Background: CD4 ⁺ T cell resistance to apoptosis is closely related to the progression of systemic lupus erythematosus (SLE) [1, 2]. Abnormal T cell metabolism has been considered to be the core pathogenesis of SLE [3]. PFKFB3, a key enzyme in the glycolysis pathway that promotes lactate production [4–6], may be involved in this process, however, the underlying mechanism is still unclear.

Objectives: To investigate the effect of PFKFB3, a key enzyme in the glycolytic pathway, on the apoptosis of CD4+T cells in systemic lupus erythematosus (SLE), and to explore the key role of DNA damage repair protein Rad50 lactylation in this process.

Methods: Western blot were used to detect the expression levels of PFKFB3 in CD4 ⁺ T cells of SLE patients and Pristane lupus mice，and Global lactylome reveals important differential lactylation modification sites in CD4 ⁺ T cells of Pristane lupus mice. CD4+T cell-specific knockout PFKFB3 mice were constructed and Pristane lupus model was established. Lactylation was enhanced by intraperitoneal injection of Rotenone, and the apoptosis rate of CD4 ⁺ T cells was detected by flow cytometry. The expression levels of apoptosis-related proteins Bcl-2 and cleaved-caspase3 were detected by Western blot, and the level of Rad50 lactate modification was detected by co-immunoprecipitation (CO-IP) ，The levels of autoantibodies dsDNA and IgG in serum were detected by ELISA. The pathological changes of kidney were detected by HE and PAS staining.

Results: Compared with healthy volunteers, the expression of PFKFB3 in peripheral blood CD4 ⁺ T cells of SLE patients was significantly increased, while the apoptosis rate was decreased, the expression of Bcl-2 was increased, and the expression of cleaved-caspase3 was decreased. The results were consistent with those in lymph node CD4 ⁺ T cells of Pristane lupus mice. The lactacylation modification omics of CD4 ⁺ T cells showed that the lactacylation modification level of DNA damage repair protein Rad50 was the most significantly up-regulated, and CO-IP results suggested that the lactylation level of Rad50 [7, 8] was increased. Compared with the Pristane group, the apoptosis rate of CD4 ⁺ T cells in CD4 ^cre/- PFKFB3 ^fl/fl +Pristane group was increased, the expression of Bcl-2 was decreased, the expression of cleaved-caspase3 was increased, the level of Rad50 lactylation was decreased, the secretion levels of dsDNA and IgG were decreased, and the pathological damage of kidney structure was improved. However, the above results were reversed in CD4 ^cre/- PFKFB3 ^fl/fl +Pristane+lactylation enhancer group.

Conclusion: PFKFB3 promotes the apoptosis resistance of CD4 ⁺ T cells in SLE, and its mechanism may be closely related to the enhancement of Rad50 lactylation and the improvement of DNA damage repair ability.

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Acknowledgements: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.