OBJECTIVE To demonstrate the expression of laminins (Lns) and their integrin (Int) receptors in different synovial samples and synovial membrane-like interface tissues from well fixed and aseptically loosened total hip replacement (THR), and the potential role of Ln-Int interaction in the production of collagenases and cytokines.

RESULTS General Ln immunoreactivity was detected in all specimens. Ln α5, β1 and β2, but not α2 and α3 chains were seen in the synovial lining and the basement membrane of blood vessels with the intensity/extent of labelling in the following rank order: rheumatoid arthritis (RA) loosened prostheses, osteoarthritis, well fixed prostheses, traumatic knees. Among Int subunits, staining for β1 was usually the strongest, followed by staining for Int α6, α1, α3, and α2 subunits, with the same rank order for overall expression of Lns. Int β4 subunit was not detectable in most of the specimens. Double labelling focused on Int α6 subunit disclosed its frequent colocalisation with collagenases 1 and 3 and with tumour necrosis factor α and interleukin 6 in synovial lining.

CONCLUSION Synovial lining contains Ln-10, Ln-11, and Int α6β1 and α1β1 receptors. In aseptic loosening of THR, interface tissue has a similar Ln subtype and Int receptor composition as RA synovium, which confirms its “lining-like” phenotype. Synovial lining does not contain Ln-5 (α3β3γ2) or Int α6β4, which are components of epithelial hemidesmosomes. The expression of Lns and their Int receptors is upregulated in inflammation. The close spatial relation between Ln and its Int receptors in synovial lining cells containing proteinases and cytokines suggests a potential role in joint destruction and prosthetic loosening.