Modulatory effects of vasoactive intestinal peptide on intestinal mucosal immunity and microbial community of weaned piglets challenged by an enterotoxigenic Escherichia coli (K88)

Bacteriocin Microcin J25's antibacterial infection effects and novel non-microbial regulatory mechanisms: differential regulation of dopaminergic receptors

BACKGROUND

The antibacterial and immunomodulatory activities of bacteriocins make them attractive targets for development as anti-infective drugs. Although the importance of the enteric nervous system (ENS) in the struggle against infections of the intestine has been demonstrated, whether it is involved in bacteriocins anti-infective mechanisms is poorly defined.

RESULTS

Here, we demonstrated that the bacteriocin Microcin J25 (J25) significantly alleviated diarrhea and intestinal inflammation in piglets caused by enterotoxigenic Escherichia coli (ETEC) infection. Mechanistically, macrophage levels were significantly downregulated after J25 treatment, and this was replicated in a mouse model. Omics analysis and validation screening revealed that J25 treatment induced significant changes in the dopaminergic neuron pathway, but little change in microbial structure. The alleviation of inflammation may occur by down-regulating dopamine receptor (DR) D1 and the downstream DAG-PKC pathway, thus inhibiting arachidonic acid decomposition, and the inhibition of macrophages may occur through the up-regulation of DRD5 and the downstream cAMP-PKA pathway, thus inhibiting NF-κB.

CONCLUSIONS

Our studies' findings provide insight into the changes and possible roles of the ENS in J25 treatment of ETEC infection, providing a more sophisticated foundational understanding for developing the application potential of J25.

Ovomucin Hydrolysates Reduce Bacterial Adhesion and Inflammation in Enterotoxigenic Escherichia coli (ETEC) K88-Challenged Intestinal Epithelial Cells

Enterotoxigenic Escherichia coli (ETEC) K88 is the most common cause of diarrhea in neonatal and postweaning pigs. After adhering to small intestinal epithelial cells via glycoprotein receptor recognition, the pathogen can produce enterotoxins, impair intestinal integrity, trigger watery diarrhea, and induce inflammation via nuclear factor κB (NF-κB) and mitogen-activated protein kinase phosphatase (MAPK) pathways. Inhibiting ETEC K88 adhesion to cell surfaces by interfering with the receptor-fimbriae recognition provides a promising strategy to prevent the initiation and progression of infection. Ovomucin is a highly glycosylated protein in chicken egg white with diverse bioactivities. Ovomucin hydrolysates prepared by the enzymes Protex 26L (OP) and pepsin/pancreatin (OPP) were previously revealed to prevent adhesion of ETEC K88 to IPEC-J2 cells. Herein, we investigated the protective effects of ovomucin hydrolysates on ETEC K88-induced barrier integrity damage and inflammation in IPEC-J2 and Caco-2 cells. Both hydrolysates inhibited ETEC K88 adhesion to cells and protected epithelial cell integrity by restoring transepithelial electronic resistance (TEER) values. Removing sialic acids in the hydrolysates reduced their antiadhesive capacities. Ovomucin hydrolysates suppressed ETEC-induced activation of NF-κB and MAPK signaling pathways in both cell lines. The ability of ETEC K88 in activating calcium/calmodulin-dependent protein kinase 2 (CaMK II), elevating intracellular Ca2+ concentration, and inducing oxidative stress was attenuated by both hydrolysates. In conclusion, this study demonstrated the potential of ovomucin hydrolysates to prevent ETEC K88 adhesion and alleviate inflammation and oxidative stress in intestinal epithelial cells.

Influence of vasoactive intestinal polypeptide on growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity in lambs

This study evaluated if vasoactive intestinal polypeptide (VIP) influences growth performance, nutrient digestibility, nitrogen balance, and digestive enzyme activity. Sixteen wether lambs (69.6 ± 1.9 kg) were housed in individual pens, adapted to a corn grain-based diet, and randomly assigned to 2 treatment groups. Lambs were injected intraperitoneally every other day for 28 d with saline (0.9% NaCl) containing no VIP (n = 8; control) or containing VIP (n = 8; 1.3 nmol/kg body weight [BW]). All lambs were transferred to individual metabolic crates for the final 7 d of the experiment to measure nitrogen balance and nutrient digestibility. At the end of the treatment period, lambs were slaughtered, and pancreatic tissue, small intestinal tissue, and rumen fluid were collected for protein, digestive enzymes, ruminal pH, and volatile fatty acid (VFA) analyses. Lambs treated with VIP had greater final BW, average daily gain, and gain:feed (P = 0.01, 0.05, 0.03, respectively). No differences between treatment groups were observed (P ≥ 0.25) for nutrient intake, digestibility, nitrogen retention, ruminal pH, and VFA concentrations. Moreover, VIP treatment did not influence (P ≥ 0.19) plasma glucose, urea N, and insulin concentrations. Treatment with VIP increased (P = 0.03) relative cecum weight (g/kg BW) and decreased (P = 0.05) relative brain weight. Pancreatic and intestinal digestive enzyme activities, except for duodenal maltase (P = 0.02), were not influenced (P ≥ 0.09) by VIP treatment. These data suggest that the administration of VIP may have potential to improve average daily gain and gain:feed in lambs fed grain-based diets.

