Promotion of regulatory T cell induction by immunomodulatory herbal medicine licorice and its two constituents

Abstract

Regulatory T cells (Treg) play a critical role to control immune responses and to prevent autoimmunity, thus selective increase of Treg cells in vivo has broad therapeutic implications for autoimmune and inflammatory diseases. Licorice is a well-known herbal medicine used worldwide for over thousands of years, and accumulating evidence has shown its immunomodulatory potential. However, it is not clear whether licorice could regulate the induction and function of Treg cells. Here we found licorice extract could promote Treg cell induction, and then we used a rational approach to isolate its functional fractions and constituents. The results showed that two constituents, isoliquiritigenin and naringenin, promoted Treg cell induction both in vitro and in vivo. The effective fractions and two constituents of licorice also enhanced immune suppression of Treg cells, and they further reduced severity of DSS-induced colitis in mice. This study suggested that promotion of regulatory T cell induction could be an underlying mechanism of the historically and widely used herbal medicine licorice, providing its two effective molecules against autoimmune and inflammatory diseases.

Isoliquiritigenin Attenuates Adipose Tissue Inflammation in vitro and Adipose Tissue Fibrosis through Inhibition of Innate Immune Responses in Mice

“…Its biological activities include anti-allergic 20 , anti-angiogenesis 21 , and anti-tumor growth 22 . A recent paper showed that ILG promotes regulatory T cell differentiation 23 . We reported previously that ILG suppressed LPS-TLR4/MD-2 complex signaling at the receptor level, resulting in inhibition of NF-κB and MAP kinases activation 24 .…”

Effects of dietary licorice extract on serum Biochemical index, tissues antioxidant capacity and immunity function of weaned piglets

“…LE had no effect on the spleen index and kidney index of weaned piglets (Table 1). Studies shown that licorice extract mainly affects liver and intestine of weaned piglets [20,31].…”

Herbal Immunomodulators - A Remedial Panacea for Designing and Developing Effective Drugs and Medicines: Current Scenario and Future Prospects

“…The Bcl-2/Bax family of genes, which are the regulatory factors for apoptosis, were found to be modulated by the components of GL root, and can be considered in elucidation of its reported cytoprotective action. Licorice contains two chemical components, isoliquiritigenin and naringenin, which have been reported to enhance regulatory T cells and therefore may be cause of the anti-inflammatory properties and efficacy against autoimmune diseases [96]. Dorhoi et al [97] induced enhanced cellular immunity in birds treated with the ethanol extracts of licorice.…”