rHuKGF ameliorates symptoms in DSS and CD4(+)CD45RB(Hi) T cell transfer mouse models of inflammatory bowel disease

KGF inhibits hypoxia-induced intestinal epithelial cell apoptosis by upregulating AKT/ERK pathway-dependent E-cadherin expression

OBJECTIVE

Intestinal ischemia-reperfusion (I/R) causes direct cellular damage, and the potential injury to the mucosal structure and barrier function. Keratinocyte growth factor (KGF) is highly expressed in gastrointestinal tract and exerts beneficial effects for intestinal epithelial growth and maintenance. E-cadherin plays an important role in intestinal epithelium renewal. However, the regulatory role of KGF on E-cadherin levels and I/R-induced apoptosis remain to be explored. The present study aimed to identify the effect of KGF on E-cadherin expression and I/R-induced intestinal epithelial cell apoptosis.

METHODS

Caco2 cells were treated with KGF (100 ng/ml) for 0, 4, 8, 12, and 24 h under hypoxia or normoxia. An E-cadherin-knockdown model was successfully established by treatment with E-cadherin RNAi. Western blotting and immunofluorescence labeling were performed to assess E-cadherin expression. Levels of PI3K|[sol]|Akt/mitogen-activated protein kinases (MAPKs), phosphoinositide 3-kinase (PI3K|[sol]|Akt)/PI3K|[sol]|Akt pathway-related proteins, and apoptosis-related proteins were also detected by western blot. Finally, a rat model of acute intestinal I/R was established and treated with KGF. Hematoxylin-eosin (HE), terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL), and immunofluorescence staining were performed to detect morphological changes in intestinal mucosal epithelium and Caco2 cell apoptosis.

RESULTS

KGF enhanced E-cadherin expression in differentiated intestinal epithelial cells under hypoxia via AKT/extracellular-regulated kinase (ERK) pathway regulation. In vitro, E-cadherin downregulation aggravates hypoxia-induced intestinal epithelial cell apoptosis. In the rat model, KGF increased E-cadherin expression, which was associated with the reduced apoptosis.

CONCLUSIONS

KGF exerts protective effects on intestinal epithelial cells under hypoxia by elevating E-cadherin levels or activating AKT/ERK signaling.

Card9-dependent IL-1β regulates IL-22 production from group 3 innate lymphoid cells and promotes colitis-associated cancer

Inflammatory bowel diseases (IBD) are key risk factors for the development of colorectal cancer, but the mechanisms that link intestinal inflammation with carcinogenesis are insufficiently understood. Card9 is a myeloid cell-specific signaling protein that regulates inflammatory responses downstream of various pattern recognition receptors and which cooperates with the inflammasomes for IL-1β production. Because polymorphisms in Card9 were recurrently associated with human IBD, we investigated the function of Card9 in a colitis-associated cancer (CAC) model. Card9-/- mice develop smaller, less proliferative and less dysplastic tumors compared to their littermates and in the regenerating mucosa we detected dramatically impaired IL-1β generation and defective IL-1β controlled IL-22 production from group 3 innate lymphoid cells. Consistent with the key role of immune-derived IL-22 in activating STAT3 signaling during normal and pathological intestinal epithelial cell (IEC) proliferation, Card9-/- mice also exhibit impaired tumor cell intrinsic STAT3 activation. Our results imply a Card9-controlled, ILC3-mediated mechanism regulating healthy and malignant IEC proliferation and demonstrates a role of Card9-mediated innate immunity in inflammation-associated carcinogenesis.

