Transforming growth factor-beta regulation of epithelial tight junction proteins enhances barrier function and blocks enterohemorrhagic Escherichia coli O157:H7-induced increased permeability

Effects of crude protein and lactose levels in diets on growth performance, intestinal morphology, and expression of genes related to intestinal integrity and immune system in weaned piglets

To evaluate the effects of crude protein (CP) and lactose (LAC) for weaned piglets on performance, intestinal morphology, and expression of genes related to intestinal integrity and immune system, 144 piglets with initial weight 7.17 ± 0.97 kg were allotted in a randomized design, in a 2 × 3 factorial arrangement (20.0% and 24.0% CP and 8.0%, 12.0%, and 16.0% LAC) with eight replicates. Piglets fed 20.0% CP had greater weight gain and feed intake. Including 12.0% LAC in the 20.0% CP diet provided higher villous height in the duodenum than 8.0% LAC, and 12.0% or 16.0% LAC in the 24.0% CP diet resulted in higher villous height in the jejunum and ileum, and higher villi/crypt ratio in the ileum than 8.0% LAC. No effects of CP and LAC on interleukin-1β and tumor necrosis factor-α mRNA were observed. The 16.0% LAC diet provided higher gene expression of transforming-β1 growth factor. Feeding 20.0% CP resulted in better performance than 24.0% CP. The 12.0% LAC diet promoted greater genetic expression of occludin and zonula occludens. Including 12.0% LAC in the diet may improve intestinal epithelial morphology and integrity, and these improvements are more evident when piglets are fed diets with 24.0% CP.

Protective effects of lactic acid bacteria on gut epithelial barrier dysfunction are Toll like receptor 2 and protein kinase C dependent

Lactic acid bacteria (LAB) are recognized for support of host gut homeostasis but the precise mechanisms remain to be identified. LABs interact with Toll-like receptors (TLRs) which might stimulate barrier function of gut epithelial cells. We previously identified six TLR2-signalling LAB strains. As TLR2 is involved in barrier-function enhancement in gut-epithelium, the epithelial barrier-protective effect of these TLR2-signalling strains was studied by using T84 human colorectal cancer cell monolayer as an in vitro gut epithelial barrier model. The protein kinase C (PKC) dependent barrier disruptor A23187 and mitogen-activated protein kinase dependent barrier stressor deoxynivalenol were tested to determine which pathways LAB influenced. We found that exclusively the PKC dependent disruption was prevented by the selected TLR2-signalling LAB strains. This study suggests that TLR2 is a pivotal epithelial barrier modulator, and provides novel insight in the molecular mechanisms by which LAB contribute to intestinal health.

Yogurt Produced by Novel Natural Starter Cultures Improves Gut Epithelial Barrier In Vitro

Yogurt is a traditional fermented dairy product, prepared with starter cultures containing Streptococcus thermophilus and Lactobacillus bulgaricus that has gained widespread consumer acceptance as a healthy food. It is widely accepted that yogurt cultures have been recognized as probiotics, due to their beneficial effects on human health. In this study, we have characterized technological and health-promoting properties of autochthonous strains S. thermophilus BGKMJ1-36 and L. bulgaricus BGVLJ1-21 isolated from artisanal sour milk and yogurt, respectively, in order to be used as functional yogurt starter cultures. Both BGKMJ1-36 and BGVLJ1-21 strains have the ability to form curd after five hours at 42 °C, hydrolyze αs1-, β-, and κ- casein, and to show antimicrobial activity toward Listeria monocytogenes. The strain BGKMJ1-36 produces exopolysaccharides important for rheological properties of the yogurt. The colonies of BGKMJ1-36 and BGVLJ1-21 strains that successfully survived transit of the yogurt through simulated gastrointestinal tract conditions have been tested for adhesion to intestinal epithelial Caco-2 cells. The results reveal that both strains adhere to Caco-2 cells and significantly upregulate the expression of autophagy-, tight junction proteins-, and anti-microbial peptides-related genes. Hence, both strains may be interesting for use as a novel functional starter culture for production of added-value yogurt with health-promoting properties.

Tight junction protein claudin-1 is downregulated by TGF-β1 via MEK signaling in benign prostatic epithelial cells

BACKGROUND

Benign prostatic hyperplasia (BPH) is arguably the most common disease in aging men. Although the etiology is not well understood, chronic prostatic inflammation is thought to play an important role in BPH initiation and progression. Our recent studies suggest that the prostatic epithelial barrier is compromised in glandular BPH tissues. The proinflammatory cytokine transforming growth factor beta 1 (TGF-β1) impacts tight junction formation, enhances epithelial barrier permeability, and suppresses claudin-1 messenger RNA expression in prostatic epithelial cells. However, the role of claudin-1 in the prostatic epithelial barrier and its regulation by TGF-β1 in prostatic epithelial cells are not clear.

METHODS

The expression of claudin-1 was analyzed in 22 clinical BPH specimens by immunohistochemistry. Human benign prostate epithelial cell lines BPH-1 and BHPrE1 were treated with TGF-β1 and transfected with small interfering RNAs specific to claudin-1. Epithelial monolayer permeability changes in the treated cells were measured using trans-epithelial electrical resistance (TEER). The expression of claudin-1, E-cadherin, N-cadherin, snail, slug, and activation of mitogen-activated proteins kinases (MAPKs) and AKT was assessed following TGF-β1 treatment using Western blot analysis.

RESULTS

Claudin-1 expression was decreased in glandular BPH tissue compared with adjacent normal prostatic tissue in patient specimens. TGF-β1 treatment or claudin-1 knockdown in prostatic epithelial cell lines increased monolayer permeability. TGF-β1 decreased levels of claudin-1 and increased levels of snail and slug as well as increased phosphorylation of the MAPK extracellular signal-regulated kinase-1/2 (ERK-1/2) in both BPH-1 and BHPrE1 cells. Overexpression of snail or slug had no effect on claudin-1 expression. In contrast, PD98059 and U0126, inhibitors of the upstream activator of ERK-1/2 (ie, MEK-1/2) restored claudin-1 expression level as well as the epithelial barrier.

CONCLUSION

Our findings suggest that downregulation of claudin-1 by TGF-β1 acting through the noncanonical MEK-1/2/ERK-1/2 pathway triggers increased prostatic epithelial monolayer permeability in vitro. These findings also suggest that elevated TGF-β1 may contribute to claudin-1 downregulation and compromised epithelial barrier in clinical BPH specimens.

Effects of antibacterial peptide combinations on growth performance, intestinal health, and immune function of broiler chickens

To study the effects of antibacterial peptides (ABPs) on feeding broilers, this experiment compared the 2 combinations of ABP with antibiotics by separately adding the supplement to the diet of 818 broilers as follows—antibiotics, Pratt and Full-tide, and Pratt and plant essential oil—and then the effect of them on production performance, immune function, antioxidant capacity, serum biochemical indicators, and microorganisms of the experimental flocks was investigated and compared. It was found that the aforementioned indicators among the 2 groups of ABP and the antibiotic group were close to or even better than those of antibiotics, and the combination added with plant essential oils had generally better effects. These results indicated that ABPs could improve economic benefits by promoting growth, preventing disease, and reducing the rate of death. This study deepened the research on the action mechanism of ABPs and not only explored the feasibility of ABPs as a novel feed additive for broilers but also provided experimental data and theoretical basis for the application of ABPs.

An In Vitro Bovine Cellular Model for Human Schlemm's Canal Endothelial Cells and Their Response to TGFβ Treatment

Purpose

Due to the limited availability of primary human Schlemm's canal (SC) endothelial cells, we aimed to develop an in vitro cellular model using the angular aqueous plexus (AAP) cells from bovine eyes.

Methods

We harvested a mixture of cells from the trabecular meshwork region including AAP loops from multiple donors, followed by puromycin treatment and immunostaining of Von Willebrand factor and vascular endothelial (VE)-cadherin to confirm identity. Previously identified differentially expressed genes in glaucomatous SC cells were examined in non-glaucomatous SC cells (n = 3) under 0% or 15% equibiaxial strain for 24 hours using droplet digital polymerase chain reaction (ddPCR) and analyzed using the Ingenuity Pathway Analysis (IPA) software application to identify upstream regulators. To compare the cellular responses to candidate regulators of these mechanoresponsive genes, AAP and human SC cells (n = 3) were treated with 5 or 10 ng/mL transforming growth factor beta-2 (TGFβ2) for 24 or 48 hours, followed with expression profiling using real-time PCR or ddPCR.

Results

We found that the isolated AAP cells displayed uniform cobblestone-like morphology and positive expression of two endothelial markers. In stretched SC cells, nine glaucoma-related genes were upregulated, and IPA implicated TGFβ as a potential upstream regulator. The effects of TGFβ2 treatment were similar for both AAP and SC cells in a dose- and time-dependent manner, activating TGFBR1 and SMAD2, inhibiting BMP4, and altering expression of three glaucoma-related genes (DCN,EZR, and CYP1B1).

