Attenuation of dextran sodium sulphate induced colitis in matrix metalloproteinase-9 deficient mice

Claudin-2 regulates colorectal inflammation via myosin light chain kinase-dependent signaling

BACKGROUND

Claudins have been demonstrated to be associated with inflammatory bowel disease (IBD), but the specific role of claudin-2 in colorectal inflammation remains undefined.

AIMS

We aimed to determine the role of claudin-2 in TNFα-induced colorectal inflammation.

METHODS

We used claudin-2 (-/-) mice to assess the role of claudin-2 in colon. The mice were intraperitoneally injected with 3 μg of recombinant murine TNFα, and the NF-κB signaling and mRNA expression levels of proinflammatory cytokines and myosin light chain kinase (MLCK) were evaluated. Moreover, in claudin-2 (-/-) mice, colitis was induced by the administration of dextran sodium sulfate (DSS). The involvement of claudin-2 in colorectal inflammation was also investigated using the Caco-2 human colon adenocarcinoma cell line, and the expression of claudin-2 was downregulated using claudin-2 siRNA.

RESULTS

TNFα-induced colorectal inflammation via NF-κB signaling activation was enhanced in claudin-2 (-/-) mice compared with that in claudin-2 (+/+) mice. MLCK expression level in the colon tissue of claudin-2 (-/-) mice treated with TNFα was enhanced in comparison to that of the claudin-2 (+/+) mice. DSS-induced colitis was more severe in the claudin-2 (-/-) mice than in the claudin-2 (+/-) mice. In in vitro experiments, the decreased expression of claudin-2 enhanced the expressions of IL-6, IL-1β and MLCK.

CONCLUSIONS

Our findings concerning the role of claudin-2 in epithelial inflammatory responses enrich our collective understanding of mucosal homeostasis and intestinal diseases such as IBD. Furthermore, the results of this study indicate that claudin-2 and MLCK are potential therapeutic targets for treatments against intestinal disease.

Proinflammatory cytokines induce crosstalk between colonic epithelial cells and subepithelial myofibroblasts: implication in intestinal fibrosis

BACKGROUND AND AIMS

Colonic epithelial cells and adjacent subepithelial myofibroblasts are important counterparts in the pathogenesis of intestinal inflammation and fibrosis. We investigated the possible crosstalk between them, whilst focusing on the mucosal inflammation pathways that potentially trigger intestinal fibrosis.

METHODS

We studied the effects of proinflammatory cytokines (IL-1α, TNF-α, IFN-γ) on human colonic epithelial cell lines and the effects of epithelial cell-conditioned media on primary human colonic subepithelial myofibroblasts isolated from normal controls or patients with inflammatory Crohn's disease along with the corresponding 18CO cell line. Readouts included production of TGF-β and TIMP-1, total collagen synthesis, matrix metalloproteinases MMP-2 and MMP-9 and myofibroblast migration/mobility.

RESULTS

Proinflammatory cytokines upregulated TGF-β and TIMP-1 in colonic epithelial cells. Conditioned medium from these epithelial cell cultures induced production of MMP-9 and collagen and inhibited the migration/mobility of subepithelial myofibroblasts. MMP-9 production depended on endothelin receptor A signalling on responding myofibroblasts. Collagen up-regulation was independent of TGF-β, CTGF, TF and endothelin. Subepithelial myofibroblasts isolated from Crohn's disease patients had similar responses to those isolated from normal controls, with the exception of higher basal collagen production.

CONCLUSIONS

Our study indicates that colonic epithelial cells may respond to an inflammatory milieu by inducing myofibroblast functions similar to those observed during intestinal fibrosis.

Hyperhomocysteinemia decreases intestinal motility leading to constipation

Elevated levels of plasma homocysteine (Hcy) called hyperhomocysteinemia (HHcy) have been implicated in inflammation and remodeling in intestinal vasculature, and HHcy is also known to aggravate the pathogenesis of inflammatory bowel disease (IBD). Interestingly, colon is the pivotal site that regulates Hcy levels in the plasma. We hypothesize that HHcy decreases intestinal motility through matrix metalloproteinase-9 (MMP-9)-induced intestinal remodeling leading to constipation. To verify this hypothesis, we used C57BL/6J or wild-type (WT), cystathionine β-synthase (CBS(+/-)), MMP-9(-/-), and MMP-9(-/-) + Hcy mice. Intestinal motility was assessed by barium meal studies and daily feces output. Plasma Hcy levels were measured by HPLC. Expression of ICAM-1, inducible nitric oxide synthase, MMP-9, and tissue inhibitors of MMPs was studied by Western blot and immunohistochemistry. Reactive oxygen species (ROS) including super oxide were measured by the Invitrogen molecular probe method. Tissue nitric oxide levels were assessed by a commercially available kit. Plasma Hcy levels in the treated MMP-9 group mice were comparable to CBS(+/-) mice. Barium meal studies suggest that intestinal motility is significantly decreased in CBS(+/-) mice compared with other groups. Fecal output-to-body weight ratio was significantly reduced in CBS(+/-) mice compared with other groups. There was significant upregulation of MMP-9, iNOS, and ICAM-1 expression in the colon from CBS(+/-) mice compared with WT mice. Levels of ROS, superoxide, and inducible nitric oxide were elevated in the CBS(+/-) mice compared with other groups. Results suggest that HHcy decreases intestinal motility due to MMP-9-induced intestinal remodeling leading to constipation.

