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

Prevention strategies of postoperative adhesion in soft tissues by applying biomaterials: Based on the mechanisms of occurrence and development of adhesions

Postoperative adhesion (POA) widely occurs in soft tissues and usually leads to chronic pain, dysfunction of adjacent organs and some acute complications, seriously reducing patients' quality of life and even being life-threatening. Except for adhesiolysis, there are few effective methods to release existing adhesion. However, it requires a second operation and inpatient care and usually triggers recurrent adhesion in a great incidence. Hence, preventing POA formation has been regarded as the most effective clinical strategy. Biomaterials have attracted great attention in preventing POA because they can act as both barriers and drug carriers. Nevertheless, even though much reported research has been demonstrated their efficacy on POA inhibition to a certain extent, thoroughly preventing POA formation is still challenging. Meanwhile, most biomaterials for POA prevention were designed based on limited experiences, not a solid theoretical basis, showing blindness. Hence, we aimed to provide guidance for designing anti-adhesion materials applied in different soft tissues based on the mechanisms of POA occurrence and development. We first classified the postoperative adhesions into four categories according to the different components of diverse adhesion tissues, and named them as "membranous adhesion", "vascular adhesion", "adhesive adhesion" and "scarred adhesion", respectively. Then, the process of the occurrence and development of POA were analyzed, and the main influencing factors in different stages were clarified. Further, we proposed seven strategies for POA prevention by using biomaterials according to these influencing factors. Meanwhile, the relevant practices were summarized according to the corresponding strategies and the future perspectives were analyzed.

Post-Operative Adhesions: A Comprehensive Review of Mechanisms

Post-surgical adhesions are common in almost all surgical areas and are associated with significant rates of morbidity, mortality, and increased healthcare costs, especially when a patient requires repeat operative interventions. Many groups have studied the mechanisms driving post-surgical adhesion formation. Despite continued advancements, we are yet to identify a prevailing mechanism. It is highly likely that post-operative adhesions have a multifactorial etiology. This complex pathophysiology, coupled with our incomplete understanding of the underlying pathways, has resulted in therapeutic options that have failed to demonstrate safety and efficacy on a consistent basis. The translation of findings from basic and preclinical research into robust clinical trials has also remained elusive. Herein, we present and contextualize the latest findings surrounding mechanisms that have been implicated in post-surgical adhesion formation.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Epidemiology and Prevention of Postsurgical Adhesions Revisited

OBJECTIVE

To provide a comprehensive review of recent epidemiologic data on the burden of adhesion-related complications and adhesion prevention. Second, we elaborate on economic considerations for the application of antiadhesion barriers.

BACKGROUND

Because the landmark SCAR studies elucidated the impact of adhesions on readmissions for long-term complications of abdominal surgery, adhesions are widely recognized as one of the most common causes for complications after abdominal surgery. Concurrently, interest in adhesion prevention revived and several new antiadhesion barriers were developed. Although these barriers have now been around for more than a decade, adhesion prevention is still seldom applied.

METHODS

The first part of this article is a narrative review evaluating the results of recent epidemiological studies on adhesion-related complications and adhesion prevention. In part II, these epidemiological data are translated into a cost model of adhesion-related complications and the potential cost-effectiveness of antiadhesion barriers is explored.

RESULTS

New epidemiologic data warrant a shift in our understanding of the socioeconomic burden of adhesion-related complications and the indications for adhesion prevention strategies. Increasing evidence from cohort studies and systematic reviews shows that difficulties during reoperations, rather than small bowel obstructions, account for the majority of adhesion-related morbidity. Laparoscopy and antiadhesion barriers have proven to reduce adhesion formation and related morbidity. The direct health care costs associated with treatment of adhesion-related complications within the first 5 years after surgery are $2350 following open surgery and $970 after laparoscopy. Costs are about 50% higher in fertile-age female patients. Application of an antiadhesion barriers could save between $328 and $680 after open surgery. After laparoscopy, the costs impact ranges from $82 in expenses to $63 of savings.

