Glycation cross-links inhibit matrix metalloproteinase-2 activation in vascular smooth muscle cells cultured on collagen lattice

Aims/hypothesis. Extracellular matrix glycation has been proposed to contribute to the arterial stiffness observed in aging and diabetes. We examined whether matrix protein glycation regulates the proleolytic process through the manipulation of matrix metalloproteinases (MMPs) activation, using collagen fibrils model. Methods. Vascular smooth muscle cells were cultured on control or glycated collagen fibrils. Matrix metalloproteinase-2 activation and the production of tissue inhibitors of metalloproteinase (TIMPs) were measured in the conditioned medium by using gelatin zymography and immunoblotting. Membrane type 1 matrix metalloproteinase (MT1-MMP) expression was also measured in cell lysates. Results. When smooth muscle cells were cultured on collagen fibrils, pro-MMP-2 processing to active form was observed in the conditioned medium in coincidence with the increased MT1-MMP expression and the suppressed TIMP-2 production. Culturing smooth muscle cells on glycated collagen fibrils inhibited MMP-2 activation and attenuated MT1-MMP expression without the alteration of TIMP-2 production compared with control fibrils, indicating the possible mechanism of the suppression of MT1-MMP expression for the inhibition of MMP-2 activation on glycated collagen fibrils. Inclusion of aminoguanidine, an inhibitor of cross-linking formation, during collagen glycation restored the MMP-2 activation, suggesting the role of cross-links on the inhibition of MMP-2 activation. Conclusion/interpretation. These observations suggest that glycation-induced cross-linking formation in interstitial collagen contributes to arterial stiffness in aging and diabetes through the manipulation of matrix metalloproteinase activation along with the reduction of the susceptibility to proteolytic enzymes. [Diabetologia (2001) 44: 433–436] Received: 16 October 2000 and in revised form: 18 December 2000     

TIMP-2、MMP-2和MT1-MMP在活化肝星状细胞中的表达及对细胞外基质合成分泌的影响

目的 研究金属蛋白酶组织抑制剂-2(TIMP-2)、基质金属蛋白酶-2(MMP-2)和膜型基质金属蛋白酶-1(MT1-MMP)在活化肝星状细胞(HSCs)中的表达,观察其对细胞外基质(ECM)合成分泌的影响.方法 原代分离培养大鼠HSCs活化后,分别给予40～160 pmol化学合成经修饰抗TIMP-2 siRNA进行干预,检测培养细胞上清液透明质酸(HA)、Ⅲ型前胶原(PCⅢ)和羟脯氨酸(Hyp)的含量,采用荧光实时定量PCR法检测TIMP-2、MMP-2、MT1-MMP、MMP-13、COL Ⅰ和COL Ⅲ mRNA的表达,western印迹检测TIMP-2、MT1-MMP和MMP-13蛋白表达及明胶酶谱法检测MMP-2蛋白表达.结果 应用化学合成经修饰抗TIMP-2 siRNA后,TIMP-2、MMP-2、MT1-MMP、COL Ⅰ和COL Ⅲ的表达明显降低,而MMP-13的表达则明显增加,培养细胞上清液中HA、PCⅢ和Hyp的含量也明显减少.结论 TIMP-2通过MT1-MMP介导MMP-2的活化,抑制TIMP-2的表达,MT1-MMP和MMP-2的表达随之降低,而HSCs合成分泌ECM也相应减少.     

High glucose concentration inhibits the expression of membrane type metalloproteinase by mesangial cells: possible role in mesangium accumulation

