<i>Lactiplantibacillus plantarum</i> (CECT7484 and CECT7485) and <i>Pedioccoccus acidilactici</i> (CECT7483) enhance actin cytoskeleton and CYP1A1 expression restoring epithelial permeability alterations induced by irritable bowel syndrome mediators

Irritable bowel syndrome (IBS) is a multifactorial condition with heterogeneous pathophysiology, including intestinal permeability alterations. The aim of the present study was to assess the ability of a probiotic blend (PB) consisting of two <i>Lactiplantibacillus plantarum</i> strains (CECT7484 and CECT7485) and one strain of <i>Pediococcus acidilactici</i> (CECT7483) to recover the permeability increase induced by mediators from IBS mucosal biopsies and to highlight the underlying molecular mechanisms. Twenty-one IBS patients diagnosed according to ROME IV criteria (11 IBS-D and 10 IBS-M) and 7 healthy controls were enrolled. Mucosal mediators spontaneously released by IBS and HC biopsies were collected and incubated with/without the PB (10⁴ and 10⁶ CFU/ml). Paracellular permeability was assessed by evaluating the amount of sulfonic-acid-conjugated to fluorescein passing through the Caco-2 monolayer. RNA was extracted from Caco-2 cells and used to perform qPCR analyses, to evaluate the expression of ZO-1 and β-actin, and RNAseq to evaluate the transcriptomic profile. Untargeted metabolomics was used to characterize metabolites produced by the PB. The PB significantly reduced paracellular permeability after 3 h of incubation. Both doses of the PB significantly recovered the increase in paracellular permeability induced by IBS mediators. qPCR analyses showed that both doses of the PB co-incubated with IBS mediators induced a significant increase in beta-actin expression compared to IBS mediators alone. Concerning IBS subtypes, the high dose of the PB recovered the increase of permeability induced by IBS-D mediators. Transcriptomic analyses, confirmed by qPCR, showed that the high dose of the PB significantly increased CYP1A1 compared to IBS mediators alone. The PB produced a high amount of indole-3-lactic acid. The PB recovers the permeability increase induced by IBS mediators inducing the up-regulation of β-actin. In addition, the PB up-regulates the expression of CYP1A1, known to be involved in the metabolism of xenobiotics, possibly through the production of the indole-3-lactic acid.