Conclusions

Bovine AAP cells may serve as an alternative cellular model of human SC cells.

Translational Relevance

These AAP cells may be used to study the functional pathways related to the outflow facility.

Proanthocyanidin-Rich Grape Seed Extract Reduces Inflammation and Oxidative Stress and Restores Tight Junction Barrier Function in Caco-2 Colon Cells

Grape polyphenols have previously been shown to improve gut health and attenuate the symptoms of metabolic syndrome; however, the mechanism of these beneficial effects is still debated. In this study, we investigated the protective effect of proanthocyanidin-rich grape seed extract (GSE) on bacterial lipopolysaccharide (LPS)-induced oxidative stress, inflammation, and barrier integrity of human Caco-2 colon cells. GSE significantly reduced the LPS-induced intracellular reactive oxygen species (ROS) production and mitochondrial superoxide production, and upregulated the expression of antioxidant enzyme genes. GSE also restored the LPS-damaged mitochondrial function by increasing mitochondrial membrane potential. In addition, GSE increased the expression of tight junction proteins in the LPS-treated Caco-2 cells, increased the expression of anti-inflammatory cytokines, and decreased pro-inflammatory cytokine gene expression. Our findings suggest that GSE exerts its beneficial effects on metabolic syndrome by scavenging intestinal ROS, thus reducing oxidative stress, increasing epithelial barrier integrity, and decreasing intestinal inflammation.

Transforming growth factor beta 1 impairs benign prostatic luminal epithelial cell monolayer barrier function

Our recent studies identifying the presence of luminal secretory protein PSA in the stroma, decreased E-cadherin expression, and reduced number of tight junction kiss points in benign prostatic hyperplasia (BPH) tissues suggest that epithelial barrier permeability is increased in BPH. However, the cause of increased epithelial permeability in BPH is unclear. Transforming growth factor beta 1 (TGF-β1) has been reported to be up-regulated in clinical BPH specimens and TGF-β1 overexpression induced fibrosis and inflammation in a murine model. TGF-β1 was reported to repress the expression of E-cadherin in benign prostatic cells. However, whether and how TGF-β1 up-regulation affects epithelial barrier permeability is unknown. Here, in vitro benign prostatic epithelial cell lines BHPrE1 and BPH-1 were utilized to determine the impact of TGF-β1 treatment on epithelial barrier, tight junctions, and expression of E-cadherin and claudin 1 by transepithelial electrical resistance (TEER) measurement, FITC-dextran trans-well diffusion assays, qPCR, as well as transmission electron microscopy (TEM) observation. Laser capture micro-dissection (LCM) combined with reverse transcription-polymerase chain reaction (qPCR) were utilized to determine the expression of E-cadherin and claudin 1 in BPH patient specimens. TGF-β1 treatment decreased TEER, increased FITC-dextran diffusion, and reduced the mRNA expression of junction protein claudin 1 in cultured cell monolayers. Claudin 1 mRNA but not E-cadherin mRNA was down-regulated in the luminal epithelial cells in BPH nodules compared to normal prostate tissues. Our studies suggest that TGF-β1 could increase the permeability through decreasing the expression of claudin 1 and inhibiting the formation of tight junctions in BHPrE1 and BPH-1 monolayers. These results suggest that TGF-β1 might play an important role in BPH pathogenesis through increasing the permeability of luminal epithelial barrier in the prostate.

Immunity, microbiota and kidney disease

The recognition that intestinal microbiota exert profound effects on human health has led to major advances in our understanding of disease processes. Studies over the past 20 years have shown that host components, including components of the host immune system, shape the microbial community. Pathogenic alterations in commensal microorganisms contribute to disease manifestations that are generally considered to be noncommunicable, such as inflammatory bowel disease, diabetes mellitus and liver disease, through a variety of mechanisms, including effects on host immunity. More recent studies have shed new light on how the immune system and microbiota might also drive the pathogenesis of renal disorders. In this Review, we discuss the latest insights into the mechanisms regulating the microbiome composition, with a focus both on genetics and environmental factors, and describe how commensal microorganisms calibrate innate and adaptive immune responses to affect the activation threshold for pathogenic stimulations. We discuss the mechanisms that lead to intestinal epithelial barrier inflammation and the relevance of certain bacteria to the pathogenesis of two common kidney-based disorders: hypertension and renal stone disease. Limitations of current approaches to microbiota research are also highlighted, emphasizing the need to move beyond studies of correlation to causation.

Effects of dietary supplementation with yeast glycoprotein on growth performance, intestinal mucosal morphology, immune response and colonic microbiota in weaned piglets

Antibiotics are commonly provided to weaned piglets; however, this practice has become controversial due to the increased occurrences of microbial resistance, and alternatives are needed. This study aimed to investigate the effects of dietary supplementation with yeast glycoprotein (YG) on growth performance, intestinal mucosal morphology, immune response and colonic microbiota in weaned piglets. A total of 240 weaned piglets (d 23 ± 2) from 16 pens (15 piglets per pen) were randomly allocated to an antibiotics group (25% quinocetone 200 mg kg-1 and 4% enduracidin 800 mg kg-1 of the basal diet) or a YG group (800 mg kg-1 YG of the basal diet), respectively. The trial lasted 14 days, and at the end of the trial, one piglet per pen was chosen to collect plasma, intestinal tissue and colonic digesta samples. The results indicate that piglets fed diets containing YG tended to show increased final body weight (0.05 < P < 0.1), increased average daily gain (P < 0.05) and decreased F/G (P < 0.05) when compared with the antibiotics group. Moreover, intestinal permeability showed that YG led to an improvement in the intestinal development via decreasing serum content of DAO (P < 0.01). Histological evaluations showed that YG contributed to the improvement of the intestinal development via increasing villous height (P < 0.05) and the villous height to crypt depth ratio (P < 0.01), and decreasing crypt depth (P < 0.01) and villous width (P < 0.05) in the ileum. Intestinal integrity also showed that YG was conducive to improvement of the intestinal development via upregulating the m-RNA expression of occludin (P < 0.05) in the duodenal and jejunal mucosa. Interestingly, YG supplementation downregulated the m-RNA expression of IL-12 (P < 0.05), upregulated the m-RNA expression of Hsp-70 (P < 0.05) in the duodenal mucosa, downregulated the m-RNA expression of Hsp-70 (P < 0.05) and IFN-γ (P < 0.05), upregulated the m-RNA expression of Hsp-90 (P < 0.05) in the jejunal mucosa, and upregulated the m-RNA expression of Hsp-70 (P < 0.05) in the ileal mucosa. On the other hand, colonic microbiota results showed that YG supplementation increased the relative abundance of Lactobacillus (P < 0.05) in the genus level. Colonic metabolite results showed that YG supplementation decreased the content of acetate (P < 0.05). Taken together, it is speculated that YG would be a potent alternative to prophylactic antibiotics in improving the gut health in weaned piglets.

Developments in the field of allergy in 2017 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2017. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis and clinical allergy are all covered.

Biomaterial-tight junction interaction and potential impacts

The active pharmaceutical ingredients (APIs) have to cross the natural barriers and get into the blood to impart the pharmacological effects. The tight junctions (TJs) between the epithelial cells serve as the major selectively permeable barriers and control the paracellular transport of the majority of hydrophilic drugs, in particular, peptides and proteins. TJs perfectly balance the targeted transport and the exclusion of other unexpected pathogens under the normal conditions. Many biomaterials have shown the capability to open the TJs and improve the oral bioavailability and targeting efficacy of the APIs. Nevertheless, there is limited understanding of the biomaterial-TJ interactions. The opening of the TJs further poses the risk of autoimmune diseases and infections. This review article summarizes the most updated literature and presents insights into the TJ structure, the biomaterial-TJ interaction mechanism, the benefits and drawbacks of TJ disruption, and methods for evaluating such interactions.

Gadd45β promotes regeneration after injury through TGFβ-dependent restitution in experimental colitis

Dysregulated immune responses and impaired function in intestinal epithelial cells contribute to the pathogenesis of inflammatory bowel disease (IBD). Growth arrest and DNA damage-inducible 45 beta (Gadd45β) has been implicated in the pathogenesis of various inflammatory symptoms. However, the role of Gadd45β in IBD is completely unknown. This study aimed to evaluate the role of Gadd45β in IBD. Gadd45β-KO mice exhibited drastically greater susceptibility to dextran sulfate sodium (DSS)-induced colitis and mortality than C57BL/6J mice. Bone marrow transplantation experiments revealed that Gadd45β functions predominantly in the intestinal epithelium and is critical during the recovery phase. Gadd45β regulates the TGF-β signaling pathway in colon tissue and epithelial cells by inhibiting Smurf-mediated degradation of TGF-β receptor type 1 via competitive binding to the N-terminal domain of Smad7. Furthermore, these results indicate that the Gadd45β-regulated TGF-β signaling pathway is involved in wound healing by enhancing epithelial restitution. These results expand the current understanding of the function of Gadd45β and its therapeutic potential in ulcerative colitis.

