Glucose metabolism pattern of peripheral blood immune cells in myasthenia gravis patients

Zhibin Li; Yuyao Peng; Yi Li; Ran Zhou; Di Chen; Wanlin Jin; Qiu Xu; Liqun Xu; Zhaohui Luo; Huan Yang

doi:10.21037/atm-20-918

Glucose metabolism pattern of peripheral blood immune cells in myasthenia gravis patients

Ann Transl Med. 2020 May;8(9):577. doi: 10.21037/atm-20-918.

Authors

Zhibin Li¹, Yuyao Peng¹, Yi Li¹, Ran Zhou¹, Di Chen¹, Wanlin Jin¹, Qiu Xu¹, Liqun Xu¹, Zhaohui Luo¹, Huan Yang¹

Affiliation

¹ Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, China.

Abstract

Background: We investigated the correlation between glucose metabolism patterns of different immune cells and the metabolic regulatory signaling pathways in myasthenia gravis (MG) and aimed to identify therapeutic targets for MG.

Methods: We isolated peripheral blood mononuclear cells (PBMCs) and sorted CD19⁺B cells, dendritic cells (DCs), CD4⁺ T cells, CD8⁺ T cells, CD4⁺CD25⁺ regulatory T cells (Tregs), CD4⁺CD25^-T cells, and T helper (Th) cells such as Th1, Th2, and Th17 cells. Then, we detected the expression levels of PI3K/AKT/mTOR-HIF-1α, GLUT1, hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK) by RT-PCR, measured the oxygen consumption rate and extracellular acidification rate of ex vivo freshly sorted cells using the Seahorse XF^e96 Analyzer. In addition, we compared the glycolysis levels using these cells from the same MG patients. By performing in vitro experiments, we measured, the mRNA expression levels of mTOR, HIF-1α, B cell activating factor receptor (BAFF-R), GLUT1, HK, PFK, and PK, in addition to ECAR profiles, frequency of CD80 and CD86, and IgG levels from the culture supernatant of B cells (isolated from MG patients) treated with rapamycin and PX-478 (selective mTOR and HIF-1α inhibitor, respectively) from.

Results: Except PBMCs, Th2 and CD8⁺ T cells, the expression levels of the key enzymes involved in glycolysis and HIF-1α were significantly higher in B cells, DCs, Tregs, CD4⁺CD25^-T cells, and Th1 and Th17 cells in MG patients, and the measurement of ECAR and OCR confirmed the metabolic status. In MG patients, B cells and DCs showed significantly higher levels of glycolysis and glycolytic capacity than CD8⁺ T cells, CD4⁺ T cells and its subsets. In vitro, except IgG levels, the increased glycolysis levels, expression of key glycolytic enzymes, BAFF-R and frequency of CD80 and CD86 of B cells, could be inhibited by rapamycin and PX-478.

Conclusions: Different subtypes of immune cells in MG exhibit different glucose metabolism patterns. The mTOR-HIF-1α signaling pathway might be the immunometabolism reprogramming checkpoint of glycolysis-dependent activated B cells in MG.

Keywords: HIF-1α; Myasthenia gravis (MG); glucose metabolism; immune cells; mTOR.