. Further progress in our understanding of the genetics of AS through functional genomic and epigenomic approaches offers new opportunities to understand mechanism and develop innovative treatments.

TNFAIP3-DEPTOR complex regulates inflammasome secretion through autophagy in ankylosing spondylitis monocytes

Ankylosing spondylitis (AS) is a chronic autoimmune inflammatory disease with severe inflammatory symptoms in the axial skeleton. The cause of ankylosing spondylitis is unknown. TNFAIP3, also named A20, uses ubiquitin-related functions to regulate immune activation, deficiency of which is highly related to autoimmune disease. However, the role of TNFAIP3 in human AS has not been reported. Our objective was to study the role and mechanism of TNFAIP3 in ankylosing spondylitis. TNFAIP3 expression on different types of immunocytes from AS peripheral blood was measured by flow cytometry. In vitro, monocytes were transfected with a TNFAIP3 shRNA lentivirus, and IL6 and IL1B activation was tested using real-time PCR and ELISA. The novel interaction complex TNFAIP3-DEPTOR was determined through GST pull-down, yeast two-hybrid system, confocal microscopy, and co-immunoprecipitation. Transmission electron microscopy, the RFP-GFP-LC3 adenovirus, and LC3 expression were used for autophagy detection. Here, we show that TNFAIP3 expression in AS peripheral blood non-classical monocytes was decreased. In normal monocytes, TNFAIP3 induced autophagy, which restricted inflammasome activation to the early stage of LPS stimulation. Zinc-finger domains of TNFAIP3 were able to interact and stabilize DEPTOR. TNFAIP3 and DEPTOR together rapidly promoted autophagy after LPS treatment to prevent NLRP3 inflammasome formation. Finally, TNFAIP3 and DEPTOR deficiency in AS non-classical monocytes facilitated inflammasome activation. Our study indicates that TNFAIP3-DEPTOR complex-induced early-onset autophagy is vital for immune inhibition in autoimmune disease.

The Diagnostic and Prognostic Role of Interleukin 12B and Interleukin 6R Gene Polymorphism in Patients With Ankylosing Spondylitis

OBJECTIVES

Interleukin 23 (IL-23) pathway and IL-1 cluster genes play prominent role in the etiopathology of ankylosing spondylitis (AS). The aim of this study was to investigate the diagnostic and prognostic role of 5 single-nucleotide polymorphisms related to IL-23 pathway and IL-1 cluster genes in AS patients.

METHODS

Four hundred thirty-one patients with AS and 206 age- and sex-matched healthy controls were recruited in this prospective cohort study. Five potential single-nucleotide polymorphisms (IL-23R [rs11209026], IL-12B [rs6871626], TYK2 [rs6511701], IL-6R [rs4129267], and IL-1R2 [rs2192752]) related to IL-23 pathway and IL-1 cluster genes by analyzing previous studies were genotyped. Among 431 total AS patients, 198 active cases were treated and followed up for 24 weeks.

RESULTS

Frequencies of IL-12B AA (rs6871626) and IL-6R TT (rs4129267) genotypes were increased in AS patients compared with healthy controls (both P < 0.001), and IL-12B A (rs6871626) as well as IL-6R T (rs4129267) allele increased the risk of AS independently (both P < 0.001). The Bath Ankylosing Spondylitis Disease Activity Index score was found to be elevated in AS patients with IL-12B AA (rs6871626) compared with patients with the CA and CC genotypes (P = 0.002 and P < 0.001, respectively), and the Bath Ankylosing Spondylitis Functional Index score was also increased in AS patents with IL-12B AA (rs6871626) than in those with the CA and CC genotypes (P = 0.001 and P < 0.001). In addition, IL-6R T (rs4129267) allele could predict a worse ASAS-20 (Assessment of SpondyloArthritis international Society) response at week 24 as an independent factor by multivariate logistic regression analysis with additive model (P = 0.011).

CONCLUSIONS

Interleukin 12B (rs6871626) and IL-6R (rs4129267) gene polymorphisms could serve as promising biomarkers for diagnosis and prognosis in AS patients.

