Divergent patterns of matrix metalloproteinase activity during wound healing in ileum and colon of rats

Impact of Glyphosate-Roundup® in the Ileal Structure of Male and Female Rats: A Morphological and Immunohistochemical Study

The current study was aimed to evaluate the effects of variable doses of the weedicide glyphosate on the ileal (the final section of the small intestine) structure of rats of both sexes, using histological, histochemical, and ultrastructural methods. Forty animals were classified into four groups of 10 animals per group (five males and five females). The first group acted as a control, and the remaining groups were treated with glyphosate-Roundup® 25, 50, and 100 mg/kg body weight daily for 15 days. The results indicated extinct histopathological changes manifested in the deformation of villi, foci of leukocytic infiltration in the core of villi, and hyperplasia of goblet cells. Histochemical examination (Alcian blue and Periodic acid-Schiff stain) revealed a strong positive reaction of goblet cells and an increase in their number in all treated groups. In addition, the immunohistochemical investigation revealed the immunoreactivity of matrix metalloproteinase-9 expression. Furthermore, electron microscopic alternations were represented by the deformation of nuclei, destruction of microvilli, and deposition of lipid droplets. Collectively, the present findings indicate that treatment with glyphosate results in extensive morphological alternations to the ileal structure of rats of both sexes and that female rats are more affected than male rats are.

Matrix metalloproteinase-9 in relation to patients with complications after colorectal surgery: a systematic review

PURPOSE

Anastomotic leakage (AL) is the most severe complication following colorectal resection and is associated with increased mortality. The main group of enzymes responsible for collagen and protein degradation in the extracellular matrix is matrix metalloproteinases. The literature is conflicting regarding anastomotic leakage and the degradation of extracellular collagen by matrix metalloproteinase-9 (MMP-9). In this systematic review, the possible correlation between anastomotic leakage after colorectal surgery and MMP-9 activity is investigated.

METHODS

Embase, MEDLINE, Cochrane, and Web of Science databases were searched up to 3 February 2020. All published articles that reported on the relationship between MMP-9 and anastomotic leakage were selected. Both human and animal studies were found eligible. The correlation between MMP-9 expression and anastomotic leakage after colorectal surgery.

RESULTS

Seven human studies and five animal studies were included for analysis. The human studies were subdivided into those assessing MMP-9 in peritoneal drain fluid, intestinal biopsies, and blood samples. Five out of seven human studies reported elevated levels of MMP-9 in patients with anastomotic leakage on different postoperative moments. The animal studies demonstrated that MMP-9 activity was highest in the direct vicinity of an anastomosis. Moreover, MMP-9 activity was significantly reduced in areas further proximally and distally from the anastomosis and was nearly or completely absent in uninjured tissue.

CONCLUSION

Current literature shows some relation between MMP-9 activity and colorectal AL, but the evidence is inconsistent. Innovative techniques should further investigate the value of MMP-9 as a clinical biomarker for early detection, prevention, or treatment of AL.

Innovative approaches for induction of gastrointestinal anastomotic healing: an update on experimental and clinical aspects

PURPOSE

In most cases, traditional techniques to perform an anastomosis following gastrointestinal resections lead to successful healing. However, despite focused research in the field, in certain high-risk situations leakage rates remain almost unchanged. Here, additional techniques may help the surgeon to protect the anastomosis and prevent leakage. We give an overview of some of the latest developments on experimental and clinical techniques for induction of anastomotic healing.

METHODS

We performed a review of the current literature on approaches to improve anastomotic healing.

RESULTS

Many promising approaches with a high clinical potential are in the developmental pipeline. Highly experimental approaches like inhibition of matrix metalloproteinases, stem cell therapy, hyperbaric oxygen therapy, induction of the hypoxic adaptive response, and the administration of growth factors are still in the preclinical phase. Other more clinical developments aim to strengthen the anastomotic suture line mechanically while shielding it from the influence of the microbiome. Among them are gluing, seaming the staple line, attachment of laminar biomaterials, and temporary intraluminal tubes. In addition, individualized bowel preparation, selectively reducing certain detrimental microbial populations could become the next stage of bowel preparation. Compression anastomoses are evolving as an equivalent technique additional to established hand-sewn and stapled anastomoses. Fluorescence angiography and flexible endoscopy could complement intraoperative quality control additionally to the air leak tests. Virtual ileostomy is a concept to prepare the bowel for the easy formation of a stoma in case of leakage.

CONCLUSION

A variety of promising diagnostic and prophylactic measures that may support the surgeon in identifying high-risk anastomoses and support them according to their potential deficits is currently in development.

Transmural intestinal wall permeability in severe ischemia after enteral protease inhibition

In intestinal ischemia, inflammatory mediators in the small intestine's lumen such as food byproducts, bacteria, and digestive enzymes leak into the peritoneal space, lymph, and circulation, but the mechanisms by which the intestinal wall permeability initially increases are not well defined. We hypothesize that wall protease activity (independent of luminal proteases) and apoptosis contribute to the increased transmural permeability of the intestine's wall in an acutely ischemic small intestine. To model intestinal ischemia, the proximal jejunum to the distal ileum in the rat was excised, the lumen was rapidly flushed with saline to remove luminal contents, sectioned into equal length segments, and filled with a tracer (fluorescein) in saline, glucose, or protease inhibitors. The transmural fluorescein transport was determined over 2 hours. Villi structure and epithelial junctional proteins were analyzed. After ischemia, there was increased transmural permeability, loss of villi structure, and destruction of epithelial proteins. Supplementation with luminal glucose preserved the epithelium and significantly attenuated permeability and villi damage. Matrix metalloproteinase (MMP) inhibitors (doxycycline, GM 6001), and serine protease inhibitor (tranexamic acid) in the lumen, significantly reduced the fluorescein transport compared to saline for 90 min of ischemia. Based on these results, we tested in an in-vivo model of hemorrhagic shock (90 min 30 mmHg, 3 hours observation) for intestinal lesion formation. Single enteral interventions (saline, glucose, tranexamic acid) did not prevent intestinal lesions, while the combination of enteral glucose and tranexamic acid prevented lesion formation after hemorrhagic shock. The results suggest that apoptotic and protease mediated breakdown cause increased permeability and damage to the intestinal wall. Metabolic support in the lumen of an ischemic intestine with glucose reduces the transport from the lumen across the wall and enteral proteolytic inhibition attenuates tissue breakdown. These combined interventions ameliorate lesion formation in the small intestine after hemorrhagic shock.

Expression and inhibition of matrix metalloproteinase (MMP)-8, MMP-9 and MMP-12 in early colonic anastomotic repair

PURPOSE

Submucosal collagen is paramount for colonic anastomotic integrity. Matrix metalloproteinases (MMPs) mediate collagen degradation that increases the risk of wound dehiscence. Although broad-spectrum MMP inhibitors are beneficial for anastomotic strength, they can cause adverse reactions. Knowledge of specific MMPs responsible for the weakening of anastomoses can be used to optimise MMP inhibition therapy. We aimed to quantify transcript and protein levels of multiple MMPs in colonic anastomoses and evaluate the effect of inhibiting the MMPs that displayed the highest expression levels on anastomotic repair.

