Reflections from the OARSI 2022 clinical trials symposium: The pain of OA-Deconstruction of pain and patient-reported outcome measures for the benefit of patients and clinical trial design

OBJECTIVE

Osteoarthritis (OA) drug development is hampered by a number of challenges. One of the main challenges is the apparent discordance between pain and structure, which has had a significant impact on drug development programs and has led to hesitance among stakeholders. Since 2017, the Clinical Trials Symposium (CTS) has been hosted under the Osteoarthritis Research Society International (OARSI) leadership. OARSI and the CTS steering committee yearly invite and encourage discussions on selected special subject matter between regulators, drug developers, clinicians, clinical researchers, biomarker specialists, and basic scientists to progress drug development in the OA field.

METHOD

The main topic for the 2022 OARSI CTS was to elucidate the many facets of pain in OA and to enable a discussion between regulators (Food and Drug Administration (FDA) and the European Medicines Agency (EMA)) and drug developers to clarify outcomes and study designs for OA drug development.

RESULTS

Signs or symptoms indicative of nociceptive pain occur in 50-70% of OA patients, neuropathic-like pain in 15-30% of patients, and nociplastic pain in 15-50% of patients. Weight-bearing knee pain is associated with bone marrow lesions and effusions. There are currently no simple objective functional tests whose improvements correlate with patient perceptions.

CONCLUSIONS

The CTS participants, in collaboration with the FDA and EMA, raised several suggestions that they consider key to future clinical trials in OA including the need for more precise differentiation of pain symptoms and mechanisms, and methods to reduce placebo responses in OA trials.

Differentiating patients with psoriasis from psoriatic arthritis using collagen biomarkers

OBJECTIVES

Around 30% of patients diagnosed with cutaneous psoriasis (PsC) will go on to develop psoriatic arthritis (PsA) which includes inflammation of the joints. Collagens are core proteins in all tissues, which are involved in the inflammatory process in both PsC and PsA. The aim of this study is to investigate collagen biomarkers and their potential use in separating the three patient groupings: PsC, PsA and healthy donors.

METHODS

Healthy donors (n=41), patients with PsC (n=30) and patients with PsA (n=30) were recruited. Clinical disease parameters were recorded. Collagen remodelling was measured using ELISA immunoassays which detect the serological anabolic biomarkers quantifying formation of type I, III and IV collagen (PRO-C1, PRO-C3 and PRO-C4 respectively), and the catabolic biomarkers measuring degradation of type I, II, III, IV and X collagen (C1M, C2M, C3M, C4M and C10C respectively).

RESULTS

Patients with PsC and PsA presented lower levels of PRO-C1 and C3M compared to healthy controls (p<0.05-p<0.0001), C1M was higher in PsA compared to healthy controls (p<0.0001) and C2M was all elevated in PsC and PsA compared to healthy controls (p=0.0002 and p=0.0004 respectively), reflecting alterations in the tissues. In addition, C1M was able to separate between PsC and PsA patients with an AUROC=0.664, indicating that this biomarker may be a biomarker of joint involvement.

CONCLUSIONS

This work provides evidence that serum collagen biomarkers are dysregulated in PsC and PsA, as compared to healthy controls. C1M was able to differentiate patients with PsC from PsA and could be a potential biomarker of inflammatory systemic musculoskeletal involvement.

Considerations for understanding protein measurements: Identification of formation, degradation and more pathological relevant epitopes

OBJECTIVES

There is a need for precision medicine and an unspoken promise of an optimal approach for identification of the right patients for value-based medicine based on big data. However, there may be a misconception that measurement of proteins is more valuable than measurement of fewer selected biomarkers. In population-based research, variation may be somewhat eliminated by quantity. However, this fascination of numbers may limit the attention to and understanding of the single. This review highlights that protein measurements (with collagens as examples) may mean different things depending on the targeted epitope - formation or degradation of tissues, and even signaling potential of proteins.

DESIGN AND METHODS

PubMed was searched for collagen, neo-epitope, biomarkers.

RESULTS

Ample examples of assays with specific epitopes, either pathological such as HbA1c, or domain specific such as pro-peptides, which total protein arrays would not have identified were evident.

CONCLUSIONS

We suggest that big data may be considered as the funnel of data points, in which most important parameters will be selected. If the technical precision is low or the biological accuracy is limited, and we include suboptimal quality of biomarkers, disguised as big data, we may not be able to fulfill the promise of helping patients searching for the optimal treatment. Alternatively, if the technical precision of the total protein quantification is high, but we miss the functional domains with the most considerable biological meaning, we miss the most important and valuable information of a given protein. This review highlights that measurements of the same protein in different ways may provide completely different meanings. We need to understand the pathological importance of each epitope quantified to maximize protein measurements.

Are fatty acids associated with disease activity and biomarkers in patients with psoriatic arthritis? Data from a multicenter clinical trial

The pathogenesis of psoriatic arthritis (PsA) involves inflammation and bone and soft tissue turnover. Dietary fatty acids have previously been associated with pro-inflammatory effects induced by saturated fatty acids (SFA) and anti-inflammatory effects achieved by at least some polyunsaturated fatty acids (PUFA). The aim of the study was to investigate the correlations between the content of fatty acids in granulocytes and clinical and biochemical markers of PsA. A total of 140 patients with PsA were included. Skin and joint disease activity were assessed. Fatty acid composition in granulocytes was determined by gas chromatography. Competitive enzyme-linked immunosorbent assays were used to assess bone and soft tissue turnover. The content of SFA, n-6 PUFA or n-3 PUFA in granulocytes was not associated with disease activity. Marine n-3 PUFA was significantly positively correlated with collagen degradation. In contrast, n-6 PUFA was significantly positively correlated with collagen formation and negatively correlated with collagen degradation. However, the correlations were all weak. No association was found between the content of fatty acids in granulocytes and disease activity in this population of patients with PsA. The correlation between fatty acids and biomarkers of bone and soft tissue turnover needs further investigation.

A case report of pregnancy in untreated alkaptonuria - Focus on urinary tissue remodelling markers

A 34-year old woman with alkaptonuria had an elective pregnancy, during which she collected urine samples over the duration of her pregnancy until parturition. She had been attending the National Alkaptonuria Centre from the age of 31 years and continued to attend after delivery for a further three annual visits. Data from her NAC visits as well as urine samples collected during pregnancy were analysed. Urine CTX-1/urine creatinine, urine αCTX-I/ urine creatinine, urine CTX-II/ urine creatinine, and urine C3M/urine creatinine all showed a rapid increase early in pregnancy, returning to baseline before increasing in late pregnancy, indicating significant remodelling of bone, subchondral bone, cartilage and other organs and connective tissue rich in collagens I, II and III. The pattern of tissue remodelling in AKU pregnancy has been described for the very first time. Further research is needed to understand pregnancy in AKU.

