Association between concentrations of urinary type II collagen neoepitope (uTIINE) and joint space narrowing in patients with knee osteoarthritis

Progress and challenges in the use of blood biomarkers in relapsing polychondritis

Relapsing polychondritis (RP) is a rare inflammatory disease with significant individual heterogeneity that involves systemic organs. The diagnosis of RP mainly depends on the clinical manifestations; currently, there are no molecular biomarkers routinely evaluated in clinical practice. Biomarkers have diagnostic or monitoring values and can predict response to treatment or the disease course. Over the years, many biomarkers have been proposed to facilitate diagnosis and prognosis. Unfortunately, ideal biomarkers to diagnose RP have not yet been discovered. Most of the molecular biomarkers in RP are immunological biomarkers, with autoantibodies and proteins related to cartilage damage in the blood being the most common. Alterations in some genes (HLA typing and UBA1 somatic mutation) were detected in patients with RP, which could serve as a potential biomarker for the diagnosis of RP. Moreover, proinflammatory cytokines and lymphocyte levels, and certain laboratory tests, have certain values of RP diagnosis and disease activity assessment but lack specificity and sensitivity. This review describes the different types of biomarkers and their clinical correlation with respect to the diagnosis of RP and disease activity. Research on biomarkers and disease pathology is ongoing to identify the ideal biomarkers that are sensitive and specific for RP.

Blood and urine biomarkers in osteoarthritis - an update on cartilage associated type II collagen and aggrecan markers

PURPOSE OF REVIEW

Osteoarthritis (OA) is a painful disease for which drug development has proven difficult. One major reason for this is the heterogeneity of the disease and the current lack of operationalized means to distinguish various disease endotypes (molecular subtypes). Biomarkers measured in blood or urine, reflecting joint tissue turnover, have been developed and tested during the last decades. In this narrative review, we provide highlights on biomarkers derived from the two most studied and abundant cartilage proteins - type II collagen and aggrecan.

RECENT FINDINGS

Multiple biomarkers assessing type II collagen degradation and formation, and aggrecan turnover have been developed. Several markers, such as uCTX-II, have been validated for their association with disease severity and prognosis, as well as pharmacodynamically used to describe the mode of action and efficacy of drugs in development. There is a great need for biomarkers for subdividing patients (i.e., endotyping) and recent scientific advances have not yet come closer to achieving this goal.

SUMMARY

There is strong support for using biomarkers for understanding OA, reflecting degradation and formation of the joint tissues, focused on type II collagen and aggrecan. There is still a lack of in vitro diagnostics, in all contexts of use.

Proteomics in the pharmaceutical and biotechnology industry: a look to the next decade

INTRODUCTION

Pioneering technologies such as proteomics have helped fuel the biotechnology and pharmaceutical industry with the discovery of novel targets and an intricate understanding of the activity of therapeutics and their various activities in vitro and in vivo. The field of proteomics is undergoing an inflection point, where new sensitive technologies are allowing intricate biological pathways to be better understood, and novel biochemical tools are pivoting us into a new era of chemical proteomics and biomarker discovery. In this review, we describe these areas of innovation, and discuss where the fields are headed in terms of fueling biotechnological and pharmacological research and discuss current gaps in the proteomic technology landscape.

AREAS COVERED

Single cell sequencing and single molecule sequencing. Chemoproteomics. Biological matrices and clinical samples including biomarkers. Computational tools including instrument control software, data analysis.

EXPERT OPINION

Proteomics will likely remain a key technology in the coming decade, but will have to evolve with respect to type and granularity of data, cost and throughput of data generation as well as integration with other technologies to fulfill its promise in drug discovery.

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.