Palifermin for the protection and regeneration of epithelial tissues following injury: new findings in basic research and pre-clinical models

Keratinocyte growth factor (KGF) is a paracrine-acting epithelial mitogen produced by cells of mesenchymal origin, that plays an important role in protecting and repairing epithelial tissues. Pre-clinical data initially demonstrated that a recombinant truncated KGF (palifermin) could reduce gastrointestinal injury and mortality resulting from a variety of toxic exposures. Furthermore, the use of palifermin in patients with hematological malignancies reduced the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. Based upon these findings, as well as the observation that KGF receptors are expressed in many, if not all, epithelial tissues, pre-clinical studies have been conducted to determine the efficacy of palifermin in protecting different epithelial tissues from toxic injury in an attempt to model various clinical situations in which it might prove to be of benefit in limiting tissue damage. In this article, we review these studies to provide the pre-clinical background for clinical trials that are described in the accompanying article and the rationale for additional clinical applications of palifermin.

JAM-related proteins in mucosal homeostasis and inflammation

Mucosal surfaces are lined by epithelial cells that form a physical barrier protecting the body against external noxious substances and pathogens. At a molecular level, the mucosal barrier is regulated by tight junctions (TJs) that seal the paracellular space between adjacent epithelial cells. Transmembrane proteins within TJs include junctional adhesion molecules (JAMs) that belong to the cortical thymocyte marker for Xenopus family of proteins. JAM family encompasses three classical members (JAM-A, JAM-B, and JAM-C) and related molecules including JAM4, JAM-like protein, Coxsackie and adenovirus receptor (CAR), CAR-like membrane protein and endothelial cell-selective adhesion molecule. JAMs have multiple functions that include regulation of endothelial and epithelial paracellular permeability, leukocyte recruitment during inflammation, angiogenesis, cell migration, and proliferation. In this review, we summarize the current knowledge regarding the roles of the JAM family members in the regulation of mucosal homeostasis and leukocyte trafficking with a particular emphasis on barrier function and its perturbation during pathological inflammation.

Keratinocyte growth factor improves epithelial structure and function in a mouse model of intestinal ischemia/reperfusion

Background

Intestinal ischemia/reperfusion (I/R) induces the desquamation of the intestinal epithelium, increases the intestinal permeability, and in patients often causes fatal conditions including sepsis and multiple organ failure. Keratinocyte growth factor (KGF) increases intestinal growth, although little is known about KGF activity on intestinal function after intestinal I/R. We hypothesized that KGF administration would improve the intestinal function in a mouse model of intestinal I/R.

Methods

Adult C57BL/6J mice were randomized to three groups: Sham, I/R group and I/R+KGF group. Mice were killed on day 5, and the small bowel was harvested for histology, wet weight, RNA and protein content analysis. Epithelial cell (EC) proliferation was detected by immunohistochemistry for PCNA, and apoptosis was determined by TUNEL staining. The expressions of Claudin-1 and ZO-1 were detected by immunohistochemistry. Epithelial barrier function was assessed with transepithelial resistance (TER).

Results

KGF significantly increased the intestinal wet weight, contents of intestinal protein and RNA, villus height, crypt depth and crypt cell proliferation, while KGF resulted in the decrease of epithelial apoptosis. KGF also stimulated the recovery of mucosal structures and attenuated the disrupted distribution of TJ proteins. Moreover, KGF attenuated the intestinal I/R-induced decrease in TER and maintained the intestinal barrier function.

Conclusion

KGF administration improves the epithelial structure and barrier function in a mouse model of intestinal I/R. This suggests that KGF may have clinical applicability.

Phase II, randomized, double-blind, placebo-controlled study of recombinant human intestinal trefoil factor oral spray for prevention of oral mucositis in patients with colorectal cancer who are receiving fluorouracil-based chemotherapy

PURPOSE

This study evaluated the safety and efficacy of recombinant human intestinal trefoil factor (rhITF) administered as topical oral spray for prevention and treatment of chemotherapy-induced oral mucositis (OM).

