Reciprocal modulation of matrix metalloproteinase-13 and type I collagen genes in rat hepatic stellate cells

Collagen degradation by matrix metalloproteinases is the limiting step in reversing liver fibrosis. Although collagen production in cirrhotic livers is increased, the expression and/or activity of matrix metalloproteinases could be normal, increased in early fibrosis, or decreased during advanced liver cirrhosis. Hepatic stellate cells are the main producers of collagens and matrix metalloproteinases in the liver. Therefore, we sought to investigate whether they simultaneously produce alpha1(I) collagen and matrix metalloproteinase-13 mRNAs. In this communication we show that expression of matrix metalloproteinase-13 mRNA is reciprocally modulated by tumor necrosis factor-alpha and transforming growth factor-beta1. When hepatic stellate cells are co-cultured with hepatocytes, matrix metalloproteinase-13 mRNA is up-regulated and alpha1(I) collagen is down-regulated. Injuring hepatocytes with galactosamine further increased matrix metalloproteinase-13 mRNA production. Confocal microscopy and differential centrifugation of co-cultured cells revealed that matrix metalloproteinase-13 is localized mainly within hepatic stellate cells. Studies performed with various hepatic stellate cell lines revealed that they are heterogeneous regarding expression of matrix metalloproteinase-13. Those with myofibroblastic phenotypes produce more type I collagen whereas those resembling freshly isolated hepatic stellate cells express matrix metalloproteinase-13. Overall, these findings strongly support the notion that alpha1(I) collagen and matrix metalloproteinase-13 mRNAs are reciprocally modulated.     

Expression of transforming growth factor-beta 1 by pancreatic stellate cells and its implications for matrix secretion and turnover in chronic pancreatitis

Pancreatic stellate cells mediate fibrosis in chronic pancreatitis. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs)-1 and -2 are crucial modulators of fibrosis. Transforming growth factor-beta (TGF-beta) is a key regulator of extracellular matrix production and myofibroblast proliferation. We have examined MMP and TIMP synthesis by transformed cultured pancreatic stellate cells and their regulation by TGF-beta 1. By Northern analysis they expressed mRNAs for procollagen 1, TIMP-1, TIMP-2, and MMP-2. Expression of membrane type-1 MMP was confirmed by Western blotting. By immunohistochemistry these enzymes localized to fibrotic areas in human chronic pancreatitis. Active TGF-beta 1 constitutes 2 to 5% of total TGF-beta 1 secreted by pancreatic stellate cells; they express TGF-beta receptors I and II. Exogenous TGF-beta 1 (10 ng/ml) significantly increased procollagen-1 mRNA by 69% and collagen protein synthesis by 34%. Similarly TGF-beta 1 at 0.1, 1, and 10 ng/ml significantly reduced cellular proliferation rate by 37%, 44%, and 44%, respectively, whereas pan-TGF-beta-neutralizing antibody increased proliferation by 40%. TGF-beta1 (10 ng/ml) down-regulated MMP-9 by 54% and MMP-3 by 34% whereas TGF-beta 1-neutralizing antibody increased MMP-9 expression by 39%. Pancreatic stellate cells express both mediators of matrix remodeling and the regulatory cytokine TGF-beta 1 that, by autocrine inhibition of MMP-3 and MMP-9, may enhance fibrogenesis by reducing collagen degradation.     

Loss of discoidin domain receptor 2 promotes hepatic fibrosis after chronic carbon tetrachloride through altered paracrine interactions between hepatic stellate cells and liver-associated macrophages

