Effects of orally administered epidermal growth factor on enteropathogenic Escherichia coli infection in rabbits

Antibiotics and the developing intestinal microbiome, metabolome and inflammatory environment in a randomized trial of preterm infants

Antibiotic use in neonates can have detrimental effects on the developing gut microbiome, increasing the risk of morbidity. A majority of preterm neonates receive antibiotics after birth without clear evidence to guide this practice. Here microbiome, metabolomic, and immune marker results from the routine early antibiotic use in symptomatic preterm Neonates (REASON) study are presented. The REASON study is the first trial to randomize symptomatic preterm neonates to receive or not receive antibiotics in the first 48 h after birth. Using 16S rRNA sequencing of stool samples collected longitudinally for 91 neonates, the effect of such antibiotic use on microbiome diversity is assessed. The results illustrate that type of nutrition shapes the early infant gut microbiome. By integrating data for the gut microbiome, stool metabolites, stool immune markers, and inferred metabolic pathways, an association was discovered between Veillonella and the neurotransmitter gamma-aminobutyric acid (GABA). These results suggest early antibiotic use may impact the gut-brain axis with the potential for consequences in early life development, a finding that needs to be validated in a larger cohort.Trial Registration This project is registered at clinicaltrials.gov under the name "Antibiotic 'Dysbiosis' in Preterm Infants" with trial number NCT02784821.

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.

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.

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.

Enteral approaches in malabsorption

Enteral autonomy and freedom from parenteral nutrition dependency is the ultimate therapeutic goal in children with intestinal failure. This can be achieved following attainment of bowel adaptation in conditions such as short bowel syndrome. Enteral nutrition is a major therapeutic cornerstone in the management of children with intestinal failure. It promotes physiological development, bowel adaptation and enhances weaning from parenteral nutrition. The optimal method of delivery, type of nutrients, timing of initiation, promotion of feeds and transition to solid food in children with short bowel syndrome are debated. Lack of high quality human data hampers evidence based conclusions and impacts daily practices in the field. Clinical approaches and therapeutic decisions are regularly influenced by expert opinion and center practices. This review summarizes the physiological principles, medical evidence and practice recommendations on enteral nutrition approaches in short bowel syndrome and provides a practical framework for daily treatment of this unique group of patients. Oral and tube feeding, bolus and continuous feeding, type of nutrients, formulas, trace elements and solid food options are reviewed. Future collaborative multicenter, high quality clinical trials are needed to support enteral nutrition approaches in intestinal failure.

Angiogenic factors and inflammation in steroid-refractory acute graft-vs-host disease

Steroid-refractory acute graft-vs-host disease (aGVHD) remains a frequent and often fatal complication of allogeneic hematopoietic cell transplantation. Recent evidence suggests that angiogenic factors-growth factors that contribute to blood vessel development-may be involved in tissue healing and restitution after inflammatory insults such as aGVHD. However, some angiogenic factors may also be involved in inflammation and worsen clinical outcomes. In this review, we summarize the data relevant to angiogenic factors that may contribute to healing after aGVHD (epidermal growth factor and vascular endothelial growth factor A) and angiogenic factors that may promote inflammation after aGVHD (placental growth factor and follistatin). It is currently unknown whether changes in these factors are a cause or a consequence of aGVHD. Mechanistic studies in the coming years will clarify their roles and identify new pathways for improving outcomes in steroid-refractory aGVHD.

Restoration of CpG Methylation in The Egf Promoter Region during Rat Liver Regeneration

Epidermal growth factor (EGF) is an important factor for healing after tissue damage in diverse experimental models. It plays an important role in liver regeneration (LR). The objective of this experiment is to investigate the methylation variation of 10 CpG sites in the Egf promoter region and their relevance to Egf expression during rat liver regenera- tion. As a follow up of our previous study, rat liver tissue was collected after rat 2/3 partial hepatectomy (PH) during the re-organization phase (from days 14 to days 28). Liver DNA was extracted and modified by sodium bisulfate. The methylation status of 10 CpG sites in Egf promoter region was determined using bisulfite sequencing polymerase chain reaction (PCR), as BSP method. The results showed that 3 (sites 3, 4 and 9) out of 10 CpG sites have strikingly methylation changes during the re-organization phase compared to the regeneration phase (from 2 hours to 168 hours, P=0.002, 0.048 and 0.018, respectively). Our results showed that methylation modification of CpGs in the Egf promoter region could be restored to the status before PH operation and changes of methylation didn’t affect Egf mRNA expression during the re-organization phase.

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.

