Sensitivity of serum concentration of cartilage biomarkers to 21‐days of bed rest

Abstract

The objective of the study was to test the hypothesis that serum levels of cartilage oligomeric 2 matrix protein (COMP) would decrease and serum levels of tumor-necrosis factor alpha 3 (TNF-α) and selected matrix metalloproteinases (MMPs) would increase in response to bed 4 rest (BR) and that these changes are unaffected by the intake of potassium bicarbonate or 5 whey protein. Seven and 9 healthy male subjects participated in two 21-day 6° head down tilt 6 crossover BR-studies with nutrition interventions. Serum samples were taken before, during, 7and after BR and biomarker concentrations were measured using commercial enzyme-linked 8 immunosorbent assays. MMP-3 during BR was significantly lower than at baseline (reduction 9 greater 20%; P<0.001). MMP-3 increased significantly from 14 to 21 days of BR (+7%; 10 P=0.049). COMP during BR was significantly lower than at baseline (reduction greater 20%; 11 P<0.001). MMP-3 and COMP returned to baseline within one day after BR. MMP-9 on day 3 12 of BR was significantly lower than at baseline (-31%; P<0.033) and on days 3, 5 and 14 of 13

The influence of a sustained 10‐day hypoxic bed rest on cartilage biomarkers and subchondral bone in females: The FemHab study

“…While biomarkers of cartilage react quickly, actual articular cartilage changes are slower and currently not the primary focus of space life sciences research. To our knowledge, there is limited evidence regarding the effect of bed rest on cartilage (Liphardt et al, , ). Liphardt et al () measured serum levels of COMP on days 14 and 21 of bed rest and noted that COMP decreased by 16% after 24h of bed rest and a further 5% by day 14 of bed rest, with no further change by Day 21.…”

“…However, preclinical detection of cartilage and subchondral bone turnover is possible with magnetic resonance (MR) and computer tomography (CT) imaging and/or by analyses of serum and urine biomarkers (Lotz et al, ; Roemer & Guermazi, ). Potential biomarkers of cartilage may indicate changes in cartilage metabolism within days of unloading (Liphardt et al, ) and earlier than with imaging techniques. Additionally, the same is apparent for bone whereby markers of bone resorption may indicate significant changes within days of inactivity (Rittweger et al, ).…”

“…Furthermore, it is well established that muscular atrophy and osteopenia have been identified as predominant musculoskeletal complications of human space habitation (Berg, Eiken, Miklavcic, & Mekjavic, ). In contrast, evidence demonstrating the responses of cartilage and subchondral bone under bed rest conditions is lacking (Liphardt et al, , ).…”

The LunHab project: Muscle and bone alterations in male participants following a 10 day lunar habitat simulation

“…ambulation (Fitzgerald, Endicott, Hansen, & Janowitz, 2019;Hoemann, Lafantaisie-Favreau, Lascau-Coman, Chen, & Guzman-Morales, 2012). There is evidence that cartilage and markers of cartilage degradation are detectable within 7 days of space flight and 24 h of bed rest (Liphardt et al, 2018;Niehoff et al, 2016). The early detection of changes in cartilage might provide a better understanding of the relationship between the mechanical stimulus in the lower limb musculoskeletal functional unit.…”

“…not possible. There is evidence that cartilage and markers of cartilage degradation are detectable within 7 days of space flight and 24 h of bed rest(Liphardt et al, 2018;Niehoff et al, 2016). The individual participants in the study of Caillot-Augusseau et al (2000) exhibited either no change in CTX or an increase.…”