Impact of lipoteichoic acid modification on the performance of the probiotic Lactobacillus rhamnosus GG in experimental colitis

Molecular Mechanisms of Lacticaseibacillus rhamnosus, LGG® Probiotic Function

To advance probiotic research, a comprehensive understanding of bacterial interactions with human physiology at the molecular and cellular levels is fundamental. Lacticaseibacillus rhamnosus LGG® is a bacterial strain that has long been recognized for its beneficial effects on human health. Probiotic effector molecules derived from LGG®, including secreted proteins, surface-anchored proteins, polysaccharides, and lipoteichoic acids, which interact with host physiological processes have been identified. In vitro and animal studies have revealed that specific LGG® effector molecules stimulate epithelial cell survival, preserve intestinal barrier integrity, reduce oxidative stress, mitigate excessive mucosal inflammation, enhance IgA secretion, and provide long-term protection through epigenetic imprinting. Pili on the cell surface of LGG® promote adhesion to the intestinal mucosa and ensure close contact to host cells. Extracellular vesicles produced by LGG® recapitulate many of these effects through their cargo of effector molecules. Collectively, the effector molecules of LGG® exert a significant influence on both the gut mucosa and immune system, which promotes intestinal homeostasis and immune tolerance.

Postbiotics Implication in the Microbiota-Host Intestinal Epithelial Cells Mutualism

To sustain host health and provide the microbial community with a nutrient-rich environment, the host and gut microbiota must interact with one another. These interactions between commensal bacterial and intestinal epithelial cells (IECs) serve as the first line of defense against gut microbiota in preserving intestinal homeostasis. In this microenvironment, the post-biotics and similar molecules such as p40 exert several beneficial effects through regulation of IECs. Importantly, post-biotics were discovered to be transactivators of the EGF receptor (EGFR) in IECs, inducing protective cellular responses and alleviating colitis. The transient exposure to post-biotics such as p40 during the neonatal period reprograms IECs by upregulation of a methyltransferase, Setd1β, leading to a sustained increase in TGF- β release for the expansion of regulatory T cells (Tregs) in the intestinal lamina propria and durable protection against colitis in adulthood. This crosstalk between the IECs and post-biotic secreted factors was not reviewed previously. Therefore, this review describes the role of probiotic-derived factors in the sustainability of intestinal health and improving gut homeostasis via certain signaling pathways. In the era of precision medicine and targeted therapies, more basic, preclinical, and clinical evidence is needed to clarify the efficacy of probiotics released as functional factors in maintaining intestinal health and preventing and treating disease.

Insight into the structure, biosynthesis, isolation method and biological function of teichoic acid in different gram-positive microorganisms: A review

Teichoic acid (TA) is a weakly anionic polymer present in the cell walls of Gram-positive bacteria. It can be classified into wall teichoic acid (WTA) and lipoteichoic acid (LTA) based on its localization in the cell wall. The structure and biosynthetic pathway of TAs are strain-specific and have a significant role in maintaining cell wall stability. TAs have various beneficial functions, such as immunomodulatory, anticancer and antioxidant activities. However, the purity and yield of TAs are generally not high, and different isolation methods may even affect their structural integrity, which limits the research progress on the probiotic functions of TA. This paper reviews an overview of the structure and biosynthetic pathway of TAs in different strains, as well as the research progress of the isolation and purification methods of TAs. Furthermore, this review also highlights the current research status on the biological functions of TAs. Through a comprehensive understanding of this review, it is expected to pave the way for advancements in isolating and purifying high-quality TAs and, in turn, lay a foundation for contributing to the development of targeted probiotic therapies.

Postbiotics: Functional Food Materials and Therapeutic Agents for Cancer, Diabetes, and Inflammatory Diseases

Postbiotics are (i) "soluble factors secreted by live bacteria, or released after bacterial lysis, such as enzymes, peptides, teichoic acids, peptidoglycan-derived muropeptides, polysaccharides, cell-surface proteins and organic acids"; (ii) "non-viable metabolites produced by microorganisms that exert biological effects on the hosts"; and (iii) "compounds produced by microorganisms, released from food components or microbial constituents, including non-viable cells that, when administered in adequate amounts, promote health and wellbeing". A probiotic- and prebiotic-rich diet ensures an adequate supply of these vital nutrients. During the anaerobic fermentation of organic nutrients, such as prebiotics, postbiotics act as a benevolent bioactive molecule matrix. Postbiotics can be used as functional components in the food industry by offering a number of advantages, such as being added to foods that are harmful to probiotic survival. Postbiotic supplements have grown in popularity in the food, cosmetic, and healthcare industries because of their numerous health advantages. Their classification depends on various factors, including the type of microorganism, structural composition, and physiological functions. This review offers a succinct introduction to postbiotics while discussing their salient features and classification, production, purification, characterization, biological functions, and applications in the food industry. Furthermore, their therapeutic mechanisms as antibacterial, antiviral, antioxidant, anticancer, anti-diabetic, and anti-inflammatory agents are elucidated.

A key genetic factor governing arabinan utilization in the gut microbiome alleviates constipation

Impaired gastrointestinal motility is associated with gut dysbiosis. Probiotics, such as Bifidobacteria, can improve this bowel disorder; however, efficacy is strain-dependent. We determine that a genetic factor, the abfA cluster governing arabinan utilization, in Bifidobacterium longum impacts treatment efficacy against functional constipation (FC). In mice with FC, B. longum, but not an abfA mutant, improved gastrointestinal transit time, an affect that was dependent upon dietary arabinan. abfA genes were identified in other commensal bacteria, whose effects in ameliorating murine FC were similarly abfA-dependent. In a double-blind, randomized, placebo-controlled clinical trial, supplementation with abfA-cluster-carrying B. longum, but not an abfA-deficient strain, enriched arabinan-utilization residents, increased beneficial metabolites, and improved FC symptoms. Across human cohorts, abfA-cluster abundance can predict FC, and transplantation of abfA cluster-enriched human microbiota to FC-induced germ-free mice improved gut motility. Collectively, these findings demonstrate a role for microbial abfA cluster in ameliorating FC, establishing principles for genomics-directed probiotic therapies.

