Cunermuspir, a Copper(I)–Niacin Complex, Modulates Mitochondrial Respiration and Cellular Oxidant Handling in Fibroblasts from Children with Autism Spectrum Disorder

Copper is a redox-active transition metal that is essential for the assembly and catalytic function of cytochrome c oxidase (Complex IV), the terminal enzyme of the mitochondrial electron transport chain and a principal site of physiological oxygen reduction. Elevated Complex IV activity and respiratory chain uncoupling are among the most consistently replicated biological findings in autism spectrum disorder (ASD), yet the interaction between mitochondrial copper delivery, respiration, and cellular oxidant handling in ASD has not been systematically defined. We treated dermal fibroblasts from 9 children with ASD and 10 typically developing controls with the copper(I)–niacin complex Cunermuspir (0, 50, or 100 µM for 1 or 24 h exposure) and challenged them with graded concentrations (0–5.0 µM) of the redox-cycling agent 2,3-dimethoxy-1,4-naphthoquinone (DMNQ). Mitochondrial respiration was profiled by Seahorse XF respirometry (2133 observations across 28 experiments), and cellular reactive oxygen species (CellROX™ Green) and mitochondrial mass/polarization (MitoTracker™ Deep Red) were quantified by fluorescence imaging. ASD fibroblasts displayed a hypermetabolic, uncoupled respiratory phenotype (~73% higher baseline respiration; ~109% higher proton leak; reduced coupling efficiency). Linear mixed models with polynomial dose terms revealed significant ASD × Cunermuspir complex interactions (ASD × Cunermuspir and/or their higher-order interactions with DMNQ and treatment) for four respiratory parameters. ASD cells exhibited lower steady-state oxidation-dependent CellROX™ Green fluorescence than controls despite greater respiratory uncoupling, as well as lower steady-state MitoTracker™ Deep Red fluorescence; Cunermuspir reshaped the MitoTracker™ DMNQ dose–response in an ASD-selective manner. These findings identify the Cunermuspir-associated modulation of the ASD mitochondrial and oxidant handling phenotype and motivate further mechanistic and translational evaluation.