Andreas Vychytil

Use of sodium thiosulphate in a multi-interventional setting for the treatment of calciphylaxis in dialysis patients

BACKGROUND Calciphylaxis is a life-threatening complication in patients with end-stage renal disease (ESRD). No established therapy exists so far. The aim of the present study was to determine the therapeutic response to a multi-interventional treatment regimen with consistent use of sodium thiosulphate (STS) in an Austrian cohort of calciphylaxis patients. METHODS We retrospectively collected demographic, clinical and laboratory data on 27 calciphylaxis patients treated with STS at seven Austrian dialysis centres between June 2004 and November 2010. RESULTS Twenty-seven dialysis patients (68 ± 12 years) were treated with STS for a median (25th, 75th percentile) of 96 (54, 133) days. Seven patients (26%) suffered from proximal-type, and 20 patients (74%) from distal-type calciphylaxis. Fourteen patients (52%) showed a complete remission, five patients (19%) a partial remission and eight patients (30%) progression that resulted in amputation in four patients. During a median follow-up of 101 (79, 273) days, 14 patients died (52%). Non-survivors were older (P = 0.04), showed higher CRP values (P = 0.04), presented more frequently with proximal-type calciphylaxis (P = 0.03), had a higher disease severity score at diagnosis (P = 0.01), were treated more often with antibiotics (P = 0.01) and cinacalcet (P = 0.03) and had a lower remission rate during treatment (P = 0.004) than did survivors. The use of antibiotics and cinacalcet, disease severity at diagnosis and remission rates were found to be significant survival predictors in logistic regression analysis. CONCLUSIONS Calciphylaxis remains a serious complication with high mortality. Early and consistent therapy including STS may help to improve the disease outcome.

Prevalence of NSF following intravenous gadolinium-contrast media administration in dialysis patients with endstage renal disease

PURPOSE To evaluate the prevalence of nephrogenic systemic fibrosis (NSF) in a patient population being at highest risk for developing this disease and to evaluate possible risk factors. MATERIALS AND METHODS The radiological records of 552 patients with ESRD being on hemodialysis (HD) or peritoneal dialysis (PD) were retrospectively reviewed to identify whether the patients underwent MR-examinations with or without intravenous administration of GBCA. In case of exposure to GBCA, the number of contrast injections, the benchmark and the cumulative doses of GBCA, and possible cofactors regarding pathogenesis of NSF were recorded. Diagnosis of NSF was confirmed either by deep skin biopsy or by review of medical and histopathological records. Data of NSF patients were compared with data of dialysis patients who did not develop NSF after MR-examinations. RESULTS 146 dialysis patients underwent MRI without i.v.-administration of GBCA. No case of NSF was observed in this patient population. 195/552 patients proved to have a total number of 325 well-documented exposures to GBCA. Seven different types of GBCA were used during these MR-examinations. NSF prevalence rate was 1.6%. One patient died of NSF. Three different types of GBCA were involved in 6 NSF cases. 4/6 proved to be confounded cases. The cumulative dose of GBCA, history of thrombosis, recent surgery, and the combination of HD and PD proved to be significant cofactors for the development of NSF (p<.05). No significant difference regarding residual renal clearance (p=.898) and residual urine volume (p=.083) was found between NSF and non-NSF patients. CONCLUSION The prevalence of NSF proved to be much lower in this high risk patient group being exposed to GBCA compared to the literature. NSF was not observed in ESRD patients undergoing MRI without administration of GBCA. Our data support a positive association between cumulative dose of GBCA and development of NSF. No positive association was found between residual renal clearance and residual urine volume and NSF.

