Fig. 1: A schematic showing the potential path followed by SARS-CoV-2 to cross the BBB.
From: Immune landscape and redox imbalance during neurological disorders in COVID-19
A typical BBB is composed of various cell types, majorly brain microvascular endothelial cells (BMECs), astrocytes, and pericytes. These cells crosstalk with other brain cells including neurons and microglia. During COVID-19, SARS-CoV-2 crosses the BBB, infecting the BMECs and following the transcellular pathway over the paracellular pathway, where the MMP9-dependent disruption of the basement membrane (BM) occurs. After gaining access to the brain by the SARS-CoV-2, neurons can be infected leading to their damage and mitochondrial dysfunction. This also involves the aggravated inflammatory response such as activation of microglia, and their polarization, followed by the production of inflammatory molecules production, which further promote the BBB damage and injury to neurons (Figure prepared with Biorender).