Biomarkers of cartilage and surrounding joint tissue

The identification and clinical demonstration of efficacy and safety of osteo- and chondro-protective drugs are met with certain difficulties. During the last few decades, the pharmaceutical industry has, in the field of rheumatology, experienced disappointments associated with the development of disease modification. Today, the vast amount of patients suffering from serious, chronic joint diseases can only be offered treatments aimed at improving symptoms, such as pain and acute inflammation, and are not aimed at protecting the joint tissue. This huge, unmet medical need has been the driver behind the development of improved analytical techniques allowing better and more efficient clinical trial design, implementation and analysis. With this review, we aim to provide a brief and general overview of biochemical markers of joint tissue, with special focus on neoepitopes. Furthermore, we highlight recent studies applying biochemical markers in joint degenerative diseases. These disorders, including osteoarthritis, rheumatoid arthritis and spondyloarthropathies, are the most predominant disorders in Europe and the USA, and have enormous socioeconomical impact.

Coupling immunoaffinity techniques with MS for quantitative analysis of low-abundance protein biomarkers

The field of proteomics is rapidly turning towards targeted mass spectrometry (MS) methods to quantify putative markers or known proteins of biological interest. Historically, the enzyme-linked immunosorbent assay (ELISA) has been used for targeted protein analysis, but, unfortunately, it is limited by the excessive time required for antibody preparation, as well as concerns over selectivity. Despite the ability of proteomics to deliver increasingly quantitative measurements, owing to limited sensitivity, the leads generated are in the microgram per milliliter range. This stands in stark contrast to ELISA, which is capable of quantifying proteins at low picogram per milliliter levels. To bridge this gap, targeted liquid chromatography (LC) tandem MS (MS/MS) analysis of tryptic peptide surrogates using selected reaction monitoring detection has emerged as a viable option for rapid quantification of target proteins. The precision of this approach has been enhanced by the use of stable isotope-labeled peptide internal standards to compensate for variation in recovery and the influence of differential matrix effects. Unfortunately, the complexity of proteinaceous matrices, such as plasma, limits the usefulness of this approach to quantification in the mid-nanogram per milliliter range (medium-abundance proteins). This article reviews the current status of LC/MS/MS using selected reaction monitoring for protein quantification, and specifically considers the use of a single antibody to achieve superior enrichment of either the protein target or the released tryptic peptide. Examples of immunoaffinity-assisted LC/MS/MS are reviewed that demonstrate quantitative analysis of low-abundance proteins (subnanogram per milliliter range). A strategy based on this technology is proposed for the expedited evaluation of novel protein biomarkers, which relies on the synergy created from the complementary nature of MS and ELISA.

CIINE Reflects Collagenase-Specific CII Breakdown in Cartilage Explant and Whole Body of Canine

To evaluate collagenase inhibitors for the treatment of osteoarthritis and to correlate them with clinical pathology, canine cartilage explant and anterior cruciate ligament transection (ACLT) models were examined by quantifying the CII neoepitope (CIINE). This peptide is a putative marker for collagenase-specific type II collagen (CII) degradation, which is a critical step in osteoarthritis pathology.

The concentration of CIINE in supernatants of canine cartilage explants showed increase upon IL-1β—stimulation and collagenase inhibitors suppressed this elevation of CIINE. In the canine ACLT model, levels of CIINE in urine (uCIINE) increased as lesions of knee joint cartilage developed and decreased in response to collagenase inhibitors.

Our results suggest that CIINE reflects collagenase-specific CII degradation in canine explants and whole bodies. It is anticipated that these data will establish a tool for clarifying and bridging the efficacy and mechanism of collagenase inhibitors at the preclinical stage of drug discovery.

Injectable hyaluronic-acid-doxycycline hydrogel therapy in experimental rabbit osteoarthritis

Background

Osteoarthritis (OA) is a common joint disease that causes disabilities in elderly adults. However, few long-lasting pharmacotherapeutic agents with low side effects have been developed to treat OA. We evaluated the therapeutic effects of intra-articular injections of hydrogels containing hyaluronic acid (HA) and doxycycline (DOX) in a rabbit OA model.

