Serum levels of matrix metalloproteinase 3 and macrophage colony-stimulating factor 1 correlate with disease activity in ankylosing spondylitis

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.

Biomarker development for axial spondyloarthritis

The term axial spondyloarthritis (axSpA) encompasses a heterogeneous group of diseases that have variable presentations, extra-articular manifestations and clinical outcomes, and that will respond differently to treatments. The prototypical type of axSpA, ankylosing spondylitis, is thought to be caused by interaction between the genetically primed host immune system and gut microbiota. Currently used biomarkers such as HLA-B27 status, C-reactive protein and erythrocyte sedimentation rate have, at best, moderate diagnostic and predictive value. Improved biomarkers are needed for axSpA to assist with early diagnosis and to better predict treatment responses and long-term outcomes. Advances in a range of 'omics' technologies and statistical approaches, including genomics approaches (such as polygenic risk scores), microbiome profiling and, potentially, transcriptomic, proteomic and metabolomic profiling, are making it possible for more informative biomarker sets to be developed for use in such clinical applications. Future developments in this field will probably involve combinations of biomarkers that require novel statistical approaches to analyse and to produce easy to interpret metrics for clinical application. Large publicly available datasets from well-characterized case-cohort studies that use extensive biological sampling, particularly focusing on early disease and responses to medications, are required to establish successful biomarker discovery and validation programmes.

An update on serum biomarkers to assess axial spondyloarthritis and to guide treatment decision

Axial spondyloarthritis (axSpA) is a group of debilitating, chronic, rheumatic conditions characterized by inflammation and new bone formation, mainly involving the spine and the sacroiliac joints. The lack of biomarkers in axSpA is well known. Despite significant treatment advances in recent years thanks to the introduction of drugs with a new mode of action, such as new biologic and targeted synthetic disease-modifying antirheumatic drugs, no relevant improvement in the identification of disease biomarkers has been achieved. Common parameters, such as erythrocyte sedimentation rate and C-reactive protein, which are routinely used to measure systemic inflammation, are the sole markers available to date and are not adequate to assess disease activity in all patients. The aim of this study is to review the most promising serum biomarkers that may help treatment decision in axSpA via a proper assessment of disease activity and identification of negative prognostic factors.

Serological Biomarkers in Early Axial Spondyloarthritis During 24-Months Follow Up (Italian Arm of Space Study)

Objectives: The study aimed to evaluate biomarkers facilitating early axial-spondyloarthritis (axSpA) diagnosis and disease activity and imaging indices correlated. Materials and Methods: Seventy-five patients with low back pain (LBP) (≥3 months, ≤2 years, onset ≤45 years) participating in the Italian arm of the SpondyloArthritis-Caught-Early (SPACE) study underwent a physical examination, questionnaires, laboratory tests, spine, and sacroiliac joints (SIJ) X-rays and magnetic resonance imaging (MRI) at baseline and during a 24-months follow-up. Two expert rheumatologists formulated axSpA diagnosis and assessed fulfillment of Assessment of SpondyloArthritis International Society (ASAS) criteria. Disease activity and physical functioning were assessed using imaging, clinical, and serological indices. Spine and SIJ MRI and X-rays were scored independently by 2 readers following the Spondyloarthritis Research Consortium of Canada (SPARCC), mSASSS, and mNY-criteria. Patients were classified in accordance to ASAS criteria as: 21 patients classified according to axSpA imaging arm; 29 patients classified according to axSpA clinical ± imaging arm; 25 patients not fulfilling ASAS criteria. Results: At baseline biomarker levels were not significantly increased in any of the patient groups. Instead, a significant decrease of all functional and disease activity indices from baseline to 24 months was observed in all the three groups. In the same period, there were no significant variation in the serological markers values within each group. The correlations between IL-17 and IL-23 and clinical and functional indices were not significant. On the other hand, significant correlations were found between IL-22 and Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Patient Global Score (BASG1), Health Assessment Questionnaire (HAQ), Visual Analog Scale (VAS pain); MMP3 and mSASSS; MMP3 and hsCRP. Conclusions: Although not significantly higher in any of the cohorts, IL-22, MMP3, and hsCRP values correlated with some disease activity indices and with mSASSS. Further studies are warranted to confirm these preliminary findings.

Hepatocyte growth factor is a potential biomarker for osteoproliferation and osteoporosis in ankylosing spondylitis

We explored relations between serum hepatocyte growth factor (HGF), disease activity, osteoproliferation, and bone mineral density (BMD) in ankylosing spondylitis (AS), in comparison with healthy controls. HGF was increased especially in male AS patients and smokers and associated with both lower BMD and more chronic radiographic changes in the spine.

INTRODUCTION

Ankylosing spondylitis (AS) is characterized by both osteoproliferation and increased bone loss. Biomarkers are requested to predict the processes. The aims of this study were to compare serum levels of hepatocyte growth factor (HGF), matrix metalloproteinase-3 (MMP-3), and vascular endothelial growth factor (VEGF) in AS patients with healthy controls (HC) and to explore the associations with disease activity, osteoproliferation, and bone mineral density (BMD).

METHODS

Serum from AS patients (modified NY-criteria) and HC was analyzed for HGF, MMP-3, and VEGF with ELISA. Disease activity parameters were collected. Osteoproliferation was assessed with modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and BMD was measured in femoral neck.

RESULTS

Totally, 204 AS patients and 80 sex and age matched HC were included. Serum HGF was higher in the AS patients compared with the HC, whereas serum MMP-3 and VEGF were not. Serum HGF was also higher in smokers and in the male AS patients positively correlated with age, BASMI, and mSASSS, and negatively correlated with BMD. The biomarkers were all positively associated with ESR, CRP, and WBC. In multiple linear regression analysis serum HGF remained associated with higher mSASSS and lower BMD, after adjusting for age, sex, CRP, smoking, and body mass index.

CONCLUSIONS

Serum HGF was increased in male AS patients and associated with higher mSASSS and lower BMD. In addition, serum HGF was positively associated with risk factors for osteoproliferation such as age, CRP and smoking. HGF could be a potential biomarker of importance for the bone metabolism in AS.

TRIAL REGISTRATION

NCT00858819.

Serum bone-turnover biomarkers are associated with the occurrence of peripheral and axial arthritis in psoriatic disease: a prospective cross-sectional comparative study

Background

A recent systematic review identified four candidate serum-soluble bone-turnover biomarkers (dickkopf-1, Dkk-1; macrophage-colony stimulating factor, M-CSF; matrix metalloproteinase-3, MMP-3; osteoprotegerin, OPG) showing possible association with psoriatic arthritis (PsA). We aimed to: (i) confirm and determine if these four biomarkers are associated with PsA; (ii) differentiate psoriasis cases with and without arthritis; and (iii) differentiate PsA cases with and without axial arthritis.

