Serum levels of hyaluronan, antigenic keratan sulfate, matrix metalloproteinase 3, and tissue inhibitor of metalloproteinases 1 change predictably in rheumatoid arthritis patients who have begun activity after a night of bed rest

Hyaluronan and Reactive Oxygen Species Signaling—Novel Cues from the Matrix?

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG) localized to the cell surface and the tissue extracellular matrix (ECM). It is composed of disaccharides containing glucuronic acid and N-acetylglucosamine, is synthesized by the HA synthase (HAS) enzymes and is degraded by hyaluronidase (HYAL) or reactive oxygen and nitrogen species (ROS/RNS) actions. HA is deposited as a high molecular weight (HMW) polymer and degraded to low molecular weight (LMW) fragments and oligosaccharides. HA affects biological functions by interacting with HA-binding proteins (hyaladherins). HMW HA is anti-inflammatory, immunosuppressive, and antiangiogenic, whereas LMW HA has pro-inflammatory, pro-angiogenetic, and oncogenic effects. ROS/RNS naturally degrade HMW HA, albeit at enhanced levels during tissue injury and inflammatory processes. Thus, the degradation of endothelial glycocalyx HA by increased ROS challenges vascular integrity and can initiate several disease progressions. Conversely, HA exerts a vital role in wound healing through ROS-mediated HA modifications, which affect the innate immune system. The normal turnover of HA protects against matrix rigidification. Insufficient turnover leads to increased tissue rigidity, leading to tissue dysfunction. Both endogenous and exogenous HMW HA have a scavenging capacity against ROS. The interactions of ROS/RNS with HA are more complex than presently perceived and present an important research topic.

Systemic Glycosaminoglycan Clearance by HARE/Stabilin-2 Activates Intracellular Signaling

Scavenger receptors perform essential functions, critical to maintaining mammalian physiologic homeostasis by continuously clearing vast numbers of biomolecules from blood, interstitial fluid and lymph. Stabilin-2 (Stab2) and the Hyaluronic Acid Receptor for Endocytosis (HARE), a proteolytic isoform of Stab2, are important scavenger receptors responsible for the specific binding and internalization (leading to degradation) of 22 discrete molecules, macromolecular complexes and cell types. One-third of these ligands are glycosaminoglycans (GAGs). Full-length Stab2, but not HARE, mediates efficient phagocytosis of apoptotic cells and bacteria via binding to target surface ligands. HARE, the C-terminal half of Stab2, mediates endocytosis of all the known soluble ligands. HA was the first ligand identified, in 1981, prior to receptor purification or cloning. Seven other GAG ligands were subsequently identified: heparin, dermatan sulfate, chondroitin and chondroitin sulfates A, C, D and E. Synthetic dextran sulfate is also a GAG mimic and ligand. HARE signaling during HA endocytosis was first discovered in 2008, and we now know that activation of HARE/Stab2 signaling is stimulated by receptor-mediated endocytosis or phagocytosis of many, but not all, of its ligands. This review focuses on the HARE-mediated GAG activation of intracellular signaling, particularly the Extracellular Signal-Regulated Kinase 1/2 pathway.

Protein kinase a mediated anti-inflammatory effects exerted by adenosine treatment in mouse chondrocytes stimulated with IL-1β

Hyaluronan (HA) fragments produced by degradation of native highly polymerized HA during inflammation may exacerbate proinflammatory responses in different pathologies. In contrast, the nucleoside adenosine (ADO) interacting with cell surface adenosine receptors A(2A) R, A(2B) R, A(1,) and A(3) , acts as endogenous modulator of the inflammation. The engagement of high-affinity A(2A) R by ADO activates a pathway leading to increased cAMP production. Elevated levels of cAMP associate with the activation of protein kinase A (PKA) able to inhibit NF-kB, hence exerting anti-inflammatory activity. In this study the effect of ADO treatment in normal murine chondrocytes stimulated with interleukin-1beta (IL-1beta) was investigated. mRNA and related protein levels were measured for enzymes, receptors and pro-inflammatory cytokines TNF-alpha, IL-6 and Il-18. IL-1beta stimulation significantly up-regulated HA levels, its fragmentation, cAMP, PKA, cytokine levels, and activated NF-kB. ADO treatment increased cAMP and PKA levels, while reduced NF-kB activation and cytokine levels. HA inhibition by specific synthetic HA blocking peptide (Pep-1) reduced IL-1beta action but not ADO activity. While A(2A) R inhibition by specific small interference RNA (siRNA) increased inflammation and decreased cAMP and PKA levels. This study suggests that HA is partially responsible for the up-regulation of proinflammatory cytokines in chondrocytes and that endogenous/exogenous ADO may reduce inflammation via PKA.

Changes in synovial fluid biochemical markers following arthroscopic surgery in patients with knee osteoarthritis

Although arthroscopic surgery (AS) for knee osteoarthritis has been widely employed, scientific evidence is lacking. The purpose of this study was to investigate temporal changes in synovial fluid levels of biochemical markers associated with cartilage metabolism following AS. Twenty-five knees of 24 patients with medial knee osteoarthritis (mean age 70.5 years) were included in this study. Synovial fluids were sampled immediately before surgery and 2, 4, 8, and 12 weeks after AS. Levels of the biochemical markers chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), and keratan sulfate (KS) were measured and correlations among the biochemical markers were analyzed before and after surgery. C6S, C4S, and total CS levels were the same before and after surgery; however, the KS level decreased significantly at 2 weeks after AS. A strong, positive correlation was detected between C6S and KS levels at 12 weeks, differing from the weaker correlation seen before surgery. Seven of the patients required total or unicompartmental knee arthroplasties in the 2 years following AS. In this study, the significant reduction in KS levels and the strong correlation between C6S and KS levels were shown, which indicates suppressed cartilage turnover after AS. Exploring predictive factors indicating favorable or unfavorable outcomes from AS will be important future studies.

