Protective effect of epidermal growth factor in an experimental model of colitis in rats

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.

Novel Insights Into the Mechanism of GVHD-Induced Tissue Damage

Prophylaxis for and treatment of graft-versus-host disease (GVHD) are essential for successful allogeneic hematopoietic stem cell transplantation (allo-SCT) and mainly consist of immunosuppressants such as calcineurin inhibitors. However, profound immunosuppression can lead to tumor relapse and infectious complications, which emphasizes the necessity of developing novel management strategies for GVHD. Emerging evidence has revealed that tissue-specific mechanisms maintaining tissue homeostasis and promoting tissue tolerance to combat GVHD are damaged after allo-SCT, resulting in exacerbation and treatment refractoriness of GVHD. In the gastrointestinal tract, epithelial regeneration derived from intestinal stem cells (ISCs), a microenvironment that maintains healthy gut microbiota, and physical and chemical mucosal barrier functions against pathogens are damaged by conditioning regimens and/or GVHD. The administration of growth factors for cells that maintain intestinal homeostasis, such as interleukin-22 (IL-22) for ISCs, R-spondin 1 (R-Spo1) for ISCs and Paneth cells, and interleukin-25 (IL-25) for goblet cells, mitigates murine GVHD. In this review, we summarize recent advances in the understanding of GVHD-induced tissue damage and emerging strategies for the management of GVHD.

Facilitating resolution of life-threatening acute GVHD with human chorionic gonadotropin and epidermal growth factor

Acute graft-versus-host disease (aGVHD) is a potentially fatal complication of allogeneic hematopoietic cell transplantation that fails to improve with intense immunosuppression in some patients. We hypothesized that urinary-derived human chorionic gonadotropin (uhCG) could help facilitate resolution of life-threatening aGVHD when added as supportive care via 2 potential mechanisms: immunomodulation (akin to its role in pregnancy) and supplementation of epidermal growth factor (EGF; to aid in epithelial repair). In a phase 1 study, 26 participants received subcutaneous injections of uhCG in addition to standard immunosuppression (13 receiving initial therapy for high-risk aGVHD [according to the Minnesota criteria] and 13 receiving second-line therapy). Participants underwent serial blood testing for biomarkers of hormone response, immune modulation, and aGVHD activity on study. uhCG was well tolerated, with no dose-limiting toxicities. Sixty-two percent of patients in the high-risk cohort and 54% of patients in the second-line cohort had a complete response at study day 28. Plasma EGF was elevated sixfold (from 4 to 24 pg/mL; P = .02) at 6 hours postdose in the high-risk cohort, in contrast to no peak in plasma EGF in the more severe second-line cohort. After 1 week of uhCG, patients reported a twofold increase in the regulatory T cell to conventional T-cell ratio, suggesting immune modulation despite high-dose steroids. Responding patients reported significantly lower plasma amphiregulin and higher plasma butyrate levels at study completion, suggesting improvement in mucosal damage over time. uhCG is a novel, safe, supportive therapy, proceeding to phase 2 testing at 2000 units/m2 in high-risk aGVHD. This study was registered at www.clinicaltrials.gov as #NCT02525029.

Role of serum amylase and salivary cytokines in oral complications during chemoradiotherapy

OBJECTIVES

To investigate whether serum amylase can predict the recovery of salivary volume and determine the correlation of the level of cytokines, including epidermal growth factor, hepatocyte growth factor and keratinocyte growth factor, with oral mucositis during chemoradiotherapy for oral cancer.

SUBJECTS AND METHODS

This study included 84 patients treated with preoperative chemoradiotherapy followed by curative surgery, following a phase II study protocol. We measured and analysed the correlation of the stimulated saliva volume, serum amylase and cytokines in resting saliva at baseline and 1 month after chemoradiotherapy with oral mucositis levels.

RESULTS

We observed a negative correlation between the serum amylase level at the beginning of chemoradiotherapy and the stimulated saliva volume at 1 month after chemoradiotherapy (p = .03). Epidermal growth factor in resting saliva was significantly reduced after chemoradiotherapy (p < .01). The incidence of severe oral mucositis during chemoradiotherapy was significantly higher and negatively associated with the epidermal growth factor and keratinocyte growth factor levels (p = .04, p = .05).

CONCLUSIONS

The serum amylase level at the beginning of chemoradiotherapy may be a predictor of the recovery of the saliva volume. Furthermore, cytokines such as epidermal growth factor and keratinocyte growth factor in resting saliva affect the development of oral mucositis during chemoradiotherapy.

The recruitment of extra-intestinal cells to the injured mucosa promotes healing in radiation enteritis and chemical colitis in a mouse parabiosis model

Mucosal healing occurs through migration and proliferation of cells within injured epithelium, yet these processes may be inadequate for mucosal healing after significant injury where the mucosa is denuded. We hypothesize that extra-intestinal cells can contribute to mucosal healing after injury to the small and large intestine. We generated parabiotic pairs between wild-type and tdTomato mice, which were then subjected to radiation-induced enteritis and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. We now show that as compared with singleton mice, mice with a parabiotic partner were protected against intestinal damage as revealed by significantly reduced weight loss, reduced expression of pro-inflammatory cytokines, reduced enterocyte apoptosis, and improved crypt proliferation. Donor cells expressed CD45-, Sca-1+, c-kit+, and CXCR4+ and accumulated around the injured crypts but did not transdifferentiate into epithelia, suggesting that extra-intestinal cells play a paracrine role in the healing response, while parabiotic pairings with Rag1-/- mice showed improved healing, indicating that adaptive immune cells were dispensable for mucosal healing. Strikingly, ablation of the bone marrow of the donor parabionts removed the protective effects. These findings reveal that the recruitment of extra-intestinal, bone marrow-derived cells into the injured intestinal mucosa can promote mucosal healing, suggesting novel therapeutic approaches for severe intestinal disease.

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

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

Pathway-based Genome-wide Association Studies Reveal the Association Between Growth Factor Activity and Inflammatory Bowel Disease

BACKGROUND

The inflammatory bowel diseases known as Crohn's disease (CD) and ulcerative colitis (UC) are related autoimmune conditions with a complex etiology composed of genetic and environmental factors. Genetic studies have revealed 200 susceptibility loci for inflammatory bowel diseases, but these only account for a small fraction of the genetic heritability of the disease. We employed pathway-based approaches to identify genes that cooperatively make contributions to the genetic etiology of CD.

METHODS

We exploited the largest CD dataset (20,000 cases + 28,000 controls) and UC dataset (17,000 cases + 33,500 controls) to date. We conducted a meta-analysis of 5 CD cohorts of European ancestry using 3 pathway-based approaches and further performed replication studies in an independent cohort genotyped on the Immunochip and in another pediatric cohort of European ancestry. Similar meta-analysis was performed for UC cohorts.

RESULTS

In addition to the multiple immune-related pathways that have been implicated in the genetic etiology of inflammatory bowel diseases before, we found significant associations involving genes in growth factor signaling for CD. This result was replicated in 2 independent cohorts of European ancestry. This association with growth factor activity is not unique to CD. We found a similar significant association with UC cohorts.

