Extracellular Vesicles of Patients on Peritoneal Dialysis Inhibit the TGF-ß- and PDGF-B-Mediated Fibrotic Processes.

Among patients on peritoneal dialysis (PD), 50-80% will develop peritoneal fibrosis, and 0.5-4.4% will develop life-threatening encapsulating peritoneal sclerosis (EPS). Here, we investigated the role of extracellular vesicles (EVs) on the TGF-ß- and PDGF-B-driven processes of peritoneal fibrosis. EVs were isolated from the peritoneal dialysis effluent (PDE) of children receiving continuous ambulatory PD. The impact of PDE-EVs on the epithelial-mesenchymal transition (EMT) and collagen production of the peritoneal mesothelial cells and fibroblasts were investigated in vitro and in vivo in the chlorhexidine digluconate (CG)-induced mice model of peritoneal fibrosis. PDE-EVs showed spherical morphology in the 100 nm size range, and their spectral features, CD63, and annexin positivity were characteristic of EVs. PDE-EVs penetrated into the peritoneal mesothelial cells and fibroblasts and reduced their PDE- or PDGF-B-induced proliferation. Furthermore, PDE-EVs inhibited the PDE- or TGF-ß-induced EMT and collagen production of the investigated cell types. PDE-EVs contributed to the mesothelial layer integrity and decreased the submesothelial thickening of CG-treated mice. We demonstrated that PDE-EVs significantly inhibit the PDGF-B- or TGF-ß-induced fibrotic processes in vitro and in vivo, suggesting that EVs may contribute to new therapeutic strategies to treat peritoneal fibrosis and other fibroproliferative diseases.

BRG1 accelerates mesothelial cell senescence and peritoneal fibrosis by inhibiting mitophagy through repression of OXR1.

Peritoneal mesothelial cell senescence promotes the development of peritoneal dialysis (PD)-related peritoneal fibrosis. We previously revealed that Brahma-related gene 1 (BRG1) is increased in peritoneal fibrosis yet its role in modulating peritoneal mesothelial cell senescence is still unknown. This study evaluated the mechanism of BRG1 in peritoneal mesothelial cell senescence and peritoneal fibrosis using BRG1 knockdown mice, primary peritoneal mesothelial cells and human peritoneal samples from PD patients. The augmentation of BRG1 expression accelerated peritoneal mesothelial cell senescence, which attributed to mitochondrial dysfunction and mitophagy inhibition. Mitophagy activator salidroside rescued fibrotic responses and cellular senescence induced by BRG1. Mechanistically, BRG1 was recruited to oxidation resistance 1 (OXR1) promoter, where it suppressed transcription of OXR1 through interacting with forkhead box protein p2. Inhibition of OXR1 abrogated the improvement of BRG1 deficiency in mitophagy, fibrotic responses and cellular senescence. In a mouse PD model, BRG1 knockdown restored mitophagy, alleviated senescence and ameliorated peritoneal fibrosis. More importantly, the elevation level of BRG1 in human PD was associated with PD duration and D/P creatinine values. In conclusion, BRG1 accelerates mesothelial cell senescence and peritoneal fibrosis by inhibiting mitophagy through repression of OXR1. This indicates that modulating BRG1-OXR1-mitophagy signaling may represent an effective treatment for PD-related peritoneal fibrosis.

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.

Investigating the therapeutic effects and mechanisms of Roxadustat on peritoneal fibrosis Based on the TGF-ß/Smad pathway.

Peritoneal fibrosis (PF) is particularly common in individuals undergoing peritoneal dialysis (PD). Fibrosis of the parenchymal tissue typically progresses slowly. Therefore, preventing and reducing the advancement of fibrosis is crucial for effective patient treatment. Roxadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI), primarily used to treat and improve renal anemia. Recent studies have found that HIF-1α possesses antioxidant activity and exerts a certain protective effect in ischemic heart disease and spinal cord injury, while it can also delay the progression of pulmonary and renal fibrosis. This study establishes the mice model through intraperitoneal injection of 4.25 % peritoneal dialysate fluid (PDF) and explores the therapeutic effects of Roxadustat by inducing TGF-ß1-mediated epithelial-mesenchymal transition (EMT) in Met-5A cells. The aim is to investigate the protective role and mechanisms of Roxadustat against PD-related PF. We observed thicker peritoneal tissue and reduced permeability in animals with PD-related PF samples. This was accompanied by heightened inflammation, which Roxadustat alleviated by lowering the levels of inflammatory cytokines (IL-6, TNF-α). Furthermore, Roxadustat inhibited EMT in PF mice and TGF-ß1-induced Met-5A cells, as evidenced by decreased expression of fibrotic markers, such as fibronectin, collagen I, and α-SMA, alongside an elevation in the expression of the epithelial marker, E-cadherin. Roxadustat also significantly decreased the expression of TGF-ß1 and the phosphorylation of p-Smad2 and p-Smad3. In conclusion, Roxadustat ameliorates peritoneal fibrosis through the TGF-ß/Smad pathway.

