Multi-Species Probiotic Strain Mixture Enhances Intestinal Barrier Function by Regulating Inflammation and Tight Junctions in Lipopolysaccharides Stimulated Caco-2 Cells

Streptococcus salivarius ameliorates the destructive effect on the epithelial barrier by inhibiting the growth of Prevotella melaninogenica via metabolic acid production

BACKGROUND

Oral lichen planus (OLP) is one of the most common oral mucosal diseases, exhibiting a higher prevalence in women than men, but its pathogenesis is still unclear. Current research suggests that microbial dysbiosis may play an important role in the pathogenesis of OLP. Our previous research has found that the increase of Prevotella melaninogenica and decrease of Streptococcus salivarius have been identified as a potential pathogenic factor in OLP. Consequently, the objective of this study is to examine whether S. salivarius can counteract the detrimental effects of P. melaninogenica on the integrity of the epithelial barrier function.

MATERIALS AND METHODS

Epithelial barrier disruption was induced by P. melaninogenica in human keratinocytes (HaCaT cells). HaCaT cells were pretreated with S. salivarius(MOI = 20) or cell-free supernatant for 3 h, followed by treatment with P. melaninogenica (MOI = 5) for 3 h. The epithelial barrier integrity of HaCaT cells was detected by FD4 permeability. The mRNA level of tight junction protein was detected by quantitative real-time polymerase chain reaction (PCR). Immunofluorescence and Western Blot were used to detect the protein expression of zonula occludin-1 (ZO-1). The serial dilution-spotting assay was applied to monitor the viability of P. melaninogenica at the end of 8 and 24 h incubation.

RESULTS

Challenge by P. melaninogenica decreased the levels of tight junction proteins, including occludin, ZO-1, and claudin in HaCaT cells. S. salivarius or its cell-free supernatant inhibited the down-regulation of ZO-1 mRNA and protein expression levels induced by P. melaninogenica and thus improved the epithelial barrier function. The inhibitory effect of the cell-free supernatant of S. salivarius on the growth of P. melaninogenica is associated with metabolic acid production rather than with bacteriocins and hydrogen peroxide.

CONCLUSIONS

These results suggest that live S. salivarius or its cell-free supernatant significantly ameliorated the disruption of epithelial tight junctions induced by P. melaninogenica, likely through the inhibition of P. melaninogenica growth mediated by metabolic acid production.

Short communication: a novel multispecies bacteria-based direct-fed microbial supports in vitro gut barrier integrity challenged with a pathogen or pro-inflammatory cytokines

We conducted two experiments to evaluate the effects of a novel bacterial-based direct-fed microbial (DFM) on intestinal barrier integrity using the in vitro transepithelial electrical resistance (TEER) assay. In experiment 1, human-derived Caco-2 cells received or not (CON) a DFM containing Ligilactobacillus (formerly Lactobacillus) animalis 506, Propionibacterium freudenreichii 507, Bacillus paralicheniformis 809, and B. subtilis 597 (BDP; BOVAMINE DEFEND® Plus) at a rate of 1 × 108 CFU/transwell. Concurrently with treatment application (CON or BDP), a pathogenic challenge of Clostridium perfringens type A was added alone (PAT) or with BDP (PAT + BDP) at a rate of 2.8 × 107 CFU/transwell in a 2 × 2 factorial arrangement. In experiment 2, Caco-2 cells were also assigned in a 2 × 2 factorial design to CON or BDP and then, 2 h post-treatment administration (CON and BDP), a mixture of tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) was added alone (CYT) or with BDP (CYT + BDP) at a 10:1 ratio, respectively. In both experiments, TEER was measured for 18 h. In experiment 1, a DFM × pathogen × hour interaction was observed for TEER (P < 0.0001). Adding the PAT alone initially tended to increase TEER vs. CON from 1.1 to 2.2 h (P ≤ 0.09), increased TEER at 3.2 h (P < 0.01), but reduced TEER from 5.4 to the end of the experimental period at 18.4 h (P ≤ 0.01). On the other hand, adding DFM, with or without the pathogenic challenge, yielded greater TEER vs. CON-CON and CON-PAT for most of the experimental period (P ≤ 0.04). A similar interaction was detected and reported in experiment 2 (P < 0.0001). The CYT challenge reduced mean TEER compared with all other treatments from 3.2 h to the remainder of the study (P ≤ 0.03). On the other hand, BDP-CYT was able to maintain the integrity of the epithelial cells when compared with CON-CON throughout the experimental period (P ≤ 0.03), the exception being at 3.2 h (P = 0.20). Moreover, BDP-CON increased (P ≤ 0.04) TEER when compared with CON-CON from 3.2 to 18.4 h, but also in comparison with BDP-CYT from 4.3 to 18.4 h post-DFM and challenge administration into the cells. In summary, C. perfringens type A and a pro-inflammatory cytokine cocktail compromised the integrity of intestinal epithelial cell monolayers in vitro, whereas adding a multispecies bacteria-based DFM counteracted these damaging effects.