The Potential Therapeutic Role of Lactobacillaceae rhamnosus for Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a heterogeneous group of diseases associated with chronic inflammation of the intestinal tract, and is highly prevalent worldwide. Although its origin is not yet fully understood, new evidence emphasizes that environmental factors, especially dietary factors and intestinal microbiota disorders are key triggers of IBD. Probiotics, such as Lactobacillaceae spp., play an essential role in human health as they exert beneficial effects on the composition of the human gastrointestinal microbial community and immune system. Probiotic-based therapies have been shown to be effective in alleviating IBD. Among these, Lactobacillaceae rhamnosus is one of the most widely used strains. L. rhamnosus is widely present in the intestines of healthy individuals; it regulates the intestinal immune system and reduces inflammation through a variety of mechanisms. The purpose of this study was to identify scientific evidence related to L. rhamnosus and IBD, review and summarize the results, and discuss the possible mechanisms of action as a starting point for future research on IBD treatment.

In vitro evaluation of Lactiplantibacillus plantarum HOKKAIDO strain, effective lactic acid bacteria for calf diarrhea

Calf diarrhea adversely affects growth and sometimes results in mortality, leading to severe economic losses to the cattle industry. Antibiotics are useful in the treatment against bacterial diarrhea, but not against viral, protozoan, and antibiotic-resistant bacterial diarrhea. Therefore, there are growing requirements for a novel control method for calf diarrhea. Probiotics have been considered promising candidates for preventive and supportive therapy for calf diarrhea for many years. A recent study has revealed that Lactiplantibacillus plantarum HOKKAIDO strain (Lp-HKD) reduces intestinal pathology and the severity of diarrhea in bovine rotavirus (BRV)-infected calves. Lp-HKD is known to enhance the function of human immune cells and expected to be used as probiotics for humans. Therefore, it is hypothesized that Lp-HKD modulates antiviral immune response in cattle and provide the clinical benefits in BRV-infected calves. However, the detailed mechanism of Lp-HKD-induced immunomodulation remains unknown. Thus, this study aimed to elucidate the immunomodulatory and antiviral effects of Lp-HKD in cattle. Cultivation assay of bovine peripheral blood mononuclear cells (PBMCs) showed that live and heat-killed Lp-HKD stimulates the production of interleukin-1β (IL-1β), IL-6, IL-10, and interferon-γ (IFN-γ) from PBMCs. Stimulation by heat-killed Lp-HKD yielded stronger cytokine production than stimulation by the live Lp-HKD. Additionally, CD14⁺ monocytes were identified as major producers of IL-1β, IL-6, and IL-10 under Lp-HKD stimulation; however, IFN-γ was mainly produced from immune cells other than CD14⁺ monocytes. Depletion of CD14⁺ monocytes from the PBMCs cultivation strongly decreased cytokine production induced by heat-killed Lp-HKD. The inhibition of toll-like receptor (TLR) 2/4 signaling decreased IL-1β and IL-6 production induced by live Lp-HKD and IL-1β, IL-6, and IFN-γ production induced by heat-killed Lp-HKD. Furthermore, live or heat-killed Lp-HKD also activated T cells and their production of IFN-γ and tumor necrosis factor-α. Then, culture supernatants of bovine PBMCs treated with heat-killed Lp-HKD demonstrated antiviral effects against BRV in vitro. In conclusion, this study demonstrated that Lp-HKD activates the functions of bovine immune cells via TLR2/4 signaling and exerts an antiviral effect against BRV through the induction of antiviral cytokines. Lp-HKD could be useful for the prevention and treatment of calf diarrhea through its immune activating effect.

The synbiotic mixture of Bacillus licheniformis and Saccharomyces cerevisiae extract aggravates dextran sulfate sodium induced colitis in rats

BACKGROUND

Uncertain effects of probiotics and/or prebiotics have been reported in experimental and clinical colitis. This study aims to examine the effects of a synbiotic combination comprising Bacillus licheniformis DSM 17236 and Saccharomyces cerevisiae cell wall extract on dextran sulfate sodium (DSS)-induced colitis in Sprague Dawley rats.

METHODS

Acute colitis was induced in rats by oral administration of DSS 3.5% for 7 days. Fifty rats were divided equally into five groups; one control group and the other groups were induced with colitis and treated with or without the tested synbiotic, mixed with diet, for 28 days and sulfasalazine (100 mg/kg) via intragastric tube once daily for 14 days.

RESULTS

Symptomatically, the synbiotic administration raised the disease activity index (DAI) to comparable scores of the DSS group, specially from the 2nd to 7th days post DSS intoxication. It also induced a significant (p < 0.05) amplification of WBCs, myeloperoxidase (MPO), malondialdehyde (MDA), nuclear factor kappa B (NF-kB) expression and proinflammatory cytokines tumor necrosis factor alpha (TNFα), interferon gamma (INFγ), and interleukin-1 beta (IL-1β) while depressed the antioxidant enzymes glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) when compared with the DSS and control groups. The DSS intoxicated and Synbiotic+DSS groups showed desquamations of the covering epithelium, noticeable diffuse leukocytic infiltrations, sever catarrhal enteritis, ischemic colitis with diffuse coagulative necrosis of the entire colonic mucosa. Contrarily, sulfasalazine proved to be effective in the reduction of the tested inflammatory markers and the pathological degenerative changes of the DSS ulcerative colitis.

CONCLUSION

The examined synbiotic did not ameliorate but aggravated the DSS-induced colitis, so it should be subjected to intensive experimental and clinical testing before their use in animals and human.

Limnospira indica PCC 8005 or Lacticaseibacillus rhamnosus GG Dietary Supplementation Modulate the Gut Microbiome in Mice

While dietary supplements can have beneficial effects on the health of the intestine, these effects can come with unresolved issues in terms of therapeutic efficacy and mechanisms of action. In this study, the model probiotic Lacticaseibacillus rhamnosus GG ATCC 53103 and the anciently used dietary supplement Limnospira indica strain PCC 8005 were compared for their effects on murine intestinal ecology. Healthy male mice received either saline or suspensions of living cells of L. indica PCC 8005 or L. rhamnosus GG daily along a two-week intervention period, followed by a two-week washout period. Both bacteria-based solutions appeared able to transiently shift the microbial community, which were characterized by a higher relative abundance of members of the butyrate producing Lachnospiraceae and Porphyromonadaceae families.