METHODS

Left-sided colonic anastomoses were made in male Sprague-Dawley rats. After 3 days when biomechanical strength is lowest, MMP mRNA and protein levels were measured by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assays and gelatin zymography. The effects of the MMP-8, MMP-9 and MMP-12 synthetic inhibitor AZD3342 was also studied.

RESULTS

MMP-8, MMP-9 and MMP-12 gene and protein expression increased profoundly (p < 0.01), and MMP-13 mRNA and MMP-2 mRNA and protein modestly (p < 0.001) in the anastomoses. MMP-3 mRNA levels were not up-regulated significantly compared with adjacent uninjured colon. Increased anastomotic MMP-12 levels paralleled macrophage infiltration by immunohistochemical analyses. AZD3342 (50 mg/kg) treatment increased the anastomotic breaking strength by 29% (p = 0.015) day 3 compared with vehicle. Improved anastomotic strength was not accompanied with alterations of type I or type III procollagen mRNA but was possibly due to inhibition of the concerted digestive action on the existent submucosal collagens by the targeted MMPs.

CONCLUSION

The present findings justify the concept of selective MMP inhibition to enhance anastomotic strength in colon.

Constitutive expression of MMP9 in intestinal epithelium worsens murine acute colitis and is associated with increased levels of proinflammatory cytokine Kc

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease, is a chronic inflammatory disease associated with an increased risk for colon cancer. Matrix metalloproteinases (MMPs) are the predominant proteinases expressed in the gut mucosa during active IBD. Our laboratory has previously demonstrated that epithelial-derived MMP9 is absent in normal colonic tissue but is upregulated during IBD. In this study MMP9 transgenic mice (Tg-villin-MMP9) are generated specifically to overexpress MMP9 in intestinal epithelium to examine the role and underlying mechanism by which it modulates the pathogenesis of acute colitis. Dextran sodium sulfate (3% DSS)- and Salmonella typhimurium (S.T.)-induced colitis models were used to study gut inflammation in Tg-villin-MMP9 and wild-type littermates (WT). Colonic tissue was analyzed via Western blot, histology, myeloperoxidase (MPO) assay, and quantitative PCR. Tg-villin-MMP9 mice expressed significantly increased MMP9 mRNA and protein expression at basal level. There was a significant decrease in the goblet cells, but a significant increase in proliferation and apoptosis were observed among Tg-villin-MMP9 mice compared with WT mice. There was also a significant increase in the proinflammatory chemokine Kc among Tg-villin-MMP9 compared with WT mice. Tg-villin-MMP9 exhibited a severe inflammatory response than WT mice in both DSS- and S.T.-induced colitis models as evident by greater weight loss and higher clinical score, histological score, and MPO activity, which correlated with relative levels of Kc mRNA. MMP9 expressed by intestinal epithelial cells mediates inflammation in colitis with simultaneous increase in proinflammatory cytokine Kc.

The effect of erythropoietin on anastomotic healing of irradiated rats

AIM

The aim of the present study is to evaluate the possible protective effects of erythropoietin (EPO) on anastomotic wound healing after preoperative radiotherapy according to its pleiotropic mechanism of action.

METHODS

Thirty-two male Wistar albino rats were randomized into four groups containing eight rats each: ANAS group, standard resection plus anastomosis; RT+ANAS group, radiation plus standard resection plus anastomosis; ANAS+EPO group, standard resection plus anastomosis plus EPO; RT+ANAS+EPO, radiation plus standard resection plus anastomosis plus EPO. All animals were sacrificed by cardiac puncture, and anastomotic healing was measured by bursting pressure, hydroxyproline (OHP) levels, myeloperoxidase (MPO) activity and histopathological evaluations. Malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and matrix metalloproteinase-9 (MMP-9) were also measured in serum specimens.

RESULTS

OHP levels in the RT+ANAS + EPO group were significantly increased compared with other groups (p < .05). In contrast, MPO activity in the RT+ANAS+EPO group was significantly decreased compared with other groups (p < .05). Serum MDA levels were found to be decreased in the ANAS+EPO and RT+ANAS+EPO groups (p < .05). Group comparisons demonstrated that bursting pressure was significantly higher in EPO treated rats (p < .05). The histopathology results revealed that EPO treatment improves anastomotic wound healing though decreased necrosis and inflammatory cell infiltration and increased fibroblast activity.

CONCLUSION

The findings of the present study indicate that EPO contributes to wound healing and the strength of colon anastomosis following radiation due to its antioxidant and anti-inflammatory effects, but further studies are needed to explore the significance of these effects.

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.

Nonselective matrix metalloproteinase but not tumor necrosis factor-α inhibition effectively preserves the early critical colon anastomotic integrity

BACKGROUND

Increased matrix metalloproteinase (MMP) activity has been implicated in the pathogenesis of colorectal anastomotic leakage. Tumor necrosis factor-α (TNF-α) induces MMPs and may influence anastomosis repair.

METHODS

We assessed the efficacies of the nonselective hydroxamate MMP inhibitor GM6001, the selective hydroxamate MMP inhibitor AG3340 and a TNF-α antagonist with respect to anastomotic breaking strength of left-sided colon anastomoses in male Sprague-Dawley rats.

RESULTS

Systemic GM6001 treatment effectively blocked MMP activity and maintained the initial breaking strength day 0 of the anastomoses when administered subcutaneously as daily depositions (100 mg/kg) or continuously (10 mg/kg/day). In contrast, the anastomotic biomechanic strength was lowered by 55% (p < 0.001) in vehicle-treated rats on postoperative day 3. GM6001 treatment increased breaking strength by 88% (p < 0.0005) compared with vehicle-treated rats day 3 and reduced (p = 0.003) the occurrence of spontaneous anastomotic dehiscence. Histologically, the anastomotic wound was narrower (p < 0.05) in the longitudinal direction in GM6001-treated animals whereas GM6001 had no significant effect on inflammatory cell infiltration or epithelialization. AG3340 (10 mg/kg) increased (p < 0.012) breaking strength by 47% compared with vehicle on day 3 but did not significantly prevent the reduction of the initial breaking strength on day 0. Although the increased TNF-α levels in the wound were attenuated, the anastomotic breaking strength was not improved (p = 0.62) by the TNF-α (10 mg/kg) inhibitor given systemically.

CONCLUSIONS

Pharmacological nonselective MMP inhibition ought to be explored as a prophylactic regimen to reduce anastomotic complications following colorectal resection. The involvement of TNF-α was insignificant in anastomotic wound healing in an experimental model.

The role of matrix metalloproteinases in intestinal epithelial wound healing during normal and inflammatory states

BACKGROUND

Healing of the epithelium is a key consideration in gastrointestinal surgery. Inflammation is one factor innate to patients with inflammatory bowel disease that poses a risk of delayed healing of the intestinal epithelium postoperatively.