Strain-dependent induction of human enterocyte apoptosis by blastocystis disrupts epithelial barrier and ZO-1 organization in a caspase 3- and 9-dependent manner

Blastocystis is an emerging protistan parasite colonizing the human intestine. It is frequently reported to cause general intestinal symptoms of vomiting, diarrhea, and abdominal pain. We recently demonstrated that Blastocystis rearranged cytoskeletal proteins and induced intestinal epithelial barrier compromise. The effect of Blastocystis on enterocyte apoptosis is unknown, and a possible link between microbially induced enterocyte apoptosis and increased epithelial permeability has yet to be determined. The aim of this study is to assess if Blastocystis induces human enterocyte apoptosis and whether this effect influences human intestinal epithelial barrier function. Monolayers of polarized human colonic epithelial cell-line Caco-2 were incubated with Blastocystis subtype 7 and subtype 4. Assays for both early and late markers of apoptosis, phosphatidylserine externalization, and nuclear fragmentation, respectively, showed that Blastocystis ST-7, but not ST-4, significantly increased apoptosis in enterocytes, suggesting that Blastocystis exhibits host specificity and strain-to-strain variation in pathogenicity. ST-7 also activated Caco-2 caspases 3 and 9 but not 8. ST-7 induced changes in epithelial resistance, permeability, and tight junction (ZO-1) localization. Pretreatment of Caco-2 monolayers with a pan-caspase inhibitor z-VAD-fmk significantly inhibited these changes. This suggests a role for enterocyte apoptosis in Blastocystis-mediated epithelial barrier compromise in the human intestine.

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.

The role of epidermal growth factor in prevention of oxidative injury and apoptosis induced by intestinal ischemia/reperfusion in rats

Intestinal ischemia/reperfusion is a major problem which may lead to multiorgan failure and death. The aim of the study was to evaluate the effects of epidermal growth factor (EGF) on apoptosis, cell proliferation, oxidative stress and the antioxidant system in intestinal injury induced by ischemia/reperfusion in rats and to determine if EGF can ameliorate these toxic effects. Intestinal ischemia/reperfusion injury was produced by causing complete occlusion of the superior mesenteric artery for 60 min followed by a 60-min reperfusion period. Animals received intraperitoneal injections of 150 μg/kg human recombinant EGF 30 min prior to the mesenteric ischemia/reperfusion. Mesenteric ischemia/reperfusion caused degeneration of the intestinal mucosa, inhibition of cell proliferation, stimulation of apoptosis and oxidative stress in the small intestine of rats. In the ischemia/reperfusion group, lipid peroxidation was stimulated accompanied by increased intestinal catalase and glutathione peroxidase activities, however, glutathione levels and superoxide dismutase activities were markedly decreased. EGF treatment to rats with ischemia/reperfusion prevented the ischemia/reperfusion-induced oxidative injury by reducing apoptosis and lipid peroxidation, and by increasing antioxidant enzyme activities. These results demonstrate that EGF has beneficial antiapoptotic and antioxidant effects on intestinal injury induced by ischemia/reperfusion in rats.

Proton pump inhibitors are not the key for therapying non-steroidal anti-inflammatory drugs-induced small intestinal injury

The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to injure the small intestine has been well established in humans and animals. Proton pump inhibitors (PPIs) are frequently prescribed to reduce gastric and duodenal injury caused in high-risk patients taking NSAIDs. However, scarce information is available concerning the effects of PPIs on intestinal damage induced by NSAIDs, and the suppression of gastric acid secretion by PPIs is hard to provide any protection against the damage caused by NSAIDs in the small intestine. The present study was designed to examine the effects of intragastric treatment of two PPIs widely used in clinical practice, namely omeprazole and pantoprazole, on the intestinal damage induced by administration of diclofenac in rat. Male SD rats were treated with omeprazole or pantoprazole for 9 days, with concomitant treatment with anti-inflammatory doses of diclofenac on the final 5 days. The anatomical lesion, villous height, the thickness, and the section area of small intestine were quantitatively analyzed. The change of ultrastructural organization was observed. Endotoxin level in blood was measured by photometry. Epidermal growth factor was observed by immunohistochemistry. Omeprazole and pantoprazole didn't decrease the macroscopic and histologic damage induced by diclofenac in the rat's small intestine. In the two PPI groups, villous height was (89.6 ± 11.8 and 92.6 ± 19.3 μm) lower than which of the control group (P < 0.05). The thickness became thinning, and the section area became small. LPS levels in the portal blood of omeprazole and pantoprazole were (4.36 ± 1.26 and 4.25 ± 1.17 EU/ml), significantly higher than in controls (P < 0.05). The EFG of PPI group descended significantly compared with the control group (P < 0.05). Omeprazole and pantoprazole cannot protect the small intestine from the damage induced by diclofenac in the conscious rat. PPIs cannot repair NSAID-induced intestinal damage at least in part because of significant lesion in mechanical barrier function and reduction in epidermal growth factor.

VIP and growth factors in the infected cornea

PURPOSE

Vasoactive intestinal peptide (VIP) is an anti-inflammatory neuropeptide that downregulates proinflammatory cytokines and promotes healing in a susceptible model of P. aeruginosa keratitis. Growth factors also play a role in corneal healing and restoration of tissue homeostasis after wounding. However, whether VIP treatment modulates growth factors to promote healing in the infected cornea remains untested and is the purpose of this study.

METHODS

C57BL/6 (B6) mice were injected with VIP and mRNA and protein levels, and immunostaining for EGF, FGF, HGF, and VEGF-A were done. Exogenous treatment with a mixture of the growth factors also was tested and levels of cytokines, defensins, and bacterial counts were determined.

