LDN down-regulation of LPS induced ERK1/2 phosphorylation.
ERK1 and ERK2 mitogen-activated protein kinases (MAPK) play a critical role in the regulation of cell proliferation and differentiation in response to mitogens and other extracellular stimuli. Mitogens and cytokines that activate MAPK in cells have been shown to activate virus replication8. The cytokine storm is a well-known factor that is increasing the severity and mortality in COVID195–7. Moreover, the phosphorylation status of ERK1/2 is positively correlated with virus load and reduced ERK1/2 phosphorylation suppressed viral replication significantly, thus reduced viral load8. We pre-treated the cells with LDN and exposed to LPS for 18 hours. As shown in Fig.1D . the phosphorylation of ERK 1/2 was increased after LPS exposure which was significantly suppressed by LDN treatment (Fig 1D ). This finding suggests that LDN can acts as an inhibitor for ERK1/2 activation and may reduce the infectivity of virions.