Epidermal growth factor-expressing Lactococcus lactis enhances intestinal development of early-weaned pigs

Expression of chicken epidermal growth factor (cEGF) in Escherichia coli regulates the microflora structure of the duodenum to improve growth performance and intestinal morphogenesis in broilers

1. A study used gene synthesis to obtain the functional domains of chicken epidermal growth factor (cEGF) and examined their impact on broiler growth performance, small intestinal morphology, digestive enzyme activities in the intestinal contents and the structure of duodenal microflora.2. The pET-32a-cEGF recombinant expression vector was constructed. The specific band at 26 KDa was shown by SDS-PAGE analysis and WB results. The purified protein content was shown to be 1687 μg/ml by assay.3. A total of 180 healthy, one-day-old Arbor Acres male, white-feathered broilers were randomly divided into three dietary treatment groups (six replicate pens, 10 birds per replicate): A control diet (ND); cEGF diet (cEGF), control supplemented with 250 mg/kg cEGF and the control diet (CD) supplemented with 250 mg/kg chlortetracycline.4. The results showed that feeding the cEGF and CD diet reduced FCR of broilers aged 1-21 d, average daily feed intake (ADFI) at 22-42 d, and the FCR in the whole period (1-42 d; p < 0.05). Compared with the ND group, the cEGF diet increased duodenal α-amylase and alkaline phosphatase activities in the 1-21 d, duodenal lipase, alkaline phosphatase, and ileal alkaline phosphatase activities in the post-period and increased villus height in the duodenum and ileum (p < 0.05). In addition, the ACE and Chao1 index for the birds fed cEGF were higher than the ND group (p < 0.05). At the phyla level, Firmicutes and Proteobacteria were dominant in all groups. At the genus level, the dominant genus was Lactobacillus. The LEfSe analysis showed that the cEGF group was enriched by 11 species including Brevibacillus, Eisenbergiella, Cloacibacterium, Butyricoccus spp.5. The addition of 250 mg/kg cEGF to the diet can increase growth performance by improving intestinal development and digestive enzyme activity, which may be related to the duodenal intestinal microflora. Therefore, cEGF is an effective alternative to antibiotics in broiler farming.

Mechanisms of Epidermal Growth Factor Effect on Animal Intestinal Phosphate Absorption: A Review

Phosphorus is one of the essential mineral elements of animals that plays an important role in animal growth and development, bone formation, energy metabolism, nucleic acid synthesis, cell signal transduction, and blood acid–base balance. It has been established that the Type IIb sodium-dependent phosphate cotransporters (NaPi-IIb) protein is the major sodium-dependent phosphate (Pi) transporter, which plays an important role in Pi uptake across the apical membrane of epithelial cells in the small intestine. Previous studies have demonstrated that epidermal growth factor (EGF) is involved in regulating intestinal Pi absorption. Here we summarize the effects of EGF on active Pi transport of NaPi-IIb under different conditions. Under normal conditions, EGF inhibits the active transport of Pi by inhibiting the expression of NaPi-IIb, while, under intestinal injury condition, EGF promotes the active absorption of Pi through upregulating the expression of NaPi-IIb. This review provides a reference for information about EGF-regulatory functions in Pi absorption in the animal intestine.

The effect of epidermal growth factor on performance and oxidative stress in piglets challenged with enterotoxigenic Escherichia coli K88

This study evaluated the efficacy of epidermal growth factor (EGF) in piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). A total of 28 piglets were assigned to the following dietary treatments for 14 d: negative control (NC) (basal diet containing supernatant without EGF), PC (NC + 2.5 g antibiotic·kg−1 feed), EGF120 [basal diet + supernatant with 120 μg EGF·kg−1 body weight (BW)·d−1], and EGF180 (basal diet + supernatant with 180 μg EGF·kg−1 BW·d−1). After a 6 d acclimation period, each pig was gavaged with 6 mL (2.4 × 1013 cfu·mL−1) of ETEC on the morning of day 7. Overall, piglets fed the EGF and PC diets tended to have higher gain to feed ratio than those fed the NC diet (P = 0.063). Pigs fed EGF diets had lower rectal temperature than those fed the NC diet at 6 h after challenge (P < 0.05). Serum and ileal malondialdehyde concentrations were higher in piglets fed the NC diet compared with those fed EGF and PC diets on days 6 and 7 after challenge, respectively (P < 0.05). In conclusion, EGF has the potential to reduce oxidative stress and body temperature elevation in piglets exposed to ETEC while supporting better feed efficiency.

