The TGF-beta-induced gene product, betaig-h3: its biological implications in peritoneal dialysis.

BACKGROUND: TGF-beta is involved in peritoneal changes during long-term peritoneal dialysis (PD). TGF-beta induces betaig-h3 in several cell lines, and betaig-h3 may be a marker for biologically active TGF-beta. However, no study has reported induction of betaig-h3 in human peritoneal mesothelial cells (HPMCs) or its involvement in PD-related peritoneal membrane changes. METHODS: We used cultured HPMCs to investigate the biological roles of betaig-h3 during mesothelial cell injury and repair, employing the adhesion, spreading, scratching and cell migration assays. Changes in betaig-h3 expression after high glucose exposure in vivo were also evaluated using an animal chronic PD model. RESULTS: In vitro, TGF-beta1 induced betaig-h3 in cultured HPMCs, and betaig-h3-mediated mesothelial cell adhesion occurred via alphavbeta3 integrin. betaig-h3 enhanced mesothelial cell adhesion and migration and, in part, wound healing during mesothelial cell injury. The animal study demonstrated that compared to the control group, betaig-h3 concentrations in the dialysate effluent increased in the dialysis group with alterations in peritoneal structure and function during PD, and betaig-h3 positively correlated with peritoneal solute transport. Immunohistochemical and immunoblotting results showed that betaig-h3 localizes in the mesothelium and submesothelial matrix of the parietal peritoneum, and in the vascular endothelium of omentum. betaig-h3 protein expression was higher in the dialysis group. CONCLUSION: In vitro, betaig-h3 induced by TGF-beta1 in HPMCs improved adhesion and migration of HPMCs during wound healing. In the chronic infusion model of PD, betaig-h3 played a role in the functional deterioration of the peritoneal membrane, which is associated with fibrosis.     

Peritoneal adhesions: pathophysiology

Peritoneal adhesions will form as a consequence of all types of trauma of the peritoneal serosa, be they mechanical, thermal, chemical, infective, or ischemic. Any stimulation induces deposition on the serosa of a fibrin-rich exudate that results in a weaker or stronger adhesion of the viscera to other viscera or to the wall parietal peritoneum. These adhesions are mostly temporary and are eliminated by the action of the fibrinolytic agents present in the peritoneum. In optimal conditions, repair of the injured peritoneum occurs thanks to early mesothelial proliferation over the entire damaged surface, with little production of permanent fibrous adhesions. Some traumatic events are more prone than others to inhibit fibrinolysis through the production of cytokines, that trigger the production of plasminogen inhibitors, thus determining a greater number of more tenacious adhesions. Some stimuli producing postoperative adhesions are iatrogenic in nature and can be individuated and corrected to reduce the production of such adhesions and avoid the onset of adhesion syndromes.     

Nucleic acid and sulphated glycosaminoglycan synthesis in the peritoneal membrane and in intra-abdominal adhesions in rat as affected by silica-induced peritonitis.

The synthesis of DNA, RNA and glycosaminoglycans was studied in the peritoneal membrane and intra-abdominal adhesions formed in rats after a single colloidal silica injection. The concentration of DNA and RNA increased from the first day of peritonitis reaching the maximum at 4--7 days in both the peritoneum and adhesions. On the other hand the synthesis of radioactive DNA and RNA from 3H-thymidine and 3H-cytidine increased during the first 12 hours and was maximal at 24 hours in the peritoneum and at 48 hours in the adhesions. Although the contents of uronic acids were maximal at 24 hours in the peritoneum and at 2--4 days in the adhesions, the maximal synthesis rate of sulphated glycosaminoglycans was observed at 5 days in the peritoneum and at 7 days in the adhesions. The difference in the uronic acid concentration and radioactivities of glycosaminoglycans was probably due to increased permeability of the peritoneal membrane and exudation. Earlier we observed that protein synthesis was maximal at 7 days and that of collagen at 3 weeks. On the basis of these and the present results it is obvious that the order of synthesis of these connective tissue components in the peritoneum after chemical peritonitis follows the pattern of tissue reaction in wound healing and in experimental subcutaneous granuloma formation. However, the activation of nucleic acid and glycosaminoglycan synthesis occurs promptly without any or with a very short lag period in the peritoneal mesenchymal tissue.     

