SPP1 and Alzheimer disease: During neuro-inflammation or degeneration in pathologies like MS, amyotrophic lateral sclerosis, stroke and Alzheimer’s disease, microglia generally respond by secreting SPP1/Osteopontin, IL-1β, and Complement (C)1q, which prompts quiescent astrocytes to acquire an immune-reactive phenotype42,43,56,57.