Expression of the mucosal lymphocyte integrin alpha E beta 7 and its ligand E-cadherin in the synovium of patients with rheumatoid arthritis.
The synovial expression of the mucosal lymphocyte integrin alpha E beta 7 and its ligand E-cadherin was analysed in order to study the relationship between T lymphocytes of the gastrointestinal tract and the synovium in patients with rheumatoid arthritis (RA). Immunohistochemical evaluation of synovium revealed that the alpha E beta 7-expression was detectable in 16 of the 38 samples examined. A concomitant examination on circulating lymphocytes by flow cytometry showed that alpha E beta 7-expressing lymphocytes occur less frequently in peripheral blood (PB). In vitro culture of lymphocytes increased the alpha E beta 7-expression on synovial lymphocytes six-fold, whereas PB lymphocytes expressed a two-fold increase. The addition of PHA to the culture medium did not dramatically increase the alpha E beta 7-expression on synovial lymphocytes, in contrast to PB lymphocytes where a 24-fold increase was detected. The addition of TGF-beta 1 to the culture of PB lymphocytes increased the alpha E beta 7-expression three-fold. E-cadherin expression was found in all synovial tissues analysed by immunohistochemistry. These results demonstrate that synovial T lymphocytes have the capacity to express the 'mucosal-type' integrin alpha E beta 7, possibly due to high levels of intra-articular TGF-beta 1. This expression might be of physiological importance since E-cadherin, the ligand for alpha E beta 7, is richly expressed by synoviocytes. In addition, the results indicate that a high in vivo expression of alpha E beta 7 is suppressed in the synovial tissue by a hitherto unknown mechanism.
Trollmo
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C
Department of Clinical Immunology, University of Göteborg, Sweden.
Nilsson
I M
IM
Sollerman
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C
Tarkowski
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A
D000328:Adult; D001171:Arthritis, Juvenile / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D015820:Cadherins / Q000096:biosynthesis*; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D016023:Integrins / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008024:Ligands; D008297:Male; D008875:Middle Aged; D013583:Synovial Membrane / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D015820:Cadherins; D016023:Integrins; D008024:Ligands; D016212:Transforming Growth Factor beta; C070709:integrin alphaEbeta7