A new study suggests that a common respiratory bacterium may play an unexpected role in Alzheimer’s disease.
Cedars-Sinai researchers are pointing to an unexpected place to look for clues about Alzheimer’s disease: the eye. In a study published in Nature Communications, they report evidence that Chlamydia pneumoniae, best known for causing pneumonia and sinus infections, can persist for years in the body and may be tied to changes seen in Alzheimer’s disease.
The work raises the possibility that a long-lasting infection could help fuel the kind of inflammation that damages nerve cells, and it also hints at new ways to intervene, from inflammation-limited approaches to earlier antibiotic treatment.
The study found that the bacterium can show up in the retina, the thin layer of neural tissue at the back of the eye that directly processes visual signals. Because the retina is part of the central nervous system and can be examined without surgery, it offers a rare chance to watch brain-linked biology in real time. The team found that when Chlamydia pneumoniae reaches this tissue, it is associated with immune activity connected to inflammation, nerve cell death, and cognitive decline.
Linking Infection, Inflammation, and Neurodegeneration
“Seeing Chlamydia pneumoniae consistently across human tissues, cell cultures and animal models allowed us to identify a previously unrecognized link between bacterial infection, inflammation and neurodegeneration,” said Maya Koronyo-Hamaoui, PhD, professor of Neurosurgery, Neurology, and Biomedical Sciences at Cedars-Sinai Health Sciences University and the leading, senior author of the study. “The eye is a surrogate for the brain, and this study shows that retinal bacterial infection and chronic inflammation can reflect brain pathology and predict disease status, supporting retinal imaging as a noninvasive way to identify people at risk for Alzheimer’s.”
