Activation of NF-κB by alloferon through down-regulation of antioxidant proteins and IκBα

Abstract

Alloferon is a 13-amino acid peptide isolated from the bacteria-challenged larvae of the blow fly Calliphora vicina. The pharmaceutical value of the peptide has been well demonstrated by its capacity to stimulate NK cytotoxic activity and interferon (IFN) synthesis in animal and human models, as well as to enhance antiviral and antitumor activities in mice. Antiviral and the immunomodulatory effectiveness of alloferon have also been supported clinically proved in patients suffering with herpes simplex virus (HSV) and human papilloma virus (HPV) infections. To elucidate molecular response to alloferon treatment, we initially screened a model cell line in which alloferon enhanced IFN synthesis upon viral infection. Among the cell lines tested, Namalva was chosen for further proteomic analysis. Fluorescence difference gel electrophoresis (DIGE) revealed that the levels of a series of antioxidant proteins decreased after alloferon treatment, while at least three glycolytic enzymes and four heat-shock proteins were increased in their expression levels. Based on the result of our proteomic analysis, we speculated that alloferon may activate the NF-κB signaling pathway. IκB kinase (IKK) assay, Western blot analysis on IκBα and its phosphorylated form at Ser 32, and an NF-κB reporter assay verified our proteomics-driven hypothesis. Thus, our results suggest that alloferon potentiates immune cells by activating the NF-κB signaling pathway through regulation of redox potential. Since NF-κB activation is involved in IFN synthesis, our results provide further clues as to how the alloferon peptide may stimulate IFN synthesis.