Tau-Marin Mucoadhesive Gel for Prevention and Treatment of Gum Diseases.

An innovative and stable probiotic-containing mucoadhesive gel (AL0020), integrated with botanical extracts, has been developed to rebalance the dysbiosis associated with periodontal diseases. Tau-Marin gel, prepared with anhydrous ingredients to prevent the replication of bacteria and ensure good stability over time, was tested against some pathogenic bacteria, belonging to the so-called "red complex", recognized as the most important pathogens in plaque specimens, adherent to the epithelial lining of periodontal pockets. This lipogel was tested in vitro, in a physiological solution (PS) and in a simulated saliva (SS), for up to 8 h, to monitor its ability to release probiotics over time. Probiotics were enumerated through two different techniques, Lacto-Counter Assay (LCA) and Colony Forming Unit (CFU). A detailed physico-chemical profile of AL0020 and its in vitro efficacy in protecting activity against pathogenic bacteria as well as soothing or irritative effect on gingival epithelium were reported. Moreover, a clinical-dermatological trial on 20 volunteers using the product once a day for 30 days was also performed, where the efficacy of the gel in the control of gum disorders was observed.

Probiotics-Containing Mucoadhesive Gel for Targeting the Dysbiosis Associated with Periodontal Diseases.

Objective: Periodontitis is a common disorder that leads to the loss of both tooth and personal well-being, contributing to worsen the risk for metabolic and cardiovascular diseases. Recently, probiotics, characterized by rapid oral dispersion, have been topically used. Here, we present data of a mucoadhesive gel containing probiotics, capable of ensuring a slow release of bacteria to prevent and treat periodontitis. Methods: An original mucoadhesive gel (AL0005) that is anhydrous and of food grade, loaded with the blend of lactobacilli and plants' dry extracts, has been assayed. Results: The release kinetics of the bacterial mixture in different experimental models in vitro, including simulated saliva or physiological solutions, showed a significant and stable release for 5-8 hours. In one in vivo study of a mouse model of periodontitis, a locally applied mucoadhesive gel enriched with probiotic strains improved significantly the tissue pathology when compared with vehicle-exposed mice. Conclusions: Together, the results suggest that this mucoadhesive gel can be useful in the normalization of the gum bacterial flora and improvement of the tissue pathology of gum disorders.

Co-administration of vitamin D3 and Lacticaseibacillus paracasei DG increase 25-hydroxyvitamin D serum levels in mice.

PURPOSE: Subclinical vitamin D (vitD) deficiency enhances the predisposition to a myriad of acute and chronic pathologies in many people worldwide. Due to the scarcity of vitD-rich foods, the consumption of supplements or fortified foods can be required to maintain healthy serum levels of 25-hydroxyvitamin D [25(OH)D], and the major circulating form of vitD that is commonly measured in serum to determine the vitD status. Since the vitD absorption seems to resemble that of lipids, improved emulsification in the gut could favor vitD permeation through the enterocyte membrane. Contextually, we hypothesized that a microorganism with cholecalciferol (vitD3)-solubilization properties may potentially result in enhanced serum vitD levels. METHODS AND RESULTS: Six probiotic strains were screened for their ability to create a stable suspension of vitD3 in water: Lacticaseibacillus paracasei DG, L. paracasei LPC-S01, L. paracasei Shirota, L. rhamnosus GG, Limosilactobacillus reuteri DSM 17938, and Lactobacillus acidophilus LA5. The DG strain displayed the strongest vitD3 solubilization ability and, consequently, were used in an in vivo trial where a commercial preparation of vitD3 in refined olive oil was administered by gavage to CD-1 mice with or without the concurrent administration of L. paracasei DG. ELISA measurements showed that the DG strain significantly increased the serum levels of 25(OH) D when administered once a day for 1 week in association with the vitD3 supplement. CONCLUSION: This preliminary pre-clinical study suggests that the combined administration of L. paracasei DG with an oil-based cholecalciferol supplement could contribute to the maintenance of the adequate 25(OH) D serum levels in people at risk of vitD deficiency.

