Pregnancy protects against the pro-inflammatory respiratory responses induced by particulate matter exposure

Maternal exposure to ultrafine particles enhances influenza infection during pregnancy

BACKGROUND

Interactions between air pollution and infectious agents are increasingly recognized and critical to identify, especially to protect vulnerable populations. Pregnancy represents a vulnerable period for influenza infection and air pollution exposure, yet interactions during pregnancy remain unclear. Maternal exposure to ultrafine particles (UFPs, [Formula: see text] 100 nm diameter), a class of particulate matter ubiquitous in urban environments, elicits unique pulmonary immune responses. We hypothesized that UFP exposure during pregnancy would lead to aberrant immune responses to influenza enhancing infection severity.

RESULTS

Building from our well-characterized C57Bl/6N mouse model employing daily gestational UFP exposure from gestational day (GD) 0.5-13.5, we carried out a pilot study wherein pregnant dams were subsequently infected with Influenza A/Puerto Rico/8/1934 (PR8) on GD14.5. Findings indicate that PR8 infection caused decreased weight gain in filtered air (FA) and UFP-exposed groups. Co-exposure to UFPs and viral infection led to pronounced elevation in PR8 viral titer and reduced pulmonary inflammation, signifying potential suppression of innate and adaptive immune defenses. Pulmonary expression of the pro-viral factor sphingosine kinase 1 (Sphk1) and pro-inflammatory cytokine interleukin-1β (IL-1 [Formula: see text]) was significantly increased in pregnant mice exposed to UFPs and infected with PR8; expression correlated with higher viral titer.

CONCLUSIONS

Results from our model provide initial insight into how maternal UFP exposure during pregnancy enhances respiratory viral infection risk. This model is an important first step in establishing future regulatory and clinical strategies for protecting pregnant women exposed to UFPs.

The Acute Effect of Diesel Exhaust Particles and Different Fractions Exposure on Blood Coagulation Function in Mice

The toxicity and widespread exposure opportunity of diesel exhaust particles (DEP) has aroused public health concerns. This study aimed to investigate the acute effect of DEP and different fractions exposure on blood coagulation function in mice. In this study, nine- week-old C57BL/6J male mice were divided into four exposure groups (with 15 mice in each group). The water-soluble (WS) and water-insoluble (WIS) fractions of DEP were isolated, and intratracheal instillation was used for DEP, WS and WIS exposure. The phosphate buffer saline (PBS) exposure group was set as the control group. After 24 h exposure, the mice were sacrificed for blood routine, coagulation function and bleeding time examinations to estimate the acute effect of DEP, WS and WIS exposure on the blood coagulation function. In our results, no statistically significant difference in weight of body, brain and lung was observed in different exposure groups. While several core indexes in blood coagulation like bleeding time (BT), fibrinogen (FIB), activated partial thromboplastin time (APTT) and prothrombin time (PT) altered or showed a lower tendency after DEP, WS and WIS exposure. For example, BT was lower In WIS exposure group (211.00 s) compared with PBS exposure group (238.50 s) (p < 0.01), and FIB was lower in WS exposure group (233.00 g/L) compared with PBS exposure group (249.50 g/L) (p < 0.05). Additionally, systemic inflammation-related indexes like white blood cell count (WBC), neutrophil count (NEUT), lymphocyte count (LYMPH) altered after DEP, WS and WIS exposure. In conclusion, DEP, WS and WIS fractions exposure could result in the hypercoagulable state of blood in mice. The noteworthy effects of WS and WIS fractions exposure on blood coagulation function deserve further investigation of the potential mechanism.

In utero exposure to diesel exhaust particles, but not silica, alters post-natal immune development and function

Our understanding of the impact of in utero exposure to PM on post-natal immune function and the subsequent response to PM exposure is limited. Similarly, very few studies have considered the effect of exposure to PM from different sources. Thus, the aim of this study was to examine how in utero exposure to PM from different sources effects the post-natal response to pro-inflammatory and immune stimuli. C56BL/6J pregnant mice were exposed intranasally on gestational day (E)7.5, E12.5 and E17.5-50 μg of diesel exhaust particles (DEP), silica or saline. At 4-weeks post-natal age, sub-groups of male and female mice were exposed intranasally to 50 μg of DEP or saline. Lung inflammatory responses were assessed 6 h later by quantifying inflammatory cells and cytokine production (MCP-1, MIP-2, IL-6). In separate groups of mice, the spleen was harvested to quantify B and T cell populations. Splenocytes were isolated and exposed to lipopolysaccharide or poly I:C for assessment of cytokine production. Exposure to DEP in utero decreased %CD1d^highCD5+ B cells in female mice and IFN-γ production by splenocytes in both sexes. Male mice had elevations in macrophage and lymphocyte numbers in response to DEP whereas female mice only had elevated IL-6, MCP-1 and MIP-2 levels. In utero exposure to silica had no effect on these measures. These data suggest that in utero exposure to PM alters immune development and post-natal immune function. This response is dependent on the source of PM, which has implications for understanding the community health effects of exposure to air pollution.