Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix and carry out key functions during brain development. Apart from a physiological role, excessive activation of MMPs in brain tissue has been postulated to represent a pathway for cell death arising from ischemia. To evaluate the possible involvement of MMPs in the perinatal brain asphyxia, we exposed 7-day-old rats to hypoxia-ischemia (HI). Unilateral HI was administered by ligation of the common carotid artery followed by hypoxia (7.4% O2/92.6% N2) for 65 minutes. This insult is known to produce brain damage confined to the cerebral hemisphere ipsilateral to the arterial occlusion in > 90% of animals. HI resulted in a significant elevation of MMP-2 and MMP-9 activity in the ipsilateral forebrain. The maximum activation was found at 48 hours and 7-14 days after the insult. These results suggest that early and late induction of MMPs may play a role in neuronal death as well as in repair processes. The treatment of animals subjected to HI with 1-methylnicotinamide (MNA), the anti-inflammatory agent, led to the inhibition of MMP-9 in an acute phase of ischemic damage and to the activation of MMP-2 in the later stages after injury. The timing of MMPs modulation by MNA may indicate its possible therapeutic implications.
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In the pathogenesis of dilated cardiomyopathy (DCM) in Emery-Dreifuss muscular dystrophy (EDMD) matrix metalloproteinases (MMPs) are supposed to be involved and may have diagnostic/prognostic value. Serum levels of MT1-MMP, MMP-2 and MMP-9 were quantified by ELISA and zymography in 22 EDMD patients and 15 age-matched controls. In the autosomal-dominant EDMD MMP-2 and MT1-MMP were increased in all cases, and MMP-9 was increased in two of the eight examined patients. In the X-linked EDMD MMP-2 expression was increased in all the cases, MMP-9 level was elevated in 3 of the 14 cases, and MT1-MMP was decreased in eight of these patients. There was no evident correlation between the MMPs level and the different cardiac parameters including left-ventricular end-diastolic diameter, left atrial diameter and left ventricular ejection fraction in either form of EDMD. The presented results indicate that a changed level of matrix metalloproteinases, especially that of MMP-2 in serum, may be of value for detection of cardiac involvement in EDMD patients, especially in those patients with no evident subjective cardiac symptoms. Further follow-up studies of MMPs are needed to check if their determination is of value for monitoring of the progression of atrial/ventricular dilatation. MMPs determinations may also be useful for monitoring DCM treatment by synthetic MMPs inhibitors.
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