Changes in Adenosine Metabolism in Asthma. A Study on Adenosine, 5&#39-NT, Adenosine Deaminase and Its Isoenzyme Levels in Serum, Lymphocytes and Erythrocytes

Abstract

Background: Adenosine deaminase (ADA) and 5ʹ-nucleotidase (5ʹ-NT) play a crucial role in adenosine metabolism in healthy individuals. Adenosine is an inflammatory mediator of asthma. Changes in adenosine metabolism and role of ADA and 5ʹ-NT in regulating adenosine level in asthmatics and correlation of these changes with severity of asthma are not clearly understood. Methods: In this study, we screened 5217 patients, of which 2416 were diagnosed with asthma. Further, of 2416 asthmatics, only 45 patients who strictly fulfilled the selection criteria were enrolled in the study. The patients were classified into mild, moderate and severe persistent groups; each group consisted of fifteen patients. Fifteen healthy subjects served as controls. Adenosine levels and activities of 5ʹ-NT, total ADA, ADA1 and ADA2 in serum, lymphocytes and erythrocytes were determined. The data were analysed statistically and p < 0.05 was considered significant. Results: In asthma, adenosine levels in serum, lymphocytes and erythrocytes were found to be raised significantly. A significant reciprocal correlation existed between adenosine levels in serum, lymphocytes and erythrocytes of asthmatics and FEV1%. The 5ʹ-nucleotidase activity in serum and lymphocytes was raised in moderate and severe persistent groups and an inverse correlation existed between 5ʹ-nucleotidase activity and FEV1% whereas in erythrocytes it was raised only in severe persistent group and FEV1% had no correlation with the 5ʹ-nucleotidase activity. The activities of total ADA, ADA1 and ADA2 were decreased in serum and lymphocytes of moderate and severe persistent asthmatics and a positive correlation existed between total ADA and FEV1%. In eryth-* Corresponding author. J. Sharma et al.34 rocytes, total ADA activity increased in mild persistent group but remained unchanged in moderate and severe persistent groups. Conclusion: The present study suggests that adenosine levels tend to increase in serum, lymphocytes and erythrocytes with the severity of bronchial asthma. The balance between ADA and 5ʹ-NT determines the levels of adenosine in serum and lymphocytes which may result in pathogenesis of asthma, or vice versa.

Activity of Several Purine Metabolic Enzymes in Sera of Pregnant Women

“…The enzymes 5-NT and ADA perform central roles in the adenosine metabolism in healthy persons, with 5′-nucleotidase (5′-NT, EC.3.1.3.5) catalyzing the hydrolysis of the phosphoric ester bonding of 5′-ribonucleotides to the corresponding ribonucleoside and phosphate (4) . The main function of the 5′-NT enzyme is the transfer of the group phosphate of AMP to adenosine (5) .…”