Transforming growth factor beta 1 selectively augments collagen synthesis by human intestinal smooth muscle cells

Oxidative imbalance and muscular alterations in diverticular disease

BACKGROUND

It is still a matter of debate if neuromuscular alterations reflect a primary event in diverticular disease (DD).

AIMS

This study aimed to assess colonic wall layers from both stenotic and non-stenotic complicated DD, bio-phenotypic alterations, inflammatory and oxidative status.

METHODS

A systematic analysis of colonic specimens obtained from stenotic and non-stenotic DD specimens was conducted and compared with controls. Biological activity and qPCR analysis were performed on longitudinal and circular muscles. Western blot analysis was performed throughout colonic wall layers to quantify oxidative and inflammatory markers.

RESULTS

A homogenous increase in oxidative stress was observed through all the layers, which were more sharpened in the longitudinal muscle for a loss in antioxidant defenses. In both stenotic and non-stenotic colon, the longitudinal muscle presented an impaired relaxation and a cellular phenotypic switch driven by transforming growth factor-β with an increase in mRNA expression of collagen Iα and a decrease in myosin heavy chain. The circular muscle, as the mucosa, was less affected by molecular alterations. No peculiar increase in inflammatory markers was observed.

CONCLUSION

A longitudinal colonic myopathy is present in DD, independently from the disease stage associated with an oxidative imbalance that could suggest new therapeutic strategies.

Expression and Possible Role of Silent Mating Type Information Regulation 2 Homolog 1 in Post-necrotizing Enterocolitis Stricture in vivo and in vitro

PURPOSE

To investigate the expression and possible role of Sirtuin1 or Silent mating-type information regulation 2 homolog-1 (SIRT1) in post-necrotizing enterocolitis stricture.

MATERIALS AND METHODS

The expression characteristics of SIRT1 and TGF-β1 in post-necrotizing enterocolitis stricture were detected by immunohistochemistry. The siRNA-SIRT1 was used to inhibit the expression of SIRT1 in intestinal epithelial cells-6 (IEC-6), and qRT-PCR, WB, and ELISA were utilized to detect the changes of Transforming growth factor-β1 (TGF-β1), nuclear factor (NF)-κB, tumor necrosis factor-α (TNF-α), tight junction protein-1 (ZO-1), and vascular endothelial growth factor (VEGF) expressions. The IEC-6 cell proliferation and migration ability were tested via CCK8 kit and Transwell test. The expression of E-cadherin and Vimentin in cells was detected by immunofluorescence.

RESULTS

The CRP, IL-6, IL-10, and IFN-γ in the serum of Necrotizing enterocolitis (NEC) intestinal stenosis patients were significantly higher than the reference values. The SIRT1 protein was under-expressed and the TGF-β1 protein was overexpressed in NEC intestinal stenosis tissue. And the expression of SIRT1 was negatively correlated with TGF-β1. At the time of diagnosis of NEC, the expression of SIRT1 decreased in children with respiratory distress syndrome and CRP level increased. After inhibiting the expression of SIRT1 in IEC6 cells, the expression levels of TGF-β1, Smad3, and NF-κB were decreased, and the expression of ZO-1 was also decreased. The proliferation and migration ability of IEC6 cells was decreased significantly, and the expression of E-cadherin and Vimentin proteins in IEC6 cells did not change significantly.

CONCLUSION

Promotion of intestinal fibrosis by inflammation may be the mechanism of post-necrotizing enterocolitis stricture. SIRT1 may be a protective protein of NEC. The probable mechanism is that SIRT1 can regulate intestinal fibrosis and can protect the intestinal mucosal barrier function to participate in the process of post-necrotizing enterocolitis stricture.

Novel mechanisms and clinical trial endpoints in intestinal fibrosis

The incidence of inflammatory bowel diseases (IBD) worldwide has resulted in a global public health challenge. Intestinal fibrosis leading to stricture formation and bowel obstruction is a frequent complication in Crohn's disease (CD), and the lack of anti-fibrotic therapies makes elucidation of fibrosis mechanisms a priority. Progress has shown that mesenchymal cells, cytokines, microbial products, and mesenteric adipocytes are jointly implicated in the pathogenesis of intestinal fibrosis. This recent information puts prevention or reversal of intestinal strictures within reach through innovative therapies validated by reliable clinical trial endpoints. Here, we review the role of immune and non-immune components of the pathogenesis of intestinal fibrosis, including new cell clusters, cytokine networks, host-microbiome interactions, creeping fat, and their translation for endpoint development in anti-fibrotic clinical trials.

HGF and TSG-6 Released by Mesenchymal Stem Cells Attenuate Colon Radiation-Induced Fibrosis

Fibrosis is a leading cause of death in occidental states. The increasing number of patients with fibrosis requires innovative approaches. Despite the proven beneficial effects of mesenchymal stem cell (MSC) therapy on fibrosis, there is little evidence of their anti-fibrotic effects in colorectal fibrosis. The ability of MSCs to reduce radiation-induced colorectal fibrosis has been studied in vivo in Sprague–Dawley rats. After local radiation exposure, rats were injected with MSCs before an initiation of fibrosis. MSCs mediated a downregulation of fibrogenesis by a control of extra cellular matrix (ECM) turnover. For a better understanding of the mechanisms, we used an in vitro model of irradiated cocultured colorectal fibrosis in the presence of human MSCs. Pro-fibrotic cells in the colon are mainly intestinal fibroblasts and smooth muscle cells. Intestinal fibroblasts and smooth muscle cells were irradiated and cocultured in the presence of unirradiated MSCs. MSCs mediated a decrease in profibrotic gene expression and proteins secretion. Silencing hepatocyte growth factor (HGF) and tumor necrosis factor-stimulated gene 6 (TSG-6) in MSCs confirmed the complementary effects of these two genes. HGF and TSG-6 limited the progression of fibrosis by reducing activation of the smooth muscle cells and myofibroblast. To settle in vivo the contribution of HGF and TSG-6 in MSC-antifibrotic effects, rats were treated with MSCs silenced for HGF or TSG-6. HGF and TSG-6 silencing in transplanted MSCs resulted in a significant increase in ECM deposition in colon. These results emphasize the potential of MSCs to influence the pathophysiology of fibrosis-related diseases, which represent a challenging area for innovative treatments.

The role of cytokine and immune responses in intestinal fibrosis

The rapidly increasing incidence of inflammatory bowel disease (IBD) in South America, eastern Europe, Asia, and Africa has resulted in a global public health challenge. Intestinal fibrosis is a common complication in patients with long-term IBD, which may develop into stenosis and subsequent obstruction. Hitherto, the origin of IBD is unclear and several factors may be involved, including genetic, immune, environmental and microbial influences. Little is known about how the recurrent inflammation in patients with IBD develops into intestinal fibrosis and currently, there is no suitable treatment to reverse intestinal fibrosis in these patients. Here, we review the role of immune components in the pathogenesis of IBD and intestinal fibrosis, including cytokine networks, host-microbiome interactions, and immune cell trafficking.

Immunological roles of intestinal mesenchymal cells

The intestine is continuously exposed to an enormous variety and quantity of antigens and innate immune stimuli derived from both pathogens and harmless materials, such as food and commensal bacteria. Accordingly, the intestinal immune system is uniquely adapted to ensure appropriate responses to the different kinds of challenge; maintaining tolerance to harmless antigens in the steady-state, whilst remaining poised to deal with potential pathogens. To accomplish this, leucocytes of the intestinal immune system have to adapt to a constantly changing environment and interact with many different non-leucocytic intestinal cell types, including epithelial and endothelial cells, neurons, and a heterogenous network of intestinal mesenchymal cells (iMC). These interactions are intricately involved in the generation of protective immunity, the elaboration of inflammatory responses, and the development of inflammatory conditions, such as inflammatory bowel diseases. Here we discuss recent insights into the immunological functions of iMC under homeostatic and inflammatory conditions, focusing particularly on iMC in the mucosa and submucosa, and highlighting how an appreciation of the immunology of iMC may help understand the pathogenesis and treatment of disease.

Very early onset IBD: novel genetic aetiologies

PURPOSE OF REVIEW

To summarize the current understanding and recent advances on the genetic aetiology in the pathogenesis of very early onset inflammatory bowel disease (VEO-IBD).

