title: Steroid treatment can inhibit nuclear localization of members of the NF-κB pathway in human disc cells stimulated with TNF-α.
abstract: Steroid applications are able to repress inflammatory activity in various conditions, including herniation of the nucleus pulposus (HNP), by inhibiting tumour necrosis factor (TNF)-α, but the effects of long-term use are unknown. Here, we investigated the effect of dexamethasone (DEXA) on TNF-α-stimulated intervertebral disc cells by monitoring the expression and localization of NF-κB in the cytoplasm and nucleus. Cultured human intervertebral disc cells were left untreated or treated with only TNF-α, only DEXA, or with TNF-α and DEXA simultaneously. Cytoplasmic and nuclear proteins were extracted and Western blotted after 10 min, 1 or 2 h, to evaluate the expression of p50, p65, p52, and p100 (components of NF-κB). Immunofluorescence analysis was used to determine the subcellular localization of the proteins at 1 h. DEXA had limited effects on NF-κB expression in TNF-α-stimulated disc cells within the first 10 min. At 1 h, DEXA prevented the TNF-α-stimulated translocation of p50, p52, and p65. After 2 h, DEXA reduced the nuclear expression of p50, p65, and p52. Thus, DEXA resulted in delayed expression of NF-κB components and inhibited the translocation of p50, p52, and p65 to the nucleus, which would prevent expression of the corresponding genes. Therefore, following stimulation with TNF-α, transcriptional regulation of NF-κB in disc cells is mainly mediated via the classical pathway, but also to some extent via the alternative pathway. Hence, blockade of sub-acute inflammatory changes in HNP can be achieved by early injection of steroids, whereas long-term injection of a steroid may initiate NF-κB autophosphorylation.
authors.affiliation: Department of Orthopedics, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, Republic of Korea.
authors.forename: Meiling
authors.initials: M
authors.lastname: Quan
authors.forename: Sang-Eun
authors.initials: SE
authors.lastname: Park
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Lin
authors.forename: Myung-Wha
authors.initials: MW
authors.lastname: Hong
authors.forename: Seong-Yel
authors.initials: SY
authors.lastname: Park
authors.forename: Young-Yul
authors.initials: YY
authors.lastname: Kim
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002467:Cell Nucleus / Q000737:chemistry*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000737:chemistry*; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D007403:Intervertebral Disc / Q000166:cytology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000032:analysis / Q000378:metabolism; D052003:NF-kappa B p52 Subunit / Q000032:analysis / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000032:analysis / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D000893:Anti-Inflammatory Agents; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D052003:NF-kappa B p52 Subunit; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone