Results
Our study included 70 asthmatic children, 36 (51.4%) males and 34 (48.6%) females. They were divided according to severity of asthma into mild persistent asthma group that included 34 patients, moderate persistent asthma group that included 26 patients, and severe persistent asthma group that included 10 patients. Control group: included 30 apparently healthy children, 15 (50%) males and 15 (50%) females. Eosinophils count, IgE in the asthmatic group were significantly higher than the control group (p<.001). FEV1, FVC and FEV1/FVC were significantly lower in moderate and severe persistent asthma when compared with mild persistent one (Table 1).
For each subject the cellular composition of the nasal respiratory epithelial sample was determined. For the control group, the mean number of cells per high-powered field (400×) was 285 ±103, with 98.2% epithelial cells, 1.54% PMNs, 0.22% squamous cells, and 0.04% eosinophils. For the mild persistent asthma group, the mean number of cells per high-power field (400×) was 235 ± 75, with 95.4% epithelial cells, 4.06% PMNs, 0.40% squamous cells, and 0.14% eosinophils. For the moderate persistent asthma group, the mean number of cells per high-powered field (400×) was 214 ± 55, with 94.5% epithelial cells, 5.22% PMNs, 0.11% squamous cells, and 0.17% eosinophils. For the severe persistent asthma group, the mean number of cells per high-power field (400×) was 145 ± 85, with 91.22% epithelial cells, 8.28% PMNs, 0.15% squamous cells, and 0.35% eosinophils. Epithelial cells represented greater than 93% of the total cells isolated in all groups. The differences between analyzed groups were not statistically significant.
Relative gene expression levels of TMEM178 decreased in asthmatic children than control group (significant down regulation in asthma) and as regards to asthma severity, there was statistically significant decrease in TMEM178 expression levels with the increase of asthma severity. While, relative gene expression levels of CLCA1, SERPINB2 and Periostin showed statistically significant up regulation in the epithelial airway cells of children with asthma when compared with control, but there were no statistically significant differences between different degrees of asthma severity. Regarding FKBP5 relative gene expression, it was increased in asthmatic children but with no statistically significant difference when compared with control group (non-significant up regulation) and as regards asthma severity, there were no statistically significant differences between different groups. (Table 2)
Regarding performance characteristics of TMEM178 expression (2^-∆CT) as a predictor for asthma severity, the best cut off values for 2^-∆CT of the expressed TMEM178 gene with the highest specificity and sensitivity for discrimination between different degrees of asthma severity were determined and analyzed. Using 2.982 as a cut off value for 2^-ΔCt of TMEM178 expression, the sensitivity and specificity of TMEM178 to discriminate mild asthmatics from severe asthmatics was 97.1 % & 100 %, respectively. Additionally, TMEM178 mRNA expression (2^-ΔCt) at a cut off value of 2.617 discriminated moderate asthmatics from severe asthmatics with a sensitivity of 92.3 % and a specificity of 90 %. (Table 3)
Regarding to asthma control level, relative gene expression levels of TMEM178, CLCA1, SERPINB2 and Periostin were significantly up regulated in controlled group. While FKBP5 was significantly increased (up regulated) in partially to uncontrolled group (table 4)
Regarding to atopic status, relative gene expression levels of CLCA1, SERPINB2 and Periostin were significantly up regulated in atopic than non-atopic asthma while TMEM178 and FKBP5 relative gene expression levels showed no statistically significant differences between atopic and non-atopic asthma.