RECENT FINDINGS

IBD is a chronic disorder of the gastrointestinal tract whose manifestation is a result of complex interactions between genetics, environment, immune system and microbial flora. Over 230 IBD risk loci have been reported in genome wide association studies but the genetic contribution of the majority of these loci in the manifestation of IBD is very low. Patients with VEO-IBD present with a more severe disease than older patients, characterized by poor prognosis and failure of conventional therapy. Recent studies have reported several monogenic diseases with high penetrance that present with IBD and IBD-like intestinal manifestations and overlap with primary immunodeficiencies. Increasing body of evidence supports a prominent role of genetics in the onset of VEO-IBD. New genetic variants and diagnoses in VEO-IBD are reviewed and current challenges in therapy with potential strategy to manage the disease are discussed.

SUMMARY

Functional analysis of the genes implicated in monogenic IBD has increased the understanding of the underlying pathobiological mechanism of the disease. This knowledge can be used to personalize medicine for specific patients, improving the standard of care and quality of life.

The Role of Cytokines in the Fibrotic Responses in Crohn's Disease

Crohn’s disease is an idiopathic disorder of the gut thought to be caused by a combination of environmental and genetic factors in susceptible individuals. It is characterized by chronic transmural inflammation of the terminal ileum and colon, with typical transmural lesions. Complications, including fibrosis, mean that between 40 and 70% of patients require surgery in the first 10 years after diagnosis. Presently, there is no evidence that the current therapies which dampen inflammation modulate or reverse intestinal fibrosis. In this review, we focus on cytokines that may lead to fibrosis and stenosis and the contribution of experimental models for understanding and treatment of gut fibrosis.

Anti-MMP-9 Antibody: A Promising Therapeutic Strategy for Treatment of Inflammatory Bowel Disease Complications with Fibrosis

BACKGROUND

Despite medical treatments or surgical options, more than one-third of patients with Crohn's disease suffer from recurring fistulae. Matrix metalloprotease 9 (MMP-9), a type IV collagenase that cleaves components of the extracellular matrix leading to tissue remodeling, is upregulated in crypt abscesses and around fistulae suggesting an important role for this enzyme in fistula formation. Our aims were (1) to correlate serum levels of MMP-9 degradation products in patients with CD with the presence of fistulae and (2) to investigate the impact of selective MMP-9 inhibition in a mouse model of intestinal fibrosis.

METHODS

Serum MMP-9 degradation products were quantified in subjects affected with nonstricturing and nonpenetrating CD (n = 50), stricturing CD (n = 41), penetrating CD (n = 22), CD with perianal fistula (n = 29), and healthy controls (n = 10). Therapeutic efficacy of anti-MMP-9 monoclonal antibodies was assessed in a heterotopic xenograft model of intestinal fibrosis.

RESULTS

C3M, an MMP-9 degradation product of collagen III, demonstrated the highest serum levels in patients with penetrating CD and differentiated penetrating CD from other CD subgroups and healthy controls, P = 0.0005. Anti-MMP-9 treatments reduced collagen deposition and hydroxyproline content in day-14 intestinal grafts indicating reduced fibrosis.

CONCLUSIONS

The serologic biomarker C3M can discriminate penetrating CD from other CD subgroups and could serve as marker for the development of penetrating CD. Anti-MMP-9 antibody has therapeutic potential to prevent intestinal fibrosis in CD complications.

Decreased Fibrogenesis After Treatment with Pirfenidone in a Newly Developed Mouse Model of Intestinal Fibrosis

BACKGROUND

Fibrosis as a common problem in patients with Crohn's disease is a result of an imbalance toward excessive tissue repair. At present, there is no specific treatment option. Pirfenidone is approved for the treatment of idiopathic pulmonary fibrosis with both antifibrotic and anti-inflammatory effects. We subsequently investigated the impact of pirfenidone treatment on development of fibrosis in a new mouse model of intestinal fibrosis.

METHODS

Small bowel resections from donor mice were transplanted subcutaneously into the neck of recipients. Animals received either pirfenidone (100 mg/kg, three times daily, orally) or vehicle.

RESULTS

After administration of pirfenidone, a significantly decreased collagen layer thickness was revealed as compared to vehicle (9.7 ± 1.0 versus 13.5 ± 1.5 µm, respectively, **P < 0.001). Transforming growth factor-β and matrix metalloproteinase-9 were significantly decreased after treatment with pirfenidone as confirmed by real-time PCR (0.42 ± 0.13 versus 1.00 ± 0.21 and 0.46 ± 0.24 versus 1.00 ± 0.62 mRNA expression level relative to GAPDH, respectively, *P < 0.05). Significantly decreased transforming growth factor-β after administration of pirfenidone was confirmed by Western blotting.

CONCLUSION

In our mouse model, intestinal fibrosis can be reliably induced and is developed within 7 days. Pirfenidone partially prevented the development of fibrosis, making it a potential treatment option against Crohn's disease-associated fibrosis.

Plasma-induced signatures reveal an extracellular milieu possessing an immunoregulatory bias in treatment-naive paediatric inflammatory bowel disease

The inflammatory state associated with Crohn's disease (CD) and ulcerative colitis (UC) remains incompletely defined. To understand more clearly the extracellular milieu associated with inflammatory bowel disease (IBD), we employed a bioassay whereby plasma of treatment naive paediatric IBD patients (n = 22 CD, n = 15 UC) and unrelated healthy controls (uHC, n = 10) were used to induce transcriptional responses in a healthy leucocyte population. After culture, gene expression was measured comprehensively with microarrays and analysed. Relative to uHC, plasma of CD and UC patients induced distinct responses consisting, respectively, of 985 and 895 regulated transcripts [|log2 ratio| ≥ 0·5 (1·4-fold); false discovery rates (FDR) ≤ 0·01]. The CD:uHC and UC:uHC signatures shared a non-random, commonly regulated, intersection of 656 transcripts (χ(2)  = P < 0·001) and were highly correlative [Pearson's correlation coefficient = 0·96, 95% confidence interval (CI) = 0.96, 0.97]. Despite sharing common genetic susceptibility loci, the IBD signature correlated negatively with that driven by plasma of type 1 diabetes (T1D) patients (Pearson's correlation coefficient = -0·51). Ontological analyses revealed the presence of an immunoregulatory plasma milieu in IBD, as transcripts for cytokines/chemokines, receptors and signalling molecules consistent with immune activation were under-expressed relative to uHC and T1D plasma. Multiplex enzyme-linked immunosorbent assay (ELISA) and receptor blockade studies confirmed transforming growth factor (TGF)-β and interleukin (IL)-10 as contributors to the IBD signature. Analysis of CD patient signatures detected a subset of transcripts associated with responsiveness to 6-mercaptopurine treatment. Through plasma-induced signature analysis, we have defined a unique, partially TGF-β/IL-10-dependent immunoregulatory signature associated with IBD that may prove useful in predicting therapeutic responsiveness.

Noncanonical STAT3 activation regulates excess TGF-β1 and collagen I expression in muscle of stricturing Crohn's disease

Increased TGF-β1 and TGF-β1-dependent Collagen I production in intestinal mesenchymal cells result in fibrosis in patients with Montreal B2 fibrostenotic Crohn's disease. Numerous cytokines, including IL-6, are produced by activated mesenchymal cells themselves and activate STAT3. The aim of the current study was to determine the mechanisms by which STAT-3 activation might result in intestinal fibrosis. Cytokine levels were measured by ELISA. STAT3 and suppressor of cytokine signaling 3 protein levels were measured by immunoblot, STAT3-TGFB1 DNA-binding activity by chromatin immunoprecipitation, and TGFB1 transcriptional activity by luciferase reporter assay. TGF-β1 (TGFB1), Collagen1α1, and connective tissue growth factor (CTGF) gene expression was measured by quantitative RT-PCR. The role of STAT3 activation was determined using STAT3 inhibitor, Stattic, and by transfection of STAT3 mutants. Autocrine production of cytokines was increased in muscle cells of B2 phenotype patients from strictures and normal intestine in the same patient and compared with other Crohn's phenotypes, ulcerative colitis, and non-Crohn's patients. A unique pattern of STAT3 phosphorylation emerged: high STAT3(S727) and low STAT3(Y705) in strictures and the opposite in unaffected intestine. TGFB1 transcriptional activity was regulated by phospho-STAT3(S727) and was decreased by Stattic or dominant-negative STAT3(S727A). TGF-β1, COL1A1, and CTGF expression was inhibited by Stattic or dominant-negative STAT3(S727A). Treatment of normal muscle cells with IL-6 or expression of constitutively active STAT3(S727E) phenocopied muscle cells from strictured intestine. Neutralization of autocrine IL-6 reversed STAT3 phosphorylation and normalized expression of TGF-β1 in strictured intestinal muscle. The ability of Stattic to improve development of fibrosis was confirmed in mice with 2,4,6-trinitrobenzenesulfonic acid-induced colitis. We observed a unique phospho-STAT3(S727) response in patients with Montreal B2 Crohn's disease, particularly in response to IL-6 leading to increased TGF-β1, collagen, and CTGF production in ileal strictures.

