Replicative senescence of activated human hepatic stellate cells is accompanied by a pronounced inflammatory but less fibrogenic phenotype
Replicative senescence of activated human hepatic stellate cells is accompanied by a pronounced inflammatory but less fibrogenic phenotype
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DOI：
10.1053/jhep.2003.50097
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发表时间：
2003-03-01
期刊：
影响因子：
13.5
通讯作者：
Brenner, DA
中科院分区：
文献类型：
--
作者：
Schnabl, B;Purbeck, CA;Brenner, DA
有限的增殖能力是大多数正常人类细胞的一个特征，并导致生长停滞状态，称为复制衰老。人活化的肝星状细胞 (HSC) 中端粒酶催化亚基（人端粒酶逆转录酶；hTERT）的功能性表达可通过永生化将其从死亡中拯救出来，并维持活化的 HSC 表型。本研究的目的是评估体外老化人类激活的 HSC 的基因和蛋白质表达的变化，并确定衰老激活的 HSC 在培养物中被消除的途径。使用 DNA 微阵列分析评估衰老人类 HSC 中基因表达的改变模式，并与早期传代 HSC 或 hTERT 永生化 HSC 进行比较。与早期传代的 HSC 相比，衰老的 HSC 表现出更高的炎症和应激相关基因表达。衰老的造血干细胞表达的细胞外基质蛋白水平降低，包括胶原蛋白、腱蛋白和纤连蛋白。衰老 HSC 的 TUNEL 染色显示大约 21% 的阳性细胞，表明 DNA 片段化和细胞凋亡。细胞凋亡涉及线粒体途径，其中 Bcl-2 和 Bcl-x(L) 蛋白水平降低、细胞色素 C 释放以及 caspase-3 活性增加。相比之下，4% 至 5% 的早期激活 HSC 或端粒酶阳性 HSC 呈 TUNEL 阳性。总之，培养的人类造血干细胞经历了从纤维形成表型向炎症表型的转变，这表明衰老的人类造血干细胞可能调节慢性伤口加热过程。端粒长度的维持是活化的人类 HSC 的重要生存因素。
Limited proliferative capacity is a characteristic of most normal human cells and results in a growth-arrested state, called replicative senescence. Functional expression of the telomerase catalytic subunit (human telomerase reverse transcriptase; hTERT) in human activated hepatic stellate cells (HSCs) rescues them from death with immortalization and maintains an activated HSC phenotype. The aim of this study was to evaluate alterations in gene and protein expression of in vitro aged human activated HSCs and to define the pathway by which senescent-activated HSCs are eliminated in culture. Altered patterns of gene expression in senescent human HSCs were assessed using DNA microarray analysis and compared with early passage HSCs or hTERT immortalized HSCs. Senescent HSCs showed higher expression of inflammation and stress-associated genes as compared with early passage HSCs. Senescent HSCs expressed reduced levels of extracellular matrix proteins, including collagens, tenascin, and fibronectin. TUNEL staining of senescent HSCs showed approximately 21% positive cells, indicating DNA fragmentation and apoptosis. Apoptosis involved the mitochondrial pathway with decreased levels of Bcl-2 and Bcl-x(L) protein, release of cytochrome C, and increased caspase-3 activity. In contrast, 4% to 5% of early activated HSCs or telomerase positive HSCs were TUNEL positive. In conclusion, cultured human HSCs undergo a switch from a fibrogenic to an inflammatory phenotype, suggesting that senescent human HSCs might modulate chronic wound heating processes. Maintenance of telomere length represents an important survival factor for activated human HSCs.