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

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.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

mRNA level of genes related to apoptosis in a colitis model in rats treated with epidermal growth factor

The deregulation of cell death pathways in intestinal epithelial cells could involve the pathogenesis of Inflammatory Bowel Diseases. An increase in apoptosis has been observed in patients who have Ulcerative Colitis. Previous experiments have demonstrated the efficacy of EGF in the healing of ulcerative Colitis and other gastrointestinal mucosa lesions. However, there are not many reports on the molecular characterization of EGF's positive effect on the gastrointestinal mucosa. This work aims to deepen the transcriptional changes induced by EGF in the intestinal epithelium in a colitis model in rats. Samples from the distal colon of an EGF-treated colitis model were collect, followed by an analysis by quantitative PCR of the mRNA of 23 genes related to apoptosis. 57% of the genes analyzed presented statistically significant changes in their mRNA level. Of these, two anti-apoptotic genes increased their mRNA level, while the genes that decreased their mRNA level were pro-apoptotic genes and genes related to the TNFα signal transmission path. Changes in the transcription profile of the genes analyzed could suggest a reduction of apoptosis, which could favor the integrity of the Intestinal Epithelium

Marked variability in bioactivity between commercially available bovine colostrum for human use; implications for clinical trials

Background

Colostrum, the milk produced during first few days after birth, is rich in immunoglobulins, antimicrobial peptides & growth factors. Multiple clinical trials using bovine colostrum are ongoing but with no assessment of test product bioactivity.

Objectives

To examine variability of bioactivity between 20 commercial colostrum products, contribution of TGFβ and EGFR in mediating effects, heat sensitivity of bioactivity and changes in bioactivity of colostrum milkings in the days following calving.

Design

In vitro bioactivity used AGS, RIE-1 and Caco-2 cell proliferation (Alamar blue) and migration (wounded monolayers) assays. Changes in colostrum bioactivity determined following addition of TGFβ-neutralising antibody, EGFR blocker (Typhostin) and after heating (40–60°C, 60 min). In vivo bioassay assessed ability of colostrum gavage (2ml, 7mg/ml) to reduce gastric damage (NSAID + restraint) in rats. Milkings from 6 cows, days 0–3 post calving were assessed for bioactivity and growth factor concentrations.

Result

Six-fold differences in pro-proliferative and migratory activity were seen comparing commercial products. Comparison of most- and least-active samples from in vitro studies showed two- to three-fold differences in ability to reduce gastric injury (86% reduction using most-active vs 48% using least-active, p<0.01). Tyrphostin reduced pro-migratory and proliferative activity by 23% and 55%. TGFβ neutralisation reduced migratory activity by 83% but did not affect proliferation Heating colostrum powder to 50°C did not affect immunoactivity of haptoglobin, EGF, TGFβ, IgG, IGF-1 or betacellulin but decreased bioactivity by >40%. Milking studies showed high bioactivity during first and second milkings on day 0 but 77% reduction by day 3. Changes in total protein, haptoglobin, EGF, TGFβ, IgG and IGF-1 paralleled falls in bioactivity.

Conclusion

Commercial colostrum products possess widely different bioactivity. Variation in heat exposure and/or proportion of day 0 colostrum content may contribute to this. Assessment of colostrum bioactivity has advantages to growth factor quantitation for quality control.

Chemical synthesis of human trefoil factor 1 (TFF1) and its homodimer provides novel insights into their mechanisms of action

TFF1 is a key peptide for gastrointestinal protection and repair. Its molecular mechanism of action remains poorly understood with synthetic intractability a recognised bottleneck. Here we describe the synthesis of TFF1 and its homodimer and their interactions with mucins and Helicobacter pylori. Synthetic access to TFF1 is an important milestone for probe and therapeutic development.