MATERIALS AND METHODS

Epithelial wounding model was performed on rat intestinal epithelial cells grown under control and interferon gamma (IFN-γ)-, interleukin-1beta (IL-1β)-, and tumor necrosis factor-alpha (TNF-α)-stimulated conditions. Wounds were measured and percent healing was calculated at 0, 8 and 24 h. Western blot analysis was performed using matrix metalloproteinase (MMP)-7 primary antibody and semiquantitative densitometry was conducted.

RESULTS

Wounds were 50.0% and 99.7% healed under control conditions at 8 and 24 h, respectively. IL-1β and IFN-γ delayed wound closure. MMP-7 increased by 2.3-fold at 8 h and 1.6-fold at 24 h during wound healing. Activated MMP-7 increased by 3- to 5-fold at 24 h. IL-1β stimulation increased levels of MMP-7 by 17% to 37% above the elevated expression due to healing alone. TNF-α up-regulated MMP-7 in non-wounded and wounded cells, and IFN-γ did not affect its expression. When MMP-7 activity was blocked, wound closure was delayed.

CONCLUSIONS

MMP-7 significantly contributes to intestinal epithelial wound closure evidenced by: (1) presence of increased MMP-7 during healing under control conditions and (2) the delayed rate of closure when MMP-7 activity was blocked. IL-1β increased MMP-7 levels beyond those seen during normal healing. It appears that some increase in MMP-7 is necessary for normal wound closure; however, its overexpression may delay intestinal epithelial wound healing, especially when MMP-7 is up-regulated by cytokines present in the inflammatory environment of inflammatory bowel disease (IBD).

Intraperitoneally applied gentamicin increases collagen content and mechanical stability of colon anastomosis in rats

BACKGROUND

Anastomotic leakage remains a serious complication in colorectal surgery, and is being caused by a multitude of factors. Recent reports reveal changes of the extracellular matrix as risk factors as well as gentamicin as a potential agent to influence wound healing. This experimental study was initiated to investigate the influence of intraperitoneally applied gentamicin on colonic anastomotic wound healing and in particular on mechanical stability, overall collagen content and collagen type I/III ratio.

MATERIALS AND METHODS

Sixty Sprague Dawley rats were randomized to one of two groups. In each animal, a standard transverse colonic end-to-end anastomosis was performed. Immediately postoperative, either 5 ml gentamicin (1 ml/kg bodyweight) or NaCl 0.9% was applied intraperitoneally. On postoperative days 3, 5, and 14, ten of the animals in each group were sacrificed. Measurements of the anastomosis bursting pressure were performed on postoperative days 3 and 5. At each explantation time, the collagen per protein ratio, the collagen types I/III ratio, and both the expression of MMP-2, -9, and Ki67 were analyzed.

RESULTS

None of the animals died. None of the rats exhibited clinical evidence of anastomotic leakage. The bursting strength in the gentamicin group was significantly elevated on postoperative day 5. Both the overall collagen content and the collagen type I/III ratio in the gentamicin group were significantly increased 3, 5, and 14 days postoperatively compared to the control group. The expression of MMP-9 was significantly elevated in the gentamicin group both 3 and 5 days postoperatively. In contrast, there were no significant differences in the expression of MMP-9 14 days postoperatively. All investigated samples demonstrated positive staining for MMP-2 and Ki67 without statistically significant differences at any term, respectively.

CONCLUSIONS

The present data confirm that intraperitoneally applied gentamicin is able to enhance healing and stability of colonic anastomosis due to an increase of both the overall collagen content and collagen type I/III ratio.

Barrett's esophagus and the increasing role of endoluminal therapy

Barrett's esophagus, or the presence of specialized intestinal mucosa in the esophagus that has a malignant potential, has experienced a rapid increase in diagnosis and prevalence over the past few decades. Once thought to progress to adenocarcinoma in an orderly sequence of increasing dysplasia, recent data suggest the process can be more random. In combination with targeted surveillance endoscopy, recent improvements in technology have aided endoluminal therapy in becoming a cost-effective adjunct to medication. When used in combination, in particular, these ablative therapies have become suitable, if not preferable, alternatives to surgery in many patients.

Matrix metalloproteinase-9 and metalloproteinase-2 activity and expression is reduced by melatonin during experimental colitis

Matrix metalloproteinases (MMPs) are associated with matrix turnover in both physiological and pathological conditions. Several data indicate that MMPs play an important role in the pathogenesis of colitis. Various evidence has documented that the pineal secretory product melatonin exerts an important anti-inflammatory effect in different experimental models including colitis. However, no reports are available on the relationship between the activity and expression of MMPs and anti-inflammatory effect of melatonin. The aim of the present study was to evaluate whether melatonin prevents the experimental colitis in rats by regulating MMP-9 and MMP-2 activity and expression. Colitis was induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). Four days after DNBS administration, colon TNF-alpha production was associated with colon damage. Biochemical methods and zymography were used to analyse MMP-9 and MMP-2 activities in colon tissues from DNBS-injured rats. Our studies reveal that melatonin prevented colon injury and lipid peroxidation in rats at 4 days after DNBS-induced colitis. Melatonin also reduced proMMP-9 and MMP-2 activities that were induced in the colon tissues by DNBS administration. Reduced MMP-9 and MMP-2 activities were associated with reduced expression of TNF-alpha. We conclude that melatonin's ability to reduce DNBS-induced colon injury in rats is related to a reduction in proMMP-9 and MMP-2 activities and expression.

Effects of nanocrystalline silver (NPI 32101) in a rat model of ulcerative colitis

Nanocrystalline silver (NPI 32101) has been demonstrated to have antimicrobial and anti-inflammatory properties. The purpose of this study was to assess the effect of NPI 32101 in a rat model of ulcerative colitis and the possible mechanisms of action of the effects observed. NPI 32101, 4 mg/kg intracolonically or 40 mg/kg orally, significantly reduced colonic inflammation compared to the placebo and no-treatment groups. Sulfasalazine (100 mg/kg), either intracolonically or orally, also reduced colonic inflammation. NPI 32101 significantly suppressed the expression of matrix metalloproteinase (MMP)-9, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-12, whereas sulfasalazine suppressed MMP-9, IL-1beta, and TNF-alpha, but not IL-12, compared to placebo. MMP-9 activity was reduced by NPI 32101 and sulfasalazine. NPI 32101 administered intracolonically or orally decreases ulcerative colitis in a rat model and is as effective as sulfasalazine. NPI 32101 treatment suppresses the expression and activity of MMP-9 and the expression of TNF-alpha, IL-1beta, and IL-12, mechanisms by which NPI 32101 may exert its anti-inflammatory effects. NPI 32101 may have therapeutic potential for treatment of ulcerative colitis.

Transient profound mesenteric ischemia strongly affects the strength of intestinal anastomoses in the rat

PURPOSE

Experimental data suggest that transient preoperative ischemia and reperfusion may compromise anastomotic strength. However, data on this subject are equivocal, in particular as to the onset and duration of this effect. This study was designed to comprehensively characterize the effects of profound transient intestinal ischemia on anastomotic healing during the first postoperative week.

