Abstract
The current limitations in evaluating synovial fluid (SF) components in health and disease and between species are due in part to the lack of data on normal SF, because of low availability of SF from healthy articular joints. Our study aimed to quantify species-dependent differences in phospholipid (PL) profiles of normal knee SF obtained from equine and human donors. Knee SF was obtained during autopsy by arthrocentesis from 15 and 13 joint-healthy human and equine donors, respectively. PL species extracted from SF were quantitated by mass spectrometry whereas ELISA determined apolipoprotein (Apo) B-100. Wilcoxon’s rank sum test with adjustment of scores for tied values was applied followed by Holm´s method to account for multiple testing. Six lipid classes with 89 PL species were quantified, namely phosphatidylcholine, lysophosphatidylcholine, sphingomyelin, phosphatidylethanolamine, plasmalogen, and ceramide. Importantly, equine SF contains about half of the PL content determined in human SF with some characteristic changes in PL composition. Nutritional habits, decreased apolipoprotein levels and altered enzymatic activities may have caused the observed different PL profiles. Our study provides comprehensive quantitative data on PL species levels in normal human and equine knee SF so that research in joint diseases and articular lubrication can be facilitated.
Highlights
The motion of joints requires the lubrication of articulating surfaces with synovial fluid (SF) that acts as the lubricant occupying the joint cavity and limiting adhesion formation [1, 2]
In total 89 individual lipid species were detected in SF, and 83 different lipid species belonging to six lipid classes were quantified in both normal equine and human SF
We found that the levels of total lipid species in equine SF [116.1 (86.3–141.8) nmol/ml] were approximately half (0.44-fold, P
Summary
The motion of joints requires the lubrication of articulating surfaces with synovial fluid (SF) that acts as the lubricant occupying the joint cavity and limiting adhesion formation [1, 2]. SF supplies the avascular cartilage with nutrients and oxygen, provides a medium for waste transport, and mediates cell-cell communication through cytokines and growth factors [3]. The measurement of SF in healthy human knee joints is problematic, only being found in small quantities of approx. 2.5 ml from which about 0.5 ml can be aspirated. The SF is spread over the internal joint surfaces to produce a film with varying.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
