Role of endothelial hyaluronan in peritoneal membrane transport and disease conditions during peritoneal dialysis

Peritoneal membrane dysfunction in peritoneal dialysis (PD) is primarily attributed to angiogenesis; however, the integrity of vascular endothelial cells can affect peritoneal permeability. Hyaluronan, a component of the endothelial glycocalyx, is reportedly involved in preventing proteinuria in the normal glomerulus. One hypothesis suggests that development of encapsulating peritoneal sclerosis (EPS) is triggered by protein leakage due to vascular endothelial injury. We therefore investigated the effect of hyaluronan in the glycocalyx on peritoneal permeability and disease conditions. After hyaluronidase-mediated degradation of hyaluronan on the endothelial cells of mice, macromolecules, including albumin and β2 microglobulin, leaked into the dialysate. However, peritoneal transport of small solute molecules was not affected. Pathologically, hyaluronan expression was diminished; however, expression of vascular endothelial cadherin and heparan sulfate, a core protein of the glycocalyx, was preserved. Hyaluronan expression on endothelial cells was studied using 254 human peritoneal membrane samples. Hyaluronan expression decreased in patients undergoing long-term PD treatment and EPS patients treated with conventional solutions. Furthermore, the extent of hyaluronan loss correlated with the severity of vasculopathy. Hyaluronan on endothelial cells is involved in the peritoneal transport of macromolecules. Treatment strategies that preserve hyaluronan in the glycocalyx could prevent the leakage of macromolecules and subsequent related complications.

Renal hyperparathyroidism- a risk factor in the development of encapsulating peritoneal sclerosis

Background

Encapsulating peritoneal sclerosis (EPS) is a rare complication of prolonged peritoneal dialysis (PD) exposure, characterised by peritoneal thickening, calcification, and fibrosis ultimately presenting with life-threatening bowel obstruction. The presence or role of peritoneal calcification in the pathogenesis of EPS is poorly characterised. We hypothesise that significantly aberrant bone mineral metabolism in patients on PD can cause peritoneal calcification which may trigger the development of EPS. We compared the temporal evolution of bone mineral markers during PD in EPS patients with non-EPS long-term PD controls.

Methods

Linear mixed model and logistic regression analysis were used to compare four-monthly serum levels of calcium, phosphate, parathyroid hormone, and alkaline phosphatase (ALP) over the duration of PD exposure in 46 EPS and 46 controls (PD, non-EPS) patients.

Results

EPS patients had higher mean calcium (2.51 vs. 2.41 mmol/L) and ALP (248.00 vs. 111.13 IU/L) levels compared with controls (p=0.01 and p<0.001 respectively, maximum likelihood estimation). Logistic regression analysis demonstrated that high serum calcium and phosphate levels during PD were associated with a 4.5 and 2.9 fold increase in the risk of developing EPS respectively.

Conclusion

High levels of calcium and phosphate in patients on PD were identified to be risk factors for EPS development. Possible reasons for this may be an imbalance of pro-calcifying factors and calcification inhibitors promoting peritoneal calcification which increases peritoneal stiffness. Mechanical alterations may trigger, unregulated fibrosis and subsequent development of EPS. Improved management of secondary hyperparathyroidism during PD may ultimately diminish the EPS risk.

Encapsulating Peritoneal Sclerosis 43 Years after Distal Gastrectomy for Early Gastric Cancer

We herein report a case of encapsulating peritoneal sclerosis (EPS) in a patient without chronic kidney disease after gastrectomy. A 69-year-old man underwent distal gastrectomy for early gastric cancer at 25 years old. After 43 years, he developed bowel obstruction and underwent enterolysis of the encapsulated small intestine. A pathological examination of the capsular membranes revealed inflammation, foam, and giant cells that destroyed foreign substances. The patient was discharged 1.5 months later. Foreign body reactions to surgical instruments used in gastrectomy are considered a cause of EPS. EPS due to foreign body reactions to surgical instruments should also be considered in such cases.

Weekly intraperitoneal steroid infusion to treat recurrent ascites in a patient with early stage of peritoneal dialysis-related encapsulating peritoneal sclerosis: A case report

Encapsulating peritoneal sclerosis (EPS) is a rare and potentially fatal complication of long-term peritoneal dialysis (PD). EPS-induced large volume and recurrent ascites represents a challenging condition. We report a 51-year-old man with kidney failure treated with PD for 13 years who eventually developed early stage of EPS accompanied with poor intake and recurrent ascites. After management including discontinuing PD and switching to haemodialysis, as well as oral steroids and tamoxifen administration, the patient had refractory ascites. An intervention of weekly intraperitoneal steroid infusion with methylprednisolone was implemented for a year. Gradually, we observed a reduction in ascites drainage, an improvement of clinical symptoms and the patient's nutritional status. The PD catheter was successfully removed as there was no recurrence of ascites. Intraperitoneal corticosteroid administration represents a new intervention for patients with early stage of EPS and recurrent ascites after PD cessation.

Melatonin decreases GSDME mediated mesothelial cell pyroptosis and prevents peritoneal fibrosis and ultrafiltration failure

Peritoneal fibrosis together with increased capillaries is the primary cause of peritoneal dialysis failure. Mesothelial cell loss is an initiating event for peritoneal fibrosis. We find that the elevated glucose concentrations in peritoneal dialysate drive mesothelial cell pyroptosis in a manner dependent on caspase-3 and Gasdermin E, driving downstream inflammatory responses, including the activation of macrophages. Moreover, pyroptosis is associated with elevated vascular endothelial growth factor A and C, two key factors in vascular angiogenesis and lymphatic vessel formation. GSDME deficiency mice are protected from high glucose induced peritoneal fibrosis and ultrafiltration failure. Application of melatonin abrogates mesothelial cell pyroptosis through a MT1R-mediated action, and successfully reduces peritoneal fibrosis and angiogenesis in an animal model while preserving dialysis efficacy. Mechanistically, melatonin treatment maintains mitochondrial integrity in mesothelial cells, meanwhile activating mTOR signaling through an increase in the glycolysis product dihydroxyacetone phosphate. These effects together with quenching free radicals by melatonin help mesothelial cells maintain a relatively stable internal environment in the face of high-glucose stress. Thus, Melatonin treatment holds some promise in preserving mesothelium integrity and in decreasing angiogenesis to protect peritoneum function in patients undergoing peritoneal dialysis.

