A neurokinin-1 receptor antagonist that reduces intra-abdominal adhesion formation decreases oxidative stress in the peritoneum

NFK prevent postoperative abdominal adhesion through downregulating the TGF-β1 signaling pathway

BACKGROUND

Postoperative abdominal adhesions (PAAs) represent a frequent condition occurring in more than 90% of patients undergoing abdomen and pelvic surgeries, which can cause chronic abdominal pain, female infertility, and repeated bowel obstruction, requiring repetitive surgical interventions causing morbidity and mortality, as well as high costs. It is therefore of paramount clinical importance and significance to develop practical and reliable strategies for preventing the occurrence of PAAs.

METHODS AND RESULTS

In this study, we demonstrated that Nianfukang (NFK, composed of polyethylene glycol 1450 and diclofenac sodium) is highly effective in preventing PAAs, likely by reducing leukocytes and inflammatory factors in the abdominal cavity, and inhibiting intestinal fibrosis in a rat model of PAAs induced by postoperative cecum scraping. We further uncovered that NFK downregulates the expression of TGF-β1, a key factor for adhesion formation, to suppress the TGF-β1/TGF-βRIII/Smad2 signaling pathway, thereby inhibiting the proliferation and migration of fibroblasts and provided evidences for the involvement of the TGF-β1/TGF-βRIII/Smad2 axis in the prevention of PAAs in normal human colon fibroblast CCD-18Co.

CONCLUSIONS

Our findings support NFK as a potential anti-adhesive product that has the advantages of significant effectiveness, safety profile, and low cost, as well as clear mechanism of action.

Cardioprotective action of aprepitant in a rat model of ischemia-reperfusioninduced myocardial injury: role of PI3K-AkT-GSK-3β-HIF-1α signaling pathway

PURPOSE

The present study explored the role and mechanism involved in aprepitant-induced cardioprotective effects in rat model of ischemia-reperfusion injury.

METHODS

The isolated hearts of Wistar male albino rats were subjected to ischemia-reperfusion injury on Langendorff apparatus. The extent of myocardial injury was assessed by measuring lactate dehydrogenase 1 and CK-MB release in the coronary effluent. The rats were treated with aprepitant (5, 10 and 20 mg/kg) before isolating hearts. After injury, the levels of HIF-1α, p-AkT, p-GSK-3β/GSK-3β were measured in heart homogenates. LY294002 was employed as PI3K inhibitor.

RESULTS

Ischemia-reperfusion led to significant myocardial injury and decreased the levels of HIF-1α, p-AkT and ratio of p-GSK-3β/GSK-3β. Aprepitant attenuated myocardial injury and restored the biochemical changes in a dose-dependent manner. Pre-treatment with LY294002 (10 and 20 mg/kg) abolished aprepitant-mediated cardioprotective effects and restored the biochemical parameters in the heart homogenate.

CONCLUSIONS

Aprepitant may be effective in preventing ischemia-reperfusion-induced myocardial injury, which may be due to activation of PI3K-AkT-GSK-3β and HIF-1α signaling pathway.

Local renin-angiotensin system molecular mechanisms in intrauterine adhesions formation following gynecological operations, new strategy for novel treatment

