Cartilage degradation products as markers for evaluation of patients with rheumatic disease

Effect of mud compress therapy on cartilage destruction detected by CTX-II in patients with knee osteoarthritis

BACKGROUND/OBJECTIVE

The aim of this study is to investigate the effect of mud compress (MC) therapy compared to hot pack (HP) therapy on cartilage destruction and subchondral bone alterations detected by urine levels of C telopeptide fragment of collagen type-II (uCTX-II) in patients with knee osteoarthritis (OA).

METHODS

Fifty-nine patients between 49-74 years of age with bilateral knee OA divided into 2 groups. Twenty-five patients (16 females, 9 males) and 34 patients (22 females, 13 males) were given HP versus local natural organic and mineral-rich MC therapy respectively for 2 weeks as a total of 12 sessions. uCTX-II, Visual Analog Scale (VAS), 15 m walking time, Western Ontario and McMaster Universities multifunctional (WOMAC) index were measured at baseline, after-treatment and 3 months after treatment.

RESULTS

uCTX-II level did not show any difference between the two groups, however it decreased significantly in MC and HP groups 3 months after treatment (p< 0.017). WOMAC stiffness sore was significantly lower in MC group 3 months after treatment (p< 0.05). Both MC and HP therapies lowered VAS, WOMAC total and subscores significantly up to 3 months (p< 0.017).

CONCLUSIONS

HP and MC therapies for OA of knee are not superior to one another with respect to the level of uCTX-II. MC may probably decrease the ongoing cartilage destruction and related subchonral bone interactions earlier compared to HP treatment in patients with knee OA as evidenced by decreased uCTX-II levels after-treatment.

Application of biomarkers in the clinical development of new drugs for chondroprotection in destructive joint diseases: a review

Emerging evidence supports the concept that biochemical markers are clinically useful non-invasive diagnostic tools for the monitoring of changes in cartilage turnover in patients with destructive joint diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA). Epidemiological studies demonstrated that measurements of different degradation products of proteins in the extracellular matrix of hyaline cartilage in urine or serum samples are (1) increased in OA or RA patients compared with healthy individuals, (2) correlate with disease activity, and (3) are predictive for the rate of changes in radiographic measures of cartilage loss. The present review provides an updated list of available biomarkers and summarize the research data arguing for their clinical utility. In addition, it addresses the question whether or not the monitoring of biomarkers during different treatment modalities could be a useful approach to characterize the chondro-protective effects of approved and candidate drugs. Finally, it briefly reviews the in vitro/ex vivo experimental settings - isolated chondrocyte cultures and articular cartilage explants - that can assist in the verification of novel markers, but also studies assessing direct effects of drug candidates on chondrocytes. Collectively, biomarkers may acquire a function as established efficacy parameters in the clinical development of novel chondro-protective agents.

Cartilage in normal and osteoarthritis conditions

The preservation of articular cartilage depends on keeping the cartilage architecture intact. Cartilage strength and function depend on both the properties of the tissue and on their structural parameters. The main structural macromolecules are collagen and proteoglycans (aggrecan). During life, cartilage matrix turnover is mediated by a multitude of complex autocrine and paracrine anabolic and catabolic factors. These act on the chondrocytes and can lead to repair, remodeling or catabolic processes like those that occur in osteoarthritis. Osteoarthritis is characterized by degradation and loss of articular cartilage, subchondral bone remodeling, and, at the clinical stage of the disease, inflammation of the synovial membrane. The alterations in osteoarthritic cartilage are numerous and involve morphologic and metabolic changes in chondrocytes, as well as biochemical and structural alterations in the extracellular matrix macromolecules.

Biomarkers for diagnosing and monitoring autoimmune diseases

The goal of studies of autoimmune disease biomarkers is to identity markers that fluctuate with disease development and severity, but then normalize following successful therapy. The perfect marker could thus serve as a diagnostic tool, as well as a monitoring device for therapeutic drug efficacy. Current biomarker discovery efforts are focused on three groups of proteins reflective of the autoimmune disease process: (1) degradation products arising from destruction of affected tissues, (2) enzymes that play a role in tissue degradation and (3) cytokines and other proteins associated with immune activation. Potential biomarkers for two autoimmune diseases, rheumatoid arthritis and multiple sclerosis, have been described in recent publications. For rheumatoid arthritis, these markers (by group) include (1) aggrecan fragments, C-propeptide of type II collagen and cartilage oligomeric matrix protein, (2) matrix metalloprotease (MMP)-1, MMP-3 and MMP-1/inhibitor complexes and (3) thioredoxin, IL-16 and tumour necrosis factor (TNF)-alpha. For multiple sclerosis, they include (1) neurofilament light protein and glial fibrillary acidic protein, (2) MMP-2 and MMP-9 and (3) TNF-alpha and soluble vascular adhesion molecule-1. The utility of most of these markers is limited by their restriction to relatively inaccessible anatomic sites (synovial or cerebrospinal fluid). Thus, from a practical standpoint, the most useful autoimmune biomarkers will be those measurable in serum or plasma.