RESULTS

Real-time RT-PCR, immunostaining, and ELISA data demonstrated that treatment with VIP enhanced levels of EGF, FGF, and HGF during disease, and that VEGF-A, and associated angiogenic molecules also were increased by VIP. Moreover, immunohistochemical studies confirmed that both epithelial and stromal cells participated in growth factor production. Most notably, treatment with a mixture of EGF, FGF, and HGF after disease onset, prevented corneal perforation when compared with controls. This outcome was associated with downregulation of proinflammatory cytokines such as macrophage inflammatory protein-2 (MIP-2), upregulation of anti-inflammatory cytokines such as TGF-β, and antimicrobials β-defensins 2 and 3, as well as decreased plate counts at 1 day postinfection (p.i.) (P = 0.0001).

CONCLUSIONS

Collectively, the data provide evidence that VIP treatment modulates growth factors, angiogenic molecules, and defensins in the infected cornea and that this in turn promotes healing and restoration of tissue homeostasis.

Effect of Lactobacillus acidophilus & epidermal growth factor on experimentally induced Clostridium difficile infection

BACKGROUND & OBJECTIVES

Clostridium difficile-associated disease (CDAD) remains an important nosocomial ailment. Antimicrobial therapy used for CDAD gives inconsistent results. This experimental study was planned to investigate the beneficial effects of Lactobacillus acidophilus and epidermal growth factor (EGF) for CDAD management.

METHODS

Among 10 groups of BALB/c mice (6 in each), group 1 served as controls receiving no inoculum. Animals in groups 2-10 received C. difficile, those in groups 3, 6 and 9 received L. acidophilus and those in groups 4, 7 and 10 received EGF after C. difficile inoculation. Animals in groups 5-7 were pre-treated with ampicillin and those in groups 8-10 with lansoprazole prior to C. difficile. The animals were killed and investigated for colonisation by C. difficile and toxin production, myeloperoxidase (MPO) activity and histopathology.

RESULTS

Colonisation by C. difficile was found to be significantly different (P<0.001) in the various groups. C. difficile toxin titres and MPO activity were significantly lower in animals given L. acidophilus and EGF after ampicillin (groups 6 and 7) and lansoprazole (groups 9 and 10). The severity of acute inflammation was also significantly less (P<0.05) in caecal and colonic segments of animals in groups 6 and 7 compared to those in group 5. Although the severity of acute inflammation was less in the caecal and colonic segment of animals in groups 9 and 10, the reduction was not significant compared to group 8.

INTERPRETATION & CONCLUSIONS

Our findings showed that the administration of L. acidophilus and EGF reduced the severity of C. difficile infection in the experimental animals.

Effect of biotherapeutics on cyclosporin-induced Clostridium difficile infection in mice

BACKGROUND AND AIM

Immunosuppressive therapy may precipitate Clostridium difficile associated disease (CDAD). We evaluated the role of cyclosporin in the development of CDAD in the experimental mouse model and studied the effect of probiotic and epidermal growth factor (EGF) as biotherapeutics measures.

METHODS

BALB/c mice (n = 24) were divided into four groups. Group I animals not given any inoculum served as controls. Animals in the remaining three groups (Group II, III and IV) were given cyclosporin daily from days 1-7 followed by C. difficile inoculum on day 8. Additionally, the animals received Lactobacillus acidophilus (Group III) and EGF (Group IV) for one-week post C. difficile challenge. The animals were evaluated for colonization and toxin production by C. difficile, myeloperoxidase (MPO) activity and histopathological changes.

RESULTS

Clostridium difficile was colonized and elaborated its toxins in animals receiving cyclosporin and C. difficile. MPO activity was significantly higher (P < 0.05) and histopathological epithelial damage, cryptitis and acute inflammatory changes were seen in the cecum and colon. C. difficile count, toxins A and B titers and MPO activity were significantly lowered (P < 0.05) in animals receiving probiotic and EGF. Histopathologically, mucodepletion and inflammatory infiltrate were decreased in the biotherapeutic receiving animals.

CONCLUSIONS

Cyclosporin led to the development of mild to moderate CDAD in animals. Administration of biotherapeutics reduced the severity of CDAD. Future clinical trials are needed for further investigation of these potential biotherapeutic measures.

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

Stress and incomplete gastrointestinal development in early-weaned piglets represent significant challenges in commercial swine farming. Orally ingested recombinant epidermal growth factor (EGF) has been shown to remain biologically active in the gastrointestinal tract as well as stimulate intestinal development, reducing the incidence of pathogen infection and diarrhea. We have previously shown that the food-grade bacterium Lactococcus lactis can be genetically altered to express biologically active EGF when fed to early-weaned mice. In this study, we assigned 8 pigs to each of 4 groups that were given EGF-expressing L. lactis (EGF-LL), empty vector-expressing L. lactis (EV-LL), recombinant human EGF, or unsupplemented bacterial media, all of which were delivered as 50-mL i.g. doses twice per day. All pigs were killed after 14 d to examine intestinal morphology. Pigs in the EGF-LL group had greater jejunal and duodenal villus heights (P < 0.0001) and intestinal length (P = 0.049) than pigs in the control group. Immunohistochemistry with antibodies against proliferating cell nuclear antigen (PCNA) revealed that the proliferation of intestinal cells was significantly greater in the EGF-LL group than in the control group. PCNA expression and intestinal length also were greater in the EV-LL group, which received L. lactis that did not express EGF, than in the control group (P = 0.049), further supporting the use of naturally occurring intestinal microbes as desirable vectors for recombinant protein delivery. Our data demonstrates the feasibility of delivering a growth factor using common probiotic bacteria to farm animals for commercial practice.

