Aqueous Humor Exosomal Membrane Proteins: Decoding Pathogenic Molecular Signatures in Retinitis Pigmentosa.

Purpose: To establish a cell origin tracing framework for aqueous humor (AH) exosomal membrane proteins and decipher their pathological implications in retinitis pigmentosa (RP). Methods: In this prospective cohort study, comprehensive ophthalmic evaluations were conducted in 14 patients with RP with concurrent cataracts and 7 age-matched senile cataract controls. AH samples from these cohorts underwent exosomal membrane protein profiling via EVArray technology. Integrated bioinformatics analysis incorporated single-cell RNA sequencing data sets from human ocular tissues. Gene Ontology (GO) enrichment analysis with cellular trajectory mapping was performed to elucidate disease-associated pathways. Results: Patients with RP in this cohort predominantly exhibited characteristic fundus pathology. EVArray profiling of AH exosomes revealed nine differentially expressed membrane proteins, comprising three downregulated and six upregulated proteins. Single-cell deconvolution mapped these proteins to immune (T cells, hyalocytes, monocytes/macrophages) and retinal glial cell lineages. Key findings showed (1) CTLA4 upregulation (1.7-fold, P = 0.021), reflecting T-cell checkpoint activation; (2) CSF-1R suppression (0.36-fold, P < 0.0001), suggesting immune homeostasis disruption; and (3) DKK1 downregulation (0.72-fold, P = 0.015), indicating activation of glia-derived Wnt signaling. GO analysis highlighted cytokine signaling (GO:0019221) and MAPK cascade activation (GO:0043410) as central pathways. Conclusions: This study demonstrates that AH exosomal membrane proteins play a role in uncovering immunopathogenic cascades and glial reactivity underpinning disease progression in RP. Furthermore, AH exosomal proteins hold promise as potential biomarkers for monitoring disease activity. Translational Relevance: These findings highlight that AH exosomal proteins hold promise as potential biomarkers and propose that immunomodulation and glial protection serve as conservative strategies to delay progression in cases of genetically unresolved RP.