Role of matrix metalloproteinases in healing of colonic anastomosis

Recurring Anastomotic Leak-A Prospective Clinicopathological Investigation of a Distinct Disease Pattern

BACKGROUND

Intestinal anastomotic insufficiency (AI) is a common problem in visceral surgery associated with overexpression of matrix metalloproteinases (MMPs). In some patients it occurs more than once. The etiology of recurring anastomotic insufficiency (RAI) is not understood yet and should be addressed as an independent disease entity.

MATERIALS AND METHODS

Thirty nine consecutive patients with AI were treated at our university center and were included in this prospective study. Clinical data were evaluated by correlative statistical analysis to identify independent risk factors for RAI. Patients were divided in two groups: 18 patients had a single operative revision until restoration (group SAI), and 21 patients had two or more revisions (group RAI). Anastomotic tissue samples as well as untouched bowel wall were collected during reoperations for analysis of MMPs and tissue inhibitor of metalloproteinases (TIMP2). Clinical data were correlated with pathological observations.

RESULTS

Significant differences of clinical and molecular pathological data were found between the two groups. Transfusion of red blood cells until the first reoperation and alcohol abuse led to RAI and were the only independent risk factors for RAI in multivariate analysis. Overexpression of MMP-8, -9, and -13 in anastomotic tissue correlated with the administration of red blood cells during initial operation. Reduced expression of TIMP2 was frequent in nearly all patients without differences throughout the subgroups.

CONCLUSIONS

RAI seems to have an independent disease pattern. Transfusion of blood products is not only a known risk factor for AI but seems to significantly disturb the anastomotic healing process leading to RAI.

Assessment of MMP-2/-9 expression by fluorescence endoscopy for evaluation of anastomotic healing in a murine model of anastomotic leakage. PLoS One. 2018;13:e0194249. [PMID: 29566031 PMCID: PMC5863981 DOI: 10.1371/journal.pone.0194249]

BACKGROUND

Disturbance of intestinal wound closure leads to insufficient anastomotic healing and is associated with considerable morbidity following colorectal resections. Matrix metalloproteinases (MMPs) play a crucial role in regulation of wound closure. Here fluorescence endoscopy was evaluated for assessment of MMP-2/-9 expression during failed intestinal anastomotic healing.

METHODS

Distal colonic anastomoses were performed as a model for disturbed healing in 36 Balb/c mice. Healing was evaluated endoscopically, macroscopically, and histologically after 1, 3 and 5 days. For detection of MMP-2/-9 expression fluorescence endoscopy (FE) was used following i.v.-administration of a Cy5.5-labeled MMP-2/-9 specific tracer. FE was complemented by quantification of the fluorescence signal using the MS-FX PRO Optical Imaging System. An overall leakage score was calculated and correlated with the results of FE.

RESULTS

With increasing incidence of anastomotic leakage from POD1 (17%) to POD5 (83%) the uptake of the MMP tracer gradually increased (signal-to-noise ratio (SNR), POD1: 17.91 ± 1.251 vs. POD3: 30.56 ± 3.03 vs. POD5: 44.8 ± 4.473, P<0.0001). Mice with defective anastomotic healing showed significantly higher uptake compared to non-defective (SNR: 37.37± 3.63 vs. 26.16± 3.635, P = 0.0369). White light endoscopy and FE allowed evaluation of anastomotic healing and visualization of mucosal MMPs in vivo. Using FE based detection of MMPs in the anastomosis, an overall positive predictive value of 71.4% and negative predictive value of 66.6% was calculated for detection of anastomotic leakage.

CONCLUSION

During disturbed anastomotic healing increased expression of MMP-2/-9 was observed in the anastomotic tissue. Fluorescence endoscopy for detection of MMP-2/-9 during the healing process might be a promising tool for early identification of anastomotic leakage.

Autologous adipose-derived stem cell sheets enhance the strength of intestinal anastomosis

Objective

Adipose-derived stem cells (ASCs) are capable of multiple differentiation pathways, imparting immunomodulatory effects, and secreting factors that are important for wound healing. These characteristics can be exploited to decrease the incidence of anastomotic leakage.

Methods

In order to delay local wound healing at the anastomotic site, we induced ischemia in a portion of porcine small intestine by ligating vessels. Then, we injected mitomycin C into the serosa of the small intestine above the ligated vessels. Anastomotic sites were created by 2 cm incisions made in the opposite mesenteric area. ASCs were isolated from the porcine subcutaneous fat tissues and expanded under culture conditions. ASCs were trypsinized and seeded on temperature-responsive dishes and cultured to form confluent sheets. Three ASC sheets were transplanted onto the serous membrane after suturing. The extent of anastomotic wound healing was evaluated by bursting pressure, hydroxyproline content, and mRNA expression of collagen-1 alpha1 and collagen-3 alpha1.

