Figure 1.

Schematic diagram showing the proposed role of mast cells and microglia in the pathogenesis of neuro-COVID. A variety of triggers including toxins and viruses such as SARS-CoV-2 can reach the hypothalamus, mostly through the nose and olfactory nerve tract. There, they can disrupt the BBB via activation of perivascular mast cells, which then further increase BBB permeability and activate microglia. Proinflammatory molecules released from microglia can damage neurons, disrupt homeostasis, and contribute to the pathogenesis of neuro-COVID.