Increased expression of epidermal growth factor receptor during gastric ulcer healing in rats

Essential Oils: Chemistry and Pharmacological Activities-Part II

The importance of essential oils and their components in the industrial sector is attributed to their chemical characteristics and their application in the development of products in the areas of cosmetology, food, and pharmaceuticals. However, the pharmacological properties of this class of natural products have been extensively investigated and indicate their applicability for obtaining new drugs. Therefore, this review discusses the use of these oils as starting materials to synthesize more complex molecules and products with greater commercial value and clinic potential. Furthermore, the antiulcer, cardiovascular, and antidiabetic mechanisms of action are discussed. The main mechanistic aspects of the chemopreventive properties of oils against cancer are also presented. The data highlight essential oils and their derivatives as a strategic chemical group in the search for effective therapeutic agents against various diseases.

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.

Sonic Hedgehog acts as a macrophage chemoattractant during regeneration of the gastric epithelium

Sonic Hedgehog (Shh), secreted from gastric parietal cells, contributes to the regeneration of the epithelium. The recruitment of macrophages plays a central role in the regenerative process. The mechanism that regulates macrophage recruitment in response to gastric injury is largely unknown. Here we tested the hypothesis that Shh stimulates macrophage chemotaxis to the injured epithelium and contributes to gastric regeneration. A mouse model expressing a myeloid cell-specific deletion of Smoothened (LysMcre/+;Smof/f) was generated using transgenic mice bearing loxP sites flanking the Smo gene (Smo loxP) and mice expressing a Cre recombinase transgene from the Lysozyme M locus (LysMCre). Acetic acid injury was induced in the stomachs of both control and LysMcre/+;Smof/f (SmoKO) mice and gastric epithelial regeneration and macrophage recruitment analyzed over a period of 7 days post-injury. Bone marrow-derived macrophages (BM-Mø) were collected from control and SmoKO mice. Human-derived gastric organoid/macrophage co-cultures were established, and macrophage chemotaxis measured. Compared to control mice, SmoKO animals exhibited inhibition of ulcer repair and normal epithelial regeneration, which correlated with decreased macrophage infiltration at the site of injury. Bone marrow chimera experiments using SmoKO donor cells showed that control chimera mice transplanted with SmoKO bone marrow donor cells exhibited a loss of ulcer repair, and transplantation of control bone marrow donor cells to SmoKO mice rescued epithelial cell regeneration. Histamine-stimulated Shh secretion in human organoid/macrophage co-cultures resulted in macrophage migration toward the gastric epithelium, a response that was blocked with Smo inhibitor Vismodegib. Shh-induced macrophage migration was mediated by AKT signaling. In conclusion, Shh signaling acts as a macrophage chemoattractant via a Smo-dependent mechanism during gastric epithelial regeneration in response to injury.

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.

Role of metaplasia during gastric regeneration

Spasmolytic polypeptide/trefoil factor 2 (TFF2)-expressing metaplasia (SPEM) is a mucous-secreting reparative lineage that emerges at the ulcer margin in response to gastric injury. Under conditions of chronic inflammation with parietal cell loss, SPEM has been found to emerge and evolve into neoplasia. Cluster-of-differentiation gene 44 (CD44) is known to coordinate normal and metaplastic epithelial cell proliferation. In particular, CD44 variant isoform 9 (CD44v9) associates with the cystine-glutamate transporter xCT, stabilizes the protein, and provides defense against reactive oxygen species (ROS). xCT stabilization by CD44v9 leads to defense against ROS by cystine uptake, glutathione (GSH) synthesis, and maintenance of the redox balance within the intracellular environment. Furthermore, p38 signaling is a known downstream ROS target, leading to diminished cell proliferation and migration, two vital processes of gastric epithelial repair. CD44v9 emerges during repair of the gastric epithelium after injury, where it is coexpressed with other markers of SPEM. The regulatory mechanisms for the emergence of CD44v9 and the role of CD44v9 during the process of gastric epithelial regeneration are largely unknown. Inflammation and M2 macrophage infiltration have recently been demonstrated to play key roles in the induction of SPEM after injury. The following review proposes new insights into the functional role of metaplasia in the process of gastric regeneration in response to ulceration. Our insights are extrapolated from documented studies reporting oxyntic atrophy and SPEM development and our current unpublished findings using the acetic acid-induced gastric injury model.

Immunohistochemical Studies of Age-Related Changes in Cell Proliferation and Angiogenesis during the Healing of Acetic Acid-Induced Gastric Ulcers in Rats

Cell proliferation and angiogenesis are of utmost importance for healing to take place. The KI67 and EGFR proteins are markers of cell proliferation, while CD31 and factor VIII are markers of angiogenesis. To elucidate the mechanism responsible for delayed healing of the gastric injury in old age, we analyzed the expression of these markers in rats of different months during the healing of an acetic acid-induced gastric ulcer. Male Wistar rats (aged 3, 6, 12, and 18 months) divided into four groups, according to their ages, formed the experimental animals. Stomach tissue samples were collected on days 3, 7, 14, and 21 after induction for assessment of ulcer healing. The area of gastric mucosa healed was inversely proportional to age. The expression of markers of proliferation (KI67 and EGFR) and angiogenesis (factor VIII and CD31) decreased significantly (p < 0.05) in older rats when compared with younger ones (3 months > six months > 12 months > 18 months) on days 7, 14, and 21 after induction of gastric ulcer. This study revealed that the slower gastric ulcer healing rate in older rats might be due to reduced epithelial cell proliferation and angiogenic activities.

CD44 variant isoform 9 emerges in response to injury and contributes to the regeneration of the gastric epithelium

The CD44 gene encodes several protein isoforms due to alternative splicing and post translational modifications. Given that CD44 variant isoform 9 (CD44v9) is expressed within Spasmolytic Polypeptide/TFF2-Expressing Metaplasia (SPEM) glands during repair, CD44v9 may be play a funcitonal role during the process of regeneration of the gastric epithelium. Here we hypothesize that CD44v9 marks a regenerative cell lineage responsive to infiltrating macrophages during regeneration of the gastric epithelium. Ulcers were induced in CD44-deficient (CD44KO) and C57BL/6 (BL6) mice by a localized application of acetic acid to the serosal surface of the stomach. Gastric organoids expressing CD44v9 were derived from mouse stomachs and transplanted at the ulcer site of CD44KO mice. Ulcers, CD44v9 expression, proliferation and histology were measured 1, 3, 5 and 7-days post-injury. Human-derived gastric organoids were generated from stomach tissue collected from elderly (>55 years) or young (14-20 years) patients. Organoids were transplanted into the stomachs of NOD scid gamma (NSG) mice at the site of injury. Gastric injury was induced in NRG-SGM3 (NRGS) mice harboring human-derived immune cells (hnNRGS) and the immune profile anlayzed by CyTOF. CD44v9 expression emerged within regenerating glands the ulcer margin in response to injury. While ulcers in BL6 mice healed within 7-days post-injury, CD44KO mice exhibited loss of repair and epithelial regeneration. Ulcer healing was promoted in CD44KO mice by transplanted CD55v9-expressing gastric organoids. NSG mice exhibited loss of CD44v9 expression and gastric repair. Transplantation of human-derived gastric organoids from young, but not aged stomachs promoted repair in NSG mouse stomachs in response to injury. Finally, compared to NRGS mice, huNRGS animals exhibited reduced ulcer sizes, an infiltration of human CD162+ macrophages and an emergence of CD44v9 expression in SPEM. Thus, during repair of the gastic epithelium CD44v9 emerges within a regenerative cell lineage that coincides with macrophage inflitration within the injured mucosa. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cathelicidin-encoding Lactococcus lactis promotes mucosal repair in murine experimental colitis

