Effect of epidermal growth factor on ontogeny of the gastrointestinal tract

A review on the safety of growth factors commonly used in cultivated meat production

Growth factors are commonly added to cell culture media in cellular agriculture to mimic the endogenous process of proliferation and differentiation of cells. Many of these growth factors are endogenous to humans and known to be present in the edible tissues and milk of food animals. However, there is little or no information on the use of growth factors intentionally added in food production before the advent of cultivated meat. Ten commonly used growth factors have been reviewed to include information on their mode of action, bioavailability, occurrence in food and food animals, endogenous levels in humans, as well as exposure and toxicological information drawn from relevant animal studies and human clinical trials with a focus on oral exposure. In addition, a comparison of homology of growth factors was done to compare the sequence homology of growth factors from humans and domestic animal species commonly consumed as food, such as bovine, porcine, and poultry. This information has been gathered as the starting point to determine the safety of use of growth factors in cultivated meat meant for human consumption. The change in levels of growth factors measured in human milk and bovine milk after pasteurization and high-temperature treatment is discussed to give an indication of how commercial food processing can affect the levels of growth factors in food. The concept of substantial equivalence is also discussed together with a conservative exposure estimation. More work on how to integrate in silico assessments into the routine safety assessment of growth factors is needed.

The Effects of Maternal Smoking on Pregnancy and Offspring: Possible Role for EGF?

Cigarette smoke exposure during pregnancy and lactation is associated with adverse pregnancy outcomes. Here, we investigated the effects of maternal smoke exposure on pregnancy and offspring immunity and explored whether, epidermal growth factor (EGF), an important growth-promoting factor in human colostrum and milk, might be a possible missing link in maternal smoke exposure and changes in infants’ immune responses. Pregnant BALB/c mice were exposed to either cigarette smoke or air during gestation and lactation, and effects on pulmonary inflammation in dams and immune responses in offspring were examined. Maternal smoke exposure increased airway hyperresponsiveness and accumulation of inflammatory cells in the lungs of pregnant dams compared to non-pregnant dams. The E-cadherin protein expression was reduced in mammary glands of cigarette smoke-exposed pregnant dams. EGF levels were higher in mammary glands and serum of smoke-exposed pregnant dams compared to air-exposed pregnant dams. Offspring from cigarette smoke-exposed dams exhibited elevated levels of IL-17A, MCP-1, IL-22, and IL-13 in anti-CD3 stimulated spleen cell culture supernatants. EGF levels were also increased in serum of offspring from smoke-exposed dams. A positive correlation was observed between serum EGF levels and neutrophil numbers in bronchoalveolar lavage fluid of the dams. Interestingly, IL-17A, MCP-1, IL-22, IL13, and IFN-γ levels in anti-CD3 stimulated spleen cell culture supernatants of male pups also showed a positive correlation with EGF serum levels. In summary, our results reveal that maternal smoke exposure predisposes dams to exacerbated airway inflammation and offspring to exacerbated immune responses and both phenomena are associated with elevated EGF concentrations.

Expression and Function of the Epidermal Growth Factor Receptor in Physiology and Disease

The epidermal growth factor receptor (EGFR) is the prototypical member of a family of membrane-associated intrinsic tyrosine kinase receptors, the ErbB family. EGFR is activated by multiple ligands, including EGF, transforming growth factor (TGF)-α, HB-EGF, betacellulin, amphiregulin, epiregulin, and epigen. EGFR is expressed in multiple organs and plays important roles in proliferation, survival, and differentiation in both development and normal physiology, as well as in pathophysiological conditions. In addition, EGFR transactivation underlies some important biologic consequences in response to many G protein-coupled receptor (GPCR) agonists. Aberrant EGFR activation is a significant factor in development and progression of multiple cancers, which has led to development of mechanism-based therapies with specific receptor antibodies and tyrosine kinase inhibitors. This review highlights the current knowledge about mechanisms and roles of EGFR in physiology and disease.

