BMSC-derived Exosomes Ameliorate Peritoneal Dialysis-associated Peritoneal Fibrosis via the Mir-27a-3p/TP53 Pathway.

OBJECTIVE: Peritoneal fibrosis (PF) is the main cause of declining efficiency and ultrafiltration failure of the peritoneum, which restricts the long-term application of peritoneal dialysis (PD). This study aimed to investigate the therapeutic effects and mechanisms of bone marrow mesenchymal stem cells-derived exosomes (BMSC-Exos) on PF in response to PD. METHODS: Small RNA sequencing analysis of BMSC-Exos was performed by second-generation sequencing. C57BL/6J mice were infused with 4.25% glucose-based peritoneal dialysis fluid (PDF) for 6 consecutive weeks to establish a PF model. A total of 36 mice were randomly divided into 6 groups: control group, 1.5% PDF group, 2.5% PDF group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to measure the expression level of miR-27a-3p in BMSC-Exos and peritoneum of mice treated with different concentrations of PDF. HE and Masson staining were performed to evaluate the extent of PF. The therapeutic potential of BMSC-Exos for PF was examined through pathological examination, RT-qPCR, Western blotting, and peritoneal function analyses. Epithelial-mesenchymal transition (EMT) of HMrSV5 was induced with 4.25% PDF. Cells were divided into control group, 4.25% PDF group, BMSC-Exos treatment group, and BMSC-Exos+TP53 treatment group. Cell Counting Kit-8 assay was used to measure cell viability, and transwell migration assay was used to verify the capacity of BMSC-Exos to inhibit EMT in HMrSV5 cells. RESULTS: Small RNA sequencing analysis showed that miR-27a-3p was highly expressed in BMSC-derived exosomes compared to BMSCs. The RT-qPCR results showed that the expression of miR-27a-3p was upregulated in BMSC-Exos, but decreased in PD mice. We found that PF was glucose concentration-dependently enhanced in the peritoneum of the PD mice. Compared with the control mice, the PD mice showed high solute transport and decreased ultrafiltration volume as well as an obvious fibroproliferative response, with markedly increased peritoneal thickness and higher expression of α-SMA, collagen-I, fibronectin, and ECM1. The mice with PD showed decreased miR-27a-3p. Peritoneal structural and functional damage was significantly attenuated after BMSC-Exos treatment, while PF and mesothelial damage were significantly ameliorated. Additionally, markers of fibrosis (α-SMA, collagen-I, fibronectin, ECM1) and profibrotic cytokines (TGF-ß1, PDGF) were downregulated at the mRNA and protein levels after BMSC-Exos treatment. In HMrSV5 cells, BMSC-Exos reversed the decrease in cell viability and the increase in cell migratory capacity caused by high-glucose PDF. Western blotting and RT-qPCR analysis revealed that BMSC-Exos treatment resulted in increased expression of E-cadherin (epithelial marker) and decreased expression of α-SMA, Snail, and vimentin (mesenchymal markers) compared to those of the 4.25% PDF-treated cells. Importantly, a dual-luciferase reporter assay showed that TP53 was a target gene of miR-27a-3p. TP53 overexpression significantly reversed the decreases in PF and EMT progression induced by BMSC-Exos. CONCLUSION: The present results demonstrate that BMSC-Exos showed an obvious protective effect on PD-related PF and suggest that BMSC-derived exosomal miR-27a-3p may exert its inhibitory effect on PF and EMT progression by targeting TP53.

High glucose dialysate-induced peritoneal fibrosis: Pathophysiology, underlying mechanisms and potential therapeutic strategies.

