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Biomedical subjects

Gerhard Opelz

Publications and source records attributed to Gerhard Opelz.

At least 55 records · Page 3Linked to original sources

Strong human leukocyte antigen matching effect in nonsensitized kidney recipients with high pretransplant soluble CD30.

The influence of human leukocyte antigen (HLA) matching on graft survival is greater in patients with preformed lymphocytotoxic antibodies than in nonsensitized patients. Pretransplant serum soluble CD30 (sCD30) affects graft outcome independently of presensitization status. The impact of HLA compatibility on kidney transplant survival was analyzed in 3980 nonsensitized first cadaveric kidney recipients in relation to the pretransplant serum sCD30 content. Although HLA compatibility influenced graft outcome only marginally in nonsensitized recipients with low sCD30 (at 3 years: P=0.0095; at 5 years: P=0.1033), a strong HLA matching effect was observed in nonsensitized recipients with high sCD30 (at 3 years: P<0.0001; at 5 years: P=0.0001). Nonsensitized patients with high pretransplant sCD30 benefit from an HLA well-matched kidney. Patients should be tested for sCD30 while on the waiting list for a kidney transplant, and HLA well-matched kidneys should be allocated to patients with high sCD30.

Cadaver↗

High urine sIL-6R as a predictor of late graft failure in renal transplant recipients.

BACKGROUND: Chronic allograft nephropathy is an important cause of late renal transplant failure. Although numerous studies on cytokines have been carried out, the pathogenetic role of cytokines in chronic renal allograft nephropathy remains unclear. METHODS: In a retrospective study, the authors compared posttransplant plasma and urine cytokine levels (interleukin [IL]-1alpha, IL-1beta, soluble [s] IL-1 receptor [R] antagonist [A], IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-10, tumor necrosis factor-alpha, transforming growth factor-beta2, and interferon-gamma) in 34 matched pairs of patients with or without late graft failure and in 50 matched pairs with either normal or increased serum creatinine levels and continued stable graft function. RESULTS: Twelve and 6 months before late graft failure, urine levels of sIL-6R were significantly increased (P=0.003 and P=0.01, respectively). Serum creatinine levels were not associated with increased urine sIL-6R. CONCLUSION: High urine sIL-6R appears to be predictive of late graft failure in renal transplant recipients.

Adult↗

Cell cycle- and activation-dependent regulation of cyclosporin A-induced T cell apoptosis.

The immunosuppressive agent cyclosporin A (CsA), which interferes with signal transduction pathways leading to cytokine gene transcription in activated T cells, was investigated regarding its ability to induce apoptosis in T cells undergoing cell cycle progression and activation. In Jurkat and peripheral CD4+ T cells, CsA was found to markedly induce apoptosis at the G0 phase of the cell cycle. Susceptibility to CsA-induced apoptosis progressively decreased during cell cycle progression to the S and G2/M phase, and subsequent T cell receptor- and mitogen-mediated activation totally abrogated CsA-induced apoptosis. Because CsA is an inhibitor of the chymotryptic peptidase activity of the proteasome, susceptibility to apoptosis induced by the proteasome inhibitor lactacystin was investigated under the same conditions. A progressive increase of the susceptibility of T cells to lactacystin-induced apoptosis during cell cycle progression and activation was demonstrated. Intracellular protein levels of the cyclin-dependent kinase inhibitor p27(Kip1)decreased from the G0 to G2/M phase and from the cycling to the activation state, but remained unchanged during the induction of apoptosis by CsA and lactacystin, suggesting a role of p27(Kip1)in the regulation of susceptibility to apoptosis during cell cycle progression and activation. Inhibition of CsA- but not lactacytin-induced apoptosis by overexpression of Bcl-2 in Jurkat T cells revealed that CsA and proteasome inhibitors activate different apoptotic pathways, while both CsA- and lactacystin-induced apoptosis were found to be dependent on caspase activation and independent of the FasL/Fas system. The results show that T cells can progressively regulate their susceptibility to apoptosis during cell cycle progression and activation in a stimulus-dependent manner, and suggest that lactacystin, but not CsA, is able to deplete activated T cells by apoptosis, a mechanism deemed necessary for the induction of allograft tolerance.

