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A new finding that even took the study’s authors by surprise lends support to the controversial idea that microbes play a role in Alzheimer’s disease. The research published June 21 in Neuron, found convincing signs that certain types of herpes virus may promote the complex process that leads to the disease that afflicts some 5.7 million Americans. The study points to the viruses as possible accomplices that drive disease progression but does not suggest that Alzheimer’s may begin after they are transmitted through casual contact.
Joel Dudley, a geneticist and genomic scientist at the Icahn School of Medicine at Mount Sinai and senior author of the new paper, had not intended to investigate this theory when his lab began working on the newly published study in 2013. The plan he had made with colleagues was to identify possible new Alzheimer’s drug targets by looking at the molecular changes in the brain that occur during the disease. Thanks to a new NIH-led public-private partnership called the Accelerating Medicines Partnership Alzheimer's Disease (AMP-AD), the team had access to data from 876 brains—some healthy and some with early- or late-stage Alzheimer’s. They used DNA and RNA sequencing to parse out genetic differences between the groups as well as differences in how inherited genes were expressed or made into RNA. That’s when they started getting strange results. “The algorithms kept returning this pattern for viral biology,” Dudley says.
The team found more viral DNA in Alzheimer’s brains compared with healthy brains—specifically, high levels of DNA from human herpesvirus 6A (HHV-6A). RNA of both HHV-6A and HHV-7 were also higher in the Alzheimer’s brains than in healthy brains, and viral RNA levels tracked with the severity of clinical symptoms. HHV-6A is a usually symptom-less virus that infects people later in life. HHV-7 infects more than 80 percent of infants, often causing a rash.
Original research Published in Neuron on June 21, 2018
https://doi.org/10.1016/j.neuron.2018.05.023
En effet, les résultats indiquent qu’une infection virale déclenche une réaction inflammatoire protectrice du système immunitaire de l’organisme contre le virus mais que celle-ci contribue à la mort des neurones et favorise ainsi la progression de la maladie.
Ces résultats sont intéressants puisqu’ils mettent en lumière l’importance de la prévention contre les virus et l’importance de se protéger. Il s’agit d’un argument de plus montrant l’importance et la nécessité des campagnes de prévention/de vaccination et dépistage en population générale.