Simultaneous quantification of cholesterol sulfate, androgen sulfates, and progestagen sulfates in human serum by LC-MS/MS

Identification of multiple plasma lipids as diagnostic biomarkers of hypercholesterolemia and the underlying mechanisms based on pseudo-targeted lipidomics

RATIONALE

Hypercholesterolemia is an important risk factor for cardiovascular diseases and death. This study performed pseudo-targeted lipidomics to identify differentially expressed plasma lipids in hypercholesterolemia, to provide a scientific basis for the diagnosis and pathogenesis of hypercholesterolemia.

METHODS

Pseudo-targeted lipidomic analyses of plasma lipids from 20 patients with hypercholesterolemia and 20 normal control subjects were performed using liquid chromatography-mass spectrometry. Differentially expressed lipids were identified by principal component analysis and orthogonal partial least squares discriminant analysis. Receiver operating characteristic curves were used to identify differentially expressed lipids with high diagnostic value. The Kyoto Encyclopedia of Genes and Genomes pathway database was used to identify enriched metabolic pathways.

RESULTS

We identified 13 differentially expressed lipids in hypercholesterolemia using variable importance of projection > 1 and p < 0.05 as threshold parameters. The levels of eight sphingomyelins and cholesterol sulfate were higher and those of three triacylglycerols and lysophosphatidylcholine were reduced in hypercholesterolemia. Seven differentially expressed plasma lipids showed high diagnostic value for hypercholesterolemia. Functional enrichment analyses showed that pathways related to necroptosis, sphingolipid signaling, sphingolipid metabolism, and steroid hormone biosynthesis were enriched.

CONCLUSIONS

This pseudo-targeted lipidomics study demonstrated that multiple sphingomyelins and cholesterol sulfate were differentially expressed in the plasma of patients with hypercholesterolemia. We also identified seven plasma lipids, including six sphingomyelins and cholesterol sulfate, with high diagnostic value.

Sulfate: a neglected (but potentially highly relevant) anion

Sulfate is an important anion as sulfonation is essential in modulation of several compounds, such as exogens, polysaccharide chains of proteoglycans, cholesterol or cholesterol derivatives and tyrosine residues of several proteins. Sulfonation requires the presence of both the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) and a sulfotransferase. Genetic disorders affecting sulfonation, associated with skeletal abnormalities, impaired neurological development and endocrinopathies, demonstrate the importance of sulfate. Yet sulfate is not measured in clinical practice. This review addresses sulfate metabolism and consequences of sulfonation defects, how to measure sulfate and why we should measure sulfate more often.

Urine and serum metabolic profiling combined with machine learning for autoimmune disease discrimination and classification

Precision diagnosis and classification of autoimmune diseases (ADs) is challenging due to the obscure symptoms and pathological causes. Biofluid metabolic analysis has the potential for disease screening, in which high throughput, rapid analysis and minimum sample consumption must be addressed. Herein, we performed metabolomic profiling by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) in urine and serum samples. Combined with machine learning (ML), metabolomic patterns from urine achieved the discrimination and classification of ADs with high accuracy. Furthermore, metabolic disturbances among different ADs were also investigated, and provided information of etiology. These results demonstrated that urine metabolic patterns based on MALDI-MS and ML manifest substantial potential in precision medicine.

Single-run UHPLC-MS/MS method for simultaneous quantification of endogenous steroids and their phase II metabolites in serum for anti-doping purposes

Anti-doping rule violations related to the abuse of endogenous anabolic androgenic steroids can be currently discovered by the urinary steroidal module of Athlete Biological Passport. Since this powerful tool is still subjected to some limitations due to various confounding factors altering the steroid profile, alternative strategies have been constantly proposed. Among these, the measurement of blood concentrations of endogenous steroid hormones by LC-MS is currently of increasing interest in anti-doping, bringing significant advantages for the detection of testosterone abuse in females and in individuals with deletion of UGT2B17 enzyme. Although various research groups have made significant efforts in method development, there is currently no accepted or harmonized anti-doping method for quantitative analysis of the various testosterone doping markers in blood. In this study we present a UHPLC-MS/MS method for the quantification of major circulating steroid hormones together with an extended panel of glucuro- and sulpho-conjugated phase II metabolites of androgens. Chromatographic setup was optimized by comparing the performance of three different C18 stationary phases and by the careful selection of mobile phases with the aim of separating all the target steroids, including numerous isomeric/isobaric compounds. MS parameters were fine-tuned to obtain the sensitivity needed for measuring the target analytes, that show specific serum concentrations ranging from low pg/mL for less abundant compounds to μg/mL for sulpho-conjugated steroids. Finally, sample preparation protocol was developed for the extraction of steroid hormones from 200 μL of serum and the performance was evaluated in terms of extraction recovery and matrix effect. The final method was then applied to authentic serum samples collected from healthy volunteers (40 males and 40 females) at the Blood Bank of the City of Health and Science University Hospital of Turin. The analysis of these samples allowed to obtain results on serum concentrations of the targeted steroids, with particular emphasis on previously undiscovered phase II metabolites, such as the isomers of 5-androstane-3,17-diol glucuronide. This preliminary application also enabled measuring dihydrotestosterone sulphate in male samples, efficiently separating this analyte from its isomer, epiandrosterone sulphate, which circulates in blood at high concentrations. The promising results of this study are encouraging for the measurement of blood steroid profile markers in serum and plasma samples for Athlete Biological Passport purposes.

Altered profile of plasma phospholipids in woman with recurrent pregnancy loss and recurrent implantation failure treated with lipid emulsion therapy

BACKGROUND

Recurrent Pregnancy Loss (RPL) and Recurrent Implantation Failure (RIF) are highly heterogeneous condition and many of the mechanisms involved still require elucidation. The aim was to analyze the lipidomic profile in plasma of women with RPL and RIF before and after receiving the Lipid Emulsion Therapy (LET) containing 10% fish oil (SMOFlipid^® 20%).

METHODS

This study included twenty-six women with RPL or RIF from immunological or inflammatory causes, with elevated natural killer cell levels and divided into a Pregnancy Loss or a Live Birth group according to the outcome. The women received intravenous LET and sample collecting was done before the first, third and fifth dose of LET in the pregnant women. Ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF MS) and multivariate statistical methods were performed to evaluate the profile of phospholipids present in the women's plasma.

RESULTS

An increase of phosphatidylcholines (PC) 40:8 and 36:5 levels with predominance of n6 polyunsaturated fatty acids (PUFA) was observed in plasma lipids of the Pregnancy Loss Group compared to Live Birth Group. We also observed an increase in the relative abundance of n3 PUFA-PC species (42:10 and 36:6) and LysoPC 15:0 with the long term use of LET.

CONCLUSION

The greater availability of n3 PUFA in plasma of the pregnant women stemming from LET use can be considered advantageous regarding the alteration of the phospholipid profile and its postulated anti-inflammatory and immunomodulatory role.

