Metabolic regulation of collagen I in fibroblasts isolated from normal peritoneum and adhesions by dichloroacetic acid

OBJECTIVE

We have previously demonstrated that collagen I, a major component of postoperative adhesions, is differentially regulated in fibroblasts isolated from normal human peritoneum and adhesions. Collagen I messenger RNA (mRNA) levels are significantly lower in fibroblasts from normal peritoneum compared with levels from adhesion fibroblasts. This variation is further accentuated by hypoxia. Because adhesions provide a means of supplying oxygen and nutrients to postsurgical ischemic tissue, we sought to examine the role of aerobic metabolism in the differential expression of collagen I. To examine this issue, we used a compound, dichloroacetic acid (DCA), that stimulates pyruvate dehydrogenase, causing pyruvate to be metabolized in the Kreb's cycle rather than converted into lactate, thereby switching anaerobic to aerobic metabolism. Specifically, we have exposed human fibroblast cultures from normal peritoneum and adhesions to DCA (0, 50, and 100 microg/mL) for 24 hours under normal and hypoxic (2% oxygen) conditions.

STUDY DESIGN

Multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) of collagen I and beta-actin was performed by using mRNA extracted from all treatment points. Analysis of PCR-amplified products was performed by fractionation over a 2% agarose gel, followed by ethidium bromide staining of DNA bands. A scanning densimeter was used to determine the ratio of intensity of each band relative to beta-actin. Densimetric analysis of gel bands was performed by using the National Institutes of Health image analysis program.

RESULTS

Although DCA stimulated peritoneal fibroblast collagen I mRNA expression under normoxic conditions, its expression was reduced during hypoxia. In adhesion fibroblasts, DCA treatment consistently lowered collagen I mRNA expression; this effect was manifested to a greater extent under hypoxic conditions.

CONCLUSION

In summary, these findings confirm that fibroblasts from adhesions are characterized by excessive collagen I production, which is further accentuated by hypoxia. These observations are extended to show the stimulation of oxidative metabolism by DCA increases collagen I production; in contrast DCA inhibits collagen I production by normoxic adhesion fibroblasts as well as under hypoxic conditions in both types of fibroblasts. Thus, regulation of metabolic activity of peritoneal cells may provide a target for future interventions for reduction of postoperative adhesions.

Increased monocyte adhesion to aortic endothelium in rats with hyperhomocysteinemia: role of chemokine and adhesion molecules

OBJECTIVE

The stimulatory effect of homocysteine (Hcy) on monocyte chemoattractant protein (MCP)-1 expression in vitro has been suggested to play an important role in Hcy-mediated atherosclerosis. We investigated whether such a stimulatory effect occurs in vivo, leading to monocyte adhesion to the endothelium.

METHODS AND RESULTS

Sprague-Dawley rats were divided into 4 groups. Hyperhomocysteinemia was induced in 1 group of rats after 4 weeks of a high-methionine diet (serum Hcy levels were 4- to 5-fold higher than levels in control rats). The number of ED-1-positive cells present on the surface of aortic endothelium was significantly elevated in hyperhomocysteinemic rats. There was a significant increase in the expression of MCP-1, vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in the endothelium. Antibodies recognizing MCP-1, VCAM-1, or E-selectin could abolish the enhanced monocyte binding to the aortic endothelium of hyperhomocysteinemic rats. Endothelium-dependent aortic relaxation was impaired in hyperhomocysteinemic rats.

CONCLUSIONS

These results suggest that in the absence of other known risk factors, hyperhomocysteinemia stimulates the expression of MCP-1, VCAM-1, and E-selectin in vivo, leading to increased monocyte adhesion to the aortic endothelium. Such an effect may contribute significantly to the development of atherosclerosis by facilitating monocyte/macrophage infiltration into the arterial wall.

Effect of laparoscopic and conventional colorectal resection on peritoneal fibrinolytic capacity: a prospective randomized clinical trial

BACKGROUND AND AIMS

Reduced fibrinolytic activity of the peritoneum seems to be the main cause of postoperative adhesions. This prospective randomized trial compared the peritoneal fibrinolytic activity between laparoscopic and conventional colorectal resection.

METHODS

Parietal peritoneal biopsy specimens were taken in standardized elective laparoscopic ( n=14) and conventional ( n=16) colorectal resections at the beginning and at the end of surgery. Activities and concentrations of tissue-plasminogen activator (tPA), plasminogen activator (PAI) type 1, and tPA/PAI complex were determined by ELISA kits.