Results

Thirteen week old New Zealand White rabbits undergone a partial meniscectomy and unilateral fibular ligament transection were administered with either normal saline (NT), HA, DOX or HA-DOX hydrogels on day 0, 3, 6, 9 and 12; animals were also examined the pain assessment in every three days. The joint samples were taken at day 14 post-surgery for further histopathological evaluation. The degree of pain was significantly attenuated after day 7 post-treatment with both HA and HA-DOX hydrogels. In macroscopic appearance, HA-DOX hydrogel group showed a smoother cartilage surface, no or minimal signs of ulceration, smaller osteophytes, and less fissure formation in compare to HA or DOX treatment alone. In the areas with slight OA changes, HA-DOX hydrogel group exhibited normal distribution of chondrocytes, indicating the existence of cartilage regeneration. In addition, HA-DOX hydrogels also ameliorated the progression of OA by protecting the injury of articular cartilage layer and restoring the elastoviscosity.

Conclusion

Overall, from both macroscopic and microscopic data of this study indicate the injectable HA-DOX hydrogels presented as a long-lasting pharmacotherapeutic agent to apply for OA therapy.

Doxycycline for osteoarthritis of the knee or hip

BACKGROUND

Osteoarthritis is a chronic joint disease that involves degeneration of articular cartilage. Pre-clinical data suggest that doxycycline might act as a disease-modifying agent for the treatment of osteoarthritis, with the potential to slow cartilage degeneration. This is an update of a Cochrane review first published in 2009.

OBJECTIVES

To examine the effects of doxycycline compared with placebo or no intervention on pain and function in people with osteoarthritis of the hip or knee.

SEARCH METHODS

We searched CENTRAL (The Cochrane Library 2008, issue 3), MEDLINE, EMBASE and CINAHL up to 28 July 2008, with an update performed at 16 March 2012. In addition, we checked conference proceedings, reference lists, and contacted authors.

SELECTION CRITERIA

We included studies if they were randomised or quasi-randomised controlled trials that compared doxycycline at any dosage and any formulation with placebo or no intervention in people with osteoarthritis of the knee or hip.

DATA COLLECTION AND ANALYSIS

We extracted data in duplicate. We contacted investigators to obtain missing outcome information. We calculated differences in means at follow-up between experimental and control groups for continuous outcomes and risk ratios (RR) for binary outcomes.

MAIN RESULTS

We identified one additional trial (232 participants) and included two trials (663 participants) in this update. The methodological quality and the quality of reporting were considered moderate. At end of treatment, clinical outcomes were similar between the two treatment groups, with an effect size of -0.05 (95% confidence interval (CI) -0.22 to 0.13), corresponding to a difference in pain scores between doxycycline and control of -0.1 cm (95% CI -0.6 to 0.3 cm) on a 10-cm visual analogue scale, or 32% versus 29% improvement from baseline (difference 3%; 95% CI -5% to 10%). The effect size for function was -0.07 (95% CI -0.25 to 0.10), corresponding to a difference between doxycycline and control of -0.2 (95% CI -0.5 to 0.2) on the Western Ontario and McMaster Universities Arthritis Index (WOMAC) disability subscale with a range of 0 to 10, or 24% versus 21% improvement (difference 3%; 95% CI -3% to 10%). The difference in changes in minimum joint space narrowing assessed in one trial was in favour of doxycycline (-0.15 mm; 95% CI -0.28 to -0.02 mm), which corresponds to a small effect size of -0.23 standard deviation units (95% CI -0.44 to -0.02). More participants withdrew from the doxycycline group compared with placebo due to adverse events (RR 2.28; 95% CI 1.06 to 4.90). There was no evidence that participants in the doxycycline group experienced more serious adverse events than those in the placebo group, but the estimate was imprecise (RR 1.07; 95% CI 0.68 to 1.68).

AUTHORS' CONCLUSIONS

In this update, the strength of evidence for effectiveness outcomes was improved from low to moderate and we confirmed that the symptomatic benefit of doxycycline is minimal to non-existent, while the small benefit in terms of joint space narrowing is of questionable clinical relevance and outweighed by safety problems. The CIs of the summary estimates now exclude any clinically relevant difference in improvement of symptoms and the small benefit in terms of joint space narrowing does not outweigh the harms.

