Carbon nanoparticles induce ceramide- and lipid raft-dependent signalling in lung epithelial cells: a target for a preventive strategy against environmentally-induced lung inflammation

Abstract

BackgroundParticulate air pollution in lung epithelial cells induces pathogenic endpoints like proliferation, apoptosis, and pro-inflammatory reactions. The activation of the epidermal growth factor receptor (EGFR) is a key event responsible for signalling events involving mitogen activated protein kinases specific for these endpoints. The molecular events leading to receptor activation however are not well understood. These events are relevant for the toxicological evaluation of inhalable particles as well as for potential preventive strategies in situations when particulate air pollution cannot be avoided. The current study therefore had the objective to elucidate membrane-coupled events leading to EGFR activation and the subsequent signalling cascade in lung epithelial cells. Furthermore, we aimed to identify the molecular target of ectoine, a biophysical active substance which we described to prevent carbon nanoparticle-induced lung inflammation.MethodsMembrane signalling events were investigated in isolated lipid rafts from lung epithelial cells with regard to lipid and protein content of the signalling platforms. Using positive and negative intervention approaches, lipid raft changes, subsequent signalling events, and lung inflammation were investigated in vitro in lung epithelial cells (RLE-6TN) and in vivo in exposed animals.ResultsCarbon nanoparticle treatment specifically led to an accumulation of ceramides in lipid rafts. Detailed analyses demonstrated a causal link of ceramides and subsequent EGFR activation coupled with a loss of the receptor in the lipid raft fractions. In vitro and in vivo investigations demonstrate the relevance of these events for carbon nanoparticle-induced lung inflammation. Moreover, the compatible solute ectoine was able to prevent ceramide-mediated EGFR phosphorylation and subsequent signalling as well as lung inflammation in vivo.ConclusionThe data identify a so far unknown event in pro-inflammatory signalling and contribute to the understanding of particle cell interaction and therefore to risk identification and risk assessment of inhalable xenobiotics. Moreover, as this cellular reaction can be prevented by the well tolerated substance ectoine, a molecular preventive strategy for susceptible persons against airway inflammation is proposed.

Intracellular Signal Modulation by Nanomaterials

“…Nanomaterials could also induce membrane receptor signaling such as shown for TiO 2 NPs which interact with toll-like receptors (Mano et al, 2013). Furthermore, CB NPs activate the epidermal growth factor receptor (EGFR), due to ceramide accumulation in lipid rafts (Peuschel et al, 2012). This lipid raft signaling induced by CB NPs has been shown to be dependent on oxidative stress induction.…”

“…This lipid raft signaling induced by CB NPs has been shown to be dependent on oxidative stress induction. Interestingly, the compatible solute ectoine prevented, ceramide-EGFR signaling and the subsequent inflammation in vivo (Peuschel et al, 2012). Lipid raft formation is also necessary for the induction of IL-1 beta secretion by TiO 2 (Morishige et al, 2010) and CB NPs can induce integrin mediated signaling (Weissenberg et al, 2010).…”

Carbon nanoparticle induced cytotoxicity in human mesenchymal stem cells through upregulation of TNF3, NFKBIA and BCL2L1 genes

“…Moreover, CNPs conferred a number of metabolic changes in hMSCs in a dose- dependent manner. Similarly, a few studies have reported cellular toxicity and apoptosis upon treating mammalian cells with CNPs in vitro (Sydlik et al, 2006;Peuschel et al, 2012).…”

Ectoine as a promising protective agent in humans and animals

“…However, this effect was not observed when lung inflammation was induced by bacterial lipopolysaccharide (35). Peuschel et al (36) reported that inhalational exposure to carbon nanoparticles in mice resulted in the accumulation of ceramides in lipid rafts of cell membranes, activation of epidermal growth factor receptor (EGFR), and lung inflammation. Animals additionally treated with ectoine, however, showed milder allergic reactions because ectoine seems to have inhibited ceramide-mediated EGFR phosphorylation.…”