Structure, Function, and Therapeutic Potential of the Trefoil Factor Family in the Gastrointestinal Tract

Trefoil factor family peptides (TFF1, TFF2, and TFF3) are key players in protecting, maintaining, and repairing the gastrointestinal tract. Accordingly, they have the therapeutic potential to treat and prevent a variety of gastrointestinal disorders associated with mucosal damage. TFF peptides share a conserved motif, including three disulfide bonds that stabilize a well-defined three-loop-structure reminiscent of a trefoil. Although multiple functions have been described for TFF peptides, their mechanisms at the molecular level remain poorly understood. This review presents the status quo of TFF research relating to gastrointestinal disorders. Putative TFF receptors and protein partners are described and critically evaluated. The therapeutic potential of these peptides in gastrointestinal disorders where altered mucosal biology plays a crucial role in the underlying etiology is discussed. Finally, areas of investigation that require further research are addressed. Thus, this review provides a comprehensive update on TFF literature as well as guidance toward future research to better understand this peptide family and its therapeutic potential for the treatment of gastrointestinal disorders.

Pasteurized Chicken Egg Powder Stimulates Proliferation and Migration of AGS, RIE1, and Caco-2 Cells and Reduces NSAID-Induced Injury in Mice and Colitis in Rats

BACKGROUND

Chicken eggs and bovine colostrum contain proteins possessing antimicrobial, immunoregulatory, and growth factor activity. The ability of eggs to influence gut defense and repair is largely unexplored.

OBJECTIVE

We examined the effect of pasteurized spray-dried egg on gastrointestinal injury using cell culture and animal models and sought to determine whether adding colostrum provided extra benefit.

METHODS

Egg alone, colostrum alone, and a 40:60 egg: colostrum combination were tested for proliferative (Alamar blue) and migratory (wounded monolayer) activity at 1 mg.mL-1 using human colon adenocarcinoma (Caco-2), human gastric cancer (AGS), and rat intestinal epithelioid-1 (RIE1) cells. Four groups of adult male C57BL/6 mice received 20 mg.kg-1.d-1 test products in drinking water for 7 d and indomethacin (85 mg.kg-1, administered subcutaneously) on day 7. Villus height and morphology were assessed. Three groups of adult male Sprague Dawley rats received 20 mg.kg-1.d-1 test product by gavage for 9 d and dextran sodium sulfate (DSS, 4% in drinking water) for the final 7 d. Histology, microscopic damage scoring, and myeloperoxidase were assessed.

RESULTS

Egg or colostrum alone caused 3-fold increases in cell proliferation and migration (P < 0.05 compared with baseline). Heating the egg removed its bioactivity. Addition of neutralizing antibodies or tyrphostin showed that ovomucoid, ovalbumin, and the epidermal growth factor receptor mediated the effects of egg (all P < 0.05 compared with egg). Egg reduced shortening of villi caused by indomethacin in mice by 34% and reduced DSS-induced colonic damage in rats by 44-61% (P < 0.05 compared with DSS). Similar results were seen using colostrum alone. In each assay, the 40:60 combination gave improved results compared with the same dose of egg or colostrum alone (P < 0.05).

CONCLUSIONS

Studies using AGS, RIE1, and Caco-2 cells, C57BL/6 mice, and Sprague Dawley rats showed protective effects of egg against gut injury. Enhanced results were seen if colostrum and egg were coadministered. Egg powder with or without colostrum may have therapeutic value for prevention and treatment of gut injuries.

Pancreatic secretory trypsin inhibitor reduces multi-organ injury caused by gut ischemia/reperfusion in mice