It has recently been proposed that local tissue renin-angiotensin system activation has a role in post-surgical adhesion. Intrauterine adhesions are scar tissues that form in the endometrial cavity causing the walls of the uterine to adhere together. Women, undergoing major gynecological surgery, are exposed to a high risk of adhesion formation. Post-operative uterine adhesion is associated with chronic pain and infertility that are important problems following post-operation uterine adhesion. A local renin-angiotensin system has been found in the organs of the female reproductive system, for example in the endometrium. Data about the physiological roles of local RAS in the gynecological tract are largely unknown, but dysfunctional local RAS in the endometrium may contribute to this pathological condition. Local AngII/AT1R may be over-activated after surgical injury or hypoxia leading to an up-regulation of the molecular mechanisms that may lead to a chronic immune response, oxidative stress, and increase the expression of fibrotic molecules like TGF-β to induce the risk of connective fibrotic tissues. Based on AngII/AT1R pathological potential to induce pelvic and uterine adhesions, using angiotensin receptor blockers could be a therapeutic strategy for the prevention and treatment of post-surgical adhesions.IMPACT STATEMENTWhat is already known on this subject? Intrauterine adhesions are described as fibrotic scar tissues following gynecological surgeries. It's reported that 55-100% of women are at risk of intrauterine adhesion after gynecological surgeries. Injury to tissues and hypoxia during the surgery, promote molecular mechanisms to contribute post-surgical adhesion. Recently evidence supports the existence of renin-angiotensin system components in the gynecological tract. Abnormal expression of local angiotensin II and AT1R in uterus tissue following gynecological surgeries up-regulate molecular mechanisms to induce post-operative adhesions.What do the results of this study add? Recently there has been an increased focus on the role of the local renin-angiotensin system in organ fibrosis. The results of this Mini-review article refer to the pathological roles of the local renin-angiotensin system in fibrotic bands formation after gynecological operations. Over-activation of local renin-angiotensin systems up-regulate molecular mechanisms such as inflammation and the TGF-β1 signalling pathway. TGF-β as a profibrotic molecule strongly induces the expression of some fibrotic molecules such as PAI and TIMP to increase the risk of intrauterine adhesions.What are the implications of these findings for clinical practice and/or further research? According to the biological roles of local renin-angiotensin system and AT1R following injuries to develop post-operative adhesion, the administration of ARBs may be considered as a new therapeutic strategy for the prevention of IUA.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

Genetic and Epidemiological Similarities, and Differences Between Postoperative Intraperitoneal Adhesion Development and Other Benign Fibro-proliferative Disorders

Intraperitoneal adhesions complicate over half of abdominal-pelvic surgeries with immediate, short, and long-term sequelae of major healthcare concern. The pathogenesis of adhesion development is similar to the pathogenesis of wound healing in all tissues, which if unchecked result in production of fibrotic conditions. Given the similarities, we explore the published literature to highlight the similarities in the pathogenesis of intra-abdominal adhesion development (IPAD) and other fibrotic diseases such as keloids, endometriosis, uterine fibroids, bronchopulmonary dysplasia, and pulmonary, intraperitoneal, and retroperitoneal fibrosis. Following a literature search using PubMed database for all relevant English language articles up to November 2020, we reviewed relevant articles addressing the genetic and epidemiological similarities and differences in the pathogenesis and pathobiology of fibrotic diseases. We found genetic and epidemiological similarities and differences between the pathobiology of postoperative IPAD and other diseases that involve altered fibroblast-derived cells. We also found several genes and single nucleotide polymorphisms that are up- or downregulated and whose products directly or indirectly increase the propensity for postoperative adhesion development and other fibrotic diseases. An understanding of the similarities in pathophysiology of adhesion development and other fibrotic diseases contributes to a greater understanding of IPAD and these disease processes. At a very fundamental level, blocking changes in the expression or function of genes necessary for the transformation of normal to altered fibroblasts may curtail adhesion formation and other fibrotic disease since this is a prerequisite for their development. Similarly, applying measures to induce apoptosis of altered fibroblast may do the same; however, apoptosis should be at a desired level to simultaneously ameliorate development of fibrotic diseases while allowing for normal healing. Scientists may use such information to develop pharmacologic interventions for those most at risk for developing these fibrotic conditions.

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.

Does the time from symptom onset to surgery affect the outcomes of patients with acute appendicitis? A prospective cohort study of 255 patients

INTRODUCTION

The objective of this study was to evaluate the impact of operative timing on outcomes of acute appendicitis.

METHODS

This study examined adult patients who had presented to the hospital with acute appendicitis and had undergone appendectomy from December 2017 to February 2019. Time delay and outcomes of perforated and non-perforated appendicitis were compared. Patients were classified into five groups based on the period from symptom onset to operation: group 1, <24 hours; group 2, ≥24 and <48 hours; group 3, ≥48 and <72 hours; group 4, ≥72 and <96 hours; and group 5, ≥96 hours. The five groups were compared, with risk of perforation assessed in particular.