Results

We found that transplantation of ASC sheets increased anastomotic site bursting pressure. Additionally, transplantation of ASC sheets increased the hydroxyproline content of the anastomoses. Furthermore, transplantation of ASC sheets increased mRNA expression of collagen-1 alpha1 and collagen-3 alpha1.

Conclusions

Our findings showed that transplantation of autologous ASC sheets enhanced collagen synthesis and anastomotic strength. Further studies are necessary to identify substances that, in combination with ASC sheets, might enhance collagen synthesis and healing in sites of anastomosis.

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Transplantation of adipose-derived stem cell (ASC) sheets after intestinal anastomosis stimulated collagen synthesis and improved anastomotic strength.

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Paracrine effects of the growth factors released by the ASC sheets might contribute to healing at the anastomotic site and stimulate the fibroblast and the collagen synthesis.

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This new approach might be a feasible and promising strategy to prevent anastomotic leakage.

Comparison of effects of the tacrolimus and cyclosporine A on the colon anastomosis recovery of rats

Purpose

This study aims to examine and compare the effects of immunosuppressant cyclosporine A (CsA) and tacrolimus (TAC) on colon anastomosis recovery.

Methods

Forty rats were randomly divided into 4 groups. The 4 groups were determined as follows: control group; sham group, given %0.09 NaCl; TAC group, given 0.5 mg/kg/day tacrolimus; and CsA group, given 5 mg/kg/day CsA. A 6-cm midabdomen incision was performed on the rats. An incision of all layers on the right colon was performed. Then anastomosis was undertaken. Laparotomy was performed on the seventh day postoperation. The colon bursting pressures were evaluated, histopathological examinations were undertaken, and E-cadherin expression and tissue hydroxyproline levels were evaluated.

Results

Statistically significant differences were observed among bursting pressures of the groups (P < 0.001). The value was significantly low in TAC and CsA groups when compared to control and sham groups (P < 0.05). The tissue hydroxyproline levels were significantly low in TAC group compared to control group (P = 0.03). Fibroblast density and neovascularization were significantly greater in the control group compared to the TAC group (P < 0.05). Levels of collagen had decreased significantly in TAC group compared to other groups (P < 0.05).

Conclusion

Our study showed that TAC may have a negative effect of colon anastomosis recovery. The lowest anastomosis bursting pressure was detected in TAC group. Also, collagen, hydroxyproline, fibroblast, neovascularization and E-Cadherin levels were comparatively lower in TAC group. CsA did not cause any significant changes to tissue hydroxyproline, collagen, fibroblast, and E-Cadherin levels.

Effects of metoclopramide on the expression of metalloproteinases and interleukins in left colonic anastomoses. An experimental study

PURPOSE

To evaluate the effects of metoclopramide on metalloproteinases (MMP) and interleukins (IL) gene expression in colonic anastomoses in rats.

METHODS

Eighty rats were divided into two groups for euthanasia on the 3rd or 7th postoperative day (POD), then into two subgroups for sepsis induction or not, and then into subgroups to receive either metoclopramide or saline solution. Left colonic anastomosis were performed and then analyzed.

RESULTS

On the 3rd POD, metoclopramide was associated with increased expression of MMP-1a, MMP-13, and TNF-α. On the 7th POD, the transcripts of all MMPs, TNF-α, IL-1β, IFN-γ, and IL-10 of the treated animals became negatively modulated. In the presence of sepsis, metoclopramide did not change MMPs and decreased IL-6, IL-1β, IFN-γ and IL-10 gene expression on the 3rd POD. On the 7th POD, increased expression of all MMPs, IFN-γ and IL-10 and negative modulated TNF-α and IL-6 gene expression.

CONCLUSION

Administration of metoclopramide increased metalloproteinases and interleukins gene expression on the 3rd postoperative day and negatively modulated them on the 7th POD. In the presence of abdominal sepsis, metoclopramide did not change MMPs and decreased ILs gene expression on the 3rd POD. On the 7th POD, the drug increased expression of all MMPs.