Melatonin inhibits the formation of chemically induced experimental encapsulating peritoneal sclerosis through modulation of T cell differentiation by suppressing of NF-κB activation in dendritic cells

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Surgery is a therapeutic strategy for the treatment of complete intestinal obstruction. However, complete intestinal obstruction in long-term PD results in high mortality and morbidity rates after surgery. Immunopathogenesis participates in EPS formation: CD8, Th1, and Th17 cell numbers increased during the formation of EPS. The anti-inflammatory and immunomodulatory effects of melatonin may have beneficial effects on this EPS. In the present study, we determined that melatonin treatment significantly decreases the Th1 and Th17 cell populations in mice with EPS, decreases the production of IL-1β, TNF-α, IL-6, and IFN-γ, and increases the production of IL-10. The suppression of Th1 and Th17 cell differentiation by melatonin occurs through the inhibition of dendritic cell (DC) activation by affecting the initiation of the NF-κB signaling pathway in DCs. Our study suggests that melatonin has preventive potential against the formation of EPS in patients with PD.

Prediction of surgical outcomes in severe encapsulating peritoneal sclerosis using a computed tomography scoring system

BACKGROUND/PURPOSE

Encapsulating peritoneal sclerosis (EPS) is a rare and potential lethal complication of peritoneal dialysis characterized by bowel obstruction. Surgical enterolysis is the only curative therapy. Currently, there are no tools for predicting postsurgical prognosis. This study aimed to identify a computed tomography (CT) scoring system that could predict mortality after surgery in patients with severe EPS.

METHODS

This retrospective study enrolled patients with severe EPS who underwent surgical enterolysis in a tertiary referral medical center. The association of CT score with surgical outcomes including mortality, blood loss, and bowel perforation was analyzed.

RESULTS

Thirty-four patients who underwent 37 procedures were recruited and divided into a survivor and non-survivor group. The survivor group had higher body mass indices (BMIs, 18.1 vs. 16.7 kg/m2, p = 0.035) and lower CT scores (11 vs. 17, p < 0.001) than the non-survivor group. The receiver operating characteristic curve revealed that a CT score of ≥15 could be considered a cutoff point to predict surgical mortality, with an area under the curve of 0.93, sensitivity of 88.9%, and specificity of 82.1%. Compared with the group with CT scores of <15, the group with CT scores of ≥15 had a lower BMI (19.7 vs. 16.2 kg/m2, p = 0.004), higher mortality (4.2% vs. 61.5%, p < 0.001), greater blood loss (50 vs. 400 mL, p = 0.007), and higher incidence of bowel perforation (12.5% vs. 61.5%, p = 0.006).

CONCLUSION

The CT scoring system could be useful in predicting surgical risk in patients with severe EPS receiving enterolysis.

Encapsulating Peritoneal Sclerosis in a Patient Receiving Peritoneal Dialysis and Glucocorticoid Therapy

Encapsulating peritoneal sclerosis (EPS) is a fatal complication of peritoneal dialysis. A 68-year-old man undergoing peritoneal dialysis for 10 years started receiving daily 50 mg of glucocorticoids for idiopathic pulmonary sclerosis. At the transition to hemodialysis, a peritoneal biopsy was performed, which demonstrated mild histological changes, including no fibrin formation and mild T lymphocyte infiltration at the time of 6.5 mg glucocorticoids. However, five months later, he developed EPS when receiving 2.5 mg glucocorticoids. Afterward, over 5 mg daily glucocorticoids were required to avoid the recurrence of EPS. These findings suggest that glucocorticoids may conceal peritoneal inflammation, a main contributor to EPS.

Advances in stem cell therapy for peritoneal fibrosis: from mechanisms to therapeutics

Peritoneal fibrosis (PF) is a pathophysiological condition caused by a variety of pathogenic factors. The most important features of PF are mesothelial-mesenchymal transition and accumulation of activated (myo-)fibroblasts, which hinder effective treatment; thus, it is critical to identify other practical approaches. Recently, stem cell (SC) therapy has been indicated to be a potential strategy for this disease. Increasing evidence suggests that many kinds of SCs alleviate PF mainly by differentiating into mesothelial cells; secreting cytokines and extracellular vesicles; or modulating immune cells, particularly macrophages. However, there are relatively few articles summarizing research in this direction. In this review, we summarize the risk factors for PF and discuss the therapeutic roles of SCs from different sources. In addition, we outline effective approaches and potential mechanisms of SC therapy for PF. We hope that our review of articles in this area will provide further inspiration for research on the use of SCs in PF treatment.

Silymarin ameliorates peritoneal fibrosis by inhibiting the TGF-β/Smad signaling pathway

Peritoneal dialysis (PD) is the mainstay of treatment for renal failure replacement therapy. Although PD has greatly improved the quality of life of end-stage renal disease (ESRD) patients, long-term PD can lead to ultrafiltration failure, which in turn causes peritoneal fibrosis (PF). Silymarin (SM) is a polyphenolic flavonoid isolated from the milk thistle (Silybum marianum) species that has a variety of pharmacological actions, including antioxidant, anti-inflammatory, antiviral, and anti-fibrotic pharmacological activities. However, the effect of SM on PF and its potential mechanisms have not been clarified. The aim of this study was to investigate the preventive effect of SM on PF in vitro and in vivo as well as elucidate the underlying mechanisms. We established PF mouse models and human pleural mesothelial cell fibrosis in vitro by intraperitoneal injection of high-glucose peritoneal dialysis solution (PDS) or transforming growth factor-β1 (TGF-β1), and evaluated the effect of SM on peritoneal fibrosis in vivo and in vitro. We found that SM alleviated peritoneal dysfunction. Meanwhile, SM inhibited the expression of fibrotic markers (TGF-β1, collagen I, fibronectin) and restored the expression of E-cadherin, BMP-7 in PF mice and TGF-β1-treated Met-5A cells. Furthermore, SM markedly down-regulated the expression of TGF-β1, p-Smad2, and p-Smad3 and up-regulated the expression of smad7. In conclusion, these findings suggested that SM may be an efficient and novel therapy for the prevention of PF through inhibition of TGF-β/Smad signaling.