PATIENTS AND METHODS

Ninety-nine patients with colorectal cancer who had moderate to severe OM (WHO grade >or= 2) in the first cycle of chemotherapy were randomly assigned to receive either placebo, rhITF 10 mg/mL (ie, low dose), or rhITF 80 mg/mL (ie, high dose) by oral spray (300 microL, eight times each day) for 14 consecutive days in the second chemotherapy cycle. Patients were assessed on days 1, 3, 5, 7, 10, 12, 14, and 21 (+/- 2 days for the last assessment) for safety and for OM incidence and severity.

RESULTS

Treatment of patients at high risk for developing OM with low- or high-dose rhITF significantly reduced the amount of incidence (75% to 81%; low-dose rhITF P < .001; high-dose rhITF P = .002). Frequencies of WHO grade >or= 2 OM in the placebo, low-dose rhITF, and high-dose rhITF groups were 48.5%, 9.1%, and 12.1%, respectively. Assessment of the area under the curve revealed statistically significant reductions in OM severity in the rhITF-treated groups versus placebo. Only a minority of patients (6.1%) reported treatment-emergent adverse events (TEAEs), all of which were mild to moderate in intensity and resolved without sequelae. The incidence of TEAEs was not significantly different among treatment groups.

CONCLUSION

rhITF oral spray formulation was safe and effective when used for the reduction of chemotherapy-associated OM in patients with colorectal cancer. Patients exhibited high compliance in dosing administration. Future clinical study is planned to develop this drug for use in OM management in patients with cancer.

Regulatory lymphocytes and intestinal inflammation

The immune system is pivotal in mediating the interactions between host and microbiota that shape the intestinal environment. Intestinal homeostasis arises from a highly dynamic balance between host protective immunity and regulatory mechanisms. This regulation is achieved by a number of cell populations acting through a set of shared regulatory pathways. In this review, we summarize the main lymphocyte subsets controlling immune responsiveness in the gut and their mechanisms of control, which involve maintenance of intestinal barrier function and suppression of chronic inflammation. CD4(+)Foxp3(+) T cells play a nonredundant role in the maintenance of intestinal homeostasis through IL-10- and TGF-beta-dependent mechanisms. Their activity is complemented by other T and B lymphocytes. Because breakdown in immune regulatory networks in the intestine leads to chronic inflammatory diseases of the gut, such as inflammatory bowel disease and celiac disease, regulatory lymphocytes are an attractive target for therapies of intestinal inflammation.

Growth factor based therapies and intestinal disease: is glucagon-like peptide-2 the new way forward?

Inflammatory bowel disease (IBD) is a chronic, debilitating disease associated with severe damage to the intestinal mucosa. Glucagon-like peptide-2 (GLP-2) is a potent and specific gastrointestinal growth factor that is demonstrating therapeutic potential for the prevention or treatment of an expanding number of intestinal diseases, including short bowel syndrome (SBS), small bowel enteritis and IBD. The biological activity of GLP-2 is limited due to proteolytic inactivation by the protease dipeptidyl peptidase (DP)IV. Inhibitors of DPIV activity may represent a novel strategy to prolong the growth promoting actions of GLP-2. This review outlines evidence for the clinical application of GLP-2, its degradation resistant analogue, Teduglutide, and novel DPIV inhibitors in efficacy studies utilizing pre-clinical models of intestinal damage, in particular IBD.

Inducible nitric oxide synthase from bone marrow-derived cells plays a critical role in regulating colonic inflammation

BACKGROUND & AIMS

Nitric oxide (NO) is an important mediator of intestinal inflammation. Inducible NO synthase (iNOS) is the main source of NO in inflammation. Because iNOS is ubiquitously expressed, our aim was to determine which cellular source(s) of iNOS plays the central role in mediating intestinal inflammation.

METHODS

Chimeric lines were produced via bone marrow (BM) transplantation following irradiation. Colitis was induced with dextran sodium sulfate (DSS) or trinitrobenzene sulfonic acid (TNBS). The severity of colitis and markers of inflammation were assessed in standard fashion. Leukocyte recruitment was assessed by intravital microscopy.