Methods

A prospective cross-sectional comparative two-centre study recruited 200 patients with psoriasis without arthritis (PsC), 127 with PsA without axial arthritis (pPsA), 117 with PsA with axial arthritis (psoriatic spondyloarthritis, PsSpA), 157 with ankylosing spondylitis (AS) without psoriasis, and 50 matched healthy controls (HC). Serum biomarker concentrations were measured using ELISA. Multivariable regression and receiver operating characteristic analyses were performed.

Results

MMP-3 concentrations were significantly higher and M-CSF significantly lower in each arthritis disease group compared with HC (p ≤ 0.02). MMP-3 concentrations were significantly higher (adjusted odds ratio, OR_adj 1.02 per ng/ml increase in concentration; p = 0.0004) and M-CSF significantly lower (OR_adj 0.44 per ng/ml increase; p = 0.01) in PsA (pPsA and PsSpA combined) compared with PsC. Dkk-1 concentrations were significantly higher (OR_adj 1.22 per ng/mL increase; p = 0.01), and OPG concentrations significantly lower (OR_adj 0.20 per ng/mL increase; p = 0.02) in patients with axial arthritis (PsSpA and AS combined) than in those without (pPsA). Furthermore, Dkk-1 concentrations were significantly higher along a spectrum of increasing axial arthritis; Dkk-1 concentrations were higher in AS compared with PsSpA (OR_adj 1.18 per ng/mL increase; p = 0.02). Receiver operating characteristic analysis showed MMP-3 to be the best single biomarker for differentiating PsA from PsC (AUC 0.70 for a cut-off of 14.51 ng/mL; sensitivity 0.76, specificity 0.60).

Conclusions

MMP-3 and M-CSF are biomarkers for the presence of arthritis in psoriatic disease, and could therefore be used to screen for PsA in psoriasis cohorts. Dkk-1 and OPG are biomarkers of axial arthritis; they could therefore be used to screen for the presence of axial disease in PsA cases, and help differentiate PsSpA from AS. High concentrations of Dkk-1 in AS and PsSpA compared with HC, support previous reports that Dkk-1 is dysfunctional in the spondyloarthritides.

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.

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.

Inflammation-driven bone formation in a mouse model of ankylosing spondylitis: sequential not parallel processes

Background

Ankylosing spondylitis (AS) is an immune-mediated arthritis particularly targeting the spine and pelvis and is characterised by inflammation, osteoproliferation and frequently ankylosis. Current treatments that predominately target inflammatory pathways have disappointing efficacy in slowing disease progression. Thus, a better understanding of the causal association and pathological progression from inflammation to bone formation, particularly whether inflammation directly initiates osteoproliferation, is required.

Methods

The proteoglycan-induced spondylitis (PGISp) mouse model of AS was used to histopathologically map the progressive axial disease events, assess molecular changes during disease progression and define disease progression using unbiased clustering of semi-quantitative histology. PGISp mice were followed over a 24-week time course. Spinal disease was assessed using a novel semi-quantitative histological scoring system that independently evaluated the breadth of pathological features associated with PGISp axial disease, including inflammation, joint destruction and excessive tissue formation (osteoproliferation). Matrix components were identified using immunohistochemistry.

Results

Disease initiated with inflammation at the periphery of the intervertebral disc (IVD) adjacent to the longitudinal ligament, reminiscent of enthesitis, and was associated with upregulated tumor necrosis factor and metalloproteinases. After a lag phase, established inflammation was temporospatially associated with destruction of IVDs, cartilage and bone. At later time points, advanced disease was characterised by substantially reduced inflammation, excessive tissue formation and ectopic chondrocyte expansion. These distinct features differentiated affected mice into early, intermediate and advanced disease stages. Excessive tissue formation was observed in vertebral joints only if the IVD was destroyed as a consequence of the early inflammation. Ectopic excessive tissue was predominantly chondroidal with chondrocyte-like cells embedded within collagen type II- and X-rich matrix. This corresponded with upregulation of mRNA for cartilage markers Col2a1, sox9 and Comp. Osteophytes, though infrequent, were more prevalent in later disease.

Conclusions

The inflammation-driven IVD destruction was shown to be a prerequisite for axial disease progression to osteoproliferation in the PGISp mouse. Osteoproliferation led to vertebral body deformity and fusion but was never seen concurrent with persistent inflammation, suggesting a sequential process. The findings support that early intervention with anti-inflammatory therapies will be needed to limit destructive processes and consequently prevent progression of AS.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0805-0) contains supplementary material, which is available to authorized users.

Biomarkers for diagnosis, monitoring of progression, and treatment responses in ankylosing spondylitis and axial spondyloarthritis

With the growing awareness of the impact of chronic back pain and axial spondyloarthritis and recent breakthroughs in genetics and the development of novel treatments which may impact best on early disease, the need for markers that can facilitate early diagnosis and profiling those individuals at the highest risk for a bad outcome has never been greater. The genetic basis of ankylosing spondylitis has been considerably advanced, and HLA-B27 testing has a role in the diagnosis. Knowledge is still incomplete of the rest of the genetic contribution to disease susceptibility, and it is likely premature to use extensive genetic testing (other than HLA-B27) for diagnosis. Serum and plasma biomarkers have been examined extensively in assessing disease activity, treatment response, and as predictors or radiographic severity. For assessing disease activity, other than C-reactive protein and erythrocyte sedimentation rate, the most work has been in examining cytokines (particularly interleukin 17 and 23), matrix metalloproteinase (MMP) markers (particularly MMP3). For assessing those at the highest risk for radiographic progression, biomarkers of bony metabolism, cartilage and connective tissue degradation products, and adipokines have been most extensively assessed. The problem is that no individual biomarkers has been reproducibly shown to assess disease activity or predict outcome, and this area still remains an unmet need, of relevance to industry stakeholders, to regulatory bodies, to the healthcare system, to academic investigators, and finally to patients and providers.

