Early Diagnostic Markers for Encapsulating Peritoneal Sclerosis: A Case-Control Study

Peritoneal equilibration testing: Your questions answered

The peritoneal equilibration test (PET), first described in 1987, is a semiquantitative assessment of peritoneal transfer characteristics in patients undergoing peritoneal dialysis. It is typically performed as a 4-h exchange using 2.27/2.5% dextrose dialysate with serial measurements of blood and dialysate creatinine, urea, and glucose concentrations. The percentage absorption of glucose and D/P creatinine ratio are used to determine peritoneal solute transfer rates. It is used to both help guide peritoneal dialysis prescriptions and to prognosticate. There are several derivative tests which have been described in the literature. In this review, we describe the original PET, the various iterations of the PET, the information gleaned, and the use in the setting of poor solute clearance and in the diagnosis of membrane dysfunction, and limitations of the PET.

Peritoneal effluent MicroRNA profile for detection of encapsulating peritoneal sclerosis

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a catastrophic complication of peritoneal dialysis (PD) with high mortality. Our aim is to develop a novel noninvasive microRNA (miRNA) test for EPS.

METHODS

We collected 142 PD effluents (EPS: 62 and non-EPS:80). MiRNA profiles of PD effluents were examined by a high-throughput real-time polymerase chain reaction (PCR) array to first screen. Candidate miRNAs were verified by single real-time PCR. The model for EPS prediction was evaluated by multiple logistic regression and machine learning.

RESULTS

Seven candidate miRNAs were identified from the screening of PCR-array of 377 miRNAs. The top five area under the curve (AUC) values with 5 miRNA-ratios were selected using 127 samples (EPS: 56 vs non-EPS: 71) to produce a receiver operating characteristic curve. After considering clinical characteristics and 5 miRNA-ratios, the accuracies of the machine learning model of Random Forest and multiple logistic regression were boosted to AUC 0.97 and 0.99, respectively. Furthermore, the pathway analysis of miRNA associated targeting genes and miRNA-compound interaction network revealed that these five miRNAs played the roles in TGF-β signaling pathway.

CONCLUSION

The model-based miRNA expressions in PD effluents may help determine the probability of EPS and provide further therapeutic opinion for EPS.

Traduction des Recommandations de l'ISPD pour l'évaluation du dysfonctionnement de la membrane péritonéale chez l'adulte

Informations concernant cette traductionDans le cadre d’un accord de partenariat entre l’ISPD et le RDPLF, le RDPLF est le traducteur français officiel des recommandations de l’ISPD. La traduction ne donne lieu à aucune compensation financière de la part de chaque société et le RDPLF s’est engagé à traduire fidèlement le texte original sous la responsabilité de deux néphrologues connus pour leur expertise dans le domaine. Avant publication le texte a été soumis à l’accord de l’ISPD. La traduction est disponible sur le site de l’ISPD et dans le Bulletin de la Dialyse à Domicile.Le texte est, comme l’original, libremement téléchargeable sous licence copyright CC By 4.0https://creativecommons.org/licenses/by/4.0/Cette traduction est destinée à aider les professionnels de la communauté francophone à prendre connaissance des recommandations de l’ISPD dans leur langue maternelle. Toute référence dans un article doit se faire au texte original en accès libre :Peritoneal Dialysis International https://doi.org/10.1177/0896860820982218 Dans les articles rédigés pour des revues françaises, conserver la référence à la version originale anglaise ci dessus, mais ajouter «version française  https://doi.org/10.25796/bdd.v4i3.62673"»TraducteursDr Christian Verger, néphrologue, président du RDPLFRDPLF, 30 rue Sere Depoin, 95300 Pontoise – FranceProfesseur Max Dratwa, néphrologueHôpital Universitaire Brugmann – Bruxelles – Belgique

Peritoneal Dialysis Guidelines 2019 Part 1 (Position paper of the Japanese Society for Dialysis Therapy)

Approximately 10 years have passed since the Peritoneal Dialysis Guidelines were formulated in 2009. Much evidence has been reported during the succeeding years, which were not taken into consideration in the previous guidelines, e.g., the next peritoneal dialysis PD trial of encapsulating peritoneal sclerosis (EPS) in Japan, the significance of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), the effects of icodextrin solution, new developments in peritoneal pathology, and a new international recommendation on a proposal for exit-site management. It is essential to incorporate these new developments into the new clinical practice guidelines. Meanwhile, the process of creating such guidelines has changed dramatically worldwide and differs from the process of creating what were “clinical practice guides.” For this revision, we not only conducted systematic reviews using global standard methods but also decided to adopt a two-part structure to create a reference tool, which could be used widely by the society’s members attending a variety of patients. Through a working group consensus, it was decided that Part 1 would present conventional descriptions and Part 2 would pose clinical questions (CQs) in a systematic review format. Thus, Part 1 vastly covers PD that would satisfy the requirements of the members of the Japanese Society for Dialysis Therapy (JSDT). This article is the duplicated publication from the Japanese version of the guidelines and has been reproduced with permission from the JSDT.

ISPD recommendations for the evaluation of peritoneal membrane dysfunction in adults: Classification, measurement, interpretation and rationale for intervention

Lay summary

Peritoneal dialysis (PD) uses the peritoneal membrane for dialysis. The peritoneal membrane is a thin layer of tissue that lines the abdomen. The lining is used as a filter to help remove extra fluid and poisonous waste from the blood. Everybody is unique. What is normal for one person’s membrane may be very different from another person’s. The kidney care team wants to provide each person with the best dialysis prescription for them and to do this they must evaluate the person’s peritoneal lining. Sometimes dialysis treatment itself can cause the membrane to change after some years. This means more assessments (evaluations) will be needed to determine whether the person’s peritoneal membrane has changed. Changes in the membrane may require changes to the dialysis prescription. This is needed to achieve the best dialysis outcomes. A key tool for these assessments is the peritoneal equilibration test (PET). It is a simple, standardized and reproducible tool. This tool is used to measure the peritoneal function soon after the start of dialysis. The goal is to understand how well the peritoneal membrane works at the start of dialysis. Later on in treatment, the PET helps to monitor changes in peritoneal function. If there are changes between assessments causing problems, the PET data may explain the cause of the dysfunction. This may be used to change the dialysis prescription to achieve the best outcomes. The most common problem with the peritoneal membrane occurs when fluid is not removed as well as it should be. This happens when toxins (poisons) in the blood cross the membrane more quickly than they should. This is referred to as a fast peritoneal solute transfer rate (PSTR). Since more efficient fluid removal is associated with better outcomes, developing a personal PD prescription based on the person’s PSTR is critically important. A less common problem happens when the membrane fails to work properly (also called membrane dysfunction) because the peritoneal membrane is less efficient, either at the start of treatment or developing after some years. If membrane dysfunction gets worse over time, then this is associated with progressive damage, scarring and thickening of the membrane. This problem can be identified through another change of the PET. It is called reduced ‘sodium dip’. Membrane dysfunction of this type is more difficult to treat and has many implications for the individual. If the damage is major, the person may need to stop PD. They would need to begin haemodialysis treatment (also spelled hemodialysis). This is a very important and emotional decision for individuals with kidney failure. Any decision that involves stopping PD therapy or transitioning to haemodialysis therapy should be made jointly between the clinical team, the person on dialysis and a caregiver, if requested. Although evidence is lacking about how often tests should be performed to determine peritoneal function, it seems reasonable to repeat them whenever there is difficulty in removing the amount of fluid necessary for maintaining the health and well-being of the individual. Whether routine evaluation of membrane function is associated with better outcomes has not been studied. Further research is needed to answer this important question as national policies in many parts of the world and the COVID-19 has placed a greater emphasis and new incentives encouraging the greater adoption of home dialysis therapies, especially PD. For Chinese and Spanish Translation of the Lay Summary, see Online Supplement Appendix 1.

