title: Mono-2-ethylhexylphthalate (MEHP) induces TNF-α release and macrophage differentiation through different signalling pathways in RAW264.7 cells.
abstract: Epidemiological studies have associated indoor phthalate exposure with increased incidences and severity of asthma in children and adults, and inflammatory effects have been suggested as a possible mechanism. Recent studies report that phthalates may activate mitogen-activated protein (MAP) kinase p38 and various peroxisome proliferator-activated receptor (PPAR) isoforms. Here we confirm and extend these findings by investigating possible signalling pathways activated in the murine monocyte-macrophage cell line RAW264.7, using mono-2-ethylhexylphthalate (MEHP) as a model compound. MEHP exposure (0.3-1.0 mM) for 3h increased tumour necrosis factor (TNF)-α release and changed the cellular morphology into elongated spindle-like appearance, resembling more differentiated anti-inflammatory macrophages (M2). This was accompanied by increased expression of the macrophage differentiation marker CD163. Western analysis showed phosphorylation of p38 and Akt after 30 min exposure. Experiments using specific inhibitors suggested that MEHP-induced activation of both p38 and the phosphoinositide-3 (PI3) kinase/Akt pathway were involved in the release of TNF-α; whereas only PI3kinase seemed to be involved in differentiation. In contrast, inhibitors of PPARα and γ reduced differentiation, but did not affect TNF-α release. In conclusion, MEHP induced cytokine release and triggered differentiation of RAW264.7 cells, possibly into M2-like macrophages, but different signalling pathways appear to be involved in these responses.
authors.affiliation: Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway. Anette.Kocbach@fhi.no
authors.forename: Anette Kocbach
authors.initials: AK
authors.lastname: Bølling
authors.forename: Johan
authors.initials: J
authors.lastname: Ovrevik
authors.forename: Jan Tore
authors.initials: JT
authors.lastname: Samuelsen
authors.forename: Jørn A
authors.initials: JA
authors.lastname: Holme
authors.forename: Kirsten E
authors.initials: KE
authors.lastname: Rakkestad
authors.forename: Gro H
authors.initials: GH
authors.lastname: Mathisen
authors.forename: Ragnhild E
authors.initials: RE
authors.lastname: Paulsen
authors.forename: Mónica Suárez
authors.initials: MS
authors.lastname: Korsnes
authors.forename: Rune
authors.initials: R
authors.lastname: Becher
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives* / Q000494:pharmacology; D007150:Immunohistochemistry; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008856:Microscopy, Fluorescence; D051058:Oncogene Protein v-akt / Q000378:metabolism; D047493:PPAR alpha / Q000037:antagonists & inhibitors; D047495:PPAR gamma / Q000037:antagonists & inhibitors; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D047493:PPAR alpha; D047495:PPAR gamma; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D004051:Diethylhexyl Phthalate; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; C016599:mono-(2-ethylhexyl)phthalate