Study of urinary 6β-hydroxycortisol/cortisol ratio in spot urine sample as a biomarker of 3A4 enzyme activity in healthy and epileptic subjects of Egyptian population

Cytochrome P450 3A4 activity and genetic variants as predictors of liver failure in patients with obstructive jaundice

Liver failure in patients with obstructive jaundice is a significant contributor to mortality within this patient cohort. The exact mechanism and triggers of this occurrence are yet to be fully understood. With this in mind, our study aimed to assess the correlation between the urinary 6 β-OHC/C ratio and various biochemical parameters of liver function. Furthermore, we conducted genotyping of CYP3A4*22 (rs35599367), CYP3A5*3 (rs776746) polymorphic markers to investigate the potential effects of their variants on the probability of liver failure in obstructive jaundice. Our study included 75 patients diagnosed with severe obstructive jaundice. All test subjects underwent functional liver tests, and control blood tests were administered on the seventh day following biliary decompression. Patients were categorized into two groups: group 1 - patients without liver failure (n = 60) and group 2 - patients with liver failure (n = 15). Laboratory indexes such as 6 β -OHC concentration and 6 β- OHC/cortisol ratio can serve as significant predictors of liver failure in patients with moderate and severe degree obstructive jaundice after biliary decompression. Based on the study of "wild" and polymorphic variants of CYP3A4*22 (CC and CT) and polymorphism of CYP3A5*3A6986G (GG, GA, AA), it was discovered that liver failure in the CYP3A4*22 variant may be associated with the CC genotype, and in the CYP3A5*3 variant - with the GA genotype. Hence, the determination of 6β- OHC concentration and 6β- OHC/C ratio, as well as the analysis of polymorphic and "wild" variants of CYP3A4*22 (CC and CT) and CYP3A5*3 polymorphism A6986G (GG, GA, AA), may play a crucial role in predicting liver failure in patients with obstructive jaundice.

The utility of endogenous glycochenodeoxycholate-3-sulfate and 4β-hydroxycholesterol to evaluate the hepatic disposition of atorvastatin in rats

The liver is an important organ for drugs disposition, and thus how to accurately evaluate hepatic clearance is essential for proper drug dosing. However, there are many limitations in drug dosage adjustment based on liver function and pharmacogenomic testing. In this study, we evaluated the ability of endogenous glycochenodeoxycholate-3-sulfate (GCDCA-S) and 4β-hydroxycholesterol (4β-HC) plasma levels to evaluate organic anion-transporting polypeptide (Oatps)-mediated hepatic uptake and Cyp3a-meidated metabolism of atorvastatin (ATV) in rats. The concentration of ATV and its metabolites, 2-OH ATV and 4-OH ATV, was markedly increased after a single injection of rifampicin (RIF), an inhibitor of Oatps. Concurrently, plasma GCDCA-S levels were also elevated. After a single injection of the Cyp3a inhibitor ketoconazole (KTZ), plasma ATV concentrations were significantly increased and 2-OH ATV concentrations were decreased, consistent with the metabolism of ATV by Cyp3a. However, plasma 4β-HC was not affected by KTZ treatment despite it being a Cyp3a metabolite of cholesterol. After repeated oral administration of RIF, plasma concentrations of ATV, 2-OH ATV and 4-OH ATV were markedly increased and the hepatic uptake ratio of ATV and GCDCA-S was decreased. KTZ did not affect plasma concentrations of ATV, 2-OH ATV and 4-OH ATV, but significantly decreased the metabolic ratio of total and 4-OH ATV. However, the plasma level and hepatic metabolism of 4β-HC were not changed by KTZ. The inhibition of hepatic uptake of GCDCA-S by RIF was fully reversed after a 7-d washout of RIF. Plasma concentration and hepatic uptake ratio of GCDCA-S were correlated with the plasma level and hepatic uptake of ATV in rats with ANIT-induced liver injury, respectively. These results demonstrate that plasma GCDCA-S is a sensitive probe for the assessment of Oatps-mediated hepatic uptake of ATV. However, Cyp3a-mediated metabolism of ATV was not predicted by plasma 4β-HC levels in rats.

