TREM2 and infectious disease: The duality of TREM2 in regulating inflammation and killing bacteria in different tissues suggests a more complex role for TREM2 in infection diseases, future studies examining the hub role of the membrane bound TREM2 in different pathogens and the bioactivity of soluble forms of TREM2 in infectious diseases may yield significant insight into the role of TREM2 as a prognostic and diagnostic tool and its potential as therapeutic target.