A wake-like state in vitro induced by transmembrane TNF/soluble TNF receptor reverse signaling

Primary author: Cheryl Dykstra-Aiello

Primary college/unit: College of Veterinary Medicine
Campus: Spokane


Tumor necrosis factor (TNF) plays a role in regulating sleep. Neuronal activity enhances TNF expression. Co-cultured neuron/glia cells exhibit deeper sleep-like states after TNF administration. Both TNF and TNF receptors (R) are produced as transmembrane ™ proteins that, when cleaved, produce soluble (s) forms. Unlike conventional cell signaling induced by soluble (s) ligands binding to tm receptors, with immunocytes, sTNFR can bind tmTNF and reverse signal within the cell expressing tmTNF. Having previously shown sTNFR sleep inhibition in animals, we hypothesized that tmTNF-sTNFR binding would induce wake-like states in cells through reverse signaling.
Somatosensory cortical neurons/glia from wildtype (WT) mice and mice lacking either TNF (TNF-KO) or both TNFRs (TNFR-KO), were co-cultured and incubated on multi-electrode arrays. Daily one-hour electrophysiological recordings were taken on days 4 – 13 for development analyses. On day 14, a one-hour baseline was recorded prior to sTNFR treatment. Immediately post-treatment, recordings resumed for another hour. Synchronization of electrical activity (SYN), action potentials, slow wave power (SWP), and burstiness index (whole animal sleep defining measures) were used to characterize the emergence of these electrophysiological properties and sTNFR-induced changes.
Relative to WT, development rates were increased in both TNF-KO and TNFR-KO cells. Additionally, a sTNFR dose-dependent wake-like state was suggested by decreased SYN and SWP in TNFR-KO cells, but not in TNF-KO cells.
To our knowledge, this is the first demonstration of reverse TNF signaling in sleep/wake states. This provides a new way of viewing state regulation and associated potential clinical applications.