Tipping the balance: innate and adaptive immunity in mitochondrial disease.

Mitochondrial diseases (MtD) provide a unique window into the complex interplay between metabolism and immune function. These rare disorders, caused by defects in oxidative phosphorylation, result in bioenergetic deficiencies that disrupt multiple organ systems. While traditionally studied for their metabolic impact, MtD also profoundly affect the immune system, altering both innate and adaptive responses. This review explores how mitochondrial dysfunction shapes immune dysregulation, influencing thymocyte maturation, regulatory T cells, and B cell function while also driving innate immune activation through mitochondrial DNA instability and type I interferon signaling. Additionally, MtD highlight an emerging overlap between inborn errors of metabolism and inborn errors of immunity, revealing shared pathways that connect mitochondrial dysfunction to immune deficiencies and inflammatory disease. Studying MtD not only advances our understanding of immunometabolism but also provides critical insights into more common inflammatory and autoimmune conditions, offering potential therapeutic targets that extend beyond rare mitochondrial disorders.