Magnesium inhibits peritoneal calcification as a late-stage characteristic of encapsulating peritoneal sclerosis

Peritoneal calcification is a prominent feature of the later stage of encapsulating peritoneal sclerosis (EPS) in patients undergoing long-term peritoneal dialysis (PD). However, the pathogenesis and preventive strategy for peritoneal calcification remain unclear. Peritoneum samples from EPS patients were examined histologically. Peritoneal calcification was induced in mice by feeding with an adenine-containing diet combined with intraperitoneal administration of lipopolysaccharide and a calcifying solution containing high calcium and phosphate. Excised mouse peritoneum, human mesothelial cells (MeT5A), and mouse embryonic fibroblasts (MEFs) were cultured in calcifying medium. Immunohistochemistry confirmed the appearance of osteoblastic differentiation-marker-positive cells in the visceral peritoneum from EPS patients. Intraperitoneal administration of magnesium suppressed peritoneal fibrosis and calcification in mice. Calcifying medium increased the calcification of cultured mouse peritoneum, which was prevented by magnesium. Calcification of the extracellular matrix was accelerated in Met5A cells and MEFs treated with calcification medium. Calcifying medium also upregulated osteoblastic differentiation markers in MeT5A cells and induced apoptosis in MEFs. Conversely, magnesium supplementation mitigated extracellular matrix calcification and phenotypic transdifferentiation and apoptosis caused by calcifying conditions in cultured MeT5A cells and MEFs. Phosphate loading contributes to the progression of EPS through peritoneal calcification and fibrosis, which can be prevented by magnesium supplementation.

N-methylpiperazine-diepoxyovatodiolide ameliorates peritoneal fibrosis via suppressing TGF-β/Smad and JAK/STAT signaling pathway

Peritoneal fibrosis (PF) is the main cause of peritoneal ultrafiltration failure in patients undergoing long-term peritoneal dialysis (PD). Epithelial-mesenchymal transition (EMT) is the key pathogenesis of PF. However, currently, no specific treatments are available to suppress PF. N-methylpiperazine-diepoxyovatodiolide (NMPDOva) is a newly synthesized compound that involves a chemical modification of ovatodiolide. In this study, we aimed to explore the antifibrotic effects of NMPDOva in PD-related PF and underlying mechanisms. A mouse model of PD-related PF was established via daily intraperitoneal injection of 4.25% glucose PD fluid. In vitro studies were performed using the transforming growth factor-beta1 (TGF-β1)-stimulated HMrSV5 cell line. Pathological changes were observed, and fibrotic markers were significantly elevated in the peritoneal membrane in mice model of PD-related PF. However, NMPDOva treatment significantly alleviated PD-related PF by decreasing the extracellular matrix accumulation. NMPDOva treatment decreased the expression of fibronectin, collagen Ⅰ, and alpha-smooth muscle actin (α-SMA) in mice with PD-related PF. Moreover, NMPDOva could alleviate TGF-β1-induced EMT in HMrSV5 cells, inhibited phosphorylation and nuclear translocation of Smad2/3, and increased the expression of Smad7. Meanwhile, NMPDOva inhibited phosphorylation of JAK2 and STAT3. Collectively, these results indicated that NMPDOva prevents PD-related PF by inhibiting the TGF-β1/Smad and JAK/STAT signaling pathway. Therefore, because of these antifibrotic effects, NMPDOva may be a promising therapeutic agent for PD-related PF.

Pathophysiology of encapsulating peritoneal sclerosis: lessons from findings of the past three decades in Japan

Encapsulating peritoneal sclerosis (EPS), a condition with a high mortality rate, is a serious complication of peritoneal dialysis (PD). In Japan, EPS became a central issue in the clinical setting during the mid-90s and the beginning of this century. However, following the introduction of biocompatible neutral PD solutions containing lower levels of glucose degradation products, the incidence and clinical severity of EPS has been greatly lessened. During the past three decades, the etiology of EPS has been elucidated by findings obtained by peritoneal biopsy, laparoscopy, and surgical intervention. Accumulating findings suggest the need for a paradigm change on the nature of EPS pathophysiology; notably, EPS appears not to reflect peritoneal sclerosis per se, but rather the formation of a neo-membrane as a biological reaction to peritoneal injury. This narrative review looks back on the history of EPS in Japan, and discusses EPS pathophysiology, the impact of neutral PD solution on peritoneal protection, and a future novel diagnostic approach, ultra-fine endoscope, for the identification of patients at high risk of EPS.

A case report of encapsulating peritoneal sclerosis followed by cesarean section: Clinical diagnosis and treatment experience

RATIONALE

Encapsulating peritoneal sclerosis (EPS), also known as abdominal cocoon syndrome, is an uncommon condition that typically presents with features of bowel obstruction. EPS followed by cesarean section is extremely rare. Intestinal obstruction caused by EPS lacks specificity and poses clinical difficulties for diagnosis and treatment. We present the case of a patient with recurrent intestinal obstruction followed by cesarean section, and the diagnosis of EPS was confirmed intraoperatively. The patient recovered well postoperatively, and achieved satisfactory therapeutic results. Management of this condition tests the surgeon's knowledge and experience of the disease.

PATIENT CONCERNS

A 27-year-old woman with recurrent abdominal pain and distention accompanied by reduced anal discharge and defecation there months. The patient had a history of cesarean section 4 months earlier and recovered well after operation. She had no other history of abdominal surgery or diseases. On examination, a 10-cm long transverse incision was made in the lower abdomen, and marking on the intestinal movements were observed in the left mid-abdomen. A long, soft lump with good mobility was touched in the left lower abdomen. The abdominal computed tomography and small bowel barium meal examination revealed incomplete intestinal obstruction.

DIAGNOSIS

Incomplete small bowel obstruction due to abdominal adhesions after the cesarean section was initially considered.

INTERVENTIONS

After conservative treatment, the symptom of intestinal obstruction still recurred. Thus, we decided to perform a surgery of repeated decortication of fibrous peritoneal membranes.

OUTCOMES

The operation successfully released the intestinal obstruction and abdominal pain, postoperative course recovered smoothly.

LESSONS

After cesarean section could develop EPS. Intestinal obstruction caused by EPS lacks specificity and poses clinical difficulty in diagnosis and treatment. The management of this condition tests the surgeon's knowledge and experience, and surgery is an effective treatment measure.

Risk factors for Encapsulating Peritoneal Sclerosis in patients undergoing peritoneal dialysis: A meta-analysis

Purpose

Encapsulating Peritoneal Sclerosis (EPS) is the most serious complication of long-term peritoneal dialysis (PD), which considerably reduces the patient’s quality of life, leading to patients discontinuing PD. Considering these negative effects, it is necessary to systematically review and determine the risk factors of EPS.

