Xylose-Taurine Reduced Suppresses the Inflammatory Responses in Lipopolysaccharide-Stimulated Raw264.7 Macrophages

Effect of saccharin on inflammation in 3T3-L1 adipocytes and the related mechanism

BACKGROUND/OBJECTIVES

Excessive intake of simple sugars induces obesity and increases the risk of inflammation. Thus, interest in alternative sweeteners as a sugar substitute is increasing. The purpose of this study was to determine the effect of saccharin on inflammation in 3T3-L1 adipocytes.

MATERIALS/METHODS

3T3-L1 preadipocytes were differentiated into adipocytes. The adipocytes were treated with saccharin (0, 50, 100, and 200 µg/mL) for 24 h. Inflammation was induced by exposure of treated adipocytes to lipopolysaccharide (LPS) for 18 h and cell proliferation was measured. The concentration of nitric oxide (NO) was measured by using Griess reagent. Protein expressions of nuclear factor kappa B (NF-κB) and inhibitor κB (IκB) were determined by western blot analysis. The mRNA expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin 1β (IL-1β), interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNF-α) were determined by real-time PCR.

RESULTS

Compared with the control group, the amount of NO and the mRNA expression of iNOS in the LPS-treated group were increased by about 17.6% and 46.9%, respectively, (P < 0.05), and those parameter levels were significantly decreased by saccharin treatment (P < 0.05). Protein expression of NF-κB was decreased and that of IκB was increased by saccharin treatment (P < 0.05). Saccharin decreased the mRNA expression of COX-2 and the inflammation cytokines (IL-1β, IL-6, MCP-1, and TNF-α) (P < 0.05).

CONCLUSIONS

The results of this study suggest that saccharin can inhibit LPS-induced inflammatory responses in 3T3-L1 adipocytes via the NF-κB pathway.

Ribose-Taurine Suppresses Inflammation Through NF-κB Regulation in Activated RAW 264.7 Macrophages

Ribose-taurine (Rib-T) suppressed the generation of inflammatory mediators and cytokines, such as nitric oxide (NO) and prostaglandin E2 (PGE2) through the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β induced by LPS was effectively blocked by Rib-T. Moreover, the anti-inflammatory actions of Rib-T were involved in its inhibitory effects against the nuclear translocation of nuclear factor-kappa B (NF-κB) p65, and NF-κB DNA-binding activity. These results suggest that the anti-inflammatory action of Rib-T is associated with NF-κB regulation.

Anti-inflammatory Action of Glucose-Taurine Reduced by Inhibiting NF-κB Activation in LPS-Activated RAW264.7 Macrophages

In the present study, we investigated the regulation of inflammatory effects by glucose-taurine reduced (G-T-R), a taurine-carbohydrate derivative, on lipopolysaccharide (LPS)-induced RAW264.7 macrophages. The anti-inflammatory action of G-T-R revealed that this derivative markedly inhibited the nitric oxide (NO) and prostaglandin E2 (PGE2) production in RAW264.7 macrophages induced by LPS. Suppression of NO and PGE2 production was involved in the inhibitory action by G-T-R on the inducible nitric oxide synthase and cyclooxygenase-2 proteins expression. G-T-R decreased the production of a variety of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and interleukin-6. Moreover, G-T-R effectively suppressed the nuclear factor-kappa B (NF-κB) activation in LPS-stimulated RAW264.7 macrophages according to evaluation of the molecular inflammatory mechanisms. Thus, we suggest that G-T-R modulates several inflammatory pathways mediated by NF-κB activation, demonstrating its potential or preventing and treating inflammatory conditions.