Background/Purpose: Systemic lupus erythematosus (SLE) is a multisystem inflammatory condition of unknown pathogenesis. We have previously shown that SLE Natural killer (NK) cells are decreased in count and display a dysfunctional cytotoxicity. In addition, engagement of SLAMF7 with elotuzumab and CD38 with daratumumab restores the cytotoxic capacity of SLE NK cells. Furthermore, priming of SLE NK cells with daratumumab promotes the specific destruction of antibody-producing circulating plasma cells (cPC).

To deeper understand the alterations that characterize SLE NK cells and the contribution of CD38 and SLAMF7 in their dysfunction, we examined the cellular metabolism of SLE NK cell and how the ligation of daratumumab and elotuzumab influences the major metabolic pathways involved in NK cell activation.

Methods: Cryopreserved PBMC from SLE patients and healthy controls were thawed to isolate NK cells by positive selection. Immunometabolism was assessed using XFe96 Seahorse. Analysis of glycolysis was measured by extracellular acidification rate (ECAR) and oxidative phosphorylation by oxidative consumption rate (OCR), after stimulations with mentioned conditions.

Results: We analyzed the cellular metabolic alterations of SLE NK cells. We showed that SLE NK cellular glycolysis is unaltered compared to healthy NK cells, whereas oxidative phosphorylation is increased (Figure1). In addition, the engagement of CD38 with daratumumab and SLAMF7 with elotuzumab activated different metabolic pathways in healthy NK cells: daratumumab primarily enhanced NK cell glycolysis, while elotuzumab increased oxidative phosphorylation (Figure 2). In SLE patients, daratumumab increased NK cell cellular glycolysis and had no significant effect on oxidative phosphorylation, while elotuzumab showed no significant effect on glycolysis or oxidative phosphorylation (Figure 3).

Conclusion: SLE NK cells exhibit abnormally high oxidative phosphorylation, while cellular glycolysis is normal.

Additionally, daratumumab and elotuzumab both enhance the degranulation of SLE NK cells, but only SLE NK cells activated with daratumumab have the ability to kill cPC, thus limiting the production of autoantibodies. This difference is likely explained by the fact that the two antibodies activate NK cells by enhancing two different metabolic pathways. Daratumumab primarily promotes glycolysis, while elotuzumab mainly increases oxidative phosphorylation, which is already abnormally high in SLE NK cells and cannot be increased further.

Figure 1. Oxidative phosphorylaation is increased in SLE NK cells. Glycolytic metabolism measured as extracellular acidification rate (ECAR) upon addition of glucose (Gluc), oligomycin (Oligo) and 2-Deoxy-glucose (2-DG) in NK cells of HC (n=13) and SLE (n=7) shows no statistical difference (Welch’s T-test, points represent mean±SEM). Oxidative phosphorylation measured as oxygen consumption rate (OCR) upont addition of oligomycin (Oligo), FCCP, rotenone and antimycin-A (Rot/AA) in NK cells of HC (n=19) and SLE (n=9) shows a significatively higher basal respiration, ATP production and maximal respiration in SLE NK cells (Welch’s T test, p* < 0.003, **p < 0.002, ***p < 0.001).

Figure 2. Daratumumab primarily promotes glycolysis and elotuzumab oxidative phosphorylation of NK cells. Stimulation of healthy NK cells with daratumumab significantly promotes glycolysis and glycolytic capacity compared to unstimulated condition (n=5,One-way ANOVA). Stimulation of healthy NK cells with elotuzumab significantly increases the maximal respiration (n=5, One-way ANOVA, p* < 0.003, **p < 0.002, ***p < 0.001).

Figure 3. Daratumumab promotes glycolysis but elotuzumab has no effect on oxidative phosphorylation of SLE NK cells. Stimualtion of SLE NK cells with daratumumab significantly increases glycolysis and glycolytic capacity (n=7, Welch’s T test), similarly to what was observed on healthy cells. Stimualtion of SLE NK cells with elotuzumab, contrarily to what was observed in healthy cells, has no impact on the oxidative phosphorylation (n=9, Welch’s T test, p* < 0.003, **p < 0.002, ***p < 0.001).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/metabolic-alterations-of-systemic-lupus-erythematosus-nk-cells-determine-response-to-anti-cd38-and-anti-slamf7-monoclonal-antibodies/