Advanced application of bovine intestinal epithelial cell line for evaluating regulatory effect of lactobacilli against heat-killed enterotoxigenic Escherichia coli-mediated inflammation

Ligilactobacillus animalis 506 Protects the Intestinal Barrier from the Damaging Effects of Enteric Pathogens and Deoxynivalenol

This study investigated the impact of L. animalis 506 on gut barrier integrity and regulation of inflammation in vitro using intestinal epithelial cell lines. Caco-2 or HT29 cell monolayers were challenged with enterotoxigenic E. coli (ETEC) or a ruminant isolate of Salmonella Heidelberg in the presence or absence of one of six probiotic Lactobacillus spp. strains. Among these, L. animalis 506 excelled at exerting protective effects by significantly mitigating the decreased transepithelial electrical resistance (TEER) as assessed using area under the curve (AUC) (p < 0.0001) and increased apical-to-basolateral fluorescein isothiocyanate (FITC) dextran translocation (p < 0.0001) across Caco-2 cell monolayers caused by S. Heidelberg or ETEC, respectively. Similarly, L. animalis 506 and other probiotic strains significantly attenuated the S. Heidelberg- and ETEC-induced increase in IL-8 from HT29 cells (p < 0.0001). Moreover, L. animalis 506 significantly counteracted the TEER decrease (p < 0.0001) and FITC dextran translocation (p < 0.0001) upon challenge with Clostridium perfringens. Finally, L. animalis 506 significantly attenuated DON-induced TEER decrease (p < 0.01) and FITC dextran translocation (p < 0.05) and mitigated occludin and zona occludens (ZO)-1 redistribution in Caco-2 cells caused by the mycotoxin. Collectively, these results demonstrate the ability of L. animalis 506 to confer protective effects on the intestinal epithelium in vitro upon challenge with enteric pathogens and DON known to be of particular concern in farm animals.

Lactobacillus rhamnosus reduces CD8+T cell mediated inflammation in patients with rheumatoid arthritis

BACKGROUND

The T cells, components of adaptive immunity participate in immune pathology of the autoimmune inflammatory disorder called rheumatoid arthritis (RA). The presence of TLRs on the surface of the CD8⁺ T cells and their ability to recognize bacterial moieties adds to the inflammatory burden in case of RA. It has been reported that the gut microbiome is necessary for the crucial shift in the balance between proinflammatory and anti-inflammatory cytokines. The altered gut microbiome and the presence of TLRs emphasizes on the microbiome driven inflammatory responses in case of RA.

METHODS

Eighty-nine RA patients participated in this study. Clinical variations like disease duration, number of actively inflamed joints, number and type of bone deformities, CRP, RF, Anti-CCP, ESR, DAS 28 score were recorded for each patient. Co-culture of CD8⁺T cells and bacteria has been performed with proper culture condition. TLRs and inflammatory mediators' expression level were checked by both qPCR and flow cytometry analysis.

RESULTS

We observed in the suppression of pro-inflammatory molecules like Granzyme B and IFNƳ and expression of TLR2 in CD8 + T cells upon treatment with Lactobacillus rhamnosus (L. rhamnosus). Moreover, L. rhamnosus activated CD8⁺T cells such that they could induce FOXP3 expression in CD4⁺T cells thereby skewing T cell population towards a regulatory phenotype. On the contrary, TLR4 engagement on CD8⁺T cell by Escherichia coli (E.coli) increased in inflammatory responses following ERK activation.

CONCLUSIONS

Thus, we conclude that L. rhamnosus can effectively suppress CD8⁺T cell mediated inflammation by a simultaneous decrease of Th1 cells that may potentiate better treatment modalities for RA.

1,25-Dihydroxyvitamin D3 potentiates the innate immune response of peripheral blood mononuclear cells from Japanese Black cattle

1,25-Dihydroxyvitamin D3 (1,25(OH)2 D3 ), a bioactive vitamin D, is known to regulate immune responses in mammals. However, its impact on the innate immune responses of Japanese Black cattle, which are beef cattle endemic to Japan, remains unknown. Thus, in this study, we investigated the effect of 1,25(OH)2 D3 on the immune responses of peripheral blood mononuclear cells from Japanese Black cattle. As a result, the treatment of 1,25(OH)2 D3 upregulated the expression of antibacterial peptides, bovine beta-defensin 10 (DEFB10), and lingual antimicrobial peptide (LAP), in the presence and absence of lipopolysaccharide (LPS) stimulation. Moreover, 1,25(OH)2 D3 enhanced the inflammatory responses, including C-X-C motif ligand 8 (CXCL8) and nitric oxide synthase (NOS2), while reducing the expression of anti-inflammatory cytokine IL10, leading to an inflammatory phenotype. However, in contrast to humans and mice, 1,25(OH)2 D3 did not alter the expression of tumor necrosis factor (TNF) and downregulated triggering receptor expressed on myeloid cell 1 (TREM1) with LPS treatment. These results suggest that 1,25(OH)2 D3 potentiates the innate immune responses of Japanese Black cattle, albeit with different effects and mechanisms as compared to humans and mice.

Quercetin Alleviates Lipopolysaccharide-Induced Cell Damage and Inflammation via Regulation of the TLR4/NF-κB Pathway in Bovine Intestinal Epithelial Cells

Acute diarrhoea and intestinal inflammation represent one of the most prevalent clinical disorders of milk production, resulting in enormous annual financial damage for the dairy sector. In the context of an unsatisfactory therapeutic effect of antibiotics, the natural products of plants have been the focus of research. Quercetin is an important flavonoid found in a variety of plants, including fruits and vegetables, and has strong anti-inflammatory effects, so it has received extensive attention as a potential anti-inflammatory antioxidant. However, the underlying basis of quercetin on inflammatory reactions and oxidative tension generated by lipopolysaccharide (LPS) in bovine intestinal epithelial cells (BIECs) is currently unexplained. This research aimed to determine the influence of quercetin on LPS-induced inflammatory reactions, oxidative tension, and the barrier role of BIECs. Our findings demonstrated that BIEC viability was significantly improved in LPS-treated BIEC with 80 μg/mL quercetin compared with the control group. Indicators of oxidative overload and genes involved in barrier role revealed that 80 μg/mL quercetin efficiently rescued BIECs from oxidative and barrier impairment triggered by 5 μg/mL LPS. In addition, the mRNA expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, as well as chemokines CXCL2, CXCL5, CCL5, and CXCL8, was diminished in LPS-treated BIECs with 80 μg/mL quercetin compared with LPS alone. Furthermore, the mRNA expression of toll-like receptor 4 (TLR4), CD14, myeloid differential protein-2 (MD2), and myeloid differentiation primary response protein (MyD88) genes associated with the TLR4 signal mechanism was markedly reduced by the addition of quercetin to LPS-modulated BIECs, indicating that quercetin can suppress the TLR4 signal mechanism. We performed Western blotting on the NF-κB signalling mechanism and compared it with immunofluorescence to further corroborate this conclusion. The LPS treatment enhanced the proportions of p-IκBα/GAPDH and p-p65/GAPDH. Compared with the LPS-treated group, quercetin administration decreased the proportions of p-IκBα/GAPDH and p-p65/GAPDH. In addition, immunofluorescence demonstrated that quercetin greatly reduced the LPS-induced nuclear translocation of NF-κB p65 in BIECs. The benefits of quercetin on inflammatory reactions in LPS-induced BIECs may be a result of its capacity to inhibit the TLR4-mediated NF-κB signalling mechanism. These findings suggest that quercetin can be used as an anti-inflammatory reagent to treat intestinal inflammation induced by LPS release.

