Table 2: In vitro evidence that supports and provides plausible mechanisms for the in vivo observed effects induced by PM and NP.

In vitro evidence supporting the observed in vivo effects
In vivo observed effectIn vitro evidence

Oxidative stressROS increases via NADPH-oxidase
in lung epithelial cell exposed to PM.
Local and systemic inflammationSecretion of IL-1b, IL-6, IL-8, TNFa,
MCP-1, and so forth, by lung cells,
macrophages, and cocultures.
HyperplasiaProliferative stimuli induced by
extracts of DEP components.
COPDIncreased cytotoxicity on exposed
cell cultures.
Systemic and endothelial dysfunctionEndothelial cell activation by direct
contact with particles or indirectly
induced in cocultures where
pneumocytes, macrophages,
and other cell are exposed.
Particle translocationChanges in the TEER values related
to tight junctions
Macrophage-dendritic
transepithelial cells network
alterations in the GJIC.