Shedding light on innate immune dysfunction in a mouse model of Alzheimer’s disease using a novel myeloid cell‐targeted PET imaging strategy

Non‐invasive assessment of maladaptive innate immune responses in the brains of Alzheimer’s disease (AD) patients is a critical unmet need; such techniques have the potential to not only improve diagnosis and disease monitoring, but also serve as endpoints in clinical trials of novel therapeutics. Positron emission tomography (PET) imaging of the translocator protein 18 kDa (TSPO) is a widely used experimental approach for assessing inflammation in vivo but is limited by its lack of cell specificity and inability to discriminate between beneficial and adverse immune responses. We developed the first PET probe targeting triggering receptor expressed on myeloid cells 1 (TREM1) and demonstrated its ability to specifically detect CNS‐infiltrating pathogenic peripheral myeloid cells (e.g., macrophages, monocytes, neutrophils) in the context of neurological disease. Herein, we assess the utility of TREM1‐PET compared to TSPO‐PET for detecting innate immune responses in the 5XFAD mouse model of AD.