Soluble Tie2 fusion protein decreases peritoneal angiogenesis in uremic rats

Biocompatible Peritoneal Dialysis: The Target Is Still Way Off

Peritoneal dialysis (PD) is a cost-effective, home-based therapy for patients with end-stage renal disease achieving similar outcome as compared to hemodialysis. Still, a minority of patients only receive PD. To a significant extend, this discrepancy is explained by major limitations regarding PD efficiency and sustainability. Due to highly unphysiological composition of PD fluids, the peritoneal membrane undergoes rapid morphological and long-term functional alterations, which limit the treatment and contribute to adverse patient outcome. This review is focused on the peritoneal membrane ultrastructure and its transformation in patients with kidney disease and chronic PD, underlying molecular mechanisms, and potential systemic sequelae. Current knowledge on the impact of conventional and second-generation PD fluids is described; novel strategies and innovative PD fluid types are discussed.

Strategies for preventing peritoneal fibrosis in peritoneal dialysis patients: new insights based on peritoneal inflammation and angiogenesis

Peritoneal dialysis (PD) is an established form of renal replacement therapy. Long-term PD leads to morphologic and functional changes to the peritoneal membrane (PM), which is defined as peritoneal fibrosis, a known cause of loss of peritoneal ultrafiltration capacity. Inflammation and angiogenesis are key events during the pathogenesis of peritoneal fibrosis. This review discusses the pathophysiology of peritoneal fibrosis and recent research progress on key fibrogenic molecular mechanisms in peritoneal inflammation and angiogenesis, including Toll-like receptor ligand-mediated, NOD-like receptor protein 3/interleukin-1β, vascular endothelial growth factor, and angiopoietin-2/Tie2 signaling pathways. Furthermore, novel strategies targeting peritoneal inflammation and angiogenesis to preserve the PM are discussed in depth.

Possible role of IL-6 and TIE2 gene polymorphisms in predicting the initial high transport status in patients with peritoneal dialysis: an observational study

OBJECTIVES

The aim of this study was to investigate the effect of interleukin (IL)-6 and TIE2 gene polymorphisms on baseline peritoneal transport property.

DESIGN

An observational study.

SETTING

Renji Hospital in Shanghai, China.

PARTICIPANTS

This study included 220 patients with continuous ambulatory peritoneal dialysis (PD).

OUTCOME MEASURES

Patients were divided into 2 groups based on the results of an initial peritoneal equilibration test performed within 3 months of starting PD therapy: group 1 consisted of low/low average transporters (n=123), and group 2 consisted of high/high average transporters (n=97). We genotyped TIE2 and IL-6 polymorphisms and analysed their effects on baseline transport status.

RESULTS

The genotype AT in IL-6 Rs13306435 and the genotype CC in TIE2 Rs639225 were both negatively associated with a higher initial peritoneal transport status (IL-6 Rs13306435: OR=0.408, 95% CI 0.227 to 0.736; TIE2 Rs639225: OR=0.188, 95% CI 0.044 to 0.806).

CONCLUSIONS

IL-6 and TIE2 polymorphisms are associated with baseline peritoneal transport property.

Protective effect of mycophenolate mofetil on residual renal function in peritoneal dialysis patients: An open label feasibility study

AIM

This study aims to evaluate the safety of mycophenolate mofetil (MMF) and its effect on residual renal function (RRF) during peritoneal dialysis (PD).

METHODS

This is a prospective, randomized study comprising 60 PD patients. The patients were assigned either to the MMF group (MMF dosage: 1.0-1.5 g/day in two divided doses for 6 months, followed by a dose of 0.5-0.75 g/day for another 6 months) or to the control group. The patients close monitoring for 1 year. Variables related to residual renal function, including urine volume, measured glomerular filtration rate (GFR), and renal Kt/V, were measured at four time points.

RESULTS

There were no significant changes in urinary protein excretion in either group (P > 0.05). The MMF group showed a significantly higher urine volume than the control group (955.38 ± 243.54 vs 786.15 ± 279.62 mL/day, P = 0.024). The renal kt/V was also significantly higher in the MMF group (0.59 ± 0.11 in MMF vs 0.50 ± 0.19 in control group, P = 0.032). There was significant difference in the renal measured GFR between the two groups at 6, 9 and 12 months (MMF vs control at 6 months, 6.14 ± 0.66 vs 5.58 ± 0.65 mL/min per 1.73m² , P = 0.003; at 9 months, 5.68 ± 0.80 vs 4.78 ± 0.75, P < 0.001; at 12 months, 5.44 ± 0.91 vs 4.43 ± 0.93, P < 0.001). MMF was well tolerated without any serious complications.

CONCLUSION

The use of MMF in PD patients tends to better preserve RRF.

