Synoviocyte stimulation by the LFA-1-intercellular adhesion molecule-2-Ezrin-Akt pathway in rheumatoid arthritis

Karnail Singh, Inés Colmegna, Xiaowen He, Cornelia M. Weyand, Jörg J. Goronzy

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


In rheumatoid arthritis (RA), the synovium is infiltrated by mononuclear cells that influence the proliferation and activation of fibroblast-like synoviocytes (FLS) through soluble mediators as well as cell-to-cell contact. To identify receptor-ligand pairs involved in this cross-talk, we cocultured T cells with FLS lines isolated from synovial tissues from RA patients. Coculture with T cells induced phosphorylation of Akt (Ser473) and its downstream mediators, GSK-3α/GSK-β, FoxO1/3a, and mouse double minute-2, and enhanced FLS proliferation. T cell-mediated phospho-Akt up-regulation was unique for FLS as no such effect was observed upon interaction of T cells with dendritic cells and B cells. Akt activation was induced by all functional T cell subsets independent of MHC/Ag recognition and was also found with other leukocyte populations, suggesting the involvement of a common leukocyte cell surface molecule. Akt phosphorylation, enhanced in vitro FLS proliferation, and enhanced FLS IL-6 production was inhibited by blocking Abs to CD11a and ICAM-2 whereas Abs to ICAM-1 had a lesser effect. Selective involvement of the LFA-1-ICAM-2 pathway was confirmed by the finding of increased ezrin phosphorylation at Tyr353 that is known to be downstream of ICAM-2 and supports cell survival through Akt activation. CD28- T cells, which are overrepresented in RA patients, have high CD11a cell surface expression and induce Akt phosphorylation in FLS more potently than their CD28+ counterparts. These findings identify ICAM-2 as a potential therapeutic target to inhibit FLS activation in RA, allowing for a more selective intervention than broad LFA-1 inhibition.

Original languageEnglish (US)
Pages (from-to)1971-1978
Number of pages8
JournalJournal of Immunology
Issue number3
StatePublished - Feb 1 2008

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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