CONCLUSIONS

Our findings suggest that genes involved in pathways of growth factor signaling may make joint contributions to the etiology of CD and UC, providing novel insight into the genetic mechanisms of these diseases.

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

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

An essential role of cAMP response element-binding protein in epidermal growth factor-mediated induction of sodium/glucose cotransporter 1 gene expression and intestinal glucose uptake

The sodium/glucose cotransporter 1 (SGLT1) is responsible for glucose uptake in intestinal epithelial cells. Its expression is decreased in individuals with intestinal inflammatory disorders and is correlated with the pathogenesis of disease. The aim of this study was to understand the regulatory mechanism of the SGLT1 gene. Using the trinitrobenzene sulfonic acid-induced mouse models of intestinal inflammation, we observed decreased SGLT1 expression in the inflamed intestine was positively correlated with the mucosal level of epidermal growth factor (EGF) and activated CREB. Overexpression of EGF demonstrated that the effect of EGF on intestinal glucose uptake was primarily due to the increased level of SGLT1. We identified an essential cAMP binding element (CRE) confers EGF inducibility in the human SGLT1 gene promoter. ChIP assay further demonstrated the increased binding of CREB and CBP to the SGLT1 gene promoter in EGF-treated cells. In addition, the EGFR- and PI3K-dependent CREB phosphorylations are involved in the EGF-mediated SGLT1 expression. This is the first report to demonstrate that CREB is involved in EGF-mediated transcription regulation of SGLT1 gene in the normal and inflamed intestine, which can provide potential therapeutic applications for intestinal inflammatory disorders.

Proteinase-activated receptor 2 (PAR2) decreases apoptosis in colonic epithelial cells

Mucosal biopsies from inflamed colon of inflammatory bowel disease patients exhibit elevated epithelial apoptosis compared with those from healthy individuals, disrupting mucosal homeostasis and perpetuating disease. Therapies that decrease intestinal epithelial apoptosis may, therefore, ameliorate inflammatory bowel disease, but treatments that specifically target apoptotic pathways are lacking. Proteinase-activated receptor-2 (PAR2), a G protein-coupled receptor activated by trypsin-like serine proteinases, is expressed on intestinal epithelial cells and stimulates mitogenic pathways upon activation. We sought to determine whether PAR2 activation and signaling could rescue colonic epithelial (HT-29) cells from apoptosis induced by proapoptotic cytokines that are increased during inflammatory bowel disease. The PAR2 agonists 2-furoyl-LIGRLO (2f-LI), SLIGKV and trypsin all significantly reduced cleavage of caspase-3, -8, and -9, poly(ADP-ribose) polymerase, and the externalization of phosphatidylserine after treatment of cells with IFN-γ and TNF-α. Knockdown of PAR2 with siRNA eliminated the anti-apoptotic effect of 2f-LI and increased the sensitivity of HT-29 cells to cytokine-induced apoptosis. Concurrent inhibition of both MEK1/2 and PI3K was necessary to inhibit PAR2-induced survival. 2f-LI was found to increase phosphorylation and inactivation of pro-apoptotic BAD at Ser(112) and Ser(136) by MEK1/2 and PI3K-dependent signaling, respectively. PAR2 activation also increased the expression of anti-apoptotic MCL-1. Simultaneous knockdown of both BAD and MCL-1 had minimal effects on PAR2-induced survival, whereas single knockdown had no effect. We conclude that PAR2 activation reduces cytokine-induced epithelial apoptosis via concurrent stimulation of MEK1/2 and PI3K but little involvement of MCL-1 and BAD. Our findings represent a novel mechanism whereby serine proteinases facilitate epithelial cell survival and may be important in the context of colonic healing.

NOD-like receptors in intestinal homeostasis and epithelial tissue repair

The intestinal epithelium constitutes a dynamic physical barrier segregating the luminal content from the underlying mucosal tissue. Following injury, the epithelial integrity is restored by rapid migration of intestinal epithelial cells (IECs) across the denuded area in a process known as wound healing. Hence, through a sequence of events involving restitution, proliferation and differentiation of IECs the gap is resealed and homeostasis reestablished. Relapsing damage followed by healing of the inflamed mucosa is a hallmark of several intestinal disorders including inflammatory bowel diseases (IBD). While several regulatory peptides, growth factors and cytokines stimulate restitution of the epithelial layer after injury, recent evidence in the field underscores the contribution of innate immunity in controlling this process. In particular, nucleotide-binding and oligomerization domain-like receptors (NLRs) play critical roles in sensing the commensal microbiota, maintaining homeostasis, and regulating intestinal inflammation. Here, we review the process of intestinal epithelial tissue repair and we specifically focus on the impact of NLR-mediated signaling mechanisms involved in governing epithelial wound healing during disease.

ErbB receptors and their growth factor ligands in pediatric intestinal inflammation

The ErbB tyrosine kinases (epidermal growth factor receptor (EGFR), ErbB2/HER2, ErbB3, and ErbB4) are cell surface growth factor receptors widely expressed in many developing mammalian tissues, including in the intestinal tract. Signaling elicited by these receptors promotes epithelial cell growth and survival, and ErbB ligands have been proposed as therapeutic agents for intestinal diseases of pediatric populations, including inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and inflammation associated with total parenteral nutrition (TPN). Furthermore, emerging evidence points to reduced ErbB ligand expression and thus reduced ErbB activity in IBD, NEC, and TPN models. This review will discuss the current understanding of the role of ErbB receptors in the pathogenesis and potential treatment of pediatric intestinal inflammation, with focus on the altered signaling in disease and the molecular mechanisms by which exogenous ligands are protective.

Layered signaling regulatory networks analysis of gene expression involved in malignant tumorigenesis of non-resolving ulcerative colitis via integration of cross-study microarray profiles

Background

Ulcerative colitis (UC) was the most frequently diagnosed inflammatory bowel disease (IBD) and closely linked to colorectal carcinogenesis. By far, the underlying mechanisms associated with the disease are still unclear. With the increasing accumulation of microarray gene expression profiles, it is profitable to gain a systematic perspective based on gene regulatory networks to better elucidate the roles of genes associated with disorders. However, a major challenge for microarray data analysis is the integration of multiple-studies generated by different groups.

Methodology/Principal Findings

In this study, firstly, we modeled a signaling regulatory network associated with colorectal cancer (CRC) initiation via integration of cross-study microarray expression data sets using Empirical Bayes (EB) algorithm. Secondly, a manually curated human cancer signaling map was established via comprehensive retrieval of the publicly available repositories. Finally, the co-differently-expressed genes were manually curated to portray the layered signaling regulatory networks.

Results

Overall, the remodeled signaling regulatory networks were separated into four major layers including extracellular, membrane, cytoplasm and nucleus, which led to the identification of five core biological processes and four signaling pathways associated with colorectal carcinogenesis. As a result, our biological interpretation highlighted the importance of EGF/EGFR signaling pathway, EPO signaling pathway, T cell signal transduction and members of the BCR signaling pathway, which were responsible for the malignant transition of CRC from the benign UC to the aggressive one.

Conclusions

The present study illustrated a standardized normalization approach for cross-study microarray expression data sets. Our model for signaling networks construction was based on the experimentally-supported interaction and microarray co-expression modeling. Pathway-based signaling regulatory networks analysis sketched a directive insight into colorectal carcinogenesis, which was of significant importance to monitor disease progression and improve therapeutic interventions.