High prevalence of hidradenitis suppurativa symptoms in axial spondyloarthritis patients: A possible new extra-articular manifestation

BACKGROUND

Spondyloarthritis (SpA), a chronic inflammatory, rheumatic disease, and hidradenitis suppurativa (HS), a chronic, debilitating, inflammatory skin disease, share several clinical and pathophysiological features, such as the association with inflammatory bowel disease and elevated cytokine levels IL-17 and TNF-α. Recently, SpA was reported to be more prevalent (2.3-28.2%) in patients with HS than in the general population. Conversely, the prevalence of HS in SpA is not exactly known.

OBJECTIVE

To determine the prevalence of HS in patients with axial SpA, a subtype of SpA primarily of the axial skeleton. Secondly, to identify patient characteristics associated with the presence of HS in axial SpA.

METHODS

In this cross-sectional study, a self-screening questionnaire based on validated diagnostic HS questions was sent to all participating axial SpA patients from the Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort fulfilling the ASAS axial SpA criteria. Self-reported HS symptoms were confirmed by previous medical diagnosis or verification by phone using highly specific validated questions.

RESULTS

In total, 75.6% (449/592) questionnaires were eligible for analyses. Included patients had a mean age of 50 ± 13 years, 64% was male, mean symptom duration was 23 ± 13 years, and 79% was HLA-B27 positive. HS diagnosis could be confirmed in 41 patients, resulting in an estimated prevalence of 9.1%. In comparison to patients without a positive history of HS, these patients were more often female (54% vs. 35%, P = 0.02), showed higher axial SpA disease activity (mean BASDAI 4.5 vs. 3.6, p = 0.01 and ASDAS_CRP 2.6 vs. 2.2, P = 0.003) and worse quality of life (QoL) (median ASQoL 9.0 vs. 4.0, P < 0.001). Also, a history of heel enthesitis and dactylitis was more prevalent (34% vs. 19%, P = 0.03 and 15% vs. 6%, P = 0.05, respectively). Multivariable analysis showed that a higher score on ASDAS was independently associated with HS (OR: 1.639, 95% CI: 1.176-2.284).

CONCLUSION

In our cohort of axial SpA patients, HS is more prevalent than in the general population (9.1% versus 0.053-4.1%). HS is associated with female gender, lower QoL, and especially higher axial SpA disease activity.

Regulation of Cytokine Production by the Unfolded Protein Response; Implications for Infection and Autoimmunity

Protein folding in the endoplasmic reticulum (ER) is an essential cell function. To safeguard this process in the face of environmental threats and internal stressors, cells mount an evolutionarily conserved response known as the unfolded protein response (UPR). Invading pathogens induce cellular stress that impacts protein folding, thus the UPR is well situated to sense danger and contribute to immune responses. Cytokines (inflammatory cytokines and interferons) critically mediate host defense against pathogens, but when aberrantly produced, may also drive pathologic inflammation. The UPR influences cytokine production on multiple levels, from stimulation of pattern recognition receptors, to modulation of inflammatory signaling pathways, and the regulation of cytokine transcription factors. This review will focus on the mechanisms underlying cytokine regulation by the UPR, and the repercussions of this relationship for infection and autoimmune/autoinflammatory diseases. Interrogation of viral and bacterial infections has revealed increasing numbers of examples where pathogens induce or modulate the UPR and implicated UPR-modulated cytokines in host response. The flip side of this coin, the UPR/ER stress responses have been increasingly recognized in a variety of autoimmune and inflammatory diseases. Examples include monogenic disorders of ER function, diseases linked to misfolding protein (HLA-B27 and spondyloarthritis), diseases directly implicating UPR and autophagy genes (inflammatory bowel disease), and autoimmune diseases targeting highly secretory cells (e.g., diabetes). Given the burgeoning interest in pharmacologically targeting the UPR, greater discernment is needed regarding how the UPR regulates cytokine production during specific infections and autoimmune processes, and the relative place of this interaction in pathogenesis.

Hematopoietic and mesenchymal stem cells: a promising new therapy for spondyloarthritis?

In the last years, a considerable progress has been made in the treatment of spondyloarthritides. Nonetheless, there remain a considerable number of patients who are unresponsive to all current therapies. Since the late 1990s, numerous trials have investigated the use of stem cell transplantation as a new approach for the treatment of autoimmune disease, particularly with hematopoietic stem cell transplantation. More recently, the research has focused on mesenchymal stem cell application due to their low immunogenicity and immunomodulatory properties. In this article, we summarize available data on hematopoietic stem cell and mesenchymal stem cell use for the treatment of spondyloarthritides and discuss the data gaps and possible research agenda in this area.