Aims/hypothesis. High glucose concentration decreases the degradation of mesangium matrix, an action substantially mediated by a reduction in the activities of the matrix metalloproteinases (MMPs). Metalloproteinase-2 is unique in that it is activated on the cell surface by one of the membrane type metalloproteinases (MT1-MMP), a process involving complex interactions with tissue inhibitor of metalloproteinase-2. The aim of this study was investigate the effects of glucose concentration on mesangial cell gene expression of MT1-MMP and its ability to modulate the activation of metalloproteinase-2. Methods. Gene expression was determined using competitive RT-PCR, protein expression of MMP-2 was measured by western blot and its activation by zymography. Concanavalin A, known to increase MT1-MMP expression was added in some experiments. Results. High glucose concentration decreased MT1-MMP gene expression (11.52 ± 1.63 and 4.84 ± 0.72 amol/μg RNA, 5 vs 25 mmol/l glucose, respectively) and decreased activation of MMP-2 by 30 % despite a twofold increase in gene expression of MMP-2. Concanavalin A increased expression of MT1-MMP and activation of MMP-2. Irrespective of whether MMP-2 was from endogenous or exogenous source there was an excellent correlation between the MT1-MMP expression and degree of MMP-2 activation, whereas the gene expression of TIMP-2 was not significantly altered by high glucose concentration or concanavalin A. Conclusions/interpretation. Our results indicate that in a high glucose milieu, suppression of MT1-MMP expression could explain the low MMP-2 activity in the presence of high MMP-2 expression. This process could contribute to the mesangium matrix accumulation in diabetic nephropathy. [Diabetologia (2000) 43: 642–648] Received: 18 November 1999 and in revised form: 17 January 2000     

Chronic hypoxia inhibits MMP-2 activation and cellular invasion in human cardiac myofibroblasts

Cardiac myofibroblasts are pivotal to adaptive remodelling after myocardial infarction (MI). These normally quiescent cells invade and proliferate as a wound healing response, facilitated by activation of matrix metalloproteinases, particularly MMP-2. Following MI these reparative events occur under chronically hypoxic conditions yet the mechanisms by which hypoxia might modulate MMP-2 activation and cardiac myofibroblast invasion have not been investigated. Human cardiac myofibroblasts cultured in collagen-supplemented medium were exposed to normoxia (20% O₂) or hypoxia (1% O₂) for up to 48 h. Secreted levels of total and active MMP-2 were quantified using gelatin zymography, TIMP-2 and membrane-associated MT1-MMP were quantified with ELISA, whole cell MT1-MMP by immunoblotting and immunocytochemistry and MT1-MMP mRNA with real-time RT-PCR. Cellular invasion was assessed in modified Boyden chambers and migration by scratch wound assay.In the human cardiac myofibroblast, MT1-MMP was central to MMP-2 activation and activated MMP-2 necessary for invasion, confirmed by gene silencing. MMP-2 activation was substantially attenuated by hypoxia (P < 0.001), paralleled by inhibition of myofibroblast invasion (P < 0.05). In contrast, migration was independent of either MT1-MMP or MMP-2. Reduced membrane expression of MT1-MMP (P < 0.05) was responsible for the hypoxic reduction of MMP-2 activation, with no change in either total MMP-2 or TIMP-2. In conclusion, hypoxia reduces MMP-2 activation and subsequent invasion of human cardiac myofibroblasts by reducing membrane expression of MT1-MMP and may delay healing after MI. Regulation of these MMPs remains an attractive target for therapeutic intervention.     

成纤维细胞与肺癌细胞相互作用对膜型基质金属蛋白酶-1及基质金属蛋白酶-2表达的影响

目的 研究胚肺成纤维细胞对肺癌H460细胞膜型基质金属蛋白酶-1(MTl-MMP)、基质金属蛋白酶-2(MMP-2)表达的影响.方法 采用Western blot方法检测各组MT1-MMP的表达.取其上清,采用酶联免疫吸附法检测各组细胞培养液中活性MMP-2的浓度.结果 H460细胞、胚肺成纤维细胞单独培养时均有MT1-MMP表达,但混合培养后MT1-MMP表达增强(P＜0.05).H460细胞、胚肺成纤维细胞单独培养时MMP-2均有分泌,混合培养MMP-2分泌增强(P＜0.05).结论 胚肺成纤维细胞和肺癌H460细胞相互作用能通过上调MT1-MMP、MMP-2的表达从而促进肺癌的侵袭和转移,这可能为肺癌侵袭转移的一个重要机制.     

