GABA attenuates ETEC-induced intestinal epithelial cell apoptosis involving GABAAR signaling and the AMPK-autophagy pathway

Activation of GABABR Attenuates Intestinal Inflammation by Reducing Oxidative Stress through Modulating the TLR4/MyD88/NLRP3 Pathway and Gut Microbiota Abundance

Oxidative stress emerges as a prominent factor in the onset and progression of intestinal inflammation, primarily due to its critical role in damaging cells and tissues. GABAergic signaling is important in the occurrence and development of various intestinal disorders, yet its effect on oxidative stress remains unclear. We attempted to assess whether GABAergic signaling participated in the regulation of oxidative stress during enteritis. The results showed that lipopolysaccharide (LPS) significantly decreased γ-aminobutyric acid (GABA) levels in the ileal tissues of mice. Interestingly, the application of GABA significantly repressed the shedding of intestinal mucosal epithelial cells and inflammatory cell infiltration, inhibited the expressions of proinflammatory factors, including granulocyte colony-stimulating factor and granulocyte-macrophage colony stimulating factor, and enhanced the levels of anti-inflammatory cytokines interleukin (IL)-4 and IL-10, indicating that GABA could alleviate enteritis in mice. This observation was further supported by transcriptome sequencing, revealing a total of 271 differentially expressed genes, which exhibited a marked enrichment of inflammatory and immune-related pathways, alongside a prominent enhancement of GABA B receptor (GABABR) signaling following GABA administration. Effectively, Baclofen pretreatment alleviated intestinal mucosal damage in LPS-induced mice, suppressed proinflammatory cytokines IL-1β, IL-6, and tumor necrosis factor alpha expressions, and boosted total antioxidant capacity, superoxide dismutase (SOD), and glutathione (GSH) levels. Moreover, Baclofen notably enhanced the viability of LPS-stimulated IPEC-J2 cells, contracted the proinflammatory secretion factors, and reinforced SOD, GSH, and catalase levels, emphasizing the anti-inflammatory and antioxidant effects associated with GABABR activation. Mechanistically, Baclofen restrained the mRNA and protein levels of toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3), and inducible nitric oxide synthase, while elevating nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 in both mice and IPEC-J2 cells, indicating that activating GABABR strengthened antioxidant abilities by interrupting the TLR4/MyD88/NLRP3 pathway. Furthermore, 16S rDNA analysis demonstrated that Baclofen increased the relative abundance of probiotic, particularly Lactobacillus, renowned for its antioxidant properties, while reducing the relative richness of harmful bacteria, predominantly Enterobacteriaceae, suggesting that GABABR signaling may have contributed to reversing intestinal flora imbalances to relieve oxidative stress in LPS-induced mice. Our study identified previously unappreciated roles for GABABR signaling in constricting oxidative stress to attenuate enteritis, thus offering novel insights for the treatment of intestinal inflammation.

Mouse intestinal microbiome modulation by oral administration of a GABA-producing Bifidobacterium adolescentis strain

IMPORTANCE

The gut microbiome-brain communication signaling has emerged in recent years as a novel target for intervention with the potential to ameliorate some conditions associated with the central nervous system. Hence, probiotics with capacity to produce neurotransmitters, for instance, have come up as appealing alternatives to treat disorders associated with disbalanced neurotransmitters. Herein, we further deep into the effects of administering a gamma-aminobutyric acid (GABA)-producing Bifidobacterium strain, previously demonstrated to contribute to reduce serum glutamate levels, in the gut microbiome composition and metabolic activity in a mouse model. Our results demonstrate that the GABA-producing strain administration results in a specific pattern of gut microbiota modulation, different from the one observed in animals receiving non-GABA-producing strains. This opens new avenues to delineate the specific mechanisms by which IPLA60004 administration contributes to reducing serum glutamate levels and to ascertain whether this effect could exert health benefits in patients of diseases associated with high-glutamate serum concentrations.

