High permeability haemofiltration improves peripheral blood mononuclear cell proliferation in septic patients with acute renal failure

BACKGROUND

Continuous veno-venous haemofiltration (HF) with high permeability (HP) haemofilters is a novel approach in the adjuvant therapy of septic patients. HP haemofilters are characterized by an increased pore size which facilitates the filtration of inflammatory mediators. The present study examines whether HP-HF has an impact on peripheral blood mononuclear cell (PBMC) proliferation and whether ultrafiltrate can alter PBMC function in isolates from healthy volunteers.

METHODS

Twenty-eight septic patients with acute renal failure were randomly allocated to either HP-HF or conventional HF (C-HF). HP-HF was performed with a newly developed high-flux polyamide membrane (P2SH) with a nominal cut-off point of 60 kDa. For C-HF, a high-flux polyamide haemofilter (Polyflux 11S; cut-off, 30 kDa) was used.

RESULTS

Septic patients demonstrated a significantly reduced proliferation of anti-CD3-stimulated PBMCs compared to healthy controls (P = 0.016). Initiating HF led to a restoration of the PBMC proliferation in HP-HF but not in C-HF. Exposing PBMCs isolated from healthy donors to ultrafiltrates from patients with sepsis demonstrated a significant suppressive effect of HP ultrafiltrates on the anti-CD3-stimulated PBMC proliferation (P = 0.011). Ultrafiltrate from patients with sepsis who received C-HF had no impact on PBMC proliferation.

CONCLUSION

HP-HF restores PBMC proliferation in septic patients probably by eliminating immunomodulatory mediators. HP-HF may represent a new renal replacement therapy able to modulate PBMC function in sepsis.

Cyclosporin C2hour monitoring after renal transplantation

Therapeutic drug monitoring of cyclosporin A (CsA) is essential because of its variable pharmacokinetics in individual patients and its narrow therapeutic window. In the past, standard trough level (C0) monitoring has been used, and although this method is currently the routine strategy, it has been shown that a single blood concentration measurement 2 hours after CsA administration (C2hour) is a significantly more accurate predictor of drug exposure and clinical events than trough concentrations. The CsA absorption profiling, in particular the measurement of C2hour, is a much more sensitive approach to assessing the pharmacokinetics and predicting the clinical effect in the individual patient. However, there are limited prospective data available examining the risks and benefits of C2hour monitoring in renal transplant recipients. Most studies focus on the early post-transplant phase, but there is little experience with C2hour monitoring in maintenance patients. Our experience in 127 stable long-term renal allograft recipients suggests that the therapeutic window for C2hour levels in patients during maintenance is lower than previously anticipated. Repeat determinations of both C0 and C2hour levels in 46 patients to determine precision of C2hour monitoring showed a high intrapatient variability. We observed only a slightly better coefficient of variation for C2hour than for C0 in repeat determinations. This suggests that drug monitoring using C2hour levels in transplant patients may provide a more accurate and reliable measure of drug exposure in the individual patient. However, CsA absorption showed only a weak correlation with dose during repeated measurements, suggesting high variability in absorption in these stable patients. We conclude that an adequate C2hour level soon after transplantation is associated with a reduced risk of acute rejection in adult renal transplant recipients. It is important to identify slow and poor absorbers in the initial phase after transplantation in order to avoid inappropriate increases in CsA dose. In maintenance patients, C2hour values between 500 and 600 ng/ml are effective and safe for providing effective rejection prophylaxis. Although mean C2hour levels do not seem to identify patients at risk of rejection, they may help to identify excessive immunosuppression and to improve long-term survival by reducing CsA toxicity.