BACKGROUND AND AIM

The preventive effect of intrarectal administration of mouse cathelicidin (mCRAMP) and oral administration of mCRAMP-encoding Lactococcus lactis (N4I) has been shown in murine experimental colitis. It is pivotal to understand the ability of N4I whether it can promote mucosal repair in existing colitis.

METHODS

Mice with dextran sulfate sodium-induced ulcerative colitis (UC) were treated orally with L. lactis or its transformed strain with or without nisin induction. The body weight, clinical symptoms, and histological changes of colonic tissues were determined. Sulfasalazine was used as a reference drug. Young adult mouse colon cells were used to further elucidate the direct action and possible mechanisms of mCRAMP to promote colonic wound repair.

RESULTS

Results showed that N4I could improve the clinical symptoms, maintain crypt integrity and preserve mucus-secreting layer in colitis animals. The preparation also could prevent cell death and promote cell proliferation. In contrast, effective dose of sulfasalazine only alleviated clinical symptoms but not the mucosal damage and repair in the colon. In vitro study further showed that mCRAMP could directly promote wound repair by accelerating cell migration but not cell proliferation through the GPCR/MAPK pathway.

CONCLUSIONS

mCRAMP-encoding L. lactis could be a potential therapeutic preparation better than the traditional anti-inflammatory agent in the treatment of UC.

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.

Whey protein concentrate enhances intestinal integrity and influences transforming growth factor-β1 and mitogen-activated protein kinase signalling pathways in piglets after lipopolysaccharide challenge

Whey protein concentrate (WPC) has been reported to have protective effects on the intestinal barrier. However, the molecular mechanisms involved are not fully elucidated. Transforming growth factor-β1 (TGF-β1) is an important component in the WPC, but whether TGF-β1 plays a role in these processes is not clear. The aim of this study was to investigate the protective effects of WPC on the intestinal epithelial barrier as well as whether TGF-β1 is involved in these protection processes in a piglet model after lipopolysaccharide (LPS) challenge. In total, eighteen weanling pigs were randomly allocated to one of the following three treatment groups: (1) non-challenged control and control diet; (2) LPS-challenged control and control diet; (3) LPS+5 %WPC diet. After 19 d of feeding with control or 5 %WPC diets, pigs were injected with LPS or saline. At 4 h after injection, pigs were killed to harvest jejunal samples. The results showed that WPC improved (P<0·05) intestinal morphology, as indicated by greater villus height and villus height:crypt depth ratio, and intestinal barrier function, which was reflected by increased transepithelial electrical resistance and decreased mucosal-to-serosal paracellular flux of dextran (4 kDa), compared with the LPS group. Moreover, WPC prevented the LPS-induced decrease (P<0·05) in claudin-1, occludin and zonula occludens-1 expressions in the jejunal mucosae. WPC also attenuated intestinal inflammation, indicated by decreased (P<0·05) mRNA expressions of TNF-α, IL-6, IL-8 and IL-1β. Supplementation with WPC also increased (P<0·05) TGF-β1 protein, phosphorylated-Smad2 expression and Smad4 and Smad7 mRNA expressions and decreased (P<0·05) the ratios of the phosphorylated to total c-jun N-terminal kinase (JNK) and p38 (phospho-JNK:JNK and p-p38:p38), whereas it increased (P<0·05) the ratio of extracellular signal-regulated kinase (ERK) (phospho-ERK:ERK). Collectively, these results suggest that dietary inclusion of WPC attenuates the LPS-induced intestinal injury by improving mucosal barrier function, alleviating intestinal inflammation and influencing TGF-β1 canonical Smad and mitogen-activated protein kinase signalling pathways.

Protective Factors of the Gastric and Duodenal Mucosa: An Overview

The structural and functional integrity of the gastric and duodenal mucosa represents equilibrium between aggressive factors and protective mechanisms. Mucus-buffers-phospholipid layer as pre-epithelial barrier, enhanced by prostaglandins and epidermal growth factor, remains a vanguard of mucosal protection. It maintains a neutral pH at the surface epithelial luminal interface, facing luminal pH dropping to 1.0, i.e., hydrogen ion concentration gradient equal 1,000,000. The surface epithelial cells, elaborating mucins, buffers, phospholipids, prostaglandins, trefoil peptides, peptide growth factor and their receptors, heat shock proteins, cathelicidins, and β-defensins form the second line of defense. Endothelium exerts mucosal protection through production of potent vasodilators like nitric oxide and prostacyclins and through release of angiogenic growth factors, securing adequate blood flow and representing the third and an ultimate line of mucosal protection. This microcirculation is instrumental for supply of oxygen, nitric oxide, hydrogen sulfide and removal of ad hoc generated toxic substances as well as for continuous mucosal cell renewal from progenitor cells, secured by growth factors accompanied by survivin preventing early apoptosis.

Confocal laser endomicroscopy: a new gold standard for the assessment of mucosal healing in ulcerative colitis

BACKGROUND AND AIM

Endoscopic assessment of mucosal healing in ulcerative colitis (UC) is increasingly accepted as a measure of disease activity, therapeutic goal, and the key prognostic indicator. While regular endoscopy evaluates appearance of the mucosal surface, confocal laser endomicroscopy (CLE) enables in vivo visualization of subepithelial mucosa at 1000× magnification during ongoing endoscopy. Our aims were to determine using CLE whether endoscopically normal appearing colonic mucosa in patients with UC in remission (UC-IR) has fully regenerated mucosal structures, resolved inflammation, and to identify the mechanisms.

METHODS

Twelve patients (six controls and six with UC-IR) underwent colonoscopy using CLE and intravenous fluorescein infusion. During colonoscopy, CLE images of colonic mucosa and conventional mucosal biopsies were obtained and evaluated using image-analysis systems. We quantified; (i) regeneration of colonic crypts and blood microvessels; (ii) cyclooxygenase 2 (COX2) expression; (iii) mitochondrial DNA (mtDNA) mutations; (iv) inflammatory infiltration; and (v) vascular permeability (VP).

