Encapsulating peritoneal sclerosis in the era of a multi-disciplinary approach based on biocompatible solutions: the NEXT-PD study

Encapsulating peritoneal sclerosis

Encapsulating peritoneal sclerosis (EPS) is a debilitating condition characterized by a fibrocollagenous membrane encasing the small intestine, resulting in recurrent small bowel obstructions. EPS is most commonly associated with long-term peritoneal dialysis, though medications, peritoneal infection, and systemic inflammatory disorders have been implicated. Many cases remain idiopathic. Diagnosis is often delayed given the rarity of the disorder combined with non-specific symptoms and laboratory findings. Although cross-sectional imaging with computed tomography of the abdomen can be suggestive of the disorder, many patients undergo exploratory laparotomy for diagnosis. Mortality approaches 50% one year after diagnosis. Treatment for EPS involves treating the underlying condition or eliminating possible inciting agents (i.e. peritoneal dialysis, medications, infections) and nutritional support, frequently with total parenteral nutrition. EPS-specific treatment depends on the disease stage. In the inflammatory stage, corticosteroids are the treatment of choice, while in the fibrotic stage, tamoxifen may be beneficial. In practice, distinguishing between stages may be difficult and both may be used. Surgical intervention, consisting of peritonectomy and enterolysis, is time-consuming and high-risk and is reserved for situations in which conservative medical therapy fails in institutions with surgical expertise in this area. Herein we review the available literature of the etiology, pathogenesis, diagnosis, and treatment of this rare, but potentially devastating disease.

Biocompatibility of a new PD solution for Japan, Reguneal™, measured as in vitro proliferation of fibroblasts

BACKGROUND

The aim of this study was to investigate in vitro biocompatibility of Reguneal™, a new bicarbonate containing peritoneal dialysis fluid (PDF) for Japan, and compare it with other PDFs available in that country.

METHODS

We assessed basal cytotoxicity using in vitro proliferation of cultured fibroblasts, L-929, determining the quantity of living cells by the uptake of Neutral Red. Levels of ten glucose degradation products (GDPs) were measured by a validated ultrahigh-performance liquid chromatography method in combination with an ultraviolet detector. We compared inhibition of fibroblast cell growth between brands of PDF, adjusting for dextrose and GDP concentrations using random-effects mixed models.

RESULTS

The results demonstrate that cytotoxicity of Reguneal™ is comparable to a sterile-filtered control and is less cytotoxic than most of the other PDFs, most of which significantly inhibited cell growth. As a "class effect", increasing dextrose and GDP concentrations were non-significantly but positively associated with cytotoxicity. As a "brand effect", these relationships varied widely between brands, and some PDFs had significant residual effects on basal cytotoxicity through mechanisms that were unassociated with either dextrose or GDP concentration.

CONCLUSION

Our study suggests that Reguneal™ is a biocompatible PDF. The results of our study also highlight that dextrose and GDPs are important for biocompatibility, but alone are not a complete surrogate. The results of our study need to be confirmed in other tissue culture models, and should lead to further research on determinants of biocompatibility and the effect of such PDFs on clinical outcomes.

Risk factors for encapsulating peritoneal sclerosis: Analysis of a 36-year experience in a University Hospital

AIM

Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication that occurs in peritoneal dialysis (PD) therapy. The present study aimed to identify the risk factors, especially peritonitis and biocompatible PD fluid.

METHODS

The study included 703 patients who received PD between January 1980 and March 2015 at two centres. The patients were divided into two groups: those who had developed EPS (EPS group: n = 44) and those who had no documentary evidence of EPS (non-EPS group: n = 659). The independent risks of EPS were determined by univariate and multivariate logistic models.