Methods

The PubMed, Embase, Web of Science, Cochrane Library, and China Biology Medicine (CBM) were searched from their inception to January 1st, 2022, and the bibliographies from the citations of relevant articles were manually searched. The ROBINS-I (Risk of Bias in Non-randomized studies of Interventions) tool was used to evaluate the risk of bias of included studies.

Results

Ten studies involving 12595 participants were included in this meta-analysis. The results revealed that a younger age at PD onset (MD = -7.70, 95% CI, -11.53~-3.86), a higher transporter (MD = 0.13, 95% CI, 0.09~0.18), a longer PD duration (SMD = 1.15, 95% CI, 0.68~1.61), a longer peritonitis duration (MD = 12.66, 95% CI, 3.85~21.47), and history of glomerulonephritis (OR = 1.42, 95% CI, 1.02~1.97) were significant risk factors for EPS. However, sex, use of icodextrin, the number of peritonitis episodes, and history of multicystic kidney disease did not affect the risk of EPS.

Conclusions

This review provides a scientific basis for further understanding the etiology of PD-related EPS and improving prevention strategies. More high-quality studies are necessary to validate this paper’s findings.

Human Amnion-Derived Mesenchymal Stromal Cells: A New Potential Treatment for Carbapenem-Resistant Enterobacterales in Decompensated Cirrhosis

BACKGROUND

Spontaneous bacterial peritonitis (SBP) is a severe and often fatal infection in patients with decompensated cirrhosis and ascites. The only cure for SBP is antibiotic therapy, but the emerging problem of bacterial resistance requires novel therapeutic strategies. Human amniotic mesenchymal stromal cells (hA-MSCs) possess immunomodulatory and anti-inflammatory properties that can be harnessed as a therapy in such a context.

METHODS

An in vitro applications of hA-MSCs in ascitic fluid (AF) of cirrhotic patients, subsequently infected with carbapenem-resistant Enterobacterales, was performed. We evaluated the effects of hA-MSCs on bacterial load, innate immunity factors, and macrophage phenotypic expression.

RESULTS

hA-MSCs added to AF significantly reduce the proliferation of both bacterial strains at 24 h and diversely affect M1 and M2 polarization, C3a complement protein, and ficolin 3 concentrations during the course of infection, in a bacterial strain-dependent fashion.

CONCLUSION

This study shows the potential usefulness of hA-MSC in treating ascites infected with carbapenem-resistant bacteria and lays the foundation to further investigate antibacterial and anti-inflammatory roles of hA-MSC in in vivo models.

Liver cirrhosis with encapsulating peritoneal sclerosis after 4 years of peritoneal dialysis: A case report

RATIONALE

Encapsulating peritoneal sclerosis (EPS), or abdominal cocoon, is a rare but fatal syndrome characterized by intestinal obstruction owing to adhesions in a diffusely thickened peritoneum. Long-term peritoneal dialysis (PD) for more than 5 years is commonly associated with EPS, while liver cirrhosis also carries a risk of EPS. However, there have been only a few reports that describe a case of EPS complicated with both cirrhosis and PD. We herein describe a case of advanced liver cirrhosis with end-stage renal disease (ESRD) who developed EPS after 4 years of PD and who was successfully recovered by surgery.

PATIENT CONCERNS

A 58-year-old man with alcoholic liver cirrhosis suffered abdominal pain. The patient had a 4-year history of continuous cycling PD to manage ESRD as well as cirrhotic complications of refractory ascites and hypotension. Laboratory test results showed increased levels of inflammation, and contrast-enhanced computed tomography scan showed dilated loops of small bowel proximal to the site of intestinal obstruction. The patient was suspected to have developed intestinal obstruction owing to EPS. The patient discontinued continuous cycling peritoneal dialysis and switched to hemodiafiltration.

DIAGNOSES

Laparoscopy revealed a whitish membranous material wrapped around the bowel, especially at the terminal ileum with a narrowed portion, consistent with EPS.

INTERVENTIONS

Repeated decortication of fibrous peritoneal membranes successfully released the intestinal obstruction.

OUTCOMES

The postoperative course went well and abdominal pain remained in remission. Because abdominal distension owing to ascites got intolerable in a few days after surgery, a PD catheter was re-inserted and ascitic fluid drainage was resumed with peritoneal lavage. The patient continued hemodiafiltration using vasopressor agents.

LESSONS

The Cirrhotic patient with ESRD undergoing PD could develop EPS after a short duration of PD.

Abdominal cocoon in children: A case report and review of literature

BACKGROUND

Abdominal cocoon or “encapsulating peritoneal sclerosis” (EPS) is an uncommon and rare cause of intestinal obstruction. Only a few cases have been reported in paediatric patients. Typically, EPS is described as the primary form in young adolescent girls from tropical and subtropical countries because of viral peritonitis due to retrograde menstruation or a history of peritoneal dialysis. Most patients are asymptomatic or present with abdominal pain, which is likely to occur secondary to subacute bowel obstruction. Findings at imaging, such as ultrasound, computed tomography, and magnetic resonance imaging, are often nonspecific. When diagnosed, EPS is characterized by total or partial encasement of the bowel within a thick fibrocollagenous membrane that envelopes the small intestine in the form of a cocoon because of chronic intraabdominal fibroinflammatory processes. The membrane forms a fibrous tissue sheet that covers, fixes, and finely constricts the gut, compromising its motility.

CASE SUMMARY

We present a case of EPS in a 12-year-old boy 8 wk after primary surgery for resection of symptomatic jejunal angiodysplasia. There was no history of peritoneal dialysis or drug intake.

CONCLUSION

In this report, we sought to highlight the diagnostic, surgical, and histopathological characteristics and review the current literature on EPS in paediatric patients.

Mechanisms of Peritoneal Fibrosis: Focus on Immune Cells-Peritoneal Stroma Interactions

Peritoneal fibrosis is characterized by abnormal production of extracellular matrix proteins leading to progressive thickening of the submesothelial compact zone of the peritoneal membrane. This process may be caused by a number of insults including pathological conditions linked to clinical practice, such as peritoneal dialysis, abdominal surgery, hemoperitoneum, and infectious peritonitis. All these events may cause acute/chronic inflammation and injury to the peritoneal membrane, which undergoes progressive fibrosis, angiogenesis, and vasculopathy. Among the cellular processes implicated in these peritoneal alterations is the generation of myofibroblasts from mesothelial cells and other cellular sources that are central in the induction of fibrosis and in the subsequent functional deterioration of the peritoneal membrane. Myofibroblast generation and activity is actually integrated in a complex network of extracellular signals generated by the various cellular types, including leukocytes, stably residing or recirculating along the peritoneal membrane. Here, the main extracellular factors and the cellular players are described with emphasis on the cross-talk between immune system and cells of the peritoneal stroma. The understanding of cellular and molecular mechanisms underlying fibrosis of the peritoneal membrane has both a basic and a translational relevance, since it may be useful for setup of therapies aimed at counteracting the deterioration as well as restoring the homeostasis of the peritoneal membrane.