Profiling and targeting connective tissue remodeling in autoimmunity - A novel paradigm for diagnosing and treating chronic diseases

Connective tissue (ConT) remodeling is an essential process in tissue regeneration, where a balanced replacement of old tissue by new tissue occurs. This balance is disturbed in chronic diseases, often autoimmune diseases, usually resulting in the buld up of fibrosis and a gradual loss of organ function. During progression of liver, lung, skin, heart, joint, skeletal and kidney diseasesboth ConT formation and degradation are elevated, which is tightly linked to immune cell activation and a loss of specific cell types and extracellular matrix (ECM) structures that are required for normal organ function. Here, we address the balance of key general and organ specific components of the ECM during homeostasis and in disease, with a focus on collagens, which are emerging as both structural and signaling molecules harbouring neoepitopes and autoantigens that are released during ConT remodeling. Specific collagen molecular signatures of ConT remodeling are linked to disease activity and stage, and to prognosis across different organs. These signatures accompany and further drive disease progression, and often become detectable before clinical disease manifestation (illness). Recent advances allow to quantify and define the nature of ConT remodeling via blood-based assays that measure the levels of well-defined collagen fragments, reflecting different facets of ConT formation and degradation, and associated immunological processes. These novel serum assays are becoming important tools of precision medicine, to detect various chronic and autoimmune diseases before their clinical manifestation, and to non-invasively monitor the efficacy of a broad range of pharmacological interventions.

Inflammation and joint destruction may be linked to the generation of cartilage metabolites of ADAMTS-5 through activation of toll-like receptors

OBJECTIVE

Links between pain and joint degradation are poorly understood. We investigated the role of activation of Toll-like receptors (TLR) by cartilage metabolites in initiating and maintaining the inflammatory loop in OA causing joint destruction.

METHODS

Synovial membrane explants (SMEs) were prepared from OA patients' synovial biopsies. SMEs were cultured for 10 days under following conditions: culture medium alone, OSM + TNFα, TLR2 agonist - Pam2CSK4, Pam3CSK4 or synthetic aggrecan 32-mer, TLR4 agonist - Lipid A. Release of pro-inflammatory and degradation biomarkers (acMMP3 and C3M) were measured by ELISA in conditioned media along with IL-6. Additionally, human cartilage was digested with ADAMTS-5, with or without the ADAMTS-5 inhibiting nanobody - M6495. Digested cartilage solution (DCS) and synthetic 32-mer were tested for TLR activation in SEAP based TLR reporter assay.

RESULTS

Western blotting confirmed TLR2 and TLR4 in untreated OA synovial biopsies. TLR agonists showed an increase in release of biomarkers - acMMP3 and C3M in SME. Synthetic 32-mer showed no activation in the TLR reporter assay. ADAMTS-5 degraded cartilage fragments activated TLR2 in vitro. Adding M6495 - an anti-ADAMTS-5 inhibiting nanobody®, blocked ADAMTS-5-mediated DCS TLR2 activation.

CONCLUSION

TLR2 is expressed in synovium of OA patients and their activation by synthetic ligands causes increased tissue turnover. ADAMTS-5-mediated cartilage degradation leads to release of aggrecan fragments which activates the TLR2 receptor in vitro. M6495 suppressed cartilage degradation by ADAMTS-5, limiting the activation of TLR2. In conclusion, pain and joint destruction may be linked to generation of ADAMTS-5 cartilage metabolites.

Bone and Soft Tissue Turnover in Relation to All-cause Mortality in Postmenopausal Women

BACKGROUND

The relationship between levels of extracellular matrix (ECM) turnover and mortality is currently unknown. The study aimed to determine if levels of ECM turnover are predictors of all-cause mortality in a large cohort of postmenopausal women.

METHODS

5,855 postmenopausal Danish women enrolled in the Prospective Epidemiologic Risk Factor (PERF) study. Baseline demographics and serum were collected at registration. Dates of death were obtained from the Danish Death Registry. ECM turnover was evaluated by serological biomarkers measuring bone (telopeptide of type I collagen [CTX-1] and osteocalcin) and soft tissue (formation of type VI collagen [PRO-C6], MMP-degraded type IV collagen [C4M], formation of type III collagen [PRO-C3], and MMP-degraded type I collagen [C1M]) turnover. Multivariate Cox analyses were performed with 3, 5, and 15 years of follow-up.

RESULTS

The association of bone turnover (CTX-1 and osteocalcin) with all-cause mortality was U-shaped for all time periods. After adjustment for possible confounders, the lowest quintile of bone formation and degradation remained significant for all time periods. We observed J-shaped association between all-cause mortality and PRO-C6, C4M, and PRO-C3, and there was a linear association between C1M and all-cause mortality. After adjustment for possible confounders, the highest quintile of the soft tissue turnover biomarkers (PRO-C6, C4M, PRO-C3, and C1M) remained significantly associated with all-cause mortality for all time periods.

CONCLUSION

Both low and high levels of tissue turnover were associated with increased risk of all-cause mortality in postmenopausal women. Overall, these results highlight the importance of bone and soft tissue homeostasis.

Blood and urinary collagen markers in osteoarthritis: markers of tissue turnover and disease activity

Introduction: The need for diagnostic markers in osteoarthritis (OA) is acute and immediate, as sensitive and precise tools that monitor disease activity and treatment response are lacking. Collagens - types I, II, and III - are the skeleton of the extracellular matrix of joint tissues. Joint collagens are generally turned over at a low rate, but the balance between formation and degradation is disturbed, leading to the loss of, for example, cartilage.Areas covered: We discuss the markers reflecting collagen turnover and provide examples of how they have been applied in OA research, as well as how we believe these should be used in the future. We have searched PubMed for full-text articles written in English using different combinations of the following terms: OA, biomarker, and collagen. The result is a narrative review that gives examples from the literature.Expert opinion: Collagen markers show promise, as they are direct measures of tissue balance. Until now, collagen markers have mainly been tested in observational cohorts, which may provide insights into the association between the candidate marker and clinical variables; however, these do not advance the development of qualified markers that can be used for drug development or in clinical practice.

The intestinal tissue homeostasis - the role of extracellular matrix remodeling in inflammatory bowel disease

Introduction: Extracellular matrix (ECM) remodeling of the intestinal tissue is important in inflammatory bowel disease (IBD) due to the extensive mucosal remodeling. There are still gaps in our knowledge as to how ECM remodeling is related to intestinal epithelium homeostasis and healing of the intestinal mucosa.Areas covered: The aim of this review is to highlight the importance of the ECM in relation to the pathogenesis of IBD, while addressing basement membrane and interstitial matrix remodeling, and the processes of wound healing of the intestinal tissue in IBD.Expert opinion: In IBD, basement membrane remodeling may reflect the integrity of the intestinal epithelial-cell homeostasis. The interstitial matrix remodeling is associated with deep inflammation such as the transmural inflammation as seen in fistulas and intestinal fibrosis leading to fibrostenotic strictures, in patients with CD. The interplay between wound healing processes and ECM remodeling also affects the tissue homeostasis in IBD. The interstitial matrix, produced by fibroblasts, holds a very different biology as compared to the epithelial basement membrane in IBD. In combination with integration of wound healing, quantifying the interplay between damage and repair to these sub compartments may provide essential information in IBD patient profiling, mucosal healing and disease management.

