Serum levels of matrix metalloproteinases: implications in clinical neurology

Matrix metalloproteinases (MMPs) are zinc-dependent enzymes involved in remodeling extracellular matrix and cell-matrix interactions. A pathogenic role of MMPs in neurological disorders is likely. This paper focuses on serological clinical aspects only. In multiple sclerosis, higher serum MMP-3 is seen during relapses. Lower serum MMP-8 and -9 levels correlate with fewer contrast-enhanced T(2)-weighted MRI lesions, and serum MMP-9 can be used in monitoring treatment. In myasthenia gravis, serum MMP-2, -3, and -9 levels are elevated in both generalized and ocular diseases. A proportion of the patients have markedly increased serum MMP-3. In acute stroke, higher serum MMP-9 correlates with larger infarct volume, stroke severity, and worse functional outcome, and serum MMP-3 is significantly lower than in several other neurological disorders and healthy controls. In amyotrophic lateral sclerosis, serum MMP-2 correlates with disease progression, and both serum MMP-1 and -2 are elevated. In Alzheimer's disease, serum MMP-3, -9, and -10 are elevated. In migraine, serum MMP-2 is elevated, and also MMP-9 in those patients with migraine without aura. MMP-9 is implicated in the pathogenesis of experimental epilepsy. A pathogenic role of MMPs in these conditions could be related to their ability to degrade extracellular matrix. MMPs may also facilitate autoimmunity.     

MMP-9 and/or TIMP as predictors of ischaemic stroke in patients with symptomatic and asymptomatic atherosclerotic stenosis of carotid artery treated by stenting or endarterectomy – A review

We still lack an optimal tool to predict ischaemic stroke in patients with symptomatic and asymptomatic carotid stenosis (CS). It has already been shown that patients at increased risk of ischaemic stroke can be identified based on the elevated plasma levels of metalloproteinases (MMPs) and reduced activity tissue inhibitor of metalloproteinase (TIMP). There are few studies presenting the role of MMP-9 and TIMP in ischaemic stroke both in patients with symptomatic and asymptomatic CS treated with stenting or endarterectomy, however we have not found any published review summarizing the role of abovementioned markers. MEDLINE was accessed via Pub Med, and searched for published studies that analyzed MMP-9 and TIMP levels in patients with asymptomatic and symptomatic internal carotid stenosis and/or examined these parameters as potential risk markers for ischaemic stroke. A total of 13 articles documenting the outcomes of patients with symptomatic or asymptomatic carotid stenosis treated by carotid stenting or endarterectomy, were analyzed. Statistically significant differences in the levels of MMP-9 and/or TIMP in patients with symptomatic and asymptomatic CS have been reported. Also the concentrations of MMP-9 and TIMP in CS patients subjected to stenting or endarterectomy were higher than in baseline group. Moreover higher levels of MMP-9 and decreased TIMP was reported to be associated with the risk of restenosis. This systematic review shows that available evidence regarding the dynamics of MMP-9 and TIMP levels may be a predictor of cerebrovascular events in both symptomatic and asymptomatic carotid stenosis in patients treated with stenting or endarterectomy.     

速避凝与丹参对缺血性脑卒中患者血浆中基质金属蛋白酶-9的影响

目的 通过对分别采用速避凝和丹参治疗的两组缺血性脑卒中患者血浆中的基质金属蛋白酶-9(MMP-9)水平的测定,探讨速避凝和丹参对缺血性脑卒中患者血浆中MMP-9含量的影响。方法 选取32例发病时间在24小时内的脑卒中急性期病例,按年龄匹配原则随机分成速避凝组16例,丹参组16例;采用酶联免疫吸附检测方法(ELISA)测定脑缺血后24小时内、第3天和第7天时血浆中MMP-9的含量。结果 脑缺血后24小时内(治疗前)、治疗后第3天和第7天时两组血浆内MMP-9含量都在上升;第3天和第7天时的含量均比发病时显著升高(P<0.001),第7天的含量比第3天的含量略高一点,但无明显差异(P>0.05);速避凝组治疗后3天内MMP-9含量增加值小于相同时间的丹参治疗组(P<0.05);7天内MMP-9水平上升值两组之间无显著差异(P=0.297)。结论 速避凝与丹参不能抑制或阻止缺血性脑卒中患者血浆中MMP-9含量上升;与丹参治疗组相比,速避凝能减少患者血浆中早期MMP-9含量的增加。     

Serum levels of matrix metalloproteinases-2 and -9 and their tissue inhibitors in inflammatory neuromuscular disorders

We monitored serum levels of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) before and during intravenously applied immunoglobulin (IVIG) therapy in 33 patients with chronic immune-mediated neuropathies and myopathies and 15 controls. Baseline MMP-2 and TIMP-2 serum levels were lower and MMP-9 and TIMP-1 serum levels higher in all patients compared to age-matched controls. Eight days after IVIG treatment, MMP-2, TIMP-2, and TIMP-1 serum levels increased, while MMP-9 serum levels decreased, indicating tissue repair. After 60 days, MMP-9 levels increased, MMP-2 approached normal levels, while TIMP-1 and TIMP-2 serum levels were below day 8 levels, indicating relapsing tissue damage. Comparing the MMP/TIMP results with the clinical courses, IVIG treatment tended to change MMP/TIMP levels in a way that paralleled clinical improvement and relapse. In sum, during a distinct time period, IVIG therapy seems to be able to modulate MMP-mediated tissue repair.     

