Corticosteroids affect nitric oxide generation, total free radicals production, and nitric oxide synthase activity in monocytes of asthmatic patients.

Airways inflammation, a pathological hallmark of asthma, is associated with the recruitment of pro-inflammatory and inflammatory cells like eosinophils, polymorphonuclear leucocytes cells, mononuclear cells, macrophages, epithelial desquamation, and airways remodeling with sub-epithelial fibrosis. Activated inflammatory cells along with the resident cells can generate pro-inflammatory mediators including oxidants such as superoxide radicals, reactive oxygen species (ROS), and reactive nitrogen species. One of such inflammatory mediator that has received considerable attention is the nitric oxide (NO(•)) generated by pulmonary macrophageal/epithelial cells. In this study, we have explored that systemic monocytes also get activated in asthma to produce oxidants like ROS and NO(•). We estimated the NO(•) production, nitric oxide synthase (NOS) activity, inducible NOS (iNOS) mRNA levels and total free radical activity (TFRA) in blood monocytes of healthy control subjects, untreated asthmatic patients, patients on corticosteroid for less than 6 months and patients on corticosteroid for more than 6 months. Increase in NOS activity, NO(•) levels, and TFRA was observed in monocytes of asthmatic patients. The increase was found to be associated with the transcriptional upregulation of iNOS gene and severity of disease. Highest values of NOS activity, NO(•), and iNOS mRNA were found in the patients with acute asthma. Corticosteroid administration was found to be effective in reversing the induction of iNOS mRNA levels, NOS activity and NO(•) levels. Corticosteroids controlled asthma appears to have association with NOS, NO(•), and TFRA in systemic monocytes of the patients.