Brain Endothelial Cells Synthesize Neurotoxic Thrombin in Alzheimer’s Disease

Abstract

Alzheimer's disease (AD) is characterized by neuronal death; thus, identifying neurotoxic proteins and their source is central to understanding and treating AD. The multifunctional protease thrombin is neurotoxic and found in AD senile plaques. The objective of this study was to determine whether brain endothelial cells can synthesize thrombin and thus be a source of this neurotoxin in AD brains. Microvessels were isolated from AD patient brains and from age-matched controls. Reverse transcription-PCR demonstrated that thrombin message was highly expressed in microvessels from AD brains but was not detectable in control vessels. Similarly, Western blot analysis of microvessels showed that the thrombin protein was highly expressed in AD- but not control-derived microvessels. In addition, high levels of thrombin were detected in cerebrospinal fluid obtained from AD but not control patients, and sections from AD brains showed reactivity to thrombin antibody in blood vessel walls but not in vessels from controls. Finally, we examined the ability of brain endothelial cells in culture to synthesize thrombin and showed that oxidative stress or cell signaling perturbations led to increased expression of thrombin mRNA in these cells. The results demonstrate, for the first time, that brain endothelial cells can synthesize thrombin, and suggest that novel therapeutics targeting vascular stabilization that prevent or decrease release of thrombin could prove useful in treating this neurodegenerative disease.

Dissecting the Contribution of Vascular Alterations and Aging to Alzheimer’s Disease

“…The production of thrombin by endothelial cells in AD seems to be another proteomical dysfunction of these cells. This protein may be an interesting therapeutic target since thrombin in the brain parenchyma causes inflammation, abnormal angiogenesis, and activation of microglia and astrocytes [90,91]. In vivo, thrombin is known to increase Aβ production, induce tau hyperphosphorylation, and lead to cognitive impairment [92,93].…”

Enhancement of aptamer immobilization using egg shell-derived nano-sized spherical hydroxyapatite for thrombin detection in neuroclinic

“…Researchers have presented results linking the thrombin levels in the metabolism with not only hemorrhage or thrombosis but also with some neurological disease like Alzhemier's, autoimmune encephalomyelitis, acute focal ischemia or Multiple Sclerosis (MS) [19][20][21][22]. Thus the sensitive, accurate and practical detection of thrombin levels in biological samples takes up an important place in public healthcare.…”

Involvement of placental growth factor in Wallerian degeneration

“…To characterize PlGF expression, double immunofluorescenct stainings for PlGF (sc-27134; 1:50; Santa Cruz Biotechnology, Santa Cruz, CA, Taylor and Goldenberg, 2007) and NF-H (MAB5448/clone TA51; 1:500; Millipore, De Girolamo et al, 2000) for axons, Neu-N (MAB377/ clone A60; 1:250; Millipore, Borsani et al, 2010) for neuronal cell nuclei, S100 (ZO311; 1/200; DakoCytomation, Gould et al, 1986) for quiescent SCs, p75NGFr (AB1554; 1/200; Millipore, Runyan and Phelps, 2009) for proliferating SCs, von Willebrand factor (vWF; AB6994; 1/2000; Abcam, Yin et al, 2010) for endothelial cells, patched-1 (Ptc-1; sc-9016/H-267; 1/50; Santa Cruz Biotechnology, Chen et al, 2007) for fibroblasts, CD11b (MCA74; 1/250; Serotec, Springer et al, 1979) for macrophages, P0 (AB9352; 1/50; Millipore) for peripheral myelin, were performed. After drying, tissue sections were fixed in cold acetone for 10 min at 4°C.…”