Peritoneal dialysis is an efficient renal replacement therapy for patients with end-stage kidney disease. However, continuous exposure of the peritoneal membrane to dialysate frequently leads to peritoneal fibrosis, which alters the function of the peritoneal membrane and results in withdrawal from peritoneal dialysis in patients. Among others, high glucose dialysate is considered as a predisposing factor for peritoneal fibrosis in patients on peritoneal dialysis. Glucose-induced inflammation, metabolism disturbance, activation of the renin-angiotensin-aldosterone system, angiogenesis and noninflammation-induced reactive oxygen species are implicated in the pathogenesis of high glucose dialysate-induced peritoneal fibrosis. Specifically, high glucose causes chronic inflammation and recurrent peritonitis, which could cause migration and polarization of inflammatory cells, as well as release of cytokines and fibrosis. High glucose also interferes with lipid metabolism and glycolysis by activating the sterol-regulatory element-binding protein-2/cleavage-activating protein pathway and increasing hypoxia inducible factor-1α expression, leading to angiogenesis and peritoneal fibrosis. Activation of the renin-angiotensin-aldosterone system and Ras-mitogen activated protein kinase signaling pathway is another contributing factor in high glucose dialysate-induced fibrosis. Ultimately, activation of the transforming growth factor-ß1/Smad pathway is involved in mesothelial-mesenchymal transition or epithelial-mesenchymal transition, which leads to the development of fibrosis. Although possible intervention strategies for peritoneal dialysate-induced fibrosis by targeting the transforming growth factor-ß1/Smad pathway have occasionally been proposed, lack of laboratory evidence renders clinical decision-making difficult. We therefore aim to revisit the upstream pathways of transforming growth factor-beta1/Smad and propose potential therapeutic targets for high glucose-induced peritoneal fibrosis.

The Transfer of the Hepatocyte Growth Factor Gene by Macrophages Ameliorates the Progression of Peritoneal Fibrosis in Mice.

Growing evidence indicates that hepatocyte growth factor (HGF) possesses potent antifibrotic activity. Furthermore, macrophages migrate to inflamed sites and have been linked to the progression of fibrosis. In this study, we utilized macrophages as vehicles to express and deliver the HGF gene and investigated whether macrophages carrying the HGF expression vector (HGF-M) could suppress peritoneal fibrosis development in mice. We obtained macrophages from the peritoneal cavity of mice stimulated with 3% thioglycollate and used cationized gelatin microspheres (CGMs) to produce HGF expression vector-gelatin complexes. Macrophages phagocytosed these CGMs, and gene transfer into macrophages was confirmed in vitro. Peritoneal fibrosis was induced by intraperitoneal injection of chlorhexidine gluconate (CG) for three weeks; seven days after the first CG injection, HGF-M was administered intravenously. Transplantation of HGF-M significantly suppressed submesothelial thickening and reduced type III collagen expression. Moreover, in the HGF-M-treated group, the number of α-smooth muscle actin- and TGF-ß-positive cells were significantly lower in the peritoneum, and ultrafiltration was preserved. Our results indicated that the transplantation of HGF-M prevented the progression of peritoneal fibrosis and indicated that this novel gene therapy using macrophages may have potential for treating peritoneal fibrosis.

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.

Encapsulating peritoneal sclerosis: Your questions answered.

Encapsulating peritoneal sclerosis (EPS) is a clinical syndrome hallmarked by the formation of a fibrous cocoon encapsulating the bowel resulting in morbidity and mortality. EPS is most frequently associated with peritoneal dialysis (PD), particularly with its discontinuation. While EPS is one of the most feared complications of PD, the majority of patients receiving PD will not go on to develop EPS. Risk factors for development include time on PD, some types of peritonitis and discontinuation of PD. Owing to its rarity, much of the knowledge of EPS comes from case series and registries and treatments are extrapolated from low-quality evidence. Malnutrition is a significant driver of mortality, and nutritional support is critical in management. We present a case of EPS and frequently asked questions including the definition, diagnosis, epidemiology, pathophysiology, risk factors, role of infection, management and roles of nutrition and surgery.

Fibrosis of Peritoneal Membrane as Target of New Therapies in Peritoneal Dialysis.

Peritoneal dialysis (PD) is an efficient renal replacement therapy for patients with end-stage renal disease. Even if it ensures an outcome equivalent to hemodialysis and a better quality of life, in the long-term, PD is associated with the development of peritoneal fibrosis and the consequents patient morbidity and PD technique failure. This unfavorable effect is mostly due to the bio-incompatibility of PD solution (mainly based on high glucose concentration). In the present review, we described the mechanisms and the signaling pathway that governs peritoneal fibrosis, epithelial to mesenchymal transition of mesothelial cells, and angiogenesis. Lastly, we summarize the present and future strategies for developing more biocompatible PD solutions.

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.

Encapsulating peritoneal sclerosis: from early diagnosis to successful kidney transplantation.

