Immunohistological features of hip synovitis in ankylosing spondylitis with advanced hip involvement

Matrix Metalloproteinases; A Biomarker of Disease Activity and Prognosis in Spondyloarthritis: A Narrative Review

BACKGROUND

Matrix metalloproteinases, as components of the proteolytic system, are deemed to be implicated in the pathogenesis and progression of several rheumatic diseases. Their role in spondyloarthritis has been investigated by several studies.

OBJECTIVE

This article aims to review and summarize the current knowledge related to metalloproteinases in patients with spondyloarthritis.

METHODS

To examine the association between matrix metalloproteinases and spondyloarthritis, we conducted a narrative review using a literature search in SCOPUS for English-language sources. The search included studies published from the database inception to December 2020.

RESULTS

A total number of 74 articles were included. It was found that levels of matrix metalloproteinases 3 were higher in radiographic axial spondyloarthritis patients and seemed to play a role in the progression of joint damage. The levels of matrix metalloproteinases 1, 2, and 9 were upregulated in psoriatic arthritis patients compared to psoriasis and could identify psoriasis patients who would develop rheumatic manifestations. The levels of matrix metalloproteinases correlated significantly with disease activity in ankylosing spondylitis and decreased upon treatment with Tumor Necrosis Factor inhibitors (TNFi).

CONCLUSION

Excessive matrix metalloproteinases activity is associated with articular destruction. Their levels can reflect disease activity, structural damage, and response to TNFi in patients with spondyloarthritis. Nevertheless, further studies are needed to confirm these results.

Age and Symptoms at Onset of Ankylosing Spondylitis in Japanese Patients

OBJECTIVE

To examine the age at onset and initial symptoms as clinical features of ankylosing spondylitis (AS) in Japanese patients.

METHODS

This retrospective study included 60 Japanese patients diagnosed with AS at our institute between January 2004 and June 2021. Initial symptoms were considered pain in axial joints and/or extra-axial joints. If a patient had initial symptoms at multiple sites, each site was counted. We assessed trends for the number of patients and sites of initial symptoms according to age at onset.

RESULTS

Mean age (± standard deviation) at onset was 28.9 (± 14.3) years. Approximately one-third of patients experienced onset before age 20. The back was the most common site of initial symptoms (36.7%), followed by the hip (26.7%), knee (15%), buttocks (15%), neck (10%), finger (6.7%), shoulder (3.3%), and others (including overlapping sites). Thirty-two (53.3%) and 25 (41.7%) patients had initial symptom only in axial joints and only in extra-axial joints, respectively. The proportion of patients with initial symptoms only in extra-axial joints significantly decreased with increasing age (p=0.024).

CONCLUSION

Sites of initial symptoms were frequently the back, hip, knee, and buttocks, and 41.7% had initial symptom only in extra-axial joints. Younger onset patients frequently had extra-axial involvement.

The Clinical and MRI Effect of TNF-α Inhibitors in Spondyloarthritis Patients With Hip Involvement: A Real-World Observational Clinical Study

Objectives

Hip involvement is an important cause of disability and poor prognosis in patients with spondyloarthritis (SpA). Tumor necrosis factor (TNF)-α inhibitor treatment has been demonstrated to be effective in SpA patients with hip arthritis; however, quantitative assessment using MRI in long-term follow-up needs further application and observation.

Methods

A total of 239 patients were involved in this study. Methotrexate and sulfasalazine were given as basic treatment. In total, 165 patients received TNF-α inhibitors plus basic treatment, and 74 received basic treatment only, as controls. Clinical symptoms were assessed at baseline and at weeks 12, 24, and 52. MRI performances of hip arthritis, including bone marrow edema (BME) and synovitis, were quantitatively assessed using the Hip Inflammation MRI Scoring System (HIMRISS).

Results

The clinical values of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Harris hip score, and Ankylosing Spondylitis Disease Activity Score (ASDAS)-ESR in both groups showed significant clinical remission at week 52 (p < 0.001). However, the change in disease activity levels at week 52 in the control group was significantly worse than in the TNF-α inhibitor group. At week 52, MRI showed a significant remission trend in the TNF-α inhibitor group versus baseline, and total HIMRISS scores were significantly decreased (26.49 ± 10.37 vs. 20.59 ± 9.41, p < 0.001); the control group only had slight improvement (p < 0.05).

Conclusions

TNF-α inhibitors could significantly improve clinical and MRI manifestations of hip involvement in patients with SpA. Quantitative MRI assessment combined with clinical assessment can be used to accurately evaluate the treatment effect of TNF-α in SpA patients with hip involvement to help guide targeted treatment.

