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RationaleGrowing evidence supports a role for the microbiota in regulating gut-brain interactions and, thus, psychiatric disorders. Despite substantial scientific efforts to delineate the mechanism of action of psychotropic medications at a central nervous system (CNS) level, there remains a critical lack of understanding on how these drugs might affect the microbiota and gut physiology.ObjectivesWe investigated the antimicrobial activity of psychotropics against two bacterial strain residents in the human gut, Lactobacillus rhamnosus and Escherichia coli. In addition, we examined the impact of chronic treatment with these drugs on microbiota and intestinal parameters in the rat.ResultsIn vitro fluoxetine and escitalopram showed differential antimicrobial effects. Lithium, valproate and aripiprazole administration significantly increased microbial species richness and diversity, while the other treatments were not significantly different from controls. At the genus level, several species belonging to Clostridium, Peptoclostridium, Intestinibacter and Christenellaceae were increased following treatment with lithium, valproate and aripiprazole when compared to the control group. Animals treated with escitalopram, venlafaxine, fluoxetine and aripiprazole exhibited an increased permeability in the ileum.ConclusionsThese data show that psychotropic medications differentially influence the composition of gut microbiota in vivo and that fluoxetine and escitalopram have specific antimicrobial activity in vitro. Interestingly, drugs that significantly altered gut microbial composition did not increase intestinal permeability, suggesting that the two factors are not causally linked. Overall, unravelling the impact of psychotropics on gastrointestinal and microbiota measures offers the potential to provide critical insight into the mechanism of action and side effects of these medications.

We evaluated the inhibitory effects of the probiotic Lactobacillus species on different phases of Candida albicans biofilm development. Quantification of biofilm growth and ultrastructural analyses were performed on C. albicans biofilms treated with Lactobacillus rhamnosus , Lactobacillus casei , and Lactobacillus acidophilus planktonic cell suspensions as well as their supernatants. Planktonic lactobacilli induced a significant reduction ( p  < 0.05) in the number of biofilm cells (25.5–61.8 %) depending on the probiotic strain and the biofilm phase. L. rhamnosus supernatants had no significant effect on the mature biofilm ( p  > 0.05), but significantly reduced the early stages of Candida biofilm formation ( p  < 0.01). Microscopic analyses revealed that L. rhamnosus suspensions reduced Candida hyphal differentiation, leading to a predominance of budding growth. All lactobacilli negatively impacted C. albicans yeast-to-hyphae differentiation and biofilm formation. The inhibitory effects of the probiotic Lactobacillus on C. albicans entailed both cell-cell interactions and secretion of exometabolites that may impact on pathogenic attributes associated with C. albicans colonization on host surfaces and yeast filamentation. This study clarifies, for the first time, the mechanics of how Lactobacillus species may antagonize C. albicans host colonization. Our data elucidate the inhibitory mechanisms that define the probiotic candicidal activity of lactobacilli, thus supporting their utility as an adjunctive therapeutic mode against mucosal candidal infections.

Dietary lipids favor the growth of the pathobiont Bilophila wadsworthia, but the relevance of this expansion in metabolic syndrome pathogenesis is poorly understood. Here, we showed that B. wadsworthia synergizes with high fat diet (HFD) to promote higher inflammation, intestinal barrier dysfunction and bile acid dysmetabolism, leading to higher glucose dysmetabolism and hepatic steatosis. Host-microbiota transcriptomics analysis reveal pathways, particularly butanoate metabolism, which may underlie the metabolic effects mediated by B. wadsworthia. Pharmacological suppression of B. wadsworthia-associated inflammation demonstrate the bacterium's intrinsic capacity to induce a negative impact on glycemic control and hepatic function. Administration of the probiotic Lactobacillus rhamnosus CNCM I-3690 limits B. wadsworthia-induced immune and metabolic impairment by limiting its expansion, reducing inflammation and reinforcing intestinal barrier. Our results suggest a new avenue for interventions against western diet-driven inflammatory and metabolic diseases.

