BACKGROUND AND OBJECTIVE: Increased sputum neutrophilia has been observed in asthma, but also during normal ageing in asthmatics and non-asthmatics. It remains unclear what constitutes 'normal' neutrophil levels in different age groups. METHODS: We assessed the relationship between age and airway neutrophils of 194 asthmatics and 243 non-asthmatics (age range: 6-80 years). Regression analyses were used to assess this relationship adjusted for confounders including asthma status, atopy, gender, smoking and current use of inhaled corticosteroids (ICS). Age-corrected reference values for different age groups were determined using the 95th percentile of non-asthmatic participants. RESULTS: Age was positively associated with sputum neutrophils in both asthmatic and non-asthmatic adults (0.46% neutrophil increase/year (95% confidence interval (CI) 0.18, 0.73) and 0.44%/year (0.25, 0.64, respectively), but no association was found in the <20-year age category. Individuals with high sputum neutrophil counts (>95th percentile of non-asthmatic counts for any given age group) were significantly more likely to be asthmatic (odds ratio = 2.5; 95% CI: 1.3, 5.0), with the greatest effect observed in the older age group. Other factors that independently associated with increased sputum neutrophil levels included atopy in non-asthmatic adults, male gender and current use of ICS in asthmatic adults. Age-specific reference values for neutrophil percentage were under 20 years-76%, 20-40 years-62%, 40-60 years-63% and over 60 years-67%. CONCLUSIONS: Airway neutrophilia is related to age in adults, with a neutrophilic asthma phenotype present in older adults. The use of appropriate age-specific reference values is recommended for future studies aimed at elucidating the role of neutrophils in asthma.
BACKGROUND AND OBJECTIVE: Increased sputum neutrophilia has been observed in asthma, but also during normal ageing in asthmatics and non-asthmatics. It remains unclear what constitutes 'normal' neutrophil levels in different age groups. METHODS: We assessed the relationship between age and airway neutrophils of 194 asthmatics and 243 non-asthmatics (age range: 6-80 years). Regression analyses were used to assess this relationship adjusted for confounders including asthma status, atopy, gender, smoking and current use of inhaled corticosteroids (ICS). Age-corrected reference values for different age groups were determined using the 95th percentile of non-asthmatic participants. RESULTS: Age was positively associated with sputum neutrophils in both asthmatic and non-asthmatic adults (0.46% neutrophil increase/year (95% confidence interval (CI) 0.18, 0.73) and 0.44%/year (0.25, 0.64, respectively), but no association was found in the <20-year age category. Individuals with high sputum neutrophil counts (>95th percentile of non-asthmatic counts for any given age group) were significantly more likely to be asthmatic (odds ratio = 2.5; 95% CI: 1.3, 5.0), with the greatest effect observed in the older age group. Other factors that independently associated with increased sputum neutrophil levels included atopy in non-asthmatic adults, male gender and current use of ICS in asthmatic adults. Age-specific reference values for neutrophil percentage were under 20 years-76%, 20-40 years-62%, 40-60 years-63% and over 60 years-67%. CONCLUSIONS: Airway neutrophilia is related to age in adults, with a neutrophilic asthma phenotype present in older adults. The use of appropriate age-specific reference values is recommended for future studies aimed at elucidating the role of neutrophils in asthma.
Authors: Gwen S Skloot; Paula J Busse; Sidney S Braman; Elizabeth J Kovacs; Anne E Dixon; Carlos A Vaz Fragoso; Nicola Scichilone; Y S Prakash; Christina M Pabelick; Sameer K Mathur; Nicola A Hanania; Wendy C Moore; Peter G Gibson; Susan Zieman; Betina B Ragless Journal: Ann Am Thorac Soc Date: 2016-11
Authors: James G Wagner; Neil P Birmingham; Daven Jackson-Humbles; Qing Jiang; Jack R Harkema; David B Peden Journal: Free Radic Biol Med Date: 2013-12-11 Impact factor: 7.376
Authors: Paula J Busse; Janette M Birmingham; Agustin Calatroni; Joseph Manzi; Anna Goryachokovsky; Giselle Fontela; Alex D Federman; Juan P Wisnivesky Journal: J Allergy Clin Immunol Date: 2016-10-08 Impact factor: 10.793
Authors: Tolly G Epstein; Banurekha Kesavalu; Cheryl K Bernstein; Patrick H Ryan; Jonathan A Bernstein; Nives Zimmermann; Zana Lummus; Manuel S Villareal; Andrew M Smith; Peter H Lenz; David I Bernstein Journal: J Asthma Date: 2013-10-01 Impact factor: 2.515