Pharmacodynamics of FTY720, the first member of a new class of immune-modulating therapeutics in transplantation medicine

FTY is a novel immunomodulator currently undergoing clinical investigation and has the potential of improving immunosuppressive therapy after organ transplantation. Previous experimental studies in animals have shown that FTY has a unique mechanism of action. We have studied the pharmacodynamic effects of FTY in stable renal allograft recipients taking part in a phase I clinical trial. As in various animal models including non-human primates, a single oral dose of FTY (0.25 - 3.5 mg) significantly reduced peripheral lymphocyte count by 30 - 70%. The peripheral lymphocyte count returned to baseline within 24 hours. Only in those patients treated with the highest dose of FTY (3.5 mg), did peripheral lymphopenia persist for more than 96 hours. FTY reduced all lymphocyte subsets, T cells more than B cells and CD4+ cells more than CD8+ cells. The reduction in CD3+CD62L+ cell counts was more pronounced, whereas CD3+CCR5+ cell counts were less affected in comparison to the total number of CD3+ lymphocytes. We found only slightly increased apoptosis rates (< 5%) in peripheral lymphocytes, and this change does not explain the marked reduction in lymphocyte count. In cultured human lymphocytes only suprapharmacological doses of 10 microM FTY induced apoptosis (20.6 +/- 2.8%) after a 4-h incubation. More important, clinically relevant doses of 0.1 microM FTY increased lymphocyte mobility 2-fold. No effect of FTY on anti-CD3mAb-stimulated lymphocyte proliferation was detected and there was no change in phagocytosis rates in whole-blood cultures incubated with FTY. Further studies are necessary to investigate the mechanism of action of FTY in detail.

Intermittent high-permeability hemofiltration modulates inflammatory response in septic patients with multiorgan failure

BACKGROUND/AIM

Continuous venovenous hemofiltration with high-permeability hemofilters is a novel approach in the adjuvant therapy of septic patients. High-permeability hemofilters are characterized by an increased pore size which facilitates the filtration of inflammatory mediators. The present study examines whether intermittent high-permeability hemofiltration has an immunomodulatory effect on polymorphonuclear leukocytes and mononuclear cells.

METHODS

Twenty-eight septic patients with acute renal failure were randomly allocated to either receive intermittent high-permeability or conventional hemofiltration. Intermittent high-permeability hemofiltration consisted of a daily 12-hour course of high-permeability hemofiltration alternated by conventional hemofiltration. For high-permeability hemofiltration, a newly developed high-flux polyamide membrane (P2SH) with a nominal cutoff point of 60 kD was used. For conventional hemofiltration a high-flux polyamide hemofilter (Polyflux 11S, cutoff point 30 kD) was used.

RESULTS

The polymorphonuclear leukocyte phagocytosis activity before starting hemofiltration was almost double the rate of healthy controls in both groups (p < 0.001). The phagocytosis rate decreased significantly during the course of intermittent high-permeability hemofiltration (p < 0.05), whereas the values remained unchanged in the conventional hemofiltration group. Incubation of high-permeability filtrates with blood from healthy donors resulted in a significant induction of phagocytosis (p < 0.001), whereas conventional filtrates had no phagocytosis-stimulating effects. In addition, incubation of healthy-donor mononuclear cells with high-permeability but not conventional filtrates resulted in a significant tumor necrosis factor alpha release (p < 0.001).

CONCLUSIONS

Intermittent high-permeability hemofiltration is a novel extracorporeal elimination modality which exhibits immunomodulatory effects on leukocytes, attenuating polymorphonuclear neutrophil phagocytosis. Further studies are necessary to elucidate whether these effects translate in a clinical improvement in patients suffering from sepsis.

Pharmacodynamics of single doses of the novel immunosuppressant FTY720 in stable renal transplant patients

FTY720, a new and potent immunosuppressant, causes in animal models a rapid, reversible reduction of all subsets of peripheral blood lymphocytes, inducing their migration to secondary lymphoid organs. In this human phase I trial, the pharmacodynamics of single oral doses of FTY720 were evaluated. A randomized, double-blind, placebo-controlled, time-lagged study of six different single ascending oral doses of FTY720 ranging from 0.25 to 3.5 mg was conducted in stable renal transplant patients receiving a cyclosporine-based regimen. Absolute and subset lymphocyte counts, as well as absolute differential leukocyte counts, were determined by differential blood counts and flow cytometry at screening and multiple intervals thereafter. A pharmacodynamic model was established. Twenty-four single doses of FTY720 that were administered caused a transient, reversible pan-lymphopenia within 4 h. Lymphocyte subgroup analysis revealed that almost all subsets declined, with CD4- and CD45RA-positive cells being affected the most. Natural killer cells, granulocytes and monocytes were not influenced by FTY720. The lymphocyte count returned to baseline within 72 h in all dosing cohorts except the highest. Pharmacokinetik/pharmacodynamic modelling revealed a nonlinear dose effect and resulted in a good fit with observed values. These data show that FTY720 is highly effective in humans, with single oral doses of FTY720 ranging from 0.25 to 3.5 mg causing a reversible selective panlymphopenia.