Encapsulating peritoneal sclerosis is an uncommon but serious complication of peritoneal dialysis. In most cases, the symptoms appear after peritoneal dialysis withdrawal, which hampers its diagnosis. We present the case of a 44-years-old Caucasian male who had been on peritoneal dialysis for 6 years and 3 months and was switched to hemodialysis due to ultrafiltration failure. During his last months on peritoneal dialysis, he developed anorexia and asthenia, which were initially attributed to dialysis inadequacy. After hemodialysis induction, the patient developed abdominal pain, increased abdominal volume, obstipation alternating with diarrhea, and weight loss. Computed tomography showed de novo ascites. A diagnosis of early encapsulating peritoneal sclerosis was considered, and treatment was promptly initiated with nutritional support, oral prednisolone, and tamoxifen for one year. The patient progressed with resolution of the symptoms. One month after the end of the treatment, he underwent a successful kidney transplant and remain without any major intercurrences. A high level of clinical suspicion is crucial for the early diagnosis of encapsulating peritoneal sclerosis as the disease can be fatal in advanced stages. This case highlights that with early treatment, kidney transplantation can be successfully performed after an episode of encapsulating peritoneal sclerosis.

Clinical improvement of encapsulating peritoneal sclerosis after challenging course and 6 months of total parenteral nutrition in child with nephronophthisis: a case report.

BACKGROUND: Encapsulating peritoneal sclerosis is a rare but potentially lethal complication of long-term peritoneal dialysis that is associated with significant morbidity and mortality. The occurrence of encapsulating peritoneal sclerosis varies worldwide, but is increased in patients maintained on peritoneal dialysis for 5-8 years. The etiology of encapsulating peritoneal sclerosis remains unidentified, and a high index of clinical suspicion is required for diagnosis. CASE PRESENTATION: We report a 5-year-old Saudi female with end-stage renal disease secondary to nephronophthisis type 2. She underwent peritoneal dialysis for 30 months, with four episodes of peritonitis. She presented with clinical signs of peritonitis. Three days later, she developed septic shock, which required pediatric intensive care unit admission. The peritoneal dialysis catheter was removed because of refractory peritonitis. Her course was complicated by small bowel perforation, and severe adhesions were revealed on abdominal ultrasound and computed tomography, consistent with a diagnosis of EPS. This finding was later confirmed by diagnostic laparotomy performed twice and complicated by recurrent abdominal wall fistula. She received total parenteral nutrition for 6 months and several courses of antibiotics. The patient received supportive treatment including nutritional optimization and treatment for infection. No other treatments, such as immunosuppression, were administered to avoid risk of infection. Following a complicated hospital course, the patient restarted oral intake after 6 months of total parenteral nutrition dependency. Her abdominal fistula resolved completely, and she was maintained on hemodialysis for few years before she received a kidney transplant. CONCLUSION: When treating patients using peritoneal dialysis, it is important to consider encapsulating peritoneal sclerosis with refractory peritonitis, which is not always easy to identify, particularly if the patient has been maintained on peritoneal dialysis for less than 3 years. Early identification of encapsulating peritoneal sclerosis and appropriate conservative treatment, including nutritional optimization and treatment of infections, are essential to achieve a better prognosis.

Mesenchymal stem cells cultured in serum-free medium ameliorate experimental peritoneal fibrosis.