Lactobacilli have been shown to promote health functions. In this study, we analyzed the mechanism by which four different strains of probiotics affected innate immunity, such as regulation of ROS, cytokines, phagocytosis, bactericidal activity, signaling by NF-κB pp65, and TLR2 activation. The production of ROS was dependent on the concentration and species of Lactobacillus. The results obtained from the tested strains (Lactobacillus rhamnosus GG, L. rhamnosus KLSD, L. helveticus IMAU70129, and L. casei IMAU60214) showed that strains induced early proinflammatory cytokines such as IL-8,TNF-α, IL-12p70, and IL-6. However, IL-1β expression was induced only by L. helveticus and L. casei strains (after 24 h stimulation). Phagocytosis and bactericidal activity of macrophages against various pathogens, such as S. aureus, S. typhimurium, and E. coli, were increased by pretreatment with Lactobacillus. The nuclear translocation NF-κB pp65 and TLR2-dependent signaling were also increased by treatment with the probiotics. Taken together, the experiments demonstrate that probiotic strains of Lactobacillus exert early immunostimulatory effects that may be directly linked to the initial inflammation of the response of human macrophages.

The gut barrier plays an important role in human health. When barrier function is impaired, altered permeability and barrier dysfunction can occur, leading to inflammatory bowel diseases, irritable bowel syndrome or obesity. Several bacteria, including pathogens and commensals, have been found to directly or indirectly modulate intestinal barrier function. The use of probiotic strains could be an important landmark in the management of gut dysfunction with a clear impact on the general population. Previously, we found that Lactobacillus rhamnosus CNCM I-3690 can protect intestinal barrier functions in mice inflammation model. Here, we investigated its mechanism of action. Our results show that CNCM I-3690 can (i) physically maintain modulated goblet cells and the mucus layer and (ii) counteract changes in local and systemic lymphocytes. Furthermore, mice colonic transcriptome analysis revealed that CNCM I-3690 enhances the expression of genes related to healthy gut permeability: motility and absorption, cell proliferation; and protective functions by inhibiting endogenous proteases. Finally, SpaFED pili are clearly important effectors since an L. rhamnosus ΔspaF mutant failed to provide the same benefits as the wild type strain. Taken together, our data suggest that CNCM I-3690 restores impaired intestinal barrier functions via anti-inflammatory and cytoprotective responses.

Increased antibiotic resistance has catalyzed the research on new antibacterial molecules and alternative strategies, such as the application of beneficial bacteria. Since lectin molecules have unique sugar-recognizing capacities, and pathogens are often decorated with sugars that affect their survival and infectivity, we explored whether lectins from the probiotic strain Lactobacillus rhamnosus GG have antipathogenic properties. The genome sequence of L. rhamnosus GG was screened for the presence of lectin-like proteins. Two genes, LGG_RS02780 and LGG_RS02750, encoding for polypeptides with an N-terminal conserved L-type lectin domain were detected and designated Llp1 (lectin-like protein 1) and Llp2. The capacity of Llp1 and Llp2 to inhibit biofilm formation of various pathogens was investigated. Sugar specificity was determined by Sepharose beads assays and glycan array screening. The isolated lectin domains of Llp1 and Llp2 possess pronounced inhibitory activity against biofilm formation by various pathogens, including clinical Salmonella species and uropathogenic E. coli, with Llp2 being more active than Llp1. In addition, sugar binding assays with Llp1 and Llp2 indicate specificity for complex glycans. Both proteins are also involved in the adhesion capacity of L. rhamnosus GG to gastrointestinal and vaginal epithelial cells. Lectins isolated from or expressed by beneficial lactobacilli could be considered promising bio-active ingredients for improved prophylaxis of urogenital and gastrointestinal infections.

The aim of this study was to analyze the cell envelope components and surface properties of two phenotypes of Lactobacillus rhamnosus isolated from the human gastrointestinal tract. The ability of the bacteria to adhere to human intestinal cells and to aggregate with other bacteria was determined. L. rhamnosus strains E/N and PEN differed with regard to the presence of exopolysaccharides (EPS) and specific surface proteins. Transmission electron microscopy showed differences in the structure of the outer cell surface of the strains tested. Bacterial surface properties were analyzed by Fourier transform infrared spectroscopy, fatty acid methyl esters and hydrophobicity assays. Aggregation capacity and adhesion of the tested strains to the human colon adenocarcinoma cell line HT29 was determined. The results indicated a high adhesion and aggregation ability of L. rhamnosus PEN, which possessed specific surface proteins, had a unique fatty acid content, and did not synthesize EPS. Adherence of L. rhamnosus was dependent on specific interactions and was promoted by surface proteins (42–114 kDa) and specific fatty acids. Polysaccharides likely hindered bacterial adhesion and aggregation by masking protein receptors. This study provides information on the cell envelope constituents of lactobacilli that influence bacterial aggregation and adhesion to intestinal cells. This knowledge will help to understand better their specific contribution in commensal–host interactions and adaptation to this ecological niche.

