TGF-beta(1) down-regulates inflammatory cytokine-induced VCAM-1 expressionin cultured human glomerular endothelial cells

Background. Endothelial cells are active participants in the processes cont rolling coagulation, inflammation and the immune response. Variations are r ecognized between endothelia isolated from different vascular beds as well as from different species. Though transforming growth factor-beta(1) (TGF-b eta(1)) has been known to have an anti-inflammatory action, little is known about its effect on expression of cellular adhesion molecules during the i nflammatory process in human glomerular endothelial cells. The aim of this study was to determine the effect of TGF-beta(1) on the inflammatory cytoki ne-induced expression of vascular cell adhesion molecule-1 (VCAM-1) in cult ured human glomerular endothelial cells. Methods. The culture of human glomerular endothelial cells was established using the normal portion of nephrectomized renal tissues and identified by factor VIII staining and cellular uptake of fluorescent-labelled acetylated low-density lipoprotein (LDL). The endothelial cells were stimulated by in terleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) with or without TGF-beta(1). Cellular expressi on of VCAM-1 was measured by enzyme-linked immunosorbent assay (ELISA) and flow cytometry, and VCAM-1 mRNA was measured by Northern blot analysis. Results. TGF-beta(1) (1, 10 and 25 ng/ml) blunted IL-1 beta-(5 ng/ml) induc ed VCAM-1 expression significantly (OD = 1.08 +/- 0.14, 1.10 +/- 1.16 and 1 .05 +/- 0.14 vs IL-1 beta = 1.97 +/- 0.29, n = 6, P < 0.05) in ELISA. The a ddition of TGF-beta 1 (1, 10 and 25 ng/ml) also suppressed TNF-alpha- (10 n g/ml) induced VCAM-1 expression (OD = 1.14 +/- 0.15, 1.17 +/- 0.17 and 1.18 +/- 0.16 vs TNF-alpha = 1.96 +/- 0.26, n = 6, P < 0.05). The same results were obtained by flow cytometry. TGF-beta(1) (10 ng/ml) inhibited both IL-1 beta- (5 ng/ml) and TNF-alpha-(10 ng/ml) induced expression of VCAM-1 (MFI : IL-1 beta = 90.8 +/- 17.6, IL-1 beta + TGF-beta(1) = 37.8 +/- 14.9, TNF-a lpha = 113.6 +/- 12.4, TNF-alpha + TGF-beta(1) = 64.3 +/- 13.8, mean +/- SD , n = 3, P < 0.05). By Northern blot analysis, TGF-beta(1) (10 ng/ml) signi ficantly suppressed the stimulatory effect of IL-1 beta and TNF-alpha. Conclusions. These results show that TGF-beta(1) down-regulates the inflamm atory cytokine-induced expression of VCAM-1 in human glomerular endothelial cells, which could be a novel mechanism for the anti-inflammatory action o f TGF-beta(1) during the inflammatory processes in human glomerular disease s.