Researchers at Griffith University in Australia have found that a bacteria called Chlamydia pneumoniae, found in the nose and responsible for respiratory tract infections, can reach the brain and cause reactions related to Alzheimer’s disease.
The bacterium uses a shorter, direct route to the brain, which bypasses the blood-brain barrier that makes it difficult for blood to pass to the central nervous system, making it an easy route into the area.
For researchers, picking the nose and damaging the internal lining of this organ can contribute to the increase in the number of bacteria that reach the brain.
“We are the first to show that Chlamydia pneumoniae can travel directly into the nose and into the brain, where it can trigger pathologies that resemble Alzheimer’s disease,” said the professor and director of the Clem Jones Center for Neurobiology and Stem Cell Research, James John, at Griffith News Portal.
Scientists have confirmed this possibility from experiments on mice. “We’ve seen this happen in a mouse model, and the evidence is potentially chilling for humans as well,” says John.
When the bacteria reached the rodents’ brains, the cells reacted by depositing the protein beta-amyloid, a hallmark of Alzheimer’s disease. After a few weeks, the genetic pathways linked to the disease were also activated.
The researchers also noticed that the bacterium infects glial nerve cells (found in nerve tissue and responsible for a range of functions), allowing it to stay in the central nervous system longer.
“These cells are often important defenders against bacteria, but in this case they become infected and can help bacteria spread,” said Jenny Ekberg, associate professor at the Clem Jones Center for Neurobiology and Stem Cell Research.
However, the bacterium may not be solely responsible for the onset of Alzheimer’s disease, specifies the professor.
“We have long suspected that bacteria and even viruses can drive neuroinflammation and contribute to the onset of Alzheimer’s disease. However, bacteria alone may not be enough to cause someone to become ill. Perhaps that it requires the combination of genetic susceptibility plus bacteria to lead to long-term Alzheimer’s disease,” says Ekberg.