Oral mucoceles: a clinical, histopathological and immunohistochemical study

The aim of study was to evaluate the clinicopathological features of oral mucoceles and the immunohistochemical expression of cellular and extracellular matrix components in these lesions. One hundred cases of oral mucoceles were examined for clinicopathological features. The expression of mast cell tryptase, CD68, MMP-1 (matrix metalloproteinase-1), MMP-9 (matrix metalloproteinase-9) and CD34 was investigated immunohistochemically in 32 cases. The lesions arose as nodules or blisters of variable color. The mean age was 23.2 years and a higher male frequency was observed. The most common locations were the lower lip (92%), followed by the floor of the mouth (7%), and palate (1%). The lesion size ranged from 0.4 to 3.0cm. Unusual histopathological findings as superficial mucoceles (n=16, 16%), pseudopapillary projections (n=3, 3%), epithelioid histiocytes (n=4, 4%), multinucleated giant cells (n=1, 1%) and myxoglobulosis (n=9, 9%) were also seen. Mast cells and CD68-positive macrophages, MMP-1, MMP-9 and CD34-positive blood vessels were seen in all cases. A significant association was seen between mast cells and MMP-1 (p=0.03) and between macrophages and MMP-1 (p=0.01). This study provided important insight into the demographic and histopathological occurrence of oral mucoceles. The tissue remodeling seen in these lesions mainly involved the migration and interaction of mast cells, macrophages and MMP-1.

Anastomotic stability and wound healing of colorectal anastomoses sealed and sutured with a collagen fleece in a rat peritonitis model. Asian J Surg. 2014;37:35-45. [PMID: 23978425 DOI: 10.1016/j.asjsur.2013.07.008]

BACKGROUND/OBJECTIVE

Anastomotic insufficiency is associated with increased morbidity and mortality. A collagen fleece that supports anastomosis is effective for preventing anastomosis insufficiency. The objective of this study was to compare between the stability of sutured anastomoses and that of anastomoses sealed with a thrombin/fibrinogen-coated collagen fleece in a rat peritonitis model.

METHODS

In 72 male Wistar rats, peritonitis was induced with a specially prepared human fecal solution. Surgery at the rectosigmoid junction was performed 24-36 hours later. The different anastomotic techniques used were circular sutured anastomoses, semicircular sutured anastomosis and closure of the anterior wall with collagen patch, and complete closure with a collagen fleece. Bursting pressure, histology of anastomosis, mRNA expression of collagen types I and III, matrix metalloproteinase-13, and vascular endothelial growth factor (VEGF) were investigated after 24 hours, 72 hours, and 120 hours.

RESULTS

All animals developed peritonitis of comparable severity. There were no differences in bursting pressures between the three suture techniques after 24 hours, 72 hours, or 120 hours. Anastomoses sealed with a collagen fleece appeared to be slightly less stable only at 24 hours, whereas they appeared to be more stable than semisutured or fully sutured anastomoses at 72 hours and 120 hours. Sealing with a collagen fleece was associated with an increase in granulation tissue, higher mRNA levels for collagen types I and III, and higher VEGF compared to sutured anastomoses.

CONCLUSION

The use of a thrombin/fibrinogen-coated collagen fleece showed similar efficacy to conventional sutures in colorectal anastomoses in the presence of peritonitis inflammation, and may provide additional benefits due to an increase in mature granulation tissue.

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.

The role of matrix metalloproteinases in intestinal epithelial wound healing during normal and inflammatory states. J Surg Res. 2011;168:315-324. [PMID: 20655064 DOI: 10.1016/j.jss.2010.03.002]

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).

Effects of nuclear factor-κB inhibitors on colon anastomotic healing in rats

BACKGROUND

Nuclear factor (NF)-κB plays an essential role in inflammation. We tested this role by administering NF-κB-inhibitors into rats undergoing a well-established model of colonic anastomotic healing.

METHODS

Wistar rats underwent laparotomy, descending colonic transection, and handsewn reanastomosis. The animals were randomized to receive either a selective NF-κB inhibitor (parthenolide 0.5 mg/kg or resveratrol 0.5 mg/kg) or an equal volume of water by gavages before operation and then daily after surgery. Animals were sacrificed either immediately after anastomotic construction (d 0) or at the third, fifth, or seventh postoperative day.

RESULTS

Both parthenolide and resveratrol treatment led to early significant increases in plasma levels of IL-6. On d 7, hydroxyproline levels were significantly higher in the parthenolide and resveratrol groups. A similar pattern was observed with the bursting pressure. In contrast, gelatinase activity (MMP-2 and MMP-9 expression) was significantly higher in the control group on postoperative d 3. On d 3, expression of NF-κB activity was up-regulated in the anastomotic area. Both parthenolide and resveratrol completely attenuated NF-κB activity. Study groups also developed more marked inflammatory cell infiltration and collagen deposition on histology analysis.

