Effects of Ocular Hypertension on Cytoskeleton and Stiffness of Trabecular Meshwork Cells in Rats

Abstract

Elevated intraocular pressure (IOP) has been considered to be the major risk factor for glaucoma. The trabecular meshwork (TM), serving as the primary outflow pathway of aqueous humor (AH), has an essential role in controlling IOP. However, the mechanism of the interaction between ocular hypertension (OHT) and TM has not been completely understood. This research intended to investigate the effect of OHT on cell stiffness, cytoskeletal structure, and vimentin expression of TM cells in rats. Polystyrene microspheres were injected into the left eye of Sprague–Dawley (SD) rats to establish the OHT animal models. TM cells were extracted from the rat eyes with 2-week duration of OHT using the trypsin digestion method. The effect of OHT on the cytoskeletal structure and expression level of vimentin in TM cells were evaluated by immunofluorescence and western blot analyses, respectively. An atomic force microscope (AFM) was used to measure the cell elastic modulus. On the eighth day after microsphere injection, the IOP of experimental eyes increased to 24.25 ± 2.21 mmHg, and the IOP was maintained above 24 mmHg until the end of the experiment. TM cells extracted from the OHT group showed cytoskeleton rearrangement and the formation of cross-linked actin networks (CLANs). Compared to the control group, the cell stiffness in the OHT group was significantly increased. Moreover, the expression level of vimentin was obviously decreased in TM cells of the OHT group. The results demonstrate that OHT induces the rearrangement of the cytoskeleton, increase of cell stiffness, and downregulation of vimentin expression in TM cells.