A1 astrocytes secrete pro-inflammatory molecules (TNF-α, [Tumor Necrosis Factor 1-Alpha] IL-6 [Interleukin-6], IL-1β [Interleukin-1 beta], and IL-1α [Interleukin-1 alpha]) whereas A2 astrocytes have an anti-inflammatory secretory profile [neurotrophic factors (Prokineticin-2 (PK2), Chitin-like 3, Frizzled class receptor 1, Nrf2, Pentraxin 3 (PTX3), Sphingosine kinase 1, and Transmembrane 4 L6 family member 1] in the AD brain [26,27,28]. Here, TM4SF1 is linked to Alzheimer disease.