METHODS

Ischemia was induced in rats by clamping both the superior mesenteric artery and ileal branches for 30 minutes. Immediately after declamping, anastomoses were constructed in both terminal ileum and descending colon. After three, five, or seven days, both bursting pressure and breaking strength were measured. Anastomotic collagen content, gelatinase activity, and histology were analyzed.

RESULTS

Anastomotic leakage rate was 13 percent in ischemia-reperfusion group and 0 percent (P=0.02) in controls. The breaking strength in ileum remained significantly (P<0.05) lower in the ischemic groups than in the control groups at all time points. Bursting pressure in the ileum was not significantly different between ischemic and control groups at either of the time points measured. However, at Day 7 the bursting site was significantly more frequent within the suture line in the ischemic groups. In the colon, at Day 3 the bursting pressure was 35 percent lower in the ischemic group than in the control group (P<0.05). Anastomotic collagen content and gelatinase activity were similar in ischemic and control groups.

CONCLUSIONS

Transient profound splanchnic ischemia compromises anastomotic strength throughout the entire first postoperative week. This effect does not seem to be caused by impaired accumulation of wound collagen.

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.

Everolimus interferes with healing of experimental intestinal anastomoses

BACKGROUND

Although clinical data suggest its existence, little is known about the effect of rapamycin derivatives on wound repair. This study aims to delineate the influence of the mammalian target of rapamycin inhibitor everolimus on wound healing in the rat intestine.

METHODS

Four groups of 26 male Wistar rats received everolimus in daily oral dosages of 0 (controls), 0.5 (group E-0.5), 1.0 (group E-1), and 3.0 (group E-3) mg/kg every 24 hours, respectively, starting four hours before the operation until killing. After resection of 1-cm segments of colon and ileum, intestinal anastomoses were constructed. The animals were killed at days three or seven after operation. Wound healing was assessed by mechanical (bursting pressure, breaking strength), biochemical (collagen content, gelatinase activity), and histologic parameters.

RESULTS

No differences between groups were recorded for any of the parameters on day three. On day seven, a dose-dependent reduction in breaking strength (P<0.05) was measured. The largest effects were found in group E-3 in which the breaking strength was reduced by 56% and 73% in colonic and ileal anastomoses, respectively. A similar pattern was observed with the bursting pressure. Loss of strength was accompanied by a reduction in hydroxyproline content and by a lessened collagen deposition in the wound area but not by an increased gelatinase activity. No further histologic abnormalities were found.

CONCLUSION

Everolimus causes a massive reduction in anastomotic strength such as normally observed in the proliferative phase of repair. The data suggest this to be caused by an impaired deposition of collagen in the anastomotic area.

Effects of Two Conventional Preoperative Radiation Schedules on Anastomotic Healing in the Rat Colon

BACKGROUND

Preoperative radiotherapy (RT) is an increasingly popular form of adjunct therapy for rectal cancer; however, little is known about its effects on matrix metalloproteinase (MMP) expression in colonic anastomotic healing.

METHODS

Wistar rats were irradiated to a total dose of 25 or 40 Gy. Four days after the end of RT, an end-to-end colorectal anastomosis was performed. Animals were sacrificed at 1, 3, and 7 days after the anastomosis. A control group was studied similarly, but was not irradiated.

RESULTS

No significant differences were found in peritonitis rate and anastomotic complications. The average bursting pressure and breaking strength were only reduced significantly in the rats irradiated with 40 Gy. However, the concentration and the content of hydroxyproline in anastomotic tissues were unchanged. In irradiated rats, MMP-2 and MMP-9 were significantly increased at 40 Gy, but not at 25 Gy. On the other hand, 25-Gy irradiation induced a smaller increase in the levels of the tissue inhibitors of metalloproteinase-1 compared with the controls.

CONCLUSION

Anastomotic strength is adversely affected by high-dose fractionated preoperative RT. In contrast, preoperative RT at 25 Gy in five fractions over 5 days is safe with regard to the maintenance of wound strength in colorectal anastomosis.

Selective ablation of matrix metalloproteinase-2 exacerbates experimental colitis: contrasting role of gelatinases in the pathogenesis of colitis

The matrix metalloproteinases (MMPs), MMP-2 and MMP-9, share structural and substrate similarities and are up-regulated during human as well as animal models of inflammatory bowel disease. We recently demonstrated that epithelial-derived MMP-9 is an important mediator of inflammation and tissue damage in colitis. In this study, we examined the role of MMP-2 in acute colitis. Colitis was induced using two models, administration of dextran sodium sulfate (DSS) and Salmonella enterica subsp. serovar Typhimurium (S.T.). Bone marrow chimeras were performed using bone marrow cells from wild-type (WT) and MMP-2(-/-) mice. Colitis was evaluated by clinical symptoms, myeloperoxidase assay, and histology. MMP-2 protein expression and activity were up-regulated in WT mice treated with DSS or S.T. MMP-2(-/-) mice were highly susceptible to the development of colitis induced by DSS (or S.T.) compared with WT. During inflammation, MMP-2 expression was increased in epithelial cells as well as in the infiltrating immune cells. Bone marrow chimera demonstrated that mucosa-derived MMP-2 was required for its protective effects toward colitis. Furthermore, we demonstrate that severe colitis in MMP-2(-/-) is not due to a compensatory increase in MMP-9. Finally, we show that MMP-2 regulates epithelial barrier function. In contrast to MMP-9, mucosa-derived MMP-2 may be a critical host factor that is involved in the prevention or cessation of the host response to luminal pathogens or toxins, an important aspect of healing and tissue resolution. Together, our data suggest that a critical balance between the two gelatinases determines the outcome of inflammatory response during acute colitis.

Action of matrix metalloproteinases at restricted sites in colon anastomosis repair: an immunohistochemical and biochemical study

BACKGROUND

Dehiscence of colon anastomosis is a common, serious and potentially life-threatening complication after colorectal operation. In experimental models, impaired biomechanic strength of colon anastomoses is preventable by general inhibitors of matrix metalloproteinases (MMPs) and associated with collagen loss, which indicates a possible link between MMP-mediated collagen degradation and dehiscence. The precise localization of collagen degradation within the anastomotic area and the specific MMPs responsible are unknown.

METHODS

We have analyzed distinct zones within anastomoses using a novel microdissection technique for collagen levels, collagenolytic activity exerted directly by endogenous proteinases, and MMP-8 and MMP-9 immunoreactivity and their collagenolytic activity.

RESULTS

The most pronounced collagen loss was observed in the suture-holding zone, showing a 29% drop compared with adjacent micro-areas of 3-day-old anastomoses. Only this specific tissue compartment underwent a dramatic and significant increase in collagenolysis, amounting to a loss of 10% of existing collagen molecules in 24 hours, and was abolished by metalloproteinase inhibitors. The tissue surrounding suture channels was heavily infiltrated with CD68-positive histiocytes that expressed MMP-8 and to a lesser extent MMP-9. The collagenolytic effect of the interstitial collagenase MMP-8 was synergistically potentiated by the gelatinase MMP-9 when added to colon biopsies incubated in vitro.

