The role of epidermal growth factor (EGF) and its receptor in mucosal protection, adaptation to injury, and ulcer healing: involvement of EGF-R signal transduction pathways

Xiaoer-Feire-Qing granules alleviate pyretic pulmonary syndrome induced by Streptococcus pneumoniae in young rats by affecting the lungs and intestines: An in vivo study based on network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) Xiaoer-Feire-Qing granules (XEFRQ) has been used to treat pyretic pulmonary syndrome (PPS) in children for many years. The function of the lungs is considered to be closely related to the large intestine in TCM.

PURPOSE

We aimed to investigate the effects of XEFRQ on PPS and the underlying mechanisms via network pharmacology and animal experiments.

METHODS

The TCMSP platform was used to identify the ingredients and potential targets of XEFRQ. The GeneCards, OMIM, and TTD databases were used to predict PPS-associated targets. Cytoscape 3.9.1 was employed to construct the protein-protein interaction network, and target prediction was performed by GO and KEGG analyses. For the animal experiment, a PPS model was constructed by three cycles of nasal drip of Streptococcus pneumoniae (STP; 0.5 mL/kg). The animals were randomly divided into the following four groups according to their weight (n = 10 rats per group): the blank group, the model group, the XEFRQ-L (16.3 g/kg) group, and the XEFRQ-H (56.6 g/kg) group. Rats in the blank group and the model group were given 0.5% CMC-Na by gavage. The general conditions of the rats were observed, and their food-intake, body weight, and body temperature were recorded for 14 days. After the intervention of 14 days, serum was collected to detect inflammatory cytokines (TNF-α, IL-1β, and PGE2) and neurotransmitters (5-HT, SP, and VIP). H&E staining was used to observe the pathological morphology of lung and colon tissue. AQP3 expression was detected by Western blot. In addition, the gut microbiota in cecal content samples were analyzed by 16S rDNA high-throughput sequencing.

RESULTS

Our network analysis revealed that XEFRQ may alleviate PPS injury by affecting the levels of inflammatory cytokines and neurotransmitters and mitigating STP-induced PPS.In vivo validation experiments revealed that XEFRQ improved STP-induced PPS and reduced the expression of inflammatory cytokines and neurotransmitters. Notably, XEFRQ significantly decreased the protein expression levels of AQP3, which was associated with dry stool. Our gut microbiota analysis revealed that the relative abundance of [Eubacterium]_ruminantium_group, Colidextribacter, Romboutsia, and Oscillibacter was decreased, which means XEFRQ exerts therapeutic effects against PPS associated with these bacteria.

CONCLUSION

Our results demonstrate that XEFRQ alleviates PPS by affecting the lungs and intestines, further guiding its clinical application.

Chemical components and protective effects of Atractylodes japonica Koidz. ex Kitam against acetic acid-induced gastric ulcer in rats

BACKGROUND

Atractylodes japonica Koidz. ex Kitam. (A. japonica, Chinese name: Guan-Cangzhu, Japanese name: Byaku-jutsu), a perennial herb, which is mainly distributed in northeast area of China, it’s often used to treat digestive system diseases such as gastric ulcer (GU). However, the mechanism of its potential protective effects against GU remains unclear.

AIM

To investigate the protective effects of A. japonica on acetic acid-induced GU rats.

METHODS

The chemical constituents of A. japonica were determined by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analysis. The rat model of GU was simulated by acetic acid method. The pathological changes of gastric tissues were evaluated by hematoxylin-eosin stain, the levels of epidermal growth factor (EGF), EGF receptor (EGFR), nuclear factor kappa-B (NF-κB), interleukin-1β (IL-1β), IL-10, Na⁺-K⁺-ATPase (NKA) in serum and gastric tissues were determined by enzyme-linked immunosorbent assay, and the mRNA expressions of EGFR, NF-κBp65, IkappaBalpha (IκBα) and Zonula Occludens-1 (ZO-1) in gastric tissues were determined by real-time reverse transcription polymerase chain reaction, and the efficacy was observed. Then, plasma metabolomic analysis was performed by UPLC-MS/MS to screen the specific potential biomarkers, metabolic pathways and to explore the possible mechanisms.

RESULTS

48 chemical constituents were identified. Many of them have strong pharmacological activity, the results also revealed that A. japonica significantly improved the pathological damage of gastric tissues, increased the expression levels of IL-10, IκBα related to anti-inflammatory factors, decreased the expression levels of IL-1β, NF-κB, NF-κBp65, related to proinflammatory factors, restored the levels of factors about EGF, EGFR, ZO-1 associated with ulcer healing and the levels of factors about NKA associated with energy metabolism. Metabolomic analysis identified 10 potential differential metabolites and enriched 7 related metabolic pathways.

CONCLUSION

These findings contribute to the understanding of the potential mechanism of A. japonica to improve acetic acid-induced GU, and will be of great importance for the development and clinical application of natural drugs related to A. japonica.

A comparative metabolomics study between grain-sized moxibustion and suspended moxibustion on rats with gastric ulcers

Grain-sized moxibustion (GS-Moxi) and suspended moxibustion (S-Moxi) represent the two typical local heat therapies in Traditional Chinese Medicine (TCM) and have been extensively used in treating gastric ulcers (GU) in China. However, the difference in biological response between the two moxibustion therapies in treating GU remains unclear. Here we investigated the therapeutic effect and potential mechanistic difference underlying the two moxibustion methods. Ethanol-induced GU model was established and was treated with GS-Moxi or S-Moxi at ST36 and ST21 for 5 days separately. And then, gastric histopathological examination, immunohistochemical staining for repair factors (EGFR, VEGF, Ki67), and 1H NMR-based metabolomics analysis of plasma and stomach of rats were conducted. We found GS-Moxi and S-Moxi effectively alleviated gastric damage and significantly increased the expression of related repair factors. However, S-Moxi corrected aberrant energy metabolism and lipids metabolism in GU rats but had little effect on neurotransmitter-related metabolism, while GS-Moxi regulated energy metabolism and neurotransmitter-related metabolism in GU rats but had no effect on lipids metabolism. We further proposed that the main target of S-Moxi may be liver and vasculature, whereas GS-Moxi specially targeted the stomach via regulating nervous system. This study strongly verified the outstanding gastroprotective effects of moxibustion and enriched our understanding of the varied biological responses triggered by different moxibustion methods.

Lack of Association between Epidermal Growth Factor or Its Receptor and Reflux Esophagitis, Barrett’s Esophagus, and Esophageal Adenocarcinoma: A Case-Control Study

The epidermal growth factor (EGF) and its receptor (EGFR) gene-gene interactions were shown to increase the susceptibility to esophageal cancer. However, the role of the EGF/EGFR pathway in the development of gastroesophageal reflux disease (GERD) and its complications (reflux esophagitis (RE), Barrett's esophagus (BE), and esophageal adenocarcinoma (EAC)) remains unclear. This association study is aimed at investigating functional EGF and EGFR gene polymorphisms, their mRNA expression in esophageal tissues, and EGF plasma levels in relation to RE, BE, and EAC development in the Central European population. 301 patients with RE/BE/EAC (cases) as well as 98 patients with nonerosive reflux disease (NERD) and 8 healthy individuals (controls) were genotyped for +61 A>G EGF (rs4444903) and +142285 G>A EGFR (rs2227983) polymorphisms using the TaqMan quantitative polymerase chain reaction (qPCR). In random subgroups, the EGF and EGFR mRNA expressions were analyzed by reverse transcription qPCR in esophageal tissue with and without endoscopically visible pathological changes; and the EGF plasma levels were determined by enzyme-linked immunosorbent assay. None of the genotyped SNPs nor EGF-EGFR genotype interactions were associated with RE, BE, or EAC development (p > 0.05). Moreover, mRNA expression of neither EGF nor EGFR differed between samples of the esophageal tissue with and without endoscopically visible pathology (p > 0.05) nor between samples from patients with different diagnoses, i.e., RE, BE, or EAC (p > 0.05). Nevertheless, the lower EGF mRNA expression in carriers of combined genotypes AA +61 EGF (rs4444903) and GG +142285 EGFR (rs2227983; p < 0.05) suggests a possible direct/indirect effect of EGF-EGFR gene interactions on EGF gene expression. In conclusion, EGF and EGFR gene variants and their mRNA/protein expression were not associated with RE, BE or EAC development in the Central European population.