RESULTS

A total of 255 patients were included in the analysis. Symptom duration, operative time, and length of postoperative hospital stay (P < .001) were significantly longer in the perforated group (n = 49) than in the non-perforated group (n = 206). The perforated group also had a higher conversion rate to open procedures (P = .002) and a higher rate of wound infection (P = .034). Group 1 had 53 patients, group 2 had 95 patients, group 3 had 57 patients, group 4 had 32 patients, and group 5 had 18 patients. The incidence of appendiceal perforation and median operative time progressively increased along with symptom duration in the five groups. In multivariate analyses, independent risk factors for appendiceal perforation were male gender (odds ratio = 2.33, 95% confidence interval [CI]: 1.07-5.08) and symptom duration ≥48 hours (relative to ≥24 and <48 hours) (odds ratio = 4.64, 95%CI: 1.76-12.27). Patients with symptom duration ≥72 hours had a significantly longer operative time than those with symptom duration ≥48 and <72 hours (β = 21.38, 95%CI: 5.66-37.11, P = .008).

CONCLUSION

The risk of perforation increased significantly 48 hours after the onset of appendicitis. Symptoms duration ≥72 hours was associated with a longer operative time.

Preoperative and perioperative intervention reduces the risk of recurrence of endometriosis in mice caused by either incomplete excision or spillage and dissemination

RESEARCH QUESTION

Can preoperative or perioperative intervention reduce the risk of recurrence of endometriosis caused by either incomplete excision or spillage and dissemination?

DESIGN

A mouse model of endometriosis recurrence caused by spillage and dissemination was first established using 24 female Balb/c mice. The spillage and dissemination model was used to test the efficacy of preoperative use of ketorolac, perioperative use of aprepitant and combined use of propranolol and andrographolide in a prospective, randomized mouse experiment involving 75 mice. The efficacy of these preoperative and perioperative interventions in a mouse recurrence model caused by incomplete excision was also tested using 72 mice. In all experiments, the baseline body weight and hotplate latency of all mice were measured and recorded before the induction of endometriosis, before the primary surgery and before sacrifice. In addition, all lesions were excised, weighed and processed for quantification and immunohistochemistry analysis of E-cadherin, α-SMA, VEGF, ADRB2 and putative markers of recurrence PR-B, p-p65, as well as Masson trichrome staining.

RESULTS

All interventions substantially and significantly suppressed the outgrowth of endometriotic lesions and reduced the risk of recurrence caused by either spillage and dissemination or incomplete excision (P = 0.0007 to 0.042). These interventions also significantly attenuated the generalized hyperalgesia, inhibited the staining of α-SMA, p-p65, VEGF and ADRB2 but increased staining of E-cadherin and PR-B, resulting in reduced fibrosis.

CONCLUSION

Given the excellent safety profiles of these drugs, these data strongly suggest that preoperative and perioperative intervention may potentially reduce the risk of endometriosis recurrence effectively.

The Effect of SP/NK1R on the Expression and Activity of Catalase and Superoxide Dismutase in Glioblastoma Cancer Cells

Introduction

Glioblastoma is the most malignant brain tumor with different therapeutic protocols, including surgery, radiotherapy, and chemotherapy. Substance P (SP), a peptide released by sensory nerves, increases cellular excitability by activating the neurokinin-1 receptor (NK1R) in several human tumor cells. Aprepitant is a potent and long-lasting NK1R antagonist, considered a new agent for inhibiting proliferation and induction of apoptosis in malignant cells. This study aimed to evaluate the effects of the SP/NK1R system on the expression and activity of catalase and superoxide dismutase (SOD) in the glioblastoma U87 cancer cell line.

Methods

Cytotoxicity was measured by the resazurin test, 24 hours after treatment, with increasing aprepitant concentrations. The production of reactive oxygen species (ROS) was also measured 24 hours after treatment with SP and aprepitant. Enzymes activity of catalase and SOD was measured using the corresponding assay kits. Real-time PCR also measured their expression.

Results

Aprepitant significantly reduced the viability of U87 cells in a concentration-dependent manner. ROS production was significantly reduced, and the activity of catalase and SOD increased after treatment with aprepitant. The expression of catalase and SOD enzymes also increased significantly in the presence of aprepitant.

