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Bernd Schröppel

Publications and source records attributed to Bernd Schröppel.

15 recordsLinked to original sources
PubMed2006

Differential expression of profibrotic and growth factors in chronic allograft nephropathy.

BACKGROUND: Chronic allograft nephropathy (CAN) is a multifactorial process, where both immunological and nonimmunological factors play roles. Microarrays detect thousands of genes simultaneously. METHODS: We have analyzed gene expression profiles of 16 kidney transplant biopsy samples with CAN by high-density oligonucleotide microarrays, comparing to six normal transplant biopsies. Eight CAN biopsies showed nodular arteriolar hyalinization and one was positive for C4d staining. RESULTS: Hierarchical clustering analysis of the 22 biopsies revealed differential gene expression patterns in CAN versus the control biopsies. However, microarray analysis did not reveal differential gene expression patterns in patients with or without arteriolar hyalinization. Fifty percent of the 100 genes with highest hybridization intensities in a C4d positive sample were related to cellular and humoral immune response. Although 212 genes were upregulated a minimum of 1.5-fold, 112 genes were downregulated in CAN samples. There was differential expression of profibrotic and growth factors that while transforming growth factor-beta induced factor, thrombospondin 1, and platelet derived growth factor-C were up-regulated, vascular endothelial growth factor, epidermal growth factor, and fibroblast growth factors 1 and 9 were downregulated. Selected differentially expressed genes were confirmed in microdissected samples by real-time quantitative PCR. Immunopathologic examination of biopsies revealed strong TGF-beta but decreased glomerular VEGF expression in CAN. CONCLUSION: Microarrays might be an important tool to uncover the mechanisms of multifactorial diseases, such as CAN.

Adult↗
PubMed2006

CD4+ CD25+ regulatory T-cells inhibit the islet innate immune response and promote islet engraftment.

Early islet cell loss is a significant problem in clinical islet cell transplantation. Diverse stress stimuli induce innate immune responses in islets that contribute to beta-cell dysfunction, inflammation, and loss. Here, we show that cytokine-stimulated murine islets express multiple inflammatory chemokines that recruit T-cells and thereby impair islet function in vitro and in vivo. Both nonislet ductal and exocrine elements and the individual islet cellular components contribute to this innate immune response. CD4+ CD25+ regulatory T-cells inhibit islet chemokine expression through a cell contact-dependent, soluble factor-independent mechanism and inhibit effector T-cell migration to the islet. Regulatory T-cells can also migrate to stimulated islets. Cotransfer of regulatory T-cells with islets in a transplantation model prevents islet innate immune responses and inflammation and preserves normal architecture and engraftment. Regulatory T-cell inhibition of multiple components of innate immune responses may be a fundamental aspect of their function that influences ischemia-reperfusion injury and adaptive immunity.

Animals↗
PubMed2004

Role of donor-derived monocyte chemoattractant protein-1 in murine islet transplantation.

Monocyte chemoattractant protein-1 (CCL2/MCP-1) is a proinflammatory chemokine produced by several cell types, including pancreatic islets. High levels of donor-derived CCL2 have been associated with poor islet allograft outcome in patients with type 1 diabetes; however, the causal relationship is unknown. The constitutive and inducible expression of chemokines and their receptors by pancreatic islets in vitro were investigated, specifically the role of donor-derived CCL2 in marginal mass murine islet transplantation. The results showed that inflammatory cytokine stimulation of islets induced de novo expression of CCL2, CCL5/RANTES, CXCL9/MIG, and CXCL10/IP-10 and increased expression of CXCL2/macrophage-inflammatory protein-2. CCL2 mRNA and protein were highly expressed within 2 d in cultures. Transplantation of islets with high levels of CCL2 into syngeneic recipients led to a significantly greater influx of CCR2(+) cells and higher expression of monocyte/macrophage-associated inflammatory cytokines compared with low CCL2-donor islets. The level of pretransplantation CCL2 inversely correlated (P < 0.0001) with isograft function. In contrast, in CCR2-/- recipients, this correlation was not present. A direct toxic effect of CCL2 on islets was excluded by assessing cell viability and insulin release in vitro. In conclusion, CCL2 secreted by islets plays an important role in the immediate islet graft function. Strategies to decrease islet-derived CCL2 release may increase the success of islet transplantation.

