Lactobacillus johnsonii ameliorates intestinal, extra-intestinal and systemic pro-inflammatory immune responses following murine Campylobacter jejuni infection

Effects of dietary metabolizable energy level on hepatic lipid metabolism and cecal microbiota in aged laying hens

Lipid metabolic capacity, feed utilization, and the diversity of gut microbiota are reduced in the late laying stage for laying hens. This experiment aimed to investigate the effects of different levels of dietary metabolizable energy (ME) on hepatic lipid metabolism and cecal microbiota in late laying hens. The 216 Peking Pink laying hens (57-wk-old) were randomly assigned to experimental diets of 11.56 (HM = high ME), 11.14 (MM = medium ME), or 10.72 (LM = low ME) MJ of ME/kg, with each dietary treatment containing 6 replicates per group and 12 chickens per replicate. The HM group showed higher triglyceride (TG), total cholesterol (T-CHO), and low-density lipoprotein cholesterol (LDL-C) concentrations in the liver compared with the LM group; second, the HM group showed higher TG concentration and the LM group showed lower T-CHO concentration compared with MM group; finally, the HM group showed a lower hepatic lipase (HL) activity compared with the MM and LM groups (P < 0.05). There was a significant difference in the microbial community structure of the cecum between the HM and MM groups (P < 0.05). The decrease of dietary ME level resulted in a gradual decrease relative abundance of Proteobacteria. At the genus level, beneficial bacteria were significantly enriched in the LM group compared to the MM group, including Faecalibacterium, Lactobacillus, and Bifidobacterium, (linear discriminant analysis [LDA] >2, P <0.05). In addition, at the species level, Lactobacillus crispatus, Parabacteroides gordonii, Blautia caecimuris, and Lactobacillus johnsonii were significantly enriched in the LM group (LDA>2, P < 0.05). The HM group had a higher abundance of Sutterella spp. compared to the LM group (LDA>2, P <0.05). In conclusion, this research suggests that the reduction in dietary energy level did not adversely affect glycolipid metabolism or low dietary ME (10.72 MJ/kg). The findings can be helpful for maintaining intestinal homeostasis and increasing benefit for gut microbiota in late laying hens.

Role of the gut microbiota in tumorigenesis and treatment

The gut microbiota is a crucial component of the intricate microecosystem within the human body that engages in interactions with the host and influences various physiological processes and pathological conditions. In recent years, the association between dysbiosis of the gut microbiota and tumorigenesis has garnered increasing attention, as it is recognized as a hallmark of cancer within the scientific community. However, only a few microorganisms have been identified as potential drivers of tumorigenesis, and enhancing the molecular understanding of this process has substantial scientific importance and clinical relevance for cancer treatment. In this review, we delineate the impact of the gut microbiota on tumorigenesis and treatment in multiple types of cancer while also analyzing the associated molecular mechanisms. Moreover, we discuss the utility of gut microbiota data in cancer diagnosis and patient stratification. We further outline current research on harnessing microorganisms for cancer treatment while also analyzing the prospects and challenges associated with this approach.

Metabolomic signatures of intestinal colonization resistance against Campylobacter jejuni in mice

Introduction

Campylobacter jejuni stands out as one of the leading causes of bacterial enteritis. In contrast to humans, specific pathogen-free (SPF) laboratory mice display strict intestinal colonization resistance (CR) against C. jejuni, orchestrated by the specific murine intestinal microbiota, as shown by fecal microbiota transplantation (FMT) earlier.

Methods

Murine infection models, comprising SPF, SAB, hma, and mma mice were employed. FMT and microbiota depletion were confirmed by culture and culture-independent analyses. Targeted metabolome analyses of fecal samples provided insights into the associated metabolomic signatures.

Results

In comparison to hma mice, the murine intestinal microbiota of mma and SPF mice (with CR against C. jejuni) contained significantly elevated numbers of lactobacilli, and Mouse Intestinal Bacteroides, whereas numbers of enterobacteria, enterococci, and Clostridium coccoides group were reduced. Targeted metabolome analysis revealed that fecal samples from mice with CR contained increased levels of secondary bile acids and fatty acids with known antimicrobial activities, but reduced concentrations of amino acids essential for C. jejuni growth as compared to control animals without CR.

Discussion

The findings highlight the role of microbiota-mediated nutrient competition and antibacterial activities of intestinal metabolites in driving murine CR against C. jejuni. The study underscores the complex dynamics of host-microbiota-pathogen interactions and sets the stage for further investigations into the mechanisms driving CR against enteric infections.

Investigation of Trehalose Supplementation Impacting Campylobacter jejuni and Clostridium perfringens from Broiler Farming

In 2006, the European Commission banned the use of antibiotic promoters in animal feed. However, there is a new situation in poultry disease where it is necessary to study feed additives, which can overcome the diseases that were previously controlled through the addition of antibiotics and antimicrobial growth promoters in the feed. Therefore, trehalose was investigated to determine whether it impacts the growth performance and pathogenic bacteria (C. jejuni and C. perfringens) inoculation in broilers. In the first experiment, the tolerance of broilers to the addition of trehalose to their feed was investigated. There was no significant difference (p > 0.05) in body weight changes, daily weight gain, feed intake or feed conversion ratio during the feeding period. Within a 35-day feeding period, it was concluded that a trehalose dosage up to 10% does not exert a negative effect on broiler farming. Moreover, there was no significant difference (p > 0.05) in the broilers' growth performance, as well as C. jejuni and C. perfringens counts in the intestines and feces of broilers observed over a 5-week feeding period. However, Lactobacillus counts significantly increased in these groups with 3% and 5% trehalose supplementation. The findings indicate that trehalose supplementation in the feed cannot directly decrease C. jejuni and C. perfringens counts but may enhance gut health by raising Lactobacillus counts in chicken gut, particularly when enteropathogenic bacteria are present.

Microbiome Alterations Driven by Trypanosoma cruzi Infection in Two Disjunctive Murine Models

Alterations caused by Trypanosoma cruzi in the composition of gut microbiome may play a vital role in the host-parasite interactions that shapes physiology and immune responses against infection. Thus, a better understanding of this parasite-host-microbiome interaction may yield relevant information in the comprehension of the pathophysiology of the disease and the development of new prophylactic and therapeutic alternatives. Therefore, we implemented a murine model with two mice strains (BALB/c and C57BL/6) to evaluate the impact of Trypanosoma cruzi (Tulahuen strain) infection on the gut microbiome utilizing cytokine profiling and shotgun metagenomics. Higher parasite burdens were observed in cardiac and intestinal tissues, including changes in anti-inflammatory (interleukin-4 [IL-4] and IL-10) and proinflammatory (gamma interferon, tumor necrosis factor alpha, and IL-6) cytokines. Bacterial species such as Bacteroides thetaiotaomicron, Faecalibaculum rodentium, and Lactobacillus johnsonii showed a decrease in relative abundance, while Akkermansia muciniphila and Staphylococcus xylosus increased. Likewise, as infection progressed, there was a decrease in gene abundances related to metabolic processes such as lipid synthesis (including short-chain fatty acids) and amino acid synthesis (including branched-chain amino acids). High-quality metagenomic assembled genomes of L. johnsonii and A. muciniphila among other species were reconstructed, confirming, functional changes associated with metabolic pathways that are directly affected by the loss of abundance of specific bacterial taxa. IMPORTANCE Chagas disease (CD) is caused by the protozoan Trypanosoma cruzi, presenting acute and chronic phases where cardiomyopathy, megaesophagus, and/or megacolon stand out. During the course of its life cycle, the parasite has an important gastrointestinal tract transit that leads to severe forms of CD. The intestinal microbiome plays an essential role in the immunological, physiological, and metabolic homeostasis of the host. Therefore, parasite-host-intestinal microbiome interactions may provide information on certain biological and pathophysiological aspects related to CD. The present study proposes a comprehensive evaluation of the potential effects of this interaction based on metagenomic and immunological data from two mice models with different genetic, immunological, and microbiome backgrounds. Our findings suggest that there are alterations in the immune and microbiome profiles that affect several metabolic pathways that can potentially promote the infection's establishment, progression, and persistence. In addition, this information may prove essential in the research of new prophylactic and therapeutic alternatives for CD.