Key recommendations

Guideline 1:

A pathophysiological taxonomy: A pathophysiological classification of membrane dysfunction, which provides mechanistic links to functional characteristics, should be used when prescribing individualized dialysis or when planning modality transfer (e.g. to automated peritoneal dialysis (PD) or haemodialysis) in the context of shared and informed decision-making with the person on PD, taking individual circumstances and treatment goals into account. (practice point)

Guideline 2a:

Identification of fast peritoneal solute transfer rate (PSTR): It is recommended that the PSTR is determined from a 4-h peritoneal equilibration test (PET), using either 2.5%/2.27% or 4.25%/3.86% dextrose/glucose concentration and creatinine as the index solute. (practice point) This should be done early in the course dialysis treatment (between 6 weeks and 12 weeks) (GRADE 1A) and subsequently when clinically indicated. (practice point)

Guideline 2b:

Clinical implications and mitigation of fast solute transfer: A faster PSTR is associated with lower survival on PD. (GRADE 1A) This risk is in part due to the lower ultrafiltration (UF) and increased net fluid reabsorption that occurs when the PSTR is above the average value. The resulting lower net UF can be avoided by shortening glucose-based exchanges, using a polyglucose solution (icodextrin), and/or prescribing higher glucose concentrations. (GRADE 1A) Compared to glucose, use of icodextrin can translate into improved fluid status and fewer episodes of fluid overload. (GRADE 1A) Use of automated PD and icodextrin may mitigate the mortality risk associated with fast PSTR. (practice point)

Guideline 3:

Recognizing low UF capacity: This is easy to measure and a valuable screening test. Insufficient UF should be suspected when either (a) the net UF from a 4-h PET is <400 ml (3.86% glucose/4.25% dextrose) or <100 ml (2.27% glucose /2.5% dextrose), (GRADE 1B) and/or (b) the daily UF is insufficient to maintain adequate fluid status. (practice point) Besides membrane dysfunction, low UF capacity can also result from mechanical problems, leaks or increased fluid absorption across the peritoneal membrane not explained by fast PSTR.

Guideline 4a:

Diagnosing intrinsic membrane dysfunction (manifesting as low osmotic conductance to glucose) as a cause of UF insufficiency: When insufficient UF is suspected, the 4-h PET should be supplemented by measurement of the sodium dip at 1 h using a 3.86% glucose/4.25% dextrose exchange for diagnostic purposes. A sodium dip ≤5 mmol/L and/or a sodium sieving ratio ≤0.03 at 1 h indicates UF insufficiency. (GRADE 2B)

Guideline 4b:

Clinical implications of intrinsic membrane dysfunction (de novo or acquired): in the absence of residual kidney function, this is likely to necessitate the use of hypertonic glucose exchanges and possible transfer to haemodialysis. Acquired membrane injury, especially in the context of prolonged time on treatment, should prompt discussions about the risk of encapsulating peritoneal sclerosis. (practice point)

Guideline 5:

Additional membrane function tests: measures of peritoneal protein loss, intraperitoneal pressure and more complex tests that estimate osmotic conductance and ‘lymphatic’ reabsorption are not recommended for routine clinical practice but remain valuable research methods. (practice point)

Guideline 6:

Socioeconomic considerations: When resource constraints prevent the use of routine tests, consideration of membrane function should still be part of the clinical management and may be inferred from the daily UF in response to the prescription. (practice point)

Non-invasive assessment of peritoneal membrane alterations

The peritoneal dialysis membrane is subject to remodelling in the course of peritoneal dialysis. In the absence of longitudinal morphological studies, this process is mainly studied indirectly by the investigation of changes in peritoneal transport. Non-invasive assessment of the peritoneum is also possible by assessment of substances that originate from peritoneal tissues and can be determined either as their gene expression in peritoneal effluent cells and/or as proteins in peritoneal effluent. Three of these biomarkers will be discussed, because longitudinal data are available. Cancer antigen 125 (CA 125) is present on the mesothelium,while its gene (MUC 16) is expressed in peritoneal effluent cells and is related to dialysate CA 125 protein. The constitutive production and the small intra-individual variability of 15% indicate its usefulness as a follow-up marker of mesothelial cell mass. Dialysate appearance rate is higher on biocompatible than on conventional solutions, but both decrease during long-term follow-up. Interleukin-6 (Il-6) is present in peritoneal effluent due to both transport from the circulation and local intraperitoneal production. Its appearance rate is unrelated to its gene expression in peritoneal cells. The intra-individual variation of effluent Il-6 averages 28%, hampering the interpretation of cross-sectional values. The relationships between effluent Il-6 and peritoneal transport have been interpreted as microinflammation, but are difficult to interprete due to mathematical coupling. Plasminogen activator inhibitor-1 (PAI-1) is encoded by the SERPINE 1 gene. A relationship is present between effluent concentration and gene expression. PAI-1 production is stimulated by glucose. PAI-1 appearance rate increases with PD duration. The sensitivity of effluent PAI-1 for the diagnosis of encapsulating peritoneal sclerosis was 100% one year prior to the diagnosis and the specificity 56%. It can be concluded that the discussed biomarkers are useful extensions to transport in assessment of the peritoneum during dialysis.  

Estimating risk of encapsulating peritoneal sclerosis accounting for the competing risk of death

Background

Risk of encapsulating peritoneal sclerosis (EPS) is strongly associated with the duration of peritoneal dialysis (PD), such that patients who have been on PD for some time may consider elective transfer to haemodialysis to mitigate the risk of EPS. There is a need to determine this risk to better inform clinical decision making, but previous studies have not allowed for the competing risk of death.

Methods

This study included new adult PD patients in Australia and New Zealand (ANZ; 1990–2010) or Scotland (2000–08) followed until 2012. Age, time on PD, primary renal disease, gender, data set and diabetic status were evaluated as predictors at the start of PD, then at 3 and 5 years after starting PD using flexible parametric competing risks models.

Results

In 17 396 patients (16 162 ANZ, 1234 Scotland), EPS was observed in 99 (0.57%) patients, less frequently in ANZ patients (n = 65; 0.4%) than in Scottish patients (n = 34; 2.8%). The estimated risk of EPS was much lower when the competing risk of death was taken into account (1 Kaplan–Meier = 0.0126, cumulative incidence function = 0.0054). Strong predictors of EPS included age, primary renal disease and time on PD. The risk of EPS was reasonably discriminated at the start of PD (C-statistic = 0.74–0.79) and this improved at 3 and 5 years after starting PD (C-statistic = 0.81–0.92).

Conclusions

EPS risk estimates are lower when calculated using competing risk of death analyses. A patient’s estimated risk of EPS is country-specific and can be predicted using age, primary renal disease and duration of PD.

Early Detection of Imminent Encapsulating Peritoneal Sclerosis: Free Water Transport, Selected Effluent Proteins, or Both?

Background

No diagnostic tool or methodology is currently available for early detection of imminent encapsulating peritoneal sclerosis (EPS). The objective of this study was to investigate the predictive value of free water transport (FWT) and construct a panel of peritoneal effluent proteins for EPS alone or in combination with FWT. These parameters could be incorporated in the follow-up of peritoneal dialysis (PD) patients.

Methods

A case-control study, nested in a longitudinal PD patient cohort, was conducted. Time-specific areas under the receiver operating characteristic (ROC) curve were calculated for FWT and effluent biomarkers at a lag time up to 3 years before EPS diagnosis. Free water transport was combined with appearance rates (AR) of biomarkers to assess their clinical validity.

Results

Free water transport volume and AR of effluent bio-markers were investigated in 11 EPS patients and 34 long-term PD patients. Diagnostic performance was best for FWT (area under the curve [AUC] 0.94) followed by plasminogen activator inhibitor (PAI-1) AR. Throughout, diagnostic panels of FWT and AR of cancer antigen 125 (CA125), interleukin-6 (IL-6), or (PAI-1) yielded specificity estimates above 84%. The combination of FWT and PAI-1 AR identified the largest proportion of EPS patients at 1 year prior to diagnosis (sensitivity 100%, specificity 94%).