Matrix metalloproteinase 9 contributes to gut microbe homeostasis in a model of infectious colitis

BACKGROUND

Inflammatory bowel diseases are associated with increased expression of zinc-dependent Matrix Metalloproteinase 9 (MMP-9). A stark dysregulation of intestinal mucosal homeostasis has been observed in patients with chronic inflammatory bowel diseases. We therefore sought to determine the contribution of MMP-9 to the pathogenesis of Citrobacter rodentium-induced colitis and its effects on gut microbiome homeostasis.

RESULTS

Wild-type and MMP-9-/- mice aged 5-6 weeks were challenged with C. rodentium by orogastric gavage and sacrificed either 10 or 30 days post-infection. Disease severity was assessed by histological analysis of colonic epithelial hyperplasia and by using an in vivo intestinal permeability assay. Changes in the inflammatory responses were measured by using qPCR, and the composition of the fecal microbiome evaluated with both qPCR and terminal restriction fragment length polymorphism. Activation and localization of MMP-9 to the apical surface of the colonic epithelium in response to C. rodentium infection was demonstrated by both zymography and immunocytochemistry. The pro-inflammatory response to infection, including colonic epithelial cell hyperplasia and barrier dysfunction, was similar, irrespective of genotype. Nonmetric multidimensional scaling of terminal restriction fragments revealed a different fecal microbiome composition and C. rodentium colonization pattern between genotypes, with MMP-9-/- having elevated levels of protective segmented filamentous bacteria and interleukin-17, and lower levels of C. rodentium. MMP-9-/- but not wild-type mice were also protected from reductions in fecal microbial diversity in response to the bacterial enteric infection.

CONCLUSIONS

These results demonstrate that MMP-9 expression in the colon causes alterations in the fecal microbiome and has an impact on the pathogenesis of bacterial-induced colitis in mice.

Correlation of MMP-3 and MMP-9 with Crohn's disease activity in children

BACKGROUND

Recently published data indicate that the inflammation in Crohn's disease (CD) may be accompanied by elevated levels of matrix metalloproteinases.

AIMS

The goals of the present study were the estimation of MMP-3 and -9 concentrations in sera of children with Crohn's disease, the examination of correlation between the concentrations of MMP-3 and -9 and clinical activity of the disease in the relation to the control group and the evaluation of the utility of MMP-3 and -9 concentration measurements as markers of disease activity.

METHODS

Serum concentrations of MMP-3 and -9 were estimated in 82 children (45 CD patients divided into severe, moderate and mild subgroups; 37 controls) and correlated with disease activity estimated by the Pediatric Crohn's Disease Activity Index (PCDAI), CRP, seromucoid and ESR.

RESULTS

Mean MMP-3 concentrations were: 2.49 ng/ml (95% CI: 1.76-3.52) for mild, 16.44 ng/ml (95% CI: 10.34-26.15) for moderate, 5.25 ng/ml (95% CI: 2.73-10.11) for severe CD and 1.95 ng/ml (95% CI: 1.53-2.48) for the control group (differences between all three groups were statistically significant; P < 0.001). Median MMP-9 concentrations were: 2.14 ng/ml (95% CI: 0-8.9) for mild, 14.21 ng/ml (95% CI: 4.53-21.48) for moderate, 42.2 ng/ml (95% CI: 5.74-61.27) for severe CD and 1.3 ng/ml (95% CI: 0.7-2.18) for the control group. MMP-9 concentrations in moderate and severe CD differed from the concentrations in mild CD (P = 0.002) and control group (P = 0.0001). MMP-3 concentration significantly correlated with MMP-9, PCDAI and ESR, while MMP-9 concentration significantly positively correlated with MMP-3, PCDAI, and CRP. Diagnostic utilities of the tests were: MMP-3 accuracy 75%, positive likelihood ratio (LR+) = 4.11 and negative likelihood ratio (LR-) = 0.51, sensitivity 56%, specificity 87%, Youden index 0.43; for MMP-9, accuracy 73%, LR+ = 5.14 and LR- = 0.50, sensitivity 56%, specificity 89%, Youden index 0.45; and for CRP, accuracy 74%, LR+ = 8.56 and LR- = 0.54, sensitivity 49%, specificity 94%, Youden index 0.43.