Novel perspective on the regulation of food allergy by probiotic: The potential of its structural components

Food allergy (FA) is a global public health issue with growing prevalence. Increasing evidence supports the strong correlation between intestinal microbiota dysbiosis and food allergies. Probiotic intervention as a microbiota-based therapy could alleviate FA effectively. In addition to improving the intestinal microbiota disturbance and affecting microbial metabolites to regulate immune system, immune responses induced by the recognition of pattern recognition receptors to probiotic components may also be one of the mechanisms of probiotics protecting against FA. In this review, it is highlighted in detail about the regulatory effects on the immune system and anti-allergic potential of probiotic components including the flagellin, pili, peptidoglycan, lipoteichoic acid, exopolysaccharides, surface (S)-layer proteins and DNA. Probiotic components could enhance the function of intestinal epithelial barrier as well as regulate the balance of cytokines and T helper (Th) 1/Th2/regulatory T cell (Treg) responses. These evidences suggest that probiotic components could be used as nutritional or therapeutic agents for maintaining immune homeostasis to prevent FA, which will contribute to providing new insights into the resolution of FA and better guidance for the development of probiotic products.

Structure and Anti-Inflammation Potential of Lipoteichoic Acids Isolated from Lactobacillus Strains

Lactobacillus are normal inhabitants of the gastrointestinal tract and confer a variety of health effects. Lipoteichoic acid (LTA), an amphiphilic substance located in the cell membrane, is a key molecule in probiotic–host crosstalk. Through the characterization of structural characteristics of LTA molecules derived from Lactobacillus plantarum A3, Lactobacillus reuteri DMSZ 8533, and Lactobacillus acidophilus CICC 6074, there exists some heterogeneity in LTA molecules, which perhaps contributes to the distinguishable adhesion properties of Lactobacillus strains based on fluorescence microscopy observations. In LPS-induced RAW 264.7 cells, LTAs derived from three Lactobacillus strains obviously alleviated inflammatory responses as evidenced by the altered inflammatory cytokine levels of TNF-α, IL-6, and IL-10. Western blotting demonstrated that L. reuteri LTA blocked LPS-triggered expression of the MAPK and NF-κB pathways. The findings further validated that LTA is an important effector molecule and deserves further consideration as an alternative therapeutic for ulcerative colitis treatment.

Microencapsulating Alginate-Based Polymers for Probiotics Delivery Systems and Their Application

Probiotics exhibit many health benefits and a great potential for broad applications in pharmaceutical fields, such as prevention and treatment of gastrointestinal tract diseases (irritable bowel syndrome), prevention and therapy of allergies, certain anticancer effects, and immunomodulation. However, their applications are limited by the low viability and metabolic activity of the probiotics during processing, storage, and delivery in the digestive tract. To overcome the mentioned limitations, probiotic delivery systems have attracted much attention. This review focuses on alginate as a preferred polymer and presents recent advances in alginate-based polymers for probiotic delivery systems. We highlight several alginate-based delivery systems containing various types of probiotics and the physical and chemical modifications with chitosan, cellulose, starch, protein, fish gel, and many other materials to enhance their performance, of which the viability and protective mechanisms are discussed. Withal, various challenges in alginate-based polymers for probiotics delivery systems are traced out, and future directions, specifically on the use of nanomaterials as well as prebiotics, are delineated to further facilitate subsequent researchers in selecting more favorable materials and technology for probiotic delivery.

Levilactobacillus brevis KU15151 Inhibits Staphylococcus aureus Lipoteichoic Acid-Induced Inflammation in RAW 264.7 Macrophages

Inflammation is a host defense response to harmful agents, such as pathogenic invasion, and is necessary for health. Excessive inflammation may result in the development of inflammatory disorders. Levilactobacillus brevis KU15151 has been reported to exhibit probiotic characteristics and antioxidant activities, but the effect of this strain on inflammatory responses has not been determined. The present study aimed to investigate the anti-inflammatory potential of L. brevis KU15151 in Staphylococcus aureus lipoteichoic acid (aLTA)-induced RAW264.7 macrophages. Treatment with L. brevis KU15151 reduced the production of nitric oxide and prostaglandin E₂ by suppressing the expression of inducible nitric oxide synthase and cyclooxygenase-2. Additionally, the production of proinflammatory cytokines including tumor necrosis factor-α, interleukin (IL)-6, and IL-1β, decreased after treatment with L. brevis KU15151 in aLTA-stimulated RAW 264.7 cells. Furthermore, this strain alleviated the activation of nuclear factor-κB and mitogen-activated protein kinase signaling pathways. Moreover, the generation of reactive oxygen species was downregulated by treatment with L. brevis KU15151. These results demonstrate that L. brevis KU15151 possesses an inhibitory effect against aLTA-mediated inflammation and may be employed as a functional probiotic for preventing inflammatory disorders.

Probiotic Molecules That Inhibit Inflammatory Diseases

Consumption of probiotics for health purposes has increased vastly in the past few decades, and yet the scientific evidence to support health benefits from probiotics is only beginning to emerge. As more probiotics are studied, we are beginning to understand the mechanisms of action by which they benefit human health, as well as to identify the bacterial molecules responsible for these benefits. A new era of therapeutics is on the horizon in which purified molecules from probiotics will be used to prevent and treat diseases. In this review, we summarize the active molecules from probiotic bacteria that have been shown to affect innate and adaptive immunity and have health benefits in experimental settings. We focus particularly on the cellular and molecular mechanisms of the probiotic Bacillus subtilis and its active molecule, exopolysaccharide (ESPBs).

Molecular and Cellular Mechanisms Influenced by Postbiotics

In recent years, commensal bacteria colonizing the human body have been recognized as important determinants of health and multiple pathologic conditions. Among the most extensively studied commensal bacteria are the gut microbiota, which perform a plethora of functions, including the synthesis of bioactive products, metabolism of dietary compounds, and immunomodulation, both through attenuation and immunostimulation. An imbalance in the microbiota population, i.e., dysbiosis, has been linked to many human pathologies, including various cancer types and neurodegenerative diseases. Targeting gut microbiota and microbiome-host interactions resulting from probiotics, prebiotics, and postbiotics is a growing opportunity for the effective treatment of various diseases. As more research is being conducted, the microbiome field is shifting from simple descriptive analysis of commensal compositions to more molecular, cellular, and functional studies. Insight into these mechanisms is of paramount importance for understanding and modulating the effects that microbiota, probiotics, and their derivatives exert on host health.