From model to mechanism: lessons of mice and men in the discovery of protein biologicals for the treatment of inflammatory bowel disease

Successful therapeutics for inflammatory bowel disease (IBD) must be able to reverse effectively the complex processes involved in the manifestation of inflammatory pathology in intact tissues. Although studies of human tissue samples are important to confirm the biological rationale for developing a particular therapeutic, in vivo rodent models of IBD provide a biological 'flask' in which therapeutics can be tested in a more representative setting. Moreover, gene targeting and transgenic technologies in rodents have exponentially increased the repertoire of available IBD models and provided insight into possible contributions that certain genes may have in the pathogenesis of disease. These models have been key in generating the current arsenal of biological therapeutics that are available, or are presently under investigation, for the treatment of IBD patients.

TNF-α induces upregulation of EGFR expression and signaling in human colonic myofibroblasts

The myofibroblast has recently been identified as an important mediator of tumor necrosis factor-α (TNF-α)-associated colitis and cancer, but the mechanism(s) involved remains incompletely understood. Recent evidence suggests that TNF-α is a central regulator of multiple inflammatory signaling cascades. One important target of TNF-α may be the signaling pathway downstream of the epidermal growth factor receptor (EGFR), which has been associated with many human cancers. Here, we show that long-term exposure of 18Co cells, a model of human colonic myofibroblasts, with TNF-α led to a striking increase in cell surface EGFR expression, an effect that was completely inhibited by cycloheximide. Subsequent EGFR binding by EGF and heparin binding (HB)-EGF was associated with enhanced EGFR tyrosine kinase activity, prolonged ERK activation, and a significant increase in cyclooxygenase-2 (COX-2) expression compared with 18Co cells treated with EGF and HB-EGF alone. TNF-α also increased EGFR expression and signaling in primary myofibroblasts isolated from human colon tissue. TNF-α-induced upregulation of EGFR may be a plausible mechanism to explain the exaggerated cellular responsiveness that characterizes inflammatory bowel disease and that may contribute to a microenvironment that predisposes to colitis-associated cancer through enhanced COX-2 expression.

ErbB2 and ErbB3 regulate recovery from dextran sulfate sodium-induced colitis by promoting mouse colon epithelial cell survival

ErbB2 and ErbB3 receptor tyrosine kinases are key regulators of proliferation, migration, differentiation and cell survival; however, their roles in gastrointestinal biology remain poorly defined. We hypothesized that ErbB2 and ErbB3 promote colon epithelial cell survival in the context of the wound-healing response following colitis. In this study, mice bearing intestinal epithelial-specific deletion of ErbB2 or ErbB3 were treated with dextran sulfate sodium (DSS). Colon sections were examined for injury, cytokine expression, epithelial cell proliferation and apoptosis. Deletion of epithelial ErbB2 did not affect the extent of intestinal injury in response to DSS, whereas deletion of ErbB3 slightly increased injury. However, the roles of both receptors were more apparent during recovery from DSS colitis, in which ErbB2 or ErbB3 epithelial deletion resulted in greater inflammation and crypt damage during the early reparative period. Moreover, loss of ErbB3 prevented normal epithelial regeneration in the long term, with damage persisting for at least 6 weeks following a single round of DSS. Delayed recovery in mice with epithelial deletion of ErbB2 or ErbB3 was associated with increased colonic expression of tumor necrosis factor alpha and increased epithelial apoptosis. Furthermore, epithelial ErbB3 deletion increased apoptosis at baseline and during DSS injury. Additionally, epithelial cell hyperproliferation during recovery was exacerbated by deletion of either ErbB2 or ErbB3. These results suggest that ErbB2 and ErbB3 have important cytoprotective and reparative roles in the colonic epithelium following injury, by promoting colon epithelial cell survival.

Erlotinib inhibits progression to dysplasia in a colitis-associated colon cancer model

AIM: To investigate the role of epidermal growth factor receptor (EGFR) in colitis-associated dysplasia using the EGFR tyrosine kinase inhibitor erlotinib.

METHODS: Sprague-Dawley rats received trinitrobenzene sulfonic acid (TNBS; 30 mg in 50% ethanol, ic), followed 6 wk later by reactivation with TNBS (5 mg/kg, iv) for 3 d. To induce colitis-associated dysplasia, rats then received TNBS (iv) twice a week for 10 wk. One group received erlotinib (10 mg/kg, ip) for 1 wk before the start of the reactivation of the colitis and 2 wk after (21 d); the rest received the vehicle. After rats were euthanized, the colons were removed and analyzed for damage and expression of the EGFR downstream effectors Erk1/2 and c-Myc.

RESULTS: Ninety percent of the vehicle-treated animals had dysplasia in any region of the colon. Erlotinib-treated animals had a significant decrease in the incidence of dysplasia compared to vehicle-treated animals in all regions of the colon (50.00% ± 11.47% vs 90.00% ± 10.00% in proximal, P < 0.05; 15.00% ± 8.19% vs 50.00% ± 16.67% in mid, P < 0.05; and 20.00% ± 9.17% vs 70.00% ± 15.28% in distal, P < 0.01). Erlotinib-treated animals also had reduced cell proliferation, reduced active Erk1/2, and reduced c-Myc in colon epithelium compared with the vehicle-treated animals. In vitro, erlotinib treatment was shown to markedly decrease c-Myc and pErk1/2 levels in rat epithelial cells. Proliferation of rat epithelial cells was stimulated by epidermal growth factor and inhibited by erlotinib (P < 0.05).

CONCLUSION: Erlotinib can decrease the development of colitis-associated dysplasia, suggesting a potential therapeutic use for erlotinib in patients with long-standing colitis.

Cancer treatment-induced oral mucositis: a critical review

Head and neck cancer represents one of the main oncological problems. Its treatment, radiotherapy and chemotherapy leads to mucositis, and other side effects. The authors reviewed high-quality evidence published over the last 25 years on the treatment of cancer treatment-induced oral mucositis. A Medline search for double blind randomized controlled clinical trials between 1985 and 2010 was carried out. The keywords were oral mucositis, radiotherapy, chemotherapy, and head and neck. The different therapeutic approaches found for cancer treatment-induced oral mucositis included: intensive oral hygiene care; use of topical antiseptics and antimicrobial agents; use of anti-inflammatory agents; cytokines and growth factors; locally applied non-pharmacological methods; antioxidants; immune modulators; and homoeopathic agents. To date, no intervention has been able to prevent and treat oral mucositis on its own. It is necessary to combine interventions that act on the different phases of mucositis. It is still unclear which strategies reduce oral mucositis, as there is not enough evidence that describes a treatment with a proven efficiency and is superior to the other treatments for this condition.

