Incidence of Pneumocystis carinii pneumonia after renal transplantation. Impact of immunosuppression

The incidence and potential risk factors of Pneumocystis carinii pneumonia (PCP) in our population of renal transplant recipients were analyzed retrospectively. Of 1427 patients who received transplants between January 1986 and June 1994, 1192 were evaluated. Four different immunosuppressive regimens were applied: (1) cyclosporine (CsA) + prednisolone (Pred), (2) CsA + azathioprine (Aza, 2 mg/kg/day) + Pred, (3) CsA + Aza + antithymocyte globulin, and (4) (after December 1, 1993, European multicenter trial) FK506 + Aza (1 mg/kg/day) + Pred. No prophylaxis against PCP was performed. Before December 1, 1993, three PCPs in 494 patients on protocol 2 or 3 occurred (0.6%). Afterward, seven PCPs in 77 patients occurred (9%): three in 38 patients on protocol 2 (7.8%) and four in 28 patients on protocol 4 (14.3%). Comparing patients with PCP on CsA and FK506, the mean Aza dose was 2.40 and 1.32 mg/kg/day, five and two patients received additional steroids, antibody treatment was used in three and no patients, and CMV infections occurred in five and two patients, respectively. The incidence of PCP with a moderate CsA-based immunosuppressive regimen is low and seems to occur only in cases of additional immunosuppressive cofactors. Despite a general increase of PCP, its incidence was highest in patients on FK506 with fewer immunosuppressive cofactors. Thus, prophylaxis against PCP after renal transplantation should be performed, if not in every renal transplant recipient, at least in case of treatment with additional steroids, antibodies, or FK506.

Pharmacokinetics of bismuth and ranitidine following single doses of ranitidine bismuth citrate

1. The pharmacokinetics of bismuth and ranitidine derived from ranitidine bismuth citrate given in single oral doses ranging from 200 mg to 1600 mg were evaluated in healthy subjects. 2. Bismuth was only minimally absorbed (< 0.5% of the amount dosed) after administration of ranitidine bismuth citrate, and peak plasma concentrations never exceeded 33 ng ml-1 in any subject. Plasma concentrations and urinary recoveries of bismuth at doses up to and including 800 mg were relatively constant and not proportional to dose. Bismuth absorption was increased more than proportionally with the dose at 1600 mg. 3. The pharmacokinetics of ranitidine after administration of ranitidine bismuth citrate were dose-proportional and consistent with previous observations for ranitidine administered alone. 4. Ranitidine bismuth citrate was well-tolerated in single oral doses of up to 1600 mg.

Pharmacokinetics of bismuth and ranitidine following multiple doses of ranitidine bismuth citrate

1. The pharmacokinetics of bismuth and ranitidine derived from oral doses of ranitidine bismuth citrate 800 mg given twice daily for 28 days were examined in this double-blind, placebo-controlled, parallel-group study in 27 healthy subjects. 2. Bismuth accumulation in plasma reflected its multicompartmental disposition, achieving the majority of predicted steady state within 14-28 days. Bismuth absorption from ranitidine bismuth citrate is limited (< 0.5% of the dose), and bismuth elimination is predominantly renal secretion. Peak plasma concentrations did not exceed 19 ng ml-1, remaining well below those associated with bismuth toxicity. Bismuth was measurable at low concentrations in plasma and urine for up to 5 months after the last dose. Plasma bismuth concentration-time data and urinary excretion data were best described by separate multicompartmental models, with terminal half-lives averaging 21 days and 45 days, respectively. 3. The pharmacokinetics of ranitidine derived from ranitidine bismuth citrate were similar to those of ranitidine administered alone. Ranitidine did not appreciably accumulate in plasma. 4. Ranitidine bismuth citrate was well-tolerated during 28 days of repeated dosing.

