Melatonin inhibits matrix metalloproteinase‐9 activity by binding to its active site

The zinc‐dependent matrix metalloproteinases (MMPs) are key enzymes associated with extracellular matrix (ECM) remodeling; they play critical roles under both physiological and pathological conditions. MMP‐9 activity is linked to many pathological processes, including rheumatoid arthritis, atherosclerosis, gastric ulcer, tumor growth, and cancer metastasis. Specific inhibition of MMP‐9 activity may be a promising target for therapy for diseases characterized by dysregulated ECM turnover. Potent MMP‐9 inhibitors including an indole scaffold were recently reported in an X‐ray crystallographic study. Herein, we addressed whether melatonin, a secretory product of pineal gland, has an inhibitory effect on MMP‐9 function. Gelatin zymographic analysis showed a significant reduction in pro‐ and active MMP‐9 activity in vitro in a dose‐ and time‐dependent manner. In addition, a human gastric adenocarcinoma cell line (AGS) exhibited a reduced (~50%) MMP‐9 expression when incubated with melatonin, supporting an inhibitory effect of melatonin on MMP‐9. Atomic‐level interaction between melatonin and MMP‐9 was probed with computational chemistry tools. Melatonin docked into the active site cleft of MMP‐9 and interacted with key catalytic site residues including the three histidines that form the coordination complex with the catalytic zinc as well as proline 421 and alanine 191. We hypothesize that under physiological conditions, tight binding of melatonin in the active site might be involved in reducing the catalytic activity of MMP‐9. This finding could provide a novel approach to physical docking of biomolecules to the catalytic site of MMPs, which inhibits this protease, to arrest MMP‐9‐mediated inflammatory signals.     

Induced sputum matrix metalloproteinase-9 correlates with lung function and airway inflammation in children with cystic fibrosis

Matrix metalloproteinases (MMPs) degrade extracellular matrix and are implicated in causing airway damage in chronic inflammatory lung diseases, including cystic fibrosis (CF). Our primary objective was to examine the relationship between matrix metalloproteinase-9 (MMP-9) and pulmonary function, as measured by forced expiratory volume in 1 sec (FEV1), in children with CF. We measured MMP-9 and its natural tissue inhibitor of metalloproteinase-1 (TIMP-1) in induced sputum from 18 clinically stable CF children with normal to mildly abnormal lung function and 7 healthy control children. Measures of airway inflammation from induced sputum included cell counts and differentials, interleukin-8 (IL-8), neutrophil elastase, MMP-9, and TIMP-1. Infection was assessed through quantitative bacterial counts. Induced sputum levels of MMP-9 and TIMP-1 were significantly increased in children with CF compared with healthy controls. Also, the MMP-9/TIMP-1 molar ratio was higher in the CF group. Among CF children, there was a significant inverse relationship between MMP-9 and FEV1. In addition, sputum MMP-9 and TIMP-1 concentrations significantly correlated with total white cells and neutrophils, IL-8, and neutrophil elastase. Neither MMP-9 nor TIMP-1 correlated with airway infection. We conclude that clinically stable CF children with normal to mildly abnormal lung function have an increased burden of MMP-9 in their airways. The observed relationships of MMP-9 with lung function and other measures of airway inflammation suggest that this enzyme may be a useful marker of airway injury and airflow obstruction in persons with CF.     

MMP‐9 and TIMP‐1 in the cord blood of premature infants developing BPD

We investigated matrix metalloproteinase‐9 (MMP‐9) and tissue inhibitor of metalloproteinase 1 (TIMP‐1) levels in the cord blood of 29 premature infants who were <30 weeks gestation. One, 8, and 14 infants developed severe, moderate and mild bronchopulmonary dysplasia (BPD), respectively, and 6 did not. MMP‐9 and TIMP‐1 levels in the cord blood were determined by ELISA. MMP‐9/TIMP‐1 ratios in the cord blood of infants who developed severe or moderate BPD (n = 9) were significantly higher than those who developed mild BPD or did not develop BPD (n = 20; P = 0.015). Multivariate linear regressions demonstrated that MMP‐9 levels and MMP‐9/TIMP‐1 ratios in the cord blood of the premature infants correlated with the oxygen supplementation period (r = 0.58, P = 0.003 and r = 0.41, P = 0.030, respectively). The MMP‐9 levels and MMP‐9/TIMP‐1 ratios correlated with the severity of maternal chorioamnionitis (both trend P = 0.006). The MMP‐9 levels and MMP‐9/TIMP‐1 ratios in the cord blood may be related to the pathogenesis and severity of BPD and maternal chorioamnionitis. Pediatr Pulmonol. 2009; 44:267–272. © 2009 Wiley‐Liss, Inc.     