WAVE1 mediates suppression of phagocytosis by phospholipid-derived DAMPs

Clearance of invading pathogens is essential to preventing overwhelming inflammation and sepsis that are symptomatic of bacterial peritonitis. Macrophages participate in this innate immune response by engulfing and digesting pathogens, a process called phagocytosis. Oxidized phospholipids (OxPL) are danger-associated molecular patterns (DAMPs) generated in response to infection that can prevent the phagocytic clearance of bacteria. We investigated the mechanism underlying OxPL action in macrophages. Exposure to OxPL induced alterations in actin polymerization, resulting in spreading of peritoneal macrophages and diminished uptake of E. coli. Pharmacological and cell-based studies showed that an anchored pool of PKA mediates the effects of OxPL. Gene silencing approaches identified the A-kinase anchoring protein (AKAP) WAVE1 as an effector of OxPL action in vitro. Chimeric Wave1(-/-) mice survived significantly longer after infection with E. coli and OxPL treatment in vivo. Moreover, we found that endogenously generated OxPL in human peritoneal dialysis fluid from end-stage renal failure patients inhibited phagocytosis via WAVE1. Collectively, these data uncover an unanticipated role for WAVE1 as a critical modulator of the innate immune response to severe bacterial infections.

Dynamic O-Linked N-Acetylglucosamine Modification of Proteins Affects Stress Responses and Survival of Mesothelial Cells Exposed to Peritoneal Dialysis Fluids

The ability of cells to respond and survive stressful conditions is determined, in part, by the attachment of O-linked N-acetylglucosamine (O-GlcNAc) to proteins (O-GlcNAcylation), a post-translational modification dependent on glucose and glutamine. This study investigates the role of dynamic O-GlcNAcylation of mesothelial cell proteins in cell survival during exposure to glucose-based peritoneal dialysis fluid (PDF). Immortalized human mesothelial cells and primary mesothelial cells, cultured from human omentum or clinical effluent of PD patients, were assessed for O-GlcNAcylation under normal conditions or after exposure to PDF. The dynamic status of O-GlcNAcylation and effects on cellular survival were investigated by chemical modulation with 6-diazo-5-oxo-L-norleucine (DON) to decrease or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc) to increase O-GlcNAc levels. Viability was decreased by reducing O-GlcNAc levels by DON, which also led to suppressed expression of the cytoprotective heat shock protein 72. In contrast, increasing O-GlcNAc levels by PUGNAc or alanyl-glutamine led to significantly improved cell survival paralleled by higher heat shock protein 72 levels during PDF treatment. Addition of alanyl-glutamine increased O-GlcNAcylation and partly counteracted its inhibition by DON, also leading to improved cell survival. Immunofluorescent analysis of clinical samples showed that the O-GlcNAc signal primarily originates from mesothelial cells. In conclusion, this study identified O-GlcNAcylation in mesothelial cells as a potentially important molecular mechanism after exposure to PDF. Modulating O-GlcNAc levels by clinically feasible interventions might evolve as a novel therapeutic target for the preservation of peritoneal membrane integrity in PD.

Icodextrin does not impact infectious and culture-negative peritonitis rates in peritoneal dialysis patients: a 2-year multicentre, comparative, prospective cohort study.

Background. Icodextrin is a glucose polymer derived by hydrolysis of cornstarch. The different biocompatibility profile of icodextrin-containing peritoneal dialysis (PD) solutions may have a positive influence on peritoneal host defence. Furthermore, cases of sterile peritonitis potentially associated with icodextrin have been reported. Methods. The primary objective of this multicentre, longitudinal, observational, non-interventional, prospective cohort study, which included 722 PD patients, was to evaluate the incidence of overall peritonitis in patients treated with icodextrin-containing PD solutions (Extraneal™) used during one long-dwell exchange/day compared with those treated with non-icodextrin-containing PD solutions. The secondary objective was to determine if culture-negative peritonitis rates differed between patients treated with icodextrin from two independent manufacturers. All peritonitis episodes were assessed by a Steering Committee in a blind manner. Results. There was no significant difference between icodextrin-treated and control patients in the adjusted overall, culture-positive or culture-negative peritonitis rates. When stratified by the icodextrin supplier, there was no significant difference in the adjusted rate of culture-negative peritonitis episodes between groups. Conclusion. Subjects receiving icodextrin as part of their PD regimen experienced neither a higher rate of culture-negative peritonitis nor a lower rate of infectious peritonitis compared with non-icodextrin users. There was no significant influence of the icodextrin raw material supplier on peritonitis rates.