Circadian pattern and the effect of standardized physical exercise on procollagen IIA N-peptide (PIIANP) in rheumatoid arthritis at different stages and in healthy individuals

BACKGROUND

Variant collagen IIA is re-expressed in diseased cartilage. Low procollagen IIA N-peptide (PIIANP) levels in serum have recently been reported in rheumatoid arthritis (RA). We investigated circadian rhythmicity and effect of physical activity on PIIANP in early and longstanding RA and in healthy subjects.

METHODS

Patients with early and longstanding RA and controls were included. Fasting and serial blood samples were collected during 24 h. PIIANP response to physical activity was studied before and serially after standardized exercise.

RESULTS AND CONCLUSION

In RA at different stages and healthy individuals, PIIANP exhibited no circadian rhythmicity, and PIIANP in serum was not influenced by physical activity.

Testing of the OMERACT 8 Draft Validation Criteria for a Soluble Biomarker Reflecting Structural Damage in Rheumatoid Arthritis: A Systematic Literature Search on 5 Candidate Biomarkers

Objective.

To test the OMERACT 8 draft validation criteria for soluble biomarkers by assessing the strength of literature evidence in support of 5 candidate biomarkers.

Methods.

A systematic literature search was conducted on the 5 soluble biomarkers RANKL, osteoprotegerin (OPG), matrix metalloprotease (MMP-3), urine C-telopeptide of types I and II collagen (U-CTX-I and U CTX-II), focusing on the 14 OMERACT 8 criteria. Two electronic voting exercises were conducted to address: (1) strength of evidence for each biomarker as reflecting structural damage according to each individual criterion and the importance of each individual criterion; (2) overall strength of evidence in support of each of the 5 candidate biomarkers as reflecting structural damage endpoints in rheumatoid arthritis (RA) and identification of omissions to the criteria set.

Results.

The search identified 111 articles. The strength of evidence in support of these biomarkers reflecting structural damage was low for all biomarkers and was rated highest for U-CTX-II [score of 6.5 (numerical rating scale 0–10)]. The lowest scores for retention of specific criteria in the draft set went to criteria that refer to the importance of animal studies, correlations with other biomarkers reflecting damage, and an understanding of the metabolism of the biomarker.

Conclusion.

Evidence in support of any of the 5 tested biomarkers (MMP-3, CTX-I, CTX-II, OPG, RANKL) was inadequate to allow their substitution for radiographic endpoints in RA. Three of the criteria in the draft criteria set might not be required, but few omissions were identified.

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.

PIIANP and HELIXII diurnal variation

OBJECTIVE

Serum levels of procollagen type IIA N-terminal propeptide (sPIIANP) and type-II collagen helical peptide (sHELIXII) biomarkers were evaluated for variation diurnally and with physical activity and food in participants with osteoarthritis (OA) of the knee.

METHODS

Forty participants with OA of at least one knee were admitted overnight to the General Clinical Research Center for serial serum sampling. Samples were obtained on the evening (6-8 pm) of Day 1 (T3, n=40); prior to rising (8 am) from bed (T0, n=40); 1 h after rising (9 am) without food consumption (T1a, n=20); 1-2 h after rising (9-10 am) with food consumption (T1, n=40); and additionally at noon, 4 h after rising (T2, n=20). sPIIANP and sHELIXII were measured by enzyme-linked immunosorbent assay. Results were analyzed using non-parametric Freidman's test with Dunn's post-hoc multiple comparison test.

RESULTS

Normalized mean concentrations for sPIIANP and sHELIXII increased significantly from T0 to T1 (P<0.05).

CONCLUSIONS

This is the first study to demonstrate diurnal variation of these collagen-II biomarkers in individuals with knee OA. These results suggest that serum sampling for these markers should be standardized for purposes of clinical trials.

The adenosine a2a receptor inhibits matrix-induced inflammation in a novel fashion

Endogenous mediators within the inflammatory milieu play a critical role in directing the scope, duration, and resolution of inflammation. High-molecular-weight extracellular matrix hyaluronan (HA) helps to maintain homeostasis. During inflammation, hyaluronan is broken down into fragments that induce chemokines and cytokines, thereby augmenting the inflammatory response. Tissue-derived adenosine, released during inflammation, inhibits inflammation via the anti-inflammatory A2 adenosine receptor (A2aR). We demonstrate that adenosine modulates HA-induced gene expression via the A2aR. A2aR stimulation inhibits HA fragment-induced pro-fibrotic genes TNF-alpha, keratinocyte chemoattractant (KC), macrophage inflammatory protein (MIP)-2, and MIP-1alpha while simultaneously synergizing with hyaluronan fragments to up-regulate the TH1 cytokine IL-12. Interestingly, A2aR stimulation mediates these affects via the novel cAMP-activated guanine nucleotide exchange factor EPAC. In addition, A2aR-null mice are more susceptible to bleomycin-induced lung injury, consistent with a role for endogenous adenosine in inhibiting the inflammation that may lead to fibrosis. Indeed, the bleomycin treated A2aR-null mice demonstrate increased lung inflammation, HA accumulation, and histologic damage. Overall, our data elucidate the opposing roles of tissue-derived HA fragments and adenosine in regulating noninfectious lung inflammation and support the pursuit of A2aR agonists as a means of pharmacologically inhibiting inflammation that may lead to fibrosis.

The need for prognosticators in rheumatoid arthritis. Biological and clinical markers: where are we now?

Rheumatoid arthritis is a heterogeneous disease with respect to clinical manifestations, serologic abnormalities, joint damage and functional impairment. Predicting outcome in a reliable way to allow for strategic therapeutic decision-making as well as for prediction of the response to the various therapeutic modalities available today, especially biological agents, would provide means for optimization of care. In the present article, the current information on biological and clinical markers related to disease activity and joint damage as well as for predictive purposes is reviewed. It will be shown that the relationship of many biomarkers with disease characteristics is confounded by factors unrelated to the disease, and that only few biomarkers exist with some predictive value. Moreover, clinical markers appear of equal value as biomarkers for this purpose, although they likewise have limited capacity in these regards. The analysis suggests the search for better markers to predict outcomes and therapeutic responsiveness in rheumatoid arthritis needs to be intensified.

