Fig. 12

Schematic diagram of the possible mechanisms involved in the enhanced production of pro-inflammatory cytokine IL-1β and increased MMP-9 activity in alveolar macrophages exposed to PM_2.5 in a high glucose environment. PM_2.5 exposure in a high glucose environment causes enhanced ROS generation, which induces nuclear translocation of the transcription factor NF-κB. Binding of NF-κB on the promoter regions of NLRP3 and IL-1β results in their upregulation, leading to the activation of NLRP3 inflammasome, which cleaves pro-IL-1β to IL-1β. IL-1β is involved in the inflammatory response and a variety of cellular activities including MMP-9 upregulation