Lactobacillus rhamnosus GG modifies the metabolome of pathobionts in gnotobiotic mice

Background

Lactobacillus rhamnosus GG (LGG) is the most widely used probiotic, but the mechanisms underlying its beneficial effects remain unresolved. Previous studies typically inoculated LGG in hosts with established gut microbiota, limiting the understanding of specific impacts of LGG on host due to numerous interactions among LGG, commensal microbes, and the host. There has been a scarcity of studies that used gnotobiotic animals to elucidate LGG-host interaction, in particular for gaining specific insights about how it modifies the metabolome. To evaluate whether LGG affects the metabolite output of pathobionts, we inoculated with LGG gnotobiotic mice containing Propionibacterium acnes, Turicibacter sanguinis, and Staphylococcus aureus (PTS).

Results

16S rRNA sequencing of fecal samples by Ion Torrent and MinION platforms showed colonization of germ-free mice by PTS or by PTS plus LGG (LTS). Although the body weights and feeding rates of mice remained similar between PTS and LTS groups, co-associating LGG with PTS led to a pronounced reduction in abundance of P. acnes in the gut. Addition of LGG or its secretome inhibited P. acnes growth in culture. After optimizing procedures for fecal metabolite extraction and metabolomic liquid chromatography-mass spectrometry analysis, unsupervised and supervised multivariate analyses revealed a distinct separation among fecal metabolites of PTS, LTS, and germ-free groups. Variables-important-in-projection scores showed that LGG colonization robustly diminished guanine, ornitihine, and sorbitol while significantly elevating acetylated amino acids, ribitol, indolelactic acid, and histamine. In addition, carnitine, betaine, and glutamate increased while thymidine, quinic acid and biotin were reduced in both PTS and LTS groups. Furthermore, LGG association reduced intestinal mucosal expression levels of inflammatory cytokines, such as IL-1α, IL-1β and TNF-α.

Conclusions

LGG co-association had a negative impact on colonization of P. acnes, and markedly altered the metabolic output and inflammatory response elicited by pathobionts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02178-2.

Immunobiotic Lactobacillus jensenii TL2937 Alleviates Dextran Sodium Sulfate-Induced Colitis by Differentially Modulating the Transcriptomic Response of Intestinal Epithelial Cells

Immunobiotics have emerged as a promising intervention to alleviate intestinal damage in inflammatory bowel disease (IBD). However, the beneficial properties of immunobiotics are strain dependent and, therefore, each strain has to be evaluated in order to demonstrate its potential application in IBD. Our previous in vitro and in vivo studies demonstrated that Lactobacillus jensenii TL2937 attenuates gut acute inflammatory response triggered by Toll-like receptor 4 activation. However, its effect on colitis has not been evaluated before. In this work, we studied whether the TL2937 strain was able to protect against the development of colitis in a dextran sodium sulfate (DSS)-induced mouse model and we delved into the mechanisms of action by evaluating the effect of the immunobiotic bacteria on the transcriptomic response of DSS-challenged intestinal epithelial cells. L. jensenii TL2937 was administered to adult BALB/c mice before the induction of colitis by the administration of DSS. Colitis and the associated inflammatory response were evaluated for 14 days. Mice fed with L. jensenii TL2937 had lower disease activity index and alterations of colon length when compared to control mice. Reduced myeloperoxidase activity, lower production of pro-inflammatory (TNF-α, IL-1, CXCL1, MCP-1, IL-15, and IL-17), and higher levels of immunoregulatory (IL-10 and IL-27) cytokines were found in the colon of TL2937-treated mice. In addition, the treatment of porcine intestinal epithelial (PIE) cells with L. jensenii TL2937 before the challenge with DSS differentially regulated the activation of the JNK pathway, leading to an increase in epithelial cell integrity and to a differential immunotranscriptomic response. TL2937-treated PIE cells had a significant reduction in the expression of inflammatory cytokines (TNF-α, IL-1α, IL-1β, IL-6, IL-15), chemokines (CCL2, CCL4, CCL8, CXCL4, CXCL5, CXCL9, CXCL10), adhesion molecules (SELE, SELL, EPCAM), and other immune factors (NCF1, NCF2, NOS2, SAA2) when compared to control cells after the challenge with DSS. The findings of this work indicate that (a) L. jensenii TL2937 is able to alleviate DSS-induced colitis suggesting a potential novel application for this immunobiotic strain, (b) the modulation of the transcriptomic response of intestinal epithelial cells would play a key role in the beneficial effects of the TL2937 strain on colitis, and (c) the in vitro PIE cell immunoassay system could be of value for the screening and selection of new immunobiotic strains for their application in IBD.

Disease managing capacities and mechanisms of host effects of lactic acid bacteria

Consumption of lactic acid bacteria (LAB) has been suggested to confer health-promoting effects on the host. However, effects of LABs have been reported to be species- and strain-specific and the mechanisms involved are subjects of discussion. Here, the possible mechanisms by which LABs induce antipathogenic, gut barrier enhancing and immune modulating effects in consumers are reviewed. Specific strains for which it has been proven that health is improved by these mechanisms are discussed. However, most strains probably act via several or combinations of mechanisms depending on which effector molecules they express. Current insight is that these effector molecules are either present on the cell wall of LAB or are excreted. These molecules are reviewed as well as the ligand binding receptors in the host. Also postbiotics are discussed. Finally, we provide an overview of the efficacy of LABs in combating infections caused by Helicobacter pylori, Salmonella, Escherichia coli, Streptococcus pneumoniae, and influenza virus, in controlling gut inflammatory diseases, in managing allergic disorders, and in alleviating cancer.

Characteristics of Effervescent Tablets of Lactobacilli Supplemented with Chinese Ginseng (Panax ginseng C.A. Meyer) and Polygonatum sibiricum

Development of probiotic products has always been popular in the food industry. Considering the advantages of effervescent tablets, developing probiotic products in effervescent tablet form was conducted in this study. Besides three Lactobacillus species, whole root powders of two medicine food homology herbs, Chinese ginseng (Panax ginseng C.A. Meyer) and Polygonatum sibiricum, were added to the formulation in equal amounts for multiple health care functions. Using the plate counting method, the viability of lactobacilli was measured. After tabletting, lactobacilli viability in tablets containing the two herbs, L-group (20 mg herbs/tablet), M-group (60 mg herbs/tablet), and H-group (100 mg herbs/tablet) was higher than that in the control (containing no herbs). After tablet disintegration, the survival rate of lactobacilli after gastrointestinal fluids treatment was measured; it was higher for the L-group and the H-group than for the control. After incubation with dissolved tablets for 1 h, the lethal rate of Staphylococcus aureus and Escherichia coli O157:H7 for tablets containing the herbs was lower than that for the control. In the organoleptic assessment test, the L-group and the control were preferred to the M-group and the H-group. During storage at 25 °C for two months, the viability of lactobacilli in tablets containing the herbs was similar to that in the control. In conclusion, the formulation of the L-group has the best characteristics.