CONCLUSIONS

The unique finding of this study was that the specific tissue holding the sutures of a colon anastomosis lost the most collagen presumably through induction and activation of multiple MMPs that may explain the beneficial effects of treatment with non-selective MMP antagonists.

Ação do extrato de Jatropha gossypiifolia L. (pião roxo) na cicatrização de anastomose colônica: estudo experimental em ratos

INTRODUÇÃO: A fitoterapia vem despertando crescente interesse na comunidade científica em relação às suas potenciais propriedades cicatriciais. Poucos são os estudos com metodologia científica existentes na literatura, constituindo-se assim um campo aberto para novas investigações. OBJETIVOS: Analisar a ação da Jatropha gossypiifolia L. (pião roxo) na cicatrização de anastomose colônica em ratos. MÉTODOS: Quarenta ratos Wistar foram submetidos à secção de toda a circunferência do cólon, sendo logo anastomosada com oito pontos separados usando fio monofilamentar de polipropileno 6-0. Aleatoriamente, os animais foram distribuídos em grupo controle (GC), contendo 20 ratos, nos quais foi administrada solução de cloreto de sódio a 0,9% por via intraperitoneal (1ml/kg) e grupo Jatropha (GJ), também com 20 nos quais foi administrado o extrato hidroalcoólico de Jatropha gossypiifolia L. por via intraperitoneal (1ml/kg). Cada um dos grupos foi subdividido em dois subgrupos de dez animais de acordo com a data de sacrifício, três e sete dias (GC3/ GC7 e GJ3/GJ7). Após o sacrifício foi retirada parte do cólon compreendendo 1 cm acima e abaixo da anastomose e submetido ao teste de resistência à insuflação de ar atmosférico. A seguir, foi aberta e retirada uma porção de 1,0 x 0,5cm de tamanho colocada em formol a 10% para análise histológica, na qual foram usadas a coloração de Hematoxilina-Eosina e o Tricrômico de Masson. RESULTADOS: Na avaliação do teste de pressão de ruptura entre os grupos houve significância estatística quando avaliados em relação à data de sacrifício Assim no terceiro dia a média no GC (25,4 mmHg.) e no GJ (76,4 mmHg.) estabeleceu p = 0.013, e no sétimo dia a média no GC (187,3 mmHg.) e no GJ (135,1 mmHg.) estabeleceu p = 0.014. Ao analisar as variáveis microscópicas entre os grupos no 3º dia, somente não houve diferença significativa nas variáveis edema e polimorfonucleares. Já no 7º dia todas as variáveis analisadas apresentaram diferença significativa. CONCLUSÕES: Na resistência mecânica pôde-se concluir que houve influência positiva da jatropha na aquisição de força na anastomose no terceiro dia. Entretanto, no sétimo dia o GC suplantou siginificativamente a pressão de ruptura obtida no GJ, sugerindo diminuição da ação da Jatropha em fase mais avançada da cicatrização. Na avaliação histológica pôde-se verificar avanço no processo inflamatório agudo no GJ3 em relação ao GC3, mantendo-se ainda mais intenso na fase crônica quando comparados os dois grupos no sétimo dia.

Targeted deletion of metalloproteinase 9 attenuates experimental colitis in mice: central role of epithelial-derived MMP

BACKGROUND & AIMS

There is mounting evidence that matrix metalloproteinases are the predominant proteinases expressed in the gut mucosa during active inflammatory bowel disease. We investigated the role of metalloproteinase 9 (MMP-9), a secreted gelatinase that is consistently up-regulated in both animal models and human inflammatory bowel disease and is associated with disease severity, in the pathogenesis of colitis by using mice containing a targeted deletion of the MMP-9 gene.

METHODS

Dextran sodium sulfate-induced colitis and Salmonella typhimurium-induced enterocolitis were used as animal models to study colitis.

RESULTS

MMP-9 activity and protein expression were absent from normal colonic mucosa but were up-regulated during experimental colitis. MMP-9-/- mice exposed to dextran sodium sulfate or salmonella had a significantly reduced extent and severity of colitis. Immunohistochemical studies showed that MMP-9 was localized to epithelial cells and granulocytes during active colitis. The immune response to systemic administration of Salmonella typhimurium was not affected in MMP-9-/- mice. Neutrophil transmigration studies and bone marrow chimeras showed that neutrophil MMP-9 is neither required for its migration nor sufficient to induce tissue damage during colitis and that epithelial MMP-9 is important for tissue damage. MMP-9 inhibited cell attachment and wound healing in the model intestinal epithelial cell line, Caco2-BBE.

CONCLUSIONS

Taken together, our data suggest that MMP-9 expressed by epithelial cells may play an important role in the development of colitis by modulating cell-matrix interaction and wound healing. Thus, strategies to inhibit MMP-9 may be of potential therapeutic benefit.

Changes in gelatinase activity in the gastrointestinal tract after anastomotic construction in the ileum or colon

PURPOSE

The strength of the uninjured and anastomosed intestinal wall is determined by its submucosal connective tissue. Matrix degradation by matrix metalloproteinases may result in loss of strength. It is known that anastomotic construction leads to up-regulation of matrix metalloproteinase activity in the wound area, but no quantitative data are available as to the extent of this effect throughout the intestinal wall. This study was designed to quantitate changes in gelatinolytic activity in the intestine after anastomotic construction in the ileum or colon.

METHODS

An anastomosis was constructed in the distal ileum or distal colon of rats, and animals were killed after one or three days. Tissue samples (5 mm) were collected containing the suture line, its adjacent segments (2- x 5-mm in both directions) and at nine other, more distant, sites throughout the gastrointestinal tract. Similar samples were collected from nonoperated control rats. All samples were analyzed by quantitative gelatin zymography.

RESULTS

In control rats, the most prominent gelatinolytic activities were found at 80 kDa, thought to represent a nonspecific proteolytic activity, 60 kDa and 50 kDa, representing the proform and active form of matrix metalloproteinase-2, respectively. Activities were higher in the small bowel than in the large bowel. Anastomotic construction led to massive up-regulation of an activity at 105 kDa, and its dimer, believed to represent promatrix metalloproteinase-9. Matrix metalloproteinase-2 remained unaffected, whereas the activity of the 80 kDa protein was significantly (P < 0.05) reduced. Significantly increased matrix metalloproteinase-9 activity was found in the actual anastomotic segments and in the immediately adjacent tissue. Matrix metalloproteinase-9 activities in the anastomotic segments were highest at Day 1 in the ileum and at Day 3 in the colon. Anastomotic construction in the ileum or colon did not lead to any significant changes of any gelatinolytic activity at the more distant sites in the bowel wall.

CONCLUSIONS

Up-regulation of gelatinase activity after anastomotic construction in the intestine is caused by matrix metalloproteinase-9. Because the effect is local and not systemic, unwanted matrix degradation at distant sites seems unlikely.

No detrimental effects of repeated laparotomies on early healing of experimental intestinal anastomoses

BACKGROUND

Little is known about the impact of repeated laparotomies on intestinal anastomotic healing. While experimental data are completely lacking, the sparse data available from clinical studies report high anastomotic failure rates, suggesting a negative effect in this respect. Since the unequivocal determination of such an effect may have important consequences for choosing the optimal treatment strategy for patients suffering from intra-abdominal infection, an experimental study has been performed in an established rodent model.

