Lipidomic UPLC-MS/MS Profiles of Normal-Appearing White Matter Differentiate Primary and Secondary Progressive Multiple Sclerosis

Abstract

Multiple sclerosis (MS) is a neurodegenerative inflammatory disease where an autoimmune response to components of the central nervous system leads to a loss of myelin and subsequent neurological deterioration. People with MS can develop primary or secondary progressive disease (PPMS, SPMS) and differentiation of the specific differences in the pathogenesis of these two courses, at the molecular level, is currently unclear. Recently, lipidomics studies using human biofluids, mainly plasma and cerebrospinal fluid, have highlighted a possible role for lipids in the initiation and progression of MS. However, there is a lack of lipidomics studies in MS on CNS tissues, such as normal-appearing white matter (NAWM), where local inflammation initially occurs. Herein, we developed an untargeted reverse phase ultra-performance liquid chromatography time of flight tandem mass spectrometry (RP-UPLC-TOF MSE)-based workflow, in combination with multivariate and univariate statistical analysis, to assess significant differences in lipid profiles in brain NAWM from post-mortem cases of PPMS, SPMS and controls. Groups of eight control, nine PPMS and seven SPMS NAWM samples were used. Correlation analysis of the identified lipids by RP-UPLC-TOF MSE was undertaken to remove those lipids that correlated with age, gender and post-mortem interval as confounding factors. We demonstrate that there is a significantly altered lipid profile of control cases compared with MS cases and that progressive disease, PPMS and SPMS, can be differentiated on the basis of the lipidome of NAWM with good sensitivity, specificity and prediction accuracy based on receiver operating characteristic (ROC) curve analysis. Metabolic pathway analysis revealed that the most altered lipid pathways between PPMS and SPMS were glycerophospholipid metabolism, glycerophosphatidyl inositol (GPI) anchor synthesis and linoleic acid metabolism. Further understanding of the impact of these lipid alterations described herein associated with progression will provide an increased understanding of the mechanisms underpinning progression and highlight possible new therapeutic targets.

New Insights into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration

“…Further understanding of the impact of lipid alterations on MS progression was provided by Pousinis et al [ 8 ]. They developed untargeted lipidomic of postmortem WM tissues in order to differentiate potential lipid-based biomarkers between PPMS and SPMS disease subtypes as well as between both PPMS and SPMS compared to samples from cerebral NAWM.…”

“…In order to obtain a better understanding of the pathophysiology of MS, we focused on the lipids that are considered to play a significant role in the disease background. Lipids are not only substantially involved in the formation of myelin sheath (and thus could be a hallmark of demyelination and repair), but are also engaged in the cell signaling, in communication, and in transport in the CNS [ 8 ]. Thus, they seem likely candidates for biomarkers of processes underlying active and progressive phase of MS, as well as potential target for new, effective, and stage-specific therapeutic interventions [ 9 , 10 ].…”

Omics approaches to understanding the efficacy and safety of disease-modifying treatments in multiple sclerosis

“…Elevated concentrations of ROS and cytokines in MS (Rajda et al, 2017) give rise to its release leading to the production of proinflammatory compounds, such as prostaglandins and leukotrienes, that are upregulated in this pathology and seem to be involved in the pathogenic mechanisms of demyelination, axonal pathology and oligodendrocyte loss, contributing to the development of motor disabilities. Changes in the lipid homeostasis and metabolism seem to be a hallmark of MS. To investigate the lipid profile can contribute to the better understanding of the pathophysiology of the disease (Pousinis et al, 2020). Moreover, this interesting class of compounds can be considered candidates for biomarkers of different aspects of MS, such as active and progressive phases of MS or potential target for new therapeutic approaches (Harlow et al, 2015).…”

“…Lipids are also involved in cell signaling, in communication, and in transport in the CNS ( Pousinis et al, 2020 ) as well as inflammatory processes ( Reale and Sanxhez-Ramon, 2017 ). In this regard, the metabolic pathway of arachidonic acid (AA) is overactivated in the CNS of MS patients ( Palumbo, 2017 ).…”

Identification of Lipid Heterogeneity and Diversity in the Developing Human Brain

“…While lipids are essential to many organs, they are particularly important for brain function because they are involved in cell shape and membrane formation, − anchoring of membrane proteins, and neuropeptide signaling . While the lipidome is less characterized compared to other molecular classes such as proteins and genes, several efforts have served to provide key information that demonstrates the importance of lipids within neuroscience. − These studies demonstrate the importance of studying the lipidome on the single cell level within human embryonic development. Tu et al., for instance, demonstrated that glycerophospholipids decreased with age, while sphingolipids increased with age.…”