Long-term Peritoneal Dialysis Research Articles

Inhibition of Transglutaminase 2 Reduces Peritoneal Injury in a Chlorhexidine-Induced Peritoneal Fibrosis Model

Long-term peritoneal dialysis (PD) is often associated with peritoneal dysfunction leading to withdrawal from PD. The characteristic pathologic features of peritoneal dysfunction are widely attributed to peritoneal fibrosis and angiogenesis. The detailed mechanisms remain unclear, and treatment targets in clinical settings have yet to be identified. We investigated transglutaminase 2 (TG2) as a possible novel therapeutic target for peritoneal injury. TG2 and fibrosis, inflammation, and angiogenesis were investigated in a chlorhexidine gluconate (CG)-induced model of peritoneal inflammation and fibrosis, representing a noninfectious model of PD-related peritonitis. Transforming growth factor (TGF)-β type I receptor (TGFβR-I) inhibitor and TG2-knockout mice were used for TGF-β and TG2 inhibition studies, respectively. Double immunostaining was performed to identify cells expressing TG2 and endothelial-mesenchymal transition (EndMT). In the rat CG model of peritoneal fibrosis, in situ TG2 activity and protein expression increased during the development of peritoneal fibrosis, as well as increases in peritoneal thickness and numbers of blood vessels and macrophages. TGFβR-I inhibitor suppressed TG2 activity and protein expression, as well as peritoneal fibrosis and angiogenesis. TGF-β1 expression, peritoneal fibrosis, and angiogenesis were suppressed in TG2-knockout mice. TG2 activity was detected by α-smooth muscle actin-positive myofibroblasts, CD31-positive endothelial cells, and ED-1-positive macrophages. CD31-positive endothelial cells in the CG model were α-smooth muscle actin-positive, vimentin-positive, and vascular endothelial-cadherin-negative, suggesting EndMT. In the CG model, EndMT was suppressed in TG2-knockout mice. TG2 was involved in the interactive regulation of TGF-β. As inhibition of TG2 reduced peritoneal fibrosis, angiogenesis, and inflammation associated with TGF-β and vascular endothelial growth factor-A suppression, TG2 may provide a new therapeutic target for ameliorating peritoneal injuries in PD.

Restoration of CPT1A-mediated fatty acid oxidation in mesothelial cells protects against peritoneal fibrosis.

Background: Peritoneal dialysis (PD) is limited by gradual fibrotic remodeling in the peritoneum, a process involving profibrotic response of mesothelial cells. However, the role of fatty acid oxidation (FAO) and carnitine palmitoyltransferase 1A (CPT1A) in this process remains unexplored. Methods: FAO and CPT1A expression were characterized in mesothelial cells from patients on long-term PD and from a mouse model of PD using multiple experimental methods, including single-cell sequencing, seahorse assay, real-time quantitative PCR, Western blot, and immunofluorescence staining. Overexpression of CPT1A was achieved in a human mesothelial cell line and in primary mouse mesothelial cells. Finally, genetic and pharmacological manipulations of CPT1A were performed in a mouse model of PD. Results: Herein, FAO and CPT1A expression were reduced in mesothelial cells from patients on long-term PD, which negatively correlated with expression of fibrogenic markers in these cells. This was corroborated in PD mice, as well as in mouse and human mesothelial cells incubated with transforming growth factor (TGF) β1. CPT1A overexpression in mesothelial cells, which prevented TGFβ1-induced suppression of mitochondrial respiration, restored cellular ATP levels and downregulated the expression of fibrogenic markers. Furthermore, restoration of FAO by overexpressing CPT1A in PD mice reversed profibrotic phenotype in mesothelial cells and reduced fibrotic lesions in the peritoneum. Treatment with the CPT1A activator C75 induced similar therapeutic benefit in PD mice. In contrast, inhibition of FAO with a CPT1 inhibitor caused more severe fibrosis in PD mice. Conclusions: A defective FAO is responsible for the profibrotic response of mesothelial cells and thus the peritoneal fibrogenesis. This aberrant metabolic state could be improved by modulating CPT1A in mesothelial cells, suggesting FAO enhancement in mesothelial cells is a potential treatment of peritoneal fibrosis.

The probiotic Lactobacillus casei Zhang-mediated correction of gut dysbiosis ameliorates peritoneal fibrosis by suppressing macrophage-related inflammation via the butyrate/PPAR-γ/NF-κB pathway.