Pharmacokinetics of Intraperitoneal and Intravenous Fosfomycin in Automated Peritoneal Dialysis Patients without Peritonitis

ABSTRACT Blood and dialysate concentrations of fosfomycin were determined after intravenous and intraperitoneal application of 4 mg/liter in patients undergoing automated peritoneal dialysis. Maximum serum concentrations after intravenous (287.75 ± 86.34 mg/liter) and intraperitoneal (205.78 ± 66.78 mg/liter) administration were comparable. Ratios of intraperitoneal to systemic exposure were 1.12 (intraperitoneal administration) and 0.22 (intravenous administration), indicating good systemic exposure after intraperitoneal application but limited penetration of fosfomycin into the peritoneal fluid after the intravenous dose.

Treatment with Oral Active Vitamin D Is Associated with Decreased Risk of Peritonitis and Improved Survival in Patients on Peritoneal Dialysis

Peritonitis is a major complication of peritoneal dialysis (PD) being associated with hospitalization, catheter loss, technique failure, and increased mortality. Data on incidence rates and risk factors for peritonitis episodes vary between centers. In seven Austrian PD units clinical and laboratory data on each peritonitis episode were collected from all patients (n = 726) who performed PD between January 2000 and December 2009. The peritonitis incidence rate was 0.32 episodes/patient-year. In a multivariate analysis the risk of peritonitis was decreased by 57% in patients treated with oral active vitamin D (HR 0.43; 95% CI 0.28–0.64). Renal disease classified as “other or unknown” (HR 1.65; 95% CI 1.08–2.53) and serum albumin <3500 mg/dl (HR 1.49; 95% CI 1.04–2.15) were also associated with an increased risk of peritonitis. Albumin levels <3500 mg/dl (HR 1.89; 95% CI 1.13–3.17), age (HR 1.06 per year; 95% CI 1.03–1.09), and cardiomyopathy (HR 3.01; 95% CI 1.62–5.59) were associated with increased mortality, whereas treatment with oral active vitamin D was associated with a significantly lower risk of death (HR 0.46; 95% CI 0.27–0.81). In this retrospective multi-center study we identified several factors being related to increased risk of peritonitis in PD patients. Treatment with oral active vitamin D was identified as being independently associated with decreased risk of peritonitis, and decreased all-cause mortality in PD patients.

Low-Sodium Versus Standard-Sodium Peritoneal Dialysis Solution in Hypertensive Patients: A Randomized Controlled Trial

BACKGROUND Peritoneal dialysis (PD) solutions with reduced sodium content may have advantages for hypertensive patients; however, they have lower osmolarity and solvent drag, so the achieved Kt/Vurea may be lower. Furthermore, the increased transperitoneal membrane sodium gradient can influence sodium balance with consequences for blood pressure (BP) control. STUDY DESIGN Prospective, randomized, double-blind clinical trial to prove the noninferiority of total weekly Kt/Vurea with low-sodium versus standard-sodium PD solution, with the lower confidence limit above the clinically accepted difference of -0.5. SETTING & PARTICIPANTS Hypertensive patients (≥ 1 antihypertensive drug, including diuretics, or office systolic BP ≥ 130 mmHg) on continuous ambulatory PD therapy from 17 sites. INTERVENTION 108 patients were randomly assigned (1:1) to 6-month treatments with either low-sodium (125 mmol/L of sodium; 1.5%, 2.3%, or 4.25% glucose; osmolarity, 338-491 mOsm/L) or standard-sodium (134 mmol/L of sodium; 1.5%, 2.3%, or 4.25% glucose; osmolarity, 356-509 mOsm/L) PD solution. OUTCOMES Primary end point: weekly total Kt/Vurea; secondary outcomes: BP control, safety, and tolerability. MEASUREMENTS Total Kt/Vurea was determined from 24-hour dialysate and urine collection; BP, by office measurement. RESULTS Total Kt/Vurea after 12 weeks was 2.53 ± 0.89 in the low-sodium group (n = 40) and 2.97 ± 1.58 in the control group (n = 42). The noninferiority of total Kt/Vurea could not be confirmed. There was no difference for peritoneal Kt/Vurea (1.70 ± 0.38 with low sodium, 1.77 ± 0.44 with standard sodium), but there was a difference in renal Kt/Vurea (0.83 ± 0.80 with low sodium, 1.20 ± 1.54 with standard sodium). Mean daily sodium removal with dialysate at week 12 was 1.188 g higher in the low-sodium group (P < 0.001). BP changed marginally with standard-sodium solution, but decreased with low-sodium PD solution, resulting in less antihypertensive medication. LIMITATIONS Broader variability of study population than anticipated, particularly regarding residual kidney function. CONCLUSIONS The noninferiority of the low-sodium PD solution for total Kt/Vurea could not be proved; however, it showed beneficial clinical effects on sodium removal and BP.