Quantitative tandem mass-spectrometry of skin tissue reveals putative psoriatic arthritis biomarkers

BACKGROUND

Psoriatic arthritis (PsA) is a distinct inflammatory arthritis occurring in 30% of psoriasis patients. There is a high prevalence of undiagnosed PsA in psoriasis patients; therefore, identifying soluble biomarkers for PsA could help in screening psoriasis patients for appropriate referral to a rheumatologist. Potential PsA biomarkers likely originate in sites of inflammation, such as the skin, and subsequently enter systemic circulation. Our goal was to identify candidate PsA biomarkers by comparing the proteome of skin biopsies obtained from patients with PsA to that from patients with psoriasis without PsA.

METHODS

Skin biopsies were obtained from involved and uninvolved skin of 10 PsA and 10 age/gender-matched psoriasis patients without PsA (PsC). Using strong cation exchange chromatography, followed by label-free quantitative tandem mass spectrometry, we characterized the proteomes of pooled skin samples. Extracted ion current intensities were used to calculate protein abundance ratios, and these were utilized to identify differentially regulated proteins.

RESULTS

Forty-seven proteins were elevated in PsA-derived skin compared to PsC-derived skin. Selected reaction monitoring assays were developed to quantify these potential PsA markers in individual skin samples, and 8 markers were confirmed in an independent sample set. ITGB5 and POSTN were measured in serum samples from 33 PsA and 15 PsC patients, using enzyme-linked immunosorbent assays. ITGB5 was significantly elevated in PsA serum (P < 0.01), and POSTN showed a trend. ITGB5 and POSTN correlated significantly in both patient groups (r = 0.472, P < 0.001).

CONCLUSION

Proteomic analysis of PsA and PsC skin identified eight new candidate biomarkers. These markers need to be validated with a larger and independent cohort, in order to delineate their clinical utility in PsA patients. These proteins may also uncover unknown aspects of PsA pathobiology.

Calprotectin (S100A8/9) as serum biomarker for clinical response in proof-of-concept trials in axial and peripheral spondyloarthritis

Introduction

Biomarkers complementing clinical evaluations may help to reduce the length and size of proof-of-concept (PoC) trials aimed to obtain quick “go/no go” decisions in the clinical development of new treatments. We aimed to identify and validate serum biomarkers with a high sensitivity to change upon effective treatment in spondyloarthritis (SpA) PoC trials.

Methods

The candidate biomarkers high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), pentraxin-3 (PTX-3), alpha-2-macroglobulin (alpha-2-MG), matrix metalloproteinase-3 (MMP-3), calprotectin, and vascular endothelial growth factor (VEGF) were determined by enzyme-linked immunosorbent assay (ELISA) in healthy controls (n = 20) and SpA patients before and after 2 weeks of infliximab (n = 18) or placebo (n = 19) treatment in cohort 1. Clinical outcome was evaluated at week 12. Results were validated in ankylosing spondylitis (AS) with infliximab (cohort 2, n = 21) and peripheral SpA with etanercept (cohort 3, n = 20).

Results

Serum levels of calprotectin, hs-CRP, PTX-3, VEGF (all P < 0.001) and MMP-3 (P = 0.062), but not IL-6 and alpha-2-MG, were increased in SpA versus healthy controls. Treatment with infliximab, but not placebo, significantly decreased calprotectin (P < 0.001) and hs-CRP (P < 0.001) levels, with a similar trend for MMP-3 (P = 0.063). The standardized response mean (SRM), which reflects the ability to detect changes over time, was high for calprotectin (−1.26), good for hs-CRP (−0.96) and moderate for MMP-3 (−0.52). Calprotectin and hs-CRP, but not MMP-3, were good biomarkers for treatment response in axial and peripheral SpA as evaluated and confirmed in cohort 2 and 3 respectively.

Conclusions

Calprotectin and hs-CRP are good serum biomarkers with high sensitivity to change upon effective treatment at the group level in small-scale, short term PoC trials in SpA.

The active form of MMP-3 is a marker of synovial inflammation and cartilage turnover in inflammatory joint diseases

Background

Matrix metalloproteinase-3 (MMP-3) plays an important role in the pathology of rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Measurement of active MMP-3 in clinical samples could provide information about progression of rheumatoid diseases, and potentially response to treatment. Hence, we aimed to develop a sensitive assay specifically measuring the active form of MMP-3 (act-MMP-3) both in ex vivo models and in human sera.

Methods

A monoclonal antibody against the first 6 amino acids of act-MMP-3 was developed, and the specificity was carefully tested by comparing total and active MMP-3. A technically robust act-MMP-3 ELISA was produced. For biological validation, human synovial membrane and human cartilage explant (HEX) culture models were measured and compared by ELISA and immunoblots. For clinical relevance, the serum levels of act-MMP-3 in AS and RA patients before and after anti-TNF-α treatment were evaluated.

Results

A highly specific and technically robust ELISA detecting act-MMP-3 in serum was developed. The lower limit of detection was 33.7 pg/mL. The dilution and spiking recovery of human serum was within 100 ± 20%. The average intra- and inter-assay variations were 3.1% and 13.5% respectively.

High levels of act-MMP-3 expression were observed in human synovial membrane culture and oncostatin M and TNF-α stimulated human cartilage. In a cross-sectional study of both AS and RA patients, serum act-MMP-3 level was correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). In addition, in patients receiving anti-TNF-α treatment, the serum level of act-MMP-3 was significantly reduced compared to baseline level reflecting the anti-inflammatory effects of the treatment.

Conclusion

We have successfully developed an assay measuring act-MMP-3 in human serum showing correlation to inflammatory markers. Further studies are required to clarify, whether act-MMP-3 can serve as a predictive marker for outcome in chronic rheumatoid disorders.

Histopathological changes in supraspinous ligaments, ligamentum flava and paraspinal muscle tissues of patients with ankylosing spondylitis

OBJECTIVE

To examine the histopathological changes in spinal tissues of ankylosing spondylitis (AS) patients.

METHODS

Tissue samples from 10 AS patients and 10 control subjects were obtained. Hematoxylin and eosin, picrosirius, Masson and van Gieson stainings were utilized to determine the pathological changes in tissues. Ultrastructural alterations were examined by electronic microscopy. Proteoglycan levels were assessed by enzyme-linked immunosorbent assays (ELISA). Matrix metalloproteinase-3 (MMP-3), transforming growth factor-β1 (TGF-β1) and tumor necrosis factor-α (TNF-α) levels were evaluated by immunohistochemistry.

