Department of Pathology, North China Coal Medical College, No. 57 South Construction Road, Tangshan City, Hebei Province, China.
Life Sci. 2010 Aug 14;87(7-8):232-9. doi: 10.1016/j.lfs.2010.06.016. Epub 2010 Jul 16.
We previously reported that tetrapeptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) inhibited pulmonary inflammation and fibrosis in SiO(2)-induced silicosis. This study aimed to explore the precise mechanism involved.
Rats were divided into 3 groups: 1) sham (saline), 2) silicosis+vehicle, and 3) silicosis+Ac-SDKP [800 microg/(kgd)]. SiO(2) particles or saline were administered by tracheal instillation and Ac-SDKP or vehicle (saline) via a mini-osmotic pump planted into the abdominal cavity 48 h before instillation. Animals were observed for 4 weeks. Silicotic nodule fraction (SNF) and macrophage infiltration (ED-1 positive cells) were measured by hematoxylin and eosin (H.E.) and immunohistochemical staining respectively. Collagen I and III, transforming growth factor-beta1 (TGF-beta1) proteins and monocyte chemotactic protein-1 (MCP-1) mRNA were detected by Western Blot (WB) and real-time RT-PCR respectively. In vitro, pulmonary fibroblasts were stimulated by TGF-beta1 (5 microg/ml) with or without Ac-SDKP. Phosphorylated c-Jun N-terminal Kinase (p-JNK) was detected by WB and p-JNK nuclear translocation by confocal analysis.
SiO(2) significantly increased the SNF, collagen I and III proteins, TGF-beta1, MCP-1 mRNA and macrophage infiltration. All these pathological changes were inhibited by Ac-SDKP. TGF-beta1 resulted in fibroblast proliferation, increased expression of collagen I and III proteins, p-JNK and its subsequent nuclear translocation. Addition of Ac-SDKP markedly suppressed these changes.
These data indicate that the anti-fibrotic effect of Ac-SDKP in silicosis is mediated by inhibiting chronic inflammation, TGF-beta1 production, and TGF-beta1-induced pulmonary fibroblast proliferation and collagen synthesis.
我们之前报道过四肽 N-乙酰丝氨酰-天冬氨酰-赖氨酰-脯氨酸（Ac-SDKP）可抑制二氧化硅（SiO2）诱导矽肺中的肺炎症和纤维化。本研究旨在探讨其确切的作用机制。
将大鼠分为 3 组：1）假手术（生理盐水）组、2）矽肺+载体组和 3）矽肺+Ac-SDKP [800μg/（kg·d）]组。SiO2 颗粒或生理盐水通过气管内滴注，Ac-SDKP 或载体（生理盐水）通过腹腔内植入的微型渗透泵在滴注前 48 小时给药。观察动物 4 周。通过苏木精和伊红（H.E.）染色和免疫组化染色分别测量矽性结节分数（SNF）和巨噬细胞浸润（ED-1 阳性细胞）。通过 Western blot（WB）和实时 RT-PCR 分别检测胶原 I 和 III、转化生长因子-β1（TGF-β1）蛋白和单核细胞趋化蛋白-1（MCP-1）mRNA。体外，用 TGF-β1（5μg/ml）刺激肺成纤维细胞，同时或不添加 Ac-SDKP。通过 WB 检测磷酸化 c-Jun N-末端激酶（p-JNK），通过共聚焦分析检测 p-JNK 核转位。
SiO2 显著增加了 SNF、胶原 I 和 III 蛋白、TGF-β1、MCP-1mRNA 和巨噬细胞浸润。所有这些病理变化均被 Ac-SDKP 抑制。TGF-β1 导致成纤维细胞增殖，增加胶原 I 和 III 蛋白、p-JNK 及其随后的核转位表达。添加 Ac-SDKP 可显著抑制这些变化。
这些数据表明，Ac-SDKP 在矽肺中的抗纤维化作用是通过抑制慢性炎症、TGF-β1 产生以及 TGF-β1 诱导的肺成纤维细胞增殖和胶原合成来介导的。