RESULTS

In control subjects, CLE demonstrated normal colonic crypts and microvasculature. COX2 expression was minimal, and < 7% crypts showed mtDNA mutations. Colonic mucosa of UC-IR patients had impaired and distorted crypt regeneration, increased COX2, 69% crypts with mtDNA mutations, persistent inflammation, and abnormal vascular architecture with increased VP (all P < 0.001 vs normal mucosa).

CONCLUSIONS

(i) Endoscopically normal appearing colonic mucosa of patients with UC-IR remains abnormal: CLE demonstrates impaired crypt regeneration, persistent inflammation, distinct abnormalities in angioarchitecture and increased vascular permeability; molecular imaging showed increased COX2 and mtDNA mutations; (ii) CLE may serve as a new gold standard for the assessment of mucosal healing in UC.

The role of growth factors in intestinal regeneration and repair in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating intestinal disease resulting in major neonatal morbidity and mortality. The pathology is poorly understood, and the means of preventing and treating NEC are limited. Several endogenous growth factors have been identified as having important roles in intestinal growth as well as aiding intestinal repair from injury or inflammation. In this review, we will discuss several growth factors as mediators of intestinal regeneration and repair as well as potential therapeutic agents for NEC.

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.

Prospective single-arm trial of two-week rabeprazole treatment for ulcer healing after gastric endoscopic submucosal dissection

AIM

Endoscopic submucosal dissection (ESD) causes artificial ulcers, and there is no consensus regarding the degree of healing in ESD-induced ulcers or the optimal duration of proton pump inhibitor (PPI) treatment. The aim of the present study was to investigate the healing rates of post-ESD ulcers in response to the protective effect of 2-week PPI treatment.

METHODS

Between February 2007 and March 2010, 75 patients/75 lesions and 55 patients/55 lesions were enrolled as interim and per-protocol groups, respectively. All patients were prescribed rabeprazole (10 mg/day) orally for 16 days beginning on the day before ESD. Follow-up endoscopy was carried out 8 weeks after ESD to evaluate ulcer healing. The primary end-point was the healing rate of post-ESD ulcers at 8 weeks after ESD. Secondary end-points were the rate of post-ESD bleeding with emergency endoscopy and the rate of other severe adverse effects during the study period.

RESULTS

The transitional rate to scarring-stage ulcers was 80.0% (44/55). Location in the lesser curve and large resected size (>40 mm) were statistically significant predictors for delayed ulcer healing by univariate analysis and the latter was still significant by the multivariate analysis. Post-ESD bleeding occurred within 2 weeks in two cases (2.7%), but both cases were successfully managed with endoscopic hemostasis only. Severe adverse effects did not occur.

CONCLUSIONS

Two-week administration of PPI for post-ESD gastric ulcers may be sufficient to aid healing without increasing any adverse effects in cases where there are no possible deteriorating factors on ulcer healing, although large resection and/or resection in the lesser curve may result in delayed healing even after 8 weeks of ESD.

Krüppel-like factor 5 protects against dextran sulfate sodium-induced colonic injury in mice by promoting epithelial repair

BACKGROUND & AIMS

Krüppel-like factor 5 (KLF5) is a transcription factor that promotes proliferation, is highly expressed in dividing crypt cells of the gastrointestinal epithelium, and is induced by various stress stimuli. We sought to determine the role of KLF5 in colonic inflammation and recovery by studying mice with dextran sulfate sodium (DSS)-induced colitis.

METHODS

Wild-type (WT) and Klf5(+/-) mice were given DSS in the drinking water to induce colitis. For recovery experiments, mice were given normal drinking water for 5 days after DSS administration. The extent of colitis was determined using established clinical and histological scoring systems. Immunohistochemical and immunoblotting analyses were used to examine proliferation, migration, and expression of the epidermal growth factor receptor.

RESULTS

Klf5 expression was increased in colonic tissues of WT mice given DSS; induction of Klf5 was downstream of mitogen-activated protein kinase signaling. In DSS-induced colitis, Klf5(+/-) mice exhibited greater sensitivity to DSS than WT mice, with significantly higher clinical and histological colitis scores. In recovery experiments, Klf5(+/-) mice showed poor recovery, with continued weight loss and higher mortality than WT mice. Klf5(+/-) mice from the recovery period had reduced epithelial proliferation and cell migration at sites of ulceration compared to WT mice; these reductions correlated with reduced expression of epidermal growth factor receptor.

CONCLUSIONS

Epithelial repair is an important aspect of recovery from DSS-induced colitis. The transcription factor KLF5 regulates mucosal healing through its effects on epithelial proliferation and migration.

Can we protect the gut in critical illness? The role of growth factors and other novel approaches

The intestine plays a central role in the pathophysiology of critical illness and is frequently called the "motor" of the systemic inflammatory response. Perturbations to the intestinal barrier can lead to distant organ damage and multiple organ failure. Therefore, identifying ways to preserve intestinal integrity may be of paramount importance. Growth factors and other peptides have emerged as potential tools for modulation of intestinal inflammation and repair due to their roles in cellular proliferation, differentiation, migration, and survival. This review examines the involvement of growth factors and other peptides in intestinal epithelial repair during critical illness and their potential use as therapeutic targets.

Immunomodulatory activity of fucoidan against aspirin-induced gastric mucosal damage in rats

Gastric ulcers and related complications associated with the use of non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin, represent a major global health problem. In the present study, we investigate the immunological activity of fucoidan against aspirin-induced gastric mucosal damage in rats. Thirty-six rats were randomly divided into the following, normal (Carboxy methyl cellulose 0.05 %), aspirin (Asp-400mg/kg) treated, fucoidan alone (Fu-0.02 g/kg, daily for 14 days) and Fu+Asp. Cytokines, total nitrite and nitrate (NOx) analysis and tissue localization of Cyclooxygenase 1, 2 and epidermal growth factor receptor (EGFR) were done using Elisa and immunohistochemistry respectively. Histopathology of gastric tissue, collagen deposition was performed using Hematoxylin and Eosin and Masson's trichrome were performed. Treatment of rats with a single dose of aspirin (400mg/kg, orally) led to significant alterations in the levels of total nitrite and nitrate (NOx), interleukins (IL-4, 6, 10, 12), tumor necrosis factor (TNF-α), and interferon gamma (IFN-γ). Notably, collagen deposition in glandular tissue and localization of cyclooxygenase 1, 2, and epidermal growth factor were considerably affected in aspirin-treated rats. These severities were prevented to a significant extent in rats pretreated with fucoidan (0.02 g/kg/day for two weeks orally). Our findings collectively indicate that the gastro-protective effect of fucoidan against aspirin-induced ulceration in rats is mediated through its immunomodulatory properties.