Immunomodulation Potential of Probiotics: A Novel Strategy for Improving Livestock Health, Immunity, and Productivity

Over the past decade, the use of probiotics as feed supplements in animal production has increased considerably due to the ban on antibiotic growth promoters in livestock. This review provides an overview of the current situation, limitation, and prospects for probiotic formulations applied to livestock. Recently, the use of probiotics in livestock has been suggested to significantly improve their health, immunity, growth performance, nutritional digestibility, and intestinal microbial balance. Furthermore, it was reported that the use of probiotics in animals was helpful in equilibrating their beneficial microbial population and microbial turnover via stimulating the host immune response through specific secretions and competitive exclusion of potentially pathogenic bacteria in the digestive tract. Recently, there has been great interest in the understanding of probiotics targeted diet and its ability to compete with harmful microbes and acquire their niches. Therefore, the present review explores the most commonly used probiotic formulations in livestock feed and their effect on animal health. In summary, this article provides an in-depth knowledge about the formulation of probiotics as a step toward a better alternative to antibiotic healthy growth strategies.

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.

Probiotics and gut microbiota: mechanistic insights into gut immune homeostasis through TLR pathway regulation

Consumption of probiotics as a useful functional food improves the host's wellbeing, and, when paired with prebiotics (indigestible dietary fibre/carbohydrate), often benefits the host through anaerobic fermentation.

Assessing Intestinal Health. In Vitro and Ex vivo Gut Barrier Models of Farm Animals: Benefits and Limitations

Animal performance is determined by the functionality and health of the gastrointestinal tract (GIT). Complex mechanisms and interactions are involved in the regulation of GIT functionality and health. The understanding of these relationships could be crucial for developing strategies to improve animal production yields. The concept of "gut health" is not well defined, but this concept has begun to play a very important role in the field of animal science. However, a clear definition of GIT health and the means by which to measure it are lacking. In vitro and ex vivo models can facilitate these studies, creating well-controlled and repeatable conditions to understand how to improve animal gut health. Over the years, several models have been developed and used to study the beneficial or pathogenic relationships between the GIT and the external environment. This review aims to describe the most commonly used animals' in vitro or ex vivo models and techniques that are useful for better understanding the intestinal health of production animals, elucidating their benefits and limitations.

Potential probiotic Lacticaseibacillus rhamnosus MTCC-5897 attenuates Escherichia coli induced inflammatory response in intestinal cells

Probiotics are microbes having tremendous potential to prevent gastrointestinal disorders. In current investigation, immunomodulatory action of probiotic Lacticaseibacillus rhamnosus MTCC-5897 was studied during exclusion, competition and displacement of Escherichia coli on intestinal epithelial (Caco-2) cells. The incubation of intestinal cells with Escherichia coli, enhanced downstream signalling and activated nuclear factor kappa B (NF-κB). This significantly increased (p < 0.01) the pro-inflammatory cytokines (IL-8, TNF-α, IFN-ϒ) expression. While, incubation of epithelial cells with Lacticaseibacillus rhamnosus during exclusion and competition with Escherichia coli, counteracted these enhanced expressions. The immunomodulatory feature of Lacticaseibacillus rhamnosus was also highlighted with increased (p < 0.05) transcription of toll-like receptor-2 (TLR-2) and single Ig IL-1-related receptor (SIGIRR) along with diminished expression of TLR-4. Likewise, attenuation (p < 0.05) of E. coli-mediated enhanced nuclear translocation of NF-κB p-65 subunit by Lacticaseibacillus rhamnosus during exclusion was confirmed with western blotting. Thus, present finding establishes the prophylactic potential of Lacticaseibacillus rhamnosus against exclusion of Escherichia coli in intestinal cells.

Cell-Free Culture Supernatant of Probiotic Lactobacillus fermentum Protects Against H2O2-Induced Premature Senescence by Suppressing ROS-Akt-mTOR Axis in Murine Preadipocytes

Information regarding cellular anti-senescence attributes of probiotic bacteria vis-à-vis modulation of senescence-associated secretory phenotype (SASP) and mTOR signaling is very limited. The present study assessed anti-senescence potential of secretory metabolites of probiotic Lactobacillus fermentum (Lact. fermentum) using H₂O₂-induced model of senescence in 3T3-L1 preadipocytes. Application of H₂O₂-induced cellular senescence characterized by increased cell size and SA-β-gal activity, activation of SASP and reactive oxygen species (ROS), DNA damage response and induction of cell cycle inhibitors (p53/p21^WAF1/p16^INK4a). Further, a robust stimulation of the PI3K/Akt/mTOR pathway and AMPK signaling was also observed in H₂O₂-treated cells. However, exposure of cells to cell-free supernatant of Lact. fermentum significantly attenuated phosphorylation of PI3K/Akt/mTOR pathway and alleviated senescence markers p53, p21^WAF1, SA-β-gal, p38MAPK, iNOS, cox-2, ROS, NF-κB, and DNA damage response. These results provide evidence that secretory metabolites of Lact. fermentum can mitigate the development as well as severity of stress-induced senescence thereby indicating its utility for use as anti-aging or age-delaying agent.

