Ochratoxin A cytotoxicity on Madin–Darby canine kidney cells in the presence of alpha‐tocopherol: Effects on cell viability and tight junctions
Increasing evidence has suggested that OTA is responsible of the perturbation of cell–cell interactions as well as cell–cell signalling (Gekle et al., 2000; González‐Mariscal, Nava, & Hernández, 2005; Mally, Decker, Bekteshi, & Dekant, 2006; Mc Laughlin, Padfield, Burt, & O'Neil, 2004; Schramek et al., 1997). Tight junctions represent the most apical components of the intercellular junctional complex, which also includes adherens junctions, desmosomes and gap junctions. Tight junctions are composed of multiple transmembrane, scaffolding and signalling proteins, between which occludin and Zo1 interact to connect with the actin cytoskeleton (Harhaj & Antonetti, 2004). In the kidney, tight junctions vary along the nephron. The level of complexity of the tight junction increases moving forward in the distal tubule. Madin–Darby canine kidney (MDCK) cells represent an estimable model of the distal tubule/collecting duct (Feldman, Mullin, & Ryan, 2005) and have been used for OTA toxicity studies (Gekle et al., 2000; Schramek et al., 1997).
Several strategies, including some nutrient supplementation, have been proposed to reduce OTA toxicity (Denli & Perez, 2010; Sorrenti et al., 2013). Among them, antioxidant molecules, such as vitamin E, vitamin A, lycopene and phenolic compounds, have been shown to demonstrate different beneficial effects in blocking OTA toxicity in vivo and in vitro and have gained a key role in promoting health (Sorrenti et al., 2013). The role of α‐tocopherol in counteracting OTA cytotoxicity has been demonstrated in several in vitro models (Baldi et al., 2004; Fusi et al., 2010). This compound could be able to reduce the damage induced by OTA at different cellular levels. In particular, the preferential localization of α‐tocopherol in the cell membranes enhances its functional role as a lipid antioxidant and membrane stabilizer (Wang & Quinn, 1999).
The aim of this study was to evaluate the effects of OTA on cell viability, apoptotic rate and occludin and Zo1 localization, and the role of α‐tocopherol in counteracting its effects in MDCK cells.