Up- and down-modulation of liver cytochrome P450 activities and associated events in two murine malaria models

Background

The mechanisms by which malaria up and down-regulates CYP activities are not understood yet. It is also unclear whether CYP activities are modulated during non-lethal malaria infections. This study was undertaken to evaluate the time course of CYP alterations in lethal (Plasmodium berghei ANKA) and non-lethal (Plasmodium chabaudi chabaudi) murine malaria. Additionally, hypotheses on the association of CYP depression with enhanced nitric oxide (NO) production, and of CYP2a5 induction with endoplasmic reticulum dysfunction, enhanced haem metabolism and oxidative stress were examined as well.

Methods

Female DBA-2 and C57BL/6 mice were infected with P.berghei ANKA or P. chabaudi and killed at different post-infection days. Infection was monitored by parasitaemia rates and clinical signs. NO levels were measured in the serum. Activities of CYP1a (ethoxyresorufin-O-deethylase), 2b (benzyloxyresorufin-O-debenzylase), 2a5 (coumarin-7-hydroxylase) and uridine-diphosphoglucuronyl-transferase (UGT) were determined in liver microsomes. Glutathione-S-transferase (GST) activity and concentrations of gluthatione (GSH) and thiobarbituric acid-reactive substances (TBARS) were determined in the liver. Levels of glucose-regulated protein 78 (GRP78) were evaluated by immunoblotting, while mRNAs of haemoxygenase-1 (HO-1) and inducible nitric oxide synthase (iNOS) were determined by quantitative RT-PCR.

Results

Plasmodium berghei depressed CYP1a and 2b and induced 2a5 in DBA-2 mice. In P.berghei-infected C57BL/6 mice CYP activities remained unaltered. In both strains, GST and UGT were not affected by P.berghei. Plasmodium c. chabaudi depressed CYP1a and 2b and induced 2a5 activities on the day of peak parasitaemia or near this day. CYP2a5 induction was associated with over-expression of HO-1 and enhanced oxidative stress, but it was not associated with GRP78 induction, a marker of endoplasmic reticulum stress. Plasmodium chabaudi increased serum NO on days near the parasitaemia peak in both strains. Although not elevating serum NO, P.berghei enhanced iNOS mRNA expression in the liver.

Conclusion

Down-regulation of CYP1a and 2b and induction of 2a5 occurred in lethal and non-lethal infections when parasitaemia rates were high. A contribution of NO for depression of CYP2b cannot be ruled out. Results were consistent with the view that CYP2a5 and HO-1 are concurrently up-regulated and suggested that CYP2a5 induction may occur in the absence of enhanced endoplasmic reticulum stress.     

Biotransformation of tamoxifen in a human endometrial explant culture model

Although long-term tamoxifen therapy is associated with increased risk of endometrial cancer, little is known about the ability of endometrial tissue to biotransform tamoxifen to potentially reactive intermediates, capable of forming DNA adducts. The present study examined whether explant cultures of human endometrium provide a suitable in vitro model to investigate the tissue-specific biotransformation of tamoxifen. Fresh human endometrial tissue, microscopically uninvolved in disease, was cut into 1 x 2-mm uniform explants and incubated with media containing either 25 or 100 microM tamoxifen in a 24-well plate. Metabolites were analyzed by reversed-phase HPLC using postcolumn, online, photochemical activation and fluorescence detection. Three metabolites, namely, alpha-hydroxytamoxifen, 4-hydroxytamoxifen, and N-desmethyltamoxifen were identified in culture medium and tissue lysates. N-desmethyltamoxifen was found to be the major metabolite in both tissue and media extracts of tamoxifen-exposed explants. Incubations of tamoxifen with recombinant human cytochrome P-450s (CYPs) found that CYP2C9 and CYP2D6 produced all three of the above tamoxifen metabolites, while CYP1A1 and CYP3A4 catalyzed the formation of alpha-hydroxytamoxifen and N-desmethyltamoxifen, and CYP1A2 and CYP1B1 only formed the alpha-hydroxy metabolite. CYP2D6 exhibited the greatest activity for the formation of all three tamoxifen metabolites. Western immunoblots of microsomes from human endometrium detected the presence of CYPs 2C9, 3A, 1A1 and 1B1 in fresh endometrium, while CYPs 2D6 and 1A2 were not detected. Immunohistochemical (IHC) analysis also confirmed the presence of CYPs 2C9, 3A and 1B1 in fresh human endometrium and in viable tissue cultured for 24 h with or without tamoxifen. Together, the results support the use of explant cultures of human endometrium as a suitable in vitro model to investigate the biotransformation of tamoxifen in this target tissue. In addition, the results support the role of CYPs 2C9, 3A, 1A1 and 1B1 in the biotransformation of tamoxifen, including the formation of the DNA reactive alpha-hydroxytamoxifen metabolite, in human endometrium.     