Peritoneal fibrosis is a complication of long-term peritoneal dialysis (PD) that restricts its clinical application for the treatment of end-stage renal disease. Lactobacillus casei Zhang (LCZ), a probiotic strain isolated from traditional fermented koumiss, exhibits health benefits such as anti-inflammatory and antioxidative effects, improvement of insulin resistance and mitigation of renal injury. However, whether LCZ can prevent peritoneal fibrosis remains unknown. Here, we assessed the effects of LCZ in a mouse model of PD-induced peritoneal fibrosis. Our results showed that the administration of LCZ significantly ameliorated peritoneal fibrosis in experimental mice. Macrophage infiltration, inflammatory M1 polarization and inflammatory cytokines in peritoneal dialysis effluents were effectively reduced by LCZ. Meanwhile, LCZ corrected gut dysbiosis and enriched beneficial bacteria that produce short-chain fatty acids, specifically Dubosiella, Lachnospiraceae, Parvibacter, and Butyricicoccus. Correspondingly, the local butyrate level in peritoneal dialysis effluents was significantly elevated by LCZ. Mechanistically, we found activation of PPARγ and inhibition of the NF-κB pathway in LCZ-treated mice, an observation that was replicated in a butyrate-treated macrophage cell line. In conclusion, our study suggests that LCZ is beneficial for preventing PD-induced peritoneal fibrosis through modulating the gut microbiota, enhancing butyrate production, activating PPARγ, and suppressing NF-κB-mediated inflammation.

Rapid Initiation of Peritoneal Dialysis by Automated Peritoneal Dialysis or Hemodialysis: A Randomized Clinical Trial

Introduction: It is still controversial whether automated peritoneal dialysis (APD) or hemodialysis (HD) is a more favorable choice for the rapid initiation of peritoneal dialysis (PD). Methods: A pilot randomized prospective controlled trial was carried out in Shanghai Ruijin Hospital. Sixty-seven patients who chose long-term PD treatment and needed unplanned dialysis were enrolled and randomized into HD-CAPD group (33 cases) or APD-CAPD group (34 cases) based on the dialysis modality during the transition period (within 14 days from the day PD catheter was implanted). Continuous ambulatory PD started after the transition period. The primary outcome was the decline rates of residual glomerular filtration rate (GFR). Secondary outcomes included the rates of mechanical complications, the rates of infectious complications, and complications of end-stage renal disease. Results: We found residual GFR decline was faster in HD-CAPD group than in APD-CAPD group (0.06 mL/min/w vs. 0.03 mL/min/w, p < 0.01). The incidences of mechanical complications were similar in APD-CAPD group comparing with HD-CAPD group, including hernia (2.9% vs. 3.0%, p = 1.00), catheter malposition (0.02 episodes/patient-months vs. 0.02 episodes/patient-months, p = 0.70), leakage (5.9% vs. 6.1%, p = 1.00), and omental wrap (0 episode vs. 3 episodes, p = 0.368). Though the 1-year overall infection rates were similar (0.03 episodes/patient-months vs. 0.05 episodes/patient-months, p = 0.10), APD-CAPD group had lower rate of bacteremia compared to HD-CAPD group (0 episodes/patient-months vs. 0.02 episodes/patient-months, p < 0.01). Conclusions: Both APD and HD could be used for patients who need to start dialysis in an unplanned manner. APD may have the advantage in protecting residual renal functions among these patients.

Inhibition of calpain9 attenuates peritoneal dialysis-related peritoneal fibrosis.

Aim: Peritoneal dialysis is a common renal replacement method for end-stage renal disease. Long-term peritoneal dialysis leads to peritoneal dialysis-related peritoneal fibrosis, which leads to a cessation of treatment. Calpain is a protein belonging to calcium-dependent endopeptidase family and plays an important role in extracellular matrix remodeling. Here, we evaluated the effect of calpain in peritoneal dialysis-related peritoneal fibrosis. Methods: We established two animal models of peritoneal fibrosis and inhibited the activity of Calpain, and then collected peritoneal tissue to evaluate the progress of fibrosis and the changes of Calpain and β-catenin. We obtained Rat peritoneal mesothelial cells and Human peritoneal mesothelial cell line and stimulated with TGF-β to produce extracellular matrix. Next we inhibited Calpain activity or reduced Calpain9 expression, and then assessed changes in extracellular matrix and β-catenin. Results: Inhibition of calpain activity attenuated chlorhexidine glucose and peritoneal dialysis-induced peritoneal thickening and β-catenin expression in mice. In addition, compared with the control group, when primary rat peritoneal mesothelial cells or human peritoneal mesothelial cells were treated with transforming growth factor beta, down-regulation of calpain activity inhibited the expression of Fibronectin and Collagen I, and increased the expression of E-cadherin. These changes could be adjusted after silencing calpain9. Finally, calpain9 deficiency was associated with down-regulation of Fibronectin and β-catenin in human peritoneal mesothelial cells. Conclusion: Our results suggest that calpain9 may be a key molecule in mediating peritoneal dialysis-related peritoneal fibrosis.

