Fibrocytes contribute to TAA-induced liver fibrosis in mice
Fibrocytes contribute to TAA-induced liver fibrosis in mice
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纤维细胞导致 TAA 诱导的小鼠肝纤维化
DOI：
10.1055/s-0039-3402123
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Pons-Kühnemann
中科院分区：
文献类型：
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作者：
Hempel;Roderfeld;Sydykov;Irungbam;Schermuly;Voswinckel;Köhler;Churin;Pons-Kühnemann
背景：骨髓源性纤维细胞是一种独特的细胞类型，具有间充质细胞和造血细胞的共同特征。它们占外周血白细胞的0.5%，与肾、肺、心脏和肝脏的纤维化疾病有关。纤维细胞特异性地渗入受损的肝脏，并参与细胞外基质成分的沉积。此外，纤维细胞通过分泌转化生长因子-β、基质金属蛋白酶、肿瘤坏死因子-α、IL-1β和其他炎性细胞因子来调节纤维化的发生。然而，它们与肝纤维化的相关性仍不清楚。我们的目的是在慢性中毒性肝纤维化的小鼠模型中研究纤维细胞在纤维化形成过程中的作用。将在I型胶原启动子控制下表达单纯疱疹病毒胸苷激酶(HSV-TK)的转基因C57BL/6J小鼠的骨髓移植到相同遗传背景的致死性照射小鼠体内(每组16只，对照组小鼠接受野生型骨髓移植)。将被HSV-TK代谢成有毒化合物的硫代乙酰胺(TAA)和伐更昔洛韦(Valganciclovir)通过饮用水给予18周，以诱导纤维化并特异性地消耗骨髓来源的纤维细胞。结果：TAA诱导了明显的小叶周围纤维化。RNA原位杂交显示对照组肝脏标本中的纤维细胞，证明自杀基因策略是成功的。纤维细胞的耗尽导致纤维胶原的数量显著减少，表现为肝脏羟脯氨酸含量的降低(-7.8%；95%可信区间：0.7-14.8%；p=0.033)。免疫印迹、免疫组织化学和RT-qPCR结果显示，去除成纤维细胞后，α-SMA的表达和分布无明显变化。对一组MMP和炎症介质的高通量分析没有产生相关的规定。然而，较低的血清ALT水平(-20.9%；95%可信区间：0.4-36.9%；p=0.049)显示肝脏特异性细胞损伤的减轻。我们的结果表明，纤维细胞在TAA诱导的肝纤维化中的作用与肌成纤维细胞的激活或增殖无关。
Background:Bone marrow-derived fibrocytes represent a unique cell type, sharing features of both mesenchymal and hematopoietic cells. They comprise 0.5% of peripheral blood leucocytes and have been implicated in fibrotic diseases of the kidney, lung, heart, and liver. Fibrocytes were shown to specifically infiltrate the injured liver and participate in the deposition of extracellular matrix components. Moreover, fibrocytes hold the potential to regulate fibrogenesis via the secretion of TGF-β, MMPs, TNF-α, IL-1β, and other inflammatory cytokines. Their relevance to hepatic fibrosis, however, remains unknown. We aimed to study the effect of a fibrocyte depletion during fibrogenesis in a mouse model of chronic-toxic liver fibrosis.Methods:Fibrocytes were depleted utilizing a suicide gene strategy. Bone marrow of transgene C57BL/6J mice, expressing a herpes simplex virus thymidine kinase (HSV-TK) under the control of a collagen I promotor, was transplanted into lethally irradiated mice of the same genetic background (n= 16 per group, mice of the control group received wild-type bone marrow). Thioacetamide (TAA) and Valganciclovir, which is metabolized into toxic compounds by the HSV-TK, were administered via drinking water for 18 weeks to induce fibrosis and specifically deplete bone marrow-derived fibrocytes.Results:TAA-administration induced a marked perilobular fibrosis. RNA in situ hybridization visualized fibrocytes in liver samples of the control group and proved the suicide gene strategy's success. The depletion of fibrocytes lead to a significantly reduced amount of fibrillar collagens, indicated by decreased hepatic hydroxyproline content (-7.8%; 95% CI: 0.7–14.8%; p= 0.033). The expression and distribution of α-SMA was unchanged in western blot, immunohistochemistry, and RT-qPCR in result of the fibrocyte ablation. High-throughput analyses of a panel of MMPs and inflammatory mediators yielded no relevant regulations. Yet lower serum ALT levels (-20.9%; 95% CI: 0.4–36.9%; p= 0.049) show a mitigation of liver-specific cellular damage.Conclusion:Our model enabled the study of fibrocytes in a complex in vivo setting. Fibrocytes functionally contribute to TAA-induced liver fibrosis, as our results suggest, independent of the activation or proliferation of myofibroblasts.