BACKGROUND: Mesenchymal stem cells (MSCs) provide potential treatments for peritoneal fibrosis. However, MSCs cultured in media containing serum bring risks of infection and other problems. In this study, we compared the effect of human MSCs in serum-free medium (SF-MSCs) on peritoneal fibrosis with that of MSCs cultured in medium containing 10% fetal bovine serum (10%MSCs). METHODS: Peritoneal fibrosis was induced by intraperitoneally injecting 0.1% chlorhexidine gluconate (CG). SF-MSCs or 10%MSCs were intraperitoneally administered 30 min after the CG injection. Ten days after the CG and MSC injections, we performed histological analyses and peritoneal equilibrium testing. In the in vitro experiments, we used transforming growth factor (TGF)-ß1-stimulated human peritoneal mesothelial cells incubated in conditioned medium from MSCs to examine whether the SF-MSCs showed enhanced ability to produce antifibrotic humoral factors. RESULTS: Histological staining showed that the SF-MSCs significantly suppressed CG-induced cell accumulation and thickening compared with that of the 10%MSCs. Additionally, the SF-MSCs significantly inhibited mesenchymal cell expression, extracellular matrix protein deposition and inflammatory cell infiltration. Peritoneal equilibration testing showed that compared with administering 10%MSCs, administering SF-MSCs significantly reduced the functional impairments of the peritoneal membrane. The in vitro experiments showed that although the conditioned medium from MSCs suppressed TGF-ß1 signaling, the suppression did not significantly differ between the SF-MSCs and 10%MSCs. CONCLUSIONS: Serum-free culture conditions can enhance the antifibrotic abilities of MSCs by suppressing inflammation. Administering ex vivo expanded SF-MSCs may be a potential therapy for preventing peritoneal fibrotic progression.

Adipose-derived mesenchymal stem cells attenuate dialysis-induced peritoneal fibrosis by modulating macrophage polarization via interleukin-6.

BACKGROUND: Life-long peritoneal dialysis (PD) as a renal replacement therapy is limited by peritoneal fibrosis. Previous studies showed immunomodulatory and antifibrotic effects of adipose-derived mesenchymal stem cells (ADSCs) on peritoneal fibrosis. However, the role of the peritoneal macrophage in this process remains uninvestigated. METHODS: We examined the therapeutic effects of ADSC and bone marrow-derived mesenchymal stem cells (BM-MSC) in the rat model of dialysis-induced peritoneal fibrosis using methylglyoxal. In addition, treatment of macrophages with the conditioned medium of ADSC and BM-MSC was performed individually to identify the beneficial component of the stem cell secretome. RESULTS: In the in vivo experiments, we found dialysis-induced rat peritoneal fibrosis was attenuated by both ADSC and BM-MSC. Interestingly, ADSC possessed a more prominent therapeutic effect than BM-MSC in ameliorating peritoneal membrane thickening while also upregulating epithelial cell markers in rat peritoneal tissues. The therapeutic effects of ADSC were positively associated with M2 macrophage polarization. In the in vitro experiments, we confirmed that interleukin-6 (IL-6) secreted by MSCs upon transforming growth factor-ß1 stimulation promotes M2 macrophage polarization. CONCLUSIONS: In dialysis-induced peritoneal fibrosis, MSCs are situated in an inflammatory environment of TGF-ß1 and secrete IL-6 to polarize macrophages into the M2 phenotype. Our findings reveal a previously unidentified role of tissue macrophage in this antifibrotic process. ADSC has the advantage of abundance and accessibility, making the application values extremely promising. In dialysis-induced peritoneal fibrosis, peritoneal mesothelial cells secrete transforming growth factor-ß1 (TGF-ß1) when exposed to methylglyoxal (MGO)-containing peritoneal dialysate. When situated in TGF-ß1, the inflammatory environment induces mesenchymal stem cells to secrete interleukin-6 (IL-6), IL-6 polarizes macrophages into the M2 phenotype. The dominant peritoneal tissue M2 macrophages, marked by upregulated Arg-1 expression, account for the attenuation of MGO-induced dedifferentiation of peritoneal mesothelial cells to maintain epithelial integrity.

Recent Understanding of Peritoneal Pathology in Peritoneal Dialysis Patients in Japan.

The thin peritoneum covering the peritoneal cavity has been used as a dialysis membrane for peritoneal dialysis (PD) because it is highly vascularized and has a large body surface area. However, it has been reported that peritoneal membranes affected by peritonitis, as well as those exposed to the nonphysiological high glucose levels containing PD dialysate, may undergo histological and functional changes. Patients undergoing PD may experience encapsulating peritoneal sclerosis (EPS), which is a life-threatening serious complication of PD that can significantly impair activities of daily living. The incidence of EPS was 1.4-7.3% of maintenance PD patients in the 1980s. The incidence has improved to 1.0% after a neutral dialysate became the standard PD treatment in Japan. Furthermore, the pathogenesis of EPS is uncertain although its onset may be explained by the "two-hit theory," in which some factors leading to impairment had an additive effect on simple peritoneal sclerosis. The evaluation of histopathological findings has shown the impact of the neutral dialysate on peritoneal deterioration as well as its role in the development of functional changes. In the present report, we discuss the advances in the understanding of peritoneal deterioration based on histological and macroscopic evaluations of the peritoneum of patients undergoing PD. We also discuss the recent treatment for PD patients.

