Licorice (Glycyrrhiza glabra): A Phytotherapeutic Agent for the Induction of Regulatory T Cells (Tregs)

Regulatory T cells (Tregs) play a fundamental role in maintaining immune homeostasis within the body. The therapeutic expansion and application of Treg cells have been widely utilized in the treatment of autoimmune diseases and various inflammatory disorders.

Licorice has been a commonly used medicinal herb for over 1,000 years. While extensive evidence supports its properties as an immunomodulator, the specific mechanisms governing the induction and functional activation of Treg cells by licorice were previously not well understood. Consequently, this research focused on investigating the processes through which licorice stimulates Treg cell induction and function.

The study revealed that licorice exerts its inductive and functional effects on Treg cells through two primary active compounds: isoliquiritigenin and naringenin. The research found that:

• Naringenin stimulates Treg cells by acting as an AhR (aryl hydrocarbon receptor) agonist.

• Isoliquiritigenin stimulates Treg cells through a mechanism distinct from naringenin. Specifically, it was found to reduce mTOR signaling activity. The mTOR pathway is a critical regulatory mechanism controlling the differentiation and growth of both Th cells and Treg cells.

In Vivo Studies on Colitis: Colitis, a condition within the spectrum of Inflammatory Bowel Disease (IBD), results from inflammatory disorders combined with mucosal immune regulatory defects. In this study, animal models with colitis were administered either isoliquiritigenin, naringenin, or water daily for two weeks. The results demonstrated that the groups treated with isoliquiritigenin or naringenin showed a significant increase in Treg cell populations. Furthermore, clinical symptoms of colitis including weight loss, rectal bleeding, and colon shortening showed statistically significant improvement.

The findings indicate that Isoliquiritigenin and Naringenin possess therapeutic efficacy for the treatment of Inflammatory Bowel Disease. Therefore, this study suggests that both compounds have the potential to be developed as pharmaceutical agents for treating colitis, autoimmune diseases, and other inflammatory conditions, including Inflammatory Bowel Disease (IBD), Rheumatoid Arthritis (RA), and Multiple Sclerosis (MS).

 

Reference:

WincellResearch A phytotherapeutic agent for the induction of regulatory t cells

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