Biochemical markers in osteoarthritis with lessons learned from osteoporosis

Osteoarthritis (OA) is a disease of the whole joint, including synovium, bone and cartilage. OA is a slow degenerative and very heterogeneous disease, with both varying levels of disease activity and progression. Biomarkers are urgently needed to assist drug developers in selecting and developing the projects with the highest chance of success. Biomarkers for enrichment of clinical studies, early efficacy as well as other diagnostic tools are needed. Osteoporosis and OA have many similarities. In osteoporosis an armamentarium of treatments are now available with high clinical efficacy and well-described effects on biomarkers. Possibly, lessons learned from the osteoporosis field in the use of biomarkers may be applied in the OA field, from both technical and scientific perspectives. To help guide the way, the FDA has recently published the BEST guidelines, to facilitate obtaining a common vocabulary to assist biomarker researchers. In the current review, we will review the biomarkers of OA, with emphasis on bone, cartilage and synovial biomarkers, and draw clear perspectives to the use of biomarkers for drug development and clinical practice in the osteoporosis field.

Potential diagnostic value of a type X collagen neo-epitope biomarker for knee osteoarthritis

OBJECTIVE

Phenotypic changes of chondrocytes toward hypertrophy might be fundamental in the pathogenesis of osteoarthritis (OA), of which type X collagen (Col10) is a well-known marker. The purpose was to develop a specific immunoassay for blood quantification of a newly identified neo-epitope of type Col10 to assess its diagnostic value for radiographic knee OA.

METHODS

A neo-epitope of Col10 was identified in urine samples from OA patients. A monoclonal antibody against the neo-epitope was produced in Balb/C mice. The enzyme responsible for the cleavage was identified. Immunohistochemical detection of this neo-epitope was performed on human OA cartilage. An immunoassay (Col10neo) was developed and quantified in two clinical studies: the C4Pain-003 and the NYU OA progression study. Receiver operating characteristic curve (ROC) curve analysis was carried out to evaluate the discriminative power of Col10neo between OA and rheumatoid arthritis (RA).

RESULTS

A neo-epitope specific mAb was produced. The Cathepsin K-generated neo-epitope was localized to the pericellular matrix of chondrocytes, while its presence was extended and more prominent in superficial fibrillation in the cartilage with advanced degradation. In the C4Pain study, a higher level of Col10neo was seen in subjects with greater KL grade. The group of the highest tertile of Col10neo included more subjects with KL3-4. In the NYU study, Col10neo was statistically higher in OA than control or RA. ROC curve analysis revealed area under the curve was 0.88 (95% CI 0.81-0.94).

CONCLUSION

Our findings indicate that Col10neo linked to hypertrophic chondrocytes could be used as a diagnostic biochemical marker for knee OA.

Osteoarthritis year in review 2018: biomarkers (biochemical markers)

OBJECTIVE

The aim of this narrative review is to summarize important findings from biochemical marker studies relevant to osteoarthritis (OA) in the context of new discoveries and clinical and scientific need.

DESIGN

We conducted a systematic search of electronic medical databases (Embase, Medline, Web of Science, Cochrane central) between 01-03-2017 and 31-03-2018. The search was restricted to human studies, English language and full text available publications while reviews were excluded. Only papers describing protein based biomarkers measured in human body fluids (blood, urine and synovial fluid (SF)) were included. Of the 992 papers, 86 were reviewed here, with inclusion primarily based on relevance to OA biochemical markers.

RESULTS

This review highlights a selection of studies based on their quality and perceived importance to the field mainly including those that¹ evaluate prognostic value of biomarkers for OA progression (i.e., biomarkers reflecting change in composition of joint tissues and biomarkers of inflammation)², help in assessment of intervention efficacy, and³ are innovative and uncover new candidate biomarkers, or use new approaches in biomarker discovery.

CONCLUSIONS

Key findings and implications for possible clinical utility of biochemical markers are summarized and discussed. Given the paucity of robust biomarkers within the field, and the heterogeneity of the condition, enormous works are needed for development and validation of novel and clinically applicable biomarkers to reduce the impact of this highly prevalent and debilitating condition.

Serological biomarker profiles of rapidly progressive osteoarthritis in tanezumab-treated patients

There is a need for efficacious and safe pain treatments for OA (osteoarthritis). The nerve growth factor (NGF) antibody tanezumab is associated with high efficacy, but when combined with chronic NSAID treatment shows an increased risk of rapidly progressive osteoarthritis (RPOA) in a small group of patients.

AIM

The aim of this study was to phenotype with biochemical biomarkers of bone, cartilage, soft tissue, synovial metabolism OA patients who are at risk of developing RPOA type-2, for both limited and chronic NSAIDs users.

MATERIAL AND METHODS

The dataset consisted of OA patients participating in tanezumab trials who used NSAIDs <90 days (limited NSAID users) or chronic users (NSAIDs ≥90 days) over an average 10 month period. Biomarker data were available for 47 cases (RPOA type-2) and 92 controls. Non-linear and linear multivariable predictive models were developed.

RESULTS

By use of two biomarkers at baseline the receiver operating characteristic (ROC) curve area for RPOA type-2 in limited NSAID users was 71%, [CI] (60-83%). OA subjects with this biomarker phenotype had 8-fold higher confidence interval [CI][(2-33)] relative risk of developing RPOA type-2 as compared to OA patients without this phenotype. The AUC of the model in chronic NSAIDs users based on 5 biomarkers was 78%, [CI](69-88%), with 4-fold [CI (2-6)] relative risk of developing RPOA type-2.

CONCLUSION

In this hypothesis generating and exploratory study, we identified combinations of biomarkers associated with OA patients who develop RPOA type-2, which may be related to the pathology of the RPOA type-2 joint.

IL-37 diminishes proteoglycan loss in human OA cartilage: donor-specific link between IL-37 and MMP-3

OBJECTIVE

A hallmark of osteoarthritis (OA) is degradation of articular cartilage proteoglycans. In isolated human OA chondrocytes, the anti-inflammatory cytokine Interleukin-37 (IL-37) lowers the expression of the proteolytic MMP and ADAMTS enzymes, which mediate this degradation. Therefore, we investigated if IL-37 protects against proteoglycan loss in freshly obtained human OA explants.

MATERIAL AND METHODS

Human OA cartilage explants were incubated with IL-37. Release of sulphated proteoglycans (sGAGs) was measured with the dimethylmethylene-blue assay. Production and degradation of newly synthesized proteoglycans was measured using ³⁵S-sulphate. Proteoglycan and proteolytic enzyme expression were analyzed by qPCR and Western Blot. Proteolytic activity was determined by measuring MMP- and ADAMTS-generated aggrecan neo-epitopes with ELISA and by using MMP-3-, MMP-13- or ADAMTS-5-inhibitors.