CONCLUSIONS

MMP-9 serum concentration increasing along with the activity of the disease, exhibiting high specificity and correlating well with the indices of inflammation might be of better usefulness in the prediction of CD activity status in children than MMP-3.

Oleuropein ameliorates acute colitis in mice

Oleuropein, the major secoiridoid in olive tree leaves, possesses a wide range of health promoting properties. It has recently been shown to exhibit anti-inflammatory activity. We have evaluated the effect of oleuropein on dextran sulfate sodium (DSS)-induced experimental colitis in mice in order to provide insight into its mechanisms of action. Oral administration of oleuropein notably attenuated the extent and severity of acute colitis while reducing neutrophil infiltration; production of NO, IL-1β, IL-6, and TNF-α; expression of iNOS, COX-2, and MMP-9; and the translocation of the NF-κB p65 subunit to the nucleus in colon tissue. In LPS-stimulated peritoneal macrophages, the oleuropein metabolite, hydroxytyrosol, was shown to inhibit NO production, iNOS expression, NF-κB p65 subunit translocation, mRNA expression, and the release of IL-1β, IL-6, and TNF-α. These results suggest that the effect of oleuropein on DSS-induced colitis is associated with a decrease in the production of interleukins and expression of proteins, principally through reduction of NF-κB activation.

Antibodies targeting the catalytic zinc complex of activated matrix metalloproteinases show therapeutic potential

Endogenous tissue inhibitors of metalloproteinases (TIMPs) have key roles in regulating physiological and pathological cellular processes. Imitating the inhibitory molecular mechanisms of TIMPs while increasing selectivity has been a challenging but desired approach for antibody-based therapy. TIMPs use hybrid protein-protein interactions to form an energetic bond with the catalytic metal ion, as well as with enzyme surface residues. We used an innovative immunization strategy that exploits aspects of molecular mimicry to produce inhibitory antibodies that show TIMP-like binding mechanisms toward the activated forms of gelatinases (matrix metalloproteinases 2 and 9). Specifically, we immunized mice with a synthetic molecule that mimics the conserved structure of the metalloenzyme catalytic zinc-histidine complex residing within the enzyme active site. This immunization procedure yielded selective function-blocking monoclonal antibodies directed against the catalytic zinc-protein complex and enzyme surface conformational epitopes of endogenous gelatinases. The therapeutic potential of these antibodies has been demonstrated with relevant mouse models of inflammatory bowel disease. Here we propose a general experimental strategy for generating inhibitory antibodies that effectively target the in vivo activity of dysregulated metalloproteinases by mimicking the mechanism employed by TIMPs.

The distinct roles of MMP-2 and MMP-9 in acute DSS colitis

Expression of gelatinases A and B, also referred to matrixmetalloproteinases (MMP)-2 and -9, respectively, is increased in inflamed tissues of experimental intestinal inflammation and humans with inflammatory bowel disease (IBDs). Given that we recently reported that treatment with the selective gelatinase inhibitor RO28-2653 ameliorates acute dextrane sulfate sodium (DSS) colitis, we asked whether gelatinase A or B expression is pivotal in mediating large intestinal inflammation. Results from our study reveal that symptoms of acute DSS colitis as well as histopathological colonic changes were ameliorated in MMP-2-, but not MMP-9-deficient mice, and were paralleled by a diminished influx of immune cells. In MMP-2-deficient mice, we observed lower expression of pro-inflammatory cytokines including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and IL-6 in colonic biopsies and less overgrowth of the colonic lumen by potentially pro-inflammatory enterobacteria from the commensal gut microbiota. We conclude that rather MMP-2 than MMP-9 is causative for the establishment of DSS colitis in mice. The discrepancy of these data to prior reports might be due to substantial differences in the intestinal microbiota composition of the mice bred at different animal facilities impacting susceptibility to inflammatory stimuli. Consequently, a detailed survey of the gut microbiota should be implemented in immunological/inflammatory studies in the future in order to allow comparison of data from different facilities.

Notch1 regulates the effects of matrix metalloproteinase-9 on colitis-associated cancer in mice

BACKGROUND & AIMS

Inflammatory bowel disease increases the risks of colon cancer and colitis-associated cancer (CAC). Epithelial cell-derived matrix metalloproteinase (MMP)-9 mediates inflammation during acute colitis and the cleavage and activation of the transcription factor Notch1, which prevents differentiation of progenitor cells into goblet cells. However, MMP-9 also protects against the development of CAC and acts as a tumor suppressor. We investigated the mechanisms by which MMP-9 protects against CAC in mice.

METHODS

C57/B6 wild-type mice were given a single dose of azoxymethane and 2 cycles of dextran sulfate sodium (DSS). Mice were also given the γ-secretase inhibitor difluorophenacetyl-l-alanyl-S-phenylglycine t-butyl ester (DAPT) or dimethyl sulfoxide (control) during each DSS cycle; they were killed on day 56. We analyzed embryonic fibroblasts isolated from wild-type and MMP-9-/- mice and HCT116 cells that were stably transfected with MMP-9.

