Pirfenidone induces intercellular adhesion molecule-1 (ICAM-1) down-regulation on cultured human synovial fibroblasts

Abstract

Pirfenidone has been shown to modify some cytokine regulatory actions and inhibit fibroblast biochemical reactions resulting in inhibition of proliferation and collagen matrix synthesis by fibroblast. We have investigated the effect of pirfenidone on the expression of cell adhesion molecules. The synovial fibroblasts were treated with IL-1alpha in the presence or absence of pirfenidone (range 0-1000 microM), and assayed for the expression of adhesion molecules such as ICAM-1 and endothelial-leucocyte adhesion molecule-1 (E-selectin) by cell ELISA. Pirfenidone significantly down-regulated the expression of ICAM-1 on cultured synovial fibroblasts in a dose-dependent manner. In contrast, expression of E-selectin was not affected. Furthermore, we examined whether pirfenidone affects the cellular binding between cultured lymphocytes and IL-1alpha-stimulated synovial fibroblasts by in vitro binding assay and found their mutual binding was significantly suppressed in a dose-dependent manner by pirfenidone. It is speculated that down-regulation of ICAM-1 might be one of the novel mechanisms of action of pirfenidone. These data indicate a novel mechanism of action for pirfenidone to reduce the activation of synovial fibroblasts.

Fig. 1

(a) A dose-dependent increase in ICAM-1 expression induced by IL-1α. Fibroblasts were cultured with various concentrations of IL-1α for 24 h, and ICAM-1 expression was assayed by cell ELISA. (b) A dose-dependent increase in E-selectin expression induced by IL-1α. Fibroblasts were cultured with various concentrations of IL-1α for 4 h, and E-selectin expression was assayed by cell ELISA. The experiment is representative of three separate experiments.

Fig. 2

(a) Inhibition of ICAM-1 expression by pirfenidone. Various concentrations of pirfenidone were added to the fibroblast culture system together with IL-1α (10 pg/ml) for 24 h. ICAM-1 expression was measured by cell ELISA. Significant suppression of ICAM-1 expression was observed: *P < 0.001. (b) Inhibition of E-selectin expression by pirfenidone. Various concentrations of pirfenidone were added to the fibroblast culture system together with IL-1α (100 pg/ml) for 4 h and tested for their ability to alter E-selection expression in the system. The experiment is representative of three separate experiments.

Fig. 3

Inhibition of cellular binding between Molt 4 cells and IL-1α-stimulated fibroblasts with pirfenidone. Various concentrations of pirfenidone were added to the fibroblast culture system together with IL-1α (10 pg/ml) for 24 h. The binding between Molt 4 and IL-1α-stimulated fibroblasts was measured by the cell binding assay described in Materials and Methods. Significant inhibition was observed: *P < 0.001. The experiment is representative of three separate experiments.