Novel Application of Magnetite Nanoparticle-Mediated Vitamin D3 Delivery for Peritoneal Dialysis-Related Peritoneal Damage

PURPOSE

Vitamin D3 is useful for the treatment of peritoneal dialysis (PD)-related peritoneal damage, but its side effects, such as hypercalcemia and vascular calcification, limit its applicability. Thus, we developed vitamin D-loaded magnetic nanoparticles (MNPs) and determined their therapeutic efficacy and side effects in vivo.

MATERIALS AND METHODS

Alginate-modified MNPs were combined with 1α, 25 (OH)2D3 to generate vitamin D-loaded nanoparticles. The particles were conjugated with an antibody against peritoneum-glycoprotein M6A (GPM6A). The particles' ability to target the peritoneum was examined following intraperitoneal administration to mice and by monitoring their bio-distribution. We also established a PD animal model to determine the therapeutic and side effects of vitamin D-loaded MNPs in vivo.

RESULTS

Vitamin D-loaded MNPs targeted the peritoneum better than vitamin D3, and had the same therapeutic effect as vitamin D3 in ameliorating peritoneal fibrosis and functional deterioration in a PD animal model. Most importantly, the particles reduced the side effects of vitamin D3, such as hypercalcemia and body weight loss, in mice.

CONCLUSION

Vitamin D-loaded MNPs could be an ideal future therapeutic option to treat PD-related peritoneal damage.

Single-cell transcriptomics provides new insights into the role of fibroblasts during peritoneal fibrosis

BACKGROUND

The contributions of various types of cell populations in dialysis-related peritoneal fibrosis are poorly understood. Single-cell RNA sequencing brings single-cell level resolution to the analysis of cellular transcriptomics, which provides a new way to further characterize the distinct roles and functional states of each cell population during peritoneal fibrosis.

METHODS

Single-cell transcriptomics from normal peritoneal tissues of six patients, from effluent of patients with short-term peritoneal dialysis (less than 2 weeks, n = 6), and from long-term peritoneal dialysis patients (more than 6 years, n = 4) were analyzed.

RESULTS

We identified a distinct cell component between samples among different groups. Functional analysis of the differentially expressed genes identified cell type specific biological processes relevant to different fibrosis stages. Well-known key molecular mechanisms participating in the pathophysiology of peritoneal fibrosis were vitrified, and some of them were found to be restricted to specific cell types. Gradually growing enrichment of PI3K/AKT/mTOR pathway and impairment of oxidative phosphorylation in mesothelial cells and fibroblasts were found from healthy control, short-term dialysis, to long-term dialysis, respectively. The fibroblasts' population obtained from the patients, who received peritoneal dialysis, showed a functional characteristic of immune-chemotaxis and immune response, which was characterized by broadly significant increase in the expression of interleukins, chemokines, cytokines, and human leukocyte antigens. Furthermore, we described the intercellular crosstalk networks based on receptor-ligand interactions, and highlighted a central role of fibroblasts in regulating the key mechanisms of peritoneal fibrosis through crosstalk with other cells.

CONCLUSIONS

In summary, despite describing information for fibrogenic molecular mechanisms in the resolution level of individual cell populations, this work identifies the significant functional evolution of fibroblasts during peritoneal fibrosis. This study also reveals the intercellular receptor-ligand interactions in which the fibroblasts serve as a major node, eventually providing new insights into the role of fibroblasts during disease pathogenesis.

The calcium concentration of peritoneal dialysis solution modifies levels of key mediators of peritoneal fibrosis

BACKGROUND

To explore the effects of different calcium concentrations of peritoneal dialysis solution (PDS) on continuous ambulatory peritoneal dialysis (CAPD) and expression of vimentin (VIM), fibroblast-specific protein (FSP1), and E-cadherin.

MATERIALS AND METHODS

This was a pilot study (#ChiCTR1900021387) conducted from January 2017 to December 2019 at the Hospital. The patients were randomized to undergo CAPD using PDS with a calcium concentration of 1.25 mmol/L (low concentration group) or 1.75 mmol/L (high concentration group). Changes in biochemistry before dialysis and at 6 and 12 months were analyzed.

RESULTS

There were 50 and 52 participants in the low and high calcium groups. The blood biochemical indexes were all different between the two groups (all Ptime  < .05, Pgroup  < .05, Pinteraction  < .05), but they remained within their normal ranges. VIM and FSP1 increased over 12 months (Ptime  < .05); VIM and FSP1 levels in the high concentration group were higher than in the low concentration group (Pgroup  < .05, Pinteraction  < .05), while E-cadherin showed the inverse association (Ptime  < .001, Pgroup  < .001, Pinteraction  < .001). There was no difference in complications (P = .973).

CONCLUSION

The calcium concentration in PDS might be an important factor affecting the progression of peritoneal fibrosis.

Molecular pathways in peritoneal fibrosis

Peritoneal dialysis (PD) is a renal replacement therapy for patients with end-stage renal disease that is equivalent to hemodialysis with respect to adequacy, mortality, and other outcome parameters, yet providing superior quality-of-life measures and cost savings. However, long-term usage of the patient's peritoneal membrane as a dialyzer filter is unphysiological and leads to peritoneal fibrosis, which is a major factor of patient morbidity and PD technique failure, resulting in a transfer to hemodialysis or death. Peritoneal fibrosis pathophysiology involves chronic inflammation and the fibrotic process itself. Frequently, inflammation precedes membrane fibrosis development, although a bidirectional relationship of one inducing the other exists. This review aims at highlighting the histopathological definition of peritoneal fibrosis, outlining the interplay of fibrosis, angiogenesis and epithelial-to-mesenchymal transition (EMT), delineating important fibrogenic pathways involving Smad-dependent and Smad-independent transforming growth factor-β (TGF-β) as well as connective tissue growth factor (CTGF) signaling, and summarizing historic and recent studies of inflammatory pathways involving NOD-like receptor protein 3 (NLRP3)/interleukin (IL)-1β, IL-6, IL-17, and other cytokines.