RESULTS

Over time, a linear release of sGAGs from OA cartilage was measured. IL-37 reduced this release by 87 μg/ml (24%) 95%CI [21.04-141.4]. IL-37 did not affect ³⁵S-sulphate incorporation or proteoglycan gene expression. In contrast, IL-37 reduced loss of ³⁵S-sulphate labeled GAGs and reduced MMP-3 protein expression, indicating that IL-37 inhibits proteoglycan degradation. Remarkably, we observed two groups of patients; one group in which MMP-3-inhibition lowered sGAG release, and one group in which ADAMTS5-inhibition had this effect. Remarkably, IL-37 was only functional in the group of patients that responded to MMP-3-inhibition.

CONCLUSION

We identified a relationship between IL-37 and reduced sGAG loss in OA cartilage. Most likely, this effect is mediated by inhibition of MMP-3 expression. These results suggest that IL-37 could be applied as therapy in a subgroup of OA patients, in which cartilage degradation is mediated by MMP-3.

The VICM biomarker is released from activated macrophages and inhibited by anti-GM-CSFRα-mAb treatment in rheumatoid arthritis patients

OBJECTIVES

Macrophages possess widespread pro-inflammatory, destructive, and remodelling capabilities that can critically contribute to acute and chronic diseases, such as rheumatoid arthritis (RA). Continuous monitoring and measurement of selective counteraction of macrophage activity in patients require a sensitivity and non-invasive marker. We characterised the VICM (citrullinated and MMP degraded vimentin fragment) biomarker by investigating the release from in vitro activated macrophages and by monitoring the change in serum levels after treatment with the anti-GM-CSFRα-mAb (mavrilimumab).

METHODS

Peripheral blood mononuclear cells were isolated, and lipopolysaccharide (LPS) was used to activate the macrophages and calcium chloride (CaCl2) was used to facilitate the citrullination process of vimentin. Supernatants, cell lysates, was collected and analysed by ELISA, and western blotting. RA patients were treated with mavrilimumab+methotrexate or methotrexate alone in a phase 2b study (NCT01706926) once every two weeks for 24 weeks. Serum levels of VICM were measured at baseline and multiple time points post-treatment. In addition, whole blood expression of peptidylarginine deiminase-2 (PAD-2) and matrix metalloproteinase-9 (MMP-9) transcripts were tested by quantitative reverse transcriptase PCR assays at day 0 and day 169 post-treatment.

RESULTS

VICM levels were significantly higher at day 5 and 8 in supernatants of activated macrophages compared to controls (p<0.01), which was confirmed by Western blot. In RA patients, VICM correlated with disease activity (DAS28), modified total sharp score (mTSS), joint space narrowing (JSN), joint erosions and CRP at baseline. VICM was dose-dependently and significantly (p<0.01) inhibited by mavrilimumab. This suppression of VICM serum levels was supported by a decreased expression of PAD2 and MMP9 transcripts in patients treated with mavrilimumab.

CONCLUSIONS

These data verified that VICM is released by activated macrophages. Treatment of RA patients with mavrilimumab significantly reduced release of VICM and peptidylarginine deiminases-2 (PAD-2) gene expression indicating that mavrilimumab indeed is targeting activated macrophages and that VICM may be a novel blood-based marker of anti-GM-CSF response.

Type IV collagen metabolism is associated with disease activity, radiographic progression and response to tocilizumab in rheumatoid arthritis

OBJECTIVES

The expanding spectrum of targeted therapies for rheumatoid arthritis (RA) implies a need for development of precision tools for disease assessment reflecting pathobiologic processes. Type IV collagen is an abundant protein of basement membranes, but is also present in the intercellular matrix of the synovial lining layer. We aimed to investigate the association of type IV collagen turnover with RA disease activity, response to IL-6 inhibition and radiographic progression.

METHODS

C4M, a serologic marker of type IV collagen metabolism, was measured at baseline and at follow-up in serum samples of RA patients participating in the phase III studies LITHE (n=687) and RADIATE (n=217). Both were double-blinded, placebo-controlled clinical trials testing the safety and efficacy of 4 and 8 mg/kg tocilizumab (TCZ) in combination with methotrexate (MTX) vs. MTX plus placebo. Associations with disease activity, radiographic severity and ACR response were investigated.

RESULTS

Baseline C4M correlated significantly with clinical disease parameters in both study populations, including DAS28, HAQ score and VASpain (all p<0.00001). C4M at baseline correlated significantly with change in JSN (p=0.001) and Sharp score (p=0.00002) at 52 weeks. TCZ lowered C4M by 11-40% in a dose dependent manner. The likelihood of achieving an ACR20 response by week 16 was associated with C4M suppression exceeding the median decrease at week 4 (p<0.0001).

CONCLUSIONS

Type IV collagen remodelling was associated with disease activity and radiographic progression in RA and was persistently and dose-dependently suppressed by TCZ. These findings indicate that C4M may serve as a plausible biologic marker of destructive synovitis growth in RA.

A machine learning approach for the identification of new biomarkers for knee osteoarthritis development in overweight and obese women

OBJECTIVE

Knee osteoarthritis (OA) is among the higher contributors to global disability. Despite its high prevalence, currently, there is no cure for this disease. Furthermore, the available diagnostic approaches have large precision errors and low sensitivity. Therefore, there is a need for new biomarkers to correctly identify early knee OA.

METHOD

We have created an analytics pipeline based on machine learning to identify small models (having few variables) that predict the 30-months incidence of knee OA (using multiple clinical and structural OA outcome measures) in overweight middle-aged women without knee OA at baseline. The data included clinical variables, food and pain questionnaires, biochemical markers (BM) and imaging-based information.

RESULTS

All the models showed high performance (AUC > 0.7) while using only a few variables. We identified both the importance of each variable within the models as well its direction. Finally, we compared the performance of two models with the state-of-the-art approaches available in the literature.

CONCLUSIONS

We showed the potential of applying machine learning to generate predictive models for the knee OA incidence. Imaging-based information were found particularly important in the proposed models. Furthermore, our analysis confirmed the relevance of known BM for knee OA. Overall, we propose five highly predictive small models that can be possibly adopted for an early prediction of knee OA.

Sprifermin (rhFGF18) enables proliferation of chondrocytes producing a hyaline cartilage matrix

OBJECTIVE

Fibroblast growth factor (FGF) 18 has been shown to increase cartilage volume when injected intra-articularly in animal models of osteoarthritis (OA) and in patients with knee OA (during clinical development of the recombinant human FGF18, sprifermin). However, the exact nature of this effect is still unknown. In this study, we aimed to investigate the effects of sprifermin at the cellular level.

DESIGN

A combination of different chondrocyte culture systems was used and the effects of sprifermin on proliferation, the phenotype and matrix production were evaluated. The involvement of MAPKs in sprifermin signalling was also studied.

RESULTS

In monolayer, we observed that sprifermin promoted a round cell morphology and stimulated both cellular proliferation and Sox9 expression while strongly decreasing type I collagen expression. In 3D culture, sprifermin increased the number of matrix-producing chondrocytes, improved the type II:I collagen ratio and enabled human OA chondrocytes to produce a hyaline extracellular matrix (ECM). Furthermore, we found that sprifermin displayed a 'hit and run' mode of action, with intermittent exposure required for the compound to fully exert its anabolic effect. Finally, sprifermin appeared to signal through activation of ERK.