Palmitoylethanolamide regulates development of intestinal radiation injury in a mast cell-dependent manner

BACKGROUND

Mast cells and neuroimmune interactions regulate the severity of intestinal radiation mucositis, a dose-limiting toxicity during radiation therapy of abdominal malignancies.

AIM

Because endocannabinoids (eCB) regulate intestinal inflammation, we investigated the effect of the cannabimimetic, palmitoylethanolamide (PEA), in a mast competent (+/+) and mast cell-deficient (Ws/Ws) rat model.

METHODS

Rats underwent localized, fractionated intestinal irradiation, and received daily injections with vehicle or PEA from 1 day before until 2 weeks after radiation. Intestinal injury was assessed noninvasively by luminol bioluminescence, and, at 2 weeks, by histology, morphometry, and immunohistochemical analysis, gene expression analysis, and pathway analysis.

RESULTS

Compared with +/+ rats, Ws/Ws rats sustained more intestinal structural injury (p = 0.01), mucosal damage (p = 0.02), neutrophil infiltration (p = 0.0003), and collagen deposition (p = 0.004). PEA reduced structural radiation injury (p = 0.02), intestinal wall thickness (p = 0.03), collagen deposition (p = 0.03), and intestinal inflammation (p = 0.02) in Ws/Ws rats, but not in +/+ rats. PEA inhibited mast cell-derived cellular immune response and anti-inflammatory IL-6 and IL-10 signaling and activated the prothrombin pathway in +/+ rats. In contrast, while PEA suppressed nonmast cell-derived immune responses, it increased anti-inflammatory IL-10 and IL-6 signaling and decreased activation of the prothrombin pathway in Ws/Ws rats.

CONCLUSIONS

These data demonstrate that the absence of mast cells exacerbate radiation enteropathy by mechanisms that likely involve the coagulation system, anti-inflammatory cytokine signaling, and the innate immune system; and that these mechanisms are regulated by PEA in a mast cell-dependent manner. The eCB system should be explored as target for mitigating intestinal radiation injury.

Amelioration of excess collagen IαI, fibrosis, and smooth muscle growth in TNBS-induced colitis in IGF-I(+/-) mice

BACKGROUND

Strictures occur in ≈ 30% of patients with Crohn's disease (CD) and are characterized by intestinal smooth muscle hyperplasia, hypertrophy, and fibrosis due to excess extracellular matrix production including collagen. Insulin-like growth factor-I (IGF-I) expression is increased in smooth muscle cells of the muscularis propria in CD and in animal models of CD, including trinitrobenzene sulfonic acid (TNBS)-induced colitis. While upregulated IGF-I is conjectured to cause smooth muscle cell growth and collagen production in the inflamed intestine, its role in the development of fibrosis has not been directly demonstrated.

METHODS

Colitis was induced in IGF-I(+/-) or wildtype C57BL/6J mice by rectal administration of TNBS or ethanol vehicle. After 7 days, colonic smooth muscle cells were isolated and used to prepare RNA or protein lysates. Transcript levels of IGF-IEa, IGF binding protein (IGFBP)-3, IGFBP-5, TGF-β1, and collagen IαI were measured by quantitative reverse-transcription polymerase chain reaction (RT-PCR). Corresponding protein levels were measured by Western blot or enzyme-linked immunosorbent assay (ELISA). Fibrosis was measured using digital image analysis of Masson's trichrome-stained histologic sections.

RESULTS

In IGF-I(+/-) mice, which express significantly lower levels of IGF-I than wildtype, the response to TNBS-induced colitis: upregulation of IGF-I, IGFBP-3, IGFBP-5 muscle growth, and collagen IαI expression, the resulting collagen deposition, and fibrosis are all significantly diminished compared to C57BL/6J wildtype controls. TGF-β1 expression and its increase following TNBS administration are not altered in IGF-I(+/-) mice compared to wildtype.

CONCLUSIONS

The findings indicate that IGF-I is a key regulator in intestinal smooth muscle hyperplasia and excess collagen production that leads to fibrosis and long term to stricture formation.

Endogenous IGFBP-3 regulates excess collagen expression in intestinal smooth muscle cells of Crohn's disease strictures

BACKGROUND

Stricture formation occurs in ≈30% of patients with Crohn's disease (CD) and is a significant cause of morbidity. Strictures are characterized by intestinal smooth muscle cell hyperplasia, smooth muscle cell hypertrophy, and fibrosis due to excess net extracellular matrix production, including collagen. Transforming growth factor-β1 (TGF-β1) has profibrotic effects in many tissues due to its ability to regulate collagen expression and extracellular matrix dynamics. We previously showed that both insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) and TGF-β1 are expressed by normal human intestinal smooth muscle cells, bind to, and activate TGF-βRII/I receptors in these cells.

METHODS

Smooth muscle cells isolated from the muscularis propria of patients were used to prepare RNA, protein lysates, or placed into primary culture. IGFBP-3, TGF-β1, and collagen IαI expression was measured with quantitative reverse-transcription polymerase chain reaction (RT-PCR) and protein levels by enzyme-linked immunosorbent assay (ELISA) or immunoblot.

RESULTS

Expression and production of IGFBP-3, TGF-β1, and collagen IαI were significantly increased specifically in smooth muscle cells isolated from regions of strictured intestine in CD compared to nonstrictured histologically normal resection margin. IGFBP-3 and TGF-β1 regulated collagen IαI expression and production via a TGF-βRII/I-dependent and Smad2/3-dependent mechanism. Upregulated (excess) collagen IαI expression and production in smooth muscle cells of strictures and basal collagen IαI in smooth muscle cells of normal margin were inhibited by immunoneutralization of IGFBP-3 or TGF-β1.

CONCLUSIONS

The findings indicate that upregulated endogenous IGFBP-3 and TGF-β1 expression regulates excess collagen IαI production and contributes to fibrosis and stricture formation in CD.

Endogenous IGF-I and alphaVbeta3 integrin ligands regulate increased smooth muscle hyperplasia in stricturing Crohn's disease

BACKGROUND & AIMS

Insulin-like growth factor-I (IGF-I) regulates human intestinal smooth muscle growth by stimulating proliferation and inhibiting apoptosis. IGF-I-stimulated growth is augmented when alphaVbeta3 integrin is occupied by its ligands, fibronectin and vitronectin. Increased IGF-I expression and muscle cell hyperplasia are features of stricturing Crohn's disease (CD); however, the role of IGF-I in stricture formation is unknown. The aim was to identify the functional role of endogenous IGF-I and alphaVbeta3 integrin ligands in regulating muscle cell hyperplasia in stricturing CD.

METHODS

Smooth muscle cells were isolated from muscularis propria of stricturing CD or normal margins. Quantitative polymerase chain reaction, immunoblot analysis, and enzyme-linked immunosorbent assay were used to measure fibronectin, vitronectin, alphaVbeta3 integrin, and IGF-I levels. Activation of the IGF-I receptor, Erk1/2, p70S6 kinase, and GSK-3beta was measured by immunoblot. Proliferation was quantified by Ki67 immunostaining and [(3)H]thymidine incorporation. Apoptosis was measured from caspase-3 cleavage and nucleosome accumulation.

RESULTS

IGF-I, vitronectin, and fibronectin RNA and protein levels were increased 1.8- to 3.4-fold in muscle cells from strictures over normal margins. Basal IGF-I receptor phosphorylation was increased 320% in strictured over normal muscle, and basal Erk1/2, p70S6 kinase, and GSK-3beta phosphorylation were increased 205%-292% in strictures. In muscle cells from strictures, Ki67 immunoreactivity and [(3)H]thymidine incorporation were increased and apoptosis was decreased compared with normal margins. Antagonists of the IGF-I receptor or alphaVbeta3 integrin reversed these changes.