Impact of PGE1 on cyclosporine A induced up-regulation of TGF-beta1, its receptors, and related matrix production in cultured mesangial cells

Transforming growth factor-beta1 (TGF-beta1) plays a major role in cyclosporine A (CsA) induced glomerulosclerosis. We have recently shown that CsA up-regulates the expression of TGF-beta1 and its receptors type I (TbetaR-I) and type II (TbetaR-II) in rat mesangial cells (MCs). Prostaglandins of the E series (PGEs) are known to exert substantial anti-fibrotic effects. Here, we assessed the effect of PGE1 on CsA induced up-regulation of TGF-beta1, TbetaR-I, TbetaR-II and related matrix production in MCs. Co-incubation with PGE1 reduced CsA induced up-regulation of TGF-beta1 and TbetaR-II at the mRNA and protein level. Alike, PGE1 reduced TbetaR-I protein expression, which is posttranscriptionally up-regulated by CsA. Whereas a low PGE(1) concentration decreased CsA induced production of fibronectin (FN) and plasminogen activator inhibitor type-1 (PAI-1), a higher PGE1 concentration did not change FN production, but further increased PAI-1 production. In vivo studies will show, whether treatment with PGE1 analogues will be useful in preventing CsA induced glomerulosclerosis.

Cyclosporine A up-regulates the expression of TGF-beta1 and its receptors type I and type II in rat mesangial cells

BACKGROUND

Chronic cyclosporine A (CsA) nephropathy is a well described side effect of CsA treatment. CsA has been shown to induce the synthesis of extracellular matrix (ECM) proteins in mesangial cells (MCs) in vitro, and glomerulosclerosis in vivo. Transforming growth factor-beta1 (TGF-beta1) is a potent stimulus for the synthesis of ECM proteins in MCs. We investigated whether CsA up-regulates the expression of TGF-beta1 and its receptors type I (TbetaR-I) and type II (TbetaR-II) in cultured rat MCs, and whether this effect translates into enhanced matrix protein accumulation.

METHODS

Resting MCs were incubated in the presence or absence of CsA and anti-TGF-beta1 antibodies. Time- and concentration-dependent expression of TGF-beta1, TbetaR-I and TbetaR-II were measured at both the mRNA (competitive reverse transcription PCR) and protein level (enzyme-linked immunosorbent assay (ELISA) and western blotting). Fibronectin (FN) and plasminogen activator inhibitor type-1 (PAI-1) synthesis were measured by ELISA.

RESULTS

Compared with untreated controls, CsA stimulated mRNA production of TGF-beta1 (maximum at 72 h, 500 ng/ml CsA: 2.1+/-0.5-fold, P<0.001) and TbetaR-II (maximum at 72 h, 1000 ng/ml CsA: 2.4+/-0.4-fold, P<0.005) time- and dose-dependently. TbetaR-I mRNA concentrations remained unchanged. Protein concentrations were analysed at 96 h: TGF-beta1, 220+/-32 vs 86+/-24 pg/ml, P<0.001 (500 ng/ml CsA vs control); TbetaR-I, 2.0+/-0.5-fold, P<0.005 (1000 ng/ml CsA vs control); TbetaR-II, 2.5+/-0.7-fold, P<0.05 (1000 ng/ml CsA vs control). CsA (500 ng/ml) also enhanced the production of FN (1.6-fold, P<0.05) and PAI-1 (2.0-fold, P<0.05). Co-incubation with neutralizing anti-TGF-beta1 antibodies reduced (P<0.05) CsA-induced expression of TbetaR-I (1.0+/-0.1-fold), TbetaR-II (1.3+/-0.1-fold) and PAI-1 (1.3-fold), but not FN production (1.6-fold).

