TREM2 and Alzheimer disease: For example, there is evident dysregulation of endogenous microglia regulatory molecules such as loss of CX3CR1 and TREM2 that can cause microgliosis and exacerbate AD pathology [241,271] While these findings implicate a dynamic microglia activation profile, the overall response of microglia in AD is more complicated than what is described by the two distinct activation phenotypes.