Genetic variations in LIGHT are associated with susceptibility to ankylosing spondylitis in a Chinese Han population

Ankylosing spondylitis (AS) is a common chronic autoimmune disease characterized by inflammation of axial skeleton and has strong genetic susceptibility. Single nucleotide polymorphisms (SNPs) have been found playing an important role in the development of AS. This study intends to explore whether the susceptibility to AS is associated with rs2171513 C>T, rs1077667 G>A in LIGHT (lymphotoxin, expressed on T lymphocytes) and rs12609318 A>G in B and T lymphocyte attenuator (BTLA) in a Chinese Han population. We studied a total of 497 AS patients and 387 healthy controls in the current research. Clinical characteristics were recorded when they were recruited. Single nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction (PCR) and high-resolution melting methods (HRM). Statistically significant difference was found in both co-dominant model (GG vs. GA vs. AA) (p = 4.00E-06) and alleles (p = 4.59E-08) of rs1077667 between patients and controls. There was also a significant difference in alleles of rs2171513 (p = 0.037) between patients and controls. We found rs1077667 in LIGHT and rs2171513 in BTLA with susceptibility to AS, while 12609318 in LIGHT associate with susceptibility to AS. Our results showed that LIGHT might be involved in pathogenesis of AS.

Osteoimmunology: The Conceptual Framework Unifying the Immune and Skeletal Systems

The immune and skeletal systems share a variety of molecules, including cytokines, chemokines, hormones, receptors, and transcription factors. Bone cells interact with immune cells under physiological and pathological conditions. Osteoimmunology was created as a new interdisciplinary field in large part to highlight the shared molecules and reciprocal interactions between the two systems in both heath and disease. Receptor activator of NF-κB ligand (RANKL) plays an essential role not only in the development of immune organs and bones, but also in autoimmune diseases affecting bone, thus effectively comprising the molecule that links the two systems. Here we review the function, gene regulation, and signal transduction of osteoimmune molecules, including RANKL, in the context of osteoclastogenesis as well as multiple other regulatory functions. Osteoimmunology has become indispensable for understanding the pathogenesis of a number of diseases such as rheumatoid arthritis (RA). We review the various osteoimmune pathologies, including the bone destruction in RA, in which pathogenic helper T cell subsets [such as IL-17-expressing helper T (Th17) cells] induce bone erosion through aberrant RANKL expression. We also focus on cellular interactions and the identification of the communication factors in the bone marrow, discussing the contribution of bone cells to the maintenance and regulation of hematopoietic stem and progenitors cells. Thus the time has come for a basic reappraisal of the framework for understanding both the immune and bone systems. The concept of a unified osteoimmune system will be absolutely indispensable for basic and translational approaches to diseases related to bone and/or the immune system.

Innate Immune Activation Can Trigger Experimental Spondyloarthritis in HLA-B27/Huβ2m Transgenic Rats

Spondyloarthritis (SpA) does not display the typical features of auto-immune disease. Despite the strong association with MHC class I, CD8⁺ T cells are not required for disease induction in the HLA-B27/Huβ2m transgenic rats. We used Lewis HLA-B27/Huβ2m transgenic rats [21-3 × 283-2]F1, HLA-B7/Huβ2m transgenic rats [120-4 × 283-2]F1, and wild-type rats to test our hypothesis that SpA may be primarily driven by the innate immune response. In vitro, splenocytes were stimulated with heat-inactivated Mycobacterium tuberculosis and cytokine expression and production was measured. In vivo, male and female rats were immunized with 30, 60, or 90 µg of heat-inactivated M. tuberculosis and clinically monitored for spondylitis and arthritis development. After validation of the model, we tested whether prophylactic and therapeutic TNF targeting affected spondylitis and arthritis. In vitro stimulation with heat-inactivated M. tuberculosis strongly induced gene expression of pro-inflammatory cytokines such as TNF, IL-6, IL-1α, and IL-1β, in the HLA-B27 transgenic rats compared with controls. In vivo immunization induced an increased spondylitis and arthritis incidence and an accelerated and synchronized onset of spondylitis and arthritis in HLA-B27 transgenic males and females. Moreover, immunization overcame the protective effect of orchiectomy. Prophylactic TNF targeting resulted in delayed spondylitis and arthritis development and reduced arthritis severity, whereas therapeutic TNF blockade did not affect spondylitis and arthritis severity. Collectively, these data indicate that innate immune activation plays a role in the initiation of HLA-B27-associated disease and allowed to establish a useful in vivo model to study the cellular and molecular mechanisms of disease initiation and progression.

