Enhancing lysosome function via TFEB activation reduces lipofuscin-like granules in the retinal pigment epithelium.

Age-Related Changes in bis-Retinoids of Lipofuscin Granules in Human Retinal Pigment Epithelium Cells

ADORA2A activation restores lysosomal function and photoreceptor outer segment degradation in stressed retinal pigment epithelium

Background Age-related macular degeneration (AMD) involves early retinal pigment epithelium (RPE) dysfunction and impaired processing of photoreceptor outer segments (POS). We investigated whether ADORA2A regulates post-ingestive POS handling and lysosomal recovery under AMD-relevant stress. Methods A2E-stressed ARPE-19 cells, primary porcine RPE cells, and a sodium iodate-induced mouse model were studied. ADORA2A was activated with CGS21680 and inhibited with ZM241385. POS handling, LC3B/Rubicon association with POS, lysosomal function, Rubicon depletion, chronic stress phenotypes, and retinal protection were assessed. Results A2E increased ADORA2A expression while preserving receptor-dependent cAMP responsiveness. CGS21680 had modest effects on early POS binding and uptake but enhanced post-ingestive POS clearance and rhodopsin degradation; these effects were attenuated by ZM241385 and ADORA2A knockdown. CGS21680 increased LC3B and Rubicon association with POS-containing structures, improved lysosomal acidification, and restored DQ Green BSA processing, Cathepsin D activity, and V-ATPase-associated assembly. Bafilomycin A1 increased LC3-II and p62 accumulation and impaired CGS21680-associated POS clearance, supporting lysosome-dependent turnover. Rubicon depletion attenuated CGS21680-associated improvements in POS clearance and lysosomal acidification. CGS21680 also reduced chronic stress-associated autofluorescence, oxidative stress, apoptosis, and junctional disruption. These protective effects were reproduced in primary RPE cells. In sodium iodate-injured mice, CGS21680 preserved outer retinal structure, reduced FITC-BSA leakage, improved electroretinographic responses, and was accompanied by increased CREB phosphorylation and recovery of Cathepsin D proteolytic competence. Conclusion ADORA2A activation promotes Rubicon-associated, lysosome-dependent LC3 processing of internalized POS and restores lysosomal degradative competence, supporting ADORA2A as a potential therapeutic target for early AMD.

The role of NLRP3 inflammasome in age-related macular degeneration: mechanisms and therapeutic prospects

Age-related macular degeneration (AMD) is a fundus oculi disease that progressively impairs the central vision of patients. To date, its pathogenesis has not been fully elucidated, and therapeutic options for dry AMD remain limited. Recently, chronic low-grade inflammation has been recognized as an important pathogenic factor in various neurodegenerative diseases, including AMD. The NLRP3 inflammasome, a key component of the innate immune system, has emerged as a critical integrator of retinal stress signals. This review first delineates the molecular architecture and activation modalities of the NLRP3 inflammasome, encompassing canonical, noncanonical, and alternative pathways, as well as its downstream cell death programs, with a particular focus on pyroptosis and PANoptosis. We describe how AMD-associated danger signals converge on NLRP3 inflammasome activation within distinct retinal cell populations and discuss how cell-type-specific NLRP3 responses differently shape retinal homeostasis, degeneration, and neovascularization. We further summarize current evidence indicating that the pathological consequences of NLRP3 activation vary across AMD progression, from amplification of chronic inflammation in early and intermediate AMD to promotion of retinal atrophy in geographic atrophy and angiogenic signaling in neovascular AMD. Finally, we evaluate emerging therapeutic strategies targeting the NLRP3 pathway and discuss the major translational challenges related to cell-type and disease-stage specificity, retinal delivery, and long-term safety. By integrating retinal triggers, cellular responses, senescence-associated inflammation, inflammatory cell death, disease phenotypes, and therapeutic opportunities into a unified framework, this review provides a comprehensive perspective on the role of NLRP3 inflammasome signaling in AMD pathogenesis and treatment.

A peripheral subpopulation of retinal pigment epithelium resists oxidative damage through SERPINE3-mediated caspase-1 inhibition

A peripheral RPE subpopulation is identified through spatial, transcriptomic, and functional analyses, thereby contributing to the understanding of the heterogeneity of degenerative RPE cells and highlighting SERPINE3 as a protective factor with therapeutic potential for macular atrophy.

CCR1 signaling as a common injury pathway in retinal degeneration.

Inflammation is a key driver of atrophic Age-Related Macular Degeneration (aAMD), and also plays a role in Inherited Retinal Degenerations (IRDs), two major causes of irreversible visual loss. We previously demonstrated that the C-C chemokine receptor type 1 (CCR1) is upregulated in monocytes from AMD patients, and that it mediates the recruitment of neurotoxic macrophages and activates Müller glial cells in rodent model of photic retinal injury. Here we report that CCR1 is expressed in Müller glia in eyes affected by AMD and that variants in CCR1 are potentially associated with the rate of macular atrophy progression in AMD. We also show that Ccr1 deletion is associated with reduced inflammation, and with rescue of photoreceptor integrity and function in Crb1rd8/rd8 mice and in Pde6brd10 mice, two models of genetically-driven retinal degeneration. Finally, we demonstrate that treatment with small molecule CCR1 antagonists delayed photoreceptor loss in Pde6brd10 mice. These data suggest that CCR1 is a mediator of retinal inflammation and injury in different forms of retinal degeneration, and that CCR1 may serve as a novel therapeutic target for atrophic AMD and IRDs.

Restoration of impaired lysosomal function mitigates drusen-like deposit formation and cell death in Malattia Leventinese

Malattia Leventinese (MAL) is an inherited macular degeneration disorder characterized by retinal drusen formation in adolescence, leading to vision loss. A mutation in the fibulin-3 gene (EFEMP1) causes MAL; however, the mechanisms underlying disease onset and drusen formation remain unclear. In this study, we generated induced pluripotent stem cell–derived retinal pigment epithelial (iPSC-RPE) cells from a patient with MAL to investigate disease mechanisms and potential therapies. MAL iPSC-RPE exhibited fibulin-3 and apolipoprotein E (ApoE) aggregation, increased endoplasmic reticulum stress, and enhanced apoptosis. Long-term culture with photoreceptor outer segments led to drusen-like deposits containing ApoE, complement components, and collagen IV accumulation, and it showed activation of matrix metalloproteinase-2 (MMP2). Untargeted lipid analysis revealed increased hexosylceramide and bis-monoacylglycerophosphate levels in MAL iPSC-RPE cells. A key pathological feature was lysosomal dysfunction associated with altered regulation of lysosomal gene programs, including reduced transcription factor EB transcript levels. Treatment with trehalose, a lysosome-modulating compound, increased lysosomal content and function, reducing drusen-like deposit formation, inhibiting MMP2 activation, and suppressing apoptosis. This study highlighted lysosomal dysfunction as a contributor to RPE damage, drusen-like deposit accumulation, and extracellular matrix degradation. Pharmacological restoration of lysosomal function alleviated these defects, suggesting therapeutic potential for MAL and other drusen-related diseases, including age-related macular degeneration.