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Coralia Catalina Luna, Jianming Qiu, Pedro Gonzalez; Over-expression of the senescence marker P16-INK4a in the anterior chamber induces experimental glaucoma in rats.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2013.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate whether the induction of senescence by overexpressing P16-INK4a in the cells of the outflow pathway modulate intraocular pressure (IOP) and could serve as a glaucoma model.
P16-INK4a adenovirus expression was confirmed in human trabecular meshwork (TM) cells by Western blot. Senescence markers as, reactive oxygen species (ROS), senescence associated beta galactosidase (SA-β- gal) and autofluorescence were measured in HTM cells by Facscan. Anesthetized Sprague-Dawley rats were injected in the anterior chamber with adenoviruses (pfu 1x10 8 to 1x109) expressing P16-INK4a or GFP and intraocular pressure (IOP) was measured at the baseline and three times a week after injection using a portable tonometer. Rats were euthanized 10 or 24 days after injections, the eyes enucleated and the optic nerves (ON) fixed and prepared for semithin sections; a semi-automated axon counting was performed. Globes were fixed and prepare for semithin and/or thin sections of the angle.<br />
HTM cells at passage three expressed little to none endogenous P16-INK4a and the adenovirus mediated expression was robust. P16-INK4a adenovirus increased the senescence markers, SA-β gal, ROS and autofluorescence by 66%, 33% and 22% respectively in cultured HTM cells. Eyes injected with P16-INK4a had an average IOP of 19.5 mmHg compared to 10.6 in control eyes, the increase in pressure was observed in most animals from day four and last approximately 20 days. Axon count of the optic nerves showed an average of 13.6% axon loss in the eyes injected with P16-INK4a compared to controls. Anterior chamber morphology at 10 days showed an increase in collagen in the conventional outflow region.
Adenoviral mediated expression of P16-INK4a in the anterior chamber of the rat eye provides a new experimental model of glaucoma characterized by consistent elevation of IOP, moderate optic nerve axon loss, and temporary increase of collagen fibers in the TM.<br />
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