TABLE 1.
Summary of in vivo experimental studies of PM2.5 on respiratory host defense.
| Animal species | Pathogen | Exposure method | Effects on respiratory host defense | References |
| SD rats | Listeria | Intranasal instillation | Exposure to diesel exhaust particles (DEP) decreased the ability of macrophages to produce antimicrobial oxidants in response to Listeria, which may play a role in the increased susceptibility of rats to pulmonary infection | Yang et al., 2001 |
| BALB/c mice | S. pneumoniae | Intranasal instillation | The combination of γ-interferon (IFN-γ) priming and concentrated ambient particles (CAPs) exposure led to an inflamed alveolar milieu where oxidant stress caused loss of antibacterial functions in alveolar macrophages (AMs) and recruited polymorphonuclear granulocytes (PMNs) | Sigaud et al., 2007 |
| BALB/c mice | S. pneumoniae | Whole-body exposure (smoking) | Exposure to wood smoke-derived particulate matter decreased the ability of pulmonary macrophages to effectively mount a defense against infection, and appeared to be mediated via RelB activation | Migliaccio et al., 2013 |
| SD rats | K. pneumoniae | Intranasal instillation | PM2.5 exposure increased the susceptibility of the rats to K. pneumoniae infection and decreased bacterial clearance. Its mechanism may be related to the impairment of bronchial mucociliary system and interaction of cytokines. | Duan et al., 2013 |
| Wistar rats | S. aureus | Intranasal instillation | Exposure to PM2.5 increased susceptibility to respiratory S. aureus infection in rats via reducing pulmonary natural killer cells and suppressing the phagocytosis ability of AMs. | Zhao et al., 2014 |
| Mice* | Influenza virus | Intranasal inhalation | Long-term exposure to PM2.5 lowered influenza virus resistance via down-regulating pulmonary macrophage Kdm6a and mediated histones modification in IL-6 and IFN-β promoter regions | Ma et al., 2017 |
| C57BL/6J mice | P. aeruginosa | Intracheal instillation | PM disrupted tight junctions (TJs) via oxidative stress to promote bacterial infection | Liu et al., 2019a |
*The specific strain is not indicated in the literature.