Endoglin aggravates peritoneal fibrosis by regulating the activation of TGF-β/ALK/Smads signaling.

Background: Peritoneal fibrosis (PF) is an intractable complication in patients on long-term peritoneal dialysis (PD). Transforming growth factor-β (TGF-β) is a key pro-fibrogenic factor involved in PD-associated PF, and endoglin, as a coreceptor for TGF-β, plays a role in balancing the TGF-β signaling pathway. Here, we investigated whether endoglin could be a potential therapeutic target for PF. Methods: In vivo, we established PF model in SD rats by daily intraperitoneal injection of peritoneal dialysis fluids (PDF) containing 4.25% glucose for 6 weeks and downregulated endoglin expression by tail vein injection of AAV9-ENG on day 14 to assess the effect of endoglin on peritoneal morphology and markers related to fibrosis, angiogenesis, and epithelial-mesenchymal transition (EMT). In vitro, we treated human peritoneal mesothelial cells (HPMCs) transfected with ENG siRNA in high glucose medium to explore the potential mechanism of endoglin in PF. Results: Compared to control group, continuous exposure to biologically incompatible PDF induced exacerbated PF, accompanied by a significant increase in endoglin expression. Conversely, knockdown of endoglin ameliorated peritoneal injury characterized by increased peritoneal thickening and collagen deposition, angiogenesis, as well as EMT. Consistently, HPMCs cultured in high glucose medium underwent the EMT process and exhibited over-expression of fibronectin, collagen type I, vascular endothelial growth factor (VEGF), whereas these aforementioned alterations were alleviated after ENG siRNA transfection. In addition, we also found that ENG siRNA inhibited TGF-β-induced phosphorylation of Smad2/3 and Smad1/5/9 in HPMCs treated with high glucose (HG). Conclusion: Our findings confirmed for the first time that endoglin exacerbated PF by regulating the activation of TGF-β/ALK/Smads signaling, which will provide a novel potential therapeutic target in PF.

Crocin ameliorates peritoneal fibrosis in rat induced by peritoneal dialysis via Wnt5a/β-Catenin pathway

Peritoneal dialysis is used in the treatment of patients with kidney diseases. Long-term peritoneal dialysis could result in peritoneal fibrosis and recurrent peritonitis, thus leading to failure of ultrafiltration. Crocin is a bioactive carotenoid and isolated from stigma of Crocus sativus, and ameliorates pulmonary and myocardial fibrosis. The role of crocin in peritoneal fibrosis was assessed. Firstly, rats model with peritoneal dialysis was treated with 4.25% peritoneal dialysate. Results showed that injection with peritoneal dialysate induced obvious hyperplasia and increased thickness in peritoneum structure. Rats with peritoneal dialysis were injected with increasing concentrations of crocin at 10, 20, or 40 mg/kg. Crocin ameliorated the pathological changes in the peritoneum of peritoneal dialysate-induced rats. Secondly, crocin attenuated peritoneal dialysate-induced decrease of E-cadherin, increase of fibronectin, α-smooth muscle actin (α-SMA), and collagen I. Moreover, crocin enhanced ultrafiltration volume and reduced glucose transport in rats model with peritoneal dialysis. Thirdly, crocin also reduced levels of Interleukin (IL)-1β, Tumor Necrosis Factor-α (TNF –α), and IL-6 in peritoneal tissues of rats model with peritoneal dialysis. Lastly, protein expression of Wnt5a and β-Catenin in rats model with peritoneal dialysis were also downregulated by crocin. In conclusion, crocin exerted anti-inflammatory and anti-fibrotic effects on rats model with peritoneal dialysis through inactivation of Wnt5a/β-Catenin pathway.

Differentially Expressed microRNAs in Peritoneal Dialysis Effluent-Derived Exosomes from the Patients with Ultrafiltration Failure.

