胆红素通过影响巨噬细胞的胞葬作用减轻吸烟暴露所致肺组织损伤

Bilirubin mitigates lung tissue damage due to smoking exposure by influencing macrophage efferocytosis

为探究胆红素通过影响巨噬细胞胞葬作用对吸烟暴露大鼠肺组织损伤的保护作用及机制,随机将6周龄健康雄性Wistar大鼠分为6组,每组10只,建立12周烟熏动物模型以及12周烟熏+4周戒烟的16周模型,并在每天烟熏前给予治疗组外源性胆红素干预。建模后采集样本行肺组织细胞学和病理学分析,ELISA检测支气管肺泡灌洗液中细胞因子表达水平,FACS分析具有胞葬活性的巨噬细胞百分比。经过12周的烟熏造模过程成功建立了大鼠肺气肿模型,香烟烟雾暴露可增加肺组织中炎症细胞的浸润、炎性细胞因子的水平及肺组织损伤(均P<0.05),影响巨噬细胞的极化和胞葬作用(均P<0.05),使M2型抑炎巨噬细胞数减少而M1型致炎巨噬细胞数增多;而戒烟4周后肺组织的炎症反应和损伤虽有一定程度的减轻(均P<0.05),但仍存在。给予外源性胆红素干预后可减轻烟熏导致的炎症细胞浸润、部分炎性细胞因子分泌及肺组织损伤(均P<0.05),可能与其能影响巨噬细胞的极化状态和胞葬作用(均P<0.05)有关。由此,胆红素可通过抗炎作用和免疫调节等多种机制减轻香烟烟雾暴露所致肺组织损伤。该研究发现胆红素对巨噬细胞极化状态和胞葬作用的影响是对胆红素功能理论的补充,为胆红素应用于防治香烟烟雾暴露相关的炎症性疾病提供了理论依据和新思路。

The aim of this study is to investigate the protective effect and the underlying mechanism of bilirubin on lung tissue damage via macrophage efferocytosis in smoking-exposed rats.Six-week-old healthy male Wistar rats were randomly divided into six groups of ten.The rat smoking model was established by twelve weeks'smoking.A smoking withdrawal model was established by twelve weeks of smoking followed by four weeks of withdrawal.Exogenous bilirubin was given in treatment groups before daily smoking exposure.Specimens were retained for pulmonary histology and histopathological analysis.ELISA was used for the detection of cytokine levels in bronchoalveolar lavage fluid(BALF)and FACS for the percentage of macrophages with efferocytosis.The results showed that after twelve weeks of smoking exposure,the emphysema model was successfully established,and the cigarette smoke exposure significantly increased the infiltration of inflammatory cells,the levels of inflammatory cytokines,and lung tissue damage(all P<0.05).In addition,smoking also affected macrophage polarization towards the M1 type.Smoking also affected macrophage efferocytosis(all P<0.05).The inflammatory response and damage of lung tissue after four weeks of smoking withdrawal were moderately alleviated(all P<0.05),but still existed.Exogenous bilirubin intervention reduced the infiltration of inflammatory cells,the secretions of partial inflammatory cytokines,and relieved lung tissue damage(all P<0.05),which might correlate to its regulation on the macrophage polarization state and efferocytosis(all P<0.05).In conclusion,bilirubin may alleviate lung tissue damage caused by cigarette smoke exposure via multiple mechanisms such as anti-inflammatory,antioxidant,and immunomodulatory.The discovery of the effect of bilirubin on the polarization state and efferocytosis of macrophages is complementary to the known functions of bilirubin and provides the theoretical basis and new ideas for the application of bilirubin to treat cigarette smoke-related inflammatory diseases.