Articular Joint Lubricants during Osteoarthritis and Rheumatoid Arthritis Display Altered Levels and Molecular Species

PLoS One. 2015 May 1;10(5):e0125192. doi: 10.1371/journal.pone.0125192. eCollection 2015.


Background: Hyaluronic acid (HA), lubricin, and phospholipid species (PLs) contribute independently or together to the boundary lubrication of articular joints that is provided by synovial fluid (SF). Our study is the first reporting quantitative data about the molecular weight (MW) forms of HA, lubricin, and PLs in SF from cohorts of healthy donors, patients with early (eOA)- or late (lOA)-stage osteoarthritis (OA), and patients with active rheumatoid arthritis (RA).

Methods: We used human SF from unaffected controls, eOA, lOA, and RA. HA and lubricin levels were measured by enzyme-linked immunosorbent assay. PLs was quantified by electrospray ionization tandem mass spectrometry. Fatty acids (FAs) were analyzed by gas chromatography, coupled with mass spectrometry. The MW distribution of HA was determined by agarose gel electrophoresis.

Results: Compared with control SF, the concentrations of HA and lubricin were lower in OA and RA SF, whereas those of PLs were higher in OA and RA SF. Moreover, the MW distribution of HA shifted toward the lower ranges in OA and RA SF. We noted distinct alterations between cohorts in the relative distribution of PLs and the degree of FA saturation and chain lengths of FAs.

Conclusions: The levels, composition, and MW distribution of all currently known lubricants in SF--HA, lubricin, PLs--vary with joint disease and stage of OA. Our study is the first delivering a comprehensive view about all joint lubricants during health and widespread joint diseases. Thus, we provide the framework to develop new optimal compounded lubricants to reduce joint destruction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Arthritis, Rheumatoid / metabolism*
  • Demography
  • Female
  • Glycoproteins / metabolism*
  • Humans
  • Hyaluronic Acid / metabolism*
  • Knee Joint / pathology*
  • Lubricants / metabolism*
  • Male
  • Middle Aged
  • Molecular Weight
  • Osteoarthritis / metabolism*
  • Phospholipids / metabolism*
  • Synovial Fluid / chemistry
  • Young Adult


  • Glycoproteins
  • Lubricants
  • Phospholipids
  • lubricin
  • Hyaluronic Acid

Grants and funding

Supported in part by a grant of the DRB foundation, the Natural Sciences and Engineering Research Council of Canada, and Alberta Innovates Health Solutions, and by the “LipidomicNet” project, funded within the Seventh Framework Programme of the European Union (Grant agreement number 202272). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.