The role of epithelial malfunction in the pathogenesis of enteropathogenic E. coli-induced diarrhea

The homeostatic balance of the gastrointestinal tract relies on a single layer of epithelial cells, which assumes both digestive and protective functions. Enteric pathogens, including enteropathogenic Escherichia coli (EPEC), have evolved numerous mechanisms to disrupt basic intestinal epithelial functions, promoting the development of gastrointestinal disorders. Despite its non-invasive nature, EPEC inflicts severe damage to the intestinal mucosa, including the dysregulation of water and solute transport and the disruption of epithelial barrier structure and function. Despite the high prevalence and morbidity of disease caused by EPEC infections, the etiology of its pathogenesis remains incompletely understood. This review integrates the newest findings on EPEC-epithelial interactions with established mechanisms of disease in an attempt to give a comprehensive understanding of the cellular processes whereby this common pathogen may cause diarrheal illness.

Generation of epidermal growth factor-expressing Lactococcus lactis and its enhancement on intestinal development and growth of early-weaned mice

BACKGROUND

Epidermal growth factor (EGF) plays an important role in intestinal proliferation and differentiation. Previous studies by others have shown that administration of EGF into the ileum lumen enhances intestinal development.

OBJECTIVE

The objective was to examine the feasibility of expressing and delivering EGF via Lactococcus lactis to early-weaned mice to enhance intestinal development at this critical transition stage.

DESIGN

EGF-expressing L. lactis (EGF-LL) was generated with a recombinant approach. Early-weaned mice were orally gavaged with the recombinant bacteria. Body weight, mean villous height, and crypt depth in the intestine were measured to examine the influence of EGF-LL on the intestinal development of early-weaned mice in vivo.

RESULTS

Populations of EGF-LL were shown to survive throughout the intestinal tract, and the recombinant EGF protein was also detected in intestinal contents. Weight gain was significantly greater in mice that received EGF-LL than in control mice fed phosphate-buffered saline or L. lactis transformed with the empty vector backbone but was comparable with that of the positive control mice that received recombinant human EGF. EGF-LL increased mean villous height and crypt depth in the intestine. Immunohistochemistry also confirmed that enterocyte proliferation was enhanced in mice that received EGF-LL, as evidenced by the greater number of cells stained with proliferative cell nuclear antigen in the intestine.

CONCLUSIONS

This study showed that EGF-LL had beneficial effects on the intestinal growth of newly weaned mice. The combination of growth factor delivery and a probiotic approach may offer possibilities for formulating dietary supplements for children during their weaning transition stage.

ERBBs in the gastrointestinal tract: recent progress and new perspectives

The gastrointestinal epithelium does much more than provide a physical barrier between the intestinal lumen and our internal milieu. It is actively engaged in absorption and secretion of salt and water via ion transporters, exchangers and selective ion channels. It is also a continuously self-renewing epithelium that undergoes ordered growth and differentiation along its vertical axis. From this dual perspective, we will consider the actions of the ERBB family of ligands and receptors in the maintenance of gastrointestinal homeostasis and discuss instances when the actions of this family go awry such as in cancer and Ménétrier's disease.

Epidermal growth factor inhibits Campylobacter jejuni-induced claudin-4 disruption, loss of epithelial barrier function, and Escherichia coli translocation

Campylobacter jejuni is a leading cause of acute bacterial enteritis in humans. Poultry serves as a major reservoir of C. jejuni and is thought to act as a principal vehicle of transmission to humans. Epidermal growth factor (EGF) is a small amino acid peptide that exerts a broad range of activities on the intestinal epithelium. The aims of this study were to determine the effect of EGF on C. jejuni intestinal colonization in newly hatched chicks and to characterize its effects on C. jejuni-induced intestinal epithelial barrier disruption. White Leghorn chicks were treated with EGF daily, starting 1 day prior to C. jejuni infection, and were compared to control and C. jejuni-infected, EGF-treated chicks. Infected chicks shed C. jejuni in their feces throughout the study period. C. jejuni colonized the small intestine and cecum, disseminated to extraintestinal organs, and caused jejunal villus atrophy. EGF reduced jejunal colonization and dissemination of C. jejuni to the liver and spleen. In EGF-treated C. jejuni-infected chicks, villus height was not significantly different from that in untreated C. jejuni-infected chicks or controls. In vitro, C. jejuni attached to and invaded intestinal epithelial cells, disrupted tight junctional claudin-4, and increased transepithelial permeability. C. jejuni also promoted the translocation of noninvasive Escherichia coli C25. These C. jejuni-induced epithelial abnormalities were abolished by pretreatment with EGF, and the effect was dependent upon activation of the EGF receptor. These findings highlight EGF's ability to alter colonization of C. jejuni in the intestinal tract and to protect against pathogen-induced barrier defects.

