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Allergen-induced asthma is characterized by airway eosinophilia and recruitment of helper T (Th) Type 2 lymphocytes. We hypothesized that lymphocyte-associated chemokines contribute to allergen-induced airway inflammation. Sixteen subjects with asthma were phenotyped according to their response to inhaled antigen as single- or dual-phase responders, and then underwent bronchoscopy and segmental allergen bronchoprovocation. Bronchoalveolar lavage fluids were obtained before and 48 hours after segmental challenge with allergen to determine the cellular response and patterns of Th1 and Th2 chemokines and cytokines. Airway cells, cytokines, and lymphocyte-associated chemokines increased after segmental challenge. Th2 chemokines (thymus and activation-regulated chemokine, macrophage-derived chemokine) correlated with airway eosinophils and concentrations of interleukin-5 and -13. In contrast, airway lymphocytes correlated with both Th2 and Th1 (monokine-induced by IFN-gamma, IFN-gamma-inducible protein-10) chemokines. Notably, when subjects were analyzed according to the presence of a late-phase response, concentrations of both types of lymphocyte-associated chemokines were significantly greater in subjects with a dual-response phenotype. Our findings suggest that both Th2 and Th1 chemokines may be involved in allergen-induced airway inflammation. However, asthma subjects with a dual-responder phenotype have greater generation of chemokines that may lead to enhanced airway inflammation and obstruction after allergen exposure. [ABSTRACT FROM AUTHOR]

In addition to its central role in hemostasis, thrombin may play a role in inflammation and remodeling. To investigate the contribution of thrombin to allergic airway inflammation in asthma, we used an enzymatic assay to determine thrombin activity in bronchoalveolar lavage fluid obtained from 19 subjects with atopic asthma before (Day 0) and 48 hours after (Day 2) segmental bronchoprovocation with antigen. Thrombin activity increased from 0 (0, 2.9) on Day 1 to 41.1 (0.3, 75.6) U x 10(-3)/ml on Day 2 (p = 0.002) and correlated with total protein levels in lavage fluid on Day 2 (r = 0.885, p < 0.001). After antigen challenge, thrombin activity also showed significant correlations with interleukin-5 (r = 0.66, p = 0.002), transforming growth factor beta1 (r = 0.70, p < 0.001), fibronectin (r = 0.85, p < 0.001) and tissue factor (r = 0.55, p = 0.03) levels in lavage fluid. Furthermore, Day 2, but not Day 0 lavage fluid, induced proliferation of human airway fibroblasts. This mitogenic effect was significantly reduced with hirudin, a specific thrombin inhibitor. Taken together, our findings suggest that allergen-driven airway inflammation in asthma is associated with enhanced potential for fibroblast proliferation that is related, at least in part, to increased thrombin activity. We propose that enhanced thrombin activity provides a potential link between allergic inflammation and initiation of airway remodeling. [ABSTRACT FROM AUTHOR]