Lipoteichoic Acid Is Involved in the Ability of the Immunobiotic Strain Lactobacillus plantarum CRL1506 to Modulate the Intestinal Antiviral Innate Immunity Triggered by TLR3 Activation

Studies have demonstrated that lipoteichoic acid (LTA) is involved in the immunomodulatory properties of some immunobiotic lactobacilli. The aim of this work was to evaluate whether LTA contributes to the capacity of Lactobacillus plantarum CRL1506 in modulating the intestinal innate antiviral immune response. A D-alanyl-lipoteichoic acid biosynthesis protein (dltD) knockout CRL1506 strain (L. plantarumΔdltD) was obtained, and its ability to modulate Toll-like receptor (TLR)-3-mediated immune response was evaluated in vitro in porcine intestinal epithelial (PIE) cells and in vivo in Balb/c mice. Wild-type (WT) CRL1506 (L. plantarum WT) was used as positive control. The challenge of PIE cells with the TLR3 agonist poly(I:C) significantly increased interferon (IFN)-β, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 expressions. PIE cells pretreated with L. plantarumΔdltD or L. plantarum WT showed higher levels of IFN-β while only L. plantarum WT significantly reduced the expression of IL-6 and MCP-1 when compared with poly(I:C)-treated control cells. The oral administration of L. plantarum WT to mice prior the intraperitoneal injection of poly(I:C) significantly increased IFN-β and IL-10 and reduced intraepithelial lymphocytes (CD3⁺NK1.1⁺CD8αα⁺) and pro-inflammatory mediators (TNF-α, IL-6, and IL-15) in the intestinal mucosa. Similar to the WT strain, L. plantarumΔdltD-treated mice showed enhanced levels of IFN-β after poly(I:C) challenge. However, treatment of mice with L. plantarumΔdltD was not able to increase IL-10 or reduce CD3⁺NK1.1⁺CD8αα⁺ cells, TNF-α, IL-6, or IL-15 in the intestine. These results indicate that LTA would be a key molecule in the anti-inflammatory effect induced by the CRL1506 strain in the context of TLR3-mediated inflammation.

Unexpected effect of probiotics by Lactococcus lactis subsp. lactis against colitis induced by dextran sulfate sodium in mice

Ulcerative colitis (UC) is a representative intestinal chronic inflammatory disease whose incidence is rapidly increasing worldwide. It was previously shown that some specific probiotics help to guard against UC. In this study, we analyzed the effect of Lactococcus lactis subsp. lactis JCM5805 (L. lactis), which has been put to practical use as a probiotic, on the pathogenesis of UC using a dextran sulfate sodium-induced colitis mouse model. Survival rate, length, and histopathological parameters of the colon were elucidated. Further, the concentrations of inflammatory cytokines in serum were measured. As a result, the oral administration of high-dose L. lactis showed significant decreases in survival rate and colon length. Histopathological analysis showed that a bleeding appearance was observed in the L. lactis group, and the histology scores in the L. lactis group were significantly higher than those in the normal saline group. Furthermore, the levels of interferon gamma, tumor necrosis factor alpha, and interleukin-6 were significantly elevated in the L. lactis group. These results support that high-dose administration of L. lactis deteriorates intestinal inflammation and suggest that the careful selection of probiotics strains and administration dose is important for improving colitis including UC.

Molecules Produced by Probiotics and Intestinal Microorganisms with Immunomodulatory Activity

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The probiotic microorganisms most commonly used in the food and pharmacy industry belong to Lactobacillus and Bifidobacterium, and several strains of these genera have demonstrated beneficial attributes. In addition, some other intestinal bacteria inhabiting the human microbiota, such as Faecalibacterium prausnitzii and Akkermansia muciniphila, have recently been discovered and are able to display health-promoting effects in animal and human trials. The beneficial properties of probiotics have been known for a long time, although little is known about the molecular mechanisms and the molecules responsible for their effects. However, in recent years, advances in microbiome studies, and the use of novel analytical and molecular techniques have allowed a deeper insight into their effects at the molecular level. This review summarizes the current knowledge of some of the molecules of probiotics and other intestinal commensal bacteria responsible for their immunomodulatory effect, focusing on those with more solid scientific evidence.

Impact of spray-drying on the pili of Lactobacillus rhamnosus GG

The preservation of the viability of microorganisms in probiotic formulations is the most important parameter ensuring the adequate concentration of live microorganisms at the time of administration. The formulation and processing techniques used to produce these probiotic formulations can influence the preservation of the microbial viability. However, it is also required that the bacteria maintain their key probiotic capacities during processing, formulation and shelf life. In this study, we investigated the impact of spray-drying on different cell wall properties of the model probiotic strain Lactobacillus rhamnosus GG, including its adherence to intestinal epithelial cells. The dltD gene knock-out mutant, L. rhamnosus GG CMPG5540, displaying modified cell wall lipoteichoic acids, showed significantly increased colony-forming units after spray-drying and subsequent storage under standard conditions compared to wild-type L. rhamnosus GG. In contrast, disruption of the biosynthesis of exopolysaccharides or pili expression did not impact survival. However, spray-drying did significantly affect the adherence capacity of L. rhamnosus GG. Scanning electron microscopy confirmed that the pili, key surface factors for adherence to intestinal cells and mucus, were sheared off during the spray-drying process. These data thus highlight that both the functionality and viability of probiotics should be assessed during the spray-drying process and subsequent storage.

Lactobacillus rhamnosus GG protects the intestinal epithelium from radiation injury through release of lipoteichoic acid, macrophage activation and the migration of mesenchymal stem cells

OBJECTIVE

Lactobacillus rhamnosus GG (LGG), a probiotic, given by gavage is radioprotective of the mouse intestine. LGG-induced radioprotection is toll-like receptor 2 (TLR2) and cyclooxygenase-2 (COX-2)-dependent and is associated with the migration of COX-2+mesenchymal stem cells (MSCs) from the lamina propria of the villus to the lamina propria near the crypt epithelial stem cells. Our goals were to define the mechanism of LGG radioprotection including identification of the TLR2 agonist, and the mechanism of the MSC migration and to determine the safety and efficacy of this approach in models relevant to clinical radiation therapy.

