Abstract
Purpose: This study investigated the protective effect of Kaempferol against hydrogen peroxides (H2O2)-induced retinal pigment epithelium (RPE) cell oxidative stress, inflammation, and apoptosis and investigated if this protection involves modulation of poly(ADP-ribose) polymerase-1 (PARP1)/silent information regulator 1 (SIRT1) signaling pathway.
Methods: ARPE-19 cells were pretreated with increasing doses of Kaempferol (10, 25, 50, 100 mu M) for 24 h in Dulbecco's modified Eagle's medium/F-12 medium with or without postincubation with H2O2. Control cells remained untreated.
Results: Kaempferol, in a dose-dependent manner, significantly increased cell survival and reduced levels of reactive oxygen species, malondialdehyde, single-stranded DNA (ssDNA), and lactate dehydrogenase but increased levels of glutathione (GSH) and manganese-superoxide dismutase (MnSOD) in H2O2-treated ARPE-19 cells. It also increased GSH and MnSOD in a dose-dependent manner in control + Kaempferol treated cells. At a dose of 50 mu M, the most effective dose, Kaempferol also inhibited protein levels of tumor necrosis factor alpha and interleukin-6, nuclear activity and protein levels of total, acetylated, and cleaved PARP1, and increased nuclear levels and activity of SIRT1 in H2O2-treated cells. In parallel, it increased total nuclear levels of Nrf2 but reduced the acetylation of p53, Nrf2, nuclear factor-kappa B (NF-kappa B) p65, and forkhead transcriptional factor 1 (FOXO1). Of interest, the stimulatory role of Kaempferol in the nuclear accumulation and activation of SIRT1 and the nuclear levels of Nrf2, as well as in reducing the acetylation of Nrf2, NF-kappa B p65, and FOXO1, was shown in nuclei of control + Kaempferol-treated cells.
Conclusion: Kaempferol protective effect against H2O2-induced ARPE-19 damage involves antioxidant and anti-inflammatory effects mediated, at least, by stimulating the nuclear accumulation, activation, and deacetylase ability of SIRT1 and concurrent inhibition of PARP1.