Dermatan sulfate in the synovial fluid of patients with knee osteoarthritis

Biochemical factors play an important role in osteoarthritis (OA) pathogenesis. The purpose of this study is to clarify whether the dermatan sulfate (DS) levels in the synovial fluid of patients with knee OA are related to residual cartilage. Synovial fluid was obtained from 51 OA patients. Knee radiographs were evaluated with the Kellgren-Lawrence (K/L) grading scale. The levels of the following disaccharides were measured by high-performance liquid chromatography (HPLC): DS (DSDeltaDi4S), chondroitin 6-sulfate (CSDeltaDi6S), and chondroitin 4-sulfate (CSDeltaDi4S). The concentration of cartilage oligomeric matrix protein (COMP) was measured by a sandwich ELISA. The levels of DSDeltaDi4S in Grades 0 and I OA were significantly higher than levels in Grade II (P = 0.0458), Grade III (P < 0.0001) and Grade IV (P < 0.0001), and we found strong relationships between the levels of DSDeltaDi4S and those of CSDeltaDi6S (P < 0.0001, r = 0.705), CSDeltaDi4S (P < 0.0001, r = 0.750), and COMP (P < 0.0001, r = 0.699). We conclude that the presence of DSDeltaDi4S reflects proteoglycan metabolism in the residual articular cartilage of OA patients. This suggests that metabolism of the small leucine-rich repeat proteoglycans decorin and biglycan, which contain chains of DSDeltaDi4S, is similar to that of aggrecan.

Oral salmon calcitonin reduces Lequesne's algofunctional index scores and decreases urinary and serum levels of biomarkers of joint metabolism in knee osteoarthritis

OBJECTIVE

To evaluate the effects of oral salmon calcitonin (sCT) on Lequesne's algofunctional index scores and on biomarkers of joint metabolism in knee osteoarthritis.

METHODS

In this randomized, double-blind trial, patients received either placebo (n = 18), 0.5 mg of sCT (n = 17), or 1 mg of sCT (n = 18) daily for 84 days. Biomarkers included C-telopeptide of type II collagen (CTX-II), type II collagen neoepitope C2C, collagenases (matrix metalloproteinase 1 [MMP-1], MMP-8, and MMP-13), stromelysin (MMP-3), tissue inhibitors of metalloproteinases 1 and 2, and hyaluronan. Statistical analysis included nonparametric tests.

RESULTS

A total of 41 patients completed the study (13 in the group receiving 0.5 mg of sCT and 14 in each of the other 2 other groups). Although, on day 84, patients in both the placebo group and the group receiving 1 mg of sCT exhibited a similar significant decrease in pain scores, a significant reduction in the function score was observed only in the 2 sCT groups. On day 84, there was no significant decrease in biomarker levels in the placebo group, whereas significant reductions in the levels of both MMP-3 and hyaluronan were observed in the 2 sCT groups. The group of patients receiving 1 mg of sCT exhibited significant decreases in the levels of CTX-II, C2C, and MMP-13.

CONCLUSION

By improving functional disability and by reducing levels of biomarkers that are thought to be predictive of joint space narrowing (and thus cartilage loss), oral sCT at a dose of 1 mg might be a useful pharmacologic agent in human knee OA.

Effects of Moving Training on Histology and Biomarkers Levels of Articular Cartilage

OBJECTIVE

To study the adaptation process and extent of articular cartilage in the canine knee joint to different modes of movements and to investigate if levels of cartilage oligomeric matrix protein (COMP), matrix metalloproteinases-1 (MMP-1), matrix metalloproteinases-3 (MMP-3), and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in serum and synovial fluid can be used to predict effectively early sports injury and remolding degree of articular cartilage in the canine knee.

MATERIALS AND METHODS

Twenty adult dogs divided randomly into three groups (eight in the common training group, Training Group; eight in the intensified training group, Intensified Group; and four in the Control Group) were trained daily at different intensities. Magnetic resonance imaging (MRI) examinations were performed regularly (0, 2, 4, 6, 8, 10 weeks) to investigate changes of articular cartilage in the canine knee, while concentrations of COMP, MMP-1, MMP-3, and TIMP-1 in serum and synovial fluid were measured by ELISA assays. All of the dogs were euthanized after training for 10 weeks, and all of the knee joints were taken out to be examined histologically.

RESULTS

We could find imaging changes of early sport injury of articular cartilage in the Training Group and Intensified Group by MRI examination after 2 weeks of training; the damage images were most severe in 4-6 weeks, and then lightened gradually. We could not find the difference of cartilage injury and repair degree in MRI images between these two groups at different time points. Elevations of levels of COMP, MMP-1, MMP-3, TIMP-1, and MMP-3/TIMP-1 in serum and synovial fluid were seen during the training period, and their levels changed remarkably at different times. Levels of MMP-1, MMP-3, and MMP-3/TIMP-1 in the Intensified Group were lower than that in the Training Group in general, and levels of COMP were higher, which hinted that the injury trend of articular cartilage in the Intensified Group was lower than that in the Training group, and the repair trend was higher. Furthermore, there were statistically significant associations between biomarker levels in serum and in synovial fluid. Histological examinations in 10 weeks demonstrated that the signs of cartilage damage and repair in canine knee joint in the Training Group and the Intensified Group were obvious, and the Intensified Group could do better than the Training Group in promoting remodeling reconstruction of articular cartilage.

