IL1B and acute respiratory distress syndrome: In addition, elevated production of IL-6 has been suggested to be stimulated by IL-1β and TNF-α, and IL-6 can also be produced by a variety of cells, including macrophages and endothelial cells [38]; moreover, circulating levels of IL-6 have been considered by many studies to be a major predictive marker of ARDS severity due to different etiologies [39,40].