Maternal milk contains antimicrobial factors that protect young rabbits from enteropathogenic Escherichia coli infection

Enteropathogenic Escherichia coli (EPEC) colibacillosis represents a major cause of lethal diarrhea in young children in developing countries. EPEC strains also infect numerous mammal species and represent a major economical problem in rabbit industry. Protection against this pathogen is a challenging goal both in humans and in other mammal species. Despite a good knowledge of the pathogenicity mechanisms of EPEC, the intrinsic and environmental factors that control the expression of EPEC virulence in mammals remain unknown. For instance, the exacerbated sensitivity of young mammals to EPEC infection is still unexplained. Our goal was to investigate if age or other factors, like milk consumption, could be determinants that trigger the disease. We used rabbits as an animal model to study the role of milk in the sensitivity to an EPEC infection. Weaned and suckling rabbits were orally inoculated with EPEC strain E22 (O103:H2:K-) at 28 days of age, and the evolution of the disease was investigated in the two groups. In addition, in order to better characterize the interactions between milk and EPEC, we determined in vitro bacterial growth and the abilities of EPEC cells to adhere to epithelial cells in the presence of milk. Our results demonstrate a protective role of milk in vivo in association with in vitro antibacterial activity. These effects are independent of the presence of specific anti-EPEC antibodies.

Enteropathogenic Escherichia coli-induced epidermal growth factor receptor activation contributes to physiological alterations in intestinal epithelial cells

The diarrheagenic pathogen enteropathogenic Escherichia coli (EPEC) is responsible for significant infant mortality and morbidity, particularly in developing countries. EPEC pathogenesis relies on a type III secretion system-mediated transfer of virulence effectors into host cells. EPEC modulates host cell survival and inflammation, although the proximal signaling pathways have not been well defined. We therefore examined the effect of EPEC on the epidermal growth factor receptor (EGFR), a known upstream activator of both the prosurvival phosphoinositide 3-kinase/Akt and proinflammatory mitogen-activated protein (MAP) kinase pathways. EPEC induced the autophosphorylation of EGFR in intestinal epithelial cells within 15 min postinfection, with maximal phosphorylation being observed at 4 h. Filter-sterilized supernatants of EPEC cultures also stimulated EGFR phosphorylation, suggesting that a secreted component(s) contributes to this activity. EPEC-induced EGFR phosphorylation was blocked by the pharmacological inhibitor tyrphostin AG1478, as well as by EGFR-neutralizing antibodies. Inhibition of EGFR phosphorylation by AG1478 had no effect on bacterial adherence, actin recruitment to sites of attachment, or EPEC-induced epithelial barrier function alteration. EPEC-mediated Akt phosphorylation, however, was inhibited by both AG1478 and EGFR-neutralizing antibodies. Correspondingly, inhibition of EGFR activation increased the apoptosis/necrosis of infected epithelial cells. Inhibition of EGFR phosphorylation also curtailed EPEC-induced ERK1/2 (MAP kinase) phosphorylation and, correspondingly, the production of the proinflammatory cytokine interleukin-8 by infected epithelial cells. Our studies suggest that EGFR is a key proximal signaling molecule during EPEC pathogenesis.

Mechanisms of epithelial dysfunction in giardiasis

A better understanding of the pathophysiological processes of Giardia may lead to understanding the diseases it causes and to identifying new therapeutic agents

Bacterial gut infections

Infections of the bowel as a result of bacterial enteropathogens are one of the most common medical problems. The use of novel molecular biology techniques and the recent development of new antimicrobial drugs and vaccines are helping us to identify, understand, treat and prevent these infections.

Ability of Orally Administered IFN-α-Containing Transgenic Potato Extracts to InhibitListeria monocytogenesInfection

Type I interferons (IFN-alpha/beta) were originally thought to be antiviral cytokines, but it has recently been reported that they also play an important role in potentiating innate and adaptive immune responses. Moreover, several studies have shown that the oral administration of type I IFN ameliorates various biologic activities. Here, we studied the ability of orally administered IFN-alpha to protect mice from systemic Listeria monocytogenes infection. Daily oral administration of purified natural IFN-alpha at a concentration of 1000 international units (IU)/20 microl reduced the bacterial burden in infected organs. We also examined the protective effect of IFN-alpha expressed in transgenic potato plants. A much lower concentration of IFN-alpha (20 IU/ 20 microl) in the plant extracts was almost as protective as much higher concentrations of purified natural IFN-alpha. Our observations indicate that transgenic cytokine-expressing plants can be used prophylactically as edible pharmaceuticals to enhance systemic defense responses in humans and animals.

Immunopathology of giardiasis: the role of lymphocytes in intestinal epithelial injury and malfunction

T lymphocyte-mediated pathogenesis is common to a variety of enteropathies, including giardiasis, cryptosporidiosis, bacterial enteritis, celiac's disease, food anaphylaxis, and Crohn's disease. In giardiasis as well as in these other disorders, a diffuse loss of microvillous brush border, combined or not with villus atrophy, is responsible for disaccharidase insufficiencies and malabsorption of electrolytes, nutrients, and water, which ultimately cause diarrheal symptoms. Other mucosal changes may include crypt hyperplasia and increased infiltration of intra-epithelial lymphocytes. Recent studies using models of giardiasis have shed new light on the immune regulation of these abnormalities. Indeed, experiments using an athymic mouse model of infection have found that these epithelial injuries were T cell-dependent. Findings from further research indicate that that the loss of brush border surface area, reduced disaccharidase activities, and increase crypt-villus ratios are mediated by CD8+ T cells, whereas both CD8+ and CD4+ small mesenteric lymph node T cells regulate the influx of intra-epithelial lymphocytes. Future investigations need to characterize the CD8+ T cell signaling cascades that ultimately lead to epithelial injury and malfunction in giardiasis and other malabsorptive disorders of the intestine.