Biological markers in osteoarthritis

Osteoarthritis (OA) is considered as a chronic disease with a long "silent" period. The diagnosis is generally based on clinical symptoms and radiographic changes. However X-ray has a poor sensitivity and a relatively large precision error that does not allow an early detection of OA or the monitoring of joint damage progression. The limitations of the tools that are currently available for OA assessment have been the impetus to identify specific biological markers that reflect quantitative and dynamic variations in joint remodeling. Research has focused on the structural components of cartilage matrix, especially type II collagen degradation markers. In spite of a significant increase of some markers in individuals with early stage of OA, the large overlap with control subjects indicates that the current biomarkers used alone have limited diagnostic potential. However, the combination of specific markers seems to improve the prediction of disease progression at the individual level. Several types of treatment have been investigated but the lack of medications with definitively demonstrated chondroprotective activity has limited the assessment of the potential role of biomarkers for monitoring patients' responses to the treatment of OA. In this review, we will use the BIPED classification that appeared in 2006 for OA markers to describe the potential usage of a given marker [5]. This article is part of a Special Issue entitled "Osteoarthritis".

Application of biomarkers in the development of drugs intended for the treatment of osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a chronic and slowly progressive disease for which biomarkers may be able to provide a more rapid indication of therapeutic responses to therapy than is currently available; this could accelerate and facilitate OA drug discovery and development programs. The goal of this document is to provide a summary and guide to the application of in vitro (biochemical and other soluble) biomarkers in the development of drugs for OA and to outline and stimulate a research agenda that will further this goal.

METHODS

The Biomarkers Working Group representing experts in the field of OA biomarker research from both academia and industry developed this consensus document between 2007 and 2009 at the behest of the Osteoarthritis Research Society International Federal Drug Administration initiative (OARSI FDA initiative).

RESULTS

This document summarizes definitions and classification systems for biomarkers, the current outcome measures used in OA clinical trials, applications and potential utility of biomarkers for development of OA therapeutics, the current state of qualification of OA-related biomarkers, pathways for biomarker qualification, critical needs to advance the use of biomarkers for drug development, recommendations regarding practices and clinical trials, and a research agenda to advance the science of OA-related biomarkers.

CONCLUSIONS

Although many OA-related biomarkers are currently available they exist in various states of qualification and validation. The biomarkers that are likely to have the earliest beneficial impact on clinical trials fall into two general categories, those that will allow targeting of subjects most likely to either respond and/or progress (prognostic value) within a reasonable and manageable time frame for a clinical study (for instance within 1-2 years for an OA trial), and those that provide early feedback for preclinical decision-making and for trial organizers that a drug is having the desired biochemical effect. As in vitro biomarkers are increasingly investigated in the context of specific drug treatments, advances in the field can be expected that will lead to rapid expansion of the list of available biomarkers with increasing understanding of the molecular processes that they represent.

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.

Enzyme-linked immunosorbent assay (ELISAs) for metalloproteinase derived type II collagen neoepitope, CIIM--increased serum CIIM in subjects with severe radiographic osteoarthritis

OBJECTIVES

In joint degenerative diseases, the collagens are degraded by matrix metalloproteinases and protein fragments are released to serum as potential biomarkers.

METHODS

A collagen type II specific neoepitope, CIIM, was identified (…RDGAAG(1053)) by mass spectrometry. Two ELISAs against the neoepitope were developed. CIIM was measured in cartilage explants in the presence or absence of protease inhibitors. CIIM was measured in OA synovial fluid (n=51) and serum (n=156). Knee OA was graded by standard Kellgren-Lawrence (KL) score.

RESULTS

The ELISAs showed good technical performance; CV%, <13%. CIIM release from cartilage explants was blocked by the MMP inhibitor. CIIM was detected in synovial fluid. Furthermore, serum CIIM levels were significantly higher (P<0.05) in those individuals with mild or severe OA than in those with no OA.

CONCLUSION

We developed a new biomarker for joint degenerative diseases, which we demonstrated was derived from MMP-degraded type II collagen.