CONCLUSIONS

High-intensity and repetitive movement may easily induce sports injury, and it is followed with a repair process; intensified training can do better than common training in promoting remodeling reconstruction of articular cartilage. The sensitivity of these biomarkers reflecting articular cartilage pathological changes is better than MRI, and the associated application of several biomarkers to predict the extent of damage and repair, as well as changes of metabolism in articular cartilage, and to monitor change of disease course has very good value for clinical application.

Threat matrix: low-molecular-weight hyaluronan (HA) as a danger signal

Whether or not T cell receptor engagement leads to full activation or tolerance is determined by the context in which the antigen is encountered. Antigen presented by activated APCs in the presence of costimulation leads to full T cell activation, while antigen presented by resting APCs leads to tolerance. Pathogen-associated molecular patterns in the form of toll-like receptor ligands play a critical role in activating APCs and promoting T cell activation. In this review we hypothesize that low-molecular-weight species of the extracellular matrix polymer hyaluronan also performs this function by acting as an endogenous danger signal.

Diurnal variation of serum and urine biomarkers in patients with radiographic knee osteoarthritis

OBJECTIVE

To evaluate diurnal variation of biomarkers in subjects with osteoarthritis (OA) of the knee.

METHODS

Twenty subjects with radiographic knee OA were admitted to the General Clinical Research Center of Duke University for an overnight stay to undergo serial blood and urine sampling. Biomarkers measured included serum hyaluronan (HA), cartilage oligomeric matrix protein (COMP), keratan sulfate (KS-5D4), aggrecan neoepitope (CS846), high-sensitivity C-reactive protein (hsCRP), osteocalcin, transforming growth factor beta1 (TGFbeta1), and type II collagen (CII)-related epitopes (neoepitope from cleavage of CII [C2C], carboxy-terminus of three-quarter peptide from cleavage of CI and CII [C1,2C], and type II procollagen carboxy-propeptide [CPII] in serum, and C-terminal telopeptides of CII [CTX-II] and C2C in urine).

RESULTS

Levels of serum HA, COMP, KS-5D4, and TGFbeta1 increased significantly from T0 (before arising from bed) to T1 (1 hour after arising). More diurnal variation in HA was observed in patients with higher daily mean HA concentrations. CPII increased significantly from T0 to T2 (4 hours after arising). Urinary concentrations of CTX-II were also found to vary with morning activity, decreasing significantly from T0 to T2. Urinary C2C concentrations increased significantly from T0 until T3 (early evening). No diurnal variations in CS846, hsCRP, osteocalcin, serum C2C, or C1,2C were observed. Six biomarkers (serum C2C, C1,2C, COMP, KS-5D4, TGFbeta1, and urinary CTX-II) were associated with radiographic knee OA (expressed as the sum of Kellgren/Lawrence radiographic severity grades), with the strongest correlations observed with measurements obtained at later time points (either T2 or T3).

CONCLUSION

Our study results suggest that serum and urine sampling for HA, COMP, KS-5D4, TGFbeta1, CPII, urinary CTX-II, and urinary C2C should be standardized in future OA clinical trials. Serum and urine sampling at late midday time points may be the optimal approach for OA studies, although this result should be validated in a larger cohort.

Use of the plasma stromelysin (matrix metalloproteinase 3) concentration to predict joint space narrowing in knee osteoarthritis

OBJECTIVE

To determine whether baseline or serial plasma concentrations of stromelysin (matrix metalloproteinase 3 [MMP-3]) protein might distinguish subjects with progressive radiographic knee osteoarthritis (OA) from those with stable disease.

METHODS

Subjects were 120 women with unilateral knee OA who participated in a 30-month randomized, placebo-controlled trial of structure modification with doxycycline. Anteroposterior views of both knees in a semiflexed position were obtained at baseline, 16 months, and 30 months. Subjects were selected to obtain comparisons of plasma MMP-3 levels between 60 progressors (21 taking doxycycline, 39 taking placebo) and 60 nonprogressors (30 taking doxycycline, 30 taking placebo) with respect to medial joint space narrowing (JSN) in the index knee. Each group consisted of 30 subjects who exhibited significant increases in knee pain. Blood samples were obtained semiannually for MMP-3 assay.

RESULTS

Subjects in the placebo group whose MMP-3 concentration was in the upper tertile of the baseline distribution showed a 4-fold increase in the odds of progression of JSN as compared with the lower tertile (odds ratio 4.12, P = 0.037). Baseline MMP-3 levels were unrelated to knee pain. The within-subject mean of serial MMP-3 concentrations was associated with concurrent JSN in the placebo group over the 0-16-month interval (b = 0.18 mm/SD increase in the mean MMP-3, P < 0.01) and over the 16-30-month interval (b = 0.15, P < 0.05). Similar evidence of concurrent validity was found in the placebo group for the maximum of intercurrent MMP-3 values.

CONCLUSION

The baseline MMP-3 level was a significant predictor of JSN in this pilot study. Moreover, serial plasma MMP-3 levels reflected concurrent JSN in the placebo group over the 30-month period of observation.

Analysis of the disaccharides derived from hyaluronic acid and chondroitin sulfate by capillary electrophoresis with sample stacking

CE conditions for monitoring the unsaturated disaccharides of hyaluronic acid (di-HA) and chondroitin sulfate (di-CS) using an alkaline tetraborate buffer, electrokinetic sample injection, and UV absorption detection at 232 nm are reported. Separations were performed in an uncoated fused-silica capillary having reversed polarity and reversed electroosmosis generated with the addition of CTAB to the buffer. The influence of various separation parameters, including the concentration of CTAB, buffer pH, concentration of tetraborate, and applied voltage, on the resolution of the two disaccharides was investigated. Baseline separation was obtained with 25 mM tetraborate at pH 10.0 and having 0.05 mM CTAB. Chloride and phosphate in the sample are beneficial for the stacking of the disaccharides, with di-HA forming a much sharper peak than di-CS. Using samples prepared in 25 mM Tris-HCl (pH 7.5) and electrokinetic injection at the cathode at -10 kV for 40 s, linear relationships between the corrected peak area and the concentration of the disaccharides have been found in the ranges of 1.0-400.0 and 0.1-1.0 microg/mL (0.2-1.0 microg/mL for di-CS), with correlation coefficients being >0.9933 in all cases. The RSDs of detection times and corrected peak areas were between 1.13-1.24 and 1.57-2.13%, respectively. Applied to human serum samples that were prepared by ethanol precipitation and depolymerization of the two polysaccharides with chondroitinase ABC reveals comigration of endogenous compounds with di-HA and a sample-dependent detection time. The di-HA content in the serum sample can be estimated via subtraction of the blank peak that is obtained without enzymatic hydrolysis.

