Abstract
BackgroundIncreased leukocyte adhesion to brain endothelial cells forming the blood–brain barrier (BBB) precedes extravasation into the central nervous system (CNS) in neuroinflammatory diseases such as multiple sclerosis (MS). Previously, we reported that microRNA-155 (miR-155) is up-regulated in MS and by inflammatory cytokines in human brain endothelium, with consequent modulation of endothelial paracellular permeability. Here, we investigated the role of endothelial miR-155 in leukocyte adhesion to the human cerebral microvascular endothelial cell line, hCMEC/D3, under shear forces mimicking blood flow in vivo.ResultsUsing a gain- and loss-of-function approach, we show that miR-155 up-regulation increases leukocyte firm adhesion of both monocyte and T cells to hCMEC/D3 cells. Inhibition of endogenous endothelial miR-155 reduced monocytic and T cell firm adhesion to naïve and cytokines-induced human brain endothelium. Furthermore, this effect is partially associated with modulation of the endothelial cell adhesion molecules VCAM1 and ICAM1 by miR-155.ConclusionsOur results suggest that endothelial miR-155 contribute to the regulation of leukocyte adhesion at the inflamed BBB. Taken together with previous observations, brain endothelial miR-155 may constitute a potential molecular target for treatment of neuroinflammation diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s12987-016-0032-3) contains supplementary material, which is available to authorized users.
Highlights
Increased leukocyte adhesion to brain endothelial cells forming the blood–brain barrier (BBB) precedes extravasation into the central nervous system (CNS) in neuroinflammatory diseases such as multiple sclerosis (MS)
Cell culture The hCMEC/D3 cell line [14] was used at passages 26–34 and cultured in endothelial cell basal medium-2 (EGM-2) medium (Lonza, Walkersville, USA) and supplemented with the following components obtained from the manufacturer: 0.025 % (v/v) rhEGF, 0.025 % (v/v) VEGF, 0.025 % (v/v) IGF, 0.1 % (v/v) rhFGF, 0.1 % (v/v) gentamycin, 0.1 % (v/v) ascorbic acid, 0.04 % (v/v) hydrocortisone and 2.5 % (v/v) foetal bovine serum (FBS), hereafter referred to as endothelial complete medium. hCMEC/D3 cells were grown to confluence (~1 × 105 cells/cm2) on tissue culture flasks coated with collagen from calf skin
MiR‐155 modulates Jurkat and THP‐1 firm adhesion to hCMEC/D3 cells We first investigated whether increased levels of miR155 in unstimulated brain endothelial cells affected firm leukocyte adhesion under shear stress
Summary
Increased leukocyte adhesion to brain endothelial cells forming the blood–brain barrier (BBB) precedes extravasation into the central nervous system (CNS) in neuroinflammatory diseases such as multiple sclerosis (MS). We investigated the role of endothelial miR-155 in leukocyte adhesion to the human cerebral microvascular endothelial cell line, hCMEC/ D3, under shear forces mimicking blood flow in vivo. In the central nervous system (CNS), firm leukocyte adhesion to the highly specialized brain endothelial cells forming the blood– brain barrier (BBB) is important in immunosurveillance and plays a critical role in the pathogenesis of neuroinflammatory diseases such as multiple sclerosis (MS) [2]. In MS, chemokines and proinflammatory cytokines such as TNFα and IFNγ are secreted in the inflammatory loci thereby leading to VCAM1 and ICAM1 overexpression on activated brain endothelial cells [2]. The endothelial molecular controls on leukocyte firm adhesion to brain endothelium have not been fully elucidated
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