The Adhesion of Lactobacillus salivarius REN to a Human Intestinal Epithelial Cell Line Requires S-layer Proteins

Research progress on the regulatory mechanism of biofilm formation in probiotic lactic acid bacteria

Probiotic lactic acid bacteria (LAB) must undergo three key stages of testing, including food processing, storage, and gastrointestinal tract environment, their beneficial effects could exert. The biofilm formation of probiotic LAB is helpful for improving their stress resistances, survival rates, and colonization abilities under adverse environmental conditions, laying an important foundation for their probiotic effects. In this review, the formation process, the composition and function of basic components of probiotic LAB biofilm have been summarized. This review focuses on the regulatory mechanism of probiotic LAB biofilm formation. In addition, the characteristics and related mechanisms of probiotics in biofilm state have been analyzed to guide the application of probiotic LAB biofilms in the field of health and food. The biofilm formation of LAB is an extremely complex process involving multiple regulatory factors. Besides quorum sensing (QS), other regulatory factors are not yet fully understood. The probiotic LAB in biofilm state exhibit superior survival rate, adhesion performance, and immunomodulation ability, attribute to various metabolic processes, including stress response, exopolysaccharide (EPS) metabolism, amino acid and protein metabolisms, etc. The understanding about regulatory mechanism of biofilm formation of different probiotic species and strains will accelerate the development and application of probiotics products.

Weissella cibaria Relieves Gut Inflammation Caused by Escherichia coli through Inflammation Modulation and Gut Microbiota Regulation

The emergence of multi-drug-resistant (MDR) pathogens has considerably challenged the development of new drugs. Probiotics that inhibit MDR pathogens offer advantages over chemical antibiotics and drugs due to their increased safety and fewer side effects. This study reported that Weissella cibaria P-8 isolated from pickles showed excellent antibacterial activity against intestinal pathogens, particularly the antibacterial activity against MDR Escherichia coli B2 was the highest. This study showed that the survival rates of W. cibaria P-8 at pH 2.0 and 0.3% bile salt concentration were 72% and 71.56%, respectively, and it still had antibacterial activity under pepsin, trypsin, protease K, and catalase hydrolysis. Moreover, W. cibaria P-8 inhibits the expression of inflammatory factors interleukin-1β, tumor necrosis factor-α, and interleukin-6, upregulates the interleukin-10 level, and increases total antioxidant capacity and superoxide dismutase enzyme activity in serum. W. cibaria P-8 also efficiently repairs intestinal damage caused by E. coli infection. The gut microbiota analysis demonstrated that W. cibaria P-8 colonizes the intestine and increases the abundance of some beneficial intestinal microorganisms, particularly Prevotella. In conclusion, W. cibaria P-8 alleviated MDR E. coli-induced intestinal inflammation by regulating inflammatory cytokine and enzyme activity and rebalancing the gut microbiota, which could provide the foundation for subsequent clinical analyses and probiotic product development.

Exploration adhesion properties of Liquorilactobacillus and Lentilactobacillus isolated from two different sources of tepache kefir grains

Due to the distinctive characteristics of probiotics, it is essential to pinpoint strains originating from diverse sources that prove efficacious in addressing a range of pathologies linked to dysfunction of the intestinal barrier. Nine strains of lactic acid bacteria were isolated from two different sources of tepache kefir grains (KAS2, KAS3, KAS4, KAS7, KAL4, KBS2, KBS3, KBL1 and KBL3), and were categorized to the genus Lacticaseibacillus, Liquorilactobacillus, and Lentilactobacillus by 16S rRNA gene. Kinetic behaviors of these strains were evaluated in MRS medium, and their probiotic potential was performed: resistance to low pH, tolerance to pepsin, pancreatin, bile salts, antibiotic resistance, hemolytic activity, and adhesion ability. KAS7 strain presented a higher growth rate (0.50 h-1) compared with KAS2 strain, who presented a lower growth rate (0.29 h-1). KBS2 strain was the only strain that survived the in vitro stomach simulation conditions (29.3%). Strain KBL1 demonstrated significantly higher viability (90.6%) in the in vitro intestine simulation conditions. Strain KAS2 demonstrated strong hydrophilic character with chloroform (85.6%) and xylol (57.6%) and a higher percentage of mucin adhesion (87.1%). However, strains KBS2 (84.8%) and KBL3 (89.5%) showed the highest autoaggregation values. In terms of adhesion to the intestinal epithelium in rats, strains KAS2, KAS3 and KAS4 showed values above 80%. The growth of the strains KAS2, KAS3, KAS4, KBS2, and KBL3 was inhibited by cefuroxime, cefotaxime, tetracycline, ampicillin, erythromycin, and cephalothin. Strains KBS2 (41.9% and 33.5%) and KBL3 (42.5% and 32.8%) had the highest co-aggregation values with S. aureus and E. coli. The results obtained in this study indicate that lactic acid bacteria isolated from tepache can be considered as candidates for potentially probiotic bacteria, laying the foundations to evaluate their probiotic functionality in vivo and thus to be used in the formulation of functional foods.

