Epidermal growth factor is digested to smaller, less active forms in acidic gastric juice

Nutritional and health effects of bovine colostrum in neonates

High concentrations of immunoglobulins, bioactive peptides, and growth factors are found in bovine colostrum (BC), the milk produced by cows in the first few days after parturition. Various biological functions make it increasingly used to provide nutritional support and immune protection to the offspring of many species, including humans. These biological functions include cell growth stimulation, anti-infection, and immunomodulation. The primary components and biological functions of colostrum were reviewed in the literature, and the authors also looked at its latent effects on the growth and development of neonates as well as on conditions such as infections, necrotizing enterocolitis, short bowel syndrome, and feeding intolerance. The importance of BC in neonatal nutrition, immune support, growth and development, and gut health has been demonstrated in a number of experimental and animal studies. BC has also been shown to be safe at low doses without adverse effects in newborns. BC supplementation has been shown to be efficient in preventing several disorders, including rotavirus diarrhea, necrotizing enterocolitis, and sepsis in animal models of prematurity and some newborn studies. Therefore, BC supplementation should be considered in cases where maternal milk is insufficient or donor milk is unavailable. The optimal age, timing, dosage, and form of BC administration still require further investigation.

Non-collagenous proteins, rather than the collagens, are key biochemical factors that mediate tenogenic bioactivity of tendon extracellular matrix

Despite the growing clinical use of extracellular matrix (ECM)-based biomaterials for tendon repair, undesired healing outcomes or complications have frequently been reported. A major scientific challenge has been the limited understanding of their functional compositions and mechanisms of action due to the complex nature of tendon ECM. Previously, we have reported a soluble ECM fraction from bovine tendons (tECM) by urea extraction, which exhibited strong, pro-tenogenic bioactivity on human adipose-derived stem cells (hASCs). In this study, to advance our previous findings and gain insights into the biochemical nature of its pro-tenogenesis activity, tECM was fractionated using (i) an enzymatic digestion approach (pepsin, hyaluronidase, and chondroitinase) to yield various enzyme-digested tECM fractions; and (ii) a gelation-based approach to yield collagen matrix-enriched (CM) and non-collagenous matrix-enriched (NCM) fractions. Their tenogenic bioactivity on hASCs was assessed. Our results collectively indicated that non-collagenous tECM proteins, rather than collagens, are likely the important biochemical factors responsible for tECM pro-tenogenesis bioactivity. Mechanistically, RNA-seq analysis revealed that tECM and its non-collagenous portion induced similar transcriptional profiles of hASCs, particularly genes associated with cell proliferation, collagen synthesis, and tenogenic differentiation, which were distinct from transcriptome induced by its collagenous portion. From an application perspective, the enhanced solubility of the non-collagenous tECM, compared to tECM, should facilitate its combination with various water-soluble biomaterials for tissue engineering protocols. Our work provides insight into the molecular characterization of native tendon ECM, which will help to effectively translate their functional components into the design of well-defined, ECM biomaterials for tendon regeneration. STATEMENT OF SIGNIFICANCE: Significant progress has been made in extracellular matrix (ECM)-based biomaterials for tendon repair. However, their effectiveness remains debated, with conflicting research and clinical findings. Understanding the functional composition and mechanisms of action of ECM is crucial for developing safe and effective bioengineered scaffolds. Expanding on our previous work with bovine tendon ECM extracts (tECM) exhibiting strong pro-tenogenesis activity, we fractionated tECM to evaluate its bioactive moieties. Our findings indicate that the non-collagenous matrix within tECM, rather than the collagenous portions, plays a major role in the pro-tenogenesis bioactivity on human adipose-derived stem cells. These insights will drive further optimization of ECM-based biomaterials, including our advanced method for preparing highly soluble, non-collagenous matrix-enriched tendon ECM for effective tendon repair.

Intestinal microbiota regulates diabetes and cancer progression by IL-1β and NOX4 dependent signaling cascades

Diabetes changes the host microbiota, a condition known as dysbiosis. Dysbiosis is an important factor for the pathogenesis of diabetes and colorectal cancer (CRC). We aimed at identifying the microbial signature associated with diabetes and CRC; and identifying the signaling mechanism altered by dysbiosis and leading to CRC progression in diabetes. MKR mice that can spontaneously develop type 2 diabetes were used. For CRC induction, another subset of mice was treated with azoxymethane and dextran sulfate sodium. To identify the role of microbiota, microbiota-depleted mice were inoculated with fecal microbial transplant from diabetic and CRC mice. Further, a mouse group was treated with probiotics. At the end of the treatment, 16S rRNA sequencing was performed to identify microbiota in the fecal samples. Blood was collected, and colons were harvested for molecular, anatomical, and histological analysis. Our results show that diabetes is associated with a microbial signature characterized by reduction of butyrate-forming bacteria. This dysbiosis is associated with gastrointestinal complications reflected by a reduction in colon lengths. These changes are reversed upon treatment with probiotics, which rectified the observed dysbiosis. Inoculation of control mice with diabetic or cancer microbiota resulted in the development of increased number of polyps. Our data also show that inflammatory cytokines (mainly interleukin (IL)-1β) and NADPH oxidase (NOX)4 are over-expressed in the colon tissues of diabetic mice. Collectively our data suggest that diabetes is associated with dysbiosis characterized by lower abundance of butyrate-forming bacteria leading to over-expression of IL-1β and NOX4 leading to gastrointestinal complications and CRC.

Tenogenic induction of human adipose-derived stem cells by soluble tendon extracellular matrix: composition and transcriptomic analyses

Background

Tendon healing is clinically challenging largely due to its inferior regenerative capacity. We have previously prepared a soluble, DNA-free, urea-extracted bovine tendon-derived extracellular matrix (tECM) that exhibits strong pro-tenogenic bioactivity on human adipose-derived stem cells (hASCs). In this study, we aimed to elucidate the mechanism of tECM bioactivity via characterization of tECM protein composition and comparison of transcriptomic profiles of hASC cultures treated with tECM versus collagen type I (Col1) as a control ECM component.

Methods

The protein composition of tECM was characterized by SDS-PAGE, hydroxyproline assay, and proteomics analysis. To investigate tECM pro-tenogenic bioactivity and mechanism of action, differentiation of tECM-treated hASC cultures was compared to serum control medium or Col1-treated groups, as assessed via immunofluorescence for tenogenic markers and RNA Sequencing (RNA-Seq).

Results

Urea-extracted tECM yielded consistent protein composition, including collagens (20% w/w) and at least 17 non-collagenous proteins (< 100 kDa) based on MS analysis. Compared to current literature, tECM included key tendon ECM components that are functionally involved in tendon regeneration, as well as those that are involved in similar principal Gene Ontology (GO) functions (ECM-receptor interaction and collagen formation) and signaling pathways (ECM-receptor interaction and focal adhesion). When used as a cell culture supplement, tECM enhanced hASC proliferation and tenogenic differentiation compared to the Col1 and FBS treatment groups based on immunostaining of tenogenesis-associated markers. Furthermore, RNA-Seq analysis revealed a total of 584 genes differentially expressed among the three culture groups. Specifically, Col1-treated hASCs predominantly exhibited expression of genes and pathways related to ECM-associated processes, while tECM-treated hASCs expressed a mixture of ECM- and cell activity-associated processes, which may explain in part the enhanced proliferation and tenogenic differentiation of tECM-treated hASCs.

Conclusions

Our findings showed that urea-extracted tECM contained 20% w/w collagens and is significantly enriched with other non-collagenous tendon ECM components. Compared to Col1 treatment, tECM supplementation enhanced hASC proliferation and tenogenic differentiation as well as induced distinct gene expression profiles. These findings provide insights into the potential mechanism of the pro-tenogenic bioactivity of tECM and support the development of future tECM-based approaches for tendon repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03038-0.

