Inhibit Adhesion Formation Research Articles

Use of a pH-responsive imatinib mesylate sustained-release hydrogel for the treatment of tendon adhesion by inhibiting PDGFRβ/CLDN1 pathway

Adhesion after tendon injury, which can result in limb movement disorders, is a common clinical complication; however, effective treatment methods are lacking. Hyaluronic acid hydrogels are a new biomedical material used to prevent tendon adhesion owing to their good biocompatibility. In addition, potential drugs that inhibit adhesion formation have gradually been discovered. The anti-adhesion effects of a combination of loaded drugs into hydrogels have become an emerging trend. However, current drug delivery systems usually lack specific regulation of drug release, and the effectiveness of drugs for treating tendon adhesions is mostly flawed. In this study, we identified a new drug, imatinib mesylate (IM), that prevents tendon adhesion and explored its related molecular pathways. In addition, we designed a pH-responsive sustained-release hydrogel for delivery. Using the metal-organic framework ZIF-8 as a drug carrier, we achieved controlled drug release to increase the effective drug dose at the peak of adhesion formation to achieve better therapeutic effects. The results showed that IM blocked the formation of peritendon adhesions by inhibiting the PDGFRβ/ERK/STAT3/CLDN1 pathway. Furthermore, the hydrogel with ZIF-8 exhibited better physical properties and drug release curves than the hydrogel loaded only with drugs, showing better prevention and treatment effects on tendon adhesion.

A novel electrospun polylactic acid silkworm fibroin mesh for abdominal wall hernia repair

ObjectiveAbdominal wall hernias are common abdominal diseases, and effective hernia repair is challenging. In clinical practice, synthetic meshes are widely applied for repairing abdominal wall hernias. However, postoperative complications, such as inflammation and adhesion, are prevalent. Although biological meshes can solve this problem to a certain extent, they face the problems of heterogeneity, rapid degradation rate, ordinary mechanical properties, and high-cost. Here, a novel electrospinning mesh composed of polylactic acid and silk fibroin (PLA-SF) for repairing abdominal wall hernias was manufactured with good physical properties, biocompatibility and low production cost. Materials and methodsFTIR and EDS were used to demonstrate that the PLA-SF mesh was successfully synthesized. The physicochemical properties of PLA-SF were detected by swelling experiments and in vitro degradation experiments. The water contact angle reflected the hydrophilicity, and the stress‒strain curve reflected the mechanical properties. A rat abdominal wall hernia model was established to observe degradation, adhesion, and inflammation in vivo. In vitro cell mesh culture experiments were used to detect cytocompatibility and search for affected biochemical pathways. ResultsThe PLA-SF mesh was successfully synthesized and did not swell or degrade over time in vitro. It had a high hydrophilicity and strength. The PLA-SF mesh significantly reduced abdominal inflammation and inhibited adhesion formation in rat models. The in vitro degradation rate of the PLA-SF mesh was slower than that of tissue remodeling. Coculture experiments suggested that the PLA-SF mesh reduced the expression of inflammatory factors secreted by fibroblasts and promoted fibroblast proliferation through the TGF-β1/Smad pathway. ConclusionThe PLA-SF mesh had excellent physicochemical properties and biocompatibility, promoted hernia repair of the rat abdominal wall, and reduced postoperative inflammation and adhesion. It is a promising mesh and has potential for clinical application.

Oral Administration Evaluation of the Hydro-Ethanolic Extract of Ginger (Rhizome of Zingiber officinale) against Postoperative-Induced Peritoneal Adhesion: Investigating the Role of Anti-Inflammatory and Antioxidative Effects.

Peritoneal adhesions (PAs) occur and develop after abdominal surgery. Abdominal adhesions are common and often develop after abdominal surgery. Currently, there are no effective targeted pharmacotherapies for treating adhesive disease. In this regard, ginger is wildly used in traditional medicine because of its anti-inflammatory and antioxidant effects and has been investigated for peritoneal adhesion treatment. This study analyzed ginger ethanolic extraction via HPLC to have a 6-gingerol concentration. Four groups induced peritoneal adhesion to evaluate ginger's effects on peritoneal adhesion. Then, ginger extract (50, 150, and 450 mg/kg) was administered by gavage in various groups of male Wistar rats (220 ± 20 g, 6-8 weeks). After scarifying the animals for biological assessment, macroscopic and microscopic parameters were determined via scoring systems and immunoassays in the peritoneal lavage fluid. Next, the adhesion scores and interleukin IL-6, IL-10, tumor necrosis factor-(TNF-) α, transforming growth factor-(TGF-) β1, vascular endothelial growth factor (VEGF), and malondialdehyde (MDA) were elevated in the control group. The results showed that ginger extract (450 mg/kg) notably decreased inflammatory (IL-6 and TNF-α), fibrosis (TGF-β1), anti-inflammatory cytokine (IL-10), angiogenesis (VEGF), and oxidative (MDA) factors, while increased antioxidant factor glutathione (GSH), compared to the control group. These findings suggest that a hydro-alcoholic extract of ginger is a potentially novel therapeutic strategy for inhibiting adhesion formation. Also, it might be considered a beneficial anti-inflammatory or antifibrosis herbal medicine in clinical trials. However, further clinical studies are required to approve the effectiveness of ginger.

