Nse. In addition to performing phagocytosis they can release inflammat…

Nse. In addition to performing phagocytosis they can release inflammatory mediators such as cytokines and chemokines and they are crucially involved in destruction of microbes and particles using various enzymatic systems [10]. Cytochromes like CYP1B1 are also expressed by macrophages and these enzymes are part of the "digestive" and detoxifying machinery of these cells [8]. The xenobiotic metabolism can be divided into two phases: modification (phase I) and conjugation (phase II). An important group of phase I enzymes consists of the cytochrome P450 oxidases (CYP) which belong to the monoxygenases. In humans 57 CYPs are known and about 25 of them are considered to be involved primarily in the xenobiotic metabolisms [11]. Superfamily members are classified according to the similarity of their primary structure. The expression of the CYP1 subfamily can be induced by polycyclic aromatic hydrocarbons (PAH), which are ubiquitously occuring environmental carcinogens [12] and are particularly known to be present in cigarette smoke [13]. The induction of CYP1 genes is regulated by a heterodimer of the aryl hydrocarbon receptor (AhR) and the aryl hydrocarbon receptor nuclear translocator (Arnt) [14]. Two cytochromes, CYP1A1 and CYP1B1, are mainly involved PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/25751659 in the formation of ultimate carcinogenic diol-epoxides of PAH such as benzo[a]pyrene (BaP) [15]. The expression of these enzymes is largely extrahepatic and both enzymes are present in many tumor tissues [16,17]. CYP1B1 has been identified as a major P450 enzyme in normal humanblood monocytes [18] and CYP1B1 is also present in human lung and lung-derived cell lines [19]. Monocytes, macrophages and epithelial cells are affected by particles. CYP1B1 is involved in both, detoxification as well as metabolic activation of xenobiotics [12]. Thus it is important to address the question of whether and in what way particles affect CYP1B1. This study is aimed on the effects of carbon particles on the expression of CYP1B1 in monocytes/macrophages and bronchial epithelial cells and we demonstrate a pronounced down-regulation of mRNA expression and protein level of this important extrahepatic enzyme.ResultsEffect of particle exposure on CYP1B1 mRNA expression In earlier experiments using gene expression arrays, we noted a decreased expression of CYP1B1 mRNA Nelfinavir (Mesylate) in monocyte-derived macrophages (MDM) of patients with COPD (http://www.ncbi.nlm.nih.gov/geo/; accession number GSE8608). Since exposure of particles plays a major role in the etiology of this disease, we studied the effect of particles on cells of the monocyte/macrophage lineage. To cover a wider range of particle materials (chemistry) and their physical properties (size, surface structure) and because of economical reasons (cost-effectiveness) we initially used a mixture of both particles, ultrafine P90 (mean size 90 nm) and fine TiO2 (mean size 200 nm). We analyzed the effect of this mixture on CD14++ monocytes after 3h of exposure.Expression levels were calculated relative to corresponding mRNA level for -enolase in the same sample, such that negative values indicate a transcript prevalence that is less than that of -enolase in the same cell population. As shown in Fig. 1A, incubation of CD14++ monocytes with this mixture of ultrafine P90 and fine TiO2 resulted in a pronounced decrease of CYP1B1 mRNA transcripts (4,308 ?2,231) reflecting a 95-fold reduction compared to untreated cells (-45 ?37). LPS showed a minor effect with respect to CYP1B1 exp.