Induction and inhibition of cytochrome P450-dependent monooxygenases of rats by fungicide bitertanol.

The effects of fungicide bitertanol on cytochrome P450-dependent monooxygenases were studied using rats treated intraperitoneally with the N-substituted triazole for 4 days. Treatment with 10, 25, and 100 mg/kg bitertanol produced 2-, 4-, and 14-fold increases of 7-ethoxyresorufin O-deethylation activity in liver microsomes, respectively. Immunoblot analysis of microsomal proteins revealed that 25 mg/kg bitertanol increased CYP1A1 protein in the liver, kidney, and lung by 10-, 13-, and 17-fold, respectively. Bitertanol produced smaller increases of CYP2B and CYP3A catalytic activity and protein than that of CYP1A1 in liver. RT-PCR analysis of total RNA indicated that bitertanol-induced CYP1A1, CYP2B, and CYP3A mRNA. Additions of 0.01-100 microM bitertanol to liver microsomes from rats treated with 25 mg/kg bitertanol or 3-methylcholanthrene inhibited microsomal 7-ethoxyresorufin O-deethylation activity (IC(50)=0.8 or 0.9 microM). Bitertanol at 100 mg/kg increased liver UDP-glucuronosyltransferase and glutathione S-transferase activities by 2-fold. Bitertanol at 25 mg/kg produced a minor increase in metabolic activation of benzo[a]pyrene by liver S-9 fraction in the Ames mutagenicity test while the increase was blocked by addition of 100 microM bitertanol. These findings show that bitertanol is an inducer of CYP1A1, CYP2B, and CYP3A in vivo and an inhibitor of CYP1A catalytic activity in vitro.

Induction of immunomodulatory monocytes by human mesenchymal stem cell-derived hepatocyte growth factor through ERK1/2.

Monocytes are a population of leukocytes that terminally differentiate into macrophages and DCs. Whereas these differentiated progeny have inflammatory and resident--which are more immunomodulatory--phenotypes, less has been reported on the plasticity of monocytes themselves. We found that MSCs, a population of somatic stem cells, can rapidly induce human and murine monocytes through secretion of HGF to acquire an immunomodulatory phenotype to suppress T cell effector function. MSCs are multilineage postnatal progenitor cells with strong immunomodulatory effects toward T lymphocytes, NK lymphocytes, and DCs, but less is known regarding their interactions with monocytes. We found that CD14(+) human monocytes express c-Met, the receptor for HGF, and both depletion of HGF-treated CD14(+) monocytes and knockdown of HGF secretion in MSCs abrogate the suppression of anti-CD3/28-activated T cell proliferation. HGF-treated monocytes remain undifferentiated and can alter activated T cell cytokine expression from a Th1 toward Th2 profile. Moreover, monocytes cocultured with MSCs or treated with HGF alone can produce high levels of IL-10, a potent immunomodulatory cytokine. Injection of HGF to WT mice also results in an increase in IL-10(+)-expressing monocytes from the spleen, a known reservoir for circulating monocytes. Mechanistically, HGFs modulate IL-10 production in monocytes through the ERK1/2 pathway. Our data demonstrate further the pleomorphic nature of MSC immunomodulation, as well as highlight the important role of immunomodulatory monocytes in altering T cell effector function.

Induction of CYP1A1, 2B, 2E1 and 3A in rat liver by organochlorine pesticide dicofol.

The present study has determined the ability of dicofol, an organochlorine pesticide, to induce cytochrome P450 using rats treated with 1, 10, and 25mg/kg dicofol intraperitoneally for 4 days. Treatments with 10 and 25mg/kg dicofol produced dose-related increases of cytochrome P450 and cytochrome b(5) contents and NADPH-cytochrome c reductase, 7-ethoxyresorufin O-deethylase, pentoxyresorufin O-dealkylase, aniline hydroxylase, and erythromycin N-demethylase activities in liver microsomes. The treatments also increased glutathione S-transferase and superoxide dismutase activities in liver cytosol. Dicofol at 1mg/kg produced a general trend towards increases of the aforementioned enzyme levels. The results of immunoblot analyses showed that 10 and 25mg/kg dicofol increased protein levels of CYP1A1, CYP2B, CYP2E1, and 3A in liver. RT-PCR data indicated that dicofol induced mRNA expression of liver CYP1A1, CYP2B, and CYP3A. Pretreatments of rats with 10 and 25mg/kg dicofol decreased phenobarbital-induced sleeping time by 34% and 39%, respectively. Dicofol pretreatment at 25mg/kg increased CCl4-induced serum alanine aminotransferase activity by 4.3-fold and aspartate aminotransferase activity by 4.1-fold. The present study demonstrates that dicofol has the ability to induce CYP1A1, CYP2B, CYP2E1, and CYP3A in the liver and increase phenobarbital metabolism and CCl4 toxicity in rats.