RESULTS

The irradiated chimeric lines with iNOS-/- BM-derived cells were markedly more resistant to both DSS- and TNBS-induced injury. Resistance to DSS-induced colitis was lost when wild-type (wt) BM was used to reconstitute iNOS-/- mice. Neutrophils were the main source of iNOS in DSS-induced colitis. iNOS-/- chimeric lines had decreased colonic macrophage inflammatory protein 1beta and tumor necrosis factor alpha expression and increased levels of the protective growth factor, keratinocyte growth factor. LPS-mediated leukocyte recruitment was reduced in iNOS-/- mice, and there were marked changes in the inflammatory cell infiltrates between the chimeric lines with iNOS-/- vs wt BM-derived cells. Furthermore, the lamina propria CD4 +ve cells from chimeric lines with iNOS-/- BM-derived cells had reduced intracellular cytokine expression.

CONCLUSIONS

iNOS produced by BM-derived cells plays a critical role in mediating the inflammatory response during colitis. Cell-specific regulation of iNOS may represent a novel form of therapy for patients with inflammatory bowel disease.

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.

Trefoil factor family-3 is associated with aggressive behavior of colon cancer cells

BACKGROUND AND AIM

Trefoil factor family 3 (TFF3) is expressed by intestinal epithelial cells and it mainly functions to protect the mucosa from injury. Expression of TFF3 has been correlated with a poor prognosis in patients with cancer, but little is known about whether TFF3 directly contributes to the malignant behavior of cancer cells. The present study was conducted to determine whether TFF3 expression contributes to the malignant behavior of cancer cells in vitro and in vivo.

METHODS

Two subclones of a metastatic rat colorectal cancer cell line, demonstrated previously to manifest aggressive (LN cells) and non-aggressive (LP cells) growth in vivo, were analyzed for expression of TFF3 and tested in assays of cancer cell migration, invasion, and apoptosis in vitro, and mortality in vivo.

RESULTS

The aggressive LN cell line endogenously expressed TFF3 and supported the transcription of a TFF3 promoter-driven reporter construct, whereas the non-aggressive LP cell line did not express TFF3. LN cells demonstrated enhanced migration, invasion, and less apoptosis compared to LP cells. Transfecting TFF3 into LP cells enhanced their ability to migrate, invade, block apoptosis, and behave more aggressively in vivo, thereby resembling the phenotype of LN cells.

CONCLUSIONS

In rat colon cancer cells, both endogenous and constitutive expression of TFF3 correlates with an aggressive phenotype. These data provide direct evidence that TFF3 contributes to the malignant behavior of cancer cells.

Palifermin

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Serum amyloid A activates NF-kappaB and proinflammatory gene expression in human and murine intestinal epithelial cells

Serum amyloid A (SAA) is an acute-phase protein whose levels positively correlate with disease activity in inflammatory bowel diseases. In this study we investigated the impact of SAA on NF-kappaB signaling and proinflammatory gene expression in intestinal epithelial cells (IEC). Human HT-29 and Caco-2 monolayers were stimulated with recombinant SAA and NF-kappaB activation/NF-kappaB-dependent gene expression measured. Adenoviral dominant negative mutants IkappaB-alpha (Ad5IkappaBAA) were utilized to determine the contribution of NF-kappaB signaling pathway to SAA-dependent gene expression. Intestinal explant and primary IEC derived from kappaB-EGFP transgenic mice were exposed to SAA and NF-kappaB-dependent enhanced green fluorescent protein (EGFP) fluorescence measured. SAA induced IkappaB-alpha degradation, RelA serine 536 (S536) phosphorylation, NF-kappaB transcriptional activity, RelA recruitment to the IL-8 gene promoter and endogenous gene expression (IL-8, COX-2) in HT-29 cells. Further, Ad5IkappaBAA abrogated SAA-induced RelA nuclear translocation, NF-kappaB transcriptional activity and IL-8 gene expression. SAA-dependent IL-8 gene expression required activation of the MAPK ERK, p38 and JNK in HT-29 cells. Finally, SAA induced EGFP expression in intestinal explants isolated from kappaB-EGFP transgenic mice and enhanced RelA and IkappaBalpha phosphorylation in primary IEC. This indicates that SAA potentially participate in the inflammatory process by virtue of its ability to activate proinflammatory signaling in IEC.