Methods to improve efficacy of orally administered bioactive peptides using bovine colostrum as an exemplar

BACKGROUND

Oral administration of bioactive peptides has potential clinical advantages, but its applicability is limited due to gastric and pancreatic enzyme proteolysis.

OBJECTIVE

To examine whether the co-packaging of bovine colostrum (BC), a rich source of IgG, immune and growth factors, with the food additives trehalose (carbohydrate), stearine (fat), casein (protein present in BC) or soy flour (plant based with high protease inhibitory activity) enhances the stability of BC against digestion.

DESIGN

Samples alone and in combination (BC+ 10% wt/wt trehalose, stearine, casein or soy) were exposed to HCl/pepsin, followed by trypsin and chymotrypsin ("CT"). Assessment of proliferation used gastric AGS cells (Alamar blue), IgG function measured bovine IgG anti-E.coli binding and ELISAs quantified growth factor constituents. In vivo bioassay assessed ability of BC alone or with soy to reduce injury caused by dextran sodium sulphate (DSS, 4% in drinking water, 7 days, test products started 2 days prior to DSS).

RESULTS

Proliferative activity of BC reduced 61% following HCl/pepsin and CT exposure. This was truncated 50% if soy was co-present, and also protected against loss of total IgG, IgG E.coli binding, TGFβ, lactoferrin and EGF (all P<0.01 vs BC alone). Co-packaging with trehalose was ineffective in preventing digestion whereas casein or stearine provided some intermediate protective effects. Rats given BC alone showed beneficial effects on weight gain, disease activity index, tissue histology and colonic MPO. Soy alone was ineffective. BC+ soy combination showed the greatest benefit with a dose of 7 mg/kg (6.4 BC + 0.6 soy flour) having the same degree of benefit as using 20 mg/kg BC alone.

CONCLUSION

Soy, and to a lesser extent casein, enhanced the biostability of BC against digestive enzymes. Co-packaging of BC with other food products such as soy flour could result in a decreased dose being required, improving cost-effectiveness and patient compliance.

Protease Inhibitors Protect Bovine Colostrum or Chicken Egg Growth Factors from Pancreatic Enzyme Digestion in AGS Cells or Colitic Rats

BACKGROUND

Bovine colostrum (BC) and chicken egg contain proteins possessing growth factor activity. Epidermal growth factor (EGF) provides much of the pro-reparative activity within BC. Clinical use of orally administered peptide growth factors is hampered by digestion from pancreatic proteases.

OBJECTIVES

We examined whether adding a protease inhibitor [soybean trypsin inhibitor (SBTI) or ovomucoid] protected bioactivity of BC ± egg or EGF alone against pancreatic digestion using in vitro and in vivo models.

METHODS

BC, egg, or EGF alone or in combination with trypsin inhibitors were tested for proliferative (Alamar blue) activity using human gastric adenocarcinoma (AGS) cells, prior to and after incubation with HCl/pepsin and trypsin/chymotrypsin. Data were analyzed using 2-factor ANOVA. Eight groups (n = 10) of adult female Sprague-Dawley rats (mean: 188.3 ± 0.8 g) received 20 mg/kg/d of BC + egg, 100 μg/d of EGF, 5 mg/d ovomucoid, or 10.8 mg/d SBTI, alone or in combination (in 1 mL 3% NaHCO3) by gavage for 9 d and dextran sodium sulfate (DSS; 5% in drinking water) for the final 7 d. Histology, microscopic damage score, and myeloperoxidase (MPO) were assessed and analyzed using 1-factor ANOVA.

RESULTS

Proliferative activities of BC, egg, or EGF were reduced 40-57% by HCl/pepsin exposure and further reduced 14-24% by chymotrypsin/trypsin. Co-addition of SBTI or ovomucoid truncated the decrease in proliferative bioactivity caused by chymotrypsin/trypsin by 54-100% (P < 0.01). In vivo study showed oral EGF alone or protease inhibitors given alone were ineffective in reducing DSS damage, whereas SBTI with EGF or ovomucoid with BC + egg improved protective effects on weight gain, disease activity score, colonic MPO, and histology damage by 3-4-fold (P < 0.01).

CONCLUSIONS

Studies using AGS, cells, and Sprague-Dawley rats showed the protease inhibitors ovomucoid and SBTI protected BC, egg, and EGF against loss of bioactivity due to pancreatic enzymes and, when given with NaHCO3, enhanced colonic protection against DSS damage.

Bovine Colostrum: Its Constituents and Uses

Colostrum is the milk produced during the first few days after birth and contains high levels of immunoglobulins, antimicrobial peptides, and growth factors. Colostrum is important for supporting the growth, development, and immunologic defence of neonates. Colostrum is naturally packaged in a combination that helps prevent its destruction and maintain bioactivity until it reaches more distal gut regions and enables synergistic responses between protective and reparative agents present within it. Bovine colostrum been used for hundreds of years as a traditional or complementary therapy for a wide variety of ailments and in veterinary practice. Partly due to concerns about the side effects of standard Western medicines, there is interest in the use of natural-based products of which colostrum is a prime example. Numerous preclinical and clinical studies have demonstrated therapeutic benefits of bovine colostrum for a wide range of indications, including maintenance of wellbeing, treatment of medical conditions and for animal husbandry. Articles within this Special Issue of Nutrients cover the effects and use bovine colostrum and in this introductory article, we describe the main constituents, quality control and an overview of the use of bovine colostrum in health and disease.

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.

Decellularized peripheral nerve supports Schwann cell transplants and axon growth following spinal cord injury

Schwann cell (SC) transplantation has been comprehensively studied as a strategy for spinal cord injury (SCI) repair. SCs are neuroprotective and promote axon regeneration and myelination. Nonetheless, substantial SC death occurs post-implantation, which limits therapeutic efficacy. The use of extracellular matrix (ECM)-derived matrices, such as Matrigel, supports transplanted SC survival and axon growth, resulting in improved motor function. Because appropriate matrices are needed for clinical translation, we test here the use of an acellular injectable peripheral nerve (iPN) matrix. Implantation of SCs in iPN into a contusion lesion did not alter immune cell infiltration compared to injury only controls. iPN implants were larger and contained twice as many SC-myelinated axons as Matrigel grafts. SC/iPN animals performed as well as the SC/Matrigel group in the BBB locomotor test, and made fewer errors on the grid walk at 4 weeks, equalizing at 8 weeks. The fact that this clinically relevant iPN matrix is immunologically tolerated and supports SC survival and axon growth within the graft offers a highly translational possibility for improving efficacy of SC treatment after SCI. To our knowledge, it is the first time that an injectable PN matrix is being evaluated to improve the efficacy of SC transplantation in SCI repair.