CONCLUSIONS

Parthenolide and resveratrol significantly improved healing and mechanical stability of colonic anastomoses in rats during the early postoperative period. Both agents may be acting to accelerate the host reparative process as well as to enhance protection of the anastomotic wound bed.

The Role of Doxycycline as a Matrix Metalloproteinase Inhibitor for the Treatment of Chronic Wounds

Many chronic wounds fail to heal with conventional therapy, resulting in disability and impaired quality of life. New technologies using recombinant growth factors, autologous growth factors, or bioengineered skin—tissue substitutes have been shown to be effective, but these treatments are costly. An effective, low-cost treatment to improve healing of chronic wounds is needed. The molecular environment of chronic wounds, like many other chronic inflammatory diseases, contains abnormally high levels of proinflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-1β]) and matrix metalloproteinases (MMPs), which impair normal wound healing. In animal models and clinical studies of ulcerative diseases, doxycycline, an inexpensive and Food and Drug Administration (FDA)-approved antibiotic, appears to inhibit members of the MMP superfamily like MMPs and TNF-α-converting enzyme (TACE). This article provides an overview of the roles of MMPs and intrinsic tissue inhibitors of metalloproteinases (TIMPs) in wound healing and the damaging effects of chronically elevated levels of MMPSs in chronic wounds. It also explores the use of topical doxycycline, a synthetic MMP inhibitor (MMPI), to enhance healing of chronic wounds.

Influence of Pneumoperitoneum on Small Bowel Anastomoses: A Histological Analysis in the Rat Model

Laparoscopic techniques are increasingly applied for the treatment of diverse gastrointestinal diseases. With regard to reports of a pronounced decrease of intra-abdominal blood flow with increasing intra-abdominal pressure, the present study investigates the impact of pressure and gas type on ischemia in small bowel anastomoses in the rat model. Laparotomy and ileoileal anastomosis were performed in 39 male Sprague-Dawley rats. A CO2 or helium pneumoperitoneum of 3 mm Hg or of 6 mm Hg was maintained before and after anastomoses. Rats in the control group received no pneumoperitoneum. Animals were sacrificed after 5 d, and the anastomotic region was explanted for subsequent histopathological examinations. In hematoxylin and eosin (HE)-stained sections, the Chiu score, villi configuration, and number of goblet cells were analyzed. Proliferation (Ki67) and expression of a matrix metalloproteinase (MMP-8) were examined by immunohistochemistry. Mucosal damage according to the scoring system by Chiu, the number of goblet cells, the villus length, the proliferation (Ki67), and the submucosal expression of MMP-8 was similar in all groups. Our results suggest that within a certain range of pressures and time, laparoscopic assisted surgery using CO2 pneumoperitoneum can be performed safely. Helium gas offers no advantages over CO2.

Effects of preoperative pelvic irradiation on colonic anastomosis healing. An experimental study in rats

PURPOSE

Colorectal anastomosis is a constant worry-issue among surgeons because of high rates of complications, specially the dehiscence. The preoperative irradiation on cancer surgeries might interfere in the healing process, leading to an unfavorable outcome.

METHODS

In the present study, two groups of rats were irradiated previously to a colorectal anastomosis surgery, with intervals of 4 and 8 weeks between the procedures. Seven days after the surgery, healing process was evaluated for dehiscence presence and histologic inflammatory characteristics. Also, levels of hydroxyproline, metalloproteinases and vascular endothelial growth factor were measured.

RESULTS

Our results showed a higher incidence of dehiscences on the animals submitted to irradiation, compared to controls, with a reduced inflammatory activity in the healing tissue.

DISCUSSION

Comparing both irradiated groups, those irradiated 8 weeks before surgery showed higher levels of hydroxyproline and metalloproteinases, indicating higher efficiency of the healing process. In conclusion, preoperative irradiation interferes with intestinal anastomosis healing and a larger time interval between both procedures is safer in terms of the healing quality.

Early anastomotic repair in the rat intestine is affected by transient preoperative mesenteric ischemia

INTRODUCTION

During bowel surgery, perioperative blood loss and hypotension can lead to transient intestinal ischemia. Recent preclinical studies reveal that the strength of intestinal anastomoses can be compromised after reperfusion. So far, this phenomenon has not been investigated in the very first days of healing when wound strength is lowest.

MATERIAL AND METHOD

Ischemia was induced in rats by clamping both the superior mesenteric artery and ileal branches for 30 min. Immediately after declamping, anastomoses were constructed in both terminal ileum and descending colon. The same was done in control groups after sham-ischemia. Anastomotic bursting pressure and breaking strength were measured immediately after operation (day 0) and after 1, 2, or 3 days. Anastomotic hydroxyproline content, gelatinase activity, and histology were analyzed.