Herbal formula BaWeiBaiDuSan alleviates polymicrobial sepsis-induced liver injury via increasing the gut microbiota Lactobacillus johnsonii and regulating macrophage anti-inflammatory activity in mice

Sepsis-induced liver injury (SILI) is an important cause of septicemia deaths. BaWeiBaiDuSan (BWBDS) was extracted from a formula of Panax ginseng C. A. Meyer, Lilium brownie F. E. Brown ex Miellez var. viridulum Baker, Polygonatum sibiricum Delar. ex Redoute, Lonicera japonica Thunb., Hippophae rhamnoides Linn., Amygdalus Communis Vas, Platycodon grandiflorus (Jacq.) A. DC., and Cortex Phelloderdri. Herein, we investigated whether the BWBDS treatment could reverse SILI by the mechanism of modulating gut microbiota. BWBDS protected mice against SILI, which was associated with promoting macrophage anti-inflammatory activity and enhancing intestinal integrity. BWBDS selectively promoted the growth of Lactobacillus johnsonii (L. johnsonii) in cecal ligation and puncture treated mice. Fecal microbiota transplantation treatment indicated that gut bacteria correlated with sepsis and was required for BWBDS anti-sepsis effects. Notably, L. johnsonii significantly reduced SILI by promoting macrophage anti-inflammatory activity, increasing interleukin-10+ M2 macrophage production and enhancing intestinal integrity. Furthermore, heat inactivation L. johnsonii (HI-L. johnsonii) treatment promoted macrophage anti-inflammatory activity and alleviated SILI. Our findings revealed BWBDS and gut microbiota L. johnsonii as novel prebiotic and probiotic that may be used to treat SILI. The potential underlying mechanism was at least in part, via L. johnsonii-dependent immune regulation and interleukin-10+ M2 macrophage production.

Garlic-Derived Metabolites Exert Antioxidant Activity, Modulate Gut Microbiota Composition and Limit Citrobacter rodentium Infection in Mice

The garlic-derived compounds propyl propane thiosulfinate (PTS) and propyl propane thiosulfonate (PTSO) are metabolites with putative health benefits against intestinal inflammation that may be related to their antioxidant activity. However, the underlying mechanisms remain unclear, and whether PTS-PTSO can promote gut health by altering the microbiota and exert protection against enteric pathogens needs further investigation. Here, we explored the antioxidant activity of PTS-PTSO in murine macrophages in vitro, and in an in vivo model of bacterial infection with the bacterial pathogen Citrobacter rodentium. PTS-PTSO attenuated reactive oxygen species in lipopolysaccharide-stimulated macrophages in a nuclear factor erythroid factor 2-related factor 2 (Nrf2)-dependent manner, decreased nitric oxide levels both in macrophages in vitro and in the sera of mice fed PTS-PTSO, and had putatively beneficial effects on the commensal gut microbiota. Importantly, PTS-PTSO decreased faecal C. rodentium counts, concomitant with upregulation of Nrf2-related genes in colon tissue. Thus, PTS-PTSO mediates Nrf2-mediated antioxidant activity and modulates gut microbiota, which may protect the host against C. rodentium colonization. Our results provide further insight into how PTS-PTSO and related bioactive dietary compounds may reduce enteric infections.

Anti-Campylobacter Probiotics: Latest Mechanistic Insights

The Campylobacter genus is the leading cause of human gastroenteritis, with the consumption of contaminated poultry meat as the main route of infection. Probiotic bacteria, such as Lactobacillus, Bacillus, Escherichia coli Nissle, and Bifidobacterium species, have a great immunomodulatory capacity and exhibit antipathogenic effects through various molecular mechanisms. Reducing Campylobacter levels in livestock animals, such as poultry, will have a substantial benefit to humans as it will reduce disease transmissibility through the food chain. Moreover, probiotic-based strategies might attenuate intestinal inflammatory processes, which consequently reduce the severity of Campylobacter disease progression. At a molecular level, probiotics can also negatively impact on the functionality of various Campylobacter virulence and survival factors (e.g., adhesion, invasion), and on the associated colonization proteins involved in epithelial translocation. The current review describes recent in vitro, in vivo, and preclinical findings on probiotic therapies, aiming to reduce Campylobacter counts in poultry and reduce the pathogen's virulence in the avian and human host. Moreover, we focused in particular on probiotics with known anti-Campylobacter activity seeking to understand the biological mechanisms involved in their mode of action.

Apyrase-mediated amplification of secretory IgA promotes intestinal homeostasis

Secretory immunoglobulin A (SIgA) interaction with commensal bacteria conditions microbiota composition and function. However, mechanisms regulating reciprocal control of microbiota and SIgA are not defined. Bacteria-derived adenosine triphosphate (ATP) limits T follicular helper (Tfh) cells in the Peyer's patches (PPs) via P2X7 receptor (P2X7R) and thereby SIgA generation. Here we show that hydrolysis of extracellular ATP (eATP) by apyrase results in amplification of the SIgA repertoire. The enhanced breadth of SIgA in mice colonized with apyrase-releasing Escherichia coli influences topographical distribution of bacteria and expression of genes involved in metabolic versus immune functions in the intestinal epithelium. SIgA-mediated conditioning of bacteria and enterocyte function is reflected by differences in nutrient absorption in mice colonized with apyrase-expressing bacteria. Apyrase-induced SIgA improves intestinal homeostasis and attenuates barrier impairment and susceptibility to infection by enteric pathogens in antibiotic-induced dysbiosis. Therefore, amplification of SIgA by apyrase can be leveraged to restore intestinal fitness in dysbiotic conditions.

Antibiotic Treatment during Pregnancy Alters Offspring Gut Microbiota in a Sex-Dependent Manner

This study investigated the effect of antibiotics administered to pregnant dams on offspring gut microbiome composition and metabolic capabilities, and how these changes in the microbiota may influence their immune responses in both the periphery and the brain. We orally administered a broad-spectrum antibiotic (ABX) cocktail consisting of vancomycin 0.5 mg/mL, ampicillin 1 mg/mL, and neomycin 1 mg/mL to pregnant dams during late gestation through birth. Bacterial DNA was extracted from offspring fecal samples, and 16S ribosomal RNA gene was sequenced by Illumina, followed by analysis of gut microbiota composition and PICRUSt prediction. Serum and brain tissue cytokine levels were analyzed by Luminex. Our results indicate that the ABX-cocktail led to significant diversity and taxonomic changes to the offspring's gut microbiome. In addition, the predicted KEGG and MetaCyc pathways were significantly altered in the offspring. Finally, there were decreased innate inflammatory cytokines and chemokines and interleukin (IL)-17 seen in the brains of ABX-cocktail offspring in response to lipopolysaccharide (LPS) immune challenge. Our results suggest that maternal ABX can produce long-lasting effects on the gut microbiome and neuroimmune responses of offspring. These findings support the role of the early microbiome in the development of offspring gastrointestinal and immune systems.

Bacterial and Fungal Adaptations in Cecum and Distal Colon of Piglets Fed With Dairy-Based Milk Formula in Comparison With Human Milk

Exclusive breastfeeding is recommended to newborns during the first 6 months of life, whereas dairy-based infant formula is an alternative nutrition source offered to infants. Several studies demonstrated that breastfed infants have a different gut bacterial composition relative to formula-fed infants. In addition, animal models have shown that human milk (HM)–fed piglets had a distinct intestinal bacterial composition compared with milk formula (MF)–fed piglets. However, the gut fungal composition and the interactions with the bacterial community in breastfed compared with formula-fed infants remain to be investigated. In an attempt to evaluate such differences, we used an animal model to perform a shotgun metagenomics analysis on the cecal and distal colon contents of neonatal piglets fed with pasteurized HM or a dairy-based infant formula (MF) during the first 21 days of life. At postnatal day 21 (PND 21), a subset of piglets from each diet group (n = 11 per group) was euthanized. The remaining piglets in each group were weaned to a solid diet and euthanized at PND 51 (n = 13 per group). Large intestine contents (i.e., cecum and distal colon) were subjected to shotgun metagenomics analysis. The differential taxonomic composition of bacteria and fungi and the predicted functional gene profiling were evaluated. Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria are the most abundant bacterial phyla observed in piglets at PND 21 and PND 51. In the large intestine at PND 21 and PND 51, Proteobacteria phylum was significantly higher in MF-fed group, and species Burkholderiales bacterium of phyla was significantly higher in MF group relative to HM group. In addition, in HM group, several Lactobacillus spp. and Bacteroides spp. were higher relative to MF group in the large intestine at PND 21 and PND 51. Fungal genus Aspergillus was higher in MF, whereas Malassezia was lower relative to HM group. Persistent effects of the neonatal diets were observed at PND 51, where alpha- and beta-diversity differences were detected for bacterial and fungal species in the large intestine. Overall, our findings indicate that neonatal diet affects the large intestinal microbial community during the exclusive milk-feeding period, as well as after the introduction of the complementary food.