Addition of Alanyl-Glutamine to Dialysis Fluid Restores Peritoneal Cellular Stress Responses – A First-In-Man Trial

Background Peritonitis and ultrafiltration failure remain serious complications of chronic peritoneal dialysis (PD). Dysfunctional cellular stress responses aggravate peritoneal injury associated with PD fluid exposure, potentially due to peritoneal glutamine depletion. In this randomized cross-over phase I/II trial we investigated cytoprotective effects of alanyl-glutamine (AlaGln) addition to glucose-based PDF. Methods In a prospective randomized cross-over design, 20 stable PD outpatients underwent paired peritoneal equilibration tests 4 weeks apart, using conventional acidic, single chamber 3.86% glucose PD fluid, with and without 8 mM supplemental AlaGln. Heat-shock protein 72 expression was assessed in peritoneal effluent cells as surrogate parameter of cellular stress responses, complemented by metabolomics and functional immunocompetence assays. Results AlaGln restored peritoneal glutamine levels and increased the primary outcome heat-shock protein expression (effect 1.51-fold, CI 1.07–2.14; p = 0.022), without changes in peritoneal ultrafiltration, small solute transport, or biomarkers reflecting cell mass and inflammation. Further effects were glutamine-like metabolomic changes and increased ex-vivo LPS-stimulated cytokine release from healthy donor peripheral blood monocytes. In patients with a history of peritonitis (5 of 20), AlaGln supplementation decreased dialysate interleukin-8 levels. Supplemented PD fluid also attenuated inflammation and enhanced stimulated cytokine release in a mouse model of PD-associated peritonitis. Conclusion We conclude that AlaGln-supplemented, glucose-based PD fluid can restore peritoneal cellular stress responses with attenuation of sterile inflammation, and may improve peritoneal host-defense in the setting of PD.

Functional and Transcriptomic Characterization of Peritoneal Immune-Modulation by Addition of Alanyl-Glutamine to Dialysis Fluid

Peritonitis remains a major cause of morbidity and mortality during chronic peritoneal dialysis (PD). Glucose-based PD fluids reduce immunological defenses in the peritoneal cavity. Low concentrations of peritoneal extracellular glutamine during PD may contribute to this immune deficit. For these reasons we have developed a clinical assay to measure the function of the immune-competent cells in PD effluent from PD patients. We then applied this assay to test the impact on peritoneal immune-competence of PD fluid supplementation with alanyl-glutamine (AlaGln) in 6 patients in an open-label, randomized, crossover pilot trial (EudraCT 2012-004004-36), and related the functional results to transcriptome changes in PD effluent cells. Ex-vivo stimulation of PD effluent peritoneal cells increased release of interleukin (IL) 6 and tumor necrosis factor (TNF) α. Both IL-6 and TNF-α were lower at 1 h than at 4 h of the peritoneal equilibration test but the reductions in cytokine release were attenuated in AlaGln-supplemented samples. AlaGln-supplemented samples exhibited priming of IL-6-related pathways and downregulation of TNF-α upstream elements. Results from measurement of cytokine release and transcriptome analysis in this pilot clinical study support the conclusion that suppression of PD effluent cell immune function in human subjects by standard PD fluid is attenuated by AlaGln supplementation.