Long-term overexpression of membrane type-1 matrix metalloproteinase and matrix metalloproteinase-2 in oleic acid-induced pancreatitis in rats

INTRODUCTION: The matrix metalloproteinase (MMP) plays important roles in extracellular matrix turnover. However, little is known about the roles of MMP-2 and type IV collagen, and the relationship between MMP-2 and membrane type-1 matrix metalloproteinase (MT1-MMP) during progressive destruction of acinar cells in pancreatitis. AIMS AND METHODOLOGY: To examine the serial changes in the expression and activity of MMP-2 and expression of MT1-MMP and tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in rats after induction of pancreatitis by intraductal infusion of oleic acid, and to determine protein concentrations by Western blot analysis and localization of type IV collagen by immunostaining. RESULTS: Gelatinolytic activity of pro-and active MMP-2 and concentrations of MT1-MMP protein, as determined by zymography and Western blot analysis, respectively, increased significantly from 6 hours to day 42 after intraductal infusion of oleic acid. TIMP-2 mRNA expression was significantly higher than that at time 0 throughout the study period, and gelatinolytic activity of active MMP-2 increased from day 3 to day 42. In addition, immunoreactivity for type IV collagen was detected as a discontinuous line along the basement membranes of ducts, vessels, tubular complexes, and acinar cells. CONCLUSION: Our findings indicate that long-term increases of gelatinolytic activity of active MMP-2 cause continuous disorganization of type IV collagen in basement membranes during progressive atrophy of pancreatic gland in oleic acid-induced pancreatitis, and that MT1-MMP and TIMP-2 work as activating factors during proMMP-2 activation. Moreover, basement membranes disorganization in the sustentacula of acinar cells and duct epithelia seems to participate in continuous derangement of acinar cells and duct epithelium.     

Expression of membrane-type matrix metalloproteinases in synovial tissue from patients with rheumatoid arthritis or osteoarthritis

We investigated the expression of membrane-type matrix metalloproteinase (MT-MMP) and matrix metalloproteinase (MMP) mRNAs in synovial tissue from patients with rheumatoid arthritis (RA, n = 5) or osteoarthritis (OA, n = 5) by Northern blot analysis. Northern analysis demonstrated strong expression of MT1-MMP, MT3-MMP, MMP-1, and MMP-3 and weak expression of MT2-MMP and MMP-8 in synovial tissue from patients with RA or OA. MT4-MMP was not detected. No significant difference was shown in the expression of MT-MMP mRNAs between RA and OA. Synovial tissue of RA or OA patients expressed MT-MMPs as well as MMPs. These results indicate that, in addition to MMPs, MT1-MMP, MT3-MMP, and probably MT2-MMP may play a role in the degradation of bone and cartilage matrix in RA and OA. Such information may provide a clue to the development of a novel therapeutic approach targeted on the prevention of joint destruction. Received: April 30, 2000 / Accepted: September 19, 2000     

1,25-二羟维生素D3对人成骨细胞基质金属蛋白酶及其抑制因子的作用

目的　研究 1, 25 二羟维生素D3 [ 1α, 25 (OH)2D3 ]对人成骨细胞基质金属蛋白酶(MMP) 1、MMP 2、膜型基质金属蛋白酶 1 (MT1 MMP)、基质金属蛋白酶抑制因子 1 (TIMP 1 )的影响,探讨 1α, 25(OH)2D3 调节骨代谢作用机制。方法　人成骨细胞用 1α, 25 (OH)2D3 干预。Western杂交检测MT1 MMP蛋白质表达。MMP 1、MMP 2、TIMP 1的分泌及MMP 2的活性用ELISA检测。Northern杂交检测维生素D受体、MT1 MMPmRNA表达。结果　 1α, 25 (OH)2D3 对人成骨细胞MMP 1、MMP 2、TIMP 1表达无影响, 10-10 ~ 10-8 mol/L 1α, 25 (OH)2D3 干预诱导成骨细胞MT1 MMP表达呈剂量依赖性 (P值均 <0 05);促进MMP 2激活呈剂量依赖性 [MMP 2活性分别为(42 3 ± 8 6)、(64 4 ±11 4)、(93 5 ±9 9)μg/L, P值均<0 05]。结论　由于MT1 MMP在骨吸收过程中起着关键作用, 1α, 25(OH)2D3 可通过诱导成骨细胞MT1 MMP表达刺激骨吸收。     

Coordinate cell-surface expression of matrix metalloproteinases and their inhibitors on cancer-associated myofibroblasts from malignant ascites in patients with gastric carcinoma