Gut microbiota bridges dietary nutrients and host immunity

Dietary nutrients and the gut microbiota are increasingly recognized to cross-regulate and entrain each other, and thus affect host health and immune-mediated diseases. Here, we systematically review the current understanding linking dietary nutrients to gut microbiota-host immune interactions, emphasizing how this axis might influence host immunity in health and diseases. Of relevance, we highlight that the implications of gut microbiota-targeted dietary intervention could be harnessed in orchestrating a spectrum of immune-associated diseases.

Activation of GABA receptor attenuates intestinal inflammation by modulating enteric glial cells function through inhibiting NF-κB pathway

AIMS

Emerging research indicates that γ-aminobutyric acid (GABA) provides substantial benefits during enteritis. Nevertheless, GABA signaling roles on enteric glial cells (EGCs) remain unknown. The study's objective was to evaluate the underlying mechanisms of GABA signaling on EGCs in vitro and in vivo.

MAIN METHODS

We established LPS-induced mouse models and stimulated EGCs with LPS to mimic intestinal inflammation, and combined GABA, GABAA receptor (GABAAR) or GABAB receptor (GABABR) agonists to explore the exact mechanisms of GABA signaling.

KEY FINDINGS

EGCs were immunopositive for GAD65, GAD67, GAT1, GABAARα1, GABAARα3, and GABABR1, indicating GABAergic and GABAceptive properties. GABA receptor activation significantly inhibited the high secretions of proinflammatory factors in EGCs upon LPS stimulation. Interestingly, we found that EGCs express immune-related molecules such as CD16, CD32, CD80, CD86, MHC II, iNOS, Arg1, and CD206, thus establishing their characterization of E1 and E2 phenotype. EGCs exposed to LPS mainly acted as E1 phenotype, whereas GABABR activation strongly promoted EGCs polarization into E2 phenotype. Transcriptome analysis of EGCs indicated that GABA, GABAAR or GABABR agonists treatment participated in various biological processes, however all of these treatments exhibit inhibitory effects on NF-κB pathway. Notably, in LPS-induced mice, activation of GABABR mitigated intestinal damage through modulating inflammatory factors expressions, strengthening sIgA and IgG levels, inhibiting NF-κB pathway and facilitating EGCs to transform into E2 phenotype.

SIGNIFICANCE

These data demonstrate that the anti-inflammatory actions of GABA signaling system offer in enteritis via regulating EGCs-polarized function through impeding NF-κB pathway, thus providing potential targets for intestinal inflammatory diseases.

The metabolic impact of bacterial infection in the gut

Bacterial infections of the gut are one of the major causes of morbidity and mortality worldwide. The interplay between the pathogen and the host is finely balanced, with the bacteria evolving to proliferate and establish infection. In contrast, the host mounts a response to first restrict and then eliminate the infection. The intestine is a rapidly proliferating tissue, and metabolism is tuned to cater to the demands of proliferation and differentiation along the crypt-villus axis (CVA) in the gut. As bacterial pathogens encounter the intestinal epithelium, they elicit changes in the host cell, and core metabolic pathways such as the tricarboxylic acid (TCA) cycle, lipid metabolism and glycolysis are affected. This review highlights the mechanisms utilized by diverse gut bacterial pathogens to subvert host metabolism and describes host responses to the infection.

GABA regulates IL-1β production in macrophages

Neurotransmitters have been well documented to determine immune cell fates; however, whether and how γ-amino butyric acid (GABA) shapes the function of innate immune cells is still obscure. Here, we demonstrate that GABA orchestrates macrophage maturation and inflammation. GABA treatment during macrophage maturation inhibits interleukin (IL)-1β production from inflammatory macrophages. Mechanistically, GABA enhances succinate-flavin adenine dinucleotide (FAD)-lysine specific demethylase1 (LSD1) signaling to regulate histone demethylation of Bcl2l11 and Dusp2, reducing formation of the NLRP3-ASC-Caspase-1 complex. The GABA-succinate axis reduces succinylation of mitochondrial proteins to promote oxidative phosphorylation (OXPHOS). We also find that GABA alleviates lipopolysaccharides (LPS)-induced sepsis as well as high-fat-diet-induced obesity in mice. Our study shows that GABA regulates pro-inflammatory macrophage responses associated with metabolic reprogramming and protein succinylation, suggesting a strategy for treating macrophage-related inflammatory diseases.

