Role of IL-17 and TGF-β in peritoneal adhesion formation after surgical trauma

Techniques for navigating postsurgical adhesions: Insights into mechanisms and future directions

Postsurgical adhesions are a common complication of surgical procedures that can lead to postoperative pain, bowel obstruction, infertility, as well as complications with future procedures. Several agents have been developed to prevent adhesion formation, such as barriers, anti-inflammatory and fibrinolytic agents. The Food and Drug Administration (FDA) has approved the use of physical barrier agents, but they have been associated with conflicting clinical studies and controversy in the clinical utilization of anti-adhesion barriers. In this review, we summarize the human anatomy of the peritoneum, the pathophysiology of adhesion formation, the current prevention agents, as well as the current research progress on adhesion prevention. The early cellular events starting with injured mesothelial cells and incorporating macrophage response have recently been found to be associated with adhesion formation. This may provide the key component for developing future adhesion prevention methods. The current use of physical barriers to separate tissues, such as Seprafilm®, composed of hyaluronic acid and carboxymethylcellulose, can only reduce the risk of adhesion formation at the end stage. Other anti-inflammatory or fibrinolytic agents for preventing adhesions have only been studied within the context of current research models, which is limited by the lack of in-vitro model systems as well as in-depth study of in-vivo models to evaluate the efficiency of anti-adhesion agents. In addition, we explore emerging therapies, such as gene therapy and stem cell-based approaches, that may offer new strategies for preventing adhesion formation. In conclusion, anti-adhesion agents represent a promising approach for reducing the burden of adhesion-related complications in surgical patients. Further research is needed to optimize their use and develop new therapies for this challenging clinical problem.

A combination of hybrid polydopamine-human keratinocyte growth factor nanoparticles and sodium hyaluronate for the efficient prevention of postoperative abdominal adhesion formation

Postoperative abdominal adhesion (PAA) is one of the more universal complications of abdominal surgery with a frequent incidence. Currently available keratinocyte growth factor (KGF)-based glues for the prevention of adhesions remain a great bottleneck since their long-term biological activity in vivo is insufficient. In this study, we fabricated hybrid polydopamine (PDA)-KGF nanoparticles (PDA-KGF NPs) by using an in situ self-assembly and polymerization method. The physicochemical properties of the PDA-KGF nanoparticles were systematically characterized. The effect of preventing PAA in rats was evaluated by using hybrid PDA-KGF NPs combined with hyaluronate (Ha). The expression levels of inflammatory factors and the degree of inflammatory cell infiltration in the injured peritoneum were evaluated by enzyme-linked immunosorbent assays and hematoxylin-eosin staining, respectively. The levels of phospho-Src expression were revealed by Western blotting. The degree of fibrosis and the density of deposited collagen fibers were measured with real-time reverse-transcription polymerase chain reaction and picrosirius red staining. The results indicated that the PDA-KGF NPs combined with Ha greatly prevented the incidence of abdominal adhesion s and promoted the repair of mesothelial cells in injured peritoneum. More importantly, the PDA-KGF NPs combined with Ha obviously reduced collagen deposition and fibrosis and inhibited the inflammatory response. Our results suggest that PDA-KGF NPs combined with Ha are promising barrier-like biomaterials for the effective prevention of postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: Postoperative abdominal adhesion (PAA) as an inevitable postoperative complication affected the quality of life of patients. Currently available methods for preventing adhesions mainly employ degradable biomaterials. Previous research demonstrated that a hybrid keratinocyte growth factor (KGF)-sodium hyaluronate (Ha) gel could prevent the formation of PAAs. However, its clinical outcomes are not satisfactory since their bioactivity in vivo is too short. In this article, we fabricated hybrid polydopamine (PDA)-KGF nanoparticles (PDA-KGF NPs), which extend KGF bioactivity, effectively prevent PAA. Moreover, PDA-KGF NPs could remarkably reduce both collagen deposition and fibrosis, inhibit the inflammatory response, and promote mesothelial regeneration. Overall, the PDA-KGF NPs combined with Ha exhibit efficient antiadhesion properties, may provide a promising clinical protocol for the prevention of PAA.

