C16 Peptide Promotes Vascular Growth and Reduces Inflammation in a Neuromyelitis Optica Model

Abstract

The goal of this study was to elucidate the mechanism of action of C16, a laminin-1 peptide that competes with αvβ3 for integrin binding, in treating neuromyelitis optica (NMO). A NMO rat model was established and specific inhibitors were used to investigate the effect of Tie2 kinase, integrin, and PI3K/Akt signaling pathways on C16 function in NMO using histological, immunohistochemical, immunofluorescence, Western blot, and ELISA assays. A total of 150 rats were divided into five groups: a control untreated group (n = 18) and four test groups (n = 33 per group) including vehicle-treated control, C16, Tie2 kinase inhibitor + C16, and PI3K/Akt inhibitor LY294002 + C16. We found that inhibiting Tie2 kinase resulted in partial loss of C16 peptide-mediated effects, while suppressing PI3K/Akt signaling reduced C16 peptide-mediated effects. In addition, activation of the αvβ3 integrin axis and Tie2 kinase promoted PI3K/Akt signaling. Our study showed that the Tie2-PI3K/Akt, Tie2 integrin, and integrin-PI3K/Akt signaling pathways regulate C16 peptide function in vascular growth and stabilization as well as inflammation in NMO.

Combined treatment with C16 peptide and angiopoietin-1 confers neuroprotection and reduces inflammation in 3-nitropropionic acid-induced dystonia mice

“…Alternative pathways including the α5β1-PI3K-Bcl-2 and α5β1/αvβ3-integrin-dependent Akt, ERK, and c-Jun N-terminal kinase (JNK) signaling pathways are involved in αvß3 and/or α5β1-integrin-mediated PI3K/Akt activation as well as the modulation of neuronal survival [ 28 ]. Our observations from dystonia mice were consistent with previous reports of neuroprotection upon PI3K/Akt activation by C16 and Ang-1, alone and in combination, which promoted cell viability and suppressed apoptosis and autophagy in basal ganglia neurons and terminals in the indirect pathway [ 29 , 35 ].…”

“…The length of time each animal spent near the object in the novel location (NL) and near the familiar object (F) were recorded to determine the preference for novelty. The discrimination score was calculated using (NL–F)/ (NL+F) [ 35 ].…”

“…The brain of each mouse was harvested and half of it was fixed in 4% paraformaldehyde for 4 h before immersing in a PBS solution with 30% sucrose. Coronal sections (20 μm-thick) of the corpus striatum and nigra substance regions were obtained using a freezing microtome and a Leica cryostat (Buffalo Grove, IL, USA) and mounted onto 0.02% poly-L-lysine-coated slides for subsequent histology experiments [ 17 – 19 , 35 ].…”

“…Half of the striatum and nigra substance was fixed in a 2.5% glutaraldehyde solution, washed three times with 0.1 M PBS, and soaked in 1% osmium tetroxide at 4°C overnight. After washing three times with 0.1 M PBS, the sections were examined under a transmission electron microscope (TEM, JEOL Ltd. Tokyo, Japan) as previously described [ 17 – 19 , 35 ].…”

“…Inflammatory cell infiltration in HE stained mouse brain tissue sections of the striatum and nigra substance was examined under a light microscope [ 17 – 19 , 35 ] by an experienced pathologist without prior knowledge of the experimental conditions. Cells in five random fields of view were counted for each section.…”