Melatonin shapes bacterial clearance function of porcine macrophages during enterotoxigenic Escherichia coli infection

Due to the immature gastrointestinal immune system, weaning piglets are highly susceptible to pathogens, e.g., enterotoxigenic Escherichia coli (ETEC). Generally, pathogens activate the immune cells (e.g., macrophages) and shape intracellular metabolism (including amino acid metabolism); nevertheless, the metabolic cues of tryptophan (especially melatonin pathway) in directing porcine macrophage function during ETEC infection remain unclear. Therefore, this study aimed to investigate the changes in the serotonin pathway of porcine macrophages during ETEC infection and the effect of melatonin on porcine macrophage functions. Porcine macrophages (3D4/21 cells) were infected with ETEC, and the change of serotonin pathway was analysed by reverse transcription PCR and metabolomic analysis. The effect of melatonin on porcine macrophage function was also studied with proteomic analysis. In order to investigate the effect of melatonin on bacterial clearance function of porcine macrophages during ETEC infection, methods such as bacterial counting, reverse transcription PCR and western blotting were used to detect the corresponding indicators. The results showed that ETEC infection blocked melatonin production in porcine macrophages (P < 0.05) which is largely associated with the heat-stable enterotoxin b (STb) of ETEC (P < 0.05). Interestingly, melatonin altered porcine macrophage functions, including bacteriostatic and bactericidal activities based on proteomic analysis. In addition, melatonin pre-treatment significantly reduced extracellular lactate dehydrogenase (LDH) activity (P < 0.05), indicating that melatonin also attenuated ETEC-triggered macrophage death. Moreover, melatonin pre-treatment resulted in the decrease of viable ETEC in 3D4/21 cells (P < 0.05), suggesting that melatonin enhances bacterial clearance of porcine macrophages. These results suggest that melatonin is particularly important in shaping porcine macrophage function during ETEC infection.

A critical role of AMP-activated protein kinase in regulating intestinal nutrient absorption, barrier function, and intestinal diseases

As one of the most important organs in animals, the intestine is responsible for nutrient absorption and acts as a barrier between the body and the environment. Intestinal physiology and function require the participation of energy. 5'-adenosine monophosphate-activated protein kinase (AMPK), a classical and highly expressed energy regulator in intestinal cells, regulates the process of nutrient absorption and barrier function and is also involved in the therapy of intestinal diseases. Studies have yielded findings that AMPK regulates the absorption of glucose, amino acids, and fatty acids in the intestine primarily by regulating transportation systems, as we detailed here. Moreover, AMPK is involved in the regulation of the intestinal mechanical barrier and immune barrier through manipulating the expression of tight junctions, antimicrobial peptides, and secretory immunoglobulins. In addition, AMPK also participates in the regulation of intestinal diseases, which indicates that AMPK is a promising therapeutic target for intestinal diseases and cancer. In this review, we summarized the current understanding regarding how AMPK regulates intestinal nutrient absorption, barrier function, and intestinal diseases.

β-defensin 118 attenuates inflammation and injury of intestinal epithelial cells upon enterotoxigenic Escherichia coli challenge

Background

Antimicrobial peptides including various defensins have been attracting considerable research interest worldwide, as they have potential to substitute for antibiotics. Moreover, AMPs also have immunomodulatory activity. In this study, we explored the role and its potential mechanisms of β-defensin 118 (DEFB118) in alleviating inflammation and injury of IPEC-J2 cells (porcine jejunum epithelial cell line) upon the enterotoxigenic Escherichia coli (ETEC) challenge.