Comparative effects of glucagon-like peptide-2 (GLP-2), growth hormone (GH), and keratinocyte growth factor (KGF) on markers of gut adaptation after massive small bowel resection in rats

BACKGROUND

Administration of specific growth factors exert gut-trophic effects in animal models of massive small bowel resection (SBR); however, little comparative data are available. Our aim was to compare effects of a human glucagon-like peptide-2 (GLP-2) analog, recombinant growth hormone (GH) and recombinant keratinocyte growth factor (KGF) on jejunal, ileal, and colonic growth and functional indices after 80% SBR in rats.

METHODS

Thirty-seven male rats underwent small bowel transection (sham operation) with s.c. saline administration (control; Tx-S; n = 7) or 80% midjejuno-ileal resection (Rx) and treatment with either s.c. saline (Rx-S, n = 7), GLP-2 at 0.2 mg/kg/d (Rx-GLP-2; n = 8), GH at 3.0 mg/kg/d (Rx-GH; n = 8), or KGF at 3.0 mg/kg/d (Rx-KGF; n = 7) for 7 days. All groups were pair-fed to intake of Rx-S rats. Gut mucosal cell growth indices (wet weight, DNA and protein content, villus height, crypt depth, and total mucosal height) were measured. Expression of the cytoprotective trefoil peptide TFF3 was determined by Western blot. Gut mucosal concentrations of the tripeptide glutathione (L-glutamyl-L-cysteinyl-glycine) and glutathione disulfide (GSSG) were measured by high-performance liquid chromatography and the glutathione/GSSG ratio calculated.

RESULTS

SBR increased adaptive growth indices in jejunal, ileal, and colonic mucosa. GLP-2 treatment increased jejunal villus height and jejunal total mucosal height compared with effects of resection alone or resection with GH or KGF treatment. Both GH and KGF modestly increased colonic crypt depth after SBR. SBR did not affect small bowel or colonic goblet cell number or TFF3 expression; however, goblet cell number and TFF3 expression in both small bowel and colon were markedly up-regulated by KGF treatment and unaffected by GLP-2 and GH. SBR oxidized the ileal and colonic mucosal glutathione/GSSG redox pools. GLP-2 treatment after SBR increased the glutathione/GSSG ratio in jejunum, whereas KGF had an intermediate effect. In addition, GLP-2 (but not GH or KGF) prevented the SBR-induced oxidation of the glutathione/GSSG pools in both ileum and colon.

CONCLUSIONS

GLP-2 exerts superior trophic effects on jejunal growth and also improves mucosal glutathione redox status throughout the bowel after massive SBR in rats. Both GH and KGF increase colonic mucosal growth in this model. KGF alone potently increases gut mucosal goblet cell number and expression of the cytoprotective trefoil peptide TFF3. The differential effects of GLP-2, GH and KGF administration in this model of short bowel syndrome suggest that individual therapy with these growth factors may not be an adequate strategy to maximally improve adaptive gut mucosal growth and cytoprotection after massive small intestinal resection. Future research should address the use of these agents in combination in short bowel syndrome.

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.