RESULTS

Our results demonstrate that the density of collagen fibrils was reduced in the supraspinous ligaments of AS tissue and fibrils were loosely and irregularly organized as compared to a regular distribution of collagen fibrils in controls. In ligamentum flava from AS patients, activated fibroblasts with enlarged nuclei were detected, while the number of elastic fibers was greatly decreased. Paraspinal muscle tissues of AS patients exhibited increased collagen fibril accumulation and atrophy. Significantly decreased proteoglycan and elevated MMP-3 levels were found in supraspinous ligament samples from AS patients (P < 0.01). Additionally, the levels of TGF-β1 in ligamentum flava and paraspinal muscle tissues of AS patients were increased (P < 0.01). The expression of TNF-α was also upregulated in the ligamentum flavum (P < 0.01), with no significant difference in the paraspinal muscle between control and AS patients (P > 0.05).

CONCLUSIONS

Our findings reveal histopathological changes that occur in certain spinal tissues of AS patients and suggest that increased levels of MMP-3 and TGF-β1 may contribute to the pathogenesis of AS.

Expression profiling in spondyloarthropathy synovial biopsies highlights changes in expression of inflammatory genes in conjunction with tissue remodelling genes

BACKGROUND

In the spondyloarthropathies, the underlying molecular and cellular pathways driving disease are poorly understood. By undertaking a study in knee synovial biopsies from spondyloarthropathy (SpA) and ankylosing spondylitis (AS) patients we aimed to elucidate dysregulated genes and pathways.

METHODS

RNA was extracted from six SpA, two AS, three osteoarthritis (OA) and four normal control knee synovial biopsies. Whole genome expression profiling was undertaken using the Illumina DASL system, which assays 24000 cDNA probes. Differentially expressed candidate genes were then validated using quantitative PCR and immunohistochemistry.

RESULTS

Four hundred and sixteen differentially expressed genes were identified that clearly delineated between AS/SpA and control groups. Pathway analysis showed altered gene-expression in oxidoreductase activity, B-cell associated, matrix catabolic, and metabolic pathways. Altered "myogene" profiling was also identified. The inflammatory mediator, MMP3, was strongly upregulated (5-fold) in AS/SpA samples and the Wnt pathway inhibitors DKK3 (2.7-fold) and Kremen1 (1.5-fold) were downregulated.

CONCLUSIONS

Altered expression profiling in SpA and AS samples demonstrates that disease pathogenesis is associated with both systemic inflammation as well as local tissue alterations that may underlie tissue damaging modelling and remodelling outcomes. This supports the hypothesis that initial systemic inflammation in spondyloarthropathies transfers to and persists in the local joint environment, and might subsequently mediate changes in genes directly involved in the destructive tissue remodelling.

Association of biomarkers of inflammation, cartilage and bone turnover with gender, disease activity, radiological damage and sacroiliitis by magnetic resonance imaging in patients with early spondyloarthritis

To assess the association between biomarkers of inflammation, cartilage and bone turnover with gender, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Spondylitis Disease Activity Score (ASDAS) and bone marrow oedema in resonance magnetic imaging (MRI) of sacroiliac joints (SIJs) and radiological damage in early spondyloarthritis (SpA). Cross-sectional study of 60 patients (56.7 % females; mean age, 32.4 years) with early SpA. Sociodemographic data, clinical features, serum matrix metalloproteinase 3 (MMP-3), high sensitivity C-reactive protein (hsCRP), C-terminal cross-linking telopeptides of type I collagen (CTX-I) and urinary deoxypyridinoline, ASDAS, BASDAI, BASFI, BASRI and MRI of the SIJs were collected. The mean (SD) disease duration was 12.4 (6.8 months). Twenty-two (68.7 %) of the 32 patients had active sacroiliitis by MRI. MMP-3 and CTX I correlated with swollen joint (r = 0.515, r = 0.386, p = 0.01). hsCRP correlated with ESR (r = 0.303, p = 0.05), with CRP (r = 0.455, p = 0.01) and with total BASRI (r = 0.95, p = 0.05). Biomarkers were unrelated with the rest of variables. Levels of MMP-3 (44.3 ± 52.4 vs 24.7 ± 33.4, p < 0.05) and CTX-I (0.53 ± 0.45 vs 0.24 ± 0.38; p < 0.05) were higher in men. Our study shows that CTX-I and MMP-3 are a marker of peripheral disease activity in early SpA. Male gender had higher levels of CTX-I and MMP-3, which may indicate higher disease activity. Higher hsCRP levels trended towards correlation with more baseline radiographic damage. Therefore, these biomarkers may help identify a subgroup of patients who will need closer monitoring and more intensive treatment.

Soluble Biomarkers Associated with Response to Treatment with Tumor Necrosis Factor Inhibitors in Psoriatic Arthritis

Objective.

To identify soluble biomarkers associated with response to therapy with tumor necrosis factor inhibitors (TNFi) in patients with psoriatic arthritis (PsA).

Methods.

The study was conducted at a PsA clinic where patients are assessed every 6 months, and serum samples are collected and stored once a year at the time of clinical assessment. Forty patients with active PsA who gave serum samples prior to treatment with TNFi and after at least 3 months of therapy were identified. Patients were classified as TNFi responders if tender joint count was < 3, swollen joint count was 0, and Psoriasis Area and Severity Index score was < 4 at the time the second sample was collected. The following biomarkers were tested by ELISA: TNF superfamily 14, matrix metalloprotease-3 (MMP-3), receptor activator of nuclear factor kappa-B ligand, osteoprotegerin, cartilage oligomeric matrix protein (COMP), CPII, C2C and C1-2C, CS-846, and highly sensitive C-reactive protein. Paired t tests and logistic regression was used for statistical analyses.

Results.

After a mean treatment duration of 11 months with TNFi (etanercept 28 patients, adalimumab 6, golimumab 4, infliximab 2), 29 patients were classified as TNFi responders. Baseline level of MMP-3 was independently associated with responder status (OR 1.067 for each 1-unit increase, p = 0.045). A reduction in MMP-3 levels with therapy increased the odds of achieving response (OR 1.213 for each 1-unit change, p = 0.030), whereas a reduction in COMP decreased the odds (OR 0.587, for each 100-unit increase, p = 0.039). None of the other biomarkers was associated with response.

Conclusion.

Baseline as well as reduction in serum MMP-3 and increase in serum COMP are independently associated with response to TNFi therapy in patients with PsA.

Association of cytokine and matrix metalloproteinase profiles with disease activity and function in ankylosing spondylitis

Introduction

The pathology of ankylosing spondylitis (AS) suggests that certain cytokines and matrix metalloproteinases (MMPs) might provide useful markers of disease activity. Serum levels of some cytokines and MMPs have been found to be elevated in active disease, but there is a general lack of information about biomarker profiles in AS and how these are related to disease activity and function. The purpose of this study was to investigate whether clinical measures of disease activity and function in AS are associated with particular profiles of circulating cytokines and MMPs.

