Effect of oat and barley β-glucans on inhibition of cytokine-induced adhesion molecule expression in human aortic endothelial cells: Molecular structure-function relations

Endothelial cell adhesion molecules have been recognized as an early step in inflammation and atherogenesis. The inhibition of TNF-α-induced expression of vascular cell adhesion molecule (VCAM-1) and intracellular cell adhesion molecule (ICAM-1) in human aortic endothelial cells (HAEC), following pretreatment with mixed-linkage (1 → 3), (1 → 4)-β-d-glucans (β-glucans) isolated from oat and barley, and the possible molecular structure-function relations, have been explored. The apparent molecular weight (Mw) of β-glucans varied in the ranges of 0.71-2.42 × 105 (barley) and 0.36-2.55 × 105 (oat); a higher ratio of 3-O-β-cellobiosyl-d-glucose to 3-O-β-cellotriosyl-d-glucose oligomers in the polymeric chains was also found for barley β-glucans. Analysis of variance showed that polysaccharide concentration, Mw and fine structure of β-glucans affected the VCAM-1 expression (P < 0.05); the reduction of VCAM-1 expression in stimulated HAEC was also dose-dependent (concentration range of 3.75-200 μg/ml β-glucans) and significant at polysaccharide levels > 6.25 μg/ml (P < 0.05). The inhibition of VCAM-1 expression was greater for barley β-glucans compared to oat, displaying a maximum anti-inflammatory activity at Mw ∼1.40 × 105. Instead, the expression of ICAM-1 was suppressed (P < 0.05) only at high polysaccharide concentrations (>100 μg/ml), with maximum activity at Mw ∼2.50 × 105. Structural differences between the oat and barley β-glucans did to seem to influence the ICAM-1 expression.