Interferon-γ alters downstream signaling originating from epidermal growth factor receptor in intestinal epithelial cells: functional consequences for ion transport

The epidermal growth factor receptor (EGFr) regulates many cellular functions, such as proliferation, apoptosis, and ion transport. Our aim was to investigate whether long term treatment with interferon-γ (IFN-γ) modulates EGF activation of downstream signaling pathways in intestinal epithelial cells and if this contributes to dysregulation of epithelial ion transport in inflammation. Polarized monolayers of T(84) and HT29/cl.19A colonocytes were preincubated with IFN-γ prior to stimulation with EGF. Basolateral potassium transport was studied in Ussing chambers. We also studied inflamed colonic mucosae from C57BL/6 mice treated with dextran sulfate sodium or mdr1a knock-out mice and controls. IFN-γ increased intestinal epithelial EGFr expression without increasing its phosphorylation. Conversely, IFN-γ caused a significant decrease in EGF-stimulated phosphorylation of specific EGFr tyrosine residues and activation of ERK but not Akt-1. In IFNγ-pretreated cells, the inhibitory effect of EGF on carbachol-stimulated K(+) channel activity was lost. In inflamed colonic tissues, EGFr expression was significantly increased, whereas ERK phosphorylation was reduced. Thus, although it up-regulates EGFr expression, IFN-γ causes defective EGFr activation in colonic epithelial cells via reduced phosphorylation of specific EGFr tyrosine residues. This probably accounts for altered downstream signaling consequences. These observations were corroborated in the setting of colitis. IFN-γ also abrogates the ability of EGF to inhibit carbachol-stimulated basolateral K(+) currents. Our data suggest that, in the setting of inflammation, the biological effect of EGF, including the inhibitory effect of EGF on Ca(2+)-dependent ion transport, is altered, perhaps contributing to diarrheal and other symptoms in vivo.

Intestinal growth factors: potential use in the treatment of inflammatory bowel disease and their role in mucosal healing

BACKGROUND

A key feature of inflammatory bowel disease (IBD) is impaired epithelial repair. Human growth factors comprise an array of signaling molecules that lead to ligand-specific signal transduction. Their downstream effects are associated with several cellular functions including epithelial healing in response to injury. Several studies have described specific growth factor deficiencies in patients with IBD, implicating their role in disease pathophysiology. The aim of this review was to describe currently known enterocyte-targeted growth factors, their mechanisms of action, and their potential therapeutic utility.

METHODS

The National Library of Medicine (http://www.pubmed.gov) and meeting abstracts were searched using the following terms: growth factor, intestine, colon, inflammatory bowel disease, Crohn's disease, ulcerative colitis, colitis, animal model, transforming growth factor, bone morphogenetic protein, activins, growth hormone, fibroblast growth factor, epidermal growth factor (EGF), keratinocyte growth factor (KGF), glucagon-like peptide II, granulocyte macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), vascular endothelial growth factor (VEGF) inhibitors, and trefoil factors.

RESULTS

Several growth factors are therapeutic candidates in IBD. Growth hormone, KGF, EGF, teduglutide, GM-CSF/G-CSF have entered early clinical trials, whereas others are currently in preclinical evaluation.

CONCLUSIONS

There are several growth factors responsible for epithelial repair. Preliminary studies using recombinant growth factors seem promising in IBD preclinical and clinical trials.

Comparative effects of probiotics, prebiotics, and synbiotics on growth factors in the large bowel in a rat model of formula-induced bowel inflammation

OBJECTIVES

Supplementation with probiotics has been shown to prevent gastrointestinal damage possibly through preservation of growth factors. We tested the hypothesis that probiotics, prebiotics, or synbiotics supplementation preserves intestinal insulin-like growth factors (IGFs) and epidermal growth factors (EGFs) in formula-fed neonatal rats.

MATERIALS AND METHODS

At birth (postnatal day 0 [P0]), neonatal rat pups (n = 18 pups/group) were either maternally fed or hand-gavaged with formula supplemented with probiotics (Pro-Fed), prebiotics, or synbiotics from P0 to P3. A formula-fed control group received formula without supplementation. At P4, large bowel samples were assessed histologically and assayed for vascular endothelial growth factor (VEGF), soluble VEGF receptor-1, IGF-I, IGF-II, and EGF.

RESULTS

All formula-fed groups were severely growth suppressed with comparable mortalities. Moderate preservation of bowel integrity was noted in the Pro-Fed group. In contrast, severe inflammation was seen in all of the other formula groups. This was associated with significant increases in VEGF levels in all of the formula groups (P < 0.05) except the Pre-Fed group. Similar elevations in soluble VEGF receptor-1 (P < 0.05), IGF-I (P < 0.05), and EGF (P < 0.05) were noted, but statistical significance was achieved only in the Pro-Fed group.

CONCLUSIONS

Induction of IGF-I and EGF with moderate bowel integrity may represent a protective effect of probiotics against formula-induced inflammation. These data, taken collectively, suggest that probiotics may provide more beneficial effects on the developing large bowel than prebiotics and synbiotics.

Biological therapies of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by increasing morbidity and, if suboptimally treated, poor prognosis. Recent evidence strongly suggests that dysfunctional immune responses play an important role in the pathogenesis of IBD. Therefore, immunologically downregulating the overactivated innate and adaptive immune responses may be a better approach to treat IBD than currently used pharmaceutical therapies. In recent years, many new biological therapies have been developed. These therapies are shown to be effective for inducing remission, preventing complications, improving life quality of the patients, and reducing hospitalization and surgical rates. This article introduces and discusses these new biological agents that have been used effectively in clinic for IBD patients.

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Carbachol induces TGF-alpha expression and colonic epithelial cell proliferation in sensory-desensitised rats

OBJECTIVE/BACKGROUND

Signals for the expression of the peptide growth factors epidermal growth factor and transforming growth factor-alpha (TGFalpha) in the gastrointestinal mucosa are largely unknown. We have shown earlier that extrinsic afferents in the gastrointestinal tract induce TGFalpha expression in colonic mucosa via the deliberation of neurotransmitters substance P and calcitonin gene-related peptide. The aim of our present study was to determine the effects of carbachol on mucosal TGFalpha expression and epithelial cell proliferation in vivo.

DESIGN/METHODS

Rats were divided in three groups. Group 1 was treated with vehicle only, group 2 received one single subcutaneous injection of 250 microg/kg of carbachol and animals in group 3 were sensory-desensitised prior to the injection of 250 microg/kg carbachol. TGFalpha expression and epithelial cell proliferation was evaluated by polymerase chain reaction, Western blot analysis and bromodeoxyuridine staining.

RESULTS

Carbachol induced a significant increase in mucosal epithelial cell proliferation and TGFalpha expression. Sensory desensitisation did neither abolish the increased TGFalpha expression nor the increase in epithelial cell proliferation.

CONCLUSION

Parasympathetic pathways are involved in the control of TGFalpha expression in gastrointestinal mucosa as well as in epithelial cell proliferation.

