Anti-inflammatory effects of lutein in retinal ischemic/ hypoxic injury: In vivo and in vitro studies

Abstract

PURPOSE: Lutein protects retinal neurons by its anti-oxidative and anti-apoptotic properties in ischemia/reperfusion (I/R) injury while its anti-inflammatory effects remain unknown. As Müller cells play a critical role in retinal inflammation, the effect of lutein on Müller cells was investigated in a murine model of I/R injury and a culture model of hypoxic damage. METHODS: Unilateral retinal I/R was induced by a blockade of internal carotid artery using the intraluminal method in mice. Ischemia was maintained for 2 hours followed by 22 hours of reperfusion, during which either lutein (0.2 mg/kg) or vehicle was administered. Flash electroretinogram (flash ERG) and glial fibrillary acidic protein (GFAP) activation were assessed. Lutein's effect on Müller cells was further evaluated in immortalized rat Müller cells (rMC-1) challenged with cobalt chloride-induced hypoxia. Levels of IL-1β, cyclooxygenase-2 (Cox-2), TNFoα and nuclear factor-NF-kappa-B (NF-κB) were examined by Western blot analysis. RESULTS: Lutein treatment minimized deterioration of b-wave/a-wave ratio and oscillatory potentials as well as inhibited upregulation of GFAP in retinal I/R injury. In cultured Müller cells, lutein treatment increased cell viability and reduced level of nuclear NF-κB, IL-1β, and Cox-2, but not TNFα after hypoxic injury. CONCLUSIONS: Reduced gliosis in I/R retina was observed with lutein treatment, which may contribute to preserved retinal function. Less production of pro-inflammatory factors from Müller cells suggested an anti-inflammatory role of lutein in retinal ischemic/hypoxic injury. Together with our previous studies, our results suggest that lutein protected the retina from ischemic/hypoxic damage by its anti-oxidative, antiapoptotic, and anti-inflammatory properties.