Purpose. Glaucoma is a leading cause worldwide of blindness and visual impairment. Transforming growth factor-beta2 (TGFbeta2) has been implicated in the pathogenesis of primary open-angle glaucoma (POAG) based on elevated levels in glaucomatous aqueous humor and its ability to induce extracellular matrix (ECM) remodeling in the trabecular meshwork (TM). The goal of this study was to generate a rodent model of POAG using viral gene transfer of human TGFbeta2. Methods. Latent (hTGFbeta2(WT)) or active (C226S, C228S; hTGFbeta2(226/228)) TGFbeta2-encoding cDNA was cloned into the pac.Ad5.CMV.K-N.pA shuttle vector for generation of replication-deficient adenovirus. Empty adenovirus (Ad5.CMV.K-N.pA) was used as a control. Adenoviral expression of active and total TGFbeta2 was assayed in vitro by the transduction of Chinese hamster ovary and trabecular meshwork cells. BALB/cJ mice or Wistar rats were injected either intracamerally or intravitreally with the adenovectors and assessed for changes in intraocular pressure (IOP) using the rebound tonometer. At peak IOP, aqueous outflow facility and total TGFbeta2 levels in aqueous humor were measured. Mouse eye morphology was assessed by hematoxylin and eosin staining. Results. Adenoviral gene transfer of hTGFbeta2(226/228), but not hTGFbeta2(WT), to the rodent eye elevated IOP in rat (43%, P < 0.001) and mouse (110%, P < 0.001) and reduced aqueous humor outflow facility in the mouse. The TGFbeta2-induced ocular hypertension correlated with anterior segment TGFbeta2 expression levels (P < 0.0001). Conclusions. The adenoviral TGFbeta2 rodent model displays the glaucoma risk factors of elevated IOP and decreased aqueous outflow facility and may potentially serve as a model for studying glaucoma.

Elevated intraocular pressure (IOP) is the principal risk factor for glaucoma and results from excessive impedance of the fluid outflow from the eye. This abnormality likely originates from outflow pathway tissues such as the trabecular meshwork (TM), but the associated molecular etiology is poorly understood. We discovered what we believe to be a novel role for secreted frizzled-related protein-1 (sFRP-1), an antagonist of Wnt signaling, in regulating IOP. sFRP1 was overexpressed in human glaucomatous TM cells. Genes involved in the Wnt signaling pathway were expressed in cultured TM cells and human TM tissues. Addition of recombinant sFRP-1 to ex vivo perfusion-cultured human eyes decreased outflow facility, concomitant with reduced levels of β-catenin, the Wnt signaling mediator, in the TM. Intravitreal injection of an adenoviral vector encoding sFRP1 in mice produced a titer-dependent increase in IOP. Five days after vector injection, IOP increased 2 fold, which was significantly reduced by topical ocular administration of an inhibitor of a downstream suppressor of Wnt signaling. Thus, these data indicate that increased expression of sFRP1 in the TM appears to be responsible for elevated IOP in glaucoma and restoring Wnt signaling in the TM may be a novel disease intervention strategy for treating glaucoma.

The rebound tonometer was easy to use and accurately measured IOP in rats and mice. This technique, together with advances in genetic and other biological studies in rodents, will be valuable in the further understanding of the etiology and pathology of glaucoma.

In this study, a unique technique was developed to concurrently assess IOP, C, Pe, Fin, and Fu in the mouse eye. This experimental approach should be useful to evaluate effects of pharmacologic agents or genetic manipulations on aqueous humor dynamics in mice and other animal models.

Glaucoma is a leading cause of worldwide irreversible visual impairment and blindness and is a clinically and genetically heterogenous group of optic neuropathies. Specific mutations in the myocilin (MYOC) gene cause primary open angle glaucoma (POAG) with varying age-of-onset and degree of severity. We show a mutation-dependent, gain-of-function association between human myocilin and the peroxisomal targeting signal type 1 receptor (PTS1R). There was correlation between the glaucoma phenotype and the specific MYOC mutations, with the more severe early-onset POAG mutations having a higher degree of association with PTS1R. Expression of human myocilin glaucomatous mutations in mouse eyes causes elevated intraocular pressure, which is a major phenotype of MYOC glaucoma. This is the first demonstration of a disease resulting from mutation-induced exposure of a cryptic signaling site that causes mislocalization of mutant protein to peroxisomes and the first disease-gene-based animal model of human POAG.

There is a canonical Wnt signaling pathway in the TM, and this canonical Wnt pathway, but not the noncanonical Wnt signaling pathway, regulates IOP.

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In mouse, Fu and Fin diminish with age. C tends to increase as animals progress to middle life. There are strain differences in Fu, IOP, C, Fin, and Pe. The current findings provide an important foundation for comparisons among different strains in different study reports.