Differential response to laser injury between young and aging retina

Abstract

Purpose : Aging is a major risk factor for retinal degenerative and angiogenic diseases, including macular fibrosis secondary to nAMD. We previously found that old age promoted subretinal fibrosis. This study aimed to understand the impact of aging on retinal response to injury.

Methods : Young (3 months) and aged (15 months) mice were subjected to two-stage laser-induced subretinal fibrosis. Twenty days later, retinal tissues were processed for bulk RNA-seq. DESeq2 was used to determine the differentially expressed genes (DEGs). Gene Ontology, wiki pathways and reactome were used to analyse the enriched pathways and functions. The expression of the selected DEGs was verified by qRT-PCR.

Results : A total of 229 DEGs were identified in the normal ageing retina compared to the young retina. The top 20 enriched pathways were related to inflammation, in particular, the complement pathway. The 10 highest degree DEGs calculated by the Cytohubba plugin of Cytoscape belonged to the complement system (C1qa,C1qb,C1qc) and extracellular matrix organization (e.g.,Ctss,P4ha2, Col4a4).
Twenty days after the second laser, 280 and 190 DEGs were detected in the aged and young lasered retina compared to the non-lasered retina of their counterparts. The top 10 enriched pathways in the lasered young retina were related to contraction, visual function and complement activation indicatives of retinal remodeling and repairing visual function. Whereas the pathways affected in the lasered aged retina were mostly related to inflammation and immune regulation, including leukocyte activation and phagocytosis.
Three hundred and fifty-seven DEGs were detected in the lasered aged retina compared to the lasered young retina. Enrichment analysis showed that complement and microglial activation were mostly affected in the aged retina following laser injury. The core genes of these pathways including microglia-related genes (Itgam,Adgre1, Aif1,Cd68,P2ry12,Cx3cr1,Tmem119,Trem2) and complement (C1qa,C1qb, C1qc,C1s1,C1ra,C3,C3ar1,C4b,Cfh,Cfb,Cd46) were further verified by qRT-PCR.

Conclusions : Our results suggest that the young retina undergoes a repair and remodeling process in response to repeated laser injury, whereas the aged retina suffers from persistent inflammation after repeated laser injury. The uncontrolled injury-induced inflammation in the aged retina may contribute to age-related retinal degeneration and its complications such as macular fibrosis in nAMD.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.