In vitro evaluation of the intestinal cell adhesion, immunomodulatory effect, and cholesterol assimilation of the potential probiotic and postbiotic isolated from healthy Thai children

Several bacterial genera, including Lactobacillus, have been evaluated for their beneficial effects in humans. This study aimed to evaluate the “probiotic” and “postbiotic” potential of three bacterial strains: Lactobacillus oris RCEID28-3, Limosilactobacillus fermentum RCEID23-2, and Limosilactobacillus fermentum RCEID47-7. Probiotics are defined as live bacterial cells, whereas postbiotics are inactivated or killed probiotics. Probiotic potential was evaluated by assessing the adhesion ability of the Caco-2 and HT-29 cell lines, immunomodulatory effects, and cholesterol assimilation. Meanwhile, postbiotic potential was assessed by evaluating their immunomodulatory effects through measuring cytokine production in human peripheral blood mononuclear cells (PBMCs) using an enzyme-linked immunosorbent assay (ELISA). The human intestinal cell adhesion assay showed that all bacterial strains exhibited adhesion of more than 90% to both the Caco-2 and HT-29 cell lines, except for L. oris RCEID28-3. The highest cell adhesion level was observed in L. fermentum RCEID47-7. The cytokine production assay revealed that probiotic and postbiotic strains stimulated the production of three cytokines: IL-10, IFN- γ, and TNF-α, in PBMCs with the different cytokines, indicating the strain-dependent property. Moreover, cholesterol assimilation by live probiotics showed that all the strains, especially L. fermentum RCEID47-7, could reduce cholesterol levels. Therefore, this study provides scientific evidence to support the possibility of applying probiotics and their inactivated forms (postbiotics) in humans in the near future.