Biallelic variants in the SLC13A1 sulfate transporter gene cause hyposulfatemia with a mild spondylo-epi-metaphyseal dysplasia

Sulfate is the fourth most abundant anion in human plasma but is not measured in clinical practice and little is known about the consequences of sulfate deficiency. Nevertheless, sulfation plays an essential role in the modulation of numerous compounds, including proteoglycans and steroids. We report the first patient with a homozygous loss-of-function variant in the SLC13A1 gene, encoding a renal and intestinal sulfate transporter, which is essential for maintaining plasma sulfate levels. The homozygous (Arg12Ter) variant in SLC13A1 was found by exome sequencing performed in a patient with unexplained skeletal dysplasia. The main clinical features were enlargement of joints and spondylo-epi-metaphyseal radiological abnormalities in early childhood, which improved with age. In addition, autistic features were noted. We found profound hyposulfatemia due to complete loss of renal sulfate reabsorption. Cholesterol sulfate was reduced. Intravenous N-acetylcysteine administration temporarily restored plasma sulfate levels. We conclude that loss of the SLC13A1 gene leads to profound hypersulfaturia and hyposulfatemia, which is mainly associated with abnormal skeletal development, possibly predisposing to degenerative bone and joint disease. The diagnosis might be easily missed and more frequent.

Online In-Tube Solid-Phase Microextraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry for Automated Analysis of Four Sulfated Steroid Metabolites in Saliva Samples

Accurate measurement of sulfated steroid metabolite concentrations can not only enable the elucidation of the mechanisms regulating steroid metabolism, but also lead to the diagnosis of various related diseases. The present study describes a simple and sensitive method for the simultaneous determination of four sulfated steroid metabolites in saliva, pregnenolone sulfate (PREGS), dehydroepiandrosterone sulfate (DHEAS), cortisol sulfate (CRTS), and 17β-estradiol-3-sulfate (E2S), by online coupling of in-tube solid-phase microextraction (IT-SPME) and stable isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). These compounds were extracted and concentrated on Supel-Q PLOT capillary tubes by IT-SPME and separated and detected within 6 min by LC-MS/MS using an InertSustain swift C18 column and negative ion mode multiple reaction monitoring systems. These operations were fully automated by an online program. Calibration curves using their stable isotope-labeled internal standards showed good linearity in the range of 0.01-2 ng mL^-1 for PREGS, DHEAS, and CRTS and of 0.05-10 ng mL^-1 for E2S. The limits of detection (S/N = 3) of PREGS, DHEAS, CRTS, and E2S were 0.59, 0.30, 0.80, and 3.20 pg mL^-1, respectively. Moreover, intraday and interday variations were lower than 11.1% (n = 5). The recoveries of these compounds from saliva samples were in the range of 86.6-112.9%. The developed method is highly sensitive and specific and can easily measure sulfated steroid metabolite concentrations in 50 μL saliva samples.

Oxysterols and Oxysterol Sulfates in Alzheimer’s Disease Brain and Cerebrospinal Fluid

Background:

Brain cholesterol levels are tightly regulated but increasing evidence indicates that cholesterol metabolism may drive Alzheimer’s disease (AD)-associated pathological changes. Recent advances in understanding of mitochondrial dysfunction in AD brain have presented a vital role played by mitochondria in oxysterol biosynthesis and their involvement in pathophysiology. Oxysterol accumulation in brain is controlled by various enzymatic pathways including sulfation. While research into oxysterol is under the areas of active investigation, there is less evidence for oxysterol sulfate levels in human brain.

Objective:

This study investigates the hypothesis that AD brain oxysterol detoxification via sulfation is impaired in later stages of disease resulting in oxysterol accumulation.

Methods:

Lipids were extracted from postmortem frozen brain tissue and cerebrospinal (CSF) from late- (Braak stage III-IV) and early- (Braak stage I-II) stage AD patients. Samples were spiked with internal standards prior to lipid extraction. Oxysterols were enriched with a two-step solid phase extraction using a polymeric SPE column and further separation was achieved by LC-MS/MS.

Results:

Oxysterols, 26-hydroxycholesterol (26-OHC), 25-hydroxycholesterol (25-OHC), and 7-oxycholesterol levels were higher in brain tissue and mitochondria extracted from late-stage AD brain tissue except for 24S-hydroxycholesterol, which was decreased in late AD. However, oxysterol sulfates are significantly lower in the AD frontal cortex. Oxysterols, 25-OHC, and 7-oxocholesterol was higher is CSF but 26-OHC and oxysterol sulfate levels were not changed.

Conclusion:

Our results show oxysterol metabolism is altered in AD brain mitochondria, favoring synthesis of 26-OHC, 25-OHC, and 7-oxocholesterol, and this may influence brain mitochondrial function and acceleration of the disease.

Congenital Adrenal Hyperplasia-Current Insights in Pathophysiology, Diagnostics, and Management

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders affecting cortisol biosynthesis. Reduced activity of an enzyme required for cortisol production leads to chronic overstimulation of the adrenal cortex and accumulation of precursors proximal to the blocked enzymatic step. The most common form of CAH is caused by steroid 21-hydroxylase deficiency due to mutations in CYP21A2. Since the last publication summarizing CAH in Endocrine Reviews in 2000, there have been numerous new developments. These include more detailed understanding of steroidogenic pathways, refinements in neonatal screening, improved diagnostic measurements utilizing chromatography and mass spectrometry coupled with steroid profiling, and improved genotyping methods. Clinical trials of alternative medications and modes of delivery have been recently completed or are under way. Genetic and cell-based treatments are being explored. A large body of data concerning long-term outcomes in patients affected by CAH, including psychosexual well-being, has been enhanced by the establishment of disease registries. This review provides the reader with current insights in CAH with special attention to these new developments.

Mass Spectrometry as a Crucial Analytical Basis for Omics Sciences

This review is devoted to the consideration of mass spectrometric platforms as applied to omics sciences. The most significant attention is paid to omics related to life sciences (genomics, proteomics, meta-bolomics, lipidomics, glycomics, plantomics, etc.). Mass spectrometric approaches to solving the problems of petroleomics, polymeromics, foodomics, humeomics, and exosomics, related to inorganic sciences, are also discussed. The review comparatively presents the advantages of various principles of separation and mass spectral techniques, complementary derivatization, used to obtain large arrays of various structural and quantitative information in the mentioned omics sciences.

Altered Steroidome in Women with Gestational Diabetes Mellitus: Focus on Neuroactive and Immunomodulatory Steroids from the 24th Week of Pregnancy to Labor

Gestational diabetes mellitus (GDM) is a complication in pregnancy, but studies focused on the steroidome in patients with GDM are not available in the public domain. This article evaluates the steroidome in GDM+ and GDM- women and its changes from 24 weeks (± of gestation) to labor. The study included GDM+ (n = 44) and GDM- women (n = 33), in weeks 24-28, 30-36 of gestation and at labor and mixed umbilical blood after delivery. Steroidomic data (101 steroids quantified by GC-MS/MS) support the concept that the increasing diabetogenic effects with the approaching term are associated with mounting progesterone levels. The GDM+ group showed lower levels of testosterone (due to reduced AKR1C3 activity), estradiol (due to a shift from the HSD17B1 towards HSD17B2 activity), 7-oxygenated androgens (competing with cortisone for HSD11B1 and shifting the balance from diabetogenic cortisol towards the inactive cortisone), reduced activities of SRD5As, and CYP17A1 in the hydroxylase but higher CYP17A1 activity in the lyase step. With the approaching term, the authors found rising activities of CYP3A7, AKR1C1, CYP17A1 in its hydroxylase step, but a decline in its lyase step, rising conjugation of neuroinhibitory and pregnancy-stabilizing steroids and weakening AKR1D1 activity.