Intestinal ischemia/reperfusion (I/R) injury occurs during transplantation, mesenteric arterial occlusion, trauma and shock, causing systemic inflammation, multiple organ dysfunction and high mortality. Pancreatic secretory trypsin inhibitor (PSTI), a serine protease inhibitor expressed in gut mucosa may function as a mucosal protective/repair peptide. We examined whether PSTI affected mesenteric I/R-induced injury. Hypoxia/normoxia (H/N) caused 50% drop in cell viability of AGS, RIE1 and Caco-2 cells but PSTI (10 μg/ml) given prior- or during-hypoxic period improved survival by 50% (p<0.01). Similarly, Caco-2 monolayers exposed to H/N had 300% increase in transepithelial permeability, PSTI truncated this by 50% (p<0.01). Mice underwent mesenteric I/R by clamping jejunum, causing severe mucosal injury, increased apoptotic markers and 3-fold increases in plasma IL-6, IL1β, TNFα, and tissue lipid peroxidation (MDA) and inflammatory infiltration (MPO) levels. Lungs showed similar significant injury and inflammatory infiltrate markers. Smaller increases in MDA and MPO were seen in kidney & liver. PSTI (20 mg/kg) reduced all injury markers by 50–80% (p<0.01). In vitro and in vivo studies showed PSTI reduced pro-apoptotic Caspase 3, 9 and Baxα levels, normalised Bcl2 and caused additional increases in HIF1α, VEGF and Hsp70 above rises caused by I/R alone (all p<0.01). PSTI also prevented reduction of tight junction molecules ZO1 and Claudin1 (all p<0.01) but did not affect increased ICAM-1 caused by I/R in gut or lung. PSTI may be a useful clinical target to prevent I/R injury.

Trefoil Factor Peptides and Gastrointestinal Function

Trefoil factor (TFF) peptides, with a 40-amino acid motif and including six conserved cysteine residues that form intramolecular disulfide bonds, are a family of mucin-associated secretory molecules mediating many physiological roles that maintain and restore gastrointestinal (GI) mucosal homeostasis. TFF peptides play important roles in response to GI mucosal injury and inflammation. In response to acute GI mucosal injury, TFF peptides accelerate cell migration to seal the damaged area from luminal contents, whereas chronic inflammation leads to increased TFF expression to prevent further progression of disease. Although much evidence supports the physiological significance of TFF peptides in mucosal defenses, the molecular and cellular mechanisms of TFF peptides in the GI epithelium remain largely unknown. In this review, we summarize the functional roles of TFF1, 2, and 3 and illustrate their action mechanisms, focusing on defense mechanisms in the GI tract.

Pancreatic duct glands (PDGs) are a progenitor compartment responsible for pancreatic ductal epithelial repair

Pancreatic duct glands (PDGs) have molecular features known to mark stem cell niches, but their function remains to be determined. To investigate the role of PDGs as a progenitor niche, PDGs were analyzed in both humans and mice. Cells were characterized by immunohistochemistry and microarray analysis. In vivo proliferative activity and migration of PDG cells were evaluated using a BrdU tag-and-chase strategy in a mouse model of pancreatitis. In vitro migration assays were used to determine the role of trefoil factor (TFF) -1 and 2 in cell migration. Proliferative activity in the pancreatic epithelium in response to inflammatory injury is identified principally within the PDG compartment. These proliferating cells then migrate out of the PDG compartment to populate the pancreatic duct. Most of the pancreatic epithelial migration occurs within 5days and relies, in part, on TFF-1 and -2. After migration, PDG cells lose their PDG-specific markers and gain a more mature pancreatic ductal phenotype. Expression analysis of the PDG epithelium reveals enrichment of embryonic and stem cell pathways. These results suggest that PDGs are an epithelial progenitor compartment that gives rise to mature differentiated progeny that migrate to the pancreatic duct. Thus PDGs are a progenitor niche important for pancreatic epithelial regeneration.

Generation of Lactococcus lactis capable of coexpressing epidermal growth factor and trefoil factor to enhance in vitro wound healing