Antioxidant inhibits tamoxifen-DNA adducts in endometrial explant culture

Fresh human endometrial explants were incubated for 24h at 37 degrees C with either tamoxifen (10-100 micro M) or the vehicle (0.1% ethanol). Three metabolites namely, alpha-hydroxytamoxifen, 4-hydroxytamoxifen, and N-desmethyltamoxifen were identified in the culture media. Tissue size was limited but DNA adducts formed by the alpha-hydroxytamoxifen pathway were detected using authentic alpha-(deoxyguanosyl-N(2)) tamoxifen standards. Relative DNA-adduct levels of 2.45, 1.12, and 0.44 per 10(6) nucleotides were detected following incubations with 100, 25, and 10 micro M tamoxifen, respectively. The concurrent exposure of the explants to 100 micro M tamoxifen with 1mM ascorbic acid reduced the level of alpha-hydroxytamoxifen substantially (68.9%). The formation of tamoxifen-DNA adducts detectable in the explants from the same specimens exposed to 100 micro M tamoxifen with 1mM ascorbic acid were also inhibited. These results support the role of oxidative biotransformation of tamoxifen in the subsequent formation of DNA adducts in this tissue.     

Antibodies to citrullinated proteins and differences in clinical progression of rheumatoid arthritis

Antibodies to citrullinated proteins (anti-cyclic-citrullinated peptide [anti-CCP] antibodies) are highly specific for rheumatoid arthritis (RA) and precede the onset of disease symptoms, indicating a pathogenetic role for these antibodies in RA. We recently showed that distinct genetic risk factors are associated with either anti-CCP-positive disease or anti-CCP-negative disease. These data are important as they indicate that distinct pathogenic mechanisms are underlying anti-CCP-positive disease or anti-CCP-negative disease. Likewise, these observations raise the question of whether anti-CCP-positive RA and anti-CCP-negative RA are clinically different disease entities. We therefore investigated whether RA patients with anti-CCP antibodies have a different clinical presentation and disease course compared with patients without these autoantibodies. In a cohort of 454 incident patients with RA, 228 patients were anti-CCP-positive and 226 patients were anti-CCP-negative. The early symptoms, tender and swollen joint count, and C-reactive protein level at inclusion, as well as the swollen joint count and radiological destruction during 4 years of follow-up, were compared for the two groups. There were no differences in morning stiffness, type, location and distribution of early symptoms, patients' rated disease activity and C-reactive protein at inclusion between RA patients with and without anti-CCP antibodies. The mean tender and swollen joint count for the different joints at inclusion was similar. At follow-up, patients with anti-CCP antibodies had more swollen joints and more severe radiological destruction. Nevertheless, the distribution of affected joints, for swelling, bone erosions and joint space narrowing, was similar. In conclusion, the phenotype of RA patients with or without anti-CCP antibodies is similar with respect to clinical presentation but differs with respect to disease course.     

