Maternal exposure to airborne particulate matter causes postnatal immunological dysfunction in mice offspring

Evidence suggests that prenatal exposure to air pollution affects the ontogeny and development of the fetal immune system. The aim of this study was to investigate the effect of maternal exposure to airborne particulate matter (PM) on immune function in postnatal offspring. Pregnant female ICR mice were intralaryngopharyngeally administered with 30 μl of phosphate buffered solution (the control group) or resuspended PM of Standard Reference Material 1649a at 0.09 (low), 0.28 (medium), 1.85 (high) or 6.92 (overdose) μg/μl once every three days from day 0 to 18 of pregnancy (n=8-10). Offspring were sacrificed on postnatal day 30. Interleukin-4 and interferon-γ levels in plasma and splenocytes, splenic lymphocyte proliferation, and expressions of GATA-3 and T-bet mRNA in the spleen were tested. The spleen and thymus were histopathologically examined. The offspring of the medium, high and overdose PM-exposed dams showed significantly suppressed splenocyte proliferation. Decreased interferon-γ and increased interleukin-4 levels in the blood and splenocytes, and lowered T-bet and elevated GATA-3 mRNA expressions were found in the spleen in the medium, high and overdose groups when compared with the control or low dose group (P<0.05). Histopathology revealed prominent tissue damage in the spleen and thymus in the overdose group. These results suggest that exposure of pregnant mice to PM modulates the fetal immune system, resulting in postnatal immune dysfunction by exacerbation of Thl/Th2 deviation. This deviation is associated with altered T-bet and GATA-3 gene expressions.