Methods

Measurement of 30 cytokines, five MMPs and four tissue inhibitors of metalloproteinases was carried out using Luminex^® technology on a well-characterised population of AS patients (n = 157). The relationship between biomarker levels and measures of disease activity (Bath ankylosing spondylitis disease activity index (BASDAI)), function (Bath ankylosing spondylitis functional index) and global health (Bath ankylosing spondylitis global health) was investigated. Principal component analysis was used to reduce the large number of biomarkers to a smaller set of independent components, which were investigated for their association with clinical measures. Further analyses were carried out using hierarchical clustering, multiple regression or multivariate logistic regression.

Results

Principal component analysis identified eight clusters consisting of various combinations of cytokines and MMPs. The strongest association with the BASDAI was found with a component consisting of MMP-8, MMP-9, hepatocyte growth factor and CXCL8, and was independent of C-reactive protein levels. This component was also associated with current smoking. Hierarchical clustering revealed two distinct patient clusters that could be separated on the basis of MMP levels. The high MMP cluster was associated with increased C-reactive protein, the BASDAI and the Bath ankylosing spondylitis functional index.

Conclusions

A profile consisting of high levels of MMP-8, MMP-9, hepatocyte growth factor and CXCL8 is associated with increased disease activity in AS. High MMP levels are also associated with smoking and worse function in AS.

MMP mediated type V collagen degradation (C5M) is elevated in ankylosing spondylitis

OBJECTIVES

Type V collagen has been demonstrated to control fibril formation. The aim of this study was to develop an ELISA capable of detecting a fragment of type V collagen generated by MMP-2/9 and to evaluate the assay as biomarker for ankylosing spondylitis (AS).

DESIGN AND METHODS

A fragment unique to type V collagen and generated by both MMP-2/9 cleaved at the amino acid position 1317 (C5M) was selected for ELISA development. 40 AS patients and 40 age-matched controls were evaluated.

RESULTS

An ELISA detecting C5M with inter- and intra-assay variations of 9.1% and 4.4% was developed. C5M levels were significantly higher in AS patients compared to controls, 229% (p<0.0001). The diagnostic AUC was 83%.

CONCLUSIONS

This ELISA is the first for detecting type V collagen degradation. AS patients had highly elevated levels of MMP mediated type V collagen degradation. The prognostic and diagnostic values need to be further investigated in additional clinical settings.

Synovial Tissue Response to Treatment with TNF Blockers in Peripheral Spondyloarthritis

This review describes the synovial response to treatment in peripheral spondyloarthritis (SpA). A series of recent studies demonstrates that the synovial histopathology is largely homogenous between different SpA subtypes and can be strongly modulated by effective treatment such as tumor necrosis factor (TNF) blockade. This includes a dramatic reduction of the infiltration with inflammatory cells (with the intriguing exception of B lymphocytes and plasma cells), a modulation of structural features such as vascularity, intimal lining layer hyperplasia, and ectopic lymphoid neogenesis, and a down-regulation of a variety of mediators involved in tissue damage. The analysis of tissue response to targeted therapies appears to be a novel and elegant approach to study the immunopathology of human peripheral SpA in vivo. Moreover, detailed cellular and molecular analysis of synovial features allows to identify synovial biomarkers of clinical response to therapeutic interventions which can be used in future early phase clinical trials in SpA.

Serum markers associated with clinical improvement in patients with ankylosing spondylitis treated with golimumab

Objective

Identify serum biomarkers modulated by golimumab treatment and associated with clinical response in patients with ankylosing spondylitis (AS).

Methods

Sera were collected at weeks 0, 4 and 14 from 100 patients with active AS in the GO–RAISE study. Patients were randomly assigned subcutaneous injections of placebo, golimumab 50 mg, or golimumab 100 mg every 4 weeks. Samples were tested for select inflammatory, bone and cartilage markers, and protein profiling was also performed.

Results

Golimumab treatment resulted in significant decreases in several serum proteins at weeks 4 and 14 compared with placebo. Patients who achieved clinical response at week 14, as assessed by a ≥20% improvement in the Assessment in SpondyloArthitis international Society response criteria (ASAS 20), demonstrated a distinct biomarker profile with lower levels of acute phase reactants and inflammatory biomarkers compared with patients who did not. Notably, combinations of two or three biomarkers assessed at baseline were predictive of various clinical outcomes (ASAS 20, Bath ankylosing spondylitis disease activity index 50 or Bath ankylosing spondylitis functional index) using a logistic regression analysis, and the overall predictive values for these combined biomarkers were greater than observed for C-reactive protein (CRP) alone.

Conclusion

Golimumab modulated acute phase reactants and inflammatory markers in patients with active AS. Specific combinations of biomarkers at baseline demonstrated a stronger prediction for clinical efficacy than CRP alone. These data provide insights into the mechanism of golimumab on inflammatory processes driving AS pathology, and may have utility in managing the treatment of patients with AS.

Levels of serum matrix metalloproteinase-3 correlate with disease activity in the enthesitis-related arthritis category of juvenile idiopathic arthritis

OBJECTIVE

Serum matrix metalloproteinase-3 (MMP-3) has been shown to reflect disease activity in ankylosing spondylitis (AS) and rheumatoid arthritis. Elevated levels have been found in juvenile idiopathic arthritis (JIA). In the enthesitis-related arthritis category of JIA (JIA-ERA), we studied whether serum MMP-3 levels and ratios of MMP-3/tissue inhibitor of metalloproteinase (TIMP-1) are correlated with disease activity and whether they are sensitive to change in disease activity.

METHODS

A total of 54 patients with JIA-ERA (International League of Associations for Rheumatology criteria) were enrolled for study. Baseline disease activity measures included tender and swollen joint counts, Maastricht AS Enthesitis Score, Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), patient assessment of pain and global disease activity, physician assessment of global disease activity, and erythrocyte sedimentation rate (ESR). Serum MMP-3 and TIMP-1 levels were measured using ELISA. A group of 24 patients were followed up for longitudinal study.

