RNA Sequencing of WT Chronic Stroke Infarcts vs. Contralateral Cortices

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. Bulk RNA sequencing was performed on chronic stroke infarcts and equivalent regions of the contralateral cortex to assess transcriptional changes that occur following ischemic stroke.