TNF‐α dependent NF‐κB activation in cultured canine keratinocytes is partly mediated by reactive oxygen species

Abstract

The cytokine TNF-alpha plays a major role in inflammatory and immunological reactions of canine skin. With respect to a possible therapeutic modulation, we investigated the role of the transcription factor NF-kappa B and the involvement of reactive oxygen species (ROS) in the TNF-alpha signalling pathway in cultured canine keratinocytes. TNF-alpha treatment resulted in activation of NF-kappa B which was partially inhibited by the antioxidant alpha-lipoic acid. Using the cytochrome c reduction test no superoxide production could be detected in the supernatant of TNF-alpha stimulated keratinocytes. However, TNF-alpha dependent intracellular hydrogen peroxide production was demonstrated spectroscopically. With electron energy loss spectroscopy (EELS) significant hydrogen peroxide formation was detected in the mitochondria, the endoplasmic reticulum, the cytosol and partially on the plasma membrane of the keratinocytes. Hence, ROS possibly play an important role in the TNF-alpha signalling pathway leading to NF-kappa B activation in canine skin. An adjunctive therapy with natural potent antioxidants modulating NF-kappa B overactivation in canine cutaneous inflammation may be of therapeutic benefit.

Identification of genes regulated by Dexamethasone in multiple myeloma cells using oligonucleotide arrays

“…Since MAD-3/IkB-a protein binds to NFkB and prevents its nuclear translocation and activation, we next examined whether Dex-induced MAD-3/ IkB-a prevents NF-kB function in MM.1S cells using an electromobility shift assay (EMSA) of NF-kB DNA binding in nuclear extracts from Dex-treated MM.1S cells. As in our and other previous studies (Kohler et al, 2001;Hideshima et al, 2001a,b), TNF-a was used to induce NF-kB activation in MM.1S cells, in the presence or absence of Dex. As shown in Figure 2c, Dex decreases DNA binding following TNF-a induction of NF-kB in MM.1S cells.…”

Suppression of TNF-alpha-induced MMP-9 expression by a cell-permeable superoxide dismutase in keratinocytes

“…Several studies reported that TNF-α can induce ROS generation, which is involved in intracellular signaling cascades leading to pro-inflammatory genes, and this is suppressed by various antioxidants (10,11). These results suggest that prevention of ROS generation is one strategy to control inflammatory skin diseases.…”

“…Previous studies have implied the involvement of TNF-α-induced oxidative stress in up-regulation of MMP-9. TNF-α can increase the levels of reactive oxygen species (ROS) both directly and indirectly, which in turn activates NF-κB, a redox-sensitive transcriptional factor (9)(10)(11). ROS such as superoxide anion (O2 − ) and hydrogen peroxide (H2O2) can act as second messengers in signaling cascades leading to expression of many pro-inflammatory genes (12,13).…”

Tumor Necrosis Factor-Alpha-Nuclear Factor-Kappa B-Signaling Enhances St2b2 Expression during 12-O-Tetradecanoylphorbol-13-acetate-Induced Epidermal Hyperplasia

“…The associated signaling is mediated by various cytokines and regulatory factors, such as tumor necrosis factor-alpha (TNFa) and interleukins, which are involved in epidermal differentiation and dyskeratosis. 18,19) Indeed, TNFa levels increase when epidermis is exposed to TPA.…”

“…The associated signaling is mediated by various cytokines and regulatory factors, such as tumor necrosis factor-alpha (TNFa) and interleukins, which are involved in epidermal differentiation and dyskeratosis. 18,19) Indeed, TNFa levels increase when epidermis is exposed to TPA.20,21) TNFa binding to TNF receptor (TNFR) results in activation of a number of transcription factors, including nuclear factor-kappa B (NF-kB). Moreover, treating keratinocytes with anti-inflammatory drugs suppresses TPAinduced increases in Ch-ST activity, 13,22) suggesting that TNFa-NF-kB signaling mediates TPA-induced enhancement of St2b2 expression.…”