The impact of exogenous vasoactive intestinal polypeptide on inflammatory responses and mRNA expression of tight junction genes in lambs fed a high-grain diet

This study assessed the impact of administering vasoactive intestinal polypeptide (VIP) on inflammation and intestinal VIP and tight junction mRNA expression in lambs fed grain-based finishing diets. Sixteen wether lambs (69.6 ± 1.9 kg) were individually housed, adapted to a corn-based diet containing no forage, and randomly assigned to 2 treatment groups. Lambs were intraperitoneally injected every other day for 28 d with either saline (0.9% NaCl) with no VIP (n = 8; control) or saline with VIP (n = 8; 1.3 nmol/kg BW). Blood samples were collected weekly for analysis of cytokine concentrations, and on days 0 and 28 for lipopolysaccharide (LPS), and LPS-binding protein (LBP) concentrations. Upon completion of the treatment period, lambs were euthanized and gastrointestinal tissues, including rumen, jejunum, cecum, and colon samples, were collected for analysis of the expression of tight junction mRNA (claudin-1, claudin-4, occludin, and ZO-1), endogenous VIP, and VIP receptor (VPAC-1). No treatment effects (P ≥ 0.38) were observed for VIP and VPAC-1 mRNA expression in the colon. Supplementation with VIP did not influence (P ≥ 0.28) the expression of claudin-1, claudin-4, occludin, and ZO-1 tight junction mRNA in the rumen, jejunum, cecum, and colon. Lambs treated with VIP had greater (P ≤ 0.01) plasma concentrations of the anti-inflammatory cytokines, IL-10 and IL-36RA. There were treatment-by-day interactions observed (P ≤ 0.02) for concentrations of the pro-inflammatory cytokines, MIP-1α and MIP-1β. Lambs that did not receive VIP had greater serum concentrations of LPS (P = 0.05) than the lambs receiving VIP. These data suggest that VIP administration may not influence tight junction mRNA expression but may decrease LPS concentrations and thus inflammation in lambs fed a grain-based diet.

Effects of mixed fibres and essential oils blend on growth performance and intestinal barrier function of piglets challenged with enterotoxigenic Escherichia coli K88

This study was to evaluate the effects of supplementing mixed dietary fibres (MDF) and essential oils blend (EOB) either alone or in combination on growth performance and intestinal barrier function in weaned piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Forty-two piglets (28 days old) were randomly allocated into six treatments in a 25-day experiment, and fed the basal diet (CON or ETEC) either with antibiotics (AT), MDF, EOB or MDF + EOB. On Day 22 of the experiment, pigs in CON and challenged groups (ETEC, AT, MDF, EOB and MDF + EOB) were orally administered sterile saline and ETEC containing 6 × 1010  CFU/kg body weight respectively. On Day 26, all pigs were euthanized to collect samples. Before ETEC challenge, piglets in MDF and EOB had lower diarrhoea incidence (p < 0.01) than others. After ETEC challenge, piglets in ETEC had lower average daily gain and higher diarrhoea incidence (p < 0.05) than those of CON. Furthermore, compared to CON, ETEC group increased the serum lipopolysaccharide concentration and diamine oxidase activity, and decreased mRNA levels of genes relating to barrier function (aquaporin 3, AQP3; mucin1, MUC1; zonula occludens-1, ZO-1; Occludin), and increased the concentration of cytokines (interleukin-1β/4/6/10, IL-1β/4/6/10) and secretory immunoglobulin A (sIgA) in jejunal mucosa (p < 0.05). However, these deleterious effects induced by ETEC were partly alleviated by MDF, EOB, MDF + EOB and AT. Additionally, compared to ETEC group, MDF increased Bifidobacterium abundance in cecal digesta and butyrate concentration in colonic digesta (p < 0.05). Also, EOB improved propionate concentration in cecal digesta, and MDF + EOB decreased IL-10 concentration in jejunal mucosa (p < 0.05) compared with ETEC. Conclusively, MDF and EOB either alone or in combination can improve growth performance and alleviate diarrhoea via improving intestinal barrier function of piglets after ETEC challenge, and all may serve as potential alternatives to AT for piglets.

Dietary Supplementation with Puerarin Improves Intestinal Function in Piglets Challenged with Escherichia coli K88

The objective of this study was to investigate the effect of puerarin supplementation on the growth performance and intestinal function of piglets challenged with enterotoxigenic Escherichia coli (ETEC) K88. Twenty-four ternary crossbred piglets were randomly assigned to three treatment groups: control group, ETEC group (challenged with ETEC K88 on day 8), and ETEC + Puerarin group (supplemented with 5 mg/kg puerarin and challenged with ETEC K88 on day 8). All piglets were orally administered D-xylose (0.1 g/kg body weight) on day 10, and blood samples were collected after 1 h. Subsequently, piglets were killed and intestinal samples were collected for further analysis. The results showed that puerarin supplementation significantly decreased the adverse effects of ETEC K88-challenged piglets; significantly improved growth performance; increased the number of Bifidobacterium in the colon and Lactobacillus in the jejunum, cecum and colon; decreased the number of Escherichia coli in the jejunum and cecum; reduced the hydrogen peroxide content in the jejunum and myeloperoxidase activity in the jejunum and ileum; and increased the activities of catalase and superoxide dismutase in the jejunum and ileum. In addition, puerarin supplementation alleviated ETEC K88-induced intestinal injury in piglets, significantly downregulated the mRNA level of Interleukin-1β and upregulated the mRNA levels of intercellular cell adhesion molecule-1, myxovirus resistance protein 1, myxovirus resistance protein 2, and guanylate-binding protein-1 in the small intestine of piglets. In conclusion, dietary supplementation with puerarin could attenuate ETEC K88-induced intestinal injury by increasing the antioxidant and anti-inflammatory capacity and the number of beneficial intestinal bacteria in piglets.

