We therefore speculate on the therapeutic utility of Trp pathway metabolites in KD, but further biochemical experiments are needed to verify this assumption Notably, increased IDO activity in the serum has been observed in patients with advanced atherosclerosis, indicating that activated kynurenine pathway may play a pivotal role in the development of vascular diseases (Ji et al., 2020). The gene discussed is IDO1; the disease is atherosclerosis.