RESULTS

Encapsulating peritoneal sclerosis occurred in 44/703 (6.3%) patients between January 1980 and March 2015. In multivariate logistic models of risk factors correlated with EPS, dialysate to plasma creatinine ratio (D/P Cr) by peritoneal equilibration test (PET) and history of peritonitis were risk factors for EPS development (P < 0.01, respectively) in addition to PD duration. Especially, total duration of peritonitis, defined by period between onset and resolution of peritonitis, was an important risk factor for EPS development in patients with a history of peritonitis. Receiver operating characteristic (ROC) curve analysis revealed that cut-off point for EPS development was 36 days. Moreover, biocompatible PD fluid contributed to decreased EPS development.

CONCLUSION

Both the longer duration of peritonitis and higher D/P Cr, as well as the longer PD duration, were risk factors for EPS development. Furthermore, use of biocompatible PD fluid contributed to the decrease in EPS development.

After peritoneal dialysis discontinuation: When will we remove peritoneal dialysis catheter?

Most of the peritoneal dialysis patients stop their peritoneal dialysis therapy and transfer to hemodialysis or kidney transplantation. In Japan, most end-stage kidney disease patients select hemodialysis after peritoneal dialysis discontinuation. Peritoneal dialysis catheter will be removed after stopping peritoneal dialysis. If peritoneal dialysis patients suffer from refractory peritonitis or severe tunnel infection, we remove the peritoneal dialysis catheter immediately. However, the causes of peritoneal dialysis discontinuation are ultrafiltration failure or peritoneal membrane dysfunction, and we have to consider the timing of peritoneal dialysis catheter removal. Encapsulating peritoneal sclerosis is the most important adverse event of peritoneal dialysis. And encapsulating peritoneal sclerosis often develops after stopping peritoneal dialysis. Risk factors associated with encapsulating peritoneal sclerosis are high peritoneal equilibration test values, longer peritoneal dialysis period, frequent peritonitis, and so on. There is no evidence to prevent encapsulating peritoneal sclerosis completely. Therefore, we can preserve the peritoneal dialysis catheter and assess the changes of peritoneal function after peritoneal dialysis discontinuation, if patient is suspected to have high risk of encapsulating peritoneal sclerosis.

Significant Decreasing Incidence of Encapsulating Peritoneal Sclerosis in the Dutch Population of Peritoneal Dialysis Patients

The Dutch Encapsulating Peritoneal Sclerosis (EPS) Registry was started in 2009. Cases were identified by contacting all Dutch nephrologists twice yearly. The predefined criteria for EPS allowed for inclusion of patients with diagnosed and suspected EPS. Cases registered between January 2009 and January 2015 were analyzed with follow-up until September 2015. Fifty-three EPS cases were identified, of which 28.3% were post-transplantation EPS cases. Fourteen patients were initially categorized as suspected EPS, of whom 13 developed EPS. A remarkable 6-fold decrease in the yearly incidence of EPS was observed, from 0.85% in 2009 to 0.14% in 2014. This decrease could not be explained by a decrease in the number of PD patients or average duration of PD treatment in this period. Two-year survival of EPS patients was 52%. The use of tamoxifen and surgical interventions increased significantly over the years. Tamoxifen-treated cases showed a trend to better patient survival and post-transplantation EPS had a significantly favorable outcome. In conclusion, the incidence of EPS has declined significantly in the Netherlands from 2009 to 2014.

Encapsulating Peritoneal Sclerosis

Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication of peritoneal dialysis. In this review, we describe the clinical picture and histologic changes to the peritoneal membrane that are associated with EPS and provide an update on current diagnosis and management. We also discuss the recent studies that have suggested that the use of more biocompatible solutions containing lower concentrations of glucose degradation product that often are pH neutral in combination with a change in clinical practice (reducing glucose exposure and monitoring peritoneal membrane function) might ameliorate peritoneal degeneration, reduce the incidence of EPS, and minimize the severity of the disease.