A pilot study of the use of epidermal growth factor in pediatric short bowel syndrome

BACKGROUND

This study examined the effects of enterally administered epidermal growth factor (EGF) on nutrient absorption and tolerance of enteral feeds in pediatric patients with short bowel syndrome (SBS).

METHODS

Patients identified with severe SBS (<25% bowel length predicted for age) were prospectively enrolled in treatment using human recombinant EGF (1-53); 100 microg/kg per day given mixed with enteral feeds and patients were treated for 6 weeks. End points followed were patient weight, tolerance of enteral feeds, nutrient absorption, and intestinal permeability as determined using carbohydrate probes and hematologic values for liver function parameters.

RESULTS

Five patients were treated with EGF; all showed a significant improvement in carbohydrate absorption (3-0 methylglucose): absorption 24.7% +/- 9.7% pretreatment vs 34.1% +/- 13.8% posttreatment and improved tolerance of enteral feeds (enteral energy as % of total energy, 25% +/- 28% pretreatment vs 36% +/- 24% posttreatment; mean +/- SD; P < .05 by Wilcoxon's signed rank test). Epidermal growth factor treatment was not associated with significant changes in intestinal permeability, the rate of weight gain, or liver function tests. During the treatment phase, no patients developed episodes of sepsis; however, within 2 weeks of discontinuation of EGF treatment, 3 patients developed septic episodes. No adverse effects of EGF administration were noted.

CONCLUSIONS

These results suggest that enteral treatment with EGF in pediatric SBS improves nutrient absorption, increases tolerance with enteral feeds, and may improve the infection rate. Further studies exploring treatment strategies including the timing and duration of EGF administration are indicated.

Cloning and characterization of a bovine genomic fragment homologous to epidermal growth factor genes

Epidermal growth factor (EGF) is a potent mitogen for a variety of cell types. The 53-amino acid mature EGF protein is encoded by sequences in exons 20 and 21 of a gene spanning over 110 kb. In this study, we report the cloning and characterization of 7.5 kb of bovine genomic sequence homologous to exon 19 through 21 from EGF genes from other mammalian species. The cloned gene fragment had an unusual sequence composition in the form of an in-frame TGA codon in the coding sequence. The sequence was expressed at low levels in kidney tissue and the corresponding cDNA contained the TGA codon. The level of similarity between the bovine exonic sequence and the human, porcine, murine, feline, and canine corresponding sequences varied from 64% to 73%; however, when only sequences encoding the mature EGF protein were compared, the level of similarity between the bovine sequence and the sequence from these species was 59% to 66%. The sequence similarity of the deduced mature protein was lower (34% to 39%) than the sequence similarity of the deduced propeptide. Although the cloned sequences could originate from a bovine EGF pseudogene, the possibility exists that they originate from the functional EGF gene. An as yet unidentified mechanism to by-pass the stop codon would allow the synthesis of a functional EGF protein. Alternatively, the cloned sequence could originate from an EGF-like gene.

Role of CD8+ and CD4+ T lymphocytes in jejunal mucosal injury during murine giardiasis

T-cell-mediated pathogenesis has been documented in various idiopathic and microbially induced intestinal disorders. Diffuse microvillous shortening seen in giardiasis is responsible for disaccharidase insufficiencies and malabsorption of electrolytes, nutrients, and water. Other mucosal changes include crypt hyperplasia and increased numbers of intraepithelial lymphocytes (IEL). A recent report using an athymic mouse model of infection showed that these epithelial injuries were dependent on T cells. The aim of the present study was to identify which subset of superior mesenteric lymph node (SMLN) T cells were responsible for mucosal alterations in giardiasis. CD4+ and CD8+ T cells, as well as whole lymphocyte populations, were isolated from SMLN of Giardia muris-infected mice for adoptive transfer. Jejunal segments of recipient mice were assessed for brush border ultrastructure, sucrase activity, crypt/villus ratio, and IEL numbers. Mice that received enriched CD8+ and whole SMLN lymphocytes, but not CD4+ T cells, from infected donors showed diffuse shortening of microvilli, loss of brush border surface area, impaired sucrase activity, and increased crypt/villus ratios compared to respective controls. Transfer of whole SMLN lymphocytes, as well as enriched CD4+ or CD8+ T cells, from infected donors led to increased IEL numbers in the recipient jejunum. The findings indicate that loss of intestinal brush border surface area, reduced disaccharidase activities, and increased crypt/villus ratios in giardiasis are mediated by CD8+ T cells, whereas both CD8+ and CD4+ SMLN T cells regulate the influx of IEL.