METHODS

Intestinal anastomoses were constructed in healthy Wistar rats (ileal and colonic anastomoses) or 24 h after peritonitis was induced by caecal ligation and puncture (colonic anastomosis only). Rats were then scheduled to undergo no, one (after 24 h) or two relaparotomies (after 24 and 48 h). Anastomotic strength was assessed 3 and 5 days after anastomotic construction. On the third post-operative day anastomotic hydroxyproline levels, matrix metalloproteinase activity and myeloperoxidase activity were measured.

RESULTS

No negative impact of repeated laparotomies was measured on any of the parameters measured. Under non-infectious conditions even an improvement in breaking strength (+48%, p=0.017) but not bursting pressure was found after two relaparotomies, but only in the ileum on the third post-operative day.

CONCLUSIONS

In this experimental setting, early anastomotic healing is not adversely affected by repeated laparotomies.

Effects of mechanical tension on matrix degradation by human periodontal ligament cells cultured in collagen gels

BACKGROUND

Periodontal ligament (PDL) cells are thought to play a crucial role in the remodelling of periodontal tissues during orthodontic tooth movement.

OBJECTIVE

The objective of this study was to analyse the effects of mechanical tension on matrix degradation by PDL cells cultured in collagen gels.

METHODS

The gels were prepared free-floating or attached to the culture wells and cultured for up to 22 d. In free-floating gels very little mechanical tension is generated within the matrix, whereas in attached gels tension is highly increased.

RESULTS

At d 8, free-floating gels had contracted to 2% of their original wet weight. Attached gels had contracted to only 40%, but by d 15 all gels had spontaneously detached from the wells and had contracted rapidly. The collagen content of free-floating gels had decreased to 30% of the initial value at d 22. Collagenase activity was detected in the culture media of the free-floating gels and the presence of matrix metalloproteinases (MMPs) 2 and 9 was shown by zymography. In addition, histological sections showed matrix degradation around the cells. This shows that ligament cells in free-floating gels are actively resorbing the collagen matrix. The collagen content of attached gels did not change during the first 8 d but, after detachment, it rapidly decreased to 2%. Therefore, mechanical tension seems to prevent degradation of the matrix. In contrast, relaxation of the tension enhances the resorptive activity.

CONCLUSIONS

The sensitivity of PDL cells to mechanical tension may be essential for the remodelling of periodontal tissues and their adaptation to physiological and orthodontic forces.

Colonic anastomotic strength and matrix metalloproteinase activity in an experimental model of bacterial peritonitis

BACKGROUND

Clinical studies report conflicting results on the safety of primary intestinal anastomoses in the presence of peritonitis, and comprehensive experimental data are lacking. The present study investigated whether the strength of experimental colonic anastomoses is affected if surgery is performed in the presence of pre-existing bacterial peritonitis.

METHODS

Colonic anastomoses were constructed in Wistar rats 24 h after caecal ligation and puncture or a sham procedure. Anastomotic strength was assessed by measuring breaking strength and bursting pressure during the first 5 days after operation. Anastomotic hydroxyproline levels were measured and matrix metalloproteinase (MMP) activity was analysed by quantitative gelatin zymography.

RESULTS

Anastomotic strength was lowered in the presence of bacterial peritonitis but in a minor and transient way. The breaking strength was lower only immediately after construction of the anastomosis (- 15 per cent, P = 0.011) and the bursting pressure only on the third postoperative day (- 33 per cent, P = 0.038); no anastomotic dehiscence was observed. At 3 days after operation increased levels of MMP activity were observed but anastomotic hydroxyproline content was not affected by bacterial peritonitis.

CONCLUSION

The influence of bacterial peritonitis on the development of anastomotic strength is limited. This experimental finding lends support to recent clinical studies that have demonstrated the feasibility of constructing a primary anastomosis under these conditions.

Repair of full-thickness bowel injury

OBJECTIVE

Colon surgery is more and more often performed in complex situations such as after trauma, under immunosuppression, or in the elderly. Even under optimal conditions, anastomosis fails in certain situations. The objective of this study was to demonstrate the normal phases of bowel healing and to review the local and systemic factors affecting healing with special attention to critical care variables such as major surgery, acute hemorrhage, and infections.

DATA SOURCE

MEDLINE cited and/or published articles.

DESIGN

Review analysis.

RESULTS

Colon healing is a structured cascade of different phases that can be affected by a multitude of local (infection, ischemia) and systemic (diabetes, malnutrition, anemia, hypothermia, trauma) factors. The normal phases of repair, the resulting bursting pressure as an experimental index of healing, and the available published data on local and systemic factors affecting healing are summarized.

CONCLUSION

Several local and systemic factors negatively affect bowel healing; there is still a small portion of patients who fail to heal, suggesting that intrinsic factors need to be analyzed.

Doxycycline improves wound strength after intestinal anastomosis in the rat

BACKGROUND

The strength of intestinal anastomoses is relatively low in the first days after operation, possibly as a result of localized degradation of the supporting matrix by enzymes from the matrix metalloproteinase (MMP) family. The aim of this study was to examine whether doxycycline, a drug known to inhibit MMP activity, could enhance anastomotic strength.

METHODS

Male Wistar rats received anastomoses in both ileum and colon. From the day before operation onwards, animals were treated daily with doxycycline (orally or subcutaneously) in a dose of 10 mg/day or with saline only. Rats were killed 1, 3, or 5 days after operation, and anastomotic bursting pressure and breaking strength were measured. At day 3, anastomotic hydroxyproline levels were measured, MMP (gelatinase) activity was analyzed by gelatin zymography, and anastomotic histology was examined.

RESULTS

Doxycycline enhanced wound strength, but only at day 3, when it was at its lowest. Subcutaneous administration of 10 mg/day increased median colonic and ileal breaking strength by 27% (P =.0019) and 104% (P =.0376), respectively. Colonic bursting pressure was increased by 93% (P =.0002). Wound histology was similar in experimental and control groups.

CONCLUSIONS

Administration of doxycycline enhances anastomotic strength and should be investigated further as a means to preserve anastomotic integrity.

Extracellular matrix remodeling and metalloproteinase involvement during intestine regeneration in the sea cucumber Holothuria glaberrima

The sea cucumber, Holothuria glaberrima, has the capacity to regenerate its internal organs. Intestinal regeneration is accomplished by the thickening of the mesenteric border and the invasion of this thickening by mucosal epithelium from the esophagus and the cloaca. Extracellular matrix (ECM) remodeling has been associated with morphogenetic events during embryonic development and regeneration. We have used immunohistochemical techniques against ECM components to show that differential changes occur in the ECM during early regeneration. Labeling of fibrous collagenous components and muscle-related laminin disappear from the regenerating intestine and mesentery, while fibronectin labeling and 4G7 (an echinoderm ECM component) are continuously present. Western blots confirm a decrease in fibrous collagen content during the first 2 weeks of regeneration. We have also identified five 1,10-phenanthroline-sensitive bands in collagen gelatin zymographs. The gelatinolytic activities of these bands are enhanced during early stages of regeneration, suggesting that the metalloprotease activity is associated with ECM remodeling. Inhibition of MMPs in vivo with 1,10-phenanthroline, p-aminobenzoyl-Gly-Pro-D-Leu-D-Ala hydroxamate or N-CBZ-Pro-Leu-Gly hydroxamate produces a reversible inhibition of intestinal regeneration and ECM remodeling. Our results show that significant changes in ECM content occur during intestine regeneration in the sea cucumber and that the onset of these changes is correlated to the proteolytic activities of MMPs.

