Effects of mTOR Inhibitors in Prevention of Abdominal Adhesions

Comparison of the effect of Everolimus, Prednisolone, and a combination of both on experimentally induced peritoneal adhesions in rats

Postoperative intra-abdominal adhesions represent a significant post-surgical problem. Its complications can cause a considerable clinical and cost burden. Herein, our study aimed to investigate the effect of Everolimus on peritoneal adhesion formation after inducing adhesions in rats. In this experimental study, adhesion bands were induced by intraperitoneal injection of 3 ml of 10% sterile talc solution in 64 male albino rats. The first group served as the control group. The second one received oral Prednisolone (1 mg/kg/day), the third received Everolimus (0.1 mg/kg/day), and group four received both drugs with similar dosages for four consecutive weeks. The formation of adhesion bands was qualitatively graded according to the Nair classification. The rats in the control group had extensive adhesions between the abdominal wall and the organs. Regarding substantial adhesion formation, 50% (8/16) of animals in the control group had substantial adhesions, while this rate in the groups receiving Prednisolone, Everolimus, and combination treatment was 31%, 31%, and 31%, respectively. Also, 68.75% (5/11) of the Prednisolone recipients had insubstantial adhesions, the same as Everolimus recipients, while in the combination group, 66.66% (10/15) rats had insubstantial adhesions. Everolimus demonstrated satisfactory results in reducing the rates of induced peritoneal adhesion in an experimental model, similar to Prednisolone and superior to a combination regime.

The Therapeutic Potential of Targeting Key Signaling Pathways as a Novel Approach to Ameliorating Post-Surgical Adhesions

BACKGROUND

Peritoneal adhesions (PA) are a common complication of abdominal operations. A growing body of evidence shows that inhibition of inflammation and fibrosis at sites of peritoneal damaging could prevent the development of intra-abdominal adhesions.

METHODS

A search of PubMed, Medline, CINAHL and Embase databases was performed using the keywords 'postsurgical adhesion', 'post-operative adhesion', 'peritoneal adhesion', 'surgery-induced adhesion' and 'abdominal adhesion'. Studies detailing the use of pharmacological and non-pharmacological agents for peritoneal adhesion prevention were identified, and their bibliographies were thoroughly reviewed to identify further related articles.

RESULTS

Several signaling pathways, such as tumor necrosis factor-alpha, tissue plasminogen activator, and type 1 plasminogen activator inhibitor, macrophages, fibroblasts, and mesothelial cells play a key part in the development of plasminogen activator. Several therapeutic approaches based on anti-PA drug barriers and traditional herbal medicines have been developed to prevent and treat adhesion formation. In recent years, the most promising method to prevent PA is treatment using biomaterial-based barriers.

CONCLUSION

In this review, we provide an overview of the pathophysiology of adhesion formation and various agents targeting different pathways, including chemical agents, herbal agents, physical barriers, and clinical trials concerning this matter.

Late renal allograft torsion in a pediatric transplant recipient

BACKGROUND

Kidney allograft torsion is a rare complication of kidney transplant that can lead to allograft loss from prolonged ischemia if not quickly corrected with detorsion and nephropexy. We report a case of late intraperitoneal renal allograft torsion in a pediatric transplant recipient.

CASE REPORT

The patient is a 7-year-old male with a history of end-stage renal disease secondary to renal dysplasia in the setting of bilateral high-grade vesicoureteral reflux. He underwent bilateral native nephrectomies for recurrent pyelonephritis and right ureteral kink with urinary tract obstruction. Torsion occurred 3 years after transplant in the setting of one day of emesis, loose stool, severe abdominal pain, and decreased urine output. Diagnosis of transplant torsion was suspected on non-contrast CT scan done after transplant Doppler ultrasound showed no flow to the allograft. The CT scan showed that the kidney had been medialized and renal hilum was flipped from the expected orientation. The patient required a transplant nephrectomy.

CONCLUSIONS

Renal transplant torsion is a rare event but should be suspected in any renal transplant recipient with acute onset of abdominal pain, acute kidney injury, and decreased urine output, regardless of length of time from transplantation. Patients suspected to have renal torsion should be evaluated emergently with a transplant ultrasound Doppler.

Comparison of Oral Sirolimus, Prednisolone, and Combination of Both in Experimentally Induced Peritoneal Adhesion

INTRODUCTION

Peritoneal adhesion formation is a challenging postoperative complication. We aim to evaluate the effect of orally administered sirolimus, prednisolone, and their combination to prevent this entity.

METHODS

Eighty female albino underwent intraperitoneal injection of 3 mL of 10% sterile talc solution to induce peritoneal adhesion, and were subsequently and randomly divided into four groups (each n = 20); including a control group; 1 mg/kg oral prednisolone daily in the morning; 0.1 mg/kg oral sirolimus daily; and a combination group which received both drugs, with the same dosage. On the 29th day, abdominal cavities were explored, and classification was done based on Nair classification.

RESULTS

All rats were healthy on the 29th day, in which exploration was performed. The rats in the control group had extensive intra-abdominal adhesions, while 17 (85%) rats in the control group had substantial adhesion; however, the prednisolone, sirolimus, and combination group had lesser adhesion formation. Also, 14 (70%) rats of prednisolone group, 13 (65%) of sirolimus group, and 16 (80%) of combination group had insubstantial adhesion. The decrease in the grade of peritoneal adhesion bands was highly significant in the combination group (P > 0.001).

CONCLUSIONS

The combination of sirolimus and prednisolone was effective for preventing peritoneal adhesions in rats.

