Distribution of fibronectins and their integrin receptors in interface tissue from aseptic loosening of hip prostheses

T. F. Li1², J.W. Xu³, S. Santavirta¹, L. Nordsletten⁴, O. Michelsson², M. Takagi⁵, I. Virtanen², Y.T. Konttinen^2,6,7

¹Department of Orthopaedics and Traumatology, Helsinki University Central Hospital; ²Department of Anatomy, Institute of Biomedicine, University of Helsinki; ³Department of Rheumatology, Long Island Jewish Medical Center, New York, USA; ⁴Ullevål Hospital, Oslo, Norway; ⁵Department of Orthopaedics, Yamagata University, Yamagata, Japan; ⁶Department of Medicine, Helsinki University Central Hospital; ⁷Dept. of Oral Medicine, Helsinki University Central Hospital, Helsinki, Finland.

ABSTRACT
Objectives
To assess the distribution of fibronectins (FNs) and their integrin (Int) receptors in synovial membrane-like interface tissue (SMLIT) from aseptic loosening of total hip replacement (THR), and potential role of FN-Int interaction in the loosening process.

Methods
The alkaline phosphatase anti-alkaline phosphatase (APAAP) method was used to detect the distribution of FNs and their Int receptors in SMLIT and control samples. Double immunofluorescence labeling was used to reveal the different co-localizations.

Results
Intensive FN staining appeared in the lining layers, sublining area, and vascular endothelium, while immuno-reactivities for Int a4, a5, b1 subunits were detected in the lining and endothelial cells of SMLIT. Immunofluorescence labeling revealed Int a5 and collagenase-1/collagenase-3 double positive cells in lining layers and sublining area of SMLIT.

Conclusion
Increased expression of FNs, Int a4b1 and a5b1 appeared in SMLIT compared with that in OA synovial membrane. FN-Int interactions may play a role in local collagenase production.

Key words
Total hip replacement, aseptic loosening, interface tissue, fibronectin, integrin, collagenase.

This study was supported by the Sigrid Juselius Foundation, the Finnish Academy, and the Helsinki University Central Hospital (Evo Grant), Finland.

Please address correspondences and reprint requests to: Professor Yrjö Konttinen, Department of Anatomy, Institute of Biomedicine, P.O. Box 9 (Siltavuorenpenger 20 A), FIN-00014 University of Helsinki, Finland.
E-mail: yrjo.konttinen@helsinki.fi

Clin Exp Rheumatol 2000; 18: 221-225.
© Copyright Clinical and Experimental Rheumatology 2000.