title: Inflammatory effects induced by selected limonene oxidation products: 4-OPA, IPOH, 4-AMCH in human bronchial (16HBE14o-) and alveolar (A549) epithelial cell lines.
abstract: Limonene, a monoterpene abundantly present in most of the consumer products (due to its pleasant citrus smell), easily undergoes ozonolysis leading to several limonene oxidation products (LOPs) such as 4-acetyl-1-methylcyclohexene (4-AMCH), 4-oxopentanal (4-OPA) and 3-isopropenyl-6-oxoheptanal (IPOH). Toxicological studies have indicated that human exposure to limonene and ozone can cause adverse airway effects. However, little attention has been paid to the potential health impact of specific LOPs, in particular of IPOH, 4-OPA and 4-AMCH. This study evaluates the cytotoxic effects of the selected LOPs on human bronchial epithelial (16HBE14o-) and alveolar epithelial (A549) cell lines by generating concentration-response curves using the neutral red uptake assay and analyzing the inflammatory response with a series of cytokines/chemokines. The cellular viability was mostly reduced by 4-OPA [IC50=1.6mM (A549) and 1.45mM (16HBE14o-)] when compared to IPOH [IC50=3.5mM (A549) and 3.4mM (16HBE14o-)] and 4-AMCH [IC50could not be calculated]. As a result from the inflammatory response, IPOH [50μM] induced an increase of both IL-6 and IL-8 secretion in A549 (1.5-fold change) and in 16HBE14o- (2.8- and 7-fold change respectively). 4-OPA [50μM] treatment of A549 increased IL-6 (1.4-times) and IL-8 (1.3-times) levels, while in 16HBE14o- had an opposite effect. A549 treated with 4-AMCH [50μM] elevate both IL-6 and IL-8 levels by 1.2-times, while in 16HBE14o- had an opposite effect. Based on our results, lung cellular injury characterized by inflammatory cytokine release was observed for both cell lines treated with the selected chemicals at concentrations that did not affect their cellular viability.
authors: Technische Universität München, Research Center Weihenstephan for Brewing and Food Quality, Alte Akademie 3, Freising-Weihenstephan, Germany; European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Chemical Assessment and Testing Unit, Ispra (VA), Italy. Electronic address: ldoreliasimona@yahoo.com.
authors: Dorelia
authors: D
authors: Lipsa
authors: European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Chemical Assessment and Testing Unit, Ispra (VA), Italy.
authors: Paolo
authors: P
authors: Leva
authors: European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Chemical Assessment and Testing Unit, Ispra (VA), Italy.
authors: Josefa
authors: J
authors: Barrero-Moreno
authors: Technische Universität München, Research Center Weihenstephan for Brewing and Food Quality, Alte Akademie 3, Freising-Weihenstephan, Germany.
authors: Mehmet
authors: M
authors: Coelhan
mesh_terms: D000447:Aldehydes / Q000633:toxicity*; D001980:Bronchi / Q000166:cytology / Q000473:pathology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018925:Chemokines / Q000378:metabolism; D000081005:Cyclohexane Monoterpenes; D003510:Cyclohexanes / Q000633:toxicity*; D053138:Cyclohexenes / Q000737:chemistry / Q000633:toxicity*; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D007659:Ketones / Q000633:toxicity*; D000077222:Limonene; D039821:Monoterpenes / Q000633:toxicity*; D010084:Oxidation-Reduction; D011650:Pulmonary Alveoli / Q000166:cytology / Q000473:pathology*; D013729:Terpenes / Q000737:chemistry / Q000633:toxicity*
chemical_list: C525009:4-acetyl-1-methylcyclohexene; D000447:Aldehydes; D018925:Chemokines; D000081005:Cyclohexane Monoterpenes; D003510:Cyclohexanes; D053138:Cyclohexenes; D016207:Cytokines; D007659:Ketones; D039821:Monoterpenes; D013729:Terpenes; C028940:limonene-1,2-epoxide; D000077222:Limonene; C575062:4-oxopentanal
keywords: Human pulmonary cell lines; Inflammatory response; Limonene oxidation products