Bonniaud Philippe, Margetts Peter J, Ask Kjetil, Flanders Kathy, Gauldie Jack, Kolb Martin
Department of Pathology and Molecular Medicine, Center for Gene Therapeutics, McMaster University, Hamilton, Ontario, Canada.
J Immunol. 2005 Oct 15;175(8):5390-5. doi: 10.4049/jimmunol.175.8.5390.
Transient adenovirus-mediated gene transfer of IL-1beta (AdIL-1beta), a proinflammatory cytokine, induces marked inflammation and severe and progressive fibrosis in rat lungs. This is associated with an increase in TGF-beta1 concentration in bronchoalveolar lavage (BAL) fluid. TGF-beta1 is a key cytokine in the process of fibrogenesis, using intracellular signaling pathways involving Smad2 and Smad3. In this study we investigate whether inflammation induced by IL-1beta is able to independently induce lung fibrosis in mice deficient in the Smad3 gene. Seven days after AdIL-1beta administration, similar levels of IL-1beta transgene are seen in BAL in both wild-type (WT) and knockout (KO) mice, and BAL cell profiles demonstrated a similar marked neutrophilic inflammation. Phospho-Smad2 staining was positive in areas of inflammation in both WT and KO mice at day 7. By day 35 after transient IL-1beta expression, WT mice showed marked fibrosis in peribronchial areas, quantified by picrosirius red staining and morphometry. However, there was no evidence of fibrosis or collagen accumulation in IL-1beta-treated KO mice, and peribronchial areas were not different from KO mice treated with the control adenovector. TGF-beta1 and phospho-Smad2 were strongly positive at day 35 in fibrotic areas observed in WT mice, but no such staining was detectable in KO mice. The IL-1beta-induced chronic fibrotic response in mouse lungs is dependent on Smad3. KO and WT animals demonstrated a similar inflammatory response to overexpression of IL-1beta indicating that inflammation must link to the Smad3 pathway, likely through TGF-beta, to induce progressive fibrosis.
促炎细胞因子白细胞介素-1β（AdIL-1β）通过腺病毒介导的短暂基因转移可在大鼠肺中引发显著炎症以及严重且进行性的纤维化。这与支气管肺泡灌洗（BAL）液中转化生长因子-β1（TGF-β1）浓度升高有关。TGF-β1是纤维生成过程中的关键细胞因子，它利用涉及Smad2和Smad3的细胞内信号通路。在本研究中，我们探究了IL-1β诱导的炎症是否能够在Smad3基因缺陷的小鼠中独立诱导肺纤维化。给予AdIL-1β七天后，野生型（WT）和基因敲除（KO）小鼠的BAL中可见相似水平的IL-1β转基因，并且BAL细胞图谱显示出相似的显著嗜中性粒细胞炎症。在第7天，WT和KO小鼠炎症区域的磷酸化Smad2染色均为阳性。在短暂表达IL-1β后第35天，WT小鼠支气管周围区域出现显著纤维化，通过天狼星红染色和形态计量学进行定量分析。然而，经IL-1β处理的KO小鼠没有纤维化或胶原积累的证据，并且支气管周围区域与用对照腺病毒载体处理的KO小鼠没有差异。在WT小鼠观察到的纤维化区域中，TGF-β1和磷酸化Smad2在第35天呈强阳性，但在KO小鼠中未检测到此类染色。小鼠肺中IL-1β诱导的慢性纤维化反应依赖于Smad3。KO和WT动物对IL-1β过表达表现出相似的炎症反应，表明炎症必须通过TGF-β与Smad3途径相连，以诱导进行性纤维化。