Hepatic stellate cells (HSCs) interact with fibrillar collagen through the discoidin domain receptor 2 (DDR2) in acute hepatic injury, generating increased fibrosis. However, the contribution of DDR2 signaling to chronic liver fibrosis in vivo is unclear, despite its relevance to chronic human liver disease. We administered carbon tetrachloride (CCl(4)) to DDR2(+/+) and DDR2(-/-) mice twice weekly, and liver tissues and isolated HSCs were analyzed. In contrast to changes seen in acute injury, after chronic CCl(4) administration, DDR2(-/-) livers had increased collagen deposition, gelatinolytic activity, and HSC density. Increased basal gene expression of osteopontin, transforming growth factor-β1, monocyte chemoattractant protein-1, and IL-10 and reduced basal gene expression of matrix metalloproteinase-2, matrix metalloproteinase-13, and collagen type I in quiescent DDR2(-/-) HSCs were amplified further after chronic CCl(4). In concordance, DDR2(-/-) HSCs isolated from chronically injured livers had enhanced in vitro migration and proliferation, but less extracellular matrix degradative activity. Macrophages from chronic CCl(4)-treated DDR2(-/-) livers showed stronger chemoattractive activity toward DDR2(-/-) HSCs than DDR2(+/+) macrophages, increased extracellular matrix degradation, and higher cytokine mRNA expression. In conclusion, loss of DDR2 promotes chronic liver fibrosis after CCl(4) injury. The fibrogenic sinusoidal milieu generated in chronic DDR2(-/-) livers recruits more HSCs to injured regions, which enhances fibrosis. Together, these findings suggest that DDR2 normally orchestrates gene programs and paracrine interactions between HSCs and macrophages that together attenuate chronic hepatic fibrosis.     

Eosinophil inflammation of nasal polyp tissue: relationships with matrix metalloproteinases,tissue inhibitor of metalloproteinase-1, and transforming growth factor-beta1

Eosinophil and mast cell infiltrations are consistent findings in nasal polyp tissue. Previous studies have shown that matrix metalloproteinases (MMPs) may be involved in eosinophil infiltration in airway mucosa of asthmatic patients, and that transforming growth factor-beta1 (TGF-beta1) induces extracellular matrix deposition in nasal polyp tissue. The aim of this study was to evaluate the role of MMPs and tissue-inhibitor of metalloproteinase-1 (TIMP-1) in association with TGF-beta1, eosinophils and mast cell activation in nasal polyp tissue. Nasal polyp tissues from 20 patients who underwent polypectomies were collected and prepared into tissue homogenate. Eosinophil cationic protein (ECP) and tryptase levels were measured by CAP system (Pharmacia, Sweden). MMP-2, MMP-9, TIMP-1 and TGF-beta1 levels were measured by enzyme-liked immunosorbent assay. MMP-2 was the predominant form of MMPs, followed by MMP-9 and TIMP-1. There were significant correlations between ECP, and MMP-9, MMP-2, TGF-beta1 and tryptase, but not with TIMP-1. Significant correlations were noted between tryptase, and MMP-2, MMP-9, and TGF-beta1, but not with TIMP-1. Close correlations were noted between TGF-beta1, and MMP-9 and MMP-2, but not with TIMP-1. MMP-2, MMP-9, and TGF-beta1 may contribute to eosinophil and mast cell migrations into nasal polyp tissue.     

七项肝纤维化血清标志物的诊断意义

目的 检测肝病患者血清基质金属蛋白酶1(MMP-1)、基质金属蛋白酶抑制剂1(TIMP-1)、转化生长因子B1(TGF-β1)、透明质酸(HA)、Ⅲ型前胶原(PⅢP)、Ⅳ型胶原(CⅣ)和层粘连蛋白(LN)含量,评价其对肝纤维化的诊断价值.方法 酶标法检测血清MMP-1、TIMP-1、TGF-β1含量.放射免疫法检测血清HA、PⅢP、CⅣ、LN含量.结果 肝病患者血清TGF-β1、HA、PⅢP、CⅣ、LN水平与健康对照组比较均有升高,差异均有统计学意义(P＜0.05).慢性肝病患者血清TIMP-1水平明显高于健康对照组(P＜0.01),而肝病患者血清MMP-1水平与健康对照组比较,差异无统计学意义(P＞0.05).结论 慢性肝病患者存在MMP-1和TIMP-1的严重失衡,是慢性肝病患者肝脏细胞外基质沉积的重要原因.血清TIMP-1、TGF-β1、HA、PⅢP、CⅣ和LN对肝纤维化具有较好的临床诊断价值,而MMP-1的临床诊断价值欠佳.     

