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Research paper
Autocrine MMP-2/9 secretion increases the BBB permeability in neuromyelitis optica
  1. Ayako Tasaki1,
  2. Fumitaka Shimizu1,
  3. Yasuteru Sano1,
  4. Miwako Fujisawa1,
  5. Toshiyuki Takahashi2,
  6. Hiroyo Haruki1,
  7. Masaaki Abe1,
  8. Michiaki Koga1,
  9. Takashi Kanda1
  1. 1Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Ube, Japan
  2. 2Department of Neurology, Tohoku University Graduate School of Medicine, Miyagi, Japan
  1. Correspondence to Dr Takashi Kanda, Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1, Minamikogushi, Ube, Yamaguchi 7558505, Japan; tkanda{at}yamaguchi-u.ac.jp

Abstract

Objective Pathological breakdown of the blood-brain barrier (BBB) is thought to constitute the beginning of the disease process in neuromyelitis optica (NMO). In the current study, we investigated possible molecular mechanisms responsible for the breakdown of BBB using NMO sera.

Methods We analysed the effects of sera obtained from anti-aquaporin 4 (AQP4) antibody-positive NMO spectrum disorder (NMOSD) patients, multiple sclerosis (MS) patients and control subjects on the production of claudin-5, matrix-metalloproteinases (MMPs)-2/9, and vascular cell adhesion protein-1 (VCAM-1) in human brain microvascular endothelial cells (BMECs). We also examined whether immunoglobulin G (IgG) purified from NMOSD sera influences the claudin-5 or VCAM-1 protein expression.

Results The disturbance of BBB properties in BMECs following exposure to NMOSD sera was restored after adding the MMP inhibitor, GM6001. The secretion of MMP-2/9 by BMECs significantly increased after applying the NMOSD sera. The sera from NMOSD patients also increased both the MMP-2/9 secretion and the VCAM-1 protein level by BMECs. The IgG purified from NMOSD sera did not influence the BBB properties or the amount of MMP-2/9 proteins, although it did increase the amount of VCAM-1 proteins in BMECs. Reduction in anti-AQP4 antibody titre was not correlated with a reduction in VCAM-1 expression.

Conclusions The autocrine secretion of MMP-2/9 by BMECs induced by humoral factors, other than IgG, in sera obtained from NMOSD patients potentially increases BBB permeability. IgG obtained from NMOSD sera, apart from anti-AQP4 antibodies, affect the BBB by upregulating VCAM, thereby facilitating the entry of inflammatory cells into the central nervous system.

  • Blood-Brain Barrier
  • Multiple Sclerosis

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