Postprandial Hypertriglyceridemia‐induced Brain Vascular Inflammation by Next‐Generation Sequencing

Vascular dementia (VaD), the second most common form of dementia, is associated with vascular risk factors, such as hyperlipidemia. The pathophysiological mechanisms and potential therapies for VaD are poorly understood; however, previous studies suggest a relationship of blood lipids and/or lipoproteins to vascular inflammation leading to dementia. The objective of this study is to characterize brain endothelial cell responses to postprandial triglyceride‐rich lipoproteins (TGRL) and determine the pathways that have potential to increase risk for vascular dementia. To address this question, we treated human brain microvascular endothelial cells (HBMVEC) with TGRL lipolysis products and then we used next‐generation sequencing (NGS)‐based RNA sequencing (RNA‐Seq) methods for transcriptional profiling experiments. Genome‐wide analyses of transcription of single nucleotides were generated on the Illumina HiSeq3000 sequencer. We then identified regulatory genes and their targets in RNA‐Seq datasets that have been differentially expressed using TopHat mapper and EdgeR statistical software packages. The Grinn software tool was used to retrieve pathway annotations of significant genes. The R package Piano was used for pathway enrichment analysis. System biology analysis showed that TGRL lipolysis products activated 108 signaling pathways of which 48 signaling pathways were significantly activated. Among them, the most significant (p value =0) activated signaling pathways were MAPK (20 up‐regulated and 4 down‐regulated genes), TNF (16 up‐regulated and 4 down‐regulated genes) and Influenza A (10 up‐regulated and 4 down‐regulated genes). Stress response related genes (activating transcription factor 3 (ATF3), ATF4, Jun dimerization protein 2, sestrin 2, growth arrest and DNA damage inducible alph, DNA damage inducible transcript 3 (DDIT3) and DDIT4) and inflammatory response related genes (CCAAT/enhancer binding protein beta (CEBPB), VEGFA, gamma‐glutamylcyclotransferase 1, and TNF superfamily member 18, IL‐1 alpha) were up‐regulated and confirmed by qRT‐PCR analysis. System biology analysis has led to the validation of putative lipid‐related targets and the discovery of 510 genes and corresponding isoforms that may be implicated in hypertriglyceridemia‐induced vascular inflammation in brain. Furthermore, the results of RNA‐Seq determined specific isoforms of key transcriptional regulator ATF3 and stress response signaling pathway in lipolysis product‐mediated brain vascular inflammation which may lead to vascular dementia. Support or Funding Information NIH‐NIA AG045541, NIH‐NIA AG039094, Richard A. and Nora Eccles Harrison Endowed Chair in Diabetes Research.