Mitochondrial proteomics reveals the impact of Estrogen in enhancing energy metabolism of patient-derived fibroblast-like synoviocytes in rheumatoid arthritis.

Mitochondrial dysfunction drives Rheumatoid Arthritis (RA) progression by disturbing energy metabolism and promoting inflammation. Additionally, the female predominance of RA highlights estrogen deficiency as an important contributor to disease development. The effect of estrogen in RA has been investigated; however, its specific effects on the mitochondrial proteome and function have yet to be studied. This study investigated the effects of 17-β estradiol (E2) on the mitochondrial proteome of patient-derived RA fibroblast-like synoviocytes (RA-FLS) using Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH-MS) analysis, followed by an assessment of key mitochondrial functional parameters and in vitro validation. The results identified an upregulated expression of two mitochondrial proteins, Acyl-CoA dehydrogenase very long chain (ACADVL) and ATP synthase subunit O (ATP5O), after E2 treatment in RA-FLS. This was further validated by increased real-time ATP production and reduced glycolytic capacity, along with increased expression of proteins related to fatty acid β-oxidation. In addition, E2 influenced mitochondrial dynamics by modulating the fission-fusion balance, resulting in improved mitochondrial morphology. E2 treatment also reduced the expression of mitophagy markers and increased mitochondrial membrane potential, indicating improved mitochondrial function. It also lowered mitochondria-centered oxidative stress by upregulating mitochondrial antioxidant enzymes. Mitochondrial proteomics analysis thus, demonstrated that E2 has the potential to enhance mitochondrial energy metabolism and alleviate mitochondrial dysfunction in RA. These findings provide a foundation for further exploration of mitochondria-targeted therapeutic approaches in RA management.