Gut homeostasis, injury, and healing: New therapeutic targets

The integrity of the gastrointestinal mucosa plays a crucial role in gut homeostasis, which depends upon the balance between mucosal injury by destructive factors and healing via protective factors. The persistence of noxious agents such as acid, pepsin, nonsteroidal anti-inflammatory drugs, or Helicobacter pylori breaks down the mucosal barrier and injury occurs. Depending upon the size and site of the wound, it is healed by complex and overlapping processes involving membrane resealing, cell spreading, purse-string contraction, restitution, differentiation, angiogenesis, and vasculogenesis, each modulated by extracellular regulators. Unfortunately, the gut does not always heal, leading to such pathology as peptic ulcers or inflammatory bowel disease. Currently available therapeutics such as proton pump inhibitors, histamine-2 receptor antagonists, sucralfate, 5-aminosalicylate, antibiotics, corticosteroids, and immunosuppressants all attempt to minimize or reduce injury to the gastrointestinal tract. More recent studies have focused on improving mucosal defense or directly promoting mucosal repair. Many investigations have sought to enhance mucosal defense by stimulating mucus secretion, mucosal blood flow, or tight junction function. Conversely, new attempts to directly promote mucosal repair target proteins that modulate cytoskeleton dynamics such as tubulin, talin, Ehm2, filamin-a, gelsolin, and flightless I or that proteins regulate focal adhesions dynamics such as focal adhesion kinase. This article summarizes the pathobiology of gastrointestinal mucosal healing and reviews potential new therapeutic targets.

The Critical Role of Growth Factors in Gastric Ulcer Healing: The Cellular and Molecular Mechanisms and Potential Clinical Implications

In this article we review the cellular and molecular mechanisms of gastric ulcer healing. A gastric ulcer (GU) is a deep defect in the gastric wall penetrating through the entire mucosa and the muscularis mucosae. GU healing is a regeneration process that encompasses cell dedifferentiation, proliferation, migration, re-epithelialization, formation of granulation tissue, angiogenesis, vasculogenesis, interactions between various cells and the matrix, and tissue remodeling, all resulting in scar formation. All these events are controlled by cytokines and growth factors (e.g., EGF, TGFα, IGF-1, HGF, bFGF, TGFβ, NGF, VEGF, angiopoietins) and transcription factors activated by tissue injury. These growth factors bind to their receptors and trigger cell proliferation, migration, and survival pathways through Ras, MAPK, PI3K/Akt, PLC-γ, and Rho/Rac/actin signaling. The triggers for the activation of these growth factors are tissue injury and hypoxia. EGF, its receptor, IGF-1, HGF, and COX-2 are important for epithelial cell proliferation, migration, re-epithelialization, and gastric gland reconstruction. VEGF, angiopoietins, bFGF, and NGF are crucial for blood vessel regeneration in GU scars. The serum response factor (SRF) is essential for VEGF-induced angiogenesis, re-epithelialization, and blood vessel and muscle restoration. Local therapy with cDNA of human recombinant VEGF165 in combination with angiopoietin1, or with the NGF protein, dramatically accelerates GU healing and improves the quality of mucosal restoration within ulcer scars. The future directions for accelerating and improving healing include local gene and protein therapies with growth factors, their combinations, and the use of stem cells and tissue engineering.

Ginsenoside Rb1 promotes intestinal epithelial wound healing through extracellular signal-regulated kinase and Rho signaling

BACKGROUND AND AIM

Daikenchuto, a traditional Japanese herbal medicine, has been reported to exhibit anti-inflammatory effects against intestinal inflammation. However, whether daikenchuto has a therapeutic effect against intestinal mucosal injuries remains unclear. Thus, the aim of this study was to determine the effect of daikenchuto on intestinal mucosal healing.

METHODS

Colitis was induced in male Wistar rats by using trinitrobenzenesulfonic acid. Daikenchuto (900 mg/kg/day) was administered for 7 days after the induction of colitis. Thereafter, intestinal mucosal injuries were evaluated by determining the colonic epithelial regeneration ratio ([area of epithelial regeneration/area of ulcer] × 100). Restoration of rat intestinal epithelial cells treated with daikenchuto and its constituent herbs (Zanthoxylum fruit, processed ginger, and ginseng) and ginsenoside Rb1, which is a ginseng ingredient, was evaluated using a wound-healing assay.

RESULTS

The colon epithelial regeneration ratio in the daikenchuto-treated rats was significantly higher than that in the control rats. Daikenchuto, ginseng, and ginsenoside Rb1 enhanced wound healing, and the ginsenoside Rb1-induced enhancement was inhibited by extracellular signal-regulated kinase and Rho inhibitors.

CONCLUSIONS

Daikenchuto and its constituent, ginsenoside Rb1, promoted wound healing. Because mucosal healing is one of the most important therapeutic targets in patients with inflammatory bowel disease, ginsenoside Rb1 may be a novel therapeutic agent against intestinal mucosal damage such as that occurring in intestinal bowel disease.

Trefoil factor 2 activation of CXCR4 requires calcium mobilization to drive epithelial repair in gastric organoids

KEY POINTS

Determining the signalling cascade of epithelial repair, using murine gastric organoids, allows definition of regulatory processes intrinsic to epithelial cells, at the same time as validating and dissecting the signalling cascade with more precision than is possible in vivo Following single cell damage, intracellular calcium selectively increases within cells adjacent to the damage site and is essential for promoting repair. Trefoil factor 2 (TFF2) acts via chemokine C-X-C receptor 4 and epidermal growth factor receptor signalling, including extracellular signal-regulated kinase activation, to drive calcium mobilization and promote gastric repair. Sodium hydrogen exchanger 2, although essential for repair, acts downstream of TFF2 and calcium mobilization.

ABSTRACT

The gastric mucosa of the stomach is continually exposed to environmental and physiological stress factors that can cause local epithelial damage. Although much is known about the complex nature of gastric wound repair, the stepwise process that characterizes epithelial restitution remains poorly defined. The present study aimed to determine the effectors that drive gastric epithelial repair using a reductionist culture model. To determine the role of trefoil factor 2 (TFF2) and intracellular calcium (Ca2+ ) mobilization in gastric restitution, gastric organoids were derived from TFF2 knockout (KO) mice and yellow Cameleon-Nano15 (fluorescent calcium reporter) transgenic mice, respectively. Inhibitors and recombinant protein were used to determine the upstream and downstream effectors of gastric restitution following photodamage (PD) to single cells within the gastric organoids. Single cell PD resulted in parallel events of dead cell exfoliation and migration of intact neighbouring cells to restore a continuous epithelium in the damage site. Under normal conditions following PD, Ca2+ levels increased within neighbour migrating cells, peaking at ∼1 min, suggesting localized Ca2+ mobilization at the site of cell protrusion/migration. TFF2 KO organoids exhibit delayed repair; however, this delay can be rescued by the addition of exogenous TFF2. Inhibition of epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK)1/2 or a TFF2 receptor, chemokine C-X-C receptor 4 (CXCR4), resulted in significant delay and dampened Ca2+ mobilization. Inhibition of sodium hydrogen exchanger 2 (NHE2) caused significant delay but did not affect Ca2+ mobilization. A similar delay was observed in NHE2 KO organoids. In TFF2 KO gastric organoids, the addition of exogenous TFF2 in the presence of EGFR or CXCR4 inhibition was unable to rescue repair. The present study demonstrates that intracellular Ca2+ mobilization occurs within gastric epithelial cells adjacent to the damage site to promote repair by mechanisms that involve TFF2 signalling via CXCR4, as well as activation of EGFR and ERK1/2. Furthermore NHE2 is shown to be important for efficient repair and to operate via a mechanism either downstream or independent of calcium mobilization.

Sex-specific effects of Eugenia punicifolia extract on gastric ulcer healing in rats

AIM

To evaluate the sex-specific effects of a hydroalcoholic extract from Eugenia punicifolia (HEEP) leaves on gastric ulcer healing.

METHODS

In this rat study involving males, intact (cycling) females, and ovariectomized females, gastric ulcers were induced using acetic acid. A vehicle, lansoprazole, or HEEP was administered for 14 d after ulcer induction. Body weight was monitored throughout the treatment period. At the end of treatment, the rats were euthanized and the following in vivo and in vitro investigations were performed: macroscopic examination of the lesion area and organ weights, biochemical analysis, zymography, and evaluation of protein expression levels. Additionally, the concentration-dependent effect of HEEP was evaluated in terms of subacute toxicity and cytotoxicity.

RESULTS

Compared to the vehicle, HEEP demonstrated a great healing capacity by substantially reducing the ulcerative lesion area in males (52.44%), intact females (85.22%), and ovariectomized females (65.47%), confirming that HEEP accelerates the healing of acetic acid-induced gastric lesions and suggesting that this effect is modulated by female sex hormones. The antiulcer effect of HEEP was mediated by prostaglandin E₂ only in male rats. Overall, the beneficial effect of HEEP was the highest in intact females. Notably, HEEP promoted the expression of vascular endothelial growth factor (intact vs ovariectomized females) and decreased the expression of Caspase-8 and Bcl-2 (intact female vs male or ovariectomized female). Additionally, HEEP enhanced fibroblast proliferation and migration into a wounded area in vitro, confirming its healing effect. Finally, no sign of subacute toxicity or cytotoxicity of HEEP was observed.

CONCLUSION

In gastric ulcers, HEEP-induced healing (modulated by female sex hormones; in males, mediated by prostaglandin) involves extracellular matrix remodeling, with gastric mucosa cell proliferation and migration.