Steroid sulfates in domestic mammals and laboratory rodents

Historically steroid sulfates have been considered predominantly as inactive metabolites. It was later discovered that by cleavage of the sulfate residue by steroid sulfatase (STS), they can be (re-)converted into active forms or into precursors for the local production of active steroids. This sulfatase pathway is now a very active field of research, which has gained considerable interest particularly in connection with the steroid metabolism of human steroid hormone-dependent cancer tissue. In comparison, there is much less information available on the occurrence of the sulfatase pathway in physiological settings, where the targeted uptake of steroid sulfates by specific transporters and their hydrolysis could serve to limit steroid effects to a subgroup of potentially steroid responsive cells. In humans, steroid sulfates of adrenal origin circulate in intriguingly high concentrations throughout most of life. Thus, ample substrate is available for the sulfatase pathway regardless of sex. However, the abundant adrenal output of steroid sulfates is a specific feature of select primates. Compared to humans, in our domestic mammals (dogs, cats, domestic ungulates) and laboratory rodents (mouse, rat) research into the biology of steroid sulfates is still in its infancy and information on the subject has so far been largely limited to punctual observations, which indicate considerable species-specific peculiarities. The aim of this overview is to provide a summary of the relevant information available in the above-mentioned species, predominantly taking into account data on concentrations of steroid sulfates in blood as well as the expression patterns and activities of relevant sulfotransferases and STS.

Effective sample preparation procedure for the analysis of free neutral steroids, free steroid acids and sterol sulfates in different tissues by GC-MS

Steroids play an important role in cell regulation and homeostasis. Many diseases like Alzheimer's disease or Smith-Lemli-Opitz syndrome are known to be associated with deviations in the steroid profile. Most published methods only allow the analysis of small subgroups of steroids and cannot give an overview of the total steroid profile. We developed and validated a method that allows the analysis of free neutral steroids, including intermediates of cholesterol biosynthesis, free oxysterols, C₁₉ and C₂₁ steroids, free steroid acids, including bile acids, and sterol sulfates using gas chromatography-mass spectrometry. Samples were analyzed in scan mode for screening purposes and in dynamic multiple reaction monitoring mode for highly sensitive quantitative analysis. The method was validated for mouse brain and liver tissue and consists of sample homogenization, lipid extraction, steroid group separation, deconjugation, derivatization and gas chromatography-mass spectrometry analysis. We applied the method on brain and liver samples of mice (10 months and 3 weeks old) and cultured N2a cells and report the endogenous concentrations of 29 physiological steroids.

The Enigma of the Adrenarche: Identifying the Early Life Mechanisms and Possible Role in Postnatal Brain Development

Dehydroepiandrosterone (DHEA) and its sulfated metabolite (DHEAS) are dynamically regulated before birth and the onset of puberty. Yet, the origins and purpose of increasing DHEA[S] in postnatal development remain elusive. Here, we draw attention to this pre-pubertal surge from the adrenal gland—the adrenarche—and discuss whether this is the result of intra-adrenal gene expression specifically affecting the zona reticularis (ZR), if the ZR is influenced by the hypothalamic-pituitary axis, and the possible role of spino-sympathetic innervation in prompting increased ZR activity. We also discuss whether neural DHEA[S] synthesis is coordinately regulated with the developing adrenal gland. We propose that DHEA[S] is crucial in the brain maturation of humans prior to and during puberty, and suggest that the function of the adrenarche is to modulate, adapt and rewire the pre-adolescent brain for new and ever-changing social challenges. The etiology of DHEA[S] synthesis, neurodevelopment and recently described 11-keto and 11-oxygenated androgens are difficult to investigate in humans owing to: (i) ethical restrictions on mechanistic studies, (ii) the inability to predict which individuals will develop specific mental characteristics, and (iii) the difficulty of conducting retrospective studies based on perinatal complications. We discuss new opportunities for animal studies to overcome these important issues.

Analytical Methods for the Determination of Neuroactive Steroids

Neuroactive steroids are a family of all steroid-based compounds, of both natural and synthetic origin, which can affect the nervous system functions. Their biosynthesis occurs directly in the nervous system (so-called neurosteroids) or in peripheral endocrine tissues (hormonal steroids). Steroid hormone levels may fluctuate due to physiological changes during life and various pathological conditions affecting individuals. A deeper understanding of neuroactive steroids' production, in addition to reliable monitoring of their levels in various biological matrices, may be useful in the prevention, diagnosis, monitoring, and treatment of some neurodegenerative and psychiatric diseases. The aim of this review is to highlight the most relevant methods currently available for analysis of neuroactive steroids, with an emphasis on immunoanalytical methods and gas, or liquid chromatography combined with mass spectrometry.

OATP2B1 - The underrated member of the organic anion transporting polypeptide family of drug transporters?

The organic anion transporting polypeptide 2B1 (OATP2B1) was one of the first cloned members of the SLCO family. However, its physiological and pharmacological role is still poorly understood, and object of a current debate on the transporter's relevance. Within this commentary, we summarize the data currently available on the transporter's expression and its substrates and highlight the strength and difficulties of the methods that have been applied to gather these data. The conclusion drawn from these findings was that OATP2B1 due to its intestinal expression is most likely involved in oral drug absorption of its substrate and therefore prone for interactions. This has been tested in in vivo drug interaction and/or pharmacogenetic studies. While some of these support the notion of OATP2B1 being of relevance in drug absorption, the pharmacogenetic findings are rather inconclusive. We will explain our thoughts why OATP2B1 may not influence the general systemic pharmacokinetic of certain substrates, but possibly local distribution processes, like the transfer across the blood-brain-barrier. Besides the pharmacokinetic aspects, there are data on endogenous molecules like coproporphyrins and sulfated steroids. Therefore, we will also highlight possible physiological roles of OATP2B1, which are driven by its expression pattern in the tubular cells of the kidney as well as its expression in the blood brain barrier. Finally we also deal with the advantages and disadvantages in the use of animal models to decipher the role of OATP2B1 in pharmacokinetics of its substrates and beyond.

25-Hydroxycholesterol 3-sulfate is an endogenous ligand of DNA methyltransferases in hepatocytes

The oxysterol sulfate, 25-hydroxycholesterol 3-sulfate (25HC3S), has been shown to play an important role in lipid metabolism, inflammatory response, and cell survival. However, the mechanism(s) of its function in global regulation is unknown. The current study investigates the molecular mechanism by which 25HC3S functions as an endogenous epigenetic regulator. To study the effects of oxysterols/sterol sulfates on epigenetic modulators, 12 recombinant epigenetic enzymes were used to determine whether 25HC3S acts as their endogenous ligand. The enzyme kinetic study demonstrated that 25HC3S specifically inhibited DNA methyltransferases (DNMTs), DNMT1, DNMT3a, and DNMT3b with IC₅₀ of 4.04, 3.03, and 9.05 × 10^-6 M, respectively. In human hepatocytes, high glucose induces lipid accumulation by increasing promoter CpG methylation of key genes involved in development of nonalcoholic fatty liver diseases. Using this model, whole genome bisulfate sequencing analysis demonstrated that 25HC3S converts the ^5mCpG to CpG in the promoter regions of 1,074 genes. In addition, we observed increased expression of the demethylated genes, which are involved in the master signaling pathways, including MAPK-ERK, calcium-AMP-activated protein kinase, and type II diabetes mellitus pathways. mRNA array analysis showed that the upregulated genes encoded for key elements of cell survival; conversely, downregulated genes encoded for key enzymes that decrease lipid biosynthesis. Taken together, our results indicate that the expression of these key elements and enzymes are regulated by the demethylated signaling pathways. We summarized that 25HC3S DNA demethylation of ^5mCpG in promoter regions is a potent regulatory mechanism.