Infection of human and bovine epithelial cells with Cryptosporidium andersoni induces apoptosis and disrupts tight junctional ZO-1: effects of epidermal growth factor

The effects of Cryptosporidium andersoni on human or bovine epithelia are poorly defined. Epidermal growth factor inhibits colonisation of the gastrointestinal epithelium with bacteria and the enteric protozoan parasite Giardia lamblia. This study characterised whether C. andersoni infects human or bovine epithelial cells in vitro, assessed its impact on apoptosis and tight junctional Zonula-Occludens-1, and determined whether these effects may be altered by epidermal growth factor. Monolayers of human colonic CaCo(2) cells, SCBN (non-malignant small intestinal epithelial cells), and Madin Darby bovine kidney epithelial cell lines (MDBK and NBL-1) were grown to confluency in Dulbecco's Modified Eagle Medium. Monolayers were assigned to one of three experimental groups-(1) control: exposed to culture medium alone; (2) untreated: exposed to 10(3) live C. andersoni oocysts or (3) epidermal growth factor-treated: apically pre-treated with recombinant human epidermal growth factor and then exposed to Cryptosporidium. Oocyst viability, infection with Cryptosporidium, apoptosis, and integrity of tight junctional Zonula-Occludens-1 were assessed. In addition, live Cryptosporidium oocysts were incubated with epidermal growth factor to assess whether epidermal growth factor had cryptosporicidial activity. Cryptosporidium andersoni oocysts infected all human and bovine monolayers, increased nuclear fragmentation, and disrupted Zonula-Occludens-1. Apical epidermal growth factor significantly reduced infection with C. andersoni in all cell lines and inhibited the Cryptosporidium-induced apoptosis and disruption of Zonula-Occludens-1. Epidermal growth factor did not affect oocyst viability.

Live probiotics protect intestinal epithelial cells from the effects of infection with enteroinvasive Escherichia coli (EIEC)

BACKGROUND

The colonic epithelium maintains a life long reciprocally beneficial interaction with the colonic microbiota. Disruption is associated with mucosal injury.

AIMS

We hypothesised that probiotics may limit epithelial damage induced by enteroinvasive pathogens, and promote restitution.

METHODS

Human intestinal epithelial cell lines (HT29/cl.19A and Caco-2) were exposed to enteroinvasive Escherichia coli (EIEC 029:NM), and/or probiotics (Streptococcus thermophilus (ST), ATCC19258, and Lactobacillus acidophilus (LA), ATCC4356). Infected cells and controls were assessed for transepithelial resistance, chloride secretory responses, alterations in cytoskeletal and tight junctional proteins, and responses to epidermal growth factor (EGF) stimulation.

RESULTS

Exposure of cell monolayers to live ST/LA, but not to heat inactivated ST/LA, significantly limited adhesion, invasion, and physiological dysfunction induced by EIEC. Antibiotic killed ST/LA reduced adhesion somewhat but were less effective in limiting the consequences of EIEC invasion of cell monolayers. Furthermore, live ST/LA alone increased transepithelial resistance, contrasting markedly with the fall in resistance evoked by EIEC infection, which could also be blocked by live ST/LA. The effect of ST/LA on resistance was accompanied by maintenance (actin, ZO-1) or enhancement (actinin, occludin) of cytoskeletal and tight junctional protein phosphorylation. ST/LA had no effect on chloride secretion by themselves but reversed the increase in basal secretion evoked by EIEC. EIEC also reduced the ability of EGF to activate its receptor, which was reversed by ST/LA.

CONCLUSIONS

Live ST/LA interact with intestinal epithelial cells to protect them from the deleterious effect of EIEC via mechanisms that include, but are not limited to, interference with pathogen adhesion and invasion. Probiotics likely also enhance the barrier function of naïve epithelial cells not exposed to any pathogen.

Giardia duodenalis trophozoites isolated from a parrot (Cacatua galerita) colonize the small intestinal tracts of domestic kittens and lambs

This study examines the ability of Giardia duodenalis trophozoites, isolated from a wild bird, to colonize the intestinal tracts of companion animals (kittens) and domestic ruminants (lambs). Trophozoites colonized the intestinal tracts of intraduodenally inoculated animals as demonstrated by increasing parasite burdens within the duodenum and jejunum and by fecal passage of cysts within 4 days post-inoculation. The pathogenesis of the trophozoites was further investigated in kittens. In these animals, infection significantly reduced jejunal brush border microvillous length and density, which resulted in a loss of overall epithelial brush border surface area. This injury was associated with the production of diarrhea in four of five infected kittens. These findings indicate that some bird species may carry G. duodenalis that represent a possible health threat to companion animals and livestock. Our results describe the first successful colonization of avian-derived G. duodenalis trophozoites in the small intestines of domestic kittens and lambs.

Intestinal infection with Giardia spp. reduces epithelial barrier function in a myosin light chain kinase-dependent fashion

BACKGROUND & AIMS

Giardiasis causes malabsorptive diarrhea, and symptoms can be present in the absence of any significant morphologic injury to the intestinal mucosa. The effects of giardiasis on epithelial permeability in vivo remain unknown, and the role of T cells and myosin light chain kinase (MLCK) in altered intestinal barrier function is unclear. This study was conducted to determine whether Giardia spp. alters intestinal permeability in vivo, to assess whether these abnormalities are dependent on T cells, and to assess the role of MLCK in altered epithelial barrier function.

METHODS

Immunocompetent and isogenic athymic mice were inoculated with axenic Giardia muris trophozoites or sterile vehicle (control), then assessed for trophozoite colonization and gastrointestinal permeability. Mechanistic studies using nontransformed human duodenal epithelial monolayers (SCBN) determined the effects of Giardia on myosin light chain (MLC) phosphorylation, transepithelial fluorescein isothiocyanate-dextran fluxes, cytoskeletal F-actin, tight junctional zonula occludens-1 (ZO-1), and MLCK.