Recurrent Renal Allograft Torsion After Simultaneous Kidney and Pancreas Transplantation: Is it Still Possible to Salvage the Graft? A Case Report

BACKGROUND

Kidney allograft torsion (KAT) is defined as a rotation of the renal allograft around its vascular pedicle. It is a rare complication with high rate of graft loss. The nonspecific presentation and inability to provide a definitive diagnosis by imaging, mainly in cases of partial torsion, often delay the diagnosis and treatment. We report a case of recurrent complete torsion of the renal allograft after simultaneous kidney and pancreas transplantation, requiring 2 emergency exploratory laparotomies.

CASE REPORT

A 38-year-old woman with a history of intraperitoneal simultaneous kidney and pancreas transplantation underwent 2 separate emergency exploratory laparotomies secondary to complete renal allograft torsion, respectively, 7 and 11 months after the transplant. In both episodes, no adhesions were encountered. During the first operation, nephropexy was performed. During the second operation, an abdominal wall mesh was placed and fixed to the abdominal wall. Acute kidney injury related to KAT recovered in both occasions with a creatinine of 1.3 mg/dL at 4 months follow-up.

CONCLUSIONS

Renal torsion always should be suspected in intraperitoneally placed kidneys presenting with nonspecific symptoms, abdominal pain, oliguria, and worsening kidney function. Surgical exploration should be considered to salvage the renal graft. This case illustrates the reversibility of a severe injury related to this vascular complication with an adequate return to baseline kidney function even when diagnosis and surgical treatment of KAT might be delayed secondary to its misleading clinical presentation.

Peritoneal adhesions: Occurrence, prevention and experimental models

Peritoneal adhesions (PA) are a postoperative syndrome with high incidence rate, which can cause chronic abdominal pain, intestinal obstruction, and female infertility. Previous studies have identified that PA are caused by a disordered feedback of blood coagulation, inflammation, and fibrinolysis. Monocytes, macrophages, fibroblasts, and mesothelial cells are involved in this process, and secreted signaling molecules, such as tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), tissue plasminogen activator (tPA), and type 1 plasminogen activator inhibitor (PAI-1), play a key role in PA development. There have been many attempts to prevent PA formation by anti-PA drugs, barriers, and other therapeutic methods, but their effectiveness has not been widely accepted. Treatment by biomaterial-based barriers is believed to be the most promising method to prevent PA formation in recent years. In this review, the pathogenesis, treatment approaches, and animal models of PA are summarized and discussed to understand the challenges faced in the biomaterial-based anti-PA treatments.

[Influence of unmodified and modified sutures on experimental abdominal adhesive process]

OBJECTIVE

Experimental assessment of the effect of modified and unmodified surgical suture material on abdominal adhesive process.

MATERIAL AND METHODS

The study was performed on male rats of the Wistar subpopulation. There were 5 animals in each group. In all animals, midline abdominal incision was followed by suturing the parietal peritoneum with modified and unmodified suture material. All animals were euthanized with carbon dioxide vapors in 14 days after surgery. Macro- and microscopic assessment of severity of abdominal adhesive process was carried out. Two types of preparation of excised complexes 'peritoneum-suture material-adhesion' were applied for histological examination: paraffin sections and embedding in epoxy resin. Specimens were stained by Van Gieson and with methylene blue solution. Histological specimens were examined using Axio Imager A1 light microscope (Zeiss, Germany).

RESULTS

Polypropylene filaments result extensive adhesions occupying about 75% of the area. Adhesions have a dense structure with signs of vascularization. Modification of suture material with solution of polyhydroxybutyrate/hydroxyvalerate and heparin reduce severity of adhesions. The use of modified suture material was followed by adhesions with more loose structure, no signs of vascularization. Adhesions occupied less than 25% of the area. Histological examination of excised complexes 'peritoneum-suture material-adhesion' revealed accumulation of inflammatory cells around the unmodified suture material, while there were no signs of tissue inflammatory process around the modified sutures.

CONCLUSION

Application of polyhydroxybutyrate/hydroxyvalerate and heparin on the surface of surgical sutures is an effective method for prevention of abdominal adhesions.

Sirolimus-coated, poly(L-lactic acid)-modified polypropylene mesh with minimal intra-peritoneal adhesion formation in a rat model

PURPOSE

This study evaluated the manufacturing method and anti-adhesion properties of a new composite mesh in the rat model, which was made from sirolimus (SRL) grafts on a poly(L-lactic acid) (PLLA)-modified polypropylene (PP) hernia mesh.

METHODS

PLLA was first grafted onto argon-plasma-treated native PP mesh through catalysis of stannous chloride. SRL was grafted onto the surface of PP-PLLA meshes using catalysis of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine (DMAP) in a CH₂Cl₂ solvent. Sprague-Dawley female rats received either SRL-coated meshes, PP-PLLA meshes, or native PP meshes to repair abdominal wall defects. At different intervals, rats were euthanized by a lethal dose of chloral hydrate and adhesion area and tenacity were evaluated. Sections of the mesh with adjacent tissues were assessed histologically.

RESULTS

Attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy indicated the existence of a C=O group absorption peak (1724.1 cm^-1), and scanning electron microscope morphological analysis indicated that the surface of the PP mesh was covered with SRL. Compared to the native PP meshes and PP-PLLA meshes, SRL-coated meshes demonstrated the greatest ability to decrease the formation of adhesions (P < 0.05) and inflammation.

CONCLUSIONS

The SRL-coated composite mesh showed minimal formation of intra-abdominal adhesions in a rat model of abdominal wall defect repair.

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.