Oral mucositis associated with anti-EGFR therapy in colorectal cancer: single institutional retrospective cohort study

Background

Chemotherapy-induced oral mucositis impairs the quality of life. The difference in severity of oral mucositis between different anti-epidermal growth factor receptor (EGFR) antibodies combined with cytotoxic drugs in colorectal cancer is unclear. The aim of this study was to investigate the differences in oral mucositis between panitumumab (Pmab) and cetuximab (Cmab) combined with 5-fluorouracil (5-FU).

Methods

We conducted a retrospective cohort study. A total of 75 colorectal cancer outpatients treated with an anti-EGFR antibody combined with FOLFOX, FOLFIRI, or 5-FU/leucovorin as the first- to third-line treatment were included. The primary endpoint was the incidence of grade 2–3 oral mucositis. The secondary endpoint was the time to onset of oral mucositis. We also compared the incidence of toxicities of interest, skin toxicity, hypomagnesaemia and neutropenia, and time to treatment failure (TTF) between the two groups.

Results

Thirty-two patients treated with Pmab and 43 patients treated with Cmab were evaluated. Patient characteristics were similar between the two groups. The incidence of grade 2–3 oral mucositis was significantly higher with Pmab than with Cmab (31.3% vs 9.3%, P < 0.05). Moreover, the incidence of grade 3 oral mucositis was significantly higher in patients treated with Pmab (18.8% vs 0%, P < 0.01). The mean (SD) cycles to onset of the worst oral mucositis was 3.0 (2.9) in the Pmab group and 2.3 (1.7) in the Cmab group (P = 0.29). Oral mucositis was characterized by glossitis and cheilitis. The incidences of other toxicities were the following (Pmab vs Cmab): grade 2–3 skin toxicity: 68.8% vs 74.4% (P = 0.61), grade 2–3 hypomagnesaemia: 9.3% vs 7.0% (P = 1.00), grade 3–4 neutropenia: 28.1% vs 37.2% (P = 0.46). The median TTF was not significantly different, i.e., 223 days vs 200 days (P = 0.39) for Pmab vs Cmab.

Conclusions

Pmab-based chemotherapy resulted in significantly higher grades of oral mucositis compared with Cmab-based chemotherapy. The oral condition should be monitored carefully and early supportive care should be provided for patients treated with Pmab-based chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4862-z) contains supplementary material, which is available to authorized users.

Challenges in the local delivery of peptides and proteins for oral mucositis management

Oral mucositis, a common inflammatory side effect of oncological treatments, is a disorder of the oral mucosa that can cause painful ulcerations, local motor disabilities, and an increased risk of infections. Due to the discomfort it produces and the associated health risks, it can lead to cancer treatment restrains, such as the need for dose reduction, cycle delays or abandonment. Current mucositis management has low efficiency in prevention and treatment. A topical drug application for a local action can be a more effective approach than systemic routes when addressing oral cavity pathologies. Local delivery of growth factors, antibodies, and anti-inflammatory cytokines have shown promising results. However, due to the peptide and protein nature of these novel agents, and the several anatomic, physiological and environmental challenges of the oral cavity, their local action might be limited when using traditional delivering systems. This review is an awareness of the issues and strategies in the local delivery of macromolecules for the management of oral mucositis.

Aspirin-Induced Gastric Lesions Alters EGFR and PECAM-1 Immunoreactivity in Wistar Rats: Modulatory Action of Flavonoid Fraction of Musa Paradisiaca

AIM

In this study, Epithelial Growth Factor Receptor and Platelet Endothelial Cell Adhesion Molecule-1 were localised to investigate the healing effects of a flavonoid-rich fraction of M. paradisiaca fruit in the gastric corpus of Wistar rats following aspirin-induced gastric lesion.

MATERIALS AND METHODS

Mature, unripe fruits of M. paradisiaca were peeled; air dried, pulverised, extracted with 70% methanol, concentrated and partitioned. Ninety male Wistar rats were randomly assigned into 6 groups of 15 rats each. The gastric lesion was induced in groups B, C, D, E and F rats by administration of 400 mg/kg aspirin in distilled water. Group A received distilled water. After 24 hours, flavonoid fraction of M. paradisiaca was administered to groups C, D and E at 100, 200 and 400 mg/kg respectively for 21 days. Group F rats received omeprazole at 1.8 mg/kg for 21 days. Five rats from each group were anaesthetized with ketamine on days 14, 21 and 28. Gastric tissues were excised and fixed in Neutral buffered formalin. This was followed by paraffin wax embedding method and sections stained with haematoxylin and eosin and for immunolocalisation of EGFR and PECAM-1. Data were analysed using descriptive and inferential statistics.

RESULTS

There was a significant difference in the ulcer index in the corpus of control and treated rats throughout the experimental period (p = 0.0001). H&E stained sections showed a gradual restoration of the epithelial lining in the treated groups. Immunohistochemical examination showed that M. paradisiaca significantly increased (p < 0.05) reactivity for both EGFR and CD31 across the treatment groups.

CONCLUSION

The efficacy of Musa paradisiaca in attenuating the damaging effects of aspirin on the gastric mucosa was observed as there was a significantly increased reactivity for EGFR and PECAM-1 in the gastric corpus in a dose-dependent manner.

Salivary epidermal growth factor correlates with hospitalization length in rotavirus infection

BACKGROUND

The IFI27 interferon gene expression has been found to be largely increased in rotavirus (RV)-infected patients. IFI27 gene encodes for a protein of unknown function, very recently linked to epidermal proliferation and related to the epidermal growth factor (EGF) protein. The EGF is a low-molecular-weight polypeptide that is mainly produced by submandibular and parotid glands, and it plays an important physiological role in the maintenance of oro-esophageal and gastric tissue integrity. Our aim was to determine salivary EGF levels in RV-infected patients in order to establish its potential relationship with IFI27 increased expression and EGF-mediated mucosal protection in RV infection.

METHODS

We conducted a prospective comparative study using saliva samples from 27 infants infected with RV (sampled at recruitment during hospital admission and at convalescence, i.e. at least 3 months after recovery) and from 36 healthy control children.

RESULTS

Median (SD) EGF salivary concentration was 777 (529) pg/ml in RV-infected group at acute phase and 356 (242) pg/m at convalescence, while it was 337 (119) pg/ml in the healthy control group. A significant association was found between EGF levels and hospitalization length of stay (P-value = 0.022; r2 = -0.63).

CONCLUSIONS

The salivary levels of EGF are significantly increased during the acute phase of natural RV infection, and relate to length of hospitalization. Further assessment of this non-invasive biomarker in RV disease is warranted.

Long-term influence of sialoadenectomy on the liver of male albino rat

Epidermal growth factor is an endocrine product of the submandibular gland; the liver is an important target of its action and is affected by sialoadenectomy. Thirty rats were used in this study and divided into group I (sham-operated animals), group II (sialoadenectomy after 4 weeks), and group III (sialoadenectomy after 10 weeks). Liver samples were processed for light and electron microscope examination. Sialoadenectomy induced mild-to-moderate liver damage which persists up to 10 weeks after the operation. This damage is manifested morphologically rather than functionally, affecting the general structure, hepatocytes, hepatic stellate cells, and hepatic sinusoids.

Partially hydrolyzed guar gum enhances colonic epithelial wound healing via activation of RhoA and ERK1/2

BACKGROUND AND AIMS

Healing of the intestinal mucosal epithelium was found to be a critical factor in the treatment of inflammatory bowel disease (IBD). In this study, we provide further evidence that partially hydrolyzed dietary fiber (PHGG) enhances colonic epithelial cell wound healing, and partially characterize the mechanism that governs this process.

MATERIALS AND METHODS

Young adult mouse colonic (YAMC) epithelial cells were scraped with a 10 μl micro-pipette tip to denude a round of the monolayer and were incubated with PHGG. The area of cell migration was measured using Image J software. Meanwhile, Rho activation assays were utilized to monitor Rho activation levels. To assess in vivo effects, C57B6 mice were treated with DSS for 7 days and then provided food supplemented with PHGG for 8 days.

RESULTS

YAMC cells treated with PHGG exhibited significantly enhanced wound healing compared to the control cells; however, this enhancement was inhibited by both Y-27632 (RhoA inhibitor) and U0126 (ERK1/2 inhibitor). Likewise, there was a PHGG-dependent increase in F-actin accumulation and Rho kinase activity that was blocked by U0126. Meanwhile, PHGG-dependent ERK1/2 activity was not inhibited by Y-27632. In the DSS-induced mouse colitis model, animals that received food supplemented with PHGG exhibited significant recovery of the colonic mucosa.

CONCLUSIONS

In this study, we demonstrate that PHGG promotes colonic epithelial cell wound healing via activation of RhoA, which occurs downstream of ERK1/2 activation. These findings indicate that PHGG could be utilized as a therapeutic agent for patients with intestinal mucosal damage such as those with IBD.

