Immunoregulatory mechanisms of an optimal Chinese herbal monomer compound in mice with allergic rhinitis

Abstract

To study the immunoregulatory effect of an optimal Chinese herbal monomer compound, which consists of three monomers, namely, icariin, baicalin and Astragalus saponin I, in a mouse model of allergic rhinitis. A mouse model of allergic rhinitis was established by intraperitoneal injection of ovalbumin and aluminum hydroxide gel suspension. The splenic lymphocytes of the mice were separated, cultured in 96-well plates and divided into three groups: control group, concanavalin A group and compound group. Splenic lymphocyte proliferation was detected by cell counting kit-8 method at different time points. Cell cycle distribution was observed by flow cytometry (FCM) also at different time points. The changes of intracellular calcium concentration of splenic lymphocytes were measured by fluorescence microplate reader after the cells were incubated with fluorescence probe Fluo-3/AM. The Chinese herbal monomer compound could inhibit cell proliferation induced by concanavalin A (P<0.01). And the inhibition presented a time-effect relationship. With extending of the action time, the inhibition rate gradually increased and reached peak at the 48th hour. FCM test revealed the fact that concanavalin A could promote cells to enter into the mitosis by reducing the percentage of cells in G0/G1 phases while increasing the percentage of cells in S and G(2)/M phases. Compared with the concanavalin A, the compound could increase the percentage of cells in G(0)/G(1) phases and at the same time reduce the percentage of cells in S and G(2)/M phases at different time points, with the effect most significant at the 24th hour (P<0.05 or P<0.01). The results of the test taken by the fluorescence microplate reader revealed that the fluorescence value of the concanavalin A group increased with time in the previous 24 h while the compound could reduce this trend obviously, thus reduce the intracellular calcium concentration (P<0.01). The Chinese herbal monomer compound can inhibit the proliferation of cultured splenic lymphocytes of mice with allergic rhinitis. The effects of the compound of lowering intracellular calcium concentration and arresting cell cycle at G(0)/G(1) phases from entering into S and G(2)/M phases are responsible for its antiproliferation activity.