Conclusion

Measurement of FWT is simple and has the highest predictive value for imminent EPS. The addition of effluent biomarkers provides an all-round insight into the state of the peritoneum. Our data indicate that combining FWT with either PAI-1, CA125, or IL-6 has the highest specificity. This is required to avoid unnecessary discontinuation of PD treatment.

High Intraperitoneal Interleukin-6 Levels Predict Peritonitis in Peritoneal Dialysis Patients: A Prospective Cohort Study

BACKGROUND

To evaluate the predictive value of dialysate interleukin-6 (IL-6) representing local subclinical intraperitoneal inflammation for the development of peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients.

METHODS

Stable prevalent CAPD patients were enrolled in this prospective study. IL-6 concentration in the overnight effluent was determined and expressed as the IL-6 appearance rate (IL-6AR). Patients were divided into 2 groups according to the median of IL-6AR and prospectively followed up until the first episode of peritonitis, cessation of PD, or the end of the study (December 30, 2017). The utility of IL-6AR in predicting peritonitis-free survival was analyzed using the Kaplan-Meier and Cox proportional hazards models.

RESULTS

A total of 149 patients were enrolled, including 72 males (48%) with mean age 52.0 ± 13.6 years and median PD duration 26 (5.9-45.5) months. During follow-up, 7,923 patient months were observed and 154 episodes of peritonitis occurred in 82 patients. Previous peritonitis episodes were significantly associated with log dialysate IL-6AR levels (β = 0.187 [0.022-0.299], p = 0.023). Patients in the high IL-6AR group showed a significantly inferior peritonitis-free survival when compared with their counterparts in the low IL-6AR group (48.8 vs. 67.7 months, p = 0.026), as well as higher treatment failure percentage of peritonitis (20.3 vs. 9.3%, p = 0.049). A multivariate Cox regression showed that high dialysate IL-6AR (hazard ratio [HR] 1.247 [1.052-1.478]; p = 0.011) and high serum C-reactive protein (HR 1.072 [1.005-1.144]; p = 0.036) were independent risk factors for inferior peritonitis-free survival.

CONCLUSION

This prospective study suggested that the intraperitoneal inflammation marker, dialysate IL-6 level, might be a potential predictor of peritonitis development in patients undergoing PD.

Hypoxia, cytokines and stromal recruitment: parallels between pathophysiology of encapsulating peritoneal sclerosis, endometriosis and peritoneal metastasis

Peritoneal response to various kinds of injury involves loss of peritoneal mesothelial cells (PMC), danger signalling, epithelial-mesenchymal transition and mesothelial-mesenchymal transition (MMT). Encapsulating peritoneal sclerosis (EPS), endometriosis (EM) and peritoneal metastasis (PM) are all characterized by hypoxia and formation of a vascularized connective tissue stroma mediated by vascular endothelial growth factor (VEGF). Transforming growth factor-β1 (TGF-β1) is constitutively expressed by the PMC and plays a major role in the maintenance of a transformed, inflammatory micro-environment in PM, but also in EPS and EM. Persistently high levels of TGF-β1 or stimulation by inflammatory cytokines (interleukin-6 (IL-6)) induce peritoneal MMT, adhesion formation and fibrosis. TGF-β1 enhances hypoxia inducible factor-1α expression, which drives cell growth, extracellular matrix production and cell migration. Disruption of the peritoneal glycocalyx and exposure of the basement membrane release low molecular weight hyaluronan, which initiates a cascade of pro-inflammatory mediators, including peritoneal cytokines (TNF-α, IL-1, IL-6, prostaglandins), growth factors (TGF-α, TGF-β, platelet-derived growth factor, VEGF, epidermal growth factor) and the fibrin/coagulation cascade (thrombin, Tissue factor, plasminogen activator inhibitor [PAI]-1/2). Chronic inflammation and cellular transformation are mediated by damage-associated molecular patterns, pattern recognition receptors, AGE-RAGE, extracellular lactate, pro-inflammatory cytokines, reactive oxygen species, increased glycolysis, metabolomic reprogramming and cancer-associated fibroblasts. The pathogenesis of EPS, EM and PM shows similarities to the cellular transformation and stromal recruitment of wound healing.

Effluent and serum protein N-glycosylation is associated with inflammation and peritoneal membrane transport characteristics in peritoneal dialysis patients

Mass spectrometric glycomics was used as an innovative approach to identify biomarkers in serum and dialysate samples from peritoneal dialysis (PD) patients. PD is a life-saving treatment worldwide applied in more than 100,000 patients suffering from chronic kidney disease. PD treatment uses the peritoneum as a natural membrane to exchange waste products from blood to a glucose-based solution. Daily exposure of the peritoneal membrane to these solutions may cause complications such as peritonitis, fibrosis and inflammation which, in the long term, lead to the failure of the treatment. It has been shown in the last years that protein N-glycosylation is related to inflammatory and fibrotic processes. Here, by using a recently developed MALDI-TOF-MS method with linkage-specific sialic acid derivatisation, we showed that alpha2,6-sialylation, especially in triantennary N-glycans from peritoneal effluents, is associated with critical clinical outcomes in a prospective cohort of 94 PD patients. Moreover, we found an association between the levels of presumably immunoglobulin-G-related glycans as well as galactosylation of diantennary glycans with PD-related complications such as peritonitis and loss of peritoneal mesothelial cell mass. The observed glycomic changes point to changes in protein abundance and protein-specific glycosylation, representing candidate functional biomarkers of PD and associated complications.

A prospective, proteomics study identified potential biomarkers of encapsulating peritoneal sclerosis in peritoneal effluent

Encapsulating peritoneal sclerosis (EPS) is a potentially devastating complication of peritoneal dialysis (PD). Diagnosis is often delayed due to the lack of effective and accurate diagnostic tools. We therefore examined peritoneal effluent for potential biomarkers that could predict or confirm the diagnosis of EPS and would be valuable in stratifying at-risk patients and driving appropriate interventions. Using prospectively collected samples from the Global Fluid Study and a cohort of Greek PD patients, we utilized 2D SDSPAGE/ MS and iTRAQ to identify changes in the peritoneal effluent proteome from patients diagnosed with EPS and controls matched for treatment exposure. We employed a combinatorial peptide ligand library to compress the dynamic range of protein concentrations to aid identification of low-abundance proteins. In patients with stable membrane function, fibrinogen γ-chain and heparan sulphate proteoglycan core protein progressively increased over time on PD. In patients who developed EPS, collagen-α1(I), γ-actin and Complement factors B and I were elevated up to five years prior to diagnosis. Orosomucoid-1 and a2-HS-glycoprotein chain-B were elevated about one year before diagnosis, while apolipoprotein A-IV and α1-antitrypsin were decreased compared to controls. Dynamic range compression resulted in an increased number of proteins detected with improved resolution of protein spots, compared to the full fluid proteome. Intelectin-1, dermatopontin, gelsolin, and retinol binding protein-4 were elevated in proteome-mined samples from patients with EPS compared to patients that had just commenced peritoneal dialysis. Thus, prospective analysis of peritoneal effluent uncovered proteins indicative of inflammatory and pro-fibrotic injury worthy of further evaluation as diagnostic/prognostic markers.

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.