A signaling molecule that prevents inflammatory damage in an animal model of ulcerative colitis offers a promising therapeutic target. The molecular drivers of this form of inflammatory bowel disease remain poorly understood, but the associated damage to the intestinal epithelium is primarily due to uncontrolled immune cell activity. Jung Hwan Hwang of the Korea Research Institute of Bioscience and Biotechnology, Daejeon, and coworkers have now demonstrated that a protein called Gadd45β helps to reduce inflammatory damage to the epithelial barrier. They showed that a mouse model of chemically induced ulcerative colitis exhibited more severe disease symptoms and higher mortality when these animals also lacked Gadd45β. This protein is generally known to modulate immune cell activity response, but in this disease model, the authors primarily observed activity within intestinal epithelial cells, where it appears to facilitate wound healing.

Effect of Multi-Microbial Probiotic Formulation Bokashi on Pro- and Anti-Inflammatory Cytokines Profile in the Serum, Colostrum and Milk of Sows, and in a Culture of Polymorphonuclear Cells Isolated from Colostrum

The use of probiotics in sows during pregnancy and lactation and their impact on the quality of colostrum and milk, as well as the health conditions of their offspring during the rearing period, are currently gaining the attention of researchers. The aim of the study was to determine the effect of Bokashi formulation on the concentrations of pro- and anti-inflammatory cytokines in the serum of sows during pregnancy, in their colostrum and milk, and in a culture of Con-A-stimulated polymorphonuclear cells (PMNs) isolated from the colostrum. The study was conducted on 60 sows aged 2–4 years. EM Bokashi were added to the sows’ feed. The material for the study consisted of peripheral blood, colostrum, and milk. Blood samples were collected from the sows on days 60 and 114 of gestation. Colostrum and milk samples were collected from all sows at 0, 24, 48, 72, 96, 120, 144, and 168 h after parturition. The results indicate that the use of Bokashi as feed additives resulted in increased concentrations of pro-inflammatory cytokines TNF-α and IL-6, which increase the protective capacity of the colostrum by stimulating cellular immune mechanisms protecting the sow and neonates against infection. At the same time, the increased concentrations of cytokines IL-4, IL-10, TGF-β, and of immunoglobulins in the colostrum and milk from sows in the experimental group demonstrate the immunoregulatory effect of Bokashi on Th2 cells and may lead to increased expression of regulatory T cells and polarization of the immune response from Th1 to Th2.

Inflammatory Bowel Disease Types Differ in Markers of Inflammation, Gut Barrier and in Specific Anti-Bacterial Response

Crohn’s disease (CD), ulcerative colitis (UC) and inflammatory bowel disease (IBD) associated with primary sclerosing cholangitis (PSC-IBD), share three major pathogenetic mechanisms of inflammatory bowel disease (IBD)-gut dysbiosis, gut barrier failure and immune system dysregulation. While clinical differences among them are well known, the underlying mechanisms are less explored. To gain an insight into the IBD pathogenesis and to find a specific biomarker pattern for each of them, we used protein array, ELISA and flow cytometry to analyze serum biomarkers and specific anti-microbial B and T cell responses to the gut commensals. We found that decrease in matrix metalloproteinase (MMP)-9 and increase in MMP-14 are the strongest factors discriminating IBD patients from healthy subjects and that PSC-IBD patients have higher levels of Mannan-binding lectin, tissue inhibitor of metalloproteinases 1 (TIMP-1), CD14 and osteoprotegerin than patients with UC. Moreover, we found that low transforming growth factor-β1 (TGF-β1) is associated with disease relapse and low osteoprotegerin with anti-tumor necrosis factor-alpha (TNF-α) therapy. Patients with CD have significantly decreased antibody and increased T cell response mainly to genera Eubacterium, Faecalibacterium and Bacteroides. These results stress the importance of the gut barrier function and immune response to commensal bacteria and point at the specific differences in pathogenesis of PSC-IBD, UC and CD.

"Candida Albicans Interactions With The Host: Crossing The Intestinal Epithelial Barrier"

Formerly a commensal organism of the mucosal surfaces of most healthy individuals, Candida albicans is an opportunistic pathogen that causes infections ranging from superficial to the more life-threatening disseminated infections, especially in the ever-growing population of vulnerable patients in the hospital setting. In these situations, the fungus takes advantage of its host following a disturbance in the host defense system and/or the mucosal microbiota. Overwhelming evidence suggests that the gastrointestinal tract is the main source of disseminated C. albicans infections. Major risk factors for disseminated candidiasis include damage to the mucosal intestinal barrier, immune dysfunction, and dysbiosis of the resident microbiota. A better understanding of C. albicans' interaction with the intestinal epithelial barrier will be useful for designing future therapies to avoid systemic candidiasis. In this review, we provide an overview of the current knowledge regarding the mechanisms of pathogenicity that allow the fungus to reach and translocate the gut barrier.

HDAC inhibitors promote intestinal epithelial regeneration via autocrine TGFβ1 signalling in inflammation

Intact epithelial barrier function is pivotal for maintaining intestinal homeostasis. Current therapeutic developments aim at restoring the epithelial barrier in inflammatory bowel disease. Histone deacetylase (HDAC) inhibitors are known to modulate immune responses and to ameliorate experimental colitis. However, their direct impact on epithelial barrier function and intestinal wound healing is unknown. In human and murine colonic epithelial cell lines, the presence of the HDAC inhibitors Givinostat and Vorinostat not only improved transepithelial electrical resistance under inflammatory conditions but also attenuated the passage of macromolecules across the epithelial monolayer. Givinostat treatment mediated an accelerated wound closure in scratch assays. In vivo, Givinostat treatment resulted in improved barrier recovery and epithelial wound healing in dextran sodium sulphate-stressed mice. Mechanistically, these regenerative effects could be linked to an increased secretion of transforming growth factor beta1 and interleukin 8, paralleled by differential expression of the tight junction proteins claudin-1, claudin-2 and occludin. Our data reveal a novel tissue regenerative property of the pan-HDAC inhibitors Givinostat and Vorinostat in intestinal inflammation, which may have beneficial implications by repurposing HDAC inhibitors for therapeutic strategies for inflammatory bowel disease.

Oral Administration of Bovine Lactoferrin-Derived Lactoferricin (Lfcin) B Could Attenuate Enterohemorrhagic Escherichia coli O157:H7 Induced Intestinal Disease through Improving Intestinal Barrier Function and Microbiota

Lactoferricin (Lfcin) B, derived from lactoferrin in whey, has attracted considerable attention because of its multiple biological functions. Zoonotic enterohemorrhagic Escherichia coli (EHEC) O157:H7 has adverse effects on intestinal epithelial barrier function, leading to serious intestinal disease. In this study, the EHEC O157:H7-induced intestinal dysfunction model was developed to investigate the effects of Lfcin B on EHEC O157:H7-induced epithelial barrier disruption and microbiota dysbiosis. Results showed that the inflammatory infiltration indexes in the jejunum of Lfcin B-treated animals were significantly decreased. Lfcin B administration also significantly improved ZO-1 and occludin expression following O157:H7-induced injury. Finally, microbiota analysis of the cecal samples revealed that Lfcin B inhibited the O157:H7-induced abnormal increase in Bacteroides. Therefore, Lfcin B efficiently attenuated O157:H7-induced epithelial barrier damage and dysregulation of inflammation status, while maintaining microbiota homeostasis in the intestine, indicating that it may be an excellent food source for prevention and therapy of EHEC O157:H7-related intestinal dysfunction.

The Influence of Heat-Killed Enterococcus faecium BGPAS1-3 on the Tight Junction Protein Expression and Immune Function in Differentiated Caco-2 Cells Infected With Listeria monocytogenes ATCC 19111

Listeria monocytogenes, the common foodborne pathogenic bacteria species, compromises the intestinal epithelial barrier, leading to development of the listeriosis, a severe disease especially among immunocompromised individuals. L. monocytogenes infection usually requires antibiotic treatment, however, excessive use of antibiotics promotes emergence of antibiotic resistance and the destruction of gut microbiota. Probiotics, including lactic acid bacteria (LAB), have been repeatedly proven as an alternative approach for the treatment of various infections. We have analyzed the potential of Enterococcus faecium BGPAS1-3, a dairy isolate exhibiting strong direct antilisterial effect, to modulate the response of differentiated Caco-2 intestinal epithelial cells to L. monocytogenes ATCC 19111 infection. We showed that the molecule with antilisterial effect is a bacterial cell-wall protein that is highly resistant to the high-temperature treatment. When we tested the antilisterial potential of heat-killed BGPAS1-3, we found that it could prevent tight junction disruption in differentiated Caco-2 monolayer infected with L. monocytogenes ATCC 19111, induce antilisterial host response mechanisms, and stimulate the production of protective TGF-β in intestinal epithelial cells. We also showed that the modulation of MyD88 dependent TLR2 and TLR4 pathways by BGPAS1-3 are involved in host response against L. monocytogenes ATCC 19111. Since heat-killed BGPAS1-3 possess strong antilisterial effects, such postbiotic could be used as a controllable and safe therapeutic.

