Abstract
Background: Airway inflammation and epithelial disruption are primary components of asthma. Secretoglobins (SCGB) and Trefoil Factors (TFF) are small secreted proteins which are involved in inflammation and epithelial restitution. Control of expression of the genes encoding these proteins is potentially by methylation of the promoter region of the genes. We hypothesized that in asthma, gene expression of specific SCGBs would be decreased, and of specific TFFs would be increased, and that the promoter region of the SCGB genes would be hypermethylated and that of the TFF genes would be hypomethylated, explaining the expressional differences. Method: Using a two-group unpaired design, individuals with (mild) asthma (n = 5) and individuals without asthma (n = 7) completed a medical history questionnaire, physical examination, spirometric pulmonary function testing and sputum-induction. Quantitative PCR was used for analysis of gene expression for TFF-1 TFF-3, SCGB1A1, SCGB3A1, and SCGB3A2, and a SEQUENOM Epityper was used for analysis of the genes promoter region methylation status. Result: In the asthma group, compared to the non-asthma group, gene expression was increased 1-fold for TFF-1 (p = 0.02) and 6-fold for TFF-3 (p = 0.03). SCGB1A1, SCGB3A1 and SCGB3A2 indicated an increase in expression in the asthmatic group. The methylation status of those promoter regions successfully analysed for each gene was similar between the two groups. Conclusion: Results indicate a difference in specific SCGB and TFF expression in asthma, and therefore, these genes could be involved in both the inflammation and epithelial restitution inherent in the disease. This differential gene expression appears to not be directly controlled by promoter region methylation.