Aging Eye Study Uncovers Molecular Cascade Behind Blinding Retinal Scarring

Scientists have identified a previously unknown molecular chain of events that links the aging of the retina’s support layer to the formation of irreversible scar tissue beneath it, a process that robs millions of older adults of sharp central vision. The discovery, published in the journal GeroScience, centers on a little-studied protein called LAPTM5 and reveals how its accumulation in aging retinal cells sabotages the cell’s waste-disposal machinery, triggering a destructive inflammatory cascade that ultimately drives fibrotic scarring in age-related macular degeneration. The findings point to two concrete therapeutic strategies that showed striking benefits in aged laboratory animals, raising hopes for treatments that could address the hardest-to-treat stage of the leading cause of vision loss in the elderly.

Age-related macular degeneration, or AMD, affects the macula, the small central region of the retina responsible for the fine detail vision needed for reading, driving, and recognizing faces. While the neovascular form of the disease, characterized by abnormal blood vessel growth under the retina, can be partially managed with injections that suppress vessel growth, a substantial fraction of patients progress to subretinal fibrosis. In this stage, the tissue beneath the retina becomes stiffened by excessive deposits of extracellular matrix proteins, forming scars that permanently destroy photoreceptors and the vision they support. No approved therapy currently reverses or reliably halts this scarring, making it one of ophthalmology’s most urgent unmet needs.

At the heart of the new study is the retinal pigment epithelium, or RPE, a single layer of pigmented cells that sits just behind the photoreceptors and performs the metabolic heavy lifting that keeps them alive. The RPE is among the most metabolically demanding tissues in the body, and its decline with age is considered a core driver of AMD. The research team, led by Xiaowei Yang, Shenglai Zhang, and Yan Wang of Nantong University and collaborating institutions in China, began by examining human AMD specimens and a mouse model of accelerated aging induced by D-galactose, a sugar that when administered chronically produces many hallmarks of natural aging. In both settings, they found that LAPTM5, a protein embedded in lysosomal membranes, was significantly elevated, and that its levels tracked with gene-expression signatures of RPE senescence and fibrogenesis.

To determine whether LAPTM5 was merely a bystander or an active participant in the disease process, the researchers conducted gain- and loss-of-function experiments, artificially increasing or decreasing the protein’s abundance in RPE cells. The results were unambiguous. When LAPTM5 was overexpressed, RPE cells displayed the classic features of senescence: they stopped dividing, accumulated damage markers, and began secreting a potent cocktail of inflammatory and remodeling factors known collectively as the senescence-associated secretory phenotype, or SASP. Conversely, reducing LAPTM5 blunted these senescence programs. This established LAPTM5 as a genuine regulatory driver of RPE aging rather than a passive correlate.

The mechanistic core of the paper lies in what LAPTM5 does to two downstream partners. The team demonstrated that LAPTM5 physically interacts with WWP2, an E3 ubiquitin ligase, and shepherds it toward lysosome-dependent degradation. WWP2, in turn, normally attaches polyubiquitin chains to optineurin, or OPTN, a well-characterized autophagy receptor. Ubiquitinated OPTN is what allows damaged mitochondria to be recognized and engulfed by autophagosomes in a selective process called mitophagy. With WWP2 destroyed, OPTN loses its ubiquitin tags, mitophagy falters, and damaged mitochondria pile up inside the cell. The authors showed that this disruption affected both K48- and K63-linked ubiquitin chains on OPTN, effectively dismantling the quality-control system that aging RPE cells depend on to keep their mitochondrial fleet in working order.

The consequences of this mitochondrial breakdown extend far beyond energy metabolism. When mitophagy fails, the outer and inner membranes of compromised mitochondria become permeable, and fragments of mitochondrial DNA escape into the cytoplasm. To the cell’s surveillance systems, this cytosolic DNA looks exactly like a viral invasion. The cGAS enzyme detects the stray DNA and produces a signaling molecule that activates STING, an adaptor protein on the endoplasmic reticulum that ignites a sustained innate immune response. The researchers documented precisely this sequence: cytoplasmic mitochondrial DNA leakage and persistent cGAS-STING activation in LAPTM5-overexpressing cells, which in turn fueled the massive SASP release that characterizes senescent RPE.