DESIGN

Intestinal radioprotection was modelled in vitro with cell lines and enteroids as well as in vivo by assaying clinical outcomes and crypt survival. Fractionated abdominal and single dose radiation were used along with syngeneic CT26 colon tumour grafts to assess tumour radioprotection.

RESULTS

LGG with a mutation in the processing of lipoteichoic acid (LTA), a TLR2 agonist, was not radioprotective, while LTA agonist and native LGG were. An agonist of CXCR4 blocked LGG-induced MSC migration and LGG-induced radioprotection. LGG given by gavage induced expression of CXCL12, a CXCR4 agonist, in pericryptal macrophages and depletion of macrophages by clodronate liposomes blocked LGG-induced MSC migration and radioprotection. LTA effectively protected the normal intestinal crypt, but not tumours in fractionated radiation regimens.

CONCLUSIONS

LGG acts as a 'time-release capsule' releasing radioprotective LTA. LTA then primes the epithelial stem cell niche to protect epithelial stem cells by triggering a multicellular, adaptive immune signalling cascade involving macrophages and PGE2 secreting MSCs.

TRIAL REGISTRATION NUMBER

NCT01790035; Pre-results.

Effects and immune responses of probiotic treatment in ruminants

Gut microbial colonization and establishment are vital to ruminant health and production. This review article focuses on current knowledge and methods used to understand and manipulate the gut microbial community in ruminant animals, with a special focus on probiotics treatment. This review highlights the most promising of studies in this area, including gut microbial colonization and establishment, effect of gastrointestinal tract microbial community on host mucosal innate immune function, impact of feeding strategies on gut microbial community, current probiotic treatments in ruminants, methods to manipulate the gut microbiota and associated antimicrobial compounds, and models and cell lines used in understanding the host immune response to probiotic treatments. As a lot of work in this area was done in humans and mice, this review article also includes up-to-date knowledge from relevant studies in human and mouse models. This review is a useful resource for scientists working in the areas of ruminant nutrition and health, and to researchers investigating the microbial ecology and its relation to animal health.

Intranasal administration of probiotic Lactobacillus rhamnosus GG prevents birch pollen-induced allergic asthma in a murine model

BACKGROUND

There is an increasing interest in targeted application of probiotic bacteria for prevention and treatment of airway diseases, including allergies. Here, we investigated the beneficial effects of preventive intranasal treatment with probiotics Lactobacillus rhamnosus GG and L. rhamnosus GR-1 in a mouse model of allergic asthma.

METHODS

Lactobacillus rhamnosus was administered intranasally eight times on days 1-4 and 8-11 at 5 × 10⁸  CFU/dose, followed by a 2-week asthma induction protocol with birch pollen extract on alternating days. Effects of preventive treatment were analyzed based on serum antibody levels, bronchoalveolar lavage cell counts, lung histology, lung cytokine levels, and airway hyperreactivity. Colonization and translocation of L. rhamnosus were assessed by bacterial cell counts in nasal mucosa, fecal samples, cervical lymph nodes, and blood. Binding of fluorescent L. rhamnosus to fixed murine nasal mucosal cells and airway macrophages was visualized by fluorescence microscopy.

RESULTS

Transient colonization of the murine upper airways by L. rhamnosus GG was demonstrated and was approximately ten times higher compared to L. rhamnosus GR-1. Marked binding of fluorescent L. rhamnosus GG to murine nasal mucosal cells and airway macrophages was visualized. Preventive treatment with L. rhamnosus GG (but not L. rhamnosus GR-1) resulted in a significant decrease in bronchoalveolar lavage eosinophil counts, lung interleukin-13 and interleukin-5 levels, and airway hyperreactivity. A tendency toward a decrease in serum Bet v 1-specific immunoglobulin G1 was likewise observed.

CONCLUSION

Intranasally administered L. rhamnosus GG prevents the development of cardinal features of birch pollen-induced allergic asthma in a strain-specific manner.

Using murine colitis models to analyze probiotics-host interactions

Probiotics are defined as 'live microorganisms which when administered in adequate amounts confer a health benefit on the host'. So, to consider a microorganism as a probiotic, a demonstrable beneficial effect on the health host should be shown as well as an adequate defined safety status and the capacity to survive transit through the gastrointestinal tract and to storage conditions. In this review, we present an overview of the murine colitis models currently employed to test the beneficial effect of the probiotic strains as well as an overview of the probiotics already tested. Our aim is to highlight both the importance of the adequate selection of the animal model to test the potential probiotic strains and of the value of the knowledge generated by these in vivo tests.

Bacterial Signaling at the Intestinal Epithelial Interface in Inflammation and Cancer

The gastrointestinal (GI) tract provides a compartmentalized interface with an enormous repertoire of immune and metabolic activities, where the multicellular structure of the mucosa has acquired mechanisms to sense luminal factors, such as nutrients, microbes, and a variety of host-derived and microbial metabolites. The GI tract is colonized by a complex ecosystem of microorganisms, which have developed a highly coevolved relationship with the host’s cellular and immune system. Intestinal epithelial pattern recognition receptors (PRRs) substantially contribute to tissue homeostasis and immune surveillance. The role of bacteria-derived signals in intestinal epithelial homeostasis and repair has been addressed in mouse models deficient in PRRs and signaling adaptors. While critical for host physiology and the fortification of barrier function, the intestinal microbiota poses a considerable health challenge. Accumulating evidence indicates that dysbiosis is associated with the pathogenesis of numerous GI tract diseases, including inflammatory bowel diseases (IBD) and colorectal cancer (CRC). Aberrant signal integration at the epithelial cell level contributes to such diseases. An increased understanding of bacterial-specific structure recognition and signaling mechanisms at the intestinal epithelial interface is of great importance in the translation to future treatment strategies. In this review, we summarize the growing understanding of the regulation and function of the intestinal epithelial barrier, and discuss microbial signaling in the dynamic host–microbe mutualism in both health and disease.

