Green tea polyphenol extract in vivo attenuates inflammatory features of neutrophils from obese rats

Abstract

Purpose: Our study aimed to evaluate whether obesity induced by cafeteria diet changes the neutrophil effector/inflammatory function and whether treatment with green tea extract (GT) can improve neutrophil function.

Methods: Male Wistar rats were treated with GT by gavage (12 weeks/5 days/week; 500 mg/kg of body weight), and obesity was induced by cafeteria diet (8 weeks). Neutrophils were obtained from the peritoneal cavity (injection of oyster glycogen). The following analyses were performed: phagocytic capacity, chemotaxis, myeloperoxidase activity (MPO), hypochlorous acid (HOCl), superoxide anion (O 2 (·-) ), hydrogen peroxide (H2O2), IL-1β, IL-6 and TNFα, mRNA levels of inflammatory genes, calcium mobilisation, activities of antioxidant enzymes, hexokinase and G6PDH.

Results: Neutrophils from obese rats showed a significant decrease in migration capacity, H2O2 and HOCl production, MPO activity and O 2 (·-) production. Phagocytosis and CD11b mRNA levels were increased, while inflammatory cytokines release remained unmodified. mRNA levels of TLR4 and IκK were enhanced. Treatment of obese rats with GT increased neutrophil migration, MPO activity, H2O2, HOCl and O 2 (·-) production, whereas TNF-α and IL-6 were decreased (versus obese). Similar reductions in TLR4, IκK and CD11b mRNA were observed. Catalase and hexokinase were increased by obesity, while SOD and G6PDH were decreased. Treatment with GT reduced catalase and increased the GSH/GSSG ratio.

Conclusion: In response to a cafeteria diet, we found a decreased chemotaxis, H2O2 release, MPO activity and HOCl production. We also showed a significant immunomodulatory effect of GT on the obese condition recovering some of these factors such H2O2 and HOCl production, also reducing the levels of inflammatory cytokines.

Keywords: Catechins; Flavonoids; Immune system; Obesity; Polyphenols; Reactive oxygen species.