CONCLUSIONS

Smooth muscle cell hyperplasia in stricturing CD is regulated by increased endogenous IGF-I and alphaVbeta3 integrin ligands that regulate augmented proliferation and diminished apoptosis.

Role of Klebsiella and collagens in Crohn's disease: a new prospect in the use of low-starch diet

Crohn's disease is suggested to result from a microbially triggered immune-mediated autoimmune process, involving mainly the terminal ileum and ileo-caecal junction. Klebsiella pneumoniae shares certain molecular structures present in pullulanase pulA and pulD secretion enzymes with various self-antigens present in collagens and HLA-B27 molecules, respectively. A link exists between high dietary starch intake and the growth of intestinal microflora, involving especially Klebsiella microbes. Increased exposure to Klebsiella in the gut as the result of high starch intake would lead to high production of antiKlebsiella antibodies as well as autoantibodies to the cross-reactive self-antigens with the resultant inflammation at the pathological sites. Eradication of these microbes from the gut in patients with Crohn's disease with the use of low-starch diet and antibacterial agents as well as immunomodulatory measures could be beneficial in the management of this disease.

Germinated barley foodstuff ameliorates inflammation in mice with colitis through modulation of mucosal immune system

OBJECTIVE

Germinated barley foodstuff (GBF) is a prebiotic product made from malt which contains glutamine-rich protein and hemicellulose-rich fiber. Although GBF has been observed to attenuate colonic mucosal inflammation and bowel movements in ulcerative colitis, both experimentally and clinically, the details of the immune response remain elusive. The aim of this study was to investigate the effects of GBF on the colonic epithelium immune response in a CD45RB(high) T cell chronic colitis model.

MATERIAL AND METHODS

Colitis was induced by transferring CD4+ CD45RB(high) T cells to severe combined immunodeficiency (SCID) mice (control n=8, GBF n=8) and the effects of GBF on the colitis were evaluated. The evaluation included measurement of body-weight, occult blood tests, histological examination, mucosal cytokine reverse transcription-polymerase chain reaction (RT-PCR) analysis (interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta)) as well as IL-6 measurements.

RESULTS

Seven weeks after transferring the above cells, body-weight loss and occult blood were significantly reduced in the mice that had been fed with GBF. In these mice, there were also significant reductions in IFN-gamma mRNA expressions and IL-6 in the colonic mucosa, as compared with the control group. GBF also significantly attenuated, mucosal damage and mucin positive goblet cell depletion. Conversely, TGF-beta expression significantly increased in the GBF group, compared with the control group.

CONCLUSIONS

In this preliminary study using an experimental model in which colitis was induced by transferring CD4+ CD45RB(high) T cells to SCID mice, GBF reduced inflammation by modulating the colonic microflora.

Antifibrogenic effects of tamoxifen in a rat model of periportal hepatic fibrosis

BACKGROUNDS/AIMS

It has been reported that tamoxifen may affect hepatoma cell growth in vitro by suppressing transforming growth factor beta-1 (TGF-beta1) expression, suggesting that tamoxifen might also retard fibrogenesis. Thus, we examined whether tamoxifen might suppress TGF-beta1 expression and consequently inhibit the process of hepatic fibrosis in vivo.

METHODS

To induce periportal hepatic fibrosis, 50 male adult Sprague-Dawley rats were injected with 0.62 mmol/kg of allyl alcohol, intraperitoneally, twice a week for 8 weeks. Hepatic fibrosis scores, intrahepatic collagen levels and plasma TGF-beta1 expression levels were evaluated in three groups of 10 rats orally administered tamoxifen at 1, 5 and 10 mg/kg, respectively, and in 20 controls. Messenger RNAs (mRNAs) encoding TGF-beta1 and TGF-beta receptors in liver tissue were semiquantified using reverse transcriptase polymerase chain reaction.

RESULTS

Hepatic fibrosis scores decreased progressively as the dose of tamoxifen increased, resulting in a significant change in rats treated with tamoxifen at 10 mg/kg compared with controls (P=0.018). Intrahepatic collagen content was significantly less in the group treated with tamoxifen at 10 mg/kg compared with the control (P=0.045). Plasma TGF-beta1 levels were also significantly lower in rats treated with tamoxifen at 10 mg/kg compared with controls (P=0.007). All three concentrations of tamoxifen tested decreased the expression levels of hepatic TGF-beta1 mRNA and type I TGF-beta receptor (TGF-beta RI) mRNA to similar extents.

CONCLUSIONS

Tamoxifen seems to inhibit the process of hepatic fibrosis dose-dependently by suppressing the transcription of TGF-beta1 and TGF-beta RI in an experimental model of periportal hepatic fibrosis.

Differential expression of inflammatory and fibrogenic genes and their regulation by NF-kappaB inhibition in a mouse model of chronic colitis

Fibrosis is a major complication of chronic inflammation, as seen in Crohn's disease and ulcerative colitis, two forms of inflammatory bowel diseases. To elucidate inflammatory signals that regulate fibrosis, we investigated gene expression changes underlying chronic inflammation and fibrosis in trinitrobenzene sulfonic acid-induced murine colitis. Six weekly 2,4,6-trinitrobenzene sulfonic acid enemas were given to establish colitis and temporal gene expression patterns were obtained at 6-, 8-, 10-, and 12-wk time points. The 6-wk point, TNBS-w6, was the active, chronic inflammatory stage of the model marked by macrophage, neutrophil, and CD3(+) and CD4(+) T cell infiltrates in the colon, consistent with the idea that this model is T cell immune response driven. Proinflammatory genes Cxcl1, Ccl2, Il1b, Lcn2, Pla2g2a, Saa3, S100a9, Nos2, Reg2, and Reg3g, and profibrogenic extracellular matrix genes Col1a1, Col1a2, Col3a1, and Lum (lumican), encoding a collagen-associated proteoglycan, were up-regulated at the active/chronic inflammatory stages. Rectal administration of the NF-kappaB p65 antisense oligonucleotide reduced but did not abrogate inflammation and fibrosis completely. The antisense oligonucleotide treatment reduced total NF-kappaB by 60% and down-regulated most proinflammatory genes. However, Ccl2, a proinflammatory chemokine known to promote fibrosis, was not down-regulated. Among extracellular matrix gene expressions Lum was suppressed while Col1a1 and Col3a1 were not. Thus, effective treatment of fibrosis in inflammatory bowel disease may require early and complete blockade of NF-kappaB with particular attention to specific proinflammatory and profibrogenic genes that remain active at low levels of NF-kappaB.

Longitudinal muscle shows abnormal relaxation responses to nitric oxide and contains altered levels of NOS1 and elastin in uncomplicated diverticular disease

OBJECTIVE

Recent evidence challenges the 'low-fibre/high-colonic intraluminal pressure' hypothesis of diverticular disease (DD) and raises the possibility that other mechanisms are involved. Although bowel wall smooth muscle is known to be hypercontractile in DD, the nature of its relaxation is unknown. The present study investigated colonic smooth muscle responses to nitric oxide, as well as the smooth muscle contents of neural nitric oxide and elastin associated with the disease.

METHOD

Immunohistochemical/image analysis of antibodies to nitric oxide synthase (NOS1), co-localized with protein gene product (PGP) and to elastin, was performed on three histological sections of sigmoid colons from 20 patients (10 DD, 10 controls) following resections for rectal tumours. Organ bath experiments examined smooth muscle responsiveness to nitroprusside, a nitric oxide donor.

RESULTS

Uncomplicated diverticular longitudinal muscle showed lower nitric oxide immunoreactivity compared with controls: median percentage surface area of NOS1 over PGP was 26.0% (range 0.5-58.3), controls 45.0% (35.0-70.1; P = 0.018). Median percentage surface area of elastin was elevated, 21.3% (10.6-45.6), controls 8.2% (1.7-13.5; P = 0.0002), together with a low sensitivity to nitroprusside [mean - log EC(50) 5.3 (SD 0.5), controls 6.6 (SD 0.5), difference 1.3, 95% CI 0.8-1.7; P < 0.0001] and there were lower maximum relaxation responses to nitroprusside compared with controls: median percentage (relaxation induced by nitroprussside/contraction induced by bethanecol) was 52.0%, range (20.0-92.0), controls 100.0% (71.0-125.0), P < 0.0001. No statistically significant differences were found in circular muscle, at the sample size studied.