Effects of putrescine on gene expression in relation to physical barriers and antioxidant capacity in organs of weaning piglets

Weaning stress can cause metabolic disorders, gastrointestinal dysfunction, physical barrier injury and disease susceptibility, thus leading to impaired growth and health of animals. Putrescine has the potential to reduce stress effects. However, the role of putrescine supplementation on barrier function and antioxidant capacity in animals' organs is largely unknown. This study evaluates the effects of putrescine on the physical barrier function, antioxidant status and related signalling molecule levels of weaning piglets' organs. A total of 24 weaning piglets were assigned to four treatment groups: (1) basal diet (control) and basal diets supplemented with (2) 0.05%, (3) 0.1% and (4) 0.15% putrescine. At the end of the 11 day experiment, ileum, liver, thymus and spleen samples were collected from the piglets. Compared with the control group, 0.15% putrescine can significantly increase anti-hydroxyl radical capacity (ileum and spleen), anti-superoxide anion capacity (liver, thymus and spleen), catalase (ileum, liver, thymus and spleen), total superoxide dismutase (ileum, thymus and spleen), glutathione peroxidase (ileum, liver and thymus), glutathione S-transferase activity (ileum, liver, thymus and spleen), glutathione content (liver and spleen) and total antioxidant capacity (ileum and thymus); decrease malondialdehyde (ileum, liver, thymus and spleen), protein carbonyl content (ileum, liver, thymus and spleen); enhance mRNA expression of zonula occludens (ZO)-1 (spleen), ZO-2 (liver, thymus and spleen), occludin (ileum, liver, thymus and spleen), claudin 1 (ileum, liver, thymus and spleen), claudin 2 (ileum, thymus and spleen), claudin 3 (ileum, liver, thymus and spleen), claudin 14 (ileum, liver and spleen), claudin 16 (ileum and liver), superoxide dismutase 1 (ileum, liver and thymus), glutathione peroxidase 1 (ileum, liver, thymus and spleen), catalase (ileum, liver, thymus and spleen), glutathione reductase (thymus and spleen), glutathione S-transferase (ileum, liver, thymus and spleen) and nuclear erythroid 2-related factor 2 (liver and thymus); decrease mRNA level of myosin light chain kinase (ileum, liver, thymus and spleen) and Kelch-like ECH-associated protein 1 (liver and spleen) (P < 0.05). 0.05% putrescine can significantly affect some of the above-mentioned parameters (P < 0.05). Collectively, putrescine supplementation improves organs' physical barrier function and antioxidant capacity in dose- and tissue-dependent and independent effects; such improvements are beneficial to the health of weaning piglets.

Weaning stress can cause metabolic disorders, gastrointestinal dysfunction, physical barrier injury and disease susceptibility, thus leading to impaired growth and health of animals.

Raw cow's milk consumption and allergic diseases - The potential role of bioactive whey proteins

The prevalence of allergic diseases has increased significantly in Western countries in the last decades. This increase is often explained by the loss of rural living conditions and associated changes in diet and lifestyle. In line with this 'hygiene hypothesis', several epidemiological studies have shown that growing up on a farm lowers the risk of developing allergic diseases. The consumption of raw, unprocessed, cow's milk seems to be one of the factors contributing to this protective effect. Recent evidence indeed shows an inverse relation between raw cow's milk consumption and the development of asthma and allergies. However, the consumption of raw milk is not recommended due to the possible contamination with pathogens. Cow's milk used for commercial purposes is therefore processed, but this milk processing is shown to abolish the allergy-protective effects of raw milk. This emphasizes the importance of understanding the components and mechanisms underlying the allergy-protective capacity of raw cow's milk. Only then, ways to produce a safe and protective milk can be developed. Since mainly heat treatment is shown to abolish the allergy-protective effects of raw cow's milk, the heat-sensitive whey protein fraction of raw milk is an often-mentioned source of the protective components. In this review, several of these whey proteins, their potential contribution to the allergy-protective effects of raw cow's milk and the consequences of heat treatment will be discussed. A better understanding of these bioactive whey proteins might eventually contribute to the development of new nutritional approaches for allergy management.

Artichoke Polyphenols Produce Skin Anti-Age Effects by Improving Endothelial Cell Integrity and Functionality

Artichoke is a characteristic crop of the Mediterranean area, recognized for its nutritional value and therapeutic properties due to the presence of bioactive components such as polyphenols, inulin, vitamins and minerals. Artichoke is mainly consumed after home and/or industrial processing, and the undersized heads, not suitable for the market, can be used for the recovery of bioactive compounds, such as polyphenols, for cosmetic applications. In this paper, the potential skin anti-age effect of a polyphenolic artichoke extract on endothelial cells was investigated. The methodology used was addressed to evaluate the antioxidant and anti-inflammatory activities and the improvement of gene expression of some youth markers. The results showed that the artichoke extract was constituted by 87% of chlorogenic, 3,5-O-dicaffeoylquinic, and 1,5-O-dicaffeoylquinic acids. The extract induced important molecular markers responsible for the microcirculation and vasodilatation of endothelial cells, acted as a potential anti-inflammatory agent, protected the lymphatic vessels from oxidative damage by ROS formation, and enhanced the cellular cohesion by reinforcing the tight junction complex. In addition, the artichoke extract, through the modulation of molecular pathways, improved the expression of genes involved in anti-ageing mechanisms. Finally, clinical testing on human subjects highlighted the enhancement by 19.74% of roughness and 11.45% of elasticity from using an artichoke extract cosmetic formulation compared to placebo cream.

Effects of Lactobacillus reuteri LR1 on the growth performance, intestinal morphology, and intestinal barrier function in weaned pigs

The objective of this study was to investigate the effects of Lactobacillus reuteri LR1, a new strain isolated from the feces of weaned pigs, on the growth performance, intestinal morphology, immune responses, and intestinal barrier function in weaned pigs. A total of 144 weaned pigs (Duroc × Landrace × Yorkshire, 21 d of age) with an initial BW of 6.49 ± 0.02 kg were randomly assigned to 3 dietary treatments with 8 replicate pens, each of per treatment and 6 pigs. Pigs were fed a basal diet (CON, controls), the basal diet supplemented with 100 mg/kg olaquindox and 75 mg/kg aureomycin (OA) or the basal diet supplemented with 5 × 1010 cfu/kg L. reuteri LR1 for a 14-d period. At the end of study, the ADG, ADFI, and G:F were calculated, and 1 randomly selected pig from each pen was euthanized for sample collection. The LR1 increased ADG (22.73%, P < 0.05) compared with CON. The villus height of the ileum was increased (P < 0.05) and crypt depth in duodenum was reduced (P < 0.05), along with increased (P < 0.05) villus height to crypt depth ratio of the jejunum and ileum by LR1 compared with CON and OA. LR1 increased (P < 0.05) ileal mucosal content of IL-22 and transforming growth factor-β compared with OA. Compared with CON, LR1 increased (P < 0.05) and OA decreased (P < 0.05) the ileal content of secretory immunoglobulin A (sIgA), and the abundance of transcripts of porcine β-defensin 2 and protegrin 1-5. Compared with CON, LR1 increased (P < 0.05) tight junction protein zonula occludens-1 and occludin transcripts in the mucosa of the jejunum and ileum, and those of mucin-2 in ileal mucosa. The relative expression of toll-like receptor 2 (TLR2) and TLR4 were increased (P < 0.05) in ileal mucosa in pigs fed LR1 compared with CON. In conclusion, these data indicated that dietary LR1 supplementation at 5 × 1010 cfu/kg improved growth performance, intestinal morphology, and intestinal barrier function in weaned pigs.

Functional diversification of the NleG effector family in enterohemorrhagic Escherichia coli

The pathogenic strategy of Escherichia coli and many other gram-negative pathogens relies on the translocation of a specific set of proteins, called effectors, into the eukaryotic host cell during infection. These effectors act in concert to modulate host cell processes in favor of the invading pathogen. Injected by the type III secretion system (T3SS), the effector arsenal of enterohemorrhagic E. coli (EHEC) O157:H7 features at least eight individual NleG effectors, which are also found across diverse attaching and effacing pathogens. NleG effectors share a conserved C-terminal U-box E3 ubiquitin ligase domain that engages with host ubiquitination machinery. However, their specific functions and ubiquitination targets have remained uncharacterized. Here, we identify host proteins targeted for ubiquitination-mediated degradation by two EHEC NleG family members, NleG5-1 and NleG2-3. NleG5-1 localizes to the host cell nucleus and targets the MED15 subunit of the Mediator complex, while NleG2-3 resides in the host cytosol and triggers degradation of Hexokinase-2 and SNAP29. Our structural studies of NleG5-1 reveal a distinct N-terminal α/β domain that is responsible for interacting with host protein targets. The core of this domain is conserved across the NleG family, suggesting this domain is present in functionally distinct NleG effectors, which evolved diversified surface residues to interact with specific host proteins. This is a demonstration of the functional diversification and the range of host proteins targeted by the most expanded effector family in the pathogenic arsenal of E. coli.

