Lycopene, quercetin and tyrosol prevent macrophage activation induced by gliadin and IFN-γ Daniela De Stefano a, ⁎ , Maria Chiara Maiuri a , Vittorio Simeon a , Gianluca Grassia a , Antonio Soscia b , Maria Pia Cinelli b , Rosa Carnuccio a a Dipartimento di Farmacologia Sperimentale, Via D. Montesano, 49, Università degli Studi di Napoli “Federico II”, 80131 Naples, Italy b Dipartimento di Scienze Biomorfologiche e Funzionali, Via S. Pansini, 5, Università degli Studi di Napoli “Federico II”, 80131 Naples, Italy Received 5 February 2007; received in revised form 23 March 2007; accepted 26 March 2007 Available online 6 April 2007 Abstract Oxidative stress plays an important role in inflammatory process of celiac disease. We have studied the effect of the lycopene, quercetin and tyrosol natural antioxidants on the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) gene expression in RAW 264.7 macrophages stimulated by gliadin in association with IFN-γ. The IFN-γ plus gliadin combination treatment was capable of enhancing iNOS and COX-2 gene expression and nuclear factor-κB (NF-κB), interferon regulatory factor-1 (IRF-1) and signal transducer and activator of transcription-1α (STAT-1α) activation induced by reactive oxygen species generation at 24 h. Lycopene, quercetin and tyrosol inhibited all these effects. The results here reported suggest that these compounds may represent non toxic agents for the control of pro-inflammatory genes involved in celiac disease. © 2007 Elsevier B.V. All rights reserved. Keywords: Celiac disease; Gliadin; Interferon-gamma; Transcription factors; RAW 264.7 macrophage 1. Introduction Celiac disease, an enteropathy caused by permanent intoler- ance to gluten/gliadin, is characterized by a complex interplay between genetic and environmental factors (Sollid, 2005). The disease in its typical form is histologically characterized by villous atrophy, crypt cell hyperplasia, and increased number of intra- epithelial lymphocytes (Sollid, 2005). The mechanisms by which gluten/gliadin damages the intestinal mucosa of celiac patients remain unclear. A large body of evidence indicates a dysregulated immune response to gluten-derived peptides in celiac patients (Sollid, 2005). However, beside the immunologic pathway, the direct cytotoxic action of gliadin peptides against intestinal mucosa has been postulated as one of the mechanisms underlying the pathogenesis and the progression of celiac disease (Maiuri et al., 1996; Maiuri et al., 2003; Gianfrani et al., 2005). It is well known that toxic gluten peptides are presented by macrophages in the lamina propria and recognised by gliadin antigen specific CD4 + T cells (Sollid, 2005). As a result, secreted mediators, such as IFN-γ, may cause activation of macrophages which, in turn, produce pro-inflammatory cytokines contributing to the damage of the mucosal matrix (Kontakou et al., 1995; Pender et al., 1996; Ciccocioppo et al., 2005). Although the molecular mechanisms involved in the inflammatory process of celiac disease have not been completely elucidated, a large body of data suggests the involvement of transcription factors such as nuclear factor-κB (NF-κB), signal transducer and activator of transcription-1α (STAT-1α) and interferon regulatory factor-1 (IRF-1) (Salvati et al., 2003; De Stefano et al., 2006). These transcription factors are dependent on the intracellular redox state (Pahl, 1999; Ramana et al., 2000; Kroger et al., 2002) and can cooperate in order to promote synergistically transcriptional activity of pro- inflammatory genes (Ohmori and Hamilton, 1993; Kinugawa et al., 1997). Binding of IFN-γ to its receptor induces activation of STAT-1α which binds to a specific consensus sequence, termed the IFN-γ activation site (GAS), of IRF-1 promoter and induces IRF-1 (Seidel et al., 1995; Decker et al., 1991). Furthermore, the IRF-1 gene promoter has been described as containing a composite GAS/κB element (Sims et al., 1993; Harada et al., 1994) and cooperative regulation of transcription by IRF-1 and NF-κB has been previously described (Garoufalis et al., 1994; European Journal of Pharmacology 566 (2007) 192 – 199 www.elsevier.com/locate/ejphar ⁎ Corresponding author. Tel.: +39 81 678430; fax: +39 81 678403. E-mail address: dadestef@unina.it (D. De Stefano). 0014-2999/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.ejphar.2007.03.051