CONCLUSION

This study established, for the first time, specific abnormalities in longitudinal muscle relaxation and contents of neural nitric oxide and elastin in uncomplicated DD. These findings may have important implications for both colon structure and function in the disease.

Triggering endogenous immunosuppressive mechanisms by combined targeting of Dipeptidyl peptidase IV (DPIV/CD26) and Aminopeptidase N (APN/ CD13)--a novel approach for the treatment of inflammatory bowel disease

The ectopeptidases Dipeptidylpeptidase IV and Alanyl-Aminopeptidase N, strongly expressed by both, activated and regulatory T cells were shown to co-operate in T cell regulation. Based on the findings that DPIV and APN inhibitors induce the TGF-beta1 and IL-10 production and a suppression of T helper cell proliferation in parallel, and that particularly APN inhibitors amplify the suppressing activity of regulatory T cells, both peptidases represent a promising target complex for treatment of diseases associated with an imbalanced T cell response, such as inflammatory bowel diseases (IBD). The aim of the present study was to analyze the therapeutic potential of DPIV and APN inhibitors in vivo in a mouse model of colitis. Balb/c mice received 3% (w/v) dextran sulphate sodium with the drinking water for 7 days. After onset of colitis symptoms, inhibitor treatment started at day 3. Disease activity index (DAI) was assessed daily, supplemented by histological and immunological analysis. While the DPIV inhibitor Lys-[Z(NO])(2)]-pyrrolidide or the APN-inhibitor Actinonin alone had marked but no significant therapeutic effects, the simultaneous administration of both inhibitors reduced colitis activity in comparison to placebo treated mice, significantly (DAI 4.8 vs. 7.7, p<0.005). A newly developed compound IP12.C6 with inhibitory capacity toward both enzymes significantly attenuated the clinical manifestation of colitis (DAI 3.2 vs. 7.6, p<0.0001). TGF-beta mRNA was found to be up-regulated in colon tissue of inhibitor-treated animals. In summary our results strongly suggest that combined DPIV and APN inhibition by synthetic inhibitors represents a novel and efficient approach for the pharmacological therapy of IBD by triggering endogenous immunosuppressive mechanisms.

TGFB1 gene polymorphisms: their relevance in the susceptibility to Helicobacter pylori-related diseases

Recent studies have revealed elevated expression of transforming growth factor beta1 (TGF-beta1) in gastric mucosa of patients with gastric cancer (GC) and those undergoing ulcer repair. As production of TGF-beta1 is genetically regulated, we aimed to assess whether functional polymorphisms of the TGFB1 gene are involved in susceptibility to and clinical characteristics of Helicobacter pylori-related diseases. DNA from 142 unrelated Spanish patients with GC, 200 with peptic ulcer and 342 healthy controls was typed for the MspA1I T+869C, and the Sau96I G+915C polymorphisms of the TGFB1 gene using polymerase chain reaction and RFLP analysis. H. pylori infection and CagA/VacA antibody status were determined by Western blot in patients and controls. H. pylori infection (odds ratio (OR): 11.44; 95% confidence interval (CI): 4.45-29.42; P<0.001) and non-steroidal anti-inflammatory drugs (OR: 5.07; 95% CI: 2.53-10.16; P<0.001) were identified as independent risks factors for duodenal ulcer (DU), whereas the TGFB1+869(*)C/C genotype was associated with reduced risk of developing the disease (OR: 0.32; 95% CI=0.15-0.68; P=0.003). Our results show that the TGFB1 T+869C gene polymorphism is involved in the susceptibility to DU and provide further evidence that host genetic factors play a key role in the pathogenesis of H. pylori-related diseases.

Mycophenolate Mofetil Impairs the Integrity of Colonic Anastomosis

BACKGROUND

The aim of this experimental study was to investigate the effect of mycophenolate mofetil (MMF) during the three phases of colonic anastomosis healing and specifically to check the effect of MMF on the expression of transforming growth factor-beta1 (TGF-beta1), one of the most important growth factors contributing to mechanical stability of colonic anastomosis.

MATERIALS AND METHODS

Sixty male Wistar rats underwent colonic resection and end-to-end anastomosis. The animals were divided into two groups, a study group given MMF 40 mg/kg, intraduodenally and a control group given vehicle. The rats were sacrificed at 3, 7, and 14 days (10 animals in each group). The anastomoses were tested by measuring bursting pressure and hydroxyproline content. Histological examination and immunohistochemical expression of TGF-beta1 also were assessed.

RESULTS

The mean bursting pressure in the study group was significantly lower on day 3 and 7, but there was no statistical significance on day 14. The mean hydroxyproline content was lower in the study group on days 3, 7, and 14. Histology showed decreased number of macrophages and fibroblasts on days 3 and 7 but no difference on day 14. The expression of TGF-beta1 was significantly reduced in the study group, with the difference being more pronounced on days 3 and 7.

CONCLUSION

MMF weakens the integrity of colonic anastomosis, and this effect is more significant during the inflammatory phase of healing. MMF has a negative effect on macrophages and TGF-beta1 expression, resulting in decreased collagen accumulation at the anastomosis.

Transforming growth factor-beta promotes pro-fibrotic behavior by serosal fibroblasts via PKC and ERK1/2 mitogen activated protein kinase cell signaling

OBJECTIVE

To assess the role of fibroblasts, transforming growth factor (TGF)-beta, and cell signal pathways in promoting fibrosis in Crohn's disease (CD).

SUMMARY BACKGROUND DATA

Intestinal strictures are a major source of morbidity in CD. Fibroblasts found at sites of stricture promote fibrogenesis. The mechanisms underlying this pro-fibrotic behavior remain elusive.

METHODS

Fibroblasts were isolated from strictured and macroscopically normal serosa in patients with CD and from normal serosa in patients with colorectal cancer. Whole cell connective tissue growth factor (CTGF) and fibronectin expression were determined by Western blot analysis. Fibroblast type I collagen expression was evaluated by real-time PCR, while fibroblast contractile activity was measured using fibroblast populated collagen lattices. Cells were stimulated with TGF-beta1 and inhibitors of the protein kinase C (PKC) and ERK 1/2 mitogen activated protein (MAP) kinase cell signaling pathways.

RESULTS

Stricture fibroblasts displayed enhanced constitutive expression of fibronectin. TGF-beta promoted fibroblast CTGF, fibronectin, and type I collagen expression and enhanced fibroblast contractile activity. Inhibition of PKC reduced basal collagen expression and contractile activity in Crohn's fibroblasts and attenuated the effect of TGF-beta on fibroblast CTGF, fibronectin, and collagen I expression as well as fibroblast contractility. ERK 1/2 inhibition had a similar effect on TGF-beta-induced CTGF and fibronectin expression.

CONCLUSIONS

TGF-beta is a critical pro-fibrotic growth factor in CD, and its effects are mediated via PKC and ERK 1/2 MAP kinase cell signaling. These pathways may represent novel therapeutic targets for patients with CD characterized by recurrent intestinal stricture formation.

Factor XIII Therapy of Anastomotic Leak, and Circulating Growth Factors

Wound healing is far more rapid in the gastrointestinal tract than in the skin. Once dehiscence of a surgical anastomosis in the gastrointestinal tract occurs, the high collagenase activity in the gastrointestinal tract may delay wound healing and promote the formation of a nonhealing fistula. Because factor XIII promotes cross-linking of fibrin during the early phase of wound healing, we investigated the effect of factor XIII concentrate on 16 anastomotic leaks and a nonhealing fistula. A 240-U dose of factor XIII concentrate (Fibrogammin P) was administrated intravenously for 5 days. Factor XIII activity and plasma levels of epidermal growth factor (EGF), transforming growth factor (TGF)-beta, and interleukin-6 were measured before treatment and 1 day and 7 days after the end of treatment. Clinical outcomes were evaluated on the basis of the findings of contrast radiography, computed tomography, and drainage volume. Improvement relevant to the therapy was observed in 15 cases (88.2%). Factor XIII activity increased to more than 70% of the normal value in 11 cases (64.7%) but remained at 40% to 70% of the normal value in 6 cases (35.3%). Plasma EGF and TGF-betalevels increased in patients with improvement but were unchanged in patients without improvement. Our findings suggest that factor XIII significantly accelerates wound healing of anastomotic leaks and nonhealing fistulas by increasing circulating growth factors after systemic administration.