Dietary Supplementation of EGF Ameliorates the Negatively Effects of LPS on Early-Weaning Piglets: From Views of Growth Performance, Nutrient Digestibility, Microelement Absorption and Possible Mechanisms

Simple Summary

This study aims to investigate how epidermal growth factor (EGF) attenuates the effect of lipopolysaccharide (LPS) on the growth performance, nutrient digestibility, microelement absorption of early-weaned pigs. A total of 48 early weaned piglets were randomly distributed to four groups consisting of a 2 × 2 factorial design. The main factors were the level of LPS (H_LPS = high LPS: 100 μg/kg body weight; Z_LPS = low LPS: 0 μg/kg body weight) and EGF (H_EGF = high EGF: 2 mg/kg diet; Z_EGF = low EGF: 0 mg/kg diet). Each group had four replicates and each replicate consisted of three piglets. The results showed that H_LPS level decreased the growth performance and the apparent digestibility of crude fat, while H_EGF level increased the average daily feed intake. The concentration of most microelements in the gastrointestinal tract chyme and feces were increased by H_LPS level and decreased by H_EGF level. The expression levels of most microelement transport-relative genes in the mucosa of gastrointestinal tissues were decreased by H_LPS level and increased by H_EGF level. In conclusion, dietary EGF could attenuate the negative effect of LPS exposure on the apparent digestibility of crude fat and microelement absorption through changing the expression levels of microelement transport-relative genes. EGF can be used as an additive to increase the essential trace elements absorption in the early weaning piglets.

Abstract

Epidermal growth factor (EGF) plays an important role in nutrients absorption. However, whether it can be an effective additive to improve the growth performance and nutrients absorption in lipopolysaccharide (LPS) challenged early weaning piglets is still unknown. A 14-days trial was conducted to investigate how EGF attenuates the effect of LPS on the growth performance, nutrient digestibility, microelement absorption of early-weaned pigs, and study the underlying mechanism. A total of 48 early weaned piglets, aged 25 days, were randomly distributed to four groups (control, EGF, LPS and EGF + LPS groups) consisting of a 2 × 2 factorial design. The main factors were the level of LPS (H_LPS = high LPS: 100 μg/kg body weight; Z_LPS = low LPS: 0 μg/kg body weight) and EGF (H_EGF = high EGF: 2 mg/kg diet; Z_EGF = low EGF: 0 mg/kg diet). Each group had four replicates and each replicate consisted of three piglets. The results showed that piglets injected with H_LPS level significantly decreased the average daily gain (ADG), and significantly increased the feed conversion ratio (FCR) compared with the piglets injected with Z_LPS level, while piglets fed H_EGF level significantly increased the average daily feed intake (ADFI) compared with the piglets fed Z_EGF level (p < 0.05). Piglets injected with H_LPS level significantly decreased the apparent digestibility of crude fat compared with the piglets injected with Z_LPS level (p < 0.05). Piglets injected with H_LPS level significantly increased the concentration of most microelements in the gastrointestinal tract chyme and feces, and significantly decreased the expression levels of most microelement transport-relative genes in the mucosa of gastrointestinal tissues compared with the piglets injected with Z_LPS level (p < 0.05). Piglets fed H_EGF level significantly decreased the concentration of microelement in the gastrointestinal tract chyme and feces, and significantly increased the expression levels of the microelement transport-relative genes in the mucosa of gastrointestinal tissues compared with the piglets fed Z_EGF level (p < 0.05). In conclusion, dietary EGF could attenuate the negative effect of LPS exposure on the apparent digestibility of crude fat and microelement absorption of early-weaning piglets. EGF and LPS influenced the absorption of essential trace element through changing the expression levels of microelement transport-relative genes in the mucosa of gastrointestinal tissues. In the early weaning piglets, EGF can be used as an additive to increase the essential trace elements absorption.

Expression of Gallus Epidermal Growth Factor (gEGF) with Food-Grade Lactococcus lactis Expression System and Its Biological Effects on Broiler Chickens

As a multifunctional polypeptide, epidermal growth factor (EGF) increases growth performance or enhances resistance to diseases in commercial broilers under adverse conditions. In this study, a recombinant Lactococcus lactis was established to produce the secretory form of bioactive gEGF. The results of in vitro testing showed that gEGF promoted the proliferation of chicken embryo fibroblast cells. A total of 63 5-day-old broiler chickens were evenly divided into three groups and treated with either M17 medium (the control group), supernatant of LL-pNZ8149 fermentation product (the P-LL group), or supernatant of LL-pNZ8149-gEGF fermentation product (the gEGF group). In two weeks, many measurements of growth, immunity and the intestines were significantly higher in the gEGF group than those in the control and the P-LL groups. Our study showed that the bioactive gEGF could be expressed with Lactococcus lactis expression system with the potential to enhance growth performance, immune function, and intestinal development in broiler chickens.