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.

Astragaloside IV ameliorates peritoneal fibrosis by promoting PGC-1α to reduce apoptosis in vitro and in vivo.

Prolonged exposure of the peritoneum to high glucose dialysate leads to the development of peritoneal fibrosis (PF), and apoptosis of peritoneal mesothelial cells (PMCs) is a major cause of PF. The aim of this study is to investigate whether Astragaloside IV could protect PMCs from apoptosis and alleviate PF. PMCs and rats PF models were induced by high glucose peritoneal fluid. We examined the pathology of rat peritoneal tissue by HE staining, the thickness of rat peritoneal tissue by Masson's staining, the number of mitochondria and oxidative stress levels in peritoneal tissue by JC-1 and DHE fluorescence staining, and mitochondria-related proteins and apoptosis-related proteins such as PGC-1α, NRF1, TFAM, Caspase3, Bcl2 smad2 were measured. We used hoechst staining and flow cytometry to assess the apoptotic rate of PMCs in the PF model, and further validated the observed changes in the expressions of PGC-1α, NRF1, TFAM, Caspase3, Bcl2 smad2 in PMCs. We further incubated PMCs with MG-132 (proteasome inhibitor) and Cyclohexylamine (protein synthesis inhibitor). The results demonstrated that Astragaloside IV increased the expression of PGC-1α by reducing the ubiquitination of PGC-1α. It was further found that the protective effects of Astragaloside IV on PMCs were blocked when PGC-1α was inhibited. In conclusion, Astragaloside IV effectively alleviated PF both in vitro and in vivo, possibly by promoting PGC-1α to enhance mitochondrial synthesis to reduce apoptotic effects.

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.

N-methylpiperazine-diepoxyovatodiolide ameliorates peritoneal fibrosis via suppressing TGF-ß/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-ß1)-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-ß1-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-ß1/Smad and JAK/STAT signaling pathway. Therefore, because of these antifibrotic effects, NMPDOva may be a promising therapeutic agent for PD-related PF.

Fibrosis of Peritoneal Membrane, Molecular Indicators of Aging and Frailty Unveil Vulnerable Patients in Long-Term Peritoneal Dialysis.

Peritoneal membrane status, clinical data and aging-related molecules were investigated as predictors of long-term peritoneal dialysis (PD) outcomes. A 5-year prospective study was conducted with the following endpoints: (a) PD failure and time until PD failure, (b) major cardiovascular event (MACE) and time until MACE. A total of 58 incident patients with peritoneal biopsy at study baseline were included. Peritoneal membrane histomorphology and aging-related indicators were assessed before the start of PD and investigated as predictors of study endpoints. Fibrosis of the peritoneal membrane was associated with MACE occurrence and earlier MACE, but not with the patient or membrane survival. Serum α-Klotho bellow 742 pg/mL was related to the submesothelial thickness of the peritoneal membrane. This cutoff stratified the patients according to the risk of MACE and time until MACE. Uremic levels of galectin-3 were associated with PD failure and time until PD failure. This work unveils peritoneal membrane fibrosis as a window to the vulnerability of the cardiovascular system, whose mechanisms and links to biological aging need to be better investigated. Galectin-3 and α-Klotho are putative tools to tailor patient management in this home-based renal replacement therapy.

Proteomic Characterization of Peritoneal Extracellular Vesicles in a Mouse Model of Peritoneal Fibrosis.