Bacterial challenge of NISSHO ultrafilter ETF 609: results of in vitro testing

In hemodialysis, a certain degree of bacterial contamination on the dialysate side is a regular finding. Concern has been growing that this contamination may lead to a chronic inflammatory response in the patient. Ultrafiltration of dialysate can be used to reduce bacterial content and levels of cytokine-inducing substances upstream of the patient's dialyzer. The aim of this study was to test in vitro the rejection capacity of a polysulfone hollow-fiber ultrafilter (ETF 609, NISSHO Co., Osaka, Japan) challenged with bacterial filtrates derived from Pseudomonas aeruginosa PA103. Results showed a reduction of interleukin-1 beta-inducing activity (measured on peripheral blood mononuclear cells) from 5,035 +/- 394 pg/ml prefilter to nondetectable levels postfilter and endotoxin levels (limulus amebocyte lysate assay) of 4,167 +/- 1,079 versus 12 +/- 2 pg/ml, respectively. In conclusion, ultrafiltration of dialysate with the polysulfone ultrafilter ETF 609 leads to a potent reduction of cytokine-inducing activity.

How best to use tacrolimus (FK506) for treatment of steroid- and OKT3-resistant rejection after renal transplantation

Nineteen patients with biopsy-confirmed ongoing acute rejection of renal allografts were converted from standard immunosuppression to FK506. Eight grafts showed vascular rejection and 11 had cellular rejection on biopsy. All patients had already received intravenous high-dose steroid treatment. Ten patients also had additional OKT3 rescue therapy. Initial FK506 doses were 0.13 +/- 0.06 mg/kg/day; the FK506 whole blood trough level after 3 days of treatment was 9.3 +/- 4.5 ng/ml. After conversion to FK506 all but four patients also received azathioprine, 1.5-2 mg/kg/day, and all patients received oral prednisolone. Concomitant with initiation of FK506, an anti-infective prophylaxis was prescribed, consisting of ganciclovir and trimethoprim/sulfamethoxazole. Sixteen out of 19 of the grafts (84%) were rescued successfully, including two grafts of patients already on hemodialysis at the time of conversion. Graft function of the responders improved from an average serum creatinine level of 364 +/- 109 mumol/L to 154 +/- 49 mumol/L. Of the patients receiving high-dose steroids alone prior to FK506 initiation, 8/9 responded to FK506 treatment, compared with 8/10 of those who had also received OKT3. During the mean follow-up of 35 weeks after conversion, no clinically apparent cytomegalovirus infection and no pneumonia were seen. Treatment with FK506 may successfully suppress ongoing acute rejection, even if antilymphocyte preparations have failed. FK506 can be used at a lower dose than so far recommended without impairing the antirejection potential. An additional anti-infective prophylaxis seems effective in preventing severe complications in the first months after rejection therapy.

High mortality from urothelial carcinoma despite regular tumor screening in patients with analgesic nephropathy after renal transplantation

Patients with end-stage renal failure due to analgesic nephropathy have an increased risk of developing a urothelial carcinoma. To determine the impact of renal transplantation on the frequency of urothelial carcinomas, we analyzed 2072 patients who underwent 2371 renal transplantation between 1968 and 1993, including 78 (3.8%) with clinically proven analgesic nephropathy. Before and after transplantation a regular tumor screening was performed in patients with analgesic nephropathy by urine cytology and abdominal sonography. In 11 of the 78 patients with analgesic nephropathy (14.1%; age 51-66 years, 40-108 months after initiation of dialysis treatment, 5-77 months after transplantation), a urothelial carcinoma of the native urinary tract, especially the kidneys, was diagnosed. Therapy comprised nephroureterectomy (n = 6), transurethral resection (n = 6) and/or cystectomy (n = 2). Seven patients died due to tumor progression 16.3 (4-33) months postoperatively and one patient died due to a perioperative complication. Despite regular tumor screening after transplantation, the diagnosis of a urothelial carcinoma was made very late, leading to a high tumor-related mortality. As a consequence, we suggest that a bilateral nephroureterectomy should be performed prophylactically in patients with proven analgesic nephropathy. In addition, a cystoscopy with lavage cytology testing of the bladder should be performed twice a year.

Chronic induction of C-reactive protein by hemodialysis, but not by peritoneal dialysis therapy

OBJECTIVE

Evaluation of the inflammatory activity in patients on chronic peritoneal dialysis (PD) and patients on chronic hemodialysis (HD) in comparison to patients with chronic renal insufficiency without dialysis treatment and healthy volunteers.

DESIGN

Open, nonrandomized prospective study.

SETTING

Nephrology Department, including HD and PD therapy in a university hospital.