Crystal structure and mechanism of human carboxypeptidase O: Insights into its specific activity for acidic residues

Human metallocarboxypeptidase O (hCPO) is a recently discovered digestive enzyme localized to the apical membrane of intestinal epithelial cells. Unlike pancreatic metallocarboxypeptidases, hCPO is glycosylated and produced as an active enzyme with distinctive substrate specificity toward C-terminal (C-t) acidic residues. Here we present the crystal structure of hCPO at 1.85-Å resolution, both alone and in complex with a carboxypeptidase inhibitor (NvCI) from the marine snail Nerita versicolor The structure provides detailed information regarding determinants of enzyme specificity, in particular Arg275, placed at the bottom of the substrate-binding pocket. This residue, located at "canonical" position 255, where it is Ile in human pancreatic carboxypeptidases A1 (hCPA1) and A2 (hCPA2) and Asp in B (hCPB), plays a dominant role in determining the preference of hCPO for acidic C-t residues. Site-directed mutagenesis to Asp and Ala changes the specificity to C-t basic and hydrophobic residues, respectively. The single-site mutants thus faithfully mimic the enzymatic properties of CPB and CPA, respectively. hCPO also shows a preference for Glu over Asp, probably as a consequence of a tighter fitting of the Glu side chain in its S1' substrate-binding pocket. This unique preference of hCPO, together with hCPA1, hCPA2, and hCPB, completes the array of C-t cleavages enabling the digestion of the dietary proteins within the intestine. Finally, in addition to activity toward small synthetic substrates and peptides, hCPO can also trim C-t extensions of proteins, such as epidermal growth factor, suggesting a role in the maturation and degradation of growth factors and bioactive peptides.

Specific protein supplementation using soya, casein or whey differentially affects regional gut growth and luminal growth factor bioactivity in rats; implications for the treatment of gut injury and stimulating repair

Modulation of regional growth within specific segments of the bowel may have clinical value for several gastrointestinal conditions. We therefore examined the effects of different dietary protein sources on regional gut growth and luminal growth factor bioactivity as potential therapies. Rats were fed for 14 days on isonitrogenous and isocaloric diets comprising elemental diet (ED) alone (which is known to cause gut atrophy), ED supplemented with casein or whey or a soya protein-rich feed. Effects on regional gut growth and intraluminal growth factor activity were then determined. Despite calorie intake being similar in all groups, soya rich feed caused 20% extra total body weight gain. Stomach weight was highest on soya and casein diets. Soya enhanced diet caused greatest increase in small intestinal weight and preserved luminal growth factor activity at levels sufficient to increase proliferation in vitro. Regional small intestinal proliferation was highest in proximal segment in ED fed animals whereas distal small intestine proliferation was greater in soya fed animals. Colonic weight and proliferation throughout the colon was higher in animals receiving soya or whey supplemented feeds. We conclude that specific protein supplementation with either soya, casein or whey may be beneficial to rest or increase growth in different regions of the bowel through mechanisms that include differentially affecting luminal growth factor bioactivity. These results have implications for targeting specific regions of the bowel for conditions such as Crohn's disease and chemotherapy.

Protective effects of amniotic fluid in the setting of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common life threatening condition affecting preterm infants. NEC occurs in 1-5% of all neonatal intensive care admissions and 5-10% of very low birth weight infants. The protective role of human breast milk (BM) has been well established. It has also been shown that amniotic fluid (AF) and BM have many similarities in terms of presence of growth and other immune-modulatory factors. This finding led to the initial hypothesis that AF may exert similar protective effects against the development of NEC, as does BM. Multiple studies have elucidated the presence of growth factors in AF and the protective effect of AF against NEC. Studies have also described possible mechanisms how AF protects against NEC. At present, research in this particular area is extremely active and robust. This review summarizes the various studies looking at the protective effects of AF against the development of NEC. It also provides an insight into future directions, the vast potential of AF as a readily available biologic medium, and the ethical barriers that must be overcome before using AF.

Extracellular matrix particle-glycosaminoglycan composite hydrogels for regenerative medicine applications

Tissue extracellular matrix (ECM) is a complex material made up of fibrous proteins and ground substance (glycosaminoglycans, GAGs) that are secreted by cells. ECM contains important biological cues that modulate cell behaviors, and it also serves as a structural scaffold to which cells can adhere. For clinical applications, where immune rejection is a constraint, ECM can be processed using decellularization methods intended to remove cells and donor antigens from tissue or organs, while preserving native biological cues essential for cell growth and differentiation. In this study, a decellularized ECM-based composite hydrogel was formulated by using modified GAGs that covalently bind tissue particles. These GAG-ECM composite hydrogels combine the advantages of solid decellularized ECM scaffolds and pepsin-digested ECM hydrogels by facilitating ECM hydrogel formation without a disruptive enzymatic digestion process. Additionally, engineered hydrogels can contain more than one type of ECM (from bone, fat, liver, lung, spleen, cartilage, or brain), at various concentrations. These hydrogels demonstrated tunable gelation kinetics and mechanical properties, offering the possibility of numerous in vivo and in vitro applications with different property requirements. Retained bioactivity of ECM particles crosslinked into this hydrogel platform was confirmed by the variable response of stem cells to different types of ECM particles with respect to osteogenic differentiation in vitro, and bone regeneration in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 147-159, 2018.

Importance of Amniotic Fluid in Gastrointestinal Development

Amniotic fluid (AF) is a bioactive medium containing various trophic factors and other nutrients that are necessary for fetal growth and organogenesis. Many trophic factors present in AF are responsible for the development of the fetal gastrointestinal tract. Development and maturation of the gastrointestinal tract is a complex cascade that begins before birth and continues during infancy and childhood by breastfeeding. Many factors, such as genetic preprogramming, local and systemic endocrine secretions, and many trophic factors from swallowed AF, modulate the development and growth of the gastrointestinal tract. Studies are currently examining a potential role of stem cells in AF as a protective agent against the development of necrotizing enterocolitis in preterm infants. Preliminary studies suggest that simulated AF may be a possible means of reducing feeding intolerance. In this article, the authors review the various functions of AF and its importance in fetal gastrointestinal tract development. They also examine possible future uses of this extremely important bioactive fluid.

Amniotic fluid: Source of trophic factors for the developing intestine

The gastrointestinal tract (GIT) is a complex system, which changes in response to requirements of the body. GIT represents a barrier to the external environment. To achieve this, epithelial cells must renew rapidly. This renewal of epithelial cells starts in the fetal life under the influence of many GIT peptides by swallowing amniotic fluid (AF). Development and maturation of GIT is a very complex cascade that begins long before birth and continues during infancy and childhood by breast-feeding. Many factors like genetic preprogramming, local and systemic endocrine secretions and many trophic factors (TF) from swallowed AF contribute and modulate the development and growth of the GIT. GIT morphogenesis, differentiation and functional development depend on the activity of various TF in the AF. This manuscript will review the role of AF borne TF in the development of GIT.

Biochemical characterization of a novel carboxypeptidase inhibitor from a variety of Andean potatoes

Natural protease inhibitors of metallocarboxypeptidases are rarely reported. In this work, the cloning, expression and characterization of a proteinaceous inhibitor of the A/B-type metallocarboxypeptidases, naturally occurring in tubers of Solanum tuberosum, subsp. andigenum cv. Imilla morada, are described. The obtained cDNA encoded a polypeptide of 80 residues, which displayed the features of metallocarboxypeptidase inhibitor precursors from the Potato Carboxypeptidase Inhibitor (PCI) family. The mature polypeptide (39 residues) was named imaPCI and in comparison with the prototype molecule of the family (PCI from S. tuberosum subsp. tuberosum), its sequence showed one difference at its N-terminus and another three located at the secondary binding site, a region described to contribute to the stabilization of the complex inhibitor-target enzyme. In order to gain insights into the relevance of the secondary binding site in nature, a recombinant form of imaPCI (rimaPCI) having only differences at the secondary binding site with respect to recombinant PCI (rPCI) was cloned and expressed in Escherichia coli. The rimaPCI exhibited a molecular mass of 4234.8Da by MALDI-TOF/MS. It displayed potent inhibitory activity towards A/B-type carboxypeptidases (with a Ki in the nanomolar range), albeit 2-4-fold lower inhibitory capacity compared to its counterpart rPCI. This result is in agreement with our bioinformatic analysis, which showed that the main interaction established between the secondary binding site of rPCI and the bovine carboxypeptidase A is likely lost in the case of rimaPCI. These observations reinforce the importance of the secondary binding site of PCI-family members on inhibitory effects towards A/B-type metallocarboxypeptidases. Furthermore, as a simple proof of concept of its applicability in biotechnology and biomedicine, the ability of rimaPCI to protect human epidermal growth factor from C-terminal cleavage and inactivation by carboxypeptidases A and B was demonstrated.