Ligilactobacillus salivarius CNCM I-4866, a potential probiotic candidate, shows anti-inflammatory properties in vitro and in vivo

INTRODUCTION

The aim of this work was to characterize a new strain of Ligilactobacillus salivarius (CNCM I-4866) (CNCM I-4866) to address its potential as probiotic with a special focus on intestinal inflammation. Potential anti-inflammatory abilities of this strain were evaluated through in vivo and in vitro experiments.

METHODS

Firstly, the strain was tested in a murine acute inflammation colitis model induced by DNBS. In vitro characterization was then performed with diverse tests: modulation capability of intestinal permeability; study of the impact on immunity profile through cytokines dosage; capacity to inhibit pathogens and adhere to intestinal cells lines. Production of metabolites, antibiotic resistance and survival to gastro-intestinal tract conditions were also tested.

RESULTS

In vitro assay has shown a reduction of colonic damage and markers of inflammation after treatment with CNCM I-4866. Transcriptomic analysis performed on colons showed the capacity of the strain to down-regulate pro-inflammatory cytokines. L. salivarius CNCM I-4866 exerted anti-inflammatory profile by reducing IL-8 production by TNF-α stimulated cell and modulated cytokines profile on peripheral blood mononuclear cells (PBMC). It protected intestinal integrity by increasing trans-epithelial electrical resistance (TEER) on Caco-2 TNF-α inflamed cells. Additionally, L. salivarius CNCM I-4866 displayed inhibition capacity on several intestinal pathogens and adhered to eukaryotic cells. Regarding safety and technical concerns, CNCM I-4866 was highly resistant to 0.3% of bile salts and produced mainly L-lactate. Finally, strain genomic characterization allowed us to confirm safety aspect of our strain, with no antibiotic gene resistance found.

DISCUSSION

Taken together, these results indicate that L. salivarius CNCM I-4866 could be a good probiotic candidate for intestinal inflammation, especially with its steady anti-inflammatory profile.

Probiotic Properties of Chicken-Derived Highly Adherent Lactic Acid Bacteria and Inhibition of Enteropathogenic Bacteria in Caco-2 Cells

Lactic acid bacteria (LAB) as probiotic candidates have various beneficial functions, such as regulating gut microbiota, inhibiting intestinal pathogens, and improving gut immunity. The colonization of the intestine is a prerequisite for probiotic function. Therefore, it is necessary to screen the highly adherent LAB. In this study, the cell surface properties, such as hydrophobicity, auto-aggregation, co-aggregation, and adhesion abilities of the six chicken-derived LAB to Caco-2 cells were investigated. All six strains showed different hydrophobicity (21.18-95.27%), auto-aggregation (13.61-30.17%), co-aggregation with Escherichia coli ATCC 25922 (10.23-36.23%), and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311 (11.71-39.35%), and adhesion to Caco-2 cells (8.57-26.37%). Pediococcus pentosaceus 2-5 and Lactobacillus reuteri L-3 were identified as the strains with strong adhesion abilities (26.37% and 21.57%, respectively). Moreover, these strains could survive in a gastric acid environment at pH 2, 3, and 4 for 3 h and in a bile salt environment at 0.1%, 0.2%, and 0.3% (w/v) concentration for 6 h. Furthermore, the cell-free supernatant of P. pentosaceus 2-5 and L. reuteri L-3 inhibited the growth of enteropathogenic bacteria and the strains inhibited the adhesion of these pathogens to Caco-2 cells. In this study, these results suggested that P. pentosaceus 2-5 and L. reuteri L-3, isolated from chicken intestines might be good probiotic candidates to be used as feed additives or delivery vehicles of biologically active substances.