RESULTS

There was no difference in age, sex, or body mass index between the two groups. Perioperative tPA activity decreased in both groups without differences between the groups. Concentrations and activities of tPA, PAI-1, and tPA/PAI complex did not differ between the groups at any time.

CONCLUSION

Peritoneal concentrations and activities of tPA, PAI-1, and tPA/PAI complex are similar during laparoscopic and conventional colorectal resections. A capnoperitoneum of 12 mmHg over 3 h did not affect the peritoneal fibrinolytic activity

Expression of connective tissue growth factor in intra-abdominal adhesions

PURPOSE

Connective tissue growth factor stimulates fibroblast proliferation and extracellular matrix deposition in many fibrotic disorders. The aim of our study was to determine the expression pattern of connective tissue growth factor in postoperative intra-abdominal adhesions.

METHODS

Adhesions were created in 46 Sprague-Dawley rats by complete dissection and resuturing of a peritoneal patch 2 cm in diameter, lateral from the midline incision. Animals were killed at postoperative Days 3, 6, 9, 12, 15, 18, and 21 and the adhesions scored on a scale of 0 to 5. Tissue samples from adhesion areas and from uninvolved peritoneum were evaluated by Northern and Western blotting for temporal connective tissue growth factor mRNA and protein expression, respectively. Immunohistochemical analysis was performed for connective tissue growth factor localization.

RESULTS

Adhesions formed in all animals after surgery and were confined to the peritoneal patches. Adhesion formation increased across time, with significant correlation between adhesion scores and postoperative days (r = 0.329, P = 0.026). Connective tissue growth factor mRNA concentrations were significantly elevated in adhesion tissue throughout the three-week period when compared with normal peritoneum (P = 0.012); peak levels occurred between Days 6 and 15. Western blots demonstrated connective tissue growth factor protein expression in adhesions from Days 6 to 21, in contrast to negligible bands in normal peritoneum. Fibroblasts within the adhesive tissue, but not in uninjured peritoneum, stained positive for connective tissue growth factor by immunohistochemistry.

CONCLUSIONS

We have demonstrated a specific temporal and spatial expression pattern for connective tissue growth factor in intra-abdominal adhesions during a three-week postoperative time course. According to what is known about the functional role of connective tissue growth factor in fibrogenesis, our findings warrant further investigations addressing a causal relationship between this growth factor and fibrous adhesion formation.

Single-chain urokinase alone or complexed to its receptor in tetracycline-induced pleuritis in rabbits

Intrapleural loculation can increase morbidity in hemothoraces or parapneumonic effusions. Intrapleural fibrin precedes visceral-parietal pleural adhesions. We speculated that single-chain urokinase plasminogen activator alone or bound to its receptor could prevent these adhesions by their relative resistance to local inhibition by plasminogen activator inhibitors. We found that recombinant human single-chain urokinase-bound rabbit pleural mesothelial cells or lung fibroblasts with kinetics similar to that reported for human cells (kD of approximately 5 nM). The receptor-bound fibrinolysin maintained in vitro fibrinolytic activity in the presence of pleural fluids from rabbits with tetracycline-induced pleural injury over 24 hours. In rabbits given intrapleural single-chain urokinase 24 and 48 hours after intrapleural tetracycline (n = 10 animals), adhesions were prevented, whereas the receptor-complexed form (n = 12) attenuated adhesions versus vehicle/tetracycline-treated rabbits (n = 22, p <or= 0.005 in both cases). There were more adhesions in the complex than the single-chain urokinase group (p = 0.02). Residual antigenic but not functional evidence of the interventional agents remained in pleural fluids at 72 hours after tetracycline. No local or systemic bleeding occurred because of either interventional agent. The data demonstrate that single-chain urokinase inhibits, whereas lysin-receptor complexes attenuate, adhesion formation in tetracycline-induced pleural injury in rabbits.