Purpose:The crucial role of tumor stroma in cancer cell invasion has been described in human carcinoma tissues. However, myofibroblastic invasion remains largely unexplored in malignant ascites. Purpose of this study is to investigate the spatial localization or regulation of matrix metalloproteinases (MMP-2, -7 -9, MT1-MMP) and their inhibitors (TIMP-2 and -4) on myofibroblasts from malignant ascites in 20 patients with gastric carcinoma. Methods: The quantitative flow cytometric analysis of MMPs or TIMPs on myofibroblasts was based on the percentage of double positive cells defined by anti MMPs or anti TIMPs, and anti α-smooth muscle actin (α-SMA) antibodies. Result: The results clearly showed that the coordination of the high level of cell-surface expression of secreted MMPs and TIMPs was noted on the α-SMA⁺ myofibroblasts. The finding suggests the possible formation of ternary complex, MT1-MMP/TIMPs/MMPs on the cells. The events might be a cause and result of activation processing of MMPs on the cells. Conclusion: This study provides the presence of invasive myofibroblasts with activated MMPs in close association with MMPs⁺ and TIMPs⁺ cancer cells and tumor-infiltrating lymphocytes from malignant ascites, emphasizing the importance of molecular cross-talk in tumor-host microenvironment for cancer invasion, metastasis and progression.     

Matrix metalloproteinase (MMP) expression by differentiated thyroid carcinoma of children and adolescents

The factor(s) that control metastasis of thyroid carcinoma are unknown, but the matrix metalloproteinases (MMPs) are excellent candidates. MMP-1, membrane-type-1 MMP (MT1-MMP), and tissue inhibitor of MMP-1 (TIMP-1) have all been implicated, but the site of production and importance are disputed. In vitro, normal thyroid cells secrete TIMP-1, while thyroid cancer cells secrete TIMP-1 and MMP-1. However, previous pathological studies identified MMP-1 and TIMP-1 only in the stroma surrounding thyroid carcinoma. These data suggest that thyroid carcinoma or tumor-associated inflammatory cells might secrete a factor(s) which stimulates MMP-1 or TIMP-1 expression by surrounding tissues. We hypothesized that MMP-1, MT1-MMP, and TIMP-1 would be directly expressed by thyroid carcinoma and might promote invasion or metastasis. We used immunohistochemistry to determine the expression of MMP-1, MT1-MMP, and TIMP-1 in 32 papillary thyroid carcinoma (PTC), 10 follicular thyroid carcinoma (FTC) and 13 benign thyroid lesions from children and adolescents. The intensity of staining was graded from absent (grade 0) to intense (grade 3). Average MMP-1 expression (mean relative intensity units+/-SE) was significantly greater among PTC (1.97+/-0.15; p=0.004) and FTC (2.2+/-0.25; p=0.006) compared to benign lesions (1.30+/-0.15); but there was no relationship between MMP-1 expression and invasion, metastasis, or recurrence. Expression of MT1-MMP and TIMP-1 was similar for benign and malignant lesions; but recurrent PTC expressed lower levels of TIMP-1 when compared to non-recurrent PTC (p=0.049). Only the expression of TIMP-1 correlated with the presence of tumor-associated lymphocytes (r=0.35, p=0.032). We conclude that MMP-1, MT1-MMP and TIMP-1 are all expressed by thyroid carcinoma and could be important in promoting recurrence.     

Enhanced Cell Surface Expression of Matrix Metalloproteinases and Their Inhibitors, and Tumor-Induced Host Response in Progression of Human Gastric Carcinoma

The cell surface and/or intracellular expression of the matrix metalloproteinases (MMP -2, 7, and -9 and MT1-MMP) and their inhibitors (TIMP-2 and -4) were investigated in tumor and tumor-infiltrating lymphocytes (TIL) in gastric carcinoma (n = 15) from the primary locus, metastatic gastric carcinoma (n = 20) from malignant ascites, and benign gastric mucosa (n = 20) for the control. The quantitative analysis was based on the percentage of positive cells by flow cytometry. The results clearly showed increased cell surface expression of MMP-2, -7, and -9, MT1-MMP, and TIMP-2 and -4 in both tumor cells and TIL during the development of invasion and/or metastasis of gastric carcinoma. There were equilateral correlations with cancer progression and frequency of cell surface expression of MMPs and their inhibitors, TIMPs, suggesting not only the aggressive nature of particularly metastatic gastric carcinoma, but also the presence of MMPs complexed with TIMPs on tumor cells and TIL. The enhanced cell surface expression of MMPs and TIMPs on TIL within metastatic carcinoma nests showed the result of a host response induced by tumors. These suggest that the increased cell surface expression of MMPs and TIMPs, and tumor-induced host response play a key role in gastric cancer invasion and/or metastasis.     