Identification and Characterization of Domains Responsible for Cell Wall Binding, Self-Assembly, and Adhesion of S-layer Protein from Lactobacillus acidophilus CICC 6074

Lactobacillus S-layer protein (SLP) is a biologically active protein on the cell surface. To further elucidate the structures and functions of SLP in Lactobacillus acidophilus CICC 6074, this study was conducted to identify the functional domains of SLP which is responsible for cell wall anchoring, self-assembly, and adhesion. The gene (slpA) of L. acidophilus CICC 6074 SLP was amplified by polymerase chain reaction and speculated functional domains. Fusion proteins of C-terminal truncations from SLP were exogenously expressed in Escherichia coli BL21 (DE3). FITC-labeling N-terminal truncations of SLP were synthesized. The C-terminal domain was more likely to be the binding region, and the cell wall-anchored receptor of SLP was teichoic acid. Furthermore, N-terminal truncations could self-assemble to milk fat globule membrane polar lipid liposomes observed using a fluorescence microscope. Notably, SAN1 (region 32-55) of N-terminal truncations was mainly responsible for the adhesion of SLP to HT-29 cells. These results showed that SLP played a crucial role in the functions of L. acidophilus CICC 6074, which might be of significant reference value for future studies.

Lactic Acid Bacteria Mixture Isolated From Wild Pig Alleviated the Gut Inflammation of Mice Challenged by Escherichia coli

Wild pigs usually showed high tolerance and resistance to several diseases in the wild environment, suggesting that the gut bacteria of wild pigs could be a good source for discovering potential probiotic strains. In our study, wild pig feces were sequenced and showed a higher relative abundance of the genus Lactobacillus (43.61% vs. 2.01%) than that in the domestic pig. A total of 11 lactic acid bacteria (LAB) strains including two L. rhamnosus, six L. mucosae, one L. fermentum, one L. delbrueckii, and one Enterococcus faecalis species were isolated. To investigate the synergistic effects of mixed probiotics strains, the mixture of 11 LAB strains from an intestinal ecology system was orally administrated in mice for 3 weeks, then the mice were challenged with Escherichia coli ATCC 25922 (2 × 10⁹ CFU) and euthanized after challenge. Mice administrated with LAB strains showed higher (p < 0.05) LAB counts in feces and ileum. Moreover, alterations of specific bacterial genera occurred, including the higher (p < 0.05) relative abundance of Butyricicoccus and Clostridium IV and the lower (p < 0.05) abundance of Enterorhabdus in mice fed with mixed LAB strains. Mice challenged with Escherichia coli showed vacuolization of the liver, lower GSH in serum, and lower villus to the crypt proportion and Claudin-3 level in the gut. In contrast, administration of mixed LAB strains attenuated inflammation of the liver and gut, especially the lowered IL-6 and IL-1β levels (p < 0.05) in the gut. Our study highlighted the importance of gut bacterial diversity and the immunomodulation effects of LAB strains mixture from wild pig in gut health.

Differential Effects of Transition Metals on Growth and Metal Uptake for Two Distinct Lactobacillus Species