Acetylcysteine↗

Mycophenolate mofetil-based immunosuppression and cytokine genotypes: effects on monokine secretion and antigen presentation in long-term renal transplant recipients.

BACKGROUND: It has been suggested that increased monocyte responses might play a role in chronic allograft rejection. METHODS: We investigated in vitro monokine responses in 112 patients with long-term stable kidney graft function (ST patients; n=80, non-mycophenolate mofetil [MMF]; n=32, MMF) and 25 patients with chronic renal transplant rejection (CR patients; non-MMF). Interleukin 10 and tumor necrosis factor (TNF)-alpha promoter gene polymorphisms were tested by polymerase chain reaction and sequence-specific primers; antigen-presenting capacity (AC) of monocytes was tested by incubation with staphylococcal superantigens (SEA, SEE, SED). RESULTS: Although non-MMF-based immunosuppression in ST patients did not result in compromised AC or lipopolysaccharide (LPS)-stimulated monokine responses compared with healthy controls, we found MMF therapy to be associated with significantly reduced TNF-R1 expression on monocytes (P<0.001), suppressed AC (P<0.02, SED), and suppressed LPS-stimulated IL-1 beta, IL-10, and TNF-alpha secretion (P<0.01). Coinciding with a significantly higher steroid dosage in CR patients, IL-6 receptor and TNF-R1 expression on monocytes were down-regulated (P< or =0.02) and AC was suppressed in CR compared with ST (non-MMF) patients (P<0.01, SED; P<0.05, SEE). However, LPS-stimulated monokine secretion was not decreased or even enhanced (IL-6, granulocyte-macrophage colony-stimulating factor [GM-CSF]; P<0.05). Enhanced in vitro IL-10 responses (>500 pg/mL) were found predominantly in non-MMF-treated patients with the IL-10 genotype GCC (GCC: 23/62 [37%], non-GCC: 2/27 [7%], P<0.005; GCC and non-MMF: 22/47 [47%], GCC and MMF: 1/15 [7%], P<0.005]. CONCLUSION: Steroids and azathioprine did not sufficiently suppress monokine responses, whereas MMF treatment might inhibit chronic graft rejection because of suppression of TNF-R1 expression and vigorous inhibition of monokine secretion. MMF treatment may especially be indicated in patients with the IL-10 "high-producer" genotype GCC.

Adult↗

A new epitope-based HLA-DPB matching approach for cadaver kidney retransplants.

BACKGROUND: Several years ago a significant impact of matching for HLA-DPB1 alleles on the survival of cadaver kidney retransplants was shown. Here we report the results of a new approach, based on matching for HLA-DPB1 epitopes. METHODS: The analysis is based on 1,478 patients who received a cadaver kidney retransplant between 1988 and 1998. DNA methodology (polymerase chain reaction, sequence-specific oligonucleotides) was used to perform HLA-DPB1 typing. Epitope matching was facilitated with the aid of sequence databases and computer calculations. RESULTS: Matching for the HLA-DP epitopes A, B, E, and F, corresponding to the homonymous hypervariable regions of the second exon of the DPB1 gene, seems to have a greater influence on graft survival than matching for the epitopes C and D. Within a group of 529 retransplants with exactly one allelic HLA-DPB1 mismatch, a significantly better graft outcome was observed when less than two epitope mismatches were found, compared with the group with more than three epitope mismatches (at 2 years: 77.8% vs. 65.8%, P=0.0112). Importantly, patients with two DPB1 allele mismatches who had less than or equal to two epitope mismatches exhibited a significantly better graft outcome than recipients who had one HLA-DPB1 allelic mismatch but more than three epitope mismatches (at 2 years: 77.1% vs. 65.8%, P=0.0488). CONCLUSIONS: The findings indicate that the impact of HLA-DPB1 matching on the outcome of kidney retransplants is a result of the predominant immunogenicity of certain epitopes of the HLA-DP molecule. Matching for immunogenic HLA-DPB1 epitopes seems to be functionally more relevant than classical matching at the allelic level.

Cadaver↗

Induction of apoptosis in human lymphocytes by human anti-HLA class I antibodies.