Background Ultrafiltration failure remains one of the most severe complications of long-term peritoneal dialysis (PD), which results in death. This study aimed to characterize the circulating exosomal microRNA (miRNA) profiles associated with ultrafiltration failure and explore its underlying mechanisms. Methods Exosomes were isolated from the peritoneal dialysis effluent (PDE) of patients with ultrafiltration failure or success using the ultracentrifugation method, and then transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot were used for exosome characterization. After that, the isolated exosomes were sent for small RNA sequencing, and eight differentially expressed miRNAs (DE-miRNAs) were chosen for RT-qPCR validation. Results TEM, NTA, and western blot revealed that exosomes were successfully isolated. After sequencing, 70 DE-miRNAs involved in ultrafiltration were identified, including 41 upregulated ones and 29 downregulated ones. Functional analyses revealed that these DE-miRNAs were significantly enriched in pathways of cancer, ubiquitin-mediated proteolysis, axon orientation, and the Rap1 and Ras signaling pathways. In addition, the consistency rate of RT-qPCR and sequencing results was 75%, which indicated the relatively high reliability of the sequencing data. Conclusions Our findings implied that these DE-miRNAs may be potential biomarkers of ultrafiltration failure, which would help us to discover novel therapeutic targets/pathways for ultrafiltration failure in patients with end-stage renal disease.

Inhibition of EZH2 suppresses peritoneal angiogenesis by targeting a VEGFR2/ERK1/2/HIF-1α-dependent signaling pathway.

The catalytic subunit of polycomb repressive complex 2 (PRC2), enhancer of zeste homolog 2 (EZH2), has been reported to be involved in angiogenesis in some tumors and autoimmune diseases. However, the mechanisms by which EZH2 regulates peritoneal angiogenesis remain unclear. We detected the expression of EZH2 in clinical samples and the peritoneal tissue of a mouse peritoneal fibrosis model induced by chlorhexidine gluconate (CG). In addition, we further investigated the mechanisms by which inhibition of EZH2 by 3-deazaneplanocin A (3-DZNeP) alleviated the CG-induced peritoneal fibrosis mouse model in vivo and 3-DZNeP or EZH2 siRNA treatment in cultured human peritoneal mesothelial cells (HPMCs) and human umbilical vein endothelial cells (HUVECs). The expression of EZH2 in the peritoneum of long-term peritoneal dialysis (PD) patients and the CG-induced peritoneal fibrosis mouse model was remarkably increased and this was positively associated with higher expression of vascular markers (CD31, CD34, VEGF, p-VEGFR2). Peritoneal injection of 3-DZNeP attenuated angiogenesis in the peritoneum of CG-injured mice; improved peritoneal membrane function; and decreased phosphorylation of STAT3, ERK1/2, and activation of Wnt1/β-catenin. In in vitro experiments, we demonstrated that inhibition of EZH2 by 3-DZNeP or EZH2 siRNA decreased tube formation and the migratory ability of HUVECs via two pathways: the Wnt1/β-catenin pathway and the IL-6/STAT3 pathway. Suppression of the Wnt1/β-catenin pathway and the IL-6/STAT3 pathway subsequently reduced VEGF production in HPMCs. Using specific inhibitors of VEGFR2, ERK1/2, and HIF-1α, we found that a VEGFR2/ERK1/2/HIF-1α axis existed and contributed to angiogenesis in vitro. Moreover, phosphorylation of VEGFR2 and activation of the ERK1/2 pathway and HIF-1α in HUVECs could be suppressed by inhibition of EZH2. Taken together, the results of this study suggest that EZH2 may be a novel target for preventing peritoneal angiogenesis in PD patients. © 2022 The Pathological Society of Great Britain and Ireland.

Prevalence and outcome of abdominal wall hernia in patients with end-stage renal disease on peritoneal dialysis.

We aimed to study the prevalence, risk factors, management, and outcome of hernias in end-stage renal disease (ESRD) patients on peritoneal dialysis (PD) from India. This was a retrospective study of ESRD-PD patients who developed hernias over 11 years. Of 470 PD patients, 21 developed hernias (4.2%). Mean age of patients was 49.9 ± 15.36 years; 15 (66.66%) were males; 18 (85.71%) patients had umbilical hernia, 3 (14.28%) had inguinal hernia. Continuous ambulatory PD (CAPD) versus automated PD (APD) (OR: 11.623, 95% CI: 2.060-65.581, p=0.005) was the independent risk factor identified. Incarcerated umbilical/inguinal hernia was managed surgically (6 [28.57%]); uncomplicated umbilical hernia (15 [71.42%]) managed conservatively (shift to (APD) [33.33%]; switch to low-volume APD [20%], switch to low-volume CAPD [46.66%]). None had postoperative hernia recurrences; 4 (19%) had PD technique failure; median PD survival was 36 (IQR 17-55) months. Although complicated hernias in PD require surgical repair, uncomplicated umbilical hernias can be managed conservatively by switching to APD/low-volume CAPD, with good long-term PD technique survival.