Methylene blue prevents surgery-induced peritoneal adhesions but impairs the early phase of anastomotic wound healing.

OBJECTIVES: Adhesion formation continues to be an important problem in gastrointestinal surgery. In recent years, methylene blue (MB) has been reported to be an effective agent for preventing peritoneal adhesions. However, its effects on the wound healing process are unknown. In the present study, we investigated the effects of MB on the early and late phases of anastomotic wound healing and on adhesion formation. METHODS: We randomly categorized 92 rats into 2 groups in bursting pressure measurements and 50 rats into 3 groups in the adhesion model. We divided the animals into saline-treated (n = 46) or MB-treated (n = 46) groups. Bursting pressures of the anastomoses were measured on postoperative days 3 and 7. In biochemical studies, tissue hydroxyproline levels, total nitrite/nitrate levels and nitric oxide synthase activity were measured on postoperative days 3 and 7. In the adhesion model, we randomly categorized rats into sham (n = 10), saline-treated (n = 20) and MB-treated (n = 20) groups, and the formation of intraperitoneal adhesions was scored on postoperative day 14. We compared the measurement of bursting pressure and biochemical measurements of tissue hydroxyproline levels, total nitrite/nitrate levels and nitric oxide synthase activity. Histopathological findings of specimens were presented. RESULTS: During the early phase of wound healing (postoperative day 3), bursting pressures, tissue hydroxyproline, total nitrite/nitrate levels and nitric oxide synthase activity in the MB-treated group were significantly lower than those of the saline-treated group. On postoperative day 7, there was no significant difference in these parameters between MB and saline-treated groups. In the adhesion model, MB caused a significant reduction in the formation of peritoneal adhesions. CONCLUSION: MB prevents peritoneal adhesions but causes a significant impairment of anastomotic bursting pressure during the early phase of the wound healing process by its transient inhibitory effect on the nitric oxide pathway.     

Postsurgical intraperitoneal exposure to glove powders modulates inflammatory and immune-related cytokine production.

The objective of the present study was to determine whether intraperitoneal exposure to glove powders modulates the inflammatory and immune responses by altering the influx of inflammatory and immune cells and peritoneal fluid cytokines and thus the outcome of surgically induced peritoneal wound healing. Peritoneal wall injuries were made by scraping the tissue until bleeding occurred in 360 mice. One of the following fluids was then introduced into the peritoneal cavity: phosphate-buffered saline solution, phosphate-buffered saline solution containing glove powders (Biosorb and Keoflo, 100 microg/ml), Hydrocote (Hydrogel film, Biogel 100 microg/ml), latex proteins (1 mg/ml), or lipopolysaccharides (12.5 microg/ml). At intervals of 1 to 28 days after injury, 10 mice per treatment per day and 10 uninjured mice were killed, peritoneal fluids were collected to determine the cytokine levels, the rate of fibrous adhesions formed at the site of injuries was graded, and peritoneal walls with attached fibrous adhesions were removed to determine the degree of inflammatory and immune cell infiltration into the wound. The results indicated that, with the exception of interferon-gamma, the peritoneal fluid levels of transforming growth factor-beta1, tumor necrosis factor-alpha, interleukin-1beta, and granulocyte-macrophage-colony stimulating factor in the phosphate-buffered saline solution-treated injured group significantly increased, reaching maximum between days 4 and 7 (p < 0.05) compared with the uninjured group and returned to uninjured values by day 14 after injury. The level of transforming growth factor-beta1 was higher in glove powders and Hydrocote-treated groups than in latex, lipo-saccharides, or phosphate-buffered saline solution-treated groups until day 14 after surgery (p < 0.05). The levels of tumor necrosis factor-alpha and interleukin-1beta increased in all treatment groups during the first week after injury compared with uninjured controls, with the exception of Hydrocote. The number of T helper/inducers (CD4), total leukocytes (CD11a), B lymphocytes (CD45R), granulocytes (Gr-1), and mononuclear phagocytes (Mac-3) in the wound increased during the first week after peritoneal wounding with no significant difference between treated and untreated groups. The rate of adhesion formation was not significantly altered in treated compared with untreated groups. These data suggest that a mechanism which mediates glove powder-induced peritoneal inflammatory and immune reactions in the postsurgical setting involves augmentation of cytokine production without influencing the influx of inflammatory and immune cells or adhesion formation.     