SIRT1-modified human umbilical cord mesenchymal stem cells ameliorate experimental peritoneal fibrosis by inhibiting the TGF-ß/Smad3 pathway.

INTRODUCTION: Peritoneal fibrosis is a serious complication of long-term peritoneal dialysis (PD). Combination therapies are emerging as a promising treatment for tissue damage. Here, we investigated the therapeutic potential of SIRT1-modified human umbilical cord mesenchymal stem cells (hUCMSCs) for peritoneal fibrosis. METHODS: SIRT1 was overexpressed in hUCMSCs to establish SIRT1-modified hUCMSCs. Co-culture and transplantation experiments were performed in TGF-ß-stimulated Met-5A cells and peritoneal damage rodent model to assess the therapeutic potential of SIRT1-modified hUCMSCs for peritoneal fibrosis through qPCR, Western blot, and peritoneal function analyses. RESULTS: SIRT1-modified hUCMSC administration had more potent anti-fibrosis ability than hUCMSCs, which significantly inhibited the expression of fibrotic genes and suppressed EMT process, increased ultrafiltration volume, and restored homeostasis of bioincompatible factors in dialysis solution. Mechanistically, SIRT1-modified hUCMSCs attenuated peritoneal fibrosis through reducing peritoneal inflammation and inhibiting the TGF-ß/Smad3 pathway in peritoneal omentum tissues. CONCLUSION: SIRT1-modified hUCMSCs might work as a promising therapeutic strategy for the treatment of peritoneal dialysis-induced peritoneal damage and fibrosis.

Treatments and outcomes of encapsulating peritoneal sclerosis in patients undergoing peritoneal dialysis: 295 cases from a nationwide inpatient database in Japan.

BACKGROUND: The number of patients undergoing renal replacement therapy is increasing. We evaluated the practice patterns and outcomes of encapsulating peritoneal sclerosis (EPS) in patients undergoing peritoneal dialysis. METHODS: Using a Japanese national inpatient database, we identified 295 patients with EPS who were hospitalized from July 2010 to March 2017. We categorized them into four groups: those who underwent surgery only (n = 39), those who received corticosteroid treatment only (n = 70), those who underwent both (n = 30), and those who underwent neither (n = 156). We investigated their characteristics, treatments, and outcomes. RESULTS: More than half of patients were males and never-smokers and had a normal body mass index. Patients tended to undergo parenteral nutrition for 2 months. The proportions of emergency admission, intensive care unit (ICU) admission, central venous catheterization, catecholamine use, mechanical ventilation, and continuous hemodiafiltration were significantly different among the four groups (61%, 8.1%, 37.0%, 44.0%, 8.8%, and 5.8%, respectively). The both-treatment group had a significantly longer hospital stay (37.0 vs. 37.5 vs. 72.5 vs. 31.0 days, p < 0.001) and higher costs (US$16,554 vs. US$17,029 vs. US$33,757 vs. US$13,983, p < 0.001) than the other groups. In total, 52 patients (18%) died during hospitalization. There was no significant difference in inhospital complications and death, discharge status, 30-day readmission, or length of ICU stay among the four groups. CONCLUSIONS: Our findings provide useful information for clinicians and patients hospitalized for treatment of EPS.

10-year-long survival in a PD patient with severe calcifying encapsulating peritoneal sclerosis treated with tamoxifen: a case-report.

