Recent advances in the management of peritoneal dialysis patients

Comprehensive cell surface protein profiling of human mesenchymal stromal cells from peritoneal dialysis effluent and comparison with those from human bone marrow and adipose tissue

Peritoneal mesenchymal stromal cells (pMSCs) are isolated from peritoneal dialysis (PD) effluent, and treatment with the pMSCs reduces peritoneal membrane injury in rat model of PD. This study was designed to verify the identity of the pMSCs. pMSCs were grown in plastic dishes for 4-7 passages, and their cell surface phenotype was examined by staining with a panel of 242 antibodies. The positive stain of each target protein was determined by an increase in fluorescence intensity as compared with isotype controls in flow cytometrical analysis. Here, we showed that pMSCs predominantly expressed CD9, CD26, CD29, CD42a, CD44, CD46, CD47, CD49b, CD49c, CD49e, CD54, CD55, CD57, CD59, CD63, CD71, CD73, CD81, CD90, CD98, CD147, CD151, CD200, CD201, β2-micoglobulin, epithelial growth factor receptor, human leukocyte antigen (HLA) class 1, and, to a lesser extent, CD31, CD45RO, CD49a, CD49f, CD50, CD58, CD61, CD105, CD164, and CD166. These cells lacked expression of most hematopoietic markers such as CD11b, CD14, CD19, CD34, CD40, CD80, CD79, CD86, and HLA-DR. There was 38.55% difference in the expression of 83 surface proteins between bone marrow (BM)-derived MSCs and pMSCs, and 14.1% in the expression of 242 proteins between adipose tissue (AT)-derived MSCs and pMSCs. The BM-MSCs but not both AT-MSCs and pMSCs express cytokine receptors (IFNγR, TNFI/IIR, IL-1R, IL-4R, IL-6R, and IL-7R). In conclusion, pMSCs exhibited a typical cell surface phenotype of MSCs, which was not the same as on BM-MSCs or AT-MSCs, suggesting that the pMSCs may represent a different MSC lineage from peritoneal cavity.

Relationship between serum iPTH and peritonitis episodes in patients undergoing continuous ambulatory peritoneal dialysis

BACKGROUND

Peritonitis is considered as one of the most serious complications that cause hospitalization in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). There is limited evidence on the impact of the parathyroid hormone (PTH) on the first peritoneal dialysis (PD)-associated peritonitis episode. We aimed to investigate the influence of serum intact parathyroid hormone (iPTH) on peritonitis in patients undergoing PD.

METHODS

This was a retrospective cohort study. Patients undergoing initial CAPD from a single center in China were enrolled. The baseline characteristics and clinical information were recorded. The primary outcome of interest was the occurrence of the first PD-associated peritonitis episode. Five Cox proportional hazard models were constructed in each group set. In group set 1, all participants were divided into three subgroups by tertiles of the serum concentration of iPTH; in group set 2, all participants were divided into three subgroups based on the serum concentration of iPTH with 150 pg/ml interval (<150, 150-300, and >300 pg/ml). Hazard ratios and 95% confidence intervals (CIs) were calculated for each model. The multivariate linear regression analysis elimination procedure assessed the association between the clinical characteristics at baseline and the iPTH levels. Restricted cubic spline models were constructed, and stratified analyses were also conducted.

RESULTS

A total of 582 patients undergoing initial PD (40% women; mean age, 45.1 ± 11.5 years) from a single center in China were recruited. The median follow-up duration was 25.3 months. Multivariate Cox regression analysis showed that, in the fully adjusted model, a higher serum iPTH level (tertile 3, iPTH >300 pg/ml) was significantly associated with a higher risk of PD-associated peritonitis at 3 years [tertile 3: hazard ratio (HR) = 1.53, 95%CI = 1.03-2.55, p = 0.03; iPTH > 300 pg/ml: HR = 1.57, 95%CI = 1.08-2.27, p = 0.02]. The hazard ratio for every 100 pg/ml increase in serum iPTH level was 1.12 (95%CI = 1.05-1.20, p < 0.01) in the total cohort when treating iPTH as a continuous variable.

CONCLUSIONS

An elevated iPTH level was significantly associated with an increased risk of peritonitis in patients undergoing CAPD.