PATIENTS

Twenty-four patients on chronic PD,21 patients on chronic HD therapy using a cuprophan dialyzer,16 patients with chronic renal insufficiency without dialysis treatment, and 33 healthy volunteers; 8 additional patients before and after initiation of chronic HD therapy. All patients and controls were without infection or immunosuppressive therapy.

MAIN OUTCOME MEASURES

As a marker of the inflammatory activity in the different patient groups, C-reactive protein (CRP) was measured serially using a sensitive, enzyme-linked, immunosorbent assay in order to detect values below the detection limit of standard assays.

RESULTS

Patient groups had CRP levels higher than the normal controls (p < 0.01). Patients on HD had CRP levels significantly higher than PD patients (p < 0.01) whose levels were comparable to patients without dialysis therapy. Accordingly, longitudinal measurements before and after initiation of chronic HD showed a significant increase in CRP levels after the beginning of HD treatment (p < 0.04).

CONCLUSIONS

The results suggest that induction of the inflammatory activity is lower during PD compared to HD, since stimulation by the dialyzer membrane, dialysate buffer, or bacterial fragments in the dialysate is avoided. This observation might indicate a possible lower risk of long-term complications in patients with PD.

Mechanisms involved in the pathogenesis of tubulointerstitial fibrosis in 5/6-nephrectomized rats

The 5/6 nephrectomy model is used to study pathogenetic mechanisms underlying chronic renal failure. We previously demonstrated that increased mesangial cell proliferation and glomerular PDGF B-chain expression precede glomerulosclerosis in this model. In the present study we have assessed the concomitant changes in the cortical tubulointerstitium. A wave of tubular and interstitial cell proliferation (as determined by immunostaining for PCNA) occurred at week 1 after 5/6 nephrectomy. This wave preceded the peak glomerular cell proliferation by one week. Tubulointerstitial cell proliferation decreased thereafter and reached control values by week 10. In situ hybridization and immunostaining for PDGF B-chain and beta-receptor in sham-operated controls showed labeling of distal tubules and collecting ducts, while no signal was present in the interstitium. PDGF B-chain mRNA and protein expression was markedly increased in tubules at weeks 2 and 4 after 5/6 nephrectomy and in the interstitium (particularly in areas of inflammatory infiltrates) at weeks 2 to 10. Similar changes occurred with PDGF receptor beta-subunit immunostaining. Interstitial expression of desmin and alpha-smooth muscle actin (markers of myofibroblasts) progressively increased after week 1. Interstitial influx of monocytes/macrophages with focal accentuation started at week 2. Counts of lymphocytes, neutrophils and platelets showed only minor changes. In parallel to the monocyte/macrophage influx, progressive interstitial accumulation of collagens I and IV, laminin, and fibronectin occurred. All of these changes were correlated with the increase in serum creatinine, proteinuria and an index of tubulointerstitial damage. We conclude that tubulointerstitial changes after 5/6 nephrectomy show similarities with those observed in the glomeruli. Tubular and interstitial overexpression of PDGF B-chain and its receptor may play a role in mediating fibroblast migration and/or proliferation in areas of tubulointerstitial injury.

Long-term performance of hemofilters in continuous hemofiltration

We measured the filter performance of six polyamide hemofilters with a running time exceeding 72 h applied for continuous hemofiltration in intensive care patients. The sieving coefficients for urea and creatinine were close to unity and remained constant. The sieving coefficient of polyfructosan (mean molecular weight 3 kD) was around 0.75 and did not change with running time. The hydraulic permeability remained also unchanged. The relationships between blood pressure and blood flow and between blood flow and filtration rate remained linear, and the gradient did not change with time. We conclude that a daily routine change of polyamide hemofilters applied in continuous arteriovenous hemofiltration and presumably in continuous venovenous hemofiltration is not necessary within the first 72 h of treatment, unless a major decrease in the filtration rate occurs.

Recurrence of membranoproliferative glomerulonephritis after renal transplantation in a patient with chronic hepatitis C

Chronic hepatitis C (HCV) infection may be associated with membranoproliferative glomerulonephritis (MPGN) with or without concomitant cryoglobulinemia. We report on a patient with end-stage renal disease caused by MPGN I in association with replicative HCV infection. Two years after successful renal transplantation, this patient developed nephrotic syndrome caused by recurrence of MPGN I in the renal transplant. The recurrence of renal disease after transplantation in this patient with chronic replicative HCV further elucidates the role of the viral infection in the pathogenesis of MPGN and suggests anti-viral treatment as, e.g., with interferon.