Early supplementation with Lactobacillus plantarum in liquid diet modulates intestinal innate immunity through toll-like receptor 4-mediated mitogen-activated protein kinase signaling pathways in young piglets challenged with Escherichia coli K88

This study was conducted to investigate the effects of early supplementation during 4 to 18 d of age with Lactobacillus plantarum (LP) in liquid diets on intestinal innate immune response in young piglets infected with enterotoxigenic Escherichia coli (ETEC) K88. Seventy-two barrow piglets at 4 d old were assigned to basal or LP-supplemented liquid diet (5 × 1010 CFU·kg-1). On day 15, piglets from each group were orally challenged with either ETEC K88 (1 × 108 CFU·kg-1) or the same amount of phosphate-buffered saline. The intestinal mucosa, mesenteric lymph node (MLN), and spleen samples were collected on day 18. Here, we found that LP pretreatment significantly decreased the mRNA relative expression of inflammatory cytokines (interleukin [IL]-1β, IL-8, and tumor necrosis factor-α), porcine β-defensin 2 (pBD-2), and mucins (MUC1 and MUC4) in the jejunal mucosa in piglets challenged with ETEC K88 (P < 0.05). Moreover, LP significantly decreased the ileal mucosa mRNA relative expression of IL-8 and MUC4 in young piglets challenged with ETEC K88 (P < 0.05). Furthermore, the piglets of the LP + ETEC K88 group had lower protein levels of IL-8, secretory immunoglobulin A, pBD-2, and MUC4 in the jejunal mucosa than those challenged with ETEC K88 (P < 0.05). Besides, LP supplementation reduced the percentage of gamma/delta T cells receptor (γδTCR) and CD172a+ (SWC3+) cells in MLN and the percentage of γδTCR cells in the spleen of young piglets after the ETEC K88 challenge. Supplementation with LP in liquid diets prevented the upregulated protein abundance of toll-like receptor (TLR) 4, phosphorylation-p38, and phosphorylation-extracellular signal-regulated protein kinases in the jejunal mucosa induced by ETEC K88 (P < 0.05). In conclusion, LP supplementation in liquid diet possesses anti-inflammatory activity and modulates the intestinal innate immunity during the early life of young piglets challenged with ETEC K88, which might be attributed to the suppression of TLR4-mediated mitogen-activated protein kinase signaling pathways. Early supplementation with LP in liquid diets regulates the innate immune response, representing a promising immunoregulation strategy for maintaining intestinal health in weaned piglets.

Screening of Lactic Acid Bacteria with Inhibitory Activity against ETEC K88 as Feed Additive and the Effects on Sows and Piglets

Simple Summary

Numerous reports have suggested that lactic acid bacteria (LAB), which are important probiotics, can protect animals against pathogen-induced injury and inflammation, regulate gut microflora, enhance digestive tract function, improve animal growth performance, and decrease the incidence of diarrhea caused by enterotoxigenic (ETEC) that expresses K88. This research selected Lactobacillus (L.) reuteri P7, L. amylovorus P8, and L. johnsonii P15 with good inhibition against ETEC K88 and excellent probiotic properties screened from 295 LAB strains isolated from fecal samples from 55 healthy weaned piglets for a study on feeding of sows in late pregnancy and weaned piglets. Feed supplementation with these three strains improved reproductive performance of sows and growth performance of piglets, decreased the incidence of diarrhea in piglets, and increased the antioxidant capacity of serum in both sows and piglets. Therefore, L. reuteri P7, L. amylovorus P8, and L. johnsonii P15 might be considered as potential antibiotic alternatives for further study.

Abstract

Enterotoxigenic Escherichia coli (ETEC), which expresses K88 is the principal microorganism responsible for bacterial diarrhea in pig husbandry, and the indiscriminate use of antibiotics has caused many problems; therefore, antibiotics need to be replaced in order to prevent diarrhea caused by ETEC K88. The objective of this study was to screen excellent lactic acid bacteria (LAB) strains that inhibit ETEC K88 and explore their effects as probiotic supplementation on reproduction, growth performance, diarrheal incidence, and antioxidant capacity of serum in sows and weaned piglets. Three LAB strains, P7, P8, and P15, screened from 295 LAB strains and assigned to Lactobacillus (L.) reuteri, L. amylovorus, and L. johnsonii with high inhibitory activity against ETEC K88 were selected for a study on feeding of sows and weaned piglets. These strains were chosen for their good physiological and biochemical characteristics, excellent exopolysaccharide (EPS) production capacity, hydrophobicity, auto-aggregation ability, survival in gastrointestinal (GI) fluids, lack of hemolytic activity, and broad-spectrum activity against a wide range of microorganisms. The results indicate that LAB strains P7, P8, and P15 had significant effects on improving the reproductive performance of sows and the growth performance of weaned piglets, increasing the activity of antioxidant enzymes and immune indexes in both.

Linear polysaccharides reduce production of inflammatory cytokines by LPS-stimulated bovine fibroblasts

Chronic lesions in the limbs of farm animals cause lameness due to chronic infection and inflammation. Exploratory treatments for chronic wounds in humans may be suitable for adaptation into the field of animal care. Specifically, antimicrobial linear polysaccharides like oxidized regenerated cellulose (ORC) and chitin/chitosan are biodegradable hemostats that are being explored to promote healing of chronic wounds but have not been directly compared using the same biological specimen. Despite their current use in humans, linear polysaccharides possess features that may preclude their use as biodegradable bandages. For example, ORC promotes inflammation when it remains in vivo and chitin/chitosan stimulate size-dependent proinflammatory responses. In order to assess the use of these materials to treat chronic wounds we have compared their effects on cellular toxicity and in stimulating the production of proinflammatory cytokines by bovine epidermal fibroblasts. While neither polysaccharide increased cell mortality, on average, they caused minor alterations in expression of proinflammatory cytokines from cells isolated from different animals. Both polysaccharides reduced expression of proinflammatory cytokines stimulated by microbial lipopolysaccharide. We conclude that the polysaccharides used in this study are relatively inert and may improve healing of chronic epidermal wounds in farm animals.

Characterization of bovine ileal epithelial cell line for lectin binding, susceptibility to enteric pathogens, and TLR mediated immune responses

In this study, primary and immortalized bovine intestinal epithelial cells (BIECs) were characterized for the expression of surface carbohydrate moieties. Primary BIEC-c4 cells showed staining greater than 90 % for 16 lectins but less than 50 % staining for four lectins. Immortalized BIECs showed significantly different lectin binding profile for few lectins compared to BIEC-c4 cells. BIEC-c4 cells were studied for infectivity to E. coli, Salmonella enterica, bovine rotavirus, bovine coronavirus, and bovine viral diarrhea virus. Bovine strain E. coli B41 adhered to BIEC-c4 cells and Salmonella strains S. Dublin and S. Mbandaka showed strong cell invasion. BIEC-c4 cells were susceptible to bovine rotavirus. LPS stimulation upregulated IL-10, IL-8, and IL-6 expression and Poly I:C upregulated TLR 8 and TLR 9 expression. This study provides important knowledge on the glycoconjugate expression profile of primary and immortalized BIECs and infectivity and immune responses of primary BIECs to bacterial and viral pathogens or ligands.

