Immunosuppressive activity on the murine immune responses of glycyrol from Glycyrrhiza uralensis via inhibition of calcineurin activity.
BACKGROUND
Calcineurin (CN), a unique protein phosphatase, plays an important role in immune regulation. Our laboratory has established an effective molecular drug-screening model based on CN activity.


OBJECTIVE
Our aim is to search for an effective immunosuppressant from Glycyrrhiza uralensis (Leguminosae).


METHODS
As guided by CN inhibitory test, an active compound was purified and identified as glycyrol. Immunosuppressive activity of glycyrol in vitro was assayed by T lymphocytes proliferation and mixed lymphocyte reaction (MLR). In addition, delayed-type hypersensitivity reaction (DTH) and skin allograft test in vivo were also carried out. Further, we have investigated the effect of glycyrol on phorbol 12-myristate 13-acetate (PMA)/ionomycin (Io)-stimulated IL-2 expression in Jurkat cells.


RESULTS
The enzymatic assay showed glycyrol (IC(50) = 84.6 μM) inhibited calcineurin activity in a dose-dependent manner. Glycyrol, at the non-cytotoxic concentration, significantly inhibited proliferation of murine spleen T lymphocytes induced by Concanavalin A (Con A) and mixed lymphocyte reaction (MLR) in vitro. In addition, mice treated with glycyrol had shown the dose-dependent decrease in delayed type hypersensitivity (DTH) and prolonged the graft survival by 59% compared to the control group (*p < 0.05). RT-PCR showed glycyrol suppressed IL-2 production in a concentration-dependent manner.


CONCLUSIONS
Our results show the immunosuppressive activity of glycyrol and this activity should be due to its inhibitory effect on CN activity, thereby suppressing IL-2 production and regulating T lymphocytes. Thus, glycyrol could be a candidate for development as a novel immunomodulatory drug.
Li
Jiayu
J
Department of Biochemistry and Molecular Biology, Beijing Normal University, Beijing Key Laboratory, Beijing, China.
Tu
Ying
Y
Tong
Li
L
Zhang
Wen
W
Zheng
Jianquan
J
Wei
Qun
Q
D000818:Animals; D065095:Calcineurin Inhibitors; D049109:Cell Proliferation / Q000187:drug effects; D003208:Concanavalin A / Q000276:immunology / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D051776:Early Growth Response Protein 3 / Q000276:immunology; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D029882:Glycyrrhiza uralensis / Q000737:chemistry*; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007166:Immunosuppressive Agents / Q000737:chemistry / Q000494:pharmacology*; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D050778:NFATC Transcription Factors / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
D065095:Calcineurin Inhibitors; C079945:EGR3 protein, human; D005419:Flavonoids; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D050778:NFATC Transcription Factors; D010936:Plant Extracts; C531349:glycyrol; D003208:Concanavalin A; D051776:Early Growth Response Protein 3