Kiyota, N. | Search bioRxiv

bioRxiv2026

VEGFA-Positive Macrophages Regulate Aqueous Humor Outflow in Aged Mice and Humans

Elevated intraocular pressure (IOP) and aging are major risk factors for primary open-angle glaucoma (POAG), but how aging affects IOP regulation remains poorly understood. IOP remains within a narrow range despite age-associated changes predicted to increase aqueous humor outflow (AHO) resistance at the interface between the trabecular meshwork and Schlemm's canal (SC), suggesting compensatory mechanisms preserve AHO homeostasis during aging. Single-cell RNA sequencing of mouse ocular angle tissues revealed immunomodulatory transcriptional reprogramming of SC endothelial cells in older mice, while mouse and human imaging showed reduced SC size and increased peri-SC macrophage accumulation with aging. Ligand-receptor analysis predicted enhanced macrophage-to-SC VEGFA-VEGFR signaling in aged and Tie2-haploinsufficient mice, an independent model of vascular stress and glaucoma risk. Deletion of Vegfa in CX3CR1+ macrophages increased IOP and reduced AHO facility in 9-month-old mice, demonstrating that macrophage-derived VEGFA supports AHO homeostasis. Tie2 haploinsufficiency recapitulated key age-associated SC niche changes, including peri-SC macrophage accumulation, whereas gene therapy boosting TIE2 activity protected wild-type mice against age-related changes. Together, these findings identify peri-SC macrophage-derived VEGFA as a compensatory mechanism maintaining AHO homeostasis during aging and vascular stress and support TIE2 activation as a therapeutic strategy to preserve SC function and IOP regulation.

physiology↗

bioRxiv2025

Piezo1 Activates an Autocrine Angiopoietin-2-Integrin Signaling Loop in Schlemm's Canal to Regulate Intraocular Pressure

Elevated intraocular pressure (IOP), driven by increased outflow resistance in the trabecular meshwork and Schlemms canal (SC), is a primary risk factor for glaucoma. This resistance is regulated by broadly active endothelial signaling systems such as ANGPT1-TIE2 and by dynamic flow-responsive pathways that remain poorly understood. Here, we identify a previously unrecognized, TIE2-independent, mechanosensitive ANGPT2-integrin 9{beta}1 pathway in the SC endothelium that regulates IOP. In vitro and in vivo, we show that activation of the mechanosensory channel PIEZO1 triggers ANGPT2 secretion and promotes cell-surface clustering of integrin 9{beta}1. Deletion of SC-expressed Piezo1 or Itga9 in mice resulted in SC narrowing, impaired flow-mediated SC endothelial proliferation, IOP elevation and glaucoma. Furthermore, ANGPT2 deficiency or blockade disrupted PIEZO1-induced integrin activation and reduced aqueous humor outflow facility. These findings establish autocrine PIEZO1-ANGPT2-ITGA9 signaling as a link between mechanosensory stimuli, SC structure and IOP regulation, offering promising new targets for glaucoma therapy.

cell biology↗