Mechanisms of disease: adipocytokines and visceral adipose tissue--emerging role in intestinal and mesenteric diseases

Adipose tissue has long been regarded as a passive type of connective tissue that stores energy as triglycerides and releases energy as free fatty acids, however, this point of view has now changed. The wide variety of products expressed and secreted by adipose tissue, such as adiponectin, leptin, and resistin, mean that the total adipose tissue mass can be defined as a real endocrine organ. The anatomic, metabolic and biochemical characteristics of visceral adipose tissue make it interesting in the context of intestinal and mesenteric diseases. These characteristics include increased lipolysis, venous drainage via the portal vein and local glucocorticoid excess owing to the specific expression of 11-beta-hydroxysteroid-dehydrogenase type 1. In this review, the role of the visceral adipose tissue and its secretory products in intestinal and mesenteric diseases is systematically reviewed, with special focus on 'creeping fat' in Crohn's disease and mesenteric panniculitis.

Selective inhibition of phosphodiesterase-4 ameliorates chronic colitis and prevents intestinal fibrosis

The phosphodiesterase-4 (PDE4) inhibitors may be an important target in the treatment of several inflammatory conditions. The anti-inflammatory effect of PDE4 inhibitors bears similarities with that of steroids, without interfering with the hypophysary-adrenal-axis. We compared the effect of rolipram, a selective PDE4 inhibitor, with steroids on the clinical course of experimental colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS). Three groups of rats (n = 20) received TNBS. One group received methylprednisolone from day 7, another group received rolipram from the same day, and control group received no further treatment. On days 14 and 21 after TNBS instillation, sets of 10 rats underwent colonic dialysis to measure eicosanoid release. Colonic lesions were blindly scored, and colons were homogenized for quantification of myeloperoxidase (MPO) activity and collagen content. Concentration of tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta1 (TGF-beta1) in colonic tissue was also measured. Both treatments reduced significantly the eicosanoid release and MPO activity. On day 14, both rolipram and methylprednisolone significantly reduced TNF-alpha content, but TGF-beta1 was only inhibited by rolipram. On day 21, lesion scores and collagen content were significantly reduced only in rolipram-treated group. In conclusion, PDE4 inhibition by rolipram markedly ameliorates the course of chronic colitis and it is superior to methylprednisolone in preventing late collagen deposition.

Intestinal macrophages: unique effector cells of the innate immune system

The gastrointestinal mucosa is the largest reservoir of macrophages in the body. These important effector cells are derived from blood monocytes that are recruited to the lamina propria by endogenous chemoattractants in the non-inflamed mucosa and by inflammatory chemokines and bacterial products during inflammation. In the non-inflamed mucosa, newly recruited pro-inflammatory monocytes are exposed to lamina propria stromal (extracellular matrix) factors that induce phenotypic and functional differentiation into non-inflammatory macrophages. As a consequence of this differentiation, resident lamina propria macrophages are strikingly downregulated for the expression of innate response receptors, such as the receptors for lipopolysaccharide, immunoglobulin G (IgG), and IgA, and the production of pro-inflammatory cytokines, including interleukin-1 (IL-1), IL-6, IL-8, and tumor necrosis factor-alpha. Despite downregulated pro-inflammatory function, strong phagocytic and bactericidal activities remain intact. Thus, in the non-inflamed intestinal mucosa, lamina propria macrophages are non-inflammatory but retain avid scavenger and host defense functions, a unique but ideal phenotype and functional profile for effector cells in close proximity to immunostimulatory microorganisms and products.

Interleukin-4- and -13-induced hypercontractility of human intestinal muscle cells-implication for motility changes in Crohn's disease

Crohn's disease is an idiopathic inflammatory condition. However, little is known about the changes that occur in the muscularis externa, despite the fact that this tissue contributes to motility changes and stricture formation. We characterized immune activity in the muscularis externa from intestinal segments of Crohn's disease patients and evaluated the role of IL-4 and -13 as well as signal transducer and activator of transcription (STAT)6 in the contractility of the cultured human intestinal smooth muscle cells. CD3+ve cells (P < 0.01) and IL-4 protein (P < 0.01) were significantly increased in the muscularis externa of Crohn's disease patients compared with noninflamed controls. Preincubation of human cultured smooth muscle cells with IL-4 (P < 0.001) or IL-13 (P < 0.05) significantly enhanced carbachol-induced contraction, and this was significantly inhibited by the STAT6 inhibitor leflunomide (P < 0.0001). A similar profile was observed in muscle cells isolated from Crohn's disease patients. Both IL-4 and IL-13 increased specific STAT6-DNA binding in control cells, and this was inhibited by anti-STAT6 Ab (P < 0.05) or leflunomide (P < 0.05). IL-4 and IL-13 mediate the hypercontractility of intestinal muscle via a STAT6 pathway at the level of the smooth muscle cell. The STAT6 pathway may contribute to the hypercontractility of intestinal muscle in Crohn's disease.

Human intestinal macrophages display profound inflammatory anergy despite avid phagocytic and bacteriocidal activity

Intestinal macrophages, which are thought to orchestrate mucosal inflammatory responses, have received little investigative attention compared with macrophages from other tissues. Here we show that human intestinal macrophages do not express innate response receptors, including the receptors for LPS (CD14), Fcalpha (CD89), Fcgamma (CD64, CD32, CD16), CR3 (CD11b/CD18), and CR4 (CD11c/CD18); the growth factor receptors IL-2 (CD25) and IL-3 (CD123); and the integrin LFA-1 (CD11a/CD18). Moreover, resident intestinal macrophages also do not produce proinflammatory cytokines, including IL-1, IL-6, IL-10, IL-12, RANTES, TGF-beta, and TNF-alpha, in response to an array of inflammatory stimuli but retain avid phagocytic and bacteriocidal activity. Thus, intestinal macrophages are markedly distinct in phenotype and function from blood monocytes, although intestinal macrophages are derived from blood monocytes. To explain this paradox, we show that intestinal stromal cell-derived products downregulate both monocyte receptor expression and, via TGF-beta, cytokine production but not phagocytic or bacteriocidal activity, eliciting the phenotype and functional profile of intestinal macrophages. These findings indicate a mechanism in which blood monocytes recruited to the intestinal mucosa retain avid scavenger and host defense functions but acquire profound "inflammatory anergy," thereby promoting the absence of inflammation characteristic of normal intestinal mucosa despite the close proximity of immunostimulatory bacteria.

Human intestinal macrophages display profound inflammatory anergy despite avid phagocytic and bacteriocidal activity

Intestinal macrophages, which are thought to orchestrate mucosal inflammatory responses, have received little investigative attention compared with macrophages from other tissues. Here we show that human intestinal macrophages do not express innate response receptors, including the receptors for LPS (CD14), Fcalpha (CD89), Fcgamma (CD64, CD32, CD16), CR3 (CD11b/CD18), and CR4 (CD11c/CD18); the growth factor receptors IL-2 (CD25) and IL-3 (CD123); and the integrin LFA-1 (CD11a/CD18). Moreover, resident intestinal macrophages also do not produce proinflammatory cytokines, including IL-1, IL-6, IL-10, IL-12, RANTES, TGF-beta, and TNF-alpha, in response to an array of inflammatory stimuli but retain avid phagocytic and bacteriocidal activity. Thus, intestinal macrophages are markedly distinct in phenotype and function from blood monocytes, although intestinal macrophages are derived from blood monocytes. To explain this paradox, we show that intestinal stromal cell-derived products downregulate both monocyte receptor expression and, via TGF-beta, cytokine production but not phagocytic or bacteriocidal activity, eliciting the phenotype and functional profile of intestinal macrophages. These findings indicate a mechanism in which blood monocytes recruited to the intestinal mucosa retain avid scavenger and host defense functions but acquire profound "inflammatory anergy," thereby promoting the absence of inflammation characteristic of normal intestinal mucosa despite the close proximity of immunostimulatory bacteria.