In ovo feeding of epidermal growth factor: embryonic expression of intestinal epidermal growth factor receptor and posthatch growth performance and intestinal development in broiler chickens

We investigated efficacy of in ovo application of epidermal growth factor (EGF) on intestinal expression of EGF receptor (EGFR) during embryogenesis (experiment 1) and posthatch growth performance and gastrointestinal development in broiler chickens (experiment 2). In experiment 1, 450 fertile Ross 708 eggs were allocated to 3 groups (150 eggs/group): 1) control, 2) 160 μg EGF/kg of egg, and 3) 640 μg of EGF/kg of egg. Eggs were candled for live embryos on day 16 and injected with the respective treatment solutions on day 17 and sampled for jejunal tissue from day 17 to hatch for EGFR analyses. There was no effect of EGF (P > 0.05) on EGFR expression on day 17 to 20; however, on day 21, EGF increased (P < 0.05) EGFR expression in EGF birds relative to control birds. In experiment 2, 600 fertile Ross 708 eggs were allocated to 5 treatments: 1) intact, no puncture or injection, 2) punched but not injected, 3) control, no EGF, 4) 80 μg of EGF/kg of egg, and 5) 160 μg of EGF/kg of egg. The eggs were incubated and candled for live embryos on D 19, treated, and subsequently transferred to the hatcher. Upon hatching, chicks were weighed, and 90 chicks per treatment placed in cages (15 birds/cage) and allowed free access to a standard antibiotic-free corn-soybean diet for 21 D. Feed intake and body weight were monitored on a weekly basis. Samples of birds were necropsied on D 0, 7, 14, and 21 for measurements of intestinal weight and jejunal histomorphology and excreta samples taken on D 3 to 5 and 17 to 19 for apparent retention of dry matter. There was no EGF effect (P > 0.05) on any posthatch response criteria. In conclusion, in ovo application of EGF increased EGFR expression but had no effect on posthatch growth performance, DM retention, and intestinal development. The lack of EGF effect on posthatch response was surprising but suggested in ovo application of EGF may not be a viable approach.

Novel Strategies to Prevent Total Parenteral Nutrition-Induced Gut and Liver Inflammation, and Adverse Metabolic Outcomes

Total parenteral nutrition (TPN) is a life-saving therapy administered to millions of patients. However, it is associated with significant adverse effects, namely liver injury, risk of infections, and metabolic derangements. In this review, the underlying causes of TPN-associated adverse effects, specifically gut atrophy, dysbiosis of the intestinal microbiome, leakage of the epithelial barrier with bacterial invasion, and inflammation are first described. The role of the bile acid receptors farnesoid X receptor and Takeda G protein-coupled receptor, of pleiotropic hormones, and growth factors is highlighted, and the mechanisms of insulin resistance, namely the lack of insulinotropic and insulinomimetic signaling of gut-originating incretins as well as the potentially toxicity of phytosterols and pro-inflammatory fatty acids mainly released from soybean oil-based lipid emulsions, are discussed. Finally, novel approaches in the design of next generation lipid delivery systems are proposed. Propositions include modifying the physicochemical properties of lipid emulsions, the use of lipid emulsions generated from sustainable oils with favorable ratios of anti-inflammatory n-3 to pro-inflammatory n-6 fatty acids, beneficial adjuncts to TPN, and concomitant pharmacotherapies to mitigate TPN-associated adverse effects.

Epidermal growth factor promotes intestinal secretory cell differentiation in weaning piglets via Wnt/β-catenin signalling

Small intestinal epithelium homeostasis involves four principal cell types: enterocytes, goblet, enteroendocrine and Paneth cells. Epidermal growth factor (EGF) has been shown to affect enterocyte differentiation. This study determined the effect of dietary EGF on goblet, enteroendocrine and Paneth cell differentiation in piglet small intestine and potential mechanisms. Forty-two weaned piglets were used in a 2 × 3 factorial design; the major factors were time post-weaning (days 7 and 14) and dietary treatment (0, 200 or 400 µg/kg EGF supplementation). The numbers of goblet and enteroendocrine cells were generally greater with the increase in time post-weaning. Moreover, the supplementation of 200 µg/kg EGF increased (P < 0.01) the number of goblet and enteroendocrine cells in villus and crypt of the piglet small intestine as compared with the control. Dietary supplementation with 200 µg/kg EGF enhanced (P < 0.05) abundances of differentiation-related genes atonal homologue 1, mucin 2 and intestinal trefoil factor 3 messenger RNA (mRNA) as compared with the control. Piglets fed 200 or 400 µg/kg EGF diet had increased (P < 0.05) abundances of growth factor-independent 1, SAM pointed domain containing ETS transcription factor and pancreatic and duodenal homeobox 1 mRNA, but decreased the abundance (P < 0.01) of E74 like ETS transcription factor 3 mRNA as compared with the control. Animals receiving 400 µg/kg EGF diets had enhanced (P < 0.05) abundances of neurogenin3 and SRY-box containing gene 9 mRNA as compared with the control. The mRNA abundance and protein expression of lysozyme, a marker of Paneth cell, were also increased (P < 0.05) in those animals. As compared with the control, dietary supplementation with 200 µg/kg EGF increased the abundance of EGF receptor mRNA and the ratio of non-phospho(p)-β-catenin/β-catenin (P < 0.05) in villus epithelial cells at days 7 and 14. This ratio in crypt epithelial cells was higher (P < 0.05) on the both 200 and 400 µg/kg EGF groups during the same period. Our results demonstrated that dietary EGF stimulated goblet, enteroendocrine and Paneth cell differentiation in piglets during the post-weaning period, partly through EGFR and Wnt/β-catenin signalling.