[Small bowel injuries due to nonsteroidal anti-inflammatory drugs and antiplatelet therapy. Approaches to prevention and treatment]

Nonsteroidal anti-inflammatory drug (NSAID)-induced small bowel injuries (NSAID enteropathies) become clinically important. Videocapsule endoscopy shows that the small bowel is involved in NSAID-related gastrointestinal tract (GIT) injury in almost two-thirds of all cases. Due to a large number of patients who receive NSAIDs, combined antiplatelet therapy, or long use anticoagulants, GIT injury prevention becomes an actual problem. Treatment for NSAID enteropathy is different from that for NSAID gastropathy. In NSAID enteropathy, it is advisable to use drugs that are able to increase the production of prostaglandins and mucus, to restore intestinal epithelial permeability, and to exert anti-inflammatory and antioxidant effects. Rebamipide that produces many pleiotropic effects and also has cytoprotective properties may become the drug of choice for treating patients with NSAID enteropathy. In addition, rebamipide has no effects on various cytochrome P-450 enzyme systems, by reducing the risk of drug interactions.

Dietary nickel chloride restrains the development of small intestine in broilers

The aim of this study was to determine the effects of dietary NiCl2 on the development of the small intestine in broilers by the methods of light microscopy, histochemistry and enzyme-linked immunosorbent assay. A total of 240 one-day-old avian broilers were divided into four groups and fed on a corn-soybean basal diet or the same basal diet supplemented with 300, 600 and 900 mg/kg of nickel chloride (NiCl2) for 42 days. Results showed that the small intestinal villus height, crypt depth and villus/crypt ratio were significantly decreased, and also the small intestinal goblet cells numbers and insulin-like growth factor-1 (IGF-1) and epidermal growth factor (EGF) contents were significantly decreased in the 300-, 600- and 900-mg/kg groups when compared with those of the control group. In conclusion, dietary NiCl2 in excess of 300 mg/kg reduced the villus height, crypt depth, the goblet cells population and the IGF-1 and EGF contents in the small intestine, indicating that the normal development and function of the small intestine were finally impaired in broilers. This study firstly provided the new experimental information for future studies on the effects of NiCl2 on the intestinal function in humans and other animals.

High-potency sucralfate prevents and rapidly reverses chemo-radiation mucositis in a patient with stage 4b head and neck cancer

AIM: To study usefulness of high-potency sucralfate (HPS) in a patient with chemoradiation mucositis and discuss its mechanism of action.

METHODS: HPS, a non-covalently cross-link of sucralfate, cations and bidentate anionic chelators, has a maintains a surface concentration of sucralfate 3 h following administration that is 7-23 fold that possible with standard-potency sucralfate. The accelerated mucosal healing and pain alleviation of HPS in patients with erosive esophageal reflux, prompted its use in this patient with chemoradiation mucositis of the oropharynx and alimentary tract. A literature-based review of the immuno-modulatory effects of sucralfate is discussed.

RESULTS: Within 48 h of intervention: (1) there was complete disappearance of oral mucositis lesions; tenderness with (2) patient-reported disappearance of pain, nausea and diarrhea; patient required (3) no opiate analgesia and (4) no tube-feeding supplements to regular diet. Dysgeusia and xerostomia persisted. A modified Naranjo Questionnaire score of 10 supported the likelihood that HPS intervention caused the observed clinical effects. No adverse reactions noted.

CONCLUSION: In this patient HPS was useful to treat chemo-radiation mucositis of the oropharynx and alimentary tract. HPS may directly or indirectly facilitate an immunomodulatory mechanism involving accelerated growth factor activation, which may be a new target for therapeutic intervention in such patients.

Anatomy and histology of rodent and human major salivary glands: -overview of the Japan salivary gland society-sponsored workshop-

MAJOR SALIVARY GLANDS OF BOTH HUMANS AND RODENTS CONSIST OF THREE PAIRS OF MACROSCOPIC GLANDS: parotid, submandibular, and sublingual. These glands secrete serous, mucous or mixed saliva via the proper main excretory ducts connecting the glandular bodies with the oral cavity. A series of discoveries about the salivary ducts in the 17th century by Niels Stensen (1638-1686), Thomas Wharton (1614-1673), and Caspar Bartholin (1655-1738) established the concept of exocrine secretion as well as salivary glands. Recent investigations have revealed the endocrine functions of parotin and a variety of cell growth factors produced by salivary glands.The present review aims to describe macroscopic findings on the major salivary glands of rodents and the microscopic differences between those of humans and rodents, which review should be of interest to those researchers studying salivary glands.

The Helicobacter pylori virulence effector CagA abrogates human β-defensin 3 expression via inactivation of EGFR signaling

Antimicrobial peptides are constituents of the first-line innate mucosal defense system that acts as a barrier to establishment of infection. The highly successful human gastric pathogen, Helicobacter pylori, is able to persistently colonize its host despite inducing expression of several antimicrobial peptides, including human β-defensin 3 (hBD3). We find that hBD3 is highly active against H. pylori in vitro and is rapidly induced during early infection via EGFR-dependent activation of MAP kinase and JAK/STAT signaling. However, during prolonged infection, hBD3 was subsequently downregulated by the H. pylori virulence determinant CagA. Upon translocation into host cells, CagA activated the cellular tyrosine phosphatase, SHP-2, terminating EGFR activation and downstream signaling and increasing bacterial viability. Chemical inhibition and knockdown of SHP-2 expression rescued hBD3 synthesis and bactericidal activity. Thus, we reveal how cagPAI-positive H. pylori strains use CagA to evade a key innate mucosal defense pathway to support the establishment of persistent infection.

Clopidogrel delays gastric ulcer healing in rats

Clopidogrel is not safe enough for the gastric mucosa in patients with high risk of peptic ulcer. This study aimed to explore if clopidogrel delays gastric ulcer healing and elucidate the involved mechanisms. Gastric ulcer was induced in rats and the ulcer size, mucosal epithelial cell proliferation of the ulcer margin, expression of growth factors [epidermal growth factor (EGF), basic fibroblast growth factor] and their receptors, and signal transduction pathways for cell proliferation were measured and compared between the clopidogrel-treated group and untreated controls. For the in vitro part, rat gastric mucosal epithelial cell line (RGM-1 cells) was used to establish EGF receptor over-expressed cells. Cell proliferation and molecular change under EGF treatment (10ng/ml) with and without clopidogrel (10(-6)M) were demonstrated. Ulcer size was significantly larger in the clopidogrel-treated group compared to the control and mucosal epithelial cell proliferation of the ulcer margin was significantly decreased in the clopidogrel-treated group (P<0.05). Clopidogrel (2mg and 10mg/kg/day) significantly decreased ulcer-induced gastric epithelial cell proliferation and ulcer-stimulated expressions of EGF receptor and phosphorylated extracellular signal-regulated kinase (PERK) at the ulcer margin (P<0.05). Clopidogrel (10(-6)M) also inhibited EGF-stimulated EGF receptor, PERK expression, and cell proliferation in RGM-1 cells (P<0.05), and caused much less inhibition of EGF-stimulated cell proliferation in EGF receptor over-expressed RGM-1 cells than in RGM-1 cells (22% vs. 32% reduction). In conclusion, clopidogrel delays gastric ulcer healing in rats via inhibiting gastric epithelial cell proliferation, at least by inhibition of the EGF receptor-ERK signal transduction pathway.

Impact of preoperative targeted therapy on postoperative complications after resection of colorectal liver metastases

PURPOSE

The impact of chemotherapy (CTx) on morbidity after liver resection for colorectal metastases (CRC-LM) has been increasingly investigated during recent years. Biologic agents like bevacizumab (BEV) or cetuximab (CET) are now added as "targeted therapy" (TT), also in neoadjuvant settings. Initial series could demonstrate the safety of those regimens in liver resection but data are still scarce. We evaluated the impact of CTx with BEV or CET (CTx + TT) on perioperative morbidity and mortality.

METHODS

Two hundred thirty-seven patients who underwent liver resections for CRC-LM after chemotherapy before surgery since 1999 were included. One hundred eighty-five patients (78%) had preoperative CTx regimen without biologic agents (fluoropyrimidine-, oxaliplatin-, or irinotecan-based) and 52 (22%) had CTx + TT (39 BEV, 11 CET, 2 CET/BEV). After preoperative CTx + TT, a time interval of at least 4-6 weeks and a residual liver volume of >35% before surgery were required.

RESULTS

Hemihepatectomy or more was performed in about half of the patients. The median amount of intraoperatively transfused blood was 0 ml in both groups (p = 0.34). Overall mortality was 1.7% and slightly elevated in patients with CTx + TT (3.8% vs. 1.1%, p = 0.17). Any complication occurred in (CTx + TT vs. CTx) 52% and 46%, respectively (p = 0.47). The rates of liver failure (9.6% vs. 9.7%, p = 0.98), infectious complications such as wound infection (19% vs. 16%, p = 0.62) and abdominal abscess (8% vs. 6.5%, p = 0.71), as well as the rate of relaparotomies (11.5% vs. 7.0%, p = 0.29) showed no significant differences between the groups with TT or without. In multivariate analyses, neither type nor duration of CTx nor the time interval between CTx and surgery showed any influence on complication rates.

