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.

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.

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.

MiR-132-3p suppresses peritoneal fibrosis induced by peritoneal dialysis via targeting TGF-ß1/Smad2/3 signaling pathway.

BACKGROUND: Peritoneal fibrosis (PF) is the main complication of peritoneal dialysis (PD) and the most common cause of cessation from PD. There is still no effective therapeutic approach to reserve PF. We aimed to investigate the role of miR-132-3p and underlying potential mechanisms in PF. METHODS: A total of 18 Sprague-Dawley (SD) rats were divided randomly into three groups (n = 6): (i)Control group (ii)PF group (iii)PF+Losartan group; Rats in the PF group and PF+Losartan group received daily intraperitoneal injections of 3 mg/kg chlorhexidine for 14 days, and rats in the PF+Losartan group simultaneously received daily intraperitoneal injections of 2 mg/kg losartan for 14 days. The control group was injected with saline in the same volume. Met-5A cells were treated for 24h with TGF-ß1 dissolved in recombinant buffered saline at a concentration of 10 ng/ml, meanwhile, PBS solution as a negative control. The human peritoneal solution was collected for the detection of miR-132-3p. RESULTS: In vivo, SD rats were infused with chlorhexidine to establish PF model, and we found that miR-132-3p significantly decreased and the expressions of transforming growth factor-ß1 (TGF-ß1), and Smad2/3 were up-regulated in PF. In vitro, miR-132-3p mimics suppressed TGF-ß1/Smad2/3 activity, whereas miR-132-3p inhibition activated the pathway. In human peritoneal solution, we found that the expression of miR-132-3p decreased in a time-dependent model and its effect became more pronounced with longer PD duration. CONCLUSION: MiR-132-3p ameliorated PF by suppressing TGF-ß1/Smad2/3 activity, suggesting that miR-132-3p represented a potential therapeutic approach for PF.

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 ß2 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.

Integrative analysis of chromatin accessibility and transcriptome landscapes in the induction of peritoneal fibrosis by high glucose.

BACKGROUND: Peritoneal fibrosis is the prevailing complication induced by prolonged exposure to high glucose in patients undergoing peritoneal dialysis. METHODS: To elucidate the molecular mechanisms underlying this process, we conducted an integrated analysis of the transcriptome and chromatin accessibility profiles of human peritoneal mesothelial cells (HMrSV5) during high-glucose treatment. RESULTS: Our study identified 2775 differentially expressed genes (DEGs) related to high glucose-triggered pathological changes, including 1164 upregulated and 1611 downregulated genes. Genome-wide DEGs and network analysis revealed enrichment in the epithelial-mesenchymal transition (EMT), inflammatory response, hypoxia, and TGF-beta pathways. The enriched genes included VEGFA, HIF-1α, TGF-ß1, EGF, TWIST2, and SNAI2. Using ATAC-seq, we identified 942 hyper (higher ATAC-seq signal in high glucose-treated HMrSV5 cells than in control cells) and 714 hypo (lower ATAC-seq signal in high glucose-treated HMrSV5 cells versus control cells) peaks with differential accessibility in high glucose-treated HMrSV5 cells versus controls. These differentially accessible regions were positively correlated (R = 0.934) with the nearest DEGs. These genes were associated with 566 up- and 398 downregulated genes, including SNAI2, TGF-ß1, HIF-1α, FGF2, VEGFA, and VEGFC, which are involved in critical pathways identified by transcriptome analysis. Integrated ATAC-seq and RNA-seq analysis also revealed key transcription factors (TFs), such as HIF-1α, ARNTL, ELF1, SMAD3 and XBP1. Importantly, we demonstrated that HIF-1α is involved in the regulation of several key genes associated with EMT and the TGF-beta pathway. Notably, we predicted and experimentally validated that HIF-1α can exacerbate the expression of TGF-ß1 in a high glucose-dependent manner, revealing a novel role of HIF-1α in high glucose-induced pathological changes in human peritoneal mesothelial cells (HPMCs). CONCLUSIONS: In summary, our study provides a comprehensive view of the role of transcriptome deregulation and chromosome accessibility alterations in high glucose-induced pathological fibrotic changes in HPMCs. This analysis identified hub genes, signaling pathways, and key transcription factors involved in peritoneal fibrosis and highlighted the novel glucose-dependent regulation of TGF-ß1 by HIF-1α. This integrated approach has offered a deeper understanding of the pathogenesis of peritoneal fibrosis and has indicated potential therapeutic targets for intervention.