That SASP is where the fibrosis story comes together. The inflammatory factors secreted by senescent RPE cells do not act in isolation; they signal to neighboring cells in a paracrine fashion. According to the study’s model, these signals drive adjacent RPE cells, fibroblasts, choroidal endothelial cells, and macrophages to transdifferentiate into myofibroblasts, the collagen-producing cells that build fibrotic scar tissue. RPE cells themselves undergo epithelial-mesenchymal transition, abandoning their supportive identity and adopting a matrix-secreting, migratory phenotype. The authors note that the paracrine signaling and downstream fibrotic events in this model are inferred from the published literature rather than fully validated experimentally in this study, an important caveat that future work will need to address directly.

The translational experiments provide the study’s most exciting results. Using an adeno-associated virus vector to specifically knock down Laptm5 in the RPE of aged mice, the team achieved a marked reduction in subretinal fibrotic lesions, demonstrating that the protein is not just a marker but a druggable point of intervention. In parallel, the researchers tested H-151, a pharmacological inhibitor of STING, and found that blocking the inflammatory arm of the cascade significantly attenuated the progression of epithelial-mesenchymal transition. Together, these two approaches validate both the upstream trigger and the downstream inflammatory amplifier of the pathway as viable therapeutic targets, offering a rare dual-entry point into a disease process that has resisted treatment for decades.

The identification of LAPTM5 as a senescence regulator also fits into a broader and rapidly expanding picture of how lysosomal dysfunction and innate immune activation conspire to drive aging across tissues. Recent work has implicated the cGAS-STING axis in fibrotic disease of the kidney, lung, and heart, and mitophagy failure has emerged as a recurring theme in neurodegeneration and cardiovascular aging. LAPTM5 itself has previously been linked to inflammatory signaling in macrophages, STING-mediated inflammation in rosacea, tubular senescence in chronic kidney disease, and poor outcomes in several cancers. The new study extends this portfolio to the eye and, crucially, supplies the missing mechanistic link explaining how a lysosomal protein can connect mitochondrial quality control to immune activation and tissue scarring.

Significant work remains before these findings reach the clinic. The study relied heavily on a D-galactose-induced aging model, which accelerates certain aging phenotypes but does not fully recapitulate the decades-long, multifactorial development of human AMD, and the paracrine steps connecting SASP release to myofibroblast formation remain partly inferential. Delivering gene-silencing therapies to the RPE also poses practical challenges, even though the subretinal space is one of the more accessible targets for AAV-based ocular gene therapy. Still, the demonstration that a single lysosomal protein sits atop a cascade connecting senescence, mitophagy, innate immunity, and fibrosis gives researchers a coherent framework for intervention, and for the growing population of patients facing fibrotic AMD, it transforms a seemingly irreversible process into a pathway with identifiable, and potentially blockable, molecular checkpoints.

Subject of Research: The role of the LAPTM5-WWP2-OPTN mitophagy cascade and cGAS-STING signaling in retinal pigment epithelium senescence and subretinal fibrosis in age-related macular degeneration

Article Title: LAPTM5 correlates with RPE senescence and subretinal fibrosis through the LAPTM5-WWP2-OPTN mitophagy cascade and cGAS/STING activation in a D-galactose-induced aging model

Article References: Yang, X., Zhang, S., Wang, Y., Shi, J., Li, W., Lou, X., Yu, Y., Zhang, J., & Sang, A. (2026). LAPTM5 correlates with RPE senescence and subretinal fibrosis through the LAPTM5-WWP2-OPTN mitophagy cascade and cGAS/STING activation in a D-galactose-induced aging model. GeroScience. https://doi.org/10.1007/s11357-026-02506-2

Image Credits: AI Generated

DOI: 10.1007/s11357-026-02506-2

Keywords: age-related macular degeneration, retinal pigment epithelium, LAPTM5, mitophagy, optineurin, WWP2, cGAS-STING, cellular senescence, SASP, subretinal fibrosis, epithelial-mesenchymal transition, GeroScience