Modulation of cytochrome P450 2A5 activity by lipopolysaccharide: low-dose effects and non-monotonic dose-response relationship

• Published in: PloS one Vol. 10; no. 1; p. e0117842
• Main Authors: De-Oliveira, Ana C A X, Poça, Kátia S, Totino, Paulo R R, Paumgartten, Francisco J R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.01.2015; Public Library of Science (PLoS)
• Subjects: Animals; Aryl Hydrocarbon Hydroxylases - metabolism; Bacteria; Biological products; Biological response modifiers; Carcinogens; CYP1A protein; Cytochrome; Cytochrome P-450; Cytochrome P450; Cytochrome P450 Family 2; Cytokines; Cytokines - blood; Depression (Mood disorder); Dose-Response Relationship, Drug; Down-Regulation - drug effects; Enzymes; Female; Gene expression; Guanidines - pharmacology; Hepatitis; Infectious diseases; Inflammation Mediators - metabolism; Interferon; Interleukin 10; Interleukin 4; Interleukin 6; Isoforms; Laboratories; Lipopolysaccharides; Lipopolysaccharides - pharmacology; Liver; Liver - enzymology; Medical research; Mental depression; Metabolism; Mice; Mitogens; Nitric oxide; Nitric Oxide - blood; Nitric-oxide synthase; Opisthorchis viverrini; Oxidation; Oxidative stress; Proteins; Public health; Rodents; Sepsis; Serum levels; Stress response; Toxicology; Transcription activation; Tropical diseases; Tumor necrosis factor; Tumors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0117842

Mouse cytochrome P450 (CYP) 2A5 is induced by inflammatory conditions and infectious diseases that down-regulate the expression and activity of most other CYP isoforms. Enhanced oxidative stress and nuclear factor (erythroid 2-related factor) 2 (Nrf2) transcription factor activation have been hypothesised to mediate up-regulation of CYP2A5 expression in the murine liver. The unique and complex regulation of CYP2A5, however, is far from being thoroughly elucidated. Sepsis and high doses of bacterial lipopolysaccharide (LPS) elicit oxidative stress in the liver, but depression, not induction, of CYP2A5 has been observed in studies of mice treated with LPS. The foregoing facts prompted us to evaluate the response of CYP2A5 liver activity in female DBA-2 mice over a broad range of LPS doses (0, 0.025, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, and 20 mg/kg). Cytokine levels (interleukin [IL]-2, IL-4, IL-6, IL-10, IL-17A, interferon gamma, tumour necrosis factor alpha) and nitric oxide (NO) were measured in the blood serum. Activities of CYP1A (EROD) and CYP2B (BROD) in the liver were also determined for comparative purposes. LPS depressed CYP2A5 at low doses (0.025-2.0 mg/kg) but not at doses (>2 mg/kg) that increased pro-inflammatory cytokines and NO serum levels, and depressed CYP1A and CYP2B activities. Blockade of pro-inflammatory cytokines and the overproduction of NO induced by co-treatment with pentoxifylline and LPS and iNOS inhibition with aminoguanidine both extended down-regulation of CYP2A5 to the high dose range while not affecting LPS-induced depression of CYP1A and CYP2B. Overall, the results suggested that NO plays a role in the reversal of the low-dose LPS-induced depression of CYP2A5 observed when mice were challenged with higher doses of LPS.