TGFβ2 alters segmental outflow and ECM ultrastructure in the trabecular meshwork

Abstract

TGFβ2 is a well-known contributor to extracellular matrix (ECM) changes in the trabecular meshwork (TM). TGFβ2 is increased in the aqueous humor (AH) of primary open angle glaucoma patients and the addition of TGFβ2 to primary human TM cells in culture induces pathogenic changes similar to what is seen in the TM of ocular hypertensive and glaucomatous eyes. Overexpression of a bioactivated form of TGFβ2 using adenovirus 5 (Ad5.TGFβ2) in the TM has previously been described as an inducible mouse model of ocular hypertension and has been utilized for multiple studies to help understand the pathogenies of TGFβ2-induced TM damage and elevated intraocular pressure (IOP). Ad5.TGFβ2 is known to elevate IOP, decrease outflow facility, and increase expression of ECM proteins in the TM. Here, we further analyze the effects of overexpression of TGFβ2 by Ad5 in the TM. We found Ad5.TGFβ2 increases expression of macrophage marker Iba1 and increases expression of ECM proteins fibronectin and collagen 1 compared to Ad5.Null injected controls. In addition, overexpression of TGFβ2 by Ad5 led to a decrease in segmental AH flow regions compared to Ad5.Null control eyes. Ultrastructure analysis of the Ad5.TGFβ2 injected eyes also show significantly more areas occupied by ECM material as well as the development of more smaller giant vacuoles compared to Ad5.Null injected eyes. These data in combination with prior research using Ad5.TGFβ2, establish the use of intraocular injection of Ad5.TGFβ2 as an appropriate mouse model of ocular hypertension to study aqueous humor outflow and its mechanisms.