Clinical and Imaging Signs of Spondyloarthritis in First-Degree Relatives of HLA-B27-Positive Ankylosing Spondylitis Patients: The Pre-Spondyloarthritis (Pre-SpA) Cohort Study

OBJECTIVE

To investigate whether seemingly healthy first-degree relatives of patients with ankylosing spondylitis (AS) have clinical, laboratory, or imaging features of spondyloarthritis (SpA).

METHODS

First-degree relatives (ages 18-40 years) of HLA-B27-positive AS patients were included in the pre-spondyloarthritis (Pre-SpA) cohort, a prospective inception cohort study. Clinical, biologic, and imaging features were recorded. First-degree relatives were classified according to several sets of SpA classification criteria.

RESULTS

We report baseline features of 51 first-degree relatives included in this study. Twenty-nine (57%) had back pain, 2 (4%) had psoriasis, 1 (2%) had inflammatory bowel disease, and 1 (2%) had uveitis. Three (6%) had low-grade sacroiliitis, 1 (2%) had cervical syndesmophytes on radiography, and 10 (20%) had bone marrow edema on magnetic resonance imaging of the sacroiliiac joints. Seventeen of 51 first-degree relatives (33%) fulfilled SpA classification criteria: 7 (14%) fulfilled both Assessment of SpondyloArthritis international Society (ASAS) axial SpA and European Spondylarthropathy Study Group (ESSG) classification criteria, 6 (12%) fulfilled only ASAS axial SpA classification criteria, and 4 (8%) fulfilled only ESSG classification criteria; 3 (6%) also fulfilled the Amor criteria. None fulfilled other SpA classification criteria. First-degree relatives fulfilling the ASAS axial SpA and/or ESSG classification criteria had more frequent inflammatory back pain, had a higher level of disease activity, and had more psoriasis. No differences were found in parameters of inflammation, peripheral and extraarticular disease other than psoriasis, and HLA-B27 positivity between those who did and those who did not fulfill the ASAS axial SpA and/or ESSG classification criteria. Four first-degree relatives (12%) who did not fulfill the ASAS axial SpA and/or ESSG classification criteria had imaging abnormalities suggestive of SpA.

CONCLUSION

A substantial proportion of seemingly healthy first-degree relatives of HLA-B27-positive AS patients have clinical and/or imaging abnormalities suggestive of SpA. Thirty-three percent could be classified as having SpA. Further follow-up will show which first-degree relatives will develop clinically manifest SpA.

Infusion of umbilical cord mesenchymal stem cells alleviates symptoms of ankylosing spondylitis

The current study evaluated 5 patients with ankylosing spondylitis (AS). Patients received intravenous transfusions of umbilical cord mesenchymal stem cells (uMSCs). All therapeutic and adverse responses were assessed and recorded during uMSC therapy. No severe adverse reactions were observed in any of the patients, although a slight transient fever was observed in 3 patients within 2–6 h of intravenous administration of uMSCs. Following treatment, the Bath Ankylosing Spondylitis Disease Activity and Bath Ankylosing Spondylitis Metrology Indices decreased, however the Bath Ankylosing Spondylitis Functional Index increased. The erythrocyte sedimentation rate in 3 patients was reduced and C-reactive protein levels in 1 patient were markedly reduced. The symptoms of AS were alleviated in all patients. The present study indicates that intravenous transfusion of uMSCs is safe and well tolerated by patients and that it effectively alleviates disease activity and clinical symptoms. In the future, a larger cohort of patients with AS should be recruited to enable the systemic evaluation of uMSC therapy.

iTRAQ quantitative proteomic study in patients with thoracic ossification of the ligamentum flavum