Lacticaseibacillus paracasei DG enhances the lactoferrin anti-SARS-CoV-2 response in Caco-2 cells.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the ongoing global pandemic of coronavirus disease 2019 (COVID-19), which primarily manifests with respiratory distress and may also lead to symptoms associated with the gastrointestinal tract. Probiotics are living microorganisms that have been shown to confer immune benefits. In this study, we investigated the immunomodulatory effects and anti-SARS-CoV-2 activity of three different Lacticaseibacillus probiotic strains, either alone or in combination with lactoferrin, using the intestinal epithelial Caco-2 cell line. Our results revealed that the Lacticaseibacillus paracasei DG strain significantly induced the expression of genes involved in protective antiviral immunity and prevented the expression of proinflammatory genes triggered by SARS-CoV-2 infection. Moreover, L. paracasei DG significantly inhibited SARS-CoV-2 infection in vitro. L. paracasei DG also positively affected the antiviral immune activity of lactoferrin and significantly augmented its anti-SARS-CoV-2 activity in Caco-2 intestinal epithelial cells. Overall, our work shows that the probiotic strain L. paracasei DG is a promising candidate that exhibits prophylactic potential against SARS-CoV-2 infection.

Supranational Assessment of the Quality of Probiotics: Collaborative Initiative between Independent Accredited Testing Laboratories.

Recent acquisitions about the role of the microbiota in the functioning of the human body make it possible to envisage an increasing use of beneficial microbes, and more particularly of probiotics as well as their metabolites, as nutritional supplements. National and EU authorities are engaged in assuring the safety and quality of food supplements and in defining rules to assess and communicate their efficacy on human health. The quality of probiotics, intended as strains' identification, viability, and stability over time, is a crucial factor of credibility with consumers and health professionals. Analytical technologies for the quality control of probiotics must also be adapted to new preparations, such as those including new multistrains complex combinations. Accredited laboratories face this relevant challenge on a daily basis. Through its close collaboration with the laboratory commissioned to produce the specifications for its ESLP quality label (identification and quantitative analyses) together with its scientific committee, the ESLP has been focusing on this issue for 10 years. Recently, as part of the internationalization of the ESLP quality label, a new and unique initiative in Europe for the evaluation of the quality of probiotic preparations has been carried out. The collaboration between two accredited laboratories in Belgium and in Italy represented a concrete example of supranational collaboration in the assessment of the quality of probiotic preparations. Results show that both laboratories are in line as expected in terms of performance. Common approaches to the qualitative assessment of probiotic preparations, especially for complex and composite recipes, in terms of number of strains and included substances, should be encouraged and promoted all over the EU.

Antibacterial Activity of a Fractionated Pistacia lentiscus Oil Against Pharyngeal and Ear Pathogens, Alone or in Combination With Antibiotics.

Previous studies have clearly demonstrated that the addition of lentisk oil (LO) to streptococcal cultures makes it possible to differentiate Streptococcus spp. into three categories with Streptococcus mitis and Streptococcus intermedius sensitive, Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus mutans partially sensitive, and Streptococcus salivarius insensitive to the product. We have investigated here whether the winterization of LO, an easy and cheap procedure that removes some of the fatty substances contained within, resulted in a better antimicrobial effect on human pathogens affecting the pharyngeal mucosa and middle ear such as S. pyogenes, S. pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae, without affecting, or minimally affecting, S. salivarius strains, oral probiotics commonly used to reduce oral and middle ear infection recurrence, especially in children. Our results not only demonstrated a stronger antimicrobial action of winterized LO (WLO) on S. pyogenes, compared to what was seen with LO, but also demonstrated a strong antimicrobial action vs. S. pneumoniae and M. catarrhalis and a very limited effect on S. salivarius (strains K12 and M18). Moreover, WLO demonstrated a co-acting action when tested along with the antibiotics amoxicillin (A) and amoxicillin clavulanate (AC), effects clearly visible also on H. influenzae. Our results also showed that at least part of the antimicrobial effect observed was due to the presence of anacardic acids (AAs). Finally, WLO, when tested with human peripheral blood mononuclear cells (h-PBMCs), reduced the release of IL-6 and TNF-α and, in the case of cells stimulated by LPS, the release of IFN-γ. In conclusion, our study highlights an enhanced antimicrobial role for LO when winterized, suggests a co-acting effect of this when given with antibiotics, identifies AAs as possible active ingredients, and proposes a possible anti-inflammatory role for it.

The combined effect of fermentation of lactic acid bacteria and in vitro digestion on metabolomic and oligosaccharide profile of oat beverage.