CD4+ T cells regulate surgical and postinfectious adhesion formation

The development of adhesions in the peritoneal and pelvic cavities, which commonly form after surgery or infection, cause significant morbidity and mortality. However, the pathogenesis of adhesion formation is still poorly understood. Because T cells are important in orchestrating fibrinogenic tissue disorders, we hypothesized that they play a critical role in the pathogenesis of peritoneal adhesion formation. Using a cecal abrasion surgical model in rodents, T cell depletion and adoptive transfer experiments demonstrated that this host response is dependent on CD4+ alphabeta T cells. These cells were also critical to adhesion formation associated with experimental intraabdominal sepsis. T cell transfer studies with mice deficient in signal transducer and activator of transcription (Stat)4 and Stat6 revealed that adhesion formation was dependent on a T helper 1 response. Activated T cells homed to the peritoneal cavity 6 hours after cecal abrasion surgery and predominated at this site during adhesiogenesis. Increased levels of the T cell-derived proinflammatory cytokine interleukin (IL)-17 and of neutrophil chemoattractant CXC chemokines macrophage inflammatory protein-2/CXCL8 and cytokine-induced neutrophil chemoattractant/CXCL1 were associated with adhesion formation. The production of these chemokines was dependent on T cells. Furthermore, the administration of neutralizing antibodies specific for IL-17 or the receptor that binds these CXC chemokines, CXC chemokine receptor 2, significantly reduced the degree of adhesion formation. These results demonstrate for the first time that the immunopathogenesis of adhesion formation is under the control of T cells and that T cell-derived cytokines and chemokines play important roles in the development of this deleterious host response.

The correlation of adhesions and peritoneal fluid cytokine concentrations: a pilot study

BACKGROUND

Intra-abdominal adhesion formation and reformation after surgery is a significant cause of morbidity. The greatest problem after the surgical removal of adhesions is their reformation. We examined the concentrations of interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-alpha in the peritoneal fluid throughout the 48 h post-operative period following adhesiolysis, and correlated the results to the extent of adhesion reformation.

METHODS

Peritoneal fluid, collected from eight patients following laparoscopy and again at 12, 36 and 48 h after surgery, was analysed using enzyme-linked immunosorbent assay (IL-1 and IL-6) and bioassay (TNF-alpha). At 48 h, a second look laparoscopy was performed to inspect the pelvis for adhesion formation/reformation.

RESULTS

Three patients had adhesion reformation >10% at 48 h after surgery. The mean adhesion score 48 h after adhesiolysis was 5 (range 0-17). The mean reduction in adhesion score was 88% (range 83-100%). Newly formed adhesions were filmy, relatively soft and avascular in nature. Adhesion reformation of >10% was associated with (i) high concentrations of IL-6 at 12 h (P < 0.01) and (ii) high concentrations of IL-1 at 48 h (P < 0.001).

CONCLUSIONS

Results from this preliminary study suggest that future treatment strategies for adhesion prevention could be aimed at the control of cellular mediators in the peritoneal fluid during the initial adhesion formation period.

Chymase inhibitor suppresses adhesion formation in a hamster experimental model

To clarify the role of chymase produced by mast cells in adhesion formation, we investigated the preventive effect of a specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)2, on adhesion formation in a hamster experimental model. Hamsters underwent resection of the right uterine body and then 10 microM Suc-Val-Pro-Phe(p) (OPh)2 or placebo was injected into the abdomen. Two weeks after the operation, the scores for adhesion formation in the chymase inhibitor-treated group were significantly lower than that in the placebo-treated group (placebo-treated group, 3.60+/-0.22; chymase inhibitor-treated group, 2.10+/-0.22; P<0.01). This specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)2, significantly suppressed the scores for adhesion formation in a hamster experimental model. Thus, chymase may play an important role in the adhesion formation.

Time course of peritoneal tissue plasminogen activator after experimental colonic surgery: effect of hyaluronan-based antiadhesive agents and bacterial peritonitis

BACKGROUND

This study assessed the peritoneal fibrinolytic response during the first week after colonic surgery in rats with and without bacterial peritonitis, and possible modulation of the response by two hyaluronan-based antiadhesive agents.

METHODS

A colonic anastomosis was constructed in 90 male Wistar rats. Peritonitis was induced in another 108 rats and a colonic anastomosis was constructed after 24 h. Rats in both groups were randomized into an untreated group or one of two groups treated with hyaluronan-based agents. One-third of each group was killed at each of days 1, 3 and 7 after operation, and tissue plasminogen activator (tPA) antigen and activity were measured in peritoneal biopsies.

RESULTS

One day after colonic surgery in normal rats, tPA antigen concentration was significantly (P < 0.005) increased, whereas tPA activity levels were normal. By day 3 after operation tPA antigen had returned to baseline values while tPA activity was significantly increased (P < 0.05). One day after inducing peritonitis tPA antigen was significantly increased (P < 0.001), while tPA activity was significantly reduced (P < 0.05). Three and seven days after colonic surgery in rats with peritonitis tPA activity was increased (P < 0.001) while tPA antigen had returned to baseline values. Neither of the hyaluronan-based agents affected peritoneal tPA antigen levels or activity after colonic surgery.