CONCLUSIONS

Pharmacologically relevant concentrations of CsA time- and dose-dependently up-regulate the expression of TGF-beta1 and, via autocrine mechanisms, its receptors type I and II in rat MCs. Whereas up-regulation of PAI-1 is mediated by TGF-beta1, up-regulation of FN is-at least in part-either directly induced by CsA or mediated by factors other than TGF-beta1.

Impact of the variability of cyclosporin A trough levels on long-term renal allograft function

BACKGROUND

Among renal allograft recipients, there is a considerable variability in cyclosporin A (CsA) trough levels. Some of the CsA metabolites are pharmacologically active. The variability of polyclonal CsA trough levels may contribute to the fact that long-term renal allograft survival is still not satisfactory. In a retrospective, single-centre study, we investigated the influence of the variability of polyclonal CsA trough levels on long-term renal allograft function.

METHODS

Patients (n=381) received double immunosuppression consisting of CsA and methylprednisolone (MP). For each patient the CsA coefficient of variation (CCV) and the mean CsA trough level during the observation period (5 years) were calculated. Based on receiver operating characteristic (ROC) analysis, patients were divided into two groups: group I, CCV <28.05%, n=231; group II, CCV >28.05%, n=150. Additionally, patients were divided into three groups according to their mean CsA trough level: group A, <270 ng/ml, n=50; group B, 270-370 ng/ml, n=282; group C: >370 ng/ml, n=49.

RESULTS

Compared to group I, patients in group II experienced a higher incidence of acute rejection episodes (40.7% vs 29.4%, P=0.02), reduced 5-year graft survival (81.1% vs 93.3%, P=0.002), and higher serum creatinine levels (1.7+/-1.2 mg/dl vs 1.4+/-0.5 mg/dl, P=0.03). In patients with low mean CsA trough levels, the incidence of acute rejection episodes was elevated (group A vs B, 50.0% vs 30.9%, P=0.008) and 5-year graft survival was reduced (group A vs B, 79.8% vs 89.5%, P=0.005). Multiple logistic regression analysis confirmed that the risk of graft failure within 5 years after transplantation was markedly elevated in group II (RR: 6.2, P=0.013) and in group A (RR: 8.9, P=0.008). Whereas the effect of CCV on 5-year graft survival was still evident in patients with normal or high mean CsA trough levels (>270 ng/ml, 81.9% vs 94.8%, P=0.0005), graft survival was independent from CCV in patients with low mean CsA trough levels (<270 ng/ml, 77.0% vs 81.7%, P=NS).

CONCLUSIONS

Both, the intra-individual variability and the mean of polyclonal CsA trough levels influence long-term renal allograft survival. Targeting at sufficiently high mean CsA levels with a low intra-individual variability may help to further improve long-term renal allograft survival.

Immunohistochemical double-staining of renal allograft tissue: critical assessment of three different protocols

Quantitative analyses of renal allograft tissue using immunohistochemical double-staining could be a useful tool to extend the existing knowledge on renal allograft immunopathology. Due to technical reasons, this method has been only rarely applied in the past. The use of indirect immunohistochemistry for double-staining bears the risk of nonspecific cross reactions between the two staining sequences. To date, various procedures have been refined to avoid such cross reactions. Here we assessed the validity of three different protocols for indirect immunohistochemical double-staining on frozen sections of renal transplant biopsies ( n=12). Both colocalized antigens and antigens with a non-overlapping distribution were stained according to each of the three protocols. Differentiation between the two staining sequences was achieved by employing different colored substrates of alkaline phosphatase (protocol 1), different enzymes (peroxidase and alkaline phosphatase) together with the use of 3,3'-diaminobenzidine-tetrahydrochloride substrate in the first staining sequence (protocol 2), or primary antibodies from different species (protocol 3). Sensitivity and specificity of each protocol were determined by quantitative comparison with control single-stainings of adjacent sections. Sensitivity of the first staining sequence was about 100% with each of the three protocols investigated. In the second staining sequence, sensitivities of protocols 1 (50%) and 2 (54-66%) were much lower than of protocol 3 (100%). Specificity of the second staining sequence was only 44% with protocol 1 compared with 98% with protocol 2 and 100% with protocol 3. In conclusion, protocols 1 and 2 are not recommended for quantitative double-staining analyses. In contrast, protocol 3 provided maximum sensitivity and specificity, even for antigens that are colocalized on the same cell type. Thus, the use of primary antibodies from different species is by far the most reliable technique for quantitative double-staining analyses in renal allograft tissue.

