Many people with COVID-19 experience brain-related symptoms like confusion, headaches, and difficulty thinking clearly. These problems can continue for months after infection as part of Long COVID. Scientists are working to understand why the virus affects the brain, even though it mainly attacks the lungs, heart, and intestines.
Researchers studied how SARS-CoV-2 affects the cells that line tiny blood vessels in the brain. These cells form a protective barrier between blood and brain tissue. The team exposed human brain blood vessel cells and African monkey kidney blood vessel cells to live SARS-CoV-2 virus in laboratory experiments. They wanted to see how the virus infects cells and get through the protective barrier into brain tissue. The researchers measured how the cells responded by looking at inflammation markers, changes in the structure of the protective barriers, and changes in the cells’ energy-producing structures called mitochondria, which help maintain the protective brain barrier.
The study found that exposure to SARS-CoV-2 triggered strong inflammation in brain blood vessel cells. The virus activated a specific inflammation pathway called NF-κB that isn't usually turned on in these cells. This led to increased production of inflammatory substances that could alter brain tissue. The researchers also discovered that the virus changed how mitochondria work in these cells. Mitochondria became longer and more connected to each other, which can happen when cells are under stress. These changes occurred even though the virus didn't directly infect or kill the brain blood vessel cells.
These findings help explain how COVID-19 might cause brain symptoms without the virus directly infecting brain cells. The inflammation and changes in mitochondria could disrupt the cellular structure of the protective barrier between blood and brain. This disruption might allow harmful substances to enter brain tissue and cause thinking and memory problems seen in people with COVID. Understanding these mechanisms is an important step toward developing treatments for the neurological symptoms of COVID.