Results

The porcine jejunum epithelial cell line (IPEC-J2) pretreated with or without DEFB118 (25 μg/mL) were challenged by ETEC (1×10⁶ CFU) or culture medium. We showed that DEFB118 pretreatment significantly increased the cell viability (P<0.05) and decreased the expressions of inflammatory cytokines such as the interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in IPEC-J2 cells exposure to ETEC (P<0.05). Interestingly, DEFB118 pretreatment significantly elevated the abundance of the major tight-junction protein zonula occludens-1 (ZO-1), but decreased the number of apoptotic cells upon ETEC challenge (P<0.05). The expression of caspase 3, caspase 8, and caspase 9 were downregulated by DEFB118 in the IPEC-J2 cells exposure to ETEC (P<0.05). Importantly, DEFB118 suppressed two critical inflammation-associated signaling proteins, nuclear factor-kappa-B inhibitor alpha (IκB-α) and nuclear factor-kappaB (NF-κB) in the ETEC-challenged IPEC-J2 cells.

Conclusions

DEFB118 can alleviate ETEC-induced inflammation in IPEC-J2 cells through inhibition of the NF-κB signaling pathway, resulting in reduced secretion of inflammatory cytokines and decreased cell apoptosis. Therefore, DEFB118 can act as a novel anti-inflammatory agent.

Itaconate, Arginine, and Gamma-Aminobutyric Acid: A Host Metabolite Triad Protective Against Mycobacterial Infection

Immune metabolic regulation shapes the host-pathogen interaction during infection with Mycobacterium tuberculosis (Mtb), the pathogen of human tuberculosis (TB). Several immunometabolites generated by metabolic remodeling in macrophages are implicated in innate immune protection against Mtb infection by fine-tuning defensive pathways. Itaconate, produced by the mitochondrial enzyme immunoresponsive gene 1 (IRG1), has antimicrobial and anti-inflammatory effects, restricting intracellular mycobacterial growth. L-arginine, a component of the urea cycle, is critical for the synthesis of nitric oxide (NO) and is implicated in M1-mediated antimycobacterial responses in myeloid cells. L-citrulline, a by-product of NO production, contributes to host defense and generates L-arginine in myeloid cells. In arginase 1-expressing cells, L-arginine can be converted into ornithine, a polyamine precursor that enhances autophagy and antimicrobial protection against Mtb in Kupffer cells. Gamma-aminobutyric acid (GABA), a metabolite and neurotransmitter, activate autophagy to induce antimycobacterial host defenses. This review discusses the recent updates of the functions of the three metabolites in host protection against mycobacterial infection. Understanding the mechanisms by which these metabolites promote host defense will facilitate the development of novel host-directed therapeutics against Mtb and drug-resistant bacteria.

Dietary gamma-aminobutyric acid ameliorates growth impairment and intestinal dysfunction in turbot (Scophthalmus maximus L.) fed a high soybean meal diet