Prognostic value of the Banff classification

We evaluated whether classification of renal allograft biopsies according to the Banff schema is a predictive parameter for graft survival. All patients who received renal transplants between 1980 and 1994 at the University of Erlangen-Nuremberg (n = 1141) were included. Patients who had undergone a renal biopsy (n = 306) were divided into groups according to the Banff classification. We observed a correlation (P < 0.05) between biopsy findings and the following patient characteristics: donor/recipient age, donor/recipient gender, panel reactive antibodies, maintenance immunosuppression, and primary renal disease. Compared to patients who did not undergo renal biopsy (55.9%), 5-year graft survival was reduced in patients with moderate acute rejection defined by tubulitis (20.6%, P = 0.03) or arteritis (0%; P < 0.0001) and in patients with severe acute rejection (24.4%, P < 0.0001).

CONCLUSIONS

(1). The Banff classification is a predictive parameter for renal allograft survival. (2). Certain characteristics predispose patients to certain biopsy findings.

FTY 720A mediates reduction of lymphocyte counts in human renal allograft recipients by an apoptosis-independent mechanism

The novel immunosuppressive compound FTY 720A posseses a mode of action which is different from all other immunosuppressive drugs. The most prominent feature is a reversible decrease in peripheral lymphocyte counts observed in animal experiments. We investigated in the first human trial (phase 1) whether FTY 720A induces apoptosis of peripheral blood mononuclear cells (PBMC) in stable renal allograft recipients. Monitoring of lymphocyte counts revealed a significant and dose-dependent decrease within 6 h post-FTY 720A dose: placebo 5.1%; 0.25 mg 36.4%; 0.5 mg 40.8%; 0.75 mg 39.4%; 1 mg 45.8%; 2 mg 67.2%; 3.5 mg 64.9%. PBMC apoptosis rates did not change, as determined before intake of FTY 720A and 2 h, 6 h, 24 h and 96 h post-FTY 720A dose. We detected no significant difference in apoptosis rates between patients who received placebo or FTY 720A. However, in vitro experiments showed that high concentrations of FTY 720 A induced apoptosis in human PBMC.

Occult thyroid pathology in a child with acquired immunodeficiency syndrome. Case report and review of the drug-related pathology in pediatric acquired immunodeficiency syndrome

A 11-year-old boy with acquired immunodeficiency syndrome (AaS), Varicella-zoster virus (VZV) infection and long-term antiviral treatment suffered from a disorder of contractility of the left ventricle of the heart. Following severe unmanageable vomiting, the patient died and the postmortem examination showed marked involution of the lymphatic system, multiple foci of fibrosis of both ventricles of the heart, and regressive changes of the thyroid gland. Biochemical values of the thyroid gland function were, however, not altered. Neither human immunodeficiency virus-related p24 antigen, nor VZV DNA sequences were found in the thyroid gland. Regressive changes of the thyroid gland can probably occur before its function fails. By analyzing the possible etiologies, the endocrine toxicity of a long-term antiviral treatment should be taken into account.

CD95 (APO-1/Fas) expression on naive CD4(+) T cells increases with disease progression in HIV-infected children and adolescents: effect of highly active antiretroviral therapy (HAART)

We studied the expression of the CD95 receptor (APO-1/Fas) on peripheral blood T cell subpopulations in 37 HIV-1-infected children and adolescents stratified according to disease stage or antiretroviral treatment regimen and compared the results to values obtained in 12 healthy age-matched control subjects. CD95 expression on CD45RA(+) CD45RO(-)/CD62L(+) (resting/naive) and CD45RO(+) CD45RA(-) (primed/memory) CD4(+) and CD8(+) T cells was assessed quantitatively by four-color and three-color flow cytometry. CD4(+) T cells contained a population of predominantly CD95(-) resting/naive cells and a population of CD95(high) primed/memory cells, whereas CD8(+) T cells had a more uniform pattern of CD95 expression. The percentage of CD95(+) CD4(+) T cells increased with disease progression because of both an augmented median fluorescence intensity on resting/naïve cells and an increased percentage of CD95(high) cells. Patients with highly active antiretroviral combination therapy who maintained stable CD4 counts in the presence of elevated plasma viral load had nearly normal numbers of CD95(-) resting/naive CD4(+) T cells, whereas CD95 expression in the CD8(+) T cell subset was still elevated compared with control subjects. Low CD95 expression on resting/naive CD4(+) T cells may therefore indicate a low risk for disease progression in antiretrovirally treated and untreated patients.

