Rationale. Viral infections in childhood are a risk factor for asthma development later in life. Respiratory viruses are the most frequent cause of asthma exacerbations. Adult asthmatic patients have an impaired immune response to respiratory viral infections. Aim. To evaluate innate immune response to viral infections in asthmatic children. Methods. Bronchial epithelial cells (BECs) were harvested by bronchial brushing during a clinically indicated bronchoscopy from asthmatic children (n=17; age 5.5±0.7) and non-atopic control subjects (n=8; age 4.8±0.5). BEC cultures were infected ex vivo with rhinovirus 16 (RV16). After 8 hours total mRNA was extracted and tested by Real Time PCR for interferon (IFN)-λ and IFN-β induction and for RV16 vRNA. When available (n=10 in asthmatics and n=6 in controls), bronchial biopsies were evaluated to quantify epithelial damage, basement membrane thickening, eosinophilic infiltration and IL-4 expression. Results. Ex vivo RV16 infections led to a significant IFN-λ and IFN-β mRNA induction in BECs from asthmatic and normal subjects (p<0.001 vs non infected cells). Induction in asthmatics was significantly lower as compared to normal subjects [IFN-β 1.8 103 (5.6 102 – 4.3 104) vs 1.7 105 (4.2 104 – 2.6 105) mRNA copies/µg RNA, respectively p<0.01; IFN-λ 1.00 103 (4.4 102 – 7.3 103) vs 2.8 104 (1.1 104 – 1.7 105) mRNA copies/µg RNA, respectively p<0.05]. Such a deficient IFNs induction was paralleled by a significant increased RV16 replication in BEC from asthmatic patients (p<0.05 vs normal subjects). Bronchial biopsies from asthmatics documented greater epithelial loss (median range: 59, 43-94%), increased eosinophilia (76, 0-441 cells/mm2) and a thickened basement membrane (5.6, 3.5-7.2 mm) than controls (32, 15-61% and 9, 0-14 cells/mm2 and 4.7, 3.1-4.9 mm; p≤ 0.05). Moreover, a prominent up-regulation of IL-4 was observed in asthmatic children as compared to controls (260, 101-620 vs 72, 14-119 cells+/mm2; p<0.005 ). Conclusions. Asthmatic children have an impaired innate immune response to viral infections similar to that documented in asthmatic adults. The Th2-oriented inflammatory environment of the airways of asthmatic children can be responsible for the aberrant innate immune response.
Bronchial epithelial cells from asthmatic children have a deficient innate immune response to rhinovirus infection
CONTOLI, Marco;PAPI, Alberto
2010
Abstract
Rationale. Viral infections in childhood are a risk factor for asthma development later in life. Respiratory viruses are the most frequent cause of asthma exacerbations. Adult asthmatic patients have an impaired immune response to respiratory viral infections. Aim. To evaluate innate immune response to viral infections in asthmatic children. Methods. Bronchial epithelial cells (BECs) were harvested by bronchial brushing during a clinically indicated bronchoscopy from asthmatic children (n=17; age 5.5±0.7) and non-atopic control subjects (n=8; age 4.8±0.5). BEC cultures were infected ex vivo with rhinovirus 16 (RV16). After 8 hours total mRNA was extracted and tested by Real Time PCR for interferon (IFN)-λ and IFN-β induction and for RV16 vRNA. When available (n=10 in asthmatics and n=6 in controls), bronchial biopsies were evaluated to quantify epithelial damage, basement membrane thickening, eosinophilic infiltration and IL-4 expression. Results. Ex vivo RV16 infections led to a significant IFN-λ and IFN-β mRNA induction in BECs from asthmatic and normal subjects (p<0.001 vs non infected cells). Induction in asthmatics was significantly lower as compared to normal subjects [IFN-β 1.8 103 (5.6 102 – 4.3 104) vs 1.7 105 (4.2 104 – 2.6 105) mRNA copies/µg RNA, respectively p<0.01; IFN-λ 1.00 103 (4.4 102 – 7.3 103) vs 2.8 104 (1.1 104 – 1.7 105) mRNA copies/µg RNA, respectively p<0.05]. Such a deficient IFNs induction was paralleled by a significant increased RV16 replication in BEC from asthmatic patients (p<0.05 vs normal subjects). Bronchial biopsies from asthmatics documented greater epithelial loss (median range: 59, 43-94%), increased eosinophilia (76, 0-441 cells/mm2) and a thickened basement membrane (5.6, 3.5-7.2 mm) than controls (32, 15-61% and 9, 0-14 cells/mm2 and 4.7, 3.1-4.9 mm; p≤ 0.05). Moreover, a prominent up-regulation of IL-4 was observed in asthmatic children as compared to controls (260, 101-620 vs 72, 14-119 cells+/mm2; p<0.005 ). Conclusions. Asthmatic children have an impaired innate immune response to viral infections similar to that documented in asthmatic adults. The Th2-oriented inflammatory environment of the airways of asthmatic children can be responsible for the aberrant innate immune response.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