A Modified In vitro Invasion Assay to Determine the Potential Role of Hormones,Cytokines and/or Growth Factors in Mediating Cancer Cell Invasion

Blood serum serves as a chemoattractant towards which cancer cells migrate and invade, facilitating their intravasation into microvessels. However, the actual molecules towards which the cells migrate remain elusive. This modified invasion assay has been developed to identify targets which drive cell migration and invasion. This technique compares the invasion index under three conditions to determine whether a specific hormone, growth factor, or cytokine plays a role in mediating the invasive potential of a cancer cell. These conditions include i) normal fetal bovine serum (FBS), ii) charcoal-stripped FBS (CS-FBS), which removes hormones, growth factors, and cytokines and iii) CS-FBS + molecule (denoted “X”). A significant change in cell invasion with CS-FBS as compared to FBS, indicates the involvement of hormones, cytokines or growth factors in mediating the change. Individual molecules can then be added back to CS-FBS to assay their ability to reverse or rescue the invasion phenotype. Furthermore, two or more factors can be combined to evaluate the additive or synergistic effects of multiple molecules in driving or inhibiting invasion. Overall, this method enables the investigator to determine whether hormones, cytokines, and/or growth factors play a role in cell invasion by serving as chemoattractants or inhibitors of invasion for a particular type of cancer cell or a specific mutant. By identifying specific chemoattractants and inhibitors, this modified invasion assay may help to elucidate signaling pathways that direct cancer cell invasion.     

Cost-effectiveness of abatacept,rituximab, and TNFi treatment after previous failure with TNFi treatment in rheumatoid arthritis: a pragmatic multi-centre randomised trial

IntroductionFor patients with rheumatoid arthritis (RA) whose treatment with a tumour necrosis factor inhibitor (TNFi) is failing, several biological treatment options are available. Often, another TNFi or a biological with another mode of action is prescribed. The objective of this study was to compare the effectiveness and cost-effectiveness of three biologic treatments with different modes of action in patients with RA whose TNFi therapy is failing.MethodsWe conducted a pragmatic, 1-year randomised trial in a multicentre setting. Patients with active RA despite previous TNFi treatment were randomised to receive abatacept, rituximab or a different TNFi. The primary outcome (Disease Activity Score in 28 joints) and the secondary outcomes (Health Assessment Questionnaire Disability Index and 36-item Short Form Health Survey scores) were analysed using linear mixed models. Cost-effectiveness was analysed on the basis of incremental net monetary benefit, which was based on quality-adjusted life-years (calculated using EQ-5D scores), and all medication expenditures consumed in 1 year. All analyses were also corrected for possible confounders.ResultsOf 144 randomised patients, 5 were excluded and 139 started taking abatacept (43 patients), rituximab (46 patients) or a different TNFi (50 patients). There were no significant differences between the three groups with respect to multiple measures of RA outcomes. However, our analysis revealed that rituximab therapy is significantly more cost-effective than both abatacept and TNFi over a willingness-to-pay range of 0 to 80,000 euros.ConclusionsAll three treatment options were similarly effective; however, when costs were factored into the treatment decision, rituximab was the best option available to patients whose first TNFi treatment failed. However, generalization of these costs to other countries should be undertaken carefully.

Trial registration

Netherlands Trial Register number NTR1605. Registered 24 December 2008.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0630-5) contains supplementary material, which is available to authorized users.     

Intramolecular interactions in aminoacyl cyclic-3',5'-nucleotides

Polymerization of amino-acid acyl cyclic-3',5'-nucleotides is postulated to be the origin of RNA and associated protein in prebiotic molecular evolution. The enthalpy change in the intramolecular interaction between the nucleotide base and the amino-acid side chain determines the stability of the particular complex, resulting in a preferred association (or coding) of a base for a particular amino acid. The compounds studied were glycine acyl cyclic-3',5'-guanylate where the strong hydrogen bond between protonated glycine and guanine N7 gives an enthalpy change of -0.05 h. Similarly, hydrogen bonds in l-lysine acyl cyclic-3',5'-adenylate give an enthalpy change of -0.06 h. Hydrophobic interactions in l-phenylalanine acyl cyclic-3',5'-uridylate give an enthalpy change of -0.02 h and the corresponding value for l-proline acyl cyclic-3',5'-cytidylate is -0.01 h. These interactions were expected to be modified as the genetic code became a duplet and finally a triplet code. The interactions have been shown to be feasible from the overall enthalpy changes in the ZKE approximation at the MP2/6-31G* level.