BackgroundSystemic lupus erythematosus (SLE), a chronic, inflammatory autoimmune disease, predominantly affects women with a 9:1 female:male incidence. Cardiovascular disease (CVD) is a leading cause of mortality in SLE via accelerated atherosclerosis: the build-up of cells and lipids in the vascular wall and the main pathology underlying CVD.ObjectivesTo define molecular profiles of SLE with subclinical atherosclerosis using multi-omics data analysis and clinical data in a well-characterised cohort of CVD-free SLE women.MethodsMulti-omics analyses were conducted to explore the molecular signatures of SLE patients with (SLE-P) and without (SLE-NP) subclinical atherosclerosis defined by non-invasive ultrasound scanning of the carotid and femoral arteries. SLE blood CD14+ monocyte transcriptomes were investigated by bulk RNA-sequencing (SLE-P N=13, SLE-NP N=8), and targeted serum cardiometabolic and cardiovascular proteomics (OLINK) were used to explore matched protein expression (SLE-P N=17, SLE-NP N=20) (no difference in disease activity between groups). Bioinformatics approaches, including pathway and disease module enrichment analyses and extended protein-protein interaction networks, further defined molecular profiles of SLE patients with atherosclerosis from patients that remained plaque free. Gene signature-derived interferon (IFN) scores were applied to investigate heterogeneous subgroups within the cohort as a measure of inflammation.ResultsDistinct monocyte gene and protein expression profiles were identified in SLE and enriched in biological pathways relating to extracellular mechanisms, including purinergic and cytokine signalling. Lipid regulatory mechanisms were enriched in SLE-P, whereas SLE-NP patient’s transcriptome and proteome profiles were defined by pathways relating to inflammation. Specifically, the type-I IFN pathway was exclusively reduced in SLE-P compared to SLE-NP. IFN scores derived from published IFN-responsive gene expression signatures stratified patients into significantly distinct subgroups (high versus low IFN-response, p=0.0001) with 66% (N=14) of patients showing high IFN expression across multiple signatures not associated with age, ethnicity, or disease activity. However, IFN scores did not predict the presence of sub-clinical atherosclerosis and further heterogeneity was revealed with 46% of SLE-P patients showing a low IFN response (N=6). Further, a measure of plaque lipid content (echogenicity) was inversely correlated with IFN score (grey scale median, p=0.03, r=-0.8) which may reflect distinct plaque phenotypes between these subgroups relating to clinical presentation and risk of cardiovascular events.ConclusionLipid dysregulation is a key mechanism that drives atherosclerosis pathology and genes and proteins relating to lipid metabolism distinguished SLE patients with and without subclinical atherosclerosis. Differences in levels of interferons and other inflammatory molecules may contribute to unique patterns of gene expression between SLE patients. A distinct subset of SLE-P patients showed low interferon expression, which may be suggestive of a dampened immune response in early subclinical CVD. Further elucidating the complexity of lipid dysregulation, inflammation and immune function in atherosclerosis in SLE will help improve patient stratification towards investigating the efficacy of anti-atherosclerotic therapies.Disclosure of InterestsNone declared

BackgroundCardiovascular disease (CVD) is a leading cause of mortality in patients with systemic lupus erythematosus (SLE, female:male ratio of 9:1) through accelerated atherosclerosis, the build-up of lipids and inflammation in the major artery walls, compared to age and sex matched healthy individuals. This is due to chronic inflammation, dyslipidaemia and other cardiometabolic defects that exacerbate with age (1). SLE in women aged of 35-44 increases the risk of coronary artery disease by 50 times and there is a 100-300-fold increased CVD-related mortality risk in young patients that develop SLE before the age of 18. Investigating metabolic defects in young patients and how they progress with age could help us understand the progressive mechanisms of atherosclerosis in SLE.ObjectivesThis study investigated detailed changes in the metabolomic profile of female patients with SLE and matched healthy controls across age.MethodsSerum NMR metabolomics (>250 metabolites, Nightingale) covering glycolysis metabolites, amino acids and 130 lipid measures was performed on serum from a cohort of female SLE patients (n=164, 13-72 years of age, median 35) and matched healthy controls (HCs, n=120, 15-76 years of age, median 36) and analysed by linear regression and Venn analysis. Multiple t-tests (corrected for multiple comparisons by false discovery rate) were used to assess unique metabolic changes by age group between SLE patients and HCs (≤25, n=62/43; 26-49, n=50/46; ≥50, n=52/31) and dysregulated metabolic pathways were assessed using metaboanalyst software. The metabolic impact of disease activity measures and treatments was assessed by Spearman correlations and unpaired t-tests respectively.ResultsTwenty-five metabolites were significantly altered in all SLE age groups compared to HCs, dominated by atheroprotective high density lipoprotein (HDL) subsets and their surface-bound peptide, apolipoprotein(Apo)A1, all of which were significantly decreased in SLE compared to HCs (p<0.0001 in ages combined). In addition, the concentration of glycoprotein acetyls (GlycA, inflammatory biomarker) was increased in SLE in all age groups compared to HCs (p<0.0001 in ages combined). Importantly, ApoA1 correlated negatively with disease activity measures (SLEDAI, p=0.005; BILAG, p=0.0009; dsDNA, p=0.003; ESR, p=0.0006) and positively with lymphocyte count (p=0.0005), whilst GlycA correlated positively with ESR (p<0.0001) and CRP (p<0.0001). Alternatively, metabolites unique to specific age groups in SLE compared to HCs included reduced amino acid subsets in the ≤25 age group, increased atherogenic very low density lipoproteins and reduced polyunsaturated fatty acids in the 26-49 age group, and increased atherogenic low density lipoproteins in the ≥50 age group.Separately, metabolites associated with the glycolysis pathway (p=0.004, metaboanalyist), including acetone, citrate, creatinine, glycerol, lactate and pyruvate, had significant positive correlations with age in SLE patients, but not in HCs. These metabolites were not significantly associated with disease activity measures. However, pyruvate (p=0.01) and lactate (p=0.009) were significantly upregulated in prednisolone treated patients, whilst citrate (p=0.002) and creatinine (p= 0.005) were downregulated in hydroxychloroquine treated patients.ConclusionIncreasing HDL (ApoA1) levels whilst maintaining low disease activity in patients with SLE from a young age could improve cardiometabolic risk outcomes. This could be achieved through improved nutrition, lipid targeted therapies and better treatment strategies. Focusing on understanding and monitoring biomarkers of the glycolytic pathway could aid treatment decisions and help avoid adverse metabolic effects of current anti-inflammatory therapies in SLE (1).References[1]Robinson G.A, Pineda-Torra I, Ciurtin C, Jury E.C. Lipid metabolism in autoimmune rheumatic disease: implications for modern and conventional therapies. J Clin Invest. 2022;132(2):e148552. https://doi.org/10.1172/JCI148552.AcknowledgementsThe authors would like to thank all of the patients and healthy blood donors, as well as Prof. Arne Akbar and Dr. Chris Wincup for additional patient and healthy donor samples.Disclosure of InterestsNone declared.