Expression of epithelial markers in nocturnal asthma.

Abstract

Although the airway epithelium participates in inflammation and repair, the circadian expression of epithelial cell markers involved in these processes has not been investigated. We sought to determine whether expression of CD51 (vitronectin and fibronectin receptor), CD54 (intercellular adhesion molecule-1), HLA-DR (activation marker), CD29 (beta1 integrin), CD49b (collagen receptor), and CD11b (complement receptor) exhibit a circadian rhythm in asthma. Eleven patients with nocturnal asthma (NA), 9 subjects with nonnocturnal asthma (NNA), and 10 control subjects underwent bronchoscopy at 4 PM and 4 AM in a random order 1 week apart, with brushing of the proximal and distal airways. The percentage of cells staining for a particular marker was determined. At 4 PM, HLA-DR in the proximal airways and CD54 in the distal airways was significantly greater in control subjects as compared with asthmatic subjects (HLA-DR, control subjects: 10.0% [range, 5.0% to 21.0%]; NNA: 8.0% [range, 4.0% to 14.5%] NA: 3.5% [range, 2.0% to 6.0%], P = .01; CD54, control subjects: 17.0% [range, 8.0% to 25.0%], NNA: 8.0% [range, 5.3% to 11.5%], NA: 7.0% [range, 4.0% to 15.0%], P = .O;). At 4 AM, CD51 in the distal airways was significantly greater in patients with NA as compared with patients with NNA and control subjects (control subjects, 23.0% [range, 13.8% to 30.5%]; NNA, 32.0% [range, 13.0% to 35.0%]; NA, 40.0% [range, 23.0% to 50.0%], P = .05). Expression of CD51 in the distal airways correlated with the degree of airway obstruction (r = -0.57, P = .001). Control subjects exhibited significant circadian variation in the expression of HLA-DR in the proximal airways and CD54 in the distal airways. The increased CD51 at night in patients with NA may be related to increased airway inflammation and repair processes in response to injury. The circadian changes in CD54 and HLA-DR in control subjects require further study to determine their significance. (J Allergy Clin