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.

SPHK1/S1P/S1PR pathway promotes the progression of peritoneal fibrosis by mesothelial-mesenchymal transition.

Long-term exposure to non-physiologically compatible dialysate inevitably leads to peritoneal fibrosis (PF) in patients undergoing peritoneal dialysis (PD), and there is no effective prevention or treatment for PF. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid produced after catalysis by sphingosine kinase (SPHK) 1/2 and activates signals through the S1P receptor (S1PR) via autocrine or paracrine. However, the role of SPHK1/S1P/S1PR signaling has never been elucidated in PF. In our research, we investigated S1P levels in peritoneal effluents and demonstrated the role of SPHK1/S1P/S1PR pathway in peritoneal fibrosis. It was found that S1P levels in peritoneal effluents were positively correlated with D/P Cr (r = 0.724, p < .001) and negatively correlated with 4 h ultrafiltration volume (r = -0.457, p < .001). S1PR1 and S1PR3 on peritoneal cells were increased after high glucose exposure in vivo and in vitro. Fingolimod was applied to suppress S1P/S1PR pathway. Fingolimod restored mouse peritoneal function by reducing interstitial hyperplasia, maintaining ultrafiltration volume, reducing peritoneal transport solute rate, and mitigating the protein expression changes of fibronectin, vimentin, α-SMA, and E-cadherin induced by PD and S1P. Fingolimod preserved the morphology of the human peritoneal mesothelial cells, MeT-5A, and moderated the mesothelial-mesenchymal transition (MMT) process. We further delineated that SPHK1 was elevated in peritoneal cells after high glucose exposure and suppression of SPHK1 in MeT-5A cells reduced S1P release. Overexpression of SPHK1 in MeT-5A cells increased S1P levels in the supernatant and fostered the MMT process. PF-543 treatment, targeting SPHK1, alleviated deterioration of mouse peritoneal function. In conclusion, S1P levels in peritoneal effluent were correlated with the deterioration of peritoneal function. SPHK1/S1P/S1PR pathway played an important role in PF.

Omega-3 polyunsaturated fatty acids protect peritoneal mesothelial cells from hyperglycolysis and mesothelial-mesenchymal transition through the FFAR4/CaMKKß/AMPK/mTOR signaling pathway.

Peritoneal fibrosis is a severe clinical complication associated with peritoneal dialysis (PD) and impacts its efficacy and patient outcomes. The process of mesothelial-mesenchymal transition (MMT) in peritoneal mesothelial cells plays a pivotal role in fibrogenesis, whereas metabolic reprogramming, characterized by excessive glycolysis, is essential in MMT development. No reliable therapies are available despite substantial progress made in understanding the mechanisms underlying peritoneal fibrosis. Protective effect of omega-3 polyunsaturated fatty acids (ω3 PUFAs) has been described in PD-induced peritoneal fibrosis, although the detailed mechanisms remain unknown. It is known that ω3 PUFAs bind to and activate the free fatty acid receptor 4 (FFAR4). However, the expression and role of FFAR4 in the peritoneum have not been investigated. Thus, we hypothesized that ω3 PUFAs would alleviate peritoneal fibrosis by inhibiting hyperglycolysis and MMT through FFAR4 activation. First, we determined FFAR4 expression in peritoneal mesothelium in humans and mice. FFAR4 expression was abnormally decreased in patients on PD and mice and HMrSV5 mesothelial cells exposed to PD fluid (PDF); this change was restored by the ω3 PUFAs (EPA and DHA). ω3 PUFAs significantly inhibited peritoneal hyperglycolysis, MMT, and fibrosis in PDF-treated mice and HMrSV5 mesothelial cells; these changes induced by ω3 PUFAs were blunted by treatment with the FFAR4 antagonist AH7614 and FFAR4 siRNA. Additionally, ω3 PUFAs induced FFAR4, Ca2+/calmodulin-dependent protein kinase kinase ß (CaMKKß), and AMPK and suppressed mTOR, leading to the inhibition of hyperglycolysis, demonstrating that the ω3 PUFAs-mediated FFAR4 activation ameliorated peritoneal fibrosis by inhibiting hyperglycolysis and MMT via CaMKKß/AMPK/mTOR signaling. As natural FFAR4 agonists, ω3 PUFAs may be considered for the treatment of PD-associated peritoneal fibrosis.