From a single steroid to the steroidome: Trends and analytical challenges

For several decades now, the analysis of steroids has been a key tool in the diagnosis and monitoring of numerous endocrine pathologies. Thus, the available methods used to analyze steroids in biological samples have dramatically evolved over time following the rapid pace of technology and scientific knowledge. This review aims to synthetize the advances in steroids' analysis, from classical approaches considering only a few steroids or a limited number of steroid ratios, up to the new steroid profiling strategies (steroidomics) monitoring large sets of steroids in biological matrices. In this context, the use of liquid chromatography coupled to mass spectrometry has emerged as the technique of choice for the simultaneous determination of a high number of steroids, including phase II metabolites, due to its sensitivity and robustness. However, the large dynamic range to be covered, the low natural abundance of some key steroids, the selectivity of the analytical methods, the extraction protocols, and the steroid ionization remain some of the current challenges in steroid analysis. This review provides an overview of the different analytical workflows available depending on the number of steroids under study. Special emphasis is given to sample treatment, acquisition strategy, data processing, steroid identification and quantification using LC-MS approaches. This work also outlines how the availability of steroid standards, the need for complementary analytical strategies and the improvement of calibration approaches are crucial for achieving complete steroidome quantification.

Targeted LC-MS/MS analysis of steroid glucuronides in human urine

Conjugation with glucuronic acid is one of the major metabolic reactions in human steroid hormone catabolism. Recently, increasing interest has been raised concerning the biological roles of steroid glucuronides. We have therefore developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of 15 urinary steroid hormone glucuronides in human urine: androsterone glucuronide (An-G), etiocholanolone glucuronide (Etio-G), epiandrosterone glucuronide (epiAn-G), dihydrotestosterone glucuronide (DHT-G), dehydroepiandrosterone glucuronide (DHEA-G), testosterone glucuronide (T-G), epitestosterone glucuronide (epiT-G), estrone glucuronide (E1-3 G), 17β-estradiol 17-glucuronide (E2-17 G), 17β-estradiol 3-glucuronide (E2-3 G), estriol 16-glucuronide (E3-16 G), pregnenolone glucuronide (Preg-G), tetrahydro-11-deoxycorticosterone 3-glucuronide (THDOC-3 G), cortisol 21-glucuronide (F-G) and pregnanediol glucuronide (PD-G). Sample workup included protein precipitation and solid phase extraction. Internal standards were used to correct for the loss of analytes during sample preparation and analysis. The method showed good linearity (R²≥0.99) and recovery ranged from 89.6 % to 113.8 %. Limit of quantification ranged from 1.9 nmol/L for F-G to 21.4 nmol/L for An-G. Intra-day and inter-day accuracy and precision were below 15 % for all quality controls. The method was successfully applied to 67 urine samples from children and adolescents in whom total concentrations of free and conjugated steroids had been previously determined by GC-MS after enzymatic hydrolysis. Free and sulfated steroids were also measured by LC-MS/MS. In general, the sums of the respective glucuronidated, sulfated and free forms of an analyte corresponded well with its total amount determined after enzymatic hydrolysis by GC-MS. Regarding the most prominent steroid metabolites, the total mean levels of androsterone and etiocholanolone showed an increase up to 5820.0 nmol/L and 4017.8 nmol/L in the group of 15-20 year-old children, respectively. Glucuronide conjugates (4374.3 nmol/L and 3588.5 nmol/L, respectively) dominated. DHEA was excreted mostly as sulfate (0-1 month of age: 184.5 nmol/L; 15-20 years of age: 1618.4 nmol/L) in all age groups. Cortisol was present predominantly as sulfate (mean: 173.8 nmol/L) in newborns. Levels of sulfated cortisol decreased with age, its glucuronidated form increased. The levels of free cortisol were relatively constant throughout childhood. Sex hormones were preferably excreted as glucuronides. In general, steroid hormone metabolites were conjugated to various extents with glucuronic acid or sulfuric acid and their ratio changed over lifetime.

Simultaneous screening for chemically diverse micropollutants in public water bodies in Japan by high-performance liquid chromatography-Orbitrap mass spectrometry

An improved assessment of environmental risks to public water bodies requires screening a large number of micropollutants. This study reports the development of a novel target screening method based on solid-phase extraction (SPE), HPLC, and high-resolution Orbitrap MS for the analysis of micropollutants with diverse chemical properties. First, target compounds were screened for their detectability by Orbitrap MS. An optimized SPE cartridge and HPLC column maximized recovery and separated most target compounds. The sensitivity and repeatability of the method was validated by determining the detection limits and relative standard deviation (RSD). Eighty-four compounds with highly diverse properties were simultaneously detected with detection limits of 0.1-100 ng/L. Of these compounds, 52 were quantitated, with R2 ≥ 0.99 by linearity analysis and SPE recovery ratios of ≥50%. The remaining 32 compounds were qualitatively detected, with R2 < 0.99 or SPE recovery ratio of <50%. Satisfactory repeatability was obtained (RSD < 13.5%). This method was applied to the surveillance of the Arakawa River in Japan in 2019. Thirty-two compounds, including pesticides, surfactants, plasticizers, adhesives, and industrial solvents, were detected in the river. The measured concentrations of 13 compounds were compared with their predicted no effect concentrations (PNECs). Decanoic acid showed a higher concentration than the corresponding PNEC value, suggesting that its risk to the Arakawa water environment required further evaluation. The concentrations of dicyclohexylamine, 1,3-diphenylguanidine, and 2,4-dichlorophenoxyacetic acid were higher than their corresponding PNEC/10 values, demonstrating that these compounds were of higher priority than other compounds.

Cholesterol and oxysterol sulfates: Pathophysiological roles and analytical challenges

Cholesterol and oxysterol sulfates are important regulators of lipid metabolism, inflammation, cell apoptosis, and cell survival. Among the sulfate-based lipids, cholesterol sulfate (CS) is the most studied lipid both quantitatively and functionally. Despite the importance, very few studies have analysed and linked the actions of oxysterol sulfates to their physiological and pathophysiological roles. Overexpression of sulfotransferases confirmed the formation of a range of oxysterol sulfates and their antagonistic effects on liver X receptors (LXRs) prompting further investigations how are the changes to oxysterol/oxysterol sulfate homeostasis can contribute to LXR activity in the physiological milieu. Here, we aim to bring together for novel roles of oxysterol sulfates, the available techniques and the challenges associated with their analysis. Understanding the oxysterol/oxysterol sulfate levels and their pathophysiological mechanisms could lead to new therapeutic targets for metabolic diseases. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Esterification of 4β-hydroxycholesterol and other oxysterols in human plasma occurs independently of LCAT

The acyltransferase LCAT mediates FA esterification of plasma cholesterol. In vitro studies have shown that LCAT also FA-esterifies several oxysterols, but in vivo evidence is lacking. Here, we measured both free and FA-esterified forms of sterols in 206 healthy volunteers and 8 individuals with genetic LCAT deficiency, including familial LCAT deficiency (FLD) and fish-eye disease (FED). In the healthy volunteers, the mean values of the ester-to-total molar ratios of the following sterols varied: 4β-hydroxycholesterol (4βHC), 0.38; 5,6α-epoxycholesterol (5,6αEC), 0.46; 5,6β-epoxycholesterol (5,6βEC), 0.51; cholesterol, 0.70; cholestane-3β,5α,6β-triol (CT), 0.70; 7-ketocholesterol (7KC), 0.75; 24S-hydroxycholesterol (24SHC), 0.80; 25-hydroxycholesterol (25HC), 0.81; 27-hydroxycholesterol (27HC), 0.86; and 7α-hydroxycholesterol (7αHC), 0.89. In the individuals with LCAT deficiency, the plasma levels of the FA-esterified forms of cholesterol, 5,6αEC, 5,6βEC, CT, 7αHC, 7KC, 24SHC, 25HC, and 27HC, were significantly lower than those in the healthy volunteers. The individuals with FLD had significantly lower FA-esterified forms of 7αHC, 24SHC, and 27HC than those with FED. It is of note that, even in the three FLD individuals with negligible plasma cholesteryl ester, substantial amounts of the FA-esterified forms of 4βHC, 5,6αEC, 7αHC, 7KC, and 27HC were present. We conclude that LCAT has a major role in the FA esterification of many plasma oxysterols but contributes little to the FA esterification of 4βHC. Substantial FA esterification of 4βHC, 5,6αEC, 7αHC, 7KC, and 27HC is independent of LCAT.