Epidermal growth factor (EGF) and trefoil factor 3 (TFF3) are peptides that actively support the restitution and repair of mucosal epithelial barriers. Previous studies have shown that TFF3 enhanced EGF effect in wound healing, suggesting that the combined application of the two factors may be advantageous in clinical tissue repair. Expression of multiple proteins in a single host is a desirable approach in a biotechnological process, allowing to reduce cost and increase production efficiency. The aim of the present study was to study the feasibility of coexpressing EGF and TFF3 in food grade bacteria, Lactococcus lactis (L. lactis). Using an expression construct allowing simultaneous translation of two separate recombinant peptides, we generated a L. lactis that coexpressed and secreted EGF and TFF3 dually (LL-ET). Western blot analysis revealed that LL-ET secreted 45-54 % more total recombinant peptides (EGF+TFF3) per flask fermentation and 21-37 % more total recombinant proteins in bioreactor fermentation compared to their single factor expressing L. lactis counterparts (LL-EGF and LL-TFF3, respectively). The resulted recombinant EGF and TFF3 showed enhancement in wound healing activity in vitro. Our data suggest that the dual expression and secretion of EGF and TFF3 by L. lactis effectively accelerated cell migration, demonstrating potential future oral application of L. lactis fermentation product containing dual factors or a cocktail of factors to potentially treat intestinal damage and inflammation.

Proteins and peptides: The need to improve them as promising therapeutics for ulcerative colitis

The present review briefly describes the nature, type and pathogenesis of ulcerative colitis, and explores the potential use of peptides and proteins in the treatment of inflammatory bowel disease, especially ulcerative colitis. Intestinal absorption and the barrier mechanism of peptide and protein drugs are also discussed, with special emphasis on various strategies which make these drugs better therapeutics having high specificity, potency and molecular targeting ability. However, the limitation of such therapeutics are oral administration, poor pharmacokinetic profile and decreased bioavailability. The recent findings illustrated in this review will be helpful in designing the peptide/protein drugs as a promising treatment of choice for ulcerative colitis.

Trefoil factors in inflammatory bowel disease

Inflammatory bowel disease (IBD), which comprises ulcerative colitis and Crohn’s disease, is characterized by inflammation of the gastrointestinal tract. The trefoil factors 1, 2, and 3 (TFF1-3) are a family of peptides that play important roles in the protection and repair of epithelial surfaces, including the gastrointestinal tract. TFFs may be involved in IBD pathogenesis and are a potential treatment option. In the present review, we describe the TFF family and their potential role in IBD by summarizing the current knowledge of their expression, possible function and pharmacological role in IBD.

Deleterious effects of indomethacin in the mid-gestation human intestine

The use of the anti-inflammatory drug indomethacin (INDO) in preterm infants has been associated with an increased risk of developing enteropathies. In this study, we have investigated the direct impact of INDO on the human mid-gestation intestinal transcriptome using serum-free organ culture. After determining the optimal dose of 1 μM of INDO (90% inhibition of intestinal prostaglandin E2 production and range of circulating levels in treated preterm babies), global gene expression profiles were determined using Illumina bead chip microarrays in both small and large intestines after 48 h of INDO treatment. Using Ingenuity Pathway Analysis software, we identified critical metabolic pathways that were significantly altered by INDO in both intestinal segments including inflammation and also glycolysis, oxidative phosphorylation and free radical scavenging/oxidoreductase activity, which were confirmed by qPCR at the level of individual genes. Taken together, these data revealed that INDO directly exerts multiple detrimental effects on the immature human intestine.

Anti-inflammatory effects of epidermal growth factor on the immature human intestine

The inflammatory response of the preterm infants' intestine underlines its inability to respond to hemodynamic stress, microbes, and nutrients. Recent evidence suggests that exogenous epidermal growth factor (EGF) exerts a therapeutic influence on neonatal enteropathies. However, the molecular mechanisms underlying the beneficial effects of EGF remain to be clarified. The purpose of this study was to evaluate the impact of EGF on the gene expression profiles of the developing human small and large intestine at midgestation in serum-free organ cultures using microarrays. The gene expression profiles of cultured human fetal ileal and colonic explants were investigated in the absence or presence of a physiological concentration of 50 ng/ml EGF for 48 h. Data were analyzed with the Ingenuity Pathway Analysis (IPA) software and confirmed by qPCR. We found a total of 6,474 differentially expressed genes in the two segments in response to EGF. IPA functional analysis revealed that in addition to differentially modulating distinct cellular, molecular, and physiological functions in the small and large intestine, EGF regulated the inflammatory response in both intestinal segments in a distinct manner. For instance, several intestinal-derived chemokines such as CCL2, CCL25, CXCL5, and CXCL10 were found to be differentially regulated by EGF in the immature ileum and colon. The findings showing the anti-inflammatory influence of exogenous EGF suggests a mechanistic basis for the beneficial effects of EGF on neonatal enteropathies. These results reinforce growing evidence that by midgestation, the human small intestine and colon rely on specific and distinct regulatory pathways.