CONCLUSIONS

Our results indicate that intermittent exposure to sprifermin leads to expansion of hyaline cartilage-producing chondrocytes. These in vitro findings are consistent with the increased cartilage volume observed in the knees of OA patients after intra-articular injection with sprifermin in clinical studies.

Identification of serological biomarker profiles associated with total joint replacement in osteoarthritis patients

OBJECTIVE

Establish a biomarker panel associated with all-cause total joint replacement (TJR) through identification of patients with osteoarthritis (OA) who do or do not progress to TJR and investigate effects of nonsteroidal anti-inflammatory drugs (NSAIDs).

DESIGN

Serum samples from patients enrolled in phase III trials of tanezumab who experienced TJR (n = 174) or matched patients who did not (n = 321) were analyzed for bone, cartilage, soft tissue, and inflammation markers. Classification and Regression Tree (CART) analysis was used to identify biomarker phenotypes associated with TJR.

RESULTS

At baseline, biomarker combinations for patients who did not use NSAIDs before starting tanezumab and used NSAIDs during tanezumab treatment <90 days ("nonNSAID"), identified 77% (95% confidence interval [CI]: 71-84%) of patients who experienced TJR and 77% (95% CI: 65-86%) who did not over a 6-month study period (on average). These biomarker combinations increased odds of identifying patients to remain free of a TJR by 3.3-fold. In patients who used NSAIDs continuously (during screening and ≥90 days during tanezumab treatment), 64% (95% CI: 54-73%) who had TJR and 75% (95% CI: 68-83%) who did not were identified by biomarker combinations different from nonNSAID patients, with an increase in odds of identifying patients to remain free of a TJR by two-fold.

CONCLUSIONS

Although validation on other cohorts is necessary, biomarkers may assist in identifying patients who will need TJR. The profiles suggest NSAID use increases importance of bone metabolism in TJR pathology.

Disease-modifying treatments for osteoarthritis (DMOADs) of the knee and hip: lessons learned from failures and opportunities for the future

Osteoarthritis (OA) is the biggest unmet medical need among the many musculoskeletal conditions and the most common form of arthritis. It is a major cause of disability and impaired quality of life in the elderly. We review several ambitious but failed attempts to develop joint structure-modifying treatments for OA. Insights gleaned from these attempts suggest that these failures arose from unrealistic hypotheses, sub-optimal selection of patient populations or drug dose, and/or inadequate sensitivity of the trial endpoints. The long list of failures has prompted a paradigm shift in OA drug development with redirection of attention to: (1) consideration of the benefits of localized vs systemic pharmacological agents, as indicated by the increasing number of intra-articularly administered compounds entering clinical development; (2) recognition of OA as a complex disease with multiple phenotypes, that may each require somewhat different approaches for optimizing treatment; and (3) trial enhancements based on guidance regarding biomarkers provided by regulatory agencies, such as the Food and Drug Administration (FDA), that could be harnessed to help turn failures into successes.

Collagen degradation products measured in serum can separate ovarian and breast cancer patients from healthy controls: A preliminary study

BACKGROUND

During cancer the otherwise tightly controlled homeostasis of the extracellular matrix (ECM) is disturbed. The protein composition changes, the ECM stiffens and increased levels of proteases are secreted. The combination of these processes result in release of specific protein fragments (e.g. collagens) to the circulation, which when measured may reflect disease pathogenesis.

OBJECTIVE

To investigate if biomarkers of protease-degraded collagen could differentiate ovarian and breast cancer patients from healthy controls when measured in serum.

METHODS

The levels of markers reflecting MMP-degradation of type I (C1M), type III (C3M) and type IV (C4M, C4M12) collagen were assessed in serum from ovarian cancer patients (n= 10), breast cancer patients (n= 14) and healthy controls (n= 49) using validated ELISAs. The markers were compared using one way ANOVA and AUC was calculated.

RESULTS

All markers were significantly elevated in serum from ovarian cancer patients (p< 0.0001) and breast cancer patients (p< 0.04-0.0001) compared to healthy controls. Furthermore, diagnostically the markers were able to differentiate ovarian (AUROC 90%-93%) and breast cancer patients (AUROC 76%-93%) from healthy controls, with C1M being the strongest differentiator of disease vs.

CONCLUSION

Four serum biomarkers reflecting altered MMP-mediated collagen turnover were able to differentiate ovarian and breast cancer patients from healthy controls.

Quantification of fibronectin as a method to assess ex vivo extracellular matrix remodeling

Altered architecture, composition and quality of the extracellular matrix (ECM) are pathological hallmarks of several inflammatory and fibro-proliferative pathological processes such as osteoarthritis (OA), rheumatoid arthritis (RA), fibrosis and cancer. One of the most important components of the ECM is fibronectin. Fibronectin serves as an adhesion molecule anchoring cells to the underlying basement membrane through direct interaction with integrin receptors. Fibronectin hereby modulates the properties of the ECM and affects cellular processes. Quantification of fibronectin remodeling could therefore be used to assess the changes in the ECM that occur during progression of fibro-proliferative pathologies. Ex vivo models are becoming state-of-the-art tools to study ECM remodeling as the cellular composition and the organization of the ECM are preserved. Ex vivo models may therefore be a valuable tool to study the ECM remodeling that occurs during progression of fibro-proliferative pathologies. The aim of this study was to quantify fibronectin remodeling in ex vivo models of cartilage and cancer. A competitive The enzyme-linked immunosorbent assay (ELISA) against the C-terminus of fibronectin was developed (FBN-C). The assay was evaluated in relation to specificity, technical performance and as a marker for quantification of fibronectin in cartilage and cancer ex vivo models. The ELISA was specific and technically stable. Cleavage of tumor tissue with MMP-2 released significantly higher levels of FBN-C compared to tissue with buffer only and western blot analysis revealed that FBN-C recognizes both full length and degraded fibronectin. When ex vivo cartilage cultures were stimulated with the anabolic factor TGFβ and catabolic factors TNF-α and OSM, significantly higher levels of FBN-C were found in the conditioned media. Lastly, FBN-C was released from a cancer ex vivo model. In conclusion, we were able to quantify fibronectin remodeling in ex vivo models of cartilage and cancer. Quantification of fibronectin remodeling could be a valuable tool to understand ECM remodeling in ex vivo models of fibro-proliferative pathologies.

Osteoarthritis biomarkers derived from cartilage extracellular matrix: Current status and future perspectives

Specific soluble biomarkers can be powerful tools for the diagnosis, prognosis and personalized management of osteoarthritis (OA). Biomarkers are potential indicators of the effect of a drug on cartilage metabolism and provide crucial information about the mechanisms of drug action. In this review, we address key questions concerning the use of biomarkers in OA management: Why do we need soluble biomarkers? What are the most widely investigated biomarkers derived from cartilage extracellular matrix? What are the most common pitfalls in interpreting soluble biomarker measurements? What are the perspectives and future research directions in this field? We review current evidence to propose that cartilage-derived soluble biomarkers are complementary "drug development tools" that can be applied during drug development from preclinical research to clinical evaluation. In the future, such biomarkers could be surrogate markers of clinical and/or imaging outcomes. Successful standardization and implementation of automated biomarker assays will facilitate their use in companion diagnostics in the context of personalized medicine for enhanced management of OA.