Induction of interleukin-1 and interleukin-1 receptor antagonist during contaminated in-vitro dialysis with whole blood

BACKGROUND

Previous studies on the permeability of cellulosic and synthetic dialysers for bacterial-derived cytokine-inducing substances gave conflicting results. We tried to study this issue as close to the in-vivo situation as possible.

METHODS

An in-vitro dialysis circuit with whole human blood present in the blood compartment of cuprophane (Cup), polysulphone (PS), and polyamide (PA) dialysers was employed; sterile filtrates derived from Pseudomonas aeruginosa cultures were added to the dialysate. We studied the induction of interleukin-1 beta (IL-1 beta) by plasma samples taken from the blood compartment as well as the induction of IL-1 beta and interleukin-1 receptor antagonist (IL-1Ra) in mononuclear cells separated from whole blood after circulation by radioimmunoassay and polymerase chain reaction.

RESULTS

Plasma samples from the blood side of all dialysers induced IL-1 beta from non-circulated mononuclear cells after addition of pseudomonas filtrates to the dialysate; the maximal amount of IL-1 beta induced by samples from the blood compartment was 4.8 +/- 1.2 ng/ml for Cup, 1.9 +/- 0.5 ng/ml for PS, and 2.0 +/- 0.6 ng/ml for PA. Mononuclear cells separated after contaminated dialysis will all types of dialysers expressed increased mRNA levels for IL-1 beta and IL-1Ra. Production of IL-1Ra by cells separated after contaminated dialysis was determined after Cup and PS dialysis; there was increased production of IL-1Ra by these cells (Cup, 10.3 +/- 4.2; PS, 7.3 +/- 2.5 ng/ml) compared to cells separated after sterile dialysis (Cup, 5.6 +/- 2.1, P < 0.05; PS, 4.5 +/- 1.1 ng/ml, n.s.) or from non-circulated blood (Cup experiments, 4.7 +/- 1.5, P < 0.05; PS experiments, 4.1 +/- 1.2 ng/ml, n.s.).

CONCLUSIONS

These data suggest penetration of cytokine-inducing substances through both cellulosic and synthetic dialysers. Differences between dialysers may exist regarding extent and time course of penetration. The detection of cytokine mRNA as well as the measurement of IL-1Ra synthesis is a more sensitive marker for the transfer of cytokine-inducing substances through dialyser membranes than the measurement of IL-1 beta protein synthesis.

Diagnostic aspects of beta 2-microglobulin amyloidosis

Osteoarticular symptoms and signs, such as carpal tunnel syndrome, periarthritis humeroscapularis, synovial and joint inflammation, lead to the clinical diagnosis of beta 2-microglobulin (beta 2-M) amyloidosis. Radiologically, destructive arthropathy, spondylarthropathy and periarticular cystic bone radiolucencies can be demonstrated by plain X-ray and conventional and computed tomography. Magnetic resonance is used to visualize amyloid masses in special locations such as the cervical spine. Joint ultrasonography demonstrating thickening of synoviae and tendons has become a useful non-invasive diagnostic tool, although it is not specific for beta 2-M amyloidosis, and results depend on observer experience. Efforts to develop more specific methods for demonstration of amyloid deposits have led to two scintigraphic techniques based on the injection of radiolabelled proteins which are incorporated into the amyloid tissue. One method uses serum amyloid P component, a non-specific constituent of all types of amyloid. An alternative imaging technique based on radiolabelled beta 2-M as the specific precursor molecule of beta 2-M amyloidosis appears to be a more sensitive diagnostic method. Both tracer techniques have been used so far only in small single-centre clinical studies, and a more widespread application will require the introduction of recombinant material as the protein source for labelling. The 'gold standard' for the definitive diagnosis of beta 2-M amyloidosis, and also for reference in the evaluation of new diagnostic techniques, remains the histomorphological demonstration of beta 2-M amyloid by Congo red staining, green birefringence under polarized light, positive immunostaining with anti-beta 2-M antibodies, and electronoptic visualization of amyloid fibrils in tissue obtained invasively by biopsy, surgery or autopsy.

