Project description:Warfare has long been associated with traumatic brain injury (TBI) in militarized zones. Common forms of TBI can be caused by a physical insult to the head-brain or by the effects of a high velocity blast shock wave generated by the detonation of an explosive device. While both forms of trauma are distinctly different regarding the mechanism of trauma induction, there are striking similarities in the cognitive and emotional status of survivors. Presently, proven effective therapeutics for the treatment of either form of TBI are unavailable. To be able to develop efficacious therapies, studies involving animal models of physical- and blast-TBI are required to identify possible novel or existing medicines that may be of value in the management of clinical events. We examined indices of cognition and anxiety-like behavior and the hippocampal gene transcriptome of mice subjected to both forms of TBI. We identified common behavioral deficits and gene expression regulations, in addition to unique injury-specific forms of gene regulation. Molecular pathways presented a pattern similar to that seen in gene expression. Interestingly, pathways connected to AlzheimerM-bM-^@M-^Ys disease displayed a markedly different form of regulation depending on the type of TBI. While these data highlight similarities in behavioral outcomes after trauma, the divergence in hippocampal transcriptome observed between models suggests that, at the molecular level, the TBIs are quite different. These models may provide tools to help define therapeutic approaches for the treatment of physical- and blast-TBIs. Based upon observations of increasing numbers of personnel displaying TBI related emotional and behavioral changes in militarized zones, the development of efficacious therapies will become a national if not a global priority. Keywords: Physical-traumatic brain injury; Blast-traumatic brain injury; Cognitive dysfunction; Gene expression; Molecular pathway(s); Neurodegeneration; Stem cells; AlzheimerM-bM-^@M-^Ys disease A mild physical-TBI was induced using a concussive head trauma device described previously (Milman et al., 2005; Zohar et al., 2003). Briefly, mice were lightly anesthetized (Isoflurane) and placed under the weight-drop concussive head trauma instrument. The device consisted of a metal tube (inner diameter 13 mm), placed vertically over the mouse head. A metal weight (30 g) was dropped from the top of the tube (80 cm) and struck the skull at the right side temporal area between the corner of the eye and the ear. A sponge supported the head, allowing some antero-posterior motion without any rotational head movement at the moment of the impact. Experimental conditions used to create a mild low-level blast-TBI and the subsequent model characterization, have been described in detail elsewhere (Rubovitch et al., 2011). In brief, mice were anaesthetized with a combination of ketamine (100 mg/kg) and xylazine (10 mg/kg). Once the animals were fully anaesthetized they were placed at a defined distance from a detonation source, in this case 7 meters. Pressure sensors were used to measure the explosion shock wave pressure (PSI) generated by the detonation (Free-Field ICPM-BM-. Blast Pressure Sensor; PCB Piezoelectronics, Depew, NY, USA, Model 137). At 7 meters from the source of the detonation, the animals were exposed to a maximum of a 2.5 PSI (17.2 kPa) pressure shock wave. Immediately after the induction of the injury, mice were placed back in their cages. Once the animals had recovered from the anesthesia, basic neurological assessments were undertaken to identify any acute neurological dysfunction. Only animals exhibiting no evidence of acute neurological damage post injury were subsequently used in further experiments. Sham treated mouse groups were treated identically; however, they were not exposed to physical- or blast-TBI. Mouse hippocampus tissues were randomly selected from the larger library of samples generated from the behavioral experiments and the numbers utilized in the gene expression study were as follows: sham, n = 5: physical-TBI, n = 4; blast-TBI, n = 7.

Project description:Warfare has long been associated with traumatic brain injury (TBI) in militarized zones. Common forms of TBI can be caused by a physical insult to the head-brain or by the effects of a high velocity blast shock wave generated by the detonation of an explosive device. While both forms of trauma are distinctly different regarding the mechanism of trauma induction, there are striking similarities in the cognitive and emotional status of survivors. Presently, proven effective therapeutics for the treatment of either form of TBI are unavailable. To be able to develop efficacious therapies, studies involving animal models of physical- and blast-TBI are required to identify possible novel or existing medicines that may be of value in the management of clinical events. We examined indices of cognition and anxiety-like behavior and the hippocampal gene transcriptome of mice subjected to both forms of TBI. We identified common behavioral deficits and gene expression regulations, in addition to unique injury-specific forms of gene regulation. Molecular pathways presented a pattern similar to that seen in gene expression. Interestingly, pathways connected to Alzheimer’s disease displayed a markedly different form of regulation depending on the type of TBI. While these data highlight similarities in behavioral outcomes after trauma, the divergence in hippocampal transcriptome observed between models suggests that, at the molecular level, the TBIs are quite different. These models may provide tools to help define therapeutic approaches for the treatment of physical- and blast-TBIs. Based upon observations of increasing numbers of personnel displaying TBI related emotional and behavioral changes in militarized zones, the development of efficacious therapies will become a national if not a global priority. Keywords: Physical-traumatic brain injury; Blast-traumatic brain injury; Cognitive dysfunction; Gene expression; Molecular pathway(s); Neurodegeneration; Stem cells; Alzheimer’s disease