Oral salmon calcitonin induced suppression of urinary collagen type II degradation in postmenopausal women: a new potential treatment of osteoarthritis

OBJECTIVE

To assess the efficacy of 3 months of oral salmon calcitonin (sCT) on cartilage degradation as estimated by the changes in the urinary excretion of C-terminal telopeptide of collagen type II (CTX-II), and to investigate whether the response of oral sCT to urinary CTX-II depends on the baseline level of cartilage turnover.

METHODS

This was a randomized, double blind, placebo-controlled clinical setting including 152 Danish postmenopausal women aged 55-85. The subjects received treatment with the different doses of sCT (0.15, 0.4, 1.0, or 2.5 mg) combined with Eligen technology-based carrier molecule (200 mg), or placebo for 3 months. The efficacy parameter was the changes in the 24-h excretion of urinary CTX-I/II corrected for creatinine excretion at month 3.

RESULTS

sCT induced a significant dose-dependent decrease in 24-h urinary CTX-II excretion. Similar dose-dependent responses were found in 24-h urinary CTX-I. When stratifying the study population into tertiles of baseline urinary CTX-II, the present osteoarthritic symptoms and definite cases of osteoarthritis (OA) were significantly more frequent in women in the highest tertile of CTX-II (mean 391 +/- 18 ng/mmol). Women who received 1.0 mg of sCT and had the highest cartilage turnover presented the greatest decrease in urinary CTX-II after 3 months of treatment.

CONCLUSION

In addition to its pronounced effect on bone resorption, this novel oral sCT formulation may also reduce cartilage degradation and thereby provide therapeutic benefit in terms of chondroprotection. Women with high cartilage turnover are more likely to benefit from oral sCT treatment.

Variation of serum hyaluronan with activity in individuals with knee osteoarthritis

PURPOSE

Serum hyaluronan (HA) was evaluated for diurnal variation in participants with osteoarthritis (OA) of the knee.

METHODS

Twenty participants with radiographic OA of at least one knee were admitted overnight to the General Clinical Research Center for serial serum sampling. Serum was obtained between 6:00 p.m. and 8:00 p.m. on Day 1 (T3) after a day of normal activity. During the night of bed rest, participants remained supine for a minimum of 5 h between the hours of 3:00 a.m. and 8:00 a.m. Blood was drawn prior to arising from bed (T0), and 1h (T1) and 4 h (T2) after arising and performing usual morning activities, including eating breakfast. During the morning, participants were encouraged to remain physically active and were not permitted to sit for more than 30 min at a time. Serum HA was measured by enzyme-linked immunosorbent assay. Results were analyzed using non-parametric Freidman's test with Dunn's post-hoc Multiple Comparison test.

RESULTS

Serum levels of HA increased significantly from T0 to T1 (P < 0.01). There were no other significant changes in serum HA levels observed between any of the other time points.

CONCLUSIONS

Although a rise in serum HA with activity and eating has been demonstrated previously in individuals with rheumatoid arthritis, this is the first study to demonstrate a similar rise in individuals with OA. These results suggest that serum sampling for HA in OA clinical trials should be performed more than 1h after arising in the morning and at least 1h after breaking an overnight fast.

The potential value of blood biomarkers of intervertebral disk metabolism in the follow-up of patients with sciatica

STUDY DESIGN

This is a prospective study with a follow-up period of 4 years.

OBJECTIVES

The study aimed to evaluate the possible clinical utility of three biomarkers [i.e., keratan sulfate (KS), hyaluronan, and cartilage oligomeric matrix protein] measured in peripheral blood in severe acute sciatica at intake and follow-up.

SUMMARY OF BACKGROUND

Our previous study and others have pointed out the interest of different laboratory tests in the acute phase of sciatica. Several blood biomarkers have been reported useful in the long-term follow-up of patients with osteoarthritis. We have found no information about the potential interest of these tests in spinal disorders.

METHODS

Patients were admitted to the hospital for intensive conservative management of acute sciatica (n=82). A subgroup of patients (n=33) was selected based on the duration of symptoms at visit 1, and included those with the shortest (n=24) as well as those with the longest (n=9) duration of sciatica. Blood samples were drawn, centrifuged, and the plasma frozen. Antigenic KS, hyaluronan, and cartilage oligomeric matrix protein were measured by ELISA. Patients were re-evaluated at an average of 4.3 years (range: 2.1-6.8 years).

RESULTS

Thirty-three subjects with an average age of 49.2+/-10.2 years participated. At intake, levels of the three biomarkers evaluated were within the range of normal values. No significant differences were found between the results of patients with a short history of sciatica (< or =3 weeks) and those with a long duration of symptoms (>20 weeks). At follow-up, a significant increase (P<0.05) in all three biomarkers was found.

CONCLUSIONS

A single measurement of these three biomarker molecules does not seem to have any diagnostic or therapeutic relevance in patients with acute radicular compression. The significance of the increase in all three biomarkers after a mean follow-up of 4.3 years is unclear; it might reflect metabolic processes involved in degenerative spinal disorders. Even though we found no correlation with clinical outcome, we believe that more research is needed.

