Abstract
Purpose :
Ultraviolet (UV)-induced photoaging is the most important environmental factor for skin damage, but it was unclear on human conjunctival epithelial cells (CjECs). In this study, we investigated the presence of senescent cells of human conjunctival epithelium and the effects of UVA on the CjECs.
Methods :
Our study involved 16 conjunctival tissue samples (10 elderly and 6 young), mean age [elderly: 75.8±3.7 years (72-81), young: 53.3±8 years (38-59)], and primary CjECs obtained from human donor eyes. CjECs were cultured and irradiated with UVA at 15 J/cm2. The senescence marker (p16), stem cell markers (Ki67, p63), tight-junction marker (ZO-1) in the conjunctival tissues was examined by immunostaining and PCR. In UVA-irradiated CjECs, the senescence markers (p16, p21), inflammatory cytokines (TNF-α, IL-6, IL-1β, GDF-15), matrix metalloproteinases (MMP3, MMP9), chemokines (CXCL6, CCL9) were assessed by western blotting and PCR.
Results :
The expression of p16 was found in 10 of 10 (100%) of the elderly conjunctival tissues, while the expression in young tissues was found in 1 of 6 specimens (16.7%). Positive rate of p16 was significantly elevated in the elderly (15±7.8%) compared to the young tissues (0.3±0.7%) (P< 0.05). Positive rate of Ki67and p63 was significantly reduced in the elderly (4.4±2% and 26±6.1%) compared to the young tissues (1.7±1.7% and 16.5±9.5%) respectively (P< 0.05). ZO-1 expression was reduced in tissue samples showing p16-positivity but was retained in tissue samples in which p16 was undetectable. The expression of p16 and p21 was significantly increase both at RNA and protein levels in UVA-irradiated CjECs compared to control cells (P<0.05) and in inflammatory cytokines, matrix metalloproteinases, chemokines at RNA levels.
Conclusions :
A significant increase in p16-expressing senescent cells and decreased expression of ZO-1 were observed in elderly conjunctival tissue, and UVA-irradiated CjECs increased expression of many inflammation-related genes.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.