Gegen Qinlian decoction restores the intestinal barrier in bacterial diarrhea piglets by promoting Lactobacillus growth and inhibiting the TLR2/MyD88/NF-κB pathway

Acute bacterial diarrhea is a severe global problem with a particularly high incidence rate in children. The microecology inhabiting the intestinal mucosa is the key factor leading to diarrhea. Gegen Qinlian decoction (GQD) is used to treat bacterial diarrhea, however, its underlying mechanism remains unclear. Thus, this study aimed to clarify the restorative effect of GQD on the intestinal barrier from the perspective of gut microbiota. A Tibetan piglet model with bacterial diarrhea was established through orally administered Escherichia coli, and diarrheal piglets were treated with GQD for three days. After treatment, GQD significantly ameliorated the diarrheal symptoms. GQD decreased the levels of IL-6, LPS, and DAO, and increased SIgA, ZO-1, and occludin levels in intestinal mucosa, indicating the restoration of intestinal barrier. GQD modulated the microbial compositions inhabited on the intestinal mucosa, especially an increase of the Lactobacillus. Spearman analysis showed that Lactobacillus was the key genus of intestinal barrier-related bacteria. Bacterial culture in vitro validated that GQD directly promoted Lactobacillus growth and inhibited E. coli proliferation. Moreover, the expressions of TLR2, MyD88, and NF-κB in the colon decreased after GQD treatment. In conclusion, GQD may treat diarrhea and restore the intestinal mucosal barrier by facilitating Lactobacillus growth and inhibiting the TLR2/MyD88/NF-κB signaling pathway.

Purification, structural characterization and immunological activity of Sibiraea laexigata (L.) Maxim polysaccharide

Sibiraea laexigata (L.) Maxim (SLM) has been used as an herbal tea for treating stomach discomfort and indigestion for a long time in china. Polysaccharides have been identified as one of the major bioactive compounds in the SLM. In the present paper, ultrasonic-assisted enzymatic extraction (UAEE) method was employed in polysaccharides extraction derived from SLM using polyethylene glycol (PEG) as extraction solvent, two SLM polysaccharides (SLMPs) fractions (SLMPs-1-1 and SLMPs-2-1) were purified by DEAE Cellulose-52 and Sephadex G-100 chromatography in sequence. Then, the preliminarily structure of the two factions were characterized by chemical composition analysis, molecular weight measurement, UVS, HPLC-PMP, FT-IR, nuclear magnetic resonance (NMR) spectra analysis and SEM. The results showed that SLMPs-1-1 and SLMPs-2-1 with different molecular weights of 1.03 and 1.02 kDa, mainly composed of glucose (46.76 and 46.79%), respectively. The results of structural characterization from FT-IR, 1H NMR, and SEM revealed that SLMPs-1-1 and SLMPs-2-1 contained the typical pyranoid polysaccharide with α-glycosidic bond and β-glycosidic bond. Furthermore, it was found that SLMPs-1-1 could increase the levels of tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2), and alleviated the immune organs tissue damage of cyclophosphamide (Cy)-treated mice. RT-qPCR and Western-Blot analysis showed that SLMPs-1-1 could significantly up-regulated the levels of NF-κB, TLR4, which revealed that SLMPs-1-1 could participate in immunosuppressive protection of Cy-treated mice. These findings suggested that the potential of SLMPs-1-1 as an alternative immunostimulator could be used in food and pharmaceutical industries.

Enterotoxigenic Escherichia coli infection of weaned pigs: Intestinal challenges and nutritional intervention to enhance disease resistance

Enterotoxigenic Escherichia coli (ETEC) infection induced post-weaning diarrhea is one of the leading causes of morbidity and mortality in newly weaned pigs and one of the significant drivers for antimicrobial use in swine production. ETEC attachment to the small intestine initiates ETEC colonization and infection. The secretion of enterotoxins further disrupts intestinal barrier function and induces intestinal inflammation in weaned pigs. ETEC infection can also aggravate the intestinal microbiota dysbiosis due to weaning stress and increase the susceptibility of weaned pigs to other enteric infectious diseases, which may result in diarrhea or sudden death. Therefore, the amount of antimicrobial drugs for medical treatment purposes in major food-producing animal species is still significant. The alternative practices that may help reduce the reliance on such antimicrobial drugs and address animal health requirements are needed. Nutritional intervention in order to enhance intestinal health and the overall performance of weaned pigs is one of the most powerful practices in the antibiotic-free production system. This review summarizes the utilization of several categories of feed additives or supplements, such as direct-fed microbials, prebiotics, phytochemicals, lysozyme, and micro minerals in newly weaned pigs. The current understanding of these candidates on intestinal health and disease resistance of pigs under ETEC infection are particularly discussed, which may inspire more research on the development of alternative practices to support food-producing animals.

Combination of pseudoephedrine and emodin ameliorates LPS-induced acute lung injury by regulating macrophage M1/M2 polarization through the VIP/cAMP/PKA pathway

Background

Acute lung injury (ALI) is an acute multifactorial infectious disease induced by trauma, pneumonia, shock, and sepsis. This study aimed to investigate the protective effects of pseudoephedrine and emodin combined treatment in experimental ALI, as well as the mechanisms underlying the regulation of inflammation and pulmonary edema via the VIP/cAMP/PKA pathway.

Methods

The wistar rats were randomly divided into fifteen groups (n = 5). Rats in each group were given intragastric administration 1 h before LPS injection. Those in the control and LPS groups were given intragastric administrations of physiological saline, rats in other groups were given intragastrically administered of differential dose therapeutic agents. The rats in the LPS and treatment groups were then injected intraperitoneally with LPS (7.5 mg/kg) to induce ALI. After being treated with pseudoephedrine and emodin for 12 h, all animals were sacrifice. Anal temperatures were taken on an hourly basis for 8 h after LPS injection. Pathological examination of lung specimen was performed by H&E staining. Cytokines (IL-1β, TNF-α, IL-6, iNOS, IL-10, Arg-1, CD86, CD206, F4/80, VIP) in lung tissue were assayed by ELISA and immunofluorescence. The expression of VIP, CAMP, AQP-1, AQP-5, p-PKA, PKA, p-IκBα, IκBα, p-p65, p65, p-P38, P38, p-ERK1/2, ERK1/2, p-JNK1/2, JNK1/2 protein in lung was determined by western blotting.