CONCLUSIONS

Our data confirm the safety of targeted therapy before liver resection for CRC-LM. This effect may in part be due to our treatment policy (time interval to resection and residual liver volume) after intensive preoperative CTx.

Acute high-dose X-radiation-induced genomic changes in A549 cells

Accidents with ionizing radiation often involve single, acute high-dose exposures that can lead to acute radiation syndrome and late effects such as carcinogenesis. To study such effects at the cellular level, we investigated acute ionizing radiation-induced chromosomal aberrations in A549 adenocarcinoma cells at the genome-wide level by exposing the cells to an acute dose of 6 Gy 240 kV X rays. One sham-irradiated clone and four surviving irradiated clones were recovered by minimal dilution and further expanded and analyzed by chromosome painting and tiling-path array CGH, with the nonirradiated clone 0 serving as the control. Acute X-ray exposure induced specific translocations and changes in modal chromosome number in the four irradiated clones. Array CGH disclosed unique and recurrent genomic changes, predominantly losses, and revealed that the fragile sites FRA3B and FRA16D were preferential regions of genomic alterations in all irradiated clones, which is likely related to radioresistant S-phase progression and genomic stress. Furthermore, clone 4 displayed an increased radiosensitivity at doses >5 Gy. Pairwise comparisons of the gene expression patterns of all irradiated clones to the sham-irradiated clone 0 revealed an enrichment of the Gene Ontology term "M Phase" (P = 6.2 × 10(-7)) in the set of differentially expressed genes of clone 4 but not in those of clones 1-3. Ionizing radiation-induced genomic changes and fragile site expression highlight the capacity of a single acute radiation exposure to affect the genome of exposed cells by inflicting genomic stress.

Downregulation of serum epidermal growth factor in patients with inflammatory bowel disease. Is there a link with mucosal damage?

BACKGROUND

Epidermal growth factor (EGF) is a multipotent peptide which contributes to epithelial development, inhibition of gastric acid secretion, acceleration of wound healing, and promotion of angiogenesis. The aim of this study is to evaluate serum EGF concentrations in inflammatory bowel disease (IBD) patients, with regard to disease and patients' characteristics.

METHODS

EGF determination was performed by a commercially available enzyme-linked immunosorbent assay. Fifty-two patients with ulcerative colitis (UC), 59 with Crohn's disease (CD), and 55 healthy controls (HC) were included in the study.

RESULTS

Mean ( ± SEM) serum EGF levels were 217.2 ( ± 30.40) pg/mL in UC patients, 324.6 ( ± 37.29) pg/mL in CD patients, and 453.1 ( ± 39.44) pg/mL in HC. Serum EGF levels were significantly lower in UC and CD patients compared to HC (P < 0.0001 and P = 0.0199, respectively). Lower serum EGF levels were observed in UC compared to CD patients (P = 0.0277). Extent of the disease was found to affect serum EGF levels in UC, demonstrating significant reduction in patients with left-sided colitis and pancolitis in comparison with those with proctitis (P = 0.0190 and P = 0.0024, respectively). EGF concentration was not influenced by other characteristics of patients and disease.

CONCLUSIONS

Significantly, lower levels of serum EGF are observed in IBD patients compared to HC, while disease extent plays a key role in regulation of serum EGF in UC. Downregulation of serum EGF may be correlated with different patterns of bowel inflammation, epithelial development, and wound healing in IBD.

Modulation of protein tyrosine phosphorylation in gastric mucosa during re-epithelization processes

AIM: To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration.

METHODS: Gastric lesions were induced in rats using restraint cold stress. To investigate the effect of oxidative and nitrosative cell stress on tyrosine phosphorylation during wound repair, total activity of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTP), antioxidant enzymes, nitric oxide synthase (NOS), 2’,5’-oligoadenylate synthetase, hydroxyl radical and zinc levels were assayed in parallel.

RESULTS: Ulcer provocation induced an immediate decrease in tyrosine kinase (40% in plasma membranes and 56% in cytosol, P < 0.05) and phosphatase activity (threefold in plasma membranes and 3.3-fold in cytosol), followed by 2.3-2.4-fold decrease (P < 0.05) in protein phosphotyrosine content in the gastric mucosa. Ulceration induced no immediate change in superoxide dismutase (SOD) activity, 30% increase (P < 0.05) in catalase activity, 2.3-fold inhibition (P < 0.05) of glutathione peroxidase, 3.3-fold increase (P < 0.05) in hydroxyl radical content, and 2.3-fold decrease (P < 0.05) in zinc level in gastric mucosa. NOS activity was three times higher in gastric mucosa cells after cold stress. Following ulceration, PTK activity increased in plasma membranes and reached a maximum on day 4 after stress (twofold increase, P < 0.05), but remained inhibited (1.6-3-fold decrease on days 3, 4 and 5, P < 0.05) in the cytosol. Tyrosine phosphatases remained inhibited both in membranes and cytosol (1.5-2.4-fold, P < 0.05). NOS activity remained increased on days 1, 2 and 3 (3.8-, 2.6-, 2.2-fold, respectively, P < 0.05). Activity of SOD increased 1.6 times (P < 0.05) days 4 and 5 after stress. Catalase activity normalized after day 2. Glutathione peroxidase activity and zinc level decreased (3.3- and 2-fold, respectively, P < 0.05) on the last day. Activity of 2’,5’-oligoadenylate synthethase increased 2.8-fold (P < 0.05) at the beginning, and 1.6-2.3-fold (P < 0.05) during ulcer recuperation, and normalized on day 5, consistent with slowing of inflammation processes.

CONCLUSION: These studies show diverse changes in total tyrosine kinase activity in gastric mucosa during the recovery process. Oxidative and nitrosative stress during lesion formation might lead to the observed reduction in tyrosine phosphorylation during ulceration.

Identification of gene biomarkers for respiratory syncytial virus infection in a bronchial epithelial cell line

Respiratory syncytial virus (RSV) infection involves complex virus-host interplay. In this study, we analyzed gene expression in RSV-infected BEAS-2B cells to discover novel signaling pathways and biomarkers. We hybridized RNAs from RSV- or vehicle-treated BEAS-2B to Affymetrix HU133 plus 2.0 microarrays (n = 4). At 4 and 24 h post-infection, 277 and 900 genes (RSV/control ratio >/=2.0 or </=0.5), and 1 and 12 pathways respectively were significantly altered. Twenty-three and 92 genes at 4 and 24 h respectively matched respiratory disease biomarkers with ARG2 flagged at 24 h and SCNN1G, EPB41L4B, CSF1, PTEN, TUBB1 and ESR2 at both time points. Hierachical clustering showed a cluster containing ARG2 and IL8. In human bronchial epithelial cells, RSV upregulated arginase II protein. Knockdown of ARG2 increased RSV-induced IL-8, LDH and histone release. With microarray, we identified novel proximal airway epithelial cell genes that may be tested in the sputum samples as biomarkers of RSV infection.

Expression of a functional epidermal growth factor receptor on human adipose-derived mesenchymal stem cells and its signaling mechanism

Adult stem cells act as a pluripotent source of regenerative cells during tissue injury. Despite expanded research in stem cell biology, understanding how growth and migration of adipose-derived adult mesenchymal stem cells (ASC) are governed by interactions with growth factors is very limited. One important property of ASC is the presence of the epidermal growth factor (EGF) receptor and the cellular response to soluble EGF. Expression of the EGF receptor was proven by PCR and Western blotting. Signal transduction was analyzed by Western blotting and PhosFlow assay. EGF caused robust phosphorylation of SHC and ERK1/2, which could be inhibited by EGF receptor antagonist AG1478 and MEK inhibitor PD98059. ASC proliferation was determined by MTT assay. Stem cell migration was analyzed in a modified Boyden chamber. Incubation with EGF led to cell proliferation and induced cell migration, but did not change the undifferentiated state of the cells. In the kidney, injured renal tubular cells express high amounts of EGF. Therefore, our results may highlight a mechanism underlying renal regeneration. Thus, future in vivo studies that focus on the effects of EGF on recruitment of ASC to sites of injury are necessary.

