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U Kunzendorf

Publications and source records attributed to U Kunzendorf.

At least 19 recordsLinked to original sources
PubMed2006

CYP3A5 genotype markedly influences the pharmacokinetics of tacrolimus and sirolimus in kidney transplant recipients.

It is currently not clear whether the concentration-time curves of the immunosuppressants differ with respect to the CYP3A5, MDR1, or MRP2 genotype in dose-adapted stable kidney transplant patients. Dose/trough concentration ratios were obtained in 134 tacrolimus and 20 sirolimus-treated patients, and plasma concentration-time profiles were obtained from 16 (tacrolimus) and 10 (sirolimus) patients. Genotyping was carried out for CYP3A5 6986A>G; ABCB1 2677G>T/A, 3435C>T and ABCC2 -24C>T; 1249G>A; 3972C>T. Dose/trough concentration ratios were 0.67+/-0.3 and 1.36+/-0.73 x 10(3) l (P<0.00001) for tacrolimus and 0.42+/-0.17 and 0.84+/-0.46 x 10(3) l (P=0.18) for sirolimus in CYP3A5 non-expressors and expressors. The unadjusted tacrolimus area under curve (AUC)(0-12) was 106.8+/-17.5 ng/ml x h compared with 133.3+/-42.2 ng/ml x h (P=0.37) without affecting serum creatinine. Mean unadjusted AUC(0-24) of sirolimus did not differ significantly either. Therefore, CYP3A5 expressor status and not transporter variants is a main determinant of oral clearance, particularly for tacrolimus. Dose adaptation according to trough levels, however, appears to be sufficient to maintain similar concentration-time profiles.

Adult↗
PubMed2006

FTY720/cyclosporine regimens in de novo renal transplantation: a 1-year dose-finding study.

FTY720 is a novel immunomodulator being investigated for rejection prophylaxis in renal transplantation when combined with full-dose cyclosporine (CsA; FDC). This 1-year phase II study compared FTY720 plus FDC (Neoral) with FTY720 plus reduced-dose CsA (RDC) and mycophenolate mofetil (MMF) plus FDC in de novo renal transplant patients. Patients were randomized 2:2:2:1 to FTY720 5 mg plus RDC (n = 72); FTY720 2.5 mg plus RDC (n = 74); FTY720 2.5 mg plus FDC (n = 76); or MMF plus FDC (n = 39) for 12 months. CsA exposure in the RDC group was reduced on average by 50% as assessed by C(2) monitoring. The primary efficacy endpoint was the composite incidence of biopsy-proven acute rejection (BPAR), graft loss, death or premature study discontinuation. The incidences for this composite endpoint were 24% and 22%, respectively, for FTY720 5 mg plus RDC and FTY720 2.5 mg plus FDC versus 39% for MMF plus FDC. Patients receiving FTY720 2.5 mg plus RDC were discontinued from treatment due to risk of under-immunosuppression. FTY720 2.5 mg plus FDC and FTY720 5 mg plus RDC were safe and effective in de novo renal transplant patients over 12 months.

Adult↗
PubMed2004

[Infections under immunosuppressive therapy following organ transplantation].

The risk to acquire opportunistic infections is clearly increased in patients receiving immunosuppressive therapeutic regimens following organ transplantation or during treatment of autoimmune disorders. The modulation of the immune system can alter the clinical symptoms and the course of infectious diseases, including diagnostic signs such as fever or pathological changes in radiographs or blood cell counts. However, a rapid diagnosis and start of treatment is essential in these patients. Thus, a correct interpretation of even mild symptoms in the initial phase of an infectious disease is essential for establishing a diagnosis and initiation of a therapy at an early stage. Therefore, it is necessary that the clinical hallmarks of these diseases are widely known and that physicians treating these patients cooperate closely with transplant centers.

Biopsy↗
PubMed2003

Simultaneous hemodialysis during coronary angiography fails to prevent radiocontrast-induced nephropathy in chronic renal failure.

