Lung infection alters perivascular aquaporin-4 in rat model of Alzheimer’s Disease detected by filter exchange imaging (FEXI)

Motivation: Pneumonia is more prevalent in Alzheimer’s Disease (AD) patients than in healthy elderly people, which may be due to blood-brain barrier (BBB) vulnerability. Goal(s): We assess whether filter exchange imaging (FEXI) can be used to understand the comorbid mechanisms occurring at the BBB with pneumonia and AD. Approach: We apply the FEXI technique to a TgF344-AD rat model of AD with induced Streptococcus pneumoniae lung infection. Results: FEXI detects significantly higher BBB water exchange in infected rats, with greater increase in the AD group, which significantly correlates to upregulation of hippocampus aquaporin-4 water channels, demonstrating the sensitivity of non-invasive FEXI to BBB alterations. Impact: This work could be translated to a clinical study using filter exchange imaging to assess whether Alzheimer’s Disease patients suffering with pneumonia also exhibit worse blood-brain barrier alterations than patients without pneumonia and healthy elderly people.