Thoracic ossification of the ligamentum flavum (TOLF) is a unique disease with ectopic ossification, and is a major cause of thoracic spinal stenosis and myelopathy. However, the underlying etiology remains largely unknown. In this study, the ligamentum flavum was systematically analyzed in TOLF patients by using comprehensive iTRAQ labeled quantitative proteomics. Among 1285 detected proteins, there were 282 proteins identified to be differentially expressed. The Gene Ontology (GO) analysis regarding functional annotation of proteins consists of the following three aspects: the biological process, the molecular function, and the cellular components. The function clustering analysis revealed that ten of the above proteins are related to inflammation, such as tumor necrosis factor (TNF). This finding was subsequently validated by ELISA, which indicated that serum TNF-α of TOLF patients was significantly higher compared with the control group. To address the effect of TNF-α on ossification-related gene expression, we purified and cultured primary cells from thoracic ligamentum flavum of patients with TOLF. TNF-α was then used to stimulate cells. RNA was isolated and analyzed by RT-PCR. Our results showed that TNF-α was able to induce the expressions of osteoblast-specific transcription factor Osterix (Osx) in ligamentum flavum cells, suggesting that it can promote osteoblast differentiation. In addition, as the Osx downstream osteoblast genes OCN and ALP were also activated by TNF-α. This is the first proteomic study to identify inflammation factors such as TNF-α involved in ossified ligamentum flavum in TOLF, which may contribute to a better understanding of the cause of TOLF.

Ankylosing spondylitis and the risk of cancer

Cancer is a multifactorial disease, and imbalances of the immune response and sex-associated features are considered risk factors for certain types of cancer. The present study aimed to assess whether ankylosing spondylitis (AS), an immune disorder that predominantly affects young adult men, is associated with an increased risk of cancer. Using the Taiwan National Health Insurance Research Database, a cohort of patients diagnosed with AS between 2000 and 2008 who had no history of cancer prior to enrollment was established (n=5,452). Age- and sex-matched patients without AS served as controls (n=21,808). The results revealed that the overall incidence of cancer was elevated in patients with AS [standardized incidence ratio (SIR), 1.15; 95% confidence interval (CI), 1.03-1.27]. AS carried an increased risk of hematological malignancy in both sexes, colon cancer in females and bone and prostate cancer in males. Young patients with AS (≤35 years) and patients with a Charlson comorbidity index (CCI) ≥2 experienced a higher incidence of cancer (males, SIR 1.92, and 95% CI 1.04-3.26; females, SIR 2.00 and 95% CI 1.46-5.50). The cancer risk was increased during the first 3 years following the diagnosis of AS (SIR 1.49, 95% CI 1.29-1.71), and overall cancer-free survival was significantly decreased in patients with AS patients of both sexes (P<0.0001). Therefore, AS was found to be associated with an increased risk of cancer. All AS patients must be screened for hematological malignancies, for prostate and bone cancer in males, and for colon cancer in females, particularly younger patients with a CCI ≥2.

The involvement and possible mechanism of pro-inflammatory tumor necrosis factor alpha (TNF-α) in thoracic ossification of the ligamentum flavum

Thoracic ossification of the ligamentum flavum (TOLF) is characterized by ectopic bone formation in the ligamentum flavum and is considered to be a leading cause of thoracic spinal canal stenosis and myelopathy. However, the underlying etiology is not well understood. An iTRAQ proteomics was used to reveal the involvement of inflammation factors in TOLF. TNF-α is a pro-inflammatory cytokine implicated in the pathogenesis of many human diseases. Protein profiling analysis showed that the protein level of TNF-α increased in the ossified ligamentum flavum of TOLF, which was confirmed by western blot. The effects of TNF-α on primary ligamentum flavum cells was examined. Cell proliferation assay demonstrated that primary cells from the ossified ligamentum flavum of TOLF grew faster than the control. Flow cytometry assay indicated that the proportions of cells in S phase of cell cycle of primary cells increased after TNF-α stimulation. To address the effect of TNF-α on gene expression, primary cells were derived from ligamentum flavum of TOLF patients. Culture cells were stimulated by TNF-α. RNA was isolated and analyzed by quantitative RT-PCR. G1/S-specific proteins cyclin D1 and c-Myc were upregulated after TNF-α stimulation. On the other hand, osteoblast differentiation related genes such as Bmp2 and Osterix (Osx) were upregulated in the presence of TNF-α. TNF-α activated Osx expression in a dose-dependent manner. Interestingly, a specific mitogen-activated protein kinase ERK inhibitor U0126, but not JNK kinase inhibitor SP600125, abrogated TNF-α activation of Osx expression. This suggests that TNF-α activates Osx expression through the mitogen-activated protein kinase ERK pathway. Taken together, we provide the evidence to support that TNF-α involves in TOLF probably through regulating cell proliferation via cyclin D1 and c-Myc, and promoting osteoblast differentiation via Osx.