Transforming Growth Factor-β1/Smad7 in Intestinal Immunity, Inflammation, and Cancer

In physiological conditions, the activity of the intestinal immune system is tightly regulated to prevent tissue-damaging reactions directed against components of the luminal flora. Various factors contribute to maintain immune homeostasis and diminished production and/or function of such molecules trigger and/or propagate detrimental signals, which can eventually lead to chronic colitis and colon cancer. One such a molecule is transforming growth factor-β1 (TGF-β1), a cytokine produced by many inflammatory and non-inflammatory cells and targeting virtually all the intestinal mucosal cell types, with the down-stream effect of activating intracellular Smad2/3 proteins and suppressing immune reactions. In patients with inflammatory bowel diseases (IBD), there is defective TGF-β1/Smad signaling due to high Smad7, an inhibitor of TGF-β1 activity. Indeed, knockdown of Smad7 with a specific antisense oligonucleotide restores endogenous TGF-β1 activity, thereby inhibiting inflammatory pathways in patients with IBD and colitic mice. Consistently, mice over-expressing Smad7 in T cells develop severe intestinal inflammation in various experimental models. Smad7 expression is also upregulated in colon cancer cells, in which such a protein controls positively intracellular pathways that sustain neoplastic cell growth and survival. We here review the role of TGF-β1 and Smad7 in intestinal immunity, inflammation, and cancer.

Cytokines in milk and the role of TGF-beta

Cytokines are required for normal growth and development of the mammary gland and TGF-β prominently represents an established effector of apoptosis, e.g., during involution of the mammary gland. By the control of intracellular signaling pathways, including JAK/STAT, MAPK, PI-3K, and NF-κB, cytokines efficiently regulate cell proliferation and inflammation in the breast. Therefore, cytokines are discussed also in a context of malignant mammary growth. As a group of tissue hormones produced by somatic cells or by cells from the immune system, cytokines are defined by their immunomodulatory potential. Over the past 40 years, multiple cytokines were identified in colostrum and milk. Importantly, cytokines derived from mammary secretions after birth are required for maturation of the immune system in the developing gastrointestinal tract from the suckling. Moreover, recent studies have further assessed the particular interactions between probiotic bacterial strains and cytokines. In light of the increasing prevalence of inflammatory diseases of the gastrointestinal system, the effects of probiotic microorganisms during milk fermentation may have immunotherapeutic potential in the future.

Glycomacropeptide Reduces Intestinal Epithelial Cell Barrier Dysfunction and Adhesion of Entero-Hemorrhagic and Entero-Pathogenic Escherichia coli in Vitro

In recent years, the potential of glycosylated food components to positively influence health has received considerable attention. Milk is a rich source of biologically active glycoconjugates which are associated with antimicrobial, immunomodulatory, anti-adhesion, anti-inflammatory and prebiotic properties. Glycomacropeptide (GMP) is the C-terminal portion of kappa-casein that is released from whey during cheese-making by the action of chymosin. Many of the biological properties associated with GMP, such as anti-adhesion, have been linked with the carbohydrate portion of the protein. In this study, we investigated the ability of GMP to inhibit the adhesion of a variety of pathogenic Escherichia coli strains to HT-29 and Caco-2 intestinal cell lines, given the importance of E. coli in causing bacterial gastroenteritis. GMP significantly reduced pathogen adhesion, albeit with a high degree of species specificity toward enteropathogenic E. coli (EPEC) strains O125:H32 and O111:H2 and enterohemorrhagic E. coli (EHEC) strain 12900 O157:H7. The anti-adhesive effect resulted from the interaction of GMP with the E. coli cells and was also dependent on GMP concentration. Pre-incubation of intestinal Caco-2 cells with GMP reduced pathogen translocation as represented by a decrease in transepithelial electrical resistance (TEER). Thus, GMP is an effective in-vitro inhibitor of adhesion and epithelial injury caused by E. coli and may have potential as a biofunctional ingredient in foods to improve gastrointestinal health.

From clinical uncertainties to precision medicine: the emerging role of the gut barrier and microbiome in small bowel functional diseases

Over the last decade, remarkable progress has been made in the understanding of disease pathophysiology. Many new theories expound on the importance of emerging factors such as microbiome influences, genomics/omics, stem cells, innate intestinal immunity or mucosal barrier complexities. This has introduced a further dimension of uncertainty into clinical decision-making, but equally, may shed some light on less well-understood and difficult to manage conditions. Areas covered: Comprehensive review of the literature on gut barrier and microbiome relevant to small bowel pathology. A PubMed/Medline search from 1990 to April 2017 was undertaken and papers from this range were included. Expert commentary: The scenario of clinical uncertainty is well-illustrated by functional gastrointestinal disorders (FGIDs). The movement towards achieving a better understanding of FGIDs is expressed in the Rome IV guidelines. Novel diagnostic and therapeutic protocols focused on the GB and SB microbiome can facilitate diagnosis, management and improve our understanding of the underlying pathological mechanisms in FGIDs.

TGF-β in inflammatory bowel disease: a key regulator of immune cells, epithelium, and the intestinal microbiota

Inflammatory bowel disease (IBD) is defined as chronic intestinal inflammation, and includes ulcerative colitis and Crohn's disease. Multiple factors are involved in the pathogenesis of IBD, and the condition is characterized by aberrant mucosal immune reactions to intestinal microbes in genetically susceptible hosts. Transforming growth factor-β (TGF-β) is an immune-suppressive cytokine produced by many cell types and activated by integrins. Active TGF-β binds to its receptor and regulates mucosal immune reactions through the TGF-β signaling pathway. Dysregulated TGF-β signaling is observed in the intestines of IBD patients. TGF-β signal impairment in specific cell types, such as T-cells and dendritic cells, results in spontaneous colitis in mouse models. In addition, specific intestinal microbes contribute to immune homeostasis by modulating TGF-β production. In this review, we describe the role of TGF-β in intestinal immunity, focusing on immune cells, epithelium, and intestinal microbes. In addition, we present potential therapeutic strategies for IBD that target TGF-β.

The effect of feed supplementation with effective microorganisms (EM) on pro- and anti-inflammatory cytokine concentrations in pigs

Effective microorganisms (EM) are used in numerous fields associated with agriculture. The beneficial effects of EM on the general health of pigs and on production parameters are also determined by the influence of these microbes on immunity. The aim of the study was to assess the effect of feed supplementation with EM on the concentration of pro- and anti-inflammatory cytokines in the serum and in a culture of PBMCs with and without ConA stimulation in pigs. ELISA kits were used to determine the cytokine levels in the porcine serum and the PBMC culture supernatants. Evaluation of the serum concentration of cytokines revealed statistically significantly higher concentrations of IL-2, IL-4, IL-10, IFN-γ and TNF-α in the pigs receiving EM Bokashi. The highest concentration of TGF-β in the experimental group was noted on the final test day. Evaluation of cytokine concentrations in the PBMC cultures revealed statistically significantly higher concentrations of IL-2, IL-4 and IL-10 from the third day of the experiment. Statistically significantly higher concentrations of TNF-α were obtained in the unstimulated PBMC culture on the second test day and in the culture treated with ConA on the second and the third test days. The results of our study indicate that supplementation of pig feed with EM Bokashi activates the cell-mediated and humoral immune response, ensuring that Th1/Th2 balance is maintained and enhancing immune processes protecting the body against infection.

Tangshen Formula Attenuates Colonic Structure Remodeling in Type 2 Diabetic Rats

Aim. This study investigated the effect and mechanism of the Chinese herbal medicine Tangshen Formula (TSF) on GI structure remodeling in the rat model of diabetes. Methods. Type 2 diabetic rats were used. Wet weight per unit length, layer thicknesses, levels of collagens I and III, nuclear factor kappa B (NF-κB), interferon-γ (IFN-γ), interleukin-6 (IL-6), transforming growth factor-β1 (TGF-β1), and Smad2/3 expression in the rat colon were measured. Results. Compared with the control group animals, wet weight and layer thicknesses of the colon increased, and expressions of collagens I and III, NF-κB, IFN-γ, IL-6, TGF-β1, and Smad2/3 increased significantly in the diabetic animals. TSF inhibited increase in colonic wet weight and layer thicknesses, downregulated expressions of collagens I and III in the mucosal layer, and downregulated expressions of NF-κB, IFN-γ, IL-6, TGF-β1, and Smad2/3 in the colon wall. Furthermore, level of expression of NF-κB was associated with those of TGF-β1 and Smad2/3. Expression of TGF-β1 was associated with the most histomorphometric parameters including colonic weight, mucosal and muscle thicknesses, and levels of collagens I and III in mucosal layer. Conclusion. TSF appears to attenuate colonic structure remodeling in type 2 diabetic rats through inhibiting the overactivated pathway of NF-κB, thus reducing expressions of TGF-β1.

