Impact of Tunisian Fermented Zgougou and Related Lactobacilli on Caco-2 Cell Barrier Integrity: Upregulation of Key Tight Junction Proteins

The intestinal barrier is a complex and dynamic structure that plays a critical role in maintaining gut health. Though, pathological conditions such as, dysbiosis or inflammation that could damage the intestinal barrier to varying degrees, aggravating the primary disease. Recently, fermented plant-origin foods and probiotics were used as an alternative for health remedy. For this reason, in this current study, we made the inquiries about the effect of Tunisian zgougou juice obtained upon both spontaneous (J) and driven fermentation (J(A1+A2)) with autochthonous probiotic bacteria Lactiplantibacillus plantarum (LP) species A1 and A2, the whole bacteria (A1) and (A2) and their CFS. The cell integrity and permeability was assessed based on the TEER measurement on monolayer cell culture of Caco-2 cell, then the gene expression levels of the tight junction proteins (TJP) and the gene expression level of the inflammatory cytokine TNFα were evaluated using the RT-PCR. Our experimental findings exhibited that the driven fermented had a potential protective effects on intestinal barrier function in vitro shown by the great increase the electrical barrier detection (TEER) between Caco2 cell reaching ca. 690 to 963.33 Ω/cm2, although the regulatory mechanism has not been reported yet. Otherwise LP (A1 and A2) and their CFS showed moderate results. Furthermore, J(A1+A2) promoted the mRNA relative gene expression of the different tested tight TJPs and moderated the intestinal inflammation by influencing the TNFα expression. This study revealed that probiotics and especially probiotic-based plant-origin fermented functional foods (Tunisian zgougou juice) could improve and reinforce the intestinal barrier which provide new ideas for treating intestinal injury-related diseases, and have to be a revival in worldwide popularity, mostly as a consequence of claims made about their health benefits. So that, to completely reveal the health advantages of these probiotic LAB strains for humans and this new food matrix, additional in vivo and clinical investigations are necessary, as highlighted by the limitations of in vitro models.