Diet and esophageal cancer risk in the Eastern Cape Province of South Africa

A multicenter hospital-based case-control study comprising 670 incident cases of esophageal cancer (EC) and 1188 controls, frequency-matched for age and sex, was conducted to evaluate the role of diet on EC development in the Eastern Cape Province, South Africa. A locally relevant lifestyle and dietary questionnaire was used. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were computed using unconditional multivariable logistic regression. Individually, maize or sorghum consumption vs. never or rare consumption were not associated with EC (P > 0.1). Males and females consuming green leafy vegetables 5-7 days/wk had 38% (P = 0.04) and 50% (P = 0.007) reduced odds of developing EC, respectively, compared with consumption ≤1 day/wk. A similar reduction in odds was observed with fruit consumption. Principal component factor analysis revealed 3 distinct dietary patterns. In females, high vs. low consumption of Pattern 1 (sorghum, green leafy vegetables, green legumes, fruits, meat) was inversely associated with EC development (OR = 0.54; 95% CI: 0.34-0.89), whereas for Pattern 2 (maize, wild greens-imifino, dry beans) the odds were elevated (OR = 1.67; 95% CI: 1.04-2.67). Compared with low adherence, high adherence to Pattern 3 (wheat-based products) reduced the odds by 35% for both sexes. This study provides further evidence on the role of diet in minimizing EC risk in this population.

Dimethyloxalyglycine stimulates the early stages of gastrointestinal repair processes through VEGF-dependent mechanisms

Dimethyloxalylglycine (DMOG) is an inhibitor of prolyl-4-hydroxylase domain enzymes. Its potential value and mechanism of actions in preventing/treating gastrointestinal injury are, however, poorly understood. We, therefore, examined the effect of DMOG on influencing gut injury and repair using a variety of in vitro and in vivo models. We performed in vitro studies utilising pro-migratory (wounded monolayer) and proliferation (using DNA quantitation) assays of human stomach (AGS) and colonic (HT29) carcinoma cells. Time course studies examined changes in hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF) levels, a growth factor known to be regulated via HIF. In vivo studies utilised a rat gastric (indomethacin, 20 mg/kg and 3 h restraint) damage model. DMOG stimulated migration in a dose-dependent manner, increasing migration twofold when added at 25μM (P<0.01). Additive effects were seen when DMOG was added to cells in hypoxic conditions. DMOG stimulated proliferation dose dependently, increasing proliferation threefold when added at 70 μM (P<0.01). DMOG caused upregulation of both HIF and VEGF within 4 h of administration. Addition of VEGF neutralising antibody truncated migratory and proliferative activity of DMOG by about 70%. Both oral and subcutaneous administration of DMOG decreased gastric injury without influencing intragastric pH (50% reduction in injury when 1 ml gavaged at 0.57 mM, P < 0.01). Indomethacin reduced tissue HIF and VEGF levels but this was prevented if DMOG was present. In conclusion, DMOG stimulates the early phases of gut repair and VEGF-dependent processes appear relevant. Non-peptide factors such as this may be useful to stabilise or repair gut mucosa.

Characterization of the human gastric fluid proteome reveals distinct pH-dependent protein profiles: implications for biomarker studies

Gastric fluid is a source of gastric cancer biomarkers. However, very little is known about the normal gastric fluid proteome and its biological variations. In this study, we performed a comprehensive analysis of the human gastric fluid proteome using samples obtained from individuals with benign gastric conditions. Gastric fluid proteins were prefractionated using ultracentrifuge filters (3 kDa cutoff) and analyzed by two-dimensional gel electrophoresis (2-DE) and multidimensional LC-MS/MS. Our 2-DE analysis of 170 gastric fluid samples revealed distinct protein profiles for acidic and neutral samples, highlighting pH effects on protein composition. By 2D LC-MS/MS analysis of pooled samples, we identified 284 and 347 proteins in acidic and neutral samples respectively (FDR ≤1%), of which 265 proteins (72.4%) overlapped. However, unlike neutral samples, most proteins in acidic samples were identified from peptides in the filtrate (i.e., <3 kDa). Consistent with this finding, immunoblot analysis of six potential gastric cancer biomarkers rarely detected full-length proteins in acidic samples. These findings have important implications for biomarker studies because a majority of gastric cancer patients have neutral gastric fluid compared to noncancer controls. Consequently, sample stratification, choice of proteomic approaches, and validation strategy can profoundly affect the interpretation of biomarker findings. These observations should help to refine gastric fluid biomarker studies.

Topical agents for idiopathic distal colitis and proctitis

Rectally administered topical agents have demonstrated efficacy in the maintenance of distal colitis (DC) and proctitis and as they are rarely associated with significant blood drug levels, side effects are infrequent. The topical 5-aminosalicylic acid (5-ASA) suppositories and enemas target different regions of the distal colon and are effective for proctitis and DC, respectively. They demonstrate clinical results that are better than oral 5-ASAs and are preferred to topical steroids with better clinical, endoscopic and histological outcomes, without the risk of adrenal suppression. Disease resistant to topical agents, however, can be extremely difficult to manage. The addition of oral 5ASAs, steroids, immunosuppressants and the anti-tumor necrosis factor-α agents may be effective, but can result in significant side effects and not all patients will respond to the therapies. It is for these patients that new and novel therapies are required. Novel topical agents have been proposed for the management of resistant DC. These agents included butyrate, cyclosporine, and nicotine enemas, as well as tacrolimus suppositories, and tacrolimus, ecabet sodium, arsenic, lidocaine, bismuth, rebamipide and thromboxane enemas. While some of these agents appear to demonstrate impressive outcomes, the majority have only been examined in small open-labeled studies. There is thus a desperate need for more randomized double-blinded placebo controlled studies to investigate the clinical utility of these topical therapies. This review summarizes the efficacy of the established topical therapies, and explores the available data on the new and novel topical agents for the management of DC and proctitis.

Attenuation of stress-induced gastric lesions by lansoprazole, PD-136450 and ranitidine in rats

Combining restraint with cold temperature (4°C) consistently induces gastric ulceration in rats after 3.5 h. The cold restraint-stress (CRS) method provides a suitable model for acute ulcer investigations. This study compares the antiulcer activities of lansoprazole (a proton pump inhibitor), PD-136450 (CCK(2)/gastrin receptor antagonist) and ranitidine (histamine H(2) receptor antagonist) on CRS-induced gastric ulcers in rats. The results have shown that lansoprazole, which is a potent anti-secretory agent, provides complete protection in this model of ulcer formation. The use of indomethacin pretreatment to inhibit the prostaglandin (PG) synthesis and N(G)-nitro L-arginine methyl ester (L-NAME) pretreatment to inhibit nitric oxide synthase did not alter the lansoprazole-induced inhibition of ulcer index obtained in the untreated Wistar rats indicating that these two systems were not involved in the activation of lansoprazole. PD-136450, an effective anti-secretory agent against gastrin- but not dimaprit-induced stimulation, evoked a dose-dependent inhibition of CRS-induced gastric ulcers. The results show that both PG and nitric oxide pathways can influence the inhibitory effect of PD-136450 against CRS-induced gastric ulcer. The antiulcer activities of both lansoprazole and PD-136450 were compared to that of ranitidine. The results showed that ranitidine was more potent than lansoprazole and PD-136450 in inhibiting CRS-induced gastric ulcers and its effect was shown to be influenced by PG as well as nitric oxide synthase. The results of this study have demonstrated that although lansoprazole, PD-136450 and ranitidine were protective against CRS-induced gastric ulcers, the antiulcer activities of PD-136450 and ranitidine involved both PG and nitric oxide pathways, while lansoprazole acted independently of these two systems during CRS.