Recent Updates in Juvenile Spondyloarthritis

Spondyloarthritis represents a group of disorders characterized by enthesitis and axial skeletal involvement. Juvenile spondyloarthritis begins before age 16. Joint involvement is usually asymmetric. Bone marrow edema on noncontrast MRI of the sacroiliac joints can facilitate diagnosis. The most significant risk factor for axial disease is HLA-B27. Most patients have active disease into adulthood. Enthesitis and sacroiliitis correlate with greater pain intensity and poor quality-of-life measures. Tumor necrosis factor inhibitors are the mainstay of biologic therapy. Although other biologics such as IL-17 blockers have shown benefit in adult spondyloarthritis, none are approved by the US Food and Drug Administration.

Assessment of hip involvement in patients with ankylosing spondylitis: reliability and validity of the Hip Inflammation MRI Scoring System

Background

This study aimed to test the reliability and validity of the Hip Inflammation MRI Scoring System (HIMRISS) in assessing hip involvement of AS patients with AS at different stages of the bath ankylosing spondylitis radiology index (BASRI-hip) scoring system.

Methods

Fifty-two outpatients with ankylosing spondylitis (AS) were included in this study. The subjects’ data includes demographics, clinical characteristics, disease activity score, and functional index. Based on the Harris hip scoring (HHS) of involved hip and BASRI-hip score, we devided these patients into no hip involvement group((HHS ≥ 80 and BASRI ≤ 1) (Group A), mild hip involvement subgroup (BASRI = 2 or BASRI ≤ 1 and HHS ≤ 79) (Group B), and moderate to advanced hip involvement subgroup (BASRI ≥ 3) (Group C). Data was analyzed statistically by SPSS software.

Results

In total of 44 patients (88 hips), group A consisted of 21 hips, group B consisted of 42 hips and group C consisted of 25 hips. The test–retest intraclass correlation coefficients (ICCs) in four raters were 0.955 ~ 0.977 and interrater ICC was 0.993. HIMRISS correlated moderately with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (r = 0.540, p < 0.001), the Bath ankylosing spondylitis functional index (BASFI) (r = 0.540, p < 0.001), the Bath Ankylosing Spondylitis Functional Index (BASFI) (r = 0.581, p < 0.001), ASDAS-ESR (r = 0.604, p < 0.001), and Ankylosing Spondylitis Disease Activity Score (ASDAS)-C reactive protein (CRP) (r = 0.575, p < 0.001). HIMRISS in groups B and C was significantly higher than that in group A: 29.38 (17.00, 40.94) vs. 14.50 (11.38, 22.25), p = 0.009; 38 (31.13, 64.38) vs 14.50 (11.38, 22.25), p < 0.001.

Conclusions

HIMRISS applied to patients with AS demonstrated a satisfactory reliability, meaning it is a reliable quantitive assessment tool for evaluating early hip involvement in patients with AS.

The application of T2W SPIR-FLAIR in the diagnosis of hip synovitis in patients with spondyloarthritis

OBJECTIVE

To investigate the feasibility and accuracy of T₂ weighted spectral pre-saturation inversion recovery combined with fluid-attenuated inversion recovery (T2W SPIR-FLAIR) in the diagnosis of hip synovitis in patients with spondyloarthritis (SpA).

METHODS

10 volunteers underwent a T2W SPIR and 4 T2W SPIR-FLAIR sequence scans with different inversion times (TIs) to determine the optimum TI that could effectively suppress the intra-articular fluid signals. Hip MRI including T2W SPIR-FLAIR and enhanced T₁ weighted (T1W) SPIR sequences was performed in 45 patients with SpA and totally 90 hips were evaluated. McNemar's test and Kappa test were used to compare the diagnostic results of synovitis between T2W SPIR-FLAIR and enhanced T1W SPIR.

RESULTS

A TI of 2100 ms was selected as the optimum TI. 32 hips from 17 patients exhibited high signal intensity within the articular cavity on both T2W SPIR-FLAIR and enhanced T1W SPIR sequences, while only 3 hips showed high signals within the articular cavity on T2W SPIR-FLAIR. The remaining 55 hips did not show high signals within the articular cavity on both sequences. The T2W SPIR-FLAIR and enhanced T1W SPIR sequences had similar values in the diagnosis of hip synovitis (p = 0.25) and a high degree of diagnostic consistency (Kappa = 0.929).

