Induction of human sulfotransferase 1A3 (SULT1A3) by glucocorticoids

Drug-Drug Interactions Involving Dexamethasone in Clinical Practice: Myth or Reality?

Concomitant administration of multiple drugs frequently causes severe pharmacokinetic or pharmacodynamic drug-drug interactions (DDIs) resulting in the possibility of enhanced toxicity and/or treatment failure. The activity of cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp), a drug efflux pump sharing localization and substrate affinities with CYP3A4, is a critical determinant of drug clearance, interindividual variability in drug disposition and clinical efficacy, and appears to be involved in the mechanism of numerous clinically relevant DDIs, including those involving dexamethasone. The recent increase in the use of high doses of dexamethasone during the COVID-19 pandemic have emphasized the need for better knowledge of the clinical significance of drug-drug interactions involving dexamethasone in the clinical setting. We therefore aimed to review the already published evidence for various DDIs involving dexamethasone in vitro in cell culture systems and in vivo in animal models and humans.

Impact of In Vitro Long-Term Low-Level DEHP Exposure on Gene Expression Profile in Human Granulosa Cells

Here, we applied a model of long-term exposure of human granulosa cells to low environmentally relevant levels of di(2-ethylhexyl) phthalate (DEHP). This approach provides more relevant data regarding the impact of DEHP on the function of human granulosa cells. The immortalized human granulosa cells HGrC1 were exposed to 50 nM and 250 nM DEHP for four weeks. The cells were collected every week to analyze the basal granulosa cells’ functions. A portion of the DEHP-exposed cells was stimulated with forskolin (FOR) for 48 h. Steroidogenesis was investigated using ELISA, whereas DNBQ sequencing and RT-qPCR were used to analyze gene expression. The results show that steroidogenesis was not affected by DEHP exposure. RNAsequencing shows that DEHP caused week- and concentration-specific changes in various genes and functions in HGrC1. Sulfotransferase family 1A member 3 (SULT1A3) and 4 (SULT1A4), which are involved in catecholamine metabolism, were the most prominent genes affected by DEHP under both the basal and FOR-stimulated conditions in all four weeks of exposure. This study showed, for the first time, that SULT1A3 and SULT1A4 are expressed in human granulosa cells, are regulated by FOR, and are affected by low-level DEHP exposure. These data provide new insight into the relationship between DEHP, SULT1A3, and SULT1A4 in human granulosa cells.

Model‐based meta‐analysis of salbutamol pharmacokinetics and practical implications for doping control

Salbutamol was included in the prohibited list of the World Anti‐Doping Agency (WADA) in 2004. Although systemic intake is banned, inhalation for asthma is permitted but with dosage restrictions. The WADA established a urinary concentration threshold to distinguish accordingly prohibited systemic self‐administration from therapeutic prescription by inhalation. This study aimed at evaluating the ability of the WADA threshold to differentiate salbutamol therapeutic use from violation of antidoping rules. Concentration‐time profile of salbutamol in plasma and its excretion in urine was characterized through a model‐based meta‐analysis of individual and aggregate data collected after administration of a large range of doses following different modes of administration and under a variety of conditions. The developed model adequately fitted salbutamol plasma and urine concentration‐time profiles of the 13 selected studies. Model‐based simulations confirmed that a wide range of salbutamol urine concentrations might be measured after drug intake. Although violation of the WADA Code can be strongly suspected in individuals showing very high salbutamol urine concentrations, uncertainty remains for values close to the WADA threshold as they can be compatible with both permitted therapeutic use and violation. Although not entirely discriminant, the current WADA rule is globally supported by our appraisal. It could be further improved by a slight and reasonable adjustment of inhaled daily dosages allowed for therapeutic use. Our model might help antidoping experts in the evaluation of suspected doping cases through confronting the athlete's urine measurements with their allegations about salbutamol treatment.

Longitudinal epigenetic predictors of amygdala:hippocampus volume ratio

BACKGROUND

The ratio between amygdala:hippocampal (AH) volume has been associated with multiple psychiatric problems, including anxiety and aggression. Yet, little is known about its biological underpinnings. Here, we used a methylome-wide approach to test (a) whether DNA methylation in early life (birth, age 7) prospectively associates with total AH volume ratio in early adulthood, and (b) whether significant DNA methylation markers are influenced by prenatal risk factors.