Retention of cytokine-inducing substances inside high-flux dialyzers

Reprocessing of dialyzers is often performed with nonsterile solutions possibly contaminated with bacterial-derived cytokine-inducing substances. We investigated the retention of cytokine-inducing substances inside the dialyzer during reprocessing in a closed loop in vitro hemodialysis system using a polyamide high flux membrane. After the first in vitro circulation of human whole blood, rinse of the blood compartment (BC) and reverse ultrafiltration (RUF) was performed with either cytokine-inducing substance-free saline or saline contaminated with filtrates from Pseudomonas cultures (6 ng/ml LAL-reactive material); subsequently, dialyzers were stored in 2% formaldehyde. Dialyzers were rinsed with approximately 15 liters pyrogen-free saline before the second circulation using blood from the same donor; the effluates were free of cytokine-inducing substances and formaldehyde. Before and after the blood circulations, peripheral blood mononuclear cells (PBMC) were separated and total production of IL-1 alpha and IL-1 beta was determined after overnight incubation. In noncirculated PBMC as well as in PBMC separated after whole blood circulation with pyrogen-free processed dialyzers, production of IL-1 beta was not detectable. After contaminated rinse of the BC, production of IL-1 beta could be observed (1,600 +/- 1,100 pg/ml, mean +/- SEM). When pyrogen-free RUF was performed after contaminated BC rinse, IL-1 beta production averaged 163 +/- 92 pg/ml when using reused dialyzers, but 1,820 +/- 880 pg/ml when using new dialyzers. After reuse with pyrogen-free BC-rinse and contaminated RUF no IL-1 beta synthesis was observed; however, when pyrogen-free BC-rinse and contaminated RUF was applied to new dialyzers, IL-1 beta synthesis averaged 1,620 +/- 1,200 pg/ml. We conclude that cytokine-inducing substances are retained inside the dialyzer, probably by adsorption to the membrane as well as to the protein layer covering the membrane and are still biologically active after sterilisation. Cytokine-inducing substances adsorbed to the protein layer can be partially removed by RUF. Finally, the protein layer on the membrane appears to reduce the convective transfer of cytokine-inducing substances from the dialysate into the blood compartment.

Basic fibroblast growth factor augments podocyte injury and induces glomerulosclerosis in rats with experimental membranous nephropathy

Podocyte injury is believed to contribute to glomerulosclerosis in membranous nephropathy. To identify the factors involved, we investigated the effects of basic fibroblast growth factor (bFGF), a cytokine produced by podocytes, on rats with membranous nephropathy (passive Heymann nephritis [PHN]). All rats received a daily i.v. bolus of 10 microg bFGF or vehicle from days 3-8 after PHN induction. In proteinuric PHN rats on day 8, bFGF injections further increased proteinuria. Podocytes of bFGF-injected PHN rats showed dramatic increases in mitoses, pseudocyst formation, foot process retraction, focal detachment from the glomerular basement membrane, and desmin expression. bFGF injections in PHN rats did not alter antibody or complement deposition or glomerular leukocyte influx. bFGF-injected PHN rats developed increased glomerulosclerosis when compared with control PHN rats. Also, bFGF induced proteinuria and podocyte damage in rats injected with 10% of the regular PHN-serum dose. None of these changes occurred in bFGF-injected normal rats, complement-depleted PHN rats or rats injected with 5% of the regular PHN serum dose. These divergent bFGF effects were explained in part by upregulated glomerular bFGF receptor expression, induced by PHN serum. Thus, bFGF can augment podocyte damage, resulting in increased glomerular protein permeability and accelerated glomerulosclerosis. This bFGF action is confined to previously injured podocytes. Release of bFGF from glomerular sources (including podocytes themselves) during injury may represent an important mechanism by which podocyte damage is enhanced or becomes self sustained.