IS LAPAROSCOPY ASSOCIATED WITH A LOWER RATE OF POSTOPERATIVE ADHESIONS THAN LAPAROTOMY? A COMPARATIVE STUDY IN THE RABBIT

This trial set out to test the hypothesis that there is no difference in the incidence of intra-abdominal adhesions after a stereotyped intraperitoneal injury created via laparoscopy or laparotomy. Twenty New Zealand White rabbits had a 2 × 2 cm area of peritoneum stripped off their caecum and adjacent parietal peritoneum, either by laparotomy or laparoscopy. Outcome was assessed by the incidence of adhesions to the test site and the wound. There was no difference in the rate of adhesions at the test site in the two groups. The rate of adhesions to the wound was different in the two groups (70% laparotomy, 0% laparoscopy; P = 0.003). In a rabbit model, comparing laparoscopy and laparotomy in a strictly controlled operative environment, a stereotyped intraperitoneal injury results in similar rates of postoperative adhesions. Laparoscopy is, however. associated with a much lower incidence of wound adhesion. The potential for postoperative adhesions is real after laparoscopic surgery.     

The effectiveness of a single intraperitoneal infusion of a neurokinin-1 receptor antagonist in reducing postoperative adhesion formation is time dependent

BACKGROUND: Current methods to prevent intraabdominal adhesions are not uniformly effective. We recently showed in rats that a neurokinin-1 receptor (NK-1R) antagonist is capable of reducing adhesion formation. To determine the clinical feasibility of using an NK-1R antagonist to reduce adhesions, this study examined the time dependence for the effectiveness of NK-1R antagonist administration and its effects on wound healing. METHODS: Adhesions were surgically induced in rats receiving a single intraperitoneal infusion of the NK-1R antagonist, CJ-12,255, during or 1, 5, 12, or 24 hours after surgery. Adhesion formation was assessed 7 days later. In a subset of animals, tissue plasminogen activator (tPA) activity, which is a measure of peritoneal fibrinolytic activity, was determined in peritoneal fluid 24 hours after surgery (48 hours for animals infused at 24 hours). The tPA activity was also determined in nonoperated animals 24 hours after peritoneal injection of the NK-1R antagonist. Colonic burst pressures were measured 7 days after creation of anastomoses in rats that were administered the antagonist at surgery. RESULTS: The NK-1R antagonist significantly reduced (P=.003) intraabdominal adhesions when administered during or 1 hour after surgery, only moderately reduced (P=.08) adhesions when administered at 5 hours, and had no effect at 12 or 24 hours. Peritoneal tPA activity was significantly increased (P<.05) in peritoneal fluid 24 hours after administration of the NK-1R antagonist regardless of the surgical procedure. The NK-1R antagonist did not alter colonic anastomotic healing. CONCLUSIONS: These data show that some of the events critical to adhesion formation occur within the first 5 hours following an abdominal operation in this model. The fact that the NK-1R antagonist does not impair colonic anastomotic healing enhances its usefulness as a therapeutic agent to inhibit adhesion formation.     

Effect of a matrix metalloproteinase activity and TNF-alpha converting enzyme inhibitor on intra-abdominal adhesions

