Matrix Metalloproteinase-12 Induces Blood–Brain Barrier Damage After Focal Cerebral Ischemia

Abstract

T he blood-brain barrier (BBB) is formed by the endothelial cells of cerebral microvessels, which are distinguished from peripheral endothelial cells by their lack of fenestrations, minimal pinocytotic activity, and the tight junctions (TJs).1 In addition to endothelial cells, the BBB is composed of pericytes, astrocytes, neurons, and extracellular matrix.2 Endothelial cells and pericytes are surrounded by the extracellular matrix, which is composed of structural proteins, such as collagen type-IV, laminin, fibronectin, elastin, thrombospondin, and various proteoglycans. The TJs between the endothelial cells of the cerebral microvessels serve to restrict blood-borne substances from entering the brain. The BBB thus provides a dynamic interface between the peripheral circulation and the brain.BBB disruption is an important contributing factor to brain injury that occurs after ischemic stroke. The expression of matrix metalloproteinases (MMPs) in the normal adult brain is very low or undetectable. In the injured brain, MMPs are expressed in various cell types, including resident and infiltrating inflammatory cells.3 However, the brain regions and cellular sources of expression differ for the specific MMPs, as well as the type, severity, and duration of injuries. 4 Ischemia leads to induction of MMPs, which contribute to BBB extracellular matrix degradation. The induction of these MMPs may further perpetuate BBB TJ permeability, thereby leading to BBB leakage, leukocyte infiltration, brain edema, and hemorrhage.2 MMP-2 and MMP-9 are considered the central mediators of ischemic BBB disruption because of their ability to degrade components of microvascular basal lamina, especially collagen type-IV, and to disrupt TJ proteins. [5][6][7][8] Recent investigations highlighted the possible pathological role for MMP-12 in the context of ischemic stroke. 9,10 MMP-12 is upregulated several fold higher than any other MMPs tested after focal cerebral ischemia, and its suppression attenuated the ischemic brain damage.10 Also, MMP-12 is reported to activate other MMPs, such as pro-MMP-2 and Background and Purpose-Matrix metalloproteinases (MMPs) have a central role in compromising the integrity of the blood-brain barrier (BBB). The role of MMP-12 in brain damage after ischemic stroke remains unknown. The main objective of the current study is to investigate the effect of MMP-12 suppression at an early time point before reperfusion on the BBB damage in rats. Methods-Sprague-Dawley rats were subjected to middle cerebral artery occlusion and reperfusion. MMP-12 shRNAexpressing plasmids formulated as nanoparticles were administered at a dose of 1 mg/kg body weight. The involvement of MMP-12 on BBB damage was assessed by performing various techniques, including Evans blue dye extravasation, 2,3,5-triphenyltetrazolium chloride staining, immunoblot, gelatin zymography, and immunofluorescence analysis. Results-MMP-12 is upregulated ≈31-, 47-, and 66-fold in rats subjected 1-, 2-, or 4-hour ischemia, respectively, followed by 1-day reperf...

Mesenchymal Stem Cell Treatment Prevents Post-Stroke Dysregulation of Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases

“…In agreement with these studies, our recent studies in a rat model of transient focal cerebral ischemia and reperfusion reported the post-ischemic induction of MMP-9 activity through gelatin zymography analysis [4,5]. TIMP-1 upregulation after stroke in the human infarcted brain tissue was recently reported [25].…”

“…Manipulation of either MMP-9 or MMP-12 by neutralizing antibodies or siRNA-/shRNAmediated gene silencing attenuated the brain damage in rats after ischemic stroke [4][5][6][7][8]. HUCB-MSCs treatment in spinal cord injured rats prevented the dysregulation of various MMPs including MMP-9 and MMP-12 as well as improved their locomotor recovery [9,31].…”

“…Several studies suggests that elevated matrix metalloproteinases (MMPs) play a detrimental role in various types of CNS pathology, including ischemic stroke [1][2][3]. Our recent studies demonstrated the predominant upregulation of MMP-12 and its pathological role in acute brain damage after ischemic stroke [4,5]. The temporal expression profile of various MMPs in ischemic rat brains after focal cerebral ischemia and reperfusion revealed that MMP-9 and MMP-12 were upregulated (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) fold in case of MMP-9 and 47-265 fold in case of MMP-12 through days 1 to 7 after reperfusion) several fold higher than any other MMPs tested [4].…”

“…The temporal expression profile of various MMPs in ischemic rat brains after focal cerebral ischemia and reperfusion revealed that MMP-9 and MMP-12 were upregulated (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) fold in case of MMP-9 and 47-265 fold in case of MMP-12 through days 1 to 7 after reperfusion) several fold higher than any other MMPs tested [4]. Evidence also suggests the detrimental role of MMP-9 and MMP-12 on post-stroke brain damage [4][5][6][7][8]. In the recent past, we demonstrated the prevention of MMPs induction in human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) treated spinal cord injured rats [9].…”

Stem Cell Treatment after Ischemic Stroke Alters the Expression of DNA Damage Signaling Molecules

“…In order for the HUCB-MSCs to migrate to the ischemic brain after their administration, they should be permeable through the blood brain barrier (BBB). Recently, we reported the possible disruption of BBB, which occurred as early as two-hours post MCAO without reperfusion in the same rodent model of focal cerebral ischemia [14]. Therefore, it is quite possible for the HUCB-MSCs administered one hour after reperfusion subsequent to a two-hour ischemia, to reach various regions of the ischemic brain.…”