RESULTS

Wild-type mice were more susceptible to CAC following inhibition of Notch1 by DAPT, shown by increased numbers of tumors and level of dysplasia compared with controls. Inhibition of Notch1 signaling significantly reduced protein levels of active Notch1, p53, p21WAF1/Cip1, Bax-1, active caspase-3, as well as apoptosis, compared with controls. Similar results were observed in transgenic HCT116 cells and embryonic fibroblasts from MMP-9-/- mice on γ-radiation-induced damage of DNA.

CONCLUSIONS

MMP-9 mediates Notch1 signaling via p53 to regulate apoptosis, cell cycle arrest, and inflammation. By these mechanisms, it might prevent CAC.

Matrix metalloproteinase-9 inhibition reduces inflammation and improves motility in murine models of postoperative ileus

BACKGROUND & AIMS

Matrix metalloproteinase (MMP)-9, a member of the gelatinase family of MMPs, mediates leukocyte migration during inflammation. Inflammation contributes to development of postoperative ileus (POI), which is caused by physical disturbances to the bowel during abdominal surgery. We evaluated the role of MMP-9 in POI and investigated whether disruption of MMP-9 or administration of an inhibitor of MMP-9 activity reduced cellular inflammation and bowel dysmotility in rat and mouse models of POI.

METHODS

Mice and rats underwent laparotomy and bowel manipulation; bowel tissues were collected 3 to 24 hours later and analyzed by real-time reverse-transcriptase polymerase chain reaction, immunoblot, in situ zymography, and functional analyses.

RESULTS

Bowel manipulation resulted in a time-dependent increase in MMP-9 expression within the intestinal muscularis; increases in MMP-9 messenger RNA were inducible nitric oxide synthase dependent. Immunoblot analyses confirmed the presence of the proenzyme and the catalytically active form of MMP-9. Administration of MMP-2/MMP-9 II, a dual active-site inhibitor, reduced the number of myeloperoxidase-positive immune cells that infiltrated the muscularis and prevented the surgically induced reduction in bowel smooth muscle contractility. Zymography analysis, performed in muscularis whole mounts in situ, indicated that MMP-9 and not MMP-2 mediated the gelatinase activity observed in infiltrating cells. MMP-9 knockout mice were protected from the inflammation and dysmotility associated with POI.

CONCLUSIONS

MMP-9 mediates cellular inflammatory responses within the intestinal muscularis in mouse and rat models of POI. Inhibition of MMP-9 activity reduced recruitment of immune cells to the intestinal muscularis, preventing loss of smooth muscle contractility. Induction of MMP-9 expression requires inducible nitric oxide synthase.

Transforming growth factor-beta type 1 receptor (ALK5) and Smad proteins mediate TIMP-1 and collagen synthesis in experimental intestinal fibrosis

Transforming growth factor β (TGF-β) is known to play a key role in intestinal fibrosis; however, the underlying mechanisms are not well understood. TGF-β signal transduction is through TGF-β receptors, including the TGF-β type 1 receptor. Most cell types contain a TGF-β type 1 receptor form known as activin receptor-like kinase 5 (ALK5), which propagates the signal to the nucleus through the phosphorylation of Smad2 and Smad3 proteins. Therefore, we assessed the effect of the disruption of TGF-β/ALK5/Smad signalling by an ALK5 inhibitor (SD-208) in two experimental animal models of intestinal fibrosis: anaerobic bacteria- and trinitrobenzensulphonic acid-induced colitis. In addition, isolated myofibroblasts were pretreated with SD-208 and exposed to recombinant TGF-β1. Finally, myofibroblasts were transfected with ALK5, Smad2, and Smad3-specific siRNA. Up-regulation of ALK5 and TIMP-1, phosphorylation of Smad2 and Smad3 proteins, and increased intestinal wall collagen deposition were found in both experimental animal models. These effects were decreased by SD-208. TGF-β1 treatment also induced phosphorylation of Smad2 and Smad3 and up-regulation of ALK5 protein, TIMP-1, and α2 type 1 collagen gene expression in isolated myofibroblasts. Again these effects were inhibited by SD-208. Also, ALK5, Smad2, and Smad3 siRNA abolished the induction of TIMP-1 and α2 type 1 collagen. Our findings provide evidence that the TGF-β/ALK5/Smad pathway participates in the pathogenesis of experimental intestinal fibrosis. These data show promise for the development of an effective therapeutic intervention in this condition.

The effect of corticosteroid on metalloproteinase levels of nasal polyposis

OBJECTIVES

The aim of this study was to investigate the effect of corticosteroid treatment on topical and systemic metalloproteinase levels of patients with nasal polyposis (NP).