Oat (Avena sativa L.) is widely appreciated for its beneficial properties for human health, which have led to the introduction of more food products on the market, including oat beverages. The fibre components found in the oat are recognized for their beneficial effects, despite other bioactive compounds with healthy properties being present. This work aimed to evaluate the metabolites profile of a commercial oat beverage, either fermented with lactic bacteria or not, following in vitro gastro-intestinal digestion. UHPLC-QTOF untargeted metabolomics allowed investigation of the bioaccessibility of health-related metabolites from the oat beverage at the intestinal level. The results identified flavonoids, phenolic acids (avenanthramides), amino acids and steroids as the major classes of compounds. In particular, after in vitro digestion, amino acids, peptides, and phenolic acids showed the highest increases. The co-fermentation of oat milk by Lactobacillus spp. and Bifidobacterium spp. strains decreased the levels of both lignans and phytic acid, while increased the levels of some polyphenols like avenanthramides. Furthermore, fermentation by microorganisms increased the bioaccessibility of specific amino acids, vitamins, and polyphenols (flavonoids and phenolic acids). Interestingly, despite lacking a significant part of beta-glucans, the HPAEC-PAD profiling of our oat beverage evidenced that the fermentation process did not alter the oligosaccharides profile, thus preserving its prebiotic potential. The phytochemical profile of oat milk was shown to have a functional potential. Nonetheless, the fermentation by bacterial strains changed the profile of metabolites during in vitro digestion, thus offering an interesting option in the future development of cereal-based beverages.

Protective Effects of Lactoferrin against SARS-CoV-2 Infection In Vitro.

SARS-CoV-2 is a newly emerging virus that currently lacks curative treatments. Lactoferrin (LF) is a naturally occurring non-toxic glycoprotein with broad-spectrum antiviral, immunomodulatory and anti-inflammatory effects. In this study, we assessed the potential of LF in the prevention of SARS-CoV-2 infection in vitro. Antiviral immune response gene expression was analyzed by qRT-PCR in uninfected Caco-2 intestinal epithelial cells treated with LF. An infection assay for SARS-CoV-2 was performed in Caco-2 cells treated or not with LF. SARS-CoV-2 titer was determined by qRT-PCR, plaque assay and immunostaining. Inflammatory and anti-inflammatory cytokine production was determined by qRT-PCR. LF significantly induced the expression of IFNA1, IFNB1, TLR3, TLR7, IRF3, IRF7 and MAVS genes. Furthermore, LF partially inhibited SARS-CoV-2 infection and replication in Caco-2 intestinal epithelial cells. Our in vitro data support LF as an immune modulator of the antiviral immune response with moderate effects against SARS-CoV-2 infection.

Gut Microbiota for Health: How Can Diet Maintain A Healthy Gut Microbiota?

The human intestinal tract is colonized by a resilient integrated ecosystem represented by a complex consortium of trillions of microbes [...].

The Biotherapeutic Potential of Lactobacillus reuteri Characterized Using a Target-Specific Selection Process.

A growing body of clinical and experimental data supports the view that the efficacy of probiotics is strain-specific and restricted to particular pathological conditions, which means that newly isolated probiotic strains need to be targeted to a specific disease. Following national and international guidelines, we used a conventional in vitro experimental approach to characterize a novel strain of Lactobacillus reuteri, LMG P-27481, for safety (sensitivity to antibiotics and genome analysis) and putative efficacy (resistance to gastro-intestinal transit, adhesiveness, induction of cytokines, and release of antimicrobial metabolites). In vitro assays, which were carried out to examine the probiotic's effect on diarrhea (lactose utilization, inhibition of pathogens such as bacteria and Rotavirus), showed that it was more efficacious with respect to well-known reference strains in antagonizing Clostridioides difficile (CD). Data confirming that the probiotic can effectively treat CD colitis was gained from in vivo trials involving mice conditioned with large spectrum antibiotics before they were subjected to CD challenge. Two out of the three antibiotic-treated groups received daily LMG P-27481 for different time durations in order to simulate a preventive approach (LMG P-27481 administered prior to CD challenge) or an antagonistic one (LMG P-27481 administered after CD challenge). Both approaches significantly reduced, with respect to the untreated controls, CD DNA concentrations in caecum and C. difficile toxin titers in the gut lumen. In addition, LMG P-27481 supplementation significantly mitigated body weight loss and the extent of inflammatory infiltrate and tissue damage. The study results, which need to be confirmed by in vivo clinical trials, have demonstrated that the L. reuteri LMG P-27481 strain is a promising probiotic candidate for the treatment of CD infection.

