PT  - JOURNAL ARTICLE
AU  - Roxane Boivin
AU  - Amandine Vargas
AU  - Josiane Lefebvre-Lavoie
AU  - Anne-Marie Lauzon
AU  - Jean-Pierre Lavoie
TI  - Inhaled corticosteroids modulate the (+)insert smooth muscle myosin heavy chain in the equine asthmatic airways
AID  - 10.1136/thoraxjnl-2014-205572
DP  - 2014 Dec 01
TA  - Thorax
PG  - 1113--1119
VI  - 69
IP  - 12
4099  - http://thorax.bmj.com/content/69/12/1113.short
4100  - http://thorax.bmj.com/content/69/12/1113.full
SO  - Thorax2014 Dec 01; 69
AB  - Rationale Overexpression of the (+)insert smooth muscle myosin heavy chain (SMMHC) isoform could contribute to airway bronchospasm by increasing the velocity of contraction. Whether the (+)insert isoform is present in the small airways and its expression is reversible in asthma are unknown.Objectives To determine the anatomical location and the expression kinetics of the (+)insert SMMHC isoform in airways of horses with heaves and to evaluate its modulation in response to disease status.Methods We evaluated the (+)insert SMMHC isoform in the airways of horses with heaves during disease exacerbation and remission, and in controls. The expression kinetics of the SMMHC (+)insert was then assessed at multiple time points in two studies: first, in horses with heaves treated for a 1-year period with antigen avoidance alone, inhaled corticosteroids alone or both; second, in horses with heaves before and after a 30-day natural antigen exposure. Gene expression analysis was assessed by quantitative PCR and protein expression was confirmed by targeted mass spectrometry.Measurements and main results The (+)insert SMMHC isoform was significantly increased in central and peripheral airways, but not in the trachea of heaves-affected horses in clinical exacerbation when compared horses with heaves in remission and controls. Both corticosteroid administration and antigen avoidance led to a significant reduction of the (+)insert expression in the airways. The (+)insert SMMHC isoform was not significantly increased in airways after 1 month of antigenic re-exposure.Conclusions The (+)insert SMMHC expression is increased throughout the bronchial tree in horses with heaves and reversible by corticosteroids administration and antigen avoidance.