Baicalein selectively induces apoptosis in activated lymphocytes and ameliorates concanavalin a-induced hepatitis in mice

PLoS One. 2013 Jul 22;8(7):e69592. doi: 10.1371/journal.pone.0069592. Print 2013.

Abstract

Background: Insufficient apoptosis in activated lymphocytes contributes to the development of autoimmune hepatitis (AIH). Baicalein (BE), a flavonoid originally isolated from the root of Scutellaria baicalensis Georgi, possesses anti-inflammatory properties. However, whether BE can selectively induce apoptosis in activated lymphocytes and exert therapeutic effect on AIH has not been studied.

Methodology/principal findings: The pro-apoptotic properties of BE were evaluated in vitro on different types of immune cells, and in vivo effects of BE were examined in a murine model of Concanavalin A (Con A)-induced hepatitis. In vitro treatment with BE resulted in a higher increase in the level of apoptosis in Con A-stimulated murine splenocytes, Con A-stimulated CD3(+) splenocytes, lipopolysaccharide (LPS)-stimulated CD19(+) splenocytes, and phorbol 12-myristate 13-acetate/ionomycin-stimulated Jurkat T cells, compared with that in unstimulated naïve ones. Murine bone marrow-derived dentritic cells, peritoneal macrophages, and RAW264.7 cells, either stimulated with LPS or unstimulated, were all insensitive to the BE-induced apoptosis. BE treatment also led to a loss of mitochondrial membrane potential, an increase of cytochrome c release from mitochondria to the cytosol, a decrease in the ratio of Bcl-2/Bax, and activation of caspase-9,-3 in Con A-stimulated CD3(+) splenocytes and LPS-stimulated CD19(+) splenocytes, while showing no impact on Fas/FasL expressions and caspase-8 activation. In vivo administration of BE alleviated Con A-induced liver injury, suppressed serum level of TNF-α and IFN-γ, and reduced liver infiltration of mononuclear cells (MNCs). Furthermore, BE treatment increased the incidences of apoptosis in liver-infiltrating MNCs and splenocytes, as well as in CD3(+) and CD19(+) splenocytes. When liver MNCs and splenocytes from BE-treated mice were cultured in vitro for 24 h, they exhibited marked increase in apoptosis compared to vehicle-treated control.

Conclusions/significance: The present study demonstrates the ability of BE to promote apoptosis in activated lymphocytes through mitochondrial pathway and its potential use in the treatment of AIH.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Concanavalin A / pharmacology*
  • Female
  • Flavanones / pharmacology*
  • Hepatitis, Autoimmune / etiology
  • Hepatitis, Autoimmune / immunology*
  • Lymphocyte Activation / drug effects*
  • Lymphocytes / cytology*
  • Lymphocytes / drug effects
  • Lymphocytes / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Mitochondria / drug effects
  • Mitogens / pharmacology
  • Spleen / immunology

Substances

  • Flavanones
  • Mitogens
  • Concanavalin A
  • baicalein

Grants and funding

The work was supported by program NCET Foundation, NSFC (30725045), and NSFC (81072653), partially supported by Global Research Network for Medicinal Plants (GRNMP) and King Saud University, Shanghai Leading Academic Discipline Project(B906), FP7- PEOPLE-IRSES-2008 (TCMCANCER Project 230232), Key laboratory of drug research for special environments, PLA, Shanghai Engineering Research Center for the Preparation of Bioactive Natural Products(10DZ2251300) and the Scientific Foundation of Shanghai China (09DZ1975700, 09DZ1971500, 10DZ1971700), National Major Project of China (2011ZX09307-002-03). National Key Technology R&D Program of China (2012BAI29B06). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.