title: Full-length membrane-bound tumor necrosis factor-α acts through tumor necrosis factor receptor 2 to modify phenotype of sensory neurons.
abstract: Neuropathic pain resulting from spinal hemisection or selective spinal nerve ligation is characterized by an increase in membrane-bound tumor necrosis factor-alpha (mTNFα) in spinal microglia without detectable release of soluble TNFα (sTNFα). In tissue culture, we showed that a full-length transmembrane cleavage-resistant TNFα (CRTNFα) construct can act through cell-cell contact to activate neighboring microglia. We undertook the current study to test the hypothesis that mTNFα expressed in microglia might also affect the phenotype of primary sensory afferents, by determining the effect of CRTNFα expressed from COS-7 cells on gene expression in primary dorsal root ganglia (DRG) neurons. Co-culture of DRG neurons with CRTNFα-expressing COS-7 cells resulted in a significant increase in the expression of voltage-gated sodium channel isoforms NaV1.7 and NaV1.8, and voltage-gated calcium channel subunit CaV3.2 at both mRNA and protein levels, and enhanced CCL2 expression and release from the DRG neurons. Exposure to sTNFα produced an increase only in CCL2 expression and release. Treatment of the cells with an siRNA against tumor necrosis factor receptor 2 (TNFR2) significantly reduced CRTNFα-induced gene expression changes in DRG neurons, whereas administration of CCR2 inhibitor had no significant effect on CRTNFα-induced increase in gene expression and CCL2 release in DRG neurons. Taken together, the results of this study suggest that mTNFα expressed in spinal microglia can facilitate pain signaling by up-regulating the expression of cation channels and CCL2 in DRG neurons in a TNFR2-dependent manner.
authors.affiliation: Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System (Neurology and Geriatric Research Education and Clinical Center), Ann Arbor, MI, USA.
authors.forename: Zetang
authors.initials: Z
authors.lastname: Wu
authors.forename: Shiyong
authors.initials: S
authors.lastname: Wang
authors.forename: Sandy
authors.initials: S
authors.lastname: Gruber
authors.forename: Marina
authors.initials: M
authors.lastname: Mata
authors.forename: David J
authors.initials: DJ
authors.lastname: Fink
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D002522:Chlorocebus aethiops; D018920:Coculture Techniques; D004622:Embryo, Mammalian; D004797:Enzyme-Linked Immunosorbent Assay; D005727:Ganglia, Spinal / Q000166:cytology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000378:metabolism*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
chemical_list: C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D007473:Ion Channels; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D049452:Green Fluorescent Proteins
keywords: Neuroinflammation; Neuropathic pain; Tumor necrosis factor