TTR and atrial fibrillation: Moreover, CTS + IL-1β stimulation of AF cells significantly increased the expression of the inhibitory complement receptor CD46, compared with the IL-1β–stimulated group (*p < 0.05), and of the inhibitor CD55, compared with the CTS group (*p < 0.05) and unstimulated cells (***p < 0.001; Figures 2C,D).