Genome Sequence and Assessment of Safety and Potential Probiotic Traits of Lactobacillus johnsonii CNCM I-4884

The probiotic strain Lactobacillus johnsonii CNCM I-4884 exhibits anti-Giardia activity in vitro and in vivo in a murine model of giardiasis. The aim of this study was the identification and characterization of the probiotic potential of L. johnsonii CNCM I-4884, as well as its safety assessment. This strain was originally classified as Lactobacillus gasseri based on 16S gene sequence analysis. Whole genome sequencing led to a reclassification as L. johnsonii. A genome-wide search for biosynthetic pathways revealed a high degree of auxotrophy, balanced by large transport and catabolic systems. The strain also exhibits tolerance to low pH and bile salts and shows strong bile salt hydrolase (BSH) activity. Sequencing results revealed the absence of antimicrobial resistance genes and other virulence factors. Phenotypic tests confirm that the strain is susceptible to a panel of 8 antibiotics of both human and animal relevance. Altogether, the in silico and in vitro results confirm that L. johnsonii CNCM I-4884 is well adapted to the gastrointestinal environment and could be safely used in probiotic formulations.

Immuno-modulatory effect of probiotic E. coli Nissle 1917 in polarized human colonic cells against Campylobacter jejuni infection

Campylobacter jejuni is among the leading causes of bacterial foodborne illness. Poultry is the major reservoir and source of human campylobacteriosis. Currently, there is no effective and practical method to decrease C. jejuni colonization in chickens or to reduce human infections. Additionally, antibiotic-resistant infections pose a serious public health concern; therefore, antibiotic-alternative approaches are needed to reduce transmission of C. jejuni including resistant bacteria from chickens to humans. Here, we evaluated the effect of E. coli Nissle 1917 (EcN) on innate responses of polarized HT-29 cells and consequently on C. jejuni 81176 infections in HT-29 cells. Pre-treatment of HT-29 cells with EcN for 4 h had a significant effect on the invasion of different C. jejuni strains (2 h post-infection) (P < .05) and no intracellular C. jejuni (24 h post-infection) were recovered. To further understand how EcN mediates its impact on C. jejuni's survival inside the cells, we used Human Antibacterial RT² Profiler^TM PCR arrays to profile gene expression in HT-29 cells after treatment with EcN with or without C. jejuni 81-176 infection. Our results suggest that pre-treatment of the HT-29 cells with EcN induced the anti-inflammatory cytokines and activated the anti-apoptotic Akt signaling which likely to protect the cells against the proinflammatory and apoptosis responses induced by C. jejuni. EcN also positively affected the expression of genes involved in cellular maintenance, growth, development, and proliferation. Further, EcN modulated the expression of genes involved in protective innate immunity, such as TLRs, ERK1/2, p38 MAPK, Ap1, JNK, IL1B, IL17A, and NF-κB signaling.

Identification of Gut Bacteria such as Lactobacillus johnsonii that Disseminate to Systemic Tissues of Wild Type and MyD88-/- Mice

In healthy hosts the gut microbiota is restricted to gut tissues by several barriers some of which require MyD88-dependent innate immune sensor pathways. Nevertheless, some gut taxa have been reported to disseminate to systemic tissues. However, the extent to which this normally occurs during homeostasis in healthy organisms is still unknown. In this study, we recovered viable gut bacteria from systemic tissues of healthy wild type (WT) and MyD88^-/- mice. Shotgun metagenomic-sequencing revealed a marked increase in the relative abundance of L. johnsonii in intestinal tissues of MyD88^-/- mice compared to WT mice. Lactobacillus johnsonii was detected most frequently from multiple systemic tissues and at higher levels in MyD88^-/- mice compared to WT mice. Viable L. johnsonii strains were recovered from different cell types sorted from intestinal and systemic tissues of WT and MyD88^-/- mice. L. johnsonii could persist in dendritic cells and may represent murine immunomodulatory endosymbionts.

Lactobacillus johnsonii Attenuates Citrobacter rodentium-Induced Colitis by Regulating Inflammatory Responses and Endoplasmic Reticulum Stress in Mice

BACKGROUND

Probiotics are beneficial in intestinal disorders. However, the benefits of Lactobacillus johnsonii in experimental colitis remain unknown.

OBJECTIVES

This study aimed to investigate the benefits of L. johnsonii against Citrobacter rodentium-induced colitis.

METHODS

Thirty-six 5-wk-old female C57BL/6J mice were randomly assigned to 3 groups (n = 12): control (Ctrl) group, Citrobacter rodentium treatment (CR) group (2 × 109 CFU C. rodentium), and Lactobacillus johnsonii and Citrobacter rodentium cotreatment (LJ + CR) group (109 CFU L. johnsonii with C. rodentium). Colon length, mucosal thickness, proinflammatory cytokine genes, and endoplasmic reticulum stress were tested.

RESULTS

The CR group had greater spleen weight, mucosal thickness, and Ki67+ cells (0.4-4.7 times), and a 23.8% shorter colon length than the Ctrl group, which in the LJ + CR group were 22.4%-77.6% lower and 30% greater than in the CR group, respectively. Relative to the Ctrl group, serum proinflammatory cytokines and immune cell infiltration were greater by 0.3-1.6 times and 6.2-8.8 times in the CR group, respectively; relative to the CR group, these were 19.9%-61.9% and 69.5%-84.2% lower in the LJ + CR group, respectively. The mRNA levels of lysozyme (Lyz) and regenerating islet-derived protein III were 22.7%-36.5% lower and 1.5-2.7 times greater in the CR group than in the Ctrl group, respectively, whereas they were 22.2%-25.7% greater and 57.2%-76.9% lower in the LJ + CR group than in the CR group, respectively. Cell apoptosis was 11.9 times greater in the CR group than in the Ctrl group, and 87.4% lower in the LJ + CR group than in the CR group. Consistently, the protein abundances of C/EBP homologous protein (CHOP), cleaved caspase 1 and 3, activating transcription factor 6α (ATF6A), and phospho-inositol-requiring enzyme 1α (P-IRE1A) were 0.3-2.1 times greater in the CR group and 31.1%-60.4% lower in the LJ + CR group. All these indexes did not differ between the Ctrl and LJ + CR groups, except for CD8+ T lymphocytes and CD11b+ and F4/80+ macrophages (1-1.5 times greater in LJ + CR) and mRNA concentration of Lyz2 (20.1% lower in LJ + CR).

CONCLUSIONS

L. johnsonii supplementation is a promising nutritional strategy for preventing C. rodentium-induced colitis in mice.

Serum Untargeted Metabolism Reveals the Mechanism of L. plantarum ZDY2013 in Alleviating Kidney Injury Induced by High-Salt Diet

A high-salt diet (HSD) is one of the key risk factors for hypertension and kidney injury. In this study, a HSD C57BL/6J mice model was established with 4% NaCl, and then different concentrations of Lactobacillus plantarum ZDY2013 were intragastrically administered for 2 weeks to alleviate HSD-induced renal injury. For the study, 16S rRNA gene sequencing, non-targeted metabonomics, real-time fluorescent quantitative PCR, and Masson’s staining were used to investigate the mechanism of L. plantarum ZDY2013 in alleviating renal damage. Results showed that HSD caused intestinal inflammation and changed the intestinal permeability of mice, disrupted the balance of intestinal flora, and increased toxic metabolites (tetrahydrocorticosteron (THB), 3-methyhistidine (3-MH), creatinine, urea, and L-kynurenine), resulting in serious kidney damage. Interestingly, L. plantarum ZDY2013 contributed to reconstructing the intestinal flora of mice by increasing the level of Lactobacillus and Bifidobacterium and decreasing that of Prevotella and Bacteroides. Moreover, the reconstructed intestinal microbiota significantly changed the concentration of the metabolites of hosts through metabolic pathways, including TCA cycle, ABC transport, purine metabolism, and histidine metabolism. The content of uremic toxins such as L-kynurenine, creatinine, and urea in the serum of mice was found to be decreased by L. plantarum ZDY2013, which resulted in renal injury alleviation. Our data suggest that L. plantarum ZDY2013 can indeed improve chronic kidney injury by regulating intestinal flora, strengthening the intestinal barrier, limiting inflammatory response, and reducing uremic toxins.