CONCLUSION

Both abdominal surgery and infection caused an early increase in peritoneal tPA antigen levels, followed by an increase in tPA activity. Peritonitis severely depressed early tPA activity. Application of hyaluronan-based agents did not affect the peritoneal fibrinolytic response to surgery and/or infection.

IL-1, IL-6 and TNF-alpha concentrations in the peritoneal fluid of women with pelvic adhesions

BACKGROUND

Pelvic adhesions are a significant cause of morbidity and are associated with infertility and pain. The three pro-inflammatory cytokines interleukin (IL)-1, IL-6 and tumour necrosis factor (TNF)-alpha are involved in adhesion formation/reformation.

METHODS

The concentration of these three cytokines was examined in the peritoneal fluid of women undergoing laparoscopy, in order to examine the factors affecting their concentrations, with specific reference to the presence or absence of adhesions.

RESULTS

We found that the concentration of TNF-alpha in the peritoneal fluid was significantly correlated to the menstrual cycle day (P < 0.01), with increasing concentration as the menstrual cycle progressed from the follicular to the luteal phase. In contrast, IL-1 and IL-6 levels did not show any variation throughout the menstrual cycle. Increased TNF-alpha was found in patients with pelvic adhesions compared with those with normal pelvis; the concentration of TNF-alpha was highest in mild compared with severe adhesions. In contrast, IL-1 concentration was higher in the presence of severe adhesions. IL-6 levels were significantly correlated with the grade of endometriosis (P < 0.05), but there were no significant correlations of either TNF-alpha or IL-1 concentrations with the various grades of endometriosis.

CONCLUSION

The exact role of TNF-alpha and IL-1 in adhesion formation is still unknown, but the results from this study suggest that their concentration in the peritoneal fluid is associated with the degree of adhesions present.

Differential expression of TGF-beta1 and TGF-beta3 in serosal tissues of human intraperitoneal organs and peritoneal adhesions

Elevated local expression of transforming growth factor (TGF-beta) has been associated with increased incidence of peritoneal adhesion formation. In this study we determine whether differences in basal expression of TGF-beta in serosal tissue of peritoneal organs correlate with incidence of adhesion formation. Serosal tissue of parietal peritoneum, uterus, oviduct, ovary, omentum, large and small bowels as well as adhesions, skin, fascia, subcutaneous tissue, peritoneal fluid and serum were collected from 57 subjects with/without adhesions who were undergoing abdominal/pelvic surgery. To determine TGF-beta1 and TGF-beta3 mRNA and protein expression, total RNA and protein were isolated from these tissues and along with the fluids, subjected to quantitative RT-PCR and enzyme-linked immunosorbent assay (ELISA) respectively. Tissue sections were immunostained for TGF-beta1 and TGF-beta3 protein. We found that TGF-beta1 and TGF-beta3 mRNA and protein are expressed in these tissues and present in peritoneal fluids and serum, with considerable variations in level of their expression. Comparatively, there was more variation in TGF-beta1 than TGF-beta3 expression without age or gender relation. Adhesions express a significantly higher TGF-beta1 mRNA and have the highest TGF-beta1:TGF-beta3 ratio, with lowest concentrations and ratio detected in omentum, small and large bowels; in contrast uterus expresses higher TGF-beta3, with lowest concentrations detected in subcutaneous tissue and large bowels (P < 0.05). A similar trend was also observed for total (active + latent) TGF-beta1 protein expression, with low active TGF-beta1 that was not significantly different among the tissue extracts and fluids. However, the lowest active:total TGF-beta1 ratio was found in adhesions and ovary. In subjects with adhesions, the adhesions express significantly more TGF-beta1 compared to parietal peritoneum (P < 0.05). Immunoreactive TGF-beta1 and TGF-beta3 protein were present in various cell types in these tissues with intensity reflecting their mRNA and protein expression. In conclusion, we provided evidence that serosal tissue of various peritoneal organs and adhesions express TGF-beta1 and TGF-beta3. Since TGF-beta is expressed differently in these tissues and tissue injury often alters the expression of TGF-beta, we propose that tissues with a higher basal expression of TGF-beta may become predisposed to develop more adhesions compared to others.