AICAR attenuates postoperative abdominal adhesion formation by inhibiting oxidative stress and promoting mesothelial cell repair.

Postoperative abdominal adhesion is one of most common complications after abdominal operations. 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR) is an adenosine 5'-monophosphate activated protein kinase (AMPK) pathway agonist that inhibits inflammation, reduces cell fibrosis and cellular reactive oxygen species (ROS) injury, promotes autophagy and mitochondrial function. This study aimed to explore the mechanism of AICAR in inhibiting adhesion formation. Forty rats were randomly divided into five groups. All of the rats except the sham group received cecal abrasion to establish an adhesion model. The rats in the sodium hyaluronate group were treated with 2 mL sodium hyaluronate before closing the peritoneal cavity. The AICAR 1 and 2 groups were treated with 100 mg/kg and 200 mg/kg AICAR, respectively. Seven days after the operation, all of the rats were euthanized, and the adhesion condition was evaluated by Nair's system. Inflammation was assessed by Eosin-hematoxylin (HE) staining and transforming growth factor-β (TGF-β1) detection. Oxidative stress effect was determined by ROS, nitric oxide (NO) level, superoxide dismutase (SOD), catalase, glutathione peroxidase (Gpx) and malondialdehyde (MDA) levels in adhesion tissue. Then, Sirius red picric acid staining was used to detect the fiber thickness. Immunohistochemical staining of cytokeratin-19 (CK-19), alpha-smooth muscle actin (α-SMA) and nuclear factor erythroid 2-related factor 2 (Nrf2) was also performed. Finally, HMrSV5 cells were treated with TGF-β1 and AICAR, the mRNA expression of E-cadherin, α-SMA and vimentin was assessed by q-PCR and cellular immunofluorescent staining. The rats in the AICAR-treated group had fewer adhesion formation incidences and a reduced Nair's score. The inflammation was determined by HE staining and TGF-β1 concentration. The ROS, SOD, Catalase, Gpx, MDA levels and fiber thickness were decreased by AICAR treatments compared to the control. However, the NO production, Nrf2 levels and peritoneal mesothelial cell integrity were promoted after AICAR treatments. In vitro work, AICAR treatments reduced E-cadherin, α-SMA and vimentin mRNA level compared to that in the TGF-β1 group. AICAR can inhibit postoperative adhesion formation by reducing inflammation, decreasing oxidative stress response and promoting peritoneal mesothelial cell repair.

Curcumin polymeric membranes for postoperative peritoneal adhesion: Comparison of nanofiber vs. film and phospholipid-enriched vs. non-enriched formulations

Intra-abdominal adhesion remains a major postoperative problem and is able to place individuals at lifelong risk of serious complications. Among available approaches, insertion of a barrier membrane at the site of injury partially inhibited adhesion formation. Moreover, the local administration of an anti-adhesive agent showed some favorable effects. In this study, we aimed to prepare and fully characterize polycaprolactone (PCL)-based film casts and electrospun nanofibers (NFs) containing a natural anti-inflammatory agent, curcumin (CUR), with extended-release properties. We also compared their efficiencies in preventing tissue adhesions. Additionally, the impact of soy phosphatidylcholine (SPC) enrichment on adhesion prevention was investigated. Prepared membranes were evaluated in terms of surface morphology (SEM, AFM), surface wettability, CUR release profiles, structural properties (FTIR, XRD, DSC), and mechanical behaviors. To further analyze the anti-adhesion effectiveness, a cecal abrasion model was performed on rats. SEM and AFM images showed a smoother surface in SPC-containing films. Concerning NFs, uniform bead-free fibers were observed and SPC containing NFs showed higher conductivity and lower viscosity and therefore, smaller fibers. All formulations exhibited sustained drug release over 4 weeks. In vivo findings revealed the superior performance of films compared to NFs and phospholipid-enriched formulations over non-enriched ones. Among all film formulations and in comparison to the positive control (Seprafilm®), CUR-SPC-PCL films significantly reduced peritoneal adhesions, as evidenced by gross examination, histological evaluation and immunohistochemical (IHC) analysis. The remarkable in vivo anti-adhesion activity together with suitable in vitro properties have made CUR-SPC-PCL films a promising system for postoperative anti-adhesion purposes in the clinic.