Development and validation of an UHPLC–MS/MS method for extended serum steroid profiling in female populations

Aim: Quantitative endogenous steroid profiling in blood appears as a complementary approach to the urinary module of the World Anti-Doping Agency's Athlete Biological Passport Steroidal Module for the detection of testosterone doping. To refine this approach further, a UHPLC–MS/MS method was developed for the simultaneous determination of 14 free and 14 conjugated steroids in serum. Results: The method was validated for quantitative purposes with satisfactory results in terms of selectivity, linearity range, trueness, precision and combined uncertainty (<20%). The validated method was then applied to serum samples from both healthy women and women diagnosed with mild hyperandrogenism. Conclusion: The UHPLC–MS/MS method showed promising capability in quantifying free and conjugated steroids in serum and determining variations of their concentration/distribution within serum samples from different populations.

Very High Dehydroepiandrosterone Sulfate (DHEAS) in Serum of an Overweight Female Adolescent Without a Tumor

Introduction: An increase of serum dehydroepiandrosterone (DHEA) sulfate (DHEAS) is observed in premature adrenarche and congenital adrenal hyperplasia. Very high DHEAS levels are typical for adrenal tumors. Approximately 74% of DHEAS is hydrolyzed to DHEA by the steroid sulfatase (STS). The reverse reaction is DHEA sulfation. Besides these two enzyme reactions, the DHEAS transported through the cell membrane is important for its distribution and excretion. Case Presentation: We present a female adolescent with overweight and a very high DHEAS. The presence of a DHEAS-producing tumor was rejected using ultrasonography, Magnetic Resonance Tomography (MRT), and dexamethasone suppression. STS deficiency was suspected. Sequence analysis revealed a heterozygous nonsense mutation which predicts a truncation of the carboxyl region of the STS that is implicated in substrate binding. No partial gene deletion outside exon 5 was detected by multiplex ligation-dependent probe amplification. The bioassay revealed normal enzyme activity in the patient's leukocytes. A defect of transporter proteins was suggested. Both efflux [multidrug-resistance protein (MRP)2 and breast cancer-resistance protein (BCRP)] and uptake [organic anion-transporting polypeptide (OATP) and organic anion transporter (OAT) carriers] transporters were studied. Sequence analysis of exons revealed a heterozygous Q141K variant for BCRP. Conclusions: A novel heterozygous nonsense mutation in the STS gene and a known heterozygous missense variant in the BCRP gene were found. The heterozygous nonsense mutation in the STS gene is not supposed to be responsible for STS deficiency. The BCRP variant is associated with reduced efflux transport activity only in its homozygous state. The combination of the two heterozygous mutations could possibly explain the observed high levels of DHEAS and other sulfated steroids.

Selective LC-MRM/SIM-MS based profiling of adrenal steroids reveals metabolic signatures of 17α-hydroxylase deficiency

Adrenal steroids are generated in the adrenal cortex and metabolized by various enzymes such as hydroxylases, dehydrogenases, and reductases. Determining the comprehensive metabolic signatures of adrenal steroids can provide insight into their metabolic functions and roles in the pathophysiology of adrenal diseases, including Cushing's syndrome (CS) and congenital adrenal hyperplasia (CAH). To this end, we developed an advanced quantitative profiling method of serum adrenal steroids with liquid chromatography-mass spectrometry (LC-MS) under molecular-specific scan modes. Twenty-seven steroids were separated on a 1.9-μm particle C18 column (50 × 2.1 mm) at a flow rate of 250 μL/min and quantified via triple-quadrupole MS with electrospray ionization. During validation, linearities ( r²) were higher than 0.940 with a limit of quantification of 0.1-5.0 ng/mL, and precision (coefficient of variation) and accuracy (%bias) of 3.7-14.3 % and 96.3-113.1 %, respectively. In contrast with the significantly increased serum levels of mineralocorticoids (P <  0.001), the present LC-MS assay revealed remarkably decreased levels of all glucocorticoids and androgens in a patient diagnosed with 17α-hydroxylase deficiency CAH (P <  0.001) compared to those of age- and sex-matched healthy and CS subjects. In the CAH patient, the metabolic ratios for 17α-hydroxylase were significantly decreased, whereas there was no reduction in the metabolic ratio of 17-hydroxyprogesterone to androstenedione, indicating 17,20-lyase activity. In particular, both pregnenolone and dehydroepiandrosterone sulfates, and their metabolic ratio, were identified as potential biomarkers for 17α-hydroxylase deficiency (all P <  0.001), which were also distinct from those of CS patients. The devised LC-MS assay clearly revealed the metabolic signatures of 17α-hydroxylase deficiency, as a rare phenotype of CAH, compared to both healthy and CS subjects, indicating its utility for screening adrenal diseases.

Changes of BMI, steroid metabolome and psychopathology in patients with anorexia nervosa during hospitalization

Anorexia nervosa (AN) is associated with various alterations including the dysfunction of the HPA axis and consequently the hypercortisolemia and deficit in sex hormones but the comprehensive evaluation of changes in circulating steroids during the hospitalization of AN patients is lacking. We investigated the effect of realimentation of women with AN during hospitalization on 45 circulating steroids, the relationships between BMI, its change during hospitalization and physical activity, on one side and initial levels and their changes for two adipokines, circulating steroids, anorexia-specific (hunger, appetite and satiety), and anorexia non-specific symptoms (anxiety, depression fatigue, sleep, and body pain) on the other side. We included 33 women with anorexia who were hospitalized for 38(35, 44) days (median with quartiles). The increase of BMI from the initial value 15.2 (13.2, 16.6) kg/m² was 1.69 (1.37, 2.66) kg/m². The patients with more severe anorexia showed higher activity in 7β-, and 16α-hydroxylation of androgen precursors, which declined during hospitalization. Otherwise, the 7α-hydroxylation activity is higher in AN patients with less severe malnutrition and the ratio of 5-androstene-3β,7α,17β-triol to 5-androstene-3β,7β,17β-triol increased during the realimentation. Our data allow to speculate that the intensive 7β-, and 16α- and possibly also the 7α-hydroxylation of C19 Δ⁵ steroids participate in the pathophysiology of anorexia by additional catabolism of substrates available for synthesis of active androgens and estrogens. However, the question remains whether the synthetic analogues of 7α/β- and 16α-hydroxy-steroids prevent the catabolism of the sex steroid precursors, or further activate the "energy wasting" mitochondrial thermogenic metabolism.