Essential roles of IL-6 trans-signaling in colonic epithelial cells, induced by the IL-6/soluble-IL-6 receptor derived from lamina propria macrophages, on the development of colitis-associated premalignant cancer in a murine model

Activation of the IL-6/Stat3 via IL-6 trans-signaling plays an important role in the pathogenesis of inflammatory bowel disease. Colitis-associated cancer (CAC) is a large bowel cancer and occurs with long-standing inflammatory bowel disease. The role of the IL-6/Stat3 in the development of CAC has not been fully understood. We investigate whether IL-6 trans-signaling contributes to the development of CAC using a mouse colitis-associated premalignant cancer (CApC) model. Chronic colitis (CC) was induced in BALB/c mice using dextran sodium sulfate. CApC was induced by dextran sodium sulfate treatment to CC-affected mice. IL-6 expression was determined by quantitative RT-PCR and immunofluorescence staining in colon. Phospho-Stat3 expression was examined by Western blotting and immunofluorescence analysis. The expression of IL-6 receptors (i.e., the IL-6R alpha-chain and gp130) and tumor necrosis factor-alpha converting enzyme in the colon was examined by laser-capture microdissection and immunofluorescence staining. Soluble IL-6R alpha (sIL-6R alpha) was examined by Western blotting of epithelial cell-depleted colonic tissues. We also investigated whether a soluble gp130-Fc fusion protein could prevent CApC. IL-6 expression was increased in the colon of CC- and CApC-affected mice and was restricted to lamina propria-macrophages. The expression of IL-6R alpha and tumor necrosis factor-alpha converting enzyme was increased in the lamina propria CD11b-macrophages of CC-affected mice. sIL-6R alpha expression was also increased in these tissues. Reduced levels of IL-6R alpha generation were observed in the colonic epithelial cells of CC- and CApC-affected mice and were associated with the increased expression of gp130 and phospho-Stat3. Treatment with soluble gp130Fc significantly reduced the CApC. IL-6 trans-signaling in epithelial cells induced by macrophage-derived IL-6/sIL-6R alpha plays a crucial role in the development of CAC.

Induction of Na+/K+/2Cl- cotransporter expression mediates chronic potentiation of intestinal epithelial Cl- secretion by EGF

Alterations in EGF receptor (EGFR) signaling occur in intestinal disorders associated with dysregulated epithelial transport. In the present study, we investigated a role for the EGFR in the chronic regulation of intestinal epithelial secretory function. Epithelial Cl(-) secretion was measured as changes in short-circuit current (Isc) across voltage-clamped monolayers of T84 cells in Ussing chambers. Acute treatment of T84 cells with EGF (100 ng/ml, 15 min) chronically enhanced Isc responses to a broad range of secretagogues. This effect was apparent within 3 h, maximal by 6 h, and sustained for 24 h after treatment with EGF. The Na+/K+/2Cl(-) cotransporter (NKCC1) inhibitor bumetanide (100 microM) abolished the effect of EGF, indicating increased responses are due to potentiated Cl(-) secretion. Neither basal nor agonist-stimulated levels of intracellular Ca2+ or PKA activity were altered by EGF, implying that the effects of the growth factor are not due to chronic alterations in levels of second messengers. EGF increased the expression of NKCC1 with a time course similar to that of its effects on Cl(-) secretion. This effect of EGF was maximal after 6 h, at which time NKCC1 expression in EGF-treated cells was 199.9 +/- 21.9% of that in control cells (n = 21, P < 0.005). EGF-induced NKCC1 expression was abolished by actinomycin D, and RT-PCR analysis demonstrated EGF increased expression of NKCC1 mRNA. These data increase our understanding of mechanisms regulating intestinal fluid and electrolyte transport and reveal a novel role for the EGFR in the chronic regulation of epithelial secretory capacity through upregulation of NKCC1 expression.