RESULTS

The mean age of 54 patients (48 males) at disease onset was 11.8 ± 4.19 years and duration of disease was 5.2 ± 4.3 years. Median ESR was 65 mm/h (range 46.5-97) and median BASDAI was 3.4 (range 2.5-4.7). Median MMP-3, TIMP-1, and MMP-3/TIMP-1 ratio were 50.4 ng/ml (IQR 13.0-193.8), 228.9 ng/ml (IQR 108.2-290.4), and 0.3 (IQR 0.07-1.13), respectively. At inclusion MMP-3 levels correlated directly with various disease activity measures: tender joint count (TJC; r = 0.60), swollen joint count (SJC; r = 0.45), BASFI (r = 0.29), BASDAI (r = 0.32), ESR (r = 0.49), physician global assessment (r = 0.40), patient visual analog scale for pain (r = 0.28), and patient global assessment (r = 0.38; all p < 0.05). MMP-3/TIMP-1 ratio correlated only with TJC (r = 0.51), SJC (r = 0.39), and ESR (r = 0.34; p < 0.05). At followup, change in MMP-3 correlated with changes in TJC (r = 0.42) and SJC (r = 0.44; p < 0.05), while change in ESR did not correlate with change in any disease activity measure.

CONCLUSION

MMP-3 levels are a good marker for disease activity in JIA-ERA.

Serum MMP-3 Level as a Biomarker for Monitoring and Predicting Response to Etanercept Treatment in Ankylosing Spondylitis

Objective.

To investigate whether level of serum matrix metalloproteinase-3 (MMP-3) can serve as a biomarker for monitoring and predicting response to etanercept treatment in patients with ankylosing spondylitis (AS) in daily clinical practice.

Methods.

Ninety-two consecutive AS outpatients with active disease who started etanercept treatment were included in this longitudinal observational study. Clinical data were collected prospectively at baseline and after 3 and 12 months of treatment. At the same timepoints, serum MMP-3 levels were measured retrospectively by ELISA.

Results.

Since baseline serum MMP-3 levels were significantly higher in male compared to female patients with AS, data analysis was split for gender. Changes in serum MMP-3 levels after etanercept treatment correlated positively with changes in clinical assessments of disease activity and physical function in both male and female patients. Receiver operating characteristic analysis in male patients showed that baseline serum MMP-3 levels had poor accuracy (AUC < 0.7) to discriminate between Assessments in Ankylosing Spondylitis 20 (ASAS20) or ASAS40 responders and nonresponders after 3 or 12 months of treatment. The accuracy of change in serum MMP-3 levels from baseline to 3 months in predicting response after 3 or 12 months of treatment was poor for ASAS40 (AUC < 0.7) or moderate for ASAS20 (AUC = 0.752 and 0.744, respectively), and was not superior to the accuracy of change in the currently used objective biomarkers, erythrocyte sedimentation rate and C-reactive protein.

Conclusion.

Although significant changes in serum MMP-3 levels were found after etanercept treatment, data analysis indicates that serum MMP-3 levels are not very useful for monitoring and predicting response to etanercept treatment in patients with AS in daily clinical practice.

Biochemical markers of ongoing joint damage in rheumatoid arthritis--current and future applications, limitations and opportunities

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease associated with potentially debilitating joint inflammation, as well as altered skeletal bone metabolism and co-morbid conditions. Early diagnosis and aggressive treatment to control disease activity offers the highest likelihood of preserving function and preventing disability. Joint inflammation is characterized by synovitis, osteitis, and/or peri-articular osteopenia, often accompanied by development of subchondral bone erosions, as well as progressive joint space narrowing. Biochemical markers of joint cartilage and bone degradation may enable timely detection and assessment of ongoing joint damage, and their use in facilitating treatment strategies is under investigation. Early detection of joint damage may be assisted by the characterization of biochemical markers that identify patients whose joint damage is progressing rapidly and who are thus most in need of aggressive treatment, and that, alone or in combination, identify those individuals who are likely to respond best to a potential treatment, both in terms of limiting joint damage and relieving symptoms. The aims of this review are to describe currently available biochemical markers of joint metabolism in relation to the pathobiology of joint damage and systemic bone loss in RA; to assess the limitations of, and need for additional, novel biochemical markers in RA and other rheumatic diseases, and the strategies used for assay development; and to examine the feasibility of advancement of personalized health care using biochemical markers to select therapeutic agents to which a patient is most likely to respond.

Soluble and tissue biomarkers in ankylosing spondylitis

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

Autoantibody and biopsy grading are associated with expression of ICAM-1, MMP-3, and TRAIL in salivary gland mononuclear cells of Chinese patients with Sjogren's syndrome

OBJECTIVE

Sjögren's syndrome (SS) is an inflammatory autoimmune disease. We investigated important factors associated with the expression of inflammation-related molecules in minor salivary gland (MSG) mononuclear cells in patients with SS.

METHODS

Thirty-four patients with SS with a MSG biopsy grading of either grade III (10 patients) or grade IV (24 patients) were enrolled. The age, sex, autoantibodies, cell infiltration, and intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase-3 (MMP-3), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), or CXCR3 expression were also analyzed.

RESULTS

Ten of the 34 patients with SS were diagnosed with secondary SS; in these patients, the diagnosis of rheumatoid arthritis was confirmed in 8 and systemic lupus erythematosus in 2. TRAIL and ICAM-1 were overexpressed in patients with antinuclear antibodies (ANA) > 1:160, compared to those with titer < 1:160 (45.1 +/- 4.4 vs 41.2 +/- 3.9, p = 0.021, and 15.2 +/- 5.7 vs 10.8 +/- 3.3, p = 0.018, respectively). Higher erythrocyte sedimentation rate (ESR; >OR= 20) was associated with higher TRAIL expression and CD20 cell infiltration in contrast to lower ESR (< 20; p < 0.05). ICAM-1, TRAIL, and MMP-3 were expressed more predominantly in anti-SSA-positive than in anti-SSA-negative patients with SS. There was a significant difference in CD20 cell infiltration and MMP-3 expression between primary SS and secondary SS. Biopsy of a grade IV showed a significantly increased expression of TRAIL (44.9 +/- 4.5 vs 40.8 +/- 3.6, p = 0.013) and MMP-3 (62.7 +/- 6.3 vs 54.4 +/- 7.3, p = 0.003) in mononuclear cells as compared to those of grade III.

CONCLUSION

In our study, pathologic grading with a higher grade (grade IV) and the presence of SSA or a higher titer of ANA were significantly associated with the overexpression of TRAIL, MMP-3, or ICAM-1 in the salivary gland mononuclear cells in patients with SS.