Role of peripheral inflammatory biomarkers, transforming growth factor-beta and interleukin 6 in predicting peritoneal adhesions following repeat cesarean delivery

BACKGROUND

Repeat cesarean deliveries (CDs) pose a risk in the development of intra-abdominal adhesions.

AIM

We aimed to examine the incidence and severity of adhesions in repeat CDs using a specific scoring system and assess the predictive power of the pre-operative value of transforming growth factor (TGF)-β and interleukin (IL)-6 with selected peripheral inflammatory biomarkers (PIBs) in the prediction of adhesion formation.

METHODS

This prospective study enrolled 91 pregnant women at term, who had previously undergone at least one or more scheduled CDs. PIBs, namely C-reactive protein, white blood cell count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and systemic immune-inflammation index, TGF-β, and IL-6 were studied according to the presence and location of adhesions.

RESULTS

There was a significant difference only in the variables of the number of CDs, post-operative adhesion index (PAI) score, IL-6, and TGF-β on the presence of adhesion (p < 0.05). The linear regression model revealed that the effect of the number of CDs, PAI score, and IL-6 values on TGF-β was significant (p < 0.05). The effect of the PAI score on TGF-β was higher than that of IL-6. As a reciprocal relationship, the effect of the TGF-β value on the PAI score was also higher than that of IL-6.

CONCLUSION

In patients with a history of repeat CDs, the preoperative determination of TGF-β seems to be an important independent predictor of POA. The adverse events due to post-operative adhesion caused by repeat CDs can be overcome by detecting high-risk patients with a comprehensive assessment and individualized intervention integrated into overall patient management.

Visceral fat-specific regulation of plasminogen activator inhibitor-1 in aged septic mice

Elevated plasma levels of plasminogen activator inhibitor-1 (PAI-1) are documented in patients with sepsis and levels positively correlate with disease severity and mortality. Our previous work demonstrated that visceral adipose tissues (VAT) are a major source of PAI-1, especially in the aged (murine endotoxemia), that circulating PAI-1 protein levels match the trajectory of PAI-1 transcript levels in VAT (clinical sepsis), and that PAI-1 in both VAT and plasma are positively associated with acute kidney injury (AKI) in septic patients. In the current study utilizing preclinical sepsis models, PAI-1 tissue distribution was examined and cellular sources, as well as mechanisms mediating PAI-1 induction in VAT, were identified. In aged mice with sepsis, PAI-1 gene expression was significantly higher in VAT than in other major organs. VAT PAI-1 gene expression correlated with PAI-1 protein levels in both VAT and plasma. Moreover, VAT and plasma levels of PAI-1 were positively associated with AKI markers, modeling our previous clinical data. Using explant cultures of VAT, we determined that PAI-1 is secreted robustly in response to recombinant transforming growth factor β (TGFβ) and tumor necrosis factor α (TNFα) treatment; however, neutralization was effective only for TNFα indicating that TGFβ is not an endogenous modulator of PAI-1. Within VAT, TNFα was localized to neutrophils and macrophages. PAI-1 protein levels were fourfold higher in stromal vascular fraction (SVF) cells compared with mature adipocytes, and among SVF cells, both immune and nonimmune compartments expressed PAI-1 in a similar fashion. PAI-1 was localized predominantly to macrophages within the immune compartment and preadipocytes and endothelial cells within the nonimmune compartment. Collectively, these results indicate that induction and secretion of PAI-1 from VAT is facilitated by a complex interaction among immune and nonimmune cells. As circulating PAI-1 contributes to AKI in sepsis, understanding PAI-1 regulation in VAT could yield novel strategies for reducing systemic consequences of PAI-1 overproduction.

Prevention of post-surgical adhesion bands by local administration of frankincense n-hexane extract

Background

and purpose: The formation of postoperative intra-abdominal adhesion band formation may lead to severe complications. This study aimed to evaluate the preventive effect of local administration of frankincense n-hexane extract (FHE) on the formation of postsurgical adhesion bands.

Materials and methods

FHE was extracted from the resin of a Boswellia sacra tree and its components were identified by gas chromatography-mass spectrometry (GC-MS). In an animal model, the expression levels of TNF-α and TGF-β1 cytokines after application of FHE were assessed to check the inflammatory and fibrotic cues, respectively.