Human pancreatic secretory trypsin inhibitor stabilizes intestinal mucosa against noxious agents

Pancreatic secretory trypsin inhibitor (PSTI) is a serine protease inhibitor, expressed in gut mucosa, whose function is unclear. We, therefore, examined the effects of PSTI on gut stability and repair. Transgenic mice overexpressing human PSTI within the jejunum (FABPi(-1178 to +28) hPSTI construct) showed no change in baseline morphology or morphometry but reduced indomethacin-induced injury in overexpressing hPSTI region by 42% (P < 0.01). Systemic recombinant hPSTI did not affect baseline morphology or morphometry but truncated injurious effects in prevention and recovery rat models of dextran-sodium-sulfate-induced colitis. In vitro studies showed PSTI stimulated cell migration but not proliferation of human colonic carcinoma HT29 or immortalized mouse colonic YAMC cells. PSTI also induced changes in vectorial ion transport (short-circuit current) when added to basolateral but not apical surfaces of polarized monolayers of Colony-29 cells. Restitution and vectorial ion transport effects of PSTI were dependent on the presence of a functioning epidermal growth factor (EGF) receptor because cells with a disrupted (EGFR(-/-) immortalized cells) or neutralized (EGFR blocking antibodies or tyrosine kinase inhibitor) receptor prevented these effects. PSTI also reduced the cytokine release of lipopolysaccharide-stimulated dendritic cells. We conclude that administration of PSTI may provide a novel method of stabilizing intestinal mucosa against noxious agents and stimulating repair after injury.

TFF3 and EGF induce different migration patterns of intestinal epithelial cells in vitro and trigger increased internalization of E-cadherin

BACKGROUND/AIMS

TFF3, a member of the TFF (trefoil factor family) peptides, and epidermal growth factor (EGF) actively support the repair of mucosal barriers, particularly during restitution. The aim of this study was to compare the motogenic effects of TFF3 and EGF.

METHODS

The influence of recombinant human TFF3 (dimeric form) and EGF on the migration of IEC-18 cells was characterized in an in vitro restitution model (scratch wound assay) with the help of time-lapse video microscopy, morphometry, and immunocytochemistry including confocal laser scanning microscopy.

RESULTS

TFF3- and EGF-treated cells re-populated the wounded area via different migration patterns; TFF3 treatment resulted in the formation of continuous sheets of migrating cells with only a few gaps. In contrast, EGF-treated cells formed a network of migrating cells (often with a fibroblast-like morphology) with numerous gaps and only punctual contacts. TFF3 and EGF treatment also changed the localization of E-cadherin indicating endocytotic recycling and/or degradation of E-cadherin.

CONCLUSION

TFF3, in contrast to EGF, enhanced a collective cell migration ensuring a precise coverage of the re-populated area avoiding gaps.

Pharmacokinetics of trefoil peptides and their stability in gastrointestinal contents

Trefoil factor family (TFF) peptides are considered promising for therapeutic use in gastrointestinal diseases, and there is a need to explore the fate of injected TFF and the stability of the peptides in the gastrointestinal tract. We studied the pharmacokinetics of intravenously (i.v.) administered hTFF2 in mice and rats and of hTFF3 administered i.v., intramuscularly, intraperitoneally, and subcutaneously in mice, and estimated by ELISA the decay of the peptides added to rat and human gastrointestinal contents. We found that i.v. injected hTFF2 and hTFF3 were cleared from the circulation within 2-3h, exhibiting comparable pharmacokinetic profiles. In contents from the rat stomach, hTFF levels remained unchanged for up to 6 days. In the small and large intestine of rats, the hTFF levels decreased markedly after 4 and 1h, respectively. In small intestinal contents from humans, the levels remained stable for more than 24h. We conclude that systemically administered hTFF2 and hTFF3 are rapidly eliminated from the circulation and that the stability of hTFF2 and hTFF3 in GI contents appeared higher in the gastric and small intestinal milieu than in the large intestine and feces, suggesting a higher stability toward gastric acid and digestive enzymes than toward microbial degradation.

