Clinical Characteristics And Features Of Airway Inflammation Of Non-allergic Asthma

BLACKGROUND Asthma is defined as a chronic inflammatory disorder of the airways, which involves many cells and cellular elements. Allergic asthma is usually diagnosed on the basis of the medical history, recurrent airway obstruction, bronchial hyperresponsiveness and the presence of an underlying variably increased eosinophil numbers in the blood.Whereas some authors suggest that around 50% of asthmatics are allergic. Several studies have identified that symptomatic asthma can occur in the absence of eosinophilic inflammation, which is triggered by infection as a respiratory influenza-like illness. This subtype is termed non-allergic asthma.OBJECTIVE TO investigate the differences of clinical characteristics concerning allergic and non-allergic asthma. we also measured inflammatory markers in the induced sputum of asthma and fractional exhaled nitric oxide (FeNO) levels to explored the difference of airway inflammation between allergic and non-allergic asthma.METHODS 40 asthmatic patients in remission phase from asmatic specialty clinics in Zhongshan Hospital were enrolled in the study. Initially serum sampling for total IgE level determinations were carried out. Afterwards, fractional FeNO levels and pulmonary function were measured. At last, all the patients were underwent hypertonic saline solution(3.0%) challenge and sputum induction. Selected sputum portions were assayed for total cell count, cellular differential and supernatantⅠ1-4,IL-8,L-13,MPO and ECP level. All the data were recored and analyzed with SPSS 16.RESULTS Compared with the allergic asthma, the non-allergic asthma group had a greater onset age (42.06±12.64 vs 25.50±17.26year). The total rate of allergic disease was lower in the non-allergic asthma than in the allergic asthma group (45% vs 95%). The non-allergic asthma group had lower IgE levels (63.30±65.81 vs 833.8±1393.93 IU/ml, P=0.004). The percentage of eosinophil in induced sputum of allergic patients were markedly higher than those of non-allergic group(15.00±14.30% vs 6.54±7.96%, P=0.048). The percentage of neutroph in induced sputum of allergic patients were markedly lower than those of non-allergic group(38.78±25.39%,55.14±22.79%, P=0.046). IL-4 level in the non-allergic group was significantly lower than the allergic group (17.61±9.98 vs 24.64±9.43 pg/ml, P=0.041); IL-8 level was no significant difference between non-allergic group and allergic group (717.74±314.82 vs 540.72±366.20 pg/ml, P=0.114); IL-13 level in the non-allergic was significantly lower than the allergic group (17.61±9.98 vs 24.64±9.43 pg/ml, P=0.008); MPO level was no significant difference between non-allergic group and allergic group(3.57±3.59 vs 2.46±1.44 pg/ml); ECP level in the non-allergic was significantly lower than the allergic group (30.98±28.95 vs 91.78±101.95 pg/ml, P=0.024). FeNO levels were lower in the non-allergic group than those of allergic group (24.8±14.62ppb vs 49.04±25.06 ppb, p=0.01). In the non-allergic group, IL-8 were positively correlated to the sputum neutrophil percentage (R=0.606, P=0.005); In the allergic group, ECP were positively correlated to the sputum eosinophil percentage (R=0.534, P=0.015). In the allergic group, there was a linear correlation between FeNO levels and the ACT scores(R=0.609, P=0.004). In the non-allergic group, there was a linear correlation between FeNO levels and the ACT scores (R=0.72, P=0.000). In the allergic group, there was a linear correlation between FeNO levels and the percentage of eosinophil in induced sputum(R=0.657, P=0.002). In the non-allergic group, there was a linear correlation between FeNO levels and the percentage of eosinophil in induced sputum(R=0.493, P=0.027).CONCLUSION:Compared with the allergic asthma, the non-allergic asthma group had a greater onset age. They had no asthma family history and allergic disease. The non-allergic asthma group had lower IgE in blood and lower eosinophil levels in induced sputum. The percentage of neutroph in induced sputum of non-allergic patients were markedly higher than those of allergic group. There is a significant difference between the airway inflammation of allergic and non-allergic asthma. Eosinophils play a dominant role in the pathogenesis of allergic asthma, but in non-allergic asthma, neutrophils play a more important role. IL-4,IL-13 can be taken as inflammatory markers in allergic asthma patients; IL-8 can be taken as inflammatory markers in non-allergic asthma patients. FeNO levels were higher in the allergic group than those of non-allergic group. There was a linear correlation between FeNO levels and the percentage of eosinophil in induced sputum.