Lactobacillus is a genus of Gram-positive bacteria and comprises a major part of the lactic acid bacteria group that converts sugars to lactic acid. Lactobacillus species found in the gut microbiota are considered beneficial to human health and commonly used in probiotic formulations, but their molecular functions remain poorly defined. Microbes require metal ions for growth and function and must acquire them from the surrounding environment. Therefore, lactobacilli need to compete with other gut microbes for these nutrients, although their metal requirements are not well-understood. Indeed, the abundance of lactobacilli in the microbiota is frequently affected by dietary intake of essential metals like zinc, manganese, and iron, but few studies have investigated the role of metals, especially zinc, in the physiology and metabolism of Lactobacillus species. Here, we investigated metal uptake by quantifying total cellular metal contents and compared how transition metals affect the growth of two distinct Lactobacillus species, Lactobacillus plantarum ATCC 14917 and Lactobacillus acidophilus ATCC 4356. When grown in rich or metal-limited medium, both species took up more manganese, zinc, and iron compared with other transition metals measured. Distinct zinc-, manganese- and iron-dependent patterns were observed in the growth kinetics for these species and while certain levels of each metal promoted the growth kinetics of both Lactobacillus species, the effects depend significantly on the culture medium and growth conditions. IMPORTANCE The gastrointestinal tract contains trillions of microorganisms, which are central to human health. Lactobacilli are considered beneficial microbiota members and are often used in probiotics, but their molecular functions, and especially those which are metal-dependent, remain poorly defined. Abundance of lactobacilli in the microbiota is frequently affected by dietary intake of essential metals like manganese, zinc, and iron, but results are complex, sometimes contradictory, and poorly predictable. There is a significant need to understand how host diet and metabolism will affect the microbiota, given that changes in microbiota composition are linked with disease and infection. The significance of our research is in gaining insight to how metals distinctly affect individual Lactobacillus species, which could lead to novel therapeutics and improved medical treatment. Growth kinetics and quantification of metal contents highlights how distinct species can respond differently to varied metal availability and provide a foundation for future molecular and mechanistic studies.

The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies

Numerous studies point to the important role of probiotic bacteria in gastrointestinal health. Probiotics act through mechanisms affecting enteric pathogens, epithelial barrier function, immune signaling, and conditioning of indigenous microbiota. Once administered, probiotics reach the gastrointestinal tract and interact with the host through bacterial surface molecules, here called adhesion factors, which are either strain- or specie-specific. Probiotic adhesion, through structural adhesion factors, is a mechanism that facilitates persistence within the gastrointestinal tract and triggers the initial host responses. Thus, an understanding of specific probiotic adhesion mechanisms could predict how specific probiotic strains elicit benefits and the potential of adherence factors as a proxy to predict probiotic function. This review summarizes the present understanding of probiotic adherence in the gastrointestinal tract. It highlights the bacterial adhesion structure types, their molecular communication with the host and the consequent impact on intestinal diseases in both adult and pediatric populations. Finally, we discuss knockout/isolation studies as direct evidence for adhesion factors conferring anti-inflammatory and pathogen inhibition properties to a probiotic.What is known: Probiotics can be used to treat clinical conditions.Probiotics improve dysbiosis and symptoms.Clinical trials may not confirm in vitro and animal studies.What is new: Adhesion structures may be important for probiotic function.Need to systematically determine physical characteristics of probiotics before selecting for clinical trials.Probiotics may be genetically engineered to add to clinical efficacy.

In vitro evaluation of the probiotic potential of Lactobacillus isolated from native swine manure

Background and Aim:

Using antimicrobials as a feed additive in swine production is prohibited because it is a major cause of the emergence of antimicrobial-resistant bacteria. Probiotics such as Lactobacillus spp. are an attractive alternative to reduce antimicrobial resistance and promote swine growth. This study aimed to evaluate the in vitro probiotic properties of Lactobacillus isolated from indigenous swine manure.

Materials and Methods:

A total of 30 fecal samples from healthy individual indigenous pigs were collected and isolated on de Man, Rogosa, and Sharpe agar. The preliminary screen identified candidates with antibacterial activity against six pathogens and >50% survival and tolerance to acid (pH 3.0) and 1% bile salt. Isolates that passed the initial screen will be tested for other probiotic properties.

Results:

Of the 314 isolates from 30 pig manure samples, 17 isolates satisfied all initial conditions for probiotic properties. Each isolate has unique, distinctive properties. Isolates B4, B5, B8, B17, B87, and B144 formed thick biofilms, whereas isolates B5, B8, and 27 adhered well to the intestinal wall and exhibited strong autoaggregation properties. Isolate B4 aggregated with Enterohemorrhagic Escherichia coli and Enteropathogenic E. coli. Tests in pH-adjusted cell-free medium indicated that the antibacterial activity resulted from bacterial acidification rather than bacteriocin formation. Sequence analysis (16S rRNA) revealed 16 of the isolates were Lactobacillus plantarum, and only one isolate was Lactobacillus salivarius.

Conclusion:

We isolated 17 Lactobacillus from swine manure and demonstrated that their probiotic properties might be useful as a probiotic cocktail for swine feed.

