LTB4/BLT1轴调控肌成纤维细胞形成参与系统性硬化症发病的作用与机制

Leukotriene B4 (LTB4), a lipid mediator of inflammation, plays a key role in the autoimmune and inflammatory diseases via its high affinity receptor BLT1. Myofibroblast is recognized to be critical in the progression of systemic sclerosis (SSc), but the mechanism is still unknown. In our previous study, LTB4 was observed to be up-regulated in the serum of SSc patients. The level of BLT1 was also increased in the skin tissues of SSc mice induced by bleomycin (BLM). BLT1-/- mice did not manifest the phenotype of SSc following the BLM treatment. And the reduction of α-SMA+ myofibroblasts was also found in the skin and lung tissues of BLT1-/- mice following the administration of BLM, compared with those in wide type mice. These findings indicated LTB4/BLT1 axis participated in the progression of SSc, and LTB4 may play its regulatory role via BLT1 in myofibroblast formation. We have already established a modified SSc mouse model by delivering BLM via an osmotic mini-pump. We plan to use BLT1-/- mice and BLT1 specific inhibitor to reveal the contribution of LTB4/BLT1 axis to the progression of SSc. Also we will study fibroblast-myofibroblast transition and adipocyte-myofibroblast transition in vitro using primary cell culture. In this way, we will try to elucidate the mechanism that LTB4/BLT1 axis may take part in the development of SSc by regulating myofibroblast formation. Taken together, these study will hopefully supply the theoretical basis for the clinical transition in SSc.

脂质炎症介质LTB4通过其高亲和性受体BLT1，在免疫炎症性疾病中发挥重要生物学功能。肌成纤维细胞在系统性硬化症（SSc）发病中作用关键，但调控机制不明。本课题前期发现：LTB4在SSc患者外周血中上调；BLT1在博来霉素（BLM）诱导的SSc小鼠皮肤中亦升高；而在BLT1基因缺失（BLT1-/-）小鼠中，BLM不能诱导出SSc表型，且皮肤和肺中α-SMA+肌成纤维细胞较野生型明显减少，提示LTB4/BLT1轴参与SSc发病，LTB4可能经BLT1调控肌成纤维细胞形成。本研究通过微渗透压泵传输BLM的方法建立了改良SSc小鼠模型，拟采用BLT1-/-小鼠和BLT1拮抗剂干预，明确LTB4/BLT1轴对SSc发病的作用，通过原代细胞培养体外研究成纤维细胞-肌成纤维细胞转化和脂肪细胞-肌成纤维细胞转化，以阐明LTB4/BLT1轴调控肌成纤维细胞形成参与SSc发病的机制，为临床转化提供理论借鉴。

脂质炎症介质白三烯（leukotriene B4, LTB4）通过其高亲和性受体BLT1，在免疫炎症性疾病中发挥重要生物学功能。肌成纤维细胞在系统性硬化症（systemic sclerosis, SSc）发病中作用关键，但调控机制不明。75%的SSc患者合并有间质性肺病（interstitial lung disease, ILD）,是导致SSc患者死亡首要病因。本研究旨在探讨LTB4/BLT1轴在SSc合并ILD中的致病机制。首先纳入60例SSc患者及100例健康对照，通过ELISA检测其血清中LTB4水平，并与临床特征进行相关性分析，通过免疫组化对受累皮肤及肺组织中LTB4合成关键酶LTA4H及BLT1进行检测，进而采用BLT1基因敲除（BLT1-/-）小鼠及BLT1特异性拮抗剂处理，探讨BLT1在博来霉素诱导的SSc-ILD小鼠模型中的作用，体外采用原代皮肤成纤维细胞及内皮细胞系HUVEC细胞，研究LTB4通过BLT1对肌成纤维细胞形成的作用及关键信号通路。研究发现LTB4在SSc患者外周血中上调，且与弥漫皮肤型和间质性肺病的临床特征相关。LTA4H及BLT1在SSc患者及博来霉素（BLM）诱导的SSc小鼠皮肤和肺组织中升高。在BLT1-/-小鼠中，BLM不能诱导出SSc表型，且皮肤和肺中α-SMA+肌成纤维细胞较野生型明显减少。予以SSc小鼠BLT1特异性拮抗剂U-75302处理，可显著缓解其皮肤及肺组织的炎症和纤维化，同时伴有α-SMA+肌成纤维细胞数目减少，提示LTB4/BLT1轴参与SSc-ILD发病，LTB4可能经BLT1调控肌成纤维细胞形成。通过体外实验证实来自SSc患者血清中的LTB4或重组LTB4可通过BLT1介导成纤维细胞-肌成纤维细胞转化和内皮细胞-肌成纤维细胞转化，进一步发现LTB4可通过BLT1介导的下游PI3K/Akt/mTOR通路的活化调控肌成纤维细胞形成，但不依赖于经典的TGF-β/TGF-βRI通路。以上内容阐明LTB4/BLT1轴调控肌成纤维细胞形成参与SSc发病的机制，为临床转化提供理论借鉴。

内容获取失败，请点击重试