Oligosaccharides from human milk induce growth arrest via G2/M by influencing growth-related cell cycle genes in intestinal epithelial cells

Oligosaccharides are present in human milk in large amounts and in a high variety. We have previously shown that these oligosaccharides are strong inhibitors of proliferation and inducers of differentiation in intestinal cell lines. To elucidate the molecular mechanism, we investigated the influence on cell cycle events via flow cytometry and expression levels by using quantitative real-time RT-PCR. Human intestinal cells, i.e. HT-29, HIEC and Caco-2 cells, were exposed to neutral or acidic human milk oligosaccharides. Both fractions induced a concentration-dependent G2/M arrest. Cell cycle analysis for HT-29 revealed 37 % of cells in G1 and 35 % in G2/M (neutral oligosaccharides) and incubation with acidic oligosaccharides led to 42 % cells in G1 and 40 % in G2/M. In control experiments without oligosaccharides we found 71 % of cells to be in G1 and 17 % in G2/M. This G2/M arrest was associated with changes in mRNA expression of cyclin A and B. A G2/M arrest with concomitant alterations of cell cycle gene expression could also be shown for HIEC and Caco-2 cells. Analysing the expression of cyclin-dependent kinase inhibitors p21(cip1) and p27(kip1) and the tumour suppressor p53 we observed that the expression of p21(cip1) was p53-independent and necessary for arresting cells in the G2/M phase, while p27(kip1) was associated with differentiation effects. Both neutral and acidic human milk oligosaccharides were able to induce epidermal growth factor receptor, extracellular signal-regulated kinase 1/2 and p38 phosphorylation. These results suggest that oligosaccharides from human milk inhibited intestinal cell proliferation and altered cell cycle dynamics by affecting corresponding regulator genes and mitogen-activated protein kinase signalling.

Helicobacter and gastric malignancies

Individuals infected with Helicobacter pylori, a stomach colonizing bacteria, have an increased risk of developing gastric malignancies. The risk for developing cancer relates to the physiologic and histologic changes that H. pylori infection induces in the stomach. In the last year numerous studies have been conducted in order to characterize the association between H. pylori infection and gastric cancer. These studies range from epidemiologic approaches aiming at the identification of environmental, host genetic, and bacterial factors associated with risk of gastric cancer, to molecular and cell biology approaches aiming at understanding the interaction between H. pylori and the transforming epithelial cell. In this review an account of the last year's research activity on the relationship between H. pylori and gastric cancer will be given.

Smad3 knockout mice exhibit impaired intestinal mucosal healing

Altered transforming growth factor-beta (TGFbeta) expression may contribute to inflammatory bowel disease and modulate epithelial cell restitution. Interference with TGFbeta-mediated signaling inhibits excisional skin wound healing, but accelerates healing of incisional cutaneous wounds and wounds in some other tissues. Therefore, we sought to clarify the potential role of Smad3-dependent TGFbeta signaling in intestinal mucosal healing in Smad3 null mice. Jejunal serosal application of filter disks saturated with 75% acetic acid yielded a circumscribed reproducible ischemic mucosal ulcer 1 day later. We compared ulcer area at 3 and 5 days to day 1 in Smad3 knockout mice and syngeneic wild-type mice, and evaluated mucosal immunoreactivity at the ulcer edge for TGFbeta, phosphorylated (activated) focal adhesion kinase (pFAK), phosphorylated extracellular signal-related kinase (pERK), proliferating cell nuclear antigen and apoptosis by TUNEL. Ulcer healing in Smad3 null mice was 17% less at day 3 (n=14, P=0.022) and 15% less at day 5 (n=14, P=0.004) than in wild-type littermates. In wild-type mice, pFAK, pERK and TGFbeta immunoreactivity were elevated in epithelium immediately adjacent to the ulcer compared with more distant mucosa. However, this pattern of immunoreactivity for pFAK, pERK and TGFbeta was not observed in Smad3 null mice. Smad3 null mice exhibited increased epithelial proliferation and no differences in apoptotic cell death compared with wild types, suggesting that ulcer healing may reflect differences in restitutive cell migration. Thus, Smad3-dependent disruption of the TGFbeta signaling pathway impairs the healing of murine intestinal mucosal ulcers and alters patterns of activated FAK and ERK immunoreactivity important for cell migration at the ulcer edge. These studies suggest a significant role for Smad3-dependent TGFbeta signaling in intestinal mucosal healing.

MS4A12 is a colon-selective store-operated calcium channel promoting malignant cell processes

Using a data mining approach for the discovery of new targets for antibody therapy of colon cancer, we identified MS4A12, a sequence homologue of CD20. We show that MS4A12 is a cell surface protein. Expression analysis and immunohistochemistry revealed MS4A12 to be a colonic epithelial cell lineage gene confined to the apical membrane of colonocytes with strict transcriptional repression in all other normal tissue types. Expression is maintained upon malignant transformation in 63% of colon cancers. Ca(2+) flux analyses disclosed that MS4A12 is a novel component of store-operated Ca(2+) entry in intestinal cells. Using RNAi-mediated gene silencing, we show that loss of MS4A12 in LoVo colon cancer cells attenuates epidermal growth factor receptor-mediated effects. In particular, proliferation, cell motility, and chemotactic invasion of cells are significantly impaired. Cancer cells expressing MS4A12, in contrast, are sensitized and respond to lower concentrations of epidermal growth factor. In summary, these findings have implications for both the physiology of colonic epithelium as well as for the biology and treatment of colon cancer.

Necrotizing enterocolitis: A multifactorial disease with no cure

Necrotizing enterocolitis is an inflammatory bowel disease of neonates with significant morbidity and mortality in preterm infants. Due to the multifactorial nature of the disease and limitations in disease models, early diagnosis remains challenging and the pathogenesis elusive. Although preterm birth, hypoxic-ischemic events, formula feeding, and abnormal bacteria colonization are established risk factors, the role of genetics and vasoactive/inflammatory mediators is unclear. Consequently, treatments do not target the specific underlying disease processes and are symptomatic and surgically invasive. Breast-feeding is the most effective preventative measure. Recent advances in the prevention of necrotizing enterocolitis have focused on bioactive nutrients and trophic factors in human milk. Development of new disease models including the aspect of prematurity that consistently predisposes neonates to the disease with multiple risk factors will improve our understanding of the pathogenesis and lead to discovery of innovative therapeutics.

The role of nitric oxide in intestinal epithelial injury and restitution in neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common life-threatening gastrointestinal disease encountered in the premature infant. Although the inciting events leading to NEC remain elusive, various risk factors, including prematurity, hypoxemia, formula feeding, and intestinal ischemia, have been implicated in the pathogenesis of NEC. Data from our laboratory and others suggest that NEC evolves from disruption of the intestinal epithelial barrier, as a result of a combination of local and systemic insults. We postulate that nitric oxide (NO), an important second messenger and inflammatory mediator, plays a key role in intestinal barrier failure seen in NEC. Nitric oxide and its reactive nitrogen derivative, peroxynitrite, may affect gut barrier permeability by inducing enterocyte apoptosis (programmed cell death) and necrosis, or by altering tight junctions or gap junctions that normally play a key role in maintaining epithelial monolayer integrity. Intrinsic mechanisms that serve to restore monolayer integrity following epithelial injury include enterocyte proliferation, epithelial restitution via enterocyte migration, and re-establishment of cell contacts. This review focuses on the biology of NO and the mechanisms by which it promotes epithelial injury while concurrently disrupting the intrinsic repair mechanisms.

SOCS3 negatively regulates the gp130-STAT3 pathway in mouse skin wound healing

Proliferation and differentiation of keratinocytes during wound healing are regulated by cytokines and chemokines, which are secreted by resident and inflammatory cells and activate the transcription factor signal transducer and activator of transcription (STAT)3. However, it is not clear to what extent STAT3 in keratinocytes is activated by gp130-containing receptors. We addressed this question genetically by deleting the suppressor of cytokine signaling (SOCS)3, a negative regulator of gp130-mediated STAT3 activation. Socs3 alleles flanked by loxP sites were deleted in mice with either an MMTV-Cre or K5-Cre transgene. While both transgenes are active in keratinocytes, the MMTV-Cre deletes floxed genes also in immune cells. Deletion of Socs3 using the MMTV-Cre transgene resulted in aberrant STAT3 activation, impaired wound healing, prolonged secretion of chemokines, a hyperproliferative epidermis, and neutrophil infiltration into wounds. Simultaneous deletion of the Socs3 and gp130 genes restored normal wound healing. Moreover, deletion of Socs3 only in keratinocytes caused impaired wound healing. These results demonstrate that wound healing is controlled in keratinocytes by the gp130-SOCS3-STAT3 pathway and an imbalance of this pathway results in delayed wound healing.

