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Fibronectin mediates enhanced wear protection of lubricin during shear
journal contribution
posted on 2015-12-17, 09:34 authored by Roberto
C. Andresen Eguiluz, Sierra G. Cook, Cory N. Brown, Fei Wu, Noah J. Pacifici, Lawrence
J. Bonassar, Delphine GourdonFibronectin (FN) is a glycoprotein
found in the superficial zone
of cartilage; however, its role in the lubrication and the wear protection
of articular joints is unknown. In this work, we have investigated
the molecular interactions between FN and various components of the
synovial fluid such as lubricin (LUB), hyaluronan (HA), and serum
albumin (SA), which are all believed to contribute to joint lubrication.
Using a Surface Forces Apparatus, we have measured the normal (adhesion/repulsion)
and lateral (friction) forces across layers of individual synovial
fluid components physisorbed onto FN-coated mica substrates. Our chief
findings are (i) FN strongly tethers LUB and HA to mica, as indicated
by high and reversible long-range repulsive normal interactions between
surfaces, and (ii) FN and LUB synergistically enhance wear protection
of surfaces during shear, as suggested by the structural robustness
of FN+LUB layers under pressures up to about 4 MPa. These findings
provide new insights into the role of FN in the lubricating properties
of synovial fluid components sheared between ideal substrates and
represent a significant step forward in our understanding of cartilage
damage involved in diseases such as osteoarthritis.