Genome Sequence Announcement of Lactobacillus vaginalis LMG S-26419, Isolated from a Healthy Woman.

The Lactobacillus vaginalis LMG S-26419 strain, also named CBA-L88 (BV2), was isolated at the AAT-Advanced Analytical Technologies laboratories from a vaginal swab obtained from a healthy woman. The total genome size is 1,806,242 bp with a G+C content of 40.6%.

Therapeutic Effect of Bifidobacterium Administration on Experimental Autoimmune Myasthenia Gravis in Lewis Rats.

Beneficial effects of probiotics on gut microbiota homeostasis and inflammatory immune responses suggested the investigation of their potential clinical efficacy in experimental models of autoimmune diseases. Indeed, administration of two bifidobacteria and lactobacilli probiotic strains prevented disease manifestations in the Lewis rat model of Myasthenia Gravis (EAMG). Here, we demonstrate the clinical efficacy of therapeutic administration of vital bifidobacteria (i.e., from EAMG onset). The mechanisms involved in immunomodulation were investigated with ex vivo and in vitro experiments. Improvement of EAMG symptoms was associated to decreased anti-rat AChR antibody levels, and differential expression of TGFß and FoxP3 immunoregulatory transcripts in draining lymph nodes and spleen of treated-EAMG rats. Exposure of rat bone marrow-derived dendritic cells to bifidobacteria or lactobacilli strains upregulated toll-like receptor 2 mRNA expression, a key molecule involved in bacterium recognition via lipotheicoic acid. Live imaging experiments of AChR-specific effector T cells, co-cultured with BMDCs pre-exposed to bifidobacteria, demonstrated increased percentages of motile effector T cells, suggesting a hindered formation of TCR-peptide-MHC complex. Composition of gut microbiota was studied by 16S rRNA gene sequencing, and α and ß diversity were determined in probiotic treated EAMG rats, with altered ratios between Tenericutes and Verrucomicrobia (phylum level), and Ruminococcaceae and Lachnospiraceae (family level). Moreover, the relative abundance of Akkermansia genus was found increased compared to healthy and probiotic treated EAMG rats. In conclusion, our findings confirms that the administration of vital bifidobacteria at EAMG onset has beneficial effects on disease progression; this study further supports preclinical research in human MG to evaluate probiotic efficacy as supplementary therapy in MG.

Isolation and Characterization of New Probiotic Strains From Chinese Babies.

GOALS: The aims of this study were to isolate, to identify, and to characterize new potential probiotic strains from the feces of Chinese neonates. BACKGROUND: Probiotic strains approved in China for use in infants were declared to originate from the human gut of Western subjects. Diet is listed among the main factors affecting the composition of the human gut along with other factors such as genetics, lifestyle, and health status. On the basis of this, the lifestyle of mothers, including dietary habits, could have an impact on the bacterial strains that colonize the gut of their babies. STUDY: Starting from fecal samples, plated onto selective media, of 26 babies, a total of 38 Lactobacillus and 45 Bifidobacterium colonies were isolated and subcultured, identified at the specie level with the partial sequencing of the 16S ribosomal RNA gene, and assessed for safety according to international guidelines for probiotics and European guidance. Only 6 Lactobacillus and 5 Bifidobacterium spp. were included for further analysis for the evaluation of survival rate within the gastrointestinal tract and for adhesive properties on the Caco-2 cell line. Some tests for prebiotic metabolism and growth on reconstituted skimmed milk were also performed. RESULTS: Three Lactobacillus strains and 1 Bifidobacterium strain showing interesting adhesive abilities were included in the in vitro immune-stimulatory test with dendritic cells. Among these isolates, the Bifidobacterium breve 2TA showed the most interesting probiotic properties. CONCLUSIONS: The results obtained led to the identification of 4 new potential probiotic strains from Chinese babies to be submitted to further investigations about their metabolic and functional features.

Administration of bifidobacterium and lactobacillus strains modulates experimental myasthenia gravis and experimental encephalomyelitis in Lewis rats.