CONCLUSIONS

Adhesions are an important cause for long-term complications in both open and laparoscopic surgery. Adhesiolysis during reoperations seems to impact adhesion-related morbidity most. Routine application of antiadhesion barriers in open surgery is safe and cost-effective. Application of antiadhesion barriers can be cost-effective in selected cases of laparoscopy. More research is needed to develop barriers suitable for laparoscopic use.

Mutant matrix metalloproteinase-9 reduces postoperative peritoneal adhesions in rats

INTRODUCTION

Postoperative peritoneal adhesions continue to be a major source of morbidity and occasional mortality. Studies have shown that matrix metalloproteinase-9 (MMP-9) levels are decreased postoperatively which may limits matrix degradation and participate in the development of peritoneal adhesions. In this proof-of-principle study, we evaluated the effect of gene therapy with catalytically inactive mutant MMP-9 on postoperative peritoneal adhesions in rats.

METHODS

Adenovirus encoding mutant MMP-9 (Ad-mMMP-9) or saline was instilled in the peritoneal cavity after cecal and parietal peritoneal injury in rats. Expression of mutant MMP-9 transcript was verified by sequencing. Adenovirus E4 gene expression, adhesion scores, MMP-9, tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and transforming growth factor-β1 (TGF-β1) expression were evaluated at sacrifice one week after treatment.

RESULTS

Both mutant MMP-9 transcripts and adenovirus E4 gene were expressed in Ad-mMMP-9 treated adhesions. Adhesions severity decreased significantly (p = 0.036) in the Ad-mMMP-9-treated compared with saline-treated adhesions. Expression of MMP-9 mRNA and protein were elevated (p = 0.001 and p = 0.029, respectively) in the Ad-mMMP-9-treated adhesions compared with saline-treated adhesions. While tPA levels were increased (p = 0.02) in Ad-mMMP-9 treated adhesions compared with saline-treated adhesions, TGF-β1 and PAI-1 levels were decreased (p = 0.017 and p = 0.042, respectively). No difference in mortality were found between groups (p = 0.64).

CONCLUSIONS

Mutant MMP-9 gene therapy effectively transduced peritoneal adhesions resulting in reduction of severity of primary peritoneal adhesions.

The distinguishing cellular and molecular features of the endometriotic ovarian cyst: from pathophysiology to the potential endometrioma-mediated damage to the ovary

BACKGROUND

Clinical data suggest that the presence of an ovarian endometrioma may cause per se damage to the surrounding otherwise healthy ovarian tissue. However, the basic research has so far done a limited job in trying to understand the potential detrimental effect of an endometrioma presence in the context of the ovarian physiology. We have reviewed the literature with the aim of characterizing the pathophysiology of the endometrioma focusing mostly on factors and mechanisms potentially affecting the surrounding, otherwise normal, ovarian tissue.

METHODS

Comprehensive searches of PUBMED were conducted to identify human studies published from 1991 to 2013 in the English language on the cellular and molecular characterization of the various endometrioma components.

RESULTS

An endometrioma contains free iron, reactive oxygen species (ROS), proteolytic enzymes and inflammatory molecules in concentrations from tens to hundreds of times higher than those present in peripheral blood or in other types of benign cysts. The cyst fluid causes substantial changes in the endometriotic cells that it baths from gene expression modifications to genetic mutations The physical barrier between the cyst contents and the normal ovarian tissue is a thin wall composed of the ovarian cortex itself or fibroreactive tissue. ROS potentially permeating the surrounding tissues and proteolytic substances degrading the adjacent areas are likely to cause the substitution of normal ovarian cortical tissue with fibrous tissue in which the cortex-specific stroma is reduced. The fibrosis is associated with smooth muscle metaplasia and followed by follicular loss and intraovarian vascular injury. Follicular density in tissue surrounding the endometriotic cyst was consistently shown to be significantly lower than in healthy ovaries but this pathological change does not appear to be caused by the stretching of surrounding tissues owing to the presence of a cyst.

CONCLUSIONS

There is sufficient molecular, histological and morphological evidence, in part deriving from knowledge of the pathophysiology, to support a deleterious effect of the endometrioma on the adjacent ovarian cortical tissue, independent of the mere mechanical stretching owing to its size.

