TLR4 and atrial fibrillation: In a high-fat diet-induced AF model, MD1 knockdown promotes atrial remodeling in AF mice by activating the TLR4 signaling pathway, which modulates the expression of CaMKII, MyD88, and NF-κB, thereby affecting the expression of Kv4.2, Kv4.3, Kv1.5, Kv2.1, and Cav1.2 channel proteins, and regulates potassium-calcium channels (Shuai et al., 2019b; Shuai et al., 2019a).