Immune responses induced by particulate matter with a diameter ≤2.5 μm (PM2.5)
| Experimental platform | PM2.5 exposure time# | Immune response | Reference |
|---|---|---|---|
| Immune responses enhanced by PM2.5 | |||
| Peritoneal macrophages isolated from C57BL/6 mice | Short-term | PM2.5 induces polarisation of macrophage through induction of ROS | [105] |
| Human umbilical vein cell line, EA.hy926 | Short-term | PM2.5 induces ERK/AKT/NF-κB signalling pathway and results in increased ICAM-1 and VCAM-1 expression | [96] |
| Human bronchial epithelial cells, 16HBE cells | Short-term | PM2.5 induces the NLRP3/caspase-1 pathway and results in cell-secreted inflammatory cytokines | [70] |
| Murine model | Short-term | PM2.5 increases ACE2 and TMPRSS2 expression | [93] |
| BALB/c mice | Long-term (6 days) | PM2.5 increases ACE2, COX-2 and HO-1 expression in several organs, including lung, heart, liver and brain | [103] |
| BALB/c mice | Long-term (14 days) | PM2.5 induces the NLRP3/caspase-1 pathway and results in mice lung inflammatory | [70] |
| BALB/c mice | Long-term (90 days) | PM2.5 activates the Notch signalling pathway and results in increased Th1/Th2 and Th17/Treg cells | [108] |
| C57BL/6 mice | Long-term (12 weeks) | PM2.5 regulates TNF-α and IL-6, leading to lung damage | [117] |
| Human experiment: traffic policemen | Long-term (4 months) | PM2.5 elevates hsCRP, IgM, IgG and IgE | [106] |
| Immune responses reduced by PM2.5 | |||
| Human experiment: traffic policemen | Long-term (4 months) | PM2.5 decreases the expression of IgA and CD8+ T-cells | [106] |
#: Short-term exposure: exposure to PM2.5 within 24 h; long-term exposure: exposure to PM2.5 for more than 24 h. ACE2: angiotensin converting enzyme 2; AKT: protein kinase B; COX-2: cyclooxygenase 2; ERK: extracellular signal-regulated kinase; HO-1: haem oxygenase 1; hsCRP: highly sensitive C-reactive protein; ICAM-1: intercellular adhesion molecule-1; IL: interleukin; NLRP3: nucleotide-binding oligomerisation domain-like receptor family, pyrin domain containing protein 3; ROS: reactive oxygen species; Th: T-helper cell; TMPRSS2: transmembrane protease serine 2; TNF-α: tumour necrosis factor-α; Treg: regulatory T-cell; VCAM1: vascular cell adhesion molecule-1.