Time- and Dose-Resolved Proteome of PM2.5-Exposure-Induced Lung Injury and Repair in Rats

Integrative proteomics and metabolomics analysis of non-observable acute effect level PM2.5 induced accumulative effects in AC16 cells

Chronic exposure to very low ambient PM2.5 has been linked to cardiovascular risks in epidemiological observation, which also brought doubts on its safety threshold. In this study, we approached this question by chronic exposure of AC16 to the non-observable acute effect level (NOAEL) PM2.5 5 μg/mL and its positive reference 50 μg/mL, respectively. The doses were respectively defined on the cell viabilities >95% (p = 0.354) and >90% (p = 0.004) when treated acutely (24 h). To mimic the long-term exposure, AC16 was cultured from the 1st to 30th generations and treated with PM2.5 24 h in every three generations. The integration of proteomic and metabolomic analysis was applied, and 212 proteins and 172 metabolites were significantly altered during the experiments. The NOAEL PM2.5 induced both dose- and time-dependent disruption, which showed the dynamic cellular proteomic response and oxidation accumulation, the main metabolomics changes were ribonucleotide, amino acid, and lipid metabolism that have involved in stressed gene expression, and starving for energy metabolism and lipid oxidation. In summary, these pathways interacted with the monotonically increasing oxidative stress and led to the accumulated damage in AC16 and implied that the safe threshold of PM2.5 may be non-existent when a long-term exposure occurred.

Long-Term Exposure to PM2.5 and Mortality: A Cohort Study in China

We investigated the association of long-term exposure to atmospheric PM2.5 with non-accidental and cause-specific mortality in Yinzhou, China. From July 2015 to January 2018, a total of 29,564 individuals aged ≥ 40 years in Yinzhou were recruited for a prospective cohort study. We used the Cox proportional-hazards model to analyze the relationship of the 2-year average concentration of PM2.5 prior to the baseline with non-accidental and cause-specific mortality. The median PM2.5 concentration was 36.51 μg/m3 (range: 25.57-45.40 μg/m3). In model 4, the hazard ratios per 10 μg/m3 increment in PM2.5 were 1.25 (95%CI: 1.04-1.50) for non-accidental mortality and 1.38 (95%CI:1.02-1.86) for cardiovascular disease mortality. We observed no associations between PM2.5 and deaths from respiratory disease or cancer. In the subgroup analysis, interactions were observed between PM2.5 and age, as well as preventive measures on hazy days. The observed association between long-term exposure to atmospheric PM2.5 at a relatively moderate concentration and the risk of non-accidental and cardiovascular disease mortality among middle-aged and elderly Chinese adults could provide evidence for government decision-makers to revise environmental policies towards a more stringent standard.

The cytotoxicity of PM2.5 and its effect on the secretome of normal human bronchial epithelial cells

Exposure to airborne fine particulate matter (PM_2.5) induced various adverse health effects, such as metabolic syndrome, systemic inflammation, and respiratory disease. Many works have studied the effects of PM_2.5 exposure on cells through intracellular proteomics analyses. However, changes of the extracellular proteome under PM_2.5 exposure and its correlation with PM_2.5-induced cytotoxicity still remain unclear. Herein, the cytotoxicity of PM_2.5 on normal human bronchial epithelia cells (BEAS-2B cells) was evaluated, and the secretome profile of BEAS-2B cells before and after PM_2.5 exposure was investigated. A total of 83 proteins (58 upregulated and 25 downregulated) were differentially expressed in extracellular space after PM_2.5 treatment. Notably, we found that PM_2.5 promoted the release of several pro-apoptotic factors and induced dysregulated secretion of extracellular matrix (ECM) constituents, showing that the abnormal extracellular environment attributed to PM_2.5-induced cell damage. This study provided a secretome data for the deep understanding of the molecular mechanism underlying PM_2.5-caused human bronchial epithelia cell damage.

Combined multi-omics analysis reveals oil mist particulate matter-induced lung injury in rats: Pathological damage, proteomics, metabolic disturbances, and lung dysbiosis

Oil mist particulate matter (OMPM) causes acute and chronic diseases and exacerbations. Owing to the characteristics of poor ventilation, high oil mist concentration, and a relatively closed working environment, the existence of OMPM in the cabin is inevitable, and its impact on the health of occupations on ships cannot be ignored. However, compared with several studies that summarized the health effects of OMPM from traditional sources, few studies have focused on the occupational exposure risk of OMPM from oil pollution sources in ships. In this study, we collected OMPM from oil pollution in cabins and assessed the exposure to OMPM from oil pollution and the corresponding health risks through acute exposure experiments in rats. OMPM exposure induces protein regulation in the extracellular matrix and immune responses, leading to severe inflammatory responses. The abundance and composition of the lung microbial community changed significantly. It interferes with the lung metabolite levels. However, more research is needed to fully understand the extent of health risks associated with OMPM exposure. Further research on vulnerable groups exposed to OMPM from ships is needed to inform public health interventions.