Cellular localization, binding sites, and pharmacologic effects of TFF3 in experimental colitis in mice

Trefoil factors (TFFs) are essential for protection and restitution of the gastrointestinal mucosa but many aspects of TFF biology are unclear. Our aim was to compare the localization of endogenous TFFs and binding sites for injected TFF3 in the colon of healthy and colitic mice and to study the effect of TFF3 on dextrane sulfate sodium (DSS)-induced colitis in mice. Expression of endogenous TFF1-3 was examined by in situ hybridization and immunohistochemistry, and the distribution of intravenously, intraperitoneally, and subcutaneously administered (125)I-TFF3 by autoradiography and gamma-counting. The effect of systemically administered TFF3 on DSS-induced colitis was assessed. We found increased expression of endogenous TFF3 and increased binding of injected (125)I-TFF3 in the colon of animals with DSS-induced colitis. The distribution of intraperitoneally and subcutaneously administered (125)I-TFF3 was comparable. Systemic administration of the peptides reduced the severity of colitis. Expression of endogenous TFF3 and binding of systemically administered TFF3 are increased in DSS-induced colitis. Systemic administration of TFF3 attenuates the disease. These findings suggest a role of TFF3 in mucosal protection.

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

Luminal and parenteral TFF2 and TFF3 dimer and monomer in two models of experimental colitis in the rat

BACKGROUND

Peptides of the trefoil factor family (TFF1, TFF2 and TFF3) are cosecreted with mucus from mucus-producing cells in most organ systems and are believed to interact with mucus to form high-viscosity stable gel complexes. In the gastrointestinal tract, they sustain the mucosal barrier, and both injected and orally administered TFF peptide have protective and healing functions in the gastric mucosa.

AIM

To investigate the possible treatment effect of luminally and parenterally administered TFF peptides in experimental colitis in rats.

METHODS

Colitis was induced by administration of 5% dextran sodium sulphate in the drinking water or by one intraperitoneal injection of mitomycin C, 3.75 mg/kg. TFF peptides were administered as subcutaneous injections or directly into the lumen via a catheter placed in the proximal colon. Treatments were saline, TFF2, TFF3 monomer or TFF3 dimer 5 mg/kg twice per day throughout the study [dextran sulphate sodium (DSS)] or from day 4 to 7 (mitomycin C). Colitis severity was scored in a stereomicroscope and histologically.

RESULTS

Luminal treatment with TFF3 in its dimeric form significantly improved the colitis score in both colitis models, whereas TFF2 had positive effect only in DSS-induced colitis. The TFF3 monomer was without any effects in both models. Treatment effect was most pronounced in the middle part of the colon, closest to the tip of the catheter. Injected TFF peptides, especially the TFF3 monomer, aggravated the colitis score in both colitis models.

CONCLUSIONS

Intracolonic administration of TFF3 dimer and TFF2 improves experimentally induced colitis in rats. The TFF3 monomer has no effect. Parenteral administration of TFF peptides aggravates the colitis especially the TFF3 monomer.

Trial of trefoil factor 3 enemas, in combination with oral 5-aminosalicylic acid, for the treatment of mild-to-moderate left-sided ulcerative colitis

BACKGROUND

Current treatment of ulcerative colitis is imperfect. Trefoil peptides are known to stimulate repair in many models of injury, including animal models of colitis.

AIM

To assess the efficacy of trefoil factor family-3 enema treatment in a clinical trial.

