Department of Biochemistry, University of Kerala, Kariavattom, Thiruvananthapuram, Kerala, India, 695 581.
Hepatol Res. 2008 Dec;38(12):1221-32. doi: 10.1111/j.1872-034X.2008.00394.x. Epub 2008 Jul 4.
Cytokines and growth factors released by various hepatic cells exert both paracrine and autocrine effects on hepatic stellate cell (HSC) activation during liver injury. The aim of the present study was to examine whether the surrounding extracellular matrix (ECM) influences the activation, transdifferentiation and survival of HSCs.
An in vitro model system of isolated HSCs maintained in culture on different matrix protein substrata was employed.
The rate of loss of HSC-specific retinol uptake activity and gain of myofibroblast-like activity such as (35)[S] proteoglycan synthesis varied in cells maintained on different matrix proteins and was in the order collagen I > collagen IV >/= laminin. (3)[H]-thymidine incorporation by HSCs maintained on different matrix proteins varied and was in the order collagen I > collagen IV > laminin. MTT assay revealed that the growth inhibition in response to curcumin was significantly low in cells maintained on collagen I. Apoptotic marker activities such as DNA fragmentation, 4',6'-diamidino-2-phenylindole dihydrochloride (DAPI) staining, annexin staining and caspase-3 activities showed that cells maintained on collagen I showed minimal apoptosis than those maintained on collagen IV, laminin and polylysine, showing the influence of ECM on HSC apoptosis. Experiments using blocking antibodies showed that the collagen I effect was mediated through alpha(2)beta(1) integrin.
These results indicate that ECM influences activation, transdifferentiation and survival of HSCs, and suggest that apart from diffusible factors, the surrounding ECM also influences HSC behavior critical in both the progression of the fibrosis and the restitution of the liver during recovery after hepatic injury.
在肝损伤过程中，各种肝细胞释放的细胞因子和生长因子对肝星状细胞（HSC）的激活具有旁分泌和自分泌作用。本研究旨在探讨细胞外基质（ECM）是否影响 HSC 的激活、转分化和存活。
采用体外分离的 HSCs 在不同基质蛋白底物上培养的模型系统。
HSCs 在不同基质蛋白上的维持中，视黄醇摄取活性的丧失率和肌成纤维细胞样活性（如[35]S 蛋白聚糖合成）的获得率不同，其顺序为胶原 I>胶原 IV>=层粘连蛋白。HSCs 在不同基质蛋白上的[3]H-胸苷掺入率不同，顺序为胶原 I>胶原 IV>层粘连蛋白。MTT 试验显示，在胶原 I 上维持的细胞对姜黄素的生长抑制反应明显较低。凋亡标记物活性，如 DNA 片段化、4'，6'-二脒基-2-苯基吲哚二盐酸盐（DAPI）染色、膜联蛋白染色和 caspase-3 活性表明，在胶原 I 上维持的细胞比在胶原 IV、层粘连蛋白和多聚赖氨酸上维持的细胞凋亡活性最小，表明 ECM 对 HSC 凋亡的影响。使用阻断抗体的实验表明，胶原 I 的作用是通过α2β1 整联蛋白介导的。
这些结果表明 ECM 影响 HSC 的激活、转分化和存活，并提示除了扩散因子外，周围的 ECM 也影响 HSC 行为，这在肝损伤后肝脏恢复过程中纤维化的进展和肝脏的恢复都很关键。