Association between synovial fluid levels of aggrecan ARGS fragments and radiographic progression in knee osteoarthritis

Introduction

Aggrecanase cleavage at the ³⁹²Glu-³⁹³Ala bond in the interglobular domain (IGD) of aggrecan, releasing N-terminal ³⁹³ARGS fragments, is an early key event in arthritis and joint injuries. We determined whether synovial fluid (SF) levels of ARGS-aggrecan distinguish subjects with progressive radiographic knee osteoarthritis (ROA) from those with stable or no ROA.

Methods

We studied 141 subjects who, at examination A, had been given meniscectomies an average of 18 years earlier (range, 15 to 22 years). Seventeen individuals without surgery, and without known injury to the menisci or cruciate ligaments, were used as references. At examinations A and B, with a mean follow-up time of 7.5 years, we obtained SF and standing tibiofemoral and skyline patellofemoral radiographs. SF ARGS-aggrecan was measured with an electrochemiluminescence immunoassay, and we graded radiographs according to the OARSI atlas. The association between SF ARGS levels at examination A and progression of radiographic features of knee OA between examinations A and B was assessed by using logistic regression adjusted for age, gender, body mass index, and time between examinations, and stratified by ROA status at examination A.

Results

We found a weak negative association between SF ARGS concentrations and loss of joint space: the likelihood of progression of radiographic joint space narrowing decreased 0.9 times per picomole per milliliter increase in ARGS (odds ratio (OR) 0.89; 95% confidence interval (CI), 0.79 to 0.996). In subjects with and without preexisting ROA at examination A, the association was OR, 0.96; 0.81 to 1.13; and 0.77; 0.62 to 0.95, respectively. Average levels of SF ARGS 18 years after meniscectomy were no different from those of reference subjects and were not correlated to radiographic status at examination A.

Conclusions

In subjects with previous knee meniscectomy but without ROA, levels of SF ARGS-aggrecan were weakly and inversely associated with increased loss of joint space over a period of 7.5 years.

Cartilage degradation biomarkers predict efficacy of a novel, highly selective matrix metalloproteinase 13 inhibitor in a dog model of osteoarthritis: confirmation by multivariate analysis that modulation of type II collagen and aggrecan degradation peptides parallels pathologic changes

OBJECTIVE

To demonstrate that the novel highly selective matrix metalloproteinase 13 (MMP-13) inhibitor PF152 reduces joint lesions in adult dogs with osteoarthritis (OA) and decreases biomarkers of cartilage degradation.

METHODS

The potency and selectivity of PF152 were evaluated in vitro using 16 MMPs, TACE, and ADAMTS-4 and ADAMTS-5, as well as ex vivo in human cartilage explants. In vivo effects were evaluated at 3 concentrations in mature beagles with partial medial meniscectomy. Gross and histologic changes in the femorotibial joints were evaluated using various measures of cartilage degeneration. Biomarkers of cartilage turnover were examined in serum, urine, or synovial fluid. Results were analyzed individually and in combination using multivariate analysis.

RESULTS

The potent and selective MMP-13 inhibitor PF152 decreased human cartilage degradation ex vivo in a dose-dependent manner. PF152 treatment of dogs with OA reduced cartilage lesions and decreased biomarkers of type II collagen (type II collagen neoepitope) and aggrecan (peptides ending in ARGN or AGEG) degradation. The dose required for significant inhibition varied with the measure used, but multivariate analysis of 6 gross and histologic measures indicated that all doses differed significantly from vehicle but not from each other. Combined analysis of cartilage degradation markers showed similar results.

CONCLUSION

This highly selective MMP-13 inhibitor exhibits chondroprotective effects in mature animals. Biomarkers of cartilage degradation, when evaluated in combination, parallel the joint structural changes induced by the MMP-13 inhibitor. These data support the potential therapeutic value of selective MMP-13 inhibitors and the use of a set of appropriate biomarkers to predict efficacy in OA clinical trials.