BACKGROUND: Formation of intra-abdominal adhesions depends, in part, on the activity of serine proteinases. Matrix metalloproteinases (MMP) are required for epithelialization of skin wounds but their involvement in mesothelialization of peritoneal wounds and in adhesion pathogenesis is not known. Early tumor necrosis factor-alpha (TNF-alpha) levels have been proposed to reflect propensity to adhesion formation. OBJECTIVE: The impact of MMP activity and secreted TNF-alpha on peritoneal adhesion formation and healing was investigated through systemic administration of the synthetic broad-spectrum MMP and TNF-alpha-converting enzyme (TACE) inhibitor GM 6001. METHODS: Female Sprague-Dawley rats of 4-6 weeks of age were injected subcutaneously daily with GM 6001 100 mg/kg (n = 12) or vehicle (n = 10) starting two days before surgery. In each rat, two standardized peritoneal wounds, 20 mm x 5 mm, were made. One peritoneal wound was sutured whereas the contralateral wound healed by secondary intention. Adhesion formation and peritoneal healing, cell proliferation, and hydroxyproline concentrations were evaluated on postoperative day 7. RESULTS: Total serum TNF-alpha levels increased in vehicle-treated rats (p = 0.019) while GM 6001 treatment effectively prevented the rise in the postoperative phase (p < 0.001). No significant differences were observed in the extent of adhesion formation (p = 0.67) between control (65.0%) and GM 6001-treated (61.5%) animals, or peritoneal wound healing or cell proliferation. Hydroxyproline levels increased in the wounds (p = 0.014) but were not different between the two groups (p = 0.14). CONCLUSIONS: Lack of a striking effect of the MMP and TACE antagonist GM 6001 on postoperative adhesions suggests that MMP activity and TNF-alpha might not be major adhesiogenic factors.     

Postoperative exposure to glove powders modulates production of peritoneal eicosanoids during peritoneal wound healing.

OBJECTIVE: To assess the effect of postsurgical exposure of peritoneal cavity to glove powders, Hydrocote, latex proteins, and lipopolysaccharide (LPS) on eicosanoid production in peritoneal fluid and cellular distribution of eicosanoid enzymes in peritoneal wound during healing. DESIGN: Randomised experimental study. SETTING: Institute for Wound Research, USA. ANIMALS: 360 mice randomised into six groups of 60 each. INTERVENTION: Abrasion of peritoneal cavity followed by instillation of 500 microl of sterile phosphate buffered saline (PBS) alone (Control) or containing 100 microg/ml of Biosorb, Keoflo, Hydrocote, 1 mg/ml of latex proteins, or 12.5 microg/ml of LPS. Mice were killed at 1, 2, 4, 7, 14 and 28 days, and the peritoneal washing obtained from each animal and concentration of eicosanoids measured. Tissue were immunostained for cyclooxygenases and 5-lipoxygenase and thromboxane A2 (TXA2) synthetase. RESULTS: Peritoneal fluid from uninjured controls contained 3.9 (0.8), 5.2 (0.3) and 0.2 (0.02) ng/ml of thromboxane B2 (TXB2), prostaglandin E2 (PGE2) and leukotriene B4 (LTB4), respectively. These increased significantly during the first week to 6.3 (0.3), 11.7 (0.8) and 2.6 (0.1) ng/ml, p<0.05, before returning to baseline by day 14. In all the treated groups the values were significantly higher than in controls (p<0.05). Immunoreactive cyclo-oxygenases, 5-lipoxygenase and TXA2 synthetase proteins were present in various cell types in uninjured skin and peritoneum, incisional and peritoneal wounds and adhesion tissues. Staining was more intense at the site of wounds and paralleled eicosanoid concentrations during healing. There was no difference between exposed and unexposed groups. CONCLUSION: The presence of glove powders, latex proteins and LPS in peritoneal cavity cause increased eicosanoid production and aggravate the normal inflammatory reaction to tissue injury. This may contribute to the inflammatory or immune reactions and development of adhesions caused by glove powders.     

免疫与炎症调节在腹腔粘连形成中的作用

腹腔粘连是临床常见的手术并发症,临床与实验研究证实：各种抗粘连药物和材料以及微创设备的应用并不能有效预防术后粘连的形成。为减少与控制粘连的发生,自世界第一台外科手术诞生以来,国内外学者从不同角度对腹腔粘连的发病机制进行研究,积累了大量文献。而免疫与炎症在腹腔粘连病理生理过程影响研究逐渐受到重视,笔者对国外学者进行的相关研究文献进行系统分析,旨在了解腹腔粘连炎症与免疫之间的关系,为临床防治提供新的靶标与路径。     