Selective Blocking of TNF Receptor 1 Attenuates Peritoneal Dialysis Fluid Induced Inflammation of the Peritoneum in Mice

Chronic inflammatory conditions during peritoneal dialysis (PD)-treatment lead to the impairment of peritoneal tissue integrity. The resulting structural and functional reorganization of the peritoneal membrane diminishes ultrafiltration rate and thereby enhances mortality by limiting dialysis effectiveness over time. Tumour necrosis factor (TNF) and its receptors TNFR1 and TNFR2 are key players during inflammatory processes. To date, the role of TNFR1 in peritoneal tissue damage during PD-treatment is completely undefined. In this study, we used an acute PD-mouse model to investigate the role of TNFR1 on structural and morphological changes of the peritoneal membrane. TNFR1-mediated TNF signalling in transgenic mice expressing human TNFR1 was specifically blocked by applying a monoclonal antibody (H398) highly selective for human TNFR1 prior to PD-treatment. Cancer antigen-125 (CA125) plasma concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Western blot analyses were applied to determine TNFR2 protein concentrations. Histological staining of peritoneal tissue sections was performed to assess granulocytes within the peritoneal membrane as well as the content of hyaluronic acid and collagen. We show for the first time that the number of granulocytes within the peritoneal membrane is significantly reduced in mice pre-treated with H398. Moreover, we demonstrate that blocking of TNFR1 not only influences CA125 values but also hyaluronic acid and collagen contents of the peritoneal tissue in these mice. These results strongly suggest that TNFR1 inhibition attenuates peritoneal damage caused by peritoneal dialysis fluid (PDF) and therefore may represent a new therapeutic approach in the treatment of PD-related side effects.

Vascular Endothelial Cell Injury Is an Important Factor in the Development of Encapsulating Peritoneal Sclerosis in Long-Term Peritoneal Dialysis Patients

Background and Objectives

Encapsulating peritoneal sclerosis (EPS) is a rare but serious and life-threatening complication of peritoneal dialysis (PD). However, the precise pathogenesis remains unclear; in addition, predictors and early diagnostic biomarkers for EPS have not yet to be established.

Methods

Eighty-three peritoneal membrane samples taken at catheter removal were examined to identify pathological characteristics of chronic peritoneal deterioration, which promotes EPS in patients undergoing long-term PD treatment with low occurrence of peritonitis.

Results

According to univariable logistic regression analysis of the pathological findings, thickness of the peritoneal membrane (P = 0.045), new membrane formation score (P = 0.006), ratio of luminal diameter to vessel diameter (L/V ratio, P<0.001), presence of CD31-negative vessels (P = 0.021), fibrin deposition (P<0.001), and collagen volume fraction (P = 0.018) were associated with EPS development. In analyses of samples with and without EPS matched for PD treatment period, non-diabetes, and PD solution, univariable analysis identified L/V ratio (per 0.1 increase: odds ratio (OR) 0.44, P = 0.003) and fibrin deposition (OR 6.35, P = 0.027) as the factors associated with EPS. L/V ratio was lower in patients with fibrin exudation than in patients without fibrin exudation.

Conclusions

These findings suggest that damage to vascular endothelial cells, as represented by low L/V ratio, could be a predictive finding for the development of EPS, particularly in long-term PD patients unaffected by peritonitis.

Peritoneal inflammation precedes encapsulating peritoneal sclerosis: results from the GLOBAL Fluid Study

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is an uncommon condition, strongly associated with a long duration of peritoneal dialysis (PD), which is itself associated with increased fibrosis in the peritoneal membrane. The peritoneal membrane is inflamed during PD and inflammation is often associated with fibrosis. We hypothesized that patients who subsequently develop EPS might have a more inflamed peritoneal membrane during PD.

METHODS

We performed a nested, case-control study identifying all EPS cases in the UK arm of the GLOBAL Fluid Study and matching them by centre and duration of PD with two to three controls. Dialysate and plasma samples were taken during repeated peritoneal equilibration tests prior to cessation of PD from cases and controls. Samples were assayed by electrochemiluminescence immunoassay for interleukin-1β (IL-1β), tumour necrosis factor α (TNF-α), interferon-γ (IFN-γ) and IL-6. Results were analysed by linear mixed models adjusted for age and time on PD.

RESULTS

Eleven EPS cases were matched with 26 controls. Dialysate TNF-α {0.64 [95% confidence interval (CI) 0.23, 1.05]} and IL-6 [0.79 (95% CI 0.03, 1.56)] were significantly higher in EPS cases, while IL-1β [1.06 (95% CI -0.11, 2.23)] and IFN-γ [0.62 (95% CI -0.06, 1.29)] showed a similar trend. Only IL-6 was significantly higher in the plasma [0.42 (95% CI 0.07, 0.78)]. Solute transport was not significantly different between cases and controls but did increase in both groups with the duration of PD.

CONCLUSIONS

The peritoneal cavity has higher levels of inflammatory cytokines during PD in patients who subsequently develop EPS, but neither inflammatory cytokines nor peritoneal solute transport clearly discriminates EPS cases. Increased systemic inflammation is also evident and is probably driven by increased peritoneal inflammation.

Overcoming the Underutilisation of Peritoneal Dialysis

Peritoneal dialysis is troubled with declining utilisation as a form of renal replacement therapy in developed countries. We review key aspects of therapy evidenced to have a potential to increase its utilisation. The best evidence to repopulate PD programmes is provided for the positive impact of timely referral and systematic and motivational predialysis education: average odds ratio for instituting peritoneal dialysis versus haemodialysis was 2.6 across several retrospective studies on the impact of predialysis education. Utilisation of PD for unplanned acute dialysis starts facilitated by implantation of peritoneal catheters by interventional nephrologists may diminish the vast predominance of haemodialysis done by central venous catheters for unplanned dialysis start. Assisted peritoneal dialysis can improve accessibility of home based dialysis to elderly, frail, and dependant patients, whose quality of life on replacement therapy may benefit most from dialysis performed at home. Peritoneal dialysis providers should perform close monitoring, preventing measures, and timely prophylactic therapy in patients judged to be prone to EPS development. Each peritoneal dialysis programme should regularly monitor, report, and act on key quality indicators to manifest its ability of constant quality improvement and elevate the confidence of interested patients and financing bodies in the programme.

The Association of Effluent Ca125 with Peritoneal Dialysis Technique Failure

♦

BACKGROUND AND OBJECTIVES

Cancer antigen 125 (CA125) reflects the mesothelial cell mass lining the peritoneal membrane in individual patients. A decline or absence of mesothelial cells can be observed with duration of peritoneal dialysis (PD) therapy. Technique failure due to peritoneal membrane malfunction becomes of greater importance after 2 years of PD therapy in comparison to the initial period. In this study, we aimed to investigate the association between effluent CA125 and technique survival in incident PD patients with a PD therapy period of at least 2 years. ♦

METHODS

Within the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), a Dutch multicenter cohort including 2,000 incident dialysis patients, we identified all PD patients who developed technique failure after 2 years of PD therapy and randomly selected a number of them as cases in a nested case-control study. Controls were PD patients matched on follow-up time without technique failure. Cases and controls were included if they had a dialysate specimen available within 24 ± 6 months of PD therapy for retrospective CA125 determinations. Odds ratios for technique failure related to CA125 were estimated. We used a prospective cohort with incident PD patients from the Academic Medical Center-University of Amsterdam (AMC) for replication of effect estimates. In these patients, absolute risk of technique failure was estimated and related to effluent CA125 levels. ♦

RESULTS

A total of 38 PD patients were selected from the NECOSAD cohort. From the AMC cohort as replication cohort, 91 PD patients were included. Incidence rates of PD technique failure per 100 patient-years were 16.3 in the NECOSAD cohort and 12.9 in the AMC cohort. In both study populations CA125 levels below 12 - 14 kU/L were associated with an increased risk for technique failure. Technique survival rates in the AMC were 87% in patients with levels of CA125 above 12.1 kU/L and 65% for those with CA125 levels below this threshold after a maximum 5-year follow-up. ♦

CONCLUSIONS

Patients with high CA125 levels after at least 2 years of PD therapy tend to have better technique survival than patients with low CA125 levels. These results support the importance of effluent CA125 as a risk factor for dropout in long-term PD therapy.