Comparative Effect of Nimesulide and??Ibuprofen on the Urinary Levels of??Collagen Type II C-Telopeptide Degradation Products and on the Serum Levels of Hyaluronan and Matrix Metalloproteinases-3 and -13 in??Patients with Flare-Up of Osteoarthritis

BACKGROUND AND AIM

Because in vitro studies have shown that nimesulide not only preferentially inhibits COX-2 but also reduces the action/release of pro-inflammatory cytokines, down-regulates the synthesis and/or activity of collagenase(s), and releases reactive oxygen species and other toxic substances from neutrophils, this study investigated whether nimesulide and ibuprofen could affect levels of biochemical markers of joint inflammation and collagen catabolism in patients with flare-up of knee or hip osteoarthritis.

METHODS

Ninety patients were included in this randomised, prospective, single- blind study. They received either nimesulide (n = 45) or ibuprofen (n = 45) for a 4-week treatment period. The following parameters were analysed by ELISA: urinary levels of C-terminal cross-linking telopeptide of type II collagen (CTX-II), a marker of type II collagen breakdown; serum levels of hyaluronan (HA), a marker of synovial inflammation and hyperplasia; and circulating levels of stromelysin-1 (matrix metalloproteinase-3 [MMP-3]), collagenase-1 (MMP-1) and collagenase-3 (MMP-13). Statistical analysis used was ANOVA.

RESULTS

At the end of the treatment period, nimesulide but not ibuprofen markedly reduced the urinary levels of CTX-II (p < 0.001) and the serum levels of HA (p < 0.05), two markers known to prognosticate poor outcome of the osteoarthritis disease process. Nimesulide also reduced the serum levels of both MMP-3 (p < 0.05) and MMP-13 (p < 0.001). Furthermore, in the nimesulide group, the decrease in levels of CTX-II correlated significantly with the decrease in levels of HA and MMP-13.

CONCLUSION

Although nonsteroidal anti-inflammatory drugs are effective in improving pain and disability in OA patients, to date it has been unclear to what extent these drugs could affect joint metabolism and hence joint structure. Patients with flare-up of their osteoarthritis disease process exhibit enhanced levels of markers of joint inflammation and cartilage collagen breakdown, which were markedly decreased by nimesulide but not by ibuprofen.

Endocytic function, glycosaminoglycan specificity, and antibody sensitivity of the recombinant human 190-kDa hyaluronan receptor for endocytosis (HARE)

The human hyaluronan receptor for endocytosis (hHARE) mediates the endocytic clearance of hyaluronan (HA) and chondroitin sulfate from lymph fluid and blood. Two hHARE isoforms (190 and 315 kDa) are present in sinusoidal endothelial cells of liver, spleen, and lymph nodes (Zhou, B., McGary, C. T., Weigel, J. A., Saxena, A., and Weigel, P. H. (2003) Glycobiology 13, 339-349). Here we report the specificity and function of the 190-kDa HARE, expressed without the larger isoform, in Flp-In 293 cell lines (190hHARE cells). Like the native protein, recombinant hHARE contains approximately 25 kDa of N-linked oligosaccharides, binds HA in a ligand blot assay, cross-reacts with three anti-rat HARE monoclonal antibodies, and is inactivated by reduction. The 190hHARE cell lines mediated rapid, continuous (125)I-HA endocytosis and degradation for >1 day. About 30-50% of the total cellular receptors were on the cell surface, and their recycling time for reutilization was approximately 8.5 min. The average K(d) for the binding of HA to the 190-kDa hHARE at 4 degrees C was 7 nm with 118,000 total HA binding sites per cell. Competition studies at 37 degrees C indicated that the 190-kDa hHARE binds HA and chondroitin better than dermatan sulfate and chondroitin sulfates A, C, D, and E, but it does not bind to heparin, heparan sulfate, or keratan sulfate. Although competition was observed at 37 degrees C, none of the glycosaminoglycans tested, except HA, competed for (125)I-HA binding by 190hHARE cells at 4 degrees C. Anti-HARE monoclonal antibodies #30 and #154, which do not inhibit (125)I-HA uptake mediated by the 175-kDa rat HARE, partially blocked HA endocytosis by the 190-kDa hHARE. We conclude that the 190-kDa hHARE can function independently of other hHARE isoforms to mediate the endocytosis of multiple glycosaminoglycans. Furthermore, the rat and human small HARE isoforms have different glycosaminoglycan specificities and sensitivities to inhibition by cross-reacting antibodies.

Characterization of the recombinant rat 175-kDa hyaluronan receptor for endocytosis (HARE)

Hyaluronan (HA) and chondroitin sulfate (CS) clearance from lymph and blood in mammals is mediated by the HA receptor for endocytosis (HARE), which is present as two isoforms in rat and human (175/300 kDa and 190/315 kDa, respectively) in the sinusoidal endothelial cells of liver, spleen, and lymph nodes (Zhou, B., McGary, C. T., Weigel, J. A., Saxena, A., and Weigel, P. H. (2003) Glycobiology 13, 339-349). The small rat and human HARE proteins are not encoded directly by mRNA but are derived from larger precursors. Here we characterize the specificity and function of the 175-kDa HARE, expressed in the absence of the 300-kDa species, in stably transfected SK-Hep-1 cells. The HARE cDNA was fused with a leader sequence to allow correct orientation of the membrane protein. The recombinant rHARE contained approximately 25 kDa of N-linked oligosaccharides and, like the native protein, was able to bind HA in a ligand blot assay, even after de-N-glycosylation. SK-HARE cell lines demonstrated specific 125I-HA endocytosis, receptor recycling, and delivery of HA to lysosomes for degradation. The Kd for the binding of HA (number-average molecular mass approximately 133 kDa) to the 175-kDa HARE at 4 degrees C was 4.1 nm with 160,000 to 220,000 HA-binding sites per cell. The 175-kDa rHARE binds HA, dermatan sulfate, and chondroitin sulfates A, C, D, and E, but not chondroitin, heparin, heparan sulfate, or keratan sulfate. Surprisingly, recognition of glycosaminoglycans (GAGs) other than HA by native or recombinant HARE was temperature-dependent. Although competition was observed at 37 degrees C, none of the other GAGs competed for 125I-HA binding to SK-HARE cells at 4 degrees C. Anti-HARE monoclonal antibody-174 showed a similar temperature-dependence in its ability to block HA endocytosis. These data suggest that temperature-induced conformational changes may alter the GAG specificity of HARE. The results confirm that the 175-kDa rHARE does not require the larger HARE isoform to mediate endocytosis of multiple GAGs.