IGF-I increases IGFBP-5 and collagen alpha1(I) mRNAs by the MAPK pathway in rat intestinal smooth muscle cells

IGF-I is a potent fibrogenic growth factor that stimulates proliferation of intestinal smooth muscle cells and increases synthesis of collagen and IGF-I-binding proteins by the cells. These processes contribute to intestinal fibrosis that develops in patients with Crohn's disease and in Lewis-strain rats with experimental Crohn's disease. The aim of this study was to determine which early docking proteins are associated with IGF-I receptor signal transduction and which transduction pathway is involved in IGF-I-mediated gene regulation in intestinal smooth muscle cells. Primary cultures of smooth muscle cells isolated from the muscularis externa of the distal colon of Lewis rats were treated with IGF-I (100 ng/ml). Immunoprecipitation studies demonstrated that IGF-I stimulation resulted in tyrosine phosphorylation of IRS-1, IRS-2, and Shc. Coimmunoprecipitation demonstrated a close association between the IGF-I receptor and these three early docking proteins. Concurrent treatment with the MAPK inhibitor PD98059 (10 microM) resulted in an inhibition of the IGF-I-mediated increase in IGFBP-5 and collagen alpha(1)(I) mRNAs, while concurrent treatment with the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin (100 nM) had no effect. In additional experiments, cells were transiently transfected with adenoviral vectors dominantly expressing inactive mutant Akt or constitutively expressing wild-type Akt. In both cases, the IGF-I-mediated increase in collagen I protein did not differ from that observed in control cultures that had been transfected with an adenoviral vector carrying the LacZ reporter gene. These results suggest that the MAPK pathway is key to IGF-I-mediated gene regulation in intestinal smooth muscle cells, whereas data do not suggest a role for the Akt-dependent pathway in our system.

Neoadjuvant antiangiogenic therapy with tamoxifen does not impair gastrointestinal anastomotic repair in the rat

INTRODUCTION

Antiangiogenic therapy has the potential to moderate tumour and micrometastatic growth. Its use in the perioperative period is attractive but its potential to compromise wound and anastomotic healing is a cause for concern. Tamoxifen is antiangiogenic but also favourably modifies some aspects of wound healing. We hypothesised that tamoxifen would not adversely affect skin wound and gut anastomotic healing.

METHODS

A previously established model of tamoxifen, administered orally at antiangiogenic doses (20 mg/ml arachais oil/day), was used. Animals received two days pretreatment prior to laparotomy and small bowel anastomosis. Treatment was continued until completion of the study. The principal outcome measures are survival, macroscopic wound and anastomotic healing, anastomotic bursting pressure and PVA sponge granuloma hydroxyproline (OHP) content.

RESULTS

Tamoxifen treated animals had fewer complications of skin wound healing than controls (4.5% vs. 19.5%; chi(2) 4.65, 1 d.f., P < 0.05). There was no significant difference in adhesion formation or macroscopic complications of anastomotic healing. Anastomotic bursting pressure was greater in tamoxifen treated animals at postoperative day 3 (39 +/- 4.4 vs. 22.5 +/- 3.5 mmHg; P < 0.01) and equal to that of controls on postoperative day 5 (144.4 +/- 9.4 vs. 127.3 +/- 10.9 mmHg; P = ns). Tamoxifen treated animals weighed significantly less than placebo controls from postoperative day 3 with no difference in mortality between groups (chi(2) = 0.06, 1 d.f., P = ns). PVA sponge granuloma OHP content on day 7 was higher in tamoxifen-treated animals (2.93 +/- 0.4 vs. 1.4 +/- 0.4 mg OHP/mg dry sponge weight; P = 0.03).

CONCLUSION

Antiangiogenic therapy with tamoxifen has no demonstrable adverse effects on wound or anastomotic repair and its perioperative use is compatible with successful early surgical outcomes.

Transforming growth factor-beta mediates intestinal healing and susceptibility to injury in vitro and in vivo through epithelial cells

In vitro studies suggest that transforming growth factor (TGF)-beta has potent effects on gastrointestinal mucosal integrity, wound repair, and neoplasia. However, the multiplicity of actions of this peptide on many different cell types confounds efforts to define the role of TGF-beta within the intestinal epithelium in vivo. To delineate these effects selective blockade of intestinal epithelial TGF-beta activity was undertaken through targeted expression of a dominant-negative (DN) TGF-beta RII to intestinal epithelial cells in vitro and in vivo. Stable intestinal epithelial cell (IEC)-6 lines overexpressing TGF-beta RII-DN (nucleotides -7 to 573) were established. Transgenic mice overexpressing TGF-beta RII-DN under the regulation of a modified liver fatty acid-binding promoter (LFABP-PTS4) were constructed. In vitro healing was assessed by wounding of confluent monolayers. Colitis was induced by the addition of dextran sodium sulfate (2.5 to 7.5% w/v) to their drinking water. Overexpression of TGF-beta RII-DN in intestinal epithelial cell-6 cells resulted in a marked reduction in cell migration and TGF-beta-stimulated wound healing in vitro. TGF-beta RII-DN transgenic mice did not exhibit baseline intestinal inflammation or changes in survival, body weight, epithelial cell proliferation, aberrant crypt foci, or tumor formation. TGF-beta RII-DN mice were markedly more susceptible to dextran sodium sulfate-induced colitis and exhibited impaired recovery after colonic injury. TGF-beta is required for intestinal mucosal healing and TGF-beta modulation of the intestinal epithelium plays a central role in determining susceptibility to injury.

IGF-I and TGF-beta1 have distinct effects on phenotype and proliferation of intestinal fibroblasts

Insulin-like growth factor I (IGF-I) and transforming growth factor-beta1 (TGF-beta1) are upregulated in myofibroblasts at sites of fibrosis in experimental enterocolitis and in Crohn's disease (CD). We compared the sites of expression of IGF-I and TGF-beta1 in a rat peptidoglycan-polysaccharide (PG-PS) model of chronic granulomatous enterocolitis and fibrosis. We used the human colonic CCD-18Co fibroblast/myofibroblast cell line to test the hypothesis that TGF-beta1 and IGF-I interact to regulate proliferation, collagen synthesis, and activated phenotype typified by expression of alpha-smooth muscle actin and organization into stress fibers. IGF-I potently stimulated while TGF-beta1 inhibited basal DNA synthesis. TGF-beta1 and IGF-I each had similar but not additive effects to induce type I collagen. TGF-beta1 but not IGF-I potently stimulated expression of alpha-smooth muscle actin and stress fiber formation. IGF-I in combination with TGF-beta1 attenuated stress fiber formation without reducing alpha-smooth muscle actin expression. Stress fibers were not a prerequisite for increased collagen synthesis. TGF-beta1 upregulated IGF-I mRNA, which led us to examine the effects of IGF-I in cells previously activated by TGF-beta1 pretreatment. IGF-I potently stimulated proliferation of TGF-beta1-activated myofibroblasts without reversing activated fibrogenic phenotype. We conclude that TGF-beta1 and IGF-I both stimulate type I collagen synthesis but have differential effects on activated phenotype and proliferation. We propose that during intestinal inflammation, regulation of activated phenotype and proliferation may require sequential actions of TGF-beta1 and IGF-I, but they may act in concert to increase collagen deposition.

The radiotherapeutic injury--a complex 'wound'

Radiotherapeutic normal tissue injury can be viewed as two simultaneously ongoing and interacting processes. The first has many features in common with the healing of traumatic wounds. The second is a set of transient or permanent alterations of cellular and extracellular components within the irradiated volume. In contrast to physical trauma, fractionated radiation therapy produces a series of repeated insults to tissues that undergo significant changes during the course of radiotherapy. Normal tissue responses are also influenced by rate of dose accumulation and other factors that relate to the radiation therapy schedule. This article reviews the principles of organised normal tissue responses during and after radiation therapy, the effect of radiation therapy on these responses, as well as some of the mechanisms underlying the development of recognisable injury. Important clinical implications relevant to these processes are also discussed.

Quantitative analysis of transforming growth factor beta 1 mRNA in patients with alcoholic liver disease

AIM: To investigate the expression of the transforming growth factor beta 1 (TGF- beta 1) mRNA in different stages of alcoholic liver disease (ALD) and its clinical value.

METHODS: One hundred and seven male alcoholics were grouped by clinical findings into four groups: Alcohol abusers without liver impairment (n = 22), alcoholic steatosis (n = 30); alcoholic hepatitis (n = 31); and alcoholic cirrhosis (n = 24). Using peripheral blood mononuclear cells (PBMC) as samples the gene expression of TGF-beta 1 was examined quantitatively by reverse transcription polymerase chain reaction (RT-PCR) and dot blot. There are 34 healthy subjects served as control.

