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Resolving mediators are altered in multiple sclerosis
A
B
C
Figure 3. Correlations between Expanded Disability Status Scale (EDSS) scores of patients and lipid mediators. Correlation plots between EDSS values and levels (pg/mL) of specific lipid mediators of the AA metabolome (A), DHA metabolome (B) and EPA metabolome (C) in the entire cohort of patients with multiple sclerosis. Data were compared by Spearman’s rank correlation coefficient (P<0.05).
t-test (two groups) or one-way ANOVA (multiple groups) fol- lowed by a post hoc Bonferroni test. P<0.05 was considered statis- tically significant.
Results
Multiple sclerosis patients show altered lipid mediators profiles in the blood
To address potential differences in LM profiles between MS patients and healthy donors, involving both pro- inflammatory and specialized pro-resolving lipid media- tors (SPM), we performed targeted LM metabololipidomics on human plasma samples using liq- uid chromatography tandem mass spectrometry (LC-MS- MS) in two different cohorts of MS patients, analyzing 42 distinct LM from the endogenous substrates AA, DHA and EPA based on published criteria for each LM (i.e. matching chromatographic retention times (RT), fragmen- tation patterns, and six characteristic and diagnostic ions).15,16 This analysis revealed a pronounced biosynthesis of 27 of these LM in the blood of healthy donors and MS
patients (Table 2), and the identification of key LM, including leukotriene B4 (LTB4), resolvin (Rv) D1, RvD5 and protectin D1 (Figure 1). Quantitation of LM was per- formed using signature ion pairs via multiple reaction monitoring (MRM) and revealed marked differences in several LM of each metabolome between MS patients and healthy subjects (Figure 2). In particular, total MS patients showed significantly higher blood levels of many AA- derived pro-inflammatory LM, such as prostaglandins (PG) PGE2, PGD2 (Figure 2A) and hydroxyeicosatetraenoic acids (HETE) 12-HETE and 15-HETE (Online Supplementary Figure S1A), as well as increases, although not significant, in leukotriene B4 and in AA-derived pro- resolving mediators lipoxins (LX)A4 and LXB4 (Figure 2A). Furthermore, as for LM derived from the DHA metabolome, we observed that MS patients displayed sig- nificantly higher levels of pathway markers 17-HDHA and 14-HDHA (Online Supplementary Figure S1B); howev- er, among the ten possible DHA-derived SPM (D-series resolvins, protectins and maresins), only four were detect- ed, e.g. RvD1, RvD5, PD1 and PDX, and these were all generally increased in MS patients, with PD1 and PDX
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