Recombinant human epidermal growth factor treatment of radiation-induced severe oral mucositis in patients with head and neck malignancies

Mucositis of the oral cavity and pharynx is a major dose-limiting factor in the application of radiotherapy (RT) to patients with head and neck cancer. Therefore, we evaluated the wound healing effect of human recombinant epidermal growth factor (rhEGF) in head and neck cancer and lymphoma patients with irradiation (with or without combined chemotherapy-induced oral mucositis). Patients at Asan Medical Center who had undergone definitive RT of the head and neck region with or without combined chemotherapy and who had developed severe oral mucositis (higher than the Radiation Therapy Oncology Group grade 3) were treated with topical rhEGF twice daily for 7 days. The evaluation of response with regard to oral mucositis was performed 1 week later. Of the 11 treated patients, three had nasopharyngeal carcinoma, three had carcinoma of the oropharynx, two had carcinoma of the oral cavity, one had carcinoma of the hypopharynx and two had lymphoma of the head and neck. Six patients received RT only, and five patients received concurrent chemoradiotherapy. All patients showed improvements in their oral mucositis after topical treatment with rhEGF in that the Radiation Therapy Oncology Group grade was significantly decreased (P = 0.0000). This finding suggests that rhEGF is effective and safe for the treatment of radiation-induced mucositis. Further studies are needed to determine the optimal dosage and fractionation schedule.

Increased duodenal expression of transforming growth factor-alpha and epidermal growth factor during experimental colitis in rats

OBJECTIVE/BACKGROUND

Epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha) protect gastrointestinal mucosa against injury. Having shown earlier, that TGFalpha but not EGF is locally increasingly expressed after mucosal injury in the colon, we now wanted to explore the pattern of expression of EGF and TGFalpha in the remaining gastrointestinal tract and to infer from the pattern of expression, to possible signals for the induction of the growth factor expression and further mechanisms for mucosal protection.

DESIGN/METHODS

The trinitrobenzene sulfonic acid/ethanol-induced model of colitis in rats was used. TGFalpha-mRNA and EGF-mRNA expression was evaluated in inflamed and noninflamed colon, in the ileum, jejunum, duodenum, stomach, and in the submandibulary glands.

RESULTS

A significant increase of TGFalpha-mRNA and EGF-mRNA expressions was detected in the duodenal mucosa and a significant increase in TGFalpha-mRNA expression was observed in the inflamed colonic mucosa after mucosal injury in the colon within the first hours of colitis.

CONCLUSION

The increased expression of EGF and TGFalpha in the duodenum may lead to neutralization of gastric acid and proteolytic enzymes in the upper gastrointestinal tract during the course of colitis. Possible signals for the increased expression of EGF and TGFalpha presumably are fasting, parasympathetic, or adrenergic parts of the enteric nervous system or yet unknown mechanisms.

Tumor necrosis factor inhibits ligand-stimulated EGF receptor activation through a TNF receptor 1-dependent mechanism

Tumor necrosis factor (TNF) and epidermal growth factor (EGF) are key regulators in the intricate balance maintaining intestinal homeostasis. Previous work from our laboratory shows that TNF attenuates ligand-driven EGF receptor (EGFR) phosphorylation in intestinal epithelial cells. To identify the mechanisms underlying this effect, we examined EGFR phosphorylation in cells lacking individual TNF receptors. TNF attenuated EGF-stimulated EGFR phosphorylation in wild-type and TNFR2(-/-), but not TNFR1(-/-), mouse colon epithelial (MCE) cells. Reexpression of wild-type TNFR1 in TNFR1(-/-) MCE cells rescued TNF-induced EGFR inhibition, but expression of TNFR1 deletion mutant constructs lacking the death domain (DD) of TNFR1 did not, implicating this domain in EGFR downregulation. Blockade of p38 MAPK, but not MEK, activation of ERK rescued EGF-stimulated phosphorylation in the presence of TNF, consistent with the ability of TNFR1 to stimulate p38 phosphorylation. TNF promoted p38-dependent EGFR internalization in MCE cells, suggesting that desensitization is achieved by reducing receptor accessible to ligand. Taken together, these data indicate that TNF activates TNFR1 by DD- and p38-dependent mechanisms to promote EGFR internalization, with potential impact on EGF-induced proliferation and migration key processes that promote healing in inflammatory intestinal diseases.

Ameliorative effects of bombesin and neurotensin on trinitrobenzene sulphonic acid-induced colitis, oxidative damage and apoptosis in rats

AIM: To investigate the effects of bombesin (BBS) and neurotensin (NTS) on apoptosis and colitis in an ulcerative colitis model.

METHODS: In this study, a total of 50 rats were divided equally into 5 groups. In the control group, no colitis induction or drug administration was performed. Colitis was induced in all other groups. Following the induction of colitis, BBS, NTS or both were applied to three groups of rats. The remaining group (colitis group) received no treatment. On the 11th d after induction of colitis and drug treatment, blood samples were collected for TNF-α and IL-6 level studies. Malondialdehyde (MDA), carbonyl, myeloperoxidase (MPO) and caspase-3 activities, as well as histopathological findings, evaluated in colonic tissues.

RESULTS: According to the macroscopic and microscopic findings, the study groups treated with BBS, NTS and BBS + NTS showed significantly lower damage and inflammation compared with the colitis group (macroscopic score, 2.1 ± 0.87, 3.7 ± 0.94 and 2.1 ± 0.87 vs 7.3 ± 0.94; microscopic score, 2.0 ± 0.66, 3.3 ± 0.82 and 1.8 ± 0.63 vs 5.2 ± 0.78, P < 0.01). TNF-α and IL-6 levels were increased significantly in all groups compared with the control group. These increases were significantly smaller in the BBS, NTS and BBS + NTS groups compared with the colitis group (TNF-α levels, 169.69 ± 53.56, 245.86 ± 64.85 and 175.54 ± 42.19 vs 556.44 ± 49.82; IL-6 levels, 443.30 ± 53.99, 612.80 ± 70.39 and 396.80 ± 78.43 vs 1505.90 ± 222.23, P < 0.05). The colonic MPO and MDA levels were significantly lower in control, BBS, NTS and BBS + NTS groups than in the colitis group (MPO levels, 24.36 ± 8.10, 40.51 ± 8.67 and 25.83 ± 6.43 vs 161.47 ± 38.24; MDA levels, 4.70 ± 1.41, 6.55 ± 1.12 and 4.51 ± 0.54 vs 15.60 ± 1.88, P < 0.05). Carbonyl content and caspase-3 levels were higher in the colitis and NTS groups than in control, BBS and BBS + NTS groups (carbonyl levels, 553.99 ± 59.58 and 336.26 ± 35.72 vs 209.76 ± 30.92, 219.76 ± 25.77 and 220.34 ± 36.95; caspase-3 levels, 451.70 ± 68.27 and 216.20 ± 28.17 vs 28.60 ± 6.46, 170.50 ± 32.37 and 166.50 ± 30.95, P < 0.05).

CONCLUSION: The results of this study suggest BBS and NTS, through their anti-inflammatory actions, support the maintenance of colonic integrity and merit consideration as potential agents for ameliorating colonic inflammation.