Membrane-type matrix metalloproteinase-1 (MT1-MMP) is down-regulated in estrogen-deficient rat osteoblast in vivo

Our previous study showed that estrogen stimulates membrane-type matrix metalloproteinases-1 (MT1-MMP) production in osteoblastic cells culture, but has no effect on MMP-2 and TIMP-2 synthesis. Osteoblast-derived MT1-MMP have been recently implied to play a role in bone metabolism by degrading tumor necrosis factor-alpha (TNF-alpha), resolving extracellular matrix and activating proMMP-2, which requires the process of activation mediated by MT1-MMP/tissue inhibitor of metalloproteinase (TIMP-2) complex on the cell surface. To investigate the mechanism of bone loss following estrogen deficiency, we examined the effects of estrogen on osteoblast synthesis of MT1-MMP, MMP-2 and TIMP-2. In situ hybridization and immunohistochemistry of rat bone samples were used to document the synthesis of MT1-MMP, MMP-2, and TIMP-2 mRNA and protein. Osteoblasts from distal femoral head showed an increase in the pattern of MT1-MMP mRNA and protein production in sham-operated controls and 17beta-estradiol (E2)-treated rats, compared with the ovariectomized group; the synthesis of MMP-2 and TIMP-2 mRNA and protein was unaffected. Our data show a down-regulation of MT1-MMP synthesis by osteoblast in vivo following estrogen withdrawal, and treatment with E2 resulted in induced MT1-MMP expression in vivo. There is evidence suggesting a role for MT1-MMP in the process of bone loss during the pathogenesis of osteoporosis.     

Plasma matrix metalloproteinase and tissue inhibitor of metalloproteinase in patients with agnogenic myeloid metaplasia or idiopathic primary myelofibrosis

Agnogenic myeloid metaplasia (AMM) is characterized by bone marrow fibrosis with abnormal accumulation of extracellular matrix components (ECM), which is dependent on the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). Twenty-five patients with AMM, 30 with essential thrombocythemia (ET), 12 with polycythemia vera (PV) and 20 normal control subjects were studied. AMM patients had decreased plasma levels of MMP-3 and marked elevated levels of TIMP-1, but MMP-1, MMP-2 and MMP-9 levels were not significantly different from control subjects. Elevated levels of plasma TIMP-1, but not MMPs, were found in ET and PV. Reduced MMP activity together with increased TIMP-1 activity may be essential in fibrosis formation.     

Nicorandil suppresses the increases in plasma level of matrix metalloproteinase activity and attenuates left ventricular remodeling in patients with acute myocardial infarction

Nicorandil, a hybrid K_ATP channel opener and nicotinamide nitrate, reduces no-reflow phenomenon and improves cardiac function in patients with acute myocardial infarction (AMI). We repoted that nicorandil suppresses radical formation in patients with AMI undergoing primary percutaneous coronary intervention (PCI). In the present study, we tested the hypothesis that nicorandil treatment suppresses MMP activities and predicts ventricular remodeling in AMI. Sixty-two patients with AMI were randomized into nicorandil pretreatment (n = 31) and control (n = 31) groups after admission and underwent primary PCI. Nicorandil was administered as a bolus injection (4 mg) followed by constant infusion (8 mg/h) for 24 h just after admission. On days 1, 2, and 14 after the onset of AMI, the plasma levels of matrix metalloproteinase (MMP)-2 and MMP-9 were measured by enzyme-linked immunosorbent assay and the activities by gelatin zymography. There were no differences in the baseline clinical characteristics between the two groups. On day 1, there were no differences in both MMP-2 and MMP-9 levels and their activities between the two groups. However, both MMP-2 and MMP-9 levels and their activities were significantly lower in nicorandil than in control group on day 2 (MMP-2 level, 1 014 ± 39 vs 1 174 ± 44 ng/ml; MMP-9 level, 17 ± 1 vs 23 ± 2 ng/ml; both P < 005) and on day l4 (MMP-2 level, 970 ± 38 vs 1 221 ± 44 ng/ml; MMP-9 level, 17 ± 1 vs 23 ± 1 ng/ml; both P < 0.05). Left ventricular end-diastolic volume index (LVEDVI) at acute phase was not different between the two groups. At 6 months after AMI, LVEDVI was significantly smaller in nicorandil than in the control group (83 ± 4 vs 96 ± 4 ml/m², P < 0.05). The change in LVEDVI from acute phase to 6 months was positively correlated with MMP-2 and MMP-9 levels and activities. Nicorandil suppresses the increases in MMP levels and activities and prevents the development of ventricular remodeling in AMI.     