Effects of dietary supplementation with epidermal growth factor on nutrient digestibility, intestinal development and expression of nutrient transporters in early-weaned piglets

The abnormalities in intestinal morphology and digestive function during weaning are associated with the loss of milk-borne growth factors. Epidermal growth factor (EGF) has been shown to stimulate the growth of animals. This study was to determine the effect of dietary EGF on nutrient digestibility, intestinal development and the expression of genes encoding nutrient transporters in weaned piglets. Forty-two piglets were weaned at 21 days and assigned to one of three treatment groups: (1) basal diet (control), (2) basal diet + 200 µg/kg EGF or (3) basal diet + 400 µg/kg EGF. Each treatment consisted of 14 replicates, and seven piglets from each treatment were sampled on day 7 and 14. The EGF supplementation significantly elevated (p < 0.05) the coefficients of total tract apparent digestibility of crude protein, calcium and phosphorus, but tended to decrease sucrase activity (p < 0.10) than the control group. At day 7 post-weaning, animals receiving EGF diets showed a tendency (p < 0.10) towards greater ileal villus height (VH), jejunal crypt depth (CD) and duodenal VH:CD when compared with the control group. Moreover, the mRNA levels of glucose transporter 2 (Slc2a2), neutral amino acid transporter (Slc6a19) and calbindin D9k (S100G) tended to be higher (p < 0.10) for EGF groups than the control group. By day 14, EGF supplementation markedly enhanced (p < 0.05) the VH, CD and VH:CD in the jejunum compared to the control group. This addition also up-regulated (p < 0.05) the mRNA level and the protein abundance of peptide transporter 1 than the control group. These findings demonstrated that dietary EGF beneficially enhanced nutrient digestibility, improved intestinal development and increased the mRNA expression of nutrient transporters in weaned piglets.

Growth performance and gastrointestinal responses of broiler chickens fed corn-soybean meal diet without or with exogenous epidermal growth factor upon challenge with Eimeria

Epidermal growth factor (EGF), a protein known for its mitogenic and anti-apoptotic effects was fed to broiler chickens to evaluate growth performance, gastrointestinal measurements, and apparent retention (AR) of components upon challenge with Eimeria. A total of 216, d old male broiler chicks (Ross 708) were placed in cages (6 birds/cage) and allocated to treatments. The treatments were: 1) control (Lactotobacilli lactis fermentation supernatant without EGF), 2) 80 μg of EGF/kg BW/d, and 3) 160 μg of EGF/kg BW/d. A basal antibiotic-free corn-soybean diet containing TiO2 was used. Birds were offered fresh feed with respective treatments on daily basis and had free access to drinking water for 14 d. On d 5, birds (6 replicates per treatment) were challenged with 1 mL of E. acervulina and E. maxima mixture via oral gavage and the other 6 replicates were given sham. Growth performance was measured in pre- (d 0 to 5) and post- (d 6 to 14) challenge periods. Two birds per cage were necropsied on d 10 for intestinal lesion scores and tissue samples for histomorphology and expression of select intestinal genes. Excreta samples for AR of components and oocyst shedding were taken d 10 to 13 and all birds were necropsied on d 14 for gastrointestinal weight. The EGF linearly (P < 0.05) increased BWG before challenge. There was no EGF and Eimeria interaction (P > 0.05) on growth performance, AR of GE, and intestinal histomorphology; the main effects were such that Eimeria depressed (P < 0.01) BWG, FCR, AR of DM, crude fat, and GE, and villi height to crypt depth ratio. An interaction between EGF and Eimeria (P < 0.05) on indices of gut function was such that EGF improved expression of genes for nutrient transporters and tight junction proteins in Eimeria challenged birds whilst no effect in non-challenged control. In conclusion, Eimeria challenge reduced growth performance and impaired gut function; EGF showed beneficial effects on growth pre-challenge and improved indices of gut function upon Eimeria challenge.