Lactobacillus johnsonii L531 Alleviates the Damage Caused by Salmonella Typhimurium via Inhibiting TLR4, NF-κB, and NLRP3 Inflammasome Signaling Pathways

Salmonella Typhimurium (S. Typhimurium) is an aggressive zoonotic pathogen that causes enteritis and diarrhea. Antibiotic therapy is still the primary method at present. However, the increasing emergence of multi-drug resistant bacteria weakens the therapeutic efficacy of antibiotics. Probiotics have been widely studied as an alternative antibiotic therapy. In this study, we established an IPEC-J2 cell model of S. Typhimurium infection, aiming to determine the protective effect of Lactobacillus johnsonii L531 (L. johnsonii L531) on S. Typhimurium infection. As our data showed, S. Typhimurium infection resulted in a robust inflammatory response demonstrated by promoted protein levels of the inflammatory-related pathway (TLR4, MyD88, p-IκBα, and p-p65), increased cytokine levels of IL-6, IL-1β, IL-18, and TNF-α, and activated the NLRP3 inflammasome via promoting its assembly. However, L. johnsonii L531 pre-incubation inhibited the activation of the above inflammatory signaling pathways and reduced the expression levels of pro-inflammatory cytokines. In addition, L. johnsonii L531 alleviated the damage of S. Typhimurium to tight junctions ZO-1, Occludin, and Claudin-1. In summary, our findings suggested that L. johnsonii L531 alleviated S. Typhimurium-induced tight junction injury by inhibiting the TLR4/NF-κB/NLRP3 inflammasome signaling pathway.

Activation of Proneuronal Transcription Factor Ascl1 in Maternal Liver Ensures a Healthy Pregnancy

BACKGROUND & AIMS

Maternal liver shows robust adaptations to pregnancy to accommodate the metabolic needs of the developing and growing placenta and fetus by largely unknown mechanisms. We found that Ascl1, a gene encoding a basic helix-loop-helix transcription factor essential for neuronal development, is highly activated in maternal hepatocytes during the second half of gestation in mice.

METHODS

To investigate whether and how Ascl1 plays a pregnancy-dependent role, we deleted the Ascl1 gene specifically in maternal hepatocytes from midgestation until term.

RESULTS

As a result, we identified multiple Ascl1-dependent phenotypes. Maternal livers lacking Ascl1 showed aberrant hepatocyte structure, increased hepatocyte proliferation, enlarged hepatocyte size, reduced albumin production, and increased release of liver enzymes, indicating maternal liver dysfunction. Simultaneously, maternal pancreas and spleen and the placenta showed marked overgrowth; and the maternal ceca microbiome showed alterations in relative abundance of several bacterial subpopulations. Moreover, litters born from maternal hepatic Ascl1-deficient dams experienced abnormal postnatal growth after weaning, implying an adverse pregnancy outcome. Mechanistically, we found that maternal hepatocytes deficient for Ascl1 showed robust activation of insulin-like growth factor 2 expression, which may contribute to the Ascl1-dependent phenotypes widespread in maternal and uteroplacental compartments.

CONCLUSIONS

In summary, we show that maternal liver, via activating Ascl1 expression, modulates the adaptations of maternal organs and the growth of the placenta to maintain a healthy pregnancy. Our studies show that Ascl1 is a novel and critical regulator of the physiology of pregnancy.

Treatment with the Probiotic Product Aviguard® Alleviates Inflammatory Responses during Campylobacter jejuni-Induced Acute Enterocolitis in Mice

Prevalences of Campylobacter (C.) jejuni infections are progressively rising globally. Given that probiotic feed additives, such as the commercial product Aviguard^®, have been shown to be effective in reducing enteropathogens, such as Salmonella, in vertebrates, including livestock, we assessed potential anti-pathogenic and immune-modulatory properties of Aviguard^® during acute C. jejuni-induced murine enterocolitis. Therefore, microbiota-depleted IL-10^−/− mice were infected with C. jejuni strain 81-176 by gavage and orally treated with Aviguard^® or placebo from day 2 to 4 post-infection. The applied probiotic bacteria could be rescued from the intestinal tract of treated mice, but with lower obligate anaerobic bacterial counts in C. jejuni-infected as compared to non-infected mice. Whereas comparable gastrointestinal pathogen loads could be detected in both groups until day 6 post-infection, Aviguard^® treatment resulted in improved clinical outcome and attenuated apoptotic cell responses in infected large intestines during acute campylobacteriosis. Furthermore, less distinct pro-inflammatory immune responses could be observed not only in the intestinal tract, but also in extra-intestinal compartments on day 6 post-infection. In conclusion, we show here for the first time that Aviguard^® exerts potent disease-alleviating effects in acute C. jejuni-induced murine enterocolitis and might be a promising probiotic treatment option for severe campylobacteriosis in humans.

Survey of Pathogen-Lowering and Immuno-Modulatory Effects Upon Treatment of Campylobacter coli-Infected Secondary Abiotic IL-10-/- Mice with the Probiotic Formulation Aviguard®

The prevalence of infections with the zoonotic enteritis pathogen Campylobacter coli is increasing. Probiotic formulations constitute promising antibiotic-independent approaches to reduce intestinal pathogen loads and modulate pathogen-induced immune responses in the infected human host, resulting in acute campylobacteriosis and post-infectious sequelae. Here, we address potential antipathogenic and immuno-modulatory effects of the commercial product Aviguard^® during experimental campylobacteriosis. Secondary abiotic IL-10^-/- mice were infected with a C. coli patient isolate on days 0 and 1, followed by oral Aviguard^® treatment on days 2, 3 and 4. Until day 6 post-infection, Aviguard^® treatment could lower the pathogen burdens within the proximal but not the distal intestinal tract. In contrast, the probiotic bacteria had sufficiently established in the intestines with lower fecal loads of obligate anaerobic species in C. coli-infected as compared to uninfected mice following Aviguard^® treatment. Aviguard^® application did not result in alleviated clinical signs, histopathological or apoptotic changes in the colon of infected IL-10^-/- mice, whereas, however, Aviguard^® treatment could dampen pathogen-induced innate and adaptive immune responses in the colon, accompanied by less distinct intestinal proinflammatory cytokine secretion. In conclusion, Aviguard^® constitutes a promising probiotic compound to alleviate enteropathogen-induced proinflammatory immune responses during human campylobacteriosis.

Spinal Cord Injury Changes the Structure and Functional Potential of Gut Bacterial and Viral Communities

Emerging data indicate that gut dysbiosis contributes to many human diseases, including several comorbidities that develop after traumatic spinal cord injury (SCI). To date, all analyses of SCI-induced gut dysbiosis have used 16S rRNA amplicon sequencing. This technique has several limitations, including being susceptible to taxonomic "blind spots," primer bias, and an inability to profile microbiota functions or identify viruses. Here, SCI-induced gut dysbiosis was assessed by applying genome- and gene-resolved metagenomic analysis of murine stool samples collected 21 days after an experimental SCI at the 4th thoracic spine (T4) or 10th thoracic spine (T10) spinal level. These distinct injuries partially (T10) or completely (T4) abolish sympathetic tone in the gut. Among bacteria, 105 medium- to high-quality metagenome-assembled genomes (MAGs) were recovered, with most (n = 96) representing new bacterial species. Read mapping revealed that after SCI, the relative abundance of beneficial commensals (Lactobacillus johnsonii and CAG-1031 spp.) decreased, while potentially pathogenic bacteria (Weissella cibaria, Lactococcus lactis _A, Bacteroides thetaiotaomicron) increased. Functionally, microbial genes encoding proteins for tryptophan, vitamin B6, and folate biosynthesis, essential pathways for central nervous system function, were reduced after SCI. Among viruses, 1,028 mostly novel viral populations were recovered, expanding known murine gut viral species sequence space ∼3-fold compared to that of public databases. Phages of beneficial commensal hosts (CAG-1031, Lactobacillus, and Turicibacter) decreased, while phages of pathogenic hosts (Weissella, Lactococcus, and class Clostridia) increased after SCI. Although the microbiomes and viromes were changed in all SCI mice, some of these changes varied as a function of spinal injury level, implicating loss of sympathetic tone as a mechanism underlying gut dysbiosis.IMPORTANCE To our knowledge, this is the first article to apply metagenomics to characterize changes in gut microbial population dynamics caused by a clinically relevant model of central nervous system (CNS) trauma. It also utilizes the most current approaches in genome-resolved metagenomics and viromics to maximize the biological inferences that can be made from these data. Overall, this article highlights the importance of autonomic nervous system regulation of a distal organ (gut) and its microbiome inhabitants after traumatic spinal cord injury (SCI). By providing information on taxonomy, function, and viruses, metagenomic data may better predict how SCI-induced gut dysbiosis influences systemic and neurological outcomes after SCI.