Monosodium urate crystal deposition associated with the progress of radiographic grade at the sacroiliac joint in axial SpA: a dual-energy CT study

Background

Previous studies have revealed that ankylosing spondylitis (AS), as the progenitor of axial spondyloarthritis (AxSpA), has been characterized by the insidiously progressive nature of sacroiliitis and spondylitis. Dual-energy computed tomography (DECT) has recently been used to analyse the deposition of monosodium urate (MSU) crystals with higher sensitivity and specificity. However, it remains unclear whether the existence of the MSU crystal deposition detected by DECT at the sacroiliac joint in patients with AxSpA also is associated with the existing structural damage. Here, we performed this study to show the DECT MSU crystal deposits in AxSpA patients without coexisting gout and to ascertain the relationship between the MSU crystal deposition and the structural joint damage of sacroiliac joints.

Methods

One hundred and eighty-six AxSpA patients without coexisting gout were recruited. The plain radiographs of the sacroiliac joint were obtained, along with the DECT scans at the pelvis and the clinical variables. All statistics based on the left or right sacroiliac joint damage grading (0–4) were calculated independently. Bivariate analysis and ordinal logistic regression was performed between the clinical features and radiographic grades at the sacroiliac joint.

Results

At the pelvis, large quantities of MSU crystal deposition were found in patients with AxSpA. The average MSU crystal volume at the left sacroiliac joint, the right sacroiliac joint, and the pelvis were 0.902 ± 1.345, 1.074 ± 1.878, and 5.272 ± 9.044 cm³, values which were correlated with serum uric acid concentrations (r = 0.727, 0.740, 0.896; p < 0.001). In bivariate analysis, wide clinical variables were associated with the changes in sacroiliac joint damage. Further, the AxSpA duration, BASFI score, and the volume of MSU crystal at both sides of sacroiliac joint were associated with the progress of radiographic grade at the sacroiliac joints in the ordinal logistic models (left AOR = 1.180, 3.800, 1.920; right AOR = 1.190, 3.034, 1.418; p < 0.01).

Conclusions

Large quantities of MSU crystal deposition detected by DECT were found at the pelvis in AxSpA patients without coexisting gout. In addition to AxSpA duration and BASFI score, the MSU crystal deposition at the sacroiliac joint is associated with the progress of radiographic grade at sacroiliac joints in those patients.

Correlation of serum MMP3 and other biomarkers with clinical outcomes in patients with ankylosing spondylitis: a pilot study

The studies aimed to assess a set of biomarkers for their correlations with disease activity/severity of patients with ankylosing spondylitis (AS). A total of 24 AS patients were treated with etanercept and prospectively followed for 12 weeks. Serum levels of TNF-α, IFN-γ, TGF-β, IL6, IL15, IL17, MMP3, and MICA were measured at baseline and after treatment. The change of these biomarkers was analyzed for correlations with MRI indices for joint inflammation, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, AS Disease Activity Score, serum CRP, and ESR. The Wilcoxon rank sum test was used to compare the biomarker levels between pre- and post-treatment and between pre-treatment and controls. Both step-wise procedures based on the Akaike information criterion (AIC) and least absolute shrinkage and selection operator with fivefold cross-validation were used to select the best model for pairwise correlations between the above clinical measures and the serum biomarkers. Serum levels of both MMP3 and IL6 were significantly higher in AS patients at baseline. After treatment, the levels of MMP3 decreased, but TGF-β and TNF-α increased significantly. The changes of serum MMP3 and MICA were significantly associated with MRI sacroiliac joint (SIJ) scores. CRP was positively correlated with serum MMP3 and IL6. The pattern of combined changes of serum MICA, MMP3, TGF-β, IL17, TNF-α, and IFN-γ predicted the MRI score of SIJ by logistic regression analysis. Specific serum biomarkers were significantly associated with clinical measures of AS. Most prominently, serum MMP3 level was found to have a positive correlation with the MRI score of SIJ and CRP. Serum MICA level negatively correlated with disease remission.