CONCLUSION

T2W SPIR-FLAIR can effectively suppress the intra-articular fluid signals, while retaining the signals of thickened synovial membranes and can be used for the diagnosis of hip synovitis in patients with SpA. Advances in knowledge: The enhanced T1W SPIR is a classic sequence for synovitis diagnosis, but it requires the injection of contrast agents. The T2W SPIR-FLAIR and enhanced T1W SPIR sequences had similar values in the diagnosis of hip synovitis (p = 0.25) and a high degree of diagnostic consistency (Kappa = 0.929).

Distinct expression of chemokine-like factor 1 in synovium of osteoarthritis, rheumatoid arthritis and ankylosing spondylitis

Chemokine-like factor 1 (CKLF1) is a newly cloned chemotactic cytokine with CCR4 being its functional receptor. Recent evidence demonstrates a role of CKLF1 in arthritis. The aim of this study was to quantify the expression of CKLF1 as well as assess the correlation between CKLF1 and plasma acute-phase markers. Synovium was obtained from 16 osteoarthritis (OA), 15 rheumatoid arthritis (RA) and 10 ankylosing spondylitis (AS) patients undergoing total joint arthroplasty, with other 11 patients treated for meniscal tears during sport accidents serving as normal controls. Levels of CKLF1 and CCR4 mRNA were detected by qRT-PCR, and the expression of CKLF1 was investigated by immunohistochemistry staining, subsequently analyzed with semiquantitative scores. Plasma acute-phase markers of inflammation were determined by ELISA. CKLF1 was found with a particularly up-regulated expression in synovim from AS and RA patients, and CCR4 mRNA levels increased in RA patients, not in OA or AS patients. Elevated levels of plasma markers of inflammation including CRP, ESR and D-dimer were observed in RA. Further, significantly positive correlations between relative expression levels of CKLF1 and CRP/ESR in RA patients and a positive correlation between CKLF1 and ESR in AS patients were found. There was no detectable correlation between CKLF1 and plasma D-dimer. This study confirms an increased but different level of CKLF1 in RA, OA and AS patients, all significantly higher than that in controls. Additionally, the significant positive correlations between CKLF1 levels and CRP/ESR in RA and between CKLF1 and ESR suggest that CKLF1 might contribute to the inflammation state and clinical symptoms in these rheumatic diseases. Further studies are required to investigate the utility of targeting specific CKLF1 for symptom control or disease modification in RA and AS.

A Literature Review of Total Hip Arthroplasty in Patients with Ankylosing Spondylitis: Perioperative Considerations and Outcome

Ankylosing spondylitis is a spondyloarthropathy affecting the sacro-iliac joints with subsequent progression to the spine and the hip joints. The hip joints are affected by synovitis, enthesial inflammation, involvement of medullary bone, progressive degeneration and secondary osteoarthritis. Clinical presentation is usually in the form of pain and stiffness progressing to disabling fixed flexion contractures and in some instances, complete ankylosis. Hip arthroplasty should be considered for hip pain, postural and functional disability, or pain in adjacent joints due to hip stiffness. We conducted a literature review to determine peri-operative considerations and outcome in ankylosing spondylitis patients undergoing hip arthroplasty. In this review, we have discussed pre-operative surgical planning, thromboprophylaxis, anaesthetic considerations and heterotopic ossification. Outcomes of arthroplasty include range of movement, pain relief, survivorship and complications.

How to translate basic knowledge into clinical application of biologic therapy in spondyloarthritis

Spondyloarthritis (SpA) is a family of many diseases, and these diseases share some clinical, genetic, and radiologic features. The disease process in the spine at the beginning is spinal inflammation, in which TNFα is the principal cytokine involved. Therefore, the dramatic clinical and pathologic response of anti-TNFα therapy in SpA is based upon the presence of increased TNFα in synovial tissues and sacroiliac joints, which perpetuates chronic inflammation. The increased Toll-like receptors (TCR) 2 and 4 in the serum, peripheral blood mononuclear cells, or synovial tissues of ankylosing spondyloarthritis (AS) or SpA patients suggest that SpA is highly associated with innate immunity. Any drug including anti-TNFα blocker which can downregulate the TCR, infiltrated neutrophils, or CD163+ macrophages in the synovial tissue is the rationale for the management of SpA. Like rheumatoid arthritis, the increased TH22 and TH17 cells either in blood, synovial fluid, or synovial tissues were also demonstrated in SpA. Thus, TH17 and TH22 may be reasonable cellular targets for therapeutic intervention. Drugs (anti-IL6R or anti-IL6) which can reduce the binding of IL6 and IL6R to the cell surface may be beneficial in SpA. Many proteins are implicated in the new bone formation (syndesmophyte) or ankylosis in AS or SpA. The enhanced BMP and Wnt pathway will activate osteoblasts which promote the new bone formation. However, no drug including anti-TNFα can stop or prevent the syndesmophyte in AS. In summary, looking for new targeting therapies for either anti-inflammation (beyond anti-TNF) or anti-bone formation (including anti-TGFβ or PDGF) is warranted in the future.

