Evaluation of correlation between airway and serum inflammatory markers in asthmatic patients

CONTEXT: Asthma is one of the most common chronic diseases all over the world, resulting from a state of persistent sub-acute inflammation of the airways. Beside local inflammation, systemic inflammation is also present, which can be shown by increased levels of C-reactive protein (CRP). One of the most important cells in this disease is eosinophil, and sputum eosinophilia is used for its diagnosis. AIMS: The purpose of the present study was to compare and evaluate the correlation between CRP level and sputum eosinophilia in asthmatic and control subjects. MATERIALS AND METHODS: A total of 61 patients suffering from mild-to-moderate asthma participated in this study. They were divided into two groups based on whether they used inhaled steroid or not. Sputum was induced by ultrasonic nebulizer, and then samples of peripheral venous blood were collected to measure peripheral cell count and CRP by Enzyme-linked immunosorbent assay (ELISA). Thirty-seven healthy subjects were selected and their blood samples were taken. Thirty-seven healthy subjects were selected and their blood samples were taken. RESULTS: Thirty asthmatic patients in user group (14 females/16 males) with the mean age of 39.4±9.37 years, 31 asthmatic patients in non-user group (13 females/18 males) with the mean age of 35.5±8.87 years, and 37 healthy controls (17 females/20 males) were included in our study. The mean serum concentration of CRP was 2.6 μg/mL, 3.32 μg/mL, and 1.16 μg/mL in user, non-user, and control groups, respectively. Compared to healthy controls, serum concentrations of high sensitivity-CRP (hs-CRP) significantly increased in the non-user group (P=0.0001), and user group as well. (P=0.016). The number of sputum eosinophils and peripheral blood eosinophils significantly increased in the non-users compared to the healthy controls (P=0.0001, P=0.003, respectively). In the non-user group, serum hs-CRP levels correlated negatively with FEV(1) and positively with numbers of sputum eosinophils, which was not statistically significant. Atopy status, age, and sex did not affect hs-CRP levels in both asthmatic groups. CONCLUSIONS: It was found that serum concentrations of hs-CRP significantly increased in asthmatic patients, and in the steroid-native group it partly correlated with FEV(1) and numbers of sputum eosinophils. It suggests that serum hs-CRP can indirectly indicate the degree of airway inflammation.