Itaconic acid (methylene-
succinic acid, ItA) is an unsaturated dicarboxylic
acid that is secreted by mammalian macrophages in response to a pro-inflammatory stimulus and shows an anti-inflammatory/antibacterial effect. Being a mitochondrial metabolite, it exhibits an inhibitory activity on
succinate dehydrogenase and subsequently induces
mitochondrial dysfunction. The present study has shown that ItA dose-dependently inhibited
ADP- and DNP-stimulated (uncoupled) respiration of rat liver mitochondria energized with
succinate. This effect of ItA could be related to the suppression of the activity of complex II and the combined activity of complexes II + III of the respiratory chain. At the same time, ItA had no effect on the activity of the
dicarboxylate carrier, which catalyzes the transport of
succinate across the inner mitochondrial membrane. It was found that 4 mM ItA diminished the rates of
ADP- and DNP-stimulated mitochondrial respiration supported by the substrates of complex I
glutamate and
malate. A study of the effect of ItA on the activity of complexes of the respiratory chain showed that it decreases the activity of complex IV. It was observed that 4 mM ItA inhibited the rate of H2O2 production by mitochondria. At the same time, ItA promoted the opening of the
cyclosporin A-sensitive Ca2+-dependent permeability transition pore. The latter was revealed as the decrease in the
calcium retention capacity of mitochondria and the stimulation of release of
cytochrome c from the organelles. ItA by itself promoted the
cytochrome c release from mitochondria. Possible mechanisms of the effect of ItA on mitochondrial function are discussed.