IOX1对TGF-β诱导的LX2细胞增殖、凋亡及细胞外基质相关蛋白表达的影响

目的:探讨组蛋白去甲基化酶抑制剂IOX1(5-羧基-8-羟基喹啉)提高组蛋白H3第9位赖氨酸二甲基化(H3K9me2)水平对转化生长因子β(TGF-β)诱导的人肝星状细胞株LX2增殖、凋亡及细胞外基质合成和代谢的影响。方法:采用实时无标记细胞分析技术动态观察不同浓度IOX1对TGF-β诱导的LX2细胞增殖的影响。采用流式细胞术观察IOX1对TGF-β诱导的LX2细胞凋亡的影响。Western blot检测细胞中H3K9me2水平,以及α-平滑肌肌动蛋白(α-SMA)、Ⅰ型胶原(Col I)、基质金属蛋白酶1(MMP-1)和金属蛋白酶组织抑制物1(TIMP-1)蛋白的表达。结果:与对照组相比,不同浓度的IOX1均能抑制LX2细胞增殖。流式细胞术结果表明,IOX1能够促进LX2细胞凋亡(P<0.05)。Western blot结果发现,IOX1能提高LX2中H3K9me2水平,且呈剂量依赖性(P<0.05);与对照组相比,300μmol/L IOX1能够明显抑制TGF-β诱导的LX2细胞中α-SMA、TIMP-1和Col I蛋白的表达(P<0.05),MMP-1蛋白的表达在不同浓度IOX1组中表现为上升趋势(P<0.05)。结论:IOX1可抑制TGF-β诱导的LX2细胞增殖并促进细胞凋亡,还可通过提高H3K9me2水平调节细胞外基质的合成和代谢,从而发挥抗肝纤维化作用。     

Appearance of denuded hepatic stellate cells and their subsequent myofibroblast-like transformation during the early stage of biliary fibrosis in the rat

To investigate the early in vivo response of hepatic stellate cells in biliary fibrosis, we examined rat livers during the first 7 days after bile duct ligation using light microscopy, immunohistochemistry, electron microscopy, and immunoelectron microscopy. At day 1 after bile duct ligation, alpha-smooth muscle actin-positive fibroblasts appeared and then increased in number around the proliferating bile ductules. With time, the destruction of the external limiting plate became accentuated because of the invasion of the proliferating bile ductules and periductural fibrosis. At day 7, stromal cells containing fat droplets appeared in the fibrous tissue adjacent to the periportal parenchyma; these are termed denuded hepatic stellate cells. In the fibrous tissue disconnected from the liver parenchyma, the denuded hepatic stellate cells were replaced by myofibroblast-like cells. Meanwhile, the expression of transforming growth factor-beta1 on biliary epithelial cells increased. These results indicate the dual origin of myofibroblasts in experimental biliary fibrosis, the periductural and periductal fibroblasts in the initial stage, and the denuded hepatic stellate cells in the subsequent stage. These two types of stromal cells may undergo myofibroblastic transformation by the transforming growth factor-beta1 secreted by the proliferating biliary epithelial cells.     

Is there a relationship between tissue inhibitor of metalloproteinase-1 and transforming growth factor-beta 1 with respect to malignant melanoma progression?

Recent articles about the roles and relationships of tissue inhibitor of metalloproteinase-1 and transforming growth factor-beta 1 in various types of normal tissues and malignancies give rise to the question: ‘Is there a relationship between them with regard to malignant melanoma progression?’ In the light of many references, it seems to be highly probable that the tissue inhibitor of metalloproteinase-1, – being a multifunctional protein – functions as a growth factor with possible stimulation by transforming growth factor-beta 1 in progression of malignant melanoma, rather than its other existing functions in many different normal and cancer tissues (e.g. inhibition of the matrix metalloproteinases or functioning as an insignificant inhibitor of angiogenesis).     

三氧化二砷对皮肤成纤维细胞、中性粒细胞MMPs活性,TIMP-1及TGF-β1表达的影响

目的：砒石是化腐生肌的常用中药，其主要成分是三氧化二砷（As₂O₃）。本研究通过观察As₂O₃对基质金属蛋白酶（MMPs）活性、基质金属蛋白酶组织抑制因子-1（TIMP-1）及转化生长因子β₁（TGF-β₁）表达影响，探讨化腐中药能否调节胶原代谢，从而治疗慢性皮肤溃疡。方法:明胶酶谱法检测大鼠中性粒细胞（PMNs）来源的MMP-9活性、人成纤维细胞（hFb）分泌的MMP-1、MMP-2的活性，免疫细胞化学法检测hFb TIMP-1、TGF-β₁的表达。结果:As₂O₃浓度在50 mg/L时可以提高大鼠PMNs来源的MMP-9的活性（P<0.01）；在0.8 mg/L可以提高hFb分泌的MMP-1、MMP-2的活性（分别P<0.01）；同时As₂O₃作用于hFb 6 h、12 h、18 h后，TIMP-1、TGF-β₁表达持续降低（P<0.01）。结论:As₂O₃在一定范围内可提高PMNs来源的MMP-9的活性；也可提高hFb分泌的MMP-1、MMP-2的活性，同时抑制hFbTIMP-1、TGF-β₁的表达。提示砷类制剂可通过提高多种MMPs的活性，降低TIMP-1的表达从而发挥化腐作用。     