Treatment of renal anemia by erythropoietin substitution. The effects on the cardiovascular system

Recombinant human erythropoietin (r-HuEPO) effectively corrects the anemia of end stage renal disease (ESRD). Development or aggravation of hypertension has been the most commonly reported side-effect of r-HuEPO treatment. Placebo controlled trials have shown incidence rates ranging from 16-21%. Renal failure itself obviously is a prerequisite in the pathogenesis of r-HuEPO-induced hypertension, since it was never observed in anemic patients without renal disease. Increased whole blood viscosity and/or reduced hypoxic vasodilatation due to the rise in hematocrit may play a role in the development of hypertension at high concentrations of hematocrit. However, at hematocrit levels around 30% additional hypertensinogenic effects of r-HuEPO treatment seem likely. Endothelin and prostanoids are possible mediators of this effect. Left ventricular hypertrophy (concentric and eccentric), which can be due to hypertension and anemia, is commonly observed in ESRD patients and has been shown to be a predictor of cardiac morbidity and mortality in these patients. Following correction of anemia with r-HuEPO measures of left ventricular hypertrophy decrease by about 18% within a year. Normalization, though, is generally not achieved and in patients with r-HuEPO induced hypertension the increase of blood pressure may oppose the beneficial effects of r-HuEPO treatment on cardiac hypertrophy.

Beta 2-microglobulin amyloidosis: why and how to look for it

Thirty years after the introduction of chronic dialysis into clinical practice, amyloidosis based on the precursor molecule beta 2-microglobulin (beta 2m-A) has emerged as an important complication of end-stage renal disease in patients on renal replacement therapies other than transplantation. For the individual patient, diagnosis of beta 2m-A is important to exclude other treatable causes of the symptoms, initiate symptomatic treatment, prevent possible life-threatening complications, and assign a high priority for transplantation. For the ESRD population as a whole, early specific diagnosis should help to assess the influence of various therapeutic modes on the development and course of beta 2m-A and to guide further the optimization of renal replacement therapy. Besides, sophisticated diagnostic techniques may yield valuable information on underlying pathogenetic mechanisms of beta 2m-A. Morphology, including immunohistochemistry, as the most definitive and specific diagnostic proof must rely on invasive procedures to obtain the appropriate material from clinically affected sites. Clinical assessment and imaging techniques such as x-ray and joint sonography suffer from non-specificity. Scintigraphic imaging of beta 2m-A after injection of radiolabelled beta 2-microglobulin is a non-invasive, specific, and highly sensitive way of diagnosis. Further refinement and more widespread use of this method can be expected to enhance the understanding of beta 2m-A pathogenesis and promote therapeutic and preventive efforts against this complication.

Minimally invasive diagnosis of renal artery stenosis by spiral computed tomography angiography

We prospectively compared in a blinded fashion spiral computed tomography angiography (CTA) with arteriography in 62 consecutive patients with suspected renal artery stenosis (RAS). For CTA 150 ml of contrast material were injected intravenously. Arteriography was performed by DSA technique with selective catheterization of renal arteries. Of the 157 visualized renal arteries 155 could be evaluated with DSA and a total of 157 with CTA. Sensitivity of CTA for RAS > or = 50% was 98% and the specificity was 94%. Comparison of the grade of stenosis as evaluated by DSA versus CTA showed: identical gradation in 59 arteries (DSA > or = 50%/CTA > or = 50%), underestimation by CTA in one artery (DSA 50 to 75%/CTA < 50%), and overestimation by CTA in six arteries (DSA < 50%/CTA 50 to 75%). Factors that may contribute to these differences include impaired renal function and possibly "underestimation" of ostial RAS by arteriography. One artery not evaluable by arteriography showed a 70% stenosis by CTA. CTA showed no major side effects. We conclude that CTA has the same accuracy for the diagnosis of RAS > or = 50% as arteriography. However, CTA is only minimally invasive, safe, and causes less discomfort to patients.

The use of epoetin beta in anemic predialysis patients with chronic renal failure

Two clinical studies were conducted to investigate the efficacy and safety of epoetin beta in 266 [corrected] anemic predialysis patients. Epoetin beta was administered subcutaneously either daily or thrice weekly. Mean duration of treatment was 211 days (interquartile range: 105 to 350 days).

RESULTS

Renal anemia could be corrected and the regular transfusion need could be eliminated in all patients. There was no difference in the dose requirement per week between daily and thrice weekly administration of epoetin beta. Regarding the entire study population, there was no acceleration of the progression of renal failure during epoetin beta treatment nor were there any notable changes in laboratory values other than retention values. Epoetin beta was safe and well tolerated; the most important adverse event was the development or aggravation of hypertension.

