PMX464, a thiol-reactive quinol and putative thioredoxin inhibitor, inhibits NF-kappaB-dependent proinflammatory activation of alveolar epithelial cells.

BACKGROUND AND PURPOSE: Subtle changes in the intracellular reduction-oxidation (redox) state can modulate nuclear factor-kappaB (NF-kappaB) activity. Thioredoxin-1 (Trx) is a small, ubiquitous, redox-active thiol (-SH) protein that, with thioredoxin reductase-1 (TrxR), modifies the redox status of NF-kappaB pathway components. PMX464 is a novel thiol-reactive quinol thought to inhibit the Trx/TrxR system. The aim of this work was to investigate whether PMX464 inhibited NF-kappaB-mediated proinflammatory activation of human type II alveolar epithelial cells (A549). EXPERIMENTAL APPROACH: Intercellular adhesion molecule-1 (ICAM-1), granulocyte-macrophage colony-stimulating factor (GM-CSF) and CXCL8, NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity were assessed in A549 cells stimulated with IL-1beta with or without PMX464 pretreatment. Effects of PMX464 on ICAM-1 expression in human lung microvascular endothelial cells (HLMVEC) were also investigated. For comparison, selected measurements (ICAM-1 and IkappaB-alpha phospho-IkappaB-alpha) were made on A549 cells after RNA interference-mediated silencing (siRNA) of Trx. KEY RESULTS: PMX464 reduced ICAM-1, GM-CSF and CXCL8 expression in IL-1beta-stimulated A549 cells and ICAM-1 in HLMVEC. PMX464 inhibited IL-1beta-induced NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit and factors involved in NF-kappaB activation; specifically, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity in A549. By contrast, Trx siRNA did not alter ICAM-1 expression or IkappaBalpha degradation/phosphorylation in IL-1beta-stimulated A549 cells. CONCLUSION AND IMPLICATIONS: PMX464 inhibits a proinflammatory response in A549 cells targeting the NFkappaB pathway above IKK. The lack of effect with Trx siRNA suggests that PMX464 acts on thiol proteins, in addition to Trx, to elicit anti-inflammatory responses in lung epithelial cells.

Influence of the pontine and medullary reticular formation on synchrony of gamma motoneurone discharge in the cat.

Discharges of gamma motoneurones were recorded from cut filaments of the nerve to the gastrocnemius medialis muscle in the cat decerebrated at an intercollicular level. Gamma motoneurones exhibited a background discharge in the absence of intentional stimulation, or could be made to discharge by continuous, innocuous stimulation of the skin of the heel. The discharges were periodic and regular (low coefficient of variation of interspike intervals), and no correlation was observed between the discharges of pairs of individual gamma efferents. Electrolytic lesion of the ipsilateral pontine and medullary reticular formation in the nucleus subcoeruleus, the nucleus reticularis gigantocellularis or the nucleus reticularis magnocellularis, invariably decreased regularity of discharge and resulted in short term synchrony. Lesions of the peri-aqueductal grey, the nucleus raphe dorsalis or the midline raphe nuclei did not induce synchrony. Surgical lesions in the locus coeruleus caused irregular firing and synchrony only when the lesion extended into the adjacent nucleus subcoeruleus. We conclude that monoaminergic neurones of the nucleus subcoeruleus, or a closely associated tegmental field, with axons descending through the gigantocellularis and magnocellularis fields, are the most likely origin of the bulbospinal control of synchronizing influences on gamma motoneurone discharge.