Attenuation of Lipopolysaccharide-Induced Inflammation in RAW264.7 Cells by Fermented Hylocereus undulatus Peels
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Abstract:
To investigate the attenuating effects of fermented Hylocereus undulatus peels (FHP) on lipopolysaccharide (LPS)-induced inflammation in RAW264.7 cells, and the mechanisms of attenuation, Hylocereus undulatus peels were fermented using Lactobacillus casei CICC20280. A methyl-thiazolyl-tetrazolium reduction assay was used to determine FHP cytotoxicity at different concentrations (50, 100, 200, 400 and 800 μg/mL). The following groups were included: a control group, an LPS-induced inflammation model group, and five groups treated with LPS and different concentrations of FHP. Nitric oxide (NO), reactive oxygen species (ROS), and cytokines (TNF-α, IL-1β, IL-6, and IL-10) in cell culture supernatants were quantitated using various molecular analysis techniques, including Griess, DCFH-DA fluorescence, and ELISA assays. RT-PCR was used to detect expression of NF-κB pathway components (TLR4/MyD88/NF-κB) and pro-inflammatory factors. FHP at concentrations of ≤400 μg/mL is non-toxic to RAW264.7 cells. FHP significantly decreases (p<0.05) concentrations of pro-inflammatory factors including NO, ROS, TNF-α, IL-1β and IL-6, by an average of 76.40%, and increases the concentration of the anti-inflammatory factor IL-10, by an average of 173.72%, in a dose-dependent manner, compared to the LPS-induced inflammation model group. Expression levels of TLR4, MyD88, NF-κB and TNF-α, IL-1β, IL-6 were significantly down-regulated (p<0.01) by FHP. In summary, FHP displays readily detectable attenuating effects on LPS-induced inflammation in RAW264.7 cells, probably by inhibiting secretion of pro-inflammatory mediators and increasing levels of anti-inflammatory factors, via a mechanism possibly associated with an NF-κB pathway.