Serum levels of biomarkers of bone and cartilage destruction and new bone formation in different cohorts of patients with axial spondyloarthritis with and without tumor necrosis factor-alpha blocker treatment

Introduction

Recent data about radiographic progression during treatment with tumor necrosis factor-alpha (TNF-α) blocker agents in patients with ankylosing spondylitis (AS) have prompted an intensive discussion about the link between inflammation/bone destruction and new bone formation and the order of events. Therefore, we analysed parameters of cartilage degradation, neoangiogenesis, and new bone formation in different cohorts of patients with axial spondyloarthritis with and without treatment with TNF-α blocker agents.

Method

TNF-α blocker-naïve AS patients were investigated for serum levels of metalloproteinase-3 (MMP-3) (n = 71), vasoendothelial growth factor (VEGF) (n = 50), and bone-specific alkaline phosphatase (BALP) (n = 71) at baseline and after 1 and 2 years. This was compared with 34 adalimumab-treated patients with axial spondyloarthritis (22 AS and 12 non-radiographic axial spondyloarthritis patients) before and after 36 to 52 weeks of treatment.

Results

There were no significant changes in serum levels of MMP-3 (P > 0.05), VEGF (P > 0.05), and BALP (P > 0.05) in a large cohort of TNF-α blocker-naïve AS patients followed for 2 years. In contrast, adalimumab-treated spondyloarthritis (AS and non-radiographic axial spondyloarthritis) patients had a significant decrease of VEGF (P < 0.001) and MMP-3 (P = 0.022) after 36 to 52 weeks of therapy. Most interestingly, the level of BALP increased significantly after 36 to 52 weeks of therapy (P < 0.001). A decrease in MMP-3 serum levels correlated significantly to an increase of BALP (r = -0.398, P = 0.02). In the case of VEGF, there was a negative correlation without significance (r = -0.214, P > 0.05).

Conclusions

Rising levels of BALP and the negative correlation between MMP-3 and BALP in spondyloarthritis patients with TNF-α blocker treatment indicate that new bone formation in AS occurs if inflammation is successfully treated and might be part of a healing process.

Identification of acute phase reactants and cytokines useful for monitoring infliximab therapy in ankylosing spondylitis

Although most ankylosing spondylitis patients show an apparent clinical response to infliximab therapy, there is considerable individual variation. Because current clinical assessment relies heavily on subjective patient self-evaluation, biomarkers of high sensitivity and specificity are much needed. Here, we assessed potential biomarkers in 47 ankylosing spondylitis patients who received three standard pulses of infliximab. Before each infusion and at week 10, the following were measured: erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), platelet count, serum levels of metalloproteinase-3 (MMP-3), and 22 different cytokines. We discovered that, 2 weeks after the first infusion, the combination of ESR, CRP, and platelet count distinguished responders from non-responders with 81.3% sensitivity and 72.7% specificity. The distinguishing power was much less when each acute phase reactant was used alone. Among the 22 cytokines, serum IL-1alpha was able to distinguish responders from non-responders at week 6, with sensitivity of 84.9% and specificity of 53.8%. Serum IL-1alpha was probably generated from the joint compartments, as synovial fluid levels were much higher than corresponding serum levels. Although infliximab infusions led to rapid and significant suppression of serum MMP-3 levels, serum MMP-3 levels did not distinguish responders from non-responders. Besides identifying potential biomarkers, our results also demonstrate the usefulness of using sensitivity and specificity to assess usefulness of potential biomarkers.

Serum matrix metalloproteinase 3 is an independent predictor of structural damage progression in patients with ankylosing spondylitis

OBJECTIVE

In prospective studies, only baseline radiographic damage has been identified as an independent predictor of radiographic progression in ankylosing spondylitis (AS). Several biomarkers have been identified as independent predictors of radiographic progression in rheumatoid arthritis, however, and these may be of use in AS. This study was undertaken to analyze serologic biomarkers as predictors of radiographic progression in AS.

METHODS

We measured a panel of biomarkers reflecting cartilage turnover and osteoclasis. These biomarkers were cartilage oligomeric matrix protein, human cartilage gp-39 (YKL-40), type II collagen epitopes detected by the C2C and C1,2C degradation assays and the CPII synthesis assay, aggrecan 846 epitope, osteoprotegerin, and matrix metalloproteinase 3 (MMP-3). The analysis was performed in a cohort of AS patients from the Netherlands, Belgium, and France enrolled in a longitudinal study, the Outcome Assessments in Ankylosing Spondylitis International Study. We examined 2-year radiographic progression data scored using the modified Stoke AS Spine Score (mSASSS).

RESULTS

Complete data were available on 97 patients. Only the biomarkers YKL-40 and MMP-3 showed weak to moderate univariate correlation with 2-year progression. After adjustment for sex, age, disease duration, C-reactive protein level, and baseline mSASSS, only MMP-3 was significantly associated with 2-year progression (beta = 0.29, P = 0.004). Logistic regression analysis revealed MMP-3 (cutoff 68 ng/ml; odds ratio 9.4 [95% confidence interval 1.6-56]) and baseline mSASSS (cutoff 10 mSASSS units; odds ratio 18.6 [95% confidence interval 2.5-138]) as the only independent predictors of 2-year progression (cutoff 3 mSASSS units; model R(2) = 50%). MMP-3 was primarily contributory in patients who already had substantial baseline damage (>10 mSASSS units).

CONCLUSION

These results indicate that MMP-3 is a significant independent predictor of radiographic progression in patients with AS, particularly in those with preexisting radiographic damage.

Matrix metalloproteinase expression in the spondyloarthropathies

PURPOSE OF REVIEW

Expression of matrix metalloproteinases and their tissue inhibitors has been an active area of investigation in rheumatoid arthritis and osteoarthritis. Only recently have investigators started to study these factors in spondyloarthropathy. The purpose of this review is to summarize these recent findings.

RECENT FINDINGS

Multiple matrix metalloproteinases and their tissue inhibitors are expressed in the synovial fluid as well as serum samples of spondyloarthropathy patients. Their degrees of expression in the synovia correlate with parameters of arthritis activity such as cell infiltration. In the synovial fluids, the factor which is expressed in very high level is matrix metalloproteinase-3. Two separate cohorts demonstrate that serum levels of matrix metalloproteinase-3 correlate with disease activity in ankylosing spondylitis. Their usefulness appears to exceed those of erythrocyte sedimentation rate and C-reactive protein. Multiple studies also indicate that serum levels of matrix metalloproteinase-3 are suppressed when patients are treated with the anti-tumor necrosis factor-alpha antibody infliximab.

