Autor(es):
Marques, Liliana 
; Robert, Lorenne ; Auriac, Anne ; Canonne-Hergaux, François ; Costa, Luciana
Data: 2012
Identificador Persistente: http://hdl.handle.net/10400.18/1322
Origem: Repositório Científico do Instituto Nacional de Saúde
Assunto(s): Determinantes Imunológicos em Doenças Crónicas
Descrição
This work was supported by National Institute of Health Dr Ricardo Jorge, I.P, INSERM (Institut National de la Santé et de la Recherche Médicale), CNRS (Centre National de la Recherche Scientifique), ANR (Agence Nationale de la
Recherche, France; ANR- 08-GENO-000) , Fundação para a Ciência e Tecnologia (Grant SFRH/BD/48671/2008) and BioFIG (B Center for Biodiversity, Functional and Integrative Genomics). Atherosclerosis (ATH) is recognized as a chronic inflammatory condition and it is the leading cause of cardiovascular disease. Atherogenesis is characterized by the accumulation and oxidation of LDL (oxLDL) in the vessel wall and subsequent infiltration, activation of lymphocytes and monocytes, these later ones differentiating into macrophages and subsequently into foam cells. The recruitment of immune cells to the site of lesion contributes to a local pro-inflammatory state that will promote the development of the atheroma plaque and progression of the disease. However, the exact mechanisms involved in this process are not fully understood. One hypothesis is the contribution of oxidative stress mediated by metals such as iron. Previous authors have shown high iron content in foam cells and also accumulation of hemoglobin and ferritin in the areas rich in foam cells. Herein, we investigate a possible pathway for cellular iron accumulation by testing the effect of pro-inflammatory as well as pro-atherogenic stimuli in the expression of proteins involved in iron efflux from macrophages.
Mouse bone marrow-derived macrophages (BMDM) were treated with LPS, iron or/and oxLDL. The expression of ferroportin (Fpn, iron exporter), beta-amyloid precursor protein (APP, ferroxidase), ceruloplasmin (Cp, ferroxidase) and hemoxygenase-1 (HO-1, heme catabolism) were analyzed by western blot of subcellular fractions (cytosol, membrane and lipid raft fractions). Oil Red O staining was used to follow foam cell differentiation by oxLDL treatment.
APP and HO-1 were shown to be upregulated by both iron and LPS, being recruited to lipid rafts enriched fractions in BMDM. Fpn, present also in lipid rafts, was upregulated by iron and downregulated by LPS confirming our previous observations. Such modulation of proteins involved in iron efflux by inflammatory stimuli could also contribute to disruption of iron metabolism in plaque macrophages. In addition, foam cell differentiation of BMDM by oxLDL was accelerated in the presence of iron. These observations suggest that iron in plaque could be a pro-atherogenic factor. Moreover, effect of oxLDL expression and localization of iron-related proteins on lipid raft microdomains may constitute an important pathway for iron efflux disruption in the plaque environment and is under investigation.