Animals↗
PubMed2004

Differential expression of chemokines and chemokine receptors in murine islet allografts: the role of CCR2 and CCR5 signaling pathways.

Chemokines and their receptors play a pivotal role in the initiation and amplification of the immune response. Investigated was their differential expression after syngeneic and allogeneic islet transplantation. During the 7 d after transplantation, the chemokines MCP-1, MCP-2, RANTES, MIG, IP-10, I-TAC, and two CC chemokine receptors CCR2 and CCR5 were highly expressed in allografts when compared with isografts. Disrupting the CCR2 and CCR5 pathways individually resulted in prolongation of the survival time 16.1 +/- 0.4 and 15.8 +/- 0.9 d, respectively, of fully major histocompatibility complex-mismatched islet grafts compared with wild-type controls (11.2 +/- 1.0 d). Blockade of both receptors had no synergistic effect. Rapamycin-treated wild-type recipients rejected their grafts at 17.4 +/- 2.2 d, in contrast to rapamycin-treated CCR2-/- recipients at 38 +/- 8.6 d (P = 0.025). The disruption of the CCR2 and CCR5 signaling, alone or in combination, moderately prolong islet allograft survival. However, the combination of low-dose immunosuppression and targeting of CCR2 greatly augmented islet graft survival.

Animals↗
PubMed2003

The impact of costimulatory molecule gene polymorphisms on clinical outcomes in liver transplantation.

CTLA-4 and CD28 deliver opposing signals for T-cell proliferation. We examined single nucleotide polymorphisms (SNPs) CTLA-4 -318C/T and CD28 IVS3 +17T/C for associations with acute rejection in liver transplant recipients. These and two other polymorphisms in CTLA-4 [microsatellite polymorphism +642(AT)n and SNP +49 A/G] were also analyzed for influence on graft survival. Two hundred and eleven liver transplant recipient genotypes were determined by direct sequencing or restriction fragment length polymorphism analysis of PCR-amplified genomic DNA. Mean graft survival for patients with the GG genotype of CTLA-4 +49 A/G was 58.5 +/- 6.0 months compared with 70.3 +/- 4.0 months and 73.8 +/- 2.8 months for the AA and AG genotypes, respectively (p = 0.0055). This is in support of previous studies suggesting decreased CTLA-4 function and increased incidence of autoimmune disease for this genotype. The 92-, 94-, and 100-bp alleles of CTLA-4 +642(AT)n occurred more often in African-American transplant recipients and were associated with decreased graft survival (p = 0.0001 and 0.007, respectively) but the independence of these variables could not be established. No associations with acute rejection or graft survival were found for CTLA-4 -318C/T or CD28 IVS3 +17T/C. The described associations between CTLA-4 gene polymorphisms and transplant outcomes provide the foundation for further investigations leading to genetic risk stratification for transplant recipients.

Alleles↗
PubMed2003

Viral IL-10 gene transfer inhibits the expression of multiple chemokine and chemokine receptor genes induced by inflammatory or adaptive immune stimuli.

Previously we have shown that adenovirus-mediated gene transfer and expression of vIL-10 are able to prolong cardiac allograft survival, through the inhibition of the immune response to both alloantigen and adenoviral antigens. In the current study, we have defined further mechanisms of Ad.vIL-10-mediated prolongation of cardiac allograft survival. E1- and E3-deleted adenoviral vectors encoding beta-galactosidase or vIL-10 were transferred into grafts at the time of transplantation, chemokine and chemokine receptor expression were evaluated by a pathway-specific cDNA array, and the results were confirmed with real time RT-PCR on selected genes. Ischemic injury, alloantigen and adenovirus vector induced the expression of multiple pro-inflammatory chemokines in the grafts, which likely amplify allograft rejection. Most of these Th1-related chemokine genes were inhibited or down-regulated by Ad.vIL-10 administration, which may help to decrease leukocytic infiltration and improve graft survival. Among the potent Th1 type chemokines inhibited were the CXCR3 ligands CXCL9 and CXCL10, which could directly inhibit vector-mediated gene expression in myoblasts, although targeting CXCR3 or its ligands did not prolong allograft survival with vIL-10 gene transfer. Ad.vIL-10 administration also induced the expression of the Th2-associated chemokines eotaxin-2 and MIP-1 gamma, suggesting Th1 to Th2 immune deviation. These results demonstrated that the vIL-10 gene transfer inhibits chemokine expression, preventing stimulation of innate and adaptive immunity.

