SARS-CoV-2 cannot spread easily between brain cells, but does cause increased inflammation levels
The coronavirus SARS-CoV-2 can infect brain cells. However, the transmission of the virus between cells quickly stops, limiting the damage. Nevertheless, the SARS-CoV-2 infection does lead to an inflammatory reaction that may contribute to the neurological and psychological complaints that many (ex) patients have. This is apparent from research by Erasmus MC that has been published in mSphere.
During the corona pandemic, current and former patients worldwide are reporting neurological and psychiatric complaints. These range from memory problems or headaches to rare psychoses and encephalitis (inflammation of the brain tissue). In addition, there are strong indications that SARS-CoV-2 can enter the central nervous system via the olfactory nerve. The researchers therefore wanted to know what happens once the virus has reached the brain. But also which cells it can infect in the brain and what the inflammatory response is. This provides more insight into the cause of the neurological problems.
The research was done by researchers from the Department of Virology and Psychiatry. They collaborated to combine viral research with research into human brain cell models. With so-called ‘pluripotent stem cell technology’, skin or blood cells can be ‘reprogrammed’ into stem cells. These can then develop into any type of body cell, including neurons. These are brain cells that make connections with each other.
The brain cells are exposed to SARS-CoV-2. The researchers saw that the virus was able to infect neurons. The spread then also stops quickly and is limited to a few cells. However, they see that this minimal infection leads to a reaction of the cytokines, the messengers between the immune cells. They may play a role in local inflammation.
‘What we saw is consistent with the fact that infection with SARS-CoV-2 rarely leads to severe encephalitis because the virus spreads uncontrollably in the brain. But the fact that SARS-CoV-2 can possibly enter the brain via the olfactory nerve and locally infect cells, which in turn leads to an inflammatory response, can certainly contribute to neurological complaints,’ says Debby van Riel of the Virology department at Erasmus MC.
The brain-related complaints after COVID-19 probably have different causes. ‘In addition to the findings from our research, the immune system probably also plays a role. More research is needed to find out,’ says researcher Femke de Vrij, of the Department of Psychiatry. Follow-up research should also provide more information about what SARS-CoV-2 does in the brain in the longer term.
‘We have now monitored the virus in the cells over a short period of time. We also only looked at a limited number of types of brain cells. By allowing the cells in a different model to develop into networks with more cell types and an organized structure, we can learn more about what a virus infection does to brain structures in the short and long term.’
Source: Erasmus MC