NOS2 and Alzheimer disease: These mice carry the humanized apolipoprotein E (APOE) gene (ε2, ε3, and ε4) to model different levels of AD genetic risk; and either mouse Nos2 or humanized nitric oxide synthase 2 (hNOS2) to mimic human-like immune responses; sex (male and females); age (middle-a and old aged); and environmental stressors such as high-fat diet [28,29,30].