Zinc reduces epithelial barrier compromise induced by human seminal plasma

Human semen has the potential to modulate the epithelial mucosal tissues it contacts, as seminal plasma (SP) is recognized to contain both pro- and anti-barrier components, yet its effects on epithelial barrier function are largely unknown. We addressed the role of human SP when exposed to the basal-lateral epithelial surface, a situation that would occur clinically with prior mechanical or disease-related injury of the human epithelial mucosal cell layers in contact with semen. The action of SP on claudins-2, -4, -5, and -7 expression, as well as on a target epithelium whose basolateral surface has been made accessible to SP, showed upregulation of claudins-4 and -5 in CACO-2 human epithelial cell layers, despite broad variance in SP-induced modulation of transepithelial electrical resistance and mannitol permeability. Upregulation of claudin-2 by SP also exhibited such variance by SP sample. We characterize individual effects on CACO-2 barrier function of nine factors known to be present abundantly in seminal plasma (zinc, EGF, citrate, spermine, fructose, urea, TGF, histone, inflammatory cytokines) to establish that zinc, spermine and fructose had significant potential to raise CACO-2 transepithelial resistance, whereas inflammatory cytokines and EGF decreased this measure of barrier function. The role of zinc as a dominant factor in determining higher levels of transepithelial resistance and lower levels of paracellular leak were confirmed by zinc chelation and exogenous zinc addition. As expected, SP presentation to the basolateral cell surface also caused a very dramatic yet transient elevation of pErk levels. Results suggest that increased zinc content in SP can compete against the barrier-compromising effect of negative modulators in SP when SP gains access to that epithelium's basolateral surface. Prophylactic elevation of zinc in an epithelial cell layer prior to contact by SP may help to protect an epithelial barrier from invasion by SP-containing STD microbial pathogens such as HPV or HIV.

Homeostasis of the gut barrier and potential biomarkers

The gut barrier plays a crucial role by spatially compartmentalizing bacteria to the lumen through the production of secreted mucus and is fortified by the production of secretory IgA (sIgA) and antimicrobial peptides and proteins. With the exception of sIgA, expression of these protective barrier factors is largely controlled by innate immune recognition of microbial molecular ligands. Several specialized adaptations and checkpoints are operating in the mucosa to scale the immune response according to the threat and prevent overreaction to the trillions of symbionts inhabiting the human intestine. A healthy microbiota plays a key role influencing epithelial barrier functions through the production of short-chain fatty acids (SCFAs) and interactions with innate pattern recognition receptors in the mucosa, driving the steady-state expression of mucus and antimicrobial factors. However, perturbation of gut barrier homeostasis can lead to increased inflammatory signaling, increased epithelial permeability, and dysbiosis of the microbiota, which are recognized to play a role in the pathophysiology of a variety of gastrointestinal disorders. Additionally, gut-brain signaling may be affected by prolonged mucosal immune activation, leading to increased afferent sensory signaling and abdominal symptoms. In turn, neuronal mechanisms can affect the intestinal barrier partly by activation of the hypothalamus-pituitary-adrenal axis and both mast cell-dependent and mast cell-independent mechanisms. The modulation of gut barrier function through nutritional interventions, including strategies to manipulate the microbiota, is considered a relevant target for novel therapeutic and preventive treatments against a range of diseases. Several biomarkers have been used to measure gut permeability and loss of barrier integrity in intestinal diseases, but there remains a need to explore their use in assessing the effect of nutritional factors on gut barrier function. Future studies should aim to establish normal ranges of available biomarkers and their predictive value for gut health in human cohorts.

Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens

Maintaining a healthy gut environment is a prerequisite for sustainable animal production. The gut plays a key role in the digestion and absorption of nutrients and constitutes an initial organ exposed to external factors influencing bird’s health. The intestinal epithelial barrier serves as the first line of defense between the host and the luminal environment. It consists of a continuous monolayer of intestinal epithelial cells connected by intercellular junctional complexes which shrink the space between adjacent cells. Consequently, free passing of solutes and water via the paracellular pathway is prevented. Tight junctions (TJs) are multi-protein complexes which are crucial for the integrity and function of the epithelial barrier as they not only link cells but also form channels allowing permeation between cells, resulting in epithelial surfaces of different tightness. Tight junction’s molecular composition, ultrastructure, and function are regulated differently with regard to physiological and pathological stimuli. Both in vivo and in vitro studies suggest that reduced tight junction integrity greatly results in a condition commonly known as “leaky gut”. A loss of barrier integrity allows the translocation of luminal antigens (microbes, toxins) via the mucosa to access the whole body which are normally excluded and subsequently destroys the gut mucosal homeostasis, coinciding with an increased susceptibility to systemic infection, chronic inflammation and malabsorption. There is considerable evidence that the intestinal barrier dysfunction is an important factor contributing to the pathogenicity of some enteric bacteria. It has been shown that some enteric pathogens can induce permeability defects in gut epithelia by altering tight junction proteins, mediated by their toxins. Resolving the strategies that microorganisms use to hijack the functions of tight junctions is important for our understanding of microbial pathogenesis, because some pathogens can utilize tight junction proteins as receptors for attachment and subsequent internalization, while others modify or destroy the tight junction proteins by different pathways and thereby provide a gateway to the underlying tissue. This review aims to deliver an overview of the tight junction structures and function, and its role in enteric bacterial pathogenesis with a special focus on chickens. A main conclusion will be that the molecular mechanisms used by enteric pathogens to disrupt epithelial barrier function in chickens needs a much better understanding, explicitly highlighted for Campylobacter jejuni, Salmonella enterica and Clostridium perfringens. This is a requirement in order to assist in discovering new strategies to avoid damages of the intestinal barrier or to minimize consequences from infections.

TGF-β1 protects intestinal integrity and influences Smads and MAPK signal pathways in IPEC-J2 after TNF-α challenge

The aim of this study was to investigate the protective effects of TGF-β1 on intestinal epithelial barrier, as well as canonical Smad and MAPK signal pathways involved in these protection processes by a IPEC-J2 model stimulated with TNF-α. IPEC-J2 monolayers were treated without or with TNF-α in the absence or presence of TGF-β1. The results showed that TGF-β1 pretreatment ameliorated TNF-α-induced intestinal epithelial barrier disturbances as indicated by decrease of transepithelial electrical resistance (TER) and increase of paracellular permeability. TGF-β1 also dramatically alleviated TNF-α-induced alteration of TJ proteins ZO-1 and occludin. Moreover, TGF-β1 pretreatment increased TβRII protein expression in IPEC-J2 monolayers challenged with TNF-α. In addition, a significant increase of Smad4 and Smad7 mRNA was also observed in the TGF-β1 pretreatment after TNF-α challenge compared with the control group. Furthermore, TGF-β1 pretreatment enhanced smad2 protein activation. These results indicated that the canonical Smad signaling pathway was activated by TGF-β1 pretreatment. Finally, TGF-β1 pretreatment decreased the ratios of the phosphorylated to total JNK and p38 (p-JNK/JNK and p-p38/p38) and increased the ratio of ERK (p-ERK/ERK). Anti-TGF-β1 Abs reduced these TGF-β1 effects. These results indicated that TGF-β1 protects intestinal integrity and influences Smad and MAPK signal pathways in IPEC-J2 after TNF-α challenge.

Long-term reduction in food allergy susceptibility in mice by combining breastfeeding-induced tolerance and TGF-β-enriched formula after weaning

BACKGROUND

Oral tolerance induction in early life is a promising approach for food allergy prevention. Its success requires the identification of factors necessary for its persistence.

OBJECTIVES

We aimed to assess in mice duration of allergy prevention by breastfeeding-induced oral tolerance and whether oral TGF-β supplementation after weaning would prolong it.

METHODS

We quantified ovalbumin (OVA) and OVA-specific immunoglobulin levels by ELISA in milk from the EDEN birth cohort. As OVA-specific Ig was found in all samples, we assessed whether OVA-immunized mice exposed to OVA during lactation could prevent allergic diarrhoea in their 6- and 13-week-old progeny. In some experiments, a TGF-β-enriched formula was given after weaning.

