PDGFRB and COVID-19: Signaling pathway analysis in COVID-19 brain tissues showed that PDGFR-β, EGF/EGFR and VEGF pathways were upregulated, while Wnt and hedgehog signaling pathways were downregulated (Fig. 2g), resulting in the abnormality in BBB-associated molecules (Fig. 2h) which physically maintain BBB integrity and function by forming adhesion junctions, solute carriers, tight junctions, efflux pumps, material transport and vesicle-mediated transport.36,37 Thus, our results reveal protein profiles associated with BBB pathogenesis, which might exacerbate COVID-19-associated encephalitis.