Conclusion

The present study showed that aprepitant inhibited SP's oxidizing effects via inducing the antioxidant effects of catalase and SOD in the U87 cell line. Therefore, this drug might be introduced as a potential candidate for controlling glioblastoma cancer in animal models and clinical trials.

Is There a Genetic Predisposition to Postoperative Adhesion Development?

Adhesions are permanent fibrovascular bands between peritoneal surfaces, which develop following virtually all body cavity surgeries. The susceptibility to develop, and the severity, of adhesions following intra-abdominal surgery varies within and between individuals, suggesting that heritable factors influence adhesion development. In this manuscript, we discuss the pathophysiology of adhesion development from the perspective of genetic susceptibility. We restrict our discussion to genes and single-nucleotide polymorphisms (SNPs) that are specifically involved in, or that cause modification of, the adhesion development process. We performed a literature search using the PubMed database for all relevant English language articles up to March 2020 (n = 186). We identified and carefully reviewed all relevant articles addressing genetic mutations or single-nucleotide polymorphisms (SNPs) that impact the risk for adhesion development. We also reviewed references from these articles for additional information. We found several reported SNPs, genetic mutations, and upregulation of messenger RNAs that directly or indirectly increase the propensity for postoperative adhesion development, namely in genes for transforming growth factor beta, vascular endothelial growth factor, interferon-gamma, matrix metalloproteinase, plasminogen activator inhibitor-1, and the interleukins. An understanding of genetic variants could provide insight into the pathophysiology of adhesion development. The information presented in this review contributes to a greater understanding of adhesion development at the genetic level and may allow modification of these genetic risks, which may subsequently guide management in preventing and treating this challenging complication of abdominal surgery. In particular, the information could help identify patients at greater risk for adhesion development, which would make them candidates for anti-adhesion prophylaxis. Currently, agents to reduce postoperative adhesion development exist, and in the future, development of agents, which specifically target individual genetic profile, would be more specific in preventing intraperitoneal adhesion development.

Prevention of Intra-abdominal Adhesions by Electrical Stimulation

The study investigated the ability of transdermal electric stimulation to prevent the formation of intra-abdominal adhesions in the combination with Seprafilm^® (anti-adhesive agent). One hundred and twenty-eight (128) rabbits were subjected to a surgical procedure to simulate the adhesion processes. After the simulation, the animals were divided into 4 groups (32 animals each), depending on the application of the methods of prevention: (1) control group (no anti-adhesives or electro-stimulation) (CG); (2) comparison group (applications of Seprafilm^®) (SF); (3) comparison group 2 (transdermal electric stimulation of the abdominal muscles) TES; (4) group (transdermal electric stimulation + Seprafilm^®) (TES + SF). We observed that the application of the Seprafilm^® alone led to a significant decrease in the adhesive process compared to the control group (CG) (p < 0.01). The adhesion process in the group underwent transdermal electrical stimulation (TES) was significantly lower compared to the Seprafilm^® group (SF) (p ≤ 0.05). The results demonstrated a significant decrease in the adhesion processes in the SF + TES group on days 1, 3, 7 and 14 in comparison with the CG group (p = 0.001), SF group (p = 0.001) and TES group (p = 0.01) group of animals. This study showed the efficacy of transdermal electrical muscle stimulation for the prevention of intra-abdominal adhesions. Moreover, the combination of Seprafilm^® anti-adhesion agent and electrical muscle stimulation resulted in the complete absence of adhesions. Our findings indicate the potential of such strategy for further clinical application.

Pharmacological Mobilization and Recruitment of Stem Cells in Rats Stops Abdominal Adhesions After Laparotomy

Adhesions are a very common complication in the abdominal surgery. Animal studies and human trials have evaluated strategies designed to reduce and prevent postsurgical adhesions but few have an evidence base that justifies routine use. A strategy to prevent adhesions effectively remains an urgent need. We studied a reproducible model of intra-peritoneal adhesion formation in rats using laparotomy with several peritoneal sutures to produce the adhesions. Here we show that entraining endogenous stem cells into injury sites using the combined effect of AMD3100 and low-dose FK-506 (AF) can reduce the adhesion score significantly and abolish peritoneal adhesions in 45% of animals in a rat model of severe postsurgical intra-abdominal adhesions, compared with saline controls. Searching for mechanisms, we found AF treatment dramatically increased SDF-1 expressing cells, HGF expressing Ym1+ M2 macrophages and CD133+ stem cells in the injury sites of peritoneal surface at day 5 post-operation. Our results demonstrate that medically induced recruitment of autologous stem cells using AF significantly reduced postsurgical intra-abdominal adhesions. These findings suggest a novel effective therapeutic approach to preventing adhesions in patients.