Interleukin-22 drives the proliferation, migration and osteogenic differentiation of mesenchymal stem cells: a novel cytokine that could contribute to new bone formation in spondyloarthropathies

OBJECTIVES.

The SpAs are genetically and therapeutically linked to IL-23, which in turn regulates IL-22, a cytokine that has been implicated in the regulation of new bone formation in experimental models. We hypothesize that IL-22, a master regulator of stem cells in other niches, might also regulate human mesenchymal stem cell (MSC) osteogenesis.

METHODS.

The effects of IL-22 on in vitro MSC proliferation, migration and osteogenic differentiation were evaluated in the presence or absence of IFN-γ and TNF (to ascertain IL-22 activity in pro-inflammatory environments). Colorimetric XTT assay, trans-well migration assays, quantitative real-time PCR (qRT-PCR) for MSC lineage markers and osteogenesis assays were used.

RESULTS.

Combined treatment of MSC with IL-22, IFN-γ and TNF resulted in increased MSC proliferation ( P = 0.008) and migration ( P = 0.04), an effect that was not seen in cells treated with IL-22 alone and untreated cells. Osteogenic and adipogenic, but not chondrogenic, transcription factors were upregulated by IL-22 alone ( P < 0.05). MSC osteogenesis was enhanced following IL-22 exposure ( P = 0.03, measured by calcium production). The combination of IFN-γ and TNF with or without IL-22 suppressed MSC osteogenesis ( P = 0.03).

CONCLUSION.

This work shows that IL-22 is involved in human MSC proliferation/migration in inflammatory environments, with MSC osteogenesis occurring only in the absence of IFN-γ/TNF. These effects of IL-22 on MSC function is a novel pathway for exploring pathological, post-inflammation osteogenesis in human SpA.

Anti-IL17A in Axial Spondyloarthritis-Where Are We At?

Knowledge regarding the mechanisms of the IL17–IL23 pathway and its role in spondyloarthritis (SpA) has been pivotal to the development of IL-17 blockade in patients with axial SpA. Previously, only anti-TNF has proven to be clinically efficacious in patients with active disease, despite non-steroidal anti-inflammatory drugs and physiotherapy. However, up to 50% fail to achieve a clinically significant response. Secukinumab, a fully humanized monoclonal antibody targeting IL-17A, has recently been approved for use in patients with active ankylosing spondylitis. Clinical studies and current issues surrounding the use of secukinumab will be discussed.

Serum inflammatory biomarkers fail to identify early axial spondyloarthritis: results from the SpondyloArthritis Caught Early (SPACE) cohort

Introduction

Decreasing the diagnostic delay in axial spondyloarthritis (axSpA) remains a major challenge. Here, we assessed the value of serum inflammatory biomarkers to distinguish early axSpA from other pathologies in a large cohort of patients referred with early back pain.

Methods

Serum c reactive protein (CRP), erythrocyte sedimentation rate (ESR) and calprotectin were determined in the SPondyloArthritis Caught Early (SPACE) cohort (n=310), an early back pain inception cohort. Additionally, explorative serum biomarkers derived from the literature (interleukin-27 (IL-27), human β-defensin-2 (hBD-2) and lipcolin-2 (LCN-2)) were determined by ELISA in full-blown patients with ankylosing spondylitis (AS) (n=21) and healthy controls (n=20).

Results

Serum CRP and ESR levels were not elevated in early axSpA versus ‘control’ back pain patients. Serum calprotectin was elevated in early axSpA versus controls (p=0.01) but failed to identify early axSpA at the individual level (positive predictive value of 38.7%). As to explorative biomarkers, serum levels of IL-27 were not detectable, and hBD-2 and LCN-2 serum levels were not elevated in full-blown AS versus healthy controls (p=0.572, p=0.562, respectively). Therefore, these markers were not further determined in the SPACE cohort.

Conclusions

None of the candidate serum inflammatory markers were useful as diagnostic markers in the early phase of axSpA.