BACKGROUND: Radiocontrast medium- (RM) associated nephrotoxicity continues to be a common cause of acute renal failure and may lead in patients with pre-existing chronic renal insufficiency even to end-stage renal failure requiring chronic dialysis. Since extracorporeal removal of RM after RM administration has been shown to be effective but does not prevent radiocontrast-induced nephropathy, the effect of a simultaneous dialysis during RM administration on renal function is not clear. METHODS: In a prospective, randomized and controlled trial, we studied the effect of a 4-hour online dialysis during RM (iomeprol) application in patients with advanced chronic renal failure (serum creatinine > or = 3 mg/dl) undergoing coronary angiography. All patients received hydration with saline before and after standardized coronary angiography and were randomized to receive a simultaneous high-flux hemodialysis (7 patients, HD group) or to control group (10 patients). 24-hour creatinine clearance (CrCl) was measured in all patients before, 1 week and 8 weeks after coronary angiography. The clinical follow-up comprised 8 weeks after RM application. RM plasma levels were measured in both groups 15, 30, 60 minutes, 2, 4, 12, 24, 48 and 72 hours after application by high-pressure liquid chromatography. RESULTS: At baseline, CrCl (19 +/- 10 vs 17 +/- 7 ml/min), percentage of diabetics (57 vs 70%) and dose of RM (77 +/- 27 vs 86 +/- 21 ml) were similar in both groups. Pharmacokinetics: Total clearance of iomeprol was significantly higher (54 +/- 15 vs 20 +/- 12 ml/min, p < 0.001) and the area under curve (AUC) was significantly lower (23 +/- 10 g x h/l vs 94 +/- 57 g x h/l, p < 0.001) in the HD group compared to control group. RM peak plasma levels 15 min after application were not different in both groups (3.0 +/- 1.1 vs 4.2 +/- 1.7 mmol/l, NS), however, significantly lower 60 min (1.6 +/- 0.4 vs 3.7 +/- 1.5 mmol/l, p < 0.01) and 240 min (0.7 +/- 0.3 vs 2.3 +/- 0.7 p < 0.001) after angiography. CLINICAL RESULTS: CrCl showed no difference 1 week (24 +/- 11 vs 19 +/- 9 ml/min, ns) and 8 weeks (24 +/- 5 vs 20 +/- 9 ml/min, NS) after angiography from baseline or between the groups. In each group, 2 patients developed end-stage renal disease and requested permanent dialysis during the 8-week follow-up. CONCLUSION: Simultaneous dialysis reduces AUC of iomeprol significantly, however, does not influence plasma peak concentration after angiography. Renal function and incidence of end-stage renal failure were not influenced by online-dialysis.

Acute Kidney Injury↗
PubMed2003

Determination of the pharmacokinetics of cerivastatin when administered in combination with sirolimus and cyclosporin A in patients with kidney transplant, and review of the relevant literature.

OBJECTIVE: Therapy of elevated cholesterol serum concentrations is often necessary in patients with kidney transplants. However, the pharmacokinetics of HMG-CoA reductase inhibitors when administered in combination with sirolimus and cyclosporin A (CsA) have not been determined. The aim of this study was to investigate the pharmacokinetics of cerivastatin when administered in combination with sirolimus in patients with kidney transplants, and to review the literature with regard to the differences in pharmacological behavior between sirolimus, CsA and tacrolimus. METHODS: Patients (n = 7) with a stable and functioning kidney transplant and elevated LDL cholesterol serum concentrations were included in the study. After an observation period of 3 months, and whilst receiving sirolimus and CsA, cerivastatin (0.2 mg daily) was administered for a period of 3 months. Pharmacokinetic parameters were calculated on Day 1 and 3 months after initiation of cerivastatin therapy. Routine laboratory parameters and clinical adverse events were monitored throughout the study period. RESULTS: Single-dose cerivastatin AUC was 2 to 3-fold higher in comparison to published values obtained in healthy subjects. The accumulation ratio of cerivastatin (after 3 months/ Day 1) was 1.6. Sirolimus and CsA trough levels, and the sirolimus AUC did not differ after single dose and multiple doses of cerivastatin. CONCLUSIONS: The combination therapy of cerivastatin with sirolimus and CsA leads to a significant increase in cerivastatin exposure. Additional drug monitoring of sirolimus and CsA is not necessary.