Experimental Animal Model for Readhesion Formation Study

The problem of postoperative adhesions remains unsolved. The formation of readhesions after tubal reconstructive surgery reduces the success rate. We have developed a modified uterine horn model in the rat to study the influence of peritoneal transplants on readhesion formation. A total of 58 rats were operated. In 25 animals (group III) the uterine horn was scratched on both sides and then sutured together. During relaparotomy 14 days later the tight connection between both sides was cut. The resulting defect was covered by a peritoneal transplant on one side (group IIIb) and was left open on the control side (group IIIa). After I4 days the presence or absence of adhesions was explored. There was a significant difference (p <. 001) between the covered (28%) and uncovered (84%) peritoneal defects with respect to incidence of adhesions. To compare the different characteristics of visceral and parietal peritoneum, a pelvic sidewall defect was induced in 33 animals. There was no significant difference between covering the defect by a peritoneal transplant (group II; 42.9%) and the control side (group I; 33.3%). These data suggest that defects on visceral peritoneum should be closed to prevent adhesion formation. The incidence of adhesions after injury of parietal peritoneum seems to be much lower and of less clinical significance.     

Reduced human peritoneal plasminogen activating activity: possible mechanism of adhesion formation

A unifying pathophysiological hypothesis states that the plasminogen activating activity (PAA) of the peritoneal mesothelium determines whether the fibrin which forms after peritoneal injury is either lysed or organized into permanent fibrous adhesions. The PAA of human peritoneal biopsies was measured using a fibrin plate lysis technique to assess the changes that occur in inflammation and ischaemia, conditions which both produce fibrous adhesions. Activity was found in all biopsies from normal parietal and visceral (appendix, bowel and omentum) peritoneum with no significant site-to-site variation. Inflamed peritoneum (parietal, appendicular and mesenteric) had significantly less PAA compared with normal peritoneum; visceral ischaemia also resulted in a significant decrease of PAA. These reductions in human peritoneal PAA observed in inflammation and ischaemia support the view that mesothelial PAA plays a key part in the prevention of events leading to the production of fibrous adhesions.     

Overproduction of transforming growth factor-beta1 (TGF-beta1) is associated with adhesion formation and peritoneal fibrinolytic impairment

BACKGROUND: Reduction in peritoneal fibrinolytic capacity and increased transforming growth factor-beta1 (TGF-beta1) production are associated with adhesion development. This study investigated the expression of TGF-beta1 in peritoneal tissue, and possible correlation with components of the fibrinolytic system locally in peritoneal tissue. MATERIALS AND METHODS: Peritoneal samples were taken from 22 patients at relaparotomy. Samples of adhesions were collected from 10 patients. The patients were categorized into different groups depending on the quantity and the quality of adhesions. TGF-beta1 and components of the fibrinolytic system in tissue extracts were assayed using enzyme-linked immunosorbent assays. RESULTS: The concentration of active TGF-beta1 in peritoneal samples from patients with extensive adhesions was double (P <.01) that of healthy subjects, but the total levels of TGF-beta1 were similar (P =.63). In adhesion tissue, both active (P <.003) and total (P <.008) TGF-beta1 concentrations were more than twice as high as unaffected peritoneum. There was a significant correlation between the concentration of plasminogen activator inhibitor type 1 in peritoneal samples with active TGF-beta1 (P <.03, r = 0.693) and adhesion tissue with total TGF-beta1 (P =.001, r = 0.872). The other components of the fibrinolytic system did not correlate significantly with TGF-beta1. CONCLUSIONS: These data indicate that an overexpression of TGF-beta1 is associated with adhesion formation, possibly through a mechanism involving local regulation of plasminogen activator inhibitor type 1.     

High glucose levels inhibit focal adhesion kinase-mediated wound healing of rat peritoneal mesothelial cells