Prevention of peritoneal adhesions: a promising role for gene therapy

Adhesions are the most frequent complication of abdominopelvic surgery, yet the extent of the problem, and its serious consequences, has not been adequately recognized. Adhesions evolved as a life-saving mechanism to limit the spread of intraperitoneal inflammatory conditions. Three different pathophysiological mechanisms can independently trigger adhesion formation. Mesothelial cell injury and loss during operations, tissue hypoxia and inflammation each promotes adhesion formation separately, and potentiate the effect of each other. Studies have repeatedly demonstrated that interruption of a single pathway does not completely prevent adhesion formation. This review summarizes the pathogenesis of adhesion formation and the results of single gene therapy interventions. It explores the promising role of combinatorial gene therapy and vector modifications for the prevention of adhesion formation in order to stimulate new ideas and encourage rapid advancements in this field.

Adenovirus-mediated overexpression of human tissue plasminogen activator prevents peritoneal adhesion formation/reformation in rats

BACKGROUND

Tissue-plasminogen activator (tPA) demonstrated beneficial effects on peritoneal adhesion formation; however, its short half-life limits its continual fibrinolytic effect. Therefore, we delivered adenovirus encoding tPA to prevent adhesions.

METHODS

Rats were subjected to peritoneal injury and assigned to two protocols. In de novo adhesion protocol, adenovirus encoding human tPA gene (Ad-htPA) was instilled after peritoneal injury in group 1 (n = 22), whereas group 2 received phosphate-buffered saline (PBS) (n = 24). In recurrent adhesion protocol, group 1 (n = 15) received the same Ad-htPA dose after adhesiolysis and group 2 (n = 13) received PBS. Adhesion severity was scored 1 week after ad-htPA instillation. Adhesions were analyzed for htPA mRNA by reverse transcription-polymerase chain reaction and levels of htPA, and fibrinolytic inhibitors PAI-1, TIMP-1, and TGF-beta1 were measured using enzyme-linked immunosorbent assay.

RESULTS

htPA mRNA and protein were only expressed in adhesions from treated groups. A reduction in adhesion scores (P < .01) and in fibrinolytic inhibitors (P < .001) occurred in the treatment groups. Also, negative correlation was found (r = -.69, P < .01) between adhesion scores and htPA protein, but a positive correlation was found (r = .90, P < .01) between adhesion score and fibrinolytic inhibitors. No bleeding or wound complications were encountered.

CONCLUSION

Administration of adenovector encoding htPA is safe and decreased de novo and recurrent peritoneal adhesions.

RNA interference targeting hypoxia inducible factor 1alpha reduces post-operative adhesions in rats

BACKGROUND

To investigate the use of RNA interference mediated gene down-regulation targeting hypoxia inducible factor 1alpha (HIF-1alpha) and plasminogen activator inhibitor 1 (PAI-1) in an effort to prevent abdominal adhesion formation.

MATERIALS AND METHODS

Real time PCR and a PAI-1 protein activity assay were used in vitro to determine the efficacy of small interfering RNAs (siRNAs). For in vivo experiments, 57 white female rats were operated to generate ischemic and serosal injury to the uterine horns, and treated with saline, siRNA(Lamin A/C) (negative control), siRNA(HIF-1alpha), siRNA(PAI-1), or siRNA(HIF-1alpha) plus siRNA(PAI-1). The cationic polyer poly(ethylenimine) (PEI) was used as the delivery vehicle for all siRNAs delivered in vivo. Adhesions were analyzed by a blinded surgeon 8 days post-surgery.

RESULTS

After in vitro transfection with siRNA, at least 69% gene down-regulation was obtained for all siRNAs tested. In vitro siRNA-mediated down-regulation of HIF-1alpha, PAI-1 or their simultaneous delivery resulted in a significant decrease of PAI-1 protein activity (at least P < 0.05). Administration of 4 nmol siRNA(HIF-1alpha)/PEI complexes after injury to the uterine horns achieved a statistical reduction of post-operative adhesion formation with a reduction by 52% (P < 0.05). Delivery of 4 nmol siRNA(PAI-1)/PEI complexes and the simultaneous delivery of 2 nmol siRNA(HIF-1alpha) plus 2 nmol siRNA(PAI-1), resulted in a reduction of abdominal adhesion by 36% and 42%, respectively, with the reduction being statistically significant when compared directly to the saline control (P < 0.01).