Enteric dysbiosis plays an essential role in the pathogenesis of alcoholic liver disease (ALD). Detailed characterization of the alterations in the gut microbiome is needed for understanding their pathogenic role in ALD and developing effective therapeutic approaches using probiotic supplementation. Mice were fed liquid Lieber-DeCarli diet without or with alcohol (5% v/v) for 6 weeks. A subset of mice were administered the probiotic Lactobacillus rhamnosus GG (LGG) from 6 to 8 weeks. Indicators of intestinal permeability, hepatic steatosis, inflammation and injury were evaluated. Metagenomic analysis of the gut microbiome was performed by analyzing the fecal DNA by amplification of the V3-V5 regions of the 16S rRNA gene and large-scale parallel pyrosequencing on the 454 FLX Titanium platform. Chronic ethanol feeding caused a decline in the abundance of both Bacteriodetes and Firmicutes phyla, with a proportional increase in the gram negative Proteobacteria and gram positive Actinobacteria phyla; the bacterial genera that showed the biggest expansion were the gram negative alkaline tolerant Alcaligenes and gram positive Corynebacterium. Commensurate with the qualitative and quantitative alterations in the microbiome, ethanol caused an increase in plasma endotoxin, fecal pH, hepatic inflammation and injury. Notably, the ethanol-induced pathogenic changes in the microbiome and the liver were prevented by LGG supplementation. Overall, significant alterations in the gut microbiome over time occur in response to chronic alcohol exposure and correspond to increases in intestinal barrier dysfunction and development of ALD. Moreover, the altered bacterial communities of the gut may serve as significant therapeutic target for the prevention/treatment of chronic alcohol intake induced intestinal barrier dysfunction and liver disease.

Probiotics have been proposed as alternatives to pharmacological products in several medical conditions including the modulation of obesity, which is frequently associated with poor semen quality. However, effects of probiotics on male fertility have been less investigated. This study assessed the effect of Lactobacillus rhamnosus PB01 (DSM-14870) on sperm kinematic parameters in Normal-weight (NW) and diet-induced obese (DIO) models. NW and DIO C57BL/6NTac mice were divided into two subgroups with or without a single daily dose (1x109CFU) of L. rhamnosus for four weeks. Sperm motility and kinematics together with blood lipid profiles and reproductive hormone levels were assessed using the sperm class analyzer system. Probiotic supplementation increased serum testosterone, LH and FSH levels in both NW and DIO groups resulting in significantly (P<0.05) higher velocity (VSL, VCL and VAP) and percentages of progressively motile sperm and significantly lower percentages of immotile sperm. Other kinematic parameters (Lin, STR, ALH and BCF) were also increased in both probiotic supplemented DIO and NW groups at the 10% level of significance. Probiotic supplemented DIO mice demonstrated significantly higher percentages of progressively motile sperm versus DIO controls. This study demonstrated the potential of L. rhamnosus PB01 as a regulatory agent with positive effects on weight loss and reproductive-hormones, significantly improving sperm motility and kinematic parameters in male DIO models.

Background The possibility of using microbes to maintain health, and to prevent or treat disease is a topic as old as microbiology. The research of novel probiotic strains is important in order to satisfy the increasing request of the market and to obtain functional products in which the probiotic cultures are more active and with better probiotic characteristics than those already present on the market. Aim of the study In this study, the probiotic potential of Lactobacillus strains isolated from Italian elderly human faeces was investigated. Methods The Lactobacillus strains were identified and examined for resistance to gastric acidity and bile toxicity, adhesion to HT-29 cells, antimicrobial activities, antibiotic susceptibility and plasmid profile. Survival of the strains through human intestine was examined in a 3 months human feeding trial. Results Two strains, Lactobacillus rhamnosus IMC 501 and Lactobacillus paracasei IMC 502, tolerated well low pH and bile acids. In antimicrobial activity assays, both strains showed inhibitory properties towards selected potential harmful microorganisms, particularly against Candida albicans. The two selected strains expressed high in vitro adherence to HT-29 cells increasing this characteristic when they are used in combination and they were resistant to vamcomycin, colistin sulphate, gentamicin, oxolinic acid and kanamycin. Moreover, the two strains could be recovered from stools of volunteers after the feeding trials. Conclusions Lactobacillus rhamnosus IMC 501 and L. paracasei IMC 502 present favourable strain-specific properties for their utilisation as probiotics in functional foods and the high adhesion ability of the L. rhamnosus IMC 501 and L. paracasei IMC 502 used in combination, confirmed by both in vitro and in vivo study, indicate that the two bacterial strains could be used as health-promoting bacteria.