IDO1 and atrial fibrillation: More interestingly, while the expression of the characteristic DC surface markers largely remained comparable in all three groups (Figure S1A), the expression of all three representative genes tested, namely Aldh1a2, Indoleamine-pyrrole 2,3-dioxygenase 1 (Ido1) and Transforming growth factor beta 1 (Tgfb1) that are functionally implicated in tolerogenic phenotype of CD103+CD11b+ DCs, were dramatically reduced in AF mice (Figure 1D).