Effects of heme oxygenase-1 recombinant Lactococcus lactis on the intestinal barrier of hemorrhagic shock rats

This study aimed to investigate the effects of heme oxygenase-1 recombinant Lactococcus lactis (LL-HO-1) on the intestinal barrier of rats with hemorrhagic shock. One hundred Sprague-Dawley male rats (280-320 g) were randomly divided into healthy control group (N group) and hemorrhagic shock group (H group). Each group was subdivided into HO1t, HO2t, HO3t, PBS and LL groups in which rats were intragastrically injected with LL-HO-1 once, twice and three times, PBS and L. lactis (LL), respectively. The mortality, intestinal myeloperoxidase (MPO) activity, intestinal contents of TNF-α, IL-10 and HO-1, and intestinal Chiu's score were determined. Results showed that in N group, the HO-1 content increased after LL-HO-1 treatment, and significant difference was observed in HO1t group and HO2t group (P<0.05). In H groups, MPO activity and Chiu's score decreased, but IL-10 content increased in LL-HO-1-treated groups when compared with PBS and LL groups (P<0.05). When compared with N group, the MPO activity reduced dramatically in LL-HO-1-treated groups. Thus, in healthy rats (N group), intragastrical LL-HO-1 treatment may increase the intestinal HO-1 expression, but has no influence on the intestinal barrier. In hemorrhagic shock rats, LL-HO-1 may significantly protect the intestinal barrier, and repeating the intragastrical LL-HO-1 treatments twice has the most obvious protection.

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.

Benzoic acid beneficially affects growth performance of weaned pigs which was associated with changes in gut bacterial populations, morphology indices and growth factor gene expression

This study was conducted to investigate the effects of benzoic acid (BA) on growth performance, intestinal development and intestinal barrier function in weaned pigs. Ninety weaned pigs were randomly assigned to one of three treatments: a basal diet (CON), the basal diet supplemented with 2000 mg/kg benzoic acid (BA1) and 5000 mg/kg benzoic acid (BA2). At the end of days 14 and 42, six pigs per treatment were randomly selected to collect plasma and intestinal samples. Results showed that BA supplementation not only improved final body weight, daily growth and feed conversion ratio from days 15 to 42 and days 1 to 42, but also decreased the activity of plasma diamine oxidase (day 42) and the pH values of jejunal contents (day 14) (p < 0.05). Ileal Bacillus populations (day 14) were increased by BA, while Escherichia coli counts in the ileum and caecum (day 42) were decreased (p < 0.05). Higher Lactobacillus counts occurred in the ileum (day 14, 42) of BA1-fed piglets as compared to CON and BA2-fed piglets (p < 0.05). In addition, BA supplementation increased the ratio of villus height to crypt depth (day 14, 42) and decreased the crypt depth (day 14) (p < 0.05). Growth-stimulating factors (insulin-like growth factor-1, day 42; insulin-like growth factor-1 receptor, day 14, 42) and tight junction protein (occludin, day 14, 42; zonula occludens-1, day 42)-related gene mRNA levels were upregulated in the jejunum of piglets fed BA diets (p < 0.05). In conclusion, this study provides the first evidence that BA has beneficial effects on intestinal development and intestinal barrier function of weaned pigs, which can partly explain why growth performance of pigs was improved by dietary BA supplementation.

Analysis of the duodenal microbiotas of weaned piglet fed with epidermal growth factor-expressed Saccharomyces cerevisiae

Background

The bacterial community of the small intestine is a key factor that has strong influence on the health of gastrointestinal tract (GIT) in mammals during and shortly after weaning. The aim of this study was to analyze the effects of the diets of supplemented with epidermal growth factor (EGF)-expressed Saccharomyces cerevisiae (S. cerevisiae) on the duodenal microbiotas of weaned piglets.

Results

Revealed in this study, at day 7, 14 and 21, respectively, the compositional sequencing analysis of the 16S rRNA in the duodenum had no marked difference in microbial diversity from the phylum to species levels between the INVSc1(EV) and other recombinant strains encompassing INVSc1-EE(+), INVSc1-TE(−), and INVSc1-IE(+). Furthermore, the populations of potentially enterobacteria (e.g., Clostridium and Prevotella) and probiotic (e.g., Lactobacilli and Lactococcus) also remained unchanged among recombinant S. cerevisiae groups (P > 0.05). However, the compositional sequencing analysis of the 16S rRNA in the duodenum revealed significant difference in microbial diversity from phylum to species levels between the control group and recombinant S. cerevisiae groups. In terms of the control group (the lack of S. cerevisiae), these data confirmed that dietary exogenous S. cerevisiae had the feasibility to be used as a supplement for enhancing potentially probiotic (e.g., Lactobacilli and Lactococcus) (P < 0.01), and reducing potentially pathogenic bacteria (e.g., Clostridium and Prevotella) (P < 0.01).

