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Updated: May 19, 2026

A Friction Testing-Bioreactor Device for Study of Synovial Joint Biomechanics, Mechanobiology, and Physical Regulation
Published on: June 2, 2022
Human synovial lubricin expresses sialyl Lewis x determinant and has L-selectin ligand activity
Chunsheng Jin1, Anna-Karin Hultgård Ekwall, Johan Bylund
1Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, 405 30 Gothenburg, Sweden. chunsheng.jin@medkem.gu.se
Abstract:
Lubricin (or proteoglycan 4 (PRG4)) is an abundant mucin-like glycoprotein in synovial fluid (SF) and a major component responsible for joint lubrication. In this study, it was shown that O-linked core 2 oligosaccharides (Galβ1-3(GlcNAcβ1-6)GalNAcα1-Thr/Ser) on lubricin isolated from rheumatoid arthritis SF contained both sulfate and fucose residues, and SF lubricin was capable of binding to recombinant L-selectin in a glycosylation-dependent manner. Using resting human polymorphonuclear granulocytes (PMN) from peripheral blood, confocal microscopy showed that lubricin coated circulating PMN and that it partly co-localized with L-selectin expressed by these cells. In agreement with this, activation-induced shedding of L-selectin also mediated decreased lubricin binding to PMN. It was also found that PMN recruited to inflamed synovial area and fluid in rheumatoid arthritis patients kept a coat of lubricin. These observations suggest that lubricin is able to bind to PMN via an L-selectin-dependent and -independent manner and may play a role in PMN-mediated inflammation.
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