Animals↗
PubMed2003

Differential chemokine and chemokine receptor gene induction by ischemia, alloantigen, and gene transfer in cardiac grafts.

Transplantation of allogeneic grafts presents several challenges to the innate and adaptive immune systems including chemokine leukocyte recruitment, activation, and effector function. We defined the chemokines and receptors induced by the transplant procedure/ischemia injury, alloantigen and gene transfer vector administration in murine cardiac grafts. E1, E3 deleted AdRSVbetagal was transferred into grafts at the time of transplantation, grafts were harvested after 1-14 days, and a pathway-specific cDNA array was used to evaluate the levels of 67 chemokine and chemokine receptor genes. Transplantation resulted in ischemic injury and induction of a number of similar genes in both the syngeneic and allogeneic grafts, such as CXCL1 and CXCL5, which increased dramatically on day 1 and returned rapidly to baseline in the syngeneic grafts. Alloantigen stimulated the adaptive immune response and induced the presence of more inflammatory genes within the grafts, particularly at later time points. The adenovirus vector induced a broader panel of genes, among them potent inflammatory chemokines CXCL9 and CXCL10, that are induced earlier or more strongly compared with alloantigen stimulation alone. As alloantigen and adenovirus vectors both induce similar sets of genes, targeting these molecules may not only inhibit alloimmunity, but also enhance the utility of the gene transfer vector.

Adenoviridae↗
PubMed2003

Adenovirus transduction induces expression of multiple chemokines and chemokine receptors in murine beta cells and pancreatic islets.

Adenoviral vectors are highly efficient for transferring genes to islets. However, the inflammatory and immune responses stimulated by adenovirus may be detrimental to islet survival. Given the role of chemokines and their receptors in inflammation, we analyzed their expression in isolated murine islets, in a murine beta cell line and in syngeneic islet grafts after adenovirus transduction (AdRSVLacZ). AdRSVLacZ transduction enhanced and induced the expression of a variety of chemokines. Transduced syngeneic transplanted islets showed significantly enhanced expression of multiple chemokines and receptors, including monocyte chemoattractant protein-1 (MCP-1), CC chemokine receptor 2 (CCR2) and regulated upon activation, normal T cell expressed and secreted (RANTES), compared with untransduced islet grafts. AdRSVLacZ-transduced islet grafts had significant mononuclear infiltrates, and in situ hybridization demonstrated intragraft expression of MCP-1, CCR2 and RANTES. Although adenovirus transduction did not impair in vitro insulin secretion, diabetes was reversed in only one of six recipients of a marginal mass of AdRSVLacZ-transduced islets, compared with six of six control recipients. In conclusion, multiple chemokines and chemokine receptors are expressed by murine islets constitutively and in response to adenovirus transduction. Adenovirus transduction impairs engraftment of marginal mass of transplanted islets. This is not because of direct vector toxicity of islet secretory capacity, but may be related to host innate immunity in response to adenovirus vector.

Adenoviridae↗
PubMed2003

Genetic variability and transplantation.

PURPOSE OF REVIEW: The purpose of this review is to summarize recent advances within the area of genetic polymorphisms with a specific emphasis on renal transplantation, and to discuss the potential clinical applications. RECENT FINDINGS: Due to recent advances in molecular techniques, there has been an abundance of publications describing genetic variability in molecules relevant to transplant outcome. Many studies are now demonstrating associations between polymorphisms in these candidate genes and outcomes in organ transplantation. SUMMARY: These studies emphasize the potential role of genetic variability in transplantation, and provide the rationale for large prospective studies to clearly define the potential benefits of genotyping in the risk stratification of transplant recipients.

