Sclerosing encapsulating peritonitis in rats: an experimental study with intraperitoneal antiseptics

Recommendations on the Management of Encapsulating Peritoneal Sclerosis in Japan, 2005: Diagnosis, Predictive Markers, Treatment, and Preventive Measures

This comprehensive update on the management of encapsulating peritoneal sclerosis incorporates insights gained from recently published findings and the accumulated experience of the authors. Aspects covered include diagnosis, risk factors and predictive markers, treatment, and prevention, including criteria for withdrawal from peritoneal dialysis.

Epidemiology of Encapsulating Peritoneal Sclerosis in Japan

Since the first peritoneal dialysis (PD) patients with encapsulating peritoneal sclerosis (EPS) were reported in 1980, EPS has been considered primarily a fatal complication. The incidence of EPS in PD patients has been reported to range from 0.7% to 7.3%, and the rate appears to be higher in patients receiving long-term treatment. The most recent data from Japan show an overall incidence of 2.5%, with a clear impact of extended PD duration, which also augments mortality. The incidence increases and the prognosis worsens with longer durations of PD. The incidences (and mortality rates) for EPS were 0% (0%), 0.7% (0%), 2.1% (8.3%), 5.9% (28.6%), 5.8% (61.5%), and 17.2% (100%) for patients who had undergone PD for 3, 5, 8, 10, 15, and >15 years respectively. Because EPS occurs after withdrawal from PD in more than half of patients with the condition, strict monitoring is necessary when a long-term patient is withdrawn from PD. Maintaining patients on standard PD for more than 8 years using conventional solutions is associated with a substantial risk for the development of EPS.

Pathogenesis of Peritoneal Fibrosing Syndromes (Sclerosing Peritonitis) in Peritoneal Dialysis

Drawing from diverse sources including epidemiological and clinical data, surgical observations, histopathology, serosal healing responses to fibrin and fibrinolysis, tissue reaction to chronic exposure, and to exo and endotoxins, new information on mesothelial stem cells, autocrine and paracrine influences on their proliferation and collagen synthesis, and the effect of glucose on fibroconnective tissue, we have begun to piece together the pathogenetic jigsaw of fibrosis in continuous ambulatory peritoneal dialysis (CAPD).

The reaction of peritoneal mesothelium and stroma to the stress of continual dialysis results in a spectrum of alterations ranging from opacification through a tanned peritoneum syndrome to sclerosing encapsulating peritonitis (SEP). Any agent that causes irritation of the mesothelial layer and induces serositis, or single severe or multiple episodes of peritonitis resulting in mesothelial loss, predisposes the peritoneum to fibroneogenesis. An accurate definition of the histopathological changes of peritoneal thickening is a prerequisite for defining pathogenesis. This paper is the first attempt to create such a framework.

It is evident from many areas of study that fibrin deposition and fibrinolysis, hyalinization of the superficial stromal collagen possibly tanned through nonenzymatic glycosylation by dialysate glucose and the proliferative potential of mesothelial stem cells play an important and possibly interdependent role in excessive fibroneogenesis in certain patients on CAPD.

Many of the pieces of the jigsaw are obviously still missing, and the picture is most surely incomplete. Nevertheless, the outline of the pathologic and etiologic landscape should now be discernible.

Sclerosing Peritonitis Complicating Prolonged Use of Chlorhexidine in Alcohol in the Connection Procedure for Continuous Ambulatory Peritoneal Dialysis

Sclerosing peritonitis (SP) is an uncommon but serious complication of CAPD with various suggested etiologies. We have documented 14 cases of SP in 18 patients who had used chlorhexidine in alcohol (ChA) in the connection procedure for CAPD. Thirteen died. Nine of the 14 patients had been transferred to hemodialysis or renal transplantation, yet all still developed symptoms of SP within a few months after transfer -even the 5 who were originally asymptomatic. The main symptoms of SP were peritoneal ultrafiltration failure, exudative bloody ascites and intestinal obstruction. They presented at around 5 years (30–80 months) after commencement of CAPD. Most deaths were related to intestinal obstruction. Four other patients with a comparable duration of ChA exposure were continued on CAPD with the Travenol Spike System (TSS), without further exposure to ChA. They were all asymptomatic of SP after 9–12 months. Comparing the 2 groups of asymptomatic patients, those transferred to TSS had a much better outcome after 9 months than those transferred to HD or renal transplantation (P=0.0476). We suggest that ChA is the main cause of SP in our patients and that continuing CAPD without further exposure to ChA is a better alternative than stopping CAPD to prevent the progression of SP.