Morphological changes of macrophages and their potential contribution to tendon healing

Poor healing ability and adhesion formation greatly hinder the recovery of injured tendon function. Previously, our local sustained gene delivery system by using cyclooxygenases (COX-1 and COX-2)-engineered miRNA plasmid/nanoparticles loaded hydrogel significantly inhibited adhesion formation and promoted tendon healing. The present study aims to study morphological changes of the macrophages in the healing tendons after above treatment with the hydrogel. Firstly, we assessed the therapeutic effect of localized delivery of the hydrogel on cyclooxygenases in the injured rat Achilles tendon model. We found ultimate strengths of the healing tendons were significantly increased at week 2 and 3. We then studied the distribution of macrophages before and after tendon injury, and found macrophages were rapidly recruited into injured sites of tendons. After being isolated and cultured, macrophages were transfected with 6-Carboxyfluorescein (FAM) labeled siRNA/nanoparticles and presented a high transfection efficiency (>70%). We further compared the change of iNOS/CD206 in macrophages between negative control siRNA/nanoparticle group and COX siRNA/nanoparticle group. The major finding is that the morphology of the macrophages changed from type I macrophages to type II macrophages after transfection of COX siRNA/nanoparticles in vitro. Subsequently, rat Achilles tendon cells were cultured with supernatant collected from macrophages transfected with negative control siRNA/nanoparticles and COX siRNA/nanoparticles, and the proliferation of tendon cells was significantly increased in COX siRNA/nanoparticle supernatant group. Because type II macrophages are responsible for tissue repair, the changes in macrophage polarization from M1 to M2 may be one of the important events in promoting the tendon healing.

MSC-derived immunomodulatory extracellular matrix functionalized electrospun fibers for mitigating foreign-body reaction and tendon adhesion

Adhesion formation during tendon healing remains a severe problem in clinical practice. Multiple factors contribute to postoperative adhesion formation, and macrophage-driven inflammation is thought to be greatly involved in this process. We hypothesize that reducing macrophage-mediated inflammation in the injured tendon by regulating M1 to M2 macrophage polarization may effectively inhibit adhesion formation. Here, we developed an acellular immunomodulatory biomaterial consisting of an electrospun polycaprolactone/silk fibroin (PCL/SF) composite fibrous scaffold functionalized with mesenchymal stem cell (MSC)-derived extracellular matrix (ECM). To enhance the immunoregulatory potential of MSCs, we performed inflammatory licensing with IFN-γ to obtain immunomodulatory ECM (iECM). Proteomic analyses of MSCs and their secreted ECM components from different culture conditions revealed the MSC-ECM molecular signatures and the potential mechanism of ECM immunoregulation. Then, the immunoregulatory potential of the iECM-modified scaffold was evaluated in vitro and in vivo. Relative to the PCL/SF fibrous scaffold, the iECM-functionalized scaffold facilitated M2 macrophage polarization and inhibited the expression of multiple cytokines (IL-1β, IL-6, CXCL11, IL-10, IL-1R2, and TGF-β1) in vitro, strongly suggesting the immunosuppressive ability of iECM derived from inflammatory licensed MSCs. Consistent with the in vitro findings, the results of rat subcutaneous implantation indicated that a markedly lower foreign-body reaction (FBR) was obtained in the PCL/SF-iECM group than in the other groups, as evidenced by thinner fibrotic capsule formation, less type I collagen production and more M2-type macrophage polarization. In the rat Achilles tendon injury model, the PCL/SF-iECM scaffold greatly mitigated tendon adhesion with clear sheath space formation between the tendon and the scaffold. These data highlight the immunomodulatory potential of iECM-functionalized fibrous scaffolds to attenuate FBR by modulating M2 macrophage polarization, thereby preventing tendon adhesion. Statement of significanceElectrospun PCL/SF fibrous scaffolds functionalized with ECM secreted by MSCs stimulated by inflammatory factor IFN-γ was developed that combined physical barrier and immunomodulatory functions to prevent tendon adhesion formation. PCL/SF micro-nanoscale bimodal fibrous scaffolds prepared by emulsion electrospinning possess high porosity and a large pore size beneficial for nutrient transport to promote intrinsic healing; moreover, surface modification with immunomodulatory ECM (iECM) mitigates the FBR of fibrous scaffolds to prevent tendon adhesion. The iECM-functionalized electrospun scaffolds exhibit powerful immunomodulatory potency in vitro and in vivo. Moreover, the iECM-modified scaffolds, as an anti-adhesion physical barrier with immunomodulatory ability, have an excellent performance in a rat Achilles tendon adhesion model. MSC secretome-based therapeutics, as an acellular regenerative medicine strategy, are expected to be applied to other inflammatory diseases due to its strong immunoregulatory potential.