Role of CXC chemokines in the enhancement of LPS-induced neutrophil accumulation in the lung of mice by dexamethasone

Lipopolysaccharide (LPS)-induced multiple organ injury was mediated in part by a transcription factor, nuclear factor-kappaB (NF-kappaB). Mice were pretreated with dexamethasone (DEX), an inhibitor of NF-kappaB activation, to elucidate its effects on LPS-induced early responses in vivo. Early responses measured 1 h after intraperitoneal LPS administration at a dose of 1 mg/kg were (1) neutrophil accumulation in the tissues, (2) neutrophil degranulation, and (3) protein and mRNA expressions of tumor necrosis factor-alpha (TNF-alpha) and ELR(+) CXC chemokines [macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC)]. Treatment with DEX before LPS administration suppressed NF-kappaB activation and plasma TNF-alpha levels almost to undetectable levels, but enhanced neutrophil accumulation and augmented MIP-2 levels in the lung. The suppression of plasma TNF-alpha levels by pretreatment with an anti-TNF-alpha antibody did not enhance LPS-induced neutrophil accumulation in the lung. These results demonstrate that the enhancement of LPS-induced neutrophil accumulation by DEX might be mediated by MIP-2 and not by TNF-alpha.

Perioperative matrix metalloproteinase inhibition therapy does not impair wound or anastomotic healing

Matrix metalloproteinases (MMPs) catalyze the degradation of collagen and extracellular matrix. They play a role in pathologic states including malignancy, in which they facilitate invasion and metastasis. MMP inhibition has been shown to block neoplastic invasion and improve survival in animal models of malignancy. Concern about the effects of MMP inhibitors on wound and anastomotic healing may limit their potential use in the perioperative period to prevent local and systemic showering of cancer cells from surgical manipulation. We sought to assess the safety of perioperative administration of an MMP inhibitor (BB-94) with respect to skin and bowel healing in a rat model. Absorption of BB-94 was confirmed through high-pressure liquid chromatography and mass spectroscopy of sera from treated animals. Bowel bursting pressure in all animals increased almost 10-fold between 4 and 14 days. Two-way analysis of variance showed no significant difference in bowel bursting pressure between control and treatment animals over time. There was a significant increase in the collagen content of skin specimens of all animals combined between 4 and 28 days. Similarly, all animals showed an increase in bowel collagen between 4 and 28 days. There was no significant difference in skin or bowel collagen concentrations between control and treatment animals over time. Perioperative treatment with MMP inhibition does not impair wound or enteric healing in a rat model of laparotomy and small bowel resection. MMP inhibitors are safe for use as adjuvant therapy after resection for cancer.

Regulation of matrix metalloproteinases in a model of colonic wound healing in a rabbit

PURPOSE

Matrix metalloproteinases occur in the colon at an anastomosis but not in the normal colon. Matrix metalloproteinase synthesis can be regulated by cytokines, for example interleukin-1 beta and growth factors, such as transforming growth factor beta and basic fibroblast growth factor. The aim of this study was to investigate the regulation of matrix metalloproteinases at an anastomosis by identifying the cell types that synthesize matrix metalloproteinases, examining factors that might regulate their synthesis, determining whether they occur in an active form, and assessing the effect of suture type on these parameters.

METHODS

An anastomosis was formed in the distal colon of rabbits using either polyglactin or polydioxanone and the animals were killed six hours or seven days later. The distribution of matrix metalloproteinases and cytokines and the cell types were assessed by immunohistochemistry. Matrix metalloproteinase-2, matrix metalloproteinase-3, and matrix metalloproteinase-9 were detected also by zymography.

RESULTS

Immunohistochemistry showed that matrix metalloproteinases were restricted to the suture line. Although zymography demonstrated that matrix metalloproteinase-2 was present mainly in an active form, matrix metalloproteinase-9 and matrix metalloproteinase-3 were present in the pro-form. The active form of matrix metalloproteinase-3 occurred more often in the polydioxanone-sutured rabbits. With the exception of matrix metalloproteinase-9, the matrix metalloproteinases were synthesized by fibroblasts. Interleukin-1 beta and transforming growth factor beta were more widespread than in the normal colon and were localized adjacent to the matrix metalloproteinases. Basic fibroblast growth factor was also more widespread postoperatively but occurred deeper in the anastomosis than the matrix metalloproteinases.

CONCLUSIONS

This study has shown that interleukin-1 beta and transforming growth factor beta may regulate the synthesis of the matrix metalloproteinases by fibroblasts and that minor differences that occur in the matrix metalloproteinase profile are dependent on the suture type.

Role of TGF-beta1, extracellular matrix, and matrix metalloproteinase in the healing process of the pancreas after induction of acute necrotizing pancreatitis using arginine in rats

INTRODUCTION

Pancreatic tissues are almost completely restored to normal after an attack of acute pancreatitis, once the cause of the disease is removed. Transforming growth factor (TGF)-beta and extracellular matrix (ECM) are known to play an important role in the process of wound healing in pathologic diseases. Tissue repair is a process regulated by a balance between synthesis and degradation of ECM.

AIMS

To elucidate the role of TGF-beta, ECM, and matrix metalloproteinase (MMP) in the process of regeneration occurring after acute necrotizing pancreatitis.

METHODOLOGY

Acute necrotizing pancreatitis was induced by intraperitoneal injection of 500 mg/100 g body weight of L-arginine in male Wistar rats. Expression of TGF-beta1 and ECM messenger RNA (mRNA) was determined by Northern blot analysis, and that of MMP-1 and MMP-2 mRNA was examined by the reverse transcription polymerase chain reaction (RT-PCR). Immunoreactivity for ECM components, TGF-beta1, and MMP-2 in the pancreas was assessed by using a monoclonal antibody.

RESULTS

TGF-beta1 mRNA expression reached a peak value on day 2.5, with a decrease on day 3, and reached the control level on day 7. Procollagen types III and IV and fibronectin mRNA reached a peak value on day 2.5, whereas the expression level of procollagen type I mRNA was maximal on day 3, and gradually decreased to control levels by day 7. MMP-2 mRNA was significantly elevated on day 3, and peaked on day 5, whereas MMP-1 mRNA levels did not change throughout the observation period. Immunoreactivity for MMP-2 was observed around disrupted acinar cells and interstitial spaces on day 3, and maximally on day 7. Immunoreactivity for fibronectin was detected around disrupted acinar cells and interstitial spaces. On day 7, it was less than on day 5 around disrupted acinar cells and interstitial spaces, whereas in the regenerated acinar cells, it was undetected.