BACKGROUND: Ligation of MHC class I molecules expressed on T cells leads to both growth arrest and apoptosis. Although mouse anti-HLA class I monoclonal antibodies (mAbs) have been previously shown to cause apoptosis of human cells, an apoptosis-inducing capacity of human anti-HLA class I antibodies on human lymphocytes has not been reported. Because this is of potential clinical relevance, we tested human anti-HLA class mAbs for their capacity to induce apoptosis. METHODS: Twenty-five human HLA class mAbs and mouse mAb W6/32 were tested on resting human peripheral blood mononuclear cells or Jurkat lymphoblastic T cells using the Annexin-V binding and immunobinding assays. RESULTS: We demonstrated that HLA class I human mAbs are able to induce apoptosis as early as 1 hr after treatment of resting human peripheral blood mononuclear cells or Jurkat lymphoblastic T cells. The apoptosis-inducing effect and the binding of anti-HLA mAbs to the cells were strongly increased when lymphoblasts were prestimulated with cytokines, such as interferon-gamma and interleukin-2. Induction of apoptosis increased with the dosage and binding of anti-HLA mAbs. Caspase inhibitors did not affect apoptosis induced by MHC class I ligation. CONCLUSIONS: Our study showed for the first time that human HLA class I mAbs induce rapid and strong apoptosis in resting human peripheral blood mononuclear cells and Jurkat T lymphoblasts.

Amino Acid Chloromethyl Ketones↗

Subjective and quantitative assessment of patient fitness for cadaveric kidney transplantation: the "equity penalty".

BACKGROUND: Patient fitness at the time of organ allocation has an impact on graft survival equivalent to the effect of human leukocyte antigen (HLA) matching. The variation between institutions in assessment of fitness is not known, nor is the potential impact on mean graft survival of incorporating patient fitness into local adult cadaveric-kidney transplant-allocation algorithms. METHODS: Data from the Collaborative Transplant Study (CTS, 1985-2000) were reviewed. Quantitative criteria (QC) of patient fitness based on national transplant society guidelines were compared with subjective categorization (SC) of each patient on the current local transplant waiting list (n=109) determined by their supervising nephrologist. RESULTS: Five-year cadaveric graft survival was 70%, 61%, and 53% for good-, moderate-, and poor-risk patients in the CTS data set (n=102, 612), equivalent to half lives of 12.7, 9.8, and 8.7 years, respectively, with similar results from the local program. The distribution of local waiting-list patients into fitness categories A (good), B (moderate), C (poor), and D (unacceptable) was 51%:31%:13%:5% by SC and 25%:40%:27%:8% by QC. At one hospital, 61% (n=51) of patients were classified category A by SC, and falling to 16% by QC (P<.0001). Compared with preferential category A recipient allocation, an unrestricted allocation policy was estimated to sacrifice 1.5 years of overall program-mean graft survival. CONCLUSIONS: Use of QC may reduce the variation in subjective patient assessment seen between institutions. Any proposed changes in organ allocation methods should address the "equity versus efficiency" balance in an open fashion and predict the impact on the overall graft survival for the program by quantifying the "equity penalty."

Adolescent↗

Evaluation of posttransplantation soluble CD30 for diagnosis of acute renal allograft rejection.

BACKGROUND: Posttransplantation measurement of soluble CD30 (sCD30) may be useful for identifying kidney graft recipients at risk of impending graft rejection in the early posttransplantation period. METHODS: We measured plasma sCD30 levels and evaluated the levels in relation to the diagnosis of rejection. RESULTS: Receiver operating characteristic curves demonstrated that on posttransplantation days 3 to 5, sCD30 allowed a differentiation of recipients who subsequently developed acute allograft rejection (n=25) from recipients with an uncomplicated course (n=20, P<0.0001) (area under the receiver operating characteristic curve 0.96, specificity 100%, sensitivity 88%) and recipients with acute tubular necrosis in the absence of rejection (n=11, P=0.001) (area under the receiver operating characteristic curve 0.85, specificity 91%, sensitivity 72%). CONCLUSIONS: sCD30 measured on posttransplantation days 3 to 5 offers a noninvasive means for differentiating patients with impending acute allograft rejection from patients with an uncomplicated course or with acute tubular necrosis.

Acute Disease↗

Apoptosis-mediated selective killing of malignant cells by cardiac steroids: maintenance of cytotoxicity and loss of cardiac activity of chemically modified derivatives.

