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Published on: January 21, 2018
Associations between nasal torquetenovirus load and spirometric indices in children with asthma
Massimo Pifferi1, Fabrizio Maggi, Elisabetta Andreoli
1Department of Pediatrics, University of Pisa, Pisa, Italy.
Insights
Torquetenovirus (TTV) in nasal fluid was studied in children with asthma. Higher TTV loads correlated with poorer lung function and increased airway inflammation in asthmatic children, suggesting TTV may worsen asthma symptoms.
Area of Science:
- Pediatric Pulmonology
- Virology
- Immunology
Background:
- Asthma is a common chronic respiratory disease in children.
- Torquetenovirus (TTV) is a widespread human virus with largely unknown clinical significance.
- Previous studies have not investigated the role of TTV in pediatric asthma.
Purpose of the Study:
- To investigate the presence and viral load of TTV in nasal fluid of children with asthma.
- To determine the association between TTV nasal load and lung function indices in pediatric asthma.
- To explore the relationship between TTV load and airway inflammation markers in asthmatic children.
Main Methods:
- Quantification of TTV DNA in nasal lavage fluid from 59 children with persistent asthma and 30 healthy controls using quantitative PCR.
- Spirometry to assess lung function parameters including forced expiratory flow (FEF) and forced expiratory volume (FEV).
- Measurement of eosinophil cationic protein (ECP) levels in sputum as a marker of airway inflammation.
Main Results:
- Nasal TTV loads and positivity rates in children with asthma were comparable to healthy controls.
- A significant inverse correlation was observed between nasal TTV load and key lung function indices (FEF(25%-75%), FEV1/FVC, FEF(25%-75%)/FVC) in asthmatic children.
- Higher nasal TTV loads were associated with more frequent signs of reduced airflow and elevated sputum ECP levels in children with asthma, unlike in controls.
Conclusions:
- This study is the first to report TTV infection status in children with asthma.
- Nasal TTV load is inversely correlated with lung function and positively associated with airway inflammation in pediatric asthma.
- TTV may play a role as a contributing factor in the lung impairment observed in childhood asthma.
Abstract:
Fifty-nine children with well-controlled, mild to moderate persistent asthma were studied for the presence and load of torquetenovirus (TTV) in nasal fluid. Rates of TTV positivity and mean nasal TTV loads were not dissimilar to those observed in the general population and in a group of 30 age- and residence-matched healthy control children without a history of asthmatic disease. However, in the children with asthma, 3 important indices of lung function--forced expiratory flow (FEF) in which 25% and 75% of forced vital capacity (FVC) is expired (FEF(25%-75%)), forced expiratory volume in 1 s/FVC, and FEF(25%-75%)/FVC--showed an inverse correlation with nasal TTV load. Furthermore, signs of reduced airflow were more frequent in the children with asthma who had high nasal TTV loads (> or =6 log(10) DNA copies/mL of nasal fluid) than they were in those who had low nasal TTV loads (<6 log(10) DNA copies/mL of nasal fluid), despite similar therapy regimens. In contrast, the control children showed no associations between nasal TTV load and the spirometric indices. Levels of eosinophil cationic protein in sputum were also greater in the children with asthma who had higher nasal viral burdens than they were in those who had lower nasal viral burdens. These findings are the first report of TTV infection status in children with asthma and suggest that TTV might be a contributing factor in the lung impairment caused by this condition.
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