Identification of probiotic effector molecules: present state and future perspectives

Comprehension of underlying mechanisms of probiotic action will support rationale selection of probiotic strains and targeted clinical study design with a higher likelihood of success. This will consequently contribute to better substantiation of health claims. Here, we aim to provide a perspective from a microbiology point of view that such comprehensive understanding is not straightforward. We show examples of well-documented probiotic effector molecules in Lactobacillus and Bifidobacterium strains, including surface-located molecules such as specific pili, S-layer proteins, exopolysaccharides, muropeptides, as well as more widely produced metabolites such as tryptophan-related and histamine-related metabolites, CpG-rich DNA, and various enzymes such as lactase and bile salt hydrolases. We also present recent advances in genetic tool development, microbiome analyses and model systems, as well as perspectives on how the field could further progress. This opinion is based on a discussion group organized at the annual meeting of the International Scientific Association on Probiotics and Prebiotics (ISAPP) in June 2017.

Microbiome, probiotics and neurodegenerative diseases: deciphering the gut brain axis

The gut microbiota is essential to health and has recently become a target for live bacterial cell biotherapies for various chronic diseases including metabolic syndrome, diabetes, obesity and neurodegenerative disease. Probiotic biotherapies are known to create a healthy gut environment by balancing bacterial populations and promoting their favorable metabolic action. The microbiota and its respective metabolites communicate to the host through a series of biochemical and functional links thereby affecting host homeostasis and health. In particular, the gastrointestinal tract communicates with the central nervous system through the gut-brain axis to support neuronal development and maintenance while gut dysbiosis manifests in neurological disease. There are three basic mechanisms that mediate the communication between the gut and the brain: direct neuronal communication, endocrine signaling mediators and the immune system. Together, these systems create a highly integrated molecular communication network that link systemic imbalances with the development of neurodegeneration including insulin regulation, fat metabolism, oxidative markers and immune signaling. Age is a common factor in the development of neurodegenerative disease and probiotics prevent many harmful effects of aging such as decreased neurotransmitter levels, chronic inflammation, oxidative stress and apoptosis-all factors that are proven aggravators of neurodegenerative disease. Indeed patients with Parkinson's and Alzheimer's diseases have a high rate of gastrointestinal comorbidities and it has be proposed by some the management of the gut microbiota may prevent or alleviate the symptoms of these chronic diseases.

The potential of lactic acid bacteria to colonize biotic and abiotic surfaces and the investigation of their interactions and mechanisms

Lactic acid bacteria (LAB) are a heterogeneous group of Gram-positive bacteria that comprise several species which have evolved in close association with humans (food and lifestyle). While their use to ferment food dates back to very ancient times, in the last decades, LAB have attracted much attention for their documented beneficial properties and for potential biomedical applications. Some LAB are commensal that colonize, stably or transiently, host mucosal surfaces, inlcuding the gut, where they may contribute to host health. In this review, we present and discuss the main factors enabling LAB adaptation to such lifestyle, including the gene reprogramming accompanying gut colonization, the specific bacterial components involved in adhesion and interaction with host, and how the gut niche has shaped the genome of intestine-adapted species. Moreover, the capacity of LAB to colonize abiotic surfaces by forming structured communities, i.e., biofilms, is briefly discussed, taking into account the main bacterial and environmental factors involved, particularly in relation to food-related environments. The vast spread of LAB surface-associated communities and the ability to control their occurrence hold great potentials for human health and food safety biotechnologies.

Pathogen control at the intestinal mucosa - H2O2 to the rescue

Intestinal infections are a global challenge, connected to malnutrition and inadequate hygiene in developing countries, and to expanding antibiotic resistance in developed countries. In general, a healthy host is capable of fighting off gut pathogens or at least to recover from infections quickly. The underlying protective mechanism, termed colonization resistance, is provided by indigenous commensal communities (microbiota) that are shaped and aided by the host's epithelial and innate immune system. Commensal-pathogen interactions are governed by competition for a suitable niche for replication and stable colonization, nutrient availability, species-specific alterations of the metabolic environment, changes in oxygen tension and release of chemicals and proteinaceous toxins (bacteriocins). This protective intestinal milieu is further reinforced by antimicrobial factors and chemicals secreted by the epithelial barrier, by dendritic cell sensing and by homeostasis between T-cell subsets (Treg/Th17) in the lamina propria. The 3 players (host-microbiota-pathogen) communicate via direct interactions or secreted factors. Our recent manuscript illustrates that reactive oxygen species (ROS) are an integral part of colonization resistance and should be considered an interkingdom antivirulence strategy.

Eosinophils, probiotics, and the microbiome

There is currently substantial interest in the therapeutic properties of probiotic microorganisms as recent research suggests that oral administration of specific bacterial strains may reduce inflammation and alter the nature of endogenous microflora in the gastrointestinal tract. Eosinophils are multifunctional tissue leukocytes, prominent among the resident cells of the gastrointestinal mucosa that promote local immunity. Recent studies with genetically altered mice indicate that eosinophils not only participate in maintaining gut homeostasis, but that the absence of eosinophils may have significant impact on the nature of the endogenous gut microflora and responses to gut pathogens, notably Clostridium difficile Furthermore, in human subjects, there is an intriguing relationship between eosinophils, allergic inflammation, and the nature of the lung microflora, notably a distinct association between eosinophil infiltration and detection of bacteria of the phylum Actinobacteria. Among topics for future research, it will be important to determine whether homeostatic mechanisms involve direct interactions between eosinophils and bacteria or whether they involve primarily eosinophil-mediated responses to cytokine signaling in the local microenvironment. Likewise, although is it clear that eosinophils can and do interact with bacteria in vivo, their ability to discern between pathogenic and probiotic species in various settings remains to be explored.

Identification of TLR2/TLR6 signalling lactic acid bacteria for supporting immune regulation

Although many lactic acid bacteria (LAB) influence the consumer’s immune status it is not completely understood how this is established. Bacteria-host interactions between bacterial cell-wall components and toll-like receptors (TLRs) have been suggested to play an essential role. Here we investigated the interaction between LABs with reported health effects and TLRs. By using cell-lines expressing single or combination of TLRs, we show that LABs can signal via TLR-dependent and independent pathways. The strains only stimulated and did not inhibit TLRs. We found that several strains such as L. plantarum CCFM634, L. plantarum CCFM734, L. fermentum CCFM381, L. acidophilus CCFM137, and S. thermophilus CCFM218 stimulated TLR2/TLR6. TLR2/TLR6 is essential in immune regulatory processes and of interest for prevention of diseases. Specificity of the TLR2/TLR6 stimulation was confirmed with blocking antibodies. Immunomodulatory properties of LABs were also studied by assessing IL-10 and IL-6 secretion patterns in bacteria-stimulated THP1-derived macrophages, which confirmed species and strain specific effects of the LABs. With this study we provide novel insight in LAB specific host-microbe interactions. Our data demonstrates that interactions between pattern recognition receptors such as TLRs is species and strain specific and underpins the importance of selecting specific strains for promoting specific health effects.