A matched case-control study of a novel Acid-pump antagonist and proton-pump inhibitor for the treatment of iatrogenic ulcers caused by endoscopic submucosal dissection

BACKGROUND/AIMS

Revaprazan, a novel acid-pump antagonist, and proton-pump inhibitors (PPIs) have pH-independent effects on ulcer healing. The addition of a PPI promotes the cell restitution rate as well as vessel regeneration and maturation for ulcer repair. Revaprazan is known to protect the mucosa by increasing the prostaglandin concentration.

METHODS

We reviewed the medical records of patients who underwent endoscopic submucosal dissection (ESD) for gastric neoplasia at Yeungnam University Hospital between January 2008 and May 2009. We conducted a matched case-control study to compare the healing rates effected by revaprazan and rabeprazole.

RESULTS

Each group consisted of 30 patients. The baseline characteristics did not differ significantly between the two groups. Stage S1 disease was observed in 97% and 100% of patients after 8 weeks of treatment in the revaprazan and rabeprazole groups, respectively. In the revaprazan group, only one patient had stage H2 disease: a 54-year-old man with a 5.5-cm lesion after ESD of the ulcer, type IIa early gastric cancer, and adenocarcinoma. No serious adverse effects occurred during the treatment period in either group.

CONCLUSIONS

The safety and efficacy profiles of revaprazan and rabeprazole are similar for the treatment of ESD-induced ulcers.

Degree of healing and healing-associated factors of endoscopic submucosal dissection-induced ulcers after pantoprazole therapy for 4 weeks

BACKGROUND

There is no consensus regarding the degree of healing of endoscopic submucosal dissection (ESD)-induced ulcers and the optimal duration of proton pump inhibitor (PPI) treatment.

AIM

To evaluate the degree of healing and the factors associated with healing of ESD-induced ulcers after PPI therapy for 4 weeks.

METHODS

Fifty-six patients who underwent complete ESD for adenoma or early gastric cancer were enrolled. All patients underwent follow-up endoscopy to evaluate the degree of ulcer healing after pantoprazole therapy (40 mg per day) for 4 weeks. We evaluated change in size of ESD-induced ulcers between baseline and 4 weeks, and correlated relevant factors with degree of healing of small and large ulcers.

RESULTS

At follow-up, 28 (50%) patients had large ulcers (area > 10 mm(2)). Ulcer size at 4 weeks was closely correlated with initial ulcer size (P < 0.001) and abruptly increased when initial ulcer size was larger than 4 cm. Comorbidity, procedure time, and initial specimen size were significantly associated with healing rate, but multivariate analysis showed that initial ulcer size was the only significant parameter (P < 0.015).

CONCLUSIONS

Healing degree of ESD-induced ulcers at 4 weeks is dependent on initial ulcer size, indicating that duration of treatment with PPI should be dependent on initial ulcer size.

Sucralfate modulates uPAR and EGFR expression in an experimental rat model of cervicitis

Sucralfate is a drug used in the treatment of gastric and duodenal ulcer; it is cytoprotective and able to increase the bioavailability of several growth factors, modulating the wound healing process. In this study we tested the possible therapeutic effect of Sucralfate in the treatment of ulcerative lesions occurring in uterine cervix; to investigate such effect we used an experimental rat model of cervicitis in which the uPAR and EGFR expression were evaluated. Cervicitis was induced in wild and ovariectomized Wistar female rats by an acetic acid-soaked tampon. The animals were divided into two main groups (4 and 7 days) and Sucralfate was administered topically until the day they were sacrificed. In order to distinguish physiological and drug-induced healing, quantitative and qualitative uPAR and EGFR expression were evaluated by using Western blot and Immunohistochemistry techniques. Western blot analysis demonstrated an increased expression of both receptors after 4 days from wounding in wild and ovariectomized animals. In particular in ovariectomized animals the expression of uPAR and EGFR increased after 4 days while it reduced following the administration of Sucralfate. In wild rats the same was observed for uPAR expression, while EGFR was different; in fact, its expression increased significantly at day 4 in the animals treated with the drug and only at day 7 in those untreated. Immunohistochemistry highlighted a noteworthy epithelial colocalization of EGFR and uPAR after 4 days in the animals treated with Sucralfate. We conclude that Sucralfate can promote the healing of ulcerative cervicitis and moreover, it reduces the normal healing time because of its modulatory property on uPAR and EGFR expression.

Gastric mucosal defense and cytoprotection: bench to bedside

The gastric mucosa maintains structural integrity and function despite continuous exposure to noxious factors, including 0.1 mol/L HCl and pepsin, that are capable of digesting tissue. Under normal conditions, mucosal integrity is maintained by defense mechanisms, which include preepithelial factors (mucus-bicarbonate-phospholipid "barrier"), an epithelial "barrier" (surface epithelial cells connected by tight junctions and generating bicarbonate, mucus, phospholipids, trefoil peptides, prostaglandins (PGs), and heat shock proteins), continuous cell renewal accomplished by proliferation of progenitor cells (regulated by growth factors, PGE(2) and survivin), continuous blood flow through mucosal microvessels, an endothelial "barrier," sensory innervation, and generation of PGs and nitric oxide. Mucosal injury may occur when noxious factors "overwhelm" an intact mucosal defense or when the mucosal defense is impaired. We review basic components of gastric mucosal defense and discuss conditions in which mucosal injury is directly related to impairment in mucosal defense, focusing on disorders with important clinical sequelae: nonsteroidal anti-inflammatory drug (NSAID)-associated injury, which is primarily related to inhibition of cyclooxygenase (COX)-mediated PG synthesis, and stress-related mucosal disease (SRMD), which occurs with local ischemia. The annual incidence of NSAID-associated upper gastrointestinal (GI) complications such as bleeding is approximately 1%-1.5%; and reductions in these complications have been demonstrated with misoprostol, proton pump inhibitors (PPIs) (only documented in high-risk patients), and COX-2 selective inhibitors. Clinically significant bleeding from SRMD is relatively uncommon with modern intensive care. Pharmacologic therapy with antisecretory drugs may be used in high-risk patients (eg, mechanical ventilation >or=48 hours), although the absolute risk reduction is small, and a decrease in mortality is not documented.

