6 research outputs found

    AIBP Regulates TRPV1 Activation in Chemotherapy-Induced Peripheral Neuropathy by Controlling Lipid Raft Dynamics and Proximity to TLR4 in Dorsal Root Ganglion Neurons

    Get PDF
    Nociceptive afferent signaling evoked by inflammation and nerve injury is mediated by the opening of ligand-gated and voltage-gated receptors or channels localized to cholesterol-rich lipid raft membrane domains. Dorsal root ganglion (DRG) nociceptors express high levels of toll-like receptor 4 (TLR4), which also localize to lipid rafts. Genetic deletion or pharmacologic blocking of TLR4 diminishes pain associated with chemotherapy-induced peripheral neuropathy (CIPN). In DRGs of mice with paclitaxel-induced CIPN, we analyzed DRG neuronal lipid rafts, expression of TLR4, activation of transient receptor potential cation channel subfamily V member 1 (TRPV1), and TLR4-TRPV1 interaction. Using proximity ligation assay, flow cytometry, and whole-mount DRG microscopy, we found that CIPN increased DRG neuronal lipid rafts and TLR4 expression. These effects were reversed by intrathecal injection of apolipoprotein A-I binding protein (AIBP), a protein that binds to TLR4 and specifically targets cholesterol depletion from TLR4-expressing cells. Chemotherapy-induced peripheral neuropathy increased TRPV1 phosphorylation, localization to neuronal lipid rafts, and proximity to TLR4. These effects were also reversed by AIBP treatment. Regulation of TRPV1-TLR4 interactions and their associated lipid rafts by AIBP covaried with the enduring reversal of mechanical allodynia otherwise observed in CIPN. In addition, AIBP reduced intracellular calcium in response to the TRPV1 agonist capsaicin, which was increased in DRG neurons from paclitaxel-treated mice and in the naĂŻve mouse DRG neurons incubated in vitro with paclitaxel. Together, these results suggest that the assembly of nociceptive and inflammatory receptors in the environment of lipid rafts regulates nociceptive signaling in DRG neurons and that AIBP can control lipid raft-associated nociceptive processing

    Role of ERK1/2 activation and nNOS uncoupling on endothelial dysfunction induced by lysophosphatidylcholine

    No full text
    Background and aims: Lysophosphatidylcholine (LPC) - a main component of oxidized LDL -is involved in endothelial dysfunction that precedes atherosclerosis, with an increased superoxide anions and a reduced NO production via endothelial NO synthase (eNOS) uncoupling. However, there is no evidence about the mechanisms involved in neuronal NOS (nNOS) uncoupling. Extracellular signal-regulated kinase (ERK) is related to the control of NO production and inflammatory gene transcription activation in atherosclerosis. Our aim was to investigate the role of nNOS/ERK1/2 pathway on endothelial dysfunction induced by LPC, in mouse aorta and human endothelial cells. Methods: Thoracic aorta from wild type mice was used to perform vascular reactivity studies in the presence or absence of LPC. Human endothelial cells were used to investigate the effect of LPC on expression of nNOS and his products NO and H2O2. Results: LPC reduced acetylcholine (ACh)-induced vasodilation in mouse aorta (Emax(CT/LPC) = similar to 95 +/- 2/ 62 +/- 3%, p = 0.0004) and increased phenylephrine-induced vasoconstriction (Emax(CT/LPC) = similar to 4 +/- 0,1/ 6 +/- 0,1 mN/mm, p = 0.0002), with a reduction in NO (fluorescence intensity(CT/LPC) = 91 +/- 3/62 +/- 2 x 10(3), p = 0.0002) and H2O2 (fluorescence intensityCT/LPC = similar to 16 +/- 0,8/10 +/- 0,7 x 10(3), p = 0.0041) production evocated by ACh. An inhibition of nNOS by TRIM (Emax(CT/CT+TRIM) = similar to 93 +/- 1/43 +/- 3%, p = 0,0048; Emax(LPC/LPC+TRIM) = similar to 62 +/- 3/65 +/- 3%) or H2O2 degradation by catalase (Emax(CT/CT+cat) = similar to 93 +/- 1/46 +/- 2%, p < 0,001; Emax(LPC/LPC+cat) = similar to 62,8 +/- 3,2/60,5 +/- 4,7%) reduced the relaxation in the control but not in LPC group. PD98059, an ERK1/2 inhibitor, abolished the increase in vasoconstriction in LPC-treated vessels (Emax(LPC/LPC+PD) = similar to 6 +/- 0,1/3 +/- 0,1 mN/mm, p = 0.0001). LPC also reduced the dimer/monomer proportion and increased nNOS(ser852) phosphorylation. Conclusions: LPC induced nNOS uncoupling and nNOS(Ser852) phosphorylation, reduced NO and H2O2 production and improved superoxide production by modulating ERK1/2 activity in human and murine endothelial cells. (C) 2016 Elsevier Ireland Ltd. All rights reserved
    corecore