Molecular insights into probiotic mechanisms of action employed against intestinal pathogenic bacteria

Gastrointestinal (GI) diseases, and in particular those caused by bacterial infections, are a major cause of morbidity and mortality worldwide. Treatment is becoming increasingly difficult due to the increase in number of species that have developed resistance to antibiotics. Probiotic lactic acid bacteria (LAB) have considerable potential as alternatives to antibiotics, both in prophylactic and therapeutic applications. Several studies have documented a reduction, or prevention, of GI diseases by probiotic bacteria. Since the activities of probiotic bacteria are closely linked with conditions in the host's GI-tract (GIT) and changes in the population of enteric microorganisms, a deeper understanding of gut-microbial interactions is required in the selection of the most suitable probiotic. This necessitates a deeper understanding of the molecular capabilities of probiotic bacteria. In this review, we explore how probiotic microorganisms interact with enteric pathogens in the GIT. The significance of probiotic colonization and persistence in the GIT is also addressed.

An evaluation of the effects of probiotics on tumoral necrosis factor (TNF-α) signaling and gene expression

The search for functional foods containing probiotics has been growing due to numerous benefits they provide to health, such as modulation of the immune system and of the anti-inflammatory activity by inhibiting the release of pro-inflammatory cytokines, such as TNF-α. However, the mechanisms of actions of the probiotics responsible for this inhibition have not been completely explained so far. A better understanding of the interaction between probiotics and cell signaling pathways related to inflammatory processes shall help to prevent inflammatory bowel diseases. Therefore, the aim of this revision is to help understand the mechanisms of action of probiotics in cell signaling pathways that regulate TNF-α expression. Probiotics might act at different points of the MAPK pathway, on NF-kB, on proteasome activity, on Toll-like receptors, and on their regulators and stimuli. The present revision reaches the conclusion that probiotics act through multiple mechanisms, especially by inhibiting IkB phosphorylation and degradation, thus preventing the translocation of NF-kB. Effects are also shown to be strain-specific, and probiotics of the genus Lactobacillus are proved to play and essential role in anti-inflammatory activity.

The Role of Microbiota in Neutrophil Regulation and Adaptation in Newborns

Newborns are highly susceptible to infections and mainly rely on innate immune functions. Reduced reactivity, delayed activation and subsequent failure to resolve inflammation however makes the neonatal immune system a very volatile line of defense. Perinatal microbiota, nutrition and different extra-uterine factors are critical elements that define long-term outcomes and shape the immune system during the neonatal period. Neutrophils are first responders and represent a vital component of the immune system in newborns. They have long been regarded as merely executive immune cells, however this notion is beginning to shift. Neutrophils are shaped by their surrounding and adaptive elements have been described. The role of “innate immune memory” and the main triangle connection microbiome—neutrophil—adaptation will be discussed in this review.

Evaluation of the Immunomodulatory Ability of Lactic Acid Bacteria Isolated from Feedlot Cattle Against Mastitis Using a Bovine Mammary Epithelial Cells In Vitro Assay

Bovine mastitis, the inflammation of the mammary gland, affects the quality and quantity of milk yield. Mastitis control relies on single or multiple combinations of antibiotic therapy. Due to increasing antibiotic resistance in pathogens, the intramammary infusion of lactic acid bacteria (LAB) has been considered as a potential alternative to antibiotics for treating and preventing bovine mastitis through the improvement of the host immunity. Probiotic effects are a strain-dependent characteristic; therefore, candidate LAB strains have to be evaluated efficiently to find out the ones with the best potential. Here, we investigated LAB strains originally isolated from feedlot cattle’s environment regarding their ability in inducing the Toll-like receptor (TLR)-triggered inflammatory responses in bovine mammary epithelial (BME) cells in vitro. The BME cells were pre-stimulated with the LAB strains individually for 12, 24, and 48 h and then challenged with Escherichia coli-derived lipopolysaccharide (LPS) for 12 h. The mRNA expression of selected immune genes—interleukin 1 alpha (IL-1α), IL-1β, monocyte chemotactic protein 1 (MCP-1), IL-8, chemokine (C-X-C motif) ligand 2 (CXCL2), and CXCL3 were quantified by real-time quantitative PCR (RT-qPCR). Results indicated that pretreatment with some Lactobacillus strains were able to differentially regulate the LPS inflammatory response in BME cells; however, strain-dependent differences were found. The most remarkable effects were found for Lactobacillus acidophilus CRL2074, which reduced the expression of IL-1α, IL-1β, MCP-1, IL-8, and CXCL3, whereas Lactobacillus rhamnosus CRL2084 diminished IL-1β, MCP-1, and IL-8 expression. The pre-stimulation of BME cells with the CRL2074 strain resulted in the upregulated expression of three negative regulators of the TLRs, including the ubiquitin-editing enzyme A20 (also called tumor necrosis factor alpha-induced protein 3, TNFAIP3), single immunoglobin IL-1 single receptor (SIGIRR), and Toll interacting protein (Tollip) after the LPS challenge. The CRL2084 pre-stimulation upregulated only Tollip expression. Our results demonstrated that the L. acidophilus CRL2074 strain possess remarkable immunomodulatory abilities against LPS-induced inflammation in BME cells. This Lactobacillus strain could be used as candidate for in vivo testing due to its beneficial effects in bovine mastitis through intramammary infusion. Our findings also suggest that the BME cells immunoassay system could be of value for the in vitro evaluation of the immunomodulatory abilities of LAB against the inflammation resulting from the intramammary infection with mastitis-related pathogens.