Mechanism of biochanin A alleviating PM2.5-induced oxidative damage based on an XRCC1 knockout BEAS-2B cell model

PM_2.5 induces oxidative/antioxidant system imbalance and excessive release of reactive oxygen species (ROS) and produces toxic effects and irreversible damage to the genetic material including chromosomes and DNA. Biochanin A (BCA), an isoflavone with strong antioxidant activity, effectively intervenes against PM_2.5-induced oxidative damage. The X-ray repair cross-complementary protein 1 (XRCC1)/BER pathway involves DNA damage repair caused by oxidative stress. This paper aims to explore the mechanism of BCA alleviating oxidative DNA damage caused by PM_2.5 by establishing the in vitro cell model based on CRISPR/Cas9 technology and combining it with mechanism pathway research. The results showed that PM_2.5 exposure inhibited the expression of BER and NER pathway proteins and induced the overexpression of ERCC1. BCA showed an effective intervention in the toxicity of PM_2.5 in normal cells, rather than XRCC1 knock-out cells. This laid a foundation for further exploring the key role of XRCC1 in PM_2.5-caused oxidative damage and the BER/DNA damage repair pathway.

Accumulated oxidative stress risk in HUVECs by chronic exposure to non-observable acute effect levels of PM2.5

Few studies have reported the accumulation of non-observable acute effect (NOAE) of PM_2.5, especially exposure to the NOAE doses (NOAEDs) of PM_2.5 in chronic way. To address this issue, HUVECs were cultured from the 1st to 30th generations (G1 to G30) and treated by the NOAED PM_2.5 once every three passages. The generational changes of oxidative damage markers, inflammatory factors, and cell adhesion molecules (CAMs) were monitored in HUVECs at G6, G12, G18, G24, and G30, and proteomes at G18 and G30, respectively. The oxidative damages monotonically accumulated with exposure time elongation and PM_2.5 dose increases. Similar to the oxidative trends, VCAM1 and ICAM1 significantly and dose-dependently increased at G30. However, many inflammatory factors altered with complex patterns to respond the NOAEDs' PM_2.5. Proteomic results demonstrated most proteins expressed stably, and the generational proteome alterations were more apparent than the NOAEDs' PM_2.5 induced ones. The PM_2.5-related proteins varied much, but only few can cross the doses and generations. These observations suggested that the proteins changed holistically rather than individually. In summary, SOD1, SUMO2, and H3F3A may initiate HUVESs responses to PM_2.5, and then broadcast and accumulate the NOAE via DNA repair, immune response, and glycolysis.

Association of exposure to fine particulate matter wave over the preconception and pregnancy periods with adverse birth outcomes: Results from the project ELEFANT

BACKGROUND

No study has explored the effects of sustained maternal exposure to high-level ambient fine particulate matter (PM_2.5) within a short period, i.e., PM_2.5 wave, on adverse birth outcomes, though increasing epidemiological studies demonstrated that exposure to single days of high ambient PM_2.5 could increase risks of adverse birth outcomes. In this study, we aim to evaluate associations of maternal PM_2.5 wave exposure around pregnancy with preterm birth (PTB), small for gestational age (SGA), and large for gestational age (LGA).

METHODS

Totally 10,916 singleton pregnant women from all 16 districts in Tianjin, China, and their followed-up birth outcomes were included in this study. We defined PM_2.5 wave as at least 2 consecutive days with daily average PM_2.5 concentration exceeding 75 μg/m³, and 90th, 92.5th, 95th, 97.5th, 99th percentiles of PM_2.5 distribution during the study period in Tianjin, respectively. Cox proportional hazard model was applied to evaluate the durational effects of PM_2.5 wave during each exposure window on PTB, SGA, and LGA after adjusting for potential confounders.

RESULTS

Exposure to PM_2.5 wave over the preconception and pregnancy periods was associated with increased risks of adverse birth outcomes. For PTB, the strongest association was found during the first trimester when PM_2.5 wave was defined as at least 4 consecutive days with daily average PM_2.5 concentration >90th (HR, 10.46; 95% CI, 6.23-17.54); and for SGA (HR, 6.23; 95% CI, 3.34-11.64) and LGA (HR, 4.70; 95% CI, 3.35-6.59), the strongest associations both were found when PM_2.5 wave was defined as at least 2 consecutive days with daily average PM_2.5 concentration >99th. Additionally, the risks of adverse birth outcomes generally increased at higher PM_2.5 thresholds or longer durations of PM_2.5 wave.

CONCLUSION

Prolonged exposure to high-level PM_2.5 over preconception and pregnancy periods was associated with increasing risks of PTB, SGA and LGA.