Tumor necrosis factor-dependent adhesions as a major protective mechanism early in septic peritonitis in mice

The occurrence of peritoneal adhesions in surgical patients is positively correlated with tumor necrosis factor (TNF) levels. In a model of septic peritonitis-cecal ligation and puncture-TNF neutralization prevented formation of peritoneal adhesions and increased mortality, most likely because localization of the septic focus was prevented. To discriminate between the coagulation-independent protective TNF effect and a potential protective procoagulant TNF effect, formation of peritoneal adhesions after CLP was inhibited with heparin, hirudin, or urokinase. Each treatment increased mortality and increased the number of bacteria in the peritoneal lavage fluid, kidney, and liver to various degrees. Under these experimental conditions, antibiotics prevented death. In coagulation-compromised mice, lethality was further enhanced by additional TNF neutralization. These findings demonstrate that peritoneal adhesions early in septic peritonitis are an important mechanism of innate immunity that prevents increased spread of bacteria and reduces mortality.

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.

Suppression of fibrous adhesion by proteoglycan decorin

Small proteoglycan decorin is known to suppress the bioactivity of TGF-beta through a competitive binding with the cell surface receptors for the cytokine. Based on this knowledge, we hypothesized that decorin could reduce the formation of fibrous adhesion, because our previous study showed the neutralizing antibody to TGF-beta1 has that effect. An intra-articular adhesion model in the rabbit knee joint was employed in this study, and decorin was administered into the joint cavity continuously during the 4 weeks of the experiment. The results of the dose-response study demonstrated that decorin suppresses formation of fibrous adhesion in a dose-dependent manner. When the administration of decorin was limited to shorter periods, this effect was considerably impaired and the necessity of long-term administration was demonstrated. On the other hand, when administered together with TGF-beta1, decorin still suppressed adhesion but to a lesser extent, and it was suggested that this proteoglycan could have other significant mechanism(s) to suppress adhesion besides the neutralization of TGF-beta. Thus, the present study showed that decorin could inhibit adhesion formation by both TGF-beta dependent and independent mechanisms. Considering that decorin exists ubiquitously in the body, its administration might be a promising approach to suppress adhesion.

Neutralization of fibroblast growth factor-2 reduces intraarticular adhesions

Adhesion is a serious complication after trauma or surgery. Because adhesion formation is essentially a fibrogenetic process, a series of growth factors are assumed to be involved in its development. If this is true, it may be possible that inhibition of the growth factor activity suppresses adhesion formation. The current study was conducted to verify this hypothesis on fibroblast growth factor-2 using an intraarticular adhesion model in the rabbit knee. Forty Japanese White rabbits were used. They were divided randomly into five groups of eight animals, and in three of them, activity of endogenous fibroblast growth factor-2 was suppressed locally by a neutralizing antibody. The remaining two groups served as controls, and formation of adhesions was evaluated 4 weeks after surgery. The results showed that the administration of the antibody reduced the extent of adhesions macroscopically, whereas histologic observation and collagen content measurement suggested the adhesion tissue was not affected significantly. Corresponding to the macroscopic findings, contraction of the knee was improved in the antibody groups. The findings showed that suppression of fibroblast growth factor-2 activity reduces adhesions. It is expected that control of the cytokine activity may become a novel method for reducing adhesions.

Effect of drying methods on retention of moist sucralfate gel properties

The aim of this work was to find a drying procedure for moist sucralfate gel capable of producing dried sucralfate gel that retains the original gel properties of bioadhesion, rheology, and micromeritics. Spray-drying and microwave-drying procedures were employed. Mannitol was used as a gel-protective substance during the drying processes. The spray drying of moist sucralfate gel gave rise to a powder whose water suspensions showed significantly reduced viscosity. The bioadhesion of spray-dried sucralfate gel was strongly reduced by drying. When mannitol was used as a gel protector, the spray-dried sucralfate in part maintained the original bioadhesion of moist sucralfate gel. The preparation of a dried sucralfate gel retaining the bioadhesion characteristics, avoiding the use of mannitol, was made possible using the microwave-drying procedure. The microwave-dried product possesses a granular morphology suitable for direct compression because it is a free flowing and strongly coherent granular powder.

Peritoneal fluid interleukin-6 in women with chronic pelvic pain

OBJECTIVE

To determine the relationship between peritoneal fluid concentrations of interleukin-6 (IL-6) and chronic pelvic pain symptomatology in women with adhesions, endometriosis, or no obvious intraperitoneal pathology.

DESIGN

Clinical research study.

SETTING

Healthy volunteers in an academic research environment.

PATIENT(S)

Reproductive-aged women undergoing laparoscopy for the diagnosis of pelvic pain, infertility, or sterilization were selected.

