Enzyme-treated asparagus extract prevents hydrogen peroxide- induced pro-inflammatory responses by suppressing p65 nuclear translocation in skin L929 fibroblasts

We recently reported that enzyme-treated asparagus extract (ETAS) attenuates hydrogen peroxide (H₂O₂)-stimulated matrix metalloproteinase-9 expression in skin fibroblast L929 cells. To further elucidate the anti-aging effects of ETAS on skin, we examined whether ETAS has preventive effects on H₂O₂-induced pro-inflammatory responses of skin fibroblasts. H₂O₂ induced Ser536 phosphorylation and nuclear accumulation of nuclear factor-κB (NF-κB) p65, and increased the mRNA levels of interleukin-12α (IL-12α) and inducible nitric oxide synthase (iNOS) in L929 cells. Pretreatment of the cells with JSH-23, an inhibitor of NF-κB nuclear translocation, abolished the H₂O₂-induced expression of IL-12α and iNOS, indicating that the increased transcription is regulated by p65. The H₂O₂-stimulated nuclear accumulation of p65 and induction of IL-12α and iNOS mRNA were significantly attenuated after pretreatment with ETAS for 3 h, and these responses were completely abolished when the duration was extended to 24 h. However, ETAS did not affect the H₂O₂-stimulated degradation of IκBα and phosphorylation of p65. On the other hand, ETAS treatment for 24 h resulted in decreased protein levels of importin-α. These results suggest that ETAS prevents pro-inflammatory responses by suppressing the p65 nuclear translocation in skin fibroblasts induced by H₂O₂.