Results

After rats being treated with pseudoephedrine + emodin, reduced of fever symptoms. The contents of inflammatory cytokines (IL-1β, TNF-α, IL-6, iNOS) were decreased and anti-inflammatory cytokines (IL-10, Arg-1) were significantly increased in serum. Pseudoephedrine + emodin treatment effectively promoted VIP cAMP and p-PKA protein expression in lung tissues, and significantly inhibited NF-κB, MAPK phosphorylation, Pseudoephedrine + emodin treatment can inhibit M1 polarization and promoted M2 polarization via the VIP/cAMP/PKA signaling pathway.

Conclusions

The combination of Pseudoephedrine and emodin was effective in ameliorating LPS-induced ALI in rats by inducing VIP/cAMP/PKA signaling. Inhibiting the NF-κB, MAPK inflammatory pathway, relief of pulmonary edema suppressing macrophage M1 polarization, and promoting macrophage M2 polarization.

Protective efficacy of a novel multivalent vaccine in the prevention of diarrhea induced by enterotoxigenic Escherichia coli in a murine model

Background

Enterotoxigenic Escherichia coli (ETEC) infection is a primary cause of livestock diarrhea. Therefore, effective vaccines are needed to reduce the incidence of ETEC infection.

Objectives

Our study aimed to develop a multivalent ETEC vaccine targeting major virulence factors of ETEC, including enterotoxins and fimbriae.

Methods

SLS (STa-LTB-STb) recombinant enterotoxin and fimbriae proteins (F4, F5, F6, F18, and F41) were prepared to develop a multivalent vaccine. A total of 65 mice were immunized subcutaneously by vaccines and phosphate-buffered saline (PBS). The levels of specific immunoglobulin G (IgG) and pro-inflammatory cytokines were determined at 0, 7, 14 and 21 days post-vaccination (dpv). A challenge test with a lethal dose of ETEC was performed, and the survival rate of the mice in each group was recorded. Feces and intestine washes were collected to measure the concentrations of secretory immunoglobulin A (sIgA).

Results

Anti-SLS and anti-fimbriae-specific IgG in serums of antigen-vaccinated mice were significantly higher than those of the control group. Immunization with the SLS enterotoxin and multivalent vaccine increased interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations. Compared to diarrheal symptoms and 100% death of mice in the control group, mice inoculated with the multivalent vaccine showed an 80% survival rate without any symptom of diarrhea, while SLS and fimbriae vaccinated groups showed 60 and 70% survival rates, respectively.

Conclusions

Both SLS and fimbriae proteins can serve as vaccine antigens, and the combination of these two antigens can elicit stronger immune responses. The results suggest that the multivalent vaccine can be successfully used for preventing ETEC in important livestock.

Pathogen Challenge and Dietary Shift Alter Microbiota Composition and Activity in a Mucin-Associated in vitro Model of the Piglet Colon (MPigut-IVM) Simulating Weaning Transition

Enterotoxigenic Escherichia coli (ETEC) is the principal pathogen responsible for post-weaning diarrhea in newly weaned piglets. Expansion of ETEC at weaning is thought to be the consequence of various stress factors such as transient anorexia, dietary change or increase in intestinal inflammation and permeability, but the exact mechanisms remain to be elucidated. As the use of animal experiments raise more and more ethical concerns, we used a recently developed in vitro model of piglet colonic microbiome and mucobiome, the MPigut-IVM, to evaluate the effects of a simulated weaning transition and pathogen challenge at weaning. Our data suggested that the tested factors impacted the composition and functionality of the MPigut-IVM microbiota. The simulation of weaning transition led to an increase in relative abundance of the Prevotellaceae family which was further promoted by the presence of the ETEC strain. In contrast, several beneficial families such as Bacteroidiaceae or Ruminococcaceae and gut health related short chain fatty acids like butyrate or acetate were reduced upon simulated weaning. Moreover, the incubation of MPigut-IVM filtrated effluents with porcine intestinal cell cultures showed that ETEC challenge in the in vitro model led to an increased expression of pro-inflammatory genes by the porcine cells. This study provides insights about the etiology of a dysbiotic microbiota in post-weaning piglets.

Alginate oligosaccharide protects against enterotoxigenic Escherichia coli-induced porcine intestinal barrier injury

Alginate oligosaccharide (AOS) possesses various pharmaceutical benefits, making it an attractive candidate for biomedical applications. In the present study, we prepared AOS by depolymerising alginate; its degree of polymerisation mainly ranged from 2 to 8. We confirmed the enteroprotective potential of AOS against enterotoxigenic Escherichia coli (ETEC)-induced intestinal barrier injury in weaned pigs. Next, we illustrated the mechanisms underlying this effect of AOS using the porcine small intestinal epithelial cell line IPEC-J2. AOS potently reduced the binding of the bacteria-deprived endotoxin lipopolysaccharide (LPS) to the IPEC-J2 cell surface. Moreover, it suppressed the LPS-induced production of pro-inflammatory cytokines and the nuclear translocation of nuclear factor-κB (NF-κB) p65 in IPEC-J2 cells. These results indicate that AOS protects the intestinal epithelium from ETEC-induced inflammatory injury by preventing the activation of NF-κB, implying that AOS could be used as an anti-inflammatory agent for treating inflammation-related intestinal diseases in mammals.

