ACE2 and Alzheimer disease: Since expression of human SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is limited in the neural central system, and TLR2 plays an important role in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, there is a hypothesis that TLR2 may play a critical role in the response to SARS-CoV-2 infiltration in the CNS, thus resulting in the induction or acceleration of AD and PD pathologies in patients [16].