Over-substitution of fishmeal with soybean meal (SBM) commonly induces inferior growth and intestinal dysfunction in fish. This study aims to evaluate whether dietary gamma-aminobutyric acid (GABA) could ameliorate the adverse effects in turbot fed a high-SBM diet (HSD). Two hundred and seventy turbots were randomly divided into three treatment groups including turbots fed on a control diet (CNT, containing 60% fishmeal), an HSD (with 45% fishmeal protein replaced by SBM), and an HSD supplemented with GABA (160 mg kg-1) for 53 days. The growth and feed utilization parameters were calculated and the intestinal antioxidant status, inflammation, apoptosis, and microbiota were evaluated using assay kits, histological analysis, qRT-PCR, high throughput sequencing, and bioinformatics analysis. The results showed that GABA ameliorated HSD-induced growth impairment and enhanced feed intake of turbot. GABA ameliorated HSD-induced intestinal oxidative stress and apoptosis by restoring the MDA content, CAT and T-AOC activities, and apoptosis-related gene (Bcl-2, Bax, Bid, and Caspase-3) expressions to similar levels to those in the CNT group. GABA also alleviated HSD-induced intestinal inflammation through down-regulating the expressions of TNF-α, IL-1β, and NF-κB p65 and up-regulating the expression of TGF-β1. Furthermore, GABA reversed HSD-induced microbiota dysbiosis through regulating the overall bacterial richness and dominative bacterial population. Spearman's correlation analysis indicated that the altered microbiota was closely associated with growth and intestinal function. Collectively, GABA could ameliorate HSD-induced intestinal dysfunction via relieving oxidative stress, inflammation, apoptosis and microbiota dysbiosis, and these findings would contribute to a better understanding of the function of GABA in the fish intestine.

Exopolysaccharides from Bifidobacterium animalis Ameliorate Escherichia coli-Induced IPEC-J2 Cell Damage via Inhibiting Apoptosis and Restoring Autophagy

Enteropathogenic Escherichia coli (EPEC) is a common zoonotic pathogen that causes acute infectious diarrhea. Probiotics like Bifidobacterium are known to help prevent pathogen infections. The protective effects of Bifidobacterium are closely associated with its secretory products exopolysaccharides (EPS). We explored the effects of the EPS from Bifidobacterium animalis subsp. lactis (B. lactis) on ameliorating the damage of an intestinal porcine epithelial cell line (IPEC-J2) during EPEC infection. Pretreatment with EPS alleviated EPEC-induced apoptosis through the restoration of cell morphology and the downregulation of protein expressions of cleaved-caspase 8, cleaved-caspase 3, and cleaved-PARP. EPS-mediated remission of apoptosis significantly improved cell viability during EPEC infection. EPEC infection also resulted in impaired autophagy, as demonstrated by decreased expressions of autophagy-related proteins Beclin 1, ATG5, and microtubule-binding protein light chain-3B (LC3B) and the increased expression of p62 through western blot analysis. However, EPS reversed these effects which indicated that EPS promoted autophagosome formation. Furthermore, EPS prevented the lysosome damage induced by EPEC as it enhanced lysosomal acidification and raised lysosome-associated protein levels, thus promoted autophagosome degradation. Our findings suggest that the amelioration of EPEC-induced cell damages by EPS is associated with the limitation of detrimental apoptosis and the promotion of autophagy flux.

Effects of dietary gamma-aminobutyric acid supplementation on amino acid profile, intestinal immunity, and microbiota in ETEC-challenged piglets

Enterotoxigenic Escherichia coli (ETEC) infection is the most common cause of diarrhea in piglets, and ETEC could increase intestinal gamma-aminobutyric acid (GABA)-producing bacteria to affect intestinal immunity. However, the effect of GABA on ETEC-infected piglets is still unclear. This study aims at investigating the impact of dietary GABA supplementation on the growth performance, diarrhea, intestinal morphology, serum amino acid profile, intestinal immunity, and microbiota  in the ETEC-infected piglet model. Eighteen piglets were randomly divided into two groups, in which the piglets were fed with a basal diet with 20 mg kg-1 GABA supplementation or not. The experiment lasted for three weeks, and the piglets were challenged with ETEC K88 on the fifteenth day. The results showed that dietary GABA reduced the feed conversion ratio, promoted the kidney organ index but did not affect the diarrheal score and small intestinal morphology in ETEC-challenged piglets. Ileal mucosal amino acids (such as carnosine and anserine) and serum amino acids (including threonine and GABA) were increased upon GABA supplementation. GABA enhanced ileal gene expression of TNF-α, IFN-γ, pIgR, and MUC2, while inhibited the ileal expression of IL-18 in ETEC-challenged piglets. GABA supplementation also highly regulated the intestinal microbiota by promoting community richness and diversity and reducing the abundance of the dominant microbial population of the ileal microbiota. Collectively, GABA improves growth performance, regulates the serum amino acid profile, intestinal immunity, and gut microbiota in ETEC-challenged piglets. This study is a fine attempt to reveal the function of GABA in ETEC-infected piglets. It would contribute to the understanding of the roles of exogenous nutrition on the host response to ETEC infection.

