Miwako Saito1, Yasuhiro Ota1, Hiroyuki Ohashi2, Yoshiaki Dei1, Kumiko Shimoyama1, Daisuke Suzuki1, Hideharu Hayashi1 and Noriyoshi Ogawa1
26 July 2006
23 October 2006
The purpose of this study is to clarify signal transduction of expression of the intercellular adhesion molecule-1 (ICAM-1) via CD40-CD40 ligand in salivary glands of patients with Sjögren's syndrome (SS). We used cultured salivary gland epithelial cells (SG cells) from 15SS patients and 8 controls obtained by labial minor salivary gland biopsy. First, ICAM-1 expression was determined with reverse transcriptase--polymerase chain reaction and flow cytometry in the presence or absence of soluble CD40L (sCD40L). Next, SG cells were transfected with plasmids of pGL1.3-Luc inserted with promoter region of ICAM-1, pGL1.3kB−-Luc mutated in nuclear factor kappa-B (NF-κB) binding site of pGL1.3-Luc and pNF-κB-Luc by lipofection method. Luciferase activity of the cells was measured in the presence or absence of sCD40L or sCD40L and an NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC). Finally NF-κB family proteins of cell nuclear extracts were determined. ICAM-1 expression was significantly enhanced with sCD40L at the mRNA and protein level. Activity of pNF-κB-Luc and pGL1.3-Luc was significantly elevated by stimulation with sCD40L and suppressed by PDTC. NF-κB p50 protein level was elevated by stimulation with sCD40L and suppressed by PDTC. Our results suggest that sCD40L enhances the ICAM-1 expression by activation of NF-κB p50 in the SS SG cells.
CD40 ligand - Intercellular adhesion molecule-1 - Nuclear factor-kappa B - Salivary gland epithelial cells - Sjögren's syndrome