METHODS

Analyses were based on a subsample (n = 109 males) from the Avon Longitudinal Study of Parents and Children, which included measures of prenatal risk, DNA methylation (Infinium Illumina 450k), T1-weighted brain scans and psychopathology in early adulthood (age 18-21). Amygdala and hippocampus measures were derived using Freesurfer 5.3.0. Methylation markers related to AH volume ratio across time were identified using longitudinal multilevel modeling.

RESULTS

Amygdala:hippocampal volume ratio correlated positively with age 18 psychosis-like symptoms (p = .007). Methylation of a probe in the gene SP6 associated longitudinally with (a) higher AH volume ratio (FDR q-value = .01) and (b) higher stressful life events during pregnancy (p = .046). SP6 is expressed in the hippocampus and amygdala and has been implicated in cognitive decline in Alzheimer's disease. The association between SP6 DNA methylation, AH volume ratio and psychopathology was replicated in an independent dataset of 101 patients with schizophrenia and 111 healthy controls.

CONCLUSIONS

Our findings suggest that epigenetic alterations in genes implicated in neurodevelopment may contribute to a brain-based biomarker of psychopathology.

Dopamine-induced SULT1A3/4 promotes EMT and cancer stemness in hepatocellular carcinoma

Hepatocellular carcinoma has the second highest incidence rate among malignant cancers in China. Hepatocellular carcinoma development is complex because of the metabolism disequilibrium involving SULT1A3/4, a predominant sulfotransferase that metabolizes sulfonic xenobiotics and endogenous catecholamines. However, the correlation between SULT1A3/4 and hepatocellular carcinoma progression is unclear. By utilizing immunofluorescence and immunohistochemical analysis, we found that in nine hepatocellular carcinoma clinical specimens, SULT1A3/4 was abundantly expressed in tumor tissues compared to that in the adjacent tissues. Moreover, liver cancer cells (HepG2, MHCC97-L, and MHCC97-H) had higher basal expression of SULT1A3/4 than immortalized liver cells (L02 and Chang liver). Ultra-high-pressure liquid chromatography-tandem mass spectrometry assay results further revealed that the concentration of dopamine (a substrate of SULT1A3/4) was negatively correlated with SULT1A3/4 protein expression. As a transcriptional regulator of SULT1A3/4 in turn, dopamine was used to induce SULT1A3/4 in vitro. Interestingly, dopamine significantly induced SULT1A3/4 expression in liver cancer HepG2 cells, while decreased that in L02 cells. More importantly, the expression levels of epithelial-mesenchymal transition biomarkers (N-cadherin and vimentin) and cell stemness biomarkers (nanog, sox2, and oct3/4) considerably increased in HepG2 with dopamine-induced SULT1A3/4, whereas in L02, epithelial-mesenchymal transition and cancer stem cell-associated proteins were contrarily decreased. Furthermore, invasion and migration assays further revealed that dopamine-induced SULT1A3/4 dramatically stimulated the metastatic capacity of HepG2 cells. Our results implied that SULT1A3/4 exhibited bidirectional effect on tumor and normal hepatocytes and may thus provide a novel strategy for hepatocellular carcinoma clinical targeting. In addition, SULT1A3/4 re-expression could serve as a biomarker for hepatocellular carcinoma prognosis.

Quantification of Oxidized and Unsaturated Bile Alcohols in Sea Lamprey Tissues by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A sensitive and reliable method was developed and validated for the determination of unsaturated bile alcohols in sea lamprey tissues using liquid-liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The liver, kidney, and intestine samples were extracted with acetonitrile and defatted by n-hexane. Gradient UHPLC separation was performed using an Acquity BEH C18 column with a mobile phase of water and methanol containing 20 mM triethylamine. Multiple reaction monitoring modes of precursor-product ion transitions for each analyte was used. This method displayed good linearity, with correlation coefficients greater than 0.99, and was validated. Precision and accuracy (RSD %) were in the range of 0.31%-5.28%, while mean recoveries were between 84.3%-96.3%. With this technique, sea lamprey tissue samples were analyzed for unsaturated bile alcohol analytes. This method is practical and particularly suitable for widespread putative pheromone residue analysis.