RESULTS AND DISCUSSION

In ileal anastomoses, at day 1, both the breaking strength and bursting pressure were significantly (p < 0.05) lower in the ischemic group, while at day 2, this was the case for the bursting pressure only. In the colon, the bursting pressure in the ischemic group was lower at day 1. Anastomotic hydroxyproline content remained unchanged. Increased presence of the various gelatinase activities was found in ileum only at day 0 and in colon at days 1 and 2. Histological mucosal damage was found in ischemia-reperfusion groups.

CONCLUSION

Transient mesenteric ischemia can negatively affect anastomotic strength during the very first days of healing, even if the tissue used for anastomotic construction looks vital.

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.

Effect of thalidomide on the healing of colonic anastomosis, in rats

PURPOSE: Thalidomide, because of its anti-inflammatory properties, as re-emerged as an option for the treatment of Crohn's disease refractory to standard therapy. We studied the effect of thalidomide on the healing of colonic anastomosis. METHODS: Sixty male rats (Rattus norvegicus), were divided into 3 groups of 20 animals each, respectively receiving 0.5 or 1.0 mg/kg thalidomide by the oral route for 7 days, or saline solution (control). All animals were submitted to continuous end-to-end anastomosis with 6-0 Prolene sutures. After sacrifice the anastomoses were analyzed macroscopically and submitted to determination of hydroxyproline, to histology and to immunohistochemistry for metalloproteinase 1, metalloproteinase 1 inhibitor and vascular endothelial growth factor (VEGF). RESULTS: Statistical analysis of the data showed no significant difference in macroscopic aspect or hydroxyproline determination (p= 0.5403). In the immunohistochemical analysis, the following p values were obtained: p = 0.5817 for VEGF, p = 0.1854 for metalloproteinase 1, and p = 0.0023 for metalloproteinase 1 inhibitor, with this last value being considered statistically significant. CONCLUSION: We conclude that thalidomide influenced collagen maturation. There was a stronger action of metalloproteinases, possibly indicating a negative tendency for the healing process.

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.

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.

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.

Effects of soluble fiber on matrix metalloproteinase-2 activity and healing of colon anastomosis in rats given radiotherapy

BACKGROUND AND AIMS

Soluble fiber is fermented by colonic microflora yielding short-chain fatty acids (SCFAs) in the colon. We aimed to investigate the effect of oral administration of soluble fiber on healing of anastomosis and matrix metalloproteinase-2 activity in radiotherapy received colonic anastomosis.

METHOD

Eighty-four Wistar rats were divided into six groups. All rats were performed a left colonic resection with end-to-end anastomosis. Group I received rat cow. Group II received soluble fiber orally for five consecutive days preoperatively as well as 3rd and 6th days postoperatively. Group III received SCFAs via rectum for five consecutive days preoperatively. Group IV received irradiation to the pelvis at a total dose of 24 Gy on the 10th and 5th days before the operation. Group V was exposed to irradiation like the rats in Group IV and oral treatment like the rats in Group II. Group VI received irradiation like the rats in Group IV and transrectal treatment like the rats in Group III. On the 3rd and 7th postoperative days, all the rats were anesthetized to evaluate the anastomosis healing clinically, histologically and biochemically.

RESULTS

Third and 7th day bursting pressures of the rats that were fed with a normal diet and exposed to radiotherapy were significantly decreased (P<0.001). Bursting pressures of Groups V and VI on the 7th day were significantly higher than the control group's bursting pressures (P<0.05). Hydroxyproline levels of Group IV were significantly decreased (P<0.001). Following oral soluble fiber and transrectal administration of SCFAs, these low levels reached to the levels of control radiotherapy group. Matrix metalloproteinase-2 activity of all the rats that were exposed to radiotherapy was higher than the control group (P<0.001). Matrix metalloproteinase-2 enzyme levels in the Groups V and VI were lower than the ones in the Group IV (P<0.001). The histologic parameters of anastomotic healing such as epithelial regeneration, exudate, necrosis, and fibroblast levels were significantly improved by the use of oral soluble fiber and transrectal SCFAs treatment.

CONCLUSION

Undesirable effects of preoperative radiotherapy on mechanical, histological and biochemical parameters can be overcome by oral soluble fiber. Oral soluble fiber administration has similar positive effects like the transrectal administration of the SCFA's.

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.