RESULTS: The expression of TGF-beta 1 from all ALD patients was significantly greater than that in controls (1.320 ± 1.162 vs 0.808 ± 0.276, P < 0.001). The differences of the expressions were significant between the patients from each groups (alcoholic steatosis, alcoholic hepatitis and alcoholic cirrhosis) and the controls (1.168 ± 0.852, 1.462 ± 1.657, 1.329 ± 0.610 vs 0.808 ± 0.276, P < 0.050). No significant differences of TGF-beta 1 mRNA expression were observed between alcohol abusers without liver impairment and controls. The expressions in patients with alcoholic hepatitis and alcoholic cirrhosis were significantly greater than that in alcohol abusers respectively (1.462 ± 1.657, 1.329 ± 0.610 vs 0.841 ± 0.706, P < 0.050). No significant differences of TGF-beta 1 mRNA expression were observed between alcoholic fatty liver men and alcohol abusers.

CONCLUSION: TGF-beta 1 expression level can be a risk factor for alcoholic liver disease and might be related to the inflammatory activity and fibrosis of the liver in patients.

Platelet-derived growth factor and its receptors are expressed in areas of both active inflammation and active fibrosis in inflammatory bowel disease

The aim of the present study is to clarify in situ expression of platelet-derived growth factor (PDGF) and its receptors in different phases of inflammatory bowel disease (IBD). Tissues samples were obtained from 20 patients with ulcerative colitis (UC) and 29 with Crohn's disease (CD) at surgery. In situ hybridization and immunohistochemistry on frozen sections were performed for PDGF-A and -B and its alpha and beta receptors (alphaR and betaR). The area of active inflammation was infiltrated by abundant polymorphonuclear and mononuclear leukocytes, of which the latter expressed mRNA and proteins of PDGF-A, -B, and -alphaR and mRNA for PDGF-betaR. The area of active fibrosis, characterized by activated fibroblasts/ myofibroblasts, was juxtaposed to ulceration, which is induced as a repair process to tissue destruction. In these areas, activated fibroblasts/myofibroblasts were positive for mRNA and protein of PDGF-A, -B, -alphaR, and -betaR. The expression of PDGF-A, -B, and -alphaR declined significantly in the scar area. Our results suggest that PDGF is not only important as an inducer of fibrosis in the repair phase but also it is involved in the active inflammatory phase possibly as a chemoattractant for mononuclear inflammatory cells.

Loss of transforming growth factor beta signalling in the intestine contributes to tissue injury in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract caused by an abnormal and uncontrolled immune response to one or more normally occurring gut constituents.

AIM

Given the effects of transforming growth factor beta1 (TGF-beta1) on both the immune system and extracellular matrix, we postulated that alterations in TGF-beta signalling in intestinal epithelial cells may play an important role in the development of IBD.

METHODS

TGF-beta signalling was inactivated in mouse intestine by expressing a dominant negative mutant form of the TGF-beta type II receptor under the control of the mouse intestinal trefoil peptide (ITF)/TFF3 promoter. Transgenic mice (ITF-dnRII) developed spontaneous colitis presenting with diarrhoea, haematochezia, and anal prolapse when not maintained under specific pathogen free (SPF) conditions. Under SPF conditions we induced colitis by mixing dextran sodium sulphate (DSS) in drinking water to examine the significance of loss of TGF-beta signalling in the pathogenesis of IBD.

RESULTS

Transgenic mice showed increased susceptibility to DSS induced IBD, and elicited increased expression of major histocompatibility complex class II, generation of autoantibodies against intestinal goblet cells, and increased activity of matrix metalloproteinase in intestinal epithelial cells compared with wild-type littermates challenged with DSS.

CONCLUSIONS

Deficiency of TGF-beta signalling specifically in the intestine contributes to the development of IBD. Maintenance of TGF-beta signalling may be important in regulating immune homeostasis in the intestine

Expression of insulin-like growth factor binding proteins and collagen in experimental colitis in rats

OBJECTIVES AND DESIGN

Crohn's disease is complicated by smooth muscle hyperplasia and stricture formation. Insulin-like growth factor (IGF)-1 and insulin-like growth factor binding proteins (IGFBPs) may be involved in stimulating intestinal smooth muscle growth and collagen synthesis. Therefore, we investigated the expression of IGFBPs, collagen and collagenase activity in rat colitis and the effects of IGF-1 on IGFBP and collagen expression in rat colonic smooth muscle cells.

METHODS

Animals were sacrificed during a 4-week time course of 2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced colitis. RNA from the animals' colons was blotted and hybridized with collagen-1 and IGFBP mRNA probes. Tissue proteins were screened for IGFBPs by Western ligand blotting. Collagenase activity was measured by zymography. Rat colonic smooth muscle cells in primary culture were incubated with IGF-1 then collagen-1, and IGFBP mRNAs and proteins were measured.

RESULTS

In the rat tissue, IGFBP-3 mRNA and protein were increased 2 h after induction of colitis. IGFBP-4 mRNA was elevated after 2 h and IGFBP-4 protein after 4 h. IGFBP-5 mRNA was upregulated after 2 h with a peak at 12 h. IGFBP-5 protein was upregulated after 1 h and reached a peak at 3 days. Collagen-1 mRNA was increased after 5 days. Collagenase levels were decreased after 1 h and returned to normal by 28 days. In rat colonic smooth muscle cells, IGF-1 increased collagen-1 and IGFBP-5 expression.

CONCLUSION

We demonstrated an upregulation of IGFBP and collagen expression and a downregulation of collagenase in rat colitis. In colonic smooth muscle cells, we found an upregulation of collagen-1 and IGFBP-5 following IGF-1 incubation. These results suggest an important role of IGF-1 in the collagen synthesis in colitis, mediated by IGFBPs.

Peptide growth factors in the intestine

A continuously increasing number of regulatory peptides has been demonstrated to be expressed in the intestine and to modulate several functional properties of various intestinal cell populations, including the intestinal epithelium and lamina propria cell populations. These regulatory peptides include members of the epidermal growth factor (EGF) family, the transforming growth factor beta (TGF-beta) family, the insulin-like growth factor (IGF) family, the fibroblast growth factor (FGF) family, the trefoil factor (TFF) family, the colony-stimulating factor (CSF) family, and a few other seemingly unrelated regulatory peptides, such as hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), and various interleukins, interferons and tumour necrosis factor-related proteins. In addition to the well-known effects on cell proliferation, these regulatory peptide factors regulate several other functional properties of epithelial and other cell populations, such as differentiation, migration, and extracellular matrix deposition and degradation. This review is designed not to discuss all the identified factors in detail but to highlight some of the basic principles of growth factor action in the intestine. It focuses mainly on classical growth factors rather than interleukins and interferons.

Heparan mimetic regulates collagen expression and TGF-beta1 distribution in gamma-irradiated human intestinal smooth muscle cells

Radiation-induced intestinal fibrosis is characterized by collagen accumulation, a process in which TGF-beta1 plays a key role. We analyzed the effects of gamma radiation on collagen expression and TGF-beta1 distribution in human intestinal smooth muscle cells (HISM). We investigated the activity of a carboxymethylated and sulfated dextran (RG-1503), exhibiting antifibrotic properties and promoting in vivo intestinal tissue repair, on irradiated HISM. After (60)Co irradiation (10 Gy), HISM were labeled with [(3)H] proline (+/-RG-1503). Radiolabeled collagen I, III, and V were quantified by SDS-PAGE. TGF-beta1 was quantified by ELISA in culture medium, pericellular and intracellular compartments. Irradiation induced a specific 2.85-fold increase in collagen III production by HISM. Collagen V decreased by 80% 72 h after irradiation. Pericellular TGF-beta1 was increased (up to twofold) in irradiated HISM. RG-1503 added before or after irradiation reversed both mRNA and protein levels of collagen III and V to control values. RG-1503 decreased the amount of TGF-beta1 in the cell layer below the control values. Irradiation of HISM induced the development of a fibrotic phenotype in terms of collagen production and TGF-beta1 distribution. The antifibrotic RG-1503 restored HISM physiological characteristics and may represent a promising therapeutic approach for radiation-induced intestinal fibrosis.