Potential Impacts of Prebiotics and Probiotics in Cancer Prevention

BACKGROUND

Cancer is a serious problem throughout the world. The pathophysiology of cancer is multifactorial and is also related to gut microbiota. Intestinal microbes are the useful resident of the healthy human. They play various aspects of human health including nutritional biotransformation, flushing of the pathogens, toxin neutralization, immune response, and onco-suppression. Disruption in the interactions among the gut microbiota, intestinal epithelium, and the host immune system are associated with gastrointestinal disorders, neurodegenerative diseases, metabolic syndrome, and cancer. Probiotic bacteria (Lactobacillus spp., Bifidobacterium spp.) have been regarded as beneficial to health and shown to play a significant role in immunomodulation and displayed preventive role against obesity, diabetes, liver disease, inflammatory bowel disease, tumor progression, and cancer.

OBJECTIVE

The involvement of gut microorganisms in cancer development and prevention has been recognized as a balancing factor. The events of dysbiosis emphasize metabolic disorder and carcinogenesis. The gut flora potentiates immunomodulation and minimizes the limitations of usual chemotherapy. The significant role of prebiotics and probiotics on the improvement of immunomodulation and antitumor properties has been considered.

METHODS

I had reviewed the literature on the multidimensional activities of prebiotics and probiotics from the NCBI website database PubMed, Springer Nature, Science Direct (Elsevier), Google Scholar database to search relevant articles. Specifically, I had focused on the role of prebiotics and probiotics in immunomodulation and cancer prevention.

RESULTS

Prebiotics are the nondigestible fermentable sugars that selectively influence the growth of probiotic organisms that exert immunomodulation over the cancerous growth. The oncostatic properties of bacteria are mediated through the recruitment of cytotoxic T cells, natural killer cells, and oxidative stress-induced apoptosis in the tumor microenvironment. Moreover, approaches have also been taken to use probiotics as an adjuvant in cancer therapy.

CONCLUSION

The present review has indicated that dysbiosis is the crucial factor in many pathological situations including cancer. Applications of prebiotics and probiotics exhibit the immune-surveillance as oncostatic effects. These events increase the possibilities of new therapeutic strategies for cancer prevention.

Determination of competition and adhesion abilities of lactic acid bacteria against gut pathogens in a whole-tissue model

In an intestinal system with a balanced microbial diversity, lactic acid bacteria (LAB) are the key element which prevents the colonization and invasion of gut pathogens. Adhesion ability is important for the colonization and competition abilities of LAB. The aim of this study was to determine the adhesion and competition abilities of LAB by using a whole-tissue model. Indigenous strains were isolated from spontaneously fermented foods like cheese and pickles. The aggregation and competition abilities of the isolates were determined, as well as their resistance to gastrointestinal conditions. Four Lactobacillus strains and one Weissella strain were found to be highly competitive against three major gut pathogens, namely Clostridium difficile, Listeria monocytogenes and Salmonella Enteritidis. Tested strains decreased the number of pathogens to below their disease-causing levels. According to the results, the numbers of C. difficile and L. monocytogenes bacteria decreased by an average of 3 log, and their adhesion rates decreased by approximately 50%. However, the number of S. Enteritidis bacteria was decreased by only 1 log compared with its initial number. We thought that the weak effect on Salmonella was due to its possession of many virulence factors. The results showed that natural isolates from sources other than human specimens like the Weissella strain in this study were quite competent when compared with the human isolates in terms of their adhesion to intestines and resistance to gastrointestinal tract conditions. It was also revealed that a whole-tissue model with all-natural layers can be successfully used in adhesion and competition tests.

