Lactate controls glomerular endothelial barrier integrity in lupus nephritis
Jiaxin Lei, Xingyu Zhai, Yixin Wang, Ying Li, Lei Li, Mengdi Liu, Jing Guo, Lingyi Li, Zhezhuyun Chen, Qinghua Cao, Zhichun Liu, Ting Liu, Lin Xu, Zhenke Wen
Jiaxin Lei, Xingyu Zhai, Yixin Wang, Ying Li, Lei Li, Mengdi Liu, Jing Guo, Lingyi Li, Zhezhuyun Chen, Qinghua Cao, Zhichun Liu, Ting Liu, Lin Xu, Zhenke Wen
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Research Article Nephrology

Lactate controls glomerular endothelial barrier integrity in lupus nephritis

Abstract

Systemic lupus erythematosus (SLE) is a progressive autoimmune disease that affects multiple organs and tissues, with lupus nephritis (LN) as one of its most severe complications. Although LN progression is associated with compromised permeability of human renal glomerular endothelial cells (HRGECs), the underlying mechanisms are not fully defined. Herein, we demonstrate that aberrant glycolysis drives this glomerular endothelial barrier defect by suppressing the transcription of tight junction (TJ) genes. Mechanistically, circulating self-DNA in SLE plasma acts as a ligand that activates the cGAS/STING pathway in HRGECs, driving aberrant glycolytic adaption. The resulting glycolytic product, lactate, serves as a substrate for protein lactylation, leading to extensive lactylation and subsequent ubiquitination of enhancer of zeste homolog 2 (EZH2). In consequence, EZH2 deficiency results in reduced H3K27me3 levels, thereby suppressing the transcription of TJ genes. In a self-DNA–induced SLE model, inhibition of cGAS/STING signaling or lactate production effectively restored the integrity of TJs of HRGECs and concurrently alleviated key LN symptoms. Together, lactate programs lactylation and ubiquitination of EZH2 to impair the glomerular endothelial barrier in human SLE.

Authors

Jiaxin Lei, Xingyu Zhai, Yixin Wang, Ying Li, Lei Li, Mengdi Liu, Jing Guo, Lingyi Li, Zhezhuyun Chen, Qinghua Cao, Zhichun Liu, Ting Liu, Lin Xu, Zhenke Wen

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Figure 3

Abnormal glycolysis and subsequent lactate accumulation trigger EZH2 degradation, leading to diminished H3K27me3 abundance.

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Abnormal glycolysis and subsequent lactate accumulation trigger EZH2 deg...
(A) Western blot analysis of histone methylation levels in HRGECs after treatment with HC- or SLE-derived plasma (10% or 20%; 24 hours). Mean ± SEM (4–6 individuals/group). (B and C) ECs were treated with 10% SLE plasma together with 2‑DG (1 mM) or GSK2837808A (40 μM), with quantification of histone methylation levels via Western blot. Mean ± SEM (5–6 individuals/group). (D) Western blot analysis of H3K27me3 levels in HRGECs after 24 hours’ treatment with or without EED226 (50 nM). (E and F) qPCR (E) and Western blot (F) analyses of TJ-related protein expression in HRGECs after 24 hours’ treatment with or without EED226 (50 nM). Mean ± SEM (n = 4 per group). (G) ECs were treated for 24 hours with plasma from HCs or patients with SLE at 10% or 20% concentration. Protein levels of EZH1 and EZH2 were analyzed by Western blot. (H) Levels of H3K27me3 in ECs assessed by Western blot after EZH2 knockdown. (I) ECs were treated with 10% SLE plasma for 24 hours in the presence or absence of EZH2 overexpression. Levels of H3K27me3 were assessed by Western blot. (J and K) Western blot analysis of EZH2 protein levels in ECs treated with 10% SLE plasma for 24 hours in the presence or absence of 2‑DG (1 mM) or GSK2837808A (40 μM). (L) EZH2 protein levels in ECs exposed to lactate (40 mM) or lactic acid (10 mM) for 24 hours assessed by Western blot. (M and N) qPCR (M) and Western blot (N) analysis of TJ-related protein expression in ECs after EZH2 knockdown. Mean ± SEM (4 independent experiments/group) (M). (O and P) TJ-related protein expression analyzed by qPCR (O) and Western blot (P) in ECs upon treatment with 10% SLE plasma with or without EZH2 overexpression. Mean ± SEM, 5 individuals (O). (Q and R) qPCR (Q) and Western blot (R) analysis of TJ-related protein expression in ECs after lactic acid treatment (10 mM) with or without EZH2 overexpression. Mean ± SEM, 5 independent experiments (Q). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 with 2‑tailed paired t test (B and C) and 1‑way (A) and 2‑way ANOVA plus Tukey’s method (E, M, O, and Q).