Epidermal growth factor increases tissue antioxidant enzyme activities in ethanol-induced gastric injury in rat

The aim of the present study is to investigate whether the antioxidant mechanisms are involved in epidermal growth factor (EGF)-mediated protection from ethanol-induced gastric damage. Twenty four female Sprague-Dawley rats were assigned into 3 groups; control (C) group (n=8) was given physiologic saline by gavage; ethanol (E) group (n=8) was given 1 ml of 80% ethanol (v/v) in distilled water by gavage and EGF group (n=8) was given EGF (100 mg/kg-body wt.) intraperitonealy half an hour before the administration of ethanol. The protein carbonyl content was significantly higher in the E group than the C group (p<0.01). On the other hand, EGF decreased the protein carbonyl content in the EGF group (p<0.01). Gastric myeloperoxidase activity increased significantly after the administration of ethanol (p<0.01). The administration of EGF decreased significantly the myeloperoxidase activity (p<0.01). Although ethanol caused a slight decrease in the catalase activity, no statistical significance was observed between groups E and C. The catalase activity increased significantly after EGF treatment (p<0.01). The superoxide dismutase activity decreased significantly in the E group when compared to the C group (p<0.05) while it was found to be increased significantly in the EGF group in comparison with the E group (p<0.01). In summary, the present results indicate that the gastroprotective effect of EGF in the experimental lesions induced by ethanol could be attributed to its property such as to augment the antioxidant enzyme activities.

Hepatocyte growth factor promotes colonic epithelial regeneration via Akt signaling

Hepatocyte growth factor (HGF) can promote the regeneration of injured organs, including HGF gene therapy by electroporation (EP) for liver injury. In this study, we investigated the effect of HGF on dextran sulfate sodium-induced colitis and tried to clarify the regenerative mechanisms of colonic epithelial cells and the signaling pathway involved. Colitis was induced by dextran sulfate sodium in mice, together with HGF gene transfer by EP. On day 10, the colitis was evaluated histologically and by Western blot analysis. The colonic epithelial cell line MCE301 was exposed to HGF protein, and its proliferation and activated signaling pathway were analyzed. In vivo, the histological score improved and the number of Ki-67-positive epithelial cells increased in the HGF-treated mice compared with the controls. Western blot analysis showed enhanced expression of phospho-Akt in the HGF-treated mice compared with the controls. In vitro, HGF stimulated the proliferation of MCE301 cells. There was enhanced phospho-Akt expression for more than 48 h after HGF stimulation, although phospho-ERK1/2 was enhanced for only 10 min. LY-294002 or Akt small interfering RNA suppressed cell proliferation induced by HGF. Thus HGF induces the proliferation of colonic epithelial cells via the phosphatidylinositol 3-kinase/Akt signaling pathway. HGF gene therapy can attenuate acute colitis via epithelial cell proliferation through the PI3K/Akt pathway. These data suggested that HGF gene therapy by EP may be effective for the regeneration and repair of injured epithelial cells in inflammatory bowel disease.

Epidermal growth factor stimulates chloride transport in primary cultures of weanling and adult rabbit colonocytes

OBJECTIVES

We have shown that Ca2+-dependent regulation of Cl- secretion in the mammalian colon exhibits age dependence. Because epidermal growth factor (EGF) has a well-established role in growth and can increase intracellular calcium [Ca2+]i, it is conceivable that its developmental influence may extend to the regulation of intestinal ion transport. In this study, we examined the role of EGF in the regulation of Cl- transport in the developing rabbit distal colon.

MATERIALS AND METHODS

Because serum contains growth factors, which could have confounded our studies, we first established an optimal milieu for testing EGF in primary cultures of adult rabbit distal colonocytes by culturing them for 24 h in media containing 0%, 1%, 5%, and 20% serum. Chloride transport (millimoles per second) and [Ca2+]i were measured with use of the fluorescent indicator N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE) and Fura-2AM, respectively.

RESULTS

Serum depletion had no effect on cell number, DNA content, or basal Cl- transport, but it significantly affected cell viability. In media with 0%, 1%, or 20% serum, bethanechol, 8BrcAMP, taurodeoxycholate, and EGF stimulated Cl- transport to a similar extent. EGF maximally stimulated Cl- transport at 16.3 nmol/L and 20 minutes. Bethanechol, but not EGF, increased [Ca2+]i. EGF did not alter bethanechol-stimulated Cl- transport or [Ca2+]i. EGF acts via an EGF-receptor and mitogen activated protein kinase (MAPK) signaling pathway, since stimulation of Cl- transport was abolished by genistein, AG1478, and PD98059. Weanling and adult colonocytes, cultured in 1% serum, showed similar basal and EGF-stimulated Cl- transport.

CONCLUSIONS

EGF stimulates rabbit colonic Cl- transport via a Ca2+-independent, tyrosine kinase- and MAPK-dependent pathway, and its effects are not age dependent.

p38 kinase regulates epidermal growth factor receptor downregulation and cellular migration

Internalization and proteolytic degradation of epidermal growth factor (EGF) receptor (R) following ligand binding is an important mechanism for regulating EGF-stimulated signals. Using pharmacological and RNA interference inhibition of p38 mitogen-activated protein kinase, we show that p38 is required for efficient EGF-induced EGFR destruction but not internalization. In the absence of p38 activity, EGF fails to stimulate the ubiquitin ligase Cbl or ubiquitinylation of EGFR, and internalized EGFR accumulates in intracellular vesicles containing caveolin-1. These effects are accompanied by loss of EGFR phosphorylation on Y1045, a phosphorylation site required for Cbl activation. Furthermore, similar to cells treated with p38 inhibitors, intestinal epithelial cells expressing Y1045F EGFR mutants show increased proliferation but not migration in response to EGF, thus uncoupling these biological responses. Together these data position p38 as a modulator of ligand-stimulated EGFR processing and demonstrate that this processing has a profound impact on the cellular outcome of EGFR signaling.

Systemic treatment of patients who have colorectal cancer and inflammatory bowel disease

Colorectal cancer is the most common malignant complication in patients who have IBD. The disease is difficult to diagnose because there is an overlap in symptoms in patients who have colon cancer and those who have IBD. Much has been learned about the incidence of colorectal cancer in patients who have IBD and its correlation with disease activity, duration, and anatomic location; however, almost no data are available regarding specific therapeutic considerations during adjuvant or palliative chemotherapy for these patients with respect to their underlying disease. Patients who have IBD who develop colorectal cancer are at higher risk for developing severe diarrhea during chemotherapy that may be due to the toxic effects of cytotoxic drugs or a flare of the IBD. Continuous infusional 5-FU alone, in combination with leucovorin, or in combination with oxaliplatin (FOLFOX) seems to be tolerated best. Bolus infusions of 5-FU (Roswell Park or Mayo regimens) and combination therapy of irinotecan with 5-FU should be avoided because of severe diarrhea and the possibility of sepsis. When diarrhea develops or worsens, empiric aminosalicylates may be given. Although it is theoretically possible that anti-EGFR therapies could affect IBD activity adversely, clinical experience with cetuximab in patients who have colorectal cancer has not shown any significant gastrointestinal side effects. Therefore, it seems reasonable to use it in patients who have colorectal cancer and IBD. The administration of bevacizumab has been associated with rare episodes of intestinal perforation; it should be used with great care in patients who have IBD. More studies and an integrative, multidisciplinary approach from oncologists and gastroenterologists are needed to provide optimal care for patients who have IBD during chemotherapy for colorectal cancer

Whey proteins and peptides: beneficial effects on immune health

A 65-year-old male with liver metastases after lung cancer resection was treated with five courses of chemotherapy consisting of gemcitabine (GEM) 1,000 mg/m2 (day 1, 8, every 4 weeks) plus carboplatin (CBDCA) AUC 6 (day 1, every 4 weeks). A partial response (PR) was achieved, his symptoms abated and his quality of life(QOL) improved. Although bone marrow suppression was observed as a side effect, it was within the tolerable range and did not interfere with therapy. This approach may be worth considering as a first-line anti-cancer chemotherapy for recurrence lung cancer.

