Quantification of cytokine secretion of AF cells (Fig. 1d, e) showed that the inhibition of miR-155-5p resulted in a significantly increased secretion of anti-inflammatory cytokine IL-10 (1.6 ± 0.1 relative fluorescent signal, p < 0.001), while miR-155-5p under IL-1β treatment let to a decrease of CCL5 (0.7 ± 0.1 relative fluorescent signal, p < 0.001) and to a recognizable though not significant increase of IL-8 (4.1 ± 2.8 relative fluorescent signal, p = 0.129) due to high donor-donor variability (Fig. 1f). Here, CXCL8 is linked to atrial fibrillation.