Depletion of CD8+ T cells enhances airway remodelling in a rodent model of asthma.

Airway remodelling is induced by persistent airway inflammation and may lead to severe asthma. T cells play a pivotal role in asthmatic airway inflammation but their role in remodelling is poorly understood. Although previous studies have revealed that CD8(+) T cells inhibit the late airway response and airway inflammation in a rat model of asthma, their effects on airway remodelling have not been evaluated. The aim of this study was to examine the role of CD8(+) T cells in airway remodelling. Brown Norway rats were sensitized with ovalbumin (OVA) on day 0. CD8(+) T cells in rats were depleted during the repeated challenges by treating them with a CD8alpha monoclonal antibody (OX-8). Control rats were treated with mouse ascites. Sensitized rats were challenged with OVA on days 14, 19 and 24 or were sham challenged with phosphate-buffered saline. On day 29, bronchoalveolar lavage and lung tissues were harvested. Repeated OVA inhalations evoked significant increases in the numbers of periodic acid-Schiff-positive epithelial cells and proliferating cell nuclear antigen-positive epithelial cells, and in airway smooth muscle mass compared to the control group. CD8-depleted rats had significant enhancement of these changes, principally affecting the large airways. These results suggest that endogenous CD8(+) T cells have inhibitory effects on airway remodelling in this model of asthma.