Modulation of Toll-like receptor-mediated innate immunity in bovine intestinal epithelial cells by lactic acid bacteria isolated from feedlot cattle

The ability of lactobacilli isolated from feedlot cattle environment to differentially modulate the innate immune response triggered by Toll-like receptors (TLRs) activation in bovine intestinal epithelial (BIE) cells was evaluated. BIE cells were stimulated with Lactobacillus mucosae CRL2069, Lactobacillus acidophilus CRL2074, Lactobacillus fermentum CRL2085 or Lactobacillus rhamnosus CRL2084 and challenged with heat-stable pathogen associated molecular patterns (PAMPs) from enterotoxigenic Escherichia coli (ETEC) to induce the activation of TLR4 or with polyinosinic:polycytidylic acid (poly(I:C)) to activate TLR3. Type I interferons, cytokines, chemokines and negative regulators of TLR signalling were studied by RT-PCR. L. mucosae CRL2069 significantly reduced the expression of interleukin (IL)-8 and monocyte chemoattractant protein (MCP)-1 in BIE cells in the context of TLR3 activation. L. mucosae CRL2069 also reduced the expression of tumour necrosis factor-α, IL-β, MCP-1, and IL-8 in heat-stable ETEC PAMPs-challenged BIE cells. In addition, reduced expressions of IL-6, MCP-1, and IL-8 were found in BIE cells stimulated with L. rhamnosus CRL2084, although its effect was significantly lower than that observed for the CRL2069 strain. The reduced levels of pro-inflammatory factors in BIE cells induced by the CRL2069 and CRL2085 strains was related to their ability of increasing the expression of TLR negative regulators. L. mucosae CRL2069 significantly improved the expression of A20-binding inhibitor of NFκ-B activation 3 (ABIN-3), interleukin-1 receptor-associated kinase M (IRAK-M) and mitogen-activated protein kinase 1 (MKP-1) while L. rhamnosus CRL2084 augmented ABIN-3 expression in BIE cells. The results of this work suggest that among the studied strains, L. mucosae CRL2069 was able to regulate TLR3-mediated innate immune response and showed a remarkable capacity to modulate TLR4-mediated inflammation in BIE cells. The CRL2069 strain induce the up-regulation of three TLR negative regulators that would influence nuclear factor kB and mitogen-activated protein kinases signalling pathways while reducing the expression of pro-inflammatory cytokines and chemokines. Therefore, L. mucosae CRL2069 is an interesting immunobiotic candidate for the protection of the bovine host against TLR-mediated intestinal inflammatory damage.

Bifidobacterium animalis subsp. lactis 420 for Metabolic Health: Review of the Research

The growing worldwide epidemic of obesity and associated metabolic health comorbidities has resulted in an urgent need for safe and efficient nutritional solutions. The research linking obesity with gut microbiota dysbiosis has led to a hypothesis that certain bacterial strains could serve as probiotics helping in weight management and metabolic health. In the search for such strains, the effect of Bifidobacterium animalis subsp. lactis 420 (B420) on gut microbiota and metabolic health, and the mechanisms of actions, has been investigated in a variety of in vitro, pre-clinical, and clinical studies. In this review, we aim to highlight the research on B420 related to obesity, metabolic health, and the microbiota. Current research supports the hypothesis that gut dysbiosis leads to an imbalance in the inflammatory processes and loss of epithelial integrity. Bacterial components, like endotoxins, that leak out of the gut can invoke low-grade, chronic, and systemic inflammation. This imbalanced state is often referred to as metabolic endotoxemia. Scientific evidence indicates that B420 can slow down many of these detrimental processes via multiple signaling pathways, as supported by mechanistic in vitro and in vivo studies. We discuss the connection of these mechanisms to clinical evidence on the effect of B420 in controlling weight gain in overweight and obese subjects. The research further indicates that B420 may improve the epithelial integrity by rebalancing a dysbiotic state induced by an obesogenic diet, for example by increasing the prevalence of lean phenotype microbes such as Akkermansia muciniphila. We further discuss, in the context of delivering the health benefits of B420: the safety and technological aspects of the strain including genomic characterization, antibiotic resistance profiling, stability in the product, and survival of the live probiotic in the intestine. In summary, we conclude that the clinical and preclinical studies on metabolic health suggest that B420 may be a potential candidate in combating obesity; however, further clinical studies are needed.

Streptococcus thermophilus alters the expression of genes associated with innate and adaptive immunity in human peripheral blood mononuclear cells

Consumption of probiotics contributes to a healthy microbiome of the GIT leading to many health benefits. They also contribute to the modulation of the immune system and are becoming popular for the treatment of a number of immune and inflammatory diseases. The main objective of this study was to evaluate anti-inflammatory and modulatory properties of Streptococcus thermophilus. We used peripheral blood mononuclear cells from healthy donors and assessed modifications in the mRNA expression of their genes related to innate and adaptive immune system. Our results showed strong immune modulatory effects of S. thermophilus 285 to human peripheral blood mononuclear cells with an array of anti-inflammatory properties. S. thermophilus 285 reduced mRNA expression in a number of inflammatory immune mediators and markers, and upregulated a few of immune markers. S. thermophilus is used in the dairy industry, survives during cold storage, tolerates well upon ingesting, and their consumption may have beneficial effects with potential implications in inflammatory and autoimmune disorders.

Development and characterization of a stable bovine intestinal sub-epithelial myofibroblast cell line from ileum of a young calf

Intestinal sub-epithelial myofibroblasts (ISEMFs) are mesenchymal cells that do not express cytokeratin but express α-smooth muscle actin and vimentin. Despite being cells with diverse functions, there is a paucity of knowledge about their origin and functions primarily due to the absence of a stable cell line. Although myofibroblast in vitro models for human, mouse, and pig are available, there is no ISEMF cell line available from young calves. We isolated and developed an ileal ISEMF cell line from a 2-d-old calf that expressed α-smooth muscle actin and vimentin but no cytokeratin indicating true myofibroblast cells. To overcome replicative senescence, we immortalized primary cells with SV40 large T antigen. We characterized and compared both primary and immortalized ileal ISEMF cells for surface glycan and Toll-like-receptor (TLR) expression by lectin-binding assay and real-time quantitative PCR (RT-qPCR) assay respectively. SV40 immortalization significantly decreased surface lectin binding for lectins GSL-I, PHA-L, ECL, Jacalin, Con-A, LCA, and LEL. Both cell types expressed TLRs 1-9 and showed no significant differences in TLR expression. Thus, these cells can be useful in vitro model to study ISEMF's origin, physiology, and functions.

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.