Steroid Metabolome Analysis in Disorders of Adrenal Steroid Biosynthesis and Metabolism

Steroid biosynthesis and metabolism are reflected by the serum steroid metabolome and, in even more detail, by the 24-hour urine steroid metabolome, which can provide unique insights into alterations of steroid flow and output indicative of underlying conditions. Mass spectrometry-based steroid metabolome profiling has allowed for the identification of unique multisteroid signatures associated with disorders of steroid biosynthesis and metabolism that can be used for personalized approaches to diagnosis, differential diagnosis, and prognostic prediction. Additionally, steroid metabolome analysis has been used successfully as a discovery tool, for the identification of novel steroidogenic disorders and pathways as well as revealing insights into the pathophysiology of adrenal disease. Increased availability and technological advances in mass spectrometry-based methodologies have refocused attention on steroid metabolome profiling and facilitated the development of high-throughput steroid profiling methods soon to reach clinical practice. Furthermore, steroid metabolomics, the combination of mass spectrometry-based steroid analysis with machine learning-based approaches, has facilitated the development of powerful customized diagnostic approaches. In this review, we provide a comprehensive up-to-date overview of the utility of steroid metabolome analysis for the diagnosis and management of inborn disorders of steroidogenesis and autonomous adrenal steroid excess in the context of adrenal tumors.

A method for determination of one hundred endogenous steroids in human serum by gas chromatography-tandem mass spectrometry

Steroid profiling helps various pathologies to be rapidly diagnosed. Results from analyses investigating steroidogenic pathways may be used as a tool for uncovering pathology causations and proposals of new therapeutic approaches. The purpose of this study was to address still underutilized application of the advanced GC-MS/MS platform for the multicomponent quantification of endogenous steroids. We developed and validated a GC-MS/MS method for the quantification of 58 unconjugated steroids and 42 polar conjugates of steroids (after hydrolysis) in human blood. The present method was validated not only for blood of men and non-pregnant women but also for blood of pregnant women and for mixed umbilical cord blood. The spectrum of analytes includes common hormones operating via nuclear receptors as well as other bioactive substances like immunomodulatory and neuroactive steroids. Our present results are comparable with those from our previously published GC-MS method as well as the results of others. The present method was extended for corticoids and 17alpha-hydroxylated 5alpha/ß-reduced pregnanes, which are useful for the investigation of alternative "backdoor" pathway. When comparing the analytical characteristics of the present and previous method, the first exhibit by far higher selectivity, and generally higher sensitivity and better precision particularly for 17alpha-hydroxysteroids.

Activation of Adrenal Steroidogenesis and an Improvement of Mood Balance in Postmenopausal Females after Spa Treatment Based on Physical Activity

Spa treatment can effectively reestablish mood balance in patients with psychiatric disorders. In light of the adrenal gland’s role as a crossroad of psychosomatic medicine, this study evaluated changes in 88 circulating steroids and their relationships with a consolidation of somatic, psychosomatic and psychiatric components from a modified N-5 neurotic questionnaire in 46 postmenopausal 50+ women with anxiety-depressive complaints. The patients underwent a standardized one-month intervention therapy with physical activity and an optimized daily regimen in a spa in the Czech Republic. All participants were on medication with selective serotonin reuptake inhibitors. An increase of adrenal steroidogenesis after intervention indicated a reinstatement of the hypothalamic-pituitary-adrenal axis. The increases of many of these steroids were likely beneficial to patients, including immunoprotective adrenal androgens and their metabolites, neuroactive steroids that stimulate mental activity but protect from excitotoxicity, steroids that suppress pain perception and fear, steroids that consolidate insulin secretion, and steroids that improve xenobiotic clearance. The positive associations between the initial values of neurotic symptoms and their declines after the intervention, as well as between initial adrenal activity and the decline of neurotic symptoms, indicate that neurotic impairment may be alleviated by such therapy provided that the initial adrenal activity is not seriously disrupted.

Measurement of serum steroid profiles by HPLC-tandem mass spectrometry

Accurate investigations of adrenal hormone levels play a vital role in pediatric endocrinology for the detection of steroid-related disorders. In this study, we developed and validated a simultaneous assay for eight serum steroids, i.e., DHEA, androstenedione, testosterone, progesterone, 17‑hydroxyprogesterone, DHEA‑sulfate, pregnenolone‑sulfate and cholesterol-sulfate, using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Serum samples were prepared by liquid-liquid extraction with methyl t‑butyl ether. Quantitation by LC-MS/MS was performed in multiple reaction monitoring mode with an electrospray ionization source. The run time was 10 min. Analytical performance was evaluated, including imprecision, linearity, ion suppression, carry over and detection capabilities. Serum specimens from 59 children and 120 adults were analyzed to compare the distribution of steroid levels between the groups. All hormones were effectively extracted and separated using our method. The method was essentially free from potential interference and ion suppression. Within-run and between-run imprecision values were <20%. The lower limits of quantification varied from 0.025 to 10 ng/mL. The results were generally good and correlated with those obtained using immunoassay techniques. We developed the HPLC-MS/MS method for the simultaneous measurement of free and sulfated steroid hormones. The performance of the developed method was generally acceptable. Thus, this method may provide a novel approach to steroid profiling in children of age before adrenarche.

Temporal expression pattern of steroid-metabolizing enzymes in bovine COC during in vitro maturation employing different gonadotropin concentrations

Steroid hormones are regulators in the fine-tuned process of follicular development. During final maturation in vivo a switch from oestradiol (E2) to progesterone (P4) dominance within the follicle is well-described. This change is accompanied by the resumption of meiosis and results in the maturation of the oocyte. It also suggests the important role of these hormones. However, present in vitro maturation (IVM) systems do not completely mimic the in vivo situation, resulting in oocytes of reduced quality. Aim of the study was to determine the temporal pattern of steroid hormone concentrations in the IVM medium of bovine cumulus-oocyte-complexes (COC) at defined time points. The influence of different gonadotropin supplementations during IVM on oocyte maturation, as well as the molecular quality of the oocytes and their corresponding cumulus cells was investigated. COCs were obtained from abattoir-derived ovaries and matured in medium added with different compounds of gonadotropins (eCG/hCG; FSH/LH, each at 0.05 IU or 0.01 IU; only FSH; without gonadotropins) employing a standard protocol without oil overlay. In experiment 1, medium, oocytes and cumulus cells were collected at different time points (0 h [control], 4 h, 8 h, 12 h, 16 h, 20 h, 24 h) after IVM in just eCG/hCG-supplemented medium. In experiment 2, medium, oocytes and cumulus cells were collected at 0 h (control) and after 24 h of IVM with all above-named supplements. The E2 concentration remained similar during IVM whereas P4 concentration increased during experiment 1. No significant changes could be determined after the addition of different gonadotropins (experiment 2). These results suggest that during IVM the temporal pattern of E2 and P4 did not correspond with the pattern during final maturation in vivo. RT-qPCR was used to assess the relative abundance of developmentally important genes in oocytes (BMP15; GDF9; ZAR1; PGR; PGRMC1/2; G6PD; StAR; ESR1/2; SULT1E1; STS; SOAT) and cumulus cells (ESR1/2; FSHR; LHCGR; CYP19A1; HSD3B1; PGR; PGRMC1/2; SULT1E1; STS; SOAT) at all collection points in both experiments. Most transcripts follow a time-regulated mRNA expression pattern during the entire in vitro maturation period. In addition, the expression of the analyzed transcripts was not influenced by the different gonadotropin supplementations during the IVM period. In all, this underlines that present conditions of IVM do not reflect the in vivo situation and require further optimisation.

