Connective Tissue Growth Factor in Hepatic Fibrosis

广泛的长期目标是确定结缔组织生长因子(CTGF)在导致纤维化疾病中的作用。CTGF是一种高度促纤维化的分子，到目前为止，在所有已检查的纤维化病变中都有过度表达。它在转录水平上被转化生长因子-β(TGF-β)激活，并介导许多先前被认为是由转化生长因子-β所具有的基质诱导特性。本提案中描述的研究重点是CTGF在肝纤维化中的作用，包括与酒精滥用有关的研究。初步数据显示，CTGF在纤维化的肝脏中过度表达，并由肝星状细胞(HSCs)产生，HSCs是主要的纤维化细胞类型，既是对转化生长因子-β的反应，也是作为激活的功能。CTGF可增强HSC的粘附性和α-平滑肌肌动蛋白水平。此外，乙醇及其致纤维化代谢产物乙醛可刺激成纤维细胞中CTGF的转录。我们的假设是，肝脏中CTGF的局部上调推动了纤维化反应，包括由酒精引发的反应。我们的具体目标是(1)确定CTGF在HSC中的调节机制，包括促进HSC和CTGF产生的转化生长因子-β和乙醛以及抑制HSC功能和CTGF产生的维甲酸和肿瘤坏死因子-α；(2)通过检测CTGF对HSC DNA合成、分裂、基质代谢、维生素A含量和黏附的影响，确定CTGF对HSC功能的影响；(3)构建CTGF基因体内转导的重组腺相关病毒，直接建立10 kDa和38 kDa CTGF体外诱导肝纤维化的能力。这些研究将从其调节、生物学特性、信号机制和蛋白质结构等方面确定CTGF的致纤维化特性。此外，这些研究将有助于确定CTGF是否是治疗纤维化的治疗目标，在美国，纤维化是导致45%死亡的一个因素。

The broad long-term objectives are to establish the role of connective tissue growth factor (CTGF) in causing fibrotic disease. CTGF is a highly pro-fibrogenic molecule which is over- expressed in all fibrotic lesions examined to date. It is transcriptionally activated by transforming growth factor-beta (TGF-beta) and mediates many of the matrix-inducing properties that have previously been attributed to TGF-beta. The studies described in this proposal focus on the role of CTGF in liver fibrosis, including that related to alcohol abuse. Preliminary data show that CTGF is over-expressed in fibrotic livers and is produced by hepatic stellate cells (HSCs), the principal fibrogenic cell type, both in response to TGF-beta and as a function of activation. HSCs show enhanced adhesion and levels of alpha smooth muscle actin in response to CTGF. In addition, ethanol and its fibrogenic metabolite, acetaldehyde, stimulate CTGF transcription in fibroblasts. Our hypothesis is that local up-regulation of CTGF in the liver drives the fibrogenic response, including that initiated by alcohol. Our Specific Aims are (1) To determine mechanisms of CTGF regulation in HSCs, including the role played by TGF-beta and acetaldehyde (which stimulate HSCs and CTGF production) as well as retinoic acid and TNF-alpha (which inhibit HSC function and CTGF production); (2) To determine the effects of CTGF on HSC function by examining HSC DNA synthesis, division, matrix metabolism, vitamin A content, and adhesion in HSCs treated with or over-expressing various mass forms (1OkDa, 16-20kDa, 38kDa) of CTGF which occur naturally in vivo and which are a product of HSCs maintained in vitro, and to determine the role of CTGF-stimulated kinases in these processes; and (3) To produce recombinant adeno-associated viruses for the delivery of the CTGF gene into the liver in vivo to directly establish the ability of 10 kDa and 38kDa CTGF to stimulate liver fibrosis. These studies will define the fibrogenic properties of CTGF in terms of its regulation, biological properties, signaling mechanisms and protein structure. In addition, these studies will help establish whether CTGF is a therapeutic target for treating fibrosis, which is a contributing factor in 45 percent of deaths in the USA.