Ang II and EGF synergistically induce COX-2 expression via CREB in intestinal epithelial cells

Cyclooxygenase (COX)-2 derived prostaglandins (PGs) play a major role in intestinal inflammation and colorectal carcinogenesis. Because COX-2 is the rate-limiting step in the production of PGs, mechanisms that regulate COX-2 expression control PG production in the cell. Using the non-tumorigenic, rat intestinal epithelial cell, IEC-18, we demonstrate that co-activation of endogenously expressed AT(1) receptor and EGFR resulted in synergistic expression of COX-2 mRNA and protein involving transcriptional and post-transcriptional mechanisms. Ang II and EGF induced transient phosphorylation of ERK, p38(MAPK) and CREB. Co-stimulation with Ang II and EGF prolonged phosphorylation of ERK, p38(MAPK), and CREB. The p38(MAPK) selective inhibitor, SB202190, but not the MEK selective inhibitor, PD98059, or the EGFR kinase inhibitor, AG1478, inhibited Ang II-dependent COX-2 expression and CREB phosphorylation. EGF-dependent COX-2 expression and CREB phosphorylation were inhibited by SB202190, PD98059, and AG1478. Inhibition of CREB expression using two separate RNAi methods blocked COX-2 expression by Ang II and EGF. Expression of a dominant negative CREB mutant inhibited Ang II- and EGF-dependent induction of the COX-2 promoter. Ang II induced luciferase expression in cells transfected with the CRE-luc reporter vector and cells co-transfected with Gal4-luc reporter vector and a Gal4-CREB expression vector. Chromatin immunoprecipitation assays demonstrated CREB binding to the proximal rat COX-2 promoter region containing a CRE cis-acting element. These results indicate that co-stimulation with Ang II and EGF synergistically induced COX-2 expression in these intestinal epithelial cells through p38(MAPK) mediated signaling cascades that converge onto CREB.

Complications after oesophagectomy with possible contribution of neoadjuvant therapy including an EGFR-antibody to a fatal outcome

Background

Different molecular therapies like the EGFR-inhibiting antibody cetuximab have come into clinical practice. Cetuximab is EMEA-approved for metastatic colorectal cancer and advanced squamous-cell head and neck cancer. Administration is said to be safe and well tolerated with common, usually mild dermatologic side effects.

Case presentation

We present the case of a patient with fatal complications after oesophagectomy and neoadjuvant chemotherapy including cetuximab for squamous-cell esophageal cancer. A transthoracic en-bloc oesophagectomy was performed. Few days later the patient died due to gas exchange dysfunction and circulation instability after a previously unseen combination of drain-erosion of the stomach with subsequent pleurisy and air leak of the left main bronchus.

Conclusion

So far we have never observed this fatal combination of drain erosion of the stomach with fibrinous pleurisy and unmanageable progressive tracheal defect before. The role of cetuximab in the multifactorial aetiology of damages of stomach and trachea after oesophagectomy remains unclear since we are not able to link the complication directly to cetuximab or definitely exclude it as a sole surgical complication. Clinicians should be aware of the possibility of fatal side effects and careful recording of all complications is necessary in ongoing and planned studies to obtain more evidence about safety and tolerance of targeted therapies.

Transactivation of the EGFR by AP-1 is induced by Helicobacter pylori in gastric cancer

BACKGROUND

Helicobacter pylori infection of the gastric mucosa is strongly associated with gastritis, peptic ulcer disease, and gastric cancer. However, the mechanisms by which H. pylori causes cancer are currently unknown. Binding of epidermal growth factor (EGF) to its receptor (EGFR) may be important in the development of gastric cancer. This interaction accelerates cell proliferation and migration, and triggers epithelial cell signaling. In this study, we investigated the effects of H. pylori on EGFR- and AP-1-mediated signal transduction pathways in the AGS gastric epithelial cell line and gastric tissue from humans.

METHODS

Cells were treated with H. pylori and cell death was examined at a variety of time points using cell viability and trypan blue exclusion dye assay. To investigate the effects on EGFR regulation, AGS cells were transfected with a full-length and truncated EGFR luciferase (luc) reporter. Tissue microarray containing 44 samples of gastric biopsies from H. pylori-positive patients was analyzed for protein expression level of EGFR by immunohistochemistry.

RESULTS

EGFR promoter activity was increased (twofold) 3 h after treatment with H. pylori commenced. Using a series of EGFR promoter deletion mutants, we identified a region that was crucial for transactivation of the EGFR by H. pylori. To determine whether AP-1 binding was altered, we transfected AGS cells with an AP-1 luciferase construct and then treated them with H. pylori for up to 6 h. We found that AP-1 activity was induced by H. pylori in gastric cells, while electrophoretic mobility shift assays confirmed that binding of AP-1 to the EGFR promoter site was increased following H. pylori treatment. Binding of c-Jun and c-Fos to the EGFR promoter region -1,062/-900 was induced eight- and six fold, respectively, using ChIP assay. Active EGFR staining was markedly increased in gastric mucosa from infected persons, compared to uninfected controls.

CONCLUSIONS

We conclude that exposure of gastric cells to H. pylori induces increased production of EGFR through various signal transduction pathways, including those mediated by the EGFR and AP-1. Distinct effects on EGFR activation may specify the subset of AP-1 target genes that are selected, including those involved in proliferation and apoptosis. This is consistent with EGFR activation that was found in the gastric mucosa of humans infected with H. pylori. Hence, the balance between apoptosis and proliferation in these cells may be altered in response to injury caused by H. pylori infection, leading to an increased risk of cancer.

Development of a quantitative, cell-based, high-content screening assay for epidermal growth factor receptor modulators

AIM

To develop a robust, cell-based, high-content screening (HCS) assay based on receptor internalization for the identification of novel modulators of the epidermal growth factor receptor (EGFR).

METHODS

Agonist-induced receptor internalization is part of the signaling cascade of EGFR. Fluorescent-tagged epidermal growth factor (EGF) was used to visualize the internalized receptor-ligand complex. The fluorescent intracellular spots were detected and measured with an ArrayScan HCS reader. Compounds that can competitively bind to EGFR or interfere with EGFR internalization process would result in a reduced number and intensity of intracellular fluorescent spots. This assay was validated, optimized, and applied to a large-scale screening of a library containing 48,000 synthetic compounds.

RESULTS

The competition between fluorescent EGF and unlabeled EGF reveals the IC(50) of unlabeled EGF is approximately 0.2 nmol/L, which is comparable with other published reports. Thirteen compounds with a relatively high degree of interference with EGFR internalization were identified. One of the compounds was proven to be agonist of the EGFR since it induced phosphorylation of the receptor and extracellular signal-regulated protein kinase (ERK).

CONCLUSION

This automated, objective, and easy-to-use assay provided abundant information, quantitative results, and demonstrated the potential use of HCS methods in searching membrane receptor modulators.

Impairment of gastric ulcer healing by alendronate, a nitrogen-containing bisphosphonate, in rats

Bisphosphonates such as alendronate have been developed as antiresorptive agents capable of treating diseases related to bone remodeling. In the present study, we examined the effect of alendronate on the healing of acetic acid-induced gastric ulcers in rats and investigated the mechanism involved in this action both in vivo and in vitro using the rat gastric epithelial cell line (RGM1). Acetic acid-induced gastric ulcers healed spontaneously, with up-regulation of COX-2/prostaglandin E2 production as well as expression of vascular endothelium-derived growth factor (VEGF) and basic fibroblast growth factor (bFGF) in ulcerated mucosa. The healing of ulcers was impaired by indomethacin (2 mg/kg, s.c.) or alendronate (60 mg/kg, p.o.) given once daily for 7 days, starting 3 days after acid application. Indomethacin, but not alendronate, inhibited mucosal prostaglandin E2 production. Alendronate as well as indomethacin decreased the protein expression of both VEGF and bFGF in ulcerated mucosa, resulting in a reduction of angiogenesis in the ulcer base. Supplementation of recombinant bFGF significantly reverted the delay in ulcer healing caused by alendronate. On the other hand, the size of cell-free areas in RGM1 cells in vitro decreased with time after wound induction, and this process was promoted by epidermal growth factor (EGF; 10 ng/ml). Co-incubation with alendronate (1 mM) did not affect the spontaneous healing but significantly suppressed the accelerated wound healing caused by EGF. These results suggest that alendronate impairs the healing of gastric ulcers in rats, and this effect may be related to down-regulation of VEGF and bFGF, the important growth factors for vascularization/granulation, as well as suppression of the stimulatory action of EGF on epithelial proliferation/migration.

Probiotic Lactobacillus rhamnosus GG enhances gastric ulcer healing in rats

Probiotics are widely used as functional foods which have been advocated for the maintenance of gastrointestinal microflora equilibrium and treatment of gastrointestinal disorders. However, studying the role of probiotics in peptic ulcer disease is limited. The aim of the present study is to investigate the effect of a probiotic strain Lactobacillus rhamnosus GG on gastric ulcer and to elucidate the mechanisms involved. Gastric kissing ulcers were induced in rats by acetic acid (60% v/v). L. rhamnosus GG was given intragastrically at 10(8) cfu/day or 10(9) cfu/day for three consecutive days after ulcer induction. L. rhamnosus GG successfully colonized in the gastric mucosa especially at the ulcer margin. It also significantly and dose-dependently reduced gastric ulcer area. Cell apoptosis to cell proliferation ratio was strongly decreased and accompanied by significant up-regulation of ornithine decarboxylase (ODC) and B-cell lymphoma 2 (Bcl-2) protein expression at the ulcer margin. Angiogenesis was also significantly stimulated together with the induction of vascular endothelial growth factor (VEGF) expression. Furthermore, L. rhamnosus GG up-regulated the phosphorylation level of epidermal growth factor receptor (EGF receptor) without altering the total EGF receptor expression. These findings suggested that L. rhamnosus GG enhanced gastric ulcer healing via the attenuation of cell apoptosis to cell proliferation ratio and increase in angiogenesis. Regulators of these processes such as ODC, Bcl-2, VEGF and EGF receptor are likely to be involved in the healing action of L. rhamnosus GG for gastric ulcer.