ADHD impacted by sulfotransferase (SULT1A) inhibition from artificial food colors and plant-based foods

BACKGROUND

Five recent reviews have analyzed trials on the association between artificial food colors and ADHD; the 50 underlying studies and the reviews in aggregate were inconclusive. Recent work has shown human in vivo SULT1A inhibition leading to incremental catecholamines, and an inverted-U relationship between brain catecholamines and proper functioning of the prefrontal cortex where ADHD behavior can arise.

METHOD

This study re-examined the same underlying trials for evidence that SULT1A inhibitors were in the placebos and other inactive foods, that these "inactive" materials were symptomatic, and that ADHD symptoms exhibited an inverted-U response to SULT1A inhibition.

RESULTS

Nearly all the underlying diets, and many placebos and delivery vehicles, were found to contain SULT1A inhibitors. Eight publications provided evidence of ADHD symptoms caused by the "inactive" materials containing SULT1A inhibitors. Ten studies showed additional SULT1A inhibitors reducing the symptoms of some subjects.

CONCLUSION

SULT1A inhibitors in foods, including natural substances and artificial food colors, have a role in ADHD that can both worsen or improve symptoms. Mechanistically, SULT1A enzymes normally deactivate catecholamines, especially dopamine formed in the intestines; SULT1A inhibition can influence brain catecholamines through the intermediary of plasma tyrosine levels, which are influenced by dopamine inhibition of intestinal tyrosine hydroxylase. Biochemical measurements focused on SULT1A activity and plasma tyrosine concentrations are proposed for future work.

SULT 1A3 single-nucleotide polymorphism and the single dose pharmacokinetics of inhaled salbutamol enantiomers: are some athletes at risk of higher urine levels?

The study was designed to investigate the effect of a common genetic variation of the main salbutamol metabolizing enzyme SULT1A3 (single nucleotide polymorphism 105A>G, rs1975350) on the stereoselective pharmacokinetics of salbutamol. Subjects were administered a 400 µg dose of inhaled salbutamol via a large volume spacer and blood samples were collected over 4 h. Plasma levels of (R)- and (S)-salbutamol were determined by an enantioselective liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay. Twenty-five subjects with asthma were recruited and underwent SULT1A3 genotyping, from which four SNP homozygote (GG) subjects and nine wild-type (AA) subjects were selected to participated in the pharmacokinetic investigation. There were no differences in pharmacokinetic parameters (t1/2 , Cmax , AUC0-4h ) between SNP and wild-type genotypes for either the R- or S-enantiomer. Observed Cmax of R- and S-salbutamol [mean (SD)] was 0.64 (0.30) ng/mL and 1.32 (0.98) ng/mL, respectively. The mean t1/2 of R- and S-salbutamol was estimated at 2.94 (1.17) h and 7.86 (6.14) h respectively. The AUC0-4h of R- and S-salbutamol was 14.0 (6.8) and 38.3 (19.5) ng/mL.h respectively. In conclusion, the common SULT1A3 SNP 105A>G is not an important determinant of salbutamol enantiomer pharmacokinetics under normal clinical use and does not place some individuals at greater risk of accumulation in the body.

Hypothesis: holiday sudden cardiac death: food and alcohol inhibition of SULT1A enzymes as a precipitant

Sudden cardiac death is a significant health issue, causing millions of deaths worldwide annually. Studies have found that the likelihood of such death is higher in winter. Further studies identified that the highest likelihood occurs on Christmas Day and New Years Day, but not the interim period. Thanksgiving, Independence Day and the Islamic holiday Eid Al-Fitr also show significant increases in the rate of cardiac events or death. A number of mechanisms have been proposed, but none have satisfactorily explained the evidence. This article reviews the data supporting the existence of a holiday cardiac death phenomenon, the involvement of catecholamines and the normal modes of human catecholamine deactivation. Further evidence is reviewed that supports a hypothesized mechanism whereby critical SULT1A catecholamine deactivation enzymes can in some patients be inhibited by naturally-occurring phenols and polyphenols in foods and alcohols. If deactivation is inhibited by holiday consumption excesses, holiday stress or excitement could lead to a buildup of catecholamines that can cause fatal arrhythmias. Awareness of this mechanism could reduce deaths, both through doctor/patient education leading to a moderation in consumption and through the potential identification of patients with a predisposition to SULT1A inhibition. This hypothesis also raises parallels between sudden cardiac death in adults and Sudden Infant Death Syndrome (SIDS). The possible involvement of SULT1A inhibition in SIDS is discussed.

Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment

Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.

