On the nerves
Jenny Ekberg and her colleagues from Menzies Health Institute Queensland and Griffith Institute for Drug Discovery in collaboration with Queensland University of Technology have discovered that the bacterium Chlamydia pneumoniae can enter the brain from the nasal cavity via the olfactory and trigeminal nerves.
C.pneumoniae often causes respiratory tract infections, but has also been found in the brain, raising the question of whether it causes damage to the central nervous system.
The research team conducted experiments on animal models and showed that the bacterium enters the brain via the olfactory and trigeminal nerves, bypassing the blood-brain barrier. Brain cells react to C.pneumoniae for several days by accumulating the beta-amyloid protein. After a few weeks, numerous gene pathways that are known to be involved in Alzheimer's disease are also dramatically activated.
A.A diagram illustrating the process of quantifying viable infectious C.pneumoniae present in various mouse tissues. Mice were first intranasally infected with C.pneumoniae (i), some with epithelial damage, and some without it. After 24 hours, 3 days, 7 days or 28 days, the selected brain tissues were homogenized in test tubes (ii) and incubated (iii). The cells were fixed and the number of inclusions characteristic of C.pneumoniae was determined.
B.Microscopic image showing a sagittal section of mouse brain tissue. The cell nuclei are colored blue. NC is the nasal cavity, OE is the olfactory epithelium, OB is the olfactory bulb, Tg is the trigeminal nerve (not visible on the slice, so the approximate location is shown by a white dotted line), Brain is the brain.
The study also showed that the bacterium can persist in the body for a long time, "hiding" in glial cells.
The authors emphasize that, despite the link between the presence of C.pneumoniae and the development of Alzheimer's disease, bacteria alone may not be enough to cause diseases. Perhaps this requires a combination of genetic predisposition, infection and other factors.
The bacterium C. pneumoniae (green) in the olfactory bulb of the brain. Beta-amyloid (red) accumulates around bacteria. The nuclei of brain cells are indicated in blue.
The study was conducted on mice, but the results obtained are probably applicable to humans, since the human body has the same nerves and can be infected with the bacterium C.pneumoniae. The group has already started working on treatment options that allow glial cells to destroy bacteria that have already entered the central nervous system. In addition, the researchers plan to create a vaccine that will reduce the ability of the pathogen to enter the brain.
Article by A.Chacko et al. Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer's disease risk published in the journal Scientific Reports.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru according to Griffith News: Bacteria in the nose may increase the risk of Alzheimer's disease.