Deletion of FaeG alleviated Enterotoxigenic Escherichia coli F4ac-induced apoptosis in the intestine

Enterotoxigenic Escherichia coli (ETEC) F4ac is a major constraint to the development of the pig industry, which is causing newborn and post-weaning piglets diarrhea. Previous studies proved that FaeG is the major fimbrial subunit of F4ac E. coli and efficient for bacterial adherence and receptor recognition. Here we show that the faeG deletion attenuates both the clinical symptoms of F4ac infection and the F4ac-induced intestinal mucosal damage in piglets. Antibody microarray analysis and the detection of mRNA expression using porcine neonatal jejunal IPEC-J2 cells also determined that the absence of FaeG subunit alleviated the F4ac promoted apoptosis in the intestinal epithelial cells. Thus, targeted depletion of FaeG is still beneficial for the prevention or treatment of F4ac infection.

Chicory fibre improves reproductive performance of pregnant rats involving in altering intestinal microbiota composition

AIM

Chicory fibre (CF) is rich in fructan, which always functions as a quality dietary fibre source during mammalian pregnancy; however, its effect on reproductive performance remains unclear.

METHODS AND RESULTS

40 pregnant SD rats were randomly allotted to receive one of four diets: basal diet (control group), basal diet + 5% CF, basal diet + 10% CF, and basal diet + 15% CF, respectively. We found that CF significantly increased the number born alive and total litter birth weight (P < 0·05), increased the expression of intestinal tight junction proteins, mucins and antimicrobial peptides, accompanied by the increase of villi height and the decrease of crypts depth of pregnant SD rats (P < 0·05). We also observed that CF markedly increased the acetic acid, propanoic acid, butyric acid and total SCFAs concentrations in caecum contents and promoted the expression of SCFAs-related receptors (P < 0·05). Notably, rats fed CF increased the relative abundance of Bacteroidetes (P < 0·001), decreased the relative abundance of Firmicutes and Proteobacteria, while markedly lowered the Firmicutes/ Bacteroidetes ratio (F/B ratio) (P < 0·05). Intriguingly, the number born alive and total litter birth weight were positively correlated with some probiotics and negatively correlated with other harmful bacteria by Pearson correlation analysis.

CONCLUSION

Collectively, CF can enhance intestinal barrier function and maintain intestinal health, and may improve reproductive performance by altering intestinal microbiota composition.

SIGNIFICANCE AND IMPACT OF THE STUDY

Adding suitable dietary fibre to the diet can improve the reproductive performance of sows. Indeed, there exist various problems in the application of traditional dietary fibres, including high insoluble fibre content and anti-nutritional factor level, and mycotoxin contamination. This study demonstrates that dietary CF supplementation improves reproductive performance and intestinal health. Thus, CF can be applied in pregnancy animals as a new dietary fibre additive in animal husbandry.

Effects of Deoxynivalenol-Contaminated Diets on Productive, Morphological, and Physiological Indicators in Broiler Chickens

Simple Summary

The presence of mycotoxins in feed is a really significant problem worldwide; it leads to adverse effects on animals and great economic losses, especially in the monogastric industry. Deoxynivalenol (DON) is one of these mycotoxins that contaminates poultry feed and consequently has negative effects on this specie. Different concentrations of DON (5 and 15 mg/kg feed) were tested in broiler chickens. Results showed that high levels could adversely affect productive and welfare parameters; however, organ weights, morphological intestine indicators, and biochemical parameters were affected at low and high level of dietary DON. In general, even the low level of DON (5 mg/kg), which is the guidance level in complete poultry feed could affect the physiological status of birds.