Substance P enhances tissue factor release from granulocyte-macrophage colony-stimulating factor-dependent macrophages via the p22phox/β-arrestin 2/Rho A signaling pathway

Granulocyte-macrophage colony stimulating factor (GM-CSF) induces procoagulant activity of macrophages. Tissue factor (TF) is a membrane-bound glycoprotein and substance P (SP) is a pro-inflammatory neuropeptide involved in the formation of membrane blebs. This study investigated the role of SP in TF release by GM-CSF-dependent macrophages. SP significantly decreased TF levels in whole-cell lysates of GM-CSF-dependent macrophages. TF was detected in the culture supernatant by enzyme-linked immunosorbent assay after stimulation of macrophages by SP. Aprepitant (an SP/neurokinin 1 receptor antagonist) reduced TF release from macrophages stimulated with SP. Pretreatment of macrophages with a radical scavenger(pyrrolidinedithiocarbamate) also limited the decrease of TF in whole-cell lysates after stimulation with SP. A protein kinase C inhibitor (rottlerin) partially blocked this macrophage response to SP, while it was significantly inhibited by a ROCK inhibitor (Y-27632) or a dynamin inhibitor (dinasore). An Akt inhibitor (perifosine) also partially blocked this response. Furthermore, siRNA targeting p22phox, β-arrestin 2, or Rho A, blunted the release of TF from macrophages stimulated with SP. In other experiments, visceral adipocytes derived from cryopreserved preadipocytes were found to produce SP. In conclusion, SP enhances the release of TF from macrophages via the p22phox/β-arrestin 2/Rho A signaling pathway.

Combined intraoperative administration of a histone deacetylase inhibitor and a neurokinin-1 receptor antagonist synergistically reduces intra-abdominal adhesion formation in a rat model

BACKGROUND

Intra-abdominal adhesions are the most frequent postoperative complication after abdominopelvic surgery. Our laboratory has previously shown that an intraoperative peritoneal lavage containing either the histone deacetylase inhibitor valproic acid (VPA) or a neurokinin-1 receptor antagonist (NK-1RA) reduced adhesions by approximately 50% in a rat model. The objective of this study was to determine whether the combination of these 2 drugs was more effective in reducing adhesions than either alone.

METHODS

Rats underwent laparotomy with creation of peritoneal ischemic buttons to induce adhesions. A single dose of VPA (25 mg/kg), NK-1RA (50 mg/kg), a combination of both, or 0.9% saline was lavaged intraperitoneally just before wound closure. On postoperative day 7, adhesions were quantified. To investigate early mechanisms of adhesiogenesis, adhesions were created as described and adhesive button tissue was harvested at 30 minutes and 3 hours postoperatively and fibrinogen and vascular endothelial growth factor (VEGF) protein levels, both indices of peritoneal extravasations, were determined by Western blot analysis. Peritoneal fluid was collected in similar experiments at 30 minutes, and 3 and 6 hours to measure fibrinolytic activity, an index of the ability of the peritoneum to degrade fibrinous adhesions.

RESULTS

The coadministration of VPA plus NK-1RA reduces adhesions by 72.6% relative to saline (P < .001); this reduction was greater than either compound alone (P < .001). Peritoneal fibrinolytic activity was significantly increased at 3 and 6 hours postoperatively in animals administered the combination therapy versus saline (P = .01). VPA plus NK-1RA significantly decreased fibrinogen and VEGF protein levels at 3 and 6 hours compared with saline controls.

CONCLUSION

These results suggest that a combined pharmacologic approach targeting multiple adhesiogenic pathways provides optimal adhesion prevention.

