Cycloastragenol mediates activation and proliferation suppression in concanavalin A-induced mouse lymphocyte...

Cycloastragenol (CAG) is a molecule isolated from various species in the genus Astragalus. Although the regulatory activity of Astragalus on immune system has been investigated, the effect of CAG on activated lymphocytes is poorly understood.

We aimed to biologically address the possible anti-inflammation potential of CAG on concanavalin A (Con A)-mediated mouse lymphocyte pan-activation model.

Mouse lymphocytes were obtained from spleens and subjected to Con A for 24 h. Herein, the cells were treated with different concentrations of CAG. Cell viability was assayed by MTT. Pretreated by CAG and stimulated by Con A, the expression of CD69 and CD25, Th1/Th2/Th17 cytokines, cell cycle, proliferation and intracellular Ca²⁺ concentration ([Ca²⁺]_i) were analyzed by flow cytometry.

The results declared that CAG significantly downregulated both CD69 and CD25 expressed on Con A activated CD3 + T cells' surface, as well as inhibiting proliferation of activated lymphocytes. In addition, CAG blocked the Con A-induced mitogenesis, exhibiting lymphocyte G₀/G₁-phase cell-cycle arrest with significant reduction of cells in S and G₂/M phases. Meanwhile, pretreated by CAG, a significant decline in [Ca²⁺]_i was observed. Furthermore, CAG significantly inhibited the production of Th1 cytokines IFN-γ, TNF, IL-2, Th2 cytokines IL-4, IL-6, IL-10 and Th17 cytokine IL-17 A on Con A-activated lymphocytes.

Our results reinforce that CAG has important anti-inflammatory activity by inhibiting lymphocytes activation, proliferation and cytokines expression, and shows, that this effect may be related to reduction of overall intracellular Ca²⁺ overload.