Adult↗
PubMed2001

Dose optimization of mycophenolate mofetil when administered with a low dose of tacrolimus in cadaveric renal transplant recipients.

BACKGROUND: Supplementation of immunosuppressive therapy with mycophenolate mofetil (MMF) has been found to reduce the rate of acute rejection in renal transplantation. We report a dose-finding study for MMF when administered in combination with low-dose tacrolimus and corticosteroid prophylaxis in cadaveric renal transplant recipients. METHODS: Two hundred thirty-two patients at 16 centers were enrolled in this randomized, parallel-group study. The three treatment groups were tacrolimus and corticosteroids (MMF-0 group, n=82); tacrolimus, corticosteroids, and 1 g of MMF daily (MMF-1 g group, n=79); and tacrolimus, corticosteroids, and 2 g of MMF daily (MMF-2 g group, n=71). Study duration was 6 months, and patients were followed up for patient and graft survival for 12 months. RESULTS: At 6 months posttransplantation, daily doses of 1 g and 2 g of MMF were associated with significantly lower rates of acute rejection compared with tacrolimus alone. The Kaplan-Meier rates were 48.5%, 24.9%, and 22.9%, respectively, for the three treatment groups when acute rejection was determined by clinical criteria (P=0.007). At month 12, patient survival rates were 100%, 97.5%, and 97.2% and graft survival rates were 90.2%, 92.4%, and 93.0% for the MMF-0 group, MMF-1 g group, and the MMF-2 g group, respectively. Gastrointestinal adverse events and leukopenia were higher in the MMF groups, especially in the MMF-2 g group (P<0.05). CONCLUSIONS: Low-dose tacrolimus combined with a MMF dose of 1 g daily and corticosteroids provided an optimized efficacy and safety profile. A higher dose of MMF (2 g) was associated with greater toxicity without a significant improvement in efficacy.

Adrenal Cortex Hormones↗
PubMed2001

The immune dysregulatory compound mercuric chloride induces integrin-mediated T-lymphocyte adhesion.

Exposure of Brown Norway rats to mercuric chloride induces systemic autoimmunity, involving T- and B-lymphocyte activation, (auto-)antibody production and multiorgan inflammation. Several divalent metal ions, such as Mg2+ and Mn2+, can activate binding of integrins to their ligands, thus causing lymphocyte adhesion. To test the hypothesis that Hg2+ acts in a similar way, we studied the effect of HgCl2 on integrin-mediated T-cell adhesion. HgCl2 induced cell-cell aggregation of human T lymphoblasts. Exposure of a human T-cell clone to HgCl2 for 1 hr enhanced, in a dose-dependent way, cell binding to fibronectin (FN) and to intercellular adhesion molecules (ICAM) -1, -2 and -3. Furthermore, HgCl2 induced strong binding of Jurkat T cells to FN. These effects of HgCl2 were of similar magnitude as the effects of phorbol 12-myristate 13-acetate (PMA) or MnCl2. Studies using blocking antibodies indicated the involvement of CD11a in binding to ICAMs, and of CD49d, CD49e, and CD29 in binding to FN. Adhesion to FN induced by HgCl2 or by PMA, but not by MnCl2, was dependent on temperature and on extracellular Ca2+ or Mg2+. Addition of cytochalasin B enhanced synergistically the FN adhesion induced by MnCl2, whereas the effects of PMA and HgCl2 were not modified. These results indicate that Hg2+ is a potent activator of T-cell adhesion, mediated by several integrins and ligands. In contrast to the effect of MnCl2, HgCl2-induced cell adhesion probably involves an intracellular pathway. Activation of integrins by HgCl2 may play an important role in activation and migration of leucocytes involved in HgCl2-induced immune dysregulation in vivo.