Histological analysis of the effects of anti-adhesive haemostatic agents on the middle ear of the guinea pig

INTRODUCTION

Adhesion formation is a frequent and serious post-operative problem in ENT surgery. This study assessed the effect of two anti-adhesive haemostatic agents on an experimental guinea pig model.

MATERIALS AND METHODS

The middle-ear mucosa of 14 guinea pigs was exposed to surgical trauma. After surgery, Arista™ AH was injected into the right middle ear of seven animals, while Ankaferd Blood Stopper was injected into the right middle ear of the other seven animals. The left ears were left untreated and regarded as the control group. The three groups were compared by histological examination at post-operative week 4.

RESULTS

In each of the three groups, consolidation of the lamina propria and epithelium mucosae, increments in the number of active fibroblasts, collagen fibrils and inflammatory cells, and increased vascular dilation were observed on haematoxylin and eosin-stained sections, and were more prominent in the control and Ankaferd Blood Stopper groups. Epithelial thickness and capillary vasodilation were significantly lower in the Arista™ AH group compared with the control and Ankaferd Blood Stopper groups (p < 0.008).

CONCLUSION

Arista™ AH may prevent the formation of adhesions in middle-ear surgery. Further experimental studies are required to determine its ototoxic potential.

The neurokinin 1 receptor regulates peritoneal fibrinolytic activity and postoperative adhesion formation

BACKGROUND

Intra-abdominal adhesions are a common source of postoperative morbidity. Previous studies in our laboratory have shown that a neurokinin 1 receptor antagonist (NK-1RA) reduces abdominal adhesion formation and increases peritoneal fibrinolytic activity. However, the cellular pathway by which the antagonist exerts its effects is unclear, as cultured peritoneal mesothelial cells exposed to the NK-1RA show increases in fibrinolytic activity despite having very low expression of neurokinin 1 receptor (NK-1R) messenger RNA and protein. Our aim was to determine whether the NK-1R plays an essential role in the adhesion-reducing effects of the NK-1RA, or if the NK-1RA is acting independently of the receptor.

METHODS

Homozygous NK-1R knockout mice and age matched wild-type mice underwent laparotomy with cecal cautery to induce adhesions. At the time of surgery, mice received a single intraperitoneal dose of either NK-1RA (25 mg/kg) or saline alone. Adhesion severity at the site of cecal cautery was assessed on postoperative day 7. In a separate experiment, peritoneal fluid was collected from wild type and NK-1R knockout mice 24 h after laparotomy with cecal cautery and administration of either NK-1RA or saline. Tissue plasminogen activator levels, representative of total fibrinolytic activity, were then measured in peritoneal fluid.

RESULTS

In wild-type mice, NK-1RA administration significantly decreased adhesion formation compared with saline controls. Among the NK-1R knockout mice, there was no significant reduction in adhesion formation by the NK-1RA. Fibrinolytic activity increased 244% in wild-type mice administered NK-1RA compared with saline controls; however, the NK-1RA did not raise fibrinolytic activity above saline controls in NK-1R knockout mice.

CONCLUSIONS

These data indicate that the NK-1R mediates the adhesion-reducing effects of the NK-1RA, in part, by the upregulation of peritoneal fibrinolysis, and suggest that the NK-1R is a promising therapeutic target for adhesion prevention.

Interferon γ and plasminogen activator inhibitor 1 regulate adhesion formation after partial hepatectomy

BACKGROUND

The pathophysiology of intra-abdominal adhesions has not been studied extensively. The aim of this study was to elucidate the molecular mechanisms underlying adhesion formation in a murine model and in patients undergoing hepatectomy.

METHODS

Partial hepatectomy was performed using bipolar forceps in mice. Wild-type mice, antibodies to CD4 and interferon (IFN) γ, IFN-γ, natural killer T (NKT) cells and plasminogen activator inhibitor (PAI) 1 knockout (KO) mice were used. Recombinant hepatocyte growth factor (HGF) was tested for its ability to prevent adhesions. Liver specimens were obtained during surgery from patients undergoing hepatectomy. Adhesion formation was evaluated using a scoring system that ranged from 0 (no adhesions) to 5 (severe adhesions). Levels of IFN-γ and PAI-1 mRNA, and protein concentration of PAI-I were measured, and fluorescence immunostaining was performed.

