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Doxycycline Blocks Matrixmetalloproteinase‐9 and Attenuates Blood‐Brain Barrier dysfunction and Hyperpermeability after Traumatic Brain Injury
Author(s) -
Robinson Bobby Darnell,
Lomas Angela,
Shaji Chinchusha Anasooya,
Isbell Claire Larson,
Tharakan Binu
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.lb762
Subject(s) - traumatic brain injury , medicine , doxycycline , blood–brain barrier , craniotomy , intracranial pressure , anesthesia , in vivo , edema , cerebral blood flow , pharmacology , evans blue , central nervous system , chemistry , antibiotics , biochemistry , microbiology and biotechnology , psychiatry , biology
Traumatic brain injury (TBI) is a global issue affecting approximately 10 million people annually. Brain edema that occurs after TBI leads to challenging clinical scenarios, including elevated intracranial pressure (ICP), decreased cerebral blood flow, poor tissue oxygenation, and brain herniation. Currently, treatment modalities exist to somewhat address symptoms of cerebral edema, but there are no effective medical therapies able to modulate the underlying pathophysiology responsible for TBI‐induced microvascular “leak.” The purpose of this study is to demonstrate that doxycycline inhibits matrixmetalloproteinase‐9 (MMP‐9) and reduces microvascular hyperpermeability in TBI in vivo. Molecular docking simulation was performed with AutoDock 4.2.6 using Lamarckian genetic algorithm. Each docking experiment was a composite of 100 independent executions. MMP‐9 and doxycycline structures were obtained from Protein Databank and DrugBank respectively. Molecular modeling showed doxycycline spontaneous binding to the MMP‐9 active site. For in vivo studies, C57BL/6 mice were injected via tail vein with 0.1 mL of 50 mg/mL FITC‐dextran prior to injury as an intravascular tracer. A mild‐moderate TBI (velocity of 0.50 m/s, contact time of 0.1 milliseconds, and depth of 2 millimeters) was performed with the Leica controlled cortical impactor after craniotomy. Sham mice had only craniotomy performed. The doxycycline group was given 20 mg/kg of doxycycline intravenously 10 minutes after injury. Intravital microscopy of brain pial microvasculature was performed 10 minutes after injury up to 70 minutes after injury and the data was analyzed. The difference in fluorescence intensity between the intravascular space and the interstitial space was calculated as a measure of BBB permeability. There was no significant difference in permeability among the groups at the initial time point of 10 mins after injury. There was a significant increase in TBI vs sham group and a decrease in hyperpermeability when compared between the TBI and TBI plus doxycycline groups ( p <0.05; ANOVA followed by Bonferroni's multiple comparisons test). There was no significant difference between the Sham group and TBI plus doxycycline group. The brain tissue was harvested from each mouse and ELISA of brain tissue extract demonstrated increase in interleukin‐1β (IL‐1β) between sham and TBI ( p <0.05) but no difference in the TBI and TBI + Doxycycline groups, suggesting that doxycycline has no effects on tissue IL‐1β levels upstream. Doxycycline spontaneously binds to MMP‐9 and its active site evidenced by the molecular docking studies. Mice treated with doxycycline following TBI had enhanced BBB integrity/decreased microvascular hyperpermeability. Doxycycline may be a viable treatment in TBI to protect the BBB and decrease brain edema when established in patients.