NLRP3 and pulmonary fibrosis: Nanomaterials including rare earth oxides (REOs), high-aspect-ratio materials including carbon nanotube (single-walled and multi-walled), TiO2 nanobelts and CeO2 nanorods, 2D materials including graphene and graphene oxide could induce NLRP3 inflammasome activation and a series of events leading to epithelial mesenchymal transition and lung fibrosis.