Increased expression of collagen receptors: α1β1 and α2β1 integrins on blood eosinophils in bronchial asthma.

Background Eosinophils are one of the major effector cells in bronchial asthma. Their infiltration of airways correlates with the asthma severity. Recruitment and activation of eosinophils are partially mediated by integrins α₄β₁ and α₄β₇. Collagens type I and IV constitute important components of extracellular matrix and vascular basement membrane, respectively. Therefore, collagen-binding integrins (α₁β₁ and α₂β₁) may also play a role in eosinophil lung infiltration. Objective To evaluate the possible presence of α₁β₁ and α₂β₁ integrins on peripheral blood eosinophils from asthmatic subjects. Methods Collagen receptors were studied on eosinophils separated by immunomagnetic CD16-negative method from healthy donors ( n=13) and patients with moderate persistent atopic bronchial asthma ( n=15). Surface receptor identification was performed by flow cytometry and cell adhesion assay. Results Eosinophils isolated from the patients showed increased expression of both α₁β₁ and α₂β₁ integrins as compared with healthy controls. Moreover, adhesive function of eosinophils to collagen type IV was inhibited by snake venom disintegrins: viperistatin and obtustatin. These disintegrins contain KTS active motif and are specific inhibitors of α₁β₁ integrin. Conclusion We demonstrated for the first time that collagen receptors: α₁β₁ and α₂β₁ integrins are overexpressed on the surface of peripheral blood eosinophils of asthmatic subjects. Further studies may reveal potential application of KTS-disintegrins or their structural analogs for therapy of bronchial asthma. [ABSTRACT FROM AUTHOR]