Attenuation of mouse acute colitis by naked hepatocyte growth factor gene transfer into the liver

BACKGROUND

Hepatocyte growth factor (HGF) has multiple biological effects on a wide variety of cells. It modulates intestinal epithelial proliferation and migration, and critically regulates intestinal wound healing.

AIMS

To investigate the therapeutic effect of HGF gene transfer, we introduced the HGF gene into the liver of mice with acute colitis.

METHODS

The rat HGF expression plasmid vector, pCAGGS-HGF, was injected via the tail vein into C57BL/6 mice, followed by dosing with dextran sulfate sodium in distilled water. Firstly, the HGF gene was injected once on day 0. Secondly, the HGF gene was injected on day 0 and again on day 2.

RESULTS

Injection of the HGF gene ameliorated colitis with inhibition of both loss of body weight and shortening of colon length. It protected the colon from epithelial erosions and cellular infiltration. Expression of mRNAs for IFN-gamma, IL18, and TNF-alpha was reduced in the colon. In contrast, expression of mRNA for IL-10 was increased. The numbers of BrdU-positive intestinal epithelial cells were increased, and the numbers of TUNEL-positive apoptotic cells were decreased. Furthermore, a second injection prolonged the elevation of serum HGF levels, and ameliorated the symptoms better than a single injection. The empty pCAGGS plasmid did not ameliorate acute colitis.

CONCLUSIONS

HGF gene transfer attenuated acute colitis by facilitating intestinal wound repair as well as inhibiting inflammation, suggesting a new strategy for treatment of IBD.

Neuropeptide neurotensin stimulates intestinal wound healing following chronic intestinal inflammation

Because neurotensin (NT) and its high-affinity receptor (NTR1) modulate immune responses, chloride secretion, and epithelial cell proliferation, we sought to investigate their role in the repair process that follows the development of mucosal injuries during a persistent inflammation. Colonic NT and NTR1, mRNA, and protein significantly increased only after dextran sodium sulfate (DSS)-induced inflammatory damage developed. Colitis-induced body weight loss, colonic myeloperoxidase activity, and histological damage were significantly enhanced by SR-48642 administration, a nonpeptide NTR1 antagonist, whereas continuous NT infusion ameliorated colitis outcome. To evaluate the NT and NTR1 role in tissue healing, mucosal inflammatory injury was established administering 3% DSS for 5 days. After DSS discontinuation, mice rapidly gained weight, ulcers were healed, and colonic NT, NTR1, and cyclooxygenase (COX)-2 mRNA levels were upregulated, whereas SR-48642 treatment caused a further body weight loss, ulcer enlargement, and a blunted colonic COX-2 mRNA upregulation. In a wound-healing model in vitro, NT-induced cell migration in the denuded area was inhibited by indomethacin but not by an antitransforming growth factor-beta neutralizing antibody. Furthermore, NT significantly increased COX-2 mRNA levels by 2.4-fold and stimulated PGE(2) release in HT-29 cells. These findings suggest that NT and NTR1 are part of the network activated after mucosal injuries and that NT stimulates epithelial restitution at least, in part, through a COX-2 dependent pathway.

Therapeutic effects of rectal administration of basic fibroblast growth factor on experimental murine colitis

BACKGROUND & AIMS

Basic fibroblast growth factor (bFGF) is a promising therapeutic agent for various diseases. It remains unclear, however, whether bFGF is effective for the treatment of inflammatory bowel disease. The aim of this study was to examine the efficacy of bFGF on 2 experimental murine colitis models and to investigate its molecular mechanisms.

METHODS

We evaluated the effects of human recombinant bFGF (hrbFGF) on mice with dextran sulfate sodium (DSS)-induced colitis and mice with trinitrobenzene sulfonic acid (TNBS)-induced colitis as well as normal mice. Body weight, survival rate, and histologic findings of the colonic tissues were examined. Gene expression of tumor necrosis factor (TNF)-alpha, cyclooxygenase (COX)-2, transforming growth factor (TGF)-beta, mucin 2 (MUC2), intestinal trefoil factor (ITF), and vascular endothelial growth factor (VEGF) in the colonic tissues was determined. The proliferation activity of hrbFGF on the colonic epithelium was evaluated by immunohistochemistry.

RESULTS

Rectal administration of hrbFGF ameliorated DSS-induced colitis in a dose-dependent manner. Gene expression of TNF-alpha was significantly reduced in the colonic tissues of mice with DSS-induced colitis treated with hrbFGF, whereas MUC2 and ITF messenger RNA expression was up-regulated. Rectal administration of hrbFGF significantly improved the survival rate of mice with TNBS-induced colitis and partially ameliorated colitis. hrbFGF significantly increased the number of Ki-67-positive cells in the colonic epithelium of normal mice, and up-regulated the gene expression of COX-2, TGF-beta, MUC2, ITF, and VEGF in the colonic tissues.

CONCLUSIONS

Rectal administration of bFGF might be a promising option for the treatment of inflammatory bowel disease.

Synergistic effects of systemic trefoil factor family 1 (TFF1) peptide and epidermal growth factor in a rat model of colitis

Novel therapies for the treatment of colitis are required. We therefore examined the potential value of the trefoil factor family 1 (TFF1) peptide and epidermal growth factor (EGF) alone and in combination. Effects of TFF1- Cys58 +/- EGF on an in vitro HT29 cell wounding model of restitution showed synergistic activity when used in combination. In addition, animals had colitis induced by adding 4% dextran sulphate sodium (DSS) to the drinking water for 7 days and they also received twice daily subcutaneous injections of test peptides. Treatment with TFF1-Cys58 alone (100 microg/kg) reduced histological colitis score by 22%, but the TFF1-Ser58 variant was ineffective. In a second study, TFF1-Cys58 reduced histological colitis score by 15%, EGF (600 microg/kg) by 26%, and an additive response (42% reduction) was demonstrated when used together (P < 0.01 versus either peptide given alone). Similar results were found using tissue myeloperoxidase (MPO) activity as a marker of inflammation. Where clinical risk/benefit seems justified, these initial studies suggest that combination therapy of systemic EGF and TFF peptides may prove useful for treatment of colitis in patients with disease extending beyond the reach of topical (enema) therapy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Use of the 'nutriceutical', bovine colostrum, for the treatment of distal colitis: results from an initial study

BACKGROUND

Bovine colostrum is a rich source of nutrients, antibodies and growth factors.

AIM

To examine the efficacy of colostrum enemas in the treatment of distal colitis using a randomized, double-blind, controlled protocol.

METHODS

Fourteen patients (eight female), with a mean age of 45 years (range, 16-75 years) and mild to moderately severe distal colitis (Powell-Tuck scoring system), received colostrum enema (100 mL of 10% solution) or placebo (albumin solution) b.d. for 4 weeks. Both groups also received mesalazine (1.6 g/day) or, if already taking it, had a dose increment of 1.6 g/day. Disease activity was documented at 0, 2 and 4 weeks.

