Session Type: Abstract Submissions (ACR)
Patients with systemic lupus erythematosus (SLE) are characterised by hyperactive T-cells that provide help to auto-reactive B-cells. Underlying this hyperactivity are alterations in the lipid and protein composition of membrane lipid microdomains (lipid rafts) that influence the nature, duration and outcome of immune synapse formation between T-cells and antigen presenting cells including B-cells. We examined the profile of lipid raft-associated glycosphingolipids (GSL) in T-cells, the mechanisms underlying their abnormal expression in patients with SLE and whether by normalising GSL expression, T-cell function could be restored in patients.
High performance liquid chromatography and flow cytometry were used to assess the GSL profile and phenotype of T-cells from 98 patients with SLE compared with 82 healthy controls and 23 patients with other autoimmune rheumatic disease. Western blotting, quantitative PCR and confocal microscopy using fluorescently-labelled GSLs were used to assess levels of proteins controlling GSL expression and GSL location within T-cells. T-cell function was assessed by measuring phosphorylation of proximal and downstream signalling molecules, proliferation and cytokine production.
The expression levels of lipid raft-associated GSL lactosylceramide (LC), Gb3 and GM1 were significantly increased in T-cells from patients with SLE compared to healthy and disease controls. In healthy donors LC+, GM1+ and Gb3+ T-cells had an activated phenotype, increased expression of proliferation marker Ki-67 and transcription factor RORgT, however, raised GSL expression was not associated with a specific T-cell phenotype in patients with SLE. Increased GSL expression in T-cells from SLE patients was not associated with altered levels of enzymes controlling GSL biosynthesis but was associated with increased GSL recycling from the plasma membrane to intracellular compartments. T-cells from patients with SLE incorporated fluorescently-labelled-LC into intracellular vesicles more rapidly compared to T-cells from healthy controls and this was accompanied by increased expression of the Niemann-Pick 1 and 2 genes that control GSL recycling. In vitro culture of T-cells from SLE patients with direct inhibitors of GSL biosynthesis normalised GSL membrane expression and restored their function in terms of lipid raft-associated T-cell signalling, proliferation and cytokine production.
We show that targeting lipid biosynthesis pathways using clinically approved inhibitors can rectify hyperactivity in autoimmune T-cells and restore their function.
D. A. Isenberg,
A. I. Magee,
E. C. Jury,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/targeting-glycosphingolipid-biosynthesis-normalises-t-lymphocyte-function-in-patients-with-systemic-lupus-eyrthematosus/