Actins↗
PubMed2000

The HTLV-I tax protein transcriptionally modulates OX40 antigen expression.

OX40 is a member of the TNF receptor family, expressed on activated T cells. It is the only costimulatory T cell molecule known to be specifically up-regulated in human T cell leukemia virus type-I (HTLV-I)-producing cells. In a T cell line, OX40 surface expression was shown to be induced by HTLV-I Tax alone. To understand molecular mechanisms of OX40 gene regulation and modulation by HTLV-I Tax, we have cloned the human OX40 gene and analyzed its 5'-flanking region. By reporter gene analysis with progressive 5' deletions from nucleotides -1259 to -64, we have defined a 157-bp DNA fragment as a minimal promoter for constitutive expression. In addition, we show that in the OX40+ cell line, Co, Tax is able to further increase OX40 surface expression. Up-regulation of OX40 promoter activity by Tax requires two upstream NF-kappaB sites, which are not active in the constitutive OX40 expression. Their deletion abrogates Tax responsiveness in reporter gene analysis. The site-directed mutagenesis of each NF-kappaB site demonstrates that cooperative NF-kappaB binding is a prerequisite for Tax-directed activity as neither site alone is sufficient for a full Tax responsiveness of the OX40 promoter. Upon Tax expression, both sites bind p65 and c-Rel. These data provide new insight into the direct regulation of OX40 by Tax and add to our understanding of the possible role of the OX40/OX40 ligand system in the proliferation of HTLV-I+ T cells.

Amino Acid Motifs↗
PubMed2000

An interleukin-2-IgG-Fas ligand fusion protein suppresses delayed-type hypersensitivity in mice by triggering apoptosis in activated T cells as a novel strategy for immunosuppression.

BACKGROUND: Cell-mediated immune responses can be down-regulated by induction of apoptosis of immunoreactive lymphocytes. In the present study, we have tested the feasibility of a strategy for immunosuppression by the selective induction of apoptosis in activated, interleukin (IL)-2 receptor-positive lymphocytes, using a triple IL-2-IgG-FasL fusion protein. The IL-2-IgG-FasL fusion protein combines IL-2 for the selection of activated T cells, with the extracellular domain of the FasL molecule for inducing T-cell apoptosis. These components were separated by the Fc part of IgG1 serving as a spacer as well as for half-life prolongation. METHODS: The gene for the chimeric protein was created by fusing DNA sequences encoding for the three functional components: human IL-2, the Fc part of human IgG1, and the extracellular domain of murine FasL. When the fusion gene was expressed in murine J558L cells, we obtained soluble dimeric immunoglobulin-like proteins in the supernatant. After analyzing the function of the IL-2 and FasL portions individually in vitro, a delayed-type hypersensitivity (DTH) reaction to sheep red blood cells as model for cell-mediated immune responses was investigated to evaluate the IL-2-IgG-FasL-mediated immunosuppression in vivo. RESULTS: In vitro, the IL-2-IgG-FasL fusion protein supported IL-2-dependent proliferation of Fas-resistant CTLL-2 cells, whereas concanavalin A-T blasts were induced to undergo apoptosis by the FasL portion. In vivo, this fusion protein potently inhibited a murine DTH. This was associated with an increased rate of apoptosis in activated lymphocytes in the spleen, even at very low doses of the fusion protein. Furthermore, a second antigen challenge 10 days after IL-2-IgG-FasL treatment still failed to elicit a DTH response. CONCLUSION: The abrogation of a standard T cell-dependent immune response in vivo demonstrates that IL-2-IgG-FasL can be successfully exploited to trigger the death of deleterious T cells, presenting a potentially useful strategy in the management of autoimmune diseases and allotransplant rejections.

Animals↗
PubMed2000

The outcome of acute interstitial nephritis: risk factors for the transition from acute to chronic interstitial nephritis.