Why is biologic therapy useful in spondyloarthritis? Knowledge from synovial immunopathologic studies of spondyloarthritis

The pathogenesis of most rheumatic diseases remains unknown. It is believed that both genetic and environmental factors play a pivotal role in the development of synovial inflammation in rheumatoid arthritis (RA), spondyloarthritis (SpA) and osteoarthritis (OA). In the last two decades, there have been many immunopathologic studies on RA, SpA and OA, and the findings revealed different types of arthritis may also present different pathologic patterns. These included higher vascularity and increased infiltration with CD163 macrophages and neutrophils, but relatively low values for lining cell (LL) hyperplasia in SpA synovium. However, the increased LL hyperplasia, as well as CD1a+ cells and the presence of intracellular citrullinated protein were more prominent in RA than in SpA synovitis. Anti-tumor necrosis factor alpha (anti-TNFα) therapy can significantly reduce synovial LL hyperplasia, vascularity and mononuclear cells infiltration in the majority of RA or SpA patients. This may explain why clinically, arthritis patients can get significant improvement after TNFα blocker treatment.

Transgenic mice over-expressing carbonic anhydrase I showed aggravated joint inflammation and tissue destruction

BACKGROUND

Studies have demonstrated that carbonic anhydrase I (CA1) stimulates calcium salt precipitation and cell calcification, which is an essential step in new bone formation. Our study had reported that CA1 encoding gene has a strong association with rheumatoid arthritis (RA) and ankylosing spondylitis (AS), two rheumatic diseases with abnormal new bone formation and bone resorption in joints. This study investigated the effect of CA1 on joint inflammation and tissue destruction in transgenic mice that over-express CA1 (CA1-Tg).

METHODS

CA1-Tg was generated with C57BL/6J mice by conventional methods. CA1-Tg was treated with collagen-II to induce arthritis (CIA). Wild-type mice, CA1-Tg treated with bovine serum albumin (BSA) and transgenic mice over-expressing PADI4 (PADI4-Tg), a gene known to be involved in rheumatoid arthritis, were used as controls. Histochemistry and X-ray radiographic assay were used to examine joint destruction. Western blotting and real time-PCR were used to examine CA1 expression.

RESULTS

CIA was observed in 60% of CA1-Tg, 20% of PADI4-Tg and 20% of wild-type mice after collagen injections. No CIA was found in CA1-Tg mice that received injections of BSA. The arthritic score was 5.5 ± 0.84 in the CA1-Tgs but the score was less than 2 in the injected wild-type mice and the PADI4-Tgs. The thickness of the hind paws in the CA1-Tgs was 3.46 ± 0.11 mm, which was thicker than that of PADI4-Tgs (2.23 ± 0.08 mm), wild-type mice (2.08 ± 0.06 mm) and BSA-treated CA1-Tgs (2.04 ± 0.07 mm). Histochemistry showed obvious inflammation, synovial hyperplasia and bone destruction in the joints of CA1-Tg that was not detected in PADI4-Tgs or wild-type mice. X-ray assays showed bone fusion in the paws and spines of CA1-Tg mice.

CONCLUSION

Over-expression of CA1 may aggravate joint inflammation and tissue destruction in the transgenic mice.

Carbonic anhydrase I (CA1) is involved in the process of bone formation and is susceptible to ankylosing spondylitis

Introduction

Ankylosing spondylitis (AS) is characterized by abnormal bone formation in the spine and the sacroiliac joints. In vitro assays demonstrate that carbonic anhydrase I (CA1) promotes calcium precipitation. This study investigated the function of CA1 for bio-mineralization and determined if common polymorphisms in the CA1 gene might contribute to AS risk.

Methods

Calcification was induced in Saos-2 cells, a human osteosarcoma cell line, with ascorbic acid and β-glycerophosphate. Calcification was determined by Alizarin Red-S (AR-S) staining. Expressions of CA1, alkaline phosphatase (ALP), bone sialoprotein (BSP), osteocalcin (OCN), osterix (OSX) and runt-related transcription factor-2 (Runx2) were determined by real-time PCR and western blotting. The cells were also treated with acetazolamide, an anti-carbonic anhydrase drug. Genotyping was performed using Illumina VeraCode microarray in a case-control study including 51 AS patients, 267 rheumatoid arthritis (RA) patients and 160 healthy controls. The result was confirmed by Taqman assay, including 258 AS patients, 288 RA patients and 288 healthy controls.

