The urothelium and the layer of glycosaminoglycans (GAG) and proteoglycans form a low-permeability urothelial barrier that prevents substances in the urine from passing into the surrounding tissues. Interstitial cystitis/bladder pain syndrome (IC/BPS) is a heterogeneous chronic inflammatory condition of unknown origin in which the integrity of the urothelial barrier is compromised and its permeability is increased. Two distinct subtypes of IC/BPS have been identified based on differences in pathophysiology and histological features. Oxidative stress may be one of the key pathophysiological mechanisms of IC/BPS. Tight junction proteins, which prevent the passage of substances via the paracellular route, are expressed at lower levels in IC/BPS. IC/BPS is not a rare disease, but it can be debilitating and have a significant impact on quality of life. Current therapies have limited efficacy. Therefore, understanding the pathophysiological mechanisms is essential for the development of targeted drugs. We established an in vitro model of IC/BPS. We added the enzyme glucose oxidase (GO), which catalyzes the formation of H₂O₂, to SV-HUC-1 human urothelial cells, thereby exposing the cells to oxidative stress. We measured the transepithelial electrical resistance (TEER) of the cells and subsequently prepared samples with immunofluorescently labeled target proteins, the tight junction proteins occludin and ZO-1, and the adherens junction protein E-cadherin. The results were not entirely consistent with expectations. The measured TEER value for the GO group was higher than that of the control group, which was not treated with GO, at several time points. This may be due to the use of cells with higher passage numbers and the growth of cells in multiple layers. The fluorescence intensity of the tight junction protein ZO-1 was also higher in the GO treated group, but the protein was more dispersed at the cell-cell junctions than in the control group. The distribution of occludin and E-cadherin in the control group also formed thinner lines at the cell junctions than in the GO group, indicating a trend toward altered transport of tight junction and adherens junction proteins in the GO group. Further analyses of the effects of oxidative stress on human urothelial cells are needed to ensure greater reliability of the results.
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