Role of epidermal growth factor and other growth factors in the prevention of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) presents as the most common gastrointestinal emergency during the neonatal period and results in ulceration and necrosis of the distal small intestine and proximal colon. The etiology of NEC remains unknown. Based on the complexity of gut development, multiple growth factors and cytokines may be needed to synergistically support the developing gut. Epidermal growth factor (EGF) has been shown to play an important role in intestinal cell restitution, proliferation, and maturation. EGF is found in abundant quantities in many fluids, including the gastrointestinal tract, amniotic fluid, breast milk, and saliva. Preliminary clinical trials using EGF in neonates diagnosed with NEC have been shown to promote repair of intestinal epithelium. Additionally, other growth factors are also emerging as potential treatment modalities, including erythropoietin, granulocyte colony stimulating factor, and heparin-binding EGF. The role of EGF and other growth factors in the pathogenesis and prevention of NEC will be reviewed.

Healing properties of malabaricone B and malabaricone C, against indomethacin-induced gastric ulceration and mechanism of action

The healing activity of malabaricone B and malabaricone C, the major antioxidant constituents of the spice Myristica malabarica against the indomethacin-induced gastric ulceration in mice has been studied. The histological indices revealed maximum ulceration on the 3rd day after indomethacin administration, which was effectively healed by malabaricone B, malabaricone C (each 10 mg/kg body weight/day) and omeprazole (3 mg/kg body weight/day) for 3 days. Compared to the untreated ulcerated mice, treatment with malabaricone B, malabaricone C and omeprazole reduced the ulcer indices by 60.3% (P<0.01), 88.4% and 86.1% respectively (P<0.001). All the test samples accelerated ulcer healing than observed in natural recovery even after 7 days. Stomach ulceration reduced the total antioxidant status of plasma by 41% (P<0.05), which was significantly increased by malabaricone B (36%, P<0.01), malabaricone C (61%, P<0.001) and omeprazole (53%, P<0.001). Compared to the ulcerated untreated mice, those treated with malabaricone B reduced the levels of thiobarbituric acid reactive substances and protein carbonyls by 17% and approximately 34% respectively (P<0.05), while malabaricone C and omeprazole reduced the parameters almost equally (approximately 30%, P<0.01, and approximately 40%, P<0.01 respectively). Likewise, all the test samples reduced the oxidation of protein and non-protein thiols significantly (P<0.05). The antioxidant activity of the test samples could partly account their healing capacities. However, the differential potency of them was explainable by considering their relative abilities to modulate mucin secretion, PGE(2) synthesis and expression of EGF receptor and COX isoforms, malabaricone C being most effective in controlling all these factors.

MEK/ERK regulates adherens junctions and migration through Rac1

Polyamine depletion with the ornithine decarboxylase inhibitor alpha-difluoromethyl ornithine (DFMO), prevents Rac1 activation causing the formation of a thick actin cortex at the cell periphery and inhibits migration of intestinal epithelial cells. In the present study, we demonstrate that MEK activation by EGF increased Rac1 activation, dissociation of intercellular contacts, and migration in both control and polyamine-depleted cells, while U0126, a specific inhibitor of MEK1, prevented disruption of junctions as well as EGF-induced Rac1 activation. Constitutively active MEK1 (CA-MEK) expression altered cell-cell contacts in control and polyamine depleted cells. The expression of constitutively active Rac1 (CA-Rac1) restored beta-catenin to the cell periphery and prevented the formation of actin cortex and caused the appearance of F-actin stress fibers in polyamine-depleted cells. Inhibition of Rac activation by NSC23766, a specific inhibitor of Tiam1, an upstream guanidine nucleotide exchange factor for Rac1, reproduced the beta-catenin localization and actin structure of polyamine-depleted cells. Tiam1 localized more extensively with beta-catenin at the cell periphery in CA-Rac1 cells compared to vector cells. Polyamine depletion decreased the expression of E-cadherin to a greater extent compared to beta-catenin. Subcellular fractionation further confirmed our immuno-localization and western blotting observations. These data suggest that EGF acting through MEK1/ERK to activate Rac1 regulates cell-cell contacts. Thus, decreased migration in polyamine depleted cells may be due to the inhibition of Tiam1 activation of Rac1 and the subsequent decreased expression of beta-catenin and E-cadherin leading to reduced cell-cell contacts.

Novel roles of local insulin-like growth factor-1 activation in gastric ulcer healing: promotes actin polymerization, cell proliferation, re-epithelialization, and induces cyclooxygenase-2 in a phosphatidylinositol 3-kinase-dependent manner

The precise role of insulin-like growth factor (IGF)-1 in gastric ulcer healing is unknown. In experimental rat gastric ulcers, we examined expression of IGF-1 mRNA and protein by reverse transcriptase-polymerase chain reaction or enzyme-linked immunosorbent assay and immunostaining, respectively. In cultured rat gastric epithelial RGM1 cells, we examined effects of exogenous IGF-1 on cell migration, re-epithelialization, and proliferation-essential components of ulcer healing. We also examined whether IGF-1 induces cyclooxygenase (COX)-2 expression and determined the role of phosphatidylinositol 3-kinase and mitogen-activated protein kinase signaling pathways in mediating IGF-1 actions. Gastric ulceration triggered an approximately threefold increase in IGF-1 expression in epithelial cells of the ulcer margins (P < 0.001 versus control), especially in cells re-epithelizing granulation tissue and in mucosa in proximity to the ulcer margin. Treatment of RGM1 cells with IGF-1 caused a dramatic increase in actin polymerization, an eightfold increase in cell migration (P < 0.001), a 195% increase in cell proliferation (P < 0.05), and a sixfold increase in COX-2 expression (P < 0.01). Inhibitor of phosphatidylinositol 3-kinase abolished IGF-1-induced RGM1 cell migration and proliferation, actin polymerization, and COX-2 expression. The up-regulation of IGF-1 in gastric ulcer margin accelerates gastric ulcer healing by promoting cell re-epithelization, proliferation, and COX-2 expression via the phosphatidylinositol 3-kinase pathway.

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.

The cationic host defense peptide rCRAMP promotes gastric ulcer healing in rats

Cathelicidin, a cationic host defense peptide, has been shown to promote cutaneous wound repair and reaches high levels in the gastric mucosa during infection and inflammation. Therefore, we investigated whether this peptide contributes to gastric ulcer healing in rats. Ulcer induction increased the expression of rat cathelicidin rCRAMP in the gastric mucosa. Further increase in expression of rCRAMP by local injection of rCRAMP-encoding plasmid promoted ulcer healing by enhancing cell proliferation and angiogenesis. rCRAMP directly stimulated proliferation of cultured rat gastric epithelial cells (RGM-1), which was abolished by inhibitors of matrix metalloproteinase (MMP), epidermal growth factor receptors (EGFR) tyrosine kinase, or mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase. rCRAMP also increased EGFR and ERK1/2 phosphorylation via an MMP-dependent mechanism. Knockdown of transforming growth factor alpha (TGFalpha), which is a ligand of EGFR, by small interfering RNA completely nullified the mitogenic signals evoked by rCRAMP in RGM-1 cells. These findings suggest that rCRAMP exhibits prohealing activity in stomachs through TGFalpha-dependent transactivation of EGFR and its related signaling pathway to induce proliferation of gastric epithelial cells.