Abstract

The present study with 1-day-old male broilers (Ross 308) was conducted to evaluate the effects of deoxynivalenol (DON) at different levels (5 and 15 mg/kg feed) on growth performance, relative weight of organs, morphology of the small intestine, serum biochemistry, and welfare parameters of broiler chickens. Forty-five broiler chicks were randomly divided into three different experimental groups with five replicates each: (1) control group received a non-contaminated diet, (2) contaminated diet with 5 mg DON/kg of feed, and (3) contaminated diet with 15 mg DON/kg of feed for 42 days. Results showed that feed artificially contaminated with DON at guidance level (5 mg/kg diet) did not affect growth performance parameters. However, 15 mg/kg reduced body weight gain and altered feed efficiency. DON at two assayed levels significantly increased the absolute and relative weight of thymus and the relative weight of gizzard and decreased the absolute and the relative weight of the colon. Compared to controls, both doses affected small intestine morphometry parameters. In terms of biochemical indicators, DON at 5 mg/kg reduced the creatine kinase level and at 15 mg/kg DON reduced the cholesterol level. Furthermore, DON at 15 mg/kg induced more fear in broilers compared to broilers fed the guidance level. It was concluded that even the guidance level of DON did not affect the chickens’ performance. However, its toxic effect occurred in some organs and biochemical parameters.

Effects of dietary supplementation with herbal extract mixture on growth performance, organ weight and intestinal morphology in weaning piglets

BACKGROUND

Many countries are increasingly prohibiting the addition of antibiotics in livestock diets. Therefore, herb extracts have gradually drawn attention to substitute antibiotics. Our present study aimed to determine the effects of herbal extract mixture (HEM) in dietary on growth performance, organ weight, intestinal morphology and intestinal nutrient transporters in weaned pigs.

METHODS

27 piglets (Duroc × [Landrace × Yorkshire]; Body Weight (BW) = 5.99 ± 0.13 kg) were weaned at day 21 and randomly divided into three groups (n = 9 piglets/group). All piglets received a basal diet containing similar amounts of nutrients for 14 days. The three groups were the control (no additive), the antibiotics (375 mg/kg chlortetracycline, 20%, 500 mg/kg enramycin, 4%, 1,500 mg/kg oxytetracycline calcium, 50%) and the HEM group (1000 mg/kg extract mixture of golden-and-silver honeysuckle, huangqi, duzhong leaves and dangshen). After 14 d of treatment, we collected tissue samples to measure organ weight, intestinal parameters, intestinal morphology, digestive enzyme activities and intestinal mRNA expression of nutrient transporters.

RESULTS

The HEM group had no effects on growth performance and organ weight of weaned pigs. But compared with the control group, both HEM and antibiotics improved intestinal morphology, and HEM elevated the expression of nutrient transporters in ileum (SLC6A9, SLC15A1, and SLC5A1). HEM significantly decreased the activities of maltase in ileum and the ratio of small intestinal weight to BW than control group.

CONCLUSIONS

These results indicate benefit effects of the supplementation of HEM in diet, including modulating intestinal morphology and increasing the mRNA expression of nutrients transporters. These findings suggest that HEM provides novel insights into a variety of herbal extract mixtures to replace antibiotics in animal production.

