title: Tryptanthrin inhibits Th2 development, and IgE-mediated degranulation and IL-4 production by rat basophilic leukemia RBL-2H3 cells.
abstract: BACKGROUND
  Tryptanthrin is a compound isolated from Polygonum tinctorium, which is a known folk medicine with various biological activities.
  
  
  OBJECTIVE
  Allergic diseases are initiated by the development of allergen-specific T helper type 2 (Th2) cells and amplified by the degranulation of and cytokine release from basophils and mast cells during an effector phase. We found that Tryptanthrin could down-regulate IL-4 production by Th2 cells, while IFN-γ production by Th1 cells was not affected. Since IL-4 produced by basophils and effector Th2 cells has been shown to play important roles in the development and amplification of Th2-dominated allergic responses, we examined the effects of Tryptanthrin on the initiation and effector phase responses of Type I allergy in vitro.
  
  
  METHODS
  To determine the mechanisms of Tryptanthrin-induced down-regulation of IL-4 production, the expression of Th2-specific transcription factors, c-Maf and GATA-3, was analyzed by RT-PCR. The effects of Tryptanthrin on Th cell differentiation were evaluated using CD4(+) T cells purified from spleen cells of Sugi basic protein (SBP)-immunized BALB/c mice. In primary cultures, cells were stimulated with SBP and antigen-presenting cells under neutral or Th2-skewing conditions in the presence or absence of Tryptanthrin. Cytokines produced by differentiated Th cells in secondary cultures were analyzed by ELISA. The effects of Tryptanthrin on IgE-mediated degranulation and IL-4 production were determined using rat basophilic leukemia (RBL-2H3) cells. Phosphorylation of ERK1/2 and Akt in Tryptanthrin-treated RBL-2H3 cells was analyzed to determine the mechanism of Tryptanthrin actions.
  
  
  RESULTS
  Tryptanthrin suppressed c-Maf mRNA expression in Th2 clone cells, and even under Th2-skewing conditions, Tryptanthrin inhibited differentiation toward the Th2 phenotype, which is an essential event for the initiation phase of allergic diseases. Tryptanthrin also inhibited the IgE-mediated degranulation of and IL-4 production by RBL-2H3 cells, probably due to inhibiting IgE-mediated signaling pathways, including the phosphorylation of ERK1/2 and Akt.
  
  
  CONCLUSIONS
  These findings suggest that Tryptanthrin effectively inhibits the effector and exacerbation responses, as well as the initiator responses, of Type I allergy. Thus, Tryptanthrin may have beneficial effects for immediate-type allergic responses.
authors.affiliation: Drugs, Cosmetics and Chemicals Development Center, Hayashibara Biochemical Laboratories, Inc., Japan.
authors.forename: Kanso
authors.initials: K
authors.lastname: Iwaki
authors.forename: Emiko
authors.initials: E
authors.lastname: Ohashi
authors.forename: Norie
authors.initials: N
authors.lastname: Arai
authors.forename: Keizo
authors.initials: K
authors.lastname: Kohno
authors.forename: Shimpei
authors.initials: S
authors.lastname: Ushio
authors.forename: Makoto
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D018926:Anti-Allergic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D052179:Antigens, Plant; D001491:Basophils / Q000187:drug effects* / Q000502:physiology; D015550:Cell Degranulation / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D006967:Hypersensitivity / Q000188:drug therapy* / Q000276:immunology; D007073:Immunoglobulin E / Q000378:metabolism; D015847:Interleukin-4 / Q000096:biosynthesis; D015471:Leukemia, Basophilic, Acute; D008407:Mast Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D010766:Phosphorylation; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D028502:Polygonum / Q000737:chemistry*; D051257:Proto-Oncogene Proteins c-maf / Q000235:genetics / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology* / Q000627:therapeutic use; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D018418:Th2 Cells / Q000187:drug effects* / Q000502:physiology
chemical_list: D018926:Anti-Allergic Agents; D052179:Antigens, Plant; D010936:Plant Extracts; D051257:Proto-Oncogene Proteins c-maf; D011799:Quinazolines; D012333:RNA, Messenger; C046243:tryptanthrine; D015847:Interleukin-4; D007073:Immunoglobulin E