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Kazuhiro Yokoyama, Tsugiaki Utsunomiya, Akihiro Ishibazawa, Nobuhito Ishii, Kazuomi Hanada, Yasuo Yanagi, Akitoshi Yoshida; Shear stress affects expression of mucins in conjunctival epithelia. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6249. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Blinking generates dynamic movement of the tear fluid, and mechanically stimulate the ocular-surface epithelial cells via fluid shear stress. Mucins are secreted mainly from conjunctival cells, and lubricate the ocular-surface during the blink, help to maintain a smooth refractive surface, and provide a barrier against pathogen penetration. Shear stress reportedly affects the expression of mucins; however, the detailed mechanism has not been determined. We therefore aim to determine whether shear stress regulates the expression of mucins in conjunctival epithelia.
Using a parallel-plate type of flow chamber and peristaltic pump as described previously (Utsunomiya et al., IOVS, 2016), the confluent monolayer of human conjunctival epithelial cells was exposed to shear stress of 0, 1, and 5 dyne/cm2 for 24 hours. To assess expression of mucins after shear stress, cultures were stained for 5 minutes with 0.025% rose bengal and photographed with an inverted microscope. Rose bengal-negative areas, which represent the areas where the mucins expressed, were quantified using the ImageJ software.
The rose bengal-negative areas in cells exposed to static (0 dyne/cm2), and low shear stress (1 dyne/cm2), and high shear stress (5 dyne/cm2) were 24.75±11.06 %, and 55.00±13.44 %, and 62.25±14.20 % respectively. The rose bengal-negative areas in cells exposed to shear stress increased significantly compared to those in static (low shear stress, p=0.0227; high shear stress, p=0.0069, One-way ANOVA with Turkey’s post hoc test).
Shear stress positively affected the rose bengal-negative areas in cultured human conjunctival epithelial cells. These findings suggest that shear stress upregulates the expression of mucins in conjunctival epithelia, thereby protecting the ocular surface from shear stress.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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