The Infectious Contribution to Alzheimer's disease -- assessing the role of Chlamydia pneumoniae infection — The Association Specialists

The Infectious Contribution to Alzheimer's disease -- assessing the role of Chlamydia pneumoniae infection (21899)

Amy McEwen 1 2 , Andrea Standke 1 2 , Edith Miller 1 2 , Ali Delbaz 1 2 , James St John 1 2
  1. Griffith University, Southport, QLD, Australia
  2. Clem Jones Centre for Neurobiology and Stem Cell Research, Southport, QLD, Australia

Chlamydia pneumoniae is an intracellular pathogen that infects the respiratory tract and has been linked to infecting the central nervous system. C. pneumoniae has been shown to be present in people with Alzheimer's disease, with prior work within our lab showing that this bacteria utilises nerves in the olfactory system and their associated glial cells to get direct entry into our brain. The presence of C. pneumoniae has been associated with amyloid beta accumulation, a hallmark feature of the disease. To assess how C. pneumoniae contributes to Alzheimer's disease progression, in vivo murine models were used. Assessing how intranasal inoculation of C. pneumoniae in childhood (Postnatal Day 14, P14), adulthood (P84) and re-infection (P14 & P84) was used to establish how the bacterium is linked to key pathways in Alzheimer's disease progression. RNA-Seq results of the olfactory mucosa showed how inoculation of the nasal cavity with Chlamydia pneumoniae led to the dysregulation of genes associated with Alzheimer's disease. Mice that were subject to a repeat exposure had an increased susceptibility of gene expression linked to neurodegenerative diseases. Proteomic analysis of the olfactory bulb also showed a response consistent with disease progression. These results indicate that repeat infections of Chlamydia pneumoniae may contribute to an increased risk in Alzheimer's disease. Establishing pre-clinical testing, such as the Smell Clinic at Griffith University, will allow for individuals prior to any signs of neurodegeneration to be assessed for risks. Further research into the nose-brain axis may lead to the establishment of therapies. 

  1. Chacko, A., Delbaz, A., Walkden, H. et al. Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer’s disease risk. Sci Rep 12, 2759 (2022). https://doi.org/10.1038/s41598-022-06749-9