Development and biochemical and immunological characterization of early passage and immortalized bovine intestinal epithelial cell lines from the ileum of a young calf

The intestinal epithelium is a major site of interaction with pathogens. In bovine intestinal epithelial cells (BIECs), Toll-like receptors (TLRs) play an important role in innate immune responses against enteric pathogens. This study is aimed at establishing a stable bovine intestinal epithelial cell line that can be maintained by a continuous passage so that studies on innate immune responses against various enteric pathogens can be performed. The main goal was to establish pure cultures of primary and immortalized bovine intestinal epithelial cells from the ileum and then characterize them biochemically and immunologically. Mixed epithelial and fibroblast bovine ileal intestinal cultures were first established from a 2-day old calf. Limiting dilution method was used to obtain a clone of epithelial cells which was characterized using immunocytochemistry (ICC). The selected clone BIEC-c4 was cytokeratin positive and expressed low levels of vimentin, confirming the epithelial cell phenotype. Early passage BIEC-c4 cells were transfected with either simian virus 40 (SV40) large T antigen or human telomerase reverse transcriptase (hTERT), or human papillomavirus (HPV) type 16E6/E7 genes to establish three immortalized BIEC cell lines. The expression of SV40, hTERT and HPV E6/E7 genes in immortalized BIECs was confirmed by a polymerase chain reaction (PCR). Immunocytochemistry and immunofluorescence assays also confirmed the expression of SV40, hTERT and HPV E6 proteins. The immortalized BIECs were cytokeratin positive and all except HPV-BIECs expressed low levels of vimentin. A growth kinetics study indicated that there were no significant differences in the doubling time of immortalized BIECs as compared to early passage BIEC-c4 cells. All four BIEC types expressed TLR 1-10 genes, with TLR 3 and 4 showing higher expression across all cell types. These newly established early passage and immortalized BIEC cell lines should serve as a good model for studying infectivity, pathogenesis and innate immune responses against enteric pathogens.

Immunobiotics for the Bovine Host: Their Interaction with Intestinal Epithelial Cells and Their Effect on Antiviral Immunity

The scientific community has reported several cases of microbes that exhibit elevated rates of antibiotic resistance in different regions of the planet. Due to this emergence of antimicrobial resistant microorganisms, the use of antibiotics as promoters of livestock animals' growth is being banned in most countries around the world. One of the challenges of agricultural immunology therefore is to find alternatives by modulating the immune system of animals in drug-independent safe food production systems. In this regard, in an effort to supplant antibiotics from bovine feeds, several alternatives were proposed including the use of immunomodulatory probiotics (immunobiotics). The purpose of this review is to provide an update of the status of the modulation of intestinal antiviral innate immunity of the bovine host by immunobiotics, and the beneficial impact of immunobiotics on viral infections, focused on intestinal epithelial cells (IECs). The results of our group, which demonstrate the capacity of immunobiotic strains to beneficially modulate Toll-like receptor 3-triggered immune responses in bovine IECs and improve the resistance to viral infections, are highlighted. This review provides comprehensive information on the innate immune response of bovine IECs against virus, which can be further investigated for the development of strategies aimed to improve defenses in the bovine host.

Probiotic Modulation of Innate Cell Pathogen Sensing and Signaling Events

There is a growing body of evidence documenting probiotic bacteria to have a beneficial effect to the host through their ability to modulate the mucosal immune system. Many probiotic bacteria can be considered to act as either immune activators or immune suppressors, which have appreciable influence on homeostasis, inflammatory- and suppressive-immunopathology. What is becoming apparent is the ability of these probiotics to modulate innate immune responses via direct or indirect effects on the signaling pathways that drive these activatory or suppressive/tolerogenic mechanisms. This review will focus on the immunomodulatory role of probiotics on signaling pathways in innate immune cells: from positive to negative regulation associated with innate immune cells driving gut mucosal functionality. Research investigations have shown probiotics to modulate innate functionality in many ways including, receptor antagonism, receptor expression, binding to and expression of adaptor proteins, expression of negative regulatory signal molecules, induction of micro-RNAs, endotoxin tolerisation and finally, the secretion of immunomodulatory proteins, lipids and metabolites. The detailed understanding of the immunomodulatory signaling effects of probiotic strains will facilitate strain-specific selective manipulation of innate cell signal mechanisms in the modulation of mucosal adjuvanticity, immune deviation and tolerisation in both healthy subjects and patients with inflammatory and suppressive pathology.

Maternal supplementation of seaweed-derived polysaccharides improves intestinal health and immune status of suckling piglets

The experiment investigated the effect of maternal dietary supplementation of seaweed-derived polysaccharides (SDP) (-SDP v. +SDP, n   20) from day 83 of gestation until weaning (day 28) on selected sow faeces and piglet digesta microbiota populations, piglet small-intestinal morphology, and intestinal nutrient transporter and inflammatory cytokine gene expression at birth, 48 h after birth and weaning. The effect of maternal dietary treatment on the piglet gene expression profile of inflammatory cytokines in the colon following a lipopolysaccharide (LPS) challenge was also investigated. Dietary SDP reduced sow faecal Enterobacteriaceae gene numbers at parturition. Small-intestinal morphology, nutrient transporter and cytokine gene expression in newborn piglets did not differ between maternal dietary treatments (P > 0·10). At 48 h after birth, sodium-glucose-linked transporter 1 gene expression was down-regulated in the ileum of piglets suckling the SDP-supplemented sows compared with those suckling the basal sows (P = 0·050). There was a SDP × LPS challenge interaction on IL-1 and IL-6 gene expression in the colon of piglets (P < 0·05). The gene expression of IL-1 and IL-6 was down-regulated in the LPS-challenged colon of piglets suckling the SDP sows compared with those suckling the basal sows (P < 0·05). However, there was no difference in IL-1 and IL-6 gene expression in the unchallenged colon between treatment groups. At weaning, piglets suckling the SDP-supplemented sows had increased villus height in the jejunum and ileum compared with those suckling the basal-fed sows (P < 0·05). In conclusion, maternal dietary SDP supplementation enhanced the immune response of suckling piglets and improved gut morphology, making them more immune competent to deal with post-weaning adversities.

Induction of pro-inflammatory gene expression by Escherichia coli and mycotoxin zearalenone contamination and protection by a Lactobacillus mixture in porcine IPEC-1 cells

This work investigated the effect of Escherichia coli K88 and zearalenone contamination on pro-inflammatory gene expression (Toll like receptors, cytokines) and signalling molecules and the protective activity of a mixture of Lactobacilli sp. (Lactobacillus plantarum, Lactobacillus acidofilus and Lactobacillus paracasei) in porcine intestinal epithelial cells as part of the local immune system. IPEC-1 cell monolayer was exposed for 1 h to the individual or combined action of E. coli, zearalenone and lactobacilli mixture. Our results showed that TLRs (1-10) and cytokine (IL-1,-6,-8,-10, TNF-α, IFN-γ) genes expressed early (after 1 h of culture) in IPEC-1 cells. E. coli alone increased the TLRs mRNA expression, especially TLR4 and the inflammatory cytokines while ZEA alone showed either no effect or a marginally effect on TLRs, cytokines, and signalling genes when compared to untreated cells. The combined actions of the two contaminants lead to a synergistically up-regulation of key cytokines (IFN-γ, IL-10 and TNF-α) and TLRs (-2,-3,-4,-6, and -10). The live lactobacilli mixture was able to attenuate the pathogen and mycotoxin-induced response by downregulated the majority of inflammatory related genes suggesting that this mixture has an immunomodulatory potential and may be used to lower the inflammatory response.