Osteoarthritis year in review 2015: soluble biomarkers and the BIPED criteria

OBJECTIVE

To review and summarize biomarker data published from April 2014 to May 2015 to provide insight to the ongoing work in the field of osteoarthritis (OA). Furthermore, to summarize the BIPED criteria and set it in context of the medical needs of 2015.

METHODS

PubMed was used as searching machine: Time period 2014/04/01-2015/05/01, MeSH term [Biomarker] AND [Osteoarthritis], Language; English, Full text available. Reviews were excluded. Only papers describing protein based biomarkers measured in human body fluids from OA patients were included.

RESULTS

Biomarkers of joint tissue turnover, cytokines, chemokines and peptide arrays were measured in different cohorts and studies. Amongst those were previously tested biomarkers such as osteocalcin, Carboxy-terminal cross-linked fragment of type II collagen (CTX-II) and cartilage oligomeric matrix protein (COMP). A majority of the biomarker were classified as I, B or B biomarkers according to the BIPED criteria. Work is continuing on testing biomarkers in OA. There is still a huge, unmet medical need to identify, test, validate and qualify novel and well-known biomarkers. A pre-requisite for this is better characterization and classification of biomarkers to their needs, which may not be reached before higher understanding of OA phenotypes has been gained. In addition, we provide some references to some recent guidelines from Food and Drug Administration (FDA) and European Medicines Agency (EMA) on qualification and usage of biomarkers for drug development and personalized medicine, which may provide value to the field.

Inflammation (or synovitis)-driven osteoarthritis: an opportunity for personalizing prognosis and treatment?

The disabling and painful disease osteoarthritis (OA) is the most common form of arthritis. Strong evidence suggests that a subpopulation of OA patients has a form of OA driven by inflammation. Consequently, understanding when inflammation is the driver of disease progression and which OA patients might benefit from anti-inflammatory treatment is a topic of intense research in the OA field. We have reviewed the current literature on OA, with an emphasis on inflammation in OA, biochemical markers of structural damage, and anti-inflammatory treatments for OA. The literature suggests that the OA patient population is diverse, consisting of several subpopulations, including one associated with inflammation. This inflammatory subpopulation may be identified by a combination of novel serological inflammatory biomarkers. Preliminary evidence from small clinical studies suggests that this subpopulation may benefit from anti-inflammatory treatment currently reserved for other inflammatory arthritides.

OA phenotypes, rather than disease stage, drive structural progression--identification of structural progressors from 2 phase III randomized clinical studies with symptomatic knee OA

BACKGROUND/PURPOSE

The aim of this study was to identify key characteristics of disease progression through investigation of the association of radiographic progression over two years with baseline Joint Space Width (JSW), Kellgren-Lawrence (KL) grade, Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain, Joint Space Narrowing (JSN), and BMI.

METHODS

Data from 2206 subjects (4390 knees) were combined for this post-hoc analysis of two randomized, double-blind, multi-center, placebo-controlled phase III trials (NCT00486434 and NCT00704847) that evaluated the efficacy and safety of 2-years treatment with oral salmon calcitonin of subjects with painful knee osteoarthritis (OA).

RESULTS

There was a clear positive and significant correlation between KL grade and WOMAC pain and total WOMAC, albeit the variance in pain measures was from min-to-max for all KL categories, emphasizing the heterogeneity of this patient population and pain perception. 32% of target knees did not progress, and only 51% had changes over minimum significant change (MSC). BMI, KL-Score and WOMAC pain was diagnostic, but only KL-score and pain had prognostic value, albeit pain in a non-linear manner.

CONCLUSION

These data clearly describe significant associations between KL grade, JSW, pain and BMI in patients with symptomatic knee OA. KL grade, BMI and WOMAC pain were diagnostically associated with OA based on JSW but only KL-score and pain in a non-linier fashion was prognostic. 50% of patients did not progress more than MSC, highlighting the importance for identification of structural progressors and the phenotypes associated with these. These results suggest that disease phenotypes, rather than disease status, are responsible for disease progression.

Association between biochemical cartilage markers and clinical symptoms in patients with hip osteoarthritis: cohort study with 2-year follow-up

OBJECTIVES

To assess associations between uCTX-II or uCIIM and severity of hip pain in patients with mild-moderate hip osteoarthritis (OA) over a 2-year period, and establish whether the level of these biomarkers at baseline could estimate a specific trajectory of hip pain.

DESIGN

A cohort study with a 2-year follow-up and 6-monthly measurements of urinary biomarkers (uCTX-II and uCIIM) and symptom severity. Patients were recruited from general practices. The primary outcome was hip pain, measured with the Western Ontario and McMasters University Osteoarthritis Index (WOMAC) subscale and the Visual Analog Scale (VAS). Associations between hip pain and biomarkers were assessed using linear mixed-model analysis for repeated measurements. Five previously identified pain trajectories were used as outcome to investigate whether the level of biomarkers at baseline could estimate membership in one of the trajectories using multinomial regression analysis.

RESULTS

LoguCTX-II and loguCIIM were not associated with WOMAC pain or VAS pain during the 2-year follow-up. Patients in the highly progressive pain trajectory and the moderate pain trajectory were more likely to have a higher loguCTX-II at baseline (OR 6.7; 95% CI 1.6-28.2 and OR 4.8; 95% CI 1.0-22.8, respectively) than patients in the mild pain trajectory.

CONCLUSION

This study shows that in patients with mild-moderate hip OA the urinary biochemical markers uCTX-II and uCIIM are not cross-sectionally associated with hip pain during the 2-year follow-up. Because the uCTX-II level estimated a progressive or moderate hip pain trajectory, this correlation needs to be confirmed in additional patients with hip OA.

Large scale meta-analysis of urinary C-terminal telopeptide, serum cartilage oligomeric protein and matrix metalloprotease degraded type II collagen and their role in prevalence, incidence and progression of osteoarthritis

OBJECTIVE

To evaluate the role of three cartilage-derived biomarkers on osteoarthritis (OA): urinary C-terminal telopeptide (uCTX-II), serum cartilage oligomeric protein (sCOMP), and serum MMP degraded type II collagen (sC2M).

SUBJECTS AND METHODS

Samples from 3582 individuals from the Rotterdam Study, the Genetics osteoArthritis and Progression (GARP), the Chingford Study and the TwinsUK cohort were assayed using enzyme-linked immune sorbent assays. Log10 of concentration levels were correlated with risk of hip, hand and knee OA, hip and knee OA severity and incidence, and progression of knee OA, adjusting for age, gender and body mass index (BMI). Results were meta-analysed to assess overall significance.

