大气颗粒物生物化学组分的促炎症效应研究进展

Pro-inflammatory effects of airborne particulate matters in relation to biological and chemical composition

大气污染物暴露与呼吸系统疾病、心脑血管疾病、神经退化性疾病之间的关系,已被大量流行病学和基于动物、细胞的毒理学所确认.促炎症效应是污染物尤其是颗粒物影响健康的重要机制之一.然而,颗粒物通过何种过程引起炎症效应,哪些组分是促炎症效应的关键因子,依然不清楚.多环芳烃、重金属等化学组分对颗粒物促炎症效应的贡献已有大量报道.细菌、真菌、病毒、花粉等微生物及其碎片构成的生物气溶胶,基于其配体特征,在激活免疫系统引起炎症反应方面有独有的"优势".但由于对生物气溶胶进行在线监测分析有较大困难,导致缺乏对其种类、浓度等特征的全面了解,从而限制了对颗粒物中生物组分促炎症效应的认识.本文简单总结了大气颗粒物的促炎症效应,从炎症效应机制、不同组分的炎症效应及生物化学组分协同作用3个方面进行了归纳,并提出了开展大气污染健康效应研究的几点新的研究思路和方向建议.

Exposure to air pollution has been linked to various adverse health effects, including respiratory diseases, cardiovascular diseases as well as neurological diseases by numerous epidemiological and toxicological studies. Pro-inflammatory effect is suggested to be one of the major mechanisms regarding the health risks posed by pollutants, especially particulate matter（PM）. Although the impacts of particle sources and compositions on the discrepancy of elicited inflammation have gained growing attentions, the key determinants remain unclear. Chemical components, i.e., sulfates, nitrates, trace metals, polycyclic aromatic hydrocarbons, have been most closely associated with inflammatory effects. Bioaerosols（short for biological aerosols） including bacteria, fungi, virus, pollen as well as their debris, feature the unique ＂ligand＂ properties in activating the receptors of the innate immune cell and evoking inflammation. Nonetheless, with the challenge of identification and characterization of bioaerosols in a real-time manner remaining, there were still limited studies discussing the inflammation induced by bioaerosols. We present a short summary of the pro-inflammatory effects of airborne particles including bioaerosols and chemical composition. Studies on the indispensable role of oxidative stress in promoting cellular inflammatory cytokine production were summarized. Specifically, chemical compositions of PM could affect cellular inflammatory responses via affecting various phosphatase, kinase（e.g., mitogen-activated protein kinase, tyrosine phosphatase）, as well as the transcription factors（e.g. NF-κB, Nrf2）. Moreover, the role of the PM-borne biological components, e.g. lipopolysaccharide（LPS）, was also summarized. Whereas, neither chemical components nor biological components could fully elucidate the PM-induced inflammation. Notably, synergistic effects between PM and allergens were largely discussed with respect to the high prevalence and severity of allergic diseases. Particularly, PM could function as ＂adjuvant＂ in elevating the allergic potential of allergens. By taking advantage of this adjuvant function concept, we summarized the past studies on the synergistic effects between chemical and microbial components of particles. Several suggestions are offered for future researches on air pollution-associated health effects：（1） characterize bioaerosols under various weather conditions, aiming to figure out the effects of air pollutants on the airborne microbes;（2） investigate the effects of the interplay between microbial components（e.g., LPS, 1,3-β-glucan） and chemical pollutants（i.e., nitrates, sulfates, organic carbon, elemental carbon, secondary organic aerosols, trace metals, O3, NOx, and SO2） on the development of individual inflammation;（3） study the dynamic change of respiratory microbiota, especially under distinct pollution levels, which might give a new clue to uncover the air pollutants-related adverse health effects.