GROUNDBREAKING research has shown that chronic intestinal infections caused by cytomegalovirus (HCMV) may play a role in a distinct subtype of Alzheimer’s disease, offering new insights into potential treatment avenues.
This collaborative study, led by Arizona State University and the Banner Alzheimer’s Institute, investigated the link between HCMV, a common virus often acquired in early life, and Alzheimer’s. HCMV is usually harmless, but in some individuals, it remains active in the gut, potentially traveling to the brain via the vagus nerve. This pathway could trigger immune responses and molecular changes, such as amyloid plaque and tau tangle formation, both hallmark characteristics of Alzheimer’s disease.
To explore this hypothesis, the researchers conducted a detailed analysis of postmortem tissue samples, including intestines, brain, and vagus nerve, from Alzheimer’s patients. They identified active HCMV infections in a subset of these individuals, along with the presence of CD83(+) microglia, a specific type of immune cell linked to chronic inflammation. Further experiments using human brain cell models revealed that exposure to HCMV induced the production of amyloid proteins and phosphorylated tau, key drivers of Alzheimer’s pathology. These findings suggest a potential causal link between chronic HCMV infections and neurodegenerative changes in the brain.
The implications of these findings are significant for clinical practice. If validated by further studies, existing antiviral drugs might be repurposed to treat this form of Alzheimer’s. Additionally, the development of a blood test to identify individuals with chronic HCMV infections could help target therapies to those most likely to benefit. As the research team continues to refine diagnostic tools and evaluate therapeutic options, their work highlights the importance of considering systemic factors, like chronic infections, in understanding and managing Alzheimer’s disease.
Future studies are needed to confirm these findings in larger cohorts and to determine whether antiviral treatments can effectively alter disease progression. If successful, this research could redefine approaches to Alzheimer’s care, particularly for patients with this biologically unique subtype.
Katrina Thornber, EMJ
Reference
Redhead BP et al. Alzheimer’s disease-associated CD83(+) microglia are linked with increased immunoglobulin G4 and human cytomegalovirus in the gut, vagal nerve, and brain. Alzheimer’s & Dementia. 2024;DOI:10.1002/alz.14401.