TNF-alpha and IL-1alpha induce apoptosis in subconfluent rat mesangial cells. Evidence for the involvement of hydrogen peroxide and lipid peroxidation as second messengers

Apoptosis of mesangial cells (MC) plays a role in glomerulonephritis (GN). In this study we investigated cytokine-induced apoptosis of cultured rat MC by morphological and biochemical features. TNF-alpha and IL-1alpha induced apoptosis in rat MC in a time- and concentration-dependent fashion. RT-PCR experiments revealed that MC express the TNF-receptor 1 (p60) gene constitutively. TNF-alpha as well as IL-1alpha stimulated the production of reactive oxygen species (ROS) and induced lipid peroxidation. Coincubation with catalase inhibited TNF-alpha and IL-1alpha induced apoptosis as well as lipid peroxidation. TNF-alpha, but not IL-1alpha increased the expression of c-jun. These results provide evidence that TNF-alpha and IL-1alpha induce apoptosis in rat MC with hydrogen peroxide and lipid peroxidation as second messengers. Increased c-jun expression may be a downstream intracellular signal of TNF-alpha-, but not IL-1alpha-induced apoptosis.

Age-matching in renal transplantation

BACKGROUND

So far, the combined influence of donor age and recipient age on renal allograft survival has not been investigated sufficiently. In this retrospective single-centre study we analysed whether the influence of donor age and recipient age on renal allograft survival are dependent on each other.

METHODS

Data from 1269 cadaveric renal allograft transplantations were evaluated. Paediatric donors (<15 years) and paediatric recipients (<15 years) were excluded. Donors and recipients were divided by age: young donors (yd, </=55 years, n=1093), old donors (od, >55 years, n=176), young recipients (yr, </=55 years, n=1058), and old recipients (or, >55 years, n=211). Functional and actual long-term graft survival (8 years) within the four resulting groups was determined: yd/yr (n=926), yd/or (n=167), od/yr (n=132), and od/or (n=44).

RESULTS

Univariate analysis showed that long-term graft survival of both, kidneys from young donors (functional, 66.1 vs 52.2%, P=0.004; actual, 53.3 vs 46.2%, P=0.065) and kidneys from old donors (functional, 68.7 vs 22.5%, P=0.07; actual, 57.1 vs 20.8%, P=0.15) was better in old recipients as compared to young recipients. Multivariate regression analysis revealed that actual graft survival of kidneys from old donors was significantly reduced in young recipients (od/yr) as compared to all other groups (P=0.001; RR, 1. 97; 95% CI, 1.32-2.94). In this group of patients, graft loss was mainly due to acute (33.7%) and chronic (24.0%) rejection.

CONCLUSION

Transplantation of kidneys from 'old' donors into 'young' recipients should be avoided, and these kidneys should be given to age-matched recipients.

Decreased mechanical stability of neonatal red cell membrane quantified by measurement of the elastic area compressibility modulus

Previous studies suggest that early loss of membrane might account for the shortened life-span of neonatal red blood cells (RBC). The elastic area compressibility modulus describes the force required to achieve a defined expansion of the membrane and is thus a suitable intrinsic material property to describe mechanical stability of the RBC membrane. We studied RBC in eight cord blood samples (representing fetal blood), ten 5-day old full-term neonates and seven healthy adults. The RBC were suspended in hypotonic buffer solution and investigated using a modification of the micropipet technique by Evans et al. Cord blood RBC (204+/-33 dyn/cm) and neonatal RBC (209+/-11 dyn/cm) showed a 25% lower elastic area compressibility modulus than adult cells (278+/-26 dyn/cm; p < 0.05). Thus, less force was necessary for expansion of neonatal RBC membrane. We conclude that neonatal RBC are more susceptible to mechanical damage of their membrane than adult cells.