Unknown,Transcriptomics,Genomics,Proteomics

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Leukocyte accumulation in graft blood vessels during self-limiting acute rejection of rat kidneys Immunobiology

ABSTRACT: Acute rejection episodes trigger chronic renal allograft vasculopathy. Numerous leukocytes, predominantly monocytes, accumulate in graft blood vessels during reversible acute rejection preceding chronic rejection of rat kidneys. We speculate that they contribute to transplant vasculopathy and set out to characterize them. Allogeneic renal transplantation was performed in the Fischer 344 to Lewis rat strain combination, Lewis isografts served as controls. Leukocytes were harvested by intensive perfusion of graft blood vessels and subjected to flow cytometry, quantitative RT-PCR and genome-wide transcriptional profiling. Kidneys of LEW and F344 rats were transplanted in LEW rats. Five biological replicates were performed for both isogenic and allogenic transplantation. Transcriptomes of allogenics were compared to isogenics on 5 dual-color hybridizations.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Jochen Wilhelm

PROVIDER: E-GEOD-18266 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Objective: Apolipoprotein E (Apo E) is a multifunctional protein, originally described in the context of lipoprotein metabolism and cardiovascular disease. More recently, anti-inflammatory functions of ApoE have been documented. ApoE was studied in the context of several inflammatory disorders, but its role in the pathogenesis of acute organ rejection is unknown. In this study, we test the hypothesis that ApoE attenuates acute renal allograft rejection. Materials and methods: The Dark Agouti (DA) to Lewis (Lew) and the Brown Norway (BN) to Lew rat strain combinations were used to investigate fatal acute rejection. In addition, Fischer 344 (F344) kidneys were transplanted to Lew rats to study reversible acute rejection. Isograft recipients and untreated Lew rats were used as controls. ApoE mRNA expression was quantified in intravascular leukocytes accumulating in the blood vessels of renal grafts and in graft tissue. Apo E protein levels were assessed in blood plasma. To test the protective potential of ApoE, recipients of BN kidneys were treated with ApoE-mimetic peptide. Results: Intravascular graft leukocytes and renal tissue obtained from animals undergoing reversible acute rejection expressed increased levels of ApoE mRNA, whereas during fatal rejection, ApoE expression remained unchanged in the BN to Lew rat strain combination or was significantly reduced when DA rats were used as donors of the kidney. On the protein level, no changes in ApoE were seen in plasma. However, we do not know if local leukocytic ApoE expression results in increased ApoE concentrations inside graft blood vessels. Peptide treatment of allograft recipients reversed fatal rejection and significantly improved animal survival. Conclusions: ApoE plays a protective role in acute organ rejection. Further studies are needed to understand the exact mechanism how ApoE reverses acute rejection. dual-color balanced dye-swap design with 4 biological replicates, hybridized on 4 arrays

Project description:The frequency of delayed function of kidney transplants varies greatly and is associated with the quality of graft, donor age, and the duration of cold ischemia time. Body weight differences between donor and recipient can affect primary graft function. The underlying mechanism is poorly understood. Here, we have transplanted kidney grafts from commensurate body weight (L-WD) or reduced body weight (H-WD) donor rats into syngeneic or allogeneic recipients. 24 hours post-transplantation, serum creatinine level in H-WD recipients was significantly higher compared to that of L-WD recipients indicating impaired primary graft function. We detected a 10 fold higher transcription of IL-6 and dramatically increased tubular destruction in grafts from H-WD recipients. This was accompanied by decreased expression of genes associated with kidney function and an up-regulation of other genes such as cytochrome P450 isoforms, FosL and Trib3 as revealed by DNA microarray analysis. A single application of IL-6 into L-WD recipients is sufficient to impair primary graft function and to cause tubular damage. Whereas, immediate neutralization of IL-6 receptor signaling rescued primary graft function resulting in low serum creatinine levels, well-preserved kidney graft architecture and a normalized gene expression profile. These findings have strong clinical implication as anti-IL6R treatment of patients receiving grafts from lower-weight donors could be used to improve primary graft function. The dataset comprises eight samples divided into four sample groups. Each group represents rat kidneys collected after allogeneic transplantation under a certain condition and includes two biological replicates. The first group is characterized by a high body weight difference between donor and recipient, rats in the second group exhibit a low weight difference. Group three and four are similar to group one, but underwent an additional treatment with anti-IL6R mAb or prednisolone immediately after transplantation.

Project description:Expression profiling of rat major histocompatibility complex and natural killer complex genes in skin explant assays reveals genes that are regulated in graft versus host disease. The major histocompatibility complex (MHC) is the most important genomic region that contributes to the genetic risk of graft rejection and graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Therefore, MHC matching is most essential for the success of clinical transplantations. However, the MHC contains in addition to MHC class I and class II genes that are genotyped for selection of donors further so far unidentified genes that also contribute significantly to the risk to develop acute GVHD. It is difficult to identify these MHC genes by genetic association studies alone due to linkage disequilibrium in this region. Therefore, we aimed to identify MHC genes that might be involved in the pathohysiology of GVHD by expression profiling. To reduce the complexity of our model, we used genetically well-defined inbred rat strains (PVG and BN) and skin explant assays, an in-vitro-model of graft versus host reaction (GVHR), to analyse the expression of MHC and natural killer complex (NKC) genes in a cutaneous GVHR by a custom microarray. A higher percentage of genes in these immunologically highly important genomic regions were regulated than in the rest of the genome. We observed a statistically significant regulation of 25 MHC and 6 NKC genes and 168 other genes (i.e., 4.9%, 14.0%, and 6.6%, respectively) in rat skin explants cultured in the presence of pre-stimulated allogeneic lymphocytes compared to control samples cultured in the presence of syngeneic lymphocytes. Seven MHC and 3 NKC genes were selected for analysis by quantitative real-time polymerase chain reaction PCR. Most of the results of the microarray were confirmed in the same experimental set that was used for the microarray analysis and in a second independent experimental set of skin explant samples. In addition, GVHD-affected skin lesions of transplanted rats were analysed and similar regulations of most of the selected MHC and NKC genes were observed. Thus, our skin explant model of GVHR is informative for the gene regulation during GVHD. Interestingly, the human homologues of several of the regulated genes are polymorphic and could therefore contribute to the genetic risk of GVHD. These genes include RT1-Dmb, C2, Aif1, Spr1, Ubd, and Olr1. The human homologues of these genes might be useful for risk assessment and diagnosis of GVHD in patients. Two-condition experiment, Stimulated vs. NonSimulated cells. 12 Biological replicates, 2 Technical Replicates (Dye Swap) per Biological Replicate.

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Leukocyte accumulation in graft blood vessels during self-limiting acute rejection of rat kidneys Immunobiology

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