COVID-19 viral spike proteins accumulate in skull, brain and meninges and may cause neurodegeneration.

Representative image of Corona virus (pixabay.com)

 

 It has been found that the spike proteins of COVID-19 causing virus accumulate in the skull-meninges-brain axis. This is the area in meninges, and parts of skull and brain near to it. The presence of spike proteins causes inflammation in the area and can cause cerebral eschemia, a condition caused by insufficient supply of blood to the brain.

The skull, meninges and brain tissue from people who had survived covid and died later due to non-covid reasons were analysed. It was found that the majority of the spike proteins in skull-marrow were outside the blood vessels. The spike proteins were also found in brain frontal cortex, an area near to the skull and also the brain tissue.

COVID-19 patients are prone to have brain haemorrhage. Even though the patients analysed here did not die of COVID-19, the researchers detected micro-bleeding in the brain region. The micro-bleeding was also, observed in patients in which spike protein were not detected in skull-meninges-brain region.

The presence of spike proteins was also associated with the observation of markers of neurodegeneration. Thus, the persistence of the spike protein in tissues might be the contributing factor for long-covid.

Mice infected with covid virus showed presence of spike-protein in their head even after 28 days of infection. When spike protein was injected intravenously, it accumulated near blood vessels of various tissue such as heart, liver, kidney, lung, intestine, spleen, thymus, pancreas and brain. It also was detected in the femur and tibia bones.

The protein expression pattern in human meninges tissue was different in covid-infected and healthy people. A blood-brain-barrier damage associated protein was upregulated in samples with spike proteins while, Myelin Basic Protein, which is associated with multiple sclerosis was downregulated. These kinds of proteomic changes were also observed in the experimental mice and also caused anxiety-like behaviour in them, 3 days after infection. Although the anxiety-like behaviour had vanished when observed after 28 days.

Spike protein was injected in the skull marrow of mice and found that it alone can trigger inflammation in the brain cortex.

Effect of vaccines on accumulation of spike protein in the meninges-skull-brain tissue was tested by infecting vaccinated and unvaccinated mice with omicron variant of the virus. The vaccinated mice were given two doses of BioNTech/Pfizer Comirnaty vaccine intramuscularly. It was observed that the vaccinated mice accumulated less spike protein in their skull, brain, lungs, liver, heart and kidney tissues. These results suggest a quicker clearance of the virus by the vaccinated mice.

Reference:

Rong, Zhouyi, Hongcheng Mai, Gregor Ebert, Saketh Kapoor, Victor G. Puelles, Jan Czogalla, Senbin Hu, et al. 2024. “Persistence of Spike Protein at the Skull-Meninges-Brain Axis May Contribute to the Neurological Sequelae of COVID-19.” Cell Host & Microbe 0 (0). Elsevier. doi:10.1016/j.chom.2024.11.007.