氯喹对体外活化肝星状细胞自噬与胶原代谢的影响

目的:研究不同浓度的自噬抑制剂氯喹(CQ)对活化的大鼠肝星状细胞系HSC-T6中Ⅰ、Ⅲ型胶原表达的影响及可能机制。方法:应用转化生长因子β1(TGF-β1)活化HSC-T6细胞,给予CQ干预24 h。实验分组为:control组、TGF-β1组、TGF-β1+CQ(15μmol/L)组、TGF-β1+CQ(30μmol/L)组和TGF-β1+CQ(60μmol/L)组。采用Western blot技术检测微管相关蛋白轻链3(LC3)比值LC3-Ⅱ/LC3-Ⅰ、自噬靶蛋白P62、α-平滑肌肌动蛋白(α-SMA)、Ⅰ型胶原、Ⅲ型胶原、基质金属蛋白酶13(MMP-13)、金属蛋白酶组织抑制物1(TIMP-1)和TIMP-2的表达情况;免疫细胞化学检测Ⅰ、Ⅲ型胶原的表达;RT-q PCR检测Ⅰ型胶原、Ⅲ型胶原、MMP-13、TIMP-1和TIMP-2mRNA的表达变化。结果:CQ干预后LC3-Ⅱ/LC3-Ⅰ比值明显升高且呈剂量依赖性;P62蛋白表达TGF-β1+CQ组均显著高于TGF-β1组(P0.01)。TGF-β1组的Ⅰ、Ⅲ型胶原表达量较control组显著增加,TGF-β1+CQ组较TGF-β1组也有明显增加。α-SMA的表达在TGF-β1组和TGF-β1+CQ组均显著高于control组(P0.05),而TGF-β1组和TGF-β1+CQ各组之间无显著差异。MMP-13表达在TGF-β1+CQ组较TGF-β1组显著下降(P0.05);TIMP-1和TIMP-2在TGF-β1+CQ组较TGF-β1组显著升高(P0.05),且呈剂量依赖性。结论:自噬抑制剂CQ能显著增加HSC-T6细胞中Ⅰ、Ⅲ型胶原的表达并呈剂量依赖性,这可能与其上调TIMP-1及TIMP-2的表达并抑制MMP-13表达有关。     

Skin flap-induced regression of granulation tissue correlates with reduced growth factor and increased metalloproteinase expression

Previous studies have shown that covering granulation tissue of a full-thickness skin wound by a vascularized skin flap induces tissue remodeling, with a rapid loss of granulation tissue cells by apoptosis. In the present study, in situ hybridization has been used to examine mRNA expression for several factors that may be implicated in the apoptosis seen in this tissue. Skin wounds were made on the dorsal skin of 8-week-old rats. Ten days after wounding, skin flaps were created surgically and sutured over the granulation tissue. Tissue sections of granulation tissue from various times after addition of the skin flap were hybridized with 33P-labelled cRNA probes for transforming growth factor-beta1 (TGF-beta1), beta-inducible gene H3 (beta-ig-h3), alpha1 (1) procollagen, alpha-smooth muscle actin, matrix metalloproteinase-13 (MMP-13) and -2 (MMP-2), tissue inhibitor of metalloproteinase-1 (TIMP-1), and inducible nitric oxide synthase (iNOS). Control granulation tissue prior to addition of the skin flap showed high levels of TGF-beta1, beta-ig-h3, alpha1 (1) procollagen, alpha-smooth muscle actin, and TIMP-1 expression. MMP-13, MMP-2, and iNOS mRNA were low in 10-day granulation tissue. Addition of a skin flap resulted in a decrease in the expression of TGF-beta1, beta-ig-h3, alpha1 (I) procollagen, alpha-smooth muscle actin, and TIMP-1, but increased expression of MMP-13 and MMP-2. Similarly, an increase in iNOS mRNA expression was observed in the granulation tissue after addition of the skin flap. Addition of a vascularized skin flap may result in rapid remodelling of granulation tissue due to a decrease in expression of the trophic growth factor TGF-beta1 and increased degradation of extracellular matrix due to an alteration in the balance between MMPs and their inhibitor, TIMP-1. Additionally, increased iNOS expression may also favour apoptosis through the generation of free radicals. The additive effect of reduced growth factor expression, increased extracellular matrix turnover, and nitric oxide generation may result in the fibroblast and vascular cell apoptosis seen during the rapid remodelling of this tissue.     

