Expression and mutation characteristics of mitochondrial genes in PBMCs of SLE patients: Implications for SLE pathogenesis

This study aimed to investigate mitochondrial gene mutations and expression in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients, focusing on MT-ND5, and assess expression changes under lipopolysaccharide (LPS), tumor necrosis factor-α (TNF-α), and dexamethasone stimulation. Peripheral blood was collected from female SLE patients. Mitochondrial DNA (mtDNA) from PBMCs was sequenced using the HiSeq PE150 platform. Quantitative reverse transcription PCR and western blotting were used to evaluate mRNA and protein expression of the most frequently mutated mitochondrial genes. Cultured PBMCs were treated with LPS, TNF-α, or dexamethasone to examine regulatory effects. A total of 589 mtDNA mutation sites were detected in SLE patients. Among 13 protein-coding genes, MT-ND5, MT-CYB, MT-CO1, MT-ND4, and MT-CO3 exhibited the highest mutation frequencies. Expression analysis revealed significantly reduced mRNA and protein levels of these genes in SLE PBMCs compared with controls, with further decreases after stimulation with LPS, TNF-α, or dexamethasone. SLE PBMCs display extensive mitochondrial mutations and downregulation of key genes, particularly MT-ND5. Inflammatory and therapeutic stimuli exacerbate this suppression, suggesting mitochondrial dysfunction contributes to SLE susceptibility and progression.