Caco-2 cells monolayer as an in-vitro model for probiotic strain translocation

Background: Caco-2 cells monolayer is one of in vitro models to evaluate the translocation capacity of Lactobacillus spp probiotic strains. The translocation is influenced by mucosa permeability of enterocytes as shown by increasing transepithelial resistance (TER) and formation of tight junction proteins. The pore size of the supported permeable membrane used in in vitro assay was one of the crucial factors in performing bacterial translocation assay. Almost no study has been conducted using Caco-2 cells monolayer grown on 8-μm pore size polycarbonate membrane for evaluating probiotics translocation. Therefore this study aimed to determine whether the Caco-2 cells monolayer model was suitable as an in vitro translocation model. Methods: Caco-2 cells monolayer was seeded onto 8-μm collagen-coated polycarbonate membrane insert Transwell®. Differentiation of Caco-2 cells was detected by measuring the TER, while the ZO-1 protein (the tight junction proteins) was detected by immunofluorescence. H₂ O₂ was used as a tight junction disruptive agent. Data were analyzed using SPSS version 23 software to compare the mean of TER measurement between untreated and H₂ O₂-treated Caco-2 cells monolayer. Results: The result showed that the TER of Caco-2 cells monolayer was gradually increasing until day 14, reaching more than 800 ohm.cm². Furthermore, the ZO-1 protein was successfully detected, indicated the tight junction formation. TER value of H₂ O₂-treated cells showed significantly lower than that of untreated cells (P<0.05), indicating a disturbance of cells monolayer integrity. Lactobacillus rhamnosus FBB81 was used for validating the translocation. There was no translocation observed; however, translocation was observed in H₂ O₂-treated cells. Conclusion: Altogether suggests that Caco-2 cells grown on 8 μm-pore size permeable filters could be considered as a suitable in vitro model for probiotics strains translocation.