A blocking antibody to the hyaluronan receptor for endocytosis (HARE) inhibits hyaluronan clearance by perfused liver

Hyaluronan (HA) and chondroitin sulfate clearance from lymph and blood is mediated by the hyaluronan receptor for endocytosis (HARE). The purification and molecular cloning (Zhou, B., Weigel, J. A., Saxena, A., and Weigel, P. H. (2002) Mol. Biol. Cell 13, 2853-2868) of this cell surface receptor were finally achieved after we developed monoclonal antibodies (mAbs) against HARE. There are actually two independent isoreceptors for HA, which in rat are designated the 175-kDa HARE and 300-kDa HARE. Only one mAb (number 174) effectively and completely blocked the specific uptake of 125I-HA at 37 degrees C by rat liver sinusoidal endothelial cells. 125I-HA binding to both the 175-kDa and 300-kDa HARE proteins in a ligand blot assay was almost completely inhibited by <1 microg/ml mAb-174, whereas mouse IgG had little or no effect. MAb-174 also performed very well in Western analysis, indirect fluorescence microscopy, and a variety of immuno-procedures. Immunohistochemistry using mAb-174 localized HARE to the sinusoidal cells of rat liver, spleen, and lymph node. Western analysis using mAb-174 revealed that the sizes of both HARE glycoproteins were the same in these three tissues. 125I-HA was taken up and degraded by excised rat livers that were continuously perfused ex vivo with a recirculating medium. This HA clearance and metabolism by liver, which is a physiological function of HARE, was very effectively blocked by mAb-174 but not by mouse IgG. The results indicate that mAb-174 will be a useful tool to study the functions of HARE and the physiological significance of HA clearance.

Age-related differences in the accumulation and size of hyaluronan in alginate culture

The alginate bead culture system has unique properties that make it possible to study the accumulation and turnover of macromolecules in two distinct matrix compartments of the cartilage matrix: the cell-associated matrix (CM) and the further removed matrix (FRM). Taking advantage of this culture system, the purpose of this study was to examine age-related changes in the metabolism of hyaluronan (HA) in these two compartments. Bovine chondrocytes, isolated from fetal, young adult, and old adult articular cartilage, were cultured in alginate beads. On Days 7 and 14 of culture, the alginate gel was solubilized, the CM and FRM were separated and macromolecules in both compartments were analyzed. When compared to the cells from fetal and old adult animals, the young adult cells proliferated at the fastest rate. Fetal cells produced a more abundant CM that was richer in proteoglycans (PGs) than the CM of young or old adult cells. With increasing age, there was an increased tendency for PG, collagen, and HA to escape incorporation into the CM and to become immobilized in the FRM. Very striking changes also were observed in the ratio of HA to PG, which increased markedly with age, and in the size of the HA molecules, which decreased markedly with age. The results suggest that the metabolism of HA in cartilage undergoes pronounced age-related changes, some of which are retained during culture in alginate gel. The findings also suggest that the previously documented age-related decrease in the size of HA in native bovine cartilage reflects, at least in part, a biochemical process occurring at the time or at least soon after the glycosaminoglycan chain is synthesized. It does not appear to simply be the result of age-related changes occurring slowly with time after synthesis, as was previously suggested to be the case for human articular cartilage.

Serum levels of cartilage oligomeric matrix protein (COMP) correlate with radiographic progression of knee osteoarthritis

OBJECTIVE

To evaluate the prognostic utility of serum COMP level measured with a new sandwich ELISA, by correlating COMP level with outcome measures of osteoarthritis (OA) progression.

DESIGN

Patients (N=48) had symptomatic primary knee OA of Kellgren-Lawrence (K-L) grade I-III and met ACR criteria. These patients were evaluated prospectively as part of a double-blind drug trial of 3 years' duration and represented the placebo arm of the study. Serum COMP levels were measured by sandwich ELISA with monoclonal antibodies 16-F12 and 17-C10 at baseline and at study end and levels were correlated with changes in (1) joint space width (JSW), (2) K-L grade, (3) Lequesne, and (4) WOMAC indices, over 3 years.

RESULTS

The change in JSW over 3 years, summed for both knees, correlated positively with serum COMP level at baseline as well as at study end. Patients were sorted by level of progression based upon a change in K-L grade summed for both knees over 3 years; patients who progressed by two K-L grades were shown to have had significantly higher COMP levels at baseline as well as at study end. Baseline and study end COMP levels did not correlate with the change of Lequesne or WOMAC indices. Baseline COMP levels correlated strongly with end serum COMP levels.

CONCLUSION

Serum COMP has the potential to be a prognostic marker of disease progression. High COMP levels, persisting over the 3-year study period in the patients with radiographic progression, indicated differences in disease activity detectable throughout the entire follow-up interval.

