Inter-patient heterogeneity in the hepatic ischemia-reperfusion injury transcriptome: implications for research and diagnostics [MUG data]
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ABSTRACT: Background & Aims: Cellular responses induced by surgical procedure or ischemia-reperfusion injury (IRI) may severely alter transcriptome profiles. We have investigated this effect to obtain insight into molecular ischemia responses during surgical procedures and characterize pre-analytical effects impacting on molecular analyses. Methods: 143 non-malignant liver samples were obtained from 30 patients at different time points of ischemia during surgery from two individual cohorts, treated either with the Pringle maneuver or total vascular exclusion. Transcriptomics profiles were analyzed by Affymetrix microarrays and expression of selected mRNAs was validated by RT-qPCR. Results: Transcriptional profiles of both cohorts displayed 179 genes that were mutually deregulated confirming elevated cytokine signaling, and NFkB as the dominant pathways in ischemia response. Contrary to ischemia, reperfusion induced pro-apoptotic and pro-inflammatory cascades involving TNF, NFkB and MAPK pathways. FOS and JUN were down-regulated in steatosis compared to their up-regulation in normal livers. Surprisingly, molecular signatures of underlying primary and secondary cancers were clearly present in the non-tumor tissue. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications.
Project description:Background & Aims: Cellular responses induced by surgical procedure or ischemia-reperfusion injury (IRI) may severely alter transcriptome profiles. We have investigated this effect to obtain insight into molecular ischemia responses during surgical procedures and characterize pre-analytical effects impacting on molecular analyses. Methods: 143 non-malignant liver samples were obtained from 30 patients at different time points of ischemia during surgery from two individual cohorts, treated either with the Pringle maneuver or total vascular exclusion. Transcriptomics profiles were analyzed by Affymetrix microarrays and expression of selected mRNAs was validated by RT-qPCR. Results: Transcriptional profiles of both cohorts displayed 179 genes that were mutually deregulated confirming elevated cytokine signaling, and NFkB as the dominant pathways in ischemia response. Contrary to ischemia, reperfusion induced pro-apoptotic and pro-inflammatory cascades involving TNF, NFkB and MAPK pathways. FOS and JUN were down-regulated in steatosis compared to their up-regulation in normal livers. Surprisingly, molecular signatures of underlying primary and secondary cancers were clearly present in the non-tumor tissue. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications. Conclusions: We identified transcripts mutually deregulated during ischemia and reperfusion injury in both cohorts that can be used to monitor ischemia during liver surgery and highlight the importance of pre-analytical quality control. The marked inter-patient variability might reflect differences in individual stress responses and impact of underlying disease conditions. Furthermore, we provide a comprehensive and pre-analytically highly standardized in vivo transcriptome profile of histologically normal liver and identified 230 genes with substantial pre-analytical robustness (<2 % covariation across both cohorts) that might serve as reference genes and could be particularly suited for future diagnostic applications.
Project description:Ischemia/reperfusion injuries is a known complication to hepatic surgery. Ischemic pre- (IPC) and postconditioning (IPO) protects the liver against ischemia/reperfusion-injuries. Expression profiling were performed on liver biopsies seeking to identify molecular mediators of the protective properties. 48 rats were divided into 5 groups; sham (n=8), IRI (n=10), IPC (n=10), IPO (n=10) and IPC+IPO (n=10). All rats except sham rats were subjected to 30 min of total liver ischemia and 30 min of reperfusion before liver biopsies were sampled. In the IPC group, liver ischemia was preceded by 10 min of hepatic ischemia, followed by 10 min of reperfusion. IPO were performed by three cycles of 30 sec of reperfusion and 30 sec of ischemia, applied immediately after the 30 min of total liver ischemia. In the IPC+IPO group the two interventions were combined.
Project description:Ischemia/reperfusion injuries is a known complication to hepatic surgery. Ischemic pre- (IPC) and postconditioning (IPO) protects the liver against ischemia/reperfusion-injuries. Expression profiling were performed on liver biopsies seeking to identify molecular mediators of the protective properties.
Project description:This study aims to determine changes in transcriptomic profiles in lymphatic vessels in response to ischemia-reperfusion injury, which mimics conditions in liver transplantation. This experiment will determine the potential role of lymphatic vessels during the ischemia-reperfusion injury in the liver.
Project description:Study was performed in groups of animals including healthy controls, ischemia reperfusion alone, and administration of drug followed by ischemia reperfusion. Samples from liver and isolated hepatocytes intact and one day after reperfusion were analyzed for gene expression in conjunction with other biological variables. Results indicated substantive alteration after drug intervention in multiple gene ontology groups and cellular events and processes after ischemia reperfusion.
Project description:For orthotopic liver transplants, ischemia-reperfusion injury (IRI) is known to compromise allograft survival. To better understand the transcriptomics of immune responses underlying liver transplant IRI, RNA-seq was performed on liver biopsies from 23 IRI+ and 17 IRI- patients, both pre-transplant and post-transplant. Genes that are differentially expressed in IRI+ samples, along with the pathways enriched for by those genes, were identified.
Project description:Purpose: Acute kidney injury (AKI) is defined as a sudden event of kidney failure or kidney damage occurring within a short period. Ischemia-reperfusion injury (IRI) is a critical factor to induce severe AKI and end-stage kidney disease in the kidney. However, biological mechanisms of ischemia and reperfusion are not well elucidated due to its complex pathophysiological processes. We aim to investigate key biological pathways affected by ischemia and by reperfusion separately at the transcriptome level. Method: We analyzed steady-state gene expressions using RNA-seq transcriptome data for normal (pre-ischemia), ischemia and reperfusion conditions obtained from the human kidney tissue. A conventional differential expression analysis and self-organizing map (SOM) clustering analysis followed by pathway analysis were performed to identify the underlying biological mechanisms of ischemia and reperfusion. Results: Differential expression analysis showed that metabolism and gap junction-related pathways were dysregulated in ischemia, whereas hypertrophy and immune response-related pathways were dysregulated in reperfusion. In addition, SOM clustering analysis revealed that metabolism, apoptosis, and fibrosis-related pathways were significantly dysregulated by ischemia compared to pre-ischemia. On the other hand, cell growth, migration, and immune response-related pathways were highly dysregulated by reperfusion after ischemia. Pro-apoptotic genes and death receptors were down-regulated during ischemia, indicating a protective process against ischemic injury. Reperfusion induced alteration of genes associated with immune components such as B-cell, neutrophil, and interleukin-15. Additionally, genes related to cell growth and migration such as AKT, KRAS, and Rho signaling were down-regulated, which might imply injury responses during reperfusion. Semaphorin 4D and plexin B1 were also down-regulated. However, further investigations are needed to identify their roles. Conclusion: We showed that specific biological pathways were distinctively involved in ischemia and reperfusion during IRI, suggesting that condition-specific therapeutic strategies may be required to prevent severe kidney damage after IRI in clinical research.
Project description:Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell’s condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ~0.007 mM could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.