Induction of membrane-type matrix metalloproteinase-1 stimulates angiogenic activities of bovine aortic endothelial cells

Matrix metalloproteinases (MMPs) have been reported to play critical roles in endothelial cell migration and matrix remodeling during the angiogenic process. Among these MMPs, membrane-type MMP-1 (MT1-MMP) is an important molecule that can trigger the invasion of tumor cells by activating MMP-2 on their plasma membrane. However, the precise involvement of MT1-MMP in the angiogenic process has not been determined. To investigate the roles of the MT1-MMP by the matrix remodeling of endothelial cells, MT1-MMP expression vector was transfected into bovine aortic endothelial cells (BAECs). Increased expression of MT1-MMP in BAECs enhanced the activation of MMP-2, invasion and migration of BAECs. Moreover, the capacity of tube formation was increased in MT1-MMP transfectants. However, cotransfection with antisense MT1-MMP expression vector abolished the effects of MT1-MMP overexpression. These observations indicate that MT1-MMP is involved in the angiogenic process of endothelial cells in vitro. This revised version was published online in June 2006 with corrections to the Cover Date.     

Activation of proMMP-2 and Src by HHV8 vGPCR in human pulmonary arterial endothelial cells

Idiopathic pulmonary arterial hypertension (iPAH) is associated with human herpesvirus 8 (HHV8) infection and demonstrates pathological angiogenesis similar to that observed with another HHV8-linked disease, namely Kaposi Sarcoma (KS). Importantly, the HHV8 encoded viral G-protein-coupled receptor (vGPCR) induces KS lesions in a murine model. Investigating the impact of vGPCR expression on the angiogenic activity of human pulmonary arterial endothelial cells (HPAEC) can yield insight into the pathobiology of HHV8-associated vascular disorders, particularly PAH. Cultured HPAECs were transduced with retroviral vectors carrying either control or vGPCR coding regions. vGPCR expression selectively activated matrix metalloproteinase (MMP)-2, a pivotal matrix modulating enzyme during angiogenesis. A membrane type 1 MMP (MT1-MMP) neutralizing antibody and the tissue inhibitor of metalloproteinases-2 (TIMP-2) independently blocked vGPCR-induced MMP-2 activation. vGPCR expression concordantly promoted MMP-2 activation by increasing MT1-MMP expression while decreasing TIMP-2 expression. vGPCR activated Src kinase as demonstrated by phosphorylation of Src and its substrate focal adhesion kinase (FAK). vGPCR promoted angiogenesis of HPAECs as demonstrated by a substantial increase in tubulogenesis in vitro. The Src inhibitors PP2 and SU6656 significantly diminished vGPCR-induced MMP-2 activation and tubulogenesis. Our findings indicate that vGPCR induces MMP-2 activation in HPAECs through regulation of MT1-MMP and TIMP-2 expression. vGPCR activates Src and inhibition of such activation abrogates proMMP-2 activation and in vitro angiogenesis induced by vGCPR. The current study implicates vGPCR as an etiological agent in iPAH and identifies Src and MMP-2 as potential therapeutic targets in HHV8 associated KS and iPAH.     

Eotaxin-induced expression of membrane type 1 matrix metalloproteinase mRNA in human eosinophils

Eosinophil penetration across the basement membrane (BM) is thought to be dependent on the degradation of membrane components. In this process, matrix metalloproteinases (MMP) appear to be primarily responsible for degradation of the BM. Matrix metalloproteinases -2 and MMP-9 degrade type IV collagen, which is a major component of the BM. In the present study, the effects of eotaxin, a selective chemoattractant for eosinophils, on the expression of MMP mRNA were examined. Incubation with chemotactically active concentrations of eotaxin for 24 h enhanced the expression of mRNA for membrane-type 1 MMP (MT1-MMP), but not of mRNA for MMP-2 and MMP-9. An increase in the protein level of MT1-MMP was also detected in the cell lysate of eotaxin-treated eosinophils. These results suggest that up-regulation of MT1-MMP expression may be involved in the eotaxin-induced penetration of eosinophils.