Swine as biomedical animal model for T-cell research-Success and potential for transmittable and non-transmittable human diseases

Swine is biologically one of the most relevant large animal models for biomedical research. With its use as food animal that can be exploited as a free cell and tissue source for research and its high susceptibility to human diseases, swine additionally represent an excellent option for both the 3R principle and One Health research. One of the previously most limiting factors of the pig model was its arguably limited immunological toolbox. Yet, in the last decade, this toolbox has vastly improved including the ability to study porcine T-cells. This review summarizes the swine model for biomedical research with focus on T cells. It first contrasts the swine model to the more commonly used mouse and non-human primate model before describing the current capabilities to characterize and extend our knowledge on porcine T cells. Thereafter, it not only reflects on previous biomedical T-cell research but also extends into areas in which more in-depth T-cell analyses could strongly benefit biomedical research. While the former should inform on the successes of biomedical T-cell research in swine, the latter shall inspire swine T-cell researchers to find collaborations with researchers working in other areas - such as nutrition, allergy, cancer, transplantation, infectious diseases, or vaccine development.

Mammalian Neuropeptides as Modulators of Microbial Infections: Their Dual Role in Defense versus Virulence and Pathogenesis

The regulation of infection and inflammation by a variety of host peptides may represent an evolutionary failsafe in terms of functional degeneracy and it emphasizes the significance of host defense in survival. Neuropeptides have been demonstrated to have similar antimicrobial activities to conventional antimicrobial peptides with broad-spectrum action against a variety of microorganisms. Neuropeptides display indirect anti-infective capacity via enhancement of the host’s innate and adaptive immune defense mechanisms. However, more recently concerns have been raised that some neuropeptides may have the potential to augment microbial virulence. In this review we discuss the dual role of neuropeptides, perceived as a double-edged sword, with antimicrobial activity against bacteria, fungi, and protozoa but also capable of enhancing virulence and pathogenicity. We review the different ways by which neuropeptides modulate crucial stages of microbial pathogenesis such as adhesion, biofilm formation, invasion, intracellular lifestyle, dissemination, etc., including their anti-infective properties but also detrimental effects. Finally, we provide an overview of the efficacy and therapeutic potential of neuropeptides in murine models of infectious diseases and outline the intrinsic host factors as well as factors related to pathogen adaptation that may influence efficacy.

Tannins extract from Galla Chinensis can protect mice from infection by Enterotoxigenic Escherichia coli O101

Background

Enterotoxigenic Escherichia coli (ETEC) is classically associated with acute secretory diarrhea, which induces 2 million people death in developing countries over a year, predominantly children in the first years of life. Previously, tannins (47.75%) were extracted from Galla Chinensis and prepared as Galla Chinensis oral solution (GOS) which showed significant antidiarrheal activity in a castor oil-induced diarrhea in mice. Whether the tannins extract were also effective in treatment of ETEC-induced diarrhea was determined in this study.

Methods

Mice were randomly divided into 6 groups (n = 22). The mice in the normal and untreated groups were given normal saline. Three GOS-treated groups were received different concentrations of GOS (5, 10 and 15%, respectively) at a dose of 10 mL/kg. Mice in the positive control group were fed with loperamide (10 mg/kg). The treatment with GOS started 3 days before infection with ETEC and continued for 4 consecutive days after infection. On day 3, mice were all infected with one dose of LD₅₀ of ETEC, except those in the normal group. Survival of mice was observed daily and recorded throughout the study. On days 4 and 7, samples were collected from 6 mice in each group.

Results

GOS could increase the survival rate up to 75%, while in the untreated group it is 43.75%. The body weights of mice treated with 15% GOS were significantly increased on day 7 in comparison with the untreated group and the normal group. GOS-treatment recovered the small intestine coefficient enhanced by ETEC-infection. The diarrhea index of mice treated with GOS was significantly decreased. GOS increased the levels of IgG and sIgA in the terminal ileum and decreased the levels of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1β, IL-6 and IL-8) in serum. GOS could increase the amount of intestinal probiotics, Lactobacilli and Bifidobacteria. GOS could alleviate colon lesions induced by ETEC-infection. GOS showed higher potency than loperamide.

Conclusions

GOS could be a promising drug candidate for treating ETEC infections.

Zinc is an important inter-kingdom signal between the host and microbe

Zinc (Zn) is an essential trace element in living organisms and plays a vital role in the regulation of both microbial virulence and host immune responses. A growing number of studies have shown that zinc deficiency or the internal Zn concentration does not meet the needs of animals and microbes, leading to an imbalance in zinc homeostasis and intracellular signalling pathway dysregulation. Competition for zinc ions (Zn²⁺) between microbes and the host exists in the use of Zn²⁺ to maintain cell structure and physiological functions. It also affects the interplay between microbial virulence factors and their specific receptors in the host. This review will focus on the role of Zn in the crosstalk between the host and microbe, especially for changes in microbial pathogenesis and nociceptive neuron-immune interactions, as it may lead to new ways to prevent or treat microbial infections.

Vasoactive Intestinal Peptide Deficiency Is Associated With Altered Gut Microbiota Communities in Male and Female C57BL/6 Mice

Vasoactive intestinal peptide (VIP) is crucial for gastrointestinal tract (GIT) health. VIP sustains GIT homeostasis through maintenance of the intestinal epithelial barrier and acts as a potent anti-inflammatory mediator that contributes to gut bacterial tolerance. Based on these biological functions by VIP, we hypothesized that its deficiency would alter gut microbial ecology. To this end, fecal samples from male and female VIP+/+, VIP+/-, and VIP-/- littermates (n = 47) were collected and 16S rRNA sequencing was conducted. Our data revealed significant changes in bacterial composition, biodiversity, and weight loss from VIP-/- mice compared to VIP+/+ and VIP+/- littermates, irrespective of sex. The gut bacteria compositional changes observed in VIP-/- mice was consistent with gut microbial structure changes reported for certain inflammatory and autoimmune disorders. Moreover, predicted functional changes by PICRUSt software suggested an energy surplus within the altered microbiota from VIP-/- mice. These data support that VIP plays an important role in maintaining microbiota balance, biodiversity, and GIT function, and its genetic removal results in significant gut microbiota restructuring and weight loss.