Human milk proteins: an interactomics and updated functional overview

Milk and milk fractions are characterized by a wide array of proteins, whose concentration spans across several orders of magnitude. By exploiting a combined approach based on functional gene ontology enrichment (FatiGO/Babelomics), hierarchical clustering, and pathway and network analyses, we merged data from literature dealing with protein-oriented studies on human milk. A total of 285 entries defined a nonredundant list upon comparison with the Ingenuity Knowledge Base from the Ingenuity Pathway Analysis software. Results were compared with an inventory of bovine milk proteins gathered from dedicated proteomic studies. A protein core of 106 proteins was found, with most of the entries associated to three main biological functions, namely nutrient transport/lipid metabolism, concretization of the immune system response and cellular proliferation processes. Our analyses confirm and emphasize that the biological role of the human milk proteins is not only limited to the provision of external nutrients and defense molecules against pathogens to the suckling but also to the direct stimulation of the growth of neonate tissues/organs and to the development of a proper independent immune system, both through the induction of a number of molecular cascades associated with cell proliferation/differentiation. The latter aspects were previously investigated by single-molecule dedicated studies, missing the holistic view that results from our analysis.

Novel topical therapies for distal colitis

Distal colitis (DC) can be effectively treated with topical 5ASA agents. Suppositories target the rectum while enemas can reliably reach the splenic flexure. Used in combination with oral 5ASAs, the control of the inflammation is even more effective. Unfortunately, resistant DC does occur and can be extremely challenging to manage. In these patients, the use of steroids, immunosuppressants and the anti-tumor necrosis factor α agents are often required. These, however, can be associated with systemic side effects and are not always effective. The investigation of new topical therapeutic agents is thus required as they are rarely associated with significant blood drug levels and side effects are infrequent. Some of the agents that have been proposed for use in resistant distal colitis include butyrate, cyclosporine and nicotine enemas as well as tacrolimus suppositories and tacrolimus, ecabet sodium, arsenic, lidocaine, rebamipide and Ridogrel^® enemas. Some of these agents have demonstrated impressive results but the majority of the agents have only been assessed in small open-labelled patient cohorts. Further work is thus required with the investigation of promising agents in the context of randomized double-blinded placebo controlled trials. This review aims to highlight those potentially effective therapies in the management of resistant distal colitis and to promote interest in furthering their investigation.

Proton pump inhibitors: actions and reactions

Proton pump inhibitors are the second most commonly prescribed drug class in the United States. The increased utilization of PPIs parallels the rising incidence of reflux disease. Owing to their clinical efficacy and relative lack of tachyphylaxis, PPIs have largely displaced H-2 receptor antagonists in the treatment of acid peptic disorders. The elevation of intragastric pH and subsequent alterations of gastric physiology induced by PPIs may yield undesired effects within the upper GI tract. The ubiquity of the various types of H(+), K(+)-ATPase could also contribute to non-gastric effects. PPIs may influence physiology in other ways, such as inducing transepithelial leak.

Secreted trefoil factor 2 activates the CXCR4 receptor in epithelial and lymphocytic cancer cell lines

The secreted trefoil factor family 2 (TFF2) protein contributes to the protection of the gastrointestinal mucosa from injury by strengthening and stabilizing mucin gels, stimulating epithelial restitution, and restraining the associated inflammation. Although trefoil factors have been shown to activate signaling pathways, no cell surface receptor has been directly linked to trefoil peptide signaling. Here we demonstrate the ability of TFF2 peptide to activate signaling via the CXCR4 chemokine receptor in cancer cell lines. We found that both mouse and human TFF2 proteins (at approximately 0.5 microm) activate Ca2+ signaling in lymphoblastic Jurkat cells that could be abrogated by receptor desensitization (with SDF-1alpha) or pretreatment with the specific antagonist AMD3100 or an anti-CXCR4 antibody. TFF2 pretreatment of Jurkat cells decreased Ca2+ rise and chemotactic response to SDF-1alpha. In addition, the CXCR4-negative gastric epithelial cell line AGS became highly responsive to TFF2 treatment upon expression of the CXCR4 receptor. TFF2-induced activation of mitogen-activated protein kinases in gastric and pancreatic cancer cells, KATO III and AsPC-1, respectively, was also dependent on the presence of the CXCR4 receptor. Finally we demonstrate a distinct proliferative effect of TFF2 protein on an AGS gastric cancer cell line that expresses CXCR4. Overall these data identify CXCR4 as a bona fide signaling receptor for TFF2 and suggest a mechanism through which TFF2 may modulate immune and tumorigenic responses in vivo.

Improving the stability of insulin in solutions containing intestinal proteases in vitro

Degradation of insulin was studied in this work. Casein and protamine could obviously suppress degradation of insulin by intestinal enzymes, and could protect insulin from degradation by the mechanism of competition and combination with proteolysis enzyme. What is more, co-incubated with HP-β-CD-casein or HP-β-CD-protamine, most insulin was protected from degradation by intestinal enzymes. In addition, it was found that the complexation of insulin with HP-β-CD was characterized by UV absorption spectra. These results indicated that HP-β-CD, casein and protamine could offer some positive and useful results, and could protect insulin from degradation during their transit through the intestinal tract.

Effects of pantoprazole on ulcer healing delay associated with NSAID treatment

Nonsteroidal anti-inflammatory drugs delay gastric ulcer healing, and the ability of proton pump inhibitors to counteract this detrimental effect is debated. This study evaluates the effects of pantoprazole on experimental gastric ulcer healing in the presence of indomethacin. Rats with acetic-acid-induced gastric ulcers were orally treated for 3 or 7 days with pantoprazole (15 micromol/kg/day) or famotidine (20 micromol/kg/day), alone or in combination with indomethacin (3 micromol/kg/day). Ulcerated tissues were processed to assess ulcer area, malondialdehyde, proliferating cell nuclear antigen (PCNA) and cleaved caspase-3. Experiments on pylorus-ligated rats indicated that pantoprazole and famotidine were employed at equivalent inhibitory doses on gastric acid secretion (-67.9% and -64.5%, respectively). Indomethacin delayed ulcer healing both at days 3 and 7 (+22 and +35 mm(2) vs control ulcer, respectively). At day 3, pantoprazole was more effective than famotidine in promoting ulcer healing in indomethacin-treated animals (-53.6 and -31.6 mm(2) vs indomethacin, respectively). Malondialdehyde levels and caspase-3 activation in ulcers were increased by indomethacin (+79% and +3.7 folds vs control ulcer, respectively), and these effects were counteracted by pantoprazole (-77.9% and -3.5 folds vs indomethacin, respectively), but not famotidine. Increments of ulcer PCNA expression (+2.5 folds vs normal) were enhanced further by pantoprazole or famotidine, alone or in combination with indomethacin (+8.6 and +10.3 folds vs normal, respectively). Similar results were obtained after 7-day treatments of ulcerated animals with test drugs. It is concluded that, along with acid suppression, pantoprazole exerts acid-independent effects on ulcer healing, which can be ascribed to a decrease in tissue oxidation and apoptosis.

