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RNA Sequencing of WT Chronic Stroke Infarcts vs. Contralateral Cortices

ABSTRACT: We conducted bulk RNA sequencing on infarcts collected from young adult (3-month-old) mice at 7 weeks after the distal middle cerebral artery occlusion + hypoxia stroke model and compared them to contralateral cortices. As expected, differential expression (DE) analysis revealed marked differences between infarcts and contralateral cortices: 3,930 upregulated and 2,869 downregulated genes. The most significantly upregulated genes, including Lpl, Spp1, Cd36, Mmp2, and Mmp19, and the most highly enriched genes, including Cd5l, Mmp3, Mmp12, and Mmp13, indicate a pronounced disturbance in lipid homeostasis in infarcts at 7 weeks after stroke. In addition to alterations in lipid metabolic processes, the transcriptome also revealed a signature of chronic inflammation at 7 weeks after stroke. We then used IPA software to define upstream regulators and identify altered biological processes based on DE analysis. Differentially expressed genes were associated with the following upregulated biological processes: (i) atherosclerosis signaling, (ii) IL-1 signaling, (iii) inflammasome pathway, (iv) eicosanoid signaling, (v) B cell receptor (BCR) signaling, and (vi) phospholipases, along with others. IPA also identified lipid metabolic upstream regulators such as cholesterol, phospholipids, and LDL, as well as immunological upstream regulators such as MYD88, IL18, CD3, IL1B, TLR4, and TNF. These altered biological processes indicate that the stroke infarct transcriptome is characterized by chronic inflammation, dysregulated lipid metabolism, and impaired or absent neuronal function at 7 weeks after stroke.

ORGANISM(S): Mus musculus

PROVIDER: GSE173544 | GEO | 2021/04/30

REPOSITORIES: GEO

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Project description:Prior to assessing the impact of repeated HPβCD administration on the peri-infarct region of the brain, we first compared the transcriptome of the peri-infarct region to the equivalent region of the contralateral hemisphere in aged (18-month-old) mice at 7 weeks after distal middle cerebral artery occlusion + hypoxia (DH) stroke. The peri-infarct region was characterized by 3,910 differentially expressed genes. Of these, 2,123 were upregulated, many of which were also upregulated in infarcts at 7 weeks after stroke. For instance, the infarct and peri-infarct regions were both defined by the upregulation of degradative enzymes, TLRs, and scavenger receptors. In addition, the upregulation of Lpl, Lrp2, Ch25h, Apoe, Trem2, and Abca1 signified a divergence from lipid homeostasis. These alterations in innate immunity coincided with corresponding perturbations in adaptive immunity. The upregulation of Cd3d, Cd3e, Cd3g, Blnk, Sdc1 and Jchain suggests that chronic inflammation persists in peri-infarct regions for at least 7 weeks after stroke. Conversely, the DE analysis revealed that 1,787 genes were downregulated in peri-infarct regions compared to equivalent regions of the contralateral hemisphere. These genes were primarily involved in mitochondrial respiration and neuronal function. Together, these results demonstrate that the transcriptome of the peri-infarct region is characterized by the upregulation of genes involved in inflammation and lipid metabolism and the downregulation of genes involved in mitochondrial respiration and neuronal function. To evaluate the impact of HPβCD treatment on the transcriptome of the peri-infarct region, we also performed bulk RNA-Seq on brain tissue collected 7 weeks after DH stroke. For this analysis, we compared the peri-infarct regions of vehicle- and HPβCD-treated aged mice. The peri-infarct region of HPβCD-treated mice was characterized by 5,385 differentially expressed genes. The DE analysis revealed that peri-infarct regions of HPβCD-treated mice were characterized by the downregulation of multiple degradative enzymes, chemokine receptors, and scavenger receptors. In addition, the transcriptomic analysis demonstrated a restoration of lipid homeostasis in peri-infarct regions of HPβCD-treated mice compared to vehicle-injected mice, as evidenced by the downregulation of Lipa, Apoe, Lamp1, Npc1, and Npc2 and upregulation of Nceh1 and Ldlr. Reductions in innate and adaptive immune responses characterized peri-infarct regions of HPβCD-treated mice; these alterations are consistent with the attenuated chronic inflammation that characterized infarcts of the HPβCD-treated aged mice. These results demonstrate that HPβCD treatment after stroke attenuates chronic inflammation and promotes lipid metabolism in peri-infarct regions of aged mice. Additionally, the DE analysis revealed an upregulation of genes involved in myelin sheath structural integrity, such as Ina, Omg, and Nefl, and synaptic plasticity and neuroplasticity, such as Syn1, Bdnf, Nrg1, Negr1, and Nsg1. These results suggest that HPβCD treatment improves the structure and function of neurons in peri-infarct regions of aged mice after stroke.

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.

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 naïve (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.

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RNA Sequencing of WT Chronic Stroke Infarcts vs. Contralateral Cortices

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