Effective Remedy for Encapsulating Peritoneal Sclerosis with Ureteroileal Fistula

Encapsulating peritoneal sclerosis (EPS), treated with surgical enterolysis as a final option, may become refractory to surgical intervention due to intraperitoneal complications. We report the case of a 59-year-old man presenting with EPS who underwent enterolysis at the age of 50, following 15 years of peritoneal dialysis (PD) and peritonitis. During the patient's first surgery, complete surgical enterolysis could not be performed due to severe intestinal adhesions with a deteriorated/calcified small bowel. Six months after the surgery, the obstructive bowel symptoms occurred several times a year. Nine years later, the patient suffered cystitis-like symptoms and fecal discharge from the urinary meatus. The patient was subsequently diagnosed with EPS recurrence with ureteroileal fistula between the right ureter and ileum. During the second surgical intervention, we conducted a divided jejunostomy, as surgical enterolysis and fistulectomy were unachievable due to severe ileal adhesion with calcified capsule and inflammation. Thereafter, symptoms reduced dramatically and oral intake became possible. Three years following surgery, the patient's condition is improved, with no evidence of EPS recurrence or cystitis-like symptoms. Although EPS with ureteroileal fistula is extremely rare, we propose that jejunostomy may be an effective treatment option for patients with EPS refractory to surgical enterolysis or intestinal bypass due to intraperitoneal complications.

Dissolved molecular hydrogen (H2) in Peritoneal Dialysis (PD) solutions preserves mesothelial cells and peritoneal membrane integrity

Background

Peritoneal dialysis (PD) is used as renal replacement therapy in patients with end-stage kidney disease. However, peritoneal membrane failure remains problematic and constitutes a critical cause of PD discontinuation. Recent studies have revealed the unique biological action of molecular hydrogen (H₂) as an anti-oxidant, which ameliorates tissue injury. In the present study, we aimed to examine the effects of H₂ on the peritoneal membrane of experimental PD rats.

Method

Eight-week-old male Sprague-Dawley rats were divided into the following groups (n = 8–11 each) receiving different test solutions: control group (no treatment), PD group (commercially available lactate-based neutral 2.5% glucose PD solution), and H₂PD group (PD solution with dissolved H₂ at 400 ppb). Furthermore, the influence of iron (FeCl₃: 5 μM: inducer of oxidative cellular injury) in the respective PD solutions was also examined (Fe-PD and Fe-H₂PD groups). The H₂PD solution was manufactured by bathing a PD bag in H₂-oversaturated water created by electrolysis of the water. Twenty mL of the test solutions were intraperitoneally injected once a day for 10 days. Parietal peritoneum samples and cells collected from the peritoneal surface following treatment with trypsin were subjected to analysis.

Results

In the PD group as compared to controls, a mild but significant sub-mesothelial thickening was observed, with increase in the number of cells in the peritoneal surface tissue that were positive for apoptosis, proliferation and vimentin, as seen by immunostaining. There were significantly fewer of such changes in the H₂PD group, in which there was a dominant presence of M2 (CD163+) macrophages in the peritoneum. The Fe-PD group showed a significant loss of mesothelial cells with sub-mesothelial thickening, these changes being ameliorated in the Fe-H₂PD group.

Conclusion

H₂-dissolved PD solutions could preserve mesothelial cells and peritoneal membrane integrity in PD rats. Clinical application of H₂ in PD could be a novel strategy for protection of peritoneal tissue during PD treatment.

Absence of Post-Transplantation Encapsulating Peritoneal Sclerosis after Relatively Short Exposure to Peritoneal Dialysis: Prospective Analysis Using Repeated Abdominal CT Scanning

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is the most severe complication of peritoneal dialysis (PD). Several retrospective reports published between 2007 and 2009 have suggested an increasing incidence of EPS occurring after kidney transplantation. We conducted a prospective observational study to determine the incidence of post-transplantation EPS and identify possible risk factors.

METHODS

Consecutive PD patients undergoing kidney transplantation between 2009 and 2013 were included. Encapsulating peritoneal sclerosis was defined as gastrointestinal obstruction combined with radiological evidence of EPS. Gastrointestinal symptoms were assessed using a self-administered Gastrointestinal Symptom Rating Scale (GSRS) questionnaire. Abdominal computed tomography (CT) was performed prospectively at 6 and 18 months post-transplantation. The primary end point was EPS during follow-up.

