Impaired cellular host defence in peritoneal dialysis by two granulocyte inhibitory proteins

Bacterial and fungal peritonitis is associated with a high riskof morbidity and mortality in patients undergoing continuousambulatory peritoneal dialysis (CAPD). Impaired cellular hostdefence in the peritoneal cavity underlies this risk. Two granulocyteinhibitory proteins with a molecular weight of 28000 dalton(GIP I) and about 9500 dalton (GIP II) with homology to light-chainproteins and beta respectively, were isolated from peritonealdialysis effluents. In vitro, both granulocyte inhibitory proteinsinhibit PMNL glucose uptake, phagocytosis and intracellularkilling of bacteria. The IC₅₀ of GIP I or GIP II required forinhibition of half-maximal FMLP-induced or PMA-stimulated PMNLfunction was found to be in the nanomolar range, suggestingvery specific inhibition. These data may explain, at least inpart, defective local cellular host defence in CAPD patients.     

Endocrine and metabolic abnormalities following kidney transplantation

Summary Various endocrine and metabolic disturbances associated with long standing uremia persist after kidney transplantation or arise from the use of immunosuppressive drugs. Hyperlipidemia for long time being implicated as the cause of corticosteroids is also observed in renal transplant recipients treated with cyclosporin A monotherapy. After conversion from cyclosporin to azathioprine serum cholesterol and triglyceride concentration fall, and elevation of LDL-cholesterol may also be reversed. There is a tendency for higher HDL-cholesterol in azathioprine and prednisolone treated transplant patients. Those patients who are at risk for clinically significant cholesterol elevations can be predicted by their pretransplant lipid levels, specifically the LDL-fraction. Risk-benefit ratio of conversion and of treatment with lipid-lowering drugs, especially with lovastatin, should be carefully examined, also in view of glucose intolerance.Higher incidence of diabetes mellitus requiring insulin therapy in cyclosporin treated transplant recipients has been reported. Cyclosporin may cause toxic effects on pancreatic beta-cells resulting in inhibition of insulin secretion. High doses of cyclosporin induce inhibition of glycogen synthesis in rat liver. Glucose intolerance is reversible after reduction of cyclosporin dose or conversion to azathioprine. Therefore glucose metabolism in kidney transplant recipients treated with cyclosporin should be carefully followed.Immunosuppressive therapy may affect reproductive function, arachidonate metabolism and renin-angiotensin-aldosterone system as well as posttransplant calcium and phophate metabolism.Endocrine and metabolic abnormalities are associated with long standing uremia. After successful kidney transplantation several observations are normalized but further complications arise from the use of immunosuppressive drugs. The present paper reviews various endocrine and metabolic disturbances described following renal transplantation.     

Peritonealdialyseassoziierte Infektionen

Infections associated with peritoneal dialysis are often the Achilles heel for success of peritoneal dialysis. Every center should regularly monitor infections. Peritonitis is diagnosed if two of the following three criteria are present: clinical symptoms and cloudy dialysate, increased white blood cells in the dialysate or positive dialysate culture. The initial antibiotic therapy should cover both gram-positive and gram-negative bacteria. Currently there is no clear definition for peritoneal dialysis catheter infections. For the diagnosis for tunnel infections and to control the success of the therapy, tunnel sonography is obligatory. The International Society for Peritoneal Dialysis (ISPD) recommends that replacement of catheters for peritoneal dialysis should be considered more frequently and the focus should always be on preservation of the peritoneum rather than saving the peritoneal catheter. Prophylaxis to reduce catheter infections is of great importance and training has a great impact on preventing infections. Re-training should be carried out regularly. The ISPD recommends local antibiotic therapy for all patients but the impact of this recommendation on the development of resistance is not clear.     

Protease dependent activation of endothelial cells by peritoneal dialysis effluents.

Incubation of cultured human umbilical vein endothelial cells (HUVECs) with dilutions of peritoneal dialysis effluents (PDEs) from 11 individual patients undergoing continuous ambulatory peritoneal dialysis (CAPD) induced cellular procoagulant activity in a dose and time dependent manner. This procoagulant activity could be attributed to tissue factor (TF) expression since it was blocked by rabbit anti-TF IgG. These data was confirmed by FACS analysis yielding surface TF expression; In addition PDEs induced the expression of E-selectin in HUVECs. This TF and selectin inducing activity was heat labile and could be inhibited by protease inhibitors. Partial purification could be achieved using a benzamidine-Sepharose column. The TF inducing activity could not be attributed to LPS, IL-1, TNF-alpha, mast cell tryptase, active thrombin, or complement factor D. We therefore conclude that the peritoneal cavity contains a protease activity that induces a procoagulatory and proinflammatory phenotype in HUVECs.     