MMP-2 and MMP-9 levels in peripheral blood after subarachnoid hemorrhage

MMPs play an important role in ischemic and hemorrhagic stroke. We analyzed replicate serum samples from 20 normal healthy individuals to assess reproducibility of MMP determinations, and found that MMP-2 and MMP-9 determinations were quite consistent. We then studied the serum levels of MMP-2 and MMP-9 in patients suffering from subarachnoid hemorrhage (SAH), another stroke subtype. Serum MMP-2 and MMP-9 levels from SAH patients were measured sequentially using gelatine zymography in 11 patients after acute SAH. The occurrence of intracerebral aneurysms and vasospasms and the initial Hunt and Hess score were analysed in relation to MMP-levels. MMP-2 levels are significantly decreased while MMP-9 levels are increased in SAH patients relative to controls. MMP-2 levels remain depressed out to day 12 post SAH, but MMP-9 levels may recover by day 12.     

Plasma MMP-2 and MMP-9 and their inhibitors TIMP-1 and TIMP-2 during human orthotopic liver transplantation. The effect of aprotinin and the relation to ischemia/reperfusion injury

Uncontrolled activation of matrix metalloproteinases (MMPs) can result in tissue injury and inflammation, yet little is known about the activation of MMPs during orthotopic liver transplantation (OLT). OLT is associated with increased fibrinolytic activity due to elevated plasmin generation. The serine-protease plasmin not only causes degradation of fibrin clots but is also thought, amongst others, to play a role in the activation of some matrix metalloproteinases. We therefore studied the evolution of MMP-2 and -9 plasma concentrations during OLT and the effect of serine-protease inhibition by aprotinin on the level and activation of these MMPs. In a group of 24 patients who participated in a randomized, double-blind, placebo-controlled study we determined serial MMP-2 and MMP-9 plasma levels during transplantation using ELISA (total MMP), activity assays (activatable MMP) and zymography. In addition, the MMP-inhibitors TIMP-1 and TIMP-2 were assessed by ELISA. The putative regulating factors tumor necrosis factor alpha (TNF-alpha) and tissue-type plasminogen activator (t-PA) were assessed as well. Patients were administered high-dose aprotinin, regular-dose aprotinin or placebo during surgery. Plasma TIMP-1, TIMP-2 and MMP-2 level gradually decreased during transplantation. Approximately two-thirds of total MMP-2 appeared to be in its activatable proMMP form. No release of MMP-2 from the graft could be detected. In contrast, plasma levels of MMP-9 increased sharply during the anhepatic and postreperfusion periods. Peak MMP-9 levels of about eight times above baseline were found at 30 minutes after reperfusion. Most MMP-9 appeared to be in its active/inhibitor-complexed form. No significant differences were observed between the three treatment groups. However, in patients with more severe ischemia/reperfusion (I/R) injury the MMP-9 concentration, particularly of the active/inhibitor-complexed form, remained high at 120 minutes postreperfusion compared to patients with no or mild I/R injury. The decrease in plasma levels of MMP-2, TIMP-1 and TIMP-2 during OLT occurred irrespective of the severity of the I/R injury. There was a significant correlation between MMP-9 and t-PA levels, but not with TNF-alpha. In conclusion, OLT is associated with a sharp increase of MMP-9 during the anhepatic and postreperfusion periods, which coincided with the changes in t-PA. MMP-2, TIMP-1 and TIMP-2 gradually decreased during OLT. The composition of these MMPs was not altered by the use of aprotinin, suggesting that serine-protease/plasmin-independent pathways are responsible for MMP regulation during OLT. In addition, only MMP-9 seems to be involved in I/R injury during human liver transplantation.     

Course of matrix metalloproteinase-9 isoforms after the administration of uric acid in patients with acute stroke

Abstract   Oxidative stress as well as expression and activity of matrix metalloproteinase 9 (MMP-9) are rapidly enhanced after cerebral ischemia. The magnitude of these effects is related to stroke outcome. In human stroke, the extent of oxidative stress correlates well with increased MMP-9 expression. The aim of this study was to evaluate whether treatment with the antioxidant molecule uric acid (UA) decreased the levels of MMP-9 in stroke patients treated with rtPA. The patients were part of a pilot, double-blind, randomized, vehiclecontrolled study of patients with acute stroke treated with rtPA (< 3 h) and randomized to receive an intravenous infusion of UA (n = 16) or vehicle (n = 8). Total matrix metalloproteinase (tMMP)-9 and active (aMMP-9) levels were measured in serum at baseline (< 3 h), at the end of study treatment infusion (< 5.5 h), and at 48 hours. Total MMP-9 and aMMP-9 increased very early after stroke onset in patients allocated vehicle after rtPA therapy. Lower increments of aMMP-9 were associated with better outcome at 3 months. UA treatment was associated with reduced levels of aMMP-9 at T1 (p < 0.02) in multivariate models adjusted for age, NIHSS score, and baseline aMMP-9 levels. The decline of aMMP-9 attained after UA administration supports further clinical assessment of UA therapy in patients with acute stroke.     