The future of the artificial kidney

End-stage renal disease (ESRD) is increasing worldwide. In India, diabetes mellitus and hypertension are the leading causes of chronic kidney disease and ESRD. Hemodialysis is the most prevalent renal replacement therapy (RRT) in India. The ideal RRT must mimic the complex structure of the human kidney while maintaining the patient's quality of life. The quest for finding the ideal RRT, the “artificial kidney”– that can be replicated in the clinical setting and scaled-up across barriers– continues to this date. This review aims to outline the developments, the current status of the artificial kidney and explore its future potential.

Genetic or pharmacologic blockade of enhancer of zeste homolog 2 inhibits the progression of peritoneal fibrosis

Dysregulation of histone methyltransferase enhancer of zeste homolog 2 (EZH2) has been implicated in the pathogenesis of many cancers. However, the role of EZH2 in peritoneal fibrosis remains unknown. We investigated EZH2 expression in peritoneal dialysis (PD) patients and assessed its role in peritoneal fibrosis in cultured human peritoneal mesothelial cells (HPMCs) and murine models of peritoneal fibrosis induced by chlorhexidine gluconate (CG) or high glucose peritoneal dialysis fluid (PDF) by using 3-deazaneplanocin A (3-DZNeP), and EZH2 conditional knockout mice. An abundance of EZH2 was detected in the peritoneum of patients with PD associated peritonitis and the dialysis effluent of long-term PD patients, which was positively correlated with expression of TGF-β1, vascular endothelial growth factor, and IL-6. EZH2 was found highly expressed in the peritoneum of mice following injury by CG or PDF. In both mouse models, treatment with 3-DZNeP attenuated peritoneal fibrosis and inhibited activation of several profibrotic signaling pathways, including TGF-β1/Smad3, Notch1, epidermal growth factor receptor and Src. EZH2 inhibition also inhibited STAT3 and nuclear factor-κB phosphorylation, and reduced lymphocyte and macrophage infiltration and angiogenesis in the injured peritoneum. 3-DZNeP effectively improved high glucose PDF-associated peritoneal dysfunction by decreasing the dialysate-to-plasma ratio of blood urea nitrogen and increasing the ratio of dialysate glucose at 2 h after PDF injection to initial dialysate glucose. Moreover, delayed administration of 3-DZNeP inhibited peritoneal fibrosis progression, reversed established peritoneal fibrosis and reduced expression of tissue inhibitor of metalloproteinase 2, and matrix metalloproteinase-2 and -9. Finally, EZH2-KO mice exhibited less peritoneal fibrosis than EZH2-WT mice. In HPMCs, treatment with EZH2 siRNA or 3-DZNeP suppressed TGF-β1-induced upregulation of α-SMA and Collagen I and preserved E-cadherin. These results indicate that EZH2 is a key epigenetic regulator that promotes peritoneal fibrosis. Targeting EZH2 may have the potential to prevent and treat peritoneal fibrosis. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Use of Toll-like receptor assays for the detection of bacterial contaminations in icodextrin batches released for peritoneal dialysis

•

Monocyte test assays were poorly efficient for the detection of little bacterial contamination in icodextrin batches.

•

TLR2- and TLR4-transfected cell lines were appropriate for detecting PGN and LPS contaminations.

•

Mutanolysin treatment of icodextrins enhanced the response of TLR2-transfected cells to contaminating PGN.

•

Using TLR-transfected cell lines is a valuable approach for selecting icodextrin batches for peritoneal dialysis solutions.

Icodextrin is a starch derivative used for preparing solutions of peritoneal dialysis. Unfortunately, peptidoglycans (PGN) and lipopolysaccharides (LPS) have been reported to contaminate certain icodextrin batches and to contribute to the development of sterile peritonitis. The decision of selecting or rejecting icodextrin batches is however difficult, because of limitations in the detection of these bacterial contaminants. Besides monocyte activation tests of cytokine release, a number of bio-assays using stably TLR-transfected cell lines have been developed. Here, we compared the efficacy of TLR2- and TLR4-transfected cells to detect bacterial contamination with the responses of monocytes exposed to the same icodextrin samples. In contrast to monocyte models of cytokine release, we found that TLR2- and TLR4-transfected cell lines are highly sensitive to detect little PGN and LPS contaminations in the presence of icodextrin. With the intent to increase PGN reactivity, mutanolysin was used to generate soluble fragments in icodextrin samples. We found that such an enzymatic treatment led to an enhanced response of TLR2-transfected cells, even though parental icodextrin samples were poorly reactive. Altogether, these findings indicate that the use of TLR2- and TLR4-transfected cell lines is a valuable approach for helping to the decision of selecting icodextrin batches for peritoneal dialysis.