Peritoneal fibrosis progression is regarded as a significant cause of the loss of peritoneal function, markedly limiting the application of peritoneal dialysis (PD). However, the pathogenesis of peritoneal fibrosis remains to be elucidated. Tissue-derived extracellular vesicles (EVs) change their molecular cargos to adapt the environment alteration, mediating intercellular communications and play a significant role in organ fibrosis. Hence, we performed, for the first time, four-dimensional label-free quantitative liquid chromatography-tandem mass spectrometry proteomic analyses on EVs from normal peritoneal tissues and PD-induced fibrotic peritoneum in mice. We demonstrated the alterations of EV concentration and protein composition between normal control and PD groups. A total of 2339 proteins containing 967 differentially expressed proteins were identified. Notably, upregulated proteins in PD EVs were enriched in processes including response to wounding and leukocyte migration, which participated in the development of fibrosis. In addition, EV proteins of the PD group exhibited unique metabolic signature compared with those of the control group. The glycolysis-related proteins increased in PD EVs, while oxidative phosphorylation and fatty acid metabolism-related proteins decreased. We also evaluated the effect of cell-type specificity on EV proteins, suggesting that mesothelial cells mainly cause the alterations in the molecular composition of EVs. Our study provided a useful resource for further validation of the key regulator or therapeutic target of peritoneal fibrosis.

Relationship between laparoscopic and microscopic findings of peritoneum in peritoneal dialysis patients.

Long-term exposure to the peritoneal dialysis solution (PDS) causes functional and morphological alterations that diminish the efficacy of peritoneal dialysis (PD). Macroscopic and microscopic findings, submesothelial compact zone (SMC) thickness and vascular patency, were associated with PD duration. The relationship between microscopic and laparoscopic morphological findings in PD patients was determined. A total of 78 laparoscopic intraperitoneal findings were recorded during PD catheter removal and 45 peritoneal tissues were obtained from the anterior parietal peritoneum. We examined macroscopic morphological findings in both parietal and visceral peritoneums and bowel movement and assessed the score semiquantitatively. SMC thickness and vascular patency were examined as microscopic findings. Total laparoscopic finding's score (LFS) and microscopic findings, SMC thickness and vascular patency, were associated with PD duration. Total LFS was related to SMC thickness in both visceral and parietal peritoneum, whereas it was related to vascular patency in parietal but not in visceral peritoneum. There was no relationship between microscopic findings and peritoneal surface color, properties, vasculopathy, and adhesion. Total LFS in patients with newly formed membrane and omentum atrophy was higher than in those without. There was a significant relationship between microscopic and laparoscopic findings in PD patients. It is important to evaluate laparoscopic findings in more PD patients to find the predictive findings of encapsulating peritoneal sclerosis development.

Imaging pearls and differential diagnosis of encapsulating peritoneal sclerosis: Emphasis on computed tomography.

Encapsulating peritoneal sclerosis (EPS) is a severe peritoneal fibrotic reaction most frequently identified as a complication of peritoneal dialysis. EPS is a complex condition whose management requires multidisciplinary input from radiologists, gastroenterologists, nephrologists, surgeons, and dietitians. EPS carries significant morbidity and mortality, primarily due to bowel obstruction that results in intestinal failure, malnutrition, and sepsis. The nondialysis causes of EPS include tuberculous peritonitis, prior abdominal surgery, beta-blocker medication use, and endometriosis. The clinical symptoms of EPS are nausea, vomiting, and abdominal pain, all of which appear to be associated with bowel obstruction. The diagnosis of EPS needs three pillars to be met: clinical features, radiological evaluation, and histopathological analysis. The disease is frequently progressive and can be fatal. Computed tomography is the gold standard imaging modality for the detection of peritoneal abnormalities and encapsulation of bowel loops by thick adhesions or fibrosis (cocooning). Computed tomography also aids in making a differential diagnosis. Unfortunately, the diagnosis of EPS is often delayed because clinical findings are not specific and may resemble other peritoneal diseases. Radiologists should be familiar with the clinical impacts and related imaging features of EPS and realize when to seek them to facilitate timely and proper treatment.

Parthenolide alleviates peritoneal fibrosis by inhibiting inflammation via the NF-κB/ TGF-ß/Smad signaling axis.