Angiotensin-converting-enzyme inhibitors suppress synthesis of tumour necrosis factor and interleukin 1 by human peripheral blood mononuclear cells

Administration of angiotensin-converting-enzyme (ACE) inhibitors reduce vascular proliferation following endothelial injury as well as progression of renal disease in various animal models. These effects might be due to interference with cytokines such as interleukin 1 (IL-1) or tumour necrosis factor alpha (TNF) since they have been implicated in regulating the effects of vascular cell growth factors such as fibroblast- and platelet-derived growth factors. We investigated the in vitro synthesis of IL-1 and TNF from human peripheral blood mononuclear cells (PBMC) in the presence of various ACE-inhibitors. Captopril dose-dependently suppressed the IL-1 beta-induced synthesis of TNF by 74% (P < 0.01) and the IL-1 beta-induced synthesis of IL-1 alpha by 60% (P < 0.01). Cytokine synthesis induced by lipopolysaccharide was less affected. At concentrations suppressing TNF and IL-1, captopril did not reduce the synthesis of complement C3 in the same cells. Enalapril and cilazapril also suppressed cytokine-induced cytokine synthesis. Ramipril, lisinopril, perindopril and spirapril had no significant effect on TNF synthesis suggesting that the effect was not related specifically to the inhibition of ACE. Accumulation of mRNA for IL-1 and TNF were not affected by captopril, suggesting a posttranscriptional effect. We conclude that certain ACE-inhibitors suppress IL-1 and TNF synthesis at a posttranscriptional level and might therefore influence cytokine-mediated cell growth.

Biocompatibility in hemodialysis: clinical relevance in 1995

Hemodialysis therapy for end-stage renal disease is still empirical even after more than 30 years of experience. Although long-term survival can now be assured in selected patients, clinical results tend to be disappointing. Hemodialysis therapy needs to be improved. Zealots of the biocompatibility school believe that this improvement will come from reducing undesirable consequences of blood membrane interaction, particularly complement activation. However, there is controversy over the clinical meaningfulness of biocompatibility when exclusively related to blood membrane interactions. Another dimension needs to be added, namely ultrapure dialysate to avoid subclinical chronic effects of activation of the cytokine cascade by bacterial fragments present in dialysate. While the pathogenesis of acute anaphylactoid reactions are understood and largely preventable, the relation of the chronic syndromes such as amyloidosis to the use of a particular membrane remain unproven. Prospective studies that will occupy at least a decade will be necessary to decide these issues.

Impaired endotoxin-induced interleukin-1 beta secretion, not total production, of mononuclear cells from ESRD patients

Lipopolysaccharide (LPS)-induced interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) production and secretion from peripheral blood mononuclear cells (PBMC) were determined in a longitudinal study with repeated measurements in PBMC from patients with chronic uremia not on hemodialysis (N = 8), end-stage renal disease (ESRD) patients (N = 8), and healthy controls (N = 7). ESRD patients were studied while using low-flux Cuprophan dialyzers and again using high-flux AN 69 dialyzers. Total (cell-associated plus secreted) LPS-induced IL-1 beta production was enhanced in uremic patients, but similar to controls in ESRD patients on Cuprophan. In contrast, LPS-induced IL-1 beta secretion (secreted amounts in % of total production) was similar to controls in uremic patients, but significantly reduced in ESRD patients on Cuprophan (P < 0.01). During AN 69 hemodialysis, LPS-induced total IL-1 beta production remained unchanged but IL-1 beta secretion increased significantly (P < 0.05) compared to Cuprophan dialysis. Increased IL-1 beta secretion coincided with a suppression in PGE2 synthesis (P < 0.02). Similarly, blockade of endogenous PGE2 by indomethacin increased LPS-induced IL-1 beta secretion (P < 0.01) but did not enhance total IL-1 beta production in PBMC from controls and patients on Cuprophan hemodialysis. Neither total production nor secretion of TNF alpha was different comparing the three study groups. We conclude that LPS-induced IL-1 beta secretion, but not total production, is impaired in PBMC from ESRD patients on long-term Cuprophan hemodialysis. This functional change in the PBMC response is specific for IL-1 beta, not due to uremia per se but hemodialysis-dependent and reversible. Hemodialysis with AN 69 suppresses endogenous PGE2 synthesis in PBMC which is associated with increased LPS-induced IL-1 beta secretion in the presence of unchanged total IL-1 beta production. We speculate that PGE2 could inactivate the IL-1 beta converting enzyme which is essential for processing and secretion of mature IL-1 beta.