Association Between Statin Use at the Time of Intra-abdominal Surgery and Postoperative Adhesion-Related Complications and Small-Bowel Obstruction

Adhesion-related complications (ARCs), including small-bowel obstruction, are common complications of intra-abdominal surgery. Statins, which have antifibrotic pleiotropic effects, inhibit adhesion formation in murine models but have not been assessed in humans. To assess whether statin use at the time of intra-abdominal surgery is associated with a reduction in ARCs. These 2 separate retrospective cohort studies (The Health Improvement Network [THIN] and Optum's Clinformatics Data Mart [Optum]) compared adults receiving statins with those not receiving statins at the time of intra-abdominal surgery. Individuals undergoing intra-abdominal surgery from January 1, 1996, to December 31, 2013, in the United Kingdom and from January 1, 2000, to December 31, 2016, in the US were included in the study. Those with obstructive events before surgery or a history of inflammatory bowel disease were excluded. Data analysis was performed from September 1, 2012, to November 24, 2020. The primary exposure was statin use at the time of surgery. The primary outcome was ARCs, defined as small-bowel obstruction or need for adhesiolysis, occurring after surgery. Sensitivity analyses included statin use preceding but not concurrent with surgery, fibrate use, and angiotensin-converting enzyme inhibitor use. All analyses were adjusted for age, sex, and conditions associated with microvascular disease, such as hypertension, hyperlipidemia, obesity, and tobacco use; surgical approach and site; and diagnosis of a malignant tumor. A total of 148 601 individuals met the inclusion criteria for THIN (mean [SD] age, 49.6 [17.7] years; 70.1% female) and 1 188 217 for Optum (mean [SD] age, 48.2 [16.4] years; 72.6% female). A total of 2060 participants (1.4%) experienced an ARC in THIN and 54 136 (4.6%) in Optum. Statin use at the time of surgery was associated with decreased risk of ARCs (THIN: adjusted hazard ratio [HR], 0.81; 95% CI, 0.71-0.92; Optum: adjusted HR, 0.92; 95% CI, 0.90-0.95). Similar associations were appreciated between statins and small-bowel obstruction (THIN: adjusted HR, 0.80; 95% CI, 0.70-0.92; Optum: adjusted HR, 0.88; 95% CI, 0.85-0.91). This study's findings suggest that, among individuals in 2 separate cohorts undergoing intra-abdominal surgery, statin use may be associated with a reduced risk of postoperative ARCs. Statins may represent an inexpensive, well-tolerated pharmacologic option for preventing ARCs.

TMIGD1 Inhibited Abdominal Adhesion Formation by Alleviating Oxidative Stress in the Mitochondria of Peritoneal Mesothelial Cells.

Background Postoperative abdominal adhesion remains one of the frequent complications after abdominal surgery and lacks effective intervention. Peritoneal mesothelial cell injury and healing play crucial roles in the process of adhesion formation, and identifying this mechanism might provide new insight into possible new therapeutic strategies for this disease. Transmembrane and immunoglobulin domain-containing 1 (TMIGD1) has been proven to protect renal epithelial cells from injury induced by oxidative stress and has also been identified as a novel adhesion molecule. Here, we investigated the role of TMIGD1 and its possible mechanism in adhesion formation. Materials and Methods Immunohistochemistry (IHC), qPCR, and immunofluorescence (IHF) were used to detect the expression of TMIGD1. The grade and tenacity score of adhesion were used to evaluate the adhesion formation conditions. A TMIGD1-overexpressing HMrSV5 cell line was established. MTT assay, Western blotting, Annexin V apoptosis analysis, and CK19 staining were used to measure mesothelial cell viability, apoptosis, and completeness. ROS and MDA detection were used to measure mesothelial cell oxidative stress levels. JC-1 staining, IHF, and transmission electron microscopy were performed to assess mitochondrial function. Scratch-wound and adhesion assays were used to evaluate the adhesion ability of mesothelial cells. Results First, we showed that TMIGD1 was decreased in mouse abdominal adhesion tissue and peritoneal mesothelial cells. Second, TMIGD1 overexpression inhibited adhesion formation. Third, TMIGD1 overexpression protected mesothelial cells from hydrogen peroxide- (H2O2-) induced oxidative stress injury. Fourth, TMIGD1 overexpression alleviated oxidative stress by protecting the mitochondrial function of mesothelial cells. In addition, TMIGD1 overexpression enhanced mesothelial cell adhesion. Conclusion Our findings suggest that TMIGD1 protects mesothelial cells from oxidative stress injury by protecting their mitochondrial function, which is decreased in regular abdominal adhesion tissue. In addition, TMIGD1 enhances peritoneal mesothelial cell adhesion to promote healing.