Effect of Anweitang on gastric ulcer and it mechanism in experimental rats

AIM: To investigate the mechanism of Anweitang in the improvement of gastric ulcer healing quality.

METHODS: Forty Wistar rats were randomly and averagely divided into group A, B, C and D. Acetic acid was used to establish the model of gastric ulcer in the rats of group B, C and D. The rats in group A and B were treated (ig) with normal saline while those in group C and D were treated (ig) with Anweitang and Ranitidine, respectively. Radioimmunoassay was used to determine the expression of serum epidermal growth factor (EGF), and immunohistochemistry was applied to detect the expression of EGF, EGF receptor, and transforming growth factor-β₁ (TGF-β₁) in the gastric mucosa.

RESULTS: In comparison with that in the group B, the expression of serum EGF was evidently enhanced in group C and D (1.12 ± 0.24, 0.99 ± 0.15 μg/L vs 0.52 ± 0.13 μg/L, P < 0.01), and serum EGF expression was also significantly different between group C and D (P < 0.01). Furthermore, the expression of mucosal EGF, EGFR and TGF-β₁ were markedly higher in group C and D than those in group B (EGF: 29.7% ± 1.9%, 26.5% ± 1.6% vs 18.4% ± 2.0%, P < 0.01; EGFR: 29.6% ± 2.6%, 25.9% ± 1.0% vs 20.4% ± 1.8%, P < 0.01; TGF-β₁: 67.0% ± 2.0%, 49.5% ± 1.1% vs 27.3% ± 1.0%, P < 0.01). There were also significant differences between group C and D in the expression of mucosal EGF, EGFR and TGF-β₁ (all P < 0.01).

CONCLUSION: Anweitang may improve the healing quality of gastric ulcer by enhancing the expression serum EGF and mucosal EGF, EGFR, and TGF-β₁.

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.

An overview of acetic acid ulcer models--the history and state of the art of peptic ulcer research

Four types of experimental chronic ulcer models, named acetic acid ulcer models, have been developed to examine the healing process of peptic ulcers, screen anti-ulcer drugs, and better evaluate the adverse effects of various anti-inflammatory drugs on the gastrointestinal mucosa. The model easily and reliably produces round, deep ulcers in the stomach and duodenum, allowing acetic acid ulcer production in mice, rats, Mongolian gerbils, guinea pigs, cats, dogs, miniature pigs, and monkeys. These ulcer models highly resemble human ulcers in terms of both pathological features and healing process. The models have been established over the past 35 years and are now used throughout the world by basic and clinical scientists. One of the characteristic features of acetic acid ulcers in rats is the spontaneous relapse of healed ulcers >100 d after ulceration, an endoscopically confirmed phenomenon. Indomethacin significantly delays the healing of acetic acid ulcers, probably by reducing endogenous prostaglandins and inhibiting angiogenesis in ulcerated tissue. Helicobacter pylori significantly delays healing of acetic acid ulcers and causes relapse of healed ulcers at a high incidence in Mongolian gerbils. Anti-secretory drugs (e.g. omeprazole), prostaglandin analogs, mucosal defense agents (e.g. sucralfate), and various growth factors all significantly enhance healing of acetic acid ulcers. Gene therapy with epidermal growth factor and vascular endothelial growth factor applied to the base of acetic acid ulcers in rats is effective in enhancing ulcer healing. Since an inhibitor of nitric oxide syntase prevents ulcer healing, nitric oxide might be involved in the mechanism underlying ulcer healing. We conclude that acetic acid ulcer models are quite useful for various studies related to peptic ulcers.

Global analysis of gene expression in gastric ischemia-reperfusion: a future therapeutic direction for mucosal protective drugs

Gastric ischemia-reperfusion is a relatively common condition leading to mucosal injury and may affect mucosal repair via modulating the gene expression of growth factors. Therefore, precise understanding of the molecular mechanism of ischemia or ischemia-reperfusion may lead to the discovery of new mucosal protective drugs. DNA microarray analysis followed by powerful data analysis has the potential to uncover previously undescribed genes involved in gastric injury and lead to an increased understanding of gastric mucosal cytoprotection. We introduced the laser-assisted microdissection to obtain cell-specific RNA from gastric mucosa in vivo and obtained sufficient amounts of cRNA for GeneChip analysis. This comprehensive approach enabled the simultaneous analysis of many genes, including transcriptional factors, as well as the generation of novel hypothesis on the mechanism of action of gastro-protective agents.

Cellular and molecular mechanisms of gastrointestinal ulcer healing

This paper reviews cellular and molecular mechanisms of gastrointestinal ulcer healing. Ulcer healing, a genetically programmed repair process, includes inflammation, cell proliferation, re-epithelialization, formation of granulation tissue, angiogenesis, interactions between various cells and the matrix and tissue remodeling, all resulting in scar formation. All these events are controlled by the cytokines and growth factors (EGF, PDGF, KGF, HGF, TGFbeta, VEGF, angiopoietins) and transcription factors activated by tissue injury in spatially and temporally coordinated manner. These growth factors trigger mitogenic, motogenic and survival pathways utilizing Ras, MAPK, PI-3K/Akt, PLC-gamma and Rho/Rac/actin signaling. Hypoxia activates pro-angiogenic genes (e.g., VEGF, angiopoietins) via HIF, while serum response factor (SRF) is critical for VEGF-induced angiogenesis, re-epithelialization and muscle restoration. EGF, its receptor, HGF and Cox2 are important for epithelial cell proliferation, migration re-epithelializaton and reconstruction of gastric glands. VEGF, angiopoietins, nitric oxide, endothelin and metalloproteinases are important for angiogenesis, vascular remodeling and mucosal regeneration within ulcer scar. Circulating progenitor cells are also important for ulcer healing. Local gene therapy with VEGF + Ang1 and/or SRF cDNAs dramatically accelerates esophageal and gastric ulcer healing and improves quality of mucosal restoration within ulcer scar. Future directions to accelerate and improve healing include the use of stem cells and tissue engineering.

Long-term omeprazole and esomeprazole treatment does not significantly increase gastric epithelial cell proliferation and epithelial growth factor receptor expression and has no effect on apoptosis and p53 expression

AIM: To study the effect of proton pump inhibitor (PPI) treatment on patients with reflux esophagitis and its in vivo effect on apoptosis, p53- and epidermal growth factor receptor (EGFR) expression.