In vitro studies of adhesion properties of six lactic acid bacteria isolated from the longevous population of China

Six lactic acid bacteria (LAB), isolated from the intestinal tract of the longevous population, were prominent for their strong bacteriostatic ability. In this study, the adhesion properties of the six strains were determined in vitro to explore their potential to be used as probiotics. The hydrophobicity and aggregation activity were firstly detected and were varied from 14.83% to 57.3% and 12.7% to 31%, respectively. Moreover, the adhesion activity to the intestinal crypt cells (IEC-6 cells) was proved to be varied from 5.4 to 21.7 bacteria numbers per cell. Furthermore, all the tested LAB samples could inhibit 3 Gram-positive and 3 Gram-negative indicator microorganisms to adhere to the IEC-6 cells. Meanwhile every sample was inclined to exclude rather than displace or compete to inhibit the indicator microorganisms to adhere to IEC-6 cells. Afterwards, the adhesion activities of the LAB were demonstrated to be highly affected by the surface proteins considering the treatments of heat, pepsin, trypsin and NaIO₄. The surface proteins (8–14 kDa) of every sample were isolated and proved to be helpful to regain more than 30% of the adhesion activity for the corresponding samples. This study will be beneficial to examine the characteristics of these strains especially L. casei g9 when used as probiotics in dairy food products.

Adhesion related activities of six lactic acid bacteria were detected. This study will be beneficial to examine the characteristics of these strains used as probiotics in dairy products.

Prolonged Heat Stress of Lactobacillus paracasei GCRL163 Improves Binding to Human Colorectal Adenocarcinoma HT-29 Cells and Modulates the Relative Abundance of Secreted and Cell Surface-Located Proteins

Lactobacillus casei group bacteria improve cheese ripening and may interact with host intestinal cells as probiotics, where surface proteins play a key role. Three complementary methods [trypsin shaving (TS), LiCl-sucrose (LS) extraction, and extracellular culture fluid precipitation] were used to analyze cell surface proteins of Lactobacillus paracasei GCRL163 by label-free quantitative proteomics after culture to the mid-exponential phase in bioreactors at pH 6.5 and temperatures of 30-45 °C. A total of 416 proteins, including 300 with transmembrane, cell wall anchoring, and secretory motifs and 116 cytoplasmic proteins, were quantified as surface proteins. Although LS caused significantly greater cell lysis as growth temperature increased, higher numbers of extracytoplasmic proteins were exclusively obtained by LS treatment. Together with the increased positive surface charge of cells cultured at supra-optimal temperatures, proteins including cell wall hydrolases Msp1/p75 and Msp2/p40, α-fucosidase AlfB, SecA, and a PspC-domain putative adhesin were upregulated in surface or secreted protein fractions, suggesting that cell adhesion may be altered. Prolonged heat stress (PHS) increased binding of L. paracasei GCRL163 to human colorectal adenocarcinoma HT-29 cells, relative to acid-stressed cells. This study demonstrates that PHS influences cell adhesion and relative abundance of proteins located on the surface, which may impact probiotic functionality, and the detected novel surface proteins likely linked to the cell cycle and envelope stress.

Aflatoxins: Occurrence, Exposure, and Binding to Lactobacillus Species from the Gut Microbiota of Rural Ugandan Children

Chronic exposure of children in sub-Saharan Africa to aflatoxins has been associated with low birth weight, stunted growth, immune suppression, and liver function damage. Lactobacillus species have been shown to reduce aflatoxin contamination during the process of food fermentation. Twenty-three Lactobacillus strains were isolated from fecal samples obtained from a cohort of rural Ugandan children at the age of 54 to 60 months, typed by 16S rRNA gene sequencing, and characterized in terms of their ability to bind aflatoxin B1 in vitro. Evidence for chronic exposure of these children to aflatoxin B1 in the study area was obtained by analysis of local foods (maize flour and peanuts), followed by the identification of the breakdown product aflatoxin M1 in their urine samples. Surprisingly, Lactobacillus in the gut microbiota of 140 children from the same cohort at 24 and 36 months showed the highest positive correlation coefficient with stunting among all bacterial genera identified in the stool samples. This correlation was interpreted to be associated with dietary changes from breastfeeding to plant-based solid foods that pose an additional risk for aflatoxin contamination, on one hand, and lead to increased intake of Lactobacillus species on the other.