The Antiadhesive Mechanism of the Lactoferrin Peptide rabPXL01 in Sodium Hyaluronate May Involve Proteoglycan 4

Objective/Hypothesis: A recent clinical study of the human lactoferrin peptide PXL01 in sodium hyaluronate (HA) administrated around repaired tendons in the hand showed significantly improved digit mobility compared with placebo. To investigate the antiadhesive mechanisms of PXL01 in HA, we have used the rabbit lactoferrin peptide, rabPXL01 in HA, in a rabbit model of healing tendons and tendon sheaths. Materials and Methods: On days 1, 3, and 6 after tendon injury and surgical repair, reverse transcription-quantitative PCR (RT-qPCR) was used to assess messenger RNA (mRNA) expression levels for genes encoding the mucinous glycoprotein PRG4 (also called lubricin), and a subset of matrix proteins, cytokines, and growth factors involved in flexor tendon repair. RabPXL01 in HA was administrated locally around the repaired tendons, and the mRNA expression was compared with untreated repaired tendons and tendon sheaths using analysis of variance. Results: We observed, at all time points, significantly increased expression of PRG4 mRNA in tendons treated with rabPXL01 in HA, but not in tendon sheaths. In addition, treatment with rabPXL01 in HA lead to repression of the mRNA levels for the proinflammatory mediators interleukin IL-1β, IL-6, and IL-8 in tendon sheaths. Conclusions: These findings suggest that rabPXL01 in HA increases lubricin production while diminishing inflammation, which correspondingly reduces the gliding resistance and inhibits adhesion formation after flexor tendon repair.

Injectable hydrogel from plum pectin as a barrier for prevention of postoperative adhesion

An injectable hydrogel was obtained from the high methyl-esterified plum Prunus domestica L. (PD) pectin and calcium ions (Ca2+). PD hydrogel showed a weak gel-like behavior and could be squeezed out of the syringe with an injection force of ca. 9 N. PD hydrogel was not suitable for the NIH/3T3 fibroblast cell adhesion in vitro. The live/dead fluorescence and MTT (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide) assays indicated that the PD hydrogel had a low cytotoxicity in relation to both the adhered and gel surrounding fibroblasts. PD hydrogel was found to inhibit adhesion formation in the sidewall defect-cecum abrasion rat model. In the control group, the occurrence of adhesion of the cecum to the peritoneal wall was found in seven of the total seven rats operated. Only four of the seven animals that were treated with the PD hydrogel were noted to have any adhesions. These adhesions were of a minimum grade of 1, 2, and 3 and were represented by a thin film that could be easily broken. The protective effect of PD hydrogel was found to be comparable with that of hyaluronic acid hydrogel used as a positive control. PD hydrogel appeared to possess enhanced in vivo residence stability on the injury sites compared to hyaluronic acid hydrogel as measured by staining of healing tissue with periodic acid-Schiff reagent. The data obtained offered the prospect for the development of the pectin-based gels as new barrier materials for surgery.

Inhibition of postsurgical adhesions by methylene blue-loaded nanofibers versus cast film matrices

In the quest for barrier membranes for the prevention of post-surgical tissue adhesions, polymer matrices may provide a platform of biomaterials with versatile properties. However, the relationship between the anti-adhesion effects of different polymer matrices and their physicochemical and structural properties is not yet adequately understood. In a preclinical study using a rat cecum model, we directly compared the anti-adhesion potential of polyhydroxybutyrate (PHB) electrospun nanofibrous versus cast film matrices loaded with methylene blue (MB) as antioxidant adhesion inhibitor. PHB retained MB presumably forming MB-bioactivated matrices. In the preclinical study, quantitative morphologic assessment in addition to histopathologic and SEM examinations 14 days post-surgery indicated that plain PHB NFs and MB-PHB NFs, moderately enhanced cecal wall healing and inhibited adhesion formation. In contrast, reshaping PHB as cast films, significantly enhanced healing, reduced adhesion bands and prevented inter-visceral adhesions. Cast films also inhibited tissue attachment to the matrix recovered 14 days post-surgery. Both PHB matrix types reduced tissue inflammation. Despite tissue anti-adhesion potential of individual matrix components, modulation of the micro-architectural properties generated polymer barriers with varying tissue anti-adhesion and healing potentials, the MB-loaded cast film achieving the best outcome.

Adeno-associated virus-2-mediated TGF-β1 microRNA transfection inhibits adhesion formation after digital flexor tendon injury.

Adhesion formation after digital flexor tendon injury greatly affects gliding function of the tendon, which is a major clinical complication after hand surgery. Transforming growth factor beta 1 (TGF-β1) has a critical role in adhesion formation during tendon healing. Persistent regulation of TGF-β1 through application of microRNA (miRNA) specifically inhibiting the function of TGF-β1 (TGF-β1-miRNA) holds promise for treatment of such a complication. Adeno-associated virus (AAV) was used to transfer TGF-β1-miRNA to the chicken digital flexor tendons, which had been injured and surgically repaired. Four doses of AAV2-TGF-β1-miRNA (2 × 10¹¹, 2 × 10¹⁰, 2 × 10⁹ and 2 × 10⁸ vector genomes (vg)) were used to determine the transfection efficiency. At postoperative 3 weeks, we found a positive correlation between the administered AAV2-TGF-β1-miRNA doses and transfection efficiency. The transfection rate ranged from 10% to 77% as the doses increased. Production of TGF-β1 protein in the tendons decreased on increasing vector dosage. When 2 × 10¹¹ and 2 × 10¹⁰) vg were injected into the tendon, gliding excursion of the repaired tendon and work of flexion of chicken toes were significantly increased and adhesion score decreased 6 and 8 weeks later, indicating the improvement of tendon gliding and decreases in adhesion formations. However, the ultimate strength of the tendons transfected at the dose of 2 × 10¹⁰ vg was 12-24% lower than that of the control tendons. The results of this study demonstrate that application of TGF-β1-miRNA had a mixed impact on tendon healing: adhesion around the tendon is reduced but strength of the tendon healing is adversely affected. Future studies should aim at maintaining the beneficial effects of reducing tendon adhesions, while eliminating the adverse effects of decreasing the healing strength.