Anti-Salmonella Defence and Intestinal Homeostatic Maintenance In Vitro of a Consortium Containing Limosilactobacillus fermentum 3872 and Ligilactobacillus salivarius 7247 Strains in Human, Porcine, and Chicken Enterocytes

Limosilactobacillus fermentum strain 3872 (LF3872) was originally isolated from the breast milk of a healthy woman during lactation and the breastfeeding of a child. Ligilactobacillus salivarius strain 7247 (LS7247) was isolated at the same time from the intestines and reproductive system of a healthy woman. The genomes of these strains contain genes responsible for the production of peptidoglycan-degrading enzymes and factors that increase the permeability of the outer membrane of Gram-negative pathogens. In this work, the anti-Salmonella and intestinal homeostatic features of the LF3872 and LS7247 consortium were studied. A multi-drug resistant (MDR) strain of Salmonella enteritidis (SE) was used in the experiments. The consortium effectively inhibited the adhesion of SE to intact and activated human, porcine, and chicken enterocytes and reduced invasion. The consortium had a bactericidal effect on SE in 6 h of co-culturing. A gene expression analysis of SE showed that the cell-free supernatant (CFS) of the consortium inhibited the expression of virulence genes critical for the colonization of human and animal enterocytes. The CFS stimulated the production of an intestinal homeostatic factor-intestinal alkaline phosphatase (IAP)-in Caco-2 and HT-29 enterocytes. The consortium decreased the production of pro-inflammatory cytokines IL-8, TNF-α, and IL-1β, and TLR4 mRNA expression in human and animal enterocytes. It stimulated the expression of TLR9 in human and porcine enterocytes and stimulated the expression of TLR21 in chicken enterocytes. The consortium also protected the intestinal barrier functions through the increase of transepithelial electrical resistance (TEER) and the inhibition of paracellular permeability in the monolayers of human and animal enterocytes. The results obtained suggest that a LF3872 and LS7247 consortium can be used as an innovative feed additive to reduce the spread of MDR SE among the population and farm animals.

Immune-Stimulating Potential of Lacticaseibacillus rhamnosus LM1019 in RAW 264.7 Cells and Immunosuppressed Mice Induced by Cyclophosphamide

Probiotics, including Lacticaseibacillus rhamnosus (L. rhamnosus), have gained recognition for their potential health benefits, such as enhancing immune function, maintaining gut health, and improving nutrient absorption. This study investigated the effectiveness of L. rhamnosus LM1019 (LM1019) in enhancing immune function. In RAW 264.7 cells, LM1019 demonstrated dose-dependent immune stimulation by increasing nitric oxide production, gene expression of proinflammatory cytokines, and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). These effects were mediated through the activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) translocation without inducing cytotoxicity. Furthermore, orally administered LM1019 was evaluated in immunosuppressed mice induced by cyclophosphamide (CTX). High-dose administration of LM1019 significantly increased the subpopulations of lymphocytes, specifically helper T cells (CD4+), as well as two subtypes of natural killer (NK) cells, namely, IFN-γ+ and granzyme B+ NK cells. Additionally, LM1019 at a high dose led to elevated levels of proinflammatory cytokines, including IFN-γ and IL-12, compared to CTX-treated mice. These findings highlight the potential of LM1019 in enhancing the immune system. The study contributes to the growing body of research on the beneficial effects of probiotics on immune function.

Natural flavones from edible and medicinal plants exhibit enormous potential to treat ulcerative colitis

Ulcerative colitis (UC) is a chronic aspecific gut inflammatory disorder that primarily involves the recta and colons. It mostly presents as a long course of repeated attacks. This disease, characterized by intermittent diarrhoea, fecal blood, stomachache, and tenesmus, severely decreases the living quality of sick persons. UC is difficult to heal, has a high recurrence rate, and is tightly related to the incidence of colon cancer. Although there are a number of drugs available for the suppression of colitis, the conventional therapy possesses certain limitations and severe adverse reactions. Thus, it is extremely required for safe and effective medicines for colitis, and naturally derived flavones exhibited huge prospects. This study focused on the advancement of naturally derived flavones from edible and pharmaceutical plants for treating colitis. The underlying mechanisms of natural-derived flavones in treating UC were closely linked to the regulation of enteric barrier function, immune-inflammatory responses, oxidative stress, gut microflora, and SCFAs production. The prominent effects and safety of natural-derived flavones make them promising candidate drugs for colitis treatment.

Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials

Background

Probiotics play a vital role in treating immune and inflammatory diseases by improving intestinal barrier function; however, a comprehensive evaluation is missing. The present study aimed to explore the impact of probiotics on the intestinal barrier and related immune function, inflammation, and microbiota composition. A systematic review and meta-analyses were conducted.

Methods

Four major databases (PubMed, Science Citation Index Expanded, CENTRAL, and Embase) were thoroughly searched. Weighted mean differences were calculated for continuous outcomes with corresponding 95% confidence intervals (CIs), heterogeneity among studies was evaluated utilizing I2 statistic (Chi-Square test), and data were pooled using random effects meta-analyses.

Results

Meta-analysis of data from a total of 26 RCTs (n = 1891) indicated that probiotics significantly improved gut barrier function measured by levels of TER (MD, 5.27, 95% CI, 3.82 to 6.72, P < 0.00001), serum zonulin (SMD, -1.58, 95% CI, -2.49 to -0.66, P = 0.0007), endotoxin (SMD, -3.20, 95% CI, -5.41 to -0.98, P = 0.005), and LPS (SMD, -0.47, 95% CI, -0.85 to -0.09, P = 0.02). Furthermore, probiotic groups demonstrated better efficacy over control groups in reducing inflammatory factors, including CRP, TNF-α, and IL-6. Probiotics can also modulate the gut microbiota structure by boosting the enrichment of Bifidobacterium and Lactobacillus.

Conclusion

The present work revealed that probiotics could improve intestinal barrier function, and alleviate inflammation and microbial dysbiosis. Further high-quality RCTs are warranted to achieve a more definitive conclusion.

Clinical trial registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=281822, identifier CRD42021281822.