Degradation of teriparatide by gastro-intestinal proteolytic enzymes

Teriparatide, a recombinant parathyroid hormone (1-34) is the first approved agent for the treatment of osteoporosis that stimulates new bone formation. Currently, the drug is administered daily by s.c. injection. Because of the obvious advantages of oral teriparatide administration, the development of such a delivery system would be of great benefit. Besides other barriers, the enzymatic barrier caused by gastro-intestinal (GI) proteolytic enzymes is believed to be responsible for negligible teriparatide oral bioavailability. It was therefore the aim of the study to evaluate the stability of teriparatide towards a variety of GI proteases under physiological conditions. Results indicate that teriparatide is entirely degraded by trypsin, chymotrypsin and pepsin within 5 min. In contrast, even after 3 h of incubation with elastase about 85% of undegraded teriparatide could still be detected. Within an incubation period of 3 h in the presence of rat small intestinal mucosa, approximately half of the teriparatide was degraded. Experiments with isolated aminopeptidase N demonstrated that this membrane bound peptidase is primarily involved in the degradation process. Results gained from and recorded in this study provide a precise characterisation of the enzymatic barrier for oral teriparatide administration and represents a prerequisite for the development of oral teriparatide delivery systems.

Effects of mouse and human lipocalin homologues 24p3/lcn2 and neutrophil gelatinase-associated lipocalin on gastrointestinal mucosal integrity and repair

BACKGROUND & AIMS

The lipocalin superfamily, including the mouse and human homologues 24p3/lcn2 and neutrophil gelatinase-associated lipocalin, show great functional diversity including roles in olfaction, transportation, and prostaglandin synthesis in mammals. Their potential role in maintaining gastrointestinal mucosal integrity and repair is, however, unclear.

METHODS

Changes in 24p3/lcn2 expression in the mouse gut in response to various noxious agents were examined using Northern blot, in situ hybridization, and immunohistochemistry. Effects of recombinant 24p3/lcn2 on proliferation ([3H]-thymidine uptake), and restitution (cell-wounding migration) were assessed using human colonic HT29 and HCT116 cells. In addition, the effects of recombinant 24p3/lcn2 on the amount of gastric damage were assessed in rats treated with indomethacin (20 mg/kg) and restraint.

RESULTS

Marked up-regulation of expression of 24p3/lcn2 was seen throughout the gut in response to indomethacin or dextran sodium sulfate treatment. Expression was increased particularly in the surface epithelial cells and infiltrating inflammatory cells. Proliferation and restitution assays in the presence of recombinant wild-type sequence neutrophil gelatinase-associated lipocalin, wild-type cys(98)-24p3/lcn2, and mutant ala98-24p3/lcn2 showed that all 3 peptides caused a 3- to 4-fold increase in promigratory activity (P < .01 vs control) but did not influence proliferation. The administration of wild-type cys98-, or mutant ala98-24p3/lcn2 (25 and 50 microg/kg/h, respectively), given via the subcutaneous route, both caused similar reductions in the rat gastric damage model (60% reduction at highest dose, P < .01 vs control), although oral administration was ineffective.

CONCLUSIONS

24p3/lcn2 facilitates mucosal regeneration by promoting cell migration.

Expression of porcine epidermal growth factor in Pichia pastoris and its biology activity in early-weaned piglets

Early-weaned piglets often have abnormalities in intestinal morphology and function. Epidermal growth factor (EGF) is critical in the development and in the repair of the gastrointestinal tract in pigs. This study investigated the effects of dietary EGF supplementation on growth performance and small intestinal morphology of early-weaned piglets. The functional domain of porcine EGF (pEGF) was cloned after RT-PCR amplification. The recombinant protein was expression by the Pichia pastoris expression system and the construct pPIC9K-pEGF was transformed into host GS115. The secretary recombinant protein in the supernatants was analyzed by SDS-PAGE. The gel indicated that the extra band at 6 kDa in the transformant, which corresponds to the standard hEGF, were both reactive to anti-pEGF antibody by Western blotting. The expression level of pEGF in the culture supernatant was 870 microg/mL. An animal feeding test was conducted to identify the effects of pEGF supplementation on growth performance and the development of digestive tracts of 14-day weaned piglets. The dietary treatment was a corn-soybean meal basal diet either with or without 1.5 mg/kg recombinant pEGF from the transformant fermentative supernatant. Dietary treatments enhanced the daily gain during 0-7 days postweaning (p < 0.05), but did not affect the performance throughout the entire test period. Dietary supplemental pEGF significantly increased serum IgA levels on day 18 postweaning, and increased the mucosa IgA levels and crypt depth at jejunum on day 28 postweaning (p < 0.05). The experimental results showed that the recombinant pEGF could be secreted by P. pastoris. The trophic effects of pEGF on growth performance, immune response, and small intestine development were determined by feeding recombinant pEGF to early-weaned piglets.

IL-8/CXC ligand 8 survives neonatal gastric digestion as a result of intrinsic aspartyl proteinase resistance

The human fetus and neonate swallow biologically significant quantities of IL-8/CXC ligand 8 (CXCL8) in amniotic fluid and breast milk, and this remains measurable through simulated neonatal gastric and proximal intestinal digestions. We sought to confirm the structural and functional integrity of IL-8/CXCL8 in digestates and determine the mechanisms underlying this protease resistance. We observed that in comparison with BSA, IL-8/CXCL8 is highly resistant to pepsin and can be detected intact in assays for structural, immunologic, and functional integrity. In a computational molecular docking simulation, IL-8/CXCL8 was observed to fit poorly in the pepsin active site. On the basis of simulated mutation analyses, we hypothesized that this protease resistance is due to disulfide bond-related tertiary folding in IL-8/CXCL8. This was confirmed on chemical reduction of these groups.

Effect of oral epidermal growth factor on mucosal healing in rats with duodenal ulcer

AIM: To investigate the effect of epidermal growth factor (EGF) on mucosal healing in rats with duodenal ulcer.

METHODS: Male Sprague-Dawley rats were randomly divided into sham operation without EGF, sham operation with EGF, duodenal ulcer without EGF, or duodenal ulcer with EGF groups. Additionally, normal rats without operation served as the control group. Duodenal ulcer was induced in rats by 300 mL/L acetic acid. Rats with EGF were orally administered at a dose of 60 μg/kg/day in drinking water on the next day of operation (day 1). Healing of duodenal ulcer was detected by haematoxylin and eosin staining. Cell growth of damaged mucosa was determined by the contents of nucleic acids and proteins. The level of EGF in duodenal mucosa was measured by ELISA.

RESULTS: The pathological results showed that duodenal ulcer rats with EGF improved mucosal healing compared with those without EGF after day 5. Duodenal ulcer rats with EGF significantly increased duodenal DNA content compared with those without EGF on day 15 (6.44 ± 0.54 mg/g vs 1.45 ± 0.52 mg/g mucosa, P < 0.05). Duodenal RNA and protein contents did not differ between duodenal ulcer rats with and without EGF during the experimental period. Sham operation and duodenal ulcer rats with EGF significantly increased duodenal mucosal EGF content compared with those without EGF on day 5 (76.0 ± 13.7 ng/g vs 35.7 ± 12.9 ng/g mucosa in sham operation rats, and 68.3 ± 10.9 ng/g vs 28.3 ± 9.2 ng/g mucosa in duodenal ulcer rats, P < 0.05).

CONCLUSION: Oral EGF can promote mucosal healing of the rats with duodenal ulcer by stimulating mucosal proliferation accompanied by an increase in mucosal EGF content.

Epidermal growth factor enemas with oral mesalamine for mild-to-moderate left-sided ulcerative colitis or proctitis

BACKGROUND

Epidermal growth factor (EGF) is a potent mitogenic peptide produced by salivary glands. We examined whether EGF enemas are an effective treatment for active left-sided ulcerative colitis and ulceration limited to the rectum (proctitis).