Results

Following FHE compound analysis, in vivo experiments demonstrated that intraoperative local administration of FHE resulted in the prevention of adhesion band formation. The adhesion grades in the FHE-treated group were significantly lower than those in the negative control (NC) and the positive control (Interceed). The infiltration of inflammatory cells observed by histopathology revealed a significant anti-inflammatory potential of FHE. Furthermore, the gene expression results proved that significant suppression of TNF-α and TGF-β1 was responsible for its antiadhesion properties.

Conclusions

The study reported the potential of FHE as an ointment for the prevention of adhesion bands.

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Recognition of compounds with anti-inflammatory, antifibrotic activities in FHE using gas chromatography-mass spectrometry.

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The avoidance of adhesion bands formation, in vivo following intraoperative local administration of FHE.

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A notable anti-inflammatory potential of FHE detected by histopathology results.

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Approving the regulation of TNF-α and TGF-β1 involved in the intra-abdomen adhesion preventive properties of FHE.

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.

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.

Regulatory role of local tissue signal Del-1 in cancer and inflammation: a review

Developmental endothelial locus-1 (Del-1) is a secretory, multifunctional domain protein. It can bind to integrins and phosphatidylserine. As a local tissue signal, it plays a regulatory role in the cancer microenvironment and inflammation. Del-1 has destructive effects in most cancers and is associated with the progression and invasion of some cancers. In contrast, Del-1 also plays a protective role in inflammation. Del-1 regulates inflammation by regulating the generation of neutrophils in bone marrow, inhibiting the recruitment and migration of neutrophils and accelerating the clearance of neutrophils by macrophages. Del-1 and IL-17 are reciprocally regulated, and their balance maintains immune system homeostasis. Del-1 is expected to become a new therapeutic target for inflammatory disorders such as multiple sclerosis.

Standardised pomegranate peel extract lavage prevents postoperative peritoneal adhesion by regulating TGF-β and VEGF levels

Peritoneal adhesion represents a severe complication following surgery. Punica granatum (pomegranate) possesses several anti-oxidative and anti-inflammatory properties. Pomegranate peel extract (PPEx) can alleviate the production of various inflammatory factors and cytokines. Thus, we sought to evaluate the anti-adhesion effects of pomegranate in rats. Thirty male Wistar rats (6-week-old, 220 ± 20 g) were divided into five groups (n = 6): normal group without any surgical procedures, control group, and experimental groups receiving 2 ml of 1%, 2%, and 4% w/v PPEx, respectively. Peritoneal adhesions were examined macroscopically. Furthermore, we evaluated inflammatory cytokines levels [interleukin 6 (IL-6), and tumour necrosis factor-α (TNF-α)], growth factors [transforming growth factor- β1 (TGF-β1), and vascular endothelial growth factor (VEGF)], and oxidative stress parameters [nitric oxide metabolites (NO), and malondialdehyde (MDA), and glutathione (GSH)] using biochemical methods. Our results showed that the adhesion score and IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA levels were increased in the control group. In contrast, the GSH level was diminished in the control group compared with the normal group (P < 0.001). PPEx (1 and 2% w/v) markedly reduced all measured parameters compared with the control group (P < 0.001-0.05). PPEx may reduce peritoneal adhesion by alleviating adhesion formation, IL-6, TNF-α, TGF-β1, VEGF, NO, and MDA, and stimulating anti-oxidative factors. Therefore, PPEx may be considered an appropriate candidate for the treatment of postoperative peritoneal adhesion.

A review of physiological and cellular mechanisms underlying fibrotic postoperative adhesion

Postoperative adhesions (PA) are fibrotic tissues that are the most common driver of long-term morbidity after abdominal and pelvic surgery. The optimal drug or material to prevent adhesion formation has not yet been discovered. Comprehensive understanding of cellular and molecular mechanisms of adhesion process stimulates the design of future anti-adhesive strategies. Recently, disruption of peritoneal mesothelial cells were suggested as the 'motor' of PA formation, followed by a cascade of events (coagulation, inflammation, fibrinolysis) and influx of various immune cells, ultimately leading to a fibrous exudate. We showed that a variety of immune cells were recruited into adhesive peritoneal tissues in patients with small bowel obstruction caused by PA. The interactions among various types of immune cells contribute to PA development following peritoneal trauma. Our review focuses on the specific role of different immune cells in cellular and humoral mechanisms underpinning adhesion development.