Changes of the extracellular matrix as a risk factor for anastomotic leakage after large bowel surgery

BACKGROUND

Despite improved surgical techniques, anastomotic leakage remains as a serious complication in colorectal surgery, producing increased morbidity and mortality. This prospective study was initiated to test the hypothesis that preexisting disorders in the extracellular matrix (ECM) may be a factor influencing the onset of anastomotic wound healing complications.

METHODS

In this prospective study of 119 patients with colorectal anastomoses, 30 clinical parameters with possible influence on anastomotic complications were evaluated. From all patients, samples of macroscopically intact colonic tissue were obtained at the index operation. Crosspolarization microscopy was performed to analyze the collagen type I/III ratio, and immunohistochemical studies were done to determine the expression of matrix metalloproteinase (MMP) 1, 2, 9, and 13. The patients with uncomplicated postoperative healing were compared with those developing anastomotic leakage.

RESULTS

Patients with impaired anastomotic healing exhibited a significantly lower collagen type I/III ratio compared with the controls. Significantly higher expression of MMP-1 and MMP-2 in the mucosal layers and of MMP-2 and MMP-9 in the submucosal layers was found in the normal bowel wall of the leakage group. These findings were statistically independent from the clinical parameters.

CONCLUSION

The present study confirms the hypothesis that disturbances of the ECM play a role in the pathogenesis of anastomotic leakage after large bowel surgery.

Collagenase-1 (MMP-1), matrilysin-1 (MMP-7), and stromelysin-2 (MMP-10) are expressed by migrating enterocytes during intestinal wound healing

BACKGROUND

Matrix metalloproteinases (MMPs) play a crucial role in wound healing of the skin, airways, and cornea, but data on MMPs in normal intestinal wound healing is limited. The aim of this study was to clarify the role of collagenase-1 (MMP-1), matrilysin-1 (MMP-7), and stromelysin-2 (MMP-10) in intestinal wound repair and to determine the effect of cytokines on the expression of these MMPs in intestinal epithelial cell lines.

METHODS

Surgical specimens from patients with ischemic colitis (n = 5) were used as an in vivo model of intestinal re-epithelialization. Fetal ileal explants were used as an ex vivo model. In situ hybridization for MMPs -1, -3, -7, and -10 was performed and immunohistochemical stainings were used to localize MMP-7 and -9 expressing cells. Stainings for cytokeratin and laminin-5 were performed to identify epithelial cells and migrating enterocytes, respectively. Caco-2, HT-29, and WiDr cell lines were treated for 6-48 h with different cytokines (e.g. EGF, KGF, IL-1 beta, TGF-alpha, TNF-alpha, and TGF-beta1) and Taqman real-time quantitative RT-PCR was used to investigate their effect on the expression of MMPs-1, -7, and -10.

RESULTS

MMP-7, MMP-10, and MMP-1 were expressed by migrating enterocytes bordering intestinal ulcers in 5/5, 3/5, and 3/5 samples, respectively. In the fetal gut model, MMP-1 and MMP-10 were expressed by migrating enterocytes, but matrilysin-1 expression was not detected. Matrilysin-1 was up-regulated by TNF-alpha and IL-1 beta, and stromelysin-2 by TNF-alpha and EGF in Caco-2 and WiDr cell cultures. MMP-1 was up-regulated in Caco-2 cells by TGF-beta, EGF, and IL-1 beta, but only by EGF in WiDR cells.

CONCLUSIONS

It is concluded that collagenase-1, stromelysin-2, and matrilysin-1 are involved in intestinal re-epithelialization in vivo and that they are up-regulated by cytokines relevant in wound repair.

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.

Tacrolimus enhances colon anastomotic healing in rats

Tacrolimus inhibits T-cell function and neutrophil chemotaxis during inflammation. We hypothesized that tacrolimus would enhance healing of a rat colon anastomosis by reducing the inflammatory response. Fifty-five male Sprague Dawley rats, 230-260 g body weight, underwent identical surgical manipulation consisting of a single-layer, inverted colon anastomosis and the implantation of osmotic pumps subcutaneously in the left flank area. The animals were randomly assigned to receive tacrolimus, at a dose of 0.01, 0.1, or 1.0 mg/kg/day, or only the control solvent solution. The animals were euthanized 4 days after surgery. Colon-bursting pressure (mmHg), anastomotic collagen content ( micro g hydroxyproline/mg wet tissue), and anastomotic type IV collagenase activity (mU/mg protein) were measured. Tacrolimus significantly increased colon-bursting pressure at all doses used (146 +/- 9, 158 +/- 10, 151 +/- 6 mmHg; 0.01, 0.1, and 1.0 mg/kg/day, respectively) vs. control (119 +/- 7 mmHg, p < 0.01). There was no effect on collagen accumulation except at a dose of 0.01 mg/kg/day, which significantly decreased anastomotic collagen content (p < 0.05). Tacrolimus at a dose of 0.01 mg/kg/day increased anastomotic collagenase activity, which was not changed by treatment with the higher doses. Microscopic examination revealed the preservation of the multilayered structure, including the mucosal muscle, a thickened submucosa, and the proper muscle of the anastomotic site in the tacrolimus-treated groups. These data suggest that tacrolimus enhances wound strength during acute anastomotic healing despite a reduction in collagen content.

Matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP in peritoneal fluids and sera and correlation with peritoneal adhesions

OBJECTIVE

To assess the presence of matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP (TIMP-1) in peritoneal fluid and serum of subjects with and without adhesions.

DESIGN

Cross-sectional study.

SETTING

Academic research centers.

PATIENT(S)

Sixty-three patients who underwent abdominal/pelvic surgery.

INTERVENTION(S)

MMP-1, TIMP-1, and MMP-1-TIMP-1 complex content.

MAIN OUTCOME MEASURE(S)

ELISA.

RESULT(S)

Peritoneal fluids (PF) and sera of subjects with and without peritoneal adhesions contain MMP-1, TIMP-1, and MMP-1-TIMP-1 complex at varying levels with 10- to 100-fold higher TIMP-1 than MMP-1. Compared with serum, PF contains a lower level of MMP-1 in subjects with mild adhesions and without adhesions, higher TIMP-1 in subjects with extensive adhesions, and lower MMP-1-TIMP-1 complex in subjects with moderate adhesions. However, the serum and PF content of MMP-1, TIMP-1, and MMP-1-TIMP-1 complex was not statistically different among subjects with or without adhesions, with the exception of TIMP-1 in PF of subjects with extensive adhesions. MMP1-TIMP-1 ratio indicates that a major portion of MMP-1 is in complex with TIMP-1. There was no age- or gender-dependent difference in MMP-1 and TIMP-1 content in serum or PF.

CONCLUSION(S)

Despite differences in MMP-1 and TIMP-1 levels in serum and PF of subjects with extensive and moderate adhesions, there is no correlation between MMP-1 and TIMP-1, with the exception of higher TIMP-1 in PF of subjects with extensive adhesions.

Expression of matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP in serosal tissue of intraperitoneal organs and adhesions

OBJECTIVE

To compare expression of matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP (TIMP-1) in serosal tissue of intraperitoneal organs and adhesions.

DESIGN

Prospective and cross-sectional study.

SETTING

Academic research centers.

PATIENT(S)

Patients undergoing abdominal or pelvic surgery.

INTERVENTION(S)

MMP-1 and TIMP-1 expression.

MAIN OUTCOME MEASURE(S)

Expression of messenger ribonucleic acid (mRNA) and protein was measured by using quantitative reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay.

RESULT(S)

Serosal tissue of intraperitoneal organs and adhesions express MMP-1 and TIMP-1 mRNA and protein at levels that are consistently varied with 10- to 10,000-fold and 2- to 10-fold higher TIMP, mRNA and protein, respectively. Parietal peritoneum, fallopian tubes and ovaries express higher MMP-1 mRNA levels compared with uterus and adhesions; the lowest expression is found in small and large bowels, subcutaneous tissue. and omentum. Expression of TIMP-1 mRNA was less variable; the highest level was found in the uterus and the lowest in subcutaneous tissue and small bowels. There was less variability in MMP-1 and TIMP-1 protein content than mRNA expression; ovaries and adhesions contained the highest MMP-1 and TIMP-1 levels, respectively, and peritoneum contained the lowest. The MMP-1 and TIMP-1 content and ratios further indicate limited MMP-1 proteolytic activity. Although tissues from premenopausal women express more MMP-1 and TIMP-1, expression did not differ by sex or age.

CONCLUSION(S)

Because MMP-1 and TIMP-1 expression varies consistently among the serosal tissues of peritoneal organs and adhesions, and because tissue injury alters their expression, site-specific variations in expression of these substances may predispose a particular organ to develop more adhesions.

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.

Inhibition of matrix metalloproteinases enhances breaking strength of colonic anastomoses in an experimental model

BACKGROUND

The breaking strength of colonic anastomoses declines after operation to a minimum at days 3-4, with a subsequent risk of anastomotic dehiscence. The mechanism is thought to be collagen degradation by matrix metalloproteinases (MMPs). This study examined the pathogenic role of MMPs on the mechanical strength of colonic anastomoses by giving the synthetic broad-spectrum MMP inhibitor BB-1101 systemically.