Evaluation of the orally administered calcium alginate aerogel on the changes of gut microbiota and hepatic and renal function of Wistar rats

The present study evaluates the effect of calcium alginate aerogel as a potential drug carrier, on the liver and kidney functions, and on the gut microbiota of Wistar rats. The studied alginate aerogel was prepared in the form of nanoparticles using the jet cutting technique, and they were characterized in terms of specific surface areas, outer morphology and particle size distribution. For the in vivo study, calcium alginate aerogel was administered orally, and liver and kidney functions were tested for one week and for four weeks in two distinct studies. During the short-term in vivo study, feces samples were collected for bacterial DNA extraction followed by 16S rRNA gene sequencing analyses to detect changes in gut microbiota. Results showed that the prepared alginate aerogel has an average BET-specific surface area of around 540 m²/g, with a pore volume of 7.4 cc/g, and pore width of 30–50 nm. The in vivo study revealed that the levels of the studied kidney and liver enzymes didn’t exceed the highest level of the normal range. The study of gut microbiota showed different patterns; certain groups of bacteria, such as Clostridia and Bacteriodia, increased during the aerogels regime and continued to increase after the aerogel was stopped. While other groups such as Erysipelotrichia, and Candidatus saccharibacteria increased during aerogels treatment, and then decreased again after one month. Members of the Bacilli class showed a unique trend, that is, after being the most abundant group (63%) at time 0, their relative abundance decreased dramatically until it reached < 5%; which was the case even after stopping the aerogel treatment.

Harnessing the potential of Lactobacillus species for therapeutic delivery at the lumenal-mucosal interface

Lactobacillus species have been studied for over 30 years in their role as commensal organisms in the human gut. Recently there has been a surge of interest in their abilities to natively and recombinantly stimulate immune activities, and studies have identified strains and novel molecules that convey particular advantages for applications as both immune adjuvants and immunomodulators. In this review, we discuss the recent advances in Lactobacillus-related activity at the gut/microbiota interface, the efforts to probe the boundaries of the direct and indirect therapeutic potential of these bacteria, and highlight the continued interest in harnessing the native capacity for the production of biogenic compounds shown to influence nervous system activity. Taken together, these aspects underscore Lactobacillus species as versatile therapeutic delivery vehicles capable of effector production at the lumenal-mucosal interface, and further establish a foundation of efficacy upon which future engineered strains can expand.

Toll-Like Receptor-4 Is Involved in Mediating Intestinal and Extra-Intestinal Inflammation in Campylobacter coli-Infected Secondary Abiotic IL-10-/- Mice

Human Campylobacter infections are emerging worldwide and constitute significant health burdens. We recently showed that the immunopathological sequelae in Campylobacter jejuni-infected mice were due to Toll-like receptor (TLR)-4 dependent immune responses induced by bacterial lipooligosaccharide (LOS). Information regarding the molecular mechanisms underlying Campylobacter coli-host interactions are scarce, however. Therefore, we analyzed C. coli-induced campylobacteriosis in secondary abiotic IL-10^−/− mice with and without TLR4. Mice were infected perorally with a human C. coli isolate or with a murine commensal Escherichia coli as apathogenic, non-invasive control. Independent from TLR4, C. coli and E. coli stably colonized the gastrointestinal tract, but only C. coli induced clinical signs of campylobacteriosis. TLR4^−/− IL-10^−/− mice, however, displayed less frequently fecal blood and less distinct histopathological and apoptotic sequelae in the colon versus IL-10^−/− counterparts on day 28 following C. coli infection. Furthermore, C. coli-induced colonic immune cell responses were less pronounced in TLR4^−/− IL-10^−/− as compared to IL-10^−/− mice and accompanied by lower pro-inflammatory mediator concentrations in the intestines and the liver of the former versus the latter. In conclusion, our study provides evidence that TLR4 is involved in mediating C. coli-LOS-induced immune responses in intestinal and extra-intestinal compartments during murine campylobacteriosis.

Changes in the diversity and composition of gut microbiota in pigeon squabs infected with Trichomonas gallinae

Pigeons, as the only altricial birds in poultry, are the primary Trichomonas gallinae (T. gallinae) host. To study the effects of T. gallinae infection on gut microbiota, we compared the microbiota diversity and composition in gastrointestinal (GI) tracts of pigeons at the age of 14 and 21 day with different degrees of T. gallinae infection. Thirty-six nestling pigeons were divided into three groups: the healthy group, low-grade and high-grade trichomonosis group. Then, the crop, small intestine and rectum contents were obtained for sequencing of the 16S rRNA gene V3–V4 hypervariable region. The results showed that the microbiota diversity was higher in crop than in small intestine and rectum, and the abundance of Lactobacillus genus was dominant in small intestine and rectum of healthy pigeons at 21 days. T. gallinae infection decreased the microbiota richness in crop at 14 days. The abundance of the Firmicutes phylum and Lactobacillus genus in small intestine of birds at 21 days were decreased by infection, however the abundances of Proteobacteria phylum and Enterococcus, Atopobium, Roseburia, Aeriscardovia and Peptostreptococcus genus increased. The above results indicated that crop had the highest microbiota diversity among GI tract of pigeons, and the gut microbiota diversity and composition of pigeon squabs were altered by T. gallinae infection.

Lactobacillus johnsonii L531 Ameliorates Escherichia coli-Induced Cell Damage via Inhibiting NLRP3 Inflammasome Activity and Promoting ATG5/ATG16L1-Mediated Autophagy in Porcine Mammary Epithelial Cells

Escherichia coli (E. coli), a main mastitis-causing pathogen in sows, leads to mammary tissue damage. Here, we explored the effects of Lactobacillus johnsonii L531 on attenuating E. coli-induced inflammatory damage in porcine mammary epithelial cells (PMECs). L. johnsonii L531 pretreatment reduced E. coli adhesion to PMECs by competitive exclusion and the production of inhibitory factors and decreased E. coli-induced destruction of cellular morphology and ultrastructure. E. coli induced activation of NLRP3 inflammasome associated with increased expression of NLRP3, ASC, and cleaved caspase-1, however, L. johnsonii L531 inhibited E. coli-induced activation of NLRP3 inflammasome. Up-regulation of interleukin (Il)-1β, Il-6, Il-8, Il-18, tumor necrosis factor alpha, and chemokine Cxcl2 expression after E. coli infection was attenuated by L. johnsonii L531. E. coli infection inhibited autophagy, whereas L. johnsonii L531 reversed the inhibitory effect of E. coli on autophagy by decreasing the expression of autophagic receptor SQSTM1/p62 and increasing the expression of autophagy-related proteins ATG5, ATG16L1, and light chain 3 protein by Western blotting analysis. Our findings suggest that L. johnsonii L531 pretreatment restricts NLRP3 inflammasome activity and induces autophagy through promoting ATG5/ATG16L1-mediated autophagy, thereby protecting against E. coli-induced inflammation and cell damage in PMECs.

The conundrum of colonization resistance against Campylobacter reloaded: The gut microbota composition in conventional mice does not prevent from Campylobacter coli infection

The physiological colonization resistance exerted by the murine gut microbiota prevents conventional mice from Campylobacter jejuni infection. In the present study we addressed whether this also held true for Campylobacter coli. Following peroral application, C. coli as opposed to C.jejuni could stably establish within the gastrointestinal tract of conventionally colonized mice until 3 weeks post-challenge. Neither before nor after either Campylobacter application any changes in the gut microbiota composition could be observed. C. coli, but not C. jejuni challenge was associated with pronounced regenerative, but not apoptotic responses in colonic epithelia. At day 21 following C. coli versus C. jejuni application mice exhibited higher numbers of adaptive immune cells including T-lymphocytes and regulatory T-cells in the colonic mucosa and lamina propria that were accompanied by higher large intestinal interferon-γ (IFN-γ) concentrations in the former versus the latter but comparable to naive levels. Campylobacter application resulted in decreased splenic IFN-γ, tumor necrosis factor-α (TNF-α), and IL-6 concentrations, whereas IL-12p70 secretion was increased in the spleens at day 21 following C. coli application only. In either Campylobacter cohort decreased IL-10 concentrations could be measured in splenic and serum samples. In conclusion, the commensal gut microbiota prevents mice from C. jejuni, but not C. coli infection.