Dynamic change of epidermal growth factor in neonatal rat with intestine injury

AIM: To determine whether diminished levels of epidermal growth factor (EGF) were present in neo-natal rats with intestinal injury and related with the degree of intestinal injury, so we modeled a model in neo-natal rats of intestinal injury and to examine the dynamic levels of EGF on injury of intestine.

METHODS: One-day-old Wistar rat pups received an intraperitoneally injection with 4 mg/kg lipopolysaccharide (LPS), followed by collection of ileum tissue at 1, 3, 6, 12, and 24 h following LPS administration. The ileum was for histological evaluation of NEC and for measurements of EGF using ABC-ELISA. The correlation between the degree of intestinal injury and levels of EGF was determined.

RESULTS: The LPS-injected pups also showed a significant increase in injury scores at 1, 3, 6, 12, and 24 h [respectively, (1.08±0.61), (1.63±0.84), (1.95±0.72), (2.42±0.43) and (2.21±0.53)] vs the control (0.12±0.17) (P<0.01). EGF levels at 1, 3, 6, 12 h [respectively, (245.6±49.0), (221.4±39.0), (223.4±48.1), (246.0±46.6)] pg/mg were significantly loss than the control (275.6±50.4) pg/mg (P<0.05). There was a significant negative correlation between the EGF levels and the grade of intestinal injury within 24 h (P<0.05).

CONCLUSION: Neo-natal rats with intestinal injury have significantly lower levels of ileum EGF. Reduced levels of this growth factor might be related to the pathogenesis of NEC.

Increased epidermal growth factor levels in human milk of mothers with extremely premature infants

Maternal milk is the major source of nutrients and growth-promoting substances in the first weeks of life for the majority of neonates. Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are trophic peptides present in human milk with significant healing effects on injured gastrointestinal mucosa. Decreasing gestational age of neonates is associated with higher risk of developing gastrointestinal disorders, and human milk provides better protection against these diseases compared with formula. The aim of this study was to evaluate the concentrations of EGF and TGF-alpha in human milk collected from mothers with infants born: extremely preterm, preterm, and full term. Milk samples were collected at the end of first, second, and fourth week postpartum from each mother of infants born in one of the three gestational age groups: extremely preterm (23-27 wk, n = 16), preterm (32-36 wk, n = 16), and full term (38-42 wk, n = 15). Milk concentrations of EGF and TGF-alpha were quantified with a homologous RIA in the milk aqueous fraction. Concentrations of EGF in human milk from the extremely preterm group (23-27 wk) were significantly higher compared with values from the preterm and full-term groups throughout the first month of lactation. A similar pattern was observed with human milk TGF-alpha; however, milk TGF-alpha levels were lower than EGF. In conclusion, we have found higher concentrations of EGF and TGF-alpha in human milk of mothers with extremely preterm babies. These data may indicate the potential importance of milk-borne EGF and TGF-alpha for the development of extremely premature infants.

Epidermal growth factor reduces the development of necrotizing enterocolitis in a neonatal rat model

Necrotizing enterocolitis (NEC) is the most common gastrointestinal disease of prematurely born infants. Maternal milk plays an important protective role against NEC development and is the major source of epidermal growth factor (EGF) for neonates. The aim of this study was to examine the effect of orally administered EGF on the incidence of NEC in a neonatal rat model. Newborn rats were artificially fed either with growth factor-free rat milk substitute (RMS) or RMS supplemented with 500 ng/ml of EGF (RMS+EGF). Experimental NEC was induced by exposure to asphyxia and cold stress. Development of NEC was evaluated by gross and histological scoring of damage in the ileum. Ileal EGF receptor (EGF-R), EGF, and transforming growth factor-alpha mRNA expression was assessed by RT competitive-PCR, and the EGF-R was localized by immunohistochemistry. EGF supplementation of formula reduced the incidence and severity of NEC in rats (13/16 RMS vs. 4/13 RMS+EGF). Ileal EGF-R mRNA expression was markedly increased in the RMS group compared with RMS+EGF. Enhanced EGF-R expression in the RMS group was localized predominantly in the epithelial cells of injured ileum. These data suggest a new potential therapeutic approach for the prevention and treatment of NEC.

