Investigation of Inhibition of Inflammatory Cell Migration into Lung Tissue by Ammeriolation of Cell Adhesion on Vascular Endothelial Cell

背景和目的：尽管间质性肺炎和肺纤维化的发病机制尚不清楚，但已有报道称炎性细胞，特别是中性粒细胞及其产生的损伤性物质在间质性肺炎和随后的纤维化的发展过程中起着重要作用。红霉素和其他14元环大环内酯类化合物(14-MRMLs)已被报道通过抗中性粒细胞和其他几种抗炎机制来改善弥漫性泛细支气管炎(DPB)患者的生存。本研究旨在观察14-MRMLs对博莱霉素(BLM)诱导的小鼠急性肺损伤及继发性纤维化模型的影响。注射博莱曼28d后，左肺组织出现纤维化灶，右肺组织羟脯氨酸(HOP)含量进行化学分析。14-MRMLs的抑制作用为…对照组(仅生理盐水)、未治疗组(仅BLM)和治疗组(BLM14-MRMLs)之间的总体比较更有说服力。分别于术后0~13d检测肺组织中黏附分子(E-选择素、P-选择素、ICAM-1、VCAM-1)的表达，并检测肺泡灌洗液(BALF)中细胞的数量。结果：红霉素等14-MRMLs均能抑制BLM诱导的ICR小鼠肺纤维化，尤其是14-MRMLs预处理组，肺组织HOP含量也明显降低。BALF中中性粒细胞数量显著增加，在给药后第1天和第9天(6~11天)出现两个高峰。14-MRMLs可显著抑制中性粒细胞进入肺泡的两个高峰。黏附分子(E-选择素、P-选择素、ICAM-1、VCAM-1)mRNA表达的变化与白细胞向腔隙内迁移有关。14-MRMLs明显抑制VCAM-1mRNA的表达，并有减弱ICAM-1mRNA表达的趋势，但对E-选择素和P-选择素mRNAs的表达均无抑制作用。结论：14-MRMLs可抑制炎症细胞向肺泡内的迁移，尤其是中性粒细胞和巨噬细胞的迁移，从而抑制肺损伤和随后的纤维化。14-MRMLs明显抑制BLM致肺损伤早期VCAM-1mRNA的表达，这可能是其抑制中性粒细胞和巨噬细胞向肺内迁移的机制之一。这可能是14-MRMLs抗炎和随后的纤维化作用的一个有效机制。提示预防性应用14-MRMLs可有效预防间质性肺炎和急性肺损伤的急性加重。较少

Background and objective : Although the pathogeneses of interstitial pneumonia and pulmonary fibrosis are not well understood, it has been reported that inflammatory cells, especially neutrophils, and injurious substances produced by them play important roles in the progression of interstitial pneumonia and subsequent fibrosis. Erythromycin and other 14-membered ring macrolides (14-MRMLs) have been reported to improve the survival of patients with diffuse panbronchiolitis (DPB) by anti-neutrophil and several other anti-inflammatory mechanisms. The present study was undertaken to investigate the effete of 14-MRMLs on an experimental model of bleomycin (BLM)-induced acute lung injury and subsequent fibrosis in mice.Methods : BLM was administered intravenously to ICR mice. At 28 days after BLM injection, fibrotic foci were histologically observed in left lung tissues, and hydroxyproline (HOP) content in right lung tissues was chemically analyzed. The inhibitory effects of 14-MRMLs were as … More sessed by overall comparison between control (NS alone), untreated (BLM alone), and treated (BLM + 14-MRMLs) groups. For evaluation of early-phase inflammation, cell populations in bronchoalveolar lavage fluid (BALF) and induction of mRNA of adhesion molecules (E-selectin, P-selectin, ICAM-1, VCAM-1) in lung tissues were examined at 0 to 13 days after BLM. These parameters were also compared wife those for the control (NS alone), 14-MRML-unteated (BLM alone) and -pre-treated (BLM + pre14-MRMLs) groups.Results : BLM-induced pulmonary fibrosis was inhibited by erythromycin and other 14-MRMLs on day 28 after BLM injection in ICR mice, especially those pre-treated with 14-MRMLs, HOP content in lung tissues was also decreased in the l4-MRML-pre-1reated groups. The number of neutrophils in BALF significantly increased, with two peaks at 1 and 9 (from 6 to 11) days after BLM administration. 14-MRMLs significantly inhibited both peaks of neutrophil infiltration into the airspace. Changes in mRNA expression of adhesion molecules (E-selectin, P-selectin, ICAM-1, VCAM-1) were associated with leucocyte migration into the airspace. 14-MRMLs clearly inhibited the induction of VCAM-1 mRNA and tended to attenuate that of ICAM-1 mRNA, but inhibited the induction of neither E-selectin mRNA nor P-selectin mRNA.Conclusion : These findings indicate that attenuation of inflammatory cell migration into the airspace by 14-MRMLs, especially of neutrophils and macrophages, resulted in inhibition of lung injury and subsequent fibrosis. 14-MRMLs clearly attenuated the expression of VCAM- 1 mRNA during the early phase of BLM-induced lung injury, and this might be one mechanism of inhibition of neutrophil and macrophage migration into the airspace by 14-MRMLs. This might be one potent mechanism of the anti-inflammatory and subsequent fibrotic effects of 14-MRMLs. These findings suggest that prophylactic administration of 14-MRMLs may be clinically efficacious in preventing acute exacerbation of interstitial pneumonia and acute lung injury. Less