Effect of DSS-Induced Ulcerative Colitis and Butyrate on the Cytochrome P450 2A5: Contribution of the Microbiome

Several studies have indicated the beneficial anti-inflammatory effect of butyrate in inflammatory bowel disease (IBD) therapy implying attempts to increase butyrate production in the gut through orally administered dietary supplementation. Through the gut–liver axis, however, butyrate may reach directly the liver and influence the drug-metabolizing ability of hepatic enzymes, and, indirectly, also the outcome of applied pharmacotherapy. The focus of our study was on the liver microsomal cytochrome P450 (CYP) 2A5, which is a mouse orthologue of human CYP2A6 responsible for metabolism of metronidazole, an antibiotic used to treat IBD. Our findings revealed that specific pathogen-free (SPF) and germ-free (GF) mice with dextran sulfate sodium (DSS)-induced colitis varied markedly in enzyme activity of CYP2A and responded differently to butyrate pre-treatment. A significant decrease (to 50%) of the CYP2A activity was observed in SPF mice with colitis; however, an administration of butyrate prior to DSS reversed this inhibition effect. This phenomenon was not observed in GF mice. The results highlight an important role of gut microbiota in the regulation of CYP2A under inflammatory conditions. Due to the role of CYP2A in metronidazole metabolism, this phenomenon may have an impact on the IBD therapy. Butyrate administration, hence, brings promising therapeutic potential for improving symptoms of gut inflammation; however, possible interactions with drug metabolism need to be further studied

Administration of a Probiotic Can Change Drug Pharmacokinetics: Effect of <i>E. coli</i> Nissle 1917 on Amidarone Absorption in Rats

<div><p>The growing interest in the composition and effects of microbiota raised the question how drug pharmacokinetics could be influenced by concomitant application of probiotics. The aim of this study was to find whether probiotic <i>E. coli</i> strain Nissle 1917 (EcN) influences the pharmacokinetics of concomitantly taken antiarrhythmic drug amiodarone (AMI). Live bacterial suspension of probiotic EcN (or non-probiotic <i>E. coli</i> strain ATCC 25922) was applied orally to male Wistar rats for seven days, while a control group of rats was treated with a saline solution. On the eighth day, the amiodarone hydrochloride was administered as one single oral dose (50 mg/kg) to all rats (N = 60). After 0, 1, 2, 3, 4, 5.5, 7, 9, 14, 22, and 30 hours, blood samples were taken from the rat abdominal aorta. The plasma level of AMI and its metabolite N-desethylamiodarone (DEA) was determined using the HPLC with UV detection. Administration of EcN led to a 43% increase of AMI AUC_0-30 in comparison with control samples. However, this effect was not observed if EcN was replaced by a reference non-probiotic <i>E. coli</i> strain. Thus, EcN administration was most probably responsible for better drug absorption from the gastrointestinal tract. Plasma levels of DEA were also increased in plasma samples from animals treated with EcN. This change was again not found in the experiment with the reference non-probiotic strain. Higher DEA levels in samples from EcN-treated rats may be explained either by better absorption of AMI and/or by an increased activity of CYP2C forms, known to participate in metabolism of this drug, after EcN administration. In this paper, it is documented that concomitantly taken probiotic EcN may modulate pharmacokinetics of a drug; in this case, it led to an increased bioavailability of AMI.</p></div

Influence of a non-probiotic bacteria on the pharmacokinetics of amiodarone (A) and N-desethylamiodarone (B).

<p>Legend Fig. 3A: Pharmacokinetics of amiodarone with or without (control group) non-probiotic <i>E. coli</i> ATCC 25922 pre-treatment. Each point is presented as means ± S.D.; N = 3. Legend Fig. 3B: Pharmacokinetics of N-desethylamiodarone (metabolite of amiodarone) with or without (control group) non-probiotic <i>E. coli</i> ATCC 25922 pre-treatment. Each point is presented as means ± S.D.; N = 3.</p

Chromatographic profile of three compounds in biological sample: trifluoperazine (an internal), amiodarone, N-desethylamiodarone.

<p>Legend <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0087150#pone-0087150-g001" target="_blank">Fig. 1</a>: i.s.: an internal standard trifluoperazine (8.32 min); amiodarone (9.31 min); N-desethylamiodarone (10.11 min). The HPLC chromatogram was obtained from the rat blood plasma sample taken 3 hours after amiodarone application.</p

Pressure effects reveal that changes in the redox states of the heme iron complexes in the sensor domains of two heme-based oxygen sensor proteins, EcDOS and YddV, have profound effects on their flexibility

The catalytic activity of a heme-based oxygen sensor phosphodiesterase from Escherichia coli (EcDOS) towards cyclic diGMP is regulated by the redox state of the heme iron complex in the enzyme's sensing domain and the association of external ligands with the iron center. Specifically, the Fe (II) complex is more active towards cyclic diGMP than the Fe(III) complex, and its activity is further enhanced by O-2 or CO binding. In order to determine how the redox state and coordination of the heme iron atom regulate the catalytic activity of EcDOS, we investigated the flexibility of its isolated N-terminal heme-binding domain (EcDOS-heme) by monitoring its spectral properties at various hydrostatic pressures. The most active form of the heme-containing domain, i.e. the Fe(II)-CO complex, was found to be the least flexible. Conversely, the oxidized Fe(III) forms of EcDOS-heme and its mutants had relatively high flexibilities, which appeared to be linked to the low catalytic activity of the corresponding intact enzymes. These findings corroborate the suggestion, made on the basis of crystallographic data, that there is an inverse relationship between the flexibility of the heme-containing domain of EcDOS and its catalytic activity. The Fe(II)-CO form of the heme domain of a second heme-based oxygen sensor, diguanylate cyclase (YddV), was also found to be quite rigid. Interestingly, the incorporation of a water molecule into the heme complex of YddV caused by mutation of the Leu65 residue reduced the flexibility of this heme domain. Conversely, mutation of the Tyr43 residue increased its flexibility