Probiotics beneficial effects on the host are associated with regulation of the intestinal microbial homeostasis and with modulation of inflammatory immune responses in the gut and in periphery. In this study, we investigated the clinical efficacy of two lactobacillus and two bifidobacterium probiotic strains in experimental autoimmune myasthenia gravis (EAMG) and experimental autoimmune encephalomyelitis (EAE) models, induced in Lewis rats. Treatment with probiotics led to less severe disease manifestation in both models; ex vivo analyses showed preservation of neuromuscular junction in EAMG and myelin content in EAE spinal cord. Immunoregulatory transcripts were found differentially expressed in gut associated lymphoid tissue and in peripheral immunocompetent organs. Feeding EAMG animals with probiotics resulted in increased levels of Transforming Growth Factor-ß (TGFß) in serum, and increased percentages of regulatory T cells (Treg) in peripheral blood leukocyte. Exposure of immature dendritic cells to probiotics induced their maturation toward an immunomodulatory phenotype, and secretion of TGFß. Our data showed that bifidobacteria and lactobacilli treatment effectively modulates disease symptoms in EAMG and EAE models, and support further investigations to evaluate their use in autoimmune diseases.

Gut microbiota and probiotics: novel immune system modulators in myasthenia gravis?

Gut microorganisms (microbiota) live in symbiosis with the host and influence human nutrition, metabolism, physiology, and immune development and function. The microbiota prevents pathogen infection to the host, and in turn the host provides a niche for survival. The alteration of gut bacteria composition (dysbiosis) could contribute to the development of immune-mediated diseases by influencing the immune system activation and driving the pro- and anti-inflammatory responses in order to promote or counteract immune reactions. Probiotics are nonpathogenic microorganisms able to interact with the gut microbiota and provide health benefits; their use has recently been exploited to dampen immunological response in several experimental models of autoimmune diseases. Here, we focus on the relationships among commensal bacteria, probiotics, and the gut, describing the main interactions occurring with the immune system and recent data supporting the clinical efficacy of probiotic administration in rheumatoid arthritis, multiple sclerosis, and myasthenia gravis (MG) animal models. The encouraging results suggest that selected strains of probiotics should be evaluated in clinical trials as adjuvant therapy to restore the disrupted tolerance in myasthenia gravis.

Short-term impact of a classical ketogenic diet on gut microbiota in GLUT1 Deficiency Syndrome: A 3-month prospective observational study.

BACKGROUND&AIMS: The classical ketogenic diet (KD) is a high-fat, very low-carbohydrate normocaloric diet used for drug-resistant epilepsy and Glucose Transporter 1 Deficiency Syndrome (GLUT1 DS). In animal models, high fat diet induces large alterations in microbiota producing deleterious effects on gut health. We carried out a pilot study on patients treated with KD comparing their microbiota composition before and after three months on the diet. METHODS: Six patients affected by GLUT1 DS were asked to collect fecal samples before and after three months on the diet. RT - PCR analysis was performed in order to quantify Firmicutes, Bacteroidetes, Bifidobacterium spp., Lactobacillus spp., Clostridium perfringens, Enterobacteriaceae, Clostridium cluster XIV, Desulfovibrio spp. and Faecalibacterium prausnitzii. RESULTS: Compared with baseline, there were no statistically significant differences at 3 months in Firmicutes and Bacteroidetes. However fecal microbial profiles revealed a statistically significant increase in Desulfovibrio spp. (p = 0.025), a bacterial group supposed to be involved in the exacerbation of the inflammatory condition of the gut mucosa associated to the consumption of fats of animal origin. CONCLUSIONS: A future prospective study on the changes in gut microbiota of all children with epilepsy started on a KD is warranted. In patients with dysbiosis demonstrated by fecal samples, it my be reasonable to consider an empiric trial of pre or probiotics to potentially restore the «ecological balance¼ of intestinal microbiota.

Assessment of the susceptibility of lactic acid bacteria to biocides.

Biocides are antimicrobial compounds that are widely used in the food industry and medical environments. In this study, we determined the Minimum Inhibitory Concentrations (MICs) by the microdilution method of four different biocides for a large collection of LAB of different origins. The tested isolates belong to 11 species of the Lactobacillus genus and to Streptococcus thermophilus, Streptococcus salivarius and Lactococcus garvieae. The results obtained in this study indicate that low susceptibilities to benzalkonium chloride (BC), triclosan (Tr), chlorhexidine (Ch), and sodium hypochlorite (SH) are not frequent among LAB. Moreover, no systematic co-tolerance between two or more tested biocides was found; that is, strains displaying high MIC values and thus low sensitivity to one of the biocides did not show higher MIC values for the other biocides.

Biocide susceptibility in bifidobacteria of human origin.