STUDY DESIGN

Prospective clinical trial.

METHODS

The study included patients undergoing a paranasal sinus operation due to NP. Oral corticosteroid therapy was performed on all patients before endoscopic sinus surgery. Endoscopic and radiological evaluation were performed and nasal tissue specimens and venous blood samples were collected before (preop phase) and after corticosteroid treatment (periop phase) and also one month after surgery (postop phase). Endoscopic and computed tomography scan findings were scored adequately and all tissue and blood samples were examined cumulatively.

RESULTS

The study included 27 patients with inflammatory NP. Preop tissue matrix metalloproteinase-2 (MMP-2) levels were found to be significantly lower than preop and postop concentrations. In contrast, periop serum MMP-2 levels were found to be significantly higher than preop and postop concentrations. Periop tissue inhibitor of metalloproteinase-1 (TIMP-1) levels were also found to be significantly lower than preop and postop concentrations, similar to MMP-2 tissue concentrations. However, there was no statistical difference among tissue MMP-9 concentrations of the three phases. In addition, there was also no statistical difference among serum MMP-9 levels of the three phases.

CONCLUSIONS

Oral corticosteroid treatment especially reduces tissue MMP-2, then TIMP-1. Severity of nasal polyposis primarily correlates with increasing tissue MMP-2/TIMP-1 ratio, then MMP-9/TIMP-1. These results suggest that selective inhibition for MMP-2 and activation for TIMP-1 might be a novel therapeutic strategy for patients with nasal polyposis.

The importance of neovascularization and its inhibition for allogeneic hematopoietic stem cell transplantation

GVHD and tumor relapse are fundamental problems in allogeneic HSCT. Recent research has linked neovascularization to GVHD, tumor growth, and graft-versus-tumor (GVT) activity. Damage of the endothelium by the conditioning regimen provides the initiation stimulus for recruitment of donor-derived endothelial cells and their progenitors. During the early inflammatory phase of GVHD there is considerable neovascularization facilitating migration of inflammatory cells to target organs. In the course of GVHD, however, the vasculature itself becomes a target of alloreactive donor T cells. As a consequence, later stages of GVHD are characterized by fibrosis and rarefaction of blood vessels. Importantly, the inhibition of tumor-neovascularization by activated donor T cells that release antiangiogenic substances contributes to GVT and may be enhanced by pharmacologic inhibition of neovascularization. Furthermore, the therapeutic inhibition of neovascularization may improve immunotherapy for cancer by enhancing leukocyte infiltration in tumor tissue because of normalization of tumor vessels and stimulation of leukocyte-vessel wall interactions. These insights identify important mechanisms underlining the importance of neovascularization for allogeneic immune responses and move therapeutic approaches targeting neovascularization into the spotlight. This perspective covers current knowledge of the role of neovascularization during GVHD as well as GVT and its implications for HSCT.

VPAC1 (vasoactive intestinal peptide (VIP) receptor type 1) G protein-coupled receptor mediation of VIP enhancement of murine experimental colitis

Distinct roles of the two T cell G protein-coupled receptors for vasoactive intestinal peptide (VIP), termed VPAC1 and VPAC2, in VIP regulation of autoimmune diseases were investigated in the dextran sodium sulfate (DSS)-induced murine acute colitis model for human inflammatory bowel diseases. In mice lacking VPAC2 (VPAC2-KO), DSS-induced colitis appeared more rapidly with greater weight loss and severe histopathology than in wild-type mice. In contrast, DSS-induced colitis in VPAC1-KO mice was milder than in wild-type mice and VPAC2-KO mice. Tissues affected by colitis showed significantly higher levels of myeloperoxidase, IL-6, IL-1β and MMP-9 in VPAC2-KO mice than wild-type mice, but there were no differences for IL-17, IFN-γ, IL-4, or CCR6. Suppression of VPAC1 signals in VPAC2-KO mice by PKA inhibitors reduced the clinical and histological severity of DSS-induced colitis, as well as tissue levels of IL-6, IL-1β and MMP-9. Thus VIP enhancement of the severity of DSS-induced colitis is mediated solely by VPAC1 receptors.

MMP9 is protective against lethal inflammatory mass lesions in the mouse colon

The family of matrix metalloproteinases (MMPs) is responsible for extracellular matrix degradation during physiological and pathophysiological tissue remodeling processes such as embryogenesis, tissue repair and cancer progression. Despite these important roles of MMPs, inhibition or ablation of individual members of the MMP family in animal models have been shown to have little effect. It has been speculated that this results from a functional overlap between individual MMPs and (as-yet-unclassified) functional overlaps between MMPs and other protease systems. We here present genetic data showing that concomitant ablation of MMP9 (gelatinase B) and the serine protease plasmin results in lethal inflammatory mass lesions in the colon. These lesions possessed several histological attributes that are characteristic of mucosal prolapse seen in humans, and they were found to be associated with splenomegaly, enlarged mesenteric lymph nodes, decreased thymus size and altered populations of circulating immune cells. A time-course study provided evidence that the massive lymphoid hyperplasia and reactive changes were secondary to discrete fibrinous lesions also observed in mice only deficient for plasminogen (Plg), the zymogen for plasmin. These data demonstrate a non-appreciated vital protective role for MMP9 in the absence of Plg.