Cardiac glycosides are commonly used drugs in clinical medicine. We analyzed the cytotoxic effect of six steroids belonging to the bufadienolide family on malignant T lymphoblasts and normal peripheral blood mononuclear cells (PBMC). One compound was a natural bufadienolide glycoside (hellebrin) with cardiac activity. The other five compounds were chemically modified derivatives that did not contain cardioactive groups. We found that these steroids were able to cause time-dependent apoptosis in Jurkat T lymphoblasts, whereas they only minimally affected PBMC. Preferential killing of malignant cells was induced by the natural cardioactive substance hellebrin and by three of the five chemically modified non-cardioactive derivatives. The substances caused mitochondrial transmembrane potential disruption and internucleosomal DNA fragmentation in tumor cells. The cytoplasmic and nuclear events of bufadienolide-induced apoptosis were strongly inhibited in the presence of caspase 8, caspase 9, or caspase 3 inhibitors, as well as in the presence of the broad-spectrum caspase inhibitor Z-VAD-FMK. Overexpression of Bcl-2 significantly protected bufadienolide-treated cells from phosphatidylserine translocation, transmembrane potential disruption, and internucleosomal DNA fragmentation. Our results show that the analyzed bufadienolide derivatives preferentially kill malignant human lymphoblasts by initiating apoptosis via the classical caspase-dependent pathway. Apoptosis-inducing agents specific for tumor cells might be ideal anti-tumor drugs. The therapeutic use of bufadienolides has been hampered by their concomitant cardiac activity. The description of compounds without cardiac activity but with tumor-specific cytotoxicity suggests the potential of using them in cancer therapy.

Amino Acid Chloromethyl Ketones↗

A new HLA-DRB allele (DRB1*15014) identified in a Caucasian individual.

Polymerase chain reaction with sequence specific primers subtyping of a DRB1*15 allele in a male 11-year-old German Caucasian and his father revealed a reaction pattern that did not agree with any known specificity, thus suggesting the existence of a novel allele. Sequence-based typing after allelic separation revealed the new allele human leukocyte antigen (HLA)-DRB1*15014. The sequence pattern of HLA-DRB1*15014 might have been generated as a result of two independent recombinations, most likely over several generations.

Adult↗

The effect of ATG on cytokine and cytotoxic T-lymphocyte gene expression in renal allograft recipients during the early post-transplant period.

BACKGROUND: Despite the long history of ATG use, the exact in vivo mechanism of action remains unclear. In the present study, we analyzed the effect of ATG-induction therapy on expression of 10 immunologically relevant genes in the early post-transplant period. METHODS: Eight renal allograft recipients received post-transplant prophylactic ATG treatment on 10 consecutive days and an additional three patients received treatment on 5, 6, or 7 consecutive days, respectively. Gene expression was measured at the beginning and the end of therapy and normalized to a control gene using Taqman real-time PCR methodology. Results were compared with those of matched control patients. No patients were diagnosed with rejection. RESULTS: ATG-treated patients showed decreases in the expression of cytotoxic T cell genes perforin (-56%, p = 0.03) and granzyme B (-45%, p = 0.01) and cytokine gene IFN-gamma (-75%, p = 0.005), and significant increases in the expression of cytokine genes IL-7 (550%, p = 0.04), IL-10 (275%, p = 0.01), IL-15 (417%, p = 0.03), TNF-alpha (615%, p = 0.01), and TGF-beta (235%, p = 0.02). No significant changes were observed in the control group, with the exception of a decrease in IL-10 expression (-42%, p = 0.01). There were no significant changes in IL-12 or Fas-L expression in either group. CONCLUSION: ATG-induced decreases in the expression of IFN-gamma, perforin, and granzyme B and increases in IL-10 and TGF-beta might be considered beneficial to the recipient, whereas increases in the expression of IL-7, IL-15, and TNF-alpha genes might be involved in immunological processes not effected by ATG that may harm the transplant in the long term.

Adult↗

Serial peripheral blood perforin and granzyme B gene expression measurements for prediction of acute rejection in kidney graft recipients.

