title: Glycyrrhizic acid suppresses Cox-2-mediated anti-inflammatory responses during Leishmania donovani infection.
abstract: OBJECTIVE
  The aim of the present study was to characterize glycyrrhizic acid (GA) and assess its immunomodulatory potential in a model of experimental visceral leishmaniasis.
  
  
  METHODS
  The antileishmanial activity of GA was tested in an amastigote-macrophage model and its non-cytotoxic dose was measured by a cell viability assay. To understand the effector mechanism of GA-treated macrophages against leishmanial parasites, real-time PCR analysis of inducible nitric oxide synthase 2 (iNOS2) was carried out followed by measurement of nitric oxide generation by Griess reagent. The effect of GA on the production of cytokines, such as interleukin (IL)-12, tumour necrosis factor (TNF)-α, IL-10 and transforming growth factor (TGF)-β, was measured by ELISA (protein) and real-time PCR. The expression of iNOS2 and cyclooxygenase-2 (Cox-2) was studied by western blotting. The parasite burden of the liver and spleen following GA treatment was determined by the stamp-smear method, and T cell proliferation was assessed via [³H]thymidine uptake, measured by a liquid scintillation counter.
  
  
  RESULTS
  Results showed that GA treatment caused an enhanced expression of iNOS2 along with inhibition of Cox-2 in Leishmania donovani-infected macrophages. GA treatment in infected macrophages enhanced the expression of IL-12 and TNF-α, concomitant with a down-regulation of IL-10 and TGF-β. GA increased macrophage effector responses via inhibition of Cox-2-mediated prostaglandin E2 release in L. donovani-infected macrophages. GA also decreased hepatic and splenic parasite burden and increased T cell proliferation in Leishmania-infected BALB/c mice.
  
  
  CONCLUSIONS
  These results provide a mechanistic understanding of GA-mediated protection against leishmanial parasites within the host.
authors.affiliation: Division of Molecular Medicine,  Bose Institute, Kolkata,  India.
authors.forename: Surajit
authors.initials: S
authors.lastname: Bhattacharjee
authors.forename: Amrita
authors.initials: A
authors.lastname: Bhattacharjee
authors.forename: Saikat
authors.initials: S
authors.lastname: Majumder
authors.forename: Suchandra Bhattacharya
authors.initials: SB
authors.lastname: Majumdar
authors.forename: Subrata
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D016207:Cytokines / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D020869:Gene Expression Profiling; D019695:Glycyrrhizic Acid / Q000008:administration & dosage* / Q000494:pharmacology; D007155:Immunologic Factors / Q000008:administration & dosage* / Q000494:pharmacology; D007893:Leishmania donovani / Q000276:immunology / Q000472:pathogenicity*; D007898:Leishmaniasis, Visceral / Q000188:drug therapy*; D008099:Liver / Q000469:parasitology; D008264:Macrophages / Q000187:drug effects / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D060888:Real-Time Polymerase Chain Reaction; D013154:Spleen / Q000469:parasitology; D016896:Treatment Outcome
chemical_list: D000893:Anti-Inflammatory Agents; D016207:Cytokines; D007155:Immunologic Factors; D009569:Nitric Oxide; D019695:Glycyrrhizic Acid; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D015232:Dinoprostone