Disinfectants have been used in a variety of environmental applications, in products for personal care and in the food industry. The food industry has increased the use of biocides and chemical-based disinfectants to control microbial ecology at production sites in an effort to improve hygiene measures and food safety. However, the susceptibility profile of micro-organisms to disinfectants has been largely neglected. This study therefore aimed to provide this type of information by focusing on the four most commonly used biocides in the food industry, determining their minimum inhibitory concentrations (MICs) and analysing the distribution of MICs across a variety of micro-organisms. In total, 99 different strains of Bifidobacterium spp. were studied. Results showed a unimodal distribution of MICs for chlorhexidine, triclosan (Irgasan) and sodium hypochlorite with no apparent species-specific correlation. Conversely, part of the tested bifidobacteria population (20%) showed reduced susceptibility to benzalkonium chloride compared with the susceptibility exhibited by the majority of the tested bacterial community. The highest MICs were distributed among almost all of the considered Bifidobacterium spp. In generally, the sensitivity of the studied strains to the four tested biocides appeared to be a genus-related trait.

Evaluation of prebiotic potential of refined psyllium (Plantago ovata) fiber in healthy women.

GOAL: To assess the effects of the consumption of psyllium seed husk on fecal bifidobacteria in healthy women and the ability of fecal bifidobacteria to metabolize psyllium seed husk in vitro. BACKGROUND: Poor microbiologic evidences are nowadays available concerning the ability of psyllium seed husk to promote the growth of bifidobacteria in human gut. STUDY: Eleven healthy women consumed 7.0 g/d of psyllium seed husk for 1 month. Viability of bifidobacteria in feces was assessed at different time points. RESULTS: In vivo results showed that the average fecal content of viable bifidobacteria was not significantly affected even if fecal counts were found to increase significantly after treatment in 6 out of 11 women having low initial concentration. In vitro trials conducted on bifidobacteria strains isolated from treated women failed to confirm the prebiotic potential of undigested psyllium seed husk, whereas treatment with simulated gastric and pancreatic juices and mimicking physical and chemical alterations during human gut transit allowed fecal Bifidobacterium isolates to metabolize psyllium seed husk as carbon source in a growth medium deprived of sugar. CONCLUSIONS: Psyllium seed husk can be metabolized by bifidobacteria only after partial hydrolysis. Bifidogenic potential can be detected in healthy women only in case of low level of fecal bifidobacteria before treatment.

Lactobacillus crispatus M247-derived H2O2 acts as a signal transducing molecule activating peroxisome proliferator activated receptor-gamma in the intestinal mucosa.

BACKGROUND & AIMS: Accumulating evidence indicates that the peroxisome proliferator activated receptor (PPAR)-gamma is a major player in maintaining intestinal mucosa homeostasis, but whether PPAR-gamma is directly involved in probiotic-mediated effects and the molecular events involved in its activation are not known. METHODS: We investigated the role of PPAR-gamma in the immunomodulatory effects of Lactobacillus crispatus M247 on intestinal epithelial cells (IEC) and the role of probiotic-derived H(2)O(2) on PPAR-gamma activity. RESULTS: L crispatus M247 supplementation in mice significantly increased PPAR-gamma levels and transcriptional activity in the colonic mucosa. L crispatus M247 induced PPAR-gamma nuclear translocation and enhanced transcriptional activity in epithelial (CMT-93) cells, as demonstrated by the increased luciferase activity of a PPAR-gamma-responsive element, PPAR-gamma-responsive gene up-regulation, and reduced activity of an nuclear factor-kappaB-responsive element. Pharmacologic PPAR-gamma inhibition or silencing by small interfering RNA cancelled the L crispatus M247-mediated effects in CMT-93 cells. Because Lactobacillus strains producing little H(2)O(2) failed to activate PPAR-gamma, we investigated the role of L crispatus M247-derived H(2)O(2) in PPAR-gamma activation. L crispatus M247 induced a transient rise in intracellular H(2)O(2) and PPAR-gamma transcriptional activity was cancelled by antioxidant or H(2)O(2) scavenger. Toll-like receptor (TLR)-2 was not required for PPAR-gamma up-regulation mediated by L crispatus M247 in mice, although the protective effects of L crispatus M247 on dextran sodium sulfate-induced colitis were less pronounced in TLR-2(-/-) mice. CONCLUSIONS: L crispatus M247 uses H(2)O(2) as a signal transducing molecule to induce PPAR-gamma activation in IEC, directly modulating epithelial cell responsiveness to inflammatory stimuli.