Experimental Animal Models of Encapsulating Peritoneal Sclerosis

Encapsulating peritoneal sclerosis (EPS) is an infrequent, but extremely serious complication of long-term peritoneal dialysis. The cause of EPS is unclear, but the low incidence suggests that it is most likely multifactorial. The elucidation of developmental pathways and predictive markers of EPS would facilitate the identification and management of high-risk patients.

Animal models are often used to define pathways of disease progression and to test strategies for treatment and prevention in the patient population. Ideally such models could help to define the cause of EPS and its developmental pathways, to facilitate the identification of contributing factors and predictive markers, and to provide a system to test therapeutic strategies.

Researchers have studied several rodent models of EPS that rely on chronic chemical irritation (for example, bleach, low-pH solution, chlorhexidine gluconate) to induce peritoneal sclerosis and abdominal encapsulation. Development in all models is progressive, with inflammation giving way to peritoneal fibrosis or sclerosis with accumulating membrane damage, culminating in cocoon formation. Microscopic findings are similar to those proposed as diagnostic criteria for clinical EPS: an initial inflammatory infiltrate and submesothelial thickening, collagen deposition, and activation and proliferation of peritoneal fibroblasts. The potential to block progression of peritoneal sclerosis in these models by anti-inflammatory, antifibrotic, and antiangiogenic agents, and by inhibitors of the renin–angiotensin system have been demonstrated.

Animal models based on clinically relevant risk factors (for example, uremia, peritonitis, and long-term exposure to dialysis solutions) now represent the next step in model development.

Animal Models of Peritoneal Dialysis: Thirty Years of Our Own Experience

Experimental animal models improve our understanding of technical problems in peritoneal dialysis PD, and such studies contribute to solving crucial clinical problems. We established an acute and chronic PD model in nonuremic and uremic rats. We observed that kinetics of PD in rats change as the animals are aging, and this effect is due not only to an increasing peritoneal surface area, but also to changes in the permeability of the peritoneum. Changes of the peritoneal permeability seen during chronic PD in rats are comparable to results obtained in humans treated with PD. Effluent dialysate can be drained repeatedly to measure concentration of various bioactive molecules and to correlate the results with the peritoneal permeability. Additionally we can study in in vitro conditions properties of the effluent dialysate on cultured peritoneal mesothelial cells or fibroblasts. We can evaluate acute and chronic effect of various additives to the dialysis fluid on function and permeability of the peritoneum. Results from such study are even more relevant to the clinical scenario when experiments are performed in uremic rats. Our experimental animal PD model not only helps to understand the pathophysiology of PD but also can be used for testing biocompatibility of new PD fluids.

Pathogenesis and Treatment of Encapsulating Peritoneal Sclerosis: Basic and Translational Research

Encapsulating peritoneal sclerosis is a devastating condition in long-term peritoneal dialysis patients. Animal models have employed chemical insults to simulate its pathology and have provided insights into its pathophysiology, which appears to include inflammation, angiogenesis, and fibrosis. Monitoring of biomarkers and interruption of molecular pathways have provided potential interventions to slow or prevent the disease process. However, there remain many questions concerning the trigger that alters chronic peritoneal inflammation in peritoneal dialysis to severe sclerosis, peritoneal adhesions, and bowel obstruction. Further advances in therapy will likely require an effective means of an early diagnosis through related biomarkers, which in turn will require further advances in the understanding of the pathogenesis of this disease process.

Experimental Encapsulating Peritoneal Sclerosis Models: Pathogenesis and Treatment

Encapsulating peritoneal sclerosis (EPS) is rare but, with its high morbidity and mortality, it represents one of the most serious complications of long-term peritoneal dialysis. The pathogenesis of EPS has not been elucidated yet; therefore, there has been a growing interest in establishing appropriate animal models for EPS that would explain the pathogenesis of EPS and verify the efficacy of therapeutic agents targeting pathways such as angiogenesis and/ or fibrosis. This brief review provides an update on previously published animal experimental models of EPS. Based on this review, we discuss some aspects of pathogenesis and treatment options in patients with EPS. Experimental models of EPS cannot exactly reproduce human EPS because the latter most likely has a diverse etiology, including the influences of uremia, dialysis, and genetic factors. There is a need for new animal models that would test interventions targeting multiple risk factors while also taking into account putative genetic diversities that most likely are involved in human EPS.