Conclusion

Herein, altered the microbiome effect was really S. cerevisiae, and then different forms of recombinant EGF, including T-EGF, EE-EGF and IE-EGF, did not appear to make a significant difference to the microbiome of weaned piglets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0783-7) contains supplementary material, which is available to authorized users.

Epidermal Growth Factor and Intestinal Barrier Function

Epidermal growth factor (EGF) is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

A Maternal High-Energy Diet Promotes Intestinal Development and Intrauterine Growth of Offspring

It has been suggested that maternal nutrition during gestation is involved in an offspring’s intestinal development. The aim of this study was therefore to evaluate the effects of maternal energy on the growth and small intestine development of offspring. After mating, twenty gilts (Large White (LW) breeding, body weight (BW) at 135.54 ± 0.66 kg) were randomly allocated to two dietary treatments: a control diet (CON) group and a high-energy diet (HED) group, respectively. The nutrient levels of the CON were referred to meet the nutrient recommendations by the National Research Council (NRC, 2012), while the HED was designed by adding an amount of soybean oil that was 4.6% of the total diet weight to the CON. The dietary treatments were introduced from day 1 of gestation to farrowing. At day 90 of gestation, day 1 post-birth, and day 28 post-birth, the weights of fetuses and piglets, intestinal morphology, enzyme activities, and gene and protein expressions of intestinal growth factors were determined. The results indicated that the maternal HED markedly increased the BW, small intestinal weight, and villus height of fetuses and piglets. Moreover, the activities of lactase in fetal intestine, sucrase in piglet intestine were markedly increased by the maternal HED. In addition, the maternal HED tended to increase the protein expression of insulin-like growth factor 1 receptor (IGF-1R) in fetal intestine, associated with significantly increased the gene expression of IGF-1R. In conclusion, increasing energy intake could promote fetal growth and birth weight, with greater intestinal morphology and enzyme activities.

Effects of dietary supplementation with epidermal growth factor-expressing Saccharomyces cerevisiae on duodenal development in weaned piglets

The aim of the present study was to assess the effects of dietary supplementation with epidermal growth factor (EGF)-expressing Saccharomyces cerevisiae on duodenal development in weaned piglets. In total, forty piglets weaned at 21-26 d of age were assigned to one of the five groups that were provided basic diet (control group) or diet supplemented with S. cerevisiae expressing either empty-vector (INVSc1(EV) group), tagged EGF (T-EGF) (INVSc1-TE(-) group), extracellular EGF (EE-EGF) (INVSc1-EE(+) group) or intracellular EGF (IE-EGF) (INVSc1-IE(+) group). All treatments were delivered as 60·00 μg/kg body weight EGF/d. On 0, 7, 14 and 21 d, eight piglets per treatment were sacrificed to analyse the morphology, activities and mRNA expressions of digestive enzymes, as well as Ig levels (IgA, IgM, IgG) in duodenal mucosa. The results showed significant improvement on 7, 14 and 21 d, with respect to average daily gain (P<0·05), mucosa morphology (villus height and crypt depth) (P<0·05), Ig levels (P<0·01), activities and mRNA expressions of digestive enzymes (creatine kinase, alkaline phosphatase, lactate dehydrogenase and sucrase) (P<0·05) and the mRNA expression of EGF-receptor (P<0·01) in NVSc1-TE(-), INVSc1-EE(+) and INVSc1-IE(+) groups compared with control and INVSc1(EV) groups. In addition, a trend was observed in which the INVSc1-IE(+) group showed an improvement in Ig levels (0·05<P<0·10), mRNA expressions of digestive enzymes and EGF-receptor (P<0·05) compared with NVSc1-TE(-) and INVSc1-EE(+) groups. These results indicate that supplementing recombinant EGF-expressing S. cerevisiae to the diet of weaned piglets enhanced duodenal development. Moreover, biological activity (Ig levels, mRNA expressions of digestive enzymes and EGF-receptor) of IE-EGF was better than either EE-EGF or T-EGF.

Oral administration of Lactococcus lactis-expressed recombinant porcine epidermal growth factor stimulates the development and promotes the health of small intestines in early-weaned piglets

AIMS

We previously generated Lactococcus lactis-expressed recombinant porcine epidermal growth factor (LL-pEGF), and demonstrated improved growth performance in early-weaned piglets. This study investigates the effect of LL-pEGF on the development and expression of genes that maintain the structural integrity and function of the small intestine in early-weaned piglets.

