Background/Purpose: Systemic lupus erythematosus (SLE) is characterised by innate immune activation and autoantibodies against nucleic self-antigens. The metabolic state of immune cells is emerging as a critical checkpoint of their effector functions, including proliferation, activation, secretion of cytokines, and escalation of inflammation. Previously described transcriptomic data suggested significant alterations in the metabolic profile of SLE immune cells, but there is lack of single-cell data confirming the changes at the protein level. The aim of this study was to create a detailed single-cell immunometabolic map in different stages of lupus disease activity and in ANA-positive individuals at risk of SLE.

Methods: Blood samples were obtained from patients from high disease activity SLE (n = 20), low disease activity SLE (n = 20), primary Sjogren’s Syndrome (n = 7), Rheumatoid Arthritis (n = 8), age- and sex-matched healthy donors (n = 20), and at-risk individuals before (n = 23) and after (n = 23) developing SLE. SLE patients met 2012 SLICC classification criteria and disease activity was evaluated using BILAG-2004. Cryopreserved human peripheral blood mononuclear cells (PBMCs) were thawed and subsequently stained with 50 distinct heavy metal-conjugated antibodies before they were processed by mass cytometry (CyTOF). Raw data were normalised using CyTOF software and were subsequently debarcoded using Premessa R package. Clustering, differential abundance, and differential expression was performed by using FlowSOM R package incorporating key clinical and immunological parameters in the data analysis.

Results: Principal analysis identified 36 distinct cellular components (B cell and T cell subsets, monocytes, NK cells, myeloid and plasmacytoid dendritic cells) and 6 key metabolic pathways (glycolysis, OxPHOS, PPP, TCA & ETC, fatty acid metabolism, amino acid metabolism). Cellular composition was significantly different among the patient groups with plasmablast expansion being a key element within the high disease activity SLE and the at-risk individuals who progressed to SLE. There were significant differences in the expression of the metabolic enzymes among different cellular components within the same individual; for instance, monocytes appeared more metabolically active compared to B cell populations. Patients with established autoimmune disease (e.g. SLE and primary Sjogren’s syndrome) were characterised by changes in several metabolic enzymes, mainly in glycolysis and OxPHOS pathways. These metabolic changes were correlated with differences in disease activity of SLE patients. Cellular and metabolic changes were observed in at-risk individuals highlighting an early immunometabolic reprogramming prior to the development of clinically overt autoimmune disease.

Conclusion: We identified immunometabolic changes at the single cell level, which can influence immune function, associated with disease activity in SLE and related diseases. Further, this immunometabolic reprogramming preceded clinically overt SLE or therapy suggesting a fundamental role in pathogenesis. Future analysis will explore the effect of these changes on longitudinal immune function and clinical status.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characterisation-of-immunometabolic-reprogramming-at-the-single-cell-level-in-patients-with-systemic-lupus-erythematosus-and-preclinical-autoimmunity/