Abstract：
Exposure to particulate matter (PM10) can induce respiratory diseases that are closely related to bronchial hyperresponsiveness. However, the involved mechanism remains to be fully elucidated. This study aimed to demonstrate the effects of PM10 on the acetylcholine muscarinic 3 receptor (CHRM3) expression and the role of the ERK1/2 pathway in rat bronchial smooth muscle. A whole-body PM10 exposure system was used to stimulate bronchial hyperresponsiveness in rats for 2 and 4 months, accompanied by MEK1/2 inhibitor U0126 injection. The whole-body plethysmography system and myography were used to detect the pulmonary and bronchoconstrictor function, respectively. The mRNA and protein levels were determined by Western blotting, qPCR, and immunofluorescence. Enzyme-linked immunosorbent assay was used to detect the inflammatory cytokines. Compared with the filtered air group, 4 months of PM10 exposure significantly increased CHRM3-mediated pulmonary function and bronchial constriction, elevated CHRM3 mRNA and protein expression levels on bronchial smooth muscle, then induced bronchial hyperreactivity. Additionally, 4 months of PM10 exposure caused an increase in ERK1/2 phosphorylation and increased the secretion of inflammatory factors in bronchoalveolar lavage fluid. Treatment with the MEK1/2 inhibitor, U0126 inhibited the PM10 exposure-induced phosphorylation of the ERK1/2 pathway, thereby reducing the PM10 exposure-induced upregulation of CHRM3 in bronchial smooth muscle and CHRM3-mediated bronchoconstriction. U0126 could rescue PM10 exposure-induced pathological changes in the bronchus. In conclusion, PM10 exposure can induce bronchial hyperresponsiveness in rats by upregulating CHRM3, and the ERK1/2 pathway may be involved in this process. These findings could reveal a potential therapeutic target for air pollution induced respiratory diseases.
摘要：
暴露于颗粒物（PM10）可诱发与支气管高反应性密切相关的呼吸系统疾病。然而,所涉及的机制仍有待充分阐明。本研究旨在证明PM10对大鼠支气管平滑肌乙酰胆碱毒蕈碱3受体（CHRM3）表达的影响以及ERK1/2通路的作用。使用全身PM10暴露系统刺激大鼠支气管高反应性，持续2个月和4个月，伴随MEK1/2抑制剂U0126注射。全身体积描记系统和肌电图用于检测肺和支气管收缩功能，分别。通过蛋白质印迹法测定mRNA和蛋白质水平，qPCR,和免疫荧光。酶联免疫吸附法检测炎性细胞因子。与过滤空气组相比，4个月的PM10暴露显着增加CHRM3介导的肺功能和支气管收缩，支气管平滑肌CHRM3mRNA和蛋白表达水平升高，然后诱导支气管高反应性。此外,4个月的PM10暴露导致支气管肺泡灌洗液中ERK1/2磷酸化增加，炎症因子的分泌增加。用MEK1/2抑制剂治疗，U0126抑制PM10暴露诱导的ERK1/2途径的磷酸化，从而减少了PM10暴露诱导的支气管平滑肌中CHRM3的上调和CHRM3介导的支气管收缩。U0126可以挽救PM10暴露引起的支气管病理变化。总之,PM10暴露可通过上调CHRM3诱导大鼠支气管高反应性，ERK1/2通路可能参与这一过程。这些发现可以揭示空气污染引起的呼吸系统疾病的潜在治疗目标。
