Experimental-analytical approach to assessing mechanosensitive cartilage blood marker kinetics in healthy adults: dose-response relationship and interrelationship of nine candidate markers

Abstract

Purpose: To determine the suitability of selected blood biomarkers of articular cartilage as mechanosensitive markers and to investigate the dose-response relationship between ambulatory load magnitude and marker kinetics in response to load. Methods: Serum samples were collected from 24 healthy volunteers before and at three time points after a 30-minute walking stress test performed on three test days. In each experimental session, one of three ambulatory loads was applied: 100% body weight (BW); 80%BW; 120%BW. Serum concentrations of COMP, MMP-3, MMP-9, ADAMTS-4, PRG-4, CPII, C2C and IL-6 were assessed using commercial enzyme-linked immunosorbent assays. A two-stage analytical approach was used to determine the suitability of a biomarker by testing the response to the stress test (criterion I) and the dose-response relationship between ambulatory load magnitude and biomarker kinetics (criterion II). Results. COMP, MMP-3 and IL-6 at all three time points after, MMP-9 at 30 and 60 minutes after, and ADAMTS-4 and CPII at immediately after the stress test showed an average response to load or an inter-individual variation in response to load of up to 25% of pre-test levels. The relation to load magnitude on average or an inter-individual variation in this relationship was up to 8% from load level to load level. There was a positive correlation for the slopes of the change-load relationship between COMP and MMP-3, and a negative correlation for the slopes between COMP, MMP-3 and IL-6 with MMP-9, and COMP with IL6. Conclusions: COMP, MMP-3, IL-6, MMP-9, and ADAMTS-4 warrant further investigation in the context of articular cartilage mechanosensitivity and its role in joint degeneration and OA. While COMP seems to be able to reflect a rapid response, MMP-3 seems to reflect a slightly longer lasting, but probably also more distinct response. MMP-3 showed also the strongest association with the magnitude of load.

Dose-response relationship of in vivo ambulatory load and mechanosensitive cartilage biomarkers—The role of age, tissue health and inflammation: A study protocol

“…In each of the stress tests, either one of the three loading conditions 80%BW, 100%BW or 120%BW will be applied [32][33][34]. The reduced load condition will be achieved via an unloading system comprising a steel frame and a pneumatic pulley system connected to an unloading harness (h/p/cosmos airwalk1, h/p/cosmos sports & medical GmbH, Nussdorf-Traunstein, Germany).…”

“…Sample size calculation. To judge the adequacy of the intended samples sizes, we performed simulation studies using the estimated population means, the estimated populations standard deviations [33,34] and the estimated residual variance as true parameter values and assuming a correlation of 0.8 between intercept and slope. We then varied the population standard deviation of the slope by factors of 2 and 3 because in this study we expect a substantially larger population variation due to wider age range and including both ACL injured and healthy participants.…”

“…In a recent study, participants with knee OA had higher sMMP-3 levels than controls [66], and among participants with knee OA those with progression of cartilage injury in the medial knee compartment had higher levels of sMMP-3 [82]. In healthy participants sMMP-3 levels decreased during immobilization [74], were temporarily increased after walking and this load-induced increase was dependent on ambulatory load magnitude [34].…”

“…Candidates for mechanosensitive blood markers of articular cartilage include cytokines, enzymes involved in ECM metabolism, non-collagenous proteins and products of collagen synthesis or degradation [29][30][31]. In a pilot study, we established an experimental framework to modulate ambulatory load [32] and showed that the increase in concentration of serum cartilage oligomeric matrix protein (sCOMP) [33] and serum matrix metalloproteinase (sMMP)-3 [34] depend on the magnitude of the applied load. Further, serum interleukin (sIL)-6 increased after the walking stress independent of the ambulatory load magnitude [34].…”

“…In a pilot study, we established an experimental framework to modulate ambulatory load [32] and showed that the increase in concentration of serum cartilage oligomeric matrix protein (sCOMP) [33] and serum matrix metalloproteinase (sMMP)-3 [34] depend on the magnitude of the applied load. Further, serum interleukin (sIL)-6 increased after the walking stress independent of the ambulatory load magnitude [34].…”