Keratinocyte growth factor/fibroblast growth factor 7, a homeostatic factor with therapeutic potential for epithelial protection and repair

Keratinocyte growth factor (KGF) is a paracrine-acting, epithelial mitogen produced by cells of mesenchymal origin. It is a member of the fibroblast growth factor (FGF) family, and acts exclusively through a subset of FGF receptor isoforms (FGFR2b) expressed predominantly by epithelial cells. The upregulation of KGF after epithelial injury suggested it had an important role in tissue repair. This hypothesis was reinforced by evidence that intestinal damage was worse and healing impaired in KGF null mice. Preclinical data from several animal models demonstrated that recombinant human KGF could enhance the regenerative capacity of epithelial tissues and protect them from a variety of toxic exposures. These beneficial effects are attributed to multiple mechanisms that collectively act to strengthen the integrity of the epithelial barrier, and include the stimulation of cell proliferation, migration, differentiation, survival, DNA repair, and induction of enzymes involved in the detoxification of reactive oxygen species. KGF is currently being evaluated in clinical trials to test its ability to ameliorate severe oral mucositis (OM) that results from cancer chemoradiotherapy. In a phase 3 trial involving patients who were treated with myeloablative chemoradiotherapy before autologous peripheral blood progenitor cell transplantation for hematologic malignancies, KGF significantly reduced both the incidence and duration of severe OM. Similar investigations are underway in patients being treated for solid tumors. On the basis of its success in ameliorating chemoradiotherapy-induced OM in humans and tissue damage in a variety of animal models, additional clinical applications of KGF are worthy of investigation.

Trefoil factor family (TFF) peptides and cancer progression

TFF peptides are involved in mucosal maintenance and repair through motogenic and antiapoptotic activities. These peptides are overexpressed during inflammatory processes and cancer progression. They also function as scatter factors, proinvasive and angiogenic agents. Such a divergence is related to the pathophysiological state of tissues submitted to persistent aggressive situations during digestive processes in the normal gastrointestinal tract, inflammatory and neoplastic diseases. In agreement with this model, TFF peptides are connected with multiple oncogenic pathways. As a consequence, the TFF signaling pathways may serve as potential targets in the control of chronic inflammation and progression of human solid tumors.

Glutamine and KGF each regulate extracellular thiol/disulfide redox and enhance proliferation in Caco-2 cells

Glutamine (Gln) and keratinocyte growth factor (KGF) each stimulate intestinal epithelial cell growth, but regulatory mechanisms are not well understood. We determined whether Gln and KGF alter intra- and extracellular thiol/disulfide redox pools in Caco-2 cells cultured in oxidizing or reducing cell medium and whether such redox variations are a determinant of proliferative responses to these agents. Cells were cultured over a physiological range of oxidizing to reducing extracellular thiol/disulfide redox (Eh) conditions, obtained by varying cysteine (Cys) and cystine (CySS) concentrations in cell medium. Cell proliferation was determined by 5-bromo-2-deoxyuridine (BrdU) incorporation. Gln (10 mmol/l) or KGF (10 microg/l) did not alter BrdU incorporation at reducing Eh (-131 to -150 mV), but significantly increased incorporation at more oxidizing Eh (Gln at 0 to -109 mV; KGF at -46 to -80 mV). Cellular glutathione/glutathione disulfide (GSH/GSSG) Eh was unaffected by Gln, KGF, or variations in extracellular Cys/CySS Eh. Control cells largely maintained extracellular Eh at initial values after 24 h (-36 to -136 mV). However, extracellular Eh shifted toward a narrow physiological range with Gln and KGF treatment (Gln -56 to -88 mV and KGF -76 to -92 mV, respectively; P < 0.05 vs. control). The results indicate that thiol/disulfide redox state in the extracellular milieu is an important determinant of Caco-2 cell proliferation induced by Gln and KGF, that this control is independent of intracellular GSH redox status, and that both Gln and KGF enhance the capability of Caco-2 cells to modulate extremes of extracellular redox.

Repifermin (keratinocyte growth factor-2) for the treatment of active ulcerative colitis: a randomized, double-blind, placebo-controlled, dose-escalation trial

BACKGROUND

Repifermin (keratinocyte growth factor-2) has been shown to reduce inflammation in animal models of colitis.