Supplemental calcium attenuates the colitis-related increase in diarrhea, intestinal permeability, and extracellular matrix breakdown in HLA-B27 transgenic rats

We have shown in several controlled rat and human infection studies that dietary calcium improves intestinal resistance and strengthens the mucosal barrier. Reinforcement of gut barrier function may alleviate inflammatory bowel disease (IBD). Therefore, we investigated the effect of supplemental calcium on spontaneous colitis development in an experimental rat model of IBD. HLA-B27 transgenic rats were fed a purified high-fat diet containing either a low or high calcium concentration (30 and 120 mmol CaHPO4/kg diet, respectively) for almost 7 wk. Inert chromium EDTA (CrEDTA) was added to the diets to quantify intestinal permeability by measuring urinary CrEDTA excretion. Relative fecal wet weight was determined to quantify diarrhea. Colonic inflammation was determined histologically and by measuring mucosal interleukin (IL)-1beta. In addition, colonic mucosal gene expression of individual rats was analyzed using whole-genome microarrays. The calcium diet significantly inhibited the increase in intestinal permeability and diarrhea with time in HLA-B27 rats developing colitis compared with the control transgenic rats. Mucosal IL-1beta levels were lower in calcium-fed rats and histological colitis scores tended to be lower (P = 0.08). Supplemental calcium prevented the colitis-induced increase in the expression of extracellular matrix remodeling genes (e.g. matrix metalloproteinases, procollagens, and fibronectin), which was confirmed by quantitative real-time PCR and gelatin zymography. In conclusion, dietary calcium ameliorates several important aspects of colitis severity in HLA-B27 transgenic rats. Reduction of mucosal irritation by luminal components might be part of the mechanism. These results show promise for supplemental calcium as effective adjunct therapy for IBD.

Matrix metalloproteinase-9-mediated tissue injury overrides the protective effect of matrix metalloproteinase-2 during colitis

Matrix metalloproteinases (MMP) play an important role in pathogenesis of inflammatory bowel disease (IBD). Two known gelatinases, MMP-2 and MMP-9, are upregulated during IBD. Epithelial-derived MMP-9 is an important mediator of tissue injury in colitis, whereas MMP-2 protects against tissue damage and maintains gut barrier function. It has been suggested that developing strategies to block MMP-9 activity in the gut might be of benefit to IBD. However, given that MMP-2 and MMP-9 are structurally similar, such approaches would also likely inhibit MMP-2. Thus, to gain insight into outcome of inhibiting both MMP-2 and MMP-9, MMP-2(-/-)/MMP-9(-/-) double knockout mice (dKO) lacking both MMP-2 and MMP-9 were used in this study. Three models of murine colitis were used: dextran sodium sulfate (DSS), Salmonella typhimurium (S.T.), and trinitrobenzene sulfonic acid (TNBS). Our data demonstrate that MMP-2 and MMP-9 activities were highly upregulated in wild-type (WT) mice treated with DSS, S.T., or TNBS whereas dKO mice were resistant to the development of colitis. WT mice had extensive inflammation and tissue damage compared with dKO mice as suggested by histological assessment and myeloperoxidase activity. In conclusion, these results suggest an overriding role of MMP-9 in mediating tissue injury compared with the protective role of MMP-2 in development of colitis. Thus inhibition of MMP-9 may be beneficial in treatment of colitis even if resulting in inhibition of MMP-2.

Synthesis and biological evaluation of curcuminoid pyrazoles as new therapeutic agents in inflammatory bowel disease: effect on matrix metalloproteinases

Seven N-unsubstituted curcuminoid pyrazoles have been synthesized from the corresponding beta-diketones (including curcumin). We evaluated the possibility of curcuminoid pyrazoles regulating the activity of matrix metalloproteinases (MMPs) by human intestinal epithelial cells in vitro. Zymographic analysis revealed that three compounds significantly down-regulated MMP-9 activity on inflammation-induced intestinal epithelial cells, making them original candidates for the treatment of inflammatory bowel disease (IBD).

Matrix metalloproteinase-9 derived from polymorphonuclear neutrophils increases gut barrier dysfunction and bacterial translocation in rat severe acute pancreatitis

BACKGROUND

The role of polymorphonuclear neutrophil granulocytes (PMNs) and the PMN-derived protease, which is called matrix metalloproteinase-9 (MMP-9), for the gut barrier dysfunction in severe acute pancreatitis (SAP) has not yet been clarified. The aim of this study was to evaluate the effects of PMNs and MMP-9 on gut barrier dysfunction in rat SAP.

