Effect of clarithromycin on the expression of heme oxygenase-1 in the lung tissue of asthmatic rat

Objective: To investigate the protein expressions of HO-1 in the lung tissue of asthmatic rat and to study the regulation roleof clarithromycin on HO-1. To research whether the ratios of eosinophils to the total cell numbers (EOS%) in BALF, the numbers ofeosinophils in lung tissue (EOS), the percent content of blood carbon monoxide Hb (COHb) and the expressions of HO-1 has a correlationin the lung tissue of asthmatic rat. Methods: Thirty Sprague-Dawley (SD) male rats were randomly divided into 3 groups: the controlgroup (N group), asthma group (A group), CAM group (C group), each group had 10 rats. The assessment of the percent content of bloodcarbon monoxide Hb (COHb) was performed. The total cell number and differentiation cell numbers in bronchoalveolar lavage fluid(BALF) and the inflammatory cells of airway wall were observed, the protein expressions of HO-1 in airway wall was detected by immuno-histochemistry techniques. Results: The expression of HO-1 was mainly located in airway epithelium in the 3 groups (N, A, C) with theoptical densities being 0.07±0.01, 0.22±0.03, 0.14±0.02, respectively. The asthmatic group (group A) showed higher optical densities thanthat of the control group (group N) (P 0.001), the protein expressions of HO-1 in airway wall of group C was significantly lower thanthose of group A (P 0.01). There was a significant correlation between the expression of HO-1 in airway wall and the percent content ofblood carbon monoxide Hb (COHb) (r = 0.887, P 0.01), EOS% in BALF (r = 0.889, P 0.01), and the numbers of EOS in lung tissue(r = 0.883, P 0.01). Conclusion: The expression of HO-1 was increased significantly in the lung tissue of asthmatic rat, suggesting HO-1 might play a significant role in the pathogenesis of asthma. CAM demonstrates anti-inflammatory effects partly by downregulating theexpressions of HO-1.