Oxidative stress is defined as a persistent imbalance in the production of oxidative and antioxidant components. The oxidative stress induces tissue destruction and functional disorders, which occurs in several diseases such as cardiovascular disease, diabetes, and periodontitis. Some antioxidant enzymes play an important role in host defense and their expressions are regulated by transcription factors, Nrf2 and Keap1. Although Porphyromonas gingivalis lipopolysaccharide (P-LPS) is a major pathogenic factor in periodontitis, the effect of P-LPS on oxidative stress in human gingival fibroblasts is not fully elucidated. In the present study, we investigated the expression of an oxidative stress marker, antioxidant enzymes, cytokines, and antimicrobial peptides in P-LPS-treated gingival fibroblasts.
Methods:
Human gingival fibroblasts were cultured with P-LPS. Oxidative stress level was evaluated by production of 8-Hydroxy-2’-deoxyguanosine (8-OHdG), an oxidative stress marker. The mRNAs expressions of cytokines, antimicrobial peptides, and antioxidant enzymes were estimated by RT-PCR. The amount of HO-1, an antioxidant enzyme, was determined by ELISA and nuclear translocation of Nrf2 was identified by western blotting.
Results: P-LPS increased mRNA levels of 8-OHdG, cytokines (IL-6, TNF-α), antimicrobial peptides (S100A9, β-defensin2), HO-1, Nrf2, and Keap1 in cultured gingival fibroblasts. P-LPS enhanced nuclear translocation of Nrf2. P-LPS did not affect on the expression of other antioxidant enzymes including NQO-1, GCLC, and GCLM.
Conclusions:
These results suggest that P-LPS may induce antioxidant defense system and oxidative stress response in human gingival fibroblasts.