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- Title
Lubricin/Proteoglycan 4 Binding to CD44 Receptor: A Mechanism of the Suppression of Proinflammatory Cytokine-Induced Synoviocyte Proliferation by Lubricin.
- Authors
Al‐Sharif, Afnan; Jamal, Maha; Zhang, Ling X.; Larson, Katherine; Schmidt, Tannin A.; Jay, Gregory D.; Elsaid, Khaled A.
- Abstract
Objective To evaluate the binding of recombinant human proteoglycan 4 (rhPRG4) to CD44 receptor and its consequences on cytokine-induced synoviocyte proliferation. Methods The binding of rhPRG4 to CD44 and competition with high molecular weight (HMW) hyaluronic acid (HA) was evaluated using a direct enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance. Sialidase A and O-glycosidase digestion of rhPRG4 was performed, and CD44 binding was evaluated using ELISA. Rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) were stimulated with interleukin-1β (IL-1β) or tumor necrosis factor α (TNFα) for 48 hours in the presence or absence of rhPRG4 or HMW HA at 20, 40, and 80 μg/ml, and cell proliferation was measured. The contribution of CD44 was assessed by coincubation with a CD44 antibody (IM7). The antiproliferative effect of rhPRG4 was investigated following treatment of PRG4-/- mouse synoviocytes with IL-1β or TNFα in the presence or absence of IM7. Results Recombinant human PRG4 bound CD44 and interfered with the binding of HMW HA to CD44. Removal of sialic acid and O-glycosylations significantly increased CD44 binding by rhPRG4 ( P < 0.001). Both rhPRG4 and HMW HA at 40 and 80 μg/ml significantly suppressed IL-1β-induced proliferation of RA FLS ( P < 0.05). Recombinant human PRG4 at 20, 40, and 80 μg/ml significantly suppressed TNFα-induced RA FLS proliferation ( P < 0.05). CD44 neutralization reversed the effect of rhPRG4 on IL-1β- and TNFα-stimulated RA FLS and the effect of HMW HA on IL-1β-stimulated RA FLS. Recombinant human PRG4 inhibited cytokine-induced proliferation of PRG4-/- synoviocytes, which could be prevented by blocking CD44. Conclusion PRG4 (lubricin) is a novel putative ligand for CD44 and may control synoviocyte overgrowth in inflammatory arthropathies via a CD44-mediated mechanism.
- Subjects
MASSACHUSETTS; ACADEMIC medical centers; ANALYSIS of variance; ENZYME-linked immunosorbent assay; GLYCOPROTEINS; IMMUNOHISTOCHEMISTRY; LUBRICATION &; lubricants; RESEARCH funding; RHEUMATOID arthritis; STATISTICS; T-test (Statistics); DATA analysis
- Publication
Arthritis & Rheumatology, 2015, Vol 67, Issue 6, p1503
- ISSN
2326-5191
- Publication type
Article
- DOI
10.1002/art.39087