Astragalus membranaceus promotes the function of regulatory t cells from asthma patients in remission periods in vitro

Abstract

Emerging data demonstrates that the chronic airway inflammation in asthma remission periods is partly attributed to the decreased function of T regulatory (Treg) cells. Astragalus membranaceus (AM), a Traditional Chinese Medicine for treatment of asthma, is confirmed to have a variety of immunomodulatory properties. This study was to explore whether AM possesses potential regulatory effect on the function of Treg cells from the patients with asthma at the remission stage. We enrolled 10 asthma patients in the remission stage and 10 healthy controls. The medicinal serum of AM was prepared from rats. CD4+CD25+ Treg cells and CD4+CD25- conventional T (Tconv) cells in peripheral blood mononuclear cells were sorted by fluorescence activated cell sorting. Treg cells were treated with three doses of AM medicinal serum. The effect of AM on Treg cells proliferation was evaluated by CCK-8 assay. Production of TGF-β, IL-10 and IL-35 cytokines was evaluated in the culture supernatant of Treg cells in the presence of medicinal serum. Suppressor activity of Tregs was examined by changes in the proliferation of CFSE-labeled Tconv cells. AM could significantly increase the proliferation of Treg cells and promote the production of TGF-β, IL-10 and IL-35 cytokines. In functional assay, the immune suppression of Tregs from asthma patients was remarkably decreased compared to that from healthy controls. However, AM increased the immune suppression of Tregs on Tconv cells. In conclusion, this study revealed AM could enhance effects on Treg proliferation and function, which may have potential benefits for asthma treatment in remission periods.