Fig. 4. IL-15 release into apical and basolateral epithelial compartments. Apical treatment of HCT-8 monolayers was carried out with named metabolites or bacterial supernatants as controls. After 24 h, secreted IL-15 was quantified, and the data are shown as the mean of three biological replicates ±sd (error bars). Two-way ANOVA was performed for each molecule versus the control condition (cells without treatment). *P<0.05, **P<0.01, ***P<0.001 and ****P<0.0001 were considered statistically significant.