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 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-1ß, 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 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.

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.

2-Deoxy-glucose ameliorates the peritoneal mesothelial and endothelial barrier function perturbation occurring due to Peritoneal Dialysis fluids exposure.

Peritoneal dialysis (PD) and prolonged exposure to PD fluids (PDF) induce peritoneal membrane (PM) fibrosis and hypervascularity, leading to functional PM degeneration. 2-deoxy-glucose (2-DG) has shown potential as PM antifibrotic by inhibiting hyper-glycolysis induced mesothelial-to-mesenchymal transition (MMT). We investigated whether administration of 2-DG with several PDF affects the permeability of mesothelial and endothelial barrier of the PM. The antifibrotic effect of 2-DG was confirmed by the gel contraction assay with embedded mesothelial (MeT-5A) or endothelial (EA.hy926) cells cultured in Dianeal® 2.5 % (CPDF), BicaVera® 2.3 % (BPDF), Balance® 2.3 % (LPDF) with/without 2-DG addition (0.2 mM), and qPCR for αSMA, CDH2 genes. Moreover, 2-DG effect was tested on the permeability of monolayers of mesothelial and endothelial cells by monitoring the transmembrane resistance (RTM), FITC-dextran (10, 70 kDa) diffusion and mRNA expression levels of CLDN-1 to -5, ZO1, SGLT1, and SGLT2 genes. Contractility of MeT-5A cells in CPDF/2-DG was decreased, accompanied by αSMA (0.17 ± 0.03) and CDH2 (2.92 ± 0.29) gene expression fold changes. Changes in αSMA, CDH2 were found in EA.hy926 cells, though αSMA also decreased under LPDF/2-DG incubation (0.42 ± 0.02). Overall, 2-DG mitigated the PDF-induced alterations in mesothelial and endothelial barrier function as shown by RTM, dextran transport and expression levels of the CLDN-1 to -5, ZO1, and SGLT2. Thus, supplementation of PDF with 2-DG not only reduces MMT but also improves functional permeability characteristics of the PM mesothelial and endothelial barrier.

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.

Novel Peritoneal Sclerosis Rat Model Developed by Administration of Bleomycin and Lansoprazole.

In our preliminary experiment, peritoneal sclerosis likely induced by peritoneal dialysis was unexpectedly observed in the livers of rats given bleomycin and lansoprazole. We examined whether this peritoneal thickening around the liver was time-dependently induced by administration of both drugs. Male Wistar rats were injected with bleomycin and/or lansoprazole for 2 or 4 weeks. The 3YB-1 cell line derived from rat fibroblasts was treated by bleomycin and/or lansoprazole for 24 h. The administration of both drugs together, but not individually, thickened the peritoneal tissue around the liver. There was accumulation of collagen fibers, macrophages, and eosinophils under mesothelial cells. Expressions of Col1a1, Mcp1 and Mcp3 genes were increased in the peritoneal tissue around the liver and in 3YB-1 cells by the administration of both drugs together, and Opn genes had increased expressions in this tissue and 3YB-1 cells. Mesothelial cells indicated immunoreactivity against both cytokeratin, a mesothelial cell marker, and αSMA, a fibroblast marker, around the livers of rats given both drugs. Administration of both drugs induced the migration of macrophages and eosinophils and induced fibrosis associated with the possible activation of fibroblasts and the possible promotion of the mesothelial-mesenchymal transition. This might become a novel model of peritoneal sclerosis for peritoneal dialysis.

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.