Encapsulating Peritoneal Sclerosis: Pathophysiology and Current Treatment Options

Encapsulating peritoneal sclerosis (EPS) is a life-threatening complication of long-term peritoneal dialysis (PD), which may even occur after patients have switched to hemodialysis (HD) or undergone kidney transplantation. The incidence of EPS varies across the globe and increases with PD vintage. Causative factors are the chronic exposure to bioincompatible PD solutions, which cause long-term modifications of the peritoneum, a high peritoneal transporter status involving high glucose concentrations, peritonitis episodes, and smoldering peritoneal inflammation. Additional potential causes are predisposing genetic factors and some medications. Clinical symptoms comprise signs of intestinal obstruction and a high peritoneal transporter status with incipient ultrafiltration failure. In radiological, macro-, and microscopic studies, a massively fibrotic and calcified peritoneum enclosed the intestine and parietal wall in such cases. Empirical treatments commonly used are corticosteroids and tamoxifen, which has fibrinolytic properties. Immunosuppressants like azathioprine, mycophenolate mofetil, or mTOR inhibitors may also help with reducing inflammation, fibrin deposition, and collagen synthesis and maturation. In animal studies, N-acetylcysteine, colchicine, rosiglitazone, thalidomide, and renin-angiotensin system (RAS) inhibitors yielded promising results. Surgical treatment has mainly been performed in severe cases of intestinal obstruction, with varying results. Mortality rates are still 25–55% in adults and about 14% in children. To reduce the incidence of EPS and improve the outcome of this devastating complication of chronic PD, vigorous consideration of the risk factors, early diagnosis, and timely discontinuation of PD and therapeutic interventions are mandatory, even though these are merely based on empirical evidence.

Encapsulating peritoneal sclerosis in a patient after allogeneic hematopoietic stem cell transplantation: a case report

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a chronic clinical syndrome of acute or subacute gastrointestinal obstruction seen mainly in patients undergoing peritoneal dialysis. Although there are a few reports on EPS developing in non-peritoneal dialysis patients, it has not been reported in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT). Here, we report a case of EPS after a second HSCT.

CASE PRESENTATION

A 46-year-old man with myelodysplastic syndrome showed relapse after HSCT and received a second HSCT. The patient was diagnosed with chronic graft-versus-host disease (cGVHD)-associated serositis because of persistent ascites. His ascites improved gradually and disappeared without immunosuppressive therapy. He presented with nausea, weight loss, and constipation 1 year after improvement of ascites. Computed tomography revealed no organic obstruction, but did reveal dilated, thickened, and adhered small bowel loops with a mass-like appearance. He was diagnosed with EPS on the basis of clinical symptoms and image findings. He received corticosteroid therapy (20 mg/body) without any improvement in symptoms. He developed recurrence of myelodysplastic syndrome at 1 month after initiation of corticosteroid therapy. This progressed into acute myeloid leukaemia after 3 months. He died 31 months after the second HSCT. At autopsy, the small and large intestines had formed extensive adhesions and showed signs of progressive fibrosis with peritoneal sclerosis, fibroblast swelling, fibrin deposition, and inflammatory cell infiltration, which confirmed the diagnosis of EPS.

CONCLUSION

This case suggests that EPS may complicate patients with cGVHD-associated serositis. Although the mechanism of EPS development is not clear, clinicians should be aware of this eventuality.

Mammalian Target of Rapamycin Complex 1 Activation Disrupts the Low-Density Lipoprotein Receptor Pathway: A Novel Mechanism for Extracellular Matrix Accumulation in Human Peritoneal Mesothelial Cells

Peritoneal fibrosis (PF) is characterized by progressive extracellular matrix (ECM) accumulation. Increasing evidence has suggested that ECM synthesis was increased in human peritoneal mesothelial cells (HPMCs) under high-glucose conditions, but the effects of high-glucose peritoneal dialysis solution (PDS) on ECM synthesis have not been fully elucidated. The aim of this study was to explore the potential mechanisms of high-glucose PDS-induced production of ECM in HPMCs. HPMCs were stimulated by high-glucose PDS. The activity of mammalian target of rapamycin complex 1 (mTORC1) was inhibited by rapamycin or regulatory-associated protein of mTOR (raptor) siRNA. Morphological changes in the cells were observed under an inverted microscope. Oil red O, filipin staining and high-performance liquid chromatography were used to examine lipid accumulation. The expression of low-density lipoprotein receptor (LDLr) regulation, the mTORC1 pathway and ECM-associated markers were assessed by real-time polymerase chain reaction and western blot analysis. The results showed that after treatment with PDS, HPMCs showed notable elongation consistent with the morphology of myofibroblasts, and the expression of ECM proteins such as α-smooth muscle actin, fibroblast specific protein-1 and collagen I was increased. In addition, there was a parallel increase in the ECM and lipid accumulation. Moreover, the effect of intracellular lipid deposition was closely correlated with the dysregulation of LDLr, which was mediated through the upregulation of LDLr, sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), and SREBP-2 and through the enhanced coexpression of the SCAP with the Golgin. Further analysis showed that PDS enhanced the protein phosphorylation of mTOR, eukaryotic initiation factor 4E-binding protein 1, and p70 S6 kinase. Interestingly, blocking mTORC1 activity reversed the dysregulation of LDLr, even in the presence of PDS. These effects were also accompanied by a decrease in the expression of ECM components. Our findings demonstrated that increased mTORC1 activity exacerbated ECM formation in HPMCs by disrupting LDLr regulation, which contributed to lipid disorder-mediated PF.

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.

Inhibition of the H3K4 methyltransferase SET7/9 ameliorates peritoneal fibrosis

Transforming growth factor-β1 (TGF-β1) is a major mediator of peritoneal fibrosis and reportedly affects expression of the H3K4 methyltransferase, SET7/9. SET7/9-induced H3K4 mono-methylation (H3K4me1) critically activates transcription of fibrosis-related genes. In this study, we examined the effect of SET7/9 inhibition on peritoneal fibrosis in mice and in human peritoneal mesothelial cells (HPMCs). We also examined SET7/9 expression in nonadherent cells isolated from the effluent of peritoneal dialysis (PD) patients. Murine peritoneal fibrosis was induced by intraperitoneal injection of methylglyoxal (MGO) into male C57/BL6 mice over 21 days. Sinefungin, a SET7/9 inhibitor, was administered subcutaneously just before MGO injection (10 mg/kg). SET7/9 expression was elevated in both MGO-injected mice and nonadherent cells isolated from the effluent of PD patients. SET7/9 expression was positively correlated with dialysate/plasma ratio of creatinine in PD patients. Sinefungin was shown immunohistochemically to suppress expression of mesenchymal cells and collagen deposition, accompanied by decreased H3K4me1 levels. Peritoneal equilibration tests showed that sinefungin attenuated the urea nitrogen transport rate from plasma and the glucose absorption rate from the dialysate. In vitro, sinefungin suppressed TGF-β1-induced expression of fibrotic markers and inhibited H3K4me1. These findings suggest that inhibiting the H3K4 methyltransferase SET7/9 ameliorates peritoneal fibrosis.

