POS1390 SINGLE-CELL PROFILING IDENTIFIES PERIPHERAL IMMUNE SIGNATURE OF CORONARY ARTERY DISEASE IN SLE PATIENTS
Authors: C. LI, L. Osmani, J. Gu, H. Zhao, I. Kang, R. Bucala, X. Dong
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Coronary artery disease (CAD) is one of the leading causes of morbidity and mortality in patients with Systemic Lupus Erythematosus (SLE). In contrast to CAD in the general population, SLE patients with CAD are primarily females of child-bearing age. After adjusting for traditional risk factors, cardiovascular events are still 3-10 times more common in SLE than in non-SLE subjects. Studies have shown that monocytes, T cells, and NK cells are associated with cardiovascular events and mediate the progression of atherogenesis. The pathogenesis and the roles of the immune cells in SLE patients with CAD currently remain unknown. <h3>Objectives:</h3> To compare the peripheral immune cell profiles in SLE patients with and without CAD for the purpose of biomarker and potential therapeutic target discovery. <h3>Methods:</h3> Using single-cell RNA sequencing (scRNA-seq), we profiled 68,494 peripheral blood mononuclear cells (PBMC) from four SLE patients with and without CAD. The data were analyzed using Seurat pipelines. We identified differentially expressed genes (|log2(fold change) |&gt;0.5, p adj&lt;0.05) using the R-based DESeq2 package. <h3>Results:</h3> Clustering and annotation of PBMCs revealed 7 cell populations based on distinct marker genes (Figure 1a and b): monocytes, T cells, NK cells, B cells, dendritic cells, low-density neutrophils (LDN), and platelets. Examination of myeloid cell populations revealed a significant increase in the percentage of NK cells (Figure 1c) (10.6% vs. 6.3%, p&lt;0.05) and CD14<sup>+</sup>CD16<sup>+</sup> intermediate monocytes (Figure 1d) (53.7% vs. 8.3%, p&lt;0.05) in SLE with CAD. We also observe a fourfold increase in LDN (Figure 1c) (0.04% vs. 0.01%, p&lt;0.05), a pro-inflammatory cell subset associated with neutrophil extracellular trap (NETs) formation and Type I interferon production, in SLE with CAD. The most striking difference among lymphoid cell populations was the expansion of cytotoxic CD8 T cells (Figure 1e) (23.0% vs. 9.2%, p&lt;0.05). Differential gene expression analysis was notable for markedly increased expression of chemokine receptors including <i>CXCR1/2</i> (p adj&lt;0.05) and <i>CX3CR1</i> (p adj&lt;0.05) in intermediate monocytes, NK cells, and cytotoxic CD8 T cells (Figure 1f-h). While in lymphoid subpopulations in SLE with CAD, we found significant upregulation of cytotoxic effector genes including <i>GZMB</i> and <i>PRF1</i>, and multiple Type I interferon-stimulated genes including <i>IFI27</i> and <i>IFI44L</i> (Figure 1i) (p adj&lt;0.05). <h3>Conclusion:</h3> Analysis of our scRNA-seq data revealed the significant difference in immune cell composition and differentially expressed genes between SLE with and without CAD. In SLE patients with CAD, we found marked expansion of intermediate monocytes, NK, LDN and cytotoxic CD8 T cells with increased expression of the chemokine receptor genes <i>CXCR1/2</i> and <i>CX3CR1</i>; the latter are known for their roles in recruiting cytotoxic immune cells in atherosclerotic lesions and promoting the progression of atherosclerotic plaque. In contrast to the pathogenesis of interleukin-1 in CAD in general population, our transcriptomic findings suggest that Type I interferon signals play a key role in contributing to cardiovascular inflammation. The chemokine receptors CXCR1/2 and CX3CR1, and Type I interferon may serve as biomarkers and potential therapeutic targets to decrease cardiovascular risk in SLE. <h3>REFERENCES:</h3> [1] Ajeganova S, Hafström I, Frostegård J. Patients with SLE have higher risk of cardiovascular events and mortality in comparison with controls with the same levels of traditional risk factors and intima-media measures, which is related to accumulated disease damage and antiphospholipid syndrome: a case-control study over 10 years. Lupus Sci Med. 2021 Feb;8(1):e000454. [2] Yen EY, Singh RR. Brief Report: Lupus-An Unrecognized Leading Cause of Death in Young Females: A Population-Based Study Using Nationwide Death Certificates, 2000-2015. Arthritis Rheumatol. 2018 Aug;70(8):1251-1255. [3] Fernandez, D.M., Rahman, A.H., Fernandez, N.F. <i>et al.</i> Single-cell immune landscape of human atherosclerotic plaques. <i>Nat Med</i><b>25</b>, 1576–1588 (2019). <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>