Abstract
Purpose :
To analyze changes in protein expression after ocular surface cells are repeatedly exposed to a mechanical model in which a contact lens is swept over the cells under dynamic conditions that mimic the force and speed of the blink.
Methods :
A computer controlled mechanical device was developed to hold a dish containing 3D cultured human corneal epithelial cells across which an arm bearing a contact lens was swept back and forth at a speed and force mimicking the human blink. The entire device was housed in an incubator to maintain temperature and humidity. Cells were subjected to sweep cycles of 20, 30, 40 and 60 minutes at a speed of 100 mm/sec and 2g applied force, after which the cells were harvested, lysed and analyzed by protein kinase arrays. The response of the cells to their perturbed environment was compared to control cells, which had not been subjected to the sweep of the arm or which were subjected to the sweeping motion but without applied force (n=3). A custom developed Matlab program was used to analyze the arrays. Data for some kinases was confirmed and quantitated by ELISA (n=3).
Results :
The phosphorylation state of several protein kinases increased in response to the sweep cycles. Quantitation by ELISA showed that the relative increase in phosphorylation levels for cells exposed to sweep cycles with applied force compared to untreated control cells were 3.91+/-0.87; 19.80+/-14.66 and 1.16+/-0.13 for HSP27, JNK and CREB respectively. For cells exposed to sweep cycles but no applied force the relative increases were 2.08+/-0.34; 5.93+/-4.03 and 1.33+/-0.24.
Conclusions :
Exposure of human corneal epithelial cells to sweep cycles increased the phosphorylation of a variety of important cellular proteins including HSP27 and JNK. These effects were due to both shear stress (sweep but no force) and mechanical stress (sweep with force) of the cells. The data show that perturbation of a cell’s environment in the presence of a contact lens and conditions mimicking blinking leads to activation of signaling pathways expected to lead to a functional change in the cell. Such responses may contribute to discomfort and other unwanted sequelae of contact lens wear.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.