BACKGROUND: The peritoneum is progressively denuded of its mesothelial cell monolayer in patients on continuous ambulatory peritoneal dialysis (CAPD). These alterations of the mesothelium cause membrane dysfunction and progressive peritoneal fibrosis. Integrins regulate cell motility and play an important role in wound healing. We investigated the effects of high glucose on the regeneration process of the peritoneal mesothelial cell monolayer using cultured rat peritoneal mesothelial cells (RPMC). METHODS: The effects of glucose or mannitol on the regeneration of RPMC and formation of focal adhesions were examined by in vitro wound healing assay and immunocytochemistry, respectively. Activities of focal adhesion kinase (FAK) and its downstream p130Cas were examined by Western blotting. Effects of wild-type and dominant-negative FAK on RPMC migration were examined by a transient transfection assay. RESULTS: Cell migration over fibronectin (FN) was clearly inhibited in culture media containing high glucose (28 to 140 mmol/L). RPMC formed focal adhesions on FN in the presence of a regular glucose concentration (5.6 mmol/L); however, tyrosine phosphorylation of FAK and p130Cas and formation of focal adhesions observed by FAK and vinculin staining were substantially inhibited by high glucose. Mannitol also induced significant inhibitory effects, but these were milder than those of glucose. Transfection of dominant-negative FAK inhibited cell migration in a regular glucose concentration, whereas overexpression of wild-type FAK abrogated glucose-induced inhibition of cell migration. CONCLUSIONS: Our results demonstrate that high glucose concentrations as well as high osmolarity inhibit FAK-mediated migration of mesothelial cells, and suggest that dialysates containing high glucose concentrations may cause peritoneal damage by inhibiting wound healing of the mesothelial cell monolayer.     

Epidermal growth factor modifies the expression and function of extracellular matrix adhesion receptors expressed by peritoneal mesothelial cells from patients on CAPD.

BACKGROUND: Efficient peritoneal dialysis depends on an intact layer of mesothelial cells that line the peritoneal membrane. This layer is disrupted in patents on continuous ambulatory peritoneal dialysis during episodes of peritonitis (acute injury) and replaced by fibrous tissue during extended dialysis (chronic injury). Little is understood of human peritoneal mesothelial cell (HPMC) responses to wounding and episodes of peritonitis. METHODS: HPMC were harvested from spent peritoneal dialysis effluent and maintained under defined in vitro conditions. Adhesive interactions with extracellular matrix (ECM) molecules and chemotactic and wound-healing responses were measured in vitro using purified ECM molecules. RESULTS: HPMC express multiple functional cell receptors recognizing and binding to ECM molecules, including several members of the integrin family. HPMC exhibit directed migration in wound healing and chemotaxis assays with ECM molecules. Epidermal growth factor (EGF) stimulates a reversible change to a fibroblastic phenotype, accompanied by increased expression of beta1 integrins, particularly alpha2beta1, increased adhesion to type I collagen, and significantly greater HPMC migration on type I collagen in wound healing and chemotaxis assays. CONCLUSIONS: HPMC possess the migratory capacity to contribute to the efficient repair of damaged peritoneal membrane after acute injury, and growth factors, such as EGF, facilitate peritoneal membrane healing by augmenting cell adhesion and migration.     

A neurokinin-1 receptor antagonist that reduces intraabdominal adhesion formation increases peritoneal matrix metalloproteinase activity

Adhesions remain a significant complication of abdominal surgery. There is a growing body of evidence suggesting that remodeling of peritoneal extracellular matrix by matrix metalloproteinases (MMPs) is involved in adhesion formation. We have shown that administration of a specific neurokinin-1 receptor (NK-1R) antagonist (CJ-12,255, Pfizer) to rats within 5 hours of surgery reduces intraabdominal adhesion formation. Because substance P (SP), the primary NK-1R ligand, is known to augment tissue fibrosis, the aim of this study was to determine the effects of NK-1R antagonist administration on peritoneal MMP expression and activity 24 hours after surgery in a rat adhesion model. Following laparotomy, four ischemic buttons were created on the peritoneum of rats that received either an intraperitoneal NK-1R antagonist or a vehicle at surgery. Adhesion formation was assessed 7 days later. Peritoneal fluid and tissue were collected at 24 hours to assess total MMP activity, as well as MMP-2, MMP-8, and MMP-9 activity. Specific MMP and tissue inhibitors of MMP mRNAs were measured, and the effects of SP on MMP-3 expression were determined in Met-5A cells, a human peritoneal mesothelial cell line. NK-1R antagonist administration reduced adhesion formation by 47% (p<0.05) at 7 days and significantly increased the total MMP activity in peritoneal fluid at 24 hours. There was an accompanying increase (p<0.05) in MMP-8 and MMP-9 mRNA expression and activity in peritoneal tissue and fluid, respectively. MMP-3 mRNA was also increased in the 24-hour peritoneal tissue, and exposure of Met-5A cells to SP reduced MMP-3 expression and activity. These data support a role for MMPs, specifically MMP-3, MMP-8, and MMP-9, in intraabdominal adhesion formation and suggest that the NK-1R antagonist may reduce adhesions, in part, by increasing MMP activity in the peritoneum by 24 hours after surgery.     

