Antioxidant properties of lutein contribute to the protection against lipopolysaccharide-induced uveitis in mice

Abstract

Background: Lutein is an important eye-protective nutrient. This study investigates the protective effects and mechanisms of lutein on lipopolysaccharides (LPS)-induced uveitis in mice.

Methods: Lutein, suspended in drinking water at a final concentration of 12.5 and 25 mg/mL, was administered to mice at 0.1 mL/10 g body weight for five consecutive days. Control and model group received drinking water only. Uveitis was induced by injecting LPS (100 mg per mouse) into the footpad in the model and lutein groups on day 5 after the last drug administration. Eyes of the mice were collected 24 hours after the LPS injection for the detection of indicators using commercial kits and reverse transcription-polymerase chain reaction.

Results: LPS-induced uveitis was confirmed by significant pathological damage and increased the nitric oxide level in eye tissue of BALB/C mice 24 hours after the footpad injection. The elevated nitric oxide level was significantly reduced by oral administration of lutein (125 and 500 mg/kg/d for five days) before LPS injection. Moreover, lutein decreased the malondialdehyde content, increased the oxygen radical absorbance capacity level, glutathione, the vitamin C contents and total superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. Lutein further increased expressions of copper-zinc SOD, manganese SOD and GPx mRNA. Conclusion The antioxidant properties of lutein contribute to the protection against LPS-induced uveitis, partially through the intervention of inflammation process.

Figure 1

Microscopic image of the eye tissues obtained from the LPS-treated mice. Photomicrographs of hematoxylin-eosin-stained sections of eyes from (A) control group and (B) model group 24 hours after the LPS injection. Views of the posterior chamber (PC) and retina (R); magnification ×400

Figure 2

Effects of lutein on the NO levels in the eyes of the mice treated with LPS. Seven-week-old male BALB/C mice were injected with LPS in the footpad at 100 mg per mouse. The results are presented as mean ± SD obtained from 18 animals in each group. ##P < 0.01: significantly different from the control group and **P < 0.01: from the model group

Figure 3

Effects of lutein on the MDA and ORAC levels in the eyes of the mice treated with LPS. Seven-week-old male BALB/C mice were injected with LPS in the footpad at 100 mg per mouse. The results are presented as mean ± SD obtained from 18 animals in each group. ##P < 0.01: significantly different from the control group and **P < 0.01: from the model group

Figure 4

Effects of lutein on the GSH and vitamin C levels in the eyes of the mice treated with LPS. Seven-week-old male BALB/C mice were injected with LPS in the footpad at 100 mg per mouse. The results are presented as mean ± SD obtained from 18 animals in each group. ##P < 0.01: significantly different from the control group and *P < 0.05, **P < 0.01: from the model group

Figure 5

Effects of lutein on the total SOD and GPx activities in the eyes of the mice treated with LPS. Seven-week-old male BALB/C mice were injected with LPS in the footpad at 100 mg per mouse. The results are presented as mean ± SD obtained from 18 animals in each group. ##P < 0.01: significantly different from the control group and **P < 0.01: from the model group

Figure 6

Effects of lutein on the mRNA expression of CuZnSOD, MnSOD and GPx in the eyes of the mice treated with LPS. (A) Agarose gel electrophoresis of RT-PCR amplication of CuZnSOD, MnSOD, GPx mRNA and β-actin mRNA. (B) Densiometric analysis of PCR products. Results were generated as relative intensity units by densitometry and expressed as the ratio to β-actin. The results are presented as mean ± SD obtained from 18 animals in each group. ##P < 0.01: significantly different from the control group and *P < 0.05, **P < 0.01: from the model group