In the present study we investigated whether peripheral blood gene expression measurements may serve as an early and non-invasive tool to predict renal allograft rejection. Peripheral blood was collected twice weekly after transplantation and gene expression was measured using real-time polymerase chain reaction (PCR). Recipients with acute rejection (n = 17) had higher levels of perforin and granzyme B transcript on days 5-7, 8-10, 11-13, 17-19, 20-22, and 26-29, as compared to patients without rejection (n = 50, p < 0.05 in all cases). Rejection diagnosis using gene expression criteria, determined with receiver operating characteristic (ROC) curves, was possible 2-30 days before traditional diagnosis (median 11 days). The best diagnostic result was obtained from samples taken on days 8-10, with a specificity of 90% and a sensitivity of 82% for perforin, and a specificity of 87% and sensitivity of 72% for granzyme B. Decreases in perforin (p < 0.01) and granzyme B expression (p < 0.05) were observed after initiation of anti-rejection therapy. Our data indicate that gene expression measurement is a useful tool for the recognition of graft rejection in its earliest stages. Serial measurements could be implemented as a monitoring system to highlight patients at higher risk of rejection, making them candidates for biopsy or pre-emptive anti-rejection therapy.

Biomarkers↗

Prolongation of long-term kidney graft survival by a simultaneous liver transplant: the liver does it, and the heart does it too.

BACKGROUND: Whereas some authors reported that kidney transplants were protected from rejection by simultaneous liver grafts, other authors failed to obtain evidence for a kidney graft-protective role for the liver. METHODS: The survival rate of 383 kidney grafts in recipients of combined kidney-liver transplants performed between 1985 and 2000 and reported to the international Collaborative Transplant Study (CTS) was analyzed and compared retrospectively with that of a matched group of control patients who were transplanted with kidneys only. In addition, 105 combined kidney-heart transplants performed during the same time period were analyzed. RESULTS: At 1 year, the survival rate of kidney grafts in recipients of kidney-liver transplants was significantly lower than that in kidney only recipients (P<0.0001). Subsequently, however, kidneys in kidney-liver recipients fared much better so that the success rates were virtually identical after 8 years of follow-up (62.1+/-3.5% vs. 61.9+/-2.3%, P=ns). Half-life times after the first posttransplant year were 27.6 and 14.5 years for combined or single kidney grafts, respectively, and the projected 20-year graft survival rates were 46% and 35%, respectively. The 8-year survival rate of kidney grafts in recipients of combined kidney-heart recipients was 63.5+/-6.2%, the associated half-life time 31.6 years, and the projected 20-year graft survival rate 49%. CONCLUSIONS: The long-term kidney graft survival rate is higher in recipients of combined kidney-liver transplants than in recipients of kidney grafts only. Because the success rate is equally high in recipients of combined kidney-heart transplants, it is necessary to reexamine the hypothesis that the liver possesses a unique capacity of protecting a simultaneous kidney graft from rejection.

Adult↗

Polymorphisms of the tumor necrosis factor-alpha gene promoter predict for outcome after thalidomide therapy in relapsed and refractory multiple myeloma.

Thalidomide (Thal) is a drug with antiangiogenic, anti-inflammatory, and immunomodulatory properties that was found to inhibit the production of tumor necrosis factor-alpha (TNF-alpha) in vitro. We studied single nucleotide polymorphisms at positions -308 and -238 of the TNF-alpha gene promoter and measured the corresponding TNF-alpha cytokine levels in 81 patients (pts) with refractory and relapsed multiple myeloma (MM) who were treated with Thal. In myeloma pts carrying the TNF-238A allele (n = 8), we found a correlation with higher pretreatment TNF-alpha levels in peripheral blood (P =.047). After Thal administration, this TNF-238A group had a prolonged 12-month progression-free and overall survival of 86% and 100% versus 44% and 84% (P =.003 and P =.07) in pts with the TNF-238G allele, respectively. These findings suggest that regulatory polymorphisms of the TNF-alpha gene can affect TNF-alpha production and predict the outcome after Thal therapy, particularly in those MM pts who are genetically defined as "high producers" of TNF-alpha.

Adult↗

Does growth hormone treatment affect the risk of post-transplant renal cancer?