RESULTS

Giardia infection caused a significant increase in small intestinal, but not gastric or colonic, permeability that correlated with trophozoite colonization in both immunocompetent and athymic mice. In vitro, Giardia increased permeability and phosphorylation of MLC and reorganized F-actin and ZO-1. These alterations were abolished with an MLCK inhibitor.

CONCLUSIONS

Disruption of small intestinal barrier function is T cell independent, disappears on parasite clearance, and correlates with reorganization of cytoskeletal F-actin and tight junctional ZO-1 in an MLCK-dependent fashion.

Epidermal growth factor improves nutritional outcome in a rat model of short bowel syndrome

BACKGROUND/PURPOSE

This study investigates the effect of epidermal growth factor (EGF) on nutrient absorption in a rat model of short bowel syndrome (SBS).

METHODS

Male juvenile rats underwent either transection (Sham) or ileocecal resection leaving a 20-cm jejunal remnant. Animals underwent follow-up for 10 days, and resected animals were treated with placebo or recombinant human EGF (1-53). Animals were pair fed; in vivo nutrient absorption, intestinal permeability, morphology, and total intestinal DNA and protein content were measured.

RESULTS

Resected EGF-treated animals lost significantly less weight than those in the placebo group (-4.2 +/- 3 v -13.7 +/- 6.9%), absorbed significantly more 3-0 methylglucose (76.8 +/- 6.6 v 64.9 +/- 10.1%), and had reduced permeability (lactulose/mannitol ratio, 0.35 +/- 0.19 v 0.60 +/- 0.20; P <.05 for all comparisons).

CONCLUSIONS

These findings show that treatment of short bowel syndrome animals with EGF reduced weight loss and improved carbohydrate absorption and intestinal permeability. These findings suggest that enteral EGF may be a useful therapy for short bowel syndrome; further studies are indicated.

Jejunal brush border microvillous alterations in Giardia muris-infected mice: role of T lymphocytes and interleukin-6

Intestinal colonization with the protozoan Giardia causes diffuse brush border microvillous alterations and disaccharidase deficiencies, which in turn are responsible for intestinal malabsorption and maldigestion. The role of T cells and/or cytokines in the pathogenesis of Giardia-induced microvillous injury remains unclear. The aim of this study was to assess the role of T cells and interleukin-6 (IL-6) in the brush border pathophysiology of acute murine giardiasis in vivo. Athymic nude (nu(-)/nu(-)) CD-1 mice and isogenic immunocompetent (nu(+)/nu(+)) CD-1 mice (4 weeks old) received an axenic Giardia muris trophozoite inoculum or vehicle (control) via orogastric gavage. Weight gain and food intake were assessed daily. On day 6, segments of jejunum were assessed for parasite load, brush border ultrastructure, IL-6 content, maltase and sucrase activities, villus-crypt architecture, and intraepithelial lymphocyte (IEL) infiltration. Despite similar parasitic loads on day 6, infected immunocompetent animals, but not infected nude mice, showed a diffuse loss of brush border microvillous surface area, which was correlated with a significant reduction in maltase and sucrase activities and a decrease in jejunal IL-6 concentration. In both athymic control and infected mice, jejunal brush border surface area and disaccharidases were high, but levels of tissue IL-6 were low and comparable to the concentration measured in immunocompetent infected animals. In both immunocompetent and nude mice, infection caused a small but significant increase in the numbers of IELs. These findings suggest that the enterocyte brush border injury and malfunction seen in giardiasis is, at least in part, mediated by thymus-derived T lymphocytes and that suppressed jejunal IL-6 does not necessarily accompany microvillous shortening.

Bacterial colonization and healing of gastric ulcers: the effects of epidermal growth factor

Experimental gastric ulcers are rapidly colonized by various bacteria, resulting in significantly impaired healing. Epidermal growth factor (EGF) is capable of preventing bacterial colonization of the healthy intestinal mucosa. In this study, we examined the possibility that EGF accelerates gastric ulcer healing by reducing bacterial colonization of the ulcer. Gastric ulcers were induced by serosal application of acetic acid. The effect of daily administration of EGF on ulcer healing and bacterial colonization was assessed and compared with the effect of daily treatment with broad-spectrum antibiotics. EGF administration reduced colonization levels and accelerated ulcer healing as effectively as the antibiotic treatment. EGF was without effect on acid secretion or neutrophil infiltration into the ulcer. Bacterial growth was not inhibited in the presence of EGF in vitro. These results demonstrate that EGF reduces bacterial colonization during an established infection of a compromised mucosal surface. This effect may contribute to the ability of EGF to accelerate gastric ulcer healing. This effect is acid independent and not due to an anti-inflammatory effect or to direct bactericidal actions.

The role of the epidermal growth factor receptor in microbial infections of the gastrointestinal tract

The epidermal growth factor receptor (EGFr) is a transmembrane glycoprotein with an intrinsic tyrosine kinase. Ligand-binding to the EGFr activates cell signaling, phosphorylates protein kinases, and rearranges cytoskeletal proteins - responses that resemble those induced by microbial attachment to cell surfaces, a process known to be mediated by host cell receptors in a number of cases. This article critically reviews the possible role played by the EGFr in microbial colonization, and discusses how modulation of the EGF-EGFr axis may affect infection of the gastrointestinal tract.