Screening of Phospholipids in Plasma of Large-Artery Atherosclerotic and Cardioembolic Stroke Patients With Hydrophilic Interaction Chromatography-Mass Spectrometry

Impaired membrane lipids in ischemic stroke: a key player in inflammation and thrombosis

BACKGROUND

Membrane lipids play a crucial role in brain function and cell signalling, and they serve as key biological substrates in inflammatory responses, thrombosis, and energy metabolism. Multiple clinical and molecular evidences suggest that membrane lipids are probably involved in the pathogenesis of ischemic stroke (IS). However, current knowledge about the membrane lipid landscape and its involvement in IS pathophysiology is limited.

METHODS

We performed untargeted lipidomic analysis on erythrocyte membranes from 56 IS patients and 55 healthy controls. Integrated with gene expression and weighted gene co-expression network analysis, we identified dysregulated lipid signalling pathways and their contributions to IS pathophysiology.

RESULTS

A total of 1392 erythrocyte membrane lipids were detected and quantified. Our results revealed significant impairment of membrane lipid homeostasis in IS patients, characterized by a marked reduction in glycerophospholipids (GPLs) and lysophospholipids (LPLs). Further analysis indicated that the impaired lipids were primarily concentrated in three disturbed signalling pathways, including the phospholipase A2-mediated GPL-LPL pathway, the phospholipase C-mediated inositol 1,4,5-trisphosphate/diglyceride pathway, and the sphingosine-1-phosphate (S1P)-S1P receptors pathway. Gene expression results indicated that these pathways were inhibited during the subacute phase of IS. Furthermore, these lipid signalling pathways form a highly interconnected network that collaboratively contributes to inflammation and thrombosis in IS, thereby influencing the progression and prognosis of the disease.

CONCLUSION

Our findings reveal impaired erythrocyte membrane lipid homeostasis in IS, which implicates inflammatory processes and thrombosis in IS. This research offers new insights into the role of membrane lipids in IS pathogenesis, potentially informing future monitoring and therapeutic strategies.

Elucidating stroke etiology through lipidomics of thrombi and plasma in acute ischemic stroke patients undergoing endovascular thrombectomy

Acute ischemic stroke (AIS) requires detailed etiology information to guide optimal management. Given the pivotal role of lipids in AIS, we conducted a comprehensive lipidomics analysis of paired thrombi and plasma from AIS patients, correlating the findings with stroke etiology. Patients were recruited across four etiologies: cardioembolism (CE), large artery atherosclerosis (LAA), active cancer (Cancer), and undetermined. Plasma and thrombi were collected before and during endovascular thrombectomy and analyzed using in-house targeted lipidomics. Among 51 patients (37 CE, 7 LAA, 4 Cancer, and 3 undetermined), we identified 37 and 70 lipid species significantly different between thrombi in CE and LAA, and CE and Cancer, respectively (FDR-corrected P < 0.05). No significant differences were observed in plasma. Notably, 21 diacylglycerols and 11 polyunsaturated triacylglycerols were depleted (2.5 to 12 folds) in LAA compared to CE, while 10 ceramides and 57 glycerophospholipids were elevated in Cancer. With 80% validation accuracy, 29 and 59 lipids distinguished LAA and Cancer from CE, respectively. A neural network model using these lipids effectively classified undetermined patients. This study emphasizes the significance of thrombus lipids in distinguishing between LAA, CE, and Cancer etiologies in AIS, enhancing our understanding of stroke pathophysiology and informing future clinical managements.

Assessing the causal effect of genetically predicted metabolites and metabolic pathways on stroke

BACKGROUND

Stroke is a common neurological disorder that disproportionately affects middle-aged and elderly individuals, leading to significant disability and mortality. Recently, human blood metabolites have been discovered to be useful in unraveling the underlying biological mechanisms of neurological disorders. Therefore, we aimed to evaluate the causal relationship between human blood metabolites and susceptibility to stroke.

METHODS

Summary data from genome-wide association studies (GWASs) of serum metabolites and stroke and its subtypes were obtained separately. A total of 486 serum metabolites were used as the exposure. Simultaneously, 11 different stroke phenotypes were set as the outcomes, including any stroke (AS), any ischemic stroke (AIS), large artery stroke (LAS), cardioembolic stroke (CES), small vessel stroke (SVS), lacunar stroke (LS), white matter hyperintensities (WMH), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), transient ischemic attack (TIA), and brain microbleeds (BMB). A two-sample Mendelian randomization (MR) study was conducted to investigate the causal effects of serum metabolites on stroke and its subtypes. The inverse variance-weighted MR analyses were conducted as causal estimates, accompanied by a series of sensitivity analyses to evaluate the robustness of the results. Furthermore, a reverse MR analysis was conducted to assess the potential for reverse causation. Additionally, metabolic pathway analysis was performed using the web-based MetOrigin.

RESULTS

After correcting for the false discovery rate (FDR), MR analysis results revealed remarkable causative associations with 25 metabolites. Further sensitivity analyses confirmed that only four causative associations involving three specific metabolites passed all sensitivity tests, namely ADpSGEGDFXAEGGGVR* for AS (OR: 1.599, 95% CI 1.283-1.993, p = 2.92 × 10-5) and AIS (OR: 1.776, 95% CI 1.380-2.285, p = 8.05 × 10-6), 1-linoleoylglycerophosph-oethanolamine* for LAS (OR: 0.198, 95% CI 0.091-0.428, p = 3.92 × 10-5), and gamma-glutamylmethionine* for SAH (OR: 3.251, 95% CI 1.876-5.635, p = 2.66 × 10-5), thereby demonstrating a high degree of stability. Moreover, eight causative associations involving seven other metabolites passed both sensitivity tests and were considered robust. The association result of one metabolite (glutamate for LAS) was considered non-robust. As for the remaining metabolites, we speculate that they may potentially possess underlying causal relationships. Notably, no common metabolites emerged from the reverse MR analysis. Moreover, after FDR correction, metabolic pathway analysis identified 40 significant pathways across 11 stroke phenotypes.

CONCLUSIONS

The identified metabolites and their associated metabolic pathways are promising circulating metabolic biomarkers, holding potential for their application in stroke screening and preventive strategies within clinical settings.

Lipidomic Approaches in Common and Rare Cerebrovascular Diseases: The Discovery of Unconventional Lipids as Novel Biomarkers

Stroke remains a major cause of death and disability worldwide. Identifying new circulating biomarkers able to distinguish and monitor common and rare cerebrovascular diseases that lead to stroke is of great importance. Biomarkers provide complementary information that may improve diagnosis, prognosis and prediction of progression as well. Furthermore, biomarkers can contribute to filling the gap in knowledge concerning the underlying disease mechanisms by pointing out novel potential therapeutic targets for personalized medicine. If many "conventional" lipid biomarkers are already known to exert a relevant role in cerebrovascular diseases, the aim of our study is to review novel "unconventional" lipid biomarkers that have been recently identified in common and rare cerebrovascular disorders using novel, cutting-edge lipidomic approaches.