Effects of macrophage-dependent peroxisome proliferator-activated receptor γ signalling on adhesion formation after abdominal surgery in an experimental model.

The pathophysiology of adhesion formation after abdominal and pelvic surgery is still largely unknown. The aim of the study was to investigate the role of macrophage polarization and the effect of peroxisome proliferator-activated receptor (PPAR) γ stimulation on adhesion formation in an animal model. Peritoneal adhesion formation was induced by the creation of ischaemic buttons within the peritoneal wall and the formation of a colonic anastomosis in wild-type, interleukin (IL) 10-deficient (IL-10(-/-) ), IL-4-deficient (IL-4(-/-) ) and CD11b-Cre/PPARγ(fl) (/fl) mice. Adhesions were assessed at regular intervals, and cell preparations were isolated from ischaemic buttons and normal peritoneum. These samples were analysed for macrophage differentiation and its markers, and expression of cytokines by quantitative PCR, fluorescence microscopy, arginase activity and pathological examination. Some animals underwent pioglitazone (PPAR-γ agonist) or vehicle treatment to inhibit adhesion formation. Anastomotic healing was evaluated by bursting pressure measurement and collagen gene expression. Macrophage M2 marker expression and arginase activity were raised in buttons without adhesions compared with buttons with adhesions. IL-4(-/-) and IL-10(-/-) mice were not affected, whereas CD11b-Cre/PPARγ(fl) (/fl) mice showed decreased arginase activity and increased adhesion formation. Perioperative pioglitazone treatment increased arginase activity and decreased adhesion formation in wild-type but not CD11b-Cre/PPARγ(fl) (/fl) mice. Pioglitazone had no effect on anastomotic healing. Endogenous macrophage-specific PPAR-γ signalling affected arginase activity and macrophage polarization, and counter-regulated peritoneal adhesion manifestation. Pharmacological PPAR-γ agonism induced a shift towards macrophage M2 polarization and ameliorated adhesion formation in a macrophage-dependent manner. Surgical relevance Postoperative adhesion formation is frequently seen after abdominal surgery and occurs in response to peritoneal trauma. The pathogenesis is still unknown but includes an imbalance in fibrinolysis, collagen production and inflammatory mechanisms. Little is known about the role of macrophages during adhesion formation. In an experimental model, macrophage M2 marker expression was associated with reduced peritoneal adhesion formation and involved PPAR-γ-mediated arginase activity. Macrophage-specific PPAR-γ deficiency resulted in reduced arginase activity and aggravated adhesion formation. Pioglitazone, a PPAR-γ agonist, induced M2 polarization and reduced postoperative adhesion formation without compromising anastomotic healing in mice. Pioglitazone ameliorated postoperative adhesion formation without compromising intestinal wound healing. Therefore, perioperative PPAR-γ agonism might be a promising strategy for prevention of adhesion formation after abdominal surgery.

Effects of inhibitory peptide of Staphylococcus epidermidis biofilm on adhesion and biofilm formation of this bacterium

