Increase in Blood-Brain Barrier (BBB) Permeability Is Regulated by MMP3 via the ERK Signaling Pathway.

Qin Zhang,James K Liao,Mei Zheng,Rongxue Wu,John H Zhang,Qiong Zhao,Albert Sitikov,Cristian E Betancourt,Lifeng Liu,Nikola Sladojevic,Kambiz Hassanzadeh

doi:10.1155/2021/6655122

Abstract

Background The blood-brain barrier (BBB) regulates the exchange of molecules between the brain and peripheral blood and is composed primarily of microvascular endothelial cells (BMVECs), which form the lining of cerebral blood vessels and are linked via tight junctions (TJs). The BBB is regulated by components of the extracellular matrix (ECM), and matrix metalloproteinase 3 (MMP3) remodels the ECM's basal lamina, which forms part of the BBB. Oxidative stress is implicated in activation of MMPs and impaired BBB. Thus, we investigated whether MMP3 modulates BBB permeability. Methods Experiments included in vivo assessments of isoflurane anesthesia and dye extravasation from brain in wild-type (WT) and MMP3-deficient (MMP3-KO) mice, as well as in vitro assessments of the integrity of monolayers of WT and MMP3-KO BMVECs and the expression of junction proteins. Results Compared to WT mice, measurements of isoflurane usage and anesthesia induction time were higher in MMP3-KO mice and lower in WT that had been treated with MMP3 (WT+MMP3), while anesthesia emergence times were shorter in MMP3-KO mice and longer in WT+MMP3 mice than in WT. Extravasation of systemically administered dyes was also lower in MMP3-KO mouse brains and higher in WT+MMP3 mouse brains, than in the brains of WT mice. The results from both TEER and Transwell assays indicated that MMP3 deficiency (or inhibition) increased, while MMP3 upregulation reduced barrier integrity in either BMVEC or the coculture. MMP3 deficiency also increased the abundance of TJs and VE-cadherin proteins in BMVECs, and the protein abundance declined when MMP3 activity was upregulated in BMVECs, but not when the cells were treated with an inhibitor of extracellular signal related-kinase (ERK). Conclusion MMP3 increases BBB permeability following the administration of isoflurane by upregulating the ERK signaling pathway, which subsequently reduces TJ and VE-cadherin proteins in BMVECs.

Highlights

The blood-brain barrier (BBB) regulates the exchange of molecules between the brain and peripheral blood and is composed primarily of endothelial cells (ECs), as well as pericytes and the endfeet of astrocytes [1]
Measurements in WT mice indicated that matrix metalloproteinase 3 (MMP3) expression was significantly higher in BMVECs than in primary astrocytes or in microvascular endothelial cells (MVECs) isolated from the heart, lung, kidney, or spleen (1 vs. 0:111 ± 0:016 vs. 0:037 ± 0:007 vs. 0:404 ± 0:056 vs. 0:058 ± 0:011, p < 0:0001) Figure 2(c)), which suggests that MMP3 may have a unique and important role in BMVECs that differs from its roles in ECs from other organs
The selective permeability of the BBB is crucially dependent on the formation of tight junctions (TJs) and adherens junctions (AJs) [38]; we investigated whether MMP3 may increase BBB permeability by disrupting expression of the TJ proteins ZO-1, occludin, and claudin-5, as well as the AJ protein vascular endothelial (VE)-cadherin; experiments were conducted with primary BMVECs isolated from the brains of MMP3-KO mice or their WT littermates

Summary

Introduction

The blood-brain barrier (BBB) regulates the exchange of molecules between the brain and peripheral blood and is composed primarily of endothelial cells (ECs), as well as pericytes and the endfeet of astrocytes [1]. The blood-brain barrier (BBB) regulates the exchange of molecules between the brain and peripheral blood and is composed primarily of microvascular endothelial cells (BMVECs), which form the lining of cerebral blood vessels and are linked via tight junctions (TJs). Extravasation of systemically administered dyes was lower in MMP3-KO mouse brains and higher in WT+MMP3 mouse brains, than in the brains of WT mice The results from both TEER and Transwell assays indicated that MMP3 deficiency (or inhibition) increased, while MMP3 upregulation reduced barrier integrity in either BMVEC or the coculture. MMP3 increases BBB permeability following the administration of isoflurane by upregulating the ERK signaling pathway, which subsequently reduces TJ and VE-cadherin proteins in BMVECs

Methods

Results

Discussion

Conclusion