48th Annual Meeting of the Society of Toxicology (SOT) location:Baltimore, Maryland, US date:16-19 March 2009
Introduction: Asthma is one of the most prevalent chronic airway diseases, characterized by reversible airway obstruction, airway inflammation, and non-specific airway hyperreactivity. Up to 15% of all asthma cases in adults are due to chemical exposures at the workplace. The early identification of biomarkers of sensitization could help to move diagnosis to an earlier stage. Using a mouse model of chemical-induced asthma we explore the process of sensitization towards chemicals at the protein level.
Methods: On days 1 and 8, mice are treated on both ears with 0.3% toluene-2,4-diisocyanate (TDI, 20µl), or the vehicle (2:3, acetone-olive oil). On day 15, mice are oropharyngeally challenged with 0.01% TDI or vehicle. On day 16, airway hyperreactivity to methacholine and BAL cell count are carried out. Two-dimensional differential gel electrophoresis (2D-DIGE) was used to analyze the differential expression of proteins in auricular lymph nodes of TDI-treated mice and vehicle-treated mice.
Results: Sensitized mice exhibit enhanced airway reactivity to methacholine (2.6 fold increase) compared to vehicle-treated mice, accompanied by a neutrophil inflammation (50%). Proteome analysis of the auricular lymph nodes illustrate differential expression of 52 proteins comparing TDI and vehicle-treated (control) mice (p<0.01). 36 proteins are found to be significantly upregulated in sensitized mice. 21 proteins could already be identified by peptide mass fingerprinting. Among the identified proteins structural proteins such as vimentin and immune related proteins, such as lymphocyte specific protein-1 involved in neutrophil activation, were found.
Conclusion: This study demonstrates the use of 2D-DIGE in the search for (early) biomarkers of chemical-induced asthma. Further studies will have to point out whether (some of) these proteins could act as valuable biomarkers. Therefore, more samples (bronchoalveolar lavage fluid, serum,…) will be analysed.