Effect of maternal supplementation with seaweed extracts on growth performance and aspects of gastrointestinal health of newly weaned piglets after challenge with enterotoxigenic Escherichia coli K88

In the present study, a 2 × 2 factorial arrangement was conducted to investigate the effect of maternal supplementation with seaweed extracts ( - SWE v. +SWE, n 20) from day 83 of gestation until weaning (day 28) on post-weaning (PW) growth performance, faecal score, faecal enterotoxigenic Escherichia coli (ETEC) toxin quantification, intestinal histology and cytokine mRNA of unchallenged and ETEC-challenged pigs. Pigs were ETEC challenged on day 9 PW. There was a maternal treatment × challenge (SWE × ETEC) interaction effect on growth performance and faecal score (P< 0.05). Pigs from SWE-supplemented sows and ETEC-challenged (SE) had higher average daily gain (ADG) during 0-13 d PW and reduced faecal score during 0-72 h post-challenge than those from basal-fed sows and ETEC-challenged (BE) (P< 0.05). However, there was no difference between unchallenged pigs from the SWE-supplemented sows (SC) and basal-fed sows (BC) (P>0.10). Pigs from the SWE-supplemented sows had reduced heat-labile enterotoxin gene copy numbers than those from the basal-fed sows (P< 0.05). Maternal SWE supplementation increased the villus height in the ileum of pigs (P< 0.05). There was a SWE × ETEC interaction effect (P< 0.05) on IL-6 mRNA and a SWE × gastrointestinal (GI) region interaction effect (P< 0.05) on transforming growth factor-β1 (TGF-β1) and TNF-α mRNA. IL-6 mRNA was down-regulated in SC pigs than BC pigs (P< 0.05). However, there was no difference in IL-6 mRNA between SE and BE pigs. The mRNA of TGF-β1 and TNF-α was down-regulated in the colon of pigs from the SWE-supplemented sows compared with those from the basal-fed sows (P< 0.05). However, there was no difference in TGF-β1 and TNF-α mRNA in the ileum between the pigs from the SWE-supplemented sows and basal-fed sows. In conclusion, maternal SWE supplementation improves ADG and the aspects of GI health of weaned pigs following an ETEC challenge.

Regulation of toll-like receptors-mediated inflammation by immunobiotics in bovine intestinal epitheliocytes: role of signaling pathways and negative regulators

Intestinal epithelial cells (IECs) detect bacterial and viral associated molecular patterns via germline-encoded pattern-recognition receptors (PRRs) and are responsible for maintaining immune tolerance to the communities of resident commensal bacteria while being also capable to mount immune responses against pathogens. Toll-like receptors (TLRs) are a major class of PRRs expressed on IECs and immune cells, which are involved in the induction of both tolerance and inflammation. In the last decade, experimental and clinical evidence was generated to support the application of probiotics with immunoregulatory capacities (immunobiotics) for the prevention and treatment of several gastrointestinal inflammatory disorders in which TLRs exert a significant role. The majority of these studies were performed in mouse and human cell lines, and despite the growing interest in the bovine immune system due to the economic importance of cattle as livestock, only few studies have been conducted on cattle. In this regard, our group has established a bovine intestinal epithelial (BIE) cell line originally derived from fetal bovine intestinal epitheliocytes and used this cell line to evaluate the impact of immunobiotics in TLR-mediated inflammation. This review aims to summarize the current knowledge of the beneficial effects of immunobiotics in the regulation of intestinal inflammation/infection in cattle. Especially, we discuss the role of TLRs and their negative regulators in both the inflammatory response and the beneficial effects of immunobiotics in bovine IECs. This review article emphasizes the cellular and molecular interactions of immunobiotics with BIE cells through TLRs and gives the scientific basis for the development of immunomodulatory feed for bovine healthy development.

Exopolysaccharides synthesized by Lactobacillus reuteri protect against enterotoxigenic Escherichia coli in piglets

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in piglets; ETEC cells colonize the intestinal mucosa with adhesins and deliver toxins that cause fluid loss. This study determined the antiadhesive properties of bacterial exopolysaccharides (reuteran and levan) and related glycans (dextran and inulin) in a small intestinal segment perfusion (SISP) model. The SISP model used 10 jejunal segments from 5-week-old piglets. Five segments were infected with ETEC expressing K88 fimbriae (ETEC K88), while five segments were treated with saline. Every two segments (ETEC and non-ETEC infected) were infused with 65 ml of 10 g liter(-1) of glycans or saline (control) for 8 h. High-resolution melting-curve (HRM) quantitative PCR (qPCR) indicated that E. coli is the dominant bacterium in infected segments, while other bacteria were predominant in noninfected segments. Infection by ETEC K88 was also verified by qPCR; gene copy numbers of K88 fimbriae and the heat-labile toxin (LT) in mucosal scrapings and outflow fluid of infected segments were significantly higher than those in noninfected segments. Genes coding for K88 fimbriae and LT were also detected in noninfected segments. LT amplicons from infected and noninfected segments were 99% identical over 481 bp, demonstrating the presence of autochthonous ETEC K88. All glycans reduced fluid loss caused by ETEC K88 infection. Reuteran tended (P = 0.06) to decrease ETEC K88 levels in mucosal scraping sample, as judged by qPCR. Fluorescent in situ hybridization analysis demonstrated that reuteran significantly (P = 0.012) decreased levels of adherent ETEC K88. Overall, reuteran may prevent piglet diarrhea by reducing adhesion of ETEC K88.

Immunobiotic Lactobacillus jensenii as immune-health promoting factor to improve growth performance and productivity in post-weaning pigs

Background

Immunoregulatory probiotics (immunobiotics) have been proposed to improve piglets’ immune system to avoid intestinal infections and reduce unproductive inflammation after weaning. Previously, it was demonstrated that Lactobacillus jensenii TL2937 (LjTL2937) attenuated the inflammatory response triggered by activation of Toll-like receptor 4 (TLR-4) in porcine intestinal epithelial (PIE) cells and antigen presenting cells (APCs) from porcine Peyer’s patches (PP).

Objective

In view of the critical importance of PIE-APCs interactions in the regulation of intestinal immune responses, we aimed to examine the effect of LjTL2937 on activation patterns of APCs from swine PPs in co-cultures with PIE cells. In addition, we investigated whether LjTL2937 was able to beneficially modulate intestinal immunity of piglets after weaning to improve immune-health status.