脑梗死患者外周血血清和血浆中白细胞基质金属蛋白酶9及基质金属蛋白酶组织抑制因子1水平差异分析

目的采用酶联免疫吸附法测定脑梗死患者外周血血清和血浆中白细胞基质金属蛋白酶9（MMP9）和基质金属蛋白酶组织抑制因子1（TIMP-1）水平的差异。方法采用无促凝剂和含抗凝剂的采血管抽取脑梗死患者和健康体检者血液,检测血清、血浆MMP9和TIMP-1水平,并进行统计分析。结果外周血MMP9及TIMP1血清与血浆水平存在差异,血清MMP9和TIMP1的水平高于血浆（P〈0.01）。同时,与对照组比较,脑梗死患者MMP9血浆水平显著增加,而TIMP-1血浆水平明显减低,差异具有统计学意义（P〈0.01）。结论血浆水平MMP9和TIMP-1更适合作为脑组织损伤的潜在生物学标志,采血方法的选择对实验结果的影响不容忽视。     

Prognostic significance of p53 and matrix metalloproteinase-9 expression in follicular lymphoma

Objectives: p53 mutations and high protein expression are associated with adverse prognosis in several lymphoma subtypes. Matrix metalloproteinase‐9 (MMP‐9) has also been found to correlate with poor survival in all lymphomas studied. The data concerning the clinical role of protein expression of p53 or gelatinases and their inhibitors in follicular lymphoma are rare. The purpose of this study was to evaluate the prognostic and clinical implications of the immunoreactive proteins p53, MMP‐2, MMP‐9, tissue inhibitor of matrix metalloproteinase‐1 (TIMP‐1) and TIMP‐2 in follicular lymphoma. Methods: The material consisted of 67 patients with primarily non‐transformed follicular lymphoma. Diagnostic lymph node tissue sections of patients were stained by immunohistochemical method using specific monoclonal antibodies. Results: p53 over‐expression was detected in 8 (12%) out of 67 cases. p53 over‐expression correlated with high grade (P = 0.011), bulky tumour (P = 0.031) and forthcoming transformation (P = 0.001). It also correlated with poor overall (P = 0.001) and cause‐specific survival (P = 0.010) in multivariate analysis and had a strong inverse correlation with time to transformation (P < 0.001). MMP‐2, MMP‐9 and TIMP‐2 expression correlated with high grade. MMP‐9 positivity in centroblasts correlated with good chemotherapy response (P = 0.019), but it was not prognostic for survival. MMP‐2, TIMP‐1 or TIMP‐2 did not associate with survival, either. Conclusions: In this study, p53 over‐expression predicted both transformation to diffuse large B‐cell lymphoma and poorer overall and cause‐specific survival of patients with follicular lymphoma. Expression of gelatinases or their inhibitors did not have any significant correlations with prognosis, although MMP‐9 predicted a good response to first‐line chemotherapy.     

血清基质金属蛋白酶9和组织基质金属蛋白酶抑制剂1与急性脑梗死的临床关系

目的探讨脑梗死患者血清基质金属蛋白酶9(MMP-9)和组织基质金属蛋白酶抑制剂1(TIMP-1)的动态变化及对临床预后的影响。方法选择急性脑梗死患者60例,按照TOAST分型方法将脑梗死患者分为3组,心源性脑栓塞(CE)组,大动脉粥样硬化性卒中(LAA)组,腔隙性脑梗死(SA)组,每组20例;另选健康体检者20例作为对照组,分别测定急性脑梗死患者发病24 h内,第5、10天的血清MMP-9、TIMP-1含量,记录患者入院时的美国国立卫生研究所脑卒中量表(NIHSS)评分;记录发病1、6个月时的Barthal指数(BI)来评价顸后。结果发病后24 h内,脑梗死各组患者血清MMP-9、TIMP-1含量较对照组均明显升高(P<0.05),其中,CE组和LAA组MMP-9、TIMP-1含量持续至第5天仍未下降.而SA组已逐渐降至正常水平。发病后24 h内血清MMP-9含量与相应时间段NIHSS评分呈正相关。近期预后较好患者发病24 h内血清MMP-9含量明显低于预后较差患者(P<0.05)。结论MMP-9与病情的严重程度有关。脑梗死后24 h内的血清MMIP-9含量是预后的独立预测因素。     

