C1QA and Alzheimer disease: Among these downregulated proteins, Tmem9 (transmembrane protein 9) accompanied by C1qa and C1qb proteins is a potential candidate for intervention targets in AD mice (Figure 1C), as synaptic loss, critically induced by C1q activation, is strongly correlated with cognitive decline in AD (Dejanovic et al. 2022, 2018; Leng and Edison 2021), and Tmem proteins regulate lysosomal acidification, thereby affecting the activation of complement cascades (Feng et al. 2021; Klein et al. 2017).