Author(s): FuruzawaCarballeda, PM MacipRodrguez, AR Cabral
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Pannus in osteoarthritis (OA) has only recently been characterized. Little is known, however, regarding the behavior
of OA pannus in vitro compared to rheumatoid arthritis (RA) pannus. The purpose of our study was to compare OA with
RA pannus.Pannus and synovial tissue co-cultures from 5 patients with OA and 5 patients with RA obtained during arthroplasty were
studied. Pannus was defi ned as the microscopic invasive granulation tissue covering the articular surface. Tissues were
cultured for 7 days and stained with Alcian Blue technique. Interleukin-1β (IL-1β), IL-8, IL-10, IL-12, tumor necrosis
factor-α (TNF-α), and interferon gamma (IFN-γ) were also determined in supernatants by ELISA. Cartilage oligomeric
matrix protein (COMP), type II collagen, TNF-α, IL-10 and Ki-67 expression were also detected by immunohistochemistry.
All patients had vascular or fi brous pannus. Synovial proliferation, infl ammatory infi ltrates and a decrease of extracellular
matrix proteins were observed in all tissue samples. Chondrocyte proliferation was lower in OA than RA cartilage. OA
synovial tissue expressed lower levels of proteoglycans than RA synoyium. Type II collagen levels were lower in OA than
in RA cartilage. Signifi cantly higher levels of IL-1β were found in the supernatants of RA pannus compared to OA pannus
(p<0.05). High but similar levels of TNF-α, IL-8 and TIMP-1 were detected in OA and RA pannus supernatants.
IL-10, IL-12 and IFN-γ were undetectable.
RA and OA pannus had similar pro-infl ammatory and anti-infl ammatory cytokine profi le expression. OA cartilage, synovial
tissue and pannus had lower production of proteoglycans, type II collagen and IL-1β. It remains to be elucidated why OA
pannus invades the cartilage surface but does not cause the marginal erosions typically seen in RA.
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This article was published in ClinExpRheumatol
and referenced in Immunotherapy: Open Access