Matrix metalloproteinases and tissue inhibitors of metalloproteinases expression in human cerebral ruptured and unruptured aneurysm

doi:10.1016/j.surneu.2007.02.060

Surgical Neurology

Volume 68, Supplement 2, December 2007, Pages S11-S16

https://doi.org/10.1016/j.surneu.2007.02.060 Get rights and content

Abstract

Backround

Matrix metalloproteinases and TIMPs are potent elastases and collagenases, which regulate the remodeling of vascular and play an important role in the development of cerebral aneurysm. Until now, little quantitative data regarding MMPs and TIMPs exist.

Methods

Tissue samples of cerebral aneurysm were obtained from 30 patients who underwent cerebral aneurysm clipping operation. We used real-time RT-PCR method to quantitatively measure mRNA levels in small tissue samples and determined gene expression levels of MMPs and TIMPs relative to that of GAPDH in each sample. The ELISA method has been used to measure the serum level of MMP-2 and MMP-9 in patients with cerebral ruptured aneurysm and patients with unruptured aneurysm.

Result

Matrix metalloproteinase-2 and MMP-9 were overexpressed in cerebral ruptured aneurysm compared with unruptured aneurysm (4.28 ± 2.01 vs 0.16 ± 0.12 [P < .01] and 5.21 ± 0.87 vs 1.69 ± 1.00 [P < .05], respectively). The expression levels of MMP-2 to TIMP-1, MMP-2 to TIMP-2, MMP-2 to TIMP-3, and MMP-9 to TIMP-2 were higher in cerebral ruptured aneurysms than in unruptured aneurysms (1.22 ± 0.53 vs 0.18 ± 0.05, 4.23 ± 1.32 vs 0.53 ± 0.12, 1.69 ± 0.49 vs 0.18 ± 0.02, and 7.61 ± 1.61 vs 2.76 ± 0.76, respectively; P < .05). Patients with cerebral ruptured aneurysm (n = 15) had higher serum MMP-2 and MMP-9 levels than those with unruptured aneurysm detectable by angiography (n = 15) (1047 ± 33 vs 110 ± 26 ng/mL and 1066 ± 43 vs 120 ± 27 ng/mL, respectively; P < .02).

Conclusion

The disproportional expression of among MMP-2, MMP-9, and TIMP contribute to the evolution of cerebral aneurysm. Real-time RT-PCR method is suitable for the determination of mRNA levels in small samples of vascular tissue.

Introduction

Cerebral aneurysm is a common vascular disease of increasing incidence. Factors such as aging, atherosclerosis, high blood pressure, and smoking have been associated with the development of cerebral aneurysms [7], [8]. However, the molecular pathogenesis of cerebral aneurysm is still unknown. Cerebral aneurysm has a life-threatening prognosis, which is characterized by alterations of the structural components of the artery wall [9], [10]. Matrix metalloproteinases, which degrade extracellular structural proteins like elastin and collagen and regulate tissue remodeling in a variety of pathophysiological conditions [5], [11] may play an important role in the formation and evolution of cerebral aneurysms. Matrix metalloproteinase-9 (gelatinase B) is a member of the MMP gene family, which encodes a family of zinc-dependent enzymes with proteolytic activity against connective tissue proteins, including collagens, elastin, and proteoglycans. Matrix metalloproteinase-9 plays an essential role in development and tissue remodeling [2], [19]. Matrix metalloproteinase-9 overexpression has been reported in abdominal aortic and cerebral aneurysms [12], [18].

The activities of MMPs are regulated on multiple levels: transcription and translation of the inactive precursors (zymogens), posttranslational activation of zymogens by proteolysis, and interactions of mature MMPs with TIMPs [16]. The equilibrium between MMPs and TIMPs expression is considered to regulate the synthesis and degradation of the ECM proteins. However, few data exist regarding the relative gene expression of MMPs and TIMPs in human samples of cerebral aneurysm, probably due to technical difficulties in measuring mRNA levels in relatively small samples of aneurysm and normal artery. In this study, we used real-time RT-PCR and analyzed gene expression levels of MMPs and TIMPs in the wall of cerebral ruptured aneurysms and unruptured aneurysms. The localization of MMPs and TIMPs in tissue and cellular was also examined through immunohistochemical staining. We used ELISA to measure serum levels of MMP-2 and MMP-9 in patients with cerebral ruptured aneurysm and patients with unruptured aneurysms [20].

