Aβ-induced senescent retinal pigment epithelial cells create a proinflammatory microenvironment in AMD

Area of Science:

• Ophthalmology
• Cell Biology
• Immunology

Background:

• Chronic inflammation is a key factor in age-related macular degeneration (AMD) pathogenesis, often linked to immune cell activation.
• Senescent cells, through their altered secretory phenotype, represent a potential additional source of chronic inflammation.
• Amyloid-beta (Aβ) may induce senescence in retinal pigment epithelial (RPE) cells, impacting tissue microenvironment.

Purpose of the Study:

• To investigate the hypothesis that altered secretory patterns in Aβ-induced senescent RPE cells contribute to compromised RPE barrier integrity and chronic inflammation in AMD.
• To explore the role of senescent RPE cells in the inflammatory processes associated with AMD.

Main Methods:

• Senescence was assessed using SA-β-Galactosidase activity, p16(INK4a) and ATM expression, and cell cycle analysis.
• Expressions of IL-8 and matrix metalloproteinases (MMPs) were quantified using RT-PCR, ELISA, and gelatin zymography.
• RPE barrier integrity was evaluated by immunochemistry (ZO-1, claudin-19, occludin), Western blot, transepithelial resistance (TER), and FITC-dextran diffusion, with MMP-9 inhibition via RNA interference.

Main Results:

• Aβ exposure induced senescence in RPE cells, leading to increased secretion of IL-8 and MMP-9.
• MMP-9 secretion correlated with compromised RPE barrier integrity and enhanced IL-8 activation.
• Silencing MMP-9 effectively preserved the barrier integrity of senescent RPE cells.

Conclusions:

• The altered secretory phenotype of senescent RPE cells, particularly MMP-9 and IL-8, plays a significant role in AMD pathogenesis.
• Targeting senescent RPE cells and their secretory products may offer a therapeutic strategy for AMD-related inflammation.