RESULTS

Adhesion formation depended on IFN-γ produced by NKT cells, and NKT KO mice developed few adhesions (mean(s.d.) 1·7(0·3) versus 4·6(0·4) in wild-type mice; P = 0·037). In wild-type mice, the level of PAI-1 mRNA increased after hepatectomy, followed by a decrease in the tissue plasminogen activator (tPA) mRNA level. Adhesion formation was inhibited completely in PAI-1 KO mice (0(0) versus 4·1(0·8) in wild-type mice; P = 0·002). HGF inhibited formation of abdominal adhesions after hepatectomy by reducing IFN-γ and PAI-1 levels, and increasing tPA levels compared with those in mice treated with phosphate-buffered saline (P < 0·001, P = 0·002 and P = 0·035 respectively). In human liver specimens, NKT cells accumulated in the liver after hepatectomy, and PAI-1 expression was increased 5·25-fold (P = 0·030).

CONCLUSION

IFN-γ is a key molecule for abdominal adhesion formation after hepatectomy, acting via the reciprocal balance of PAI-1 and tPA. This molecular mechanism may also regulate adhesion formation in patients following hepatectomy. HGF inhibited formation of adhesions by regulating IFN-γ and PAI-1, suggesting that it may be an important target for prevention of adhesions after hepatectomy. SURGICAL RELEVANCE: Postoperative intra-abdominal adhesions can be asymptomatic or cause significant morbidity and mortality. Adhesion formation after hepatectomy has not been studied extensively. In the present study, the molecular mechanisms underlying intra-abdominal adhesions after hepatectomy were investigated in a murine model and in patients. Interferon (IFN) γ produced by natural killer T cells is a key molecule for adhesion formation after hepatectomy in mice, acting via the reciprocal balance between plasminogen activator inhibitor (PAI) 1 and tissue plasminogen activator, the pivotal factors in fibrinolytic activity. This mechanism was also involved in the regulation of adhesions in human tissue samples. Hepatocyte growth factor (HGF) strongly inhibited adhesion formation by regulating IFN-γ and PAI-1. These results indicate that IFN-γ and PAI-1 are possible therapeutic targets, and HGF could prevent postoperative adhesion formation after hepatectomy.

Advances in the Pathogenesis of Adhesion Development: The Role of Oxidative Stress

Over the past several years, there has been increasing recognition that pathogenesis of adhesion development includes significant contributions of hypoxia induced at the site of surgery, the resulting oxidative stress, and the subsequent free radical production. Mitochondrial dysfunction generated by surgically induced tissue hypoxia and inflammation can lead to the production of reactive oxygen and nitrogen species as well as antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase which when optimal have the potential to abrogate mitochondrial dysfunction and oxidative stress, preventing the cascade of events leading to the development of adhesions in injured peritoneum. There is a significant cross talk between the several processes leading to whether or not adhesions would eventually develop. Several of these processes present avenues for the development of measures that can help in abrogating adhesion formation or reformation after intraabdominal surgery.

Current strategies and future perspectives for intraperitoneal adhesion prevention

INTRODUCTION

The formation of peritoneal adhesions still is a relevant clinical problem after abdominal surgery. Until today, the most important clinical strategies for adhesion prevention are accurate surgical technique and the physical separation of traumatized serosal areas. Despite a variety of barriers which are available in clinical use, the optimal material has not yet been found.

DISCUSSION

Mesothelial cells play a crucial physiological role in friction less gliding of the serosa and the maintenance of anantiadhesive surface. The formation of postoperative adhesions results from a cascade of events and is regulated by various cellular and humoral factors. Therefore, optimization or functionalization of barrier materials by developments interacting with this cascade on a structural or pharmacological level could give an innovative input for future strategies in peritoneal adhesion prevention. For this purpose, the proper understanding of the formal pathogenesis of adhesion formation is essential. Based on the physiology of the serosa and the pathophysiology of adhesion formation, the available barriers in current clinical practice as well as new innovations are discussed in the present review.

