Results:
The current study was a case control study which included 96 subjects attending the allergy and immunology unit, microbiology and immunology department, Faculty of medicine, Zagazig University during the year 2021.They were divided into 2 groups, group 1 included healthy controls with a median age of 28 [ n=48] and group 2 included patients with allergic asthma according to Global Initiative for asthma consensus report (GINA), 2020 with a median age of 30 [ n=48].
Regarding the asthmatic patients, the mean value of age was 30.67±15.609, most of the patients were female (62.5%) and most of them lived in rural areas (54.16%). 39 patients (81.3%) had positive family history of atopy. All patients displayed positive skin prick test results to house dust mites, most of the patients (70.8%) were sensitive to D. pteronyssinus and 60.4% were sensitive to D. farina. 14 patients were mono sensitized to a single type of house dust mites and 34 patients were polysensitized to both types. As for the grade of asthma severity, 4 patients (8.3%) had grade 1severity, 24 patients (50%) had grade 2 asthma severity, 12 (25%) patients had grade 3 severity, and 8 patients (16.7%) had grade 3 asthma severity. (Table 1)
Concerning the control group, the mean value of age was 32.7± 11.2, most patients were males (85.3%) and 70.8% of them lived in rural areas. As per the family history of atopy, only 11 (22.9%) patients had positive family history of atopy and all of them displayed negative skin prick test results.
On comparing serum total immunoglobulin E (IgE) level between asthmatic patients and control subjects, there was a highly statistically significant difference between both groups (p=0.000). Asthmatic patients displayed a higher statistically significant level of serum total IgE. The mean serum IgE was equal to 233.3±103.4IU/ml in the asthmatic group and 84.4±18.6 IU/ml in the control group. (Table 2)
Similarly, there was a high statistically significant difference between both groups as regards serum zonulin level. Asthmatic patients displayed a higher statistically significant level of serum zonulin than control subjects. The mean serum zonulin was equal to 258.3±153.01 ng/ml in the asthmatic group and 80±13 ng/ml in the control group. (Table 2)
Factors affecting serum total IgE level were male sex, asthma grade, and positive skin prick test. Male patients displayed a statistically significant higher serum total IgE level (p=0.03). The mean value of serum total IgE was 272.89±141.33 among male patients and was 193.53±56.38 IU/ml among female patients. Besides, post hoc test showed a significant difference between grade 1 vs grade 2 as regards serum total IgE. As the asthma severity increased there was a significant corresponding increase in the serum total IgE (p=0.02). Moreover, there was a highly statistically significant difference as regards the mean value of serum total IgE between patients displaying positive skin prick test results and those displaying negative skin prick test results (p=0.002) The mean value of serum total IgE among patients displaying positive skin prick test results was 244.41±114.85 IU/ml. (Table 3)
With regard to the correlation between serum zonulin level and seum total IgE, it didn’t reach statistical significance (p=0.34) . (Table 4) Figure 2
As for the factors affecting serum zonulin level, they were residence and asthma grade. There was a statistically significant difference in the serum zonulin level between patients living in Urban areas and those living in rural areas. (p=0.002) The mean value of serum zonulin was significantly higher in patients living in urban areas and it equaled to 315.55±157.34 ng/ml. Post hoc test showed a highly statistically significant difference between grade 1 vs grade 2, grade 1 vs grade 3, grade 1 vs grade 4, grade 2 vs grade 4 and grade 3 vs grade 4 as regards serum zonulin level (p˂0.001). (Table 4) Figure 2
Grade of asthma had independent significant effect on zonulin level (p<0.001) while serum total IgE had no significant effect on zonulin level via linear regression analysis ( p= 0.684 NS). ( Table 5)
Roc curve was done to assess the validity of zonulin level for differentiation between (grade 1 or 2) vs (grade 3 or 4) (p=0.002). It displayed sensitivity equal to 80% and specificity equal to 71.4%. Its positive predictive value was equal to 66.7% and negative predictive value was equal to 83.3%. The cut off value of serum zonulin was ≥ 198 ng/ml. The area under the curve was 0.76. (Table 6) Figure 3