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Eveliina Korhonen, Niina Piippo, Maria Hytti, Kai Kaarniranta, Anu Kauppinen; NLRP3 inflammasome activation after ultraviolet B irradiation in human corneal epithelial cells. Invest. Ophthalmol. Vis. Sci. 2016;57(12):327.
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© ARVO (1962-2015); The Authors (2016-present)
Cornea is the most apical layer of the eye, which protects deeper ocular structures by absorbing the majority of solar ultraviolet B (UVB) light (290-320 nm). The aim of the present study was to investigate the ability of UVB irradiation to trigger the activation of Nod-like receptor protein 3 (NLRP3) inflammasomes in human corneal epithelial (HCE) cells in vitro.
HCE cells were primed by tumor necrosis factor α (TNF-α) before an exposure to UVB. NLRP3 and IL-1β were measured 24 h after the UVB irradiation using enzyme-linked immunosorbent assay (ELISA). Intracellular protein levels of NLRP3 were also determined by the Western blot method. In addition, activation of caspase-1 was detected by enzymatic assay from the cell lysates. Experiments were repeated at least three times. Data was analyzed by the Mann-Whitney U-test.
UVB exposure induced the release of NLRP3, which was visible as significantly increased extracellular (p<0.001) and decreased intracellular (p<0.01) levels of NLRP3. Moreover, caspase-1 activity was significantly increased when compared to cells without UVB exposure (p<0.0001). These results were consistent with concurrently elevated levels of secreted IL-1β (p<0.0001).
Our findings show that NLRP3 is activated after UVB irradiation in in vitro-cultured HCE cells. We have previously shown that UVB irradiation increases the secretion of IL-6 and IL-8 in HCE cells, and the present study provides a deeper understanding for UVB induced painful inflammatory conditions in cornea.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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