Results

Stimulation of PIE-APCs co-cultures with LjTL2937 increased the expression of MHC-II, CD80/86, IL-10, and Bcl-3 in CD172a⁺CD11R1^- and CD172a⁺CD11R1^high APCs. In addition, the TL2937 strain caused the upregulation of three negative regulators of TLR4 in PIE cells: MKP-1, Bcl-3 and A20. These changes significantly reduced the inflammatory response triggered by TLR4 activation in PIE-APCs co-cultures. The in vivo experiments using castrated male piglets (crossbreeding (LWD) with Landrace (L), Large Yorkshire (W) and Duroc (D))of 3 weeks of age demonstrated that feeding with LjTL2937 significantly reduced blood complement activity and C reactive protein concentrations while no changes were observed in blood leukocytes, ratio of granulocytes to lymphocyte numbers, macrophages’ activity and antibody levels. In addition, treatment with LjTL2937 significantly improved growth performance and productivity, and increased carcass quality.

Conclusions

We demonstrated that the use of immunobiotics strains like LjTL2937, as supplemental additives for piglets feedings, could be used as a strategy to maintain and improve intestinal homeostasis; that is important for the development of the pig and for health and performance throughout the productive life of the animal.

Modulation of Respiratory TLR3-Anti-Viral Response by Probiotic Microorganisms: Lessons Learned from Lactobacillus rhamnosus CRL1505

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract illness in infants and young children. Host immune response is implicated in both protective and immunopathological mechanisms during RSV infection. Activation of Toll-like receptor (TLR)-3 in innate immune cells by RSV can induce airway inflammation, protective immune response, and pulmonary immunopathology. A clear understanding of RSV–host interaction is important for the development of novel and effective therapeutic strategies. Several studies have centered on whether probiotic microorganisms with the capacity to stimulate the immune system (immunobiotics) might sufficiently stimulate the common mucosal immune system to improve defenses in the respiratory tract. In this regard, it was demonstrated that some orally administered immunobiotics do have the ability to stimulate respiratory immunity and increase resistance to viral infections. Moreover, during the last decade scientists have significantly advanced in the knowledge of the cellular and molecular mechanisms involved in the protective effect of immunobiotics in the respiratory tract. This review examines the most recent advances dealing with the use of immunobiotic bacteria to improve resistance against viral respiratory infections. More specifically, the article discuss the mechanisms involved in the capacity of the immunobiotic strain Lactobacillus rhamnosus CRL1505 to modulate the TLR3-mediated immune response in the respiratory tract and to increase the resistance to RSV infection. In addition, we review the role of interferon (IFN)-γ and interleukin (IL)-10 in the immunoregulatory effect of the CRL1505 strain that has been successfully used for reducing incidence and morbidity of viral airways infections in children.

Lactobacillus amylovorus inhibits the TLR4 inflammatory signaling triggered by enterotoxigenic Escherichia coli via modulation of the negative regulators and involvement of TLR2 in intestinal Caco-2 cells and pig explants

Inflammation derived from pathogen infection involves the activation of toll-like receptor (TLR) signaling. Despite the established immunomodulatory activities of probiotics, studies relating the ability of such bacteria to inhibit the TLR signaling pathways are limited or controversial. In a previous study we showed that Lactobacillus amylovorus DSM 16698T, a novel lactobacillus isolated from unweaned pigs, protects the intestinal cells from enterotoxigenic Escherichia coli (ETEC) K88 infection through cytokine regulation. In the present study we investigated whether the ability of L. amylovorus to counteract the inflammatory status triggered by ETEC in intestine is elicited through inhibition of the TLR4 signaling pathway. We used the human intestinal Caco-2/TC7 cells and intestinal explants isolated from 5 week-old crossbreed Pietrain/Duroc/Large-White piglets, treated with ETEC, L. amylovorus or L. amylovorus cell free supernatant, either alone or simultaneously with ETEC. Western blot analysis showed that L. amylovorus and its cell free supernatant suppress the activation of the different steps of TLR4 signaling in Caco-2/TC7 cells and pig explants, by inhibiting the ETEC induced increase in the level of TLR4 and MyD88, the phosphorylation of the IKKα, IKKβ, IκBα and NF-κB subunit p65, as well as the over-production of inflammatory cytokines IL-8 and IL-1β. The immunofluorescence analysis confirms the lack of phospho-p65 translocation into the nucleus. These anti-inflammatory effects are achieved through modulation of the negative regulators Tollip and IRAK-M. We also found that L. amylovorus blocks the up-regulation of the extracellular heat shock protein (Hsp)72 and Hsp90, that are critical for TLR4 function. By using anti-TLR2 antibody, we demonstrate that TLR2 is required for the suppression of TLR4 signaling activation. These results may contribute to develop therapeutic interventions using L. amylovorus in intestinal disorders of piglets and humans.

Sterile-filtered saliva is a strong inducer of IL-6 and IL-8 in oral fibroblasts

OBJECTIVES

Saliva has been implicated to support oral wound healing, a process that requires a transient inflammatory reaction. However, definitive proof that saliva can provoke an inflammatory response remained elusive.

MATERIALS AND METHODS

We investigated the ability of freshly harvested and sterile-filtered saliva to cause an inflammatory response of oral fibroblasts and epithelial cells. The expression of cytokines and chemokines was assessed by microarray, RT-PCR, immunoassays, and Luminex technology. The involvement of signaling pathways was determined by Western blot analysis and pharmacologic inhibitors.

RESULTS

We report that sterile-filtered whole saliva was a potent inducer of IL-6 and IL-8 in fibroblasts from the gingiva, the palate, and the periodontal ligament, but not of oral epithelial cells. This strong inflammatory response requires nuclear factor-kappa B and mitogen-activated protein kinase signaling. The pro-inflammatory capacity is heat stable and has a molecular weight of <40 kDa. Genome-wide microarrays and Luminex technology further revealed that saliva substantially increased expression of other inflammatory genes and various chemokines. To preclude that the observed pro-inflammatory activity is the result of oral bacteria, sterile-filtered parotid saliva, collected under almost aseptic conditions, was used and also increased IL-6 and IL-8 expression in gingiva fibroblasts. The inflammatory response was, furthermore, independent of MYD88, an adapter protein of the Toll-like receptor signaling pathway.

CONCLUSIONS

We conclude that saliva can provoke a robust inflammatory response in oral fibroblasts involving the classical nuclear factor-kappa B and mitogen-activated protein kinase signaling pathway.

CLINICAL RELEVANCE

Since fibroblasts but not epithelial cells show a strong inflammatory response, saliva may support the innate immunity of defect sites exposing the oral connective tissue.