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.

Regulation and function of IL-22 in peritoneal adhesion formation after abdominal surgery

Peritoneal adhesion occurs frequently after gastrointestinal/gynecological surgery. Tissue repair and regeneration are very important during this process. IL-22 is an important cytokine that is secreted from immune cells but functions on mesenchymal cells, such as mesothelial cells. The objective of this study was to investigate the roles of IL-22 and its regulators during adhesion formation. Postsurgical peritoneal drainage fluid from patients and rodent models was examined by enzyme-linked immunosorbent assay and fluorescence-activated cell sorting. It was observed that IL-22 expression in the abdominal cavity was rapidly induced 12 hours after surgery and then slowly decreased to a lower, steady level for up to 7 days after surgery. However, neutralizing IL-22 at the time point at which the highest level of expression was observed failed to reduce adhesion, but neutralizing IL-22 at a later time point, i.e., 3 days after surgery, prevented adhesion significantly. The IL-22 receptor was induced on the mesothelial membrane, and IL-22BP, an inhibitor of IL-22, was reduced 3 days after surgery. Furthermore, IFN-γ was identified to have the ability to induce IL-22R, and IL-18, which was induced by the infiltrating macrophages, was found to inhibit IL-22BP expression both in vivo and in vitro. Together, these data suggest that IL-22 may promote adhesion formation and that the regulation of IL-22, IL-22R, and IL-22BP may have therapeutic potential to prevent adhesion formation after surgery without disturbing the normal immune process.

Anti-interleukin-6 receptor antibody treatment ameliorates postoperative adhesion formation

Postoperative adhesion formation often ruins the quality of life or is an obstacle to illnesses with curative operation such as cancer. Previously we demonstrated that interferon-γ-promoted fibrin deposition drove postoperative adhesion formation. However, its underlying cellular and molecular mechanisms remain poorly understood. We found that myofibroblasts of the adhesion predominantly expressed signature molecules of mesothelial cells that line the serosa. Microarray analysis revealed IL-6 as a key underlying player, supported by elevated IL-6 levels in the peritoneal fluid of post-laparotomy human subjects. Injured serosa of cecum-cauterized mice also exhibited induction of Il6, which was followed by Tnf, concomitant with rapid accumulation of neutrophils, substantial population of which expressed TGF-β1, a master regulator of fibrosis. Besides, neutrophil-ablated mice showed reduction in induction of the adhesion, suggesting that TGF-β1⁺neutrophils triggered the adhesion. Human neutrophils expressed TGFB1 in response to TNF-α and TNF in response to IL-6. Moreover, anti-IL-6 receptor monoclonal antibody abrogated neutrophil recruitment and adhesion formation. Thus, IL-6 signaling represents a potential target for the prevention of postoperative adhesions.

Interleukin-17 pathways in systemic sclerosis-associated fibrosis

Fibrosis is unregulated tissue repair that may cause impairment of organ function, especially in end-organ damage. Systemic sclerosis (SSc) is the prototype systemic fibrosing disorder. Classical targets for fibrosis in SSc like transforming growth factor Beta (TGF-β), Interleukin-6 (IL-6), and multiple tyrosine kinases, have not yielded therapeutic benefit. There is multitude of evidence from across different tissues like the heart, lung, skin, liver, colon, and, to some extent, the kidney, that interleukin-17 (IL-17) and its downstream pathways are strongly associated with the initiation and propagation of fibrosis. Data from scleroderma patients, as well as from animal models of SSc, mirror these findings. Interestingly, hitherto unknown to be related to IL-17, newer molecules like Programmed Death-protein1 (PD-1), the phosphatase SHP2, along with known signal transducers like signal transducer and activator of transcription (STAT3), have been recently shown to be involved in the pathogenesis of fibrosis. Related molecules include the intracellular signalling molecules Ras/Erk, mammalian target organ of rapamycin (mTOR), and complement components. The biology of these pathways has not yet been fully elucidated to predict regulatory mechanisms, redundancies, and potential off-target effects. All these need to be better understood in the context of each other, in an effort to arrive at the optimal target to modulate fibrosis.

