title: Melatonin Preserves Blood-Brain Barrier Integrity and Permeability via Matrix Metalloproteinase-9 Inhibition.
abstract: Microvascular hyperpermeability that occurs at the level of the blood-brain barrier (BBB) often leads to vasogenic brain edema and elevated intracranial pressure following traumatic brain injury (TBI). At a cellular level, tight junction proteins (TJPs) between neighboring endothelial cells maintain the integrity of the BBB via TJ associated proteins particularly, zonula occludens-1 (ZO-1) that binds to the transmembrane TJPs and actin cytoskeleton intracellularly. The pro-inflammatory cytokine, interleukin-1β (IL-1β) as well as the proteolytic enzymes, matrix metalloproteinase-9 (MMP-9) are key mediators of trauma-associated brain edema. Recent studies indicate that melatonin a pineal hormone directly binds to MMP-9 and also might act as its endogenous inhibitor. We hypothesized that melatonin treatment will provide protection against TBI-induced BBB hyperpermeability via MMP-9 inhibition. Rat brain microvascular endothelial cells grown as monolayers were used as an in vitro model of the BBB and a mouse model of TBI using a controlled cortical impactor was used for all in vivo studies. IL-1β (10 ng/mL; 2 hours)-induced endothelial monolayer hyperpermeability was significantly attenuated by melatonin (10 μg/mL; 1 hour), GM6001 (broad spectrum MMP inhibitor; 10 μM; 1 hour), MMP-9 inhibitor-1 (MMP-9 specific inhibitor; 5 nM; 1 hour) or MMP-9 siRNA transfection (48 hours) in vitro. Melatonin and MMP-9 inhibitor-1 pretreatment attenuated IL-1β-induced MMP-9 activity, loss of ZO-1 junctional integrity and f-actin stress fiber formation. IL-1β treatment neither affected ZO-1 protein or mRNA expression or cell viability. Acute melatonin treatment attenuated BBB hyperpermeability in a mouse controlled cortical impact model of TBI in vivo. In conclusion, one of the protective effects of melatonin against BBB hyperpermeability occurs due to enhanced BBB integrity via MMP-9 inhibition. In addition, acute melatonin treatment provides protection against BBB hyperpermeability in a mouse model of TBI indicating its potential as a therapeutic agent for brain edema when established in humans.
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Himakarnika
authors.initials: H
authors.lastname: Alluri
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Rickesha L
authors.initials: RL
authors.lastname: Wilson
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Chinchusha
authors.initials: C
authors.lastname: Anasooya Shaji
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Katie
authors.initials: K
authors.lastname: Wiggins-Dohlvik
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Savan
authors.initials: S
authors.lastname: Patel
authors.affiliation: Department of Medical Physiology, Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Medical Physiology, Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Xu
authors.initials: X
authors.lastname: Peng
authors.affiliation: Department of Pediatrics, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Madhava R
authors.initials: MR
authors.lastname: Beeram
authors.affiliation: Department of Medical Physiology, Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Davis
authors.affiliation: Department of Neurosurgery, Baylor Scott & White Health/ Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Jason H
authors.initials: JH
authors.lastname: Huang
authors.affiliation: Department of Surgery, Baylor Scott & White Health/Texas A&M University Health Science Center College of Medicine, Temple, Texas, United States of America.
authors.forename: Binu
authors.initials: B
authors.lastname: Tharakan
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D006801:Humans; D053583:Interleukin-1beta / Q000627:therapeutic use; D020780:Matrix Metalloproteinase 9 / Q000187:drug effects* / Q000235:genetics; D008550:Melatonin / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011480:Protease Inhibitors / Q000494:pharmacology*; D051381:Rats
chemical_list: D053583:Interleukin-1beta; D011480:Protease Inhibitors; D020780:Matrix Metalloproteinase 9; D008550:Melatonin