Aged red garlic extract reduces lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophages and acute pulmonary inflammation through haeme oxygenase-1 induction

Aim It is known that garlic has antioxidative and anti-inflammatory properties. Aged red garlic (ARG), a novel aged garlic formulation, has higher antioxidant effects than fresh raw garlic. This study was performed to examine the anti-inflammatory effects of ARG extract (ARGE).

Methods The anti-inflammatory effects of ARGE were evaluated in the lipopolysaccharide (LPS)-treated Raw 264.7 macrophages and acute lung inflammatory mice. NO production was determined by the Griess method, and iNOS, HO-1 and COX-2 expressions were measured using Western blot analysis. Histology and inflammation extent of lung were analysed using haematoxylin–eosin staining and immunohistochemistry.
Results ARGE treatment markedly reduced LPS-induced nitrite production in RAW 264.7 macrophages and reduced inducible nitric oxide synthase (iNOS) expression. Treatment of cells with ARGE led to a significant increase in haeme oxygenase-1 (HO-1) protein expression, which was mediated by stimulating the expression of nuclear factor erythroid 2-related factor 2 (Nrf2). Treatment with zinc protoporphyrin, a selective inhibitor of HO-1, significantly reversed the ARGE-mediated inhibition
of nitrite production (P < 0.05). In LPS-induced inflammatory mice, ARGE treatment down-regulated iNOS and COX-2 expressions, while it up-regulated HO-1 expression.
Conclusion These results show that ARGE reduces LPS-induced nitric oxide production in RAW 264.7 macrophages through HO-1 induction and suggest that ARGE may have potential effects on prevention and  treatment of acute inflammatory lung injury.

Keywords garlic, haeme oxygenase-1, lipopolysaccharide, macrophage, nitric oxide.