A Synthetic Agonist to Vasoactive Intestinal Peptide Receptor-2 Induces Regulatory T Cell Neuroprotective Activities in Models of Parkinson's Disease

A paradigm shift has emerged in Parkinson’s disease (PD) highlighting the prominent role of CD4⁺ Tregs in pathogenesis and treatment. Bench to bedside research, conducted by others and our own laboratories, advanced a neuroprotective role for Tregs making pharmacologic transformation of immediate need. Herein, a vasoactive intestinal peptide receptor-2 (VIPR2) peptide agonist, LBT-3627, was developed as a neuroprotectant for PD-associated dopaminergic neurodegeneration. Employing both 6-hydroxydopamine (6-OHDA) and α-synuclein (α-Syn) overexpression models in rats, the sequential administration of LBT-3627 increased Treg activity without altering cell numbers both in naïve animals and during progressive nigrostriatal degeneration. LBT-3627 administration was linked to reductions of inflammatory microglia, increased survival of dopaminergic neurons, and improved striatal densities. While α-Syn overexpression resulted in reduced Treg activity, LBT-3627 rescued these functional deficits. This occurred in a dose-dependent manner closely mimicking neuroprotection. Taken together, these data provide the basis for the use of VIPR2 agonists as potent therapeutic immune modulating agents to restore Treg activity, attenuate neuroinflammation, and interdict dopaminergic neurodegeneration in PD. The data underscore an important role of immunity in PD pathogenesis.

The involvement of NF-κB/P38 pathways in Scutellaria baicalensis extracts attenuating of Escherichia coli K88-induced acute intestinal injury in weaned piglets

The present study was carried out to evaluate the effect of dietary supplementation of Scutellaria baicalensis extracts (SBE) on intestinal health in terms of morphology, barrier integrity and immune responses in weaned piglets challenged with Escherichia coli K88. A total of seventy-two weaned piglets were assigned into two groups to receive a basal diet without including antibiotic additives or the basal diet supplemented 1000 mg SBE/kg diet for 14 d. On day 15, twelve healthy piglets from each group were selected to expose to oral administration of either 10 ml 1 × 109 colony-forming units of E. coli K88 or the vehicle control. After 48 h of E.coli K88 challenge, blood was sampled, and then all piglets were killed humanely for harvesting jejunal and ileal samples. Dietary supplementation of SBE significantly decreased diarrhoea frequency and improved feed conversion ratio (P < 0·05). SBE supplementation to E.coli K88-challenged piglets improved villous height and villous height/crypt depth (P < 0·05), recovered the protein expression of occludin and zonula occludens-2 in both the jejunum and ileum (P < 0·05), and mitigated the increases in plasma IL-1β, TNF-α, IL-6, IgA and IgG (P < 0·05). Meanwhile, dietary SBE effectively inhibited the stimulation of NF-κB, P38 and TNF-α as well as IL-1β in the small intestine of piglets challenged by E. coli K88 and prevented the activation of NF-κB/P38 signalling pathways (P < 0·05). Collectively, SBE supplementation can potently attenuate diarrhoea in weaning piglets and decrease inflammatory cytokine expressions through inhibiting the NF-κB and P38 signalling pathways.

Amelioration of Enterotoxigenic Escherichia coli-Induced Intestinal Barrier Disruption by Low-Molecular-Weight Chitosan in Weaned Pigs is Related to Suppressed Intestinal Inflammation and Apoptosis

Enterotoxigenic Escherichia coli (ETEC) infection destroys the intestinal barrier integrity, in turn, disrupting intestinal homoeostasis. Low-molecular-weight chitosan (LMWC) is a water-soluble chitosan derivative with versatile biological properties. Herein, we examined whether LMWC could relieve ETEC-induced intestinal barrier damage in weaned pigs. Twenty-four weaned pigs were allotted to three treatments: (1) non-infected control; (2) ETEC-infected control; and (3) ETEC infection + LMWC supplementation (100 mg/kg). On day 12, pigs in the infected groups were administered 100 mL of ETEC at 2.6 × 10⁹ colony-forming units/mL to induce intestinal barrier injury. Three days later, serum samples were obtained from all pigs, which were then slaughtered to collect intestinal samples. We evidenced that LMWC not only increased (P < 0.05) the occludin protein abundance but also decreased (P < 0.05) the interleukin-6, tumour necrosis factor-α and mast cell tryptase contents, and the apoptotic epithelial cell percentages, in the small intestine of ETEC-infected pigs. Furthermore, LMWC down-regulated (P < 0.05) the small intestinal expression levels of critical inflammatory- and apoptotic-related genes, such as Toll-like receptor 4 (TLR4) and tumour necrosis factor receptor 1 (TNFR1), as well as the intra-nuclear nuclear factor-κB (NF-κB) p65 protein abundance, in the ETEC-infected pigs. Our study indicated a protective effect of LMWC on ETEC-triggered intestinal barrier disruption in weaned pigs, which involves the repression of intestinal inflammatory responses via blocking the TLR4/NF-κB signalling pathway and the depression of epithelial cell death via TNFR1-dependent apoptosis.