Peritoneal fibrosis is a common complication of peritoneal dialysis (PD) with a complicated pathogenesis and limited treatments. Parthenolide (PTL), a recognized nuclear factor-κB (NF-κB) inhibitor extracted from Tanacetum balsamita, has been widely used to treat various inflammatory diseases and has been proven to improve peritoneal fibrosis in PD mice by selectively inhibiting the phosphorylation of Smad2/3. Transforming growth factor-ß1 (TGF-ß1), via Smad-dependent signaling, has a pivotal role in promoting pathogenic of fibrosis. To investigate whether PTL can inhibit peritoneal fibrosis, we affected the interaction between NF-κB and the TGF-ß/Smad2/3 pathway. Long dwell peritoneal dialysis fluid (PDF) and peritoneum tissues were collected from continuous ambulatory peritoneal dialysis (CAPD) patients. PTL was administered intragastrically into a PD mouse model by daily infusion of 4.25% dextrose-containing PDF. Treated HMrSV5 cells or rat peritoneal mesothelial cells (RPMCs) were treated with high glucose(138 mM) at the same concentration as 2.5% dextrose-containing PDF and PTL. PD-related peritoneal fibrosis samples indicated an increase in inflammation, and PTL decreased the levels of inflammatory cytokines (L-6, TNF-α, and MCP-1). PTL inhibited high glucose-induced mesothelial-to-mesenchymal transition (MMT), as indicated by a reduced expression of fibrosis markers (fibronectin, collagen I, and α-SMA) and increased expression of the epithelial marker E-cadherin. PTL also significantly decreased TGF-ß1 expression and the phosphorylation of IκBα and NF-κBp65. The changes in the levels of TGF-ß1 expression and p-p65 or p65 showed similar trends according to western blot, immunohistochemistry, and immunofluorescence assays in vitro and in vivo. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays were used to confirm that PTL regulates the transcription of TGF-ß1 induced by high glucose through NF-κBp65. In summary, PTL induces a therapeutic effect in peritoneal fibrosis by inhibiting inflammation via the NF-κB/ TGF-ß/Smad signaling axis.

A Clinically Relevant Murine Model of Peritoneal Fibrosis by Dialysate and Catheters.

Peritoneal fibrosis can occur in patients undergoing peritoneal dialysis (PD), and patients with severe peritoneal fibrosis have high morbidity and mortality. Peritonitis, high-glucose peritoneal dialysis fluid, and a long period of PD precipitate the onset of peritoneal fibrosis. An animal study of peritoneal fibrosis is needed due to the limitations of human and in vitro studies. However, most animal models do not mimic clinical conditions. To study peritoneal fibrosis, we developed a clinically relevant murine model by implanting a peritoneal catheter and injecting 2.5% high-glucose PD fluid plus 20 mM methylglyoxal (MGO) into the peritoneal cavity daily for 21 days. Implantation of the peritoneal catheter avoids peritoneal injury by needles and mimics clinical PD patients. Immunofluorescence staining showed that myofibroblasts accumulated in the fibrotic peritoneum. The experimental group had lower ultrafiltration volume and peritoneal membrane transport function (peritoneal equilibration test). In this article, we provide a detailed protocol of the model.

A Mice Model of Chlorhexidine Gluconate-Induced Peritoneal Damage.

Peritoneal fibrosis is an important complication of peritoneal dialysis (PD). To investigate and address this problem, an appropriate animal model of PD is required. The present protocol establishes a chlorhexidine gluconate (CG) induced peritoneal fibrosis model that mimics the condition of a patient with PD. Peritoneal fibrosis was induced by intraperitoneal injection of 0.1% of CG in 15% ethanol for 3 weeks (administered every other day), for a total of nine times in male C57BL/6 mice. Peritoneal functional tests were then performed on day 22. After the mice were sacrificed, the parietal peritoneum of the abdominal wall and the visceral peritoneum of the liver were harvested. They were thicker and more fibrotic when analyzed microscopically after Masson's trichrome staining. The ultrafiltration rate decreased, and glucose mass transport indicated a CG-induced increase in peritoneal permeability. The PD model thus established may have applications in improving PD technology, dialysis efficacy, and prolonging patient survival.

Epithelial-mesenchymal Transition of Peritoneal Mesothelial Cells Is Enhanced by M2c Macrophage Polarization.

BACKGROUND: Peritoneal fibrosis (PF) can reduce the efficiency of peritoneal dialysis and eventually lead to ultrafiltration failure. Epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) is the start of PF. Macrophages are involved in the process. This study was to investigate the effect of macrophage polarization on EMT of PMCs. METHODS: Monocyte-macrophage cells (THP-1) were treated to induce macrophage subsets (M1, M2a, M2c). The inducing was assessed by detecting protein and mRNA expression of cytokines using ELISA and RT-PCR. Subsequently, PMCs were co-cultured with M1, M2a and M2c, respectively, in Transwell chambers for 48 h and then expressions of E-cadherin and α-SMA were determined in PMCs. The PMCs that were not co-cultured with macrophages served as control PMCs. One-way ANOVA and SNK-q test were used to conduct statistics and P < .05 as significant. RESULTS: Detection of the cytokines, including IL-6, IL-10, IL-12, TGF-ß1, CCL17 and CXCL13, verified that the inducting of macrophage subtypes was successful. Compared to control, E-cadherin protein expression was significantly decreased and α-SMA protein expression increased in M1-treated PMCs (P < .05); M2a-treated PMCs had an increased gene expression of α-SMA (P < .05); E-cadherin protein and gene expression were decreased and α-SMA protein and gene expression increased significantly in M2c-treated PMCs (P < .05 or P < .01). CONCLUSIONS: EMT of PMCs is enhanced by M2c macrophage polarization; meanwhile, M1 and M2a polarization may have the effect to some extent, but not as definite as M2c.