METHODS

SAP was induced by the injection of 5% sodium taurocholate, and anti-rat PMN serum or BB-94 were administered 48 h and 24 h, respectively, before the induction of acute pancreatitis. Twenty-four hours after the induction of acute pancreatitis, the gut barrier dysfunction and the incidence of bacterial translocation (BT) and PMN transmigration were investigated by bacterial, histologic, and biochemical (MPO) analysis. Inhibition of MMP-9 was achieved by depletion of PMNs or inhibition of MMP-activity by a broad-spectrum MMP inhibitor and confirmed by zymography. In addition, reactive oxygen species were evaluated by spin trap assay.

RESULTS

The mucosal injury and the infiltration of PMNs into the gut tissue of rats with SAP were significantly increased in comparison with rats treated with anti-rat PMN serum or BB-94. The levels of MMP-9 and reactive oxygen species in the gut of rats with SAP were significantly higher than those of the rats treated with anti-rat PMN serum or BB-94. Pretreatment with anti-rat PMN serum or BB-94 reduced the incidence of BT in SAP.

CONCLUSION

The incidence of BT in SAP was prevented by the depletion of PMNs or less pronounced by the injection of the MMP inhibitor BB-94. PMNs play an important pathophysiologic role in the occurrence of BT, and MMP-9 is involved in both BT and PMN transmigration in rat SAP.

The expression of MMP-2, MMP-7, MMP-9, and TIMP-1 in chronic rhinosinusitis and nasal polyposis

OBJECTIVES

To investigate the expression and clinical significance of MMP-2, MMP-7, MMP-9, and TIMP-1 in patients with nasal polyposis (NP) and chronic rhinosinusitis (CRS).

STUDY DESIGN

Prospective study.

SUBJECTS AND METHODS

This study involved 54 patients. There were three groups: nasal polyposis group, chronic rhinosinusitis group, and control group. Specimens were collected during endoscopic sinus surgery. Each sample was immunohistochemically examined.

RESULTS

Expression of MMP-2 was found significantly increased in NP, whereas MMP-7 expression was found significantly increased in CRS (P < 0.001). TIMP-1 was significantly high in control group compared to CRS and NP (P < 0.001 and P = 0.002, respectively).

CONCLUSIONS

Different regulation type of activation of MMPs has been found in these two diseases. If MMP-2 expression is intense in the mucosa, then this ends with polyp formation; if MMP-7 expression is intense, it ends with CRS or stays as CRS.

Role of chymase-dependent matrix metalloproteinase-9 activation in mice with dextran sodium sulfate-induced colitis

Matrix metalloproteinase (MMP)-9 plays an important role in the pathogenesis of colitis. Recent studies have demonstrated that chymase is involved in the conversion of promatrix metalloproteinase (proMMP)-9 to MMP-9. However, whether chymase contributes to the activation of proMMP-9 in colitis has remained unclear. In this study, we administered 5% dextran sodium sulfate (DSS) solution to mice for 7 days. At 7 days after starting administration, both chymase activity and MMP-9 activity were significantly increased. In extract from colitis in DSS-treated mice, MMP-9 activity was significantly increased after 8 h of incubation, but increased activity was almost completely suppressed in the presence of a chymase inhibitor, 2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidine-1-yl)-N-[{3,4-dioxo-1-phenyl-7-(2-pyridyloxy)}-2-heptyl] acetamide (NK3201). At 7 days after starting administration, intestinal length was significantly shorter in DSS-treated mice than in normal mice, but these changes were significantly prevented by NK3201 (10 mg/kg per day i.p.). Disease activity index and histological damage score were also significantly reduced by NK3201. The filtrated neutrophil number was significantly decreased by NK3201. Furthermore, NK3201 significantly attenuated not only chymase activity but also MMP-9 activity in DSS-treated mice. These findings suggest that chymase plays an important role in the development of colitis via MMP-9 activation.

PPARalpha transcriptionally induces AhR expression in Caco-2, but represses AhR pro-inflammatory effects

In this work we demonstrate that Caco-2 cell treatment with WY-14643 (a potent PPARalpha agonist) causes an increase in AhR expression. Luciferase assays and directed mutagenesis experiments showed that induction mainly occurred at transcriptional level and involved a PPRE site located within the AhR promoter. These results were further confirmed by the use of PPARalpha knockout mice in which AhR induction by WY14643 was abrogated. In addition to CYP1 regulation, AhR has been described as being involved in inflammation, so we also studied the effect of AhR regulation by PPARalpha on the expression of some inflammation target genes. 3-Methylcholanthrene (a potent AhR agonist) increased the expression (mRNA) of the major inflammatory targets IL-1beta and MMP9. WY-14643 co-treatment abrogated the 3-methylcholanthrene pro-inflammatory effect. Hence the anti-inflammatory effect of PPARalpha overrides the pro-inflammatory effect of AhR.