RESULTS

Fifty-three PD patients were included (age 51 ± 14 years). Mean PD duration was 31.3 months. Peritoneal dialysis solutions low in glucose degradation products and icodextrin were used by 86.8% of patients. A fast or average-fast transport status was documented in 83.0%. After a median follow-up of 19 months, complete data of 47 patients were available for analysis. None of the patients developed clinical or radiological signs of EPS. The GSRS score improved from 1.87 to 1.55 (p = 0.024) and body weight increased from 75.9 to 78.3 kg (p = 0.003). Only 1 patient had new onset localized (< 20%) peritoneal thickening on CT 22 months post-transplantation.

CONCLUSION

Post-transplantation EPS did not develop in this cohort of patients with a relatively short time of PD exposure. This suggests that these patients can be transplanted safely without concern for the development of EPS, at least within the follow-up period of 19 months.

Recommendations for pathological diagnosis on biopsy samples from peritoneal dialysis patients

Peritoneal dialysis (PD) has been established as an essential renal replacement therapy for patients with end stage renal disease during the past half century. Histological evaluation of the peritoneal membrane has contributed to the pathophysiological understanding of PD-related peritoneal injury such as peritonitis, fibrosis, and encapsulating peritoneal sclerosis (EPS). Hyalinizing peritoneal sclerosis (HPS), also known as simple sclerosis, is observed in almost all of PD patients. HPS is morphologically characterized by fibrosis of the submesothelial interstitium and hyalinizing vascular wall, particularly of the post-capillary venule (PCV). Two histological factors, the thickness of submesothelial compact zone (SMC) and the lumen/vessel ratio (L/V) at the PCV, have been used for the quantitative evaluation of HPS. The measuring system on SMC thickness and L/V ratio is easy and useful for evaluating the severity of HPS. On the other hand, EPS is characterized by unique encapsulation of the intestines by an "encapsulating membrane". This newly formed membranous structure covers the visceral peritoneum of the intestines, which contains fibrin deposition, angiogenesis, and proliferation of fibroblast-like cells and other inflammatory cells. This review will cover the common understandings of PD-related peritoneal alterations and provide a basic platform for clinical applications and future studies in this field.

Newly Developed Neutralized pH Icodextrin Dialysis Fluid: Nonclinical Evaluation

A two-compartment system (NICOPELIQ; NICO, Terumo Co., Tokyo, Japan) has recently been developed to neutralize icodextrin peritoneal dialysis fluid (PDF). In this study, a nonclinical evaluation of NICO was carried out to evaluate biocompatibility as well as water transport ability. Glucose degradation products (GDPs) in the icodextrin PDFs were analyzed via high-performance liquid chromatography (HPLC). The cell viability of human peritoneal mesothelial cells derived from peritoneal dialysis effluent (PDE-HPMCs) was evaluated as well as the amount of lactate dehydrogenase (LDH) released after exposure to different PDFs (NICO and EXTRANEAL [EX, Baxter Healthcare Corp., Chicago, IL, USA]) and neutralized pH glucose PDF MIDPELIQ 250 (M250, Terumo). The water transport ability of NICO, EX, and M250 was tested using dialysis tube membranes with various pore sizes: 1, 2, 6-8, and 12-16 kDa. Although cell viability decreased by 30% after 30 min exposure to NICO, it was maintained for 6 h while a significant decrease was observed after 6 h exposure to EX. However, following adjustment of the pH to the same pre-exposure pH value, there was no significant difference in cell viability within the same pH group despite a doubling of the difference in the total amount of GDPs (44.6 ± 8.6 µM in NICO and 91.9 ± 9.5 µM in EX, respectively). In contrast, a significant decrease in cell viability was observed when the pH decreased to less than pH 6. Levels of released LDH, a cytotoxic marker, were within 5% after a 6-h exposure of NICO to PDE-HPMCs. There was no significant difference in water transport ability represented as overall osmotic gradients between NICO and EX. In conclusion, neutralization of icodextrin PDF is beneficial for maintaining cell viability and minimizing LDH release while water transport ability is comparable to the conventional icodextrin PDF.