BACKGROUND: Encapsulating-peritoneal-sclerosis (EPS) is a rare, but serious and life-threatening complication of peritoneal dialysis (PD). Treatment of EPS consists of discontinuation of PD and maintenance of nutritional status, whereas the role of corticosteroids, tamoxifen and other immunosuppresive agents is not yet fully elucidated. CASE-PRESENTATION: We report the case of a 28-year-old patient, who developed a severe form of calcifying EPS after a 6-year-long therapy with automated PD. The clinical presentation was severe with repeated episodes of total bowel obstruction, weight loss and malnutrition that mandated his prolonged hospitalization. Initial treatment included corticosteroids and tamoxifen (20 mg/day) with a clinically meaningful improvement in gastrointestinal function and nutritional status over the first 6-12 months. Corticosteroids were discontinued at 18 months, but owing to persistence of calcifying lesions and peritoneal thickening in repeated computed-tomography (CT) scans, tamoxifen remained unmodified at a low-dose of 20 mg/day for a 10-year-long period. During follow-up, the patient remained symptoms-free in an excellent clinical condition and the CT findings were unchanged. CONCLUSIONS: Long-term administration of tamoxifen was not accompanied by any drug-related adverse effects and potentially exerted a beneficial action on down-regulation of inflammatory and fibrotic processes and improvement of gastrointestinal function, nutritional status and overall health-related quality of life.

Klotho is a novel therapeutic target in peritoneal fibrosis via Wnt signaling inhibition.

BACKGROUND: Long-term exposure to bioincompatible peritoneal dialysate causes the loss of mesothelial cells and accumulation of matrix proteins, leading to an increase in the thickness of the submesothelial layer, thereby limiting the long-term effectiveness of peritoneal dialysis (PD). However, the detailed molecular mechanisms underlying the process of peritoneal fibrosis have not been clearly elucidated. Wnt/ß-catenin signaling pathway activation has been suggested to play a pivotal role in the development of organ fibrosis. Moreover, Klotho protein can regulate Wnt/ß-catenin signaling. We examined the role of Klotho protein in reducing peritoneal fibrosis by inhibiting Wnt/ß-catenin signaling. METHODS: The ß-catenin-activated transgenic (BAT) driving expression of nuclear ß-galactosidase reporter transgenic (BAT-LacZ) mice, the alpha-Klotho gene under control of human elongation factor 1 alpha promoter [Klotho transgenic (KLTG) and C57BL/6 background] and C57BL/6 mice [wild-type (WT)] were used. The mice received daily intraperitoneal (i.p.) injections of 4.25% glucose with lactate (PD solution) or saline as a control for 4 weeks. Other mice received daily i.p. injections of the same volume of saline (normal control). RESULTS: After exposure to PD, Wnt signal activation was observed on the peritoneal mesothelial cells in WT-PD mice. The peritoneal fibrosis was also accelerated in WT-PD mice. The protein expression of ß-catenin and Wnt-inducible genes were also remarkably increased in WT-PD mice. On the other hand, KLTG-PD mice attenuated activation of Wnt/ß-catenin signaling after exposure to PD and ameliorated the progression of peritoneal fibrosis. CONCLUSIONS: Overexpression of Klotho protein protects the peritoneal membrane through attenuation of the Wnt/ß-catenin signaling pathway. The availability of recombinant Klotho protein would provide a novel potential therapeutic target in peritoneal fibrosis.

MiR-200a ameliorates peritoneal fibrosis and functional deterioration in a rat model of peritoneal dialysis.

Peritoneal fibrosis is recognised as the main cause of the technical failure of peritoneal dialysis (PD), and currently, there are no specific and effective anti-fibrosis therapies. We have found that miR-200a is down-regulated in a rat model of PD-related peritoneal fibrosis (PF) and could inhibit transforming growth factor beta 1 (TGF-ß1)-induced epithelial-mesenchymal transition (EMT) in peritoneal mesothelial cells by target ZEB1/2. However, its treatment role in vivo is still largely unclear. In this study, we examined the therapeutic potential for miR-200a on PD-related PF in a rat model of PD induced by daily infusion of 4.25% dextrose-containing dialysate. Male Sprague-Dawley rats were divided into four groups: control group, PD group, PD + miR-agomir-NC group, and PD + miR-200a-agomir group (n = 5 in each group). MiR-200a agomir was delivered into the peritoneum by intra-peritoneal injection on days 10 and 20 after PD. We found that treatment with miR-200a agomir significantly reduced the collagen volume fraction (CVF) of the peritoneum and prevented peritoneal dysfunction. The up-regulation of the EMT marker (decreased E-cadherin and increased α-smooth muscle actin) and extracellular matrix (fibronectin and collagen I) was significantly ameliorated by miR-200a in the PD + miR-200a-agomir group. Furthermore, we demonstrated that miR-200a inhibition of PF in vivo was associated with the suppression of ZEB1 and 2, which were proved to be the target of miR-200a in our previous study. In conclusion, results from the present study suggest that treatment with miR-200a may represent a novel and effective therapy for PD-related PF.