METHODS

In a randomized, double-blind clinical trial conducted at Leicester Royal Infirmary, 12 patients with mild-to-moderate left-sided ulcerative colitis received daily enemas of 5 microg of EGF in 100 ml of an inert carrier and 12 received daily enemas with carrier alone for 14 days. All also began to receive 1.2 g of oral mesalamine per day or had their dose increased by 1.2 g per day. Patients were assessed clinically at 0, 2, 4, and 12 weeks and by sigmoidoscopy and biopsy at 0, 2, and 4 weeks. The primary end point was disease remission (defined by a St. Marks score of 4 or less without sigmoidoscopic evidence of inflammation) at two weeks. Secondary end points were clinically significant improvements in disease activity (defined by a decrease of more than 3 points in the St. Marks score or the ulcerative colitis disease-activity index) at two and four weeks. Analyses were performed according to the intention-to-treat principle.

RESULTS

After two weeks, 10 of the 12 patients given EGF enemas were in remission, as compared with 1 of 12 in the control group (83 percent vs. 8 percent, P<0.001). At the 2-week assessment, disease-activity scores, sigmoidoscopic score, and histologic scores were all significantly better in the EGF group than in the placebo group (P<0.01 for all comparisons), and this benefit was maintained at 4 weeks and at 12 weeks.

CONCLUSIONS

This study provides preliminary data suggesting that EGF enemas are an effective treatment for active left-sided ulcerative colitis.

Apical EGF receptors regulate epithelial barrier to gastric acid: endogenous TGF-alpha is an essential facilitator

In previous studies, we found that apical and basolateral EGF receptors (EGFR) on primary canine gastric monolayers decreased paracellular permeability, evident by increased transepithelial electrical resistance (TER) and decreased flux of [(3)H]mannitol (MF). After studying monolayers in Ussing chambers, we now report that treatment with apical, but not basolateral, EGF enhanced tolerance to apical H(+), evident by a slower decay in TER and an attenuated rise in MF. Enhanced tolerance to apical acid was evident within 10 min of treatment with apical EGF. Immunoneutralization of endogenous transforming growth factor (TGF)-alpha accelerated the drop in TER and the rise in MF in response to apical acidification; apical EGF reversed these effects. Study of monolayers cultured in Transwell inserts showed that immunoblockade of basolateral, but not apical, EGFR also impaired the resistance to apical acidification and enhanced MF. We conclude that apical EGFR regulates the barrier to apical acidification via effects on paracellular resistance. Although exogenous basolateral EGF has a less apparent effect on the barrier to acid, endogenous ligand active at basolateral EGFR plays an important role in maintaining the barrier to apical acid. Our data implicate a role for an apical EGFR ligand, which may be EGF or another member of the EGF family.

The effect of epidermal growth factor on the distribution of SGLT-1 in rabbit jejunum

The effect of epidermal growth factor (EGF) on the cellular and villous distribution of the sugar transporter SGLT-1 was examined. New Zealand White rabbits (1 kg) were anesthetized, and two jejunal blind loops were isolated and exposed to either 0.9% saline or EGF (60 ng/mL saline), for 1 h. In separate experiments, tissue was harvested for brush border membrane vesicles (BBMV), microsomal membranes, or fixed for immunohistochemistry. SGLT-1 was measured in membrane fractions by Western immunoblot or localized along the villus-crypt axis by immunofluorescent microscopy. EGF increased BBMV SGLT-1 content compared with paired controls. EGF stimulation also induced a corresponding decrease in microsomal SGLT-1 levels and induced the expression of additional SGLT-1 immunoreactivity further down the villus axis. The findings suggest that EGF upregulates intestinal glucose transport by stimulating the translocation of SGLT-1 from an internal microsomal pool into the brush border, thereby recruiting more villus enterocytes into the glucose transporting population.

Prophylactic use of epidermal growth factor reduces ischemia/reperfusion intestinal damage

Ischemia/reperfusion of mesenteric vessels is a useful model for acute vascular insufficiency and the early stages of multiorgan failure, conditions associated with high morbidity and mortality. Epidermal growth factor (EGF) is a potent mitogen that shows potential for use in intestinal injury. We therefore examined its influence on this model. Male Sprague-Dawley rats received human recombinant EGF (2 mg/kg i.p., n = 14) or saline (n = 16); 25 minutes before arterial clamping of the superior mesenteric artery (ischemic period) for 60 minutes followed by a final 60-minute reperfusion period. Additional rats were not operated on (controls, n = 7) or had sham operation (laparotomy only, n = 10). Ischemia/reperfusion caused macroscopic damage affecting 56%, 51 to 67% (median, interquartile range), of small intestinal length and intraluminal bleeding. Malondialdehyde levels (free radical marker) increased eightfold compared to nonoperated animals (2400, 2200 to 2700 micro mol/mg protein versus 290, 250 to 350 micro mol/mg protein, P < 0.01) and myeloperoxidase levels (marker for inflammatory infiltrate) increased 15-fold (3150, 2670 to 4180 U/g tissue versus 240, 190 to 250 U/g tissue, P < 0.01). Pretreatment with EGF reduced macroscopic injury to 11%, 0 to 15%; prevented intraluminal bleeding; and reduced malondialdehyde and myeloperoxidase levels by approximately 60% and 90% (all P < 0.01 versus non-EGF-treated). Mesenteric ischemia/reperfusion also damaged the lungs and kidneys and increased serum tumor necrosis factor-alpha levels (circulating cytokine activity marker). EGF pretreatment also reduced these changes. These studies provide preliminary evidence that EGF is a novel therapy for the early treatment or prevention of intestinal damage and multiorgan failure resulting from mesenteric hypoperfusion.

Attenuation of internal organ damages by exogenously administered epidermal growth factor (EGF) in burned rodents

Major burns are associated with multiple internal organ damages, including necrosis of the gastrointestinal mucosa. Failure of the intestinal barrier is a serious complication in burned patients. Epidermal growth factor (EGF) is a mitogenic polypeptide that stimulates wound repair and affords protection to the gastric mucosa. We examined whether a single systemic intervention with EGF prevents organ systems damages, following full-thickness scalds (25-30%) in rodents. Animals were randomly assigned to receive an intraperitoneal injection of EGF (30 microg/kg in mice, 10 microg/kg in rats) or saline solution, 30 min prior thermal injury in mice or after the cutaneous injury in rats. General clinical condition and mortality during 24h were recorded. Animals were autopsied and histopathological and histomorphometric studies were conducted. Mice treated with EGF exhibited a milder clinical evolution and acute lethality was significantly reduced as compared to saline counterparts (P<0.01). Histopathological and morphometric analysis showed that EGF significantly reduced intestinal necrosis and contributed to preserve jejunoileal architecture in mice (P<0.05) and rats (P<0.01). The onset of renal hemorrhagic foci was significantly reduced in EGF-treated groups (P<0.01). Lung damages appeared attenuated in EGF-treated animals. These data indicate the salutary effects of EGF by attenuating internal complications associated to thermal injuries. Further studies are warranted to fully elucidate the usefulness of this therapy.