OpenCYP: An open source database exploring human variability in activities and frequencies of polymophisms for major cytochrome P-450 isoforms across world populations

The open source database "OpenCYP database" has been developed based on the results of extensive literature searches from the peer-reviewed literature. OpenCYP provides data on human variability on baseline of activities and polymophism frequencies for selected cytochrome P-450 isoforms (CYP1A2, CYP2A6, CYP2D6, CYP3A4/3A5 and CYP3A7) in healthy adult populations from world populations. CYP enzymatic activities were generally expressed as the metabolic ratio (MR) between an unchanged probe drug and its metabolite(s) in urine or plasma measured in healthy adults. Data on other age groups were very limited and fragmented, constituting an important data gap. Quantitative comparisons were often hampered by the different experimental conditions used. However, variability was quite limited for CYP1A2, using caffeine as a probe substrate, with a symmetrical distribution of metabolic activity values. For CYP3A4, human variability was dependent on the probe substrate itself with low variability when data considering the dextromethorphan/demethilathed metabolite MR were used and large variability when the urinary 6β-hydroxycortisol/cortisol ratio was used. The largest variability in CYP activity was shown for CYP2D6 activity, after oral dosing of dextromethorphan, for which genetic polymorphisms are well characterised and constitute a significant source of variability. It is foreseen that the OpenCYP database can contribute to promising tools to support the further development of QIVIVE and PBK models for human risk assessment of chemicals particularly when combined with information on isoform-specific content in cells using proteomic approaches.

Luminescent Strategies for Label-Free G-Quadruplex-Based Enzyme Activity Sensing

By catalyzing highly specific and tightly controlled chemical reactions, enzymes are essential to maintaining normal cellular physiology. However, aberrant enzymatic activity can be linked to the pathogenesis of various diseases. Therefore, the unusual activity of particular enzymes can represent testable biomarkers for the diagnosis or screening of certain diseases. In recent years, G-quadruplex-based platforms have attracted wide attention for the monitoring of enzymatic activities. In this Personal Account, we discuss our group's works on the development of G-quadruplex-based sensing system for enzyme activities by using mainly iridium(III) complexes as luminescent label-free probes. These studies showcase the versatility of the G-quadruplex for developing assays for a variety of different enzymes.

Effects of carbamazepine on cortisol levels and behavioral responses to stress in the fish Jenynsia multidentata

Carbamazepine (CBZ) is an anticonvulsant drug, prescribed worldwide for the treatment of epilepsy, bipolar disorder and trigeminal neuralgia, which has been frequently detected in aquatic environments. The objective of this study was to analyze if CBZ modifies scototaxis and shoaling behaviors and/or whole-body cortisol levels of the one-sided livebearing fish Jenynsia multidentata under stress condition. Female adults of J. multidentata were exposed to 0, 10, 50 and 200μgCBZ/L during 14days. After CBZ exposure, fish were subjected to restraint stress during 15min. Control animals were not exposed to CBZ or stress. In the light/dark preference test (scototaxis), the individuals under acute restraint stress (without CBZ) exhibited a significant increase in the mean speed and in the time spent both in the light compartment and in the bottom of the tank with respect to controls. They also showed a tendency to stay longer frozen in the light compartment. Fish exposed to 10 and 50μgCBZ/L showed a significant reduction in mean speed compared to stressed fish without CBZ. A reduction in the time spent in the bottom of the tank was also observed in fish exposed to 10μgCBZ/L. Fish exposed to 200μgCBZ/L showed a decreasing tendency in all behavioral endpoints (time spent in the light compartment, mean speed, time spent at the bottom and freezing) in comparison to stressed fish not exposed to CBZ. Considering whole-body cortisol results, fish under acute restraint stress (without CBZ) significantly increased their hormone levels with respect to the control group, while fish exposed to CBZ and acute restraint stress, significantly decreased their whole-body cortisol levels. There were no significant changes in shoaling behavior due to either stress or CBZ exposure and no significant differences in whole-body cortisol levels between experimental groups. Considering that the light/dark and shoaling tests measure different stress response behaviors regulated by different neuroendocrine systems, these results could indicate that CBZ has a differential effect on fish behavioral stress response and cortisol levels, depending on the behavioral test used and stressor applied.

