Effects of Curcumin on LPS-induced Nitric Oxide Production from Murine Macrophages and PBMC of Humans with Respiratory Allergic Disease

Abstract

RATIONALE: Curcumin(Cur), found in curry, is a dietary pigment giving curry its unique color and has anti-inflammatory properties. Airway macrophages of asthmatics are a source of exhaled nitric oxide(NO), which is elevated in active asthma. We determined if Cur suppressed NO production from both a murine macrophage cell line (RAW264.7) and PBMC from allergic asthmatic adult humans(AAAH).METHODS: RAW264.7 cells were stimulated ± LPS (100 ng/ml) and ± Cur (1.4-5.4uM). Cur was also added to cells at 1 and 4 days before and after LPS activation to determine time course of suppression. PBMC from AAAH (n=4) ± LPS or allergen were treated ± Cur. NO2-, a measure of NO, was measured by Greiss reagent on days 3-6.RESULTS: Baseline LPS stimulated NO production from RAW264.7 cells(22.8uM) and was suppressed 73% with maximal Cur concentration(6.2uM); suppression was observed without LPS but not dose-dependently. Cur induced suppression was still present 1 and 4 days after LPS (60% and 9% respectively). NO levels were variable when Cur was added 1 day before LPS and not suppressed when Cur added 4 days before. (p<0.05) PBMC of AAAH produced variable amounts of NO (0.44-7uM) which were not increased with allergen/LPS(2.0-5.85uM) nor suppressed by Cur (2.0-7.42uM) (p=0.9).CONCLUSIONS: Cur suppresses LPS-induced NO production in RAW264.7 macrophages in a dose-dependent manner. Neither LPS or allergen stimulated NO production from PBMC of AAAH so evaluation of NO suppressive capacity of Cur was not optimal. The antioxidant activity of Cur on NO production by airway macrophages in asthma needs further investigation. RATIONALE: Curcumin(Cur), found in curry, is a dietary pigment giving curry its unique color and has anti-inflammatory properties. Airway macrophages of asthmatics are a source of exhaled nitric oxide(NO), which is elevated in active asthma. We determined if Cur suppressed NO production from both a murine macrophage cell line (RAW264.7) and PBMC from allergic asthmatic adult humans(AAAH). METHODS: RAW264.7 cells were stimulated ± LPS (100 ng/ml) and ± Cur (1.4-5.4uM). Cur was also added to cells at 1 and 4 days before and after LPS activation to determine time course of suppression. PBMC from AAAH (n=4) ± LPS or allergen were treated ± Cur. NO2-, a measure of NO, was measured by Greiss reagent on days 3-6. RESULTS: Baseline LPS stimulated NO production from RAW264.7 cells(22.8uM) and was suppressed 73% with maximal Cur concentration(6.2uM); suppression was observed without LPS but not dose-dependently. Cur induced suppression was still present 1 and 4 days after LPS (60% and 9% respectively). NO levels were variable when Cur was added 1 day before LPS and not suppressed when Cur added 4 days before. (p<0.05) PBMC of AAAH produced variable amounts of NO (0.44-7uM) which were not increased with allergen/LPS(2.0-5.85uM) nor suppressed by Cur (2.0-7.42uM) (p=0.9). CONCLUSIONS: Cur suppresses LPS-induced NO production in RAW264.7 macrophages in a dose-dependent manner. Neither LPS or allergen stimulated NO production from PBMC of AAAH so evaluation of NO suppressive capacity of Cur was not optimal. The antioxidant activity of Cur on NO production by airway macrophages in asthma needs further investigation.