Encapsulating peritoneal sclerosis is associated with T-cell activation

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is an excessive fibrotic response of the peritoneum that may occur after long-term peritoneal dialysis (PD). The underlying pathophysiology is poorly understood, but involvement of peritoneal inflammatory T helper 1 cells may be pivotal.

METHODS

Soluble interleukin-2 receptor alpha (sCD25) concentration was measured as a marker for T-cell activation in serum and ascites from EPS patients and various control patient groups. Peritoneal biopsies were stained for the presence of T cells, and T cells isolated from ascites of EPS patients were characterized in detail for differentiation status and cytokine expression.

RESULTS

Serum sCD25 concentrations are significantly and specifically increased in EPS patients compared with haemodialysis, PD and predialysis patients. Peritoneal effluent of stable PD patients contains very low levels of sCD25, while sCD25 levels in ascites of EPS patients are high and indicative of local production. In the years preceding the diagnosis of EPS, the serum sCD25 concentrations increased while remaining at stable levels in control PD patients. The peritoneum and ascites of EPS patients showed a significant influx of T cells with relatively increased numbers of CD4(+) T cells. These T cells were fully differentiated and displayed a T helper 1 cell type with a pro-inflammatory cytokine profile.

CONCLUSIONS

Increased serum sCD25 concentrations and peritoneal lymphocytosis in EPS patients indicate the involvement of activated T cells in the pathophysiology of excessive fibrosis.

CD4-Positive T Cells and M2 Macrophages Dominate the Peritoneal Infiltrate of Patients with Encapsulating Peritoneal Sclerosis

Background

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Previously, it has been shown that infiltrating CD4-positive T cells and M2 macrophages are associated with several fibrotic conditions. Therefore, the characteristics of the peritoneal cell infiltrate in EPS may be of interest to understand EPS pathogenesis. In this study, we aim to elucidate the composition of the peritoneal cell infiltrate in EPS patients and relate the findings to clinical outcome.

Study Design, Setting, and Participants

We studied peritoneal membrane biopsies of 23 EPS patients and compared them to biopsies of 15 PD patients without EPS. The cellular infiltrate was characterized by immunohistochemistry to detect T cells(CD3-positive), CD4-positive (CD4+) and CD8-positive T cell subsets, B cells(CD20-positive), granulocytes(CD15-positive), macrophages(CD68-positive), M1(CD80-positive), and M2(CD163-positive) macrophages. Tissues were analysed using digital image analysis. Kaplan-Meier survival analysis was performed to investigate the survival in the different staining groups.

Results

The cellular infiltrate in EPS biopsies was dominated by mononuclear cells. For both CD3 and CD68, the median percentage of area stained was higher in biopsies of EPS as opposed to non-EPS patients (p<0.001). EPS biopsies showed a higher percentage of area stained for CD4 (1.29%(0.61-3.20)) compared to CD8 (0.71%(0.46-1.01), p = 0.04), while in the non-EPS group these cells were almost equally represented (respectively 0.28%(0.05-0.83) versus 0.22%(0.17-0.43), p = 0.97). The percentage of area stained for both CD80 and CD163 was higher in EPS than in non-EPS biopsies (p<0.001), with CD163+ cells being the most abundant phenotype. Virtually no CD20-positive and CD15-positive cells were present in biopsies of a subgroup of EPS patients. No relation was found between the composition of the mononuclear cell infiltrate and clinical outcome.

Conclusions

A characteristic mononuclear cell infiltrate consisting of CD4+ and CD163+ cells dominates the peritoneum of EPS patients. These findings suggest a role for both CD4+ T cells and M2 macrophages in the pathogenesis of EPS.

Encapsulating peritoneal sclerosis-a rare but devastating peritoneal disease

Encapsulating peritoneal sclerosis (EPS) is a devastating but, fortunately, rare complication of long-term peritoneal dialysis. The disease is associated with extensive thickening and fibrosis of the peritoneum resulting in the formation of a fibrous cocoon encapsulating the bowel leading to intestinal obstruction. The incidence of EPS ranges between 0.7 and 3.3% and increases with duration of peritoneal dialysis therapy. Dialysis fluid is hyperosmotic, hyperglycemic, and acidic causing chronic injury and inflammation in the peritoneum with loss of mesothelium and extensive tissue fibrosis. The pathogenesis of EPS, however, still remains uncertain, although a widely accepted hypothesis is the "two-hit theory," where, the first hit is chronic peritoneal membrane injury from long standing peritoneal dialysis followed by a second hit such as an episode of peritonitis, genetic predisposition and/or acute cessation of peritoneal dialysis, leading to EPS. Recently, EPS has been reported in patients shortly after transplantation suggesting that this procedure may also act as a possible second insult. The process of epithelial-mesenchymal transition of mesothelial cells is proposed to play a central role in the development of peritoneal sclerosis, a common characteristic of patients on dialysis, however, its importance in EPS is less clear. There is no established treatment for EPS although evidence from small case studies suggests that corticosteroids and tamoxifen may be beneficial. Nutritional support is essential and surgical intervention (peritonectomy and enterolysis) is recommended in later stages to relieve bowel obstruction.

Hepatocyte growth factor signalizes peritoneal membrane failure in peritoneal dialysis

Background

Hepatocyte growth factor (HGF) counteracts peritoneal fibrosis in animal models and in-vitro studies, but no study explored effluent HGF in peritoneal dialysis (PD) patients with ultrafiltration failure (UFF). Our aim was to assess the relationship between effluent HGF with UF profile, free water transport (FWT) and small-solute transport.

Methods

We performed 4-hour, 3.86% PET with additional UF measurement at 60 minutes in 68 PD patients. MTAC_creatinine, FWT, small-pore ultrafiltration, and effluent HGF were quantified.

Results

Effluent HGF negatively correlated with UF (r = −0.80, p = 0.009) and FWT (r = −0.69, p = 0.04). Patients with UFF had higher dialysate HGF (103 pg/mL vs 77 pg/mL, p = 0.018) and, although not statistically significant, those with FWT compromise had also higher dialysate HGF compared with subgroup of UFF without FWT compromise (104 pg/mL vs 88 pg/mL, p = 0.08). FWT ≤ 45% without clinical UFF was documented in some patients who also had increased effluent HGF.

Conclusions

Dialysate HGF concentration is significantly higher among patients with UFF, specially, if FWT is impaired, being a sign of peritoneal membrane deterioration.

Peritoneal effluent MMP-2 and PAI-1 in encapsulating peritoneal sclerosis

BACKGROUND

Recently, the use of effluent matrix metalloproteinase 2 (MMP-2) and plasminogen activator inhibitor 1 (PAI-1) as potential biomarkers of peritoneal fibrosis has been demonstrated during longitudinal follow-up of incident peritoneal dialysis (PD) patients. This study focuses on effluent MMP-2 and PAI-1 as early diagnostic markers in the preceding years of patients who develop encapsulating peritoneal sclerosis (EPS).

STUDY DESIGN

Diagnostic test study.

SETTINGS & PARTICIPANTS

PD patients who developed EPS were compared with controls using a 1:3 case-control design with a minimum PD duration of 57 months.

INDEX TESTS

Dialysate appearance rates of MMP-2 and PAI-1.

REFERENCE TEST

EPS cases identified by 2 experienced nephrologists and a radiologist based on predefined criteria.

RESULTS

11 patients developed EPS within our center. The time course of MMP-2 appearance rates, studied by means of a linear repeated-measures model 4 years prior to the diagnosis of EPS, showed no difference between long-term controls and patients with EPS. In contrast, higher PAI-1 appearance rates were found in patients with EPS compared with controls (P=0.01). At a lag time of 1 year prior to EPS diagnosis, time-specific receiver operating characteristic curve analyses indicated a discriminative ability for PAI-1 appearance rate of 0.77 (95% CI, 0.63-0.91). A discriminative capacity was absent for those of MMP-2.

LIMITATIONS

Low event rate of EPS prevented independent validation in this single-center study.