METHODS: After informed consent was obtained, gastric biopsies of the antrum were taken from patients with reflux oesophagitis prior to and after 6 mo of 20 mg omeprazole (n = 14) or 40 mg esomeprazole (n = 12) therapy. Patients did not take any other medications known to affect the gastric mucosa. All patients were Helicobacter pylori negative as confirmed by rapid urease test and histology, respectively. Cell proliferation, apoptosis, EGFR, and p53 expression were measured by immunohistochemical techniques. At least 600 glandular epithelial cells were encountered and results were expressed as percentage of total cells counted. Was considered statistically significant.

RESULTS: Although there was a trend towards increase of cell proliferation and EGFR expression both in omeprazole and esomeprazole treated group, the difference was not statistically significant. Neither apoptosis nor p53 expression was affected.

CONCLUSION: Long-term PPI treatment does not significantly increase gastric epithelial cell proliferation and EGFR expression and has no effect on apoptosis and p53 expression.

Role of epidermal growth factor in the pathogenesis of neonatal necrotizing enterocolitis

Neonatal necrotizing enterocolitis (NEC) is an increasingly frequent condition encountered in premature infants for which the etiology is not well understood. Epidermal growth factor (EGF) is abundant in many fluids bathing the fetal and neonatal gastrointestinal tract, including amniotic fluid, saliva, and breast milk. EGF is acknowledged to be important for normal intestinal development as well as repair following injury to the gastrointestinal mucosa. There appears to be mounting evidence to support a possible link between deficient EGF production and the development of NEC. The relevant evidence for the role of EGF in intestinal development and mucosal repair, as well as its potential involvement in the genesis of NEC will be reviewed.

Proton pump inhibitor co-therapy normalizes the increased cell turnover of the gastric mucosa both in NSAID and selective COX-2 users

Proton pump inhibitor (PPI) co-therapy is considered the best strategy in preventing gastrointestinal complications during non-steroidal anti-inflammatory drug (NSAID) treatment, but there is limited information available on its effect on gastric mucosal cell kinetics. To evaluate the effect of PPI co-therapy on gastric mucosa we investigated epithelial cell proliferation, apoptosis, epithelial growth factor receptor (EGFR) and p53 expression in patients on chronic non-selective NSAID or cyclooxygenase-2 selective inhibitor (COX-2) treatment. Gastric biopsies of the antrum were taken from 10-10 patients on chronic NSAID and COX-2, therapy prior and after 6 months PPI co-therapy, and 10 controls without any treatment. Cell proliferation, apoptosis, EGFR and p53 expression were measured by immunohistochemistry. At least 600 glandular epithel cells were encountered and results were expressed as % of total cells counted. We found increased cell proliferation in patients on chronic COX-2 but not on NSAID therapy. Patients on either NSAID or COX-2 therapy had an increased p53 and decreased EGFR expression. PPI therapy reversed not only the increased cell proliferation and p53 expression, but also the suppressed EGFR expression when administered as co-therapy. The fewer gastrointestinal side effects observed during chronic COX-2 therapy may partially be the result of the higher cell proliferation. This effect is not mediated by the EGFR pathway. PPI co-therapy normalizes the disturbed cell kinetics irrespective of NSAID treatment used.

Menadione protects gastric mucosa against ethanol-induced ulcers

Previous studies have shown a definite role of mitogen activated protein kinase (MAPK) and epidermal growth factors (EGF) in the maintenance and repair of gastric mucosa. The aim of this study is to investigate the effect of menadione, an activator of MAPK pathway, on gastric acid secretion and experimentally induced gastric ulcer in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with menadione (5 - 45 mg/kg, i.p.). The effect of orally administered menadione on ethanol-induced gastric ulcers was also examined. The level of gastric wall mucus, non-protein sulfhydryls (NP-SH) and myeloperoxidase (MPO) was measured in the glandular stomach of rats following ethanol-induced gastric lesions. There was a significant inhibition of gastric acid secretion in the menadione treated rats. Pretreatment of rats with menadione significantly protected gastric mucosa against ethanol-induced gastric lesion. A significant attenuation of ethanol-induced reduction of gastric wall mucus, depletion of NP-SH and increase in gastric MPO activity was also observed in menadione treated rats. In conclusion, this study clearly showed acid antisecretory and antiulcer activity of menadione. Further studies are warranted to determine the mechanism of antiacid and gastroprotective effect of menadione.

MEK1 restores migration of polyamine-depleted cells by retention and activation of Rac1 in the cytoplasm

We previously showed that polyamines are required for proliferation and migration both in vivo and in a cultured intestinal epithelial cell (IEC-6) model. Wounding of the IEC-6 monolayer induced transient ERK activation, which was further enhanced by EGF. EGF stimulated migration in control and polyamine-depleted cells, but the degree of stimulation was significantly less in polyamine-depleted cells. Inhibition of MEK1 inhibited basal as well as EGF-induced ERK activation and migration. Expression of constitutively active (CA)-MEK and dominant-negative (DN)-MEK had significant effects on F-actin structure. CA-MEK increased stress fiber and lamellipodia formation, while DN-MEK showed loss of stress fibers and abnormal actin cytoskeletal structure. Unlike EGF, CA-MEK significantly increased migration of both control and polyamine-depleted cells. The most important and significant finding in this study was that polyamine depletion caused localization of Rac1 and RhoA to the nuclear as well as perinuclear regions. Interestingly, CA-MEK completely reversed the subcellular distribution of Rac1 and RhoA proteins in polyamine-depleted cells. Polyamine depletion increased Rac1 in the nuclear fraction and decreased it in the cytoplasmic and membrane fractions of vector-transfected cells. CA-MEK prevented accumulation of Rac1 in the nucleus. Polyamine depletion significantly decreased Rac1 activity during 6-h migration in vector-transfected cells. Cells transfected with CA-MEK had almost identical levels of activated Rac1 in all three groups. These results suggest that polyamine depletion prevents activation of Rac1 and RhoA by sequestering them to the nucleus and that expression of constitutively active MEK reverses this effect, creating the cellular localization required for activation.

[Effect of Jianwei Yuyang Granules on expression of epidermal growth factor receptor in gastric mucosa of gastric ulcer patients]

OBJECTIVE

To observe the effect of Jianwei Yuyang Granules on the expression of epidermal growth factor receptor (EGFR) in the gastric mucosa of gastric ulcer patients.

METHODS

Sixty gastric ulcer patients (final diagnosis by gastroscope) were randomly divided into Jianwei Yuyang Granules treated group (JWYY group, n=30) and western medicine treated group (control group, n=30). Ten patients without gastric mucosa lesion were treated as normal control group. The expression of EGFR in the mucosa was tested by immunohistochemistry and RT-PCR.

RESULTS

Expression of EGFR and EGFR mRNA was not observed in patients without gastric mucosa lesion, and slight expression was observed in the edge of ulcer region of the gastric ulcer patients. The expression of EGFR and EGFR mRNA was increased in JWYY group and control group.