[Sclerosing peritonitis]

Sclerosing peritonitis (also described as sclerosing obstructive peritonitis, encapsulating peritonitis, obliterative adhesive peritonitis, abdominal cocoon syndrome) is not well-known by the general surgeon; most reviews of this subject occur in the nephrology literature. Peritoneal dialysis and continuous hyperthermic peritoneal perfusion are the main causes. No controlled study exists to evaluate the optimal therapeutic approach. Pre-operative diagnosis is difficult since the clinical signs and radiologic findings are non-specific. Nevertheless, the diagnosis should be considered when small bowel obstruction with proximal dilatation, ascites, and thickened or calcified peritoneum are seen on imaging. The surgeon should recognize sclerosing peritonitis grossly when it is encountered and adapt his surgical strategy accordingly.

Encapsulating peritoneal sclerosis

Since the first peritoneal dialysis (PD) patients with encapsulating peritoneal sclerosis (EPS) were reported in 1980, EPS has been considered primarily a fatal complication. The incidence of EPS in PD patients has been reported to be from 0.7% to 7.3%, and the rate appears to be higher in patients receiving long-term treatment. Most data from Japan has shown an overall incidence of 2.5% with an evident negative effect of increasing duration of PD, which also augments mortality. Since EPS occurred after withdrawal from PD in more than half of the patients, strict monitoring is necessary when a long-term PD patient is withdrawn from PD. Maintaining patients on standard PD for more than 8 years using conventional solutions is associated with a substantial risk for development of EPS. Appropriate treatment according to the disease stage is most important in EPS treatment. Therefore, when examining a PD patient complaining of gastrointestinal symptoms, the possibility of EPS has to be kept in mind. Basic therapeutic tactics for EPS include appropriate use of steroids. If the state of bowel obstruction persists, laparotomy and enterolysis should be performed to obtain a complete cure. It is now recognized that EPS is not a fatal complication of PD.

The pathogenesis and therapeutic option of encapsulating peritoneal sclerosis

Since the first peritoneal dialysis (PD) patients with encapsulating peritoneal sclerosis (EPS) were reported in 1980, EPS has been considered primarily a fatal complication. The incidence of EPS in PD patients has been reported to be from 0.7% to 7.3%, and the rate appears to be higher in patients receiving long-term treatment. Most data from Japan has shown an overall incidence of 2.5% with an evident negative effect of increasing duration of PD, which also augments mortality. Since EPS occurred after withdrawal from PD in more than half of the patients, strict monitoring is necessary when a long-term PD patient is withdrawn from PD. Maintaining patients on standard PD for more than 8 years using conventional solutions is associated with a substantial risk for development of EPS. Appropriate treatment according to the disease stage is most important in EPS treatment. Therefore, when examining a PD patient complaining of gastrointestinal symptoms, the possibility of EPS has to be kept in mind. Basic therapeutic tactics for EPS include an appropriate use of steroids. If the state of bowel obstruction persists, laparotomy and enterolysis should be performed to obtain complete cure. It is now recognized that EPS is not a fatal complication of PD.

Selective depletion of fibroblasts preserves morphology and the functional integrity of peritoneum in transgenic mice with peritoneal fibrosing syndrome

BACKGROUND

A peritoneal fibrosing syndrome (PFS) can progressively reduce peritoneal ultrafiltration during chronic peritoneal dialysis in patients with renal failure. The pathogenesis of PFS is unclear and the role of peritoneal fibroblasts has not been evaluated experimentally.

METHODS

We followed the fate of fibroblasts producing PFS in a mouse model using fibroblast-specific protein 1 (FSP1) as a marker. PFS was induced by daily peritoneal infusions of chlorhexidine gluconate (CHG) saline into transgenic mice expressing the thymidine kinase (Delta tk) gene under the control of the FSP1 promoter (FSP1.Delta tk mice). To demonstrate the role of fibroblasts in PFS, we treated these FSP1.Delta tk mice with a nucleoside analogue to induce DNA chain termination and fibroblast death.

RESULTS

Mice receiving peritoneal infusions of CHG saline every other day for 2 weeks developed increasing numbers of FSP1+ fibroblasts in the subserosal layers of the visceral peritoneum. Mac-3+ monocytes (macrophages) subsequently accumulated over the next 2 weeks in association with increased deposition of type I collagen and increased endothelial vascularity (CD31+) in these subserosal tissues. Since these peritoneal fibroblasts expressed monocyte chemoattractant protein-1 (MCP-1), heat shock protein 47 (HSP47), and vascular endothelial growth factor (VEGF), we suspect they were partially responsible for macrophage recruitment, matrix production, and the neoangiogenesis in the subserosal tissue. Treatment of PFS in FSP1.Delta tk transgenic mice with a nucleoside analogue selectively reduced the numbers of peritoneal fibroblasts and attenuated the attendant changes in peritoneal histology. Rescuing the peritoneal membrane from chronic thickening and neoangiogenesis by reducing the number of fibroblasts also preserved ultrafiltration.

