TNF and COVID-19: Triggering PRR signalling within cells involved in the innate immune responses elevates the levels of pro-inflammatory factors, including tumour necrosis factor (TNF)-α and granulocyte macrophage-colony stimulating factor (GM-CSF) in the plasma of COVID-19 patients as well as interleukin (IL)-1β, IL-6, and IL-8, in their BALF and plasma [56–59].