METHODS AND RESULTS

The mitogenic effect of porcine epidermal growth factor (pEGF) was tested in vitro with the 5-Bromodeoxyuridine (BrdU) incorporation assay in fibroblast cells. In the in vivo study, 40 weaned piglets were randomly allocated to control, antibiotic control, Lc. lactis-expressing empty vector (LL-EV) and LL-pEGF treatment groups. Cells treated with LL-pEGF had higher BrdU-positive stained cells than those in the control and the LL-EV treatments (P < 0·05). Scanning electron microscope and histological examination demonstrated that the small intestinal villi treated with LL-pEGF were higher (P < 0·05) than in the other treatments. LL-pEGF increased the messenger RNA (mRNA) expression levels of the intestinal structural integrity proteins trefoil factor 3, claudin 1 (CLDN1), occludin and zonula occludens 1 (ZO-1), the digestive enzymes sucrose, aminopeptidase A, and aminopeptidase N, and the nutrient transporters sodium/glucose cotransporter 1 (SGLT1), glucose transporter 2, and peptide transporter 1 (PEPT1) as compared with the control (P < 0·05) in the small intestine. Meanwhile, the mRNA levels of CLDN1 in the jejunum and ZO-1 in the ileum were higher in the LL-EV group than in the control group (P < 0·05). LL-EV and the antibiotic control increased SGLT1 mRNA in the jejunum and PEPT1 mRNA in the ileum compared with the control (P < 0·05).

CONCLUSIONS

Recombinant pEGF promotes cell mitosis. Oral administration of Lc. lactis-expressing pEGF stimulated intestinal development by upregulating the gene expression of the intestinal structural integrity proteins, the digestive enzymes and the nutrient transporters.

SIGNIFICANCE AND IMPACT OF THE STUDY

The combination of epidermal growth factor and genetically modified micro-organisms may be used as dietary supplements to reduce intestinal stress in animals and even humans.

Epidermal growth factor containing culture supernatant enhances intestine development of early-weaned pigs in vivo: potential mechanisms involved

We have previously generated epidermal factor expressing Lactococcus lactis (EGF-LL) using a bioengineering approach, and shown that EGF-LL fermentation supernatant enhanced newly weaned pigs growth. The objective of the current study was to further understand the mechanisms behind this improved performance. Sixty-four piglets were weaned at 3 weeks of age and then fed ad libitum according to a 2-phase feeding program. Four pens with 8 pigs per pen were assigned to each of two treatments for 3 weeks: (1) EGF containing supernatant from EGF-LL culture (SuperEGF) or (2) blank M17GE media (Control). Consistent with previous findings, SuperEGF pigs had an increased average daily gain during week 3 post-weaning (433.4 ± 10.86 vs 388.7 ± 7.76 g; P<0.05) and overall gain:feed ratio (0.757 ± 0.03 vs 0.677 ± 0.01 kg/kg, P < 0.05). Moreover, jejunal structure development was enhanced, and inflammation index was minimized in SuperEGF pigs as indicated by increased villi height (P<0.05), decreased lamina propria width (P<0.05), and higher expression of anti-inflammatory cytokine, IL-13 (P<0.05). Further, goblet cell numbers and Muc2 levels were increased in SuperEGF pigs. Interestingly, the weaning-induced decrease of glucose cotransporter sodium-glucose linked transporter 1 (SGLT1) and glucagon-like peptide-2 (GLP2) levels was reversed by SuperEGF supplementation. Our findings add to our understanding of the mechanisms behind enhancing piglet performance by EGF containing fermentation product.

Recombinant porcine epidermal growth factor-secreting Lactococcus lactis promotes the growth performance of early-weaned piglets

Background

Epidermal growth factor (EGF) is an important growth factor in regulation of cell proliferation, differentiation, survival and apoptosis. Studies showed that food-grade Lactococcus lactis (L. lactis) and NICE expression system have superior performance in exogenous protein expression. This study aimed to construct and express porcine EGF (pEGF), and use L. lactis as vehicle for producing and delivering pEGF. Furthermore, investigating biological activity of pEGF and exploring applications feasibility of combination effects of L. lactis and pEGF on early weaned piglets’ production.

Results

A recombinant Lactococcus lactis which produced and secreted pEGF at 1000 ng/ml in culture supernatant was generated. Secreted pEGF was a fully biologically active protein, as demonstrated by its capacity to stimulate L929 mouse fibroblast cell line proliferation in vitro. For in vivo study, forty piglets were randomly allocated to control, antibiotic control, empty vector-expressing L. lactis (LL-EV) and pEGF-secreting L. lactis (LL-pEGF). After 14 d of rearing, final body weight and average daily gain in LL-pEGF were greater (P < 0.05, 8.95 vs. 8.37 kg, 206.1 vs. 157.7 g/day, respectively) than those in control, but no significant differences between LL-pEGF, LL-EV and antibiotic control. Overall period average daily feed intake was higher in LL-pEGF, LL-EV and antibiotic control than in control (P < 0.05, 252.9, 255.6, 250.0, 207.3 g/day, respectively). No significant difference was observed on ADFI/ADG. LL-pEGF increased villous height in the duodenum, jejunum and ileum than in control and LL-EV (P < 0.05). Sucrase in the 3 intestinal segments, aminopeptidase A in the duodenum and Jejunum, aminopeptidase N and dipeptidase IV in the duodenum in LL-pEGF were higher than those in control (P < 0.05). Furthermore, Escherichia coli and Enterococcus counts decreased in the ileum and Lactobacillus increased in the ileum and cecum digesta in LL-pEGF compare with the control (P < 0.05). Lactobacillus increased in the cecum in LL-EV compared with control and antibiotic control (P < 0.05).

