Effect of beta-Sitosterol in pro-inflammatory gene expression in bronchial epithelial cells

Previously, we reported that beta-sitosterol (bss), extracted from N.arvensis seeds, was able to inhibit the expression of the pro-inflammatory chemokine IL-8 in IB3-1 CF bronchial cells exposed to the P.aeruginosa laboratory strain PAO1. Chemically, bss is a steroid-like and modern in vitro and clinical studies have shown that plants containing such steroids are anti-inflammatory agents. In the present study bss was tested in the human CF airway epithelial cell line CuFi-1 exposed to PAO1 for 4 h. CuFi-1 when seeded on semipermeable filters and grown at the air-liquid interface, are capable of forming polarized differentiated epithelia that exhibits transepithelial resistance and maintains the ion channel physiology expected of the genotype delta F508/delta F508. CuFi-1 cells were pre-treated for 20 h with 100 nM of bss. Total RNA was extracted and a TaqMan Low Density Array was performed by which 92 target genes, that are crucial in the first line of response against pathogens and critical in chronic inflammatory diseases of the airways, were quantified. Among the PAO-1 induced genes, bss showed an anti-inflammatory acitivity inhibiting the overexpression of IL-8, GRO-alpha and GRO-beta genes. No changes in cell proliferation have been observed at bss high concentration (150 ). To exclude that the inhibition of the P.aeruginosa-dependent induction of the three genes was due to an indirect anti-bacterial effect on P.aeruginosa, we performed an anti-bacterial array following the procedure for the Minimum Inhibitory Concentration. In this paper, we have explored the anti-inflammatory effect of bss in a model of CF cell lines finding that bss is able to inhibit selectively the expression of the pro-inflammatory chemokines IL-8, GRO-alpha and GRO-beta. Recent mounting evidence to suggest that bss acts as anti-inflammatory molecules warrants further mechanistic studies to determine the full extent of its action.