CONCLUSION

These data show that administration of siRNA/PEI complexes within the peritoneal cavity can be used to prevent post-operative abdominopelvic adhesions.

Female infertility and free radicals: potential role in adhesions and endometriosis

Free radicals are highly reactive molecules produced in the cell either as part of, or as end-products of, biochemical reactions that have crucial roles in the homeostasis of the organism. Thus, excess production or impaired elimination of free radicals leads to increased oxidative stress, which has been implicated in the development of several different disease states, including hypoxia-reperfusion injury, cancer, and aging. Peritoneal adhesions and endometriosis are relatively commonly identified in women, and are known to be associated with infertility without clearly understood pathophysiology. The prevention and treatment strategies of these conditions, both of which have tremendous propensity to recur, have not been completely established. The development of both disorders has been shown to be closely related to the presence of increased oxidative stress in the tissues. In this article, we review this relationship with reference to the mechanistic steps involved and their regulation. As our knowledge of both conditions expands, we believe there will be opportunities for specific steps to intervention in free radical metabolism to reduce and/or prevent further development of endometriosis and adhesions.

Molecular Characterization of Postoperative Adhesions: The Adhesion Phenotype

Postoperative adhesion development remains a very frequent occurrence, which is often unrecognized by surgeons because of limited ability to conduct early second-look laparoscopies. The consequences include infertility, pelvic pain, bowel obstruction, and difficult reoperative procedures. To date, approaches to limit adhesions primarily have involved barriers to separate tissue during reepithelization. Future progress in regulating adhesion development and tissue fibrosis likely will require an improved understanding of the molecular processes involved in normal peritoneal repair and its aberrations leading to adhesion development. We hypothesize that tissue hypoxia (in part resulting from tissue incision, fulguration, suture ligation, etc.) is the major inciting event, which leads to a coordinated series of molecular events that promote an inflammatory response leading to enhanced tissue fibrosis. These events are reduced plasminogen activator activity, extracellular matrix deposition, increased cytokine production, increased angiogenesis, and reduced apoptosis (programmed cell death). Improved understanding of these events and their regulation will provide the opportunity to regulate better postoperative adhesion development and tissue fibrosis, thereby reducing the morbidity and mortality they cause.

Regulation of matrix metalloproteinase-1 and tissue inhibitor of matrix metalloproteinase-1 by dichloroacetic acid in human fibroblasts from normal peritoneum and adhesions

OBJECTIVE

To examine the role of stimulation of aerobic metabolism on the differential expression of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), which are differentially regulated in fibroblasts isolated from normal human peritoneum and adhesions.

DESIGN

Tissue culture study.

SETTING

University research laboratory.

PATIENT(S)

Human fibroblasts cultures from normal peritoneum and adhesions that were exposed to dichloroacetic acid (DCA; 0 and 100 microg/mL) for 24 hours under normal and hypoxic conditions.

MAIN OUTCOME MEASURE(S)

Real-time reverse-transcription polymerase chain reaction of MMP-1, TIMP-1, and beta-actin.

RESULT(S)

Dichloroacetic acid stimulated peritoneal fibroblast MMP-1 mRNA expression under normoxic conditions; this stimulation was lost during hypoxia. In adhesion fibroblasts, DCA increased MMP-1 mRNA expression; this effect was reversed by hypoxia. Expression of TIMP-1 mRNA was insignificantly increased by DCA in normal peritoneal and adhesion fibroblasts under normoxic conditions; however under hypoxic conditions, DCA reduced TIMP-1 mRNA expression from both.

CONCLUSION(S)

Regulation of metabolic activity of peritoneal cells may provide a target for future interventions for reduction of development of postoperative adhesions, particularly as it relates to healing of peritoneal sites that did not previously have adhesions as opposed to sites that underwent lysis of preexistent adhesions.