SUMMARY

New biomarkers are in demand for spondyloarthropathy in deciding whether patients would benefit from treatment with tumor necrosis factoralpha blockers, monitoring response to treatment, or predicting potential of joint damage if untreated. Recent studies show that among the matrix metalloproteinase and their tissue inhibitors, serum MMP-3 is the one with potential usefulness.

Outcomes in ankylosing spondylitis: what makes the assessment of treatment effects in ankylosing spondylitis different?

There are four major challenges in the assessment of outcomes in patients with ankylosing spondylitis (AS) that are particularly relevant to the evaluation of new therapies. Firstly, measures of symptoms and impairment in AS are not specific for inflammatory processes, they also capture mechanical symptoms and fixed limitations. The non-specific nature of these measures may cause them to be less responsive and therefore less useful in determining treatment efficacy. Secondly, acute phase reactants have limited value as measures of AS activity and other surrogate markers have not yet been established. Thirdly, the assessment of the disease modifying potential of new therapies is hampered by the slow rate of spinal fusion. Fourthly, work disability has not be studied as an endpoint in clinical trials in AS, despite the fact that work disability is an important outcome in patients with AS. Research into ways to overcome these challenges in outcome measurement will help identify useful therapies and define the range of outcomes that they influence.

Biomarkers in spondyloarthritis

In spondyloarthritis, in particular ankylosing spondylitis (AS), a need exists for clinically meaningful biomarkers, both for diagnosis and prognosis. Earlier diagnosis has become an imperative since the advent of biologic therapy, which has proved effective in controlling axial inflammation. Presently, however, there are no biomarkers that reliably distinguish inflammatory back pain from the far more prevalent mechanical back pain. The target sites in AS--sacroiliac joints and the spine--are relatively inaccessible to the investigator and clinician, so defining markers associated with or predictive of axial inflammation remains an important goal. Cytokines, metalloproteinases, and cartilage catabolic products are all candidates for the important role of biomarker in spondyloarthritis.

Infliximab for the treatment of ankylosing spondylitis

Ankylosing spondylitis (AS) had previously been considered as a chronic disease with little therapeutic options. Non-steroidal anti-inflammatory drugs (NSAIDs) and regular physiotherapy were the only treatment modalities available for patients with AS. The introduction of biologics into clinical practice has substantially broadened the therapeutic armamentarium in AS patients who are refractory to NSAIDs. Remicade (infliximab; Centocor, Inc., USA), a chimeric monoclonal antibody, targets TNF-alpha, and by inhibition of this proinflammatory cytokine, exerts strong clinical improvement of signs and symptoms of AS. In AS, infliximab 5 mg/kg body weight is usually given as an infusion at weeks 0, 2 and 6, and every 6 - 8 weeks thereafter. An improvement of the disease activity by at least 50% is seen in as many as 50% of AS patients treated with infliximab in addition to NSAIDs. Back pain and also peripheral manifestations, such as enthesitic sites and arthritis, improve, and quality of life significantly increases. In addition, elevated acute phase reactants return to normal or low levels, and active inflammatory lesions of the spine as detected by magnetic resonance imaging substantially regress during treatment with infliximab. Clinical improvement occurs during the first 2 weeks of treatment and the clinical response to infliximab, if given continuously, is sustained and long-lasting as follow-up data of ongoing studies show. The short-term benefit/risk ratio of infliximab is clearly in favour of the drug, and it is estimated that at present up to 30% of patients with active AS are in need of this kind of effective treatment.

M-CSF mediates TNF-induced inflammatory osteolysis

TNF-alpha is the dominant cytokine in inflammatory osteolysis. Using mice whose BM stromal cells and osteoclast precursors are chimeric for the presence of TNF receptors, we found that both cell types mediated the cytokine's osteoclastogenic properties. The greater contribution was made, however, by stromal cells that express the osteoclastogenic cytokine M-CSF. TNF-alpha stimulated M-CSF gene expression, in vivo, only in the presence of TNF-responsive stromal cells. M-CSF, in turn, induced the key osteoclastogenic cytokine receptor, receptor activator of NF-kappaB (RANK), in osteoclast precursors. In keeping with the proproliferative and survival properties of M-CSF, TNF-alpha enhanced osteoclast precursor number only in the presence of stromal cells bearing TNF receptors. To determine the clinical relevance of these observations, we induced inflammatory arthritis in wild-type mice and treated them with a mAb directed against the M-CSF receptor, c-Fms. Anti-c-Fms mAb selectively and completely arrested the profound pathological osteoclastogenesis attending this condition, the significance of which is reflected by similar blunting of the in vivo bone resorption marker tartrate-resistant acid phosphatase 5b (TRACP 5b). Confirming that inhibition of the M-CSF signaling pathway targets TNF-alpha, anti-c-Fms also completely arrested osteolysis in TNF-injected mice with nominal effect on macrophage number. M-CSF and its receptor, c-Fms, therefore present as candidate therapeutic targets in states of inflammatory bone erosion.

Serum matrix metalloproteinases and tissue inhibitors of metalloproteinases in ankylosing spondylitis: MMP-3 is a reproducibly sensitive and specific biomarker of disease activity

OBJECTIVE

To submit serum levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) to statistical analyses to test their exact degrees of clinical usefulness as biomarkers for detecting high disease activity in ankylosing spondylitis (AS), comparing them with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).

METHODS

Serum levels of MMP-1, -3, -9 and TIMP-1 and -2 were measured in 42 AS patients and 20 healthy controls. The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) provided the gold standard for measuring disease activity. Patients with BASDAI > or =4 were regarded as having high disease activity. The results were compared with results for a separate cohort of 41 AS patients.

RESULTS

Only MMP-3 levels were significantly higher in AS patients than in healthy controls (P<0.001). Within AS patients, MMP-3 levels were also higher in patients with high disease activity compared with those with low disease activity, and correlated significantly with BASDAI (r = 0.366, P = 0.017) and functional indices (r = 0.344, P = 0.026). The correlation with BASDAI was stable in a 1-yr follow-up (r = 0.464, P = 0.095) and reproducible with two different enzyme-linked immunosorbent assays. For detecting high disease activity, the sensitivity and specificity of MMP-3 level was 69.2 and 68.8% respectively. Most importantly, using receiver operating characteristic plots to analyse the two cohorts, MMP-3 was more accurate than ESR and CRP in detecting AS patients with high disease activity (P = 0.01 and P = 0.009, respectively).

CONCLUSION

Using several analytical approaches that have never been reported previously, we showed that MMP-3 is a more useful biomarker than ESR and CRP to detect high disease activity in AS.