Increased matrix metalloproteinase-9 activity in unstable carotid plaques. A potential role in acute plaque disruption

BACKGROUND AND PURPOSE: Acute disruption of atherosclerotic plaques precedes the onset of clinical syndromes, and studies have implicated a role for matrix metalloproteinases (MMPs) in this process. The aim of this study was to establish the character, level, and expression of MMPs in carotid plaques and to correlate this with clinical status, cerebral embolization, and histology. METHODS: Plaques were obtained from 75 consecutive patients undergoing carotid endarterectomy and divided into 4 groups according to symptomatology (group 1, asymptomatic; group 2, symptomatic >6 months before surgery; group 3, symptomatic within 1 to 6 months; group 4, symptomatic within 1 month). All patients underwent preoperative and intraoperative transcranial Doppler monitoring. Plaques were subjected to histological examination and quantification of MMPs by zymography and ELISA. RESULTS: The level of MMP-9 was significantly higher in group 4 (median 125.7 ng/mL for group 4, median <32 ng/mL for all other groups; P=0.003), with no difference in the levels of MMPs 1, 2, or 3. Furthermore, the MMP-9 concentration was significantly higher in plaques undergoing spontaneous embolization (P=0.019) and those with histological evidence of plaque instability (P<0.03). In situ hybridization demonstrated increased MMP-9 expression in highly symptomatic plaques in areas of intense inflammatory infiltrate. CONCLUSIONS: The concentration, production, and expression of MMP-9 is significantly higher in unstable carotid plaques. If this proves to be a causal relationship, MMP-9 may be a strong candidate for pharmacotherapy aimed at stabilizing plaques and preventing stroke.     

Hemorrhagic transformation after ischemic stroke in animals and humans

Hemorrhagic transformation (HT) is a common complication of ischemic stroke that is exacerbated by thrombolytic therapy. Methods to better prevent, predict, and treat HT are needed. In this review, we summarize studies of HT in both animals and humans. We propose that early HT (<18 to 24 hours after stroke onset) relates to leukocyte-derived matrix metalloproteinase-9 (MMP-9) and brain-derived MMP-2 that damage the neurovascular unit and promote blood–brain barrier (BBB) disruption. This contrasts to delayed HT (>18 to 24 hours after stroke) that relates to ischemia activation of brain proteases (MMP-2, MMP-3, MMP-9, and endogenous tissue plasminogen activator), neuroinflammation, and factors that promote vascular remodeling (vascular endothelial growth factor and high-moblity-group-box-1). Processes that mediate BBB repair and reduce HT risk are discussed, including transforming growth factor beta signaling in monocytes, Src kinase signaling, MMP inhibitors, and inhibitors of reactive oxygen species. Finally, clinical features associated with HT in patients with stroke are reviewed, including approaches to predict HT by clinical factors, brain imaging, and blood biomarkers. Though remarkable advances in our understanding of HT have been made, additional efforts are needed to translate these discoveries to the clinic and reduce the impact of HT on patients with ischemic stroke.     

Serum levels of matrix metalloproteinase-9 and its tissue inhibitor (TIMP-1) in acute disseminated encephalomyelitis

In multiple sclerosis, there have been many reports on matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). However, MMPs and TIMPs have not been reported in acute disseminated encephalomyelitis (ADEM). We determined the relationship between the serum concentrations of MMP-9 and TIMP-1 and activity of lesions on MRI in 14 patients with ADEM to investigate the roles of MMP-9 and TIMP-1 in the pathogenesis of ADEM. Serum MMP-9 and TIMP-1 levels, measured by ELISA and gadolinium-enhanced (Gd+) brain MRI, were analyzed. Serum MMP-9 and TIMP-1 levels at the acute stage were higher than controls, and the serum MMP-9 levels at the acute stage were higher than those at the convalescent stage in ADEM. In seven patients with Gd+ lesions on brain MRI, serum MMP-9 levels and the MMP-9/TIMP-1 ratio at the acute stage were higher than those at the convalescent stage, and serum TIMP1 levels at the acute stage were lower than those at the convalescent stage. In seven patients without Gd+ lesions on brain MRI, serum TIMP-1 levels at the acute stage were higher than those at the convalescent stage. We speculated that MMP-9 is related to lesion formation at the early stage in ADEM and that TIMP-1 is induced to modulate MMP-9 activity. These findings suggest that MMP-9 and TIMP-1 secondarily play some roles in the inflammatory cascade of ADEM.