Darbepoetin alfa effectively maintains haemoglobin concentrations at extended dose intervals relative to intravenous or subcutaneous recombinant human erythropoietin in dialysis patients.

BACKGROUND: Darbepoetin alfa is a unique molecule that stimulates erythropoiesis by the same mechanism as endogenous erythropoietin. Due to its approximately 3-fold longer half-life and greater biological activity than recombinant human erythropoietin (rHuEpo), darbepoetin alfa maintains effective haemoglobin control at extended dose intervals compared with rHuEpo. This study assessed the efficacy and safety of unit doses of darbepoetin alfa for the treatment of renal anaemia. METHODS: In this multicentre, prospective, open-label study, 1502 dialysis subjects maintained on stable rHuEpo treatment were switched to darbepoetin alfa at extended dose intervals by the same route of administration as previous rHuEpo therapy [intravenous (i.v.), n = 900 or subcutaneous (s.c.), n = 602]. Subjects receiving rHuEpo two (n = 408, 27%) or three times (n = 884, 59%) a week were switched to darbepoetin alfa once a week, and those receiving rHuEpo once a week (n = 210, 14%) were switched to darbepoetin alfa once every 2 weeks. The unit doses of darbepoetin alfa (10-150 microg) were titrated to maintain haemoglobin concentrations of 10-13 g/dl for 24 weeks. RESULTS: Haemoglobin concentrations were maintained effectively in subjects regardless of whether they received darbepoetin alfa once a week or once every 2 weeks. The overall mean change in haemoglobin from baseline to the evaluation period (weeks 21-24) was +0.10 g/dl [95% confidence interval (CI) 0.04+/- 0.17]. The mean haemoglobin concentration increased by 0.19 g/dl (95% CI 0.11+/-0.27) in subjects receiving i.v. darbepoetin alfa, and was unchanged (-0.02 g/dl; 95% CI -0.12 to 0.07) in patients treated with s.c. darbepoetin alfa. Subjects with baseline haemoglobin < 11 g/dl experienced a clinically relevant increase in mean haemoglobin concentration of 0.67 g/dl (95% CI 0.56+/-0.77) from baseline to the evaluation period. The mean weekly i.v. and s.c. darbepoetin alfa dosage requirements during the evaluation period were 19.9 microg/week (95% CI 19.02+/-20.87) and 21.6 microg/week (95% CI 20.36+/- 22.94), respectively. Darbepoetin alfa was well tolerated and the safety profile was consistent with previous trials with darbepoetin alfa in dialysis subjects. CONCLUSIONS: Treating renal anaemia with darbepoetin alfa administered at extended dose intervals is both effective and well tolerated. Moreover, administration of darbepoetin alfa by both the i.v. and s.c. route is associated with stable haemoglobin concentrations.     

Physicochemical characterization of a polypeptide present in uremic serum that inhibits the biological activity of polymorphonuclear cells.

A granulocyte inhibitory protein was isolated and characterized from uremic serum by using ion-exchange column chromatography, high-performance size-exclusion chromatography, and immunochemical procedures. The purification process concentrated the protein 240-fold and to a purity of greater than 95%. An overall recovery of 45% was achieved; the purified protein had a specific activity of 104 units per mg of protein. The polypeptide had a molecular weight of approximately 28,000 and an isoelectric point of 4.0-4.5. Amino acid sequencing of the NH2 terminus revealed a single sequence (Asp-Ile-Val-Met-Thr-Gln-Ser-Pro-Gly-Thr-Leu-Ser-Val-Ser-Pro-Gly-Glu-Arg-Ala- Thr) that proved to be nonhomologous with other serum proteins that appear during an inflammatory state. The polypeptide inhibited the uptake of deoxyglucose, chemotaxis, oxidative metabolism, and intracellular bacterial killing by polymorphonuclear leukocytes. A specific rabbit polyclonal antibody raised against the protein nullified these inhibitory changes. We contend that the protein is responsible for the leukocyte dysfunction that is commonly seen in patients with uremia.     

Intensivierte Hämodialyse

There are different ways to intensify hemodialysis. These include lengthening the duration of dialysis at the same frequency, increasing the frequency at the same total weekly duration, and both. Increase in frequency is more effective than longer duration of dialysis alone. Almost all applicable studies found improvements in blood pressure as well as reductions in left ventricular hypertrophy. Also less erythropoietin is needed for managing anemia, and phosphate levels are easier to control. With most patients however, completely avoiding phosphate binders has been possible only with long and daily dialysis. Daily dialysis is possible without assistance for patients at home. So far there is no indication of a negative influence from daily dialysis on the longevity of shunts.     