Animals↗
PubMed2002

Analysis of gene polymorphisms in the regulatory region of MCP-1, RANTES, and CCR5 in liver transplant recipients.

Chemokines and their receptors play a major role in the inflammatory and immune responses that mediate allograft outcome. The production of some chemokines varies among individuals and these variations may be determined by genetic polymorphisms, most commonly within the regulatory region of the gene. We investigated whether the functional polymorphisms of the chemokines RANTES, MCP-1 and chemokine receptor CCR5 are associated with the incidence of acute rejection and long-term liver graft survival. Two hundred nine liver transplant recipients were genotyped using polymerase chain reaction sequence-specific primers for the following polymorphisms: RANTES-28, MCP-1 -2518, and CCR5-59029. There was no association with any of the three genotypes and the incidence of acute rejection episodes. In addition, no association of RANTES-28, MCP-1 -2518, or CCR5 -59029 variants with long-term liver graft survival was found. In conclusion, variants of RANTES-28, MCP-1 -2518, and CCR5-59029 neither influenced the incidence of acute rejection nor affected long-term allograft survival upon liver transplantation in the context of this analysis.

Adult↗
PubMed2002

The impact of polymorphisms in chemokine and chemokine receptors on outcomes in liver transplantation.

Chemokines and their corresponding receptors likely play a central role in directing mononuclear cells to the graft sites during rejection. Genes for the chemokine stromal derived factor-1 (SDF1) and CC chemokine receptors CCR2 and CCR5 are characterized by polymorphisms which alter their function. We genotyped DNA of 207 liver transplant recipients by PCR or PCR-RFLP for CCR2-641, CCR5delta32, and SDF1-3'A polymorphisms, and examined their association on outcomes in liver allograft recipients. Due to the low number of patients homozygous for CCR2-641 and CCR5delta32, only the effects of their heterozygous variants were addressed in this study. None of the investigated polymorphisms showed a significant shift in gene frequency in acute rejection and rejection-free groups, or for graft survival. The gene frequency of the SDF1-3'A allele was significantly (p = 0.034) higher in patients who died (29.0%, n = 31) compared to recipients still alive (17.1%, n = 172). The mean patient survival time post transplant was 134 months in patients with SDF1 wild-type, significantly (log rank p = 0.014) longer than 98 months in patients with at least one SDF1-3'A allele. The CCR2 and CCR5 polymorphisms were not associated with significant differences in mortality rate. In conclusion, CCR2-641, CCR5delta32, and SDF1-3'A genotypes did not influence the risk for acute rejection or graft survival. However, in liver allograft recipients SDF1-3'A is significantly associated with higher mortality.

Chemokine CXCL12↗
PubMed2002

A Monocyte chemoattractant protein-1 (MCP-1) polymorphism and outcome after renal transplantation.

Among the factors modulating transplant rejection and cardiovascular disease, chemokines and their respective receptors deserve special attention. In this respect, increased expression of MCP-1 and the corresponding receptor CCR2 have been demonstrated in renal transplant rejection and coronary artery disease. The impact of the MCP-1-2518G and CCR2-64I genotypes on renal allograft function was investigated in 232 patients who underwent transplantation over an 11-yr period. Genomic DNA was genotyped using PCR with sequence-specific primers followed by restriction fragment length polymorphism analysis. Eighteen (7.8%) patients were homozygous for the MCP-1-2518G mutation. The G/G allele of MCP-1 -2518 behaved as a determinant for long-term allograft survival and resulted in reduction of the mean graft survival, as compared with the heterozygous (A/G) or wild-type (A/A) allele (67 +/- 14 versus 95 +/- 4 mo; Log rank P = 0.0052). The 64I mutation of CCR2 had no effect on kidney graft failure (93 +/- 6 and 91 +/- 5 mo, respectively; P = 0.81). None of the investigated polymorphisms showed a significant shift in gene frequency in acute rejection and rejection-free groups. In conjunction with these findings, peripheral blood mononuclear cells from kidney transplant recipients carrying the G-allele were characterized by a 2.5-fold higher MCP-1 secretion (P < 0.05). In conclusion, recipients of renal transplants homozygous for the -2518 G mutation of the MCP-1 gene are at risk for premature kidney graft failure. This variant of MCP-1 may be a future predictor for long-term kidney graft failure.