INTERVENTION(S)

Peritoneal fluid was collected at the time of the laparoscopy and later assayed for IL-6. Subjects completed a pelvic pain questionnaire, and operative reports were used to obtain the underlying diagnosis.

MAIN OUTCOME MEASURE(S)

Interleukin-6 concentrations.

RESULT(S)

No correlation between the presence or absence of pelvic pain, findings of adhesions or endometriosis, and the concentration of peritoneal fluid IL-6 was observed.

CONCLUSION(S)

The cytokine IL-6 does not seem to play a role in the genesis of chronic pelvic pain in women with adhesions or endometriosis.

ROCK mediates thrombin's endothelial barrier dysfunction

Thrombin-induced endothelial monolayer hyperpermeability is thought to result from increased F-actin stress fiber-related contractile tension, a process regulated by the small GTP-binding protein Rho. We tested whether this process was dependent on the Rho-associated protein kinase, ROCK, using a specific ROCK inhibitor, Y-27632. The effects of Y-27632 on thrombin-induced myosin light chain phosphorylation (MLCP) and tyrosine phosphorylation of p125 focal adhesion kinase (p125(FAK)) and paxillin were measured by Western blotting. F-actin organization and content were analyzed by digital imaging, and endothelial monolayer permeability was measured in bovine pulmonary artery endothelial cell (EC) monolayers using a size-selective permeability assay. Y-27632 enhanced EC monolayer barrier function due to a decline in small-pore number that was associated with increased EC surface area, reduced F-actin content, and reorganization of F-actin to beta-catenin-containing cell-cell adherens junctions. Although Y-27632 prevented thrombin-induced MLCP, stress fiber formation, and the increased phosphotyrosine content of paxillin and p125(FAK), it attenuated but did not prevent the thrombin-induced formation of large paracellular holes. These data indicate that thrombin-induced stress fiber formation is ROCK dependent. In contrast, thrombin-induced paracellular hole formation occurs in a ROCK-independent manner, whereas thrombin-induced monolayer hyperpermeability appears to be partially ROCK dependent.

Role of transforming growth factor beta-1 in peritonitis-induced adhesions

Peritonitis is a major cause of intra-abdominal adhesion formation. The overexpression of transforming growth factor beta-1 (TGF-Beta1), a potent mitogen, chemoattractant, and stimulant for collagen synthesis by fibroblasts, has been linked to tissue fibrosis at various sites throughout the body including peritoneal adhesion formation. Hence we hypothesized that the mechanism(s) involved in peritonitis-induced adhesion formation may be mediated through the upregulation of TGF-Beta1 expression. Peritonitis was induced in rats by cecal ligation and puncture, while a control group underwent sham operation. Adhesions were scored and harvested from both groups at 0, 6 and 12 hours and at 1, 2, 4, 7, and 28 days. Tissue expression of TGF-Beta1 mRNA was determined by quantitative reverse transcription-polymerase chain reaction and TGF-Beta1 protein was localized by immunohistochemical analysis. Serum and peritoneal fluid TGF-Beta1 concentrations were quantified by enzyme-linked immunosorbent assay. Compared with sham operation, peritonitis was associated with a significantly greater incidence of abdominal adhesions and a significant increase in the levels of TGF-Beta1 mRNA expression at days 2, 4, and 7. Immunostaining intensity of TGF-Beta1 in adhesions from the peritonitis group also steadily rose through day 7. In peritoneal fluid, the ratio of active:total TGF-Beta1 was significantly increased in the peritonitis group on days 1, 2, and 4 compared with the sham group. These results suggest that peritonitis is associated with the upregulation of TGF-Beta1, a mechanism that may exacerbate adhesion formation.

Altered expressions of VEGF mRNA splice variants during progression of uterine-peritoneal adhesions in the rat

PROBLEM

Postoperative pelvic adhesions contribute to infertility, pelvic pain, bowel obstruction, and difficult reoperative procedures.

METHOD OF STUDY

In the present study, a rat uterine-peritoneal adhesion model was developed to study the progression of adhesion formation during a course of 7 days following pelvic surgery. The distal 1 cm of each uterine horn and its adjacent peritoneum was abraded by six scratches with a scalpel blade, producing punctate bleeding. The scratched portion of uterine horn and the peritoneum was then held with Vicryl 3-0 to promote adhesion. The uterine tissue and the portion of peritoneum, held with suture, were then excised from a group of four rats, each at 6, 12, 24, 48, 72 hr and 5 and 7 days following surgery. Total RNA was isolated from these tissues and the expression pattern of different splice variants of vascular endothelial growth factors (VEGF) was examined using relative abundance reverse transcriptase polymerase chain reaction (RA-RT-PCR) method.

