The 18 kDa translocator protein is associated with microglia in the hippocampus of non-demented elderly subjects

Benjamin B Tournier; Christophe Snoeijs; Stergios Tsartsalis; Quentin Amossé; Ramzi Farchoukh; Eniko Kövari; Kelly Ceyzériat; Philippe Millet

doi:10.1016/j.nbas.2022.100045

The 18 kDa translocator protein is associated with microglia in the hippocampus of non-demented elderly subjects

Aging Brain. 2022 Jul 8:2:100045. doi: 10.1016/j.nbas.2022.100045. eCollection 2022.

Authors

Benjamin B Tournier^{1

2}, Christophe Snoeijs², Stergios Tsartsalis^{1

2}, Quentin Amossé^{1

2}, Ramzi Farchoukh², Eniko Kövari^{1

2}, Kelly Ceyzériat^{1

2

3

4}, Philippe Millet^{1

2}

Affiliations

¹ Department of Psychiatry, University Hospitals of Geneva, Switzerland.
² Department of Psychiatry, University of Geneva, Switzerland.
³ Division of Nuclear Medicine and Molecular Imaging, Diagnostic Department, University Hospitals of Geneva, Switzerland.
⁴ Division of Radiation Oncology, Department of Oncology, University Hospitals of Geneva, Switzerland.

Abstract

Increase in the brain expression of the 18 kDa translocator protein (TSPO) is considered as a marker of neuroinflammation in the context of brain diseases, such as Alzheimer's disease (AD). However, in non-demented subjects with Alzheimer's neuropathology, TSPO accumulation in hippocampus subdivisions has not been fully characterized. To determine if TSPO is associated with the presence of amyloid β plaques and/or phosphorylated Tau accumulation, we analyzed hippocampal sections using immunohistochemistry of 14 non-demented subjects with positive staining for Aβ and/or phosphorylated Tau. TSPO expression was heterogenous with higher accumulation in the CA2/3 and subiculum subfields of the hippocampus. Its distribution closely resembled that of the microglial IBA1 marker and of the Aβ42 amyloid form. In addition, positive correlations were observed between TSPO and IBA1 densities in CA4, CA2/3 and the subiculum but not with either the astrocyte GFAP marker or the AD-type Aβ and Tau markers. This study sustains the hypothesis that TSPO is mainly associated with microglia and in Aβ42-rich subdivisions in the hippocampus of non-demented elderly individuals.

Keywords: Alzheimer’s disease; Neuropathology; Non-demented; TSPO; TSPO, 18 kDa translocator protein.