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· DOS Abstracts
Collagen type IV-induced changes in expression of
stress-related proteins in normal and osteoarthritic
chondrocytes are mediated by integrins -
α
2
β
1 and
ανβ
3
Casper Bindzus Foldager, Martin Lind, Wei Seong Toh, Helle Lysdahl
Orthopaedic Research Laboratory, Aarhus University Hospital; Sports Trauma
Clinic, Aarhus University Hospital; Faculty of Dentistry, National University of
Singapore; Orthopaedic Research Laboratory, Aarhus University Hospital
Background:
Chondrocytes in healthy cartilage express collagen type IV
(COL4) in the pericellular matrix (PCM) and the expression is decreased around
osteoarthritic (OA) chondrocytes.
Purpose / Aim of Study:
The aim was to investigate the role of COL4 in the
expression of stress-related proteins in healthy and OA chondrocytes and to
determine the role of COL4-binding integrins (
α
1
β
1,
α
2
β
1, and
α
νβ
3).
Materials and Methods:
Chondrocytes isolated from three healthy patients
undergoing anterior cruciate ligament reconstruction and OA chondrocytes
were isolated from three patients undergoing knee replacement surgery. Cells
in passage one were seeded at 10,000 cells/cm2 in COL4-coated wells or
non-coated control wells and cultured for 1, 5, and 14 days. Integrin profiles
of
α
1
β
1,
α
2
β
1, and
α
νβ
3 were performed using flow cytometry. Evaluation
of stress-related proteins was performed on day 5, with and without five-
hour prior integrin blocking by antibodies, using Proteome Profiler™ Human
Cell Stress Array. Data was analyzed using Kruskal-Wallis and Wilcoxon-Mann-
Whitney tests.
Findings / Results:
Both cell types expressed the evaluated integrins. On days
5 and 14, OA chondrocytes had higher
α
1
β
1 expression than normal chon-
drocytes. COL4 decreased the expression of
α
2
β
1 on both cell types on day
5. The expression of stress-related proteins was increased by COL4 in normal
chondrocytes, while it was decreased in OA chondrocytes. Integrin blocking with
neutralizing antibodies indicated that
α
2
β
1, and
α
νβ
3 were comparatively
more involved than
α
1
β
1 in mediating the stress-response induced by COL4.
Conclusions:
Integrin blocking revealed
α
2
β
1, and
α
νβ
3 as primary media-
tors of changes in the expression of stress-related proteins induced by the PCM
molecule COL4.
No conflicts of interest reported
9.