MicroRNA-302c modulates peritoneal dialysis-associated fibrosis by targeting connective tissue growth factor.

Long-term peritoneal dialysis (PD) can lead to the induction of mesothelial/epithelial-mesenchymal transition (MMT/EMT) and fibrosis; these effects eventually result in ultrafiltration failure and the discontinuation of PD. MicroRNA-302c (miR-302c) is believed to be involved in regulating tumour cell growth and metastasis by suppressing MMT, but the effect of miR-302c on MMT in the context of PD is unknown. MiR-302c levels were measured in mesothelial cells isolated from the PD effluents of continuous ambulatory peritoneal dialysis patients. After miR-302c overexpression using lentivirus, human peritoneal mesothelial cell line (HMrSV5) and PD mouse peritoneum were treated with TGF-ß1 or high glucose peritoneal dialysate respectively. MiR-302c expression level and MMT-related factors alteration were observed. In addition, fibrosis of PD mouse peritoneum was alleviated by miR-302c overexpression. Furthermore, the expression of connective tissue growth factor (CTGF) was negatively related by miR-302c, and LV-miR-302c reversed the up-regulation of CTGF induced by TGF-ß1. These data suggest that there is a novel TGF-ß1/miR-302c/CTGF pathway that plays a significant role in the process of MMT and fibrosis during PD. MiR-302c might be a potential biomarker for peritoneal fibrosis and a novel therapeutic target for protection against peritoneal fibrosis in PD patients.

Encapsulating peritoneal sclerosis: do not be too late for the right diagnosis! Case report and short literature review.

Encapsulating peritoneal sclerosis (EPS) is a rare clinical syndrome characterized by an acquired, inflammatory fibrocollagenous membrane encasing the small intestine, resulting in symptoms of bowel obstruction. It is still unclear whether early surgical intervention has an advantage over conservative management, but, in most reviewed case reports, it is preferred to preserve the surgical management in patients not responding to conservative measures, or when bowel ischaemia is occurring. We report a case of a 58-year old patients, affected by chronic renal failure, on treatment with peritoneal dialysis, in which a late diagnosis of encapsulating peritoneal sclerosis was made, and where surgical intervention was not sufficient to guarantee survival due to the late diagnosis.

Encapsulating Peritoneal Sclerosis: The Abdominal Cocoon.

Encapsulating peritoneal sclerosis (EPS) is a rare but serious condition that results in (a) encapsulation of bowel within a thickened fibrocollagenous peritoneal membrane and (b) recurrent episodes of bowel obstruction. Although described by various names in the literature, the preferred term is encapsulating peritoneal sclerosis because it best describes the morphologic and histologic changes in this disorder. The etiology of EPS is multifactorial, with a wide variety of implicated predisposing factors that disrupt the normal physiologic function of the peritoneal membrane-prime among these factors being long-term peritoneal dialysis and bacterial peritoneal infections, especially tuberculosis. The clinical features of EPS are usually nonspecific, and knowledge of the radiologic features is necessary to make a specific diagnosis. The findings on radiographs are usually normal. Images from small-bowel follow-through studies show the bowel loops conglomerated in a concertina-like fashion with a serpentine arrangement in a fixed U-shaped configuration. US demonstrates a "cauliflower" appearance of bowel with a narrow base, as well as a "trilaminar" appearance depicted especially with use of high-resolution US probes. CT is the imaging modality of choice and allows identification of the thickened contrast material-enhanced abnormal peritoneal membrane and the encapsulated clumped bowel loops. In addition, CT can potentially help identify the cause of EPS (omental granuloma in tuberculosis), as well as the complications of EPS (bowel obstruction). Conservative medical treatment and surgical therapy early in the course of EPS have been used for management of the condition. The purpose of this article is to review the nomenclature and etiopathogenesis of EPS, describe the multimodality imaging appearances of EPS, including differentiating its features from those of other conditions mimicking EPS, and give an overview of management options. Online DICOM image stacks are available for this article. ©RSNA, 2018.