RESULTS

After adjusting for covariates, sCOMP was associated with knee OA and hip and knee OA incidence. Furthermore, sC2M was associated with knee OA incidence and progression. After adjustment for multiple tests (Bonferroni P < 0.002) only the association between sCOMP and knee OA remained significant (odds ratio (OR) = 3.26 (95%CI 1.63-10.1) P = 0.0008 for each standard deviation (SD) increase in biomarker levels). Levels of uCTX-II were significantly associated with risk of hand, hip and knee OA, progression and incidence of knee OA. A receiver operating characteristics (ROC) analysis showed a consistent improvement in prediction of knee OA progression from an average area under the curve (AUC) is 0.646 for age, sex and BMI alone to an AUC = 0.668 including uCTX-II for prediction.

CONCLUSIONS

uCTX-II is the most informative biochemical marker for prediction of OA. Both sCOMP and C2M showed some association with OA, thus indicating that they are descriptive of disease activity.

Osteoarthritis--a case for personalized health care?

For both economic and ethical reasons, identification of the optimal treatment for each individual patient is a pressing concern, not only for the patients and their physician, but also health care payers and the pharmaceutical industry. In the field of osteoarthritis (OA) this is of particular relevance, due to the heterogeneity of the disease and the very large number of affected individuals. There is a need to pair the right patients with the right therapeutic modes of action. At present, the clinical trial failures in OA may be a consequence of both bona fide treatment failures and trial failures due to clinical design deficiencies. Tools are needed for characterization and segregation of patients with OA. Key lessons may be learned from advances with another form of arthritis, namely rheumatoid arthritis (RA). Personalized health care (PHC) may be more advantageous for a number of specific indications which are characterized by costly therapy, low response rates and significant problems associated with trial and error prescription, including the risk of serious side effects. We discuss the use of diagnostic practices guiding RA treatment, which may serve as a source of key insights for diagnostic practices in OA. We discuss the emerging concept of PHC, and outline the opportunities and current successes and failures across the RA field, as the OA field collects further data to support the hypothesis. We attempt to outline a possible path forward to assist patients, physicians, payers and the pharmaceutical industry in assuring the 'right' patients are treated with the 'right drug' in OA. Finally we highlight methods for possible segregation of OA patients that would allow identification of patient subtypes, such as OA driven by inflammation that may be ideally suited for PHC and for targeted therapies.

Identification and characterisation of osteoarthritis patients with inflammation derived tissue turnover

OBJECTIVES

Osteoarthritis (OA) is a degenerative disease with a subset of patients experiencing joint inflammation, but C-reactive protein (CRP) has shown limited use in OA as a diagnostic marker. The aim was to identify subpopulations of patients with high or low levels of acute (high sensitive CRP (hsCRP)) and/or matrix metalloproteinase (MMP) derived inflammation (CRPM) and investigate the subpopulations' association with biomarkers of collagen degradation and Kellgren-Lawrence (KL) score.

METHODS

hsCRP, CRPM and MMP-degraded type I, II and III collagen (type I collagen degraded by MMP (C1M), type II collagen degraded by MMP (C2M) and type III collagen degraded by MMP (C3M)) were quantified by enzyme linked immunosorbent assays (ELISA) in serum of 342 patients with symptomatic knee OA of which 60 underwent total knee replacement (TKR). KL was obtained. Patients were divided into quartiles by hsCRP and CRPM levels, where Q1 and Q4 were low or high in both. The biomarker levels of healthy adults provided in the ELISA kits were used as reference level.

RESULTS

hsCRP was elevated in TKR (5.9(3.6-8.2 95% confidence interval (CI)) μg/mL) compared to reference level (3 μg/mL), while CRPM was highly elevated with OA independent of KL (10-14 ng/mL) compared to reference level (5 ng/mL). Q4 had higher KL than Q1 (P < 0.001), Q2 (P = 0.017) and Q3 (P < 0.001). C1M, C2M and C3M were lowest in Q1. C1M was elevated in Q3 compared to Q2 (P < 0.001), whereas C3M was lower (P = 0.019).

CONCLUSION

A bigger proportion of patients were elevated in CRPM compared to hsCRP, indicating MMP-derived inflammation as a component of OA. Moreover, the levels of MMP-degraded collagens differed between the subgroups segregated by inflammation, indicating distinctively different subpopulation selected by inflammation.

The coupling of bone and cartilage turnover in osteoarthritis: opportunities for bone antiresorptives and anabolics as potential treatments?

Osteoarthritis (OA) is the most common form of arthritic disease, and a major cause of disability and impaired quality of life in the elderly. OA is a complex disease of the entire joint, affecting bone, cartilage and synovium that thereby presents multiple targets for treatment. This manuscript will summarise emerging observations from cell biology, preclinical and preliminary clinical trials that elucidate interactions between the bone and cartilage components in particular. Bone and cartilage health are tightly associated. Ample evidence has been found for bone changes during progression of OA including, but not limited to, increased turnover in the subchondral bone, undermineralisation of the trabecular structure, osteophyte formation, bone marrow lesions and sclerosis of the subchondral plate. Meanwhile, a range of investigations has shown positive effects on cartilage health when bone resorption is suppressed, or deterioration of the cartilage when resorption is increased. Known bone therapies, namely oestrogens, selective oestrogen receptor modifiers (SERMs), bisphosphonates, strontium ranelate, calcitonin and parathyroid hormone, might prove useful for treating two critical tissue components of the OA joint, the bone and the cartilage. An optimal treatment for OA likely targets at least these two tissue components. The patient subgroups for whom these therapies are most appropriate have yet to be fully defined but would likely include, at a minimum, those with high bone turnover.

Oral salmon calcitonin attenuates hyperglycaemia and preserves pancreatic beta-cell area and function in Zucker diabetic fatty rats

BACKGROUND AND PURPOSE

Oral salmon calcitonin (sCT), a dual-action amylin and calcitonin receptor agonist, improved glucose homeostasis in diet-induced obese rats. Here, we have evaluated the anti-diabetic efficacy of oral sCT using parameters of glycaemic control and beta-cell morphology in male Zucker diabetic fatty (ZDF) rats, a model of type 2 diabetes.

EXPERIMENTAL APPROACH

Male ZDF rats were treated with oral sCT (0.5, 1.0 or 2 mg·kg(-1) ) or oral vehicle twice daily from age 8 to 18 weeks. Zucker lean rats served as control group. Fasting and non-fasted blood glucose, glycosylated haemoglobin (HbA1c) and levels of pancreas and incretin hormones were determined. Oral glucose tolerance test and i.p. glucose tolerance test were compared, and beta-cell area and function were evaluated.

KEY RESULTS

Oral sCT treatment dose-dependently attenuated fasting and non-fasted hyperglycaemia during the intervention period. At the end of the study period, oral sCT treatment by dose decreased diabetic hyperglycaemia by ∼9 mM and reduced HbA1c levels by 1.7%. Furthermore, a pronounced reduction in glucose excursions was dose-dependently observed for oral sCT treatment during oral glucose tolerance test. In addition, oral sCT treatment sustained hyperinsulinaemia and attenuated hyperglucagonaemia and hypersecretion of total glucagon-like peptide-1 predominantly in the basal state. Lastly, oral sCT treatment dose-dependently improved pancreatic beta-cell function and beta-cell area at study end.

