Lutein and eicosapentaenoic acid interact to modify iNOS mRNA levels through the PPARγ/RXR pathway in chickens and HD11 cell lines

Two experiments were conducted to investigate the effect of lutein and fat or eicosapentaenoic acid (EPA) interaction on inducible nitric oxide synthase (NOS), 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 mu mol/L and lutein at 0, 10 and 100 mu mol/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 NOS, PPAR gamma, and RXR alpha in chicken macrophages and HD11 cells, respectively (P < 0.05). At 3% dietary fat or up to 15 mu mol/L EPA in the medium, increasing lutein increased the NOS mRNA. However, at 6% dietary fat or 50 mu mol/L EPA, lutein did not cause a rise in NOS mRNA. Increasing lutein in the medium from 0 to 100 mu mol/L decreased NOS mRNA. Increasing lutein with high fat (6%) or EPA (15 mu mol/L EPA) increased PPAR gamma and RXRa mRNA levels. Lutein increased PPAR alpha mRNA levels in both macrophages (P < 0.01) and HD11 (P = 0.01) cells and RXR gamma (P < 0.01) mRNA levels in macrophages. GW9662, a PPAR gamma antagonist, prevented (P < 0.01) the lutein-induced NOS mRNA downregulation in HD11 cells. LG101208, a RXR antagonist, prevented (P < 0.01) iNOS upregulation induced by 10 mu mol/L lutein and iNOS mRNA downregulation induced by 100 mu mol/L lutein. We conclude that lutein and EPA interact through the PPAR gamma and RXR pathways to modulate NOS mRNA.