CONCLUSION

Peritoneal fibroblasts play a pivotal role in PFS, and their deletion using a fibroblasts-specific transgene was effective in preventing peritoneal fibrogenesis.

Evaluation of an antimicrobial-impregnated continuous ambulatory peritoneal dialysis catheter for infection control in rats

Infection is the most serious complication arising in long-term continuous ambulatory peritoneal dialysis (CAPD), specifically peritonitis and exit-site infection. The initial weeks after implantation is the crucial period during which bacterial colonization of the catheter results in maximal morbidity, with Staphylococcus aureus being the most virulent organism. We developed an antimicrobial-impregnated CAPD catheter by impregnating the cuff and tubing with chlorhexidine, silver sulfadiazine, and triclosan in a polymer matrix. The antimicrobial spectrum and duration were shown by measuring zones of inhibition to various bacteria and fungi over the course of 5 to 10 days. Activity also was assessed subsequent to soaking in trypticase soy broth containing 20% bovine serum over the course of 1, 3, and 7 days. Significant antimicrobial activity was shown against all organisms tested for, with particular efficacy against gram-positive bacteria. Catheters were implanted in rats followed by inoculation of the exit site with S aureus. Seven days postimplantation, 0% of the impregnated catheters were colonized intraperitoneally compared with 100% of the control catheters. Similarly, 12.5% of the impregnated catheters were colonized at the exit site, whereas 100% of the controls were colonized. Histologic analysis showed that this combination and concentration of antimicrobials did not retard healing or cause increased inflammation compared with control catheters after 3, 10, and 24 days postimplantation in noninoculated rats.

Peritoneal sclerosis: one or two nosological entities?

The frequency, pathology, animal models, pathogenesis, clinical manifestations, diagnostic criteria, therapy and prevention of peritoneal sclerosis are reviewed. Many of these aspects have a bimodal configuration which suggests that peritoneal sclerosis, usually considered a single pathology in peritoneal dialysis, is actually two distinct nosological entities: simple sclerosis and sclerosing peritonitis. The former is very frequent, with minor anatomical alterations and low clinical impact; it is reproducible in animals by means of peritoneal dialysis, and is clearly due to the poor biocompatibility of peritoneal dialysis solutions. The latter is rare, with radical anatomical alterations and high mortality requiring valid methods of diagnosis, therapy and prevention; it can only be reproduced in animal models by means other than peritoneal dialysis and seems to be due to factors both related and unrelated to peritoneal dialysis.

Peritoneal dialysis in Hungary

In 1991 the technical conditions and the number of patients receiving peritoneal dialysis were surveyed in the Hungarian nephrology and dialysing units. Not only the number of patients with chronic uraemia (undergoing dialysis + transplantation) is lower in this country as compared to the European average (106 and 236 per one million people, respectively), but also their distribution according to the type of treatment is different. For several years patients under intermittent peritoneal dialysis make up more than 10% of the cases and those under continuous ambulatory peritoneal dialysis less than 2% (in Europe: < 2% and 4-43%, respectively). The survey also included the types of solution, disinfection and connecting devices used in peritoneal dialysis, as well as the incidence of peritonitis and the administration of antibiotics. The principles of biocompatibility, the function of interleukin, as well as the effectiveness and the conditions of continuous ambulatory peritoneal dialysis are summarized.

Sclerosing encapsulating peritonitis in chronic ambulatory peritoneal dialysis

Sclerosing encapsulating peritonitis is now a well-recognised, but uncommon, complication of chronic ambulatory peritoneal dialysis. Patients present with impaired ultrafiltration capacity, abdominal pain, nausea, vomiting and episodes of small bowel obstruction. Barium studies of the small bowel are characteristic, showing varying lengths of intestine tightly enclosed in a 'cocoon' of thickened peritoneum, proximal small bowel dilatation and an increased transit time. Ultrasonography may show a thick-walled mass containing bowel loops, loculated ascites and fibrous adhesions. With the increasing use of ambulatory peritoneal dialysis in the treatment of end-stage renal failure, it is important that this condition is recognised. The prognosis is poor when the bowel becomes obstructed; before this happens the offending 'sclerotic' membrane may be amenable to surgical removal.