Sulfate-based lipids: Analysis of healthy human fluids and cell extracts

Sulfate-based lipids (SL) have been proposed as players in inflammation, immunity and infection. In spite of the many biochemical processes linked to SL, analysis on this class of lipids has only focused on specific SL sub-classes in individual fluids or cells leaving a range of additional SL in other biological samples unaccounted for. This study describes the mass spectrometry screening of SL in lipid extracts of human fluids (saliva, plasma, urine, seminal fluid) and primary human cells (RBC, neutrophils, fibroblasts and skin epidermal) using targeted precursor ion scanning (PIS) approach. The PIS 97 mass spectra reveal a wide diversity of SL including steroid sulfates, sulfoglycolipids and other unidentified SL, as well as metabolites such as taurines, sulfated polyphenols and hypurate conjugates. Semi-quantification of SL revealed that plasma exhibited the highest content of SL whereas seminal fluid and epithelial cells contained the highest sulphur to phosphorous (S/P) ratio. The complexity of biofluids and cells sulfateome presented in this study highlight the importance of expanding the panel of synthetic sulfate-based lipid standards. Also, the heterogenous distribution of SL provides evidence for the interplay of sulfotransferases/sulfatases, opening new avenues for biomarker discovery in oral health, cardiovascular, fertility and dermatology research areas.

The TRPP2-dependent channel of renal primary cilia also requires TRPM3

Primary cilia of renal epithelial cells express several members of the transient receptor potential (TRP) class of cation-conducting channel, including TRPC1, TRPM3, TRPM4, TRPP2, and TRPV4. Some cases of autosomal dominant polycystic kidney disease (ADPKD) are caused by defects in TRPP2 (also called polycystin-2, PC2, or PKD2). A large-conductance, TRPP2-dependent channel in renal cilia has been well described, but it is not known whether this channel includes any other protein subunits. To study this question, we investigated the pharmacology of the TRPP2-dependent channel through electrical recordings from the cilia of mIMCD-3 cells, a murine cell line of renal epithelial origin. The pharmacology was found to match that of TRPM3 channels. The ciliary TRPP2-dependent channel is known to be activated by depolarization and by increasing cytoplasmic Ca²⁺. This activation was greatly enhanced by external pregnenolone sulfate, an agonist of TRPM3 channels. Pregnenolone sulfate did not change the single-channel current-voltage relation. The channels were effectively blocked by isosakuranetin, a specific inhibitor of TRPM3 channels. Both pregnenolone sulfate and isosakuranetin were effective at concentrations as low as 1 μM. Knocking out TRPM3 by CRISPR/Cas9 genome editing eliminated the ciliary channel. Thus the channel is both TRPM3-dependent and TRPP2-dependent, suggesting that it may include both types of subunit. Knocking out TRPM3 did not change the level of TRPP2 protein in the cilia, so it is unlikely that the absence of functional ciliary channels results from a failure of trafficking.

Label-free impedimetric immunosensor based on arginine-functionalized gold nanoparticles for detection of DHEAS, a biomarker of pediatric adrenocortical carcinoma

Pediatric adrenocortical carcinoma (pACC) is a rare and aggressive malignancy of high occurrence in Southern Brazil. pACC is characterized by the usual overproduction of dehydroepiandrosterone sulfate (DHEAS), whose detection in serum or plasma can be effective to the early diagnosis of the disease. Therefore, the present paper reports, for the first time, the construction and application of a label-free impedimetric immunosensor to detect DHEAS, which was based on the modification of an oxidized glassy carbon electrode with arginine-functionalized gold nanoparticles (AuNPs-ARG) and anti-DHEA IgM antibodies (ox-GCE/AuNPs-ARG/IgM). AuNPs-ARG was synthesized by a green route, and characterized by UV-VIS spectroscopy, FTIR, TEM, DLS, and XRD. The construction of ox-GCE/AuNPs-ARG/IgM was optimized through factorial design and response surface methodology. Cyclic voltammetry and electrochemical impedance spectroscopy measurements were employed to characterize the optimized immunosensor. The DHEAS detection principle was based on the variation of charge transfer resistance (∆R_ct) relative to the Fe(CN)₆^4-/3- electrochemical probe after immunoassays in the presence of the biomarker. A linear relationship between ∆R_ct and DHEAS concentration was verified in the range from 10.0 to 110.0 µg dL^-1, with a LOD of 7.4 µg dL^-1. Besides the good sensitivity, the immunosensor displayed accuracy, stability, and specificity to detect DHEAS. The promising analytical performance of ox-GCE/AuNPs-ARG/IgM was confirmed by quantifying DHEAS in real patient plasma samples, with results that were comparable to the reference chemiluminescence assay. Our results suggest that the presented immunosensor can find clinical applications in the early diagnosis of pACC and to monitor DHEAS levels in other adrenal pathologies.

Characterizing the steroidal milieu in amniotic fluid of mid-gestation: A LC-MS/MS study

Growth and development of an embryo or fetus during human pregnancy mainly depend on intact hormone biosynthesis and metabolism in maternal amniotic fluid (AF). We investigated the hormonal milieu in AF and developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of 14 sulfated and 6 unconjugated steroids in AF. 65 A F samples (male: female = 35: 30) of mid-gestation ranging from 16^th week of gestation to 25^th week of gestation were analyzed. Reference data of 20 steroid levels in AF of healthy women were provided. 13 sulfated and 3 unconjugated steroids were for the first time quantified in AF by LC-MS/MS. Highest concentrations were found for pregnenolone sulfate (PregS: mean ± SD, 8.6 ± 3.7 ng/mL), 17α-hydroxypregnenolone sulfate (17OHPregS: 4.9 ± 2.0 ng/mL), epitestosterone sulfate (eTS: 7.3 ± 3.6 ng/mL), 16α-hydroxydehydroepiandrosterone sulfate (16OH-DHEAS: 21.5 ± 10.7 ng/mL), androsterone sulfate (AnS: 9.2 ± 7.4 ng/mL), estrone sulfate (E1S: 3.0 ± 3.0 ng/mL), estriol 3-sulfate (E3S: 8.1 ± 4.0 ng/mL) and estriol (E3: 1.2 ± 0.4 ng/mL). Only testosterone (T) showed a significant sex difference (p < 0.0001). Correlations between AF steroids mirrored the steroid metabolism of the feto-placental unit, and not only confirmed the classical steroid pathway, but also pointed to a sulfated steroid pathway.

UPLC⁻MS/MS Identification of Sterol Sulfates in Marine Diatoms

Diatoms are unicellular eukaryotic organisms that play a key ecological and biogeochemical role in oceans as major primary producers. Recently, these microalgae have also attracted interest as a promising source of functional products with widespread relevance. Progress in the knowledge of cell and molecular biology of diatoms is envisaged as a key step to understanding regulation of their life cycle in marine environments as well as facilitating their full and profitable exploitation by biotechnological platforms. Recently, we identified sterol sulfates (StS) as regulatory molecules of cell death in the diatom Skeletonema marinoi. As these compounds may have a general role in diatom physiology and chemical signals in aquatic systems, we investigated a suitable tool for their analysis in laboratory and field samples. Herein, we describe a sensitive, fast, and efficient ultra performance liquid chromatography–mass spectrometry (UPLC–MS) method for qualitative and quantitative analysis of StS from crude extract of diatoms and other microalgae. The method was applied to 13 different strains of our collection of marine protists. This first study suggested a species-specific distribution of StS and identified the sulfated derivatives of 24-methylene cholesterol and 24-methyl cholesterol as the most common members in diatoms.