Design and validation of an immunoaffinity LC-MS/MS assay for the quantification of a collagen type II neoepitope peptide in human urine: application as a biomarker of osteoarthritis

Biomarkers play an increasingly important role for drug efficacy and safety evaluation in all stages of drug development. It is especially important to develop and validate sensitive and selective biomarkers for diseases where the onset of the disease is very slow and/or the disease progression is hard to follow, i.e., osteoarthritis (OA). The degradation of Type II collagen has been associated with the disease state of OA. Matrix metalloproteinases (MMPs) are enzymes that catalyze the degradation of collagen and therefore pursued as potential targets for the treatment of OA. Peptide biomarkers of MMP activity related to type II collagen degradation were identified and the presence of these peptides in MMP digests of human articular cartilage (HAC) explants and human urine were confirmed. An immunoaffinity LC/MS/MS assay for the quantification of the most abundant urinary type II collagen neoepitope (uTIINE) peptide, a 45-mer with 5 HO-proline residues was developed and clinically validated. The assay has subsequently been applied to analyze human urine samples from clinical studies. We have shown that the assay is able to differentiate between symptomatic OA and normal subjects, indicating that uTIINE can be used as potential biomarker for OA. This chapter discusses the assay procedure and provides information on the validation experiments used to evaluate the accuracy, precision, and selectivity data with attention to the specific challenges related to the quantification of endogenous protein/peptide biomarker analytes. The generalized approach can be used as a follow-up to studies whereby proteomics-based urinary biomarkers are identified and an assay needs to be developed. Considerations for the validation of such an assay are described.

Biochemical markers of joint tissue turnover

Recent disappointments in late stage developments of anti-osteoarthritic drugs have reinforced efforts to develop better biomarkers for application in both the drug development process as well as in the routine management of these patients. Here we provide a brief review of biochemical tests available for the study of tissue turnover in each of the three compartments of the articular joint, that is the bone, the cartilage, and the synovium. Finally, we provide some perspective to future developments in biomarker discovery and discuss the potential impact such technologies could have on the drug development process.

Proteomics role in the search for improved diagnosis, prognosis and treatment of osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is the most common rheumatic pathology. It is related to aging and is characterized primarily by cartilage degradation. Despite its high prevalence, the diagnostic methods currently available are limited and lack sensitivity. The focus of this review is the application of proteomic technologies in the search of new biomarkers for improved diagnosis, prognosis and treatment of OA.

METHODS

This review focuses on the utilization of proteomics in OA biomarker research to enable early diagnosis, improved prognosis and the application of tailored treatments.

RESULTS

New diagnostic tests for OA are urgently needed and would also promote the development of alternative therapeutic strategies. Considering that OA involves different tissues and complex biological processes, the most promising diagnostic approach would be the study of combinations of biomarkers. New experimental approaches for the identification and validation of OA biomarkers have recently emerged and include proteomic technologies. These techniques allow the simultaneous analysis of multiple markers and become a very powerful tool for both biomarker discovery and validation.

CONCLUSIONS

Improvements in proteomics technology will undoubtedly lead to advances in characterizing new OA biomarkers and developing alternative therapies. Even so, further work is required to enhance the performance and reproducibility of proteomics tools before they can be routinely used in clinical trials and practice.

Selective MMP13 inhibitors

Pharmacology of MMP13 and MMP13 selective inhibitors is reviewed.

Discovery of (pyridin-4-yl)-2H-tetrazole as a novel scaffold to identify highly selective matrix metalloproteinase-13 inhibitors for the treatment of osteoarthritis

Potent, highly selective and orally-bioavailable MMP-13 inhibitors have been identified based upon a (pyridin-4-yl)-2H-tetrazole scaffold. Co-crystal structure analysis revealed that the inhibitors bind at the S(1)(') active site pocket and are not ligands for the catalytic zinc atom. Compound 29b demonstrated reduction of cartilage degradation biomarker (TIINE) levels associated with cartilage protection in a preclinical rat osteoarthritis model.

