Unknown,Transcriptomics,Genomics,Proteomics

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Common molecular signature of two neuroprotective agents

ABSTRACT: The current lack of proven pharmacological treatment options for traumatic brain injury (TBI) patients reflects the poor translation of successful preclinical studies in clinical trials. This may be due to poor choice of therapeutic agents based on incomplete knowledge of critical elements of neuroprotection. Our goal is to expedite discovery and translation of therapeutic agents that can improve functional outcome by identifying the common molecular profile of neuroprotective drugs. Since damage to the hippocampus is associated with TBI-induced deficits in learning and memory, we analyzed of the hippocampal transcriptional profiles of TBI rats treated with two clinically used drugs metyrapone and carbenoxolone, which have been shown to improve cognitive deficits in previous studies. Despite their different structures, we found that MT and CB have similar effects on several known biological pathways. The neuroprotective effects of these drugs are associated with a distinctive molecular signature which is characterized not by changes in expression of any individual gene but by a common global effect on multiple cell signaling pathways. These data suggest that drug treatments that induce a coordinated attenuation of multiple injury-induced cell signaling networks, both deleterious and protective, have high translational potential. There were 16 samples for array analysis, two biological replicates each for control (4 and 24 hour), TBI (4 and 24 hour), TBI plus MT (4 and 24 hour) and TBI plus CB (4 and 24 hour). Each biological sample, which is a pooled RNA sample (laser captured CA3 pyramidal neurons) from the hippocampus of 3-6 rats, was hybridized to duplicate arrays so that there were 32 gene arrays in this study.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Michael Falduto

PROVIDER: E-GEOD-31357 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The development of a biodosimetric assay based on the combined gene expression analysis of ex vivo-irradiated human peripheral blood (PB) and humans treated with total body irradiation has been developed. Gene expression profile signature of human radiation injury into a rapid and high-throughput chemical ligation-dependent probe amplification assay (CLPA) has been shown to discriminate 6 radiation dose levels in human PB. Candidate gene lists were first developed assaying human ex vivo and human TBI samples on the Affymetrix platform. For the Ex Vivo samples, healthy consented adult donor was randomly assigned to a radiation group and labeled with the target dose of 0 cGy, 150 cGy, 300 cGy, or 600 cGy. In addition to the radiation exposures, the samples were also treated with either no treatment, GCSF, or LPS at time points 6 hours and 24 hours. Radiation expire times from the Cs137 irradiator were calculated to achieve target doses specific for tubes filled with blood and inserted in the roaring test tube holder. The dose rate was 480 cGy/min for the duration of the study. The healthy donors were enrolled to participate in this study following a protocol to collect PB samples that was previously approved by the Duke University Institutional Review Board. For the TBI samples, adult patients, ages 21 to 66, were evaluated at the Duke University Adult Bone Marrow Transplantation Program enrolled in a Duke IRB-approved protocol to collect PB prior to and post TBI conditioning. With approval from the Duke University Institutional Review Board (IRB), between 5-12 mL of peripheral blood was collected from consented patients prior to and 6 hours following TBI with 150-200 cGy as part of their pre-transplantation conditioning. All patients receiving non-myeloablative conditioning were treated with 200 cGy of TBI from a linear accelerator at a dose rate of 20 cGy/min. All patients who underwent TBI-based myeloablative allogeneic or autologous stem-cell transplantation received radiation fractionated at 150 cGy per fraction at 20 cGy/min. All patients had PB collected (50 ml) prior to and 6 hours following exposure to either 200 cGy or 150 cGy radiation treatment. The dose exposure for TBI patients used in this study were 0 cGy, 150 cGy, 450 cGy and 1050 cGy at 0, 6, 30 and 78 hours post irradiation. Total RNA was extracted and assayed on the Affymetrix platform.

Project description:Abstract Background Traumatic brain injury (TBI) results in irreversible damage at the site of impact and initiates cellular and molecular processes that lead to secondary neural injury in the surrounding tissue. We used microarray analysis to determine which genes, pathways and networks were significantly altered using a rat model of TBI. Adult rats received a unilateral controlled cortical impact (CCI) and were sacrificed 24h post-injury. The ipsilateral hemi-brain tissue at the site of the injury, the corresponding contralateral hemi-brain tissue, and naM-CM-/ve (control) brain tissue were used for microarray analysis. Ingenuity Pathway Analysis (IPA) software was used to identify molecular pathways and networks that were associated with the altered gene expression in brain tissues following TBI. Results Inspection of the top fifteen biological functions in IPA associated with TBI in the ipsilateral tissues revealed that all had an inflammatory component. IPA analysis also indicated that inflammatory genes were altered on the contralateral side, but many of the genes were inversely expressed compared to the ipsilateral side. The contralateral gene expression pattern suggests a remote anti-inflammatory molecular response. We created a network of the inversely expressed common (i.e., same gene changed on both sides of the brain) inflammatory response (IR) genes and those IR genes included in pathways and networks identified by IPA that changed on only one side. We ranked the genes by the number of direct connections each had in the network, creating a gene interaction hierarchy (GIH). Two well characterized signaling pathways, toll-like receptor/NF-kappaB signaling and JAK/STAT signaling, were prominent in our GIH. Conclusions Bioinformatic analysis of microarray data following TBI identified key molecular pathways and networks associated with neural injury following TBI. The GIH created here provides a starting point for investigating therapeutic targets in a ranked order that is somewhat different than what has been presented previously. In addition to being a vehicle for identifying potential targets for post-TBI therapeutic strategies, our findings can also provide a context for evaluating the potential of therapeutic agents currently in development. The ipsilateral hemi-brain tissue at the site of the injury, the corresponding contralateral hemi-brain tissue, and naM-CM-/ve (control) brain tissue (n=3 for each) were used for RNA isolation. The TBI injured animals were Todd 1, 2 Todd, and Todd 3, each yielding an ispilateral and contralateral sample. The naM-CM-/ve animals were Xu 13 control, Xu 2 control, and Xu 6 control.

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Common molecular signature of two neuroprotective agents

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