This finding was a little contradictory. It would be expected to see differences also in the TJ mRNA levels of the gliadin treated cells compared to controls. Therefore, ZO-1, Claudin-1 and Occludin expressions were evaluated
in function of the time, following 24 h of exposure. ZO-1 and Claudin-1 mRNA levels were significantly (P < 0.05) affected by exposure to gliadin compared to untreated control cells. In particular ZO-1 expression decreased by 25% (0.80 ± 0.04 vs. 0.60 ± 0.01) while Claudin-1 decreased by 80% (0.05 ± 0.02 vs. 0.01 ± 0.01). Occludin expression remained unchanged (0.04 ± 0.02 vs. 0.035 ± 0.02). These results suggest that gliadin may be involved in the regulation of the TJ expression in a time dependent fashion. The administration of viable L.GG in combination with gliadin continued to significantly (P < 0.05) increase the mRNA levels of Claudin-1 (2.27 ± 0.06 selleck compound vs. 0.037 ± 0.01) and Occludin (1.3 ± 0.02 vs. 0.12 ± 0.02) see more while
exerting a slight and not significant decrease on ZO-1 expression (0.79 ± 0.02 vs. 1.04 ± 0.04) compared to gliadin treated cells. Given that only viable L.GG was effective in modulating TJ expression, alone or in combination with gliadin, we investigated whether the presence of cellular polyamines could affect the action of viable L.GG on TJ protein expression. Therefore, a subsequent set of experiments was conducted also in 4-Hydroxytamoxifen in vitro absence of polyamines by treating Caco-2 cells with DFMO for 6 h. The addition of gliadin to cells did not significantly influence the expression of all the proteins. Interestingly, also the supplementation of viable L.GG to gliadin did not produce consequences on the mRNA levels of ZO-1, Claudin-1 and Occludin and this evidence suggests the
need of polyamines by this probiotic to exert Thiamine-diphosphate kinase its actions on TJ protein expression (Figure 4, panels A, B, and C). Figure 4 ZO-1, Claudin-1 and Occludin mRNA levels in Caco-2 monolayers after 6 h of exposure to gliadin (1 mg/ml) alone or in combination with viable L.GG (10 8 CFU/ml), in presence or absence of polyamines following administration of α-Difluoromethylornithine (DFMO). All data represent the results of three different experiments (mean ± SEM). A. ZO-1 mRNA levels; B. Claudin-1 mRNA levels; C. Occludin mRNA levels. Data were analyzed by Kruskal-Wallis analysis of variance and Dunn’s Multiple Comparison Test. (*) P < 0.05 compared to gliadin treated cells. Overall, Western Blot analysis confirmed the results obtained by qPCR at 6 h and 24 h. In particular, Figure 5 reports the results obtained at 6 h. The protein levels of ZO-1 and Occludin in Caco-2 cells decreased not significantly after treatment with gliadin alone compared to control cells. Claudin-1 was not affected in its levels. Besides, the co-administration of gliadin with viable L.GG, but not with L.GG-HK and L.GG-CM, led to a significant increase (P < 0.