IDO2 and cardiac arrest: The crucial role of the kynurenine pathway on neuroinflammation has been previously reported as another pathophysiological mechanism of brain injury related to the activation of this pathway.32 In our study, we observed that indoleamine 2,3-dioxygenase deficiency mitigated neuroinflammation at 7 days after cardiac arrest, as represented by a consistent reduction of microglial activation in the white matter tract, in the cortex, in the hippocampus, and in the caudoputamen.