Release and binding of epidermal growth factor in the pancreas of rats

Previous studies showed that EGF is produced by salivary and duodenal glands and released in saliva and duodenal secretion. Using specific radioimmunoassay of EGF, this study showed that the salivary glands and duodenal mucosa contain high levels of EGF, reaching, respectively, about 38 and 4 micrograms/g of tissue weight. EGF immunoreactivity was also found in high amounts in the pancreatic tissue (20 micrograms/g) and the pancreatic juice (32 ng/mL), where the content of EGF was found to increase in response to feeding, cholecystokinin, or bombesin and to decrease after the administration of atropine and somatostatin. Studies on the binding of EGF revealed that pancreatic acinar membranes possess the specific and saturable EGF receptors with a high affinity sites with Kd of about 4.3 nM and binding capacity of about 62 fmol/mg of protein, and with low affinity sites with Kd of 21 nM and binding capacity of about 180 fmol/mg of protein. The observed high content of immunoreactive EGF in the pancreatic tissue and the presence of high and low affinity binding sites for EGF in the pancreatic acinar membranes, as well as the high EGF output in the pancreatic juice and its alterations in response to hormonal and postprandial stimulation, suggest an important role of EGF in pancreatic physiology.

Distribution, release, and secretory activity of epidermal growth factor in the pancreas

This study was designed to determine the distribution of immunoreactive epidermal growth factor (EGF) in the gastrointestinal tract and the action of this peptide on pancreatic secretion in vivo and in vitro. Immunoreactive EGF was found in large amounts in the salivary glands and the pancreas and in the pancreatic juice. EGF infused subcutaneously (50 micrograms/kg-h) in conscious rats with intact or removed salivary glands stimulated pancreatic protein secretion after 4 h of peptide infusion; this effect was completely prevented by the pretreatment with DL-difluoromethyl-ornithine (DFMO) (200 mg/kg), an irreversible inhibitor of activity of ornithine decarboxylase (ODC), a key enzyme in polyamine synthesis. EGF added to the incubation medium in concentrations ranging from 10(-10)-10(-6) M increased, in a concentration-dependent manner both unstimulated and stimulated by caeruelin or urecholine, amylase release from dispersed pancreatic acini obtained from rats pretreated in 3 h with EGF in a dose of 50 micrograms/kg-h. Spermine given at concentrations ranging from 10(-12)-10(-6) M to the freshly prepared rat pancreatic acini also increased amylase release in a concentration-related manner. DFMO injected in a single dose (200 mg/kg), before the infusion of EGF to the rats, completely abolished the stimulatory effect of EGF on amylase release, but failed to affect that of spermine. This study shows that 1. EGF is present in large amounts in pancreatic tissue and pancreatic juice. 2. EGF stimulates pancreatic secretion in vivo and amylase release in vitro from isolated rat pancreatic acini. 3. The activation of ODC and polyamine biosynthesis in acinar cells plays an important role in EGF-induced stimulation of pancreatic secretion.

Immunohistochemical localisation and developmental aspects of epidermal growth factor in the rat

The tissue localisation and time of first appearance of Epidermal Growth Factor (EGF) in the developing rat were investigated by means of immunohistochemistry, radioimmunoassay and radioreceptor assay. In this study we were able to show, that EGF appears prenatally in the lung and the kidney from gestational day 19. Postnatally EGF was found also in the gastrointestinal tract, first in Brunner's glands of the duodenum (at birth), next in the Paneth cells (day 7), and finally in the submandibular glands (day 25). The immunohistochemical and radioreceptor results are consistent, whereas the radioimmunoassay detects EGF later and in smaller quantities, than does the radioreceptor assay. These differences will be discussed.