oxygen-glucose-deprivation-reoxygenation-as-an-vitro-ischemia

Oxygen-Glucose Deprivation and Reoxygenation as an <em>In Vitro</em> Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic ...

Texas A&M University Health Science Center College of Medicine

Baylor Scott & White Health

Microvascular hyperpermeability that occurs due to breakdown of the BBB is a major contributor of brain vasogenic edema, following IR injury. In microvascular endothelial cells, increased ROS formation leads to caspase-3 activation following IR injury. The specific mechanisms, by which ROS mediates microvascular hyperpermeability following IR, are not clearly known. We utilized an OGD-R in vitro model of IR injury to study this.

Reactive oxygen species-caspase-3 relationship in mediating blood-brain barrier endothelial cell hyperpermeability following oxygen-glucose deprivation and reoxygenation.

Burns induce systemic inflammatory reactions and vascular hyperpermeability. Breakdown of endothelial cell adherens junctions is integral in this process, and reactive oxygen species (ROS) and proteolytic enzymes such as matrix metalloproteinase-9 (MMP-9) play pivotal roles therein. Outside trauma, melatonin has shown to exhibit anti-MMP activity and to be a powerful antioxidant. Consequently, we hypothesized that burn-induced junctional damage and hyperpermeability could be attenuated with melatonin.

Melatonin inhibits thermal injury-induced hyperpermeability in microvascular endothelial cells.

Traumatic brain injuries cause vascular hyperpermeability. Tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and caspase-3 may be important in these processes but the relationship between them has not been investigated. We hypothesized that TNF-α regulates caspase-3-mediated hyperpermeability and blood brain barrier damage and hyperpermeability directly or indirectly via activation of MMP-9. To test this, rat brain microvascular endothelial cells were treated with TNF-α with or without inhibition of MMP-9. Monolayer permeability was measured, zonula occludens-1 and F-actin configuration were examined, and MMP-9 and caspase-3 activities were quantified. TNF-α increased monolayer permeability, damaged zonula occludens-1, induced filamentous-actin stress fiber formation, and increased both MMP-9 and caspase-3 activities. Inhibition of MMP-9 attenuated these changes. These data highlight a novel link between TNF-α and MMP-9 and show that TNF-α regulated caspase-3-mediated hyperpermeability and vascular damage may be linked to MMP-9 in vitro. These findings augment the understanding of traumatic brain injury and pave the way for improved treatment.

Tumor necrosis factor-α disruption of brain endothelial cell barrier is mediated through matrix metalloproteinase-9.

Traumatic brain injury is a serious cause of morbidity and mortality worldwide. After traumatic brain injury, the blood-brain barrier, the protective barrier between the brain and the intravascular compartment, becomes dysfunctional, leading to leakage of proteins, fluid, and transmigration of immune cells. As this leakage has profound clinical implications, including edema formation, elevated intracranial pressure and decreased perfusion pressure, much interest has been paid to better understanding the mechanisms responsible for these events. Various molecular pathways and numerous mediators have been found to be involved in the intricate process of regulating blood-brain barrier permeability following traumatic brain injury. This review provides an update to the existing knowledge about the various pathophysiological pathways and advancements in the field of blood-brain barrier dysfunction and hyperpermeability following traumatic brain injury, including the role of various tight junction proteins involved in blood-brain barrier integrity and regulation. We also address pitfalls of existing systems and propose strategies to improve the various debilitating functional deficits caused by this progressive epidemic.

Article	Year
Reactive oxygen species-caspase-3 relationship in mediating blood-brain barrier endothelial cell hyperpermeability following oxygen-glucose deprivation and reoxygenation. Microcirculation (New York, N.Y. : 1994)\| PubMed ID: 24372803	2014
Melatonin inhibits thermal injury-induced hyperpermeability in microvascular endothelial cells. The journal of trauma and acute care surgery\| PubMed ID: 25051382	2014
Tumor necrosis factor-α disruption of brain endothelial cell barrier is mediated through matrix metalloproteinase-9. American journal of surgery\| PubMed ID: 25312844	2014
Blood-brain barrier dysfunction following traumatic brain injury. Metabolic brain disease\| PubMed ID: 25624154	2015

Himakarnika Alluri

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