The Effect of Daikenchuto, Japanese Herbal Medicine, on Adhesion Formation Induced by Cecum Cauterization and Cecum Abrasion in Mice

Daikenchuto (DKT) has been widely used for the treatment of postsurgical ileus in Japan. However, its effect on postsurgical adhesion formation has been obscure. In this study, the effect of DKT on postsurgical adhesion formation induced by cecum cauterization or cecum abrasion in mice was investigated. First, the expression of adhesion-related molecules in damaged ceca was investigated by quantitative (q)RT-PCR. During 24 h after surgery, mRNA expressions of interferon-γ (IFN-γ), plasminogen activator inhibitor-1 (PAI-1), interleukin-17 (IL-17), and Substance P (SP) in cauterized ceca and those of PAI-1 and IL-17 in abraded ceca were significantly up-regulated. Next, the effect of DKT on adhesion formation macroscopically evaluated with adhesion scoring standards. DKT (22.5-67.5 mg/d) was administered orally for 7 d during the perioperative period, and DKT did not reduce adhesion scores in either the cauterization model (control : DKT 67.5 mg/d, 4.8 ± 0.2 : 4.8 ± 0.2) or in the abrasion model (control : DKT 67.5 mg/d, 4.9 ± 0.1 : 4.5 ± 0.3). Histologically, collagen deposition and leukocyte accumulation were found at the adhesion areas of control mice in both models, and DKT supplementation did not alleviate them. Last, effect of DKT on expression of proadhesion moleculs was evaluated. DKT also failed to down-regulate mRNA expression levels of them in damaged ceca of both models. In conclusion, PAI-1 and IL-17 may be key molecules of postsurgical adhesion formation. Collagen deposition and leukocytes accumulation are histological characteristic feature of post-surgical adhesion formation. DKT may not have any preventive effect on postsurgical adhesion formation in mice.

IL-17A contributes to perioperative neurocognitive disorders through blood-brain barrier disruption in aged mice

BACKGROUND

Perioperative neurocognitive disorders (PND) occur frequently after surgery, especially in aged patients. Surgery-induced neuroinflammation and blood-brain barrier (BBB) dysfunction play a crucial role in the pathogenesis of PND. Interleukin-17A (IL-17A) increases after surgical stress and will be involved in BBB dysfunction. However, the effect of IL-17A on BBB function during PND remains poorly understood.

METHODS

Male wild-type C57BL/6J mice (15 months old) received tibial fracture surgery and fixation to establish the PND model. All the mice were injected intraperitoneally with an IL-17A-neutralizing antibody (Abs) or isotype-control Abs 30 min before tibial fracture surgery. Animal behaviour tests conducted 24 h after surgery included the contextual fear conditioning and Y maze tests. Serum and hippocampus IL-17A levels and hippocampus IL-6 and IL-1β levels were detected by ELISA. BBB function was detected by Evans blue (EB) test. Hippocampus matrix metalloproteinase-2 (MMP-2)- and MMP-9-positive cells were detected by immunohistochemistry. Hippocampus albumin, occludin, claudin-5 and IL-17A receptors were detected by Western blot. For the in vitro experiment, bEnd.3 cells were incubated with IL-17A. Cell IL-17A receptors were detected by immunofluorescence. Cellular MMP-2, MMP-9, occludin, and claudin-5 were detected by Western blot.

RESULTS

Tibial fracture surgery promoted memory impairment, increased levels of IL-17A and IL-17A receptors, inflammatory factor production and BBB dysfunction. IL-17A Abs inhibited this effect, including improving memory function, decreasing inflammatory factor production and alleviating BBB disruption, indicated by decreased tight junctions (TJs) and increased MMPs after surgery. The in vitro study suggested that recombinant IL-17A could upregulate the expression of IL-17A receptors, decrease TJs and increase the level of MMPs in bEnd.3 cells.

CONCLUSIONS

Our results suggested that IL-17A-promoted BBB disruption might play an important role in the pathogenesis of PND.