BACKGROUND: Acute interstitial nephritis has been known as a complication of mainly streptococcal infection for nearly a century. With the advent of infection control, it became a complication caused by antibiotics and later by other drugs, which might have changed the outcome. To determine risk factors for the development of chronic renal insufficiency, and thus, the transition from acute to chronic interstitial nephritis, we performed a retrospective study of all cases of acute interstitial nephritis found by reviewing 1,068 renal biopsies from 1968 to 1997. METHODS: Patients with permanent and reversible renal insufficiency after acute interstitial nephritis were compared with respect to the causative event, the symptoms, and the clinical and histological findings. Differences between the groups were calculated by applying bi- and multivariate analysis. RESULTS: Acute interstitial nephritis was found in 6.5% of all biopsies (64 patients with 68 episodes of acute interstitial nephritis); it was infection-induced in 10%, idiopathic in 4%, and drug-induced in 85% of the cases (antibiotics in 13 cases, analgesics in 17, non-steroidal anti-inflammatory drugs (NSAIDs) in 16, diuretics in 5, and various other drugs in 7). Renal insufficiency was reversible in 69% and permanent in 31% (12% partially reversible, 19% irreversible). The infection-induced and idiopathic types of acute interstitial nephritis were always reversible. Drug-related acute interstitial nephritis caused permanent renal insufficiency in 36% with a maximum of 56% in NSAID-induced cases. In drug-induced cases, intake of the suspected drug for more than a month prior to diagnosis caused permanent renal insufficiency in 88% and interstitial granuloma in 31%. Multivariate analysis disclosed the following significant features separating the permanent from the reversible renal insufficiency group: patients in the first group had more tubular atrophy in their histology, more chronic use of mixed analgesics and/or NSAIDs, less oliguria or anuria as an acute symptom, fewer antibiotics as causative agents, more interstitial granuloma, more pronounced interstitial cell infiltration in their histology, and more imaging of renal shrinkage. Renal histology had the highest predictive value. CONCLUSION: Today, acute interstitial nephritis is mainly drug-induced. NSAIDs are the most frequent cause of permanent renal insufficiency after acute interstitial nephritis. Clinically, subacute symptoms, a prolonged intake of the suspect drug, and chronic analgesic or NSAID use are related to a more chronic course of interstitial nephritis. In histology, tubular atrophy, interstitial granuloma, and pronounced interstitial cell infiltration indicate chronicity.

Acute Disease↗
PubMed1999

Protection of trinitrobenzene sulfonic acid-induced colitis by an interleukin 2-IgG2b fusion protein in mice.

BACKGROUND & AIMS: We have shown in previous studies that an interleukin 2 (IL-2)-IgG2b fusion protein suppresses both humoral and cellular immune reactions in a murine model of DTH reaction. We now analyze the effects of IL-2-IgG2b in a model of intestinal inflammation in mice induced by the hapten reagent 2,4, 6-trinitrobenzene sulfonic acid (TNBS) that mimics immunologic characteristics of human Crohn's disease. METHODS: In TNBS-induced colitis, colonic and splenic T-cell subsets were characterized by immunohistochemistry and flow cytometry. Cytokine synthesis was studied by semiquantitative reverse-transcription polymerase chain reaction and intracellular cytokine staining in CD4(+) T cells. RESULTS: When mice were treated with IL-2-IgG2b, improvement in both wasting disease and histopathologic signs of colonic inflammation was observed. An increase in the number of colonic CD4(+)/CD25(+) T cells and increased synthesis of the immunosuppressive cytokine IL-10 also occurred. The protective role of IL-10 was demonstrated by the finding that neutralization of IL-10 in vivo using IL-10-specific antibodies inhibited the IL-2-IgG2b effects in TNBS-induced colitis. CONCLUSIONS: These studies show for the first time that the IL-2-IgG2b fusion protein can abrogate experimental colitis by local induction of IL-10-secreting T cells.

Animals↗
PubMed1999

Death deflected: IL-15 inhibits TNF-alpha-mediated apoptosis in fibroblasts by TRAF2 recruitment to the IL-15Ralpha chain.