Relative Contributions of Pseudohypoxia and Inflammation to Peritoneal Alterations with Long-Term Peritoneal Dialysis Patients.

Long-term peritoneal dialysis is associated with alterations in peritoneal function, like the development of high small solute transfer rates and impaired ultrafiltration. Also, morphologic changes can develop, the most prominent being loss of mesothelium, vasculopathy, and interstitial fibrosis. Current research suggests peritoneal inflammation as the driving force for these alterations. In this review, the available evidence for inflammation is examined and a new hypothesis is put forward consisting of high glucose-induced pseudohypoxia. Hypoxia of cells is characterized by a high (oxidized-reduced nicotinamide dinucleotide ratio) NADH-NAD+ ratio in their cytosol. Pseudohypoxia is similar but occurs when excessive amounts of glucose are metabolized, as is the case for peritoneal interstitial cells in peritoneal dialysis. The glucose-induced high NADH-NAD+ ratio upregulates the hypoxia-inducible factor-1 gene, which stimulates not only the glucose transporter-1 gene but also many profibrotic genes like TGFβ, vascular endothelial growth factor, plasminogen activator inhibitor-1, and connective tissue growth factor, all known to be involved in the development of peritoneal fibrosis. This review discusses the causes and consequences of pseudohypoxia in peritoneal dialysis and the available options for treatment and prevention. Reducing peritoneal exposure to the excessively high dialysate glucose load is the cornerstone to avoid the pseudohypoxia-induced alterations. This can partly be done by the use of icodextrin or by combinations of low molecular mass osmotic agents, all in a low dose. The addition of alanyl-glutamine to the dialysis solution needs further clinical investigation.

Prevalence of Apparent Treatment-Resistant Hypertension in ESKD Patients Receiving Peritoneal Dialysis.

Apparent treatment-resistant hypertension (aTRH) is defined as failure to achieve adequate blood pressure (BP) control despite taking ≥3 antihypertensive medications from different categories or when taking ≥4 antihypertensives regardless of BP levels. In this cross-sectional study, we estimated the prevalence of aTRH in 140 patients receiving long-term peritoneal dialysis (PD) in four centers of Northern Greece, using the "gold-standard" method of ambulatory BP monitoring for the assessment of BP control status. The presence of subclinical overhydration was evaluated with the method of bioimpedance spectroscopy (BIS). Incorporating the diagnostic threshold of 130/80 mmHg for 24-hour ambulatory BP, the prevalence of aTRH in the overall study population was 30%. Compared to patients without aTRH, those with aTRH tended to be older in age, had higher PD vintage, had higher dialysate-to-plasma creatinine ratio, had more commonly history of diabetes mellitus, and were more commonly current smokers. With respect to the volume status, the overhydration index in BIS was higher in those with versus without aTRH (2.0 ± 1.9 L vs. 1.1 ± 2.0 L, P < 0.05). The prevalence of volume overload, defined as an overhydration index in BIS > 2.5 L, was also higher in the subgroup of patients with aTRH (38.1% vs. 18.4, P = 0.01). The present study showed that among patients on PD, the prevalence of aTRH was 30%. However, 38% of PD patients with aTRH had subclinical overhydration in BIS, suggesting that the achievement of adequate volume control may be a therapeutic opportunity to improve the management of hypertension in this high-risk patient population.The present study showed that among patients on PD, the prevalence of aTRH was 30%. However, 38% of PD patients with aTRH had subclinical overhydration in BIS, suggesting that the achievement of adequate volume control may be a therapeutic opportunity to improve the management of hypertension in this high-risk patient population. Trial Number NCT03607747.

Peritonitis as the Cause of Death of CAPD Patients at RSUD Dr. Saiful Anwar Malang 2014-2020