CONCLUSIONS

Elevated levels of PAI-1 appearance rates are present in patients who develop EPS, pointing to progressive peritoneal fibrosis and sclerosis. The PAI-1 appearance rate has fair discriminative capacity from 3 years prior to EPS diagnosis. Therefore, effluent PAI-1 may aid in monitoring peritoneal fibrosis and serve as a biomarker for EPS.

Patients with encapsulating peritoneal sclerosis have increased peritoneal expression of connective tissue growth factor (CCN2), transforming growth factor-β1, and vascular endothelial growth factor

INTRODUCTION

Encapsulating peritoneal sclerosis (EPS) is a devastating complication of peritoneal dialysis (PD). The pathogenesis is not exactly known and no preventive strategy or targeted medical therapy is available. CCN2 has both pro-fibrotic and pro-angiogenic actions and appears an attractive target. Therefore, we studied peritoneal expression of CCN2, as well as TGFβ1 and VEGF, in different stages of peritoneal fibrosis.

MATERIALS AND METHODS

Sixteen PD patients were investigated and compared to 12 hemodialysis patients and four pre-emptively transplanted patients. Furthermore, expression was investigated in 12 EPS patients in comparison with 13 PD and 12 non-PD patients without EPS. Peritoneal tissue was taken during kidney transplantation procedure or during EPS surgery. In a subset of patients, CCN2 protein levels in peritoneal effluent and plasma were determined. Samples were examined by qPCR, histology, immunohistochemistry, and ELISA.

RESULTS

Peritoneal CCN2 expression was 5-fold higher in PD patients compared to pre-emptively transplanted patients (P < 0.05), but did not differ from hemodialysis patients. Peritoneal expression of TGFβ1 and VEGF were not different between the three groups; neither was peritoneal thickness. Peritoneum of EPS patients exhibited increased expression of CCN2 (35-fold, P < 0.001), TGFβ1 (24-fold, P < 0.05), and VEGF (77-fold, P < 0.001) compared to PD patients without EPS. In EPS patients, CCN2 protein was mainly localized in peritoneal endothelial cells and fibroblasts. CCN2 protein levels were significantly higher in peritoneal effluent of EPS patients compared to levels in dialysate of PD patients (12.0 ± 4.5 vs. 0.91 ± 0.92 ng/ml, P < 0.01), while plasma CCN2 levels were not increased.

CONCLUSIONS

Peritoneal expression of CCN2, TGFβ1, and VEGF are significantly increased in EPS patients. In early stages of peritoneal fibrosis, only CCN2 expression is slightly increased. Peritoneal CCN2 overexpression in EPS patients is a locally driven response. The potential of CCN2 as biomarker and target for CCN2-inhibiting agents to prevent or treat EPS warrants further study.

Encapsulating peritoneal sclerosis in children

Encapsulating peritoneal sclerosis (EPS) is a rare but extremely serious complication of peritoneal dialysis (PD). While EPS has been well recognized in adults on long-term PD, and children can spend many years on PD before a transplant becomes available, only a small number of children with EPS have been described. Two European pediatric registries have recently reported on the prevalence, potential risk factors and outcomes of EPS in children. Although the prevalence of EPS is comparable to that published in adult registries, the outcome of pediatric EPS is significantly better and carries a lower mortality. All studies have shown a greater risk of EPS with a longer dialysis vintage, but it is not known why some individuals are susceptible to EPS development. In this review we discuss current views on the epidemiology, pathogenesis and management strategies for EPS. The hope of the authors is that this review will alert pediatric nephrologists to this rare but extremely serious complication of chronic PD. In the future, collaborative research and the establishment of a pediatric EPS registry may be of importance in helping pediatric nephrologists to recognize the early warning signs of EPS development and thereby to develop strategies for its prevention and optimal management.

Histological and clinical findings in patients with post-transplantation and classical encapsulating peritoneal sclerosis: a European multicenter study

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) commonly presents after peritoneal dialysis has been stopped, either post-transplantation (PT-EPS) or after switching to hemodialysis (classical EPS, cEPS). The aim of the present study was to investigate whether PT-EPS and cEPS differ in morphology and clinical course.

METHODS

In this European multicenter study we included fifty-six EPS patients, retrospectively paired-matched for peritoneal dialysis (PD) duration. Twenty-eight patients developed EPS after renal transplantation, whereas the other twenty-eight patients were classical EPS patients. Demographic data, PD details, and course of disease were documented. Peritoneal biopsies of all patients were investigated using histological criteria.

RESULTS

Eighteen patients from the Netherlands and thirty-eight patients from Germany were included. Time on PD was 78(64-95) in the PT-EPS and 72(50-89) months in the cEPS group (p>0.05). There were no significant differences between the morphological findings of cEPS and PT-EPS. Podoplanin positive cells were a prominent feature in both groups, but with a similar distribution of the podoplanin patterns. Time between cessation of PD to the clinical diagnosis of EPS was significantly shorter in the PT-EPS group as compared to cEPS (4(2-9) months versus 23(7-24) months, p<0.001). Peritonitis rate was significantly higher in cEPS.

CONCLUSIONS

In peritoneal biopsies PT-EPS and cEPS are not distinguishable by histomorphology and immunohistochemistry, which argues against different entities. The critical phase for PT-EPS is during the first year after transplantation and therefore earlier after PD cessation then in cEPS.

New insights into therapeutic strategies for the treatment of peritoneal fibrosis: learning from histochemical analyses of animal models

Encapsulating peritoneal sclerosis (EPS) is a fatal complication that can occur in patients undergoing long-term peritoneal dialysis. It is characterized by bowel obstruction and marked sclerotic thickening of the peritoneal membrane. Although the mechanisms underlying the development of EPS are complex, angiogenesis, inflammation, and peritoneal fibrosis are known to be essential factors. Now, several animal models that exhibit EPS have pathophysiology similar to that of human EPS and have been proposed for use in research to provide insights into it. Recent histochemical methods also help us to understand the pathophysiology of EPS. Advances in basic research based on the findings in those animal models have enabled the development of several strategies for the prevention and treatment of EPS. We describe here interventional studies in some animal models for peritoneal fibrosis, one of the histological disorders findings characteristic to EPS, and we highlight the need for a sophisticated animal model that closely resembles human conditions.

Can EPS development be avoided with early interventions? The potential role of tamoxifen--a single-center study

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Identification of patients at high risk for EPS ("EPS-prone") and delivery of appropriate interventions might prevent its development. Our aim was to evaluate the clinical characteristics and outcomes of all EPS and EPS-prone patients diagnosed at our PD unit.

METHODS

For a 30-year period representing our entire PD experience, we retrospectively identified all patients with EPS (diagnosed according to International Society for Peritoneal Dialysis criteria) and all patients defined as EPS-prone because they met at least 2 established criteria (severe peritonitis, PD vintage greater than 3 years, severe hemoperitoneum, overexposure to glucose, and acquired ultrafiltration failure).

RESULTS

Of 679 PD patients, we identified 20 with EPS, for an overall prevalence of 2.9%. Mean age at diagnosis was 50.2 ± 16.4 years, with a median PD time of 77.96 months (range: 44.36 - 102.7 months) and a median follow-up of 30.91 months (range: 4.6 - 68.75 months). Of patients with EPS, 10 (50%) received tamoxifen, 10 (50%) received parenteral nutrition, and 2 (10%) underwent adhesiolysis, with 25% mortality related to EPS. Another 14 patients were identified as EPS-prone. Median follow-up was 54.05 months (range: 11.9 - 87.04 months). All received tamoxifen, and 5 (36%) received corticosteroids; none progressed to full EPS. We observed no differences in baseline data between the groups, but the group with EPS had been on PD longer (84 ± 53 months vs 39 ± 20 months, p = 0.002) and had a higher cumulative number of days of peritoneal inflammation from peritonitis (17.2 ± 11.1 days vs 9.8 ± 7.9 days, p = 0.015). Overall mortality was similar in the groups. The incidence of EPS declined during our three decades of experience (5.6%, 3.9%, and 0.3%).