TGF-β and inflammatory blood markers in prediction of intraperitoneal adhesions

PURPOSE

Intraperitoneal adhesions (IA) develop as a consequence of the healing process in peritoneum injured during surgeries. IA might be formed after all types of surgical interventions regardless the surgical approach with a higher incidence in obese individuals. Here we determine the diagnostic power of TGF-β and blood inflammatory parameters in the prediction of IA in obese patients undergoing second surgical intervention.

MATERIALS AND METHODS

Eighty patients were divided into groups according to body mass index (BMI) values and presence of intraperitoneal adhesions (IA). Evaluation of peritoneal adhesion index (PAI), serum TGF-β and blood inflammatory parameters was performed.

RESULTS

Level of TGF-β, C-reactive protein (CRP), leukocytes, neutrophil to lymphocyte ratio and platelet to lymphocyte ratio were significantly higher in obese patients while TGF-β, CRP, and leukocytes were higher in patients with IA. There was a significant correlation between PAI values and TGF-β concentration (p<0.001; r=0.869) in IA group.

CONCLUSIONS

The preoperative TGF-β concentration, BMI, CRP and NLR could be strong predictors of intraperitoneal adhesions in patients with the history of surgeries.

Peripheral serotonin regulates postoperative intra-abdominal adhesion formation in mice

The aim of the present study is to investigate the role and potential mechanisms of peripheral serotonin in postoperative intra-abdominal adhesion formation in mice. The caecum-rubbing operations were conducted for intra-abdominal adhesion formation modelling in wild-type and Tph1−/− mice. The deficiency of serotonin significantly decreased the adhesion scores, weight loss, and adhesion thickness as well as levels of collagen fibres and hydroxyproline in the adhesive tissues. The Tph1−/− mice exhibited a milder inflammatory response and oxidative stress in the adhesive tissues than did the wild-type mice. Moreover, the deficiency of serotonin reduced the levels of PAI-1 and fibrinogen, and raised the t-PA and t-PA/PAI levels in the peritoneal fluids. Moreover, the expressions of CD34, VEGF, TGF-β and 5-HT_2B receptor in the adhesive tissues were significantly decreased in the Tph1−/− group mice. Furthermore, the Tph1−/− +5-HTP group showed more severe adhesions than did the Tph1−/− group mice, and the p-chlorophenylalanine (PCPA) could markedly alleviated the adhesion formation in the WT mice. In conclusion, the present study showed that peripheral serotonin regulated postoperative intra-abdominal adhesion formation by facilitating inflammation, oxidative stress, disorder of the fibrinolytic system, angiopoiesis and TGF-β1 expression via the 5-HT_2B receptor in the adhesive tissues.

Preventive Effects of the Intestine Function Recovery Decoction, a Traditional Chinese Medicine, on Postoperative Intra-Abdominal Adhesion Formation in a Rat Model

The intestine function recovery decoction (IFRD) is a traditional Chinese medicine that has been used for the treatment of adhesive intestinal obstruction. In this study, the preventative effects and probable mechanism of the IFRD were investigated in a rat model. We randomly assigned rats to five groups: normal, model, control, low dose IFRD, and high dose IFRD. In the animal model, the caecum wall and parietal peritoneum were abraded to induce intra-abdominal adhesion formation. Seven days after surgery, adhesion scores were assessed using a visual scoring system, and histopathological samples were examined. The levels of serum interleukin-6 (IL-6) and transforming growth factor beta-1 (TGF-β1) were analysed by an enzyme-linked immunosorbent assay (ELISA). The results showed that a high dose of IFRD reduced the grade of intra-abdominal adhesion in rats. Furthermore, the grades of inflammation, fibrosis, and neovascularization in the high dose IFRD group were significantly lower than those in the control group. The results indicate that the IFRD can prevent intra-abdominal adhesion formation in a rat model. These data suggest that the IFRD may be an effective antiadhesion agent.

Effect of Pirfenidone on Vascular Proliferation, Inflammation and Fibrosis in an Abdominal Adhesion Rat Model

AIM

To study the efficacy of pirfenidone for prevention of postoperative adhesion formation in an adhesion rat model.

