ScFv T1 Protects Against Mitochondrial Damage of SH-SY5Y Cells Caused by Extracellular Tau Aggregates

Mitochondria are essential organelles that perform irreplaceable functions in neurons. The degeneration of neurons in Alzheimer's disease (AD) is associated with mitochondrial damage, and Tau pathology represents a significant pathogenic factor in AD. However, the relationship between Tau and mitochondrial dysfunction during neuronal degeneration remains unclear. In this study, we investigated the effects and mechanisms by which extracellular Tau aggregates induce neuronal mitochondrial damage and dysfunction. The results showed that extracellular Tau aggregates lead to structural damage of mitochondria in SH-SY5Y cells and disrupt mitochondrial homeostasis. Extracellular Tau aggregates can also cause mitochondrial oxidative stress and inhibit Oxidative Phosphorylation in SH-SY5Y cells. Concurrently, extracellular Tau aggregates promote neuronal death through an increase in cytochrome C, mtDNA leakage and activation of the cGAS/STING pathway. We also explored the effects of a single-chain variable fragment antibody (scFv T1) and found that scFv T1 alleviated mitochondrial damage and dysfunction by inhibiting the formation of Tau aggregates. These findings suggest that targeting Tau pathology may be crucial to address neuronal mitochondrial impairment and that reduction of the toxicity associated with extracellular Tau aggregates could help slow Tau pathology progression.