To study the effects of inhibitory peptide of Staphylococcus epidermidis (SE) biofilm (briefly referred to as inhibitory peptide) on adhesion and biofilm formation of SE at early stage. By using peptide synthesizer, the inhibitory peptide was synthesized with purity of 96.8% and relative molecular mass of 874.4. (1) Solution of SE ATCC 35984 (the same below) was cultivated with inhibitory peptide in the final concentrations of 1-256 µg/mL, and the M-H broth without bacteria solution was used as blank control. The MIC of the inhibitory peptide against SE was determined (n=3). (2) Solution of SE was cultivated with trypticase soy broth (TSB) culture solution containing inhibitory peptide in the final concentrations of 16, 32, 64, 128, and 256 µg/mL (set as inhibitory peptide groups in corresponding concentration), and solution of SE being cultivated with TSB culture medium was used as negative control group. Growth of SE was observed every one hour from immediately after cultivation (denoted as absorbance value), and the growth curve of SE during the 24 hours of cultivation was drawn, with 3 samples in each group at each time point. (3) Solution of SE was cultivated with TSB culture solution containing inhibitory peptide in the final concentrations of 16, 32, 64, 128, and 256 µg/mL (set as inhibitory peptide groups in corresponding concentration), and solution of SE being cultivated with TSB culture medium was used as negative control group. Adhesive property of SE was observed after cultivation for 4 hours (denoted as absorbance value, n=10); biofilm formation of SE was observed after cultivation for 20 hours (denoted as absorbance value, n=10). (4) Solution of SE was cultivated with TSB culture solution containing inhibitory peptide in the final concentration of 128 µg/mL (set as 128 µg/mL inhibitory peptide group), and solution of SE being cultivated with TSB culture medium was used as negative control group. Adhesive property of SE and its biofilm formation were observed with confocal laser scanning microscope (CLSM), and the sample numbers were both 3. Data were processed with one-way analysis of variance, LSD test, and Dunnett T3 test. (1) The MIC of inhibitory peptide against SE exceeded 256 µg/mL. (2) There was no significant difference in the growth curve of SE between inhibitory peptide groups in different concentrations and negative control group. (3) After 4 hours of cultivation, the absorbance values of adhesive property of SE in 256, 128, 64, and 32 µg/mL inhibitory peptide groups were respectively 0.20 ± 0.04, 0.27 ± 0.03, 0.35 ± 0.04, and 0.40 ± 0.04, which were significantly lower than the absorbance value in negative control group (0.53 ± 0.10, P<0.05 or P<0.01); the absorbance value of adhesive property of SE in 16 µg/mL inhibitory peptide group was 0.47 ± 0.09, which was close to the absorbance value in negative control group (P>0.05). After 20 hours of cultivation, the absorbance values of biofilm formation of SE in 256, 128, and 64 µg/mL inhibitory peptide groups were respectively 0.49 ± 0.10, 0.68 ± 0.06, and 0.93 ± 0.13, which were significantly less than the absorbance value in negative control group (1.21 ± 0.18, P<0.05 or P<0.01); the absorbance values of biofilm formation in 32 and 16 µg/mL inhibitory peptide groups were respectively 1.18 ± 0.22 and 1.15 ± 0.26, which were close to the absorbance value in negative control group (with P values above 0.05). (4) CLSM showed that more adhering bacteria and compact structure of biofilm were observed in negative control group, but less adhering bacteria and loose structure of biofilm were observed in 128 µg/mL inhibitory peptide group. The inhibitory peptide can inhibit adhesion and biofilm formation of SE at early stage, but its structure still needs to be further modified.

Peritoneal response to abdominal surgery: the role of equine abdominal adhesions and current prophylactic strategies.

Intra-abdominal adhesions constitute a significant clinical and surgical problem that can lead to complications such as pain and bowel occlusion or subocclusion. These adhesions are frustrating and potentially fatal, representing a major postoperative complication in abdominal surgery. It is estimated that 32% of horses undergoing laparotomy will present clinical symptoms due to adhesions, but the true prevalence is not known because a large proportion of animals with postoperative recurrent colics are medically treated or submitted to euthanasia without necropsy. Adhesions are highly cellular, vascularized, dynamic structures that are influenced by complex signaling mechanisms. Understanding their pathogenesis could assist in applying better therapeutic strategies and in developing more effective antiadhesion products. Currently, there are no definitive strategies that prevent adhesion formation, and it is difficult to interpret the results of existing studies due to nonstandardization of an induction model and evaluation of their severity. The best clinical results have been obtained from using minimally traumatic surgical techniques, anti-inflammatory agents, antimicrobials, anticoagulants, and mechanical separation of serosal surfaces by viscous intraperitoneal solutions or physical barriers. This paper aims to review adhesion formation pathogenesis, guide the understanding of major products and drugs used to inhibit adhesion formation, and address their effectiveness in the equine species.

A non-canonical role for Rgnef (p190RhoGEF) in promoting integrin-stimulated focal adhesion kinase activation

Rgnef (also known as p190RhoGEF or ARHGEF28) is a Rho guanine-nucleotide-exchange factor (GEF) that binds focal adhesion kinase (FAK). FAK is recruited to adhesions and activated by integrin receptors binding to matrix proteins, such as fibronectin (FN). Canonical models place Rgnef downstream of integrin-FAK signaling in regulating Rho GTPase activity and cell movement. Herein, we establish a new, upstream role for Rgnef in enhancing FAK localization to early peripheral adhesions and promoting FAK activation upon FN binding. Rgnef-null mouse embryo fibroblasts (MEFs) exhibit defects in adhesion formation, levels of FAK phosphotyrosine (pY)-397 and FAK localization to peripheral adhesions upon re-plating on FN. Rgnef re-expression rescues these defects, but requires Rgnef-FAK binding. A mutation in the Rgnef pleckstrin homology (PH) domain inhibits adhesion formation, FAK localization, and FAK-Y397 and paxillin-Y118 phosphorylation without disrupting the Rgnef-FAK interaction. A GEF-inactive Rgnef mutant rescues FAK-Y397 phosphorylation and early adhesion localization, but not paxillin-Y118 phosphorylation. This suggests that, downstream of FN binding, paxillin-pY118 requires Rgnef GEF activity through a mechanism distinct from adhesion formation and FAK activation. These results support a scaffolding role for Rgnef in FAK localization and activation at early adhesions in a PH-domain-dependent but GEF-activity-independent manner.