METHODS

A total of 16 patients with mild-to-moderate left sided ulcerative colitis were recruited into a double-blind randomized placebo-controlled study. Patients taking steroids or with proctitis only were excluded. Patients received 75 mL enemas containing either human recombinant trefoil factor family-3 (10 mg/mL) or saline alone once a day for 14 days. All patients also received an oral dose-increment of 1.2 g of mesalazine daily above their normal usage. Patients were assessed at 0, 2, 4 and 12 weeks. Remission was defined as Ulcerative Colitis Disease Activity Index of 0 or 1 with no blood in stool. Individual clinical improvement was defined as a Ulcerative Colitis Disease Activity Index reduction of >3. Data was analysed using chi-square test and anova.

RESULTS

Median Ulcerative Colitis Disease Activity Index at entry were 8.5 (trefoil factor family-3 group) and 8 (placebo group). Analysed on an intention-to-treat basis, only one patient went into remission (in trefoil factor family-3 group at day 28). Clinical improvement was seen in two trefoil factor family-3 and three placebo patients on day 14 and two patients in each group on day 28.

CONCLUSION

Increasing the dose of 5-aminosalicylic acid was moderately effective in reducing the Ulcerative Colitis Disease Activity Index but was insufficient to induce remission. Trefoil factor family-3 enemas were well-tolerated but did not provide additional benefit above that of adding additional 5-aminosalicylic acid alone.

Trefoil factor family (TFF) peptides of normal human Vater's ampulla

Vater's ampulla is of great clinical relevance with regard to the influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic maneuvers, therapeutic papillotomy and, especially, the formation of malignancies. Little is known about the distribution of trefoil factor family (TFF) peptides in the ampulla. We have therefore examined TFF peptide distribution in the normal ampulla of Vater and compared it with that in duodenal mucosa and Brunner's glands. Expression and synthesis of TFF peptides in Vater's ampulla and duodenum was investigated by reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. The samples studied originated from 30 autopsy cases with short postmortem intervals. TFF3 was expressed in the ampulla of Vater. mRNA expression of TFF1 was detected in only approximately 25% of the investigated samples. Western blot revealed the production of TFF3 and immunohistochemistry showed that TFF3 was the product of goblet cells. TFF peptide composition of Vater's ampulla varied in comparison with that in the duodenum regarding TFF2 expression. The ampulla of Vater thus has a unique profile of TFF peptide production, supporting the hypothesis that the ampulla is an autonomous organ. The observed differences in the TFF peptide distribution between the duodenum and Vater's ampulla favour the investigation of TFF peptides as prognostic markers in the classification of ampullary carcinomas.

Epidermal growth factor and trefoil factor family 2 synergistically trigger chemotaxis on BEAS-2B cells via different signaling cascades

Injured areas of the respiratory epithelium are subject to rapid repair by the migration of adjacent epithelial cells, a process termed "restitution". Rapid re-epithelialization is promoted by interactions between migrating cells and the extracellular matrix proteins. Furthermore, epidermal growth factor (EGF) as well as trefoil factor family (TFF) peptides are well known regulators of epithelial restitution due to their motogenic effects. Migration of the human bronchial epithelial cell line BEAS-2B in modified Boyden chambers was used as a model system for airway restitution. EGF or recombinant human TFF2 or TFF3 showed mainly chemotactic activity. The motogenic response was strictly dependent upon a haptotactic substrate, but to different degrees. EGF induced phosphorylation of extracellular signal-regulated kinases (ERK) 1/2, c-Jun-N-terminal kinase, p38, Akt, and p70S6K in BEAS-2B cells. Using specific inhibitors, the signaling cascades responsible for the motogenic response were shown to differ drastically when EGF was compared with TFF2. The motogenic effect of TFF2 was previously demonstrated to depend on ERK1/2 and protein kinase C activation; whereas the EGF-triggered motogenic response was completely independent of ERK1/2 activation but sensitive to the inhibition of phosphoinositide 3-kinase, p38, protein kinase C, or nuclear factor kappaB. However, the motogenic effects of EGF and TFF2 are additive. These data suggest that luminal EGF and TFF peptides can act synergistically in the human respiratory epithelium to enhance rapid repair processes in the course of diseases such as asthma.