TREM2 and Alzheimer disease: Recent studies have found that soluble TREM2 (sTREM2) can cross the BBB and may disrupt the integrity of the BBB in the context of AD [162], possibly by interacting with pro-inflammatory proteins such as TNF receptor 1 and TNF receptor 2, and their effectors like intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 [163].