Background: Continuous Ambulatory Peritoneal Dialysis (CAPD) is an effective modality of renal replacement therapy in patients with kidney failure. Peritonitis associated with peritoneal dialysis remains a significant challenge and complication to success long-term peritoneal dialysis. Aim: This study aims to report the peritonitis as a cause of death of CAPD patients for six years in end-stage renal failure (ESRD) patients at RSUD Dr. Saiful Anwar Malang. Methods: A descriptive study was conducted involving 40 patients with end-stage renal failure who underwent CAPD therapy with peritonitis as the cause of patient mortality by taking data from the CAPD Center medical record at RSUD Dr. Saiful Anwar from August 2014 to July 2020. Results: From 674 end-stage renal failure patients who underwent CAPD, 248 patients (36.8%) died, and 426 patients (63.2%) survived to 5 years. CAPD peritonitis is the second most common cause of 40 (16.1%) mortality cases after cardiovascular disease. The most common bacteria causing CAPD peritonitis was coagulate-negative Staphylococcus, with as many as 15 (37.5%) cases. Conclusion: the most common cause of mortality was Staphylococcus coagulase-negative (37.5 %,), a bacteria that come from touch contamination or infection at the exit site. So that patients and caregivers must be trained to carry out proper exit-site, and it is essential to maintain good hand hygiene before performing exit-site. Appropriate prevention and management of peritonitis are critical to patients' long-term success on peritoneal dialysis.

Use of paclitaxel carried in solid lipid nanoparticles to prevent peritoneal fibrosis in rats.

Progressive fibrous thickening of peritoneal membrane (PM) is a major complication of long-term peritoneal dialysis. TGF-β/SMAD pathway activation, inflammation and neoangiogenesis have an important role in PM changes induced by peritoneal dialysis. Here, we investigated the effects of paclitaxel (PTX) carried in lipid core nanoparticles (LDE) on the development of peritoneal fibrosis (PF) in rats. To induce PF, 21 male Wistar rats (300-350g) were injected with chlorhexidine gluconate for 15 consecutive days and randomly assigned to three groups: 1)PF, n = 5: no treatment; 2)LDE, n = 8: treated with LDE only, 3/3 days during 15 days; 3)LDE-PTX, n = 8: treated with PTX (4mg/kg) associated with LDE, 3/3 days during 15 days. A Control group without PF induction (n = 5) was designed, received saline solution, 3/3 days. Peritoneum function tests were performed, and anterior abdominal wall samples of the PM were collected for analyses of peritoneal thickness, immunohistochemitry, and gene expression. LDE-PTX treatment preserved the membrane function, maintaining the ultrafiltration rate and mass transfer of glucose at normal levels. LDE-PTX also prevented PM thickening induced by chlorhexidine gluconate injections. LDE-PTX treatment reduced the number of myofibroblasts infiltrating PM and inhibited the cell proliferation. Gene expression of fibronectin, FSP-1, VEGF, TGF-β, and SMAD3 were reduced by LDE-PTX. LDE-PTX was effective to prevent development of PF and preserve the PM filtration capacity in this rat model, with clear-cut actions on pro-fibrotic mechanisms. Thus, LDE-PTX can be candidate for future clinical trials as adjuvant to peritoneal dialysis to prevent PF development, since this preparation is devoid of toxicity as shown previously.

MO705: Factors Associated with Uncontrolled Ambulatory Hypertension in Peritoneal Dialysis Patients

Abstract BACKGROUND AND AIMS Hypertension among patients on long-term peritoneal dialysis (PD) is common and remains often inadequately control (Cocchi et al. Prevalence of hypertension in patients on peritoneal dialysis: results of an Italian multicentre study. Nephrol Dial Transplant. 1999; 14(6): 1536–40; Vaios et al.. Assessment and management of hypertension among patients on peritoneal dialysis. Clin J Am Soc Nephrol. 2019; 14(2): 297–305). The aim of the present study was to describe the epidemiology of hypertension using the ‘gold-standard’ method of ambulatory blood pressure monitoring (ABPM) and to identify determinants of inadequate ambulatory blood pressure (BP) control in this high-risk population. METHOD In 140 stable patients receiving PD in four centers of Northern Greece, we performed 24-h ABPM using the oscillometric Mobil-O-Graph device (IEM, Stolberg Germany) (Franssen and Imholz. Evaluation of the Mobil-O-Graph new generation ABPM device using the ESH criteria. Blood Press Monit. 2010; 15(4): 229–31). Hypertension was defined as 24-h ambulatory BP ≥ 130/80 mmHg or current use of at least 1 BP-lowering medication (Williams et al. 2018 ESC/ESH guidelines for the management of arterial hypertension: the Task Force for the Management of Arterial Hypertension of the European Society of Cardiology and the European Society of Hypertension. J Hypertens. 2018; 36(10): 1953–2041). The volume status of study participants was assessed with the method of bioimpedance spectroscopy (Fresenius Medical Care, Bad Homburg, Germany). Univariate and multivariate binary logistic regression analysis was performed to identify factors that were independently associated with uncontrolled ambulatory hypertension. RESULTS Ambulatory hypertension was diagnosed in 95% of the patients enrolled in the study. Despite the fact that 96.9% of hypertensives were being treated with an average of 2.4 BP-lowering medications daily, adequate control of 24-h ambulatory BP was achieved in only 38.3% of them. In univariate regression analysis, there was a significant interaction of uncontrolled ambulatory hypertension with the mode of PD, history of cardiovascular disease and smoking status. In multivariate analysis, among variables inserted in the model, the higher overhydration index in bioimpedance spectroscopy [odds ratio (OR): 1.308; 95% confidence interval (CI): 1.023–1.673/L higher overhydration] and the history of cardiovascular disease (OR: 3.069; 95% CI: 1.157–8.140) were the two factors that were associated with higher odds of uncontrolled ambulatory hypertension. In contrast, the presence of residual diuresis ≥ 0.5 L/24 h (OR: 0.304; 95% CI: 0.105–0.881) was the only parameter associated with lower odds of inadequate ambulatory BP control. CONCLUSION Among patients on PD, ambulatory hypertension is highly prevalent and remains often poorly controlled, despite the extensive use of antihypertensive drug therapy. Achievement of adequate volume control and long-term preservation of residual kidney function appear to be two attractive non-pharmacological strategies for optimization of the management of hypertension in this high-risk population.

