Alteration in the Cerebrospinal Fluid Lipidome in Parkinson's Disease: A Post-Mortem Pilot Study

Abstract

Lipid metabolism is clearly associated to Parkinson's disease (PD). Although lipid homeostasis has been widely studied in multiple animal and cellular models, as well as in blood derived from PD individuals, the cerebrospinal fluid (CSF) lipidomic profile in PD remains largely unexplored. In this study, we characterized the post-mortem CSF lipidomic imbalance between neurologically intact controls (n = 10) and PD subjects (n = 20). The combination of dual extraction with ultra-performance liquid chromatography-electrospray ionization quadrupole-time-of-flight mass spectrometry (UPLC-ESI-qToF-MS/MS) allowed for the monitoring of 257 lipid species across all samples. Complementary multivariate and univariate data analysis identified that glycerolipids (mono-, di-, and triacylglycerides), saturated and mono/polyunsaturated fatty acids, primary fatty amides, glycerophospholipids (phosphatidylcholines, phosphatidylethanolamines), sphingolipids (ceramides, sphingomyelins), N-acylethanolamines and sterol lipids (cholesteryl esters, steroids) were significantly increased in the CSF of PD compared to the control group. Interestingly, CSF lipid dyshomeostasis differed depending on neuropathological staging and disease duration. These results, despite the limitation of being obtained in a small population, suggest extensive CSF lipid remodeling in PD, shedding new light on the deployment of CSF lipidomics as a promising tool to identify potential lipid markers as well as discriminatory lipid species between PD and other atypical parkinsonisms.

Keywords: Parkinson’s disease; cerebrospinal fluid; lipidomics; lipids; mass-spectrometry.

Figure A1

Score scatter plot of the PCA model of CSF, Pool and QC samples. Pool: 15 µl of each CSF sample was collected and pooled together. Model diagnostics (A = 6, R2X = 0.829, Q2X = 0.496).

Figure A2

Score scatter plot of the PCA model of CSF samples. Model diagnostics (A = 6, R2X = 0.807, Q2X = 0.401).

Figure A3

Score scatter plot of the PCA model of CSF samples after square root transformation of the data. Model diagnostics (A = 4, R2X = 0.752, Q2X = 0.505).

Figure A4

Loadings scatter plot of the PCA model of cerebrospinal fluid samples after square root transformation of the data. Model diagnostics (A = 4, R2X = 0.752, Q2X = 0.505).

Figure 1

Lipidomic workflow applied in our pilot study.

Figure 2

Score scatter plot (left panel) and loadings scatter plot (right panel) of the OPLS-DA model of CSF samples after square root transformation of the data. Model diagnostics (A = 9; R2X = 0.860; Q2X = 0.150).

Figure 3

Heatmap representing differential individual metabolic features obtained from the global PD and control comparison and based on disease duration and neuropathological staging. Log transformed ion abundance ratios are depicted, as represented by the scale. Darker green and red colors indicate the change intensity of the metabolite levels, respectively. Grey lines correspond to significant fold-changes of individual metabolites; darker grey colors have been used to highlight higher significances (p < 0.05, p < 0.01 or p < 0.001). It is relevant to highlight that metabolites have been ordered in the heatmap according to their carbon number and unsaturation degree of their acyl chains. Heatmap color codes for log2 (fold change) and unpaired Student’s t-test p-values are indicated at the bottom of the heatmap. Metabolite order is supplied in the “Heatmap datasheet” in Tables S1–S3.

Figure 4

Volcano plot [−log10(p-value) vs. log2(fold-change)] for the PD vs. control subjects comparison. This volcano plot highlights the significance p-value < 0.01 for glycerolipids and, more specifically, triacylglycerols (TAG).

Figure 5

Boxplots of glycerolipids (monoacylglycerols (MAG), diacylglycerols (DAG), triacylglycerols (TAG)), phosphatidylcholines (PC) and sphingolipids (ceramides (Cer), sphingomyelins (SM)) (left). Boxplots of non-esterified fatty acids (NEFA) (saturated fatty acids (SFA), monounsaturated fatty acids (MUFA)), primary fatty amides (FAA) and sterol lipids (cholesteryl esters (ChoE), steroids (ST)) (right). significances (*; p < 0.05 and **; p < 0.01).

Figure 6

Pathway localization of deregulated lipid species detected in post-mortem CSF in PD. (A) Biosynthetic pathway of n-3 and n-6 fatty acids, (B) de novo lipogenesis and (C) lipid biosynthesis. Delta-6 desaturase (Δ6D), Delta-5 desaturase (Δ5D), elongase (ELOVL), beta-oxidation (β-ox), cyclooxygenase-2 (COX-2), phospholipases (PL). Fatty acid synthase (FAS), long-chain elongase (LCE), stearoyl-CoA desaturase (SCD), Glycerol 3-phosphate (G3P), phosphatidic acids (PA), phosphatidylinositols (PI), lysophosphatidylinositols (LPI), acyl carnitines (AC), unesterified cholesterol (UC), cholesterol sulfate (CS), cholesteryl esters (CE), steroids (ST), phodphatidylserines (PS), phosphatidylglycerols (PG), lysophosphatidylglycerols (LPG), cardiolipins (CL), S-adenosylmethionine (SAMe). Red arrows indicate significant increments in CSF lipid levels (p < 0.05). Grey arrows indicate non-significant increments in CSF lipid levels (p > 0.05). Orange areas represent routes carried out at the mitochondrial level.