Acute Disease↗
PubMed2000

Tunneled-cuffed catheter associated infections in hemodialysis patients who are seropositive for the human immunodeficiency virus.

Infection rates in tunneled-cuffed catheters (TCC) are reported to be higher in immunocompromised patients. The purpose of this study was to evaluate TCC-associated infection rates in patients with HIV infection (HIV+). Data were collected in 40 HIV + patients and 41 controls (C), and in 118 TCC (HIV+, 58; C, 60) for 28,146 catheter days (HIV+, 16,227; C, 11,919). There were no significant differences in the TCC bacteremia rates (HIV+, 2.23 versus C, 2.53 per 1000 TCC days, P: = NS) or in the TCC exit site infection rates (HIV+, 2.20 versus C, 2.24 per 1000 TCC days, P: = NS) between the groups. The number of TCC removed due to infection was also similar, (HIV+ versus C: 17 versus 15%, P: = NS). In the HIV+ group, the association of hepatitis B surface antigenemia with TCC exit site infection was dependent on the history of injection drug use. Black race was a significant risk factor for higher TCC exit site infection rates, whereas prophylactic antibiotic use and high CD4 count were significantly associated with lower TCC exit site infection rates. None of the factors significantly predicted bacteremia rate in either group (HIV+ or C). In comparison to controls, HIV+ patients had a fivefold increased risk of having a Gramnegative organism (P: = 0.02) and a sevenfold increased risk of a fungal isolate (P: = 0.08), although the latter finding was not statistically significant. HIV infection is not a significant risk factor for TCC-associated infection but is associated with a higher prevalence of Gram-negative and fungal species.

Adult↗
PubMedDate not supplied

Regulation of glucose transporters in human peritoneal mesothelial cells.

BACKGROUND: Risk factors for peritoneal fibrosis and mesothelial cell (MsC) injury in CAPD are infections and bioincompatibility of the dialysate, including high glucose concentrations. To study a potential link between dialysate and glucose toxicity in MsC, we investigated the expression of facilitative glucose transporters (GLUT), which could contribute to glucose toxicity. METHODS: After induction of cell differentiation, MsC were incubated in regular medium or medium with 60 mM D-glucose, 30 mM glucose plus 30 mM mannitol, 60 mM mannitol, PD effluent, or with a cytokine mix. Expression of GLUT1, GLUT3, SGLT and GAPDH/L32 was studied by RNase protection assay. MsC were incubated under identical conditions with 14C-fluoro-deoxy-glucose for 30 minutes and glucose uptake was measured. To estimate Vmax and Km, 14C-fluoro-deoxy-glucose uptake rates were determined over a range of 0.6 to 10 mM unlabeled glucose. RESULTS: The cytokine mix significantly stimulated GLUT1 expression (3-fold) and GLUT3 (1.7-fold). There was a 1.4-fold increase in GLUT1 (p<0.05) and a 1.7-fold increase in GLUT3 (p<0.05) after incubation in high glucose but not in mannitol or PD-effluent controls. Glucose uptake studies confirmed this increase after incubation in 30 mM (p<0.05) and 60 mM glucose solutions. Kinetic studies showed the Km was approximately 3.7 mM for this transport. CONCLUSIONS: GLUT mRNA expression and glucose uptake are induced by high ambient glucose concentrations and cytokines. Unlike many other cells, MsC are not able to protect themselves from increased glucose concentrations by downregulation of GLUTs. The intracellular glucose concentration may therefore increase during CAPD, affecting growth factor expression and glycosylation, and contributing to glucose toxicity.

Biological Transport, Active↗