P162 Dimethyl fumarate modulates T cell metabolism and function in systemic lupus erythematosus patient samples
Authors: Kell Loren , Shah Kavina , Taylor Samuel , De Maeyer Roel , Isenberg David A , Sen Debajit , Castelino Madhura , Leandro Maria , Akbar Arne , Reddy Venkat 
Published: April 2024

Abstract

Background/Aims
Activated CD4+T cells make a significant contribution to inflammation in systemic lupus erythematosus (SLE) through secretion of proinflammatory cytokines such as IFN-γ and TNF-α. CD4+T cells can also express activating NK receptors such as NKG2D that can engage with stress-induced ligands such as MICA, as noted in lupus nephritis, and mediate nonspecific tissue injury. We know that cellular metabolism regulates the activation of T cells. Evidence from patients with multiple sclerosis indicates that dimethyl fumarate (DMF), an electrophile, targets cellular metabolism to modulate CD4+T cell activation and function. Here, we investigated whether DMF modulates T cell metabolism and function in samples from patients with SLE in a series of in vitro experiments.

Methods
All experiments were performed using isolated T cells from freshly drawn whole blood samples from patients with SLE. T cells were isolated using negative selection using stem cell or Miltenyei magnetic bead separation kit. Isolated T cells were activated with anti-CD3 and IL-2 and incubated with either DMF at 25μM concentration or DMSO alone for three or seven days at 37 °C and 5% CO2 before harvesting.

Results
In Seahorse experiments, after three days of incubation, dimethyl fumarate (DMF) inhibited Figure A-i) the oxygen consumption rate (OCR) and A-ii) extra cellular acidification rate (ECAR) in isolated T cells when compared with samples incubated with vehicle, dimethyl sulfoxide (DMSO). Our results revealed that DMF significantly inhibited: 1) aerobic glycolysis and oxidative phosphorylation in activated T cells from patients with SLE (n = 4) (Figure A- i and ii) in vitro; 2) T cell activation and proliferation as assessed by a reduction in the frequency of CD69 (n = 4) and D) Ki67 (n = 2) positivity, respectively (Figure B-E); 3) Collectively, these results suggest that DMF inhibits T cell activation and proliferation in samples from patients with SLE. After 7 days of incubation, DMF significantly inhibited the expression of activating NK receptors CD158a and NKG2D on T cells whereas there was a trend toward enhancing the expression of inhibitory NK receptors NKG2A and CD158b (Figure F-I). After 7 days of incubation, DMF significantly reduced intracellular expression of IFN-γ, TNF-α, IL-17 and secretion of pro-inflammatory cytokines IFN-γ and TNF-α in supernatants (Figure J - N).

Conclusion
Our preliminary data indicated that, in SLE patient samples, DMF modulates metabolic programming of CD4+ T cells and inhibits glycolysis and oxidative phosphorylation of activated CD4+ T cells. In vitro, DMF inhibited: T cell activation; proliferation; the expression of activating NK receptors; and secretion of proinflammatory cytokines from T cells patients with SLE. Taken together with the existing safety data in humans, these data provide mechanistic rationale for investigating the potential of dimethyl fumarate, with a distinct mechanism of action, as a novel therapy for SLE.

Disclosure
L. Kell: None. K. Shah: None. S. Taylor: None. R. De Maeyer: None. D.A. Isenberg: None. D. Sen: None. M. Castelino: None. M. Leandro: None. A. Akbar: None. V. Reddy: Grants/research support; UCLH Biomedical research centre funded this work, Dr.Reddy's work was supported through MR/T024968/1 MRC-CARP Fellowship.