Probiotic Propionibacterium freudenreichii requires SlpB protein to mitigate mucositis induced by chemotherapy

Propionibacterium freudenreichii CIRM-BIA 129 (P. freudenreichii wild type, WT) is a probiotic bacterium, which exerts immunomodulatory effects. This strain possesses extractable surface proteins, including SlpB, which are involved in anti-inflammatory effect and in adhesion to epithelial cells. We decided to investigate the impact of slpB gene mutation on immunomodulation in vitro and in vivo. In an in vitro assay, P. freudenreichii WT reduced expression of IL-8 (p<0.0001) and TNF-α (p<0.0001) cytokines in LPS-stimulated HT-29 cells. P. freudenreichii ΔslpB, lacking the SlpB protein, failed to do so. Subsequently, both strains were investigated in vivo in a 5-FU-induced mucositis mice model. Mucositis is a common side effect of cytotoxic chemotherapy with 5-FU, characterized by mucosal injury, inflammation, diarrhea, and weight loss. The WT strain prevented weight loss, reduced inflammation and consequently histopathological scores. Furthermore, it regulated key markers, including Claudin-1 (cld1, p<0.0005) and IL-17a (Il17a, p<0.0001) genes, as well as IL-12 (p<0.0001) and IL-1β (p<0.0429) cytokines levels. Mutant strain displayed opposite regulatory effect on cld1 expression and on IL-12 levels. This work emphasizes the importance of SlpB in P. freudenreichii ability to reduce mucositis inflammation. It opens perspectives for the development of probiotic products to decrease side effects of chemotherapy using GRAS bacteria with immunomodulatory surface protein properties.

Adhesion mechanisms mediated by probiotics and prebiotics and their potential impact on human health

Adhesion ability to the host is a classical selection criterion for potential probiotic bacteria that could result in a transient colonisation that would help to promote immunomodulatory effects, as well as stimulate gut barrier and metabolic functions. In addition, probiotic bacteria have a potential protective role against enteropathogens through different mechanisms including production of antimicrobial compounds, reduction of pathogenic bacterial adhesion and competition for host cell binding sites. The competitive exclusion by probiotic bacteria has a beneficial effect not only on the gut but also in the urogenital tract and oral cavity. On the other hand, prebiotics may also act as barriers to pathogens and toxins by preventing their adhesion to epithelial receptors. In vitro studies with different intestinal cell lines have been widely used along the last decades to assess the adherence ability of probiotic bacteria and pathogen antagonism. However, extrapolation of these results to in vivo conditions still remains unclear, leading to the need of optimisation of more complex in vitro approaches that include interaction with the resident microbiota to address the current limitations. The aim of this mini review is to provide a comprehensive overview on the potential effect of the adhesive properties of probiotics and prebiotics on the host by focusing on the most recent findings related with adhesion and immunomodulatory and antipathogenic effect on human health.

Slp-coated liposomes for drug delivery and biomedical applications: potential and challenges

Slp forms a crystalline array of proteins on the outermost envelope of bacteria and archaea with a molecular weight of 40-200 kDa. Slp can self-assemble on the surface of liposomes in a proper environment via electrostatic interactions, which could be employed to functionalize liposomes by forming Slp-coated liposomes for various applications. Among the molecular characteristics, the stability, adhesion, and immobilization of biomacromolecules are regarded as the most meaningful. Compared to plain liposomes, Slp-coated liposomes show excellent physicochemical and biological stabilities. Recently, Slp-coated liposomes were shown to specifically adhere to the gastrointestinal tract, which was attributed to the "ligand-receptor interaction" effect. Furthermore, Slp as a "bridge" can immobilize functional biomacromol-ecules on the surface of liposomes via protein fusion technology or intermolecular forces, endowing liposomes with beneficial functions. In view of these favorable features, Slp-coated liposomes are highly likely to be an ideal platform for drug delivery and biomedical uses. This review aims to provide a general framework for the structure and characteristics of Slp and the interactions between Slp and liposomes, to highlight the unique properties and drug delivery as well as the biomedical applications of the Slp-coated liposomes, and to discuss the ongoing challenges and perspectives.

Interrogation of Milk-Driven Changes to the Proteome of Intestinal Epithelial Cells by Integrated Proteomics and Glycomics

Bovine colostrum is a rich source of bioactive components which are important in the development of the intestine, in stimulating gut structure and function and in preparing the gut surface for subsequent colonization of microbes. What is not clear, however, is how colostrum may affect the repertoire of receptors and membrane proteins of the intestinal surface and the post-translational modifications associated with them. In the present work, we aimed to characterize the surface receptor and glycan profile of human HT-29 intestinal cells after exposure to a bovine colostrum fraction (BCF) by means of proteomic and glycomic analyses. Integration of label-free quantitative proteomic analysis and lectin array profiles confirmed that BCF exposure results in changes in the levels of glycoproteins present at the cell surface and also changes to their glycosylation pattern. This study contributes to our understanding of how milk components may regulate intestinal cells and prime them for bacterial interaction.