RESULTS

At 6 weeks, only 13% and 34% of mice breastfed by OVA-exposed mothers exhibited diarrhoea after six and seven OVA challenges vs. 44% and 72% in mice breastfed by naïve mothers (P = 0.02 and 0.01). Protection was associated with decreased levels of MMCP1 and OVA-specific IgE (P < 0.0001). At 13 weeks, although OVA-specific IgE remained low (P = 0.001), diarrhoea occurrence increased to 32% and 46% after six and seven OVA challenges in mice breastfed by OVA-exposed mothers. MMCP1 levels were not significantly inhibited. Supplementation with TGF-β after weaning induced a strong protection in 13-week-old mice breastfed by OVA-exposed mothers compared with mice breastfed by naive mothers (0%, 13% and 32% of diarrhoea at the fifth, sixth and seventh challenges vs. 17, 42 and 78%; P = 0.05, 0.0043 and 0.0017). MMCP1 levels decreased by half compared with control mice (P = 0.02). Prolonged protection was only observed in mice rendered tolerant by breastfeeding and was associated with an improved gut barrier.

CONCLUSIONS

In mice, prevention of food allergy by breastfeeding-induced tolerance is of limited duration. Nutritional intervention by TGF-β supplementation after weaning could prolong beneficial effects of breast milk on food allergy prevention.

Cathelicidin-WA Improves Intestinal Epithelial Barrier Function and Enhances Host Defense against Enterohemorrhagic Escherichia coli O157:H7 Infection

Impaired epithelial barrier function disrupts immune homeostasis and increases inflammation in intestines, leading to many intestinal diseases. Cathelicidin peptides suppress intestinal inflammation and improve intestinal epithelial barrier function independently of their antimicrobial activity. In this study, we investigated the effects of Cathelicidin-WA (CWA) on intestinal epithelial barrier function, as well as the underlying mechanism, by using enterohemorrhagic Escherichia coli (EHEC)-infected mice and intestinal epithelial cells. The results showed that CWA attenuated EHEC-induced clinical symptoms and intestinal colitis, as did enrofloxacin (Enro). CWA decreased IL-6 production in the serum, jejunum, and colon of EHEC-infected mice. Additionally, CWA alleviated the EHEC-induced disruption of mucin-2 and goblet cells in the intestine. Interestingly, CWA increased the mucus layer thickness, which was associated with increasing expression of trefoil factor 3, in the jejunum of EHEC-infected mice. CWA increased the expression of tight junction proteins in the jejunum of EHEC-infected mice. Using intestinal epithelial cells and a Rac1 inhibitor in vitro, we demonstrated that the CWA-mediated increases in the tight junction proteins might depend on the Rac1 pathway. Furthermore, CWA improved the microbiota and short-chain fatty acid concentrations in the cecum of EHEC-infected mice. Although Enro and CWA had similar effects on intestinal inflammation, CWA was superior to Enro with regard to improving intestinal epithelial barrier and microbiota in the intestine. In conclusion, CWA attenuated EHEC-induced inflammation, intestinal epithelial barrier damage, and microbiota disruption in the intestine of mice, suggesting that CWA may be an effective therapy for many intestinal diseases.

The Anti-Inflammatory Effect of Spray-Dried Plasma Is Mediated by a Reduction in Mucosal Lymphocyte Activation and Infiltration in a Mouse Model of Intestinal Inflammation

Spray-dried preparations from porcine and bovine plasma can alleviate mucosal inflammation in experimental models and improve symptoms in patients with enteropathy. In rodents, dietary supplementation with porcine spray-dried plasma (SDP) attenuates intestinal inflammation and improves the epithelial barrier function during intestinal inflammation induced by Staphylococcus aureus enterotoxin B (SEB). The aim of this study was to discern the molecular mechanisms involved in the anti-inflammatory effects of SDP. Male C57BL/6 mice were fed with 8% SDP or control diet (based on milk proteins) for two weeks, from weaning until day 33. On day 32, the mice were given a SEB dose (i.p., 25 µg/mouse) or vehicle. SEB administration increased cell recruitment to mesenteric lymph nodes and the percentage of activated Th lymphocytes and SDP prevented these effects). SDP supplementation increased the expression of interleukin 10 (IL-10) or transforming growth factor- β (TGF-β) compared to the SEB group. The SEB challenge increased six-fold the expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) and intercellular adhesion molecule 1 (ICAM-1); and these effects were attenuated by SDP supplementation. SEB also augmented NF-κB phosphorylation, an effect that was prevented by dietary SDP. Our results indicate that the anti-inflammatory effects of SDP involve the regulation of transcription factors and adhesion molecules that reduce intestinal cell infiltration and the degree of the inflammatory response.

Early Activation of MAPK p44/42 Is Partially Involved in DON-Induced Disruption of the Intestinal Barrier Function and Tight Junction Network

Deoxynivalenol (DON), produced by the plant pathogens Fusarium graminearum and Fusarium culmorum, is one of the most common mycotoxins, contaminating cereal and cereal-derived products. Although worldwide contamination of food and feed poses health threats to humans and animals, pigs are particularly susceptible to this mycotoxin. DON derivatives, such as deepoxy-deoxynivalenol (DOM-1), are produced by bacterial transformation of certain intestinal bacteria, which are naturally occurring or applied as feed additives. Intestinal epithelial cells are the initial barrier against these food- and feed-borne toxins. The present study confirms DON-induced activation of MAPK p44/42 and inhibition of p44/42 by MAPK-inhibitor U0126 monoethanolate. Influence of DON and DOM-1 on transepithelial electrical resistance (TEER), viability and expression of seven tight junction proteins (TJ), as well as the potential of U0126 to counteract DON-induced effects, was assessed. While DOM-1 showed no effect, DON significantly reduced TEER of differentiated IPEC-J2 and decreased expression of claudin-1 and -3, while leaving claudin-4; ZO-1, -2, and -3 and occludin unaffected. Inhibition of p44/42 counteracted DON-induced TEER decrease and restored claudin-3, but not claudin-1 expression. Therefore, effects of DON on TEER and claudin-3 are at least partially p44/42 mediated, while effects on viability and claudin-1 are likely mediated via alternative pathways.

Increased Prevalence of Inflammatory Bowel Disease in Patients with Mutations in Genes Encoding the Receptor Subunits for TGFβ

BACKGROUND

TGFβ is a multifunctional cytokine that is critical in regulating mucosal immunity. Murine studies have revealed that disruption of canonical TGFβ signaling leads to systemic inflammation including colitis. Loeys-Dietz syndrome (LDS) results from heterozygous mutations in the genes encoding the subunits of the TGFβ receptor.

METHODS

All patients with confirmed mutations in TGFBR1 or TGFBR2, seen in the Johns Hopkins Connective Tissue Disorders clinic, were asked to participate in the study. Ninety-three consecutive patients were enrolled, including 4 with inflammatory bowel disease (IBD). Using the Illumina Immunochip array, we undertook an exploratory analysis to evaluate the potential genetic risk factors that could predict which patients with LDS would develop IBD.

RESULTS

We report an increased prevalence of IBD in patients with LDS types I and II. We describe the course of several patients. In this small sample, the 3 whites with IBD had a genetic risk score in the top 6 highest scores of patients evaluated.

CONCLUSION

We report a 10-fold increase in the prevalence of IBD in patients with LDS compared with the general population. Onset of disease in 3 of the 4 patients was at less than 18 years, and the clinical course in 2 of the 4 was severe with a poor response to traditional medications. Further evaluation of the genetic risk score is needed to determine whether it can predict which patients with LDS are most likely to develop IBD. This case series of patients with LDS with IBD suggests that defective TGFβ signaling may have an influence on IBD risk.

Regulation of endothelial and epithelial barrier functions by peptide hormones of the adrenomedullin family

The correct regulation of tissue barriers is of utmost importance for health. Barrier dysfunction accompanies inflammatory disorders and, if not controlled properly, can contribute to the development of chronic diseases. Tissue barriers are formed by monolayers of epithelial cells that separate organs from their environment, and endothelial cells that cover the vasculature, thus separating the blood stream from underlying tissues. Cells within the monolayers are connected by intercellular junctions that are linked by adaptor molecules to the cytoskeleton, and the regulation of these interactions is critical for the maintenance of tissue barriers. Many endogenous and exogenous molecules are known to regulate barrier functions in both ways. Proinflammatory cytokines weaken the barrier, whereas anti-inflammatory mediators stabilize barriers. Adrenomedullin (ADM) and intermedin (IMD) are endogenous peptide hormones of the same family that are produced and secreted by many cell types during physiologic and pathologic conditions. They activate certain G-protein-coupled receptor complexes to regulate many cellular processes such as cytokine production, actin dynamics and junction stability. In this review, we summarize current knowledge about the barrier-stabilizing effects of ADM and IMD in health and disease.