Peritoneal Membrane Preservation

Peritoneal dialysis (PD) is a successfully used method for renal replacement therapy. However, long-term PD may be associated with peritoneal fibrosis and ultrafiltration failure. The key factors linked to their appearance are repeated episodes of inflammation associated with peritonitis and long-term exposure to bioincompatible PD fluids. Different strategies have been proposed to preserve the peritoneal membrane. This article reviews the functional and structural alterations related to PD and strategies whereby we may prevent them to preserve the peritoneal membrane. The use of new, more biocompatible, PD solutions is promising, although further morphologic studies in patients using these solutions are needed. Blockade of the renin-angiotensin-aldosterone system appears to be efficacious and strongly should be considered. Other agents have been proven in experimental studies, but most of them have not yet been tested appropriately in human beings.

The truth on current peritoneal dialysis: state of the art

The share of peritoneal dialysis (PD) in the spectrum of chronic dialysis has decreased markedly in the Netherlands in the last 15 years. Consequently, the knowledge of nephrologists and nursing staff on PD has declined leading to a negative spiral in which loss of experience resulted in loss of enthusiasm to offer PD to patients and also in less interest in the new PD developments. All these changes took place while the results of PD improved and patient survival was at least similar to that on haemodialysis. The aim of this review is first to give a summary of the principles and practice of patient and staff education and to describe the role of the medical contribution in decision-making. On this basis, the second aim is to update internist-nephrologists on a number of issues that have been underexposed in the past. Recent patient and technique survival data of PD patients is reviewed, and also the new insights into dialysis adequacy. The presence of residual renal function is the main determinant of patient survival together with prevention of overhydration. Urea and creatinine removal are not important at all when patients are still passing urine. Many early problems with PD are due to the peritoneal catheter and suggestions are made for improvement of its function. The prevention and management of infections is reviewed, and also the regular assessment of peritoneal function. Free water transport is a predictor of encapsulating peritoneal sclerosis (EPS), which should be assessed regularly. The pathogenesis of EPS, treatment and the decreasing incidence are discussed.

A Case of Encapsulating Peritoneal Sclerosis Complicated by Malignant Peritoneal Mesothelioma

We report a case of peritoneal mesothelioma discovered in a patient during peritoneal dialysis. The patient was a 55-year-old woman who had no history of asbestos exposure. Owing to end-stage kidney failure, she had been undergoing peritoneal dialysis for over 8 years, and she had been diagnosed with encapsulating peritoneal sclerosis. She was admitted to the hospital for intestinal obstruction. Three months later, she noticed an enlarging mass in the epigastric region. Computed tomography showed a 10-cm mass originating in the abdominal wall that had invaded the liver. It was diagnosed as malignant mesothelioma via biopsy. Cases of sarcoma-like mass-forming peritoneal mesothelioma are rare, and there are no prior reports of encapsulating peritoneal sclerosis complicated by malignant peritoneal mesothelioma. Thus, this unique case of peritoneal mesothelioma can provide us with important knowledge about this rare entity.

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.

[A case of encapsulating of peritoneal sclerosis with fast and ominous evolution]

Encapsulating peritoneal sclerosis (EPS) is a rare and life-threatening complication of long-term peritoneal dialysis and until now, there is no established medical treatment for it. Many factors have been incriminated in its pathogenesis but they do not explain all risk conditions. EPS is significantly associated with PD duration, particularly more than 5 years, however the relationship between long-term PD and EPS increased risk is currently unknown. The "two-hit hypothesis" analyzes the relationship between the histological changes Peritoneal Dialysis-induced and intercurrent acute inflammatory episodes, but it does not explain the transition from Sclerosis Simple to EPS. We report our experience and we investigate the predisposing factors. The abdominal cocooning is a pathognomonic finding but it requires further investigations. Probably unidentified factors make some patients more susceptible to developing encapsulating peritoneal sclerosis.

Rat Models of Acute and/or Chronic Peritoneal Injuries Including Peritoneal Fibrosis and Peritoneal Dialysis Complications

Peritoneal injury is a major cause of discontinuation from long-term peritoneal dialysis. However, the precise mechanisms underlying such injury remain unclear. Suitable animal models of peritoneal injury may be useful to analyze pathogenic mechanisms and facilitate the development of therapeutic approaches. We describe herein two rat models of peritoneal injury that we have recently proposed.

Long-Term Success with Adhesiolysis in Post-Transplant Encapsulating Peritoneal Sclerosis: A Retrospective Case Series of 4 Patients and Review of the Literature

Encapsulating peritoneal sclerosis (EPS) is an occasional and serious complication for peritoneal dialysis (PD) patients for whom no evidence-based management strategies have yet been established. Encapsulating peritoneal sclerosis could appear after kidney transplantation in patients who previously underwent long-term PD. In this report, we present our experience in four PD patients diagnosed with EPS after kidney transplantation. Adhesiolysis provided improvement in their acute clinical conditions and allograft functions, despite the long-term follow-up. Surgical intervention may be a safe modality for this specific group of patients.

Time Is Not Always the Matter: An Instance of Encapsulating Peritoneal Sclerosis Developing in a Patient on Peritoneal Dialysis for a Short Term

Encapsulating peritoneal sclerosis (EPS) is an infrequent but serious complication that is observed mostly in patients on long-term peritoneal dialysis (PD). However it can occur after short-term PD, in association with "second hit" risk factors such as peritonitis, acute cessation of PD, or kidney transplantation with the use of calcineurin inhibitors.In our case, a young woman with second-hit risk factors presented with clinical and abdominal computed tomography findings consistent with EPS after short-term PD. She was treated conservatively with nutritional support and was discharged in improved and stable clinical status.In general, the diagnosis of EPS requires clinical findings of bowel obstruction combined with typical computed tomography imaging features. However, the clinical manifestations can be very vague, and the diagnosis is often unclear. A recent study categorized EPS into 4 clinical stages, from pre-EPS to chronic ileus, with associated management from conservative treatment to surgical intervention.In association with second-hit risk factors, EPS can occur after short-term PD. Severity is variable, and the outcome is often devastating. Timely recognition and expert management of EPS can change the outcome very favorably.