Hepatocyte Growth Factor Inhibited Adhesion Formation After Hepatectomy by Regulating Interferon-Gamma and Plasminogen Activator Inhibitor-1 (PAI-1) in Mice

Hepatocyte Growth Factor Inhibited Adhesion Formation After Hepatectomy by Regulating Interferon-Gamma and Plasminogen Activator Inhibitor-1 (PAI-1) in Mice

Celecoxib, NSAIDs and the skeleton

Treating acute and chronic musculoskeletal pain is essential for improving healing of traumatic injuries and surgical procedures, and for improving patient quality of life. Physicians are limited primarily to treating musculoskeletal pain with nonsteroidal antiinflammatory drugs (NSAIDs), cyclooxygenase type 2 (COX-2)-selective NSAIDs such as celecoxib, or narcotics. Patients often treat their pain with over-the-counter NSAIDs. Unlike narcotics that target the central nervous system to alleviate pain, NSAIDs inhibit cyclooxygenase activity within the central nervous system and at the peripheral pain site to prevent the conversion of arachidonic acid into prostaglandins. Thus, NSAID use can and does alter certain fundamental processes involved in the normal healing of injured tissues. Cyclooxygenase activity and prostaglandin signaling are critical regulators of normal skeletal metabolism and inflammation related to injury or disease. Since most people only use NSAIDs sporadically to treat pain, few data indicate that short-term or repeated occasional use of NSAIDs is deleterious to skeletal health. However, clinical data suggest that chronic use of celecoxib, may impair normal skeletal function leading to decreased bone mineral density in older male patients. Experimental studies also have documented the negative effects of NSAIDs on healing of skeletal tissues. Fracture healing and tendon-to-bone healing appear to be particularly susceptible to inhibition by celecoxib. Limited retrospective clinical data tends to support the experimental data that COX-2 function is critical for normal bone healing. In contrast, NSAID use and perhaps COX-2-selective NSAID use may be beneficial for healing of other skeletal injuries. In particular, NSAID use does not appear to have a long-term negative effect on the ultimate healing of tendons and ligaments. Indeed, NSAID therapy may inhibit adhesion formation during tendon healing, which leads to a better functional recovery. Certainly, NSAID therapy following acetabular fractures, other hip fractures, or following hip replacement surgery is beneficial for reducing heterotopic ossification that can limit joint mobility. The effects of NSAID or celecoxib therapy on healing of other skeletal tissues is less clear. For instance, clinical data indicates that celecoxib therapy does not impair spinal fusion but experimental data indicates the opposite. Similarly, some reports suggest that NSAID therapy may prevent further erosion of cartilage in certain arthritic conditions while other reports indicate that NSAID treatment will exacerbate cartilage damage. The difference in effects caused by NSAID or celecoxib therapy likely relate to the role cyclooxygenase has in the biology of the injured tissue or its healing response. Differences in pharmacology between NSAIDs, treatment regimens, experimental models and potential off-target effects also may confuse many of these issues. It is clear, however, that cyclooxygenase activity is involved in the healing of many skeletal tissues, either directly or indirectly through modulation of the inflammatory response. Consequently, pharmacological manipulation of cyclooxygenase using NSAIDs or celecoxib can profoundly affect skeletal health.

The Effect of Intraperitoneal Catalase on Prevention of Peritoneal Adhesion Formation in Rats

The objective of our study was to investigate the efficacy of catalase in preventing the formation of peritoneal adhesions induced by cecal serosal laceration in rats. A research study was set up using a randomized complete block design. This study was performed in the Experimental Surgical Research Center, Kahramanmaras Sutcuimam University, Kahramanmaras, Turkey. Thirty Wistar albino rats were assigned to 3 groups of 10 animals each. The animals were anesthetized, a median laparotomy was performed, and the cecum was traumatized. In the final stages of surgery, the first group received 30,000 U of catalase intraperitoneally (ip) (catalase group), the second group received 2 mL of saline solution ip (isotonic group), and the last group received no treatment (control group). All rats were sacrificed on day 14. Adhesions were counted and blood samples were taken for measuring the catalase level. There were significant differences between the adhesion scores among all groups (p <. 05, Kruskal–Wallis test). The catalase group had significantly lower adhesion scores than the other groups (post hoc Mann–Whitney test). At day 14, blood catalase levels in the catalase group were significantly lower than in the other groups (p <. 05). We conclude that introduction of catalase into the peritoneal cavity during surgery inhibited adhesion formation.