Higher steroid sulfation is linked to successful weight loss in obese children

Objective Little information is available on the steroid sulfates profile in obese children. Therefore, we examined whether sulfated steroids are linked with weight status and associated comorbidities in obese children. Methods We analyzed 66 obese children (mean age 10.5 ± 2.5 years, 57.6% female, 53.9% prepubertal, mean BMI 27.0 ± 4.6 kg/m2, 50% with BMI-SDS reduction >0.5, 50% without BMI-SDS reduction) who participated in an outpatient 1-year intervention program based on exercise, behavior and nutrition therapy. We measured intact sulfated steroids (cholesterol sulfate (CS), pregnenolone sulfate (PregS), 17αOH pregnenolone sulfate (17OH-PregS), 16αOH dehydroepiandrosterone sulfate (16OH-DHEAS), DHEAS, androstenediol-3-sulfate, androsterone sulfate and epiandrosterone sulfate) by LC-MS/MS, and insulin resistance index HOMA, lipids, blood pressure at baseline and 1 year later. Results All sulfated steroids except 17OH-PregS, 16OH-DHEAS, androsterone sulfate and epiandrosterone sulfate were higher in boys compared to girls. Concentrations of CS before intervention were higher in children who lost weight. After 1 year of treatment, both groups showed increased levels of DHEAS, 16OH-DHEAS and androstenediol-3-sulfate, but PregS was only increased in children with weight loss. None of the steroid sulfates was significantly related to cardiovascular risk factors or HOMA except 17OH-PregS, which was associated with systolic blood pressure both in cross-sectional (β-coefficient: 0.09 ± 0.07, P = 0.020) and longitudinal analyses (β-coefficient: 0.06 ± 0.04, P = 0.013) in multiple linear regression analyses. Conclusions Since higher steroid sulfation capacity was associated with successful weight intervention in children disruption of sulfation may be associated with difficulties to lose weight. Future studies are necessary to prove this hypothesis.

GC/MS in Recent Years Has Defined the Normal and Clinically Disordered Steroidome: Will It Soon Be Surpassed by LC/Tandem MS in This Role?

Gas chromatography/mass spectrometry (GC/MS) has been used for steroid analysis since the 1960s. The advent of protective derivatization, capillary columns, and inexpensive electron ionization bench-top single quadrupole soon made it the method of choice for studying disorders of steroid synthesis and metabolism. However, the lengthy sample workup prevented GC/MS from becoming routine for steroid hormone measurement, which was dominated by radioimmunoassay. It was the emergence of liquid chromatography/tandem MS (LC/MS/MS) that sparked a renewed interest in GC/MS for the multicomponent analysis of steroids. GC/MS is excellent at providing an integrated picture of a person's steroid metabolome, or steroidome, as we term it. We review the recent work on newly described disorders and discuss the technical advances such as GC coupling to triple quadrupole and ion trap analyzers, two-dimensional GC/MS, and alternative ionization and detection systems such as atmospheric pressure chemical ionization (APCI) and time of flight. We believe that no novel GC/MS-based technique has the power of GC(electron ionization)/MS/MS as a "discovery tool," although APCI might provide ultimate sensitivity, which might be required in tissue steroidomics. Finally, we discuss the role of LC/MS/MS in steroidomics. This remains a challenge but offers shorter analysis times and advantages in the detection and discovery of steroids with a known structure. We describe recent advances in LC/MS steroidomics of hydrolyzed and intact steroid conjugates and suggest the technique is catching up with GC/MS in this area. However, in the end, both techniques will likely remain complementary and both should be available in advanced analytical laboratories.

SULFATION PATHWAYS: Insights into steroid sulfation and desulfation pathways

Sulfation and desulfation pathways represent highly dynamic ways of shuttling, repressing and re-activating steroid hormones, thus controlling their immense biological potency at the very heart of endocrinology. This theme currently experiences growing research interest from various sides, including, but not limited to, novel insights about phospho-adenosine-5'-phosphosulfate synthase and sulfotransferase function and regulation, novel analytics for steroid conjugate detection and quantification. Within this review, we will also define how sulfation pathways are ripe for drug development strategies, which have translational potential to treat a number of conditions, including chronic inflammatory diseases and steroid-dependent cancers.

GC/MS in Recent Years Has Defined the Normal and Clinically Disordered Steroidome: Will It Soon Be Surpassed by LC/Tandem MS in This Role?

Gas chromatography/mass spectrometry (GC/MS) has been used for steroid analysis since the 1960s. The advent of protective derivatization, capillary columns, and inexpensive electron ionization bench-top single quadrupole soon made it the method of choice for studying disorders of steroid synthesis and metabolism. However, the lengthy sample workup prevented GC/MS from becoming routine for steroid hormone measurement, which was dominated by radioimmunoassay. It was the emergence of liquid chromatography/tandem MS (LC/MS/MS) that sparked a renewed interest in GC/MS for the multicomponent analysis of steroids. GC/MS is excellent at providing an integrated picture of a person's steroid metabolome, or steroidome, as we term it. We review the recent work on newly described disorders and discuss the technical advances such as GC coupling to triple quadrupole and ion trap analyzers, two-dimensional GC/MS, and alternative ionization and detection systems such as atmospheric pressure chemical ionization (APCI) and time of flight. We believe that no novel GC/MS-based technique has the power of GC(electron ionization)/MS/MS as a “discovery tool,” although APCI might provide ultimate sensitivity, which might be required in tissue steroidomics. Finally, we discuss the role of LC/MS/MS in steroidomics. This remains a challenge but offers shorter analysis times and advantages in the detection and discovery of steroids with a known structure. We describe recent advances in LC/MS steroidomics of hydrolyzed and intact steroid conjugates and suggest the technique is catching up with GC/MS in this area. However, in the end, both techniques will likely remain complementary and both should be available in advanced analytical laboratories.

Sodium-dependent organic anion transporter (Slc10a6-/-) knockout mice show normal spermatogenesis and reproduction, but elevated serum levels for cholesterol sulfate

The sodium-dependent organic anion transporter SOAT (gene name SLC10A6 in man and Slc10a6 in mice) is a plasma membrane transporter for sulfated steroids, which is highly expressed in germ cells of the testis. SOAT can transport biologically inactive sulfated steroids into specific target cells, where they can be reactivated by the steroid sulfatase (STS) to biologically active, unconjugated steroids known to regulate spermatogenesis. Significantly reduced SOAT mRNA expression was previously found in different forms of impaired spermatogenesis in man. It was supposed that SOAT plays a role for the local supply of steroids in the testis and consequently for spermatogenesis and fertility. Thus, an Slc10a6^-/- Soat knockout mouse model was established by recombination-based target deletion of the Slc10a6 gene to elucidate the role of Soat in reproduction. However, the Slc10a6^-/- knockout mice were fertile, produced normal litter sizes, and had normal spermatogenesis and sperm vitality. This phenotype suggests that the loss of Soat can be compensated in the knockout mice or that Soat function is not essential for reproduction. In addition to reproductive phenotyping, a comprehensive targeted steroid analysis including a set of 9 un-conjugated and 12 sulfo-conjugated steroids was performed in serum of Slc10a6^-/- knockout and Slc10a6^+/+ wildtype mice. Only cholesterol sulfate, corticosterone, and testosterone (only in the males) could be detected in considerable amounts. Interestingly, male Slc10a6^-/- knockout mice showed significantly higher serum levels for cholesterol sulfate compared to their wildtype controls. As cholesterol sulfate has a broader impact apart