Project description:Purpose: High throughput small RNA-Seq analysis from circulating biofluids is crucial in driving the discovery of non-invasive miRNA biomarkers for TBI. In this study, we focused our analysis on acute post-TBI alterations in plasma miRNA profiles in adult, male Sprague-Dawley rats. We compared the plasma miRNA profiles from naive, sham-operated controls and rats with mild and severe TBI. The aim was to identify a miRNA signature that would distinguish the rats with mTBI from the naive and sham-operated controls. Next, we compared the rats with mild and severe TBIs to investigate if a dose-dependent increase would occur in the plasma miRNA levels with corresponding increase in injury severities. Finally, we analysed if the sham surgery itself results in alterations in circulating miRNA profiles, by comparing the naive and sham-operated controls. Methods: TBI was induced with the lateral fluid percussion injury (FPI) model. Tail-vein plasma was collected at 2 days post-TBI from 31 adult male, Sprague-Dawley rats (5 naive, 8 sham-operated controls, 10 mTBI and 8 sTBI) under inhalation of isoflurane anesthesia. Small RNA-Seq was performed from plasma samples of a subset of 20 rats (5 cases each from naive, sham-operated controls, mTBI and sTBI groups). For each case, RNA was isolated from 200 µL plasma using the miRNeasy serum/plasma kit. The extracted RNA was subjected to qPCR-based quality control (QC). Small RNA library preparation was performed with the QIASeq miRNA library kit for Illumina NGS systems. Single-end sequencing of 75 bp reads was performed at a depth of 12M, with one sample/lane in the Illumina NextSeq 550. One naive plasma sample failed at the library preparation step. Hence, small RNA-Seq was succesful for 19/20 cases. The raw fastq files obtained from small RNA-Seq were first manually inspected with FastQC (v0.11.3) to check the overall quality of the sequencing data. For primary quantification of read counts, the fastq files were then uploaded to the Qiagen Geneglobe Data analysis center (DAC), a freely available web resource to analyze data from Qiagen’s QIASeq NGS library kits (https://geneglobe.qiagen.com/in/analyze/). Mapping was performed in the DAC portal with bowtie, using the rat reference genome RGSC Rnor_6.0. Annotation of miRNAs was performed with miRBase v21. Following primary quantification, differential expression analysis for miRNAs was performed with DESeq2 (v1.22.2) in R environment (v3.5.3). Logistic regression (LR) with feature selection utilizing nested leave-one-out cross-validation was also performed to identify miRNAs (“features”) contributing most to groupwise differences (differences between naïve, sham, mTBI, sTBI, sTBI + mTBI and naïve + sham). Results: A total of 748 miRNAs were detected across all samples, out of which 723 (97%) were expressed in all the four groups (naive, sham-operated, mTBI and sTBI). Based on the differential expression and logistic regression analyses, we identified five miRNA candidates that contributed most to the seperation between the mTBI and naive groups: rno-miR-9a-3p, rno-miR-153-3p, rno-miR-15a-3p, rno-miR-136-3p and rno-miR-434-3p. We validated the small RNA-Seq data for these miRNA candidates with miRCURY reverse transcriptase quantitative PCR (RT-qPCR). We could succesfully validate elevated levels of miR-9a-3p, miR-136-3p and miR-434-3p in the mTBI group in comparison to naive. When analysed from the whole cohort, the elevated levels of these miRNAs were consistently observed in the mTBI group compared to the naive, both with RT-qPCR and droplet digital PCR (ddPCR). Further, all the three miRNAs revealed elevated plasma levels in the sTBI group in comparison to the mTBI. Conclusions: Elevated plasma miRNA signature of miR-9a-3p, miR-136-3p and miR-434-3p distinguishes rats with mTBI from the naive, in the lateral FPI model of TBI. Further, all these miRNAs exhibit a dose-dependent increase in plasma levels with increase in injury severities.

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Comprehensive assessment of shockwave intensity: transcriptomic biomarker discovery for primary blast-induced mild traumatic brain injury (mTBI) using the mammalian hair follicle

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