CONCLUSIONS AND IMPLICATIONS

Oral sCT attenuated diabetic hyperglycaemia in male ZDF rats by improving postprandial glycaemic control, exerting an insulinotropic and glucagonostatic action in the basal state and by preserving pancreatic beta-cell function and beta-cell area.

The pathogenesis of osteoarthritis involves bone, cartilage and synovial inflammation: may estrogen be a magic bullet?

The female predominance of polyarticular osteoarthritis (OA), and in particular the marked increase of OA in women after the menopause points to a likely involvement of female sex hormones in the maintenance of cartilage homeostasis. This perception has inspired many research groups to investigate the role of estrogens in the modulation of cartilage homeostasis with the ultimate aim to clarify whether estrogen replacement therapy (ERT) could provide benefits in preventing the rapid rise in the prevalence of OA in postmenopausal women. The effects of ERT and selective estrogen-receptor modulators on the joint in various experimental models have been investigated. Clinically, the effects of estrogens have been evaluated by post hoc analysis in clinical trials using biochemical markers of cartilage and bone degradation. Lastly, the Women's Health Initiative trial (WHI) investigated the effects of estrogens on the joint and joint replacements. Even though the exact mode of action still needs to be elucidated, the effect involves both direct and indirect mechanisms on the whole joint pathophysiology. Several animal models have demonstrated structural benefits of estrogens, as well as significant effects on joint inflammation. This is in complete alignment with clinical data using biochemical markers of joint degradation which demonstrated approximately 50% inhibition of cartilage destruction. These finding were recently validated in WHI, where women taking estrogens had significantly less joint replacement. In conclusion, the pleiotropic effect of estrogens on several different tissues may match the complicated aetiology of OA in some important aspects.

Investigation of two novel biochemical markers of inflammation, matrix metalloproteinase and cathepsin generated fragments of C-reactive protein, in patients with ankylosing spondylitis

OBJECTIVES

Ankylosing spondylitis (AS) is a chronic inflammation of the spine and the sacroiliac joints. Current markers of inflammation, such as C-reactive protein (CRP), are reflecting the production of an acute phase reactant rather than tissue specific inflammation, but the use of CRP as a diagnostic and prognostic marker for AS has not provided the sought accuracy and specificity. We hypothesized that local enzymatic activity in the disease-affected tissue, which is associated with extensive tissue turnover may, by cleavage, modify the CRP produced in the liver. These cleavage products may provide additional information on systemic inflammation as compared to that of full-length CRP. We investigated whether these CRP degradation products would provide additional diagnostic value in AS patients compared to full-length CRP.

METHODS

CRP fragments were identified by mass-spectrometry. Two fragments were selected for ELISA development. One assay exclusively identified a matrix metalloproteinase (MMP) generated fragment, CRP-MMP, whereas the other assay identified a cathepsin generated fragment, CRP-CAT. Full-length CRP, CRP-MMP and CRP-CAT were measured in serum samples from 40 AS patients and 40 sex- and age-matched controls.

RESULTS

Full-length CRP was not elevated in AS patients compared to controls, whereas CRP-MMP was elevated by 25% (p<0.001) and CRP-CAT by 50% (p<0.0001). The Area Under Curve of the Receiver-Operator Characteristic curve of CRP-CAT was the highest with 77%.

CONCLUSIONS

MMP and cathepsin degraded CRP provided more discriminative diagnostic potential compared to that of full-length CRP in this current study. These data suggest that different pools of CRP may provide insight into the inflammation processes in AS.

Post-translational modifications of the extracellular matrix are key events in cancer progression: opportunities for biochemical marker development

The aim of this review is to discuss the potential usefulness of a novel class of biochemical markers, designated neoepitopes. Neoepitopes are post-translational modifications (PTMs) of proteins and are derived by processes, such as protease cleavage, citrullination, nitrosylation, glycosylation and isomerization. Each PTM results from a specific local physiological or pathobiological process. Identification of each modification to a tissue-specific protein may reveal a unique disease-specific biochemical marker. During cancer metastasis, the host tissue is extensively degraded and replaced by cancer-associated extracellular matrix (ECM) proteins. Furthermore, severe cellular stress and inflammation, caused by cancer, results in generation of PTMs, which will be distributed throughout the ECM. This gives rise to release of protein-specific fragments to the circulation. Here we highlight the importance of remodeling of the ECM in cancer and the generation of PTMs, which may be cancer specific and reflect disease progression; thus having potential for biochemical marker development.

Biochemical markers identify influences on bone and cartilage degradation in osteoarthritis--the effect of sex, Kellgren-Lawrence (KL) score, body mass index (BMI), oral salmon calcitonin (sCT) treatment and diurnal variation

Background

Osteoarthritis (OA) involves changes in both bone and cartilage. These processes might be associated under some circumstances. This study investigated correlations between bone and cartilage degradation in patients with OA as a function of sex, Kellgren-Lawrence (KL) score, Body Mass Index (BMI), oral salmon calcitonin (sCT) treatment and diurnal variation.

Methods

This study was a 2-week, double-blind, double-dummy, randomized study including 37 postmenopausal women and 36 men, aged 57-75 years, with painful knee OA, and a KL-score of I - III. Subjects were allocated to one of three treatment arms: 0.6 mg or 0.8 mg oral sCT, or placebo given twice-daily for 14 days. Correlations between gender, KL score, or BMI and the bone resorption marker, serum C-terminal telopeptide of collagen type I (CTX-I), or the cartilage degradation marker, urine C-terminal telopeptide of collagen type II (CTX-II) were investigated.

Results

At baseline, biomarkers indicated women with OA experienced higher bone and cartilage degradation than men. CTX-I levels were significantly higher, and CTX-II levels only marginally higher, in women than in men (p = 0.04 and p = 0.06, respectively). Increasing KL score was not correlated with bone resorption, but was significantly associated with the cartilage degradation CTX-II marker in both men and women (p = 0.007). BMI was significantly and negatively correlated to the bone resorption marker CTX-I, r = -0.40 (p = 0.002), but showed only a borderline positive correlation to CTX-II, r = 0.25 (p = 0.12). Before morning treatments on days 1 and 14, no correlation was seen between CTX-I and CTX-II in either the sCT or placebo group. However, oral sCT and food intake induced a clear correlation between these bone and cartilage degradation markers. Four hours after the first sCT dose on treatment days 1 and 14, a significant correlation (r = 0.71, p < 0.001) between changes in both CTX-I and CTX-II was seen. In the placebo group a weakly significant correlation between changes in both markers was found on day 1 (r = 0.49, p = 0.02), but not on day 14.

Conclusion

Bone resorption was higher in females than males, while cartilage degradation was correlated with increasing KL-score and only weakly associated with BMI. Bone and cartilage degradation were not correlated in untreated individuals, but dosing with oral sCT with or without food, and a mid-day meal, decreased bone and cartilage degradation and induced a correlation between both markers. Changes in bone and cartilage markers may aid in the identification of potential new treatment opportunities for OA.

Trial Registration

Clinical trial registration number (EUDRACT2006-005532-24 & NCT00486369)