Intestinal microbiota characteristics of mice treated with Folium senna decoction gavage combined with restraint and tail pinch stress

To investigate the characteristics of the intestinal microbiota of mice treated with Folium senna decoction gavage combined with restraint and tail pinch stress. Ten healthy male Kunming mice were chosen and randomly divided into control group and model group, with five mice in each group. Mice in the control group were raised regularly, while mice in the model group were treated by feeding with Folium senna decoction, restraint in a constraint tube and tail pinch with a clip for 7 days. Intestinal contents from the jejunum to ileum were collected, and DNA was extracted from each mouse. The characteristics of the intestinal microbial species were analysed by PacBio Sequel-based 16S rRNA sequencing. Result showed that alpha diversity indices in the model group were higher than those in the control group, and the Simpson index differed significantly (P < 0.05). Based on the composition and abundances of species, there were differences between the control group and model group at the species level, but these differences were not significant (P > 0.05). In the control group, Candidatus arthromitus sp. SFB-mouse and Lactobacillus johnsonii were the dominant species. In the model group, Staphylococcus lentus, Lactobacillus johnsonii, Candidatus arthromitus sp. SFB-mouse and Lactobacillus murinus were included. Furthermore, LEfSe analysis showed that the relative abundances of Escherichia sp. BBDP27, Helicobacter ganmani, Bacteroides vulgatus and Lactobacillus intestinalis in the model group were higher than those in the control group (P < 0.05 or P < 0.01). In conclusion, Folium senna decoction gavage combined with restraint and tail pinch stress increased the intestinal microbiota diversity. Strains associated with intestinal diseases, including Bacteroides vulgatus, Helicobacter ganmani, Staphylococcus lentus and Lactobacillus murinus, were significantly enriched, while strains beneficial to health, such as Candidatus arthromitus sp. SFB-mouse and Lactobacillus johnsonii, were significantly depleted.

Standardized Natural Citrus Extract dietary supplementation influences sows’ microbiota, welfare, and preweaning piglets’ performances in commercial rearing conditions

We investigated the effect of the Standardized Natural Citrus Extract (SNCE; Nor-Spice AB, Nor-Feed SAS, France) on the microbiota of the sows and on the weight gain of their piglets. Fifty sows were randomly divided into two groups: a control group (23 sows) with a standard diet and a SNCE group (27 sows) with a standard diet supplemented with 2,500 ppm of SNCE. Supplementation occurred 10 d before and 5 d after farrowing. Fecal samples from 16 sows (8 randomly selected sows of each dietary treatment) were collected for the fecal microbiota analysis 5 d after farrowing. The supplementation of SNCE increases the amount of cultivable Lactobacillus threefold in vitro. Microbial DNA was extracted from the fecal samples for sequencing of the 16S rRNA gene. The SNCE, which affected the microbiota as a discriminant analysis, was able to separate the microbial communities of the eight sows that received SNCE from the three control sows with 21 Operational Taxonomic Units (area under the ROC curve = 96%). SNCE also reduced the interval between farrowing and the first dejection of the sow and increased their feed intake (P-value < 0.05). Furthermore, feeding the sows with SNCE improved the weight gain of the piglets in the first week of life. These results show that SNCE supplementation allows to enhance zootechnical performances of peripartum’ sows, possibly due to the modulation of the microbiota transmitted to the piglets.

Friend or foe? Lactobacillus in the context of autoimmune disease

Over the last decade, the interplay between the gut microbiota, the consortium of intestinal microbes that colonizes intestinal mucosal barriers, and its host immune system has been increasingly better understood. Disruption of the delicate balance between beneficial and pathogenic commensals, known as dysbiosis, contributes to a variety of chronic immunologic and metabolic diseases. Complicating this paradigm are bacterial strains that can operate paradoxically both as instigators and attenuators of inflammatory responses, depending on host background. Here, we review the role of several strains in the genus Lactobacillus within the context of autoimmune and other chronic disorders with a predominant focus on L. reuteri. While strains within this species have been shown to provide immune health benefits, they have also been demonstrated to act as a pathobiont in autoimmune-prone hosts. Beneficial functions in healthy hosts include competing with pathogenic microbes, promoting regulatory T cell development, and protecting the integrity of the gut barrier. On the other hand, certain strains can also break through a dysfunctional gut barrier, colonize internal tissues such as the spleen or liver and promote inflammatory responses in host tissues that lead to autoimmune disease. This review summarizes the manifold roles that these commensals play in the context of health and disease.

Bifidobacterium longum subsp. infantis ATCC 15697 and Goat Milk Oligosaccharides Show Synergism In Vitro as Anti-Infectives against Campylobacter jejuni

Bifidobacteria are known to inhibit, compete with and displace the adhesion of pathogens to human intestinal cells. Previously, we demonstrated that goat milk oligosaccharides (GMO) increased the attachment of Bifidobacterium longum subsp. infantis ATCC 15697 to intestinal cells in vitro. In this study, we aimed to exploit this effect as a mechanism for inhibiting pathogen association with intestinal cells. We examined the synergistic effect of GMO-treated B. infantis on preventing the attachment of a highly invasive strain of Campylobacter jejuni to intestinal HT-29 cells. The combination decreased the adherence of C. jejuni to the HT-29 cells by an average of 42% compared to the control (non-GMO treated B. infantis). Increasing the incubation time of the GMO with the Bifidobacterium strain resulted in the strain metabolizing the GMO, correlating with a subsequent 104% increase in growth over a 24 h period when compared to the control. Metabolite analysis in the 24 h period also revealed increased production of acetate, lactate, formate and ethanol by GMO-treated B. infantis. Statistically significant changes in the GMO profile were also demonstrated over the 24 h period, indicating that the strain was digesting certain structures within the pool such as lactose, lacto-N-neotetraose, lacto-N-neohexaose 3′-sialyllactose, 6′-sialyllactose, sialyllacto-N-neotetraose c and disialyllactose. It may be that early exposure to GMO modulates the adhesion of B. infantis while carbohydrate utilisation becomes more important after the bacteria have transiently colonised the host cells in adequate numbers. This study builds a strong case for the use of synbiotics that incorporate oligosaccharides sourced from goat′s milk and probiotic bifidobacteria in functional foods, particularly considering the growing popularity of formulas based on goat milk.

Vitamin C alleviates acute enterocolitis in Campylobacter jejuni infected mice

Human foodborne infections with the zoonotic pathogen Campylobacter jejuni are on the rise and constitute a significant socioeconomic burden worldwide. The health-beneficial, particularly anti-inflammatory effects of vitamin C (ascorbate) are well known. In our preclinical intervention study, we assessed potential anti-pathogenic and immunomodulatory effects of ascorbate in C. jejuni-infected secondary abiotic IL-10-/- mice developing acute campylobacteriosis similar to humans. Starting 4 days prior peroral C. jejuni-infection, mice received synthetic ascorbate via the drinking water until the end of the experiment. At day 6 post-infection, ascorbate-treated mice harbored slightly lower colonic pathogen loads and suffered from less severe C. jejuni-induced enterocolitis as compared to placebo control animals. Ascorbate treatment did not only alleviate macroscopic sequelae of infection, but also dampened apoptotic and inflammatory immune cell responses in the intestines that were accompanied by less pronounced pro-inflammatory cytokine secretion. Remarkably, the anti-inflammatory effects of ascorbate pretreatment in C. jejuni-infected mice were not restricted to the intestinal tract but could also be observed in extra-intestinal compartments including liver, kidneys and lungs. In conclusion, due to the potent anti-inflammatory effects observed in the clinical murine C. jejuni-infection model, ascorbate constitutes a promising novel option for prophylaxis and treatment of acute campylobacteriosis.

Lactobacillus Protects Against S. Typhimurium-Induced Intestinal Inflammation by Determining the Fate of Epithelial Proliferation and Differentiation

SCOPE

The influence of the intestinal microbiota, such as Lactobacillus, on the intestinal mucosa, particularly intestinal stem cells, remains incompletely understood. In this study, mice and intestinal organoids are used to explore the regulatory effect of Lactobacillus on the proliferation and differentiation of intestinal epithelial cells.

METHODS AND RESULTS

This study demonstrates that S. typhimurium causes intestinal epithelial damage and affected growth of intestinal organoids. S. typhimurium also colonizes the intestine and then causes pathological changes to the intestinal epithelium, intestinal inflammation, and even death. However, L. acidophilus alleviates damage to intestinal organoids, increases the survival ratio of mice infected with S. typhimurium, and reduces tumor necrosis factor-α (TNF-α) secretion. Moreover, L. acidophilus affects the differentiation of epithelial cells through inhibition of the excessive expansion of goblet cells and Paneth cells induced by S. typhimurium to avoid over-exhaustion. Finally, it is also demonstrated that L. acidophilus ameliorates overactivation of Wnt/β-catenin pathway by Salmonella, depending on the contact with toll-like receptor 2 (TLR2), to affect the proliferation of the intestinal epithelium.

CONCLUSIONS

This study demonstrates that L. acidophilus protects the intestinal mucosa against S. typhimurium infection through not only the inhibition of pathogen invasion but also determination of the fate of the intestinal epithelium.

