SIRT3 deficiency reduces PFKFB3-driven T-cell glycolysis and promotes arthritic inflammation

Cell metabolism is an indispensable biochemical process that provides the basic energy and materials necessary for normal cell function. Accumulating evidence implicates abnormal metabolism of T cells as playing a critical role in the pathogenesis of rheumatoid arthritis (RA). The deacetylase SIRT3 has been shown to directly regulate energy metabolism in nonimmune cells. However, the role of SIRT3 in T cells and whether it participates in RA process remain unclear. In this study, we demonstrated that T-cell glycolysis was inhibited after SIRT3 deficiency. Compared to wild-type mice, SIRT3 knockout mice exhibited more severe arthritis, cartilage erosion, and inflammation after immunization with antigen-induced arthritis (AIA). It is interesting to note that SIRT3 deficiency reduced the expression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a regulatory and rate-limiting enzyme in glycolysis. Overexpression of PFKFB3 was shown to restore the impaired ATP production caused by SIRT3 deficiency in T cells, and protects T cells from apoptosis. In summary, SIRT3 plays an important role in the regulation of T-cell metabolism in the pathogenesis of RA. SIRT3 deficiency decreases glycolysis, reduces ATP production, induces apoptosis in CD4⁺ T cells, and further promotes AIA in mice.