Lutein and Eicosapentaenoic Acid Interact to Modify iNOS mRNA Levels through the PPARγ/RXR Pathway in Chickens and HD11 Cell Lines

Abstract

Two experiments were conducted to investigate the effect of lutein and fat or eicosapentaenoic acid (EPA) interaction on inducible nitric oxide synthase (iNOS), PPARs alpha, beta, and gamma, and retinoic acid X receptor (RXR) alpha and gamma mRNA levels. In Expt. 1, macrophages were collected from broiler chicks fed 3 or 6% dietary fat (g/100 g) with 0, 25, and 50 mg lutein/kg feed for 23 d. In Expt. 2, using a 3 x 3 factorial, eicosapentaenoic acid (EPA) at 0, 15 and 50 micromol/L and lutein at 0, 10 and 100 micromol/L were applied to HD11 cell culture for 24 h. In both experiments, cells were stimulated with lipopolysaccharide before RNA isolation. Lutein interacted with fat in Expt. 1 and with EPA in Expt. 2 to affect mRNA levels of iNOS, PPARgamma, and RXRalpha in chicken macrophages and HD11 cells, respectively (P < 0.05). At 3% dietary fat or up to 15 micromol/L EPA in the medium, increasing lutein increased the iNOS mRNA. However, at 6% dietary fat or 50 micromol/L EPA, lutein did not cause a rise in iNOS mRNA. Increasing lutein in the medium from 0 to 100 micromol/L decreased iNOS mRNA. Increasing lutein with high fat (6%) or EPA (15 micromol/L EPA) increased PPARgamma and RXRalpha mRNA levels. Lutein increased PPARalpha mRNA levels in both macrophages (P < 0.01) and HD11 (P = 0.01) cells and RXRgamma (P < 0.01) mRNA levels in macrophages. GW9662, a PPARgamma antagonist, prevented (P < 0.01) the lutein-induced iNOS mRNA downregulation in HD11 cells. LG101208, a RXR antagonist, prevented (P < 0.01) iNOS upregulation induced by 10 micromol/L lutein and iNOS mRNA downregulation induced by 100 micromol/L lutein. We conclude that lutein and EPA interact through the PPARgamma and RXR pathways to modulate iNOS mRNA.