Lactobacillus plantarum ZS2058 produces CLA to ameliorate DSS-induced acute colitis in mice

Lactobacillus plantarumZS2058 is an efficient producer of conjugated linoleic acid (CLA)in vitro.

Preferential production of G-CSF by a protein-like Lactobacillus rhamnosus GR-1 secretory factor through activating TLR2-dependent signaling events without activation of JNKs

Background

Different species and strains of probiotic bacteria confer distinct immunological responses on immune cells. Lactobacillus rhamnosus GR-1 (GR-1) is a probiotic bacterial strain found in both the intestinal and urogenital tracts, and has immunomodulatory effects on several cell types including macrophages. However, detailed immunological responses and the signaling mechanism involved in the response are largely unknown.

Results

We examined the production of GR-1-induced cytokines/chemokines and signaling events in macrophages. Among 84 cytokines and chemokines examined, GR-1 discretely induced granulocyte colony-stimulating factor (G-CSF) mRNA at highest levels (>60-fold) without inducing other cytokines such as IL-1α, IL-1β, IL-6 and TNF-α (<5-fold). The toll-like receptor (TLR) 2/6-agonist PAM₂CSK₄, TLR2/1-agonist PAM₃CSK₄ and TLR4-agonist lipopolysaccharide induced all of these inflammatory cytokines at high levels (>50-fold). The TLR2 ligand lipoteichoic acid activated all mitogen-activated kinases, Akt and NF-κB; whereas, GR-1 selectively activated extracellular regulated kinases and p38, NF-κB and Akt, but not c-Jun N-terminal kinases (JNKs) in a TLR2-dependent manner. Using specific inhibitors, we demonstrated that lack of JNKs activation by GR-1 caused inefficient production of pro-inflammatory cytokines but not G-CSF production. A secreted heat-labile protein-like molecule, 30–100 kDa in size, induced the preferential production of G-CSF.

Conclusion

This study elucidated unique signaling events triggered by GR-1, resulting in selective production of the immunomodulatory cytokine G-CSF in macrophages.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0578-2) contains supplementary material, which is available to authorized users.

Breaking down the barriers: the gut microbiome, intestinal permeability and stress-related psychiatric disorders

The emerging links between our gut microbiome and the central nervous system (CNS) are regarded as a paradigm shift in neuroscience with possible implications for not only understanding the pathophysiology of stress-related psychiatric disorders, but also their treatment. Thus the gut microbiome and its influence on host barrier function is positioned to be a critical node within the brain-gut axis. Mounting preclinical evidence broadly suggests that the gut microbiota can modulate brain development, function and behavior by immune, endocrine and neural pathways of the brain-gut-microbiota axis. Detailed mechanistic insights explaining these specific interactions are currently underdeveloped. However, the concept that a "leaky gut" may facilitate communication between the microbiota and these key signaling pathways has gained traction. Deficits in intestinal permeability may underpin the chronic low-grade inflammation observed in disorders such as depression and the gut microbiome plays a critical role in regulating intestinal permeability. In this review we will discuss the possible role played by the gut microbiota in maintaining intestinal barrier function and the CNS consequences when it becomes disrupted. We will draw on both clinical and preclinical evidence to support this concept as well as the key features of the gut microbiota which are necessary for normal intestinal barrier function.

Selective enrichment of commensal gut bacteria protects against Citrobacter rodentium-induced colitis

The intestinal microbiota plays a key role in shaping the host immune system. Perturbation of gut microbial composition, termed dysbiosis, is associated with an increased susceptibility to intestinal pathogens and is a hallmark of a number of inflammatory, metabolic, and infectious diseases. The prospect of mining the commensal gut microbiota for bacterial strains that can impact immune function represents an attractive strategy to counteract dysbiosis and resulting disease. In this study, we show that selective enrichment of commensal gut lactobacilli protects against the murine pathogen Citrobacter rodentium, a well-characterized model of enteropathogenic and enterohemorrhagic Escherichia coli infection. The lactobacilli-enriched bacterial culture prevented the expansion of Gammaproteobacteria and Actinobacteria and was associated with improved indexes of epithelial barrier function (dextran flux), transmissible crypt hyperplasia, and tissue inflammatory cytokine levels. Moreover, cultivation of gut bacteria from Citrobacter rodentium-infected mice reveals the differential capacity of bacterial subsets to mobilize neutrophil oxidative burst and initiate the formation of weblike neutrophil extracellular traps. Our findings highlight the beneficial effects of a lactobacilli-enriched commensal gut microenvironment and, in the context of an intestinal barrier breach, the ability of neutrophils to immobilize both commensal and pathogenic bacteria.

Attenuation of Colitis by Lactobacillus casei BL23 Is Dependent on the Dairy Delivery Matrix

The role of the food delivery matrix in probiotic performance in the intestine is not well understood. Because probiotics are often provided to consumers in dairy products, we investigated the contributions of milk to the health-benefiting performance of Lactobacillus casei BL23 in a dextran sulfate sodium (DSS)-induced murine model of ulcerative colitis. L. casei BL23 protected against the development of colitis when ingested in milk but not in a nutrient-free buffer simulating consumption as a nutritional supplement. Consumption of (acidified) milk alone also provided some protection against weight loss and intestinal inflammation but was not as effective as L. casei and milk in combination. In contrast, L. casei mutants deficient in DltD (lipoteichoic acid d-alanine transfer protein) or RecA (recombinase A) were unable to protect against DSS-induced colitis, even when consumed in the presence of milk. Mice fed either L. casei or milk contained reduced quantities of colonic proinflammatory cytokines, indicating that the L. casei DltD(-) and RecA(-) mutants as well as L. casei BL23 in nutrient-free buffer were effective at modulating immune responses. However, there was not a direct correlation between colitis and quantities of these cytokines at the time of sacrifice. Identification of the cecal microbiota by 16S rRNA gene sequencing showed that L. casei in milk enriched for Comamonadaceae and Bifidobacteriaceae; however, the consumption of neither L. casei nor milk resulted in the restoration of the microbiota to resemble that of healthy animals. These findings strongly indicate that probiotic strain efficacy can be influenced by the food/supplement delivery matrix.