ABSTRACT
BACKGROUND: Methyl methacrylate (MMA) has been reported to cause histopathological changes in rodent nasal epithelium after inhalation challenges. Data in humans are lacking. METHODS: In this in vitro design 22 primary cell cultures taken from inferior turbinate tissue of healthy individuals were exposed to MMA concentrations of 50 ppm (German MAK-value) and 200 ppm. mRNA expression and cytokine release of inflammatory mediators were quantified after 4h and after 24h. Controls were exposed to synthetic air. Q-PCR analysis was performed for TNF-alpha, IL-1beta, IL-6, IL-8, MCP-1, GMCSF, Cox-1 and Cox-2. ELISA assays were performed from culture supernatants for TNF-alpha, IL-1beta, IL-6, IL-8, MCP-1 and GMCSF. RESULTS: Acute inductions of mRNA after 4h were observed for TNF-alpha, IL-1beta, IL-6, IL-8 and MCP-1 at 50 ppm. ELISA analysis of the described parameters did not reveal any significant upregulations at both concentrations after both 4h and 24h. CONCLUSIONS: The obtained data suggest that exposure of human respiratory epithelia in vitro to 50 ppm and to 200 ppm of MMA does not induce lasting upregulation of the inflammatory mediators measured in this study. The exposure limit of 50 ppm appears safe following these results obtained from human respiratory epithelia.
Subject(s)
Cytokines/metabolism , Epithelial Cells/drug effects , Methylmethacrylate/pharmacology , Nasal Mucosa/drug effects , RNA, Messenger/metabolism , Antimutagenic Agents/pharmacology , Cell Culture Techniques , Cell Survival/drug effects , Cells, Cultured , Chemokine CCL2/genetics , Chemokine CCL2/metabolism , Cyclooxygenase 1/genetics , Cyclooxygenase 1/metabolism , Cyclooxygenase 2/genetics , Cyclooxygenase 2/metabolism , Cytokines/genetics , Dose-Response Relationship, Drug , Enzyme-Linked Immunosorbent Assay , Epithelial Cells/cytology , Epithelial Cells/metabolism , Gene Expression Regulation/drug effects , Granulocyte-Macrophage Colony-Stimulating Factor/genetics , Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Humans , Interleukins/metabolism , Nasal Mucosa/cytology , Nasal Mucosa/metabolism , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Acetaldehyde has been shown to be cytotoxic and carcinogenic to the upper respiratory tract epithelium of rodents following long-term exposure. Most animal studies have concentrated on carcinogenicity and DNA-protein cross-link formation, while less is known about potential dose- and time-dependent induction of aldehyde-induced rhinitis in humans. In this in vitro study, 22 primary cell cultures established from inferior turbinate tissue of healthy individuals were exposed to acetaldehyde concentrations of 50 (German MAK value) or 500 ppm for 4 or 24 h. mRNA expression and protein levels of cytokines and other inflammatory mediators were quantified at the end of the 4- and 24-h exposures. Controls were exposed to synthetic air. Quantitative polymerase chain reaction (Q-PCR) analysis was performed for interleukin (IL)-6, IL-8, IL-1beta, monocyte chemotactic protein (MCP)-1, tumor necrosis factor (TNF)-alpha, GMCSF, Cox-1, and Cox-2. Enzyme-linked immunosorbent assay (ELISA) was performed from culture supernatants for IL-6, IL-8, IL-1beta, MCP-1, TNF-alpha, and GMCSF. Significant inductions of IL-1beta, TNF-alpha, and Cox-1 and Cox-2 mRNA were observed following exposure to > or =50 ppm acetaldehyde for 4 h. IL-6 and MCP-1 were also induced following a 4-h exposure to 500 ppm acetaldehyde. For all these parameters, effects were significantly stronger at the higher concentration. After 24-h of exposure only Cox-2 remained significantly elevated at 500 ppm but not at 50 ppm, while all other mediators had been downregulated. The obtained data suggest that with exposure to 500 ppm and remarkably also at the level of the occupational exposure limit of 50 ppm, an immediate transient upregulation of inflammatory mediator mRNA is induced, possibly leading to subclinical inflammatory effects.
