GFAP and COVID-19: Upregulation of astrocyte gene expression in glial fibrillary acidic protein (GFAP), thrombospondin 2 (Thbs2), leukemia inhibitory factor (Lif), and interleukin 6 (IL-6) by physical activity [275] deserve further studies to explore whether it helps in immune responses, such as those against COVID-19 [277].