According to the analysis of the Collaborative Transplant Study (CTS), the incidence of renal carcinoma in patients with renal transplantation as well as with heart transplantation is significantly increased at any given patient age. The cumulative incidence 10 years after kidney transplantation is 185 per 100,000 patients in children below the age of 19 years at the time of transplantation. Age and immunosuppressive treatment seem to be the major risk factors. The majority of cancers develop within the native kidneys. Chronic transplant nephropathy and accelerated senescence may be further risk factors for the development of cancer within a kidney transplant. Growth hormone (GH) treatment could not be identified as an additional risk factor.

Carcinoma, Renal Cell↗

Inhibition of allogeneic T cell proliferation by indoleamine 2,3-dioxygenase-expressing dendritic cells: mediation of suppression by tryptophan metabolites.

Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, is expressed in certain cells and tissues, particularly in antigen-presenting cells of lymphoid organs and in the placenta. It was shown that IDO prevents rejection of the fetus during pregnancy, probably by inhibiting alloreactive T cells, and it was suggested that IDO-expression in antigen-presenting cells may control autoreactive immune responses. Degradation of tryptophan, an essential amino acid required for cell proliferation, was reported to be the mechanism of IDO-induced T cell suppression. Because we wanted to study the action of IDO-expressing dendritic cells (DCs) on allogeneic T cells, the human IDO gene was inserted into an adenoviral vector and expressed in DCs. Transgenic DCs decreased the concentration of tryptophan, increased the concentration of kynurenine, the main tryptophan metabolite, and suppressed allogeneic T cell proliferation in vitro. Kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid, but no other IDO-induced tryptophan metabolites, suppressed the T cell response, the suppressive effects being additive. T cells, once stopped in their proliferation, could not be restimulated. Inhibition of proliferation was likely due to T cell death because suppressive tryptophan catabolites exerted a cytotoxic action on CD3(+) cells. This action preferentially affected activated T cells and increased gradually with exposure time. In addition to T cells, B and natural killer (NK) cells were also killed, whereas DCs were not affected. Our findings shed light on suppressive mechanisms mediated by DCs and provide an explanation for important biological processes in which IDO activity apparently is increased, such as protection of the fetus from rejection during pregnancy and possibly T cell death in HIV-infected patients.

3-Hydroxyanthranilic Acid↗

Kidney graft failure and presensitization against HLA class I and class II antigens.

BACKGROUND: It is well known that kidney transplant recipients with preformed lymphocytotoxic antibodies against HLA antigens have an increased graft rejection rate. However, the individual contribution of anti-HLA class I and class II antibodies to this phenomenon is poorly understood. We investigated the clinical relevance of preformed anti-HLA class I and class II antibodies on graft outcome in more than 4000 kidney recipients. METHODS: Pretransplant sera of 4136 cadaver kidney recipients from 28 transplant centers were tested in ELISA for IgG-anti-HLA class I and IgG-anti-HLA class II antibodies. The influence of antibody reactivity on graft survival was analyzed. RESULTS: Four hundred eighty of the anti-HLA class I antibody-positive recipients had a graft survival rate at 2 years of 77+/-2%, compared with an 84+/-1% rate in 3656 anti-HLA class I antibody-negative recipients (P<0.0001), and 770 anti-HLA class II-positive recipients had a graft survival rate of 79+/-2%, compared with an 84+/-1% rate in 3366 anti-HLA class II-negative patients (P<0.0001). Importantly, good 2-year graft survival rates of 85+/-3% and 84+/-2%, respectively, were observed in 206 anti-HLA class I-positive/class II-negative and 496 anti-HLA, class I-negative/class II-positive recipients. In contrast, the 274 recipients positive for both types of antibodies showed a poor graft survival rate of 71+/-3% (P<0.0001). Among 853 patients who received a well-matched kidney (0 or 1 HLA-A+B+DR mismatch), sensitization against either class I or class II, or both, had no deleterious effect. However, in 113 class I and class II antibody-positive patients who received a kidney with > or =3 HLA-A+B+DR mismatches, the 2-year graft survival rate was only 60+/-5%. CONCLUSION: Presensitization of first kidney transplant recipients against either HLA class I or class II is of no clinical consequence, whereas sensitization against both HLA class I and class II results in increased rejection of HLA mismatched grafts.

Adult↗