Supplementation with high-dose trans-resveratrol improves ultrafiltration in peritoneal dialysis patients: a prospective, randomized, double-blind study

BACKGROUND

Ultrafiltration (UF) failure mostly contributes to technical failure in peritoneal dialysis (PD) patients, and one of its responsible factors is peritoneal angiogenesis. Resveratrol has been proposed to have an angiogenesis-ameliorating effect on tumor patients. We hypothesize trans-resveratrol has beneficial effects on angiogenesis-related markers in PD patients.

METHODS

In this prospective, randomized, and double-blind trial, 72 patients were randomly assigned to 12-week treatment of low-dose or high-dose (150 or 450 mg/d) trans-resveratrol or a placebo. Visits were scheduled at 0, 4, 8, and 12 weeks after treatment. Clinical indices including 24-hour UF volume, UF rate, 24-hour urine volume, residual renal function, and dialysis adequacy (kt/v) were measured. Angiogenesis markers including vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk-1), angiopoietin-2 (Ang-2), tyrosine kinase 2 (Tie-2), and thrombospondin-1 (Tsp-1) in peritoneal effluent were also assessed by enzyme-linked immunosorbent assay.

RESULTS

Finally, 64 out of 72 patients were analyzed, 18 in the high-dose group, 22 in the low-dose group, and 24 in the placebo group. Over the 12-week period, patients in the high-dose group [mean change from baseline (95% CI): 171.4 (141.3-201.5) (mL), p = 0.003 (Net UF); 11.3(10.5-12.1) (mL/h), p = 0.02 (UF rate)] or the low-dose group [mean change from baseline (95% CI: 98.1 (49.5-146.7) (mL), p = 0.007 (Net UF); 6.5 (4.4-8.6) (mL/h), p = 0.04 (UF rate)] versus the placebo group had a significantly greater improvement in mean net UF volume and UF rate. The appearance rates of VEGF, Flk-1, and Ang-2 were more significantly reduced (appearance rates of Tie-2 and Tsp-1 increased) in the high-dose group versus the placebo group, but not in the low-dose group.

CONCLUSION

Supplementation with trans-resveratrol is beneficial to improve ultrafiltration in PD patients, and high-dose supplementation may improve ultrafiltration by ameliorating angiogenesis induced by conventional lactate-buffered PD solutions.

A review of rodent models of peritoneal dialysis and its complications

This article reviews the available rodent models of peritoneal dialysis (PD) that have been developed over the past 20 years and the complications associated with their use. Although there are several methods used in different studies, the focus of this article is not to review or provide detailed summaries of these methods. Rather, this article reviews the most common methods of establishing a dialysis model in rodents, the assays used to observe function of the peritoneum in dialysis, and how these models are adapted to study peritonitis and peritoneal fibrosis. We compared the advantages and disadvantages of different methods, which should be helpful in studies of PD and may provide valuable data for further clinical studies.

Increased endothelial inflammation, sTie-2 and arginase activity in umbilical cords obtained from gestational diabetic mothers

Objective

The aim of this study was to determine subclinical inflammation in umbilical vein derived endothelial cells (HUVECs) obtained from Asian Indian subjects with gestational diabetes (GDM) and to determine levels of angiogenic factors and arginase activity in their cord blood.

Methods

This case-control study included 38 control and 30 GDM subjects. Subjects were confirmed as GDM based on 75g oral glucose tolerance test (OGTT) conducted in the second trimester of pregnancy. Angiogenic markers and arginase activity were measured in cord blood by ELISA and colorimetric methods respectively. Endothelial inflammation was assessed through adhesion of PKH26-labelled leukocytes onto HUVEC monolayer obtained from the study groups. Gene and surface expression of adhesion molecules were confirmed via reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry respectively.

Results

The study revealed increased adhesion of leukocytes to HUVECs isolated from GDM subjects compared to controls. HUVECs of babies born to GDM mothers had increased surface and mRNA expression of E-selectin. sTie2 levels were significantly higher in the cord blood for GDM subjects (3869 ± 370 ng/L) compared to controls (3045 ± 296 ng/L). Furthermore, arginase activity was higher in cord blood of GDM mothers as opposed to the control group (7.75 ± 2.4 µmoles of urea/ml/hour vs 2.88 ±0.49 µmoles of urea/ml/hour; p-value= 0.019). Spearman’s correlation analysis revealed positive correlation of cord blood arginase activity with glucose intolerance (ρ=0.596, p=0.004) and post load glucose values (ρ=0.472, p=0.031) of mothers observed during the second trimester of pregnancy.

Conclusions

HUVECs derived from Asian Indian GDM mothers, exhibit signs of sub-clinical endothelial inflammation along with increased levels of sTie2 and arginase activity in their cord blood serum.