Localization of MT1-MMP, TIMP-1, TIMP-2, and TIMP-3 messenger RNA in normal, hyperplastic, and neoplastic endometrium. Enhanced expression by endometrial adenocarcinomas is associated with low differentiation

We studied membrane-type matrix metalloproteinase-1 (MT1-MMP), tissue inhibitor of metalloproteinase-1 (TIMP-1), TIMP-2, and TIMP-3 messenger RNA (mRNA) using in situ hybridization to elucidate their temporal and spatial expression patterns in normal, hyperplastic, and neoplastic endometrium. All mRNAs studied were expressed weakly in proliferating endometrium but were induced strongly in late secretory endometrium except MT1-MMP. Endometrial hyperplasia samples did not show increased MT1-MMP or TIMP mRNA expression, indicating that the overall expression patterns in hyperplasia are comparable to those in proliferating endometrium under estrogen effect and that synthesis of extracellular matrix proteins, rather than degradation, predominates in this condition. Exceptionally, stromal cells in areas of desquamation were seen to express focally intense MT1-MMP mRNA in hyperplasia samples. All mRNAs investigated were expressed increasingly in endometrial adenocarcinomas, especially in less differentiated carcinomas. Furthermore, gelatin zymography revealed higher functional degradative activities in carcinoma tissues than in normal endometrium. Our results indicate that MT1-MMP expression, together with that of TIMPs, is involved most notably in normal endometrium under progesterone effect and, without being connected to cyclic hormonal levels, has an important role in the invasive growth of endometrial adenocarcinomas.     

Differential effects of transforming growth factor-beta(s) and glial cell line-derived neurotrophic factor on gene expression of presenilin-1 in human post-mitotic neurons and astrocytes.

Mutations in the presenilin-1 gene are linked to the majority of early-onset familial Alzheimer's disease cases. We have previously shown that the expression of transforming growth factor-beta is altered in Alzheimer's patients, compared to controls. Here we examine presenilin- expression in human post-mitotic neurons (hNT cells), normal human astrocytes, and human brain tumor cell lines following treatment with three isoforms of transforming growth factor-beta, or glial cell line-derived neurotrophic factor, a member of the transforming growth factor-beta superfamily. As the NT2/D1 teratocarcinoma cell line is treated with retinoic acid to induce differentiation to hNT cells, presenilin-1 messenger RNA expression is dramatically increased. Furthermore, there is a 2-3-fold increase in presenilin-1 messenger RNA expression following treatment of hNT cells with growth factors and similar results are found by Western blotting and with immunohistochemical staining for presenilin-1 protein. However, treatment of normal human astrocytes with cytokines results in minimal changes in presenilin-1 messenger RNA and protein. Interestingly, the expression of presenilin-1 in human U87 MG astrocytoma and human SK-N-SH neuroblastoma cells is only increased when cells are treated with glial cell line-derived neurotrophic factor or transforming growth factor-beta3. These findings suggest that endogenous presenilin-1 gene expression in human neurons can be induced by growth factors present in normal and diseased brain tissue. Cytokines may play a major role in regulating expression of presenilin-1 which may affect its biological actions in physiological and pathological conditions.     