Personalized medicine: myth or reality? The position of Russian clinical pharmacologists

A personalized medicine, a recent trend of clinical pharmacology, makes possible the individual approach to the choice of the drugs and their dosage. According to the results of a study of the activity of different biomarkers, particularly the isoenzymes of the cytochrome P-450, they provide the efficiency and safety of the pharmacotherapy. The activity of the isoenzymes of the cytochrome P-450 determines an individual pharmacological response and depends on many factors, including genetic ones. The biomarkers of the activity of the isoenzymes of the cytochrome P-450 should be tested in the clinical practice settings using the simple and cheap methods, one of the most available is an immunofluorescent assay. The skilled staff and the centers of personalized medicine are necessary for this approach.

Illicit treatments in cattle and urinary 6beta-hydroxycortisol/cortisol ratio

Dexamethasone (DXM) is often illegally used as a growth promoter. To identify indirect biomarkers of illicit treatments, the urinary ratio between 6beta-hydroxycortisol (6beta-OHF) and cortisol (F) was measured in urines obtained from bulls experimentally treated per os and intramuscularly (i.m.) with different DXM dosages. Dexamethasone, given per os at low doses elicited an early and lasting significant reduction of 6beta-OHF/F. No significant variations were seen in urines from bulls given DXM intramuscularly. These results suggest 6beta-OHF/F as a rapid, non-invasive, screening test for oral, low-dose, long-term corticosteroid treatment in cattle. Further studies are required to go deep inside the biochemical and molecular events underlying such an effect.

Study of the Urinary Ratio of 6 β-Hydroxycortisol/Cortisol as a Biomarker of CYP3A4 Activity in Egyptian Patients with Chronic Liver Diseases

Summary

The urinary ratio of 6 β-hydroxycortisol/cortisol (6 β-OHC/C) as a biomarker of CYP3A4 metabolizing activity has been studied in Egyptian patients with chronic liver cirrhosis associated with previous hepatic Schistosomiasis infection to determine any possible alteration in enzyme activity. The ratio of 6-β OHC/C was determined in morning urine samples collected from 8:00 a.m. to 12:00 p.m. in healthy adults (n = 36) and patients with liver cirrhosis (n = 57). The median age for control was 27 years (range: 18–50 years) and 50 years (range: 27–75 years) for patients. 6 β-OHC was detected in urine by ELIZA kits (Stabiligen, France). Patients with liver cirrhosis were categorized according to Child Pugh Classification into Child B (n = 28) and Child C (n = 29) classes. Cholestasis was observed in 9/28 of Child B class and 8/29 of Child C class of patients. The control subjects showed gender-related difference in the urinary ratio of 6 β-OHC/C. A significant reduction ( P <0.001) in 6 β-OHC/C ratio was observed only in Child C patients in comparison with control subjects. Regression analysis showed a significant correlation ( P < 0.05) between 6 β-OHC/C ratio and serum albumin. The influence of cholestasis on the urinary ratio of 6-β OHC/C was observed on cirrhotic patients of Child B class. In conclusion, patients with chronic liver cirrhosis might have a reduction of metabolizing activity of CYP3A4 enzymes which could be identified by measuring the urinary ratio of 6 β-OHC/C. This reduction is more apparent in severe liver injury (Child C class). Therefore, it is important to understand the metabolic fate of drugs metabolized by 3A4 enzymes in patients with liver cirrhosis to avoid drug accumulation that might lead to development of drug toxicity.