RESULTS

Three known splice variants of VEGF mRNA (VEGF120, VEGF164 and VEGF188), as well as an additional band (approximately 510 bp), were amplified from these tissues. The relative abundance of known VEGF isoforms demonstrated altered expression during adhesion progression. When compared with noninjured uterine tissues, VEGF120 and VEGF188 demonstrated up-regulation during early stages of adhesion formation, whereas VEGF164 rather demonstrated down-regulation 24 and 48 hr following surgery.

CONCLUSIONS

The up-regulation of VEGF isoforms during the progression of uterine-peritoneal adhesion may be a compensatory mechanism regulating angiogenesis in order to provide nutrients and oxygen to the injured tissues.

Peritoneal fluid cytokine and eicosanoid levels and their relation to the incidence of peritoneal adhesion

OBJECTIVE

To determine the peritoneal fluid content of several cytokines and eicosanoids with inflammatory, anti-inflammatory, anti-fibrotic, and fibrotic activities, and to assess the relationship of these levels with the incidence of peritoneal adhesions.

METHODS

Peritoneal fluids were collected from 30 subjects with adhesions (n = 22) or with normal pelvic anatomy (n = 8), and the level of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), interleukin-10 (IL-10), interferon gamma (IFN-gamma), transforming growth factor beta-1 (TGF-beta 1), granulocyte macrophage-colony stimulating factor (GM-CSF), prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and thromboxane B2 (TXB2) were determined by enzyme-linked immunosorbent assay (ELISA) and radioreceptor assay.

RESULTS

The peritoneal fluid content of these factors varied considerably, with low levels of IL-1 beta, TNF-alpha, IL-10, IFN-gamma, and GM-CSF. Only IFN-gamma levels were significantly lower in subjects with adhesions compared with the normal group (P < .05). The levels of total (latent + active) and active TGF-beta 1 were higher than those of other cytokines assayed and were significantly higher in subjects with adhesions compared with the normal group (P < .05). The peritoneal fluid content of PGE2, TXB2, and LTB4 was significantly higher than that of the cytokines and was higher, but not significantly so, in subjects with adhesions compared with normal subjects (P = .06).

CONCLUSION

Although the effect of length of time since the adhesions were formed is not known, the results indicate that peritoneal fluid content of these cytokines and eicosanoids, with the exception of IFN-gamma and TGF-beta 1, does not correlate with the presence of peritoneal adhesions.

Remodeling of peritoneal-like structures by mesothelial cells: its role in peritoneal healing

BACKGROUND

Intraabdominal adhesions are a common complication following laparotomy. Since the exact mechanisms involved in this processes are unknown we have analyzed in vitro the role of mesothelial cells in peritoneal healing.

MATERIAL AND METHODS

Human mesothelial cells from omental tissue were cultivated for 2 weeks in a three-dimensional culture either on or in a collagen type I matrix. The effects of blood and collagen matrix were analyzed by exposing mesothelial cells to an overlying blood clot, simulating intraperitoneal bleeding, or a second collagen layer. The production of collagen types III and IV, fibronectin, and laminin was analyzed with immunohistochemical methods.

RESULTS

Mesothelial cells grown on a collagen matrix formed a monolayer of flat or cobblestone-like cells whereas those cultivated in a collagen matrix exhibited spindle-like morphology. Mesothelial cells failed to grow into an overlying collagen matrix, but did grow into a blood clot, emphasizing a potential role of blood clots in peritoneal adhesion formation. Independent of the culture systems mesothelial cells produced collagen type III, fibronectin, and laminin but not collagen type IV.

CONCLUSIONS

Our experiments demonstrate remodeling of peritoneal-like structures by mesothelial cells in a three-dimensional culture reflecting their putative role in the reepithelialization after serosal defects, and also in the formation of peritoneal adhesions.