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.

mTOR inhibitors for medical treatment of post-transplantation encapsulating peritoneal sclerosis: a favourable single center experience

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is a serious complication in patients on peritoneal dialysis (PD) causing intestinal obstruction. Two different forms of EPS are reported: the classical one observed in patients on PD, and post-transplantation EPS (PostTx-EPS). The first-line therapy of classical and PostTx-EPS remains surgical treatment, but for both the complication rate and mortality are high. Recently, a few cases of EPS were successfully treated with inhibitors of mammalian target of rapamycin (mTORi). The aim of this study was to evaluate PostTx-EPS outcome in our patients, focusing on the potential benefit of mTORi treatment.

METHODS

We performed a retrospective analysis on 1,048 kidney transplanted patients at our center between 11/2001 and 12/2011.

RESULTS

In the 226 patients treated with PD at any time before grafting, we found 10 cases of PostTx-EPS (prevalence 4.4%). The mean age was 54.9 years (26-69), with a mean time on PD of 83.1 months (33-156). The interval between kidney transplant and EPS diagnosis was 10.5 months (4-18.9). Five of the ten patients were treated after the diagnosis with mTORi, with a favorable outcome in 4/5 cases. This result was substantially independent of surgical and steroid therapy, performed in 9/10 and 10/10 patients respectively.

CONCLUSION

EPS is a serious complication but susceptible to improvement if early diagnosed. mTORi represent a useful option for EPS treatment. We too suggest adopting an immunosuppressive protocol based on mTORi, mycophenolate mofetil and steroids in order to prevent PostTx-EPS in transplanted patients at high risk.

[Encapsulating peritoneal sclerosis in a patient who had previously been in peritoneal dialysis]

Encapsulating peritoneal sclerosis (EPS) is a rare but potentially fatal complication to long-term peritoneal dialysis (PD). We describe a case of EPS in a 58-year-old patient who had formerly had PD. The interdisciplinary approach for diagnosis and possible treatments in this condition is discussed.

A review of rodent models of peritoneal dialysis and its complications

This article reviews the available rodent models of peritoneal dialysis (PD) that have been developed over the past 20 years and the complications associated with their use. Although there are several methods used in different studies, the focus of this article is not to review or provide detailed summaries of these methods. Rather, this article reviews the most common methods of establishing a dialysis model in rodents, the assays used to observe function of the peritoneum in dialysis, and how these models are adapted to study peritonitis and peritoneal fibrosis. We compared the advantages and disadvantages of different methods, which should be helpful in studies of PD and may provide valuable data for further clinical studies.

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.

Living with encapsulating peritoneal sclerosis (EPS): the patient's perspective

BACKGROUND

Although relatively rare, encapsulating peritoneal sclerosis (EPS) is nonetheless a major concern within the renal community. Risk of developing EPS is associated with long-term peritoneal dialysis (PD). High mortality was previously reported, although surgery has since improved outcomes. Research into EPS focuses on imaging and early detection methods, genetics, biomarkers and preventive strategies. No previous studies have examined patients' experiences of EPS.

AIMS

The aim of the present study was to explore the experience of patients who have undergone surgery for EPS in one center in the North of England.

METHODS

A qualitative phenomenological approach, involving in-depth interviews, was adopted. Nine participants were recruited out of a total of 18 eligible. Most participants were interviewed twice over a 12-month period (October 2009 to October 2010).

ANALYSIS

Interpretive data analysis was conducted, following the philosophical tradition of hermeneutics, to draw out themes from the data. Data collection and analysis took place concurrently and participants were sent a summary of their first interview to allow a period of reflection prior to the subsequent interview.

RESULTS

EPS presented the most serious challenge participants had faced since developing chronic kidney disease (CKD). Three major themes were identified, each with subcategories. The key issues for patients were related to identification of early symptoms and lack of understanding. The patients' sense of 'not being heard' by health care professionals led to a loss of trust and enhanced their feelings of uncertainty. The enormity of the surgery, the suffering, and what they had to endure had an enormous impact, but an overriding aspect of this experience was also the loss they felt for their independence and for the PD therapy over which they had control.

CONCLUSIONS

The findings of this study highlight a number of important issues relevant to clinical practice, including lack of information and understanding of EPS, particularly its early symptoms At the time patients transfer from peritoneal to hemodialysis, the provision of adequate information about the risks and potential early signs of EPS may not only improve their experiences, but may also assist in early detection.

Peritoneal fibrosis induced by intraperitoneal methylglyoxal injection: the role of concurrent renal dysfunction

BACKGROUND

Peritoneal fibrosis (PF) is a serious pathophysiology of peritoneal dialysis (PD). An ongoing focus of research is the potential fibrogenic nature of methylglyoxal (MGO) in conventional PD fluid (PDF). The aim of the current study was to explore the effects of the uremic milieu on the promotion of PF by MGO using rats with adenine-induced renal failure (RF).

METHODS

Adenine-treated Sprague-Dawley rats were randomly assigned to receive continuous peritoneal injections of PDF with or without MGO for three weeks or were left untreated for the same duration. Rats without RF were also assigned to three groups. The peritoneal histology and expression levels of type I collagen, transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (αSMA), Snail, matrix metalloproteinase-2 (MMP-2), advanced glycation end-products (AGEs) and the receptor for AGE (RAGE) were then analyzed.

RESULTS

Peritoneal treatment with 5 mM MGO accelerated the fibrous peritoneal thickening progression promoted by exposure to standard PDF in the rats with RF, but not in the rats with a normal renal function. Treatment with MGO significantly augmented the proliferation of mesenchymal-like mesothelial cells, accumulation of AGE, de novo expression of αSMA and RAGE and gene expression of type I collagen, TGF-β1, Snail and MMP-2, whereas both MGO and RF alone had, at most, marginal effects on the changes in these biological parameters.

CONCLUSIONS

In the present study, the adverse effects of MGO on the peritoneum became more prominent under conditions of a uremic milieu. These findings imply that MGO and uremia act cooperatively to induce PF.