PM 2.5 collected in a residential area induced Th1-type inflammatory responses with oxidative stress in mice

Epidemiologists have tried to establish an association between human health and exposure to particulate matter (PM). In addition, many researchers have investigated the adverse effects of PM as a trigger of cardiovascular and pulmonary diseases. It is known that a number of environmental contaminants are attached to PM and the toxicity of PM may depend on the sources. We investigated the effects of PM collected in a residential area of Seoul on the immunotoxic responses including cytokine production in BAL fluid and in blood after a single intratracheal instillation in mice with the characterization of physico-chemical properties of PM 2.5 samples. As results, pro-inflammatory cytokines (IL-1, TNF-α, and IL-6), Th0-type cytokine (IL-2), and Th1-type cytokines (IL-12 and IFN-γ) were increased by a dose-dependent manner. Cell infiltration in the alveolar area and phagocytosis by macrophage was observed until day 28 after instillation. The expressions of oxidative stress-related genes (HSP 1a, HSP 8, and SOD) and tissue damage-related genes (MMP-15, -19, and Slpi) were time-dependently increased. PM 2.5 also induced an increase of T cell distribution in lymphocyte and decreased the CD4+/CD8+ ratio. Based on the results, we suggest that PM 2.5 collected in a residential area of Seoul may induce Th1 type-inflammatory responses with oxidative stress and trigger adverse effects in human health.

Research highlights
► Particulate matter is one of the important environmental risk factor.
► Many epidemiological studies have suggested that PM increases pulmonary morbidity and mortality, and it exacerbates allergic rhinitis and asthma especially in industrialized urban areas.
► It is known that the relationships between PM exposure and adverse effects on human health are more sensitively shown by PM 2.5 than by PM 10.
► I think an environmental disease is caused by break of an immune balance by inflowing of ambient particles into lung.
► In this study, we investigated a series of immunotoxic responses by PM 2.5.