Astragaloside IV Alleviates Intestinal Barrier Dysfunction via the AKT-GSK3β-β-Catenin Pathway in Peritoneal Dialysis.

Background and aims: Long-term peritoneal dialysis (PD) causes intestinal dysfunction, including constipation, diarrhea, or enteric peritonitis. However, the etiology and pathogenesis of these complications are still unclear and there are no specific drugs available in the clinic. This study aims to determine whether Astragaloside IV (AS IV) has therapeutic value on PD-induced intestinal epithelial barrier dysfunction in vivo and in vitro. Methods: We established two different long-term PD treatment mice models by intraperitoneally injecting 4.25% dextrose-containing peritoneal dialysis fluid (PDF) in uremia mice and normal mice, which were served as controls. In addition, PDF was applied to T84 cells in vitro. The therapeutic effects of AS IV on PD-induced intestinal dysfunction were then examined by histopathological staining, transmission electron microscopy, western blotting, and reverse transcription polymerase chain reaction. The protein levels of protein kinase B (AKT), glycogen synthase kinase 3β (GSK-3β) and β-catenin were examined after administration of AS IV. Results: In the present study, AS IV maintained the intestinal crypt, microvilli and desmosome structures in an orderly arrangement and improved intestinal epithelial permeability with the up-regulation of tight junction proteins in vivo. Furthermore, AS IV protected T84 cells from PD-induced damage by improving cell viability, promoting wound healing, and increasing the expression of tight junction proteins. Additionally, AS IV treatment significantly increased the levels of phosphorylation of AKT, inhibited the activity GSK-3β, and ultimately resulted in the nuclear translocation and accumulation of β-catenin. Conclusion: These findings provide novel insight into the AS IV-mediated protection of the intestinal epithelial barrier from damage via the AKT-GSK3β-β-catenin signal axis during peritoneal dialysis.

Aging of the Peritoneal Dialysis Membrane.

Long-term peritoneal dialysis as currently performed, causes structural and functional alterations of the peritoneal dialysis membrane. This decay is brought about by the continuous exposure to commercially available glucose-based dialysis solutions. This review summarizes our knowledge on the peritoneum in the initial phase of PD, during the first 2 years and the alterations in function and morphology in long-term PD patients. The pseudohypoxia hypothesis is discussed and how this glucose-induced condition can be used to explain all peritoneal alterations in long-term PD patients. Special attention is paid to the upregulation of hypoxia inducing factor-1 and the subsequent stimulation of the genes coding for glucose transporter-1 (GLUT-1) and the growth factors transforming growth factor-β (TGFβ), vascular endothelial growth factor (VEGF), plasminogen growth factor activator inhibitor-1 (PAI-1) and connective tissue growth factor (CTGF). It is argued that increased pseudohypoxia-induced expression of GLUT-1 in interstitial fibroblasts is the key factor in a vicious circle that augments ultrafiltration failure. The practical use of the protein transcripts of the upregulated growth factors in peritoneal dialysis effluent is considered. The available and developing options for prevention and treatment are examined. It is concluded that low glucose degradation products/neutral pH, bicarbonate buffered solutions with a combination of various osmotic agents all in low concentration, are currently the best achievable options, while other accompanying measures like the use of RAAS inhibitors and tamoxifen may be valuable. Emerging developments include the addition of alanyl glutamine to the dialysis solution and perhaps the use of nicotinamide mononucleotide, available as nutritional supplement.

