IgE is associated with exacerbations and lung function decline in COPD

Abstract

Background: Both allergen-specific IgE and total IgE in serum play a major role in asthma. However, the role of IgE in chronic obstructive pulmonary disease (COPD) is poorly understood. It was the aim of this study to systematically analyze the relationship between serum IgE levels and disease characteristics in large COPD cohorts.

Methods: COSYCONET is a comprehensively characterized cohort of patients with COPD: total IgE and IgE specific to common aeroallergens were measured in serum of 2280 patients, and related to clinical characteristics of the patients. WISDOM is another large COPD population (2477 patients): this database contains the information whether total IgE in serum was elevated (≥ 100 IU/l) or normal in patients with COPD.

Results: Both in COSYCONET and WISDOM, total IgE was elevated (≥ 100 IU/l) in > 30% of the patients, higher in men than in women, and higher in currently than in not currently smoking men. In COSYCONET, total IgE was elevated in patients with a history of asthma and/or allergies. Men with at least one exacerbation in the last 12 months (50.6% of all men in COSYCONET) had higher median total IgE (71.3 IU/l) than men without exacerbations (48.3 IU/l): this difference was also observed in the subgroups of not currently smoking men and of men without a history of asthma. Surprisingly, a history of exacerbations did not impact on total IgE in women with COPD. Patients in the highest tertiles of total IgE (> 91.5 IU/ml, adjusted OR: 1.62, 95% CI 1.12-2.34) or allergen-specific IgE (> 0.19 IU/ml, adjusted OR: 2.15, 95% CI 1.32-3.51) were at risk of lung function decline (adjusted by: age, gender, body mass index, initial lung function, smoking status, history of asthma, history of allergy).

Conclusion: These data suggest that IgE may play a role in specific COPD subgroups. Clinical trials using antibodies targeting the IgE pathway (such as omalizumab), especially in men with recurrent exacerbations and elevated serum IgE, could elucidate potential therapeutic implications of our observations.

Keywords: COPD; Exacerbations; IgE; Lung function decline.

Fig. 1

Distribution of IgE in serum. Shown are total IgE and allergen-specific IgE (as measured by the SX1 screening test) levels in the COSYCONET cohort. Box plots display the median (line within the box), interquartile range (edges of the box) and extremes (vertical lines). The dotted lines show currently accepted cut-offs for normal values. The differences between men and women were highly significant (***: p < 0.001)

Fig. 2

IgE and history of asthma or allergies. Shown are total IgE and allergen-specific IgE (as measured by the SX1 screening test) levels in patients with or without a history of asthma or allergies (COSYCONET cohort). The bars show median values with interquartile ranges. ***: p < 0.001

Fig. 3

IgE and risk of lung function decline. A Lung function trajectories in the COSYCONET cohort. Shown are relative changes in FEV₁ in the 3 groups (group A: increasing FEV₁; group B: stable FEV₁; group C: declining FEV₁). B and C Comparison of mean concentrations of total IgE (B) or allergen-specific IgE (as measured by the SX1 screening test, C) between group B (stable FEV₁) and group C (declining FEV₁). D Risk of declining FEV₁, according to the tertiles of total IgE or allergen-specific IgE (SX1) in serum

Fig. 4

IgE and exacerbation history. Shown are total IgE and allergen-specific IgE (as measured by the SX1 screening test) levels in patients without and in patients with at least one exacerbation in the last 12 months prior to IgE measurement (COSYCONET cohort). The bars show median values with interquartile ranges. The difference between men with and without exacerbations was highly significant (***: p < 0.001)