Caloric restriction promotes functional changes involving short-chain fatty acid biosynthesis in the rat gut microbiota

Caloric restriction (CR) is known to promote health and longevity, likely via modification of the gut microbiota (GM). However, functional and metabolic changes induced in the GM during CR are still unidentified. Here, we investigated the short- and long-term effects of CR on the rat GM using a metaproteogenomic approach. We show that a switch from ad libitum (AL) low fat diet to CR in young rats is able to induce rapid and deep changes in their GM metaproteomic profile, related to a reduction of the Firmicutes/Bacteroidetes ratio and an expansion of lactobacilli. Specifically, we observed a significant change in the expression of the microbial enzymes responsible for short-chain fatty acid biosynthesis, with CR boosting propionogenesis and limiting butyrogenesis and acetogenesis. Furthermore, these CR-induced effects were maintained up to adulthood and started to be reversed after a short-term diet change. We also found that CR alters the abundance of an array of host proteins released in stool, mainly related to epithelial barrier integrity and inflammation. Hence, our results provide thorough information about CR-induced modifications to GM and host functional activity, and might constitute the basis for novel GM-based approaches aimed at monitoring the effectiveness of dietary interventions.

Lactobacillus accelerates ISCs regeneration to protect the integrity of intestinal mucosa through activation of STAT3 signaling pathway induced by LPLs secretion of IL-22

The regeneration of intestinal epithelial are maintained by continuous differentiation and proliferation of intestinal stem cells (ISCs) under physiological and pathological conditions. However, little is known about the regulatory effect of intestinal microbiota on its recovery ability to repair damaged mucosal barrier. In this study, we established intestinal organoids and lamina propria lymphocytes (LPLs) co-cultured system, plus mice experiments, to explore the protective effect of Lactobacillus reuteri D8 on integrity of intestinal mucosa. We found that only live L. reuteri D8 was effective in protecting the morphology of intestinal organoids and normal proliferation of epithelial stained with EdU under TNF-α treatment, which was also further verified in mice experiments. L. reuteri D8 colonized in the intestinal mucosa and ameliorated intestinal mucosa damage caused by DSS treatment, including improvement of body weight, colon length, pathological change, and proliferation level. The repair process stimulated by L. reuteri D8 was also accompanied with increased numbers of Lgr5+ and lysozyme+ cells both in intestinal organoids and mice intestine. Furthermore, we demonstrated that D8 metabolite indole-3-aldehyde stimulated LPLs to secret IL-22 through aryl hydrocarbon receptor (AhR) and then induced phosphorylation of STAT3 to accelerate proliferation of intestinal epithelial, thus recovering damaged intestinal mucosa. Our findings indicate L. reuteri protects intestinal barrier and activates intestinal epithelial proliferation, which sheds light on treatment approaches for intestinal inflammation based on ISCs with probiotics Lactobacillus and daily probiotic consumption in heath foods.

Extractable Bacterial Surface Proteins in Probiotic-Host Interaction

Some Gram-positive bacteria, including probiotic ones, are covered with an external proteinaceous layer called a surface-layer. Described as a paracrystalline layer and formed by the self-assembly of a surface-layer-protein (Slp), this optional structure is peculiar. The surface layer per se is conserved and encountered in many prokaryotes. However, the sequence of the corresponding Slp protein is highly variable among bacterial species, or even among strains of the same species. Other proteins, including surface layer associated proteins (SLAPs), and other non-covalently surface-bound proteins may also be extracted with this surface structure. They can be involved a various functions. In probiotic Gram-positives, they were shown by different authors and experimental approaches to play a role in key interactions with the host. Depending on the species, and sometime on the strain, they can be involved in stress tolerance, in survival within the host digestive tract, in adhesion to host cells or mucus, or in the modulation of intestinal inflammation. Future trends include the valorization of their properties in the formation of nanoparticles, coating and encapsulation, and in the development of new vaccines.