TLR4 and acute respiratory distress syndrome: In this study, we have tested the effect of infrared light exposure, PEMF exposure, and static magnetic field exposure on a cell culture system specifically engineered to initiate an inflammatory immune response through the Toll-like receptor 4 (TLR4) signaling pathway (HEK – TLR4; see methods) responsible for the acute respiratory distress syndrome induced by lung pathogens [42].