Vaccinium oldhamii fruits improve insulin resistance by inhibiting inflammation in macrophages and adipocytes.

BACKGROUND/OBJECTIVES: This study aimed to elucidate the mechanisms by which Vaccinium oldhamii water extract (VOW) modulates inflammation and insulin sensitivity in 3T3-L1 cells and RAW 264.7 macrophages. MATERIALS/METHODS: VOW's effects on inflammation and insulin resistance were assessed in macrophages and adipocytes. To investigate crosstalk between macrophages and adipocytes, RAW 264.7 cells were cultured in the upper chamber while mature 3T3-L1 cells were cultured in the lower chamber. The medium was collected to measure glucose uptake. RESULTS: Our findings indicate that VOW significantly reduces the protein expression of inflammatory cytokines, including extracellular signal-regulated kinase, Jun N-terminal kinase, mitogen-activated protein kinase p38, and nuclear factor kappa-light-chain-enhancer of activated B cells, which are upregulated by lipopolysaccharide and inhibit reactive oxygen species expression. In mature 3T3-L1 cells with type 2 diabetes mellitus, VOW treatment enhances the protein expression of phosphatidylinositol 3-kinase, Ak strain transforming, and insulin receptor substrate, which are critical for insulin sensitivity, and facilitates the translocation of glucose transporter type 4 from the cytosol to the plasma membrane. Additionally, treatment of 3T3-L1 cells with macrophage-conditioned media results in decreased insulin sensitivity, whereas VOW treatment restores insulin signaling protein expression in a dose-dependent manner. CONCLUSION: Our study suggests that VOW modulates the interplay between increased insulin sensitivity and inflammation.