Effects Of Ursolic Acid On Cytokines Expression In Human Peripheral Blood Lymphocytes

Background and ObjectiveUrsolic acid is a pentacyclic triterpene compound in many herbs and human diet. It has been reported to possess a wide range of pharmacological properties, including anti-tumor, anti-inflammatory, immunoregulation and recovering hematopoiesis. You et al reported that ursolic acid elicited a dose dependent increase in NO and TNF-α production in the resting macrophages , thereby ursolic acid was considered a potential immunopotentiating agent. Helper T (Th) cell is crucial in immunity for its interaction with other cells, especially regulating the immune function through secreted cytokines. However, the effects of ursolic acid on T helper cell are very poorly understood. Here, we report the effects of ursolic acid on Thl type cytokine expression in peripheral blood lymphocytes, and detect the change of specific MAP kinas for Thl cell differentiation in order to know somemechanisms. MethodsThe peripheral blood lymphocytes (PBLC) from normal healthy human volunteers were stimulated optimally with phytohaemagglutinin (PHA) and phorbol myristate acetate (PMA) in the presence of varying concentrations of ursolic acid (5-30μM) . The proliferation of drugs treated PBLC were estimated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The levels of secreted interferon γ (IFN-γ) and interleukin 2 (IL-2) and mRNA expression were respectively determined by sandwich enzyme-linked immunosorbent assay (ELISA) and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Ursolic acid induced p38 MAPK activation were measured with Western blotting using anti-p38 MAPK phospho-specific antibodies that recognize the phosphrylated (on Thr180/Thr182). ResultsThe proliferation of ursolic acid treated PBLC were not significant difference at different concentration. ELISA and RT-PCR analysis showed that ursolic acid caused a dose-dependent inhibition of IFN-y and IL-2. Compared with the control group, thedecreases were statistically significant (P< 0.05) at the concentration above 20 uM, and theactivation levels of p38 MAPK decreased at 30 uM concentration.ConclusionsThis study showed the inhibition of Thl type cytokine gene expression and secretion by ursolic acid in normal peripheral blood lymphocytes were stimulated with mitogens, and they maybe trigger a signal pathway that depressed activation p38 MAPK. Since the chemical structure of ursolic acid resembles that of dexamethasone, a synthetic glucocorticoid, we assumed that ursolic acid might act as a glucocorticoid through glucocorticoid receptor-mediated manner. Therefore, ursolic acid may be used to treatallergic diseases and autoimmune diseases.