Researchers have found a link between chronic intestinal infections caused by common viruses and the development of Alzheimer’s disease in some people.
most people encounter cytomegalovirus (CMV) After initial infection, the virus remains in the body for life and is usually dormant.
When I turned 80, 9 out of 10 people You will have tell-tale antibodies to CMV in your blood. sort of herpes virusPathogens spread through body fluids (breast milk, saliva, blood, semen, etc.), but only when the virus is active.
In one unlucky group, research suggests the virus may have discovered a biological loophole that allows it to remain active long enough to officially travel up the gut-brain axis ‘superhighway’. vagus nerve.
If the active virus reaches the brain, it can worsen the immune system and possibly contribute to the development of Alzheimer’s disease.
This is a worrisome possibility, but it also means that antiviral drugs could prevent some people from developing Alzheimer’s disease, especially if researchers can develop a blood test that can quickly detect active CMV infection in the gut.
Earlier this year, some members of the Arizona State University team announced the link A subtype of microglial cells associated with Alzheimer’s disease, named CD83(+) due to the genetic characteristics of the cells, and elevated levels of immunoglobulin G4 in the transverse colon, suggesting some type of infection.
Microglia are cells that perform cleaning duties throughout the central nervous system. They clean out plaque, debris, surplus or broken neurons and synapses. Munching Block them where possible and sound the alarm when infection or damage gets out of control.
They are here to help, but when microglia work continuously, releasing inflammatory weapons non-stop, they can lead to the neuronal damage associated with Alzheimer’s disease.
“We think we have discovered a biologically unique subtype of Alzheimer’s disease that may affect 25 to 45 percent of people with the disease,” said lead author Ben Readhead, a biomedical scientist at Arizona State University. . says.
“This subtype of Alzheimer’s disease includes characteristic amyloid plaques and tau tangles (microscopic brain abnormalities used for diagnosis) and is characterized by a distinct biological profile of viruses, antibodies and immune cells in the brain.”
Researchers had access to a variety of organ tissue, including colon, vagus nerve, brain and spinal fluid, donated from 101 physical donors, 66 of whom had Alzheimer’s disease. This has helped us study how body systems interact with Alzheimer’s disease, which is often considered through a purely neurological lens.
They traced the presence of CMV antibodies from the donor’s gut to the spinal fluid to the brain, and even found the virus itself lurking within the donor’s vagus nerve.
The same pattern emerged when the study was repeated in a separate, independent cohort.
Human brain cell models provided further evidence of virus involvement by increasing amyloid and phosphorylated tau protein production and contributing to neurodegeneration and death.
Importantly, this association was found only in a very small subset of individuals with chronic intestinal CMV infection. Considering that almost everyone comes into contact with CMV, simply being exposed to the virus is not always a cause for concern.
Readhead and the team are working to develop a blood test that can detect enteric CMV infection so that it can be treated with antiviral drugs and prevent patients from developing this type of Alzheimer’s disease.
This study Alzheimer’s disease and dementia: Journal of the Alzheimer’s Association.