CONCLUSION

Jianwei Yuyang Granules enhances the expression of EGFR in the mucosa of gastric ulcer patients to prevent peptic ulcer recurrence.

Gastrin and interleukin-1beta stimulate growth factor secretion from cultured rabbit gastric parietal cells

The hormone gastrin stimulates proliferation of the gastric mucosa. Inflammation of the stomach is also associated with increased proliferation. The proliferative response is important in the reparative response to injury but can be deleterious by predisposing to the development of cancer. Parietal cells, but not the cells in the proliferative zone of the gastric glands, express the appropriate gastrin receptor. Parietal cells may mediate the trophic effects of gastrin by secreting other growth factors. The role of parietal cells in the proliferative responses has been examined in this study. Rabbit parietal cells were cultured with gastrin or the cytokine interleukin-1beta for 18 hours. The conditioned medium from gastrin or IL-1beta stimulated parietal cells increased proliferation of HeLa cells in an epidermal growth factor-receptor dependant manner. Gastrin and IL-1beta stimulated the secretion of heparin-binding epidermal growth factor and amphiregulin but not transforming growth factor-alpha from parietal cells. Combinations of gastrin and IL-1beta on growth factor secretion were synergistic. The protein kinase C inhibitor staurosporine abolished these stimulatory effects of gastrin and IL-1beta. Divergent effects on histamine-stimulated acid secretion were observed; 18 hours pre-treatment with gastrin enhanced acid secretion by 50% but IL-1beta inhibited acid secretion in both control and gastrin pre-treated parietal cells. The acid-secreting parietal cell plays a central role in the regulation of mucosal proliferation in gastric inflammation. Secretion of paracrine growth factors by parietal cells may be an important point of integration between the endocrine and inflammatory stimuli in determining mucosal responses to injury and inflammation.

Healing rate of EMR-induced ulcer in relation to the duration of treatment with omeprazole

BACKGROUND

Although EMR-induced ulcers heal faster and recur less often than noniatrogenic gastric ulcers, there is no consensus regarding the duration of therapy for these ulcers. This study prospectively evaluated healing of EMR-induced ulcers according to the duration of omeprazole therapy.

METHODS

A total of 69 patients were randomly assigned, after EMR, to treatment with omeprazole (20 mg per day) for 7 days (1-week group) or with omeprazole (20 mg per day) for 28 days (4-week group). Four weeks after EMR, ulcer size and stage were compared with those of the initial EMR-induced ulcer. Each patient kept a daily diary of drugs consumed and ulcer-related symptoms during the 4-week period after EMR.

RESULTS

Thirty-four patients were randomized to the 4-week group, and 26 were randomized to the 1-week group. No significant differences were observed between the two groups at 4 weeks after EMR in terms of ulcer reduction ratio (p=0.29) or stage (p=0.11). In addition, no difference was observed between the two groups with respect to ulcer-related symptoms or use of additional gastric-coating medication (p=0.48).

CONCLUSIONS

For EMR-induced ulcer, treatment with omeprazole for 1 week is equivalent to treatment for 4 weeks. Short-term therapy with omeprazole can be considered for EMR-induced ulcer.

Effect of adrenomedullin on c-Met receptor expression after reserpine-induced gastric damage in the rat

Here, we show an increase in c-Met receptor expression during reserpine-induced gastric damage in the rat, as assessed by immunohistochemistry. Pretreatment of animals with adrenomedullin prevented this increase in c-Met expression. c-Met immunoreactivity was localized in gastric glands. c-Met immunoreactivity was associated with increased phosphorylation of c-Met receptor and extracellular signal-regulated kinase (ERK(1/2)). Our results suggest that both adrenomedullin and c-Met act as parallel defence mechanisms during pharmacologically induced gastric mucosa injury.

Expression of functional neurokinin-1 receptors in regenerative glands during gastric wound healing in rodents

BACKGROUND & AIMS

Although functions of the neurokinin-1 receptor have been well explored in neurogenic inflammation and immunoinflammatory responses, little is known about neurokinin-1 receptors during gastric wound healing. The aim of this study was to assess whether neurokinin-1 receptors play a role in gastric wound healing.

METHODS

In vitro neurokinin-1 receptor autoradiography and immunohistochemistry were performed to identify, locate, and quantify neurokinin-1 receptors during wound healing in rodents with cryoulcers in the gastric corpus and antrum. Moreover, to assess the functionality of these receptors, the effect of the neurokinin-1 receptor antagonist NKP608 on gastric wound healing was quantified in vivo in wild-type and cyclooxygenase-2(-/-) mice.

RESULTS

Regenerative glands of the mucosal ulcer margin of rat cryoulcers of the gastric corpus showed strong expression of neurokinin-1 receptors in binding studies between days 3 and 22, with little expression on days 29-84. In addition, strong immunoreactivity for neurokinin-1 receptors was detected on the cell membrane of these regenerative glands. Expression of neurokinin-1 receptors in regenerative glands was confirmed in the rat antrum and the mouse gastric corpus. Moreover, in vivo functional tests during gastric ulcer healing showed that cell proliferation in the regenerative epithelia of the ulcer margin was significantly decreased by NKP608 compared with placebo; furthermore, gastric ulcer healing was significantly delayed by NKP608 both in wild-type and cyclooxygenase-2(-/-) mice.

CONCLUSIONS

This report shows the time-limited overexpression of neurokinin-1 receptors in the mucosal repair tissue of the corpus and antrum. Our in vitro and in vivo data suggest that neurokinin-1 receptors are involved in gastric wound healing.

[An overview of acetic acid ulcer models and their utility for drug screening]

Since Takagi et al. reported an experimental chronic gastric ulcer model [acetic acid ulcers induced by submucosal injection of acetic acid (Type 1)], we further modified the methodology and subsequently devised three more models. The second model involves inducing ulcers by serosal application of an acetic acid solution (Type 2) and the third model achieves ulcer induction by intragastric application of an acetic acid solution (Type 3). The forth model was modification of the third model by giving the acetic acid solution and the same volume of air to make one ulcer in the stomach (Type 4). In general, animals accepted the procedures without problems and no undesirable effects were noticed. More importantly, this experimental animal model allows production of ulcers that highly resemble human ulcers in terms of both pathology and healing. Indeed, relapse is even endoscopically observed for 360 days after ulceration. The ulcers produced not only respond well to various anti-ulcer medications, such as antisecretory and mucosal protective drugs and growth factors, but also demonstrate appropriate responses to ulcerogenic agents such as NSAIDs. In addition, we have recently demonstrated that H. pylori infection resulted in delayed ulcer healing and recurrence of healed acetic acid ulcers induced in Mongolian gerbils. The present article gives a brief summary of the ulcer history before establishment of acetic acid ulcers and characteristic features of acetic acid ulcer, including both their merits and shortcomings.