PCSK9 and hyperlipidemia: In addition to proinflammatory cytokines, high-fat diet (HFD)-induced hyperlipidemia also enhances PCSK9 expression potentially by modulating Toll-like receptor (TLR) 4 and its downstream signaling factors myeloid differentiation primary response gene 88 (MyD88) and nuclear factor kappa-B (NF-κB) (Liu et al., 2020).