Dexamethasone inhibits epidermal growth factor-stimulated gastric epithelial cell proliferation

Epidermal growth factor (EGF) is essential to heal gastric ulcers, whereas glucocorticoid delays rat gastric ulcer healing. We found that dexamethasone inhibited EGF-stimulated rat gastric epithelial cell (RGM-1) proliferation by cell count and DNA synthesis analysis of flow cytometry and attempted to elucidate the possible mechanistic pathway via Western blot analysis. EGF (10 ng/ml) treatment for 24 h significantly increased RGM-1 cell proliferation, and dexamethasone (10(-8) and 10(-6) M) markedly suppressed EGF-stimulated cell proliferation. Western blotting results demonstrated that the phosphorylated extracellular signal-regulated kinase (pERK) (pERK1/pERK2) significantly increased at 10 min after EGF treatment. This was followed by increase of cyclooxygenase (COX)-2 expression at 3 h after EGF treatment. The continued increase of COX-2 (up to 18 h) resulted in increased intracellular prostaglandin E(2) and cyclin D1 expression significantly after 8 and 12 h of EGF treatment. Dexamethasone substantially reduced EGF-stimulated COX-2 expression at 3 and 6 h and cyclin D1 expression at 8 and 12 h. Pretreatment of RGM-1 cells with dexamethasone or 2'-amino-3'-methoxyflavone (PD98059)-mitogen-activated protein kinase kinase inhibitor (5 x 10(-5) M) significantly reduced EGF-stimulated pERK1/pERK2 expression. Simultaneous treatment of RGM-1 cells with PD98059 and EGF also markedly decreased EGF-stimulated COX-2 expression at 6 h. These findings indicate that dexamethasone significantly suppresses EGF-stimulated gastric epithelial cell proliferation, and one of the pathways involved is via inhibiting activation of ERK1/ERK2, followed by inhibition of COX-2, cyclin D1 expression, and finally DNA synthesis.

Different Effects of Growth Factors on Human Renal Early Distal Tubular Cells in vitro

BACKGROUND

In the kidney, recovery from tubular damage requires regenerative mechanisms leading to re-epithelialization of the injured tubules. Current evidence supports the para- or autocrine role of growth factors in repair and regeneration of ischemic or nephrotoxic experimental acute renal failure.

METHODS

We evaluated the effects of EGF, HGF, IGF-1, and bFGF on human renal thick ascending limb and distal convoluted cells (TALDC) in vitro. TALDC were isolated by immunomagnetic separation and cultured. Signal transduction of the growth factors was evaluated by Western blot of ERK1/2 MAP-K phosphorylation. Cell proliferation was measured by MTT assay and a fluorometric assay.

RESULTS

A significant, dose- and time-dependent phosphorylation of ERK1/2 could be detected exclusively after stimulation with EGF. No other growth factor induced a significant MAPK phosphorylation. In the same manner, proliferation assays showed a significant growth-promoting effect of EGF. Neither HGF, nor IGF-1 or bFGF showed a stimulative effect on TALDC proliferation.

CONCLUSION

The present study highlights the effects of growth factors on cultured TALDC and supports the hypothesis that in vivo EGF plays a para- or autocrine role during renal repair mechanisms.

Enhanced expression of epidermal growth factor receptor gene in gastric mucosal cells by the serum derived from rats treated with electroacupuncture at stomach meridian acupoints

AIM: To investigate the effect of serum derived from rats treated with electroacupuncture at stomach meridian acupoints on the expression of epidermal growth factor receptor (EGFR) gene in gastric mucosal cells.

METHODS: The stress-induced gastric mucosal injury in rat model was established by water-immersion and restrained stress methods. 52 rats were randomly divided into: normal group (n = 8), model group (n = 8), model serum group (n = 12), stomach serum group (n = 12), and gallbladder serum group (n = 12). The gastric mucosal cells were separated by pronase-EDTA digestion method and incubated with serum. The EGFR gene expression in gastric mucosal cells was detected by reverse transcription-polymerase chain reaction (RT-PCR) method.

RESULTS: Compared with normal group (0.6860 ± 0.0594), the serum derived from rats of the stomach group (1.2272 ± 0.0813, P = 0.00 < 0.01) and gallbladder group (0.9640 ± 0.0387, P = 0.00 < 0.01) had a tendency to enhance the EGFR gene expression in gastric mucosal cells. Such tendency existed in the model group (0.7104 ± 0.0457) but with no significant difference (P = 0.495 > 0.05) and in model serum group (0.8516 ± 0.0409) with an extremely obvious difference (P = 0.001 < 0.01). Furthermore, the EGFR gene expression in stomach serum group was significantly higher than that in gallbladder serum group (P = 0.00 < 0.01).

CONCLUSION: The present study shows that serum derived from rats treated with electroacupuncture at stomach meridian acupoints can distinctly increase the EGFR gene expression of gastric mucosal cells. Therefore, there is certain meridian specificity in the serum, which could provide a proof for the TCM theory “particular relation between meridian and internal organ”.

Focal adhesion kinase protein levels in gut epithelial motility

Mucosal healing requires migration and proliferation. Most studies of focal adhesion kinase (FAK), a protein that regulates motility, proliferation, and apoptosis, have focused on rapid phosphorylation. We reported lower FAK protein levels in motile Caco-2 colon cancer cells and postulated that this reduction in FAK available for activation might impact cell migration and mucosal healing. Therefore, total and active FAK (FAK(397)) immunoreactivity was assessed at the migrating fronts of human Caco-2 and rat IEC-6 intestinal epithelial cells. Caco-2 and IEC-6 motility, quantitated as migration into linear or circular wounds, was examined following FAK protein inhibition by small interfering RNA (siRNA). FAK protein stability and mRNA expression were ascertained by cycloheximide decay, RT-PCR, and in situ hybridization in static and migrating Caco-2 cells. Cells at the migrating front of Caco-2 and IEC-6 monolayers exhibited lower immunostaining for both total and activated FAK than cells immediately behind the front. Western blot analysis also demonstrated diminished FAK protein levels in motile cells by >/=30% in both the differential density seeding and multiple scrape models. siRNA FAK protein inhibition enhanced motility in both the linear scrape (20% in Caco-2) and circular wound (16% in Caco-2 and 19% in IEC-6 cells) models. FAK protein degradation did not differ in motile and static Caco-2 cells and was unaffected by FAK(397) phosphorylation, but FAK mRNA was lower in migrating Caco-2 cells. Thus FAK protein abundance appears regulated at the mRNA level during gut epithelial cell motility and may influence epithelial cell migration coordinately with signals that modify FAK phosphorylation.

Roles of epidermal growth factor and Na+/H+ exchanger-1 in esophageal epithelial defense against acid-induced injury

Epidermal growth factor (EGF) is predominantly secreted by salivary glands and activates Na(+)/H(+) exchanger-1 (NHE-1), which regulates intracellular pH (pH(i)). We investigated the roles of EGF and NHE-1 in esophageal epithelial defense against acid using human esophageal epithelial cell lines and a rat chronic esophagitis model. Esophageal epithelial cells were incubated with acidified medium in the absence or presence of EGF. Cell viability and changes in pH(i) were measured. Chronic acid reflux esophagitis was induced in rats with and without sialoadenectomy. Esophageal lesion index, epithelial proliferation, and expression of EGF receptors and NHE-1 were examined. EGF protected esophageal epithelial cells against acid in a dose-dependent manner, and the cytoprotective effect of EGF was completely blocked by treatment with NHE-1 inhibitors. Tyrosine kinase, calmodulin, and PKC inhibitors significantly inhibited cytoprotection by EGF, whereas MEK, phosphatidylinositol 3-kinase, and PKA inhibitors had no effect. EGF significantly increased pH(i) recovery after NH(4)Cl pulse acidification, and this increase in pH(i) recovery was significantly blocked by inhibitors of calmodulin and PKC. Sialoadenectomy led to an increase in the severity of chronic esophagitis but affected neither epithelial proliferation nor expression of EGF receptors. Expression of NHE-1 mRNA was increased in esophagitis and upregulated in rats with sialoadenectomy. The increasing severity of esophagitis in rats with sialoadenectomy was prevented by exogenous administration of EGF. In conclusion, EGF protects esophageal epithelial cells against acid through NHE activation via Ca(2+)/calmodulin and the PKC pathway. Deficiency in endogenous EGF is associated with increased severity of esophagitis. EGF and NHE-1 play crucial roles in esophageal epithelial defense against acid.

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