Liepelt Anke, Tacke Frank
Department of Medicine III, University Hospital Aachen, Aachen, Germany.
Department of Medicine III, University Hospital Aachen, Aachen, Germany
Am J Physiol Gastrointest Liver Physiol. 2016 Aug 1;311(2):G203-9. doi: 10.1152/ajpgi.00193.2016. Epub 2016 Jun 16.
The chemokine stromal cell-derived factor-1 (SDF-1) or CXCL12 is constitutively expressed in healthy liver. However, its expression increases following acute or chronic liver injury. Liver sinusoidal endothelial cells (LSEC), hepatic stellate cells (HSC), and malignant hepatocytes are important sources of SDF-1/CXCL12 in liver diseases. CXCL12 is able to activate two chemokine receptors with different downstream signaling pathways, CXCR4 and CXCR7. CXCR7 expression is relevant on LSEC, while HSC, mesenchymal stem cells, and tumor cells mainly respond via CXCR4. Here, we summarize recent developments in the field of liver diseases involving this chemokine and its receptors. SDF-1-dependent signaling contributes to modulating acute liver injury and subsequent tissue regeneration. By activating HSC and recruiting mesenchymal cells from bone marrow, CXCL12 can promote liver fibrosis progression, while CXCL12-CXCR7 interactions endorse proregenerative responses in chronic injury. Moreover, the SDF-1 pathway is linked to development of hepatocellular carcinoma (HCC) by promoting tumor growth, angiogenesis, and HCC metastasis. High hepatic CXCR4 expression has been suggested as a biomarker indicating poor prognosis of HCC patients. Tumor-infiltrating myeloid-derived suppressor cells (MDSC) also express CXCR4 and migrate toward CXCL12. Thus CXCL12 inhibition might not only directly block HCC growth but also modulate the tumor microenvironment (angiogenesis, MDSC), thereby sensitizing HCC patients to conventional or emerging novel cancer therapies (e.g., sorafenib, regorafenib, nivolumab, pembrolizumab). We herein summarize the current knowledge on the complex interplay between CXCL12 and CXCR4/CXCR7 in liver diseases and discuss approaches on the therapeutic targeting of these axes in hepatitis, fibrosis, and liver cancer.
趋化因子基质细胞衍生因子-1(SDF-1)或CXCL12在健康肝脏中组成性表达。然而,在急性或慢性肝损伤后其表达会增加。肝窦内皮细胞(LSEC)、肝星状细胞(HSC)和恶性肝细胞是肝脏疾病中SDF-1/CXCL12的重要来源。CXCL12能够激活具有不同下游信号通路的两种趋化因子受体,即CXCR4和CXCR7。CXCR7的表达与LSEC相关,而HSC、间充质干细胞和肿瘤细胞主要通过CXCR4作出反应。在此,我们总结了涉及这种趋化因子及其受体的肝脏疾病领域的最新进展。SDF-1依赖性信号传导有助于调节急性肝损伤及随后的组织再生。通过激活HSC并从骨髓募集间充质细胞,CXCL12可促进肝纤维化进展,而CXCL12-CXCR7相互作用在慢性损伤中支持促再生反应。此外,SDF-1途径通过促进肿瘤生长、血管生成和肝癌转移与肝细胞癌(HCC)的发生相关。肝脏CXCR4高表达已被认为是提示HCC患者预后不良的生物标志物。肿瘤浸润性髓源性抑制细胞(MDSC)也表达CXCR4并向CXCL12迁移。因此,抑制CXCL12不仅可能直接阻断HCC生长,还可能调节肿瘤微环境(血管生成、MDSC),从而使HCC患者对传统或新兴的新型癌症疗法(如索拉非尼、瑞戈非尼、纳武单抗、派姆单抗)敏感。我们在此总结了目前关于CXCL12与CXCR4/CXCR7在肝脏疾病中复杂相互作用的认识,并讨论了在肝炎、纤维化和肝癌中针对这些轴进行治疗靶向的方法。