Role of vascular endothelial growth factor and placental growth factor in basal adhesion formation and in carbon dioxide pneumoperitoneum-enhanced adhesion formation after laparoscopic surgery in transgenic mice

OBJECTIVE

To evaluate the role of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) in adhesion formation after laparoscopic surgery.

DESIGN

Prospective, randomized study.

SETTING

Academic research center.

ANIMAL(S)

Female wild-type mice and transgenic mice (n = 110), expressing exclusively VEGF-A(164) (VEGF-A(164/164)) or deficient for VEGF-B (VEGF-B(-/-)) or for PlGF (PlGF(-/-)).

INTERVENTION(S)

Adhesions were induced during laparoscopy. To evaluate "basal adhesions" and "CO(2) pneumoperitoneum-enhanced adhesions," the pneumoperitoneum was maintained for a minimum (10 minutes) or prolonged (60 minutes) period. The role of PlGF was also evaluated by administration of antibodies.

MAIN OUTCOME MEASURE(S)

Adhesions were blindly scored after 7 days.

RESULT(S)

In all wild-type mice, CO(2) pneumoperitoneum enhanced adhesion formation. In comparison with wild-type mice, basal adhesions were higher in VEGF-A(164/164) mice and similar in VEGF-B(-/-) and PlGF(-/-) mice. Pneumoperitoneum did not enhance adhesions in any of these transgenic mice. The effects observed in PlGF(-/-) mice were confirmed in PlGF antibody-treated mice.

CONCLUSION(S)

The data demonstrate that the VEGF family plays a role in adhesion formation and confirm that CO(2) pneumoperitoneum enhances adhesions. VEGF-A(164) has a direct role in basal adhesions. Absence of pneumoperitoneum-enhanced adhesions in VEGF-A(164/164), VEGF-B(-/-), and PlGF(-/-) mice indicates up-regulation of VEGF-A(164), VEGF-B, and PlGF by CO(2) pneumoperitoneum as a mechanism for pneumoperitoneum-enhanced adhesion formation.

Differential expression of matrix metalloproteinase and tissue inhibitor of MMP in serosal tissue of intraperitoneal organs and adhesions

OBJECTIVE

To comparatively analyse the expression of matrix metalloproteinase (MMP-3) and tissue inhibitor of MMP (TIMP-2) in serosal tissue of intraperitoneal organs and adhesions, as well as peritoneal fluid and serum of subjects with and without adhesions.

DESIGN

Cross sectional study.

SETTING

Academic research centres.

SAMPLE

Patients undergoing abdominal/pelvic surgery.

METHODS

Messenger ribonucleic acid (mRNA) and protein expression using quantitative reverse transcription polymerase chain reaction (Q-RT-PCR), ELISA and immunohistochemistry.

RESULTS

All the tissues examined express MMP-3 and TIMP-2 mRNA and protein at consistently varying levels ranging from 100- to 1000-fold and 2- to 10-fold mRNA and protein, respectively. Serosa of uterine, fallopian tube, ovary and partial peritoneum express a higher MMP-3 mRNA compared with small and large bowels and omentum, while TIMP-2 expression was less variable with the highest level found in uterine serosa (P < 0.05). The expression of MMP-3 and TIMP-2 mRNA in adhesions was not significantly different compared with parietal peritoneum. MMP-3 and TIMP-2 protein content in tissue extracts, peritoneal fluids and serum also varied with higher TIMP-2 than MMP-3 (P < 0.05). TIMP-2 levels were lower in serum of subjects with moderate/extensive adhesions compared with subjects without adhesions. Immunoreactive MMP-3 and TIMP-2 proteins were detected in various cell types in these tissues. There was no correlation between MMP-3 and TIMP-2 expression, and age, gender or menstrual status of subjects with or without adhesions.

CONCLUSION

MMP-3 and TIMP-2 are expressed at varying levels in serosal tissues of peritoneal organs and adhesions, with higher TIMP-2 than MMP-3. Based on the knowledge that tissue injury alters the expression of MMPs and TIMPs, such variations may predispose an organ to develop more adhesions than others. In addition, the results suggest that serum level of TIMP-2 may represent a marker for subjects who will form adhesions with greater severity.

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.