Designing Epidemiology Studies to Determine the Incidence and Prevalence of Encapsulating Peritoneal Sclerosis (EPS)

The reported incidence and prevalence of encapsulating peritoneal sclerosis (EPS) varies markedly between North America, Europe, Japan, and Australia. Although this could reflect differences in clinical practice patterns and access to transplantation as there is no current test for early detection, and some patients may present many years after discontinuation of peritoneal dialysis (PD), there are concerns about under-reporting, particularly for those with milder forms. Currently, only PD vintage has been identified as a significant risk factor for developing EPS, although some patients can develop EPS within months of starting PD. As such, there is a need for epidemiological studies to determine the incidence and prevalence of EPS to allow for patient education and counselling in terms of dialysis modality choice and length of treatment. In addition, carefully designed epidemiological studies could potentially allow for the identification of risk factors and bio-markers that could then be used to identify patients at increased risk of developing EPS in the future. Typically, studies to date have been underpowered with inadequate longitudinal follow-up. We review the different types of epidemiological studies and provide information as to the number of patients to be recruited and the duration of follow-up required to determine the incidence and prevalence of EPS.

Age-Related Differences of Organism-Specific Peritonitis Rates: A Single-Center Experience

Peritonitis remains an important cause of morbidity and mortality in peritoneal dialysis (PD) patients, but its incidence and the distribution of causative organisms vary widely between institutions and age groups. This study was performed to investigate the recent status and risk factors of PD-related peritonitis and to clarify differences between age groups. We retrospectively reviewed the medical records of 119 PD patients treated at our department between January 2002 and January 2013. We calculated both overall and organism-specific peritonitis rates and also analyzed risk factors. Sixty-three episodes of peritonitis occurred during 261.5 patient-years for an incident rate of 0.24 episodes/patient-year. Multivariate analysis showed that older age (≥65 years) and hypoalbuminemia (<3.0 g/dL) were associated with an increased risk of peritonitis (P = 0.035 and P = 0.029, respectively). In elderly patients (≥65 years old), the rate of peritonitis due to Gram-positive and Gram-negative bacteria was 0.17 and 0.08 episodes/patient-year, respectively, and Gram-positive peritonitis was markedly more frequent than in younger patients (<65 years old). In particular, there was a high frequency of Staphylococcus aureus peritonitis in elderly patients (0.09 episodes/patient-year) and it had a poor outcome. At our department, the risk of peritonitis was increased in older patients and patients with hypoalbuminemia. The distribution of causative organisms was markedly different between age groups and analysis of organism-specific peritonitis rates helped to identify current problems with our PD program.

The number of patients with severe encapsulating peritoneal sclerosis is decreasing in a large referral center in Germany

Background

Encapsulating peritoneal sclerosis (EPS) is the most severe complication associated with long-term peritoneal dialysis (PD). Previous studies noticed a sharp decline in new patients with severe EPS. We investigated the number of severe EPS patients in our large referral center over almost 20 years.

Methods

All late-stage EPS patients who underwent major surgery due to extensive symptoms caused by bowel obstruction (vomiting, abdominal pain, and weight loss) between March 1997 and end of December 2015 in our hospital were included in the present study. An index was calculated between the number of patients with severe EPS and the implanted PD catheters in our center.

Results

Between 1979 and 2015, a total of 745 PD catheters were implanted in our center, with a steady increase in the numbers between 2003 and 2015. First patient with severe EPS was treated in 1998, then a rise in the number of patients with EPS was present in 2005. The number of patients with EPS peaked in the period of 2010–2012 (15 patients within 3 years). Afterward, both the absolute numbers and the index between the number of patients with severe EPS and the implanted catheters demonstrated a prominent reduction in the next 3-year period from 2013 to 2015.

