Characterization of a bovine synovial fluid lubricating factor III. The interaction with hyaluronic acid

Abstract

Although hyaluronate is not a boundary lubricant in cartilaginous and latex:glass bearings, a distinct interaction with purified synovial lubricating factor (PSLF) was demonstrated by three means: 1) enhancement of lubricating ability in an artificial test system; 2) viscometry; 3) electron microscopy. The interaction was of a physical rather than a specific chemical type; it varied with the degree of purification of PSLF and of hyaluronate. The interaction accounts for retention of the relatively small PSLF molecule (approximately 280 kDa) with the synovial mucin on a 0.22 microns filter. The data provide evidence that hyaluronate and PSLF act synergistically in the boundary lubricating activity of animal joints.

Boundary lubrication of articular cartilage: Role of synovial fluid constituents

“…Similar SF constituents have been used in several previous studies examining their lubricating function (12,18,21,(23)(24)(25)(26), and future studies may examine the friction-lowering effects of other specific forms of SF constituents. Additional studies examining the structure-function relationship of SF constituents contributing to boundary lubrication, both alone and in combination, may provide the framework for the potential complete recapitulation of the boundary-lubricating ability of whole SF.…”

“…Jay et al (21) previously reported that HA and PRG4 acted synergistically, with HA enabling PRG4 to lubricate under higher contact pressures at a latex-glass interface under boundary-lubricating conditions. In that study, hydrophobic attraction of PRG4 molecules along the length of HA was suggested as a possible mechanism for this interaction, although PRG4 does contain other putative binding domains as well (25).…”

“…More than one specific molecule contributing to the boundary lubrication of articular cartilage is not particularly surprising given the variety of interactions that can occur between the many molecules present in SF and at the articular surface (for example, see refs. 5,21,54,55).…”

“…These results were consistent with findings of several previous studies and extended them using native cartilage surfaces in similar (8,9) and different (10,11) test configurations, as well as using nonbiologic surfaces (8,12,13). The lubricating ability of HA has been assessed at cartilage-cartilage (14)(15)(16)(17)(18), cartilage-steel (19), and cartilage-glass interfaces (18,20), as well as at a latex-glass interface under boundary lubrication conditions (12,21), with variable conclusions, possibly due to the different test surfaces and configurations and the various resulting operative modes of lubrication. Conversely, PRG4 proteins (22), which are synthesized and secreted by cells lining the synovial cavity (4,5), have consistently demonstrated boundary-lubricating ability at both cartilage-glass (23) and latex-glass interfaces (12,21,24,25).…”

“…The lubricating ability of HA has been assessed at cartilage-cartilage (14)(15)(16)(17)(18), cartilage-steel (19), and cartilage-glass interfaces (18,20), as well as at a latex-glass interface under boundary lubrication conditions (12,21), with variable conclusions, possibly due to the different test surfaces and configurations and the various resulting operative modes of lubrication. Conversely, PRG4 proteins (22), which are synthesized and secreted by cells lining the synovial cavity (4,5), have consistently demonstrated boundary-lubricating ability at both cartilage-glass (23) and latex-glass interfaces (12,21,24,25). Studies examining the lubricating ability of SAPL at a cartilage-cartilage interface (in combination with HA) (19) and at a cartilage-steel interface (19,26), as well as at a latex-glass interface under boundary lubrication conditions (13), suggest that SAPL may also possess boundary-lubricating ability.…”