Obesity in asthma: more neutrophilic inflammation as a possible explanation for a reduced treatment response

Authors

  • E. D. Telenga,

    1. Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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    • Both authors contributed equally.
  • S. W. Tideman,

    1. Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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    • Both authors contributed equally.
  • H. A. M. Kerstjens,

    1. Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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  • N. H. T. ten Hacken,

    1. Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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  • W. Timens,

    1. Department of Pathology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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  • D. S. Postma,

    1. Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    2. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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  • M. van den Berge

    Corresponding author
    1. Groningen Research Institute for Asthma and COPD, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
    • Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
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  • Edited by: Hans-Uwe Simon

Correspondence

Dr. Maarten van den Berge, University Medical Center Groningen (AA11), P.O. Box 30.001, 9700 RB Groningen, the Netherlands.

Tel.: +31-50-361912357

Fax: +31-50-3619320

E-mail: m.van.den.berge@umcg.nl

Abstract

Background

The incidence of asthma and obesity is increasing worldwide, and reports suggest that obese patients have more severe asthma. We investigated whether obese asthma patients have more severe airway obstruction and airway hyper-responsiveness and a different type of airway inflammation than lean asthmatics. Furthermore, we assessed the effect of obesity on corticosteroid treatment response.

Methods

Patient data from four well-documented asthma cohorts were pooled (n = 423). We evaluated FEV1, bronchial hyper-responsiveness (PC20) to either methacholine/histamine or adenosine 5′-monophosphate (AMP) (differential) cell counts in induced sputum and blood and corticosteroid treatment response in 118 patients.

Results

At baseline, FEV1, PC20 methacholine or histamine, and PC20 AMP values were comparable in 63 obese (BMI ≥30 kg/m2) and 213 lean patients (BMI <25 kg/m2). Obese patients had significantly higher blood neutrophils. These higher blood neutrophils were only seen in obese women and not in obese men. After a two-week treatment with corticosteroids, we observed less corticosteroid-induced improvement in FEV1%predicted in obese patients than in lean patients (median 1.7% vs 6.3% respectively, P = 0.04). The percentage of sputum eosinophils improved significantly less with higher BMI (P = 0.03), and the number of blood neutrophils increased less in obese than in lean patients (0.32 x103/μl vs 0.57 x103/μl, P = 0.046).

Conclusions

We found no differences in asthma severity between obese and nonobese asthmatics. Interestingly, obese patients demonstrated more neutrophils in sputum and blood than nonobese patients. The smaller improvement in FEV1 and sputum eosinophils suggests a worse corticosteroid treatment response in obese asthmatics.

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