Conclusion

Our data support the hypothesis that there seems to be a decrease of late-stage EPS incidence over the last years, but data about milder or asymptomatic patients are lacking. This should be kept in mind while giving the patients information about different renal replacement therapies at start of dialysis.

Preventing peritoneal membrane fibrosis in peritoneal dialysis patients

Long-term peritoneal dialysis causes morphologic and functional changes in the peritoneal membrane. Although mesothelial-mesenchymal transition of peritoneal mesothelial cells is a key process leading to peritoneal fibrosis, and bioincompatible peritoneal dialysis solutions (glucose, glucose degradation products, and advanced glycation end products or a combination) are responsible for altering mesothelial cell function and proliferation, mechanisms underlying these processes remain largely unclear. Peritoneal fibrosis has 2 cooperative parts, the fibrosis process itself and the inflammation. The link between these 2 processes is frequently bidirectional, with each one inducing the other. This review outlines our current understanding about the definition and pathophysiology of peritoneal fibrosis, recent studies on key fibrogenic molecular machinery in peritoneal fibrosis, such as the role of transforming growth factor-β/Smads, transforming growth factor-β β/Smad independent pathways, and noncoding RNAs. The diagnosis of peritoneal fibrosis, including effluent biomarkers and the histopathology of a peritoneal biopsy, which is the gold standard for demonstrating peritoneal fibrosis, is introduced in detail. Several interventions for peritoneal fibrosis based on biomarkers, cytology, histology, functional studies, and antagonists are presented in this review. Recent experimental trials in animal models, including pharmacology and gene therapy, which could offer novel insights into the treatment of peritoneal fibrosis in the near future, are also discussed in depth.

Matrix metalloproteinase-2 as a superior biomarker for peritoneal deterioration in peritoneal dialysis

AIM: To investigate the efficacy of effluent biomarkers for peritoneal deterioration with functional decline in peritoneal dialysis (PD).

METHODS: From January 2005 to March 2013, the subjects included 218 PD patients with end-stage renal disease at 18 centers. Matrix metalloproteinase-2 (MMP-2), interleukin-6 (IL-6), hyaluronan, and cancer antigen 125 (CA125) in peritoneal effluent were quantified with enzyme-linked immunosorbent assay. Peritoneal solute transport rate was assessed by peritoneal equilibration test (PET) to estimate peritoneal deterioration.

RESULTS: The ratio of the effluent level of creatinine (Cr) obtained 4 h after injection (D) to that of plasma was correlated with the effluent levels of MMP-2 (ρ = 0.74, P < 0.001), IL-6 (ρ = 0.46, P < 0.001), and hyaluronan (ρ = 0.27, P < 0.001), but not CA125 (ρ = 0.13, P = 0.051). The area under receiver operating characteristic curve for the effluent levels of MMP-2, IL-6, and hyaluronan against high PET category were 0.90, 0.78, 0.62, and 0.51, respectively. No patient developed new-onset encapsulating peritoneal sclerosis for at least 1.5 years after peritoneal effluent sampling.

CONCLUSION: The effluent MMP-2 level most closely reflected peritoneal solute transport rate. MMP-2 can be a reliable indicator of peritoneal deterioration with functional decline.

Multidisciplinary clinical strategies for encapsulating peritoneal sclerosis in peritoneal dialysis: update from Japan

Peritoneal dialysis is established as a first-line standard renal replacement therapy for end-stage renal disease. However, the development of encapsulating peritoneal sclerosis has been a critical complication among long-term peritoneal dialysis patients. During the past decade, multidisciplinary approaches have been used to suppress encapsulating peritoneal sclerosis. The present article reviews the historical and present status of encapsulating peritoneal sclerosis in Japan.