Vasoactive intestinal peptide overexpression mediated by lentivirus attenuates lipopolysaccharide-induced acute lung injury in mice by inhibiting inflammation

Vasoactive intestinal peptide (VIP) is one of the most abundant neuropeptides in the lungs with various biological characters. We have reported that VIP inhibited the expressions of TREM-1 and IL-17A, which are involved in the initiation and amplification of inflammation in acute lung injury (ALI). However, the overall effect of VIP on ALI remains unknown. The aim of this study is to investigate the therapeutic effect of VIP mediated by lentivirus (Lenti-VIP) on lipopolysaccharide (LPS)-induced murine ALI. We found that the expression of intrapulmonary VIP peaked at day7 after the intratracheal injection of Lenti-VIP. Lenti-VIP increased the respiratory rate, lung compliance, and tidal volume, while decreased airway resistance in ALI mice, detected by Buxco system. Lenti-VIP significantly reduced inflammatory cell infiltration and maintained the integrity of the alveolar septa. Lenti-VIP also remarkably decreased the total protein level, the number of neutrophil and lactate dehydrogenase activity in the bronchoalveolar lavage fluid of LPS-induced ALI mice. In addition, Lenti-VIP down-regulated pro-inflammatory tumor necrosis factor (TNF)-α mRNA and protein expression, while up-regulated anti-inflammatory interleukin-10 mRNA and protein expression in lungs of ALI mice. Furthermore, we observed that VIP reduced the TNF-α expression in murine macrophages under LPS stimulation through protein kinase C and protein kinase A pathways. Together, our findings show that in vivo administration of lentivirus expressing VIP exerts a potent therapeutic effect on LPS-induced ALI in mice via inhibiting inflammation.

Role of vasoactive intestinal peptide in Aspergillus fumigatus-infected cornea

AIM

To investigate the anti-inflammatory role of vasoactive intestinal peptide (VIP) in Aspergillus fumigatus (A. fumigatus) ketatitis.

METHODS

Expression of VIP was tested by polymerase chain reaction (PCR) in C57BL/6 and BALB/c normal and A. fumigatus infected corneas. C57BL/6 mice were pretreated with recombinant (r) VIP, while BALB/c mice were pretreated with VIP antagonist, and then infected with A. fumigatus. Clinical score was recorded. Expression of pro- and anti-inflammatory cytokines, toll-like receptor 4 (TLR4), lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1), and neutrophil infiltration were tested by PCR, enzyme-linked immunosorbent assay (ELISA), and myeloperoxidase (MPO) assay.

RESULTS

VIP mRNA expression in BALB/c cornea was higher than C57BL/6 cornea at 1 and 3d post infection (p.i.). rVIP treatment of C57BL/6 mice showed alleviated disease and down-regulated expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), while IL-10 expression was up-regulated. Neutrophil infiltration and TLR4, IL-17 expression were decreased after rVIP treatment, while LOX-1 expression was up-regulated in C57BL/6. VIP antagonist pretreatment showed increased disease and higher IL-1β, TNF-α, TLR4, IL-17 and MPO levels, while IL-10 and LOX-1 levels were down-regulated in BALB/c mice.

CONCLUSION

rVIP alleviate disease response of C57BL/6 mice. VIP antagonist resulted in worsened disease of BALB/c mice. VIP proposed anti-inflammatory role in A. fumigatus keratitis.

Dietary grape seed proanthocyanidins (GSPs) improve weaned intestinal microbiota and mucosal barrier using a piglet model

Proanthocyanidins have been suggested as an effective antibiotic alternative, however their mechanisms are still unknown. The present study investigated the effects of grape seed proanthocyanidins on gut microbiota and mucosal barrier using a weaned piglet model in comparison with colistin. Piglets weaned at 28 day were randomly assigned to four groups treated with a control ration, or supplemented with 250 mg/kg proanthocyanidins, kitasamycin/colistin, or 250 mg/kg proanthocyanidins and half-dose antibiotics, respectively. On day 28, the gut chyme and tissue samples were collected to test intestinal microbiota and barrier function, respectively. Proanthocyanidins treated piglets had better growth performance and reduced diarrhea incidence (P < 0.05), accompanied with decreased intestinal permeability and improved mucosal morphology. Gene sequencing analysis of 16S rRNA revealed that dietary proanthocyanidins improved the microbial diversity in ileal and colonic digesta, and the most abundant OTUs belong to Firmicutes and Bacteroidetes spp.. Proanthocyanidins treatment decreased the abundance of Lactobacillaceae, and increased the abundance of Clostridiaceae in both ileal and colonic lumen, which suggests that proanthocyanidins treatment changed the bacterial composition and distribution. Administration of proanthocyanidins increased the concentration of propionic acid and butyric acid in the ileum and colon, which may activate the expression of GPR41. In addition, dietary proanthocyanidins improved the antioxidant indices in serum and intestinal mucosa, accompanied with increasing expression of barrier occludin. Our findings indicated that proanthocyanidins with half-dose colistin was equivalent to the antibiotic treatment and assisted weaned animals in resisting intestinal oxidative stress by increasing diversity and improving balance of gut microbes.

Alginate oligosaccharide alleviates enterotoxigenicEscherichia coli-induced intestinal mucosal disruption in weaned pigs

Alginate oligosaccharide (AOS) is a non-toxic, non-immunogenic, non-carcinogenic and biodegradable product generated by depolymerisation of alginate, and exhibits various salutary properties.

Enterotoxigenic Escherichia coli is phagocytosed by macrophages underlying villus-like intestinal epithelial cells: modeling ex vivo innate immune defenses of the human gut

There is a paucity of information on diarrheagenic enterotoxigenic Escherichia coli (ETEC)'s interaction with innate immune cells, in part due to the lack of reliable models that recapitulate infection in human gut. In a recent publication, we described the development of an ex vivo enteroid-macrophage co-culture model using human primary cells. We reported that macrophages residing underneath the epithelial monolayer acquired "resident macrophage" phenotype characterized by lower production of inflammatory cytokines and strong phagocytic activity. These macrophages extended projections across the epithelium, which captured ETEC applied to the apical side of the epithelium and reduced luminal bacterial load. Additional evidence presented in this addendum confirms these findings and further demonstrates that macrophage adaptation occurs regardless of the stage of differentiation of epithelial cells, and that ETEC uptake arises rapidly after infection. The enteroid-macrophage co-culture represents a novel and relevant tool to study host-cell interactions and pathogenesis of enteric infections in humans.