Doxycycline for osteoarthritis of the knee or hip

BACKGROUND

Osteoarthritis is a chronic joint disease that involves degeneration of articular cartilage. Pre-clinical data suggest that doxycycline might act as a disease-modifying agent for the treatment of osteoarthritis, with the potential to slow cartilage degeneration.

OBJECTIVES

To examine the effects of doxycycline compared with placebo or no intervention on pain and function in patients with osteoarthritis of the hip or knee.

SEARCH STRATEGY

We searched CENTRAL ( The Cochrane Library 2008, issue 3), MEDLINE, EMBASE and CINAHL up to 28 July 2008, checked conference proceedings, reference lists, and contacted authors.

SELECTION CRITERIA

We included studies if they were randomised or quasi-randomised controlled trials that compared doxycycline at any dosage and any formulation with placebo or no intervention in patients with osteoarthritis of the knee or hip.

DATA COLLECTION AND ANALYSIS

We extracted data in duplicate. We contacted investigators to obtain missing outcome information. We calculated differences in means at follow-up between experimental and control groups for continuous outcomes and risk ratios for binary outcomes.

MAIN RESULTS

We found one randomised controlled trial that compared doxycycline with placebo in 431 obese women. After 30 months of treatment, clinical outcomes were similar between the two treatment groups, with a mean difference of -0.20 cm (95% confidence interval (CI) -0.77 to 0.37 cm) on a visual analogue scale from 0 to 10 cm for pain and -1.10 units (95% CI -3.86 to 1.66) for function on the WOMAC disability subscale, which ranges from 17 to 85. These differences correspond to clinically irrelevant effect sizes of -0.08 and -0.09 standard deviation units for pain and function, respectively. The difference in changes in minimum joint space narrowing was in favour of doxycycline (-0.15 mm, 95% CI -0.28 to -0.02 mm), which corresponds to a small effect size of -0.23 standard deviation units. More patients withdrew from the doxycycline group compared with placebo due to adverse events (risk ratio 1.69, 95% CI 1.03 to 2.75).

AUTHORS' CONCLUSIONS

The symptomatic benefit of doxycycline is minimal to non-existent. The small benefit in terms of joint space narrowing is of questionable clinical relevance and outweighed by safety problems. Doxycycline should not be recommended for the treatment of osteoarthritis of the knee or hip.

Biomarkers in the development of novel disease-modifying therapies for osteoarthritis

Identification and utilization of biomarkers is vitally important for the successful development of disease-modifying osteoarthritis drugs. Biochemical and imaging platforms hold great promise to deliver such biomarkers. Studies indicate a marked increase in biochemical products arising from the breakdown and biosynthesis of collagen, extracellular matrix and bone in osteoarthritis. These molecules have been associated with disease severity and may also have prognostic value as indicators of disease progression. However, issues including biological variability and lack of tissue specificity currently hinder the utility of these molecular markers in drug development. Imaging technologies hold great potential for sensitive and accurate measurement of disease-related structural damage. Drawbacks, including expense, need for validation and limited accessibility also limit the utility of these technologies. In this article, the potential value and challenges in developing and utilizing biomarkers in disease-modifying osteoarthritis drug development will be discussed.

Type II collagen markers in osteoarthritis: what do they indicate?

PURPOSE OF REVIEW

We provide a critical review of recent in-vitro, animal and human clinical studies on type II collagen biomarkers. In describing the human studies, we have applied the BIPED (burden of disease, investigative, prognostic, efficacy of intervention, and diagnostic) classification scheme recently proposed by the Osteoarthritis Biomarkers Network (a consortium of five US National Institutes of Health designated sites). Based on this analysis, we propose an update to the classification of the type II collagen biomarkers.

RECENT FINDINGS

Various type II collagen epitopes have been described as potential biomarkers for osteoarthritis. Some have demonstrated ability in the following areas: classification of individuals as either diseased or nondiseased; assessment of severity or extent of osteoarthritis; prediction of future onset of osteoarthritis among those without osteoarthritis at baseline or the progression of osteoarthritis among those with existing disease; and monitoring treatment efficacy.

