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T-cell activation during exacerbations: a longitudinal study in refractory asthma
E Mamessier1, A Nieves, A-M Lorec
1Université de Méditerranée, EA 3287, IFR125, France.
Allergy
|August 14, 2008
Summary
Asthma exacerbations involve T-cell shifts, with increased T helper 2 cells and decreased regulatory T (Treg) cells. During exacerbations, a mixed Th1/Th2 activation occurs, impairing Treg cell function and worsening asthma.
Area of Science:
- Immunology
- Respiratory Medicine
- Cell Biology
Background:
- Asthma exacerbations are a major cause of morbidity and healthcare costs.
- Preventing exacerbations requires understanding the underlying inflammatory processes.
- Severe refractory asthma (SRA) presents unique challenges in management.
Purpose of the Study:
- To investigate T-cell activation patterns during exacerbations in patients with severe refractory asthma.
- To elucidate the role of T helper (Th) cells and regulatory T (Treg) cells in asthma exacerbations.
Main Methods:
- Flow cytometry was used to quantify T-cell subsets and their cytokine production (IL-13, IFN-gamma, IL-4, IL-5, IL-10).
- Messenger RNA (mRNA) and protein levels of cytokines were analyzed.
- Treg cell function was assessed through depletion experiments.
- T-cell responses were examined in both blood and induced sputum.
Main Results:
- Baseline T-cell profiles in asthmatics showed increased T helper 2 (Th2) cells and decreased T helper 1 (Th1) and Treg cells.
- Prior to exacerbations, Th2 cells increased, followed by Th1 cells, in both blood and sputum.
- Treg cells and IL-10-producing T cells decreased during exacerbations.
- The suppressive capacity of Treg cells was diminished during exacerbations compared to baseline.
Conclusions:
- Asthma exacerbations are characterized by a shift from a baseline Th2-biased T-cell response to a mixed Th1/Th2 activation.
- A deficiency in Treg cells, present at baseline in SRA, is exacerbated during exacerbation events.
- These findings offer new insights into the pathophysiology of asthma exacerbations and potential therapeutic targets.
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