Lipidomics and Transcriptomics in Neurological Diseases

Abstract

Lipids serve as the primary interface to brain insults or stimuli conducive to neurological diseases and are a reservoir for the synthesis of lipids with various signaling or ligand function that can underscore the onset and progression of diseases. Often changing at the presymptomatic level, lipids are an emerging source of drug targets and biomarkers. Many neurological diseases exhibit neuroinflammation, neurodegeneration, and neuronal excitability as common hallmarks, partly modulated by specific lipid signaling systems. The interdependence and interrelation of synthesis of various lipids prompts a multilipid, multienzyme, and multireceptor analysis in order to derive the commonalities and specificities of neurological contexts and to expedite the unravelling of mechanistic aspects of disease onset and progression. Ascribing lipid roles to distinct brain regions advances the determination of lipid molecular phenotype and morphology associated with a neurological disease. Presented here is a modular protocol suitable for the analysis of membrane lipids and downstream lipid signals along with mRNA of enzymes and mediators underlying their functionality, extracted from discrete brain regions that are relevant for a particular neurological disease and/or condition. To ensure accurate comparative lipidomic profiling, the workflows and operating criteria were optimized and standardized for: i) brain sampling and dissection of regions of interest, ii) co-extraction of multiple lipid signals and membrane lipids, iii) dual lipid/mRNA extraction, iv) quantification by liquid chromatography multiple reaction monitoring (LC/MRM), and v) standard mRNA profiling. This workflow is amenable for the low tissue amounts obtained by sampling of the functionally discrete brain subregions (i.e. by brain punching), thus preventing bias in multimolecular analysis due to tissue heterogeneity and/or animal variability. To reveal peripheral consequences of neurological diseases and establish translational molecular readouts of neurological disease states, peripheral organ sampling, processing, and their subsequent lipidomic analysis, as well as plasma lipidomics, are also pursued and described. The protocol is demonstrated on an acute epilepsy mouse model.