CD40 ligand induces expression of vascular cell adhesion molecule 1 and E-selectin in orbital fibroblasts from patients with Graves' orbitopathy.

PURPOSE: The aim of this study was to detect the effect of the CD40 ligand (CD40L) on the expression of vascular cell adhesion molecule 1 (VCAM-1) and E-Selectin in orbital fibroblasts (OFs) from patients with Graves' orbitopathy (GO), as well as the signaling pathways involved in this effect.
METHODS: OFs were isolated from orbital tissues obtained from patients with severe GO who were undergoing orbital decompression surgery. VCAM-1 and E-selectin RNA and protein expression levels were quantified in OFs stimulated with soluble CD40L (sCD40L). RNA and protein quantification was performed with real-time polymerase chain reaction (PCR) and western blot analysis. Cytoplasmic and nuclear fractions were isolated in order to detect the nuclear translocation of nuclear factor-κB (NF-κB). Signaling pathway inhibitors were applied to determine the pathways involved.
RESULTS: Compared to unstimulated OFs, the mRNA and protein levels of VCAM-1 and E-selectin in OFs incubated with sCD40L were significantly increased. This was observed in dose- and time-course experiments, and the inductive effects of sCD40L were much weaker in OFs from healthy donors. At the same time, we observed that CD40L induced nuclear translocation of NF-κB, also in a dose- and time-dependent manner. The up-regulation of VCAM-1 and E-selectin, as well as the NF-κB nuclear translocation induced by CD40L, was significantly attenuated by inhibitors targeting mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinase (PI3K), and NF-κB.
CONCLUSIONS: CD40L demonstrated the ability to up-regulate the expression of VCAM-1 and E-selectin at the pre-translational level in OFs from patients with GO. The MAPK and PI3K pathways and NF-κB may play important roles in CD40L-induced VCAM-1 and E-selectin expression.