Abstract
The medicinal herb Lycium barbarum fruit has been widely used for improving and maintaining the health of the eyes in the Far East for many centuries. This study is aimed at investigating whether protective effects generated from the aqueous (LBA) and ethanol (LBE) extracts of the L. barbarum fruit existed against oxidative stress-induced apoptosis in human retinal pigment epithelial cells. L. barbarum extracts LBA and LBE exerted the activity of ROS scavenging and rescued UVB irradiation-induced growth inhibition in retinal pigment epithelial ARPE-19 cells. Compared to LBA, the ethanol extract LBE exerted a superior protective activity on UVB-induced growth arrest in ARPE-19 cells. Both L. barbarum extracts significantly reduced cell cycle G2-arrest population in ARPE-19 cells. Furthermore, the cytometer-based Annexin V/propidium iodide staining assay further showed that both L. barbarum extracts protected ARPE-19 cells from UVB-induced apoptosis. L. barbarum extracts also reduced the activation of γH2AX, a sensor of DNA damage in ARPE-19 cells in a dose-responsive manner. By using Ingenuity Pathway Analysis (IPA), the bioinformatics revealed that the protective effects of both LBA and LBE extracts might be involved in three signaling pathways, especially the Toll-like receptor (TLR) pathway associated with cellular proliferation. Our study suggests that both ethanol and aqueous extracts of L. barbarum exhibit antioxidant activity and rescue UVB-induced apoptosis of ARPE-19 cells. Collectively, the ethanol extract exerts a superior effect on rescuing UVB-induced growth arrest of ARPE-19 compared to the aqueous extract, which might be associated with the activation of TLR signaling. Our present work will benefit the preventive strategy of herbal medicine-based vision protection for treating eye diseases such as age-related macular degeneration in the future.
Highlights
Age-related macular degeneration (AMD), a progressive macular retinal disease with degenerative changes, can be divided into atrophic and exudative, characterized by the progressive atrophy of retinal pigment epithelial (RPE) cells and the formation of choroidal neovascularization (CNV) [1]
The results showed that the irradiation of 50 mJ/cm2 UVB significantly induced cell death of RPE cells
Our results showed that the pretreatments of both LBE and LBA significantly attenuated the activation of γH2AX in a dose-responsive manner, suggesting a protective role of Lycium barbarum (LB) extracts in UVB-induced DNA damage of human Arising retinal pigment epithelia cell line-19 (ARPE-19) cells
Summary
Age-related macular degeneration (AMD), a progressive macular retinal disease with degenerative changes, can be divided into atrophic and exudative, characterized by the progressive atrophy of retinal pigment epithelial (RPE) cells and the formation of choroidal neovascularization (CNV) [1]. If oxidative damage occurs in RPE cells, the breakdown of photoreceptor cells would quickly follow and visual acuity might become damaged [2]. A previous study showed that LBP (Lycium barbarum polysaccharides) extracted from the fruit of L. barbarum might be responsible for the above biological activities [16]. Based on the antioxidant activity of L. barbarum, many studies have demonstrated that LBP has a protective effect against oxidative injury in cells [17,18,19,20], and many studies have focused on the bioactivities of this extract of L. barbarum. We prepared both aqueous (LBA) and ethanol (LBE) extracts of LB and investigated the protective effects of LBA or LBE on human retinal pigment epithelial (ARPE-19) cells from UVB damage, notably proliferation inhibition and apoptosis. We discussed the possible mechanism underlying L. barbarum extract-mediated protective effect on retinal pigment epithelial cells
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