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

Presented at the Southwestern Surgical Congress 66th Annual Meeting, April 13–16, 2014.
https://doi.org/10.1016/j.amjsurg.2014.08.014Get rights and content

Abstract

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.

Section snippets

Chemicals and reagents

Rat brain microvascular endothelial cells (RBMECs) from Cell Applications, Inc (San Diego, CA), fibronectin from bovine serum (.1% solution; Sigma-Aldrich, St. Louis, MO), RBMEC growth media (Cell Applications, Inc), and Trypsin-EDTA solution (.25%; Invitrogen, Grand Island, NY) were used for all in vitro experiments. TNF-α was obtained from Sigma and MMP-9 inhibitor 1 from Calbiochem (San Diego, CA). DMEM-Fluorobrite (Life Technologies, Grand Island, NY) media and Fluorescein isothiocyanate

Matrix metalloproteinase-9 inhibitor 1 decreases tumor necrosis factor-α-induced monolayer hyperpermeability

Fluorescent intensity was measured and values are expressed as a percentage of control. RBMEC monolayers exposed to TNF-α displayed significantly increased permeability evidenced by increased fluorescent intensity when compared with those measured in the control group (P = .002). MMP-9 inhibitor 1 significantly attenuated this increase (P = .02; Fig. 1).

Tumor necrosis factor-α-induced disruption to tight junction protein zonula occluden-1 is ameliorated with matrix metalloproteinase-9 inhibitor 1

Confocal images of RBMECs with immunofluorescence staining of the endothelial TJ protein ZO-1 are illustrated in Fig. 2A, demonstrating loss

Comments

The complexity of the human brain is paralleled only by the pathology that afflicts it. Traumatic injuries are no exception, and the role of TNF-α therein is equally as complex. As a testament to this, a PubMed query for ‘TNF and brain injury’ returns over 1,000 results. In this literature, TNF-α has been shown, among other things, to stimulate apoptosis of brain microvascular endothelium, increase vasogenic brain edema, and correlate with breakdown of the BBB.7, 23, 24, 26 On the contrary,

References (28)

  • A.G. Mustafa et al.

    Pathophysiology of traumatic brain injury

    Neurosciences

    (2013)
  • H. Algattas et al.

    Traumatic brain injury pathophysiology and treatments: early, intermediate, and late phases post-injury

    Int J Mol Sci

    (2014)
  • J.T. Weber

    Altered calcium signaling following traumatic brain injury

    Front Pharmacol

    (2012)
  • A.W. Unterberg et al.

    Edema and brain trauma

    Neuroscience

    (2004)
  • Cited by (0)

    The authors declare no conflicts of interest.

    We acknowledge the Office of Academic Operations and Department of Surgery, Baylor Scott & White Health, Temple, Texas, for financial support and Texas A&M Health Science Center College of Medicine Integrated Imaging Laboratory for the use of the confocal laser microscope and technical assistance with imaging.

    View full text