Sensory neuron regulation of gastrointestinal inflammation and bacterial host defence

Sensory neurons in the gastrointestinal tract have multifaceted roles in maintaining homeostasis, detecting danger and initiating protective responses. The gastrointestinal tract is innervated by three types of sensory neurons: dorsal root ganglia, nodose/jugular ganglia and intrinsic primary afferent neurons. Here, we examine how these distinct sensory neurons and their signal transducers participate in regulating gastrointestinal inflammation and host defence. Sensory neurons are equipped with molecular sensors that enable neuronal detection of diverse environmental signals including thermal and mechanical stimuli, inflammatory mediators and tissue damage. Emerging evidence shows that sensory neurons participate in host-microbe interactions. Sensory neurons are able to detect pathogenic and commensal bacteria through specific metabolites, cell-wall components, and toxins. Here, we review recent work on the mechanisms of bacterial detection by distinct subtypes of gut-innervating sensory neurons. Upon activation, sensory neurons communicate to the immune system to modulate tissue inflammation through antidromic signalling and efferent neural circuits. We discuss how this neuro-immune regulation is orchestrated through transient receptor potential ion channels and sensory neuropeptides including substance P, calcitonin gene-related peptide, vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide. Recent studies also highlight a role for sensory neurons in regulating host defence against enteric bacterial pathogens including Salmonella typhimurium, Citrobacter rodentium and enterotoxigenic Escherichia coli. Understanding how sensory neurons respond to gastrointestinal flora and communicate with immune cells to regulate host defence enhances our knowledge of host physiology and may form the basis for new approaches to treat gastrointestinal diseases.

Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance, immune status and anti-oxidative capacity in early weaned piglets

The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses.

Stress, Nutrition, and Intestinal Immune Responses in Pigs - A Review

Modern livestock production became highly intensive and large scaled to increase production efficiency. This production environment could add stressors affecting the health and growth of animals. Major stressors can include environment (air quality and temperature), nutrition, and infection. These stressors can reduce growth performance and alter immune systems at systemic and local levels including the gastrointestinal tract. Heat stress increases the permeability, oxidative stress, and inflammatory responses in the gut. Nutritional stress from fasting, antinutritional compounds, and toxins induces the leakage and destruction of the tight junction proteins in the gut. Fasting is shown to suppress pro-inflammatory cytokines, whereas deoxynivalenol increases the recruitment of intestinal pro-inflammatory cytokines and the level of lymphocytes in the gut. Pathogenic and viral infections such as Enterotoxigenic E. coli (ETEC) and porcine epidemic diarrhea virus can lead to loosening the intestinal epithelial barrier. On the other hand, supplementation of Lactobacillus or Saccharaomyces reduced infectious stress by ETEC. It was noted that major stressors altered the permeability of intestinal barriers and profiles of genes and proteins of pro-inflammatory cytokines and chemokines in mucosal system in pigs. However, it is not sufficient to fully explain the mechanism of the gut immune system in pigs under stress conditions. Correlation and interaction of gut and systemic immune system under major stressors should be better defined to overcome aforementioned obstacles.

Dietary Sodium Butyrate Decreases Postweaning Diarrhea by Modulating Intestinal Permeability and Changing the Bacterial Communities in Weaned Piglets

BACKGROUND

The vast majority of substances used as alternatives to antibiotics produce inconsistent results and rarely equal the effectiveness of in-feed antibiotics.

OBJECTIVE

This study evaluated the effects of the combined use of sodium butyrate (SB) and reduced antibiotics in a piglet diet in promoting performance and to control weaning diarrhea.

METHODS

Piglets weaned at 28 d were randomly assigned to a corn-soybean meal control ration [negative control (NC)]; a similar ration with 50 mg kitasamycin/kg, 20 mg colistin sulfate/kg, and 1000 mg encapsulated SB/kg [reduced antibiotics + SB (ASB)]; or to a ration with 100 mg kitasamycin/kg and 40 mg colistin sulfate/kg [positive control (PC)] for 28 d. Performance, diarrhea incidence, intestinal permeability, and changes in the bacterial communities in the ileum and colon were determined.

RESULTS

Weight gain and the ratio of weight gain to feed intake were significantly greater in the ASB and PC piglets than in the NC piglets (P < 0.05). Diarrhea incidence was lower in the ASB and PC piglets than in the NC piglets (P < 0.05). Urinary lactulose to mannitol ratios were 25% and 30% lower, respectively, whereas jejunal and colonic occludin protein expressions were significantly greater in the ASB and PC piglets compared with the NC piglets (P < 0.05). In the intestinal mucosa, malondialdehyde was lower in the ASB and PC piglets (by 42% and 43%, respectively), whereas tumor necrosis factor α (TNF-α) was 63% lower in the ASB piglets and 59% lower in the PC piglets compared with the NC piglets (P < 0.05). 16S ribosomal RNA gene sequence analysis revealed a higher colonic Shannon index and a lower colonic Simpson index in the ASB and PC piglets than in the NC piglets. In addition, the ASB and PC treatments caused a striking decrease in Lactobacillaceae and a noticeable increase in Clostridiaceae in the ileal and colonic lumen, as well as increases in Ruminococcaceae, Lachnospiraceae, and Bacteroidetes in the colonic lumen.

CONCLUSION

Collectively, our results support an important role for SB in improving performance and decreasing diarrhea incidence in weaned piglets by modulation of intestinal permeability and the bacterial communities in the ileum and colon.