SUMMARY

Type II collagen biomarkers provide useful information for clinical and research applications. Furthermore, they are promising tools for the monitoring the influence of drug treatment on cartilage metabolism in joint diseases such as osteoarthritis.

Monitoring cartilage turnover

In arthritic diseases, the stability of the extracellular matrix of articular cartilage is compromised by extensive proteolytic breakdown associated with alterations of synthesis of the proteins of the tissue leading to cartilage loss. This article reviews developments in assays of biochemical markers of cartilage matrix turnover and studies investigating their use. Because type II collagen and aggrecan are the most abundant proteins of the cartilage matrix, current biochemical markers are based mainly on immunologic reagents detecting their synthesis and degradation. Clinical studies indicate that some markers of type II collagen may be useful to predict disease progression in osteoarthritis and rheumatoid arthritis. Conversely, major achievements have been made in the development of immunoassays detecting the various fragments of aggrecan released by matrix metalloproteases or aggrecanases, but their use has been limited mostly to investigating cartilage turnover in ex vivo experiments. Because of the complexity of the mechanisms involved in arthritic joint damage, only a combination of different biochemical markers reflecting the various aspects of synthesis and degradation of matrix molecules will likely provide efficient cartilage turnover monitoring.

Clinical validation of an immunoaffinity LC-MS/MS assay for the quantification of a collagen type II neoepitope peptide: A biomarker of matrix metalloproteinase activity and osteoarthritis in human urine

The degradation of type II collagen has been associated with the pathology of osteoarthritis (OA). Matrix metalloproteinases (MMPs) are enzymes that are responsible for catalyzing the degradation of collagen and, therefore, are pursued as potential targets for the treatment of OA. Collagen-derived peptides identified as a reflection of in vivo MMP activity have been investigated as target biomarkers of MMP activity as well as potential biomarkers of OA disease state and/or progression. An immunoaffinity liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay developed for the quantification of the most abundant urinary type II collagen neoepitope (uTIINE) peptide, a 45-mer with 5 HO-proline residues resulting from MMP-13-catalyzed degradation, was validated for clinical use. Validation experiments were designed with attention to specific challenges related to quantification of endogenous analytes. The validated method is sensitive, selective, accurate (<15% relative error) and precise (<15% coefficient of variation) over a linear range of 0.156-7.50 ng/ml. Sample stability and inter- and intrasubject variability were evaluated in the urine of normal and OA populations. The method was applied to analyze human urine samples from clinical studies investigating the utility of uTIINE as a potential biomarker for OA.

Discovery and development of a type II collagen neoepitope (TIINE) biomarker for matrix metalloproteinase activity: from in vitro to in vivo

Destruction of cartilage by matrix metalloproteinases (MMPs) plays a significant role in the pathology of osteoarthritis (OA). A translatable biomarker of MMP activity would enable development of MMP inhibitors for the treatment of OA and potentially the improved diagnosis of OA. A directed approach to identifying specific MMP cleavage products as potential biomarkers has been undertaken. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify peptides generated by MMP-driven degradation of human articular cartilage (HAC) in vivo. It was shown that a 45-mer peptide fragment of collagen type II with five hydroxyprolines (OH) can be selectively produced by the activity of collagenase, an enzyme purported to be involved in the pathology of OA. This 45-mer is the most abundant neoepitope peptide found in biological fluids such as urine and synovial fluid. An immunoaffinity LC-MS/MS assay has been developed to quantify collagen type II neoepitope peptides as biomarkers of collagenase modulation. The lower limit of quantification for this assay was established to be 0.035 nM. The assay was used to measure the levels of collagen type II peptides in the urine of both clinical (healthy human subjects) and preclinical species. The urinary levels of the most abundant peptides are reported for rat, rabbit, guinea pig, dog, and healthy human adult subjects. The utility of this peptide to monitor collagenase activity in vivo has been demonstrated through its detailed characterization in HAC explants as well as in the urine of human and other preclinical species.