Oxidative Stress-Induced Alterations of Cellular Localization and Expression of Aquaporin 1 Lead to Defected Water Transport upon Peritoneal Fibrosis.

Being one of the renal replacement therapies, peritoneal dialysis (PD) maintains around 15% of end-stage kidney disease patients’ lives; however, complications such as peritoneal fibrosis and ultrafiltration failure during long-term PD compromise its application. Previously, we established a sodium hypochlorite (NaClO)-induced peritoneal fibrosis porcine model, which helped to bridge the rodent model toward pre-clinical human peritoneal fibrosis research. In this study, the peritoneal equilibration test (PET) was established to evaluate instant functional changes in the peritoneum in the pig model. Similar to observations from long-term PD patients, increasing small solutes transport and loss of sodium sieving were observed. Mechanistic investigation from both in vivo and in vitro data suggested that disruption of cytoskeleton induced by excessive reactive oxygen species defected intracellular transport of aquaporin 1, this likely resulted in the disappearance of sodium sieving upon PET. Functional interference of aquaporin 1 on free water transport would result in PD failure in patients.

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

Encapsulating Peritoneal Sclerosis (EPS) is the most serious complication of long-term peritoneal dialysis (PD), which considerably reduces the patient's quality of life, leading to patients discontinuing PD. Considering these negative effects, it is necessary to systematically review and determine the risk factors of EPS. The PubMed, Embase, Web of Science, Cochrane Library, and China Biology Medicine (CBM) were searched from their inception to January 1st, 2022, and the bibliographies from the citations of relevant articles were manually searched. The ROBINS-I (Risk of Bias in Non-randomized studies of Interventions) tool was used to evaluate the risk of bias of included studies. Ten studies involving 12595 participants were included in this meta-analysis. The results revealed that a younger age at PD onset (MD = -7.70, 95% CI, -11.53~-3.86), a higher transporter (MD = 0.13, 95% CI, 0.09~0.18), a longer PD duration (SMD = 1.15, 95% CI, 0.68~1.61), a longer peritonitis duration (MD = 12.66, 95% CI, 3.85~21.47), and history of glomerulonephritis (OR = 1.42, 95% CI, 1.02~1.97) were significant risk factors for EPS. However, sex, use of icodextrin, the number of peritonitis episodes, and history of multicystic kidney disease did not affect the risk of EPS. This review provides a scientific basis for further understanding the etiology of PD-related EPS and improving prevention strategies. More high-quality studies are necessary to validate this paper's findings.

Inhibition of PI3K/AKT/mTOR Signalling Pathway Activates Autophagy and Suppresses Peritoneal Fibrosis in the Process of Peritoneal Dialysis.

Peritoneal dialysis (PD) is an important part of replacement therapy for kidney failure. However, long-term PD treatment can cause peritoneal fibrosis. Autophagy may be involved in the pathological mechanism of peritoneal fibrosis (PF). Although autophagy is currently known to be involved in course of PF, its specific effects still lack in-depth research. In this experiment, a high-glucose (HG)-induced peritoneal fibrosis rat model was successfully established via intraperitoneal injection of HG peritoneal dialysate, and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and the mechanistic target of rapamycin (mTOR) inhibitor rapamycin were used to treat peritoneal fibrosis rats. In addition, in vitro studies of high glucose-induced peritoneal fibrosis were performed using rat peritoneal mesothelial cells (PMCs). In vivo and in vitro experiments showed that LY294002 and rapamycin effectively inhibited the process of PF induced by high glucose. In addition, LY294002 and rapamycin were found to alleviate fibrosis by eliminating intracellular reactive oxygen species (ROS) levels, promoting the expression of the epithelial mesenchymal transdifferentiation proteins zonula occludens-1 (ZO-1) and E-cadherin, and inhibiting the expression of p-PI3K, PI3K, p-mTOR, mTOR, the fibroblast-specific proteins ferroptosis suppressor protein 1 (FSP1), and alpha-smooth muscle actin (α-SMA). Moreover, LY294002 and rapamycin promoted expression of autophagy-related proteins LC3-II/I, p62, and beclin-1. The current data indicated that inhibition of PI3K/AKT/mTOR signalling pathway activated autophagy and suppressed PF in the process of PD. Therefore, intervention in this signalling pathway may become a research goal for the prevention and treatment of PF, which has important clinical significance.