Results

Following the induction of calcification, Saos-2 cells produced large amounts of calcium-rich deposits. Increased transcriptions of CA1, ALP, BSP, OCN, OSX and Runx2, essential genes for ossification, were detected in the cultured cells. Following treatmen with acetazolamide, the expression of CA1 obviously declined and mineralized nodule formation was also decreased. Illumina microarray indicates that SNP at rs7841425 also showed significant differences in allelic frequency (P = 0.01396) and genotypic frequency (P = 0.005902) between AS cases and controls. In addition, SNP at rs7827474 showed significant differences in allelic frequency (P = 5.83E-04) and genotypic frequency (P = 0.000186) between RA cases and controls (P values were adjusted to multiple comparisons). The Taqman assay revealed that rs725605 demonstrated statistically significant evidence of allele frequency (P = 0.022307) and gene frequency (P = 0.007731) for association with AS. This SNP did not show significant differences in allelic frequencies and gene frequencies between RA patients and controls.

Conclusions

CA1 may play an essential role in bio-mineralization and new bone formation. The gene encoding CA1 is susceptible to AS.

Investigation of involved tissue in axial spondyloarthritis--what have we learnt from immunohistochemical studies?

The principal clinical and radiological feature of all axial spondyloarthritis is an involvement of the axial skeleton (sacroiliac joints and spine) and, to a lesser extent, the hip joints. Immunohistochemical studies provide worthwhile information regarding disease mechanisms in axial spondyloarthritis. Immunohistochemical investigation of sacroiliac joints, spine and hip joints suggested an important role of T-cells in the development of acute inflammatory lesions. Furthermore, activated angiogenesis and macrophage/osteoclast activation also play a relevant role in the development of early active inflammatory lesions. Nonetheless, the mechanisms leading to activation of osteoproliferation with subsequent syndesmophyte and ankylosis formation in patients with spondyloarthritis remains unclear. It is suggested that the Wnt pathway is actively involved in this process due to decreased expression of new bone formation inhibitors such as sclerostin. However, to understand the full picture of the interrelationship between inflammation and new bone formation, and to explore new treatment targets for suppression of the excessive bone formation as well, further investigations are needed.

Increased expression of carbonic anhydrase I in the synovium of patients with ankylosing spondylitis

Background

One of the most distinctive features of ankylosing spondylitis (AS) is new bone formation and bone resorption at sites of chronic inflammation. Previous studies have indicated that the hyperplasia and inflammation of synovial tissues are significantly related to the pathogenic process of AS. The present study used a proteomic approach to identify novel AS-specific proteins by simultaneously comparing the expression profiles of synovial membranes from patients with AS, rheumatoid arthritis (RA) and osteoarthritis (OA).

Methods

Synovial tissues were collected from the hip joints of patients with AS and knee joints of patients with RA or OA (n = 10 for each disease) during joint replacement surgery. Proteins extracted from the synovial tissues were separated by 2-D electrophoresis (2-DE), and the proteins with significantly increased expression in the AS samples were subjected to MALDI-TOF/TOF-MS analysis. The results were verified using western blotting and immunohistochemistry. Levels of the candidate proteins in synovial fluids from knee joints (n = 40 for each disease) were measured using ELISA.

Results

The proteomic approach revealed significantly increased expression of carbonic anhydrase I (CA1) in the synovial membrane of patients with AS as compared with the RA and OA tissue samples. Immunohistochemistry and western blotting analysis confirmed the findings described above. The ELISA detected a higher level of CA1 in synovial fluids from patients with AS than those with OA. The mean value of the CA1 level was also higher in AS patients as compared with RA patients. This study also detected increased expression of alpha-1-antitrypsin in the synovial tissues from AS patients, which is in agreement with other reports.

Conclusion

In vitro experiments by other groups indicated that CA1 catalyzes the generation of HCO₃^- through the hydration of CO₂, which then combines with Ca²⁺ to form a CaCO3 precipitate. Calcification is an essential step of bone formation. Substantial evidence indicates that carbonic anhydrase also stimulates bone resorption. Hence, overexpression of CA1 in the synovial tissues of AS patients may promote improper calcification and bone resorption in AS.