Background: MicroRNAs (miRNAs) are a key factor in epigenetic regulation of gene expression, but miRNA responses to fine particulate matter (PM2.5) air pollution and their potential contribution to cardiovascular effects of PM2.5 are unknown. Objective: We explored the potential influence of PM2.5 on the expression of selected cytokines relevant to systemic inflammation, coagulation, and vasoconstriction, and on miRNAs that may regulate their expression. Methods: We designed a double-blind, randomized crossover study in which true and sham air purifiers were used to expose 55 healthy young adult students in Shanghai, China, to reduced or ambient levels of indoor PM2.5 during two-week periods, and we measured the expression (mRNA and protein) of 10 serum cytokines, and miRNAs that target them, after each intervention period. We used linear mixed-effect models to estimate associations of the intervention, and time-weighted personal PM2.5 exposures, with the cytokines, mRNA, and miRNAs; we also explored pote...

Objective: To examine temperature in relation to stroke mortality in a multicity time series study in China. Methods: We obtained data on daily temperature and mortality from 8 large cities in China. We used quasi-Poisson generalized additive models and distributed lag nonlinear models to estimate the accumulative effects of temperature on stroke mortality across multiple days, adjusting for long-term and seasonal trends, day of the week, air pollution, and relative humidity. We applied the Bayesian hierarchical model to pool city-specific effect estimates. Results: Both cold and hot temperatures were associated with increased risk of stroke mortality. The potential effect of cold temperature might last more than 2 weeks. The pooled relative risks of extreme cold (first percentile of temperature) and cold (10th percentile of temperature) temperatures over lags 0–14 days were 1.39 (95% posterior intervals [PI] 1.18–1.64) and 1.11 (95% PI 1.06–1.17), compared with the 25th percentile of temperature. In contrast, the effect of hot temperature was more immediate. The relative risks of stroke mortality over lags 0–3 days were 1.06 (95% PI 1.02–1.10) for extreme hot temperature (99th percentile of temperature) and 1.14 (95% PI 1.05–1.24) for hot temperature (90th percentile of temperature), compared with the 75th percentile of temperature. Conclusions: This study showed that both cold and hot temperatures were associated with increased risk of stroke mortality in China. Our findings may have important implications for stroke prevention in China.

Short-term associations between size-fractionated particulate air pollution and circulating biomarkers are not well established, especially in developing countries with high levels of particulate matter (PM). We designed a panel study involving 34 healthy young adults to evaluate acute effects of size-fractionated PM on 13 circulating biomarkers of inflammation, coagulation, and vasoconstriction. We measured real-time, size-fractionated number concentrations of PM (aerodynamic diameters from 0.25 to 10 μm, mass concentrations of PM < 10 μm) over four follow-up measurements. The short-term associations between size-fractionated PM and biomarkers were assessed using linear mixed effect models. We found positive associations between short-term exposure to PM and 10 biomarkers. PM with smaller size had stronger associations. The size fractions with the strongest associations were 0.25-0.40 μm for number concentrations and <1 μm for mass concentrations. For example, an interquartile range increase in 24-hour-average number concentrations of PM0.25-0.40 was associated with a 7%-32% increase in biomarkers of inflammation, 34%-68% of blood coagulation, and 45% of vasoconstriction. Similar estimates were found for mass concentrations of PM1. Furthermore, our results demonstrated an apparent acute effect on circulating biomarkers, even 2 hours after exposure. The effects were strongest within the first 12-24 hours, and effects on inflammation occurred more quickly than on coagulation and vasoconstriction. Our results provided potentially vital insights into the size and temporal characteristics of PM that could modify subclinical cardiovascular effects. These findings may have implications on disease prevention and environmental regulation in China.