Glycyrrhiza Glabra Extract Modulates Type 1 T Helper (TH1) and Regulatory T Cell-Related Immune Responses in an Animal Model of Breast Cancer.

Background: It is well-known that TH1 and Treg cells exert anti- and pro-tumorigenic activity, respectively. Thus, TH1 cell suppression together with Treg cell hyperactivation contribute to tumor development. Glycyrrhiza glabra (G. glabra) has various immunomodulatory and anti-tumorigenic properties.

Objective: To explore the impacts of G. glabra extract on different parameters related to TH1 and Treg cells using a breast cancer (BC) model.

Methods: Four groups of Balb/C mice bearing 4T1 cell-induced BC were treated intraperitoneally with either saline or G. glabra extract at dosages of 50, 100 and 150 mg/kg (G. glabra-50, G. glabra-100, and G. glabra-150, respectively). After sacrificing animals on day 26, the frequency of splenic TH1 and Treg cells, the levels of serum IFN-γ, TGF-β, and IL-12, and intra-tumoral expressions of granzyme-B, T-bet, and FOXP3 were assessed.

Results: Compared to untreated tumor control (UTC) group, treatment with G. glabra-50, G. glabra-100, or G. glabra-150 increased the survival rate, percentage of TH1 cells, and T-bet expression. Conversely, they reduced the percentage of Treg cells, and serum TGF-β levels. In comparison to the UTC group, treatment with G. glabra-50 and G. glabra-150 increased the serum IL-12 levels. Treatment with G. glabra-100 and G. glabra-150 boosted granzyme-B expression. Treatment with G. glabra-150 elevated IFN-γ levels, while treatment with G. glabra-50 decreased the FOXP3 expression. IL-12 levels were higher in mice treated with G. glabra-150 compared to those treated with G. glabra-100.

Conclusion: Treatment of mice with BC using G. glabra extract improved survival rate, reduced tumor growth, and modulated T cell-mediated immune responses.