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.

STAT3/HIF-1α signaling activation mediates peritoneal fibrosis induced by high glucose.

BACKGROUND: Epithelial-mesenchymal transition (EMT) of mesothelial cells is a key step in the peritoneal fibrosis (PF). Recent evidence indicates that signal transducer and activator of transcription 3 (STAT3) might mediate the process of renal fibrosis, which could induce the expression of hypoxia-inducible factor-1α (HIF-1α). Here, we investigated the effect of STAT3 activation on HIF-1α expression and the EMT of mesothelial cells, furthermore the role of pharmacological blockade of STAT3 in the process of PF during peritoneal dialysis (PD) treatment. METHODS: Firstly, we investigated the STAT3 signaling in human peritoneal mesothelial cells (HPMCs) from drained PD effluent. Secondly, we explored the effect of STAT3 signaling activation on the EMT and the expression of HIF-1α in human mesothelial cells (Met-5A) induced by high glucose. Finally, peritoneal fibrosis was induced by daily intraperitoneal injection with peritoneal dialysis fluid (PDF) so as to explore the role of pharmacological blockade of STAT3 in this process. RESULTS: Compared with the new PD patient, the level of phosphorylated STAT3 was up-regulated in peritoneal mesothelial cells from long-term PD patients. High glucose (60 mmol/L) induced over-expression of Collagen I, Fibronectin, α-SMA and reduced the expression of E-cadherin in Met-5A cells, which could be abrogated by STAT3 inhibitor S3I-201 pretreatment as well as by siRNA for STAT3. Furthermore, high glucose-mediated STAT3 activation in mesothelial cells induced the expression of HIF-1α and the profibrotic effect of STAT3 signaling was alleviated by siRNA for HIF-1α. Daily intraperitoneal injection of high-glucose based dialysis fluid (HG-PDF) induced peritoneal fibrosis in the mice, accompanied by the phosphorylation of STAT3. Immunostaining showed that phosphorylated STAT3 was expressed mostly in α-SMA positive cells in the peritoneal membrane induced by HG-PDF. Administration of S3I-201 prevented the progression of peritoneal fibrosis, angiogenesis, macrophage infiltration as well as the expression of HIF-1α in the peritoneal membrane induced by high glucose. CONCLUSIONS: Taken together, these findings identified a novel mechanism linking STAT3/HIF-1α signaling to peritoneal fibrosis during long-term PD treatment. It provided the first evidence that pharmacological inhibition of STAT3 signaling attenuated high glucose-mediated mesothelial cells EMT as well as peritoneal fibrosis.

Effects of TGF-ß1 Receptor Inhibitor GW788388 on the Epithelial to Mesenchymal Transition of Peritoneal Mesothelial Cells.

We investigated the effectiveness of the transforming growth factor beta-1 (TGF-ß) receptor inhibitor GW788388 on the epithelial to mesenchymal transition (EMT) using human peritoneal mesothelial cells (HPMCs) and examined the effectiveness of GW788388 on the peritoneal membrane using a peritoneal fibrosis mouse model. HPMCs were treated with TGF-ß with or without GW788388. Animal experiments were conducted on male C57/BL6 mice. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate. GW788388 was administered by once-daily oral gavage. The morphological change, cell migration, and invasion resulted from TGF-ß treatment, but these changes were attenuated by cotreatment with GW788388. TGF-ß-treated HPMCs decreased the level of the epithelial cell marker and increased the levels of the mesenchymal cell markers. Cotreatment with GW788388 reversed these changes. Phosphorylated Smad2 and Smad3 protein levels were stimulated with TGF-ß and the change was attenuated by cotreatment with GW788388. For the peritoneal fibrosis mice, thickness and collagen deposition of parietal peritoneum was increased, but this change was attenuated by cotreatment with GW788388. GW788388, an orally available potent TGF-ß receptor type 1 inhibitor, effectively attenuated TGF-ß-induced EMT in HPMCs. Cotreatment with GW788388 improved peritoneal thickness and fibrosis, and recovered peritoneal membrane function in a peritoneal fibrosis mouse model.