Changes in erythrocyte polyunsaturated fatty acids and plasma eicosanoids level in patients with asthma

Background: To investigate the changes of polyunsaturated fatty acids (PUFAs) and their downstream eicosanoids in patients with asthma, the levels of erythrocyte membrane lipids and plasma lipid metabolites were examined. Methods: Erythrocyte membrane lipids were extracted and esterificated, and then fatty acid compositions were determined by gas chromatography. The concentrations of six eicosanoids of PGE(2), TXA(2), LTB4, PGE(1), 6-k-PGF(1 alpha) and PGF(2 alpha) in plasma were measured by ELISA. Results: The results showed that the contents of erythrocyte membrane fatty acids in patients with asthma were mainly composed of C16:0, C18:0, C18: 1, C18: 2(n-6), and C20:4(n-6). The ratio n-6/n-3 PUFAs in patients and health persons were (4.42 +/- 1.33):1 and (3.21 +/- 0.79): 1 (p < 0.01), showing statistically significant differences. ELISA results showed that the levels of plasma PGE(2), TXB2, and PGE(1) in patients were higher than health persons; and the levels of eicosanoids of PGF(2a) and 6-k-PGF(1 alpha) were significantly lower in patient group than healthy group (p < 0.05), but LTB4 was no obvious difference (p = 0.09). Increased ratio of n-6/n-3 PUFAs is consistent to the increased levels of pro-inflammatory PGE(2) and TXB2 and anti-inflammatory PGE(1) originated from C20: 4(n-6) and C18: 2(n-6), indicating that increased ratio of n-6/n-3 PUFAs and eicosanoids from n-6 PUFAs might promote the progress of airway inflammation of asthma. Conclusion: Changes of erythrocyte fatty acids, n-6/n-3 PUFAs ratio and the levels of plasma PGE2, TXB2, and PGE1 in patients with asthma were relevant to airway inflammation in some extent. Therefore, it could be proposed that increase of n-3/n-6 PUFAs ratio by diet supplementation of n-3 PUFAs might effectively improve airway inflammation in asthma.