Mechanisms of disease: protease functions in intestinal mucosal pathobiology

Of all our organ systems, the gastrointestinal tract contains the highest levels of endogenous and exogenous proteases (also known as proteinases and peptidases); however, our understanding of their functions and interactions within the gastrointestinal tract is restricted largely to nutrient digestion. The gut epithelium is a sensor of the luminal environment, not only controlling digestive, absorptive and secretory functions, but also relaying information to the mucosal immune, vascular and nervous systems. These functions involve a complex array of cell types that elaborate growth factors, cytokines and extracellular matrix (ECM) proteins, the activity and availability of which are regulated by proteases. Proteolytic activity must be tightly regulated in the face of diverse environmental challenges, because unrestrained or excessive proteolysis leads to pathological gastrointestinal conditions. Moreover, enteric microbes and parasites can hijack proteolytic pathways through 'pathogen host mimicry'. Understanding how the protease balance is maintained and regulated in the intestinal epithelial cell microenvironment and how proteases contribute to physiological and pathological outcomes will undoubtedly contribute to the identification of new potential therapeutic targets for gastrointestinal diseases.

Matrix metalloproteinase-9 regulates MUC-2 expression through its effect on goblet cell differentiation

BACKGROUND & AIMS

We recently demonstrated that epithelial-derived matrix metalloproteinase (MMP) 9 up-regulated during inflammatory bowel disease is a critical mediator of tissue damage during colitis. MMP-9 null mice (MMP-9(-/-)) develop dramatically reduced inflammatory response to luminally administered colitic agents in the face of intact systemic immune response and inflammatory cell recruitment, suggesting protected epithelial barrier in these mice. In this study, we sought to address the role and mechanism by which MMP-9 influences barrier protective function.

METHODS

Wild-type and MMP-9(-/-) mice were used for in vivo studies, and the goblet cell line HT29-cl.16E and the enterocyte cell line Caco2-BBE were used for in vitro studies.

RESULTS

Compared with wild-type mice, MMP-9(-/-) mice had an increased number of goblet cells and MUC-2 expression. In addition, KLF-4 and Elf-3, transcription factors involved in terminal differentiation of goblet cells were up-regulated, whereas notch intracellular domain (NICD; activated Notch-1) was down-regulated in MMP-9(-/-) mice. These findings suggest altered epithelial cell differentiation in MMP-9(-/-) mice. Temporal expression of MMP-9 inversely correlated with MUC-2 expression during maturation of goblet cells. MMP-9 over expression inhibited goblet cell differentiation in vitro. Conversely, MMP-9 gene silencing in Caco2-BBE cells resulted in a change in their phenotype toward goblet cells. Finally, MMP-9 over expression or silencing in goblet cells increased or decreased Salmonella typhimurium adherence, respectively.

CONCLUSIONS

MMP-9 regulates goblet cell differentiation in colon. The effect of MMP-9 on goblet cells could contribute to alteration in mucosal defense leading to inflammation. Together, our data uncover a novel function of MMP-9 in intestinal epithelial cells.

Induction of matrix metalloproteinase-2 and matrix metalloproteinase-9 expression in gastric cancer cells by tumor necrosis factor-α

AIM: To investigate the inductive effect of tumor necrosis factor-α (TNF-α) on the expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) in gastric cancer cells.

METHODS: Gastric cancer cells were stimulated by exogenous TNF-α and the cells without stimulation served as controls. The contents of MMP-2 and MMP-9 in the supernatant fluid of gastric cancer cells were measured by enzyme-linked immunosorbnent assay (ELISA). The expression of MMP-2 and MMP-9 mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). Western blot was used to detect the expression of MMP-2 and MMP-9 protein in gastric cancer cells.

RESULTS: Following stimulation with 1, 10 and 100 mg/L TNF-α, the contents of MMP-2 (8.24 ± 1.36, 23.65 ± 3.45, 14.83 ± 2.54 ng/L) and MMP-9 (12.47 ± 2.66, 34.12 ± 6.78, 23.31 ± 4.45 ng/L) in the supernatant fluid of gastric cancer cells were increased significantly as compared with those in the control group (MMP-2: 1.56 ± 0.23 ng/L; 5.25 ± 0.89 ng/L; all P < 0.01). After 16 h of stimulation with TNF-α, the contents of MMP-2 and MMP-9 in the supernatant fluid reached the peak values, which were 23.65 ± 3.45 and 34.12 ± 6.78 ng/L, respectively. MMP-2 and MMP-9 expression were up-regulated both at mRNA and protein level.

CONCLUSION: TNF-α can up-regulate the expression of MMP-2 and MMP-9 in gastric cancer cells.