Statins (HMG-CoA reductase inhibitors) decrease postoperative adhesions by increasing peritoneal fibrinolytic activity

OBJECTIVES: The aims of this study were to determine if statins reduce adhesion formation in vivo and to identify the mechanism of action in vitro. BACKGROUND:: Intraperitoneal adhesions develop in up to 95% of patients following laparotomy. Adhesions are reduced by mechanisms that up-regulate fibrinolysis within the peritoneum. Statins promote fibrinolysis in the cardiovascular system and may play a role in the prevention of adhesions. METHODS: Adhesions were induced in rats (n = 102) using our previously described ischemic button model. Rats received vehicle (controls), lovastatin (30 mg/kg), or atorvastatin (30 mg/kg) as a single intraperitoneal dose at the time of laparotomy. Animals were killed and adhesions were quantified at day 7. Peritoneal fluid and tissue were collected at day 1 to measure tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) by real-time PCR and ELISA. To assess the effects of statins on wound healing, burst pressures were measured in anastomoses of the colon. The effects of lovastatin on tPA and PAI-1 production were measured in vitro in human mesothelial cells (HMC) in the presence or absence of mevalonate (MVA), geranylgeranyl-pyrophosphate (GGPP) and farnesyl-pyrophosphate (FPP), all intermediates in the cholesterol pathway downstream of HMG-CoA. The effect of a Rho protein inhibitor, exoenzyme C3 transferase, on tPA production was also determined. RESULTS: Lovastatin and atorvastatin reduced adhesion formation by 26% and 58%, respectively (P < 0.05), without affecting anastomotic burst pressure. At 24 hours, tPA mRNA levels in peritoneal tissue and tPA activity in peritoneal fluid from lovastatin-treated animals were increased by 57% and 379%, respectively (P < 0.05), while PAI-1 levels were unchanged. HMC incubated with either lovastatin or atorvastatin showed concentration-dependent increases in tPA production and decreases in PAI-1 production (P < 0.05). These lovastatin-induced changes in tPA and PAI-1 production were significantly reversed by the addition of MVA, GGPP, and FPP. The Rho protein inhibitor increased tPA production and rescued tPA production from the inhibitory effect of GGPP. CONCLUSION: These data suggest that statins administered within the peritoneum can up-regulate local fibrinolysis, while the in vitro studies show that this effect may be mediated, in part, by intermediates of the cholesterol biosynthetic pathway that regulate Rho protein signaling.     

Role of fibrinolysis in the formation of postoperative adhesions

It has been hypothesized that peritoneal hypofibrinolysis is of importance in the formation of postoperative adhesions, but results from experiments with fibrinolytic modulators are conflicting. We tested this hypothesis in a controlled prospective study in rabbits, comparing the effects of fibrinolytic inhibition (tranexamic acid) to fibrinolysis enhancement by local instillation of gel containing tissue-type plasminogen activator. Adhesion formation was measured after 1 week in a strictly standardized way and is presented as a percentage of an induced lesion that was covered by adhesions. Fibrinolytic inhibition significantly increased adhesion formation, both to the parietal peritoneum (34.2%+/- 3.2%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and to the bowel (76.3%+/- 5.8%) compared with untreated control (51.2%+/- 8.7%, p < 0.05). Control gel significantly increased adhesions to the parietal peritoneum (35.6%+/- 4.6%) versus untreated control (19.7%+/- 3.3%, p < 0.05), whereas gel containing tissue-type plasminogen activator significantly reduced the amount of adhesions to the parietal peritoneum (4.9%+/- 1.7%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and abolished adhesion formation to the injured bowel. The fibrinolytic system thus seems to be intimately involved in the early formation of intraabdominal adhesions.