CONCLUSIONS

Being a serious, life-threatening complication of PD, EPS requires high suspicion to allow for prompt diagnosis and treatment. Early detection of EPS-prone states and delivery of appropriate intervention might prevent EPS development. Tamoxifen seems to be a key strategy in prevention, but caution should be used in interpreting our results. Additional randomized controlled studies are needed.

Dialysate cytokine levels do not predict encapsulating peritoneal sclerosis

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a rare but devastating complication of long-term peritoneal dialysis (PD). There is no well-validated method for predicting which patients will develop the condition, although known risk factors include long duration of PD, high glucose exposure and lack of residual renal function. We have investigated whether dialysate cytokines (MCP-1 (monocyte chemotactic protein-1), CCL18 (pulmonary and activation-regulated cytokine, PARC), IL-6 (interleukin-6), CCL15 (leukotactin) and angiogenin) could be used to predict the onset of EPS more effectively than known clinical risk factors.

METHODS

Samples of dialysate and clinical data were prospectively collected from 151 patients at the West London Renal center between 2003 and 2010. Dialysate cytokine levels were measured using the enzyme-linked immunoabsorbant assay (ELISA) technique. Encapsulating peritoneal sclerosis subsequently developed in 17 patients during a follow-up period of 27 - 113 months. Cytokines found at higher levels in dialysate of pre-EPS patients were investigated as candidate predictors of EPS using logistic regression analysis.

RESULTS

Dialysate IL-6, MCP-1 and CCL15 were significantly higher in patients who subsequently developed EPS; however, a logistic regression model using dialysate cytokines to predict EPS was no better than a model using well-recognized clinical markers (length of time on PD and membrane transport status).

CONCLUSIONS

Although MCP-1, IL-6 and CCL15 were found at higher levels in the dialysate of patients who subsequently developed EPS, dialysate levels of these cytokines do not improve prediction of future EPS above a model using known clinical risk factors.

Longitudinal study of small solute transport and peritoneal protein clearance in peritoneal dialysis patients

BACKGROUND AND OBJECTIVES

Peritoneal protein clearance (Pcl) is determined by both effective (small pores) membrane area and relative capillary leakiness (large pores). It is not known how these two components change with duration of peritoneal dialysis (PD) in the context of progressive membrane injury and differential attrition of patients with higher Pcl, which has been associated with increased mortality risk in several studies.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients treated continuously from 2000 to 2011 for a minimum of 4 years were selected from the longitudinal prospective Stoke PD Study. Pcl, membrane area (peritoneal solute transport rate [PSTR]), dialysis prescription, and residual renal function were measured every 6 months, along with comorbidity and peritonitis events. Multilevel multivariate analysis was used to determine associations with Pcl over time, taking into account within-subject correlations.

RESULTS

From 280 incident patients, 335 datasets were analyzed from 49 patients receiving treatment for 4 years. Pcl correlated with PSTR at baseline (R=0.61; P<0.01), but over time there was progressive uncoupling of this relationship (year 4, R=0.28; P=0.05) with increasing PSTR (0.66-0.74; P<0.01) and stable Pcl (78.4-81.9 ml/d; P=0.7). Multivariate analysis found that age, PSTR, daily ultrafiltration, and sodium removal were significant predictors of Pcl when adjusted for sex, comorbidity, glucose exposure, and residual renal function. Peritonitis was associated with increased PSTR but a similar pattern of uncoupling.

CONCLUSION

There is a progressive dissociation of the small- and large-pore pathways with time on PD, which would be in keeping with a switch from local inflammation early on to progressive fibrosis, combined with increased vascular surface area. Measuring longitudinal changes in Pcl may complement membrane function tests used to monitor progressive injury.

American Society of Nephrology quiz and questionnaire 2012: renal replacement therapy

Presentation of the Nephrology Quiz and Questionnaire has become an annual tradition at the meetings of the American Society of Nephrology. It is a very popular session judged by consistently large attendance. Members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. They can also compare their answers in real time, using audience response devices, with the answers of program directors of nephrology training programs in the United States acquired through an Internet-based questionnaire. Topics presented here include fluid and electrolyte disorders, glomerular diseases, transplantation, and ESRD and dialysis. Cases representing each of these categories along with single best answer questions were prepared by a panel of experts (Drs. Palmer, Fervenza, and Brennan and Mehrotra, respectively). The correct and incorrect answers then were briefly discussed after the audience responses, and the results of the questionnaire were displayed. This article tries to recapitulate the session and reproduce its educational value for a larger audience-the readers of the CJASN.

Persistent sterile peritoneal inflammation after catheter removal for refractory bacterial peritonitis predicts full-blown encapsulating peritoneal sclerosis

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is the most serious complication of peritoneal dialysis, having high morbidity and mortality. To improve outcomes, early diagnosis is needed to direct treatment during the early inflammatory phase. However, in the early inflammatory phase, clinical features are nonspecific, and no reliable diagnostic criteria have been established. Because bacterial peritonitis and termination of dialysis are two important risk factors triggering the progression of EPS, patients with refractory bacterial peritonitis necessitating dialysis catheter removal are at particularly high risk of developing EPS. Many of these patients might indeed experience non-resolving sterile peritonitis (probably the inflammatory phase of EPS) before progression to full-blown disease (that is, the presence of intestinal obstruction). We undertook a retrospective study to compare, in this particular situation, the clinical characteristics of patients with or without sterile peritoneal inflammation, assessing their clinical outcomes in terms of short-term mortality and the chance of developing full-blown EPS.

METHODS

Our retrospective review included 62 patients whose dialysis catheter was removed because of refractory peritonitis between January 2005 and December 2010.

RESULTS

Of the 62 patients identified, 39 (63%) had persistent sterile peritoneal inflammation ("high-risk" group, n = 39), and 23 (37%) had resolution of inflammation without significant intra-abdominal collection after catheter withdrawal ("control" group, n = 23). Compared with the control group, the high-risk group had a significantly longer PD duration (71.6 ± 43.3 months vs 42.3 ± 29.9 months, p = 0.003), a higher dialysate-to-plasma ratio (D/P) of creatinine (0.768 ± 0.141 vs 0.616 ± 0.091, p = 0.004), and a higher computed tomography score for EPS (7.69 ± 2.98 vs 1.00 ± 1.00, p < 0.001). During the 6-month study period, the high-risk group had a higher chance of developing full-blown EPS (31% vs 0%, p = 0.002) and a higher 6-month all-cause mortality (36% vs 4.3%, p = 0.004).

CONCLUSIONS

Persistent sterile peritoneal inflammation was common after dialysis catheter removal for refractory bacterial peritonitis, and the patients with such inflammation were at high risk of progression to full-blown EPS.

Dialysate cancer antigen 125 in long-term peritoneal dialysis patients

Structural and functional peritoneal membrane changes are associated with long-term peritoneal dialysis. These changes can lead to ultrafiltration failure and peritoneal fibrosis, reducing the efficacy of the peritoneal membrane to remove waste and balance fluid and electrolytes. The loss of mesothelial cells from the basement membrane is one of the major characteristics in peritoneal membrane structural change. Thus, if the reduction of peritoneal mesothelial cell mass in peritoneal dialysis patients is monitored, signs of ultrafiltration failure and peritoneal fibrosis can be detected early. One of biomarkers that can be used to indicate the change in peritoneal mesothelial cell mass is CA125, which is produced by mesothelial cells. In this article, we review the measurement and clinical use of CA125 in peritoneal dialysate effluent. Additionally, we address the data and studies on the association between dialysate CA125 levels and factors related to ultrafiltration failure and peritoneal fibrosis, including the parameters used to monitor the functional status of the peritoneal membrane. Our review shows that dialysate CA125 can be used to evaluate the peritoneal membrane in noninfected patients to predict peritoneal fibrosis, and it can also be used as a biomarker of biocompatible dialysis solutions.

