TSPO and Alzheimer disease: CLUSTERIN, a protein secreted by astrocytes and known to promote formation of extracellular Aβ deposits [54, 55], and an AD GWAS gene, was significantly reduced in 3xTgAD.TSPO−/− mice (−9±1.2%, P = 0.024, Fig. 3B), further suggesting a reduction in the pro-inflammatory state of astrocytes [56].