METHODS

Forty-eight male Sprague-Dawley rats were treated daily for 7 days with BB-1101 30 mg/kg or vehicle alone (control) starting 2 days before operation. The breaking strength of standardized left-sided colonic anastomoses was measured on postoperative days 1, 3 and 7.

RESULTS

Serum BB-1101 levels were increased at 100 nmol/l in BB-1101-treated rats. The anastomotic breaking strength was 48 per cent higher (P = 0.02) in BB-1101-treated animals compared with controls on postoperative day 3. Neither collagen accumulation nor infiltration of neutrophils in the anastomotic area was influenced by BB-1101 treatment. Net deposition of new collagen in subcutaneous sponges was unaffected by the BB-1101.

CONCLUSION

The enhanced breaking strength of colonic anastomoses during the critical early postoperative phase found after administration of a broad-spectrum MMP inhibitor implies that MMPs might increase the risk of anastomotic dehiscence. Presented in part to the third joint meeting of the European Tissue Repair Society and the Wound Healing Society in Bordeaux, France, 24-28 August 1999, and published in abstract form in Wound Repair Regen 1999; 7: A321

Expression of matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 in acute liver injury

BACKGROUND/AIMS

Matrix metalloproteinase-13, one of the principal neutral proteinases capable of cleaving native fibrillar collagens, is important in the degradation and remodeling of extracellular matrix. However, its precise expression in liver injury has not been characterized. We examined the kinetics of the expression of matrix metalloproteinase-13 and one of its specific inhibitors, tissue inhibitor of metalloproteinase-1, in acute liver injury in rats.

METHODS

Acute liver injury was induced by administration of carbon tetrachloride or two different doses of D-galactosamine hydrochloride in Wistar rats. Hepatic matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 mRNA levels were then examined by Northern blotting.

RESULTS

All rats survived after liver injury induced by carbon tetrachloride or low doses of D-galactosamine hydrochloride. However, rats died 5 days after induction of liver injury by high doses of D-galactosamine hydrochloride. In carbon tetrachloride-induced liver injury, matrix metalloproteinase-13 mRNA was transiently increased between 6 h and 1 day after injury. Tissue inhibitor of metalloproteinase-1 mRNA expression was increased between 6 h and 3 days after the peak of matrix metalloproteinase-13 expression. Similar patterns of matrix metalloproteinase-13 and tissue inhibitor of metalloproteinase-1 expression were observed in low-dose D-galactosamine hydrochloride-induced liver injury. In contrast, in high-dose D-galactosamine hydrochloride-induced liver injury, tissue inhibitor of metalloproteinase-1 expression peaked before matrix metalloproteinase-13 expression, which was increased 2 days after injury. Both mRNA levels continued to increase until death.

CONCLUSIONS

Transient expression of matrix metalloproteinase-13, followed by that of tissue inhibitor of metalloproteinase-1, was observed during recovery from acute liver injury induced by carbon tetrachloride and low-dose D-galactosamine hydrochloride. In contrast, disordered expression of matrix metalloproteinase-13 was observed in fatal liver injury caused by high-dose D-galactosamine hydrochloride. These results indicate that matrix metalloproteinase13 plays an important role in the early phase of recovery from liver injury.

Effect of colonic obstruction on the distribution of matrix metalloproteinases during anastomotic healing

BACKGROUND

Anastomotic dehiscence is common after surgery for colonic obstruction. The strength of an anastomosis is dependent on collagen, which is degraded by matrix metalloproteinases (MMPs). The aim of this study was to determine the distribution of the MMPs and their inhibitor, tissue inhibitor of metalloproteinases (TIMP) 1 in an experimental model of colonic obstruction, with and without resection and anastomosis.

METHODS

The distal colon of rabbits was obstructed with a Silastic ring for 24 h and then either the ring was removed or the obstructed segment was resected and an anastomosis formed. Rabbits were killed immediately or at intervals for up to 7 days after operation. The distribution of the MMPs and TIMP-1 was examined by indirect immunofluorescence.

RESULTS

MMPs and TIMP-1 were present throughout the descending colon for 24 h in both groups. They persisted to the third day in rabbits with an anastomosis but by day 7 were restricted to the suture line. Their presence correlated with microscopic damage.

CONCLUSION

The extensive distribution of the MMPs suggests that these enzymes contribute to anastomotic dehiscence, but only in the immediate postoperative period.