Postoperative adhesion development following cesarean and open intra-abdominal gynecological operations: a review

In this review, we discuss the pathophysiology of adhesion development, the impact of physiological changes associated with pregnancy on markers of adhesion development, and the clinical implications of adhesion development following cesarean delivery (CD). Although peritoneal adhesions develop after the overwhelming majority of intra-abdominal and pelvic surgery, there is evidence in the literature that suggests that patients having CD may develop adhesions less frequently. However, adhesions continue to be a concern after CD, and are likely significant, albeit on average less than after gynecological operations, but with potential to cause significant delay in the delivery of the baby with serious, lifelong consequences. Appreciation of the pathophysiology of adhesion development described herein should allow a more informed approach to the rapidly evolving field of intra-abdominal adhesions and should serve as a reference for an evidence-based approach to consideration for the prevention and treatment of adhesions.

Peritoneal adhesions in human and veterinary medicine: from pathogenesis to therapy. A review

Any peritoneal inflammatory process consequent to infections or surgical injuries may induce abdominal adhesion formation. Peritoneal adhesions are connective laciniae that develop among abdomino-pelvic organs that limit physiologic visceral motion. Consequently, fertility may be impaired, and intestinal obstruction and pelvic pain may develop, mainly in subjects that had undergone gynaecological surgery. This review illustrates the pathogenic steps of adhesiogenesis and the therapeutic scenario that evolved over the years to tackle the threat of peritoneal adhesions, both in domestic animals and in women.

Intra-abdominal adhesions: definition, origin, significance in surgical practice, and treatment options

BACKGROUND

Intra-abdominal adhesions arise after more than 50% of all abdominal operations and are an important source of postoperative complications. They attach normally separated organs to each other and can cause major problems for the affected patients by giving rise to small bowel obstruction, chronic pelvic pain, dyspareunia, infertility, and higher complication rates in subsequent operations. They are also a frequent source of medicolegal conflict. Thus, every physician should be familiar with their mechanism of origin, their consequences, and the methods by which they can be prevented.

METHODS

A selective PubMed/Medline search from 1960 onward as well as articles to which these publications referred. The expert consensus position of the European Society for Gynaecological Surgery is also taken into consideration.

RESULTS

Adhesions arise through aberrant wound healing after peritoneal injury with further influence from a variety of other factors. Preventive measures include minimizing peritoneal injury intraoperatively through the meticulous observance of basic surgical principles, moistening the mesothelium to keep it from drying out, irrigating the peritoneal cavity to remove blood and clot, and keeping the use of intra-abdominal foreign material to a minimum.

CONCLUSION

Adhesions are an inevitable consequence of intra-abdominal surgery. They can be prevented to some extent with meticulous surgical technique and certain other measures. For operations carrying a high risk of postoperative adhesions, e.g., surgery on the adnexa or bowel, commercially available peritoneal instillates or barrier methods can be used to limit adhesion formation.

Peritoneal damage: the inflammatory response and clinical implications of the neuro-immuno-humoral axis

BACKGROUND

The peritoneum is a bilayer serous membrane that lines the abdominal cavity. We present a review of peritoneal structure and physiology, with a focus on the peritoneal inflammatory response to surgical injury and its clinical implications.

METHODS

We conducted a nonsystematic clinical review. A search of the Ovid MEDLINE database from 1950 through January 2009 was performed using the following search terms: peritoneum, adhesions, cytokine, inflammation, and surgery.

RESULTS

The peritoneum is a metabolically active organ, responding to insult through a complex array of immunologic and inflammatory cascades. This response increases with the duration and extent of injury and is central to the concept of surgical stress, manifesting via a combination of systemic effects, and local neural pathways via the neuro-immuno-humoral axis. There may be a decreased systemic inflammatory response after minimally invasive surgery; however, it is unclear whether this is due to a reduced local peritoneal reaction.

CONCLUSIONS

Interventions that dampen the peritoneal response and/or block the neuro-immuno-humoral pathway should be further investigated as possible avenues of enhancing recovery after surgery, and reducing postoperative complications.