Prospective multicenter study of HX575 (biosimilar epoetin-α) in patients with chronic kidney disease applying a target hemoglobin of 10--12 g/dl

HX575 was approved in the European Union in August 2007 as the first-ever biosimilar epoetin-α product. The present study extended the safety database on HX575 by monitoring adverse events (AEs) in clinical practice. Hemoglobin (Hb) levels and HX575 doses were recorded for the assessment of efficacy. This open, 6-month single-arm study was conducted in 10 European countries with a target enrollment of 1,500 patients with anemia due to chronic kidney disease (CKD). HX575 was intravenously (i.v.) administered aiming at an Hb target of 10 - 12 g/dl. Most patients (92.3%) had already received erythropoiesis stimulating agents (ESAs) treatment before enrolment into this study; the recorded treatments mainly comprised i.v. or subcutaneous (s.c.) administration of epoetin-α, epoetin-β or darbepoetin. The study period covered 770 patient years. The observed AE profile was in line with expectations for this patient population. Thrombotic vascular events (TVEs) were reported in 11.9% of patients (0.2612 per patient year). Tumor incidence was 1.4% (0.0299 per patient year). No subject developed anti-epoetin antibodies. Mean Hb levels were effectively maintained between 11.2 and 11.3 g/dl following the conversion from a broad spectrum of pre-study ESA treatments with stable overall mean i.v. HX575 doses. The proportion of patients within the Hb target range increased from 57.5% at baseline to 66.8% at study end.     

β-2-Microglobulin and Main Granulocyte Components in Hemodialysis Patients

Plasma levels of granulocyte elastase in complex with alpha 1-proteinase inhibitor (E-alpha 1-PI) increased during hemodialysis from 110 +/- 10 to 506 +/- 66 micrograms/L using dialyzers made of polyamide, from 95 +/- 2.2 to 211 +/- 54 micrograms/ml with hemophane and from 114 +/- 10 to 203 +/- 25 using dialyzers made of polysulfone. Plasma lactoferrin values were also significantly higher during hemodialysis with polyamide (772 +/- 110 micrograms/L) compared with hemophane (268 +/- 2.2) and the polysulfone (278 +/- 31 micrograms/L) dialyzer. After dialysis each dialyzer was rinsed. We found the lowest concentration of lactoferrin (902 +/- 254 micrograms/L) and E-alpha 1-PI (739 +/- 162 micrograms/L) after rinsing polysulfone dialyzers, whereas the highest concentrations were observed after rinsing the polyamide dialyzer (lactoferrin: 2,426 +/- 314; E-alpha 1-PI: 1,134 +/- 144 micrograms/L). Hemodialysis with polysulfone dialyzers caused significantly lower plasma levels of beta-2-microglobulin compared with polyamide or hemophane membranes despite significantly lower levels in the rinsing solutions. Our data indicate that low plasma levels of main granulocyte component observed with polysulfone and hemophane dialyzers are not the result of higher membrane adsorption of E-alpha 1-PI and lactoferrin. These main granulocyte components are not related to beta-2-microglobulin levels of both plasma and rinsing solutions.     

Isolation of a granulocyte inhibitory protein from uraemic patients with homology of {beta}2-microglobulin

Increased incidence of infection in uraemic patients is mainlycaused by granulocyte dysfunction. Recently we discovered agranulocyte inhibitory protein (GIP I) in the ultrafiltrateof haemodialysis patients, that inhibits four fundamental functionsof polymorphonuclear leukocytes (PMNLs). We now report on theisolation of a further polypeptide in end- stage renal diseasepatient ultrafiltrate using a polyamide filter with biologicalactivity inhibiting healthy PMNL function in vitro. This protein (GIP II) has a molecular weight of about 9500 Da.In-vitro nanomolar concentrations inhibit PMNL 02 productionand glucose uptake stimulated by phorbol-myristate-acetate (PMA),but not by formyl-methionyl-leucyl-phenylalanine (FMLP). In-vitrostudies were performed to compare the effects of GIP I and GIPII on several PMNL functions. In contrast to GIP II, GIP I inhibitsonly FMLP-, but not PMA-stimulated PMNL glucose uptake. TheNH2 terminal amino acid sequence (21 amino acids) of GIP IIshows homology to ß-microglobulin. Commercially availableintact ß-microglobulin had no effect on PMNL glucoseuptake and 02 production. The ß-microglobulin homologueprotein isolated from plasma ultrafiltrates of uraemic patientscross-reacts with three different commercially available assaysfor intact ß-microglobulin. Therefore, ß-microglobulinlevels measured in the plasma ultraffitrates of regular haemodialysispatients are overestimated with contribution of an uncertainamount of the ß-microglobulin homologue protein (GIPII).