Nuclear receptor PXR, transcriptional circuits and metabolic relevance

The pregnane X receptor (PXR, NR1I2) is a ligand activated transcription factor that belongs to the nuclear hormone receptor (NR) superfamily. PXR is highly expressed in the liver and intestine, but low levels of expression have also been found in many other tissues. PXR plays an integral role in xenobiotic and endobiotic metabolism by regulating the expression of drug-metabolizing enzymes and transporters, as well as genes implicated in the metabolism of endobiotics. PXR exerts its transcriptional regulation by binding to its DNA response elements as a heterodimer with the retinoid X receptor (RXR) and recruitment of a host of coactivators. The biological and physiological implications of PXR activation are broad, ranging from drug metabolism and drug-drug interactions to the homeostasis of numerous endobiotics, such as glucose, lipids, steroids, bile acids, bilirubin, retinoic acid, and bone minerals. The purpose of this article is to provide an overview on the transcriptional circuits and metabolic relevance controlled by PXR. This article is part of a Special Issue entitled: Translating Nuclear Receptors from Health to Disease.

Megadose vitamin C suppresses sulfoconjugation in human colon carcinoma cell line Caco-2

Intake of high doses of vitamin C has known to modulate sulfoconjugation of drugs in the intestine, but the underlying mechanisms for this effect remain to be elucidated. In the present study, we investigated the effects of vitamin C (l-ascorbic acid (AA)) on sulfation of 1-naphthol using Caco-2 cells, a model of human intestinal cells. We found that high dose of AA inhibited the accumulation of 1-naphthyl sulfate in Caco-2 culture medium within 24h in a dose-dependent manner (IC(50)=42 mM). Dehydroascorbic acid (DA), an oxidized form of AA, showed no inhibition. AA did not inhibit the in vitro sulfotransferase (SULT) activity toward 1-naphthol, whereas it reduced the expression of genes belonging to SULT1A family, SULT1A1 and SULT1A3. DA showed no effect on SULT1A gene expression. Consistent with the reduction in gene expression, AA reduced the cytosolic SULT activity towards 1-naphthol in the AA-treated Caco-2 cells. In addition, cAMP exerted an additive effect on AA-mediated repression of SULT1A gene expression. Our results suggest that megadose AA suppresses sulfoconjugation in the intestine mainly by downregulating the expression of SULT1A genes.

Glucocorticoids stimulate hepatic and renal catecholamine inactivation by direct rapid induction of the dopamine sulfotransferase Sult1d1

During the stress response and metabolic fasting, glucocorticoids acting via the glucocorticoid receptor (GR) stimulate hepatic glucose production by activating specific gluconeogenic enzyme target genes. To characterize novel direct GR-regulated hepatic target genes under glucocorticoid control, we performed a whole genome gene expression microarray using dexamethasone-treated GR-null mice. Strongly induced previously characterized genes included phosphoenolpyruvate carboxykinase, serine dehydratase, tyrosine oxygenase, lipin 1, metallothionine, and cdkn1A. Novel induced genes included Ddit4, Fkbp5, Megf9, Sult1e1, and Sult1d1, and all were verified by real-time PCR. Sult1d1, a sulfotransferase, is a member of a large superfamily of detoxification enzymes and has an important role in the inactivation of endogenous dopamine-derived compounds, including the catecholamines. Treatment of primary mouse hepatocytes with dexamethasone for 6 h dramatically increased Sult1d1 mRNA levels, whereas cotreatment with RU-486, a GR antagonist, blocked induction by dexamethasone. Sult1d1 mRNA levels were also increased by dexamethasone in the kidney, a major site of Sult1d1 synthesis. Sult1d1 mRNA was localized by in situ hybridization to renal collecting ducts and was rapidly induced by glucocorticoids in renal inner medullary collecting duct (IMCD3) cells. Hepatic and renal Sult1d1 enzymatic activity was significantly induced in vivo in wild-type mice 6 h after dexamethasone treatment. Chromatin immunoprecipitation assay analysis upstream of the Sult1d1 gene promoter identified a glucocorticoid response element close to the neighboring glucocorticoid-responsive estrogen sulfotransferase Sult1e1 gene, indicating that both genes potentially share a common glucocorticoid response element. These results suggest that Sult1d1 in mice is directly induced by glucocorticoids and may attenuate elevated catecholamine activity during the stress response.