Indomethacin induces increase in gastric epithelial tight junction permeability via redistribution of occludin and activation of p38 MAPK in MKN-28 Cells

Tight Junctions (TJ) create a paracellular barrier that is compromised when nonsteriodal anti-inflammatory drugs (NSAIDs) injure the gastric epithelium, leading to increased permeability. However, the mechanism of NSAID-induced gastric injury is unclear. Here, we examined the effect of indomethacin on barrier function and TJ in gastric MKN-28 cells. In concentration response studies, 500 µm indomethacin induced a significant decrease in transepithelial resistance (TER; 380 vs. 220 Ω·cm(2) for control and indomethacin-treated cells respectively, p < 0.05), and increased dextran permeability by 0.2 vs 1.2 g/l (p < 0.05). These changes in barrier function were completely ameliorated by the p38 MAPK inhibitor (SB-203580) but not by JNK inhibitor (SP-600125) or MEK/ERK inhibitor (PD-98059). SiRNA knock down of p38 MAPK prevented the loss of barrier function caused by indomethacin in MKN-28 cells. Western analyses of TJ proteins revealed that expression of occludin was reduced by indomethacin, whereas there was no change in other TJ proteins. The loss of occludin expression induced by indomethacin was prevented by inhibition of p38 MAPK but not JNK or ERK and also by siRNA of p38 MAPK. Immunofluorescence revealed disruption of occludin localization at the site of the tight junction in indomethacin-treated cells, and this was attenuated by inhibition of p38 MAPK. NSAID injury to murine gastric mucosa on Ussing chambers revealed that indomethacin caused a significant drop in TER and increased paracellular permeability. Pretreatment with the p38 MAPK inhibitor significantly attenuated the disruption of barrier function, but JNK and MEK/ERK inhibition had no effect. Western blot analysis on gastric mucosa reveled loss of TJ protein occludin by indomethacin, which was prevented by inhibition of p38 MAPK. This data suggests that indomethacin compromises the gastric epithelial barrier via p38 MAPK inducing occludin alterations in the TJs.

Effects of Piper sarmentosum extract on the growth performance, antioxidant capability and immune response in weaned piglets

The biological properties of Piper sarmentosum render it a potential substitute for antibiotics in livestock feed. This study evaluated the effects of P. sarmentosum extract (PSE) on the growth performance, antioxidant capability and immune response of weaned piglets. Eighty 21-d-old weaned piglets were selected and randomly allocated to one of four dietary treatments with five replicates of four pigs each. The dietary treatments consisted of a basal diet supplemented with 0 (T0), 50 (T50), 100 (T100) or 200 (T200) mg/kg PSE. The feeding trial lasted 4 weeks. The results revealed that the T50 group had the highest average daily gain (ADG) and average daily feed intake (ADFI) throughout the feeding trial (p < 0.05). Additionally, the T50 group had higher (p < 0.05) serum glutathione peroxidase activity (GSH-Px) and lower (p < 0.05) serum malondialdehyde (MDA) levels than the T0 group at 4 weeks post-weaning (p < 0.05). Serum levels of interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α) decreased, while serum levels of interleukin-4 (IL-4), interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) increased by PSE supplementation at 4 weeks post-weaning (p < 0.05). PSE supplementation upregulated the mRNA expression of IL-4, IL-10 and TGF-β and downregulated the mRNA expression of TNF-α, IL-1β and interleukin-6 (IL-6) in the ileal mucosal layer of piglets (p < 0.05). In summary, our study findings revealed that PSE supplementation improved the antioxidant capability, and reduced inflammation, which may be beneficial to weaned piglet health.

Whey protein concentrate enhances intestinal integrity and influences transforming growth factor-β1 and mitogen-activated protein kinase signalling pathways in piglets after lipopolysaccharide challenge

Whey protein concentrate (WPC) has been reported to have protective effects on the intestinal barrier. However, the molecular mechanisms involved are not fully elucidated. Transforming growth factor-β1 (TGF-β1) is an important component in the WPC, but whether TGF-β1 plays a role in these processes is not clear. The aim of this study was to investigate the protective effects of WPC on the intestinal epithelial barrier as well as whether TGF-β1 is involved in these protection processes in a piglet model after lipopolysaccharide (LPS) challenge. In total, eighteen weanling pigs were randomly allocated to one of the following three treatment groups: (1) non-challenged control and control diet; (2) LPS-challenged control and control diet; (3) LPS+5 %WPC diet. After 19 d of feeding with control or 5 %WPC diets, pigs were injected with LPS or saline. At 4 h after injection, pigs were killed to harvest jejunal samples. The results showed that WPC improved (P<0·05) intestinal morphology, as indicated by greater villus height and villus height:crypt depth ratio, and intestinal barrier function, which was reflected by increased transepithelial electrical resistance and decreased mucosal-to-serosal paracellular flux of dextran (4 kDa), compared with the LPS group. Moreover, WPC prevented the LPS-induced decrease (P<0·05) in claudin-1, occludin and zonula occludens-1 expressions in the jejunal mucosae. WPC also attenuated intestinal inflammation, indicated by decreased (P<0·05) mRNA expressions of TNF-α, IL-6, IL-8 and IL-1β. Supplementation with WPC also increased (P<0·05) TGF-β1 protein, phosphorylated-Smad2 expression and Smad4 and Smad7 mRNA expressions and decreased (P<0·05) the ratios of the phosphorylated to total c-jun N-terminal kinase (JNK) and p38 (phospho-JNK:JNK and p-p38:p38), whereas it increased (P<0·05) the ratio of extracellular signal-regulated kinase (ERK) (phospho-ERK:ERK). Collectively, these results suggest that dietary inclusion of WPC attenuates the LPS-induced intestinal injury by improving mucosal barrier function, alleviating intestinal inflammation and influencing TGF-β1 canonical Smad and mitogen-activated protein kinase signalling pathways.

Rearing conditions affected responses of weaned pigs to organic acids showing a positive effect on digestibility, microflora and immunity

Three experiments were conducted to assess the response of weaned pigs to organic acid SF3, which contains 34% calcium formate, 16% calcium lactate, 7% citric acid and 13% medium chain fatty acids. Dietary treatments had no effect on growth performance of piglets (21-day weaning) fed the commercial prestart diet for 1 week before receiving the experimental diets supplemented with SF3 at 0, 3 or 5 g/kg diet (Exp. 1), whereas diarrhea frequency averaged across a week was decreased by SF3 supplementation (5 g/kg diet) in piglets fed the experimental diets immediately after weaning (Exp. 2). In Exp. 3, piglets (28-day weaning) were fed the control (containing pure colistin sulfate and enramycin, respectively, at 20 mg/kg diet) for 1 week and then were fed the control or SF3-supplemented (5 g/kg diet) diet for 2 weeks. The SF3-fed piglets had greater apparent ileal digestibility of calcium and dry matter, while also demonstrating greater overall gross energy, up-regulated jejunal expression of sodium-glucose cotransporter-1 and transforming growth factor-β, down-regulated jejunal expression of tumor necrosis factor (TNF)-α, higher ileal Lactobacillus, with lower total bacteria content, lower plasma TNF-α but higher IgG levels than the control-fed piglets. Collectively, SF3 consumption improved diarrhea resistance of weaned pigs by improving nutrient digestibility, piglet immunity and intestinal bacteria profile. © 2016 Japanese Society of Animal Science.

Transforming growth factor-β1 protects against intestinal epithelial barrier dysfunction caused by hypoxia-reoxygenation

Intestinal epithelia regulate barrier integrity when challenged by inflammation, oxidative stress, and microbes. Transforming growth factor-β1 (TGF-β1) is a cytokine with known beneficial effects on intestinal epithelia, including barrier enhancement, after exposure to proinflammatory cytokines and infectious agents. The aim of this study was to determine whether TGF-β1 directly protects intestinal epithelia during hypoxia-reoxygenation (HR). Intestinal epithelial monolayers (T84, Caco-2) were exposed to either hypoxia (1% O2, 1 h) or oxidative stress (hydrogen peroxide, 1 mM), followed by normoxic atmosphere for different time points in the absence and presence of varying concentrations of TGF-β1. Transepithelial electrical resistance (TER) assessed barrier function, with RNA extracted for reverse transcription polymerase chain reaction analysis of GPx-1, HIF-1, heme-oxygenase-1 (HO-1), and NOX-1. In some experiments, intestinal epithelia were exposed to enterohemorrhagic Escherichia coli (EHEC) O157:H7 during the reoxygenation period and TER recorded 7 h after the infectious challenge. Hypoxia-reoxygenation significantly decreased TER in intestinal epithelia compared with normoxic controls. Transforming growth factor-β1 pretreatment ameliorated HR-induced epithelial barrier dysfunction in T84 (at 1 - 3 h) and Caco-2 (1 h) monolayers. Transforming growth factor-β1 preserved barrier integrity for up to 16 h after challenge with hydrogen peroxide. In TGF-β1-treated epithelial monolayers, only HO-1 mRNA significantly increased after HR (P < 0.05 vs. normoxic controls). The EHEC-induced epithelial barrier dysfunction was significantly worsened by intestinal HR (P < 0.05 vs. normoxia-EHEC-infected cells), but this was not protected by TGF-β1 pretreatment. Transforming growth factor-β1 preserves loss of epithelial barrier integrity caused by the stress of HR via a mechanism that may involve the upregulation of HO-1 transcription. Targeted treatment with TGF-β could lead to novel therapies in enteric diseases characterized by HR injury.