RESULTS

After 4 weeks, the colostrum group showed a mean reduction in symptom score of - 2.9 (95% confidence interval (CI), - 5.4 to - 0.3), whereas the placebo group showed a mean response of + 0.5 (95% CI, - 2.4 to +3.4). The histological score improved in five of the eight patients in the colostrum group (mean response, - 0.9; 95% CI, - 1.69 to - 0.03), whereas the histological scores only improved in two of the six patients in the placebo group (mean response, 0.2; 95% CI, - 2.4 to +2.6).

CONCLUSIONS

Bovine colostrum enema shows potential as a novel therapy for left-sided colitis with additional benefits over using mesalazine alone. Further studies appear to be warranted.

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

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

Protective effects of neurokinin-1 receptor during colitis in mice: role of the epidermal growth factor receptor

1. The role of substance P and its high affinity neurokinin-1 receptor in colitis has not been fully elucidated. We assessed the participation of neurokinin-1 receptor in colitis using the 2,4,6,-trinitrobenzensulphonic acid and dextran sulphate-induced animal models of colitis and genetically-engineered, neurokinin-1 receptor-deficient mice. 2. Clinical signs, macroscopic and histologic damage associated with 2,4,6,-trinitrobenzensulphonic acid (12 days) and dextran sulphate (5 days) colitis were more severe in neurokinin-1 deficient than in wild-type mice, while immunoreactivities for epidermal growth factor and its receptor were similar in the colon of both mice strains before and after colitis. 3. Substance P, dose-dependently induced intestinal fibroblast proliferation and enhanced epidermal growth factor-induced proliferation in intestinal fibroblasts isolated from wild-type, but not from neurokinin-1 receptor deficient mice. 4. Substance P-induced intestinal fibroblast proliferation required the presence of epidermal growth factor receptor with kinase activity. Furthermore, substance P induced epidermal growth factor tyrosine phosphorylation and activation in normal intestinal fibroblasts. 5. Our results indicate that in mice lacking the neurokinin - 1 receptor, substance P plays a protective role in prolonged experimental colitis.

Effects of TGF-alpha gene knockout on epithelial cell kinetics and repair of methotrexate-induced damage in mouse small intestine

While previous studies have indicated that exogenous TGF-alpha stimulates epithelial growth, maintenance, and repair of the gut, roles of endogenous TGF-alpha are less well-defined particularly in the small bowel. The current study examined effects of TGF-alpha knockout on adult small intestinal epithelial cell proliferation, migration, apoptosis, and damage/repair response after methotrexate treatment. Compared to normal mice, TGF-alpha gene knockout did not affect crypt cell production, mitosis position, migration, and apoptosis in non-injured intestine. RT-PCR gene expression analysis revealed presence of four out of six TGF-alpha related EGF family ligands in the normal intestine, suggesting a possible functional redundancy of the EGF family in maintenance of the intestine. Although TGF-alpha gene knockout did not significantly impair the overall mucosal repair in methotrexate-induced acute damage in the small intestine, it resulted in a higher apoptotic response in the early hours following methotrexate challenge, and a delayed and reduced crypt cell proliferation during repair. Consistently, after methotrexate challenge, intestinal TGF-alpha mRNA was found to be markedly upregulated in the early hours and during repair in the wild type, and there were similar profiles in the increased expression of all other ligands (except EGF) between the wild type and knockout intestines. Therefore, despite a possible functional redundancy among the EGF family ligands in the normal small intestine, TGF-alpha may play a role in modulating the early apoptotic events and in enhancing the subsequent reparative proliferative response in the methotrexate-damaged intestine.

A major quantitative trait locus on chromosome 3 controls colitis severity in IL-10-deficient mice

Colitic lesions are much more severe in C3H/HeJBir (C3H) than C57BL/6J (B6) mice after 10 backcrosses of a disrupted interleukin-10 (Il10) gene. This study identified cytokine deficiency-induced colitis susceptibility (Cdcs) modifiers by using quantitative trait locus (QTL) analysis. A segregating F(2) population (n = 408) of IL-10-deficient mice was genotyped and necropsied at 6 weeks of age. A major C3H-derived colitogenic QTL (Cdcs1) on chromosome (Chr.) 3 contributed to lesions in both cecum [logarithm of odds ratio (LOD) = 14.6)] and colon (LOD = 26.5) as well as colitis-related phenotypes such as spleen/body weight ratio, mesenteric lymph node/body weight ratio, and secretory IgA levels. Evidence for other C3H QTL on Chr. 1 (Cdcs2) and Chr. 2 (Cdcs3) was obtained. Cdcs1 interacted epistatically or contributed additively with loci on other chromosomes. The resistant B6 background also contributed colitogenic QTL: Cdcs4 (Chr. 8), Cdcs5 (Chr. 17, MHC), and Cdcs6 (Chr. 18). Epistatic interactions between B6 QTL on Chr. 8 and 18 contributing to cecum hyperplasia were particularly striking. In conclusion, a colitogenic susceptibility QTL on Chr. 3 has been shown to exacerbate colitis in combination with modifiers contributed from both parental genomes. The complex nature of interactions among loci in this mouse model system, coupled with separate deleterious contributions from both parental strains, illustrates why detection of human inflammatory bowel disease linkages has proven to be so difficult. A human ortholog of the Chr. 3 QTL, if one exists, would map to Chr. 4q or 1p.

Epithelial cell-derived components induce transforming growth factor-alpha mRNA expression and epithelial cell proliferation in vitro

BACKGROUND

Epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha protect the gastrointestinal mucosa against injury. In response to mucosal injury TGF-alpha, but not EGF, is locally increasingly expressed in the mucosa of the rat colon and stomach 4-8 h after injury. The aim of our present study was to characterize the possible signal for the induction of TGF-alpha expression.

METHODS

Monolayers of the non-transformed intestinal epithelial cell (IEC)-6 and IEC-18 lines were harvested, homogenized and shock-frozen at -80 degrees C for 1 h. Cell cultures of intact IEC-6 or IEC-18 cells were exposed to these cell homogenates and modulation of epithelial cell migration and proliferation was evaluated using standardized procedures as described previously. TGF-alpha mRNA expression in the exposed epithelial cell monolayers was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and normalized to the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

RESULTS

The proliferation of IEC-6 and IEC-18 epithelial cell monolayers was significantly inhibited if epithelial cell homogenates of 2000 cells/ml or more, and significantly induced if homogenates of less than 2000 cells/ml, were applied to the medium of the monolayers in vitro. In proliferating epithelial cells, a significant two-fold increase in TGF-alpha mRNA expression was obtained at 48 h and 72 h after application of the cell homogenates. The homogenate-induced epithelial cell proliferation was completely abolished after preincubation of the epithelial cell homogenates with neutralizing monoclonal anti-TGF-alpha antibodies. No effect on epithelial cell migration was noticed after application of epithelial-cell homogenates to the cell cultures.

CONCLUSIONS

Epithelial cell-derived components induce TGF-alpha mRNA expression and TGF-alpha-dependent cell proliferation of intact epithelial cells. We hypothesize that epithelial cell interaction bears one of the possible signals for the increased TGF-alpha mRNA expression after mucosal injury.