Differential expression of phosphorylated NF-kappaB/RelA in normal and psoriatic epidermis and downregulation of NF-kappaB in response to treatment with etanercept

• Published in: Journal of investigative dermatology Vol. 124; no. 6; pp. 1275 - 1283
• Main Authors: Lizzul, Paul F, Aphale, Abhishek, Malaviya, Rama, Sun, Yvonne, Masud, Salman, Dombrovskiy, Viktor, Gottlieb, Alice B
• Format: Journal Article
• Language: English
• Published: United States 01-06-2005
• Subjects: Adult; Anti-Inflammatory Agents, Non-Steroidal - therapeutic use; Cell Differentiation - drug effects; Cell Proliferation - drug effects; Down-Regulation; Epidermis - metabolism; Epidermis - pathology; Etanercept; Humans; Immunoglobulin G - therapeutic use; Middle Aged; NF-kappa B - antagonists & inhibitors; NF-kappa B - metabolism; Phosphorylation; Psoriasis - drug therapy; Psoriasis - metabolism; Psoriasis - pathology; Receptors, Tumor Necrosis Factor - therapeutic use; Recombinant Fusion Proteins - therapeutic use; Single-Blind Method; Skin - metabolism; Transcription Factor RelA
• ISSN: 0022-202X

Etanercept, a recombinant human tumor necrosis factor (TNF) receptor fusion protein, is FDA approved for psoriasis and psoriatic arthritis. TNFalpha increases the synthesis of proinflammatory cytokines and leads to the activation of multiple signaling pathways, including nuclear factor kappa B (NF-kappaB). The Rel/NF-kappaB transcription factors play a central role in numerous cellular processes, including the stress response and keratinocyte proliferation and differentiation. Utilizing a phosphorylation-specific antibody, we examined the expression of active nuclear NF-kappaB/RelA via immunohistochemistry in normal skin, non-lesional psoriatic skin, lesional psoriatic skin, and lesional skin from patients treated with etanercept. There was no expression of active nuclear NF-kappaB in the normal epidermis, whereas a basal level of constitutive active phosphorylated NF-kappaB/RelA was present in uninvolved epidermis from psoriasis patients. There was also significant upregulation of active phosphorylated NF-kappaB/RelA in the epidermis from psoriatic plaques. Serial biopsies from psoriasis patients treated with etanercept at 1, 3, and 6 mo demonstrated a significant downregulation of phosphorylated NF-kappaB/RelA, which correlated with decreases in epidermal thickness, restoration of normal markers of keratinocyte differentiation, and clinical outcomes. These data suggest that activation of NF-kappaB plays a significant role in the pathogenesis of psoriasis and that a potential mechanism of action for TNF-targeting agents is downregulation of NF-kappaB transcriptional activity.