Background: Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by antiphospholipid antibodies and a hypercoagulable state, leading to arterial, venous, or microvascular thrombosis, accelerated atherosclerosis and obstetric morbidity. Due to the heterogeneity of the disease, the limited effective responses and the risk of recurrences, it is crucial to develop new approaches that enable more personalized management and precise monitoring to optimize therapeutic interventions.

Objectives: 1 ) To thoroughly characterize the complete lipidomic profile present in the serum of APS patients and analyse its association with the disease´s physiopathology.

2 ) To assess in vitro the impact of circulating lipidomic alterations on macrophages, key cells involved in the pathophysiology.

3 ) To investigate the short-term effects of in vivo ubiquinol supplementation (reduced coenzyme Q10) on these processes.

Methods: A total of 129 primary APS patients and 43 healthy donors (HD) underwent clinical and molecular characterization. Serum lipidomic profiles were assessed using nuclear magnetic resonance (NMR) metabolomics (>250 metabolites, Nightingale) analysis, covering glycolysis metabolites, amino acids and 130 lipid measures. Unsupervised clustering analysis was conducted to identify patient subgroups based on their lipid profiles and their contribution to atherothrombotic risk. Serum levels of 92 cardiovascular-related proteins were evaluated using proximity extension immunoassay (PEA-Olink, Cobiomic). Furthermore, the lipid profile of 15 APS patients receiving adjuvant Ubiquinol treatment for one month was evaluated. In vitro studies exposed macrophages from HD to serum from identified APS patient subgroups to assess the modulation of cell activation and lipid metabolism.

Results: APS patients exhibited significant alterations in 53 metabolites compared to HD, including reduced levels of atheroprotective lipids such as HDL, sphingomyelins, and phospholipids, as well as increased levels of pro-atherogenic mediators like VLDL and LDL. Unsupervised clustering analysis identified two patient subgroups. At molecular level, 143 deregulated metabolites were revealed between clusters: in cluster 2 (C2), as compared to cluster 1 (C1), higher levels of VLDL and LDL, triglycerides, fatty acids, metabolites related to glycolysis and inflammation, and other lipids involved in immune cell activity were identified. Furthermore, proteomic analysis identified specific proteins associated with increased cardiovascular risk in these clusters.

At the clinical level, C2 patients had a higher prevalence of arterial thrombosis, an elevated thrombotic risk score (aGAPSS over 9), and more cardiovascular risk factors such as atheroma plaques, dyslipidemia, and hypertension.

In vivo, ubiquinol treatment partially reversed the altered lipidomic profile in APS patients, reducing pro-atherogenic lipoproteins and increasing anti-atherogenic lipoproteins. In vitro, exposure of macrophages to serum from patients with increased cardiovascular risk (C2) promoted a more pro-atherogenic phenotype, characterized by their transformation into foam cells and increased expression of macrophage activation markers and regulators of lipid metabolism.

Conclusion: 1. APS patients exhibit an altered lipidomic profile compared to HD, marked by an increase in pro-atherogenic mediators and a decrease in atheroprotective ones, correlating with the disorder´s pathogenesis.

2. For the first time, we have categorised two patient subgroups based on their lipidomic and proteomic profiles, along with thrombotic risk, all linked to distinctive clinical features.

3. Ubiquinol supplementation restores disrupted circulating lipidomic profile in APS patients, supporting its atheroprotective role.

4. In vitro assays elucidate the impact of the altered circulating lipidomic profile on key immune cells in APS, particularly macrophages, enhancing their pro-atherogenic phenotype.

REFERENCES: NIL.

Acknowledgements: EU/EFPIA Innovative Medicines Initiative Joint Undertaking 3TR, Projects no. PI21/0591 & CD21/00187 funded by Instituto de Salud Carlos III (ISCIII) and co-funded by the European Union. Project no. RD21/0002/0033 funded by ISCIII and funded by the European Union-NextGeneration EU, via Plan de Recuperación, Transformacion y Resiliencia (PRTR) and MINECO (RYC2021-033828-I, and PID2022-141500OA-I00).

Disclosure of Interests: None declared.