Conclusion

We have generated a recombinant Lactococcus lactis which produced and secreted fully biologically active porcine EGF. Oral administration of pEGF-secreting L. lactis had beneficial effects on intestinal health and performance of early-weaned piglets.

Growth performance of early-weaned pigs is enhanced by feeding epidermal growth factor-expressing Lactococcus lactis fermentation product

We have previously generated epidermal growth factor expressing Lactococcus lactis (EGF-LL) using bioengineering approach, and shown that feeding newly-weaned piglets EGF-LL improves digestive function. To address concerns over the use of genetically modified organisms (GMO), the objective of the current study was to investigate the effect of feeding the EGF-LL fermentation product, after removal of the genetically modified EGF-LL, on growth performance and intestine development of newly-weaned piglets. One hundred and twenty newly-weaned piglets were fed ad libitum according to a 2-phase feeding program. Four pens were assigned to each of three treatments: (1) complete EGF-LL fermentation product (Ferm), (2) supernatant of EGF-LL fermentation product, after removal of EGF-LL (Supern), or (3) blank M17GE media (Control). EGF-LL or its fermented supernatant was administrated to piglets in the first 3 weeks post-weaning; their growth performance was monitored throughout treatment, and for the following week. Daily body weight gain (254.8g vs. 200.5g) and Gain:Feed (0.541kg/kg vs. 0.454kg/kg) of pigs on the Supern group were significantly improved compared to that of Control, although no difference was observed between the Ferm and Control pigs. Intestinal sucrase activity was increased in Supern- compared to Control group (166.3±62.1 vs. 81.4±56.5nmol glucose released/mg protein; P<0.05). The lack of growth response with Ferm pigs may be attributed to an overload of bacteria (daily dose included 4.56×10(10)CFU/kg BW/day EGF-LL). These results suggest that GMO-free EGF-LL fermentation product is effective in increasing growth performance of early-weaned piglets.

Recombinant protein expression in Lactococcus lactis using the P170 expression system

The use of the Gram-positive bacterium Lactococcus lactis in recombinant protein production has several advantages, including the organism's long history of safe use in food production and the fact that it does not produce endotoxins. Furthermore the current non-dairy L. lactis production strains contain few proteases and can secrete stable recombinant protein to the growth medium. The P170 expression system used for recombinant protein production in L. lactis utilizes an inducible promoter, P170, which is up-regulated as lactate accumulates in the growth medium. We have optimised the components of the expression system, including improved promoter strength, signal peptides and isolation of production strains with increased productivity. Recombinant proteins are produced in a growth medium with no animal-derived components as a simple batch fermentation requiring minimal process control. The accumulation of lactate in the growth medium does, however, inhibit growth and limits the yield from batch and fed-batch processes. We therefore combined the P170 expression system with the REED™ technology, which allows control of lactate concentration by electro-dialysis during fermentation. Using this combination, production of the Staphylococcus aureus nuclease reached 2.5 g L(-1).

Micro-RNA378 (miR-378) regulates ovarian estradiol production by targeting aromatase

Estradiol is a steroid hormone that not only plays an important role in ovarian follicular development but also is associated with many reproductive disorders. Owing to the importance of aromatase in the production of estradiol, the regulation of aromatase gene expression at the transcriptional level has been an extensive area of study for over two decades. However, its regulation at the posttranscriptional level has remained unclear. Here, we show that micro-RNA378 (miR-378) is spatiotemporally expressed in porcine granulosa cells, the cells that generate estradiol in the ovary during follicular development, in an inverse manner compared with the expression of aromatase. In vitro overexpression and inhibition experiments revealed that aromatase expression, and therefore estradiol production, by granulosa cells, is posttranscriptionally down-regulated by miR-378. Furthermore, site-directed mutation studies identified two binding sites in the 3'-untranslated region (3'-UTR) of the aromatase coding sequence that are critical for the action of miR-378. Interestingly, overexpression of the aromatase 3'-UTR enhanced aromatase expression at the protein level in granulosa cells, possibly mediated by the binding of miR-378 within this region, thereby reducing the binding of this micro-RNA to the endogenous aromatase 3'-UTR.