CONCLUSION

Our results show that TGF-beta1 mRNA expression peaked earlier than that of ECM mRNA. Furthermore, increased level of the MMP-2 transcript was followed by disappearance of fibronectin. Our findings suggest that TGF-beta1 plays an important role in ECM production in the early phase of acute pancreatitis, and that MMP-2 is involved in the subsequent healing process.

Matrix metalloproteinases-2 and 9 do not play a role in the growth of preneoplastic liver lesions in F344 rats

Matrix metalloproteinases- (MMPs) 2 and 9 (gelatinases A and B) have been implicated in tumor invasion and metastasis, and recent studies have shown increased levels of these enzymes during recovery from partial hepatectomy (PH) in rats. F344 rats are highly susceptible to the growth of glutathione S-transferase 7-7- (GST 7-7) positive preneoplastic liver lesions promoted using the modified resistant hepatocyte (RH) protocol. Since the RH protocol consists of 2-acetylaminofluorene (2-AAF) followed by a PH, we reasoned that MMP-2 and -9 might be critical for the growth of lesions. Using gelatin zymography, we examined the expression of these enzymes in the livers of F344 rats treated with the RH protocol and sacrificed on Days 2, 4, 7, 14, and 21 after 2-AAF/PH. We found increases in both pro- and active MMP-2 and -9 over baseline levels, with the highest levels occurring on Day 7 post-PH. Also, a 54-kDa band, likely to be proMMP-1, was elevated in a pattern similar to MMP-2 and -9. In contrast to F344 rats, identically treated Copenhagen rats that are highly resistant to promotion of liver lesion growth using the RH protocol had significantly lower levels of proMMP-1 and -2. To test the importance of these MMPs to the growth of liver lesions, F344 rats that had been initiated with diethylnitrosamine were treated using the RH protocol. They then received either the MMP inhibitor batimastat (30 mg/kg, intraperitoneally) or vehicle alone daily from Day 3 to 20 post-PH and were sacrificed on Day 21. There were no differences in the percentage of liver volume occupied by GST 7-7-positive lesions (19.1 +/- 4.84 vs 19.4 +/- 3.31, treated versus vehicle, mean +/- SEM) or liver weight as a percentage of body weight (4.11% +/- 0.15 vs 4.07% +/- 0.18, treated versus vehicle, mean +/- SEM) between the treated and control groups. Treatment of rats with batimastat clearly did not affect lesion growth or liver regeneration following the RH protocol. These results suggest that increases in gelatinase expression during the RH protocol are a result of the promotional stimulus rather than a mechanism by which 2-AAF/PH causes lesion growth.

The role of up-regulated serine proteases and matrix metalloproteinases in the pathogenesis of a murine model of colitis

Proteinases are important at several phases of physiological and pathological inflammation, mediating cellular infiltration, cytokine activation, tissue damage, remodeling, and repair. However, little is known of their role in the pathogenesis of inflammatory bowel disease. The aim of this study was to assess the role of tissue proteases in a mouse model of colitis. Proteolytic activity was analyzed, using gel and in situ zymography, in colonic tissues from severe combined immunodeficient mice with colitis induced by transfer of CD4(+) T lymphocytes. Serine proteinase levels increased in colitic tissue, with major species of 23 kd, 30 kd, and 45 kd. Co-migration and inhibition studies indicated that the 23-kd proteinase was pancreatic trypsin and that the 30-kd species was neutrophil elastase. Matrix metalloproteinase (MMP)-9 expression, and MMP-2 and MMP-9 activation, was elevated in colitic tissues. Proteinase levels followed a decreasing concentration gradient from proximal to distal colon. Proteolysis was localized to infiltrating leukocytes in diseased severe combined immunodeficient mice. Transmural inflammation was associated with serine proteinase and MMP activity in overlying epithelium and with marked subepithelial proteolytic activity. The results demonstrate a clear elevation in the levels and activation of proteases in colitis, potentially contributing to disease progression through loss of epithelial barrier function.

Coexpression of integrin alpha(v)beta3 and matrix metalloproteinase-2 (MMP-2) coincides with MMP-2 activation: correlation with melanoma progression

Tumor cell invasion and metastasis formation depend on both adhesive and proteolytic mechanisms. Previous studies have shown that expression of matrix metalloproteinase-2 and integrin alphavbeta3 correlate with melanoma progression. Recently, direct binding of matrix metalloproteinase-2 to alpha(v)beta3 was implicated in presenting activated matrix metalloproteinase-2 on the cell surface of invasive cells. In this study we investigated this, using the highly metastatic, alpha(v)beta3-negative melanoma cell lines MV3 and BLM, their beta3-transfected alpha(v)beta3 expressing counterparts, xenografts derived from these cell lines, and fresh human cutaneous melanoma lesions comprising all stages of melanoma progression. Expression and activation status of matrix metalloproteinase-2 were studied by reverse transcription-polymerase chain reaction, immunohistochemistry, western blotting, and zymographic analysis, respectively. Matrix metalloproteinase-2 protein expression in vitro was similar in both alpha(v)beta3-negative and alpha(v)beta3-positive cell lines Remarkable differences, however, exist in the localization of inactive and active matrix metalloproteinase-2. Soluble active matrix metalloproteinase-2 was detectable only in the conditioned medium of alpha(v)beta3-negative cell lines and undetectable in the alpha(v)beta3-positive cell lines. Conversely, active matrix metalloproteinase-2 was present exclusively on the cell surface of the alpha(v)beta3 expressing transfectants. Western blot analysis of other components that are involved in matrix metalloproteinase-2 activation showed that processing of proMT1-matrix metalloproteinase to the activated form was enhanced in beta3 transfectants, whereas secretion of tissue inhibitor of metalloproteinase-2 was decreased. In vivo, the presence of functionally active matrix metalloproteinase-2 was significantly higher in xenografts derived from the alpha(v)beta3 expressing MV3 and BLM cell lines. In human cutaneous melanoma lesions, neither matrix metalloproteinase-2 nor integrin alpha(v)beta3 is detectable in melanoma in situ as determined by immunohistochemistry. In contrast, the number of matrix metalloproteinase-2-positive and alphavbeta3-positive tumor cells was clearly increased in primary melanomas, and melanoma metastases. Double staining experiments and confocal laser microscopy demonstrated that the percentage of cells coexpressing matrix metalloproteinase-2 and alpha(v)beta3 increased in advanced primary melanomas and melanoma metastases. In addition, zymography showed that functionally active matrix metalloproteinase-2 was frequently present in melanoma metastases. In these lesions a high proportion of matrix metalloproteinase-2- and alphavbeta3-double-positive melanoma cells were detectable. Our study demonstrates that the presence of activated matrix metalloproteinase-2 correlates with expression of alpha(v)beta3 in human melanoma cells both in vitro and in vivo, and also in fresh human melanoma lesions. These findings strongly suggest that co-ordinated expression of both factors may be required for melanoma cell invasion and metastasis formation.