Comparison of the antisecretory and antiulcer activity of epidermal growth factor, urogastrone and transforming growth factor alpha and its derivative in rodents in vivo

This study investigates the effects of epidermal growth factor (EGF), urogastrone (UG) and transforming growth factor-alpha (TGFalpha) and its derivative on dimaprit- and pentagastrin-induced gastric acid secretion and on acidified ethanol (AE)-evoked ulcer formation in anaesthetized rats. EGF, TGFalpha and UG administered subcutaneously (s.c.) 30 min before dimaprit inhibited gastric acid secretion. Against pentagastrin-stimulated secretion, TGFalpha inhibited, while EGF and UG potentiated, acid secretion dose-dependently. Intraduodenal (i.d.) administration of TGFalpha and UG had no effect, while EGF potentiated, both secretagogue-induced acid secretion in the same dosage schedule. Administration of either EGF, UG or TGFalpha i.v. bolus, in response to continuous infusion of dimaprit resulted in a significant (p < 0.05-p < 0.001) inhibition of acid secretion which was transient and returned to normal within 30-45 min for UG while it slowly returned to normal for EGF and TGFalpha. The truncated form of TGFa (amino acids 34-43) did not show any antisecretory effect when administered parenterally. Acidified ethanol produced gastric haemorrhagic lesions in the rat 1 h after oral administration. The gastric mucosal protective effects of TGFalpha, EGF and UG administered either orally or s.c. 30 min before the administration of AE were dose-dependent against this model of ulcer induction. Indomethacin (Indo), administered 15 min before AE to inhibit prostanoids biosynthesis, significantly (p < 0.001) reduced the cytoprotective effects of TGFalpha, EGF and UG and aggravated the ulcer index when administered s.c. The results show that PGs may be involved in mediating the protective effects of the three growth factors. Administration of NG-nitro-L argininemethylester (L-NAME) 15 min prior to TGFa, EGF and UG s.c. or orally, significantly (p < 0.001) decreased the degree of ulcer indices and was able to reduce the protective effects of TGFalpha, EGF and UG, thus including the role of NO in mediating the protective effects of these growth factors. In conclusion, these results have demonstrated that EGF, UG and TGFalpha have a short and reversible inhibitory effect on dimaprit-stimulated gastric acid secretion and each is effective parenterally but not orally. UG and EGF potentiated, while, TGFa inhibited pentagastrin-stimulated acid secretion. In addition, TGFalpha seems to lose its activity when it is truncated from the C terminus. The present study also suggests that EGF, UG and TGFalpha are equally effective against AE-induced gastric ulcer and bring about their cytoprotective action through their reduction of acid secretion and through PG and NO pathways.

EGF promotes gastric mucosal restitution by activating Na(+)/H(+) exchange of epithelial cells

This study was conducted to determine whether the contributions of epidermal growth factor (EGF) to gastric mucosal restitution after injury are mediated by stimulation of Na(+)/H(+) exchangers in surface mucous cells (SMC). Intact sheets of guinea pig gastric mucosae were incubated in vitro. Intracellular pH (pH(i)) in SMC was measured fluorometrically, using 2',7'- bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein. Restitution after Triton X-100-induced injury was evaluated by recovery of electrical resistance. At neutral luminal pH, exogenous EGF (ex-EGF) increased pH(i) and enhanced restitution in the absence but not in the presence of serosal HCO. During exposure to luminal acid, ex-EGF not only prevented intracellular acidosis but also promoted restitution. These effects of ex-EGF were blocked by serosal amiloride or anti-EGF-receptor antibody. In the absence of ex-EGF, restitution was inhibited by replacement of luminal and serosal solutions with fresh solutions and was blocked more completely by serosal anti-EGF-receptor antibody. These results suggest that both endogenous and ex-EGF contribute to restitution via basolateral EGF receptors, with effects mediated, at least in part, by stimulation of basolateral Na(+)/H(+) exchangers.

Growth factor regulation of enterocyte nutrient transport during intestinal adaptation

BACKGROUND

Intestinal adaptation occurs in response to injury or alteration in nutrient availability. It is both morphologic and physiologic in nature and can be mediated by growth factors and nutrients. Pathologic conditions such as short-bowel syndrome and inflammatory bowel disease lead to derangements in nutrient absorption that may exceed the body's regenerative and adaptive capacity. Failure to fully adapt often results in long-term dependence on parenteral nutrition, leading to decreased quality of life and excessive medical expenses. The therapeutic use of appropriate growth factors may increase the adaptive capabilities of the gut.

DATA SOURCE

Medline and current literature review.

CONCLUSIONS

The major known nutrient transporters present in the gut and the mechanisms by which growth factors alter transport activity during intestinal adaptation are summarized. Growth factors have the potential to improve nutrient absorption in some bowel diseases.

Comparison of the effects of concanavalin-A and epidermal growth factor on epithelial cell proliferation in the rat intestine

BACKGROUND

Concanavalin-A, the lectin present in Jack beans, binds to mannose- and glucose-containing residues and can interact with the epidermal growth factor receptor and moderate cell proliferation in vitro.

AIM

To compare the actions of concanavalin-A and epidermal growth factor on the gastrointestinal tract in vivo.

METHODS

Rats maintained on total parenteral nutrition were given intragastric concanavalin-A, intravenous epidermal growth factor or concanavalin-A and epidermal growth factor. Cell proliferation and crypt fission were assayed in 'micro-dissected' crypts.

RESULTS

Concanavalin-A and epidermal growth factor both significantly elevated proliferation in the small intestine and colon. No significant interaction between the effects of these two agents was seen, except in the mid small intestine where there was a synergistic interaction. Concanavalin-A had no effect on crypt branching. Epidermal growth factor significantly reduced branching in the distal small intestine and mid colon.

CONCLUSION

The effects of the two agents appeared to be separate, except in the mid small intestine where they were additive. This is in marked contrast with the actions reported in vitro, where concanavalin-A is a powerful inhibitor of epidermal growth factor-induced cell proliferation. Concanavalin-A thus has potential for enhancing the functions of the small intestine.

Microparticles for delivering therapeutic peptides and proteins to the lumen of the small intestine

Several different peptides and proteins, such as the pancreatic trypsin inhibitor, growth factors and trefoil peptides, are known to play important roles in maintaining the structure and function of the gastrointestinal wall. With the advent of recombinant biotechnology, it has become feasible to test some of these proteins as therapeutics in different inflammatory conditions of the intestines. However, the harsh pH and enzymatic conditions of the stomach can lead to their inactivation. This research was aimed at the development of particulate, gastric-resistant pharmaceutical forms, incorporating those bioactive molecules. Mixtures of proteins in powder form were coated with cellulose acetate phthalate, Eudragit S100 or Eudragit RS PO, using simple preparation techniques based on single emulsion/solvent evaporation. Using aprotinin as a model drug, it was found that these procedures were effective in microencapsulating protein in the solid form without affecting its biological activity. Furthermore, and in particular with the first two polymers above, particles showed adequate in vitro release patterns for the applications envisioned.

Epidermal growth factor increases surface hydrophobicity and resistance to acid in the rat duodenum

Epidermal growth factor (EGF) is produced in Brunner's glands and plays a role in healing and repair of duodenal ulcers. We examined the participation of zwitterionic phospholipids of mucus in the effects of EGF. Under anesthesia, groups of rats received an intraduodenal bolus of either saline or EGF. Some rats received subcutaneous indomethacin followed by EGF or EGF followed by a detergent (5% Brij 35, a nonionic detergent that solubilizes luminal phospholipids). Thirty minutes after treatment, mucosal surface hydrophobicity and phospholipid concentration in the mucus layer were measured. Matched groups of rats were challenged with 0.5 M HCl, instilled intraduodenally 30 min after treatment, and mucosal damage was assessed 1 h after acid challenge. Exogenous EGF significantly increased surface hydrophobicity and phosphatidylcholine concentration in the mucus layer. EGF treatment also reduced mucosal damage induced by acid. However, indomethacin pretreatment or detergent administration after EGF abolished both protection against acid and changes in the mucus layer. These data suggest that EGF increases duodenal resistance to luminal acid via stimulation of mucosal zwitterionic phospholipids.