title: Elevated sputum interleukin-5 and submucosal eosinophilia in obese individuals with severe asthma.
abstract: BACKGROUND
  The relationship between airway inflammation and obesity in severe asthma is poorly understood.
  
  
  OBJECTIVE
  We sought to determine the relationship between sputum mediator profiles and the distribution of eosinophilic inflammation and obesity in people with severe asthma.
  
  
  METHODS
  Clinical parameters and eight mediators in sputum were assessed in 131 subjects with severe asthma from a single center categorized into lean, overweight, and obese groups defined by their body mass index. In an independent group of people with severe asthma (n = 45) and healthy control subjects (n = 19) eosinophilic inflammation was enumerated in bronchial submucosa, blood, and sputum and related to their body mass index.
  
  
  RESULTS
  Sputum IL-5 geometric mean (95% confidence interval) (pg/ml) was elevated in the obese (1.8 [1.2-2.6]) compared with overweight (1.1 [0.8-1.3]; P = 0.025) and lean (0.9 [0.6-1.2]; P = 0.018) subjects with asthma and was correlated with body mass index (r = 0.29; P < 0.001). There was no relationship among body mass index, the sputum cell count, or other sputum mediators. In the bronchoscopy group the submucosal eosinophil number in the subjects with asthma was correlated with body mass index (Spearman rank correlation, rs = 0.38; P = 0.013) and the median (interquartile range) number of submucosal eosinophils was increased in obese (19.4 [11.8-31.2]) (cells per square millimeter) versus lean subjects (8.2 [5.4-14.6]) (P = 0.006). There was no significant association between sputum or peripheral blood eosinophil counts and body mass index.
  
  
  CONCLUSIONS
  Sputum IL-5 and submucosal eosinophils, but not sputum eosinophils, are elevated in obese people with severe asthma. Whether specific antieosinophilic therapy is beneficial, or improved diet and lifestyle in obese asthma has antiinflammatory effects beyond weight reduction, requires further study.
authors.affiliation: 1 Institute for Lung Health, NIHR Respiratory Biomedical Research Unit, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom.
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Desai
authors.forename: Christopher
authors.initials: C
authors.lastname: Newby
authors.forename: Fiona A
authors.initials: FA
authors.lastname: Symon
authors.forename: Pranabashis
authors.initials: P
authors.lastname: Haldar
authors.forename: Sachil
authors.initials: S
authors.lastname: Shah
authors.forename: Sumit
authors.initials: S
authors.lastname: Gupta
authors.forename: Mona
authors.initials: M
authors.lastname: Bafadhel
authors.forename: Amisha
authors.initials: A
authors.lastname: Singapuri
authors.forename: Salman
authors.initials: S
authors.lastname: Siddiqui
authors.forename: Joanne
authors.initials: J
authors.lastname: Woods
authors.forename: Athula
authors.initials: A
authors.lastname: Herath
authors.forename: Ian K
authors.initials: IK
authors.lastname: Anderson
authors.forename: Peter
authors.initials: P
authors.lastname: Bradding
authors.forename: Ruth
authors.initials: R
authors.lastname: Green
authors.forename: Nita
authors.initials: N
authors.lastname: Kulkarni
authors.forename: Ian
authors.initials: I
authors.lastname: Pavord
authors.forename: Richard P
authors.initials: RP
authors.lastname: Marshall
authors.forename: Ana R
authors.initials: AR
authors.lastname: Sousa
authors.forename: Richard D
authors.initials: RD
authors.lastname: May
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Wardlaw
authors.forename: Chris E
authors.initials: CE
authors.lastname: Brightling
mesh_terms: D001249:Asthma / Q000150:complications / Q000276:immunology* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015992:Body Mass Index; D004802:Eosinophilia / Q000150:complications / Q000276:immunology* / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D015848:Interleukin-5 / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000276:immunology* / Q000378:metabolism; D020545:Respiratory Mucosa / Q000276:immunology* / Q000378:metabolism; D012720:Severity of Illness Index; D013183:Sputum / Q000276:immunology* / Q000378:metabolism
chemical_list: D015415:Biomarkers; D015848:Interleukin-5