丹参单体IH764-3促进H2O2刺激的鼠肝星状细胞胶原降解

目的观察丹参单体IH764-3对鼠肝星状细胞株(HSCs)基质金属蛋白酶-13(MMP-13)及其组织抑制因子(TIMP-1)表达的影响。方法应用体外细胞培养技术,用RT-PCR检测HSCsMMP-13mRNA水平;原位杂交和Westernblotting技术分别检测上述细胞TIMP-1mRNA和蛋白水平。结果IH764-3干预2h组MMP-13mRNA的表达强度明显上调,同时TIMP-1mRNA表达受抑制;IH764-3干预24h组TIMP-1蛋白表达受抑制。结论丹参单体IH764-3诱导HSCsMMP-13表达,抑制其TIMP-1表达是其抗肝纤维化的作用机制之一。     

人脂肪干细胞来源外泌体对四氯化碳诱导肝纤维化模型大鼠的治疗作用

文题释义： 脂肪干细胞：是指从脂肪组织中分离得到的一种间充质干细胞,不但具有跨胚层多向分化潜能,在不同培养条件下可以分化成肌肉、软骨、脂肪组织、神经组织或肝脏组织,而且具备取材方便、来源广阔、增殖能力强、免疫原性低等优点,近年来成为干细胞治疗的热点。 外泌体：是一种细胞主动分泌的大小均一、直径为50-150 nm的脂质双分子层结构囊泡,可由树突细胞、淋巴细胞、成纤维细胞、间充质干细胞和肿瘤细胞等多种不同细胞类型释放。 背景：肝纤维化具有较高的发病率和死亡率,肝星状细胞的活化和增殖是肝纤维化进程中的关键环节。目前还没有针对单一环节或靶点的有效抗纤维化药物。 目的：分析人脂肪干细胞来源外泌体对四氯化碳诱导的大鼠肝纤维化的影响。 方法：①通过酶溶解法获取健康人群来源脂肪中干细胞,体外培养获取一定数量细胞后通过多重超滤法获取外泌体。体外培养的肝星状细胞经转化生长因子β1活化后利用不同浓度外泌体进行处理,通过定量PCR检测细胞内α-平滑肌动蛋白的表达明确其活化程度,以及分别使用CCK-8及流式细胞术检测各组外泌体处理后活化肝星状细胞的生长率及凋亡率。②通过腹腔注射四氯化碳构建肝纤维化大鼠动物模型,尾静脉注射外泌体进行治疗。检测各组动物的肝功能及血清Ⅲ型前胶原、Ⅳ型胶原,肝组织Ishak评分及肝纤维化半定量,以及通过免疫荧光法检测肝组织内基质金属蛋白酶组织抑制剂1、基质金属蛋白酶9及α-平滑肌动蛋白的表达。实验方案于2017年1月经同济大学动物实验伦理委员会以及医学伦理学委员会批准。 结果与结论：人脂肪干细胞来源外泌体可抑制活化的肝星状细胞增殖,其可能的机制为抑制活化巨噬细胞的增殖,减少胶原纤维、α-平滑肌动蛋白及基质金属蛋白酶组织抑制剂1的表达,并促进基质金属蛋白酶9的表达。提示外泌体可治疗四氯化碳诱导肝纤维化。 orcid: 0000-0002-7141-8135 (Li Hongchao) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Regulation of matrix metalloproteinases (MMPs) and their tissue inhibitors in human myometrial smooth muscle cells by TGF-beta1.

The objective of the present study was to determine whether transforming growth factor beta (TGF-beta) regulates the expression of matrix metalloproteinases (MMP) and the tissue inhibitor of MMP (TIMP) in myometrial smooth muscle cells. Using primary cultures of human myometrial smooth muscle cells we found that these cells express MMP-1, MMP-3, TIMP-1 and TIMP-2 mRNA and protein, with significantly higher values of TIMP than MMP. We also found that TGF-beta1 (1 ng/ml) increased the expression of TIMP-1 mRNA, while it reduced the expression of MMP-1 and MMP-3 mRNA, compared with untreated controls. In addition, TGF-beta1 slightly increased the production of TIMP-1, but not TIMP-2. Production of MMP-1 and MMP-3 was reduced by treatment with TGF-beta1, compared with the untreated control. A major portion of MMP-1 released into the culture-conditioned media was in complex with TIMP-1, and the levels of this complex were reduced by treatment with TGF-beta1. In conclusion, the data indicate that myometrial smooth muscle cells express MMP and TIMP mRNA and protein, and their expression is differentially regulated by TGF-beta1. Such a differential regulation of MMP and TIMP by TGF-beta may influence the rate of extracellular matrix (ECM) turnover following tissue injury, induced during myomectomy and Caesarean section, or in leiomyomas during growth.