Interleukin-15 (IL-15) is a potent inhibitor of several apoptosis pathways. One prominent path toward apoptosis is the ligand-induced association of TNF receptor 1 (TNFR1) with death domain adaptor proteins. Studying if and how IL-15 blocks TNFR1-mediated apoptosis in a murine fibroblast cell line (L929), we show here that IL-15 blocks TNFR1-induced apoptosis via IL-15Ralpha chain signaling. The intracellular tail of IL-15Ralpha shows sequence homologies to the TRAF2 binding motifs of CD30 and CD40. Most important, binding of IL-15 to IL-15Ralpha successfully competes with the TNFR1 complex for TRAF2 binding, which may impede assembly of key adaptor proteins to the TNFR1 complex, and induces IkappaBalpha phosphorylation. Thus, IL-15Ralpha chain stimulation is a powerful deflector of cell death very early in the apoptosis signaling cascade, while TNF-alpha and IL-15 surface as major opponents in apoptosis control.

Amino Acid Sequence↗
PubMed1998

Vaccination with tumor cells engineered to secrete interleukin 2-immunoglobulin G fusion protein induces tumor rejection.

Here we provide proof that the injection of tumor cells engineered to secrete interleukin 2 (IL-2)-IgG chimeric proteins locally induces potent antitumor responses, which are more effective than tumor transfection with IL-2 alone. Murine plasmacytoma cells (J558L) were stably transfected with DNA coding for a human IL-2-IgG1 or a murine IL-2-IgG2b fusion protein and were injected s.c. into syngeneic BALB/c mice. Evaluation of tumor growth and rejection patterns showed that IL-2-IgG secretion by transfected J558L tumor cells induced their rejection in all animals tested, similar to the rejection of J558L cells engineered to secrete IL-2 alone, whereas treatment with parental cells was lethal. However, mice treated with IL-2-IgG-secreting J558L cells (human IL-2-IgG1 and murine IL-2-IgG2b) exhibited a significantly stronger tumor immunity against a later challenge with parental J558L cells than mice treated with IL-2-secreting tumor cells.

Animals↗
PubMed1998

Prolongation of corneal allograft survival by an interleukin-2-immunoglobulin fusion protein in mice.

BACKGROUND: Interleukin 2 (IL2) production by activated T-helper cells leads to activation and proliferation of cytotoxic T cells. Recently, an IL2-IgG fusion protein was found to suppress cell-mediated and humoral immune responses in mice. METHODS: We used the genetically engineered murine IL2-IgG2b fusion protein in a fully MHC-mismatched mouse keratoplasty model. The DTH reaction against sheep red blood cells was investigated as a measure of IL2-IgG2b-mediated immunosuppression. The animals were divided into three control groups (n > or = 6) [no treatment, subconjunctival (SQ) treatment with saline or mouse serum], two IL2 SQ-treated groups (14 micrograms or 140 micrograms), and four IL2-IgG2b-treated groups (14 micrograms, 140 micrograms or 280 micrograms SQ or 280 micrograms i.p.). RESULTS: Administration of 20 micrograms of IL2-IgG2b twice daily from the time of immunization until the time of challenge resulted in almost complete prevention of footpad swelling. The 140 micrograms SQ application of IL2 (allograft reaction on day 20.5 +/- 4.04) and the 280 micrograms SQ (day 19.2 +/- 2.48) or i.p. (day 19.7 +/- 1.5) application of IL2-IgG2b fusion protein significantly prolonged the corneal graft survival in comparison to the untreated group (day 13.4 +/- 1.35) (P < 0.01) or saline control group (P < 0.01) and the mouse-serum-treated group (day 14.7 +/- 3.5) (P < 0.05). CONCLUSION: Our results indicate that, at a total dose of 280 micrograms, the fusion protein IL2-IgG2b causes no detectable side effects and very effectively suppresses the immune response of the corneal allograft in mice. This fusion protein could prove useful in the treatment of allograft rejections and autoimmune diseases.

Animals↗