Objective: To investigate the effect of folic acid on homocysteine (Hcy)-induced chemokine secretion and NADPH oxidase activity in human monocytes.
Methods: Human monocytes from healthy volunteers were incubated with Hcy (100 micromol/L) with or without folic acid (5 micromol/L) for 24 h; MCP-1 and IL-8 were assessed by ELISA. DCFH-DA was added to monitor intracellular ROS production on confocal microscopy. A cytochrome c reduction assay was used to measure NADPH oxidase activity.
Results: The Hcy-induced secretion of MCP-1 and IL-8 was significantly reduced by folic acid [(1.88 +/- 0.51) ng/ml vs. (4.36 +/- 0.72) ng/ml vs. (2.40 +/- 0.60) ng/ml and (4.9 +/- 1.9) ng/ml vs. (12.7 +/- 1.5) ng/ml vs. (7.2 +/- 1.9) ng/ml, all P < 0.05]. The Hcy-induced production of ROS was also significantly attenuated by folic acid. Moreover, the Hcy-induced NADPH oxidase activity increase was significantly inhibited by cotreatment with folic acid.
Conclusion: Folic acid may attenuate oxidative stress induced by Hcy by reducing NADPH oxidase activity in monocytes.