MATERIALS AND METHODS

Eighteen female Wistar rats were subjected to right-sided parietal peritoneum and right uterine horn adhesion model. Rats were randomized into three groups: group 1 (control) (closure of midline abdominal incision without any agent administration), group 2 (closure of incision after intraperitoneal administration of pirfenidone), and group 3 (closure of incision and only oral administration of pirfenidone for 14 days). Relaparotomy was performed 14 days after the first surgery. Effect of pirfenidone on adhesion formation was assessed on light microscopy by scoring vascular proliferation, inflammation, fibrosis, and collagen formation in the scarred tissue. Effect of pirfenidone on inflammation was assessed by measurement of transforming growth factor-β and interleukin-17 levels in scarred tissue.

RESULTS

The degree of vascular proliferation (1.32 ± 0.39 versus 2.34 ± 0.46, p < 0.001), inflammation (1.60 ± 0.70 versus 2.60 ± 0.52, p < 0.01), and fibrosis (1.50 ± 0.53 versus 2.40 ± 0.52, p < 0.01) were less prominent in group 2 compared to group 1, respectively. Only vascular proliferation was found to be less prominent in group 3 compared to group 1 (1.60 ± 0.42 versus 2.34 ± 0.46, p < 0.01). Intraperitoneal and oral administration of pirfenidone reduced tissue levels of inflammatory markers (TGF-β and IL-17) in parietal and visceral peritoneum compared to control group. Intraperitoneal administration of pirfenidone compared to oral administration was more effective in reducing tissue levels of inflammatory markers.

CONCLUSION

Pirfenidone is an effective agent on the prevention of postoperative vascular proliferation, inflammation and fibrosis in scarred tissue particularly with intraperitoneal administration.

Ghrelin Inhibits Post-Operative Adhesions via Blockage of the TGF-β Signaling Pathway

Post-operative adhesions are a critical problem in pelvic and abdominal surgery despite a multitude of studies dedicated to finding modalities to prevent their occurrence. Ghrelin administration promotes an anti-fibrotic response in a surgical mouse model of adhesion-induction, but the mechanisms mediating this effect have not been established. In the current study, the molecular mechanisms that underlie the anti-adhesion effect of ghrelin were investigated. Post-surgical adhesions were experimentally created in C57BL/6 wild-type mice via a combination of ischemic peritoneal buttons and cecal multiple abrasions. Ghrelin or saline intraperitoneal injections were given twice daily from two days before surgery to selected time points post-surgically to assess the phenotypic and molecular effects of treatment (1 day (n = 20), 4 days (n = 20) and 20 days (n = 40) after surgery). Endpoints included the scoring of adhesions and gene and protein expression analysis of pro-fibrogenic factors conducted on peritoneal ischemic tissue by quantitative PCR and Western blot. Ghrelin administration significantly reduced post-surgical adhesions and down-regulated pro-inflammatory gene and protein expression, including Tgfb3 and Tgfbr2. The up-regulation of inhibitory proteins Smad6 and Smad7 confirmed the ghrelin-induced blockage of TGF-β signaling. Ghrelin is a candidate therapeutic drug for post-operative adhesion prevention, inhibiting inflammatory responses via blockage of the TGF-β signaling pathway at the onset of surgery before the occurrence of the granulation-remodeling phase.

P-glycoprotein Mediates Postoperative Peritoneal Adhesion Formation by Enhancing Phosphorylation of the Chloride Channel-3

P-glycoprotein (P-gp) is encoded by the multidrug resistance (MDR1) gene and is well studied as a multi-drug resistance transporter. Peritoneal adhesion formation following abdominal surgery remains an important clinical problem. Here, we found that P-gp was highly expressed in human adhesion fibroblasts and promoted peritoneal adhesion formation in a rodent model. Knockdown of P-gp expression by intraperitoneal injection of MDR1-targeted siRNA significantly reduced both the peritoneal adhesion development rate and adhesion grades. Additionally, we found that operative injury up-regulated P-gp expression in peritoneal fibroblasts through the TGF-β1/Smad signaling pathway and histone H3 acetylation. The overexpression of P-gp accelerated migration and proliferation of fibroblasts via volume-activated Cl(-) current and cell volume regulation by enhancing phosphorylation of the chloride channel-3. Therefore, P-gp plays a critical role in postoperative peritoneal adhesion formation and may be a valuable therapeutic target for preventing the formation of peritoneal adhesions.