Lactobacillus johnsonii L531 ameliorates enteritis via elimination of damaged mitochondria and suppression of SQSTM1-dependent mitophagy in a Salmonella infantis model of piglet diarrhea

Newly weaned piglets challenged with Salmonella infantis were particularly susceptible, whereas oral preadministration of Lactobacillus johnsonii L531 alleviated enteritis and promoted intestinal secretory IgA production. Salmonella infantis-induced activation of NLRC4 and NLRP3 inflammasomes and (nuclear factor kappa B) NF-κB signaling in the small intestine was also inhibited by L. johnsonii L531 pretreatment, thus limiting inflammation. An IPEC-J2 cell model of S. infantis infection yielded similar results. Salmonella infantis infection also resulted in mitochondrial damage and impaired mitophagy in the ileum and IPEC-J2 cells, as demonstrated by immunofluorescence colocalization of mitochondria with microtubule-binding protein light chain 3 (LC3) and high expression of autophagy-related proteins PTEN-induced putative kinase 1 (PINK1), sequestosome 1 (SQSTM1/p62), optineurin (OPTN), and LC3 by Western blotting analysis. However, L. johnsonii L531 pretreatment reduced both the extent of mitochondrial damage and autophagy-related protein expression. Our findings suggest that the amelioration of S. infantis-associated enteritis by L. johnsonii L531 is associated with regulation of NLRC4 and NLRP3 inflammasomes and NF-κB signaling pathway activation and suppression of mitochondrial damage. Amelioration of impaired mitophagy by L. johnsonii L531 could involve eliminating damaged mitochondria and regulating S. infantis-induced activation of the NF-κB-SQSTM1mitophagy signaling pathway in host cells to prevent the further mitochondrial damage and S. infantis dissemination.

Murine fecal microbiota transplantation lowers gastrointestinal pathogen loads and dampens pro-inflammatory immune responses in Campylobacter jejuni infected secondary abiotic mice

Conventional mice are protected from Campylobacter jejuni infection by the murine host-specific gut microbiota composition. We here addressed whether peroral fecal microbiota transplantation (FMT) might be an antibiotics-independent option to lower even high gastrointestinal C. jejuni loads in the infected vertebrate host. To address this, secondary abiotic mice were generated by broad-spectrum antibiotic treatment and perorally infected with C. jejuni by gavage. One week later, mice were stably colonized with more than 109 C. jejuni and subjected to peroral FMT from murine donors on three consecutive days. Two weeks post-intervention, gastrointestinal C. jejuni loads were up to 7.5 orders of magnitude lower following murine FMT versus mock challenge. Remarkably, FMT reversed C. jejuni induced colonic epithelial apoptosis, but enhanced proliferative and regenerative responses in the colon thereby counteracting pathogenic cell damage. Furthermore, FMT dampened both, innate and adaptive immune cell responses in the large intestines upon C. jejuni infection that were accompanied by less C. jejuni-induced colonic nitric oxide secretion. Our study provides strong evidence that novel probiotic formulations developed as alternative option to FMT in severe intestinal inflammatory morbidities including Clostridoides difficile infection might be effective to treat campylobacteriosis and lower pathogen loads in colonized vertebrates including farm animals.

Gastric acid inhibitor aggravates indomethacin-induced small intestinal injury via reducing Lactobacillus johnsonii

Proton pump inhibitors (PPIs) alter the composition of the intestinal microbiome, exacerbating indomethacin (IND)-induced small intestinal damage. Vonoprazan fumarate inhibits gastric acid secretion using a different mechanism from PPIs. We investigated the effects of both drugs on the intestinal microbiome and IND-induced small intestinal damage. We sought to clarify whether PPI-induced dysbiosis and worsening of the damage were due to a specific drug class effect of PPIs. Rabeprazole administration increased operational taxonomic unit numbers in the small intestines of C57BL/6 J mice, whereas the difference was not significant in the vonoprazan-treated group but exhibited a trend. Permutational multivariate analysis of variance of the unweighted UniFrac distances showed significant differences between vehicle- and vonoprazan- or rabeprazole-treated groups. L. johnsonii was the predominant microbial species, and the population ratio decreased after vonoprazan and rabeprazole administration. The vonoprazan- and rabeprazole-treated groups showed increased IND-induced damage. This high sensitivity to IND-induced damage was evaluated by transplantation with contents from the small intestine of mice treated with either vonoprazan or rabeprazole. Supplementation of L. johnsonii orally in mice treated with rabeprazole and vonoprazan prevented the increase in IND-induced small intestinal damage. In conclusion, both rabeprazole and vonoprazan aggravated NSAID-induced small intestinal injury by reducing the population of L. johnsonii in the small intestine via suppressing gastric acid secretion.

Murine Fecal Microbiota Transplantation Alleviates Intestinal and Systemic Immune Responses in Campylobacter jejuni Infected Mice Harboring a Human Gut Microbiota

Human campylobacteriosis constitutes a zoonotic food-borne disease and a progressively rising health burden of significant socioeconomic impact. We have recently shown that conventional mice are protected from Campylobacter jejuni infection, which was not the case for human microbiota associated (hma) mice indicating that the host-specific gut microbiota composition primarily determines susceptibility to or resistance against C. jejuni infection. In our present preclinical intervention study we addressed whether gut microbiota changes in stably C. jejuni infected hma mice following murine fecal microbiota transplantation (mFMT) could alleviate pathogen-induced immune responses. To accomplish this, secondary abiotic C57BL/6 mice were generated by broad-spectrum antibiotic treatment, perorally reassociated with a complex human gut microbiota and challenged with C. jejuni by gavage. Seven days later C. jejuni infected hma mice were subjected to peroral mFMT on 3 consecutive days. Within a week post-mFMT fecal pathogenic burdens had decreased by two orders of magnitude, whereas distinct changes in the gut microbiota composition with elevated numbers of lactobacilli and bifidobacteria could be assessed. In addition, mFMT resulted in less C. jejuni induced apoptotic responses in colonic epithelia, reduced numbers of macrophages and monocytes as well as of T lymphocytes in the large intestinal mucosa and lamina propria and in less distinct intestinal pro-inflammatory cytokine secretion as compared to mock challenge. Strikingly, inflammation dampening effects of mFMT were not restricted to the intestinal tract, but could also be observed systemically as indicated by elevated serum concentrations of pro-inflammatory cytokines such as TNF-α, IL-12p70, and IL-6 in C. jejuni infected hma mice of the mock, but not the mFMT cohort. In conclusion, our preclinical mFMT intervention study provides evidence that changes in the gut microbiota composition which might be achieved by pre- or probiotic formulations may effectively lower intestinal C. jejuni loads, dampen both, pathogen-induced intestinal and systemic inflammatory sequelae and may represent a useful tool to treat continuous shedding of C. jejuni by asymptomatic carriers which is critical in the context of food production, hospitalization and immunosuppression.

Vitamin D in Acute Campylobacteriosis-Results From an Intervention Study Applying a Clinical Campylobacter jejuni Induced Enterocolitis Model

Human Campylobacter infections are progressively rising and of high socioeconomic impact. In the present preclinical intervention study we investigated anti-pathogenic, immuno-modulatory, and intestinal epithelial barrier preserving properties of vitamin D applying an acute campylobacteriosis model. Therefore, secondary abiotic IL-10^−/− mice were perorally treated with synthetic 25-OH-cholecalciferol starting 4 days before peroral Campylobacter jejuni infection. Whereas, 25-OH-cholecalciferol application did not affect gastrointestinal pathogen loads, 25-OH-cholecalciferol treated mice suffered less frequently from diarrhea in the midst of infection as compared to placebo control mice. Moreover, 25-OH-cholecalciferol application dampened C. jejuni induced apoptotic cell responses in colonic epithelia and promoted cell-regenerative measures. At day 6 post-infection, 25-OH-cholecalciferol treated mice displayed lower numbers of colonic innate and adaptive immune cell populations as compared to placebo controls that were accompanied by lower intestinal concentrations of pro-inflammatory mediators including IL-6, MCP1, and IFN-γ. Remarkably, as compared to placebo application synthetic 25-OH-cholecalciferol treatment of C. jejuni infected mice resulted in lower cumulative translocation rates of viable pathogens from the inflamed intestines to extra-intestinal including systemic compartments such as the kidneys and spleen, respectively, which was accompanied by less compromised colonic epithelial barrier function in the 25-OH-cholecalciferol as compared to the placebo cohort. In conclusion, our preclinical intervention study provides evidence that peroral synthetic 25-OH-cholecalciferol application exerts inflammation-dampening effects during acute campylobacteriosis.

