Abstract
Background:
Rheumatoid arthritis (RA) is an aggressive, systemic autoimmune disease in which overactivated macrophages play a critical role in its pathogenesis. This study aimed to explore the potential role of glycolytic reprogramming in the production of proinflammatory cytokines by macrophages in RA.
Methods:
The Seahorse assay was conducted on RA or healthy control (HC) serum-treated human monocyte-derived macrophages (HMDMs) to evaluate glycolysis levels. RNA sequencing was performed to identify activated signaling pathways and key molecules in HMDMs stimulated by RA serum. The proinflammatory cytokines and hypoxia-inducible factor 1α (HIF-1α) were verified by Western blotting and quantitative polymerase chain reaction (qPCR).
Results:
We found that HMDMs stimulated with RA serum showed higher aerobic glycolysis levels than those treated with HC serum, along with higher expression of glycolysis-related genes, including hexokinase2 (HK2), pyruvate kinase L/R (PKLR), and phosphoglycerate kinase 1 (PGK1). Furthermore, RA serum-treated macrophages exhibited a higher level of interleukin-1 beta (IL-1β), and the expression of IL-1β positively correlated with HK2. Inhibition of glycolysis by 3-bromopyruvate (3BrPA) or HK2 knockdown significantly suppressed IL-1β production in macrophages. The HIF-1α-associated signaling pathways and HIF-1α protein levels were also elevated in RA serum-treated macrophages. Inhibition of glycolysis by 3BrPA or knockdown of HK2 reduced HIF-1α. Inhibiting HIF-1α can suppress IL-1β production of RA serum-treated macrophages, and vice versa. TNF-α and IL-1β enhanced HIF-1α and IL-1β expression in macrophages, an effect attenuated by glycolysis inhibition. Blocking TNF-α and IL-1β in RA serum diminished both glycolysis and IL-1β production.
Conclusion:
Our findings demonstrate that RA serum triggers aerobic glycolysis in macrophages, which promotes HIF-1α to drive IL-1β production. Notably, IL-1β within RA serum amplifies its own expression via this glycolysis-HIF-1α axis, establishing a pathogenic positive feedback loop in RA.
Keywords:
Glycolysis; HIF-1α; IL-1β; Macrophage; Rheumatoid arthritis.