Peritoneal changes in patients on long-term peritoneal dialysis

Long-term peritoneal dialysis can lead to morphological and functional changes in the peritoneum. Although the range of morphological alterations is known for the peritoneal dialysis population as a whole, these changes will not occur in every patient in the same sequence and to the same extent. Longitudinal studies are therefore required to help identify which patients might develop the changes. Although longitudinal studies using peritoneal biopsies are not possible, analyses of peritoneal effluent biomarkers that represent morphological alterations could provide insight. Longitudinal studies on peritoneal transport have been performed, but follow-up has often been too short and an insufficient number of parameters have been investigated. This Review will firstly describe peritoneal morphology and structure and will then focus on peritoneal effluent biomarkers and their changes over time. Net ultrafiltration will also be discussed together with the transport of small solutes. Data on the peritoneal transport of serum proteins show that serum protein levels do not increase to the same extent as levels of small solutes with long-term peritoneal dialysis. Early alterations in peritoneal transport must be distinguished from alterations that only develop with long-term peritoneal dialysis. Early alterations are related to vasoactive mediators, whereas later alterations are related to neoangiogenesis and fibrosis. Modern peritoneal dialysis should focus on the early detection of long-term membrane alterations by biomarkers--such as cancer antigen 125, interleukin-6 and plasminogen activator inhibitor 1--and the improved assessment of peritoneal transport.

Current status and practical use of effluent biomarkers in peritoneal dialysis patients

Long-term peritoneal dialysis therapy can lead to alterations in the function and morphology of the peritoneal membrane. Assessment of the peritoneal dialysis membrane usually is done by investigating the transport of small solutes and fluid. Assessment of morphologic alterations and their development would require repetitive peritoneal biopsies that usually are not feasible. Peritoneal tissues are bathed in dialysis solutions during peritoneal dialysis and may secrete or shed substances that can be recovered in peritoneal effluent. These molecular effluent biomarkers may give insight into morphologic changes. In this review, established and emerging candidate biomarkers in peritoneal dialysis are discussed. Additionally, requirements, challenges, and clinical applications of effluent biomarkers in peritoneal dialysis are addressed.

Lower mortality and inflammation from post-transplantation encapsulating peritoneal sclerosis compared to the classical form

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) may occur after kidney transplantation (post-transplantation EPS) or may be diagnosed during or after peritoneal dialysis treatment (classical EPS). The aim of the present study was to investigate to what extent both EPS entities differ in clinical presentation, radiological findings, outcome, and the systemic inflammatory response, as measured by plasma C-reactive protein (CRP) levels both prior to and after EPS diagnosis.

METHODS

We performed a retrospective analysis of 15 post-transplantation EPS and 19 classical EPS patients who were diagnosed at seven hospitals in the Netherlands between January 1, 2000, and January 1, 2011.

RESULTS

There were no inter-group differences in age, duration of peritoneal dialysis, clinical presentation, or radiology findings at diagnosis. Post-transplantation patients had experienced a lower number of peritonitis episodes per patient-year (0.2 (0.0-0.4) vs. 0.7 (0.3-1.2), p = 0.01) with a longer interval between the last peritonitis and EPS diagnosis (18.1 (4.6-34.3) vs. 4.4 (0.89-13.78) months, p = 0.01). Post-transplantation EPS patients showed a remarkably lower mortality rate (40.0 vs. 84.2%, p < 0.05). In both groups a pattern of elevated CRP values was observed, increasing within the year before EPS diagnosis. In the post-transplantation group the median CRP level at diagnosis was lower (56.0 vs. 144.50 mg/l, p < 0.05) than in the classical EPS group.

CONCLUSION

Post-transplantation EPS has a similar clinical presentation as classical EPS but with a lower systemic inflammatory response and better outcome.

Peritoneal adhesion: it can be life-threatening, and life-saving

Background

The inevitable post-inflammatory fibrosis and adhesion often compromises future treatment in peritoneal dialysis patients. Here, we describe a patient who experienced an unusual form of peritoneal adhesion that made her give up peritoneal dialysis. However, its unique pattern also saved her from infection caused by bowel perforation.

Case presentation

The female patient discontinued peritoneal dialysis due to gradual dialysis inadequacy. Two months after shifting to hemodialysis with generally improved sense of well-being and no sign of abdominal illness, she was admitted to remove the Tenckhoff catheter. The procedure was smooth, but fever and abdominal pain not at the site of operation developed the next day. Abdominal ultrasound showed the presence of ascites and aspiration revealed slimy, green-yellowish pus that gave a negative result on bacterial culture. Abdominal computed tomography (CT) with oral contrast medium was performed, but failed to demonstrate the suspected bowel perforation. The examination, however, did show accumulation of pus inside the abdomen but outside the peritoneal cavity. We drained the pus with two 14-F Pig-tail catheters and the total amount of drainage approached 4000 ml. The second CT was performed with double dose of the contrast medium and found a leak of the contrast from the jejunum. She then received laparotomy and had the perforation site closed.

Conclusions

In summary, this uremic patient suffered from pus accumulation inside her abdomen without obvious systemic toxic effect. The bowel perforation and pus formation might be caused by repeated peritonitis, but the peritoneal adhesion itself might also isolate her peritoneal cavity from the anticipated toxic injuries of bowel perforation.

Proof-of-principle study to detect metabolic changes in peritoneal dialysis effluent in patients who develop encapsulating peritoneal sclerosis

BACKGROUND

Prolonged peritoneal dialysis (PD) therapy can result in the development of encapsulating peritoneal sclerosis (EPS), characterized by extensive sclerosis of the peritoneum with bowel adhesions often causing obstruction.

METHODS

As a proof-of-principle study, holistic profiling of endogenous metabolites has been applied in a prospective collection of PD effluent collected in multiple UK renal centres over 6 years in order to investigate metabolic differences in PD effluent between PD therapy patients who later developed clinically defined EPS (n = 11) and controls, who were matched for PD vintage, age and gender (n = 11).

RESULTS

'Fit-for-purpose' analytical methods employing gas chromatography-mass spectrometry (MS), direct injection MS and quality control samples were developed and validated. These methods were applied in a proof-of-principle study to define metabolic differences in PD effluent related to subsequent development of EPS. Changes in amino acids, amines and derivatives, short-chain fatty acids and derivatives and sugars were observed prior to EPS developing, and changes in the metabolomic profiles could be detected.

CONCLUSION

There is potential for applying metabolic profiles to identify patients at risk of developing EPS although long-term prospective studies with larger patient cohorts are required.

Encapsulating peritoneal sclerosis: what have we learned?

Encapsulating peritoneal sclerosis (EPS) is a rare complication of peritoneal dialysis (PD), but carries significant morbidity and mortality. We review the clinical features and radiologic and histologic changes found at diagnosis of EPS. Although EPS is strongly associated with the duration of PD, the pathogenesis remains only partly understood. We discuss the mechanisms thought to underlie the abnormally thickened, sclerotic peritoneal membrane seen in long-term PD patients including epithelial to mesenchymal transition and the molecular mediators of fibrosis and angiogenesis. We review how exposure to high-glucose, nonphysiological dialysis fluids, peritonitis, and uremia may be responsible for these changes. Much remains to be learned about optimal management of EPS, both medical and surgical, because the literature lacks controlled studies. Future research challenges include defining the role of surgery, immunosuppression, and antifibrotic agents in the management of EPS. We also need to understand why some patients progress from asymptomatic peritoneal sclerosis to the extreme levels of fibrin deposition and bowel encapsulation seen in EPS. Screening PD patients for potential future EPS remains difficult, and we need strategies for monitoring patients on longer-term PD that enable us to better quantify the risk of EPS for the individual patient.