Abstract
Purpose :
Accumulation of cytosolic DNA in cells exposed to oxidative stress (OS) potently triggers cGAS-STING signaling activation and leads to an enhanced immune response. The interaction between OS and inflammation has a significant impact on RPE and retinal degeneration. However, the relationship between OS-mediated DNA damage, cytosolic leakage, and retinal inflammation remains unclear. Additionally, drugs that promote the clearance of cytosolic DNA may help to inhibit unwanted innate immune responses during retina degeneration. Recently, BRD4 has been reported as a transcription repressor for autophagy genes. In this study, we aim to investigate whether the BRD4 inhibitor JQ1 can promote the clearance of cytosolic DNA and inhibit retinal inflammation.
Methods :
To induce the OS-induced retinal degeneration mouse model, C57BL/6J mice (5-6 weeks) were intraperitoneally injected with 35 mg/kg of sodium iodate (SI). The control mice were injected with PBS. At 2 h post SI injection, JQ1 (50 mg/kg) or vehicle was intraperitoneally injected, and the injection was performed daily for 3 days. Immunofluorescence was used to determine DNA leakage in the cytoplasm. Chloroquine (CQ, 1μM, 6 h) was used to block autophagy in ARPE-19 cell line. Western blot was used to evaluate the activation of autophagy. To determine whether JQ1 promotes the clearance of cytosolic DNA, Cy3-DNA was transfected into ARPE LC3-GFP cells, and live cell imaging was performed 6 h after transfection with or without the addition of JQ1 (1 or 10 μM). ARPE cells were transfected with H2O2-treated genomic DNA, and inflammatory factors were determined by qRT-PCR analysis.
Results :
JQ1 effectively reduces DNA leakage induced by oxidative stress in the mouse retina. Additionally, JQ1 enhances the autophagy-dependent clearance of cytosolic DNA. This was evidenced by an increase in the levels of the lapidated form of LC3 (LC3II), and the inhibition of autophagic flux by chloroquine treatment. Furthermore, upon transfection of H2O2-treated genomic DNA, JQ1 significantly decreases the expression of IL6 and IFNβ, while this repression is partially reversed by CQ.
Conclusions :
In summary, our findings demonstrate that JQ1 facilitates the clearance of cytosolic DNA and effectively inhibits retinal inflammation. These results suggest that JQ1 holds promise as a potential therapeutic drug for the treatment of retinal inflammation.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.