Molecular cloning and functional expression of the rat 175-kDa hyaluronan receptor for endocytosis

We recently purified the rat liver hyaluronan receptor for endocytosis (HARE) and found abundant expression of 175- and approximately 300-kDa HARE species in sinusoidal endothelial cells of the liver, spleen, and lymph nodes. We report herein the first cloning and functional expression of the rat 175-kDa HARE. Peptide sequences were obtained from the purified 175-kDa HARE, and degenerate oligonucleotide primers were designed for reverse transcription-polymerase chain reaction and cDNA cloning. Results of 5'-rapid amplification of cDNA ends, Northern analysis, N-terminal sequence, and antibody reactivity analyses indicated the absence of mRNA directly encoding the 175-kDa HARE. This protein is most likely derived from a larger precursor. Accordingly, we constructed an artificial 4.7-kb cDNA encoding the 1431 amino acid 175-kDa HARE. The predicted type I membrane protein has a mass of 156,393 Da and a pI of 7.86. The 175-kDa HARE cDNA, fused to the N-terminal leader sequence of the Ig kappa-chain, was transfected transiently into COS-7 cells and stably into SK-Hep-1 cells, respectively, to assess hyaluronan or hyaluronic acid (HA)-binding activity and endocytosis. In both cases, HARE expression and HA-binding activity were detected. Furthermore, stable SK-175HARE cells demonstrated specific endocytosis of (125)I-HA and receptor recycling. Fluorescence-activated cell sorting analysis confirmed that recombinant HARE was expressed on the cell surface and that fluorescent HA uptake was inhibited by a specific blocking monoclonal antibody against HARE. Additionally, HARE was substantially colocalized with clathrin, but not with internalized HA that was delivered to lysosomes. The results confirm that recombinant 175-kDa HARE is an authentic endocytic receptor for HA and that this receptor can function independently of the approximately 300-kDa HARE. HARE is the first functionally identified member of a protein family that shares a similar organization of Fasciclin, epidermal growth factor-like, Xlink, and transmembrane domains.

Sleep and pain

Noxious stimuli and painful disorders interfere with sleep, but disturbances in sleep also contribute to the experience of pain.Chronic paroxysmal hemicrania and possibly cluster headaches are related to REM sleep. Whereas headache is associated with snoring and sleep apnea, morning headaches are not specific for any primary sleep disorder. Nevertheless, the management of the sleep disorder ameliorates both morning headache and migraine.Noxious stimuli administered into muscles during slow-wave sleep (SWS) result in decreases in delta and sigma but an increase in alpha and beta EEG frequencies during sleep. Noise stimuli that disrupt SWS result in unrefreshing sleep, diffuse musculoskeletal pain, tenderness, and fatigue in normal healthy subjects. Such symptoms accompany alpha EEG sleep patterns that often occur in patients with fibromyalgia. The alpha EEG patterns include phasic and tonic alpha EEG sleep as well as periodic K alpha EEG sleep or frequent periodic cyclical alternating pattern. Moreover, alpha EEG sleep, as well as sleep-related breathing disorder and periodic limb movement disorder, occur in some patients with fibromyalgia, rheumatoid arthritis and osteoarthritis. Depression and not alpha EEG sleep are features of somatoform pain disorder. Disturbances in sleep, pain behaviour and psychological distress influence return to work in workers who have suffered a soft tissue injury, e.g. low back pain. Patients with irritable bowel disorder have disturbed sleep and have increased REM sleep. In conclusion, there is a reciprocal relationship between sleep quality and pain. The recognition of disturbed or unrefreshing sleep influences the management of painful medical disorders.

Paradoxical effects of tissue inhibitor of metalloproteinases 1 gene transfer in collagen-induced arthritis

OBJECTIVE

The imbalance between matrix metalloproteinases (MMPs) 1, 3, and 9 and their specific inhibitor, tissue inhibitor of metalloproteinases 1 (TIMP-1), is a critical step in cartilage injury and angiogenesis in arthritis. To explore the therapeutic potential of TIMP-1 gene transfer in erosive arthritis, the effects of an adenoviral vector (Ad-TIMP-1) were assessed in DBA/1 mice with collagen-induced arthritis (CIA).

METHODS

DBA/1 mice with CIA received an intravenous injection of replication-deficient adenovirus containing the human TIMP-1 gene or a control LacZ gene on day 28 postimmunization. The efficiency of gene transfer was determined by serum TIMP-1 detection, measurements of paw swelling, as well as radiologic and histologic examination of the paws.

RESULTS

A single administration of Ad-TIMP-1 resulted in detectable serum levels of the exogenous protein for at least 13 days. The incidence and onset of arthritis were not statistically modified after human TIMP-1 gene transfer in DBA/1 mice compared with control mice. However, the severity of inflammation was statistically significantly increased in Ad-TIMP-1-treated mice and a similar trend was observed in the histologic and radiologic scores. With regard to the mechanisms of the worsened effect in the Ad-TIMP-1-treated mice, we observed 1) higher serum levels of anti-type II collagen IgG2a, 2) a significant increase in endogenous soluble tumor necrosis factor receptor I (TNFRI) in sera, and 3) increased labeling of mouse tumor necrosis factor alpha and TNFRI within arthritic joints.

CONCLUSION

These findings show that overexpression of TIMP-1 does not prevent osteochondral injury in a mouse model of arthritis. Since MMPs have overlapping properties in terms of their roles in extracellular matrix degradation, angiogenesis, and shedding of cell surface adhesion molecules, cytokines, and cytokine receptors, the paradoxical results obtained suggest that TIMP-1 is probably not the main inhibitor to target.

Markers of disease in rheumatoid arthritis

Substantial progress can be noted in the efforts to demonstrate the usefulness of tissue-related markers of disease in rheumatoid arthritis and other joint diseases. The most informative studies use longitudinal analyses of well-characterized patient groups. Emphasis should be on searching for markers which can be of prognostic significance. New markers need to be assessed in relation to existing ones, such as C-polysaccharide reacting protein and erythrocyte sedimentation rate, which, although not specific, are hard to beat as measures of inflammation. A newly identified matrix component, cartilage intermediate layer protein, has features which make it attractive as a potential cartilage specific marker. Many markers may not in the end prove clinically useful. They will, however, give important insight into pathogenic processes, and may help in evaluating new therapy. Finally, markers originally identified in humans have now proven their value in experimental arthritis.