AIM

To evaluate repifermin for the treatment of active ulcerative colitis.

METHODS

Eighty-eight patients with active ulcerative colitis were enrolled in a 6-week, double-blind trial. Patients were randomized to receive treatment for five consecutive days with intravenous repifermin at a dose of 1, 5, 10, 25 or 50 microg/kg, or placebo. The primary objective of the study was to evaluate the safety of repifermin. The primary efficacy outcome was clinical remission at week 4, defined as a score of zero on the endoscopic appearance and stool blood components of the Mayo score and a score of zero or unity on the stool frequency and physician's global assessment components.

RESULTS

At week 4, the rates of clinical remission in the 1, 5, 10, 25 and 50 microg/kg repifermin groups were 19%, 9%, 0%, 0% and 0%, respectively, and 11% for the placebo group (P = 0.32 for repifermin vs. placebo). The frequencies of commonly occurring adverse events and severe adverse events were similar in both groups.

CONCLUSIONS

Intravenous repifermin at a dose of 1-50 microg/kg was very well tolerated, but there was no evidence that repifermin was effective for the treatment of active ulcerative colitis at these doses. An additional study to determine the efficacy of repifermin at doses of > 50 microg/kg or for a longer treatment duration may be warranted, as the maximally tolerated dose was not reached in the present study.

Trefoil peptide expression and goblet cell number in rat intestine: effects of KGF and fasting-refeeding

The trefoil factor family peptides TFF1, TFF2, and TFF3 are important for gut mucosal protection and restitution. Keratinocyte growth factor (KGF) stimulates proliferation and differentiation of epithelial cells with potent effects on goblet cells. To investigate interactions between food intake and KGF, rats were fed ad libitum (control), fasted for 72 h, or fasted for 72 h and then refed for 72 h with or without KGF (3 mg. kg(-1). day(-1)). With fasting, goblet cell number in duodenum increased, TFF3 mRNA in duodenum and jejunum decreased, and TFF3 protein did not change or increased. KGF during fasting stimulated colonic growth, normalized TFF3 mRNA in duodenum and jejunum, and broadly upregulated gut goblet cell number and TFF3 protein expression. With fasting-refeeding, KGF increased small bowel and colonic mucosal growth, goblet cell number, and TFF3 protein but had variable effects on TFF3 mRNA. KGF induced TFF2 mRNA and protein in duodenum and jejunum with both nutritional regimens. We conclude that nutrient availability modifies rat intestinal goblet cell number, TFF3 mRNA, and the gut-trophic effects of KGF in a region-specific manner. KGF enhances TFF2 expression in proximal small bowel and increases goblet cell number and TFF3 protein content throughout the intestine independent of food intake.

Protection of the intestinal mucosa by intraepithelial gamma delta T cells

gammadelta intraepithelial T lymphocytes (IEL) represent a major T cell population within the intestine of unclear functional relevance. The role of intestinal gammadelta IEL was evaluated in the dextran sodium sulfate (DSS) induced mouse colitis model system. Large numbers of gammadelta T cells, but not alphabeta T cells, were localized at sites of DSS-induced epithelial cell damage. gammadelta IEL in DSS treated mice expressed keratinocyte growth factor (KGF), a potent intestinal epithelial cell mitogen. gammadelta cell-deficient mice (TCRdelta(-/-)) and KGF-deficient mice (KGF(-/-)), but not alphabeta cell-deficient mice (TCRalpha(-/-)), were more prone than wild-type mice to DSS-induced mucosal injury and demonstrated delayed tissue repair after termination of DSS treatment. Termination of DSS treatment resulted in vigorous epithelial cell proliferation in wild-type mice but not in TCRdelta(-/-) mice or KGF(-/-) mice. These results suggest that gammadelta IEL help preserve the integrity of damaged epithelial surfaces by providing the localized delivery of an epithelial cell growth factor.