Section snippets

Patient selection

The protocol of this study was approved by the institutional ethical committee. Thirty patients were divided into 2 group by computed tomography scan: ruptured aneurysm (n = 15) and unruptured aneurysms (n = 15). Thirty patients who underwent cerebral aneurysm clipping operation had written consent (13 men and 17 women; mean age, 71.3 ± 1.6 years). All patients underwent DSA (Angio Star, Siemens, Germany) to assess the size of the aneurysm. The diameter of cerebral aneurysm measured by DSA

Expression levels of MMP and TIMP genes

The values of MMP and TIMP expression in the ruptured aneurysm and unruptured aneurysm are summarized in Table 2. The expressions of MMP-2 and MMP-9 were significantly up-regulated in ruptured aneurysm compared to unruptured aneurysm (Fig. 2, Fig. 3). The gene of TIMP-1, TIMP-2, and TIMP-3 were also up-regulated.

Ratios of MMPs to TIMPs

The ratio of MMPs to TIMPs was higher in ruptured cerebral aneurysm than in unruptured aneurysm, The expression levels of MMP-2 to TIMP-1, MMP-2 to TIMP-2, MMP-2 to TIMP-3, and MMP-9 to

Discussion

Cerebral aneurysms usually remain asymptomatic until rupture occurs. Despite modern therapy, aneurysmal subarachnoid hemorrhage remains one of the most severe forms of cerebrovascular disease, with a mortality approaching 50%. An understanding of the biological mechanisms of cerebral aneurysms can result to new therapeutic strategies for these patients. Genetic factors play an important part in the pathogenesis of SAH and intracranial aneurysm [22].

Rupture of aneurysm is most common between 40

Conclusion

The disproportional expressions of MMP-2, MMP-9, and TIMP contribute to the evolution of cerebral aneurysm. Real-time RT-PCR method is suitable for the determination of mRNA levels in small samples of vascular tissue.

Acknowledgments

We thank Dr PeiTong Sun for the sample of ruptured and unruptured aneurysm.

This study was supported by research grant from National Natural Science Foundation of China (no. 30200289).

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Matrix metalloproteinases are important elastases and play a significant role in vascular remodeling. Specifically, MMP9 is a member of the matrix metalloproteinase gene family, which encodes a proteolytic enzyme, with elevated levels found in the wall of intracranial aneurysms.48,60,61 A limitation of this study is the between-study heterogeneity of the datasets analyzed.
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AneurysmMatrix metalloproteinases and tissue inhibitors of metalloproteinases expression in human cerebral ruptured and unruptured aneurysm

Abstract

Backround

Methods

Result

Conclusion

Introduction

Section snippets

Patient selection

Expression levels of MMP and TIMP genes

Ratios of MMPs to TIMPs

Discussion

Conclusion

Acknowledgments

Biochim Biophys Acta

J Surg Res

J Biol Chem

Cell

Lancet

Aneurysm growth, elastilynosis and attempted doxycycline inhibition of elastase-induced aneurysm in rabbits

J Vasc Interv Radiol

Vascular extracellular matrix remodeling in cerebral aneurysms

J Neurosurg

Heritability of intracerebral hemorrhagic lesions and cerebral aneurysms in the rat

Stroke

Remodeling of saccular cerebral artery aneurysm wall is associated with rupture. Histological analysis of 24 unruptured and 42 ruptured cases

Stroke

Ultrastructural connective tissue aberrations in patients with intracranial aneurysms

Stroke

Cigarette smoking and alcohol consumption as risk factors for aneurysmal subarachnoid hemorrhage

Stroke

Aneurysm
Matrix metalloproteinases and tissue inhibitors of metalloproteinases expression in human cerebral ruptured and unruptured aneurysm