The role of neutrophils in the formation of peritoneal adhesions

The most common cause of intraperitoneal adhesions which may result in infertility and intestinal obstruction is previous abdominal surgery. Surgical trauma of the peritoneum in the absence of infection elicits a rapid and transient influx of polymorphonuclear leukocytes (PMN) into the peritoneal cavity. The role of neutrophils in intraperitoneal adhesion formation has not been studied. We aimed to study the effects of PMN counts and PMN functions on peritoneal adhesion formation. Forty peritoneal adhesion-induced rats were randomly divided into three groups; group I, receiving saline; group II, receiving cyclophosphamide; and group III, receiving granulocyte-macrophage colony-stimulating factor (GM-CSF). In all groups, peritoneal lavage was performed to determine PMN counts the day after adhesion induction. Blood neutrophil counts and neutrophil functions were also determined. Adhesions were evaluated blindly 14 days after the operation. Adhesion tissue samples were microscopically evaluated. Tissue hydroxyproline and collagen concentrations were measured. The neutrophil counts and phagocytosis significantly increased in group III and neutrophil counts decreased in group II (P < 0.05). The score of adhesion formation in group II was significantly less than that in groups I and III (P < 0.05). Hydroxyproline concentrations of adhesion tissue were significantly decreased in group II when compared with group III (P < 0.05). The present study shows that neutropenia lowers the degree of postoperative adhesion formation. It is concluded that PMN may have a role to play in modulating post-operative adhesion formation.

Tissue markers as predictors of postoperative adhesions

BACKGROUND

Postoperative adhesion formation has been associated with a decreased capacity to degrade intra-abdominally deposited fibrin. Adhesions, once lysed, have a high propensity for reformation. This study tested the hypothesis that patients with a high propensity for adhesion formation as well as adhesion tissue had a reduced fibrinolytic capacity.

METHODS

Peritoneal biopsies were taken during abdominal surgery from 21 patients who had previously undergone operation; previously formed adhesion tissue was sampled from ten of these patients. Adhesion formation was scored. The fibrinolytic capacity of peritoneum was determined in tissue extracts.

RESULTS

At the time of opening of the abdominal cavity, levels of plasminogen activator inhibitor (PAI) type 1 (P = 0.009) and tissue-type plasminogen activator (tPA)/PAI complex (P = 0.008) were increased in peritoneal samples from patients with severe adhesions compared with those in samples from patients with less severe adhesions. Adhesion tissue similarly had reduced fibrinolytic capacity as judged by a decrease in tPA activity (P = 0.005) and an increase in PAI-1 level (P = 0.01), reflected in an increased level of tPA/PAI complex (P = 0.008) compared with unaffected peritoneum.

CONCLUSION

These observations demonstrate reduced fibrinolytic capacity in peritoneal tissue in patients with a greater propensity for development of adhesions and likewise in adhesion tissue. This suggests that components of the fibrinolytic system may be used as markers of an increased risk of adhesion development.

Peri-ovarian adhesions interfere with the diffusion of gonadotrophin into the follicular fluid

In previous studies, patients with severe peri-ovarian adhesions have been found to show low pregnancy rates and a poor response to gonadotrophin stimulation during in-vitro fertilization (IVF) treatment. The purpose of this retrospective pharmacokinetic study was to assess the diffusion of exogenous human chorionic gonadotrophin (HCG) in patients with peri-ovarian adhesions by examining the concentration of exogenous HCG in the follicular fluid in patients undergoing down-regulation and IVF due to infertility. The patients underwent laparoscopic examination for the scoring of peri-ovarian adhesions (using the classification of adnexal adhesions adopted by the American Fertility Society, a score of 0 means no adhesions, and a score of 32 represents bilateral expanded dense adhesions). Oocytes were recovered after human menopausal gonadotrophin-human chorionic gonadotrophin (HMG-HCG) stimulation with gonadotrophin-releasing hormone agonist. Serum and follicular fluid were collected at the time of oocyte recovery for measuring the HCG ratio (the follicular HCG concentration to the serum HCG concentration; a reflection of the diffusion of exogenous gonadotrophin) by time-resolved fluoroimmunoassay. A negative correlation was found between the number of oocytes recovered and the peri-ovarian adhesion score (r = -0.62, P < 0.01). In a given patient, the follicular HCG concentration was always lower than the serum HCG at the time of oocyte recovery. The HCG ratio in all samples was 0.9 or less (0.51 +/- 0.20; range, 0.09-0.90). Significant negative correlations were found between the peri-ovarian adhesion score and both the follicular HCG concentration (r = -0.80, P < 0.01) and the HCG ratio (r = -0.75, P < 0.01). In conclusion, severe peri-ovarian adhesions interfered with the diffusion of exogenous gonadotrophin into the follicular fluid during IVF treatment. Thus, the diffusion of exogenous gonadotrophin into the follicular fluid may represent a new parameter in the assessment of ovarian blood flow and IVF outcome.