Influence of dietary supplementation with Bacillus velezensis on intestinal microbial diversity of mice

Yaks are an aboriginal breed of the Qinghai-Tibet plateau (3000 m), which are highly adaptable to cold and hypoxic environments. It is noticed that hypoxia and hypothermia can induce changes in intestinal microbial structure in animals. Increasing evidences suggested that probiotics supplementation can improve the balance of gut microbiota of animals. However, so far, very few studies have emphasized on the probiotics isolated from yaks in the Qinghai-Tibet Plateau. Therefore, a potential probiotic strain Bacillus velezensis was isolated from yaks. In the present study, a total of 18 Kunming mice (15-18 g) were equally distributed into two groups; control and probiotic treated groups (1 × 10⁹ CFU/day). During the experimental period, all the mice from both groups were given standard normal diet ad libitum. At the end of the experiment, mice were euthanized and the intestines (duodenum, jejunum, ileum, and cecum) were removed for high-throughput sequencing. The results demonstrated that Bacillus velezensis supplementation showed beneficial effects on the gut microbiota of mice. Specifically, Bacillus velezensis supplementation increased the population of Lactobacillus and Ruminococcus in the duodenum, and Candidatus Arthromitus in the jejunum. Additionally, Acinetobacter in the duodenum and Helicobacter in the cecum were decreased after feeding Bacillus velezensis. Altogether, these findings suggested that Bacillus velezensis isolated from Tibetan yaks can improve gut microbiota of mice.

Comprehensive Kinetic Survey of Intestinal, Extra-Intestinal and Systemic Sequelae of Murine Ileitis Following Peroral Low-Dose Toxoplasma gondii Infection

We have recently shown that following peroral low-dose Toxoplasma gondii infection susceptible mice develop subacute ileitis within 10 days. Data regarding long-term intestinal and extra-intestinal sequelae of infection are scarce, however. We therefore challenged conventional C57BL/6 mice with one cyst of T. gondii ME49 strain by gavage and performed a comprehensive immunopathological survey 10, 36, and 57 days later. As early as 10 days post-infection, mice were suffering from subacute ileitis as indicated by mild-to-moderate histopathological changes of the ileal mucosa. Furthermore, numbers of apoptotic and proliferating/regenerating epithelial cells as well as of T and B lymphocytes in the mucosa and lamina propria of the ileum were highest at day 10 post-infection, but declined thereafter, and were accompanied by enhanced pro-inflammatory mediator secretion in ileum, colon and mesenteric lymph nodes that was most pronounced during the early phase of infection. In addition, subacute ileitis was accompanied by distinct shifts in the commensal gut microbiota composition in the small intestines. Remarkably, immunopathological sequelae of T. gondii infection were not restricted to the intestines, but could also be observed in extra-intestinal tissues including the liver, kidneys, lungs, heart and strikingly, in systemic compartments that were most prominent at day 10 post-infection. We conclude that the here provided long-term kinetic survey of immunopathological sequalae following peroral low-dose T. gondii infection provides valuable corner stones for a better understanding of the complex interactions within the triangle relationship of (parasitic) pathogens, the host immunity and the commensal gut microbiota during intestinal inflammation. The low-dose T. gondii infection model may be applied as valuable gut inflammation model in future pre-clinical studies in order to test potential treatment options for intestinal inflammatory conditions in humans.

Impact of the gut microbiome on the genome and epigenome of colon epithelial cells: contributions to colorectal cancer development

In recent years, the number of studies investigating the impact of the gut microbiome in colorectal cancer (CRC) has risen sharply. As a result, we now know that various microbes (and microbial communities) are found more frequently in the stool and mucosa of individuals with CRC than healthy controls, including in the primary tumors themselves, and even in distant metastases. We also know that these microbes induce tumors in various mouse models, but we know little about how they impact colon epithelial cells (CECs) directly, or about how these interactions might lead to modifications at the genetic and epigenetic levels that trigger and propagate tumor growth. Rates of CRC are increasing in younger individuals, and CRC remains the second most frequent cause of cancer-related deaths globally. Hence, a more in-depth understanding of the role that gut microbes play in CRC is needed. Here, we review recent advances in understanding the impact of gut microbes on the genome and epigenome of CECs, as it relates to CRC. Overall, numerous studies in the past few years have definitively shown that gut microbes exert distinct impacts on DNA damage, DNA methylation, chromatin structure and non-coding RNA expression in CECs. Some of the genes and pathways that are altered by gut microbes relate to CRC development, particularly those involved in cell proliferation and WNT signaling. We need to implement more standardized analysis strategies, collate data from multiple studies, and utilize CRC mouse models to better assess these effects, understand their functional relevance, and leverage this information to improve patient care.

A prostate derived commensal Staphylococcus epidermidis strain prevents and ameliorates induction of chronic prostatitis by UPEC infection

Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS) is a common syndrome with limited therapies and an unknown etiology. Previously, our laboratory has defined a potential role for pathogenic infection in disease onset. Intra-urethral infection with a uropathogenic Escherichia coli strain isolated from a CP/CPPS patient, CP1, induces prostatic inflammation and tactile allodynia in mice. We have also demonstrated that a prostate specific Staphylococcus epidermidis bacterial isolate, NPI (non-pain inducing), from a healthy subject reduces pain and inflammation in an experimental autoimmune prostatitis (EAP) murine model. Here we focus on the interplay between these human isolates in the context of prostatitis development and resolution. NOD/ShiLtJ mice were inoculated with either NP1 or CP1, or combinations of both. Infection with CP1 induced pelvic tactile allodynia after 7 days, while NPI instillation alone induced no such response. Instillation with NPI 7 days following CP1 infection resolved pelvic tactile allodynia and prophylactic instillation 7 days prior to CPI infection prevented its onset. Prophylactic NPI instillation also prevented CP1 colonization of both prostate and bladder tissues. In vitro analyses revealed that CP1 and NPI do not directly inhibit the growth or invasive potential of one another. Immunological analyses revealed that specific markers associated with CP1-induced pelvic allodynia were decreased upon NPI treatment or repressed by prophylactic colonization. This study demonstrates that a commensal bacterial isolate can inhibit the colonization, pain responses, and immunological activation to uropathogenic bacteria, emphasizing the power of a healthy prostatic microflora in controlling health and disease.

Fecal Microbiota Transplantation, Commensal Escherichia coli and Lactobacillus johnsonii Strains Differentially Restore Intestinal and Systemic Adaptive Immune Cell Populations Following Broad-spectrum Antibiotic Treatment

The essential role of the intestinal microbiota in the well-functioning of host immunity necessitates the investigation of species-specific impacts on this interplay. Aim of this study was to examine the ability of defined Gram-positive and Gram-negative intestinal commensal bacterial species, namely Escherichia coli and Lactobacillus johnsonii, respectively, to restore immune functions in mice that were immunosuppressed by antibiotics-induced microbiota depletion. Conventional mice were subjected to broad-spectrum antibiotic treatment for 8 weeks and perorally reassociated with E. coli, L. johnsonii or with a complex murine microbiota by fecal microbiota transplantation (FMT). Analyses at days (d) 7 and 28 revealed that immune cell populations in the small and large intestines, mesenteric lymph nodes and spleens of mice were decreased after antibiotic treatment but were completely or at least partially restored upon FMT or by recolonization with the respective bacterial species. Remarkably, L. johnsonii recolonization resulted in the highest CD4+ and CD8+ cell numbers in the small intestine and spleen, whereas neither of the commensal species could stably restore those cell populations in the colon until d28. Meanwhile less efficient than FMT, both species increased the frequencies of regulatory T cells and activated dendritic cells and completely restored intestinal memory/effector T cell populations at d28. Furthermore, recolonization with either single species maintained pro- and anti-inflammatory immune functions in parallel. However, FMT could most effectively recover the decreased frequencies of cytokine producing CD4+ lymphocytes in mucosal and systemic compartments. E. coli recolonization increased the production of cytokines such as TNF, IFN-γ, IL-17, and IL-22, particularly in the small intestine. Conversely, only L. johnsonii recolonization maintained colonic IL-10 production. In summary, FMT appears to be most efficient in the restoration of antibiotics-induced collateral damages to the immune system. However, defined intestinal commensals such as E. coli and L. johnsonii have the potential to restore individual functions of intestinal and systemic immunity. In conclusion, our data provide novel insights into the distinct role of individual commensal bacteria in maintaining immune functions during/following dysbiosis induced by antibiotic therapy thereby shaping host immunity and might thus open novel therapeutical avenues in conditions of perturbed microbiota composition.