Effects of GABA Supplementation on Intestinal SIgA Secretion and Gut Microbiota in the Healthy and ETEC-Infected Weanling Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) has been considered a major cause of diarrhea which is a serious public health problem in humans and animals. This study was aimed at examining the effect of γ-aminobutyric acid (GABA) supplementation on intestinal secretory immunoglobulin A (SIgA) secretion and gut microbiota profile in healthy and ETEC-infected weaning piglets. A total of thirty-seven weaning piglets were randomly distributed into two groups fed with the basal diet or supplemented with 40 mg·kg-1 of GABA for three weeks, and some piglets were infected with ETEC at the last week. According to whether ETEC was inoculated or not, the experiment was divided into two stages (referred as CON1 and CON2 and GABA1 and GABA2). The growth performance, organ indices, amino acid levels, and biochemical parameters of serum, intestinal SIgA concentration, gut microbiota composition, and intestinal metabolites were analyzed at the end of each stage. We found that, in both the normal and ETEC-infected piglets, jejunal SIgA secretion and expression of some cytokines, such as IL-4, IL-13, and IL-17, were increased by GABA supplementation. Meanwhile, we observed that some low-abundance microbes, like Enterococcus and Bacteroidetes, were markedly increased in GABA-supplemented groups. KEGG enrichment analysis revealed that the nitrogen metabolism, sphingolipid signaling pathway, sphingolipid metabolism, and microbial metabolism in diverse environments were enriched in the GABA1 group. Further analysis revealed that alterations in microbial metabolism were closely correlated to changes in the abundances of Enterococcus and Bacteroidetes. In conclusion, GABA supplementation can enhance intestinal mucosal immunity by promoting jejunal SIgA secretion, which might be related with the T-cell-dependent pathway and altered gut microbiota structure and metabolism.

Daily consumption of a homeopathic product decreases intestinal damage and stool bacterial counts in mice challenged with Escherichia coli

Escherichia coli is a bacterium normally found in the gastrointestinal tract of domestic animals that can usually control the infection. Nevertheless, some factors (high exposure, stress conditions, animal category, among others) can favor the exacerbation of E. coli infection and cause of disease. Because it is a zoonotic bacterium, it is important to control the infection, avoiding contamination of home interiors in the case of pets. There are various forms of treatment for E. coli; nevertheless, there are few options for prevention. In the present study, we evaluated homeopathy. Thus, the objective of this study was to determine whether administration of a prophylactic homeopathic in water would minimize the negative effects of E. coli infection, as well as reducing bacterial counts in the feces of a experimental model. Forty mice were divided into four experimental groups (n = 10/group). Groups NC (negative control) and PC (positive control) were not treated; in group T1, the animals received 0.002 mL/day/animal of the homeopathic in water, and animals in group T2 0.004 mL/day/animal. The experiment lasted 54 days, and on the 31st day, mice of T1, T2 and PC groups were infected orally a 0.2 mL inoculum of 1.5 × 10⁸ CFU of E. coli. Euthanasia and sample collection were performed on the 40th and 54th days of the experiment (n = 5/group/time point). Blood, liver, spleen, intestine, and feces samples were collected from the final portion of the intestine. There was no significant difference in animal weight between groups at the end of the experiment. Neutrophil count was lower in PC group animals on day 40, while on day 54, the counts were lower in T2 and PC. Lymphocyte counts were lower only in the PC group than in the NC group on day 54. Globulins were lower in the NC and PC groups than in T1 and T2 on day 40, remaining lower the PC group and higher in T1 on day 54; levels of immunoglobulin IgG and IgM were higher in groups T1 and T2, which differed from PC and NC. TNF-α levels were higher in the T1 and T2 groups at 40 and 54 days. INF-γ levels were higher in T1, T2, and PC compared to NC on day 40, remaining higher than NC in groups T1 and T2 on day 54. Total bacterial count, total coliforms and E. coli counts were lower in group T1 and higher in NC and PC on days 40 and 54, when they were lower for T1 and T2. Histologically, no lesions were observed in extra-intestinal tissues; however the height of intestinal crypts in the PC group was smaller than the others on day 40. On day 54, villi and crypts of all infected groups were larger in T1 and T2 than in NC; sizes in the PC group were higher than those of all other groups. These data suggest that the homeopathic agent in the drinking water improved health of the mice.