Serum matrix metalloproteinase-1 in patients with chronic viral hepatitis

BACKGROUND AND AIMS: Previously we found that serum matrix metalloproteinase (MMP)-1 activity decreased with progression of chronic liver disease. Our objectives in the present study were to observe the change in the serum MMP-1 protein concentration using recently developed specific enzyme immunoassays for MMP-1 and MMP-1 complexed with tissue inhibitor of metalloproteinases (TIMP)-1 and to elucidate the clinical usefulness of the serum MMP-1 test in chronic viral hepatitis. We measured the serum concentrations of MMP-1 and MMP-1/TIMP-1 complex using these immunoassays in 64 patients with histologically characterized chronic viral hepatitis. RESULTS: Serum MMP-1 concentration was inversely related to the histological severity of chronic hepatitis (P< 0.0001). It was closely associated with the histological degree of periportal necrosis (P< 0.0001), intralobular necrosis (P< 0.005), portal inflammation (P<0.0001) and liver fibrosis (P< 0.05). The serum concentration of MMP-1/TIMP-1 complex was also related to the histological severity of chronic hepatitis (P< 0.0001). It was associated with the degree of portal inflammation (P< 0.05), but not with the degree of periportal necrosis, intralobular necrosis or liver fibrosis. As serum MMP-1 level was closely associated with the histological degree of necroinflammation, we examined the ability of the serum MMP-1 test to differentiate active and inactive forms of hepatitis with a receiver operating curve. The results were compared with those of serum procollagen type III N-peptide (PIIINP) test. We found that the serum MMP-1 test was superior to the serum PIIINP test in assessing liver necroinflammation. CONCLUSIONS: In addition to the previously reported changes in enzyme activity, MMP-1 proteins in serum decreased during histological progression of chronic hepatitis. The serum MMP-1 test may be useful clinically to differentiate active and inactive types of hepatitis in patients with chronic viral hepatitis.     

Role of melatonin in regulating matrix metalloproteinase-9 via tissue inhibitors of metalloproteinase-1 during protection against endometriosis

Abstract:  Endometriosis is a gynecological disease of women and plausibly regulated by matrix metalloproteinases (MMPs). However, mechanisms of alterations in MMPs during endometriosis remain unclear. Human endometriotic tissues possessing varying degrees of severity were examined for expression of MMPs and tissue inhibitors of metalloproteinase (TIMP)-1. In addition, endometriosis was generated in mice and endometriotic tissues were tested for MMP-9 activity. Results show significant upregulation of secreted and synthesized proMMP-9 activity with duration and severity of endometriosis. Along with upregulation of activity, the expression of proMMP-9 was found increased while TIMP-1 expression followed an inverse trend. The effect of melatonin, a major secretory product of the pineal gland, on endometriosis was examined in preventive and therapeutic models in mice. The results show that melatonin arrested lipid peroxidation and protein oxidation and downregulated proMMP-9 activity and expression in a time and dose-dependent manner while protecting and regressing peritoneal endometriosis. Moreover, the attenuated activity and expression of proMMP-9 were associated with subsequent elevation in the expression of TIMP-1. Our study reveals for the first time the role of melatonin in arresting peritoneal endometriosis in mice and a novel marker, expression ratio of proMMP-9 versus TIMP-1, was identified for assessing severity and progression of endometriosis.     

Early postnatal dexamethasone influences matrix metalloproteinase-2 and -9, and their tissue inhibitors in the developing rat lung

In order to test the hypothesis that early postnatal exposure to dexamethasone (Dex) influences matrix metalloproteinases (MMP)-2 and -9, as well as their tissue inhibitors (TIMP-1 and -2) in the developing rat lung, newborn rats (3 litters/group) were treated with low Dex (0.1 mg/kg/day, IM), high Dex (0.5 mg/kg/day), or equivalent volumes of saline at 5 days postnatal age (P5), P6, and P7. Lung weight and lung MMP and TIMP levels were determined at sacrifice (7 days postinjection, P14; at weaning, P21; and at adolescence, P45, n = 10/group and time). Dex did not adversely affect lung weight or lung MMP-2 levels, which peaked in all groups at P21 and then fell by P45. In contrast, Dex decreased TIMP-2 at all time intervals, but achieved statistical significance only at P45. An imbalance in MMP-2/TIMP-2 ratio was noted at P21, with elevations occurring in the low and high Dex-treated groups. Lung MMP-9 levels remained comparable with controls during low Dex treatment. However, high Dex exposure resulted in elevated lung MMP-9 levels at P21 and P45. Lung TIMP-1 levels increased only with high Dex exposure at P14 and P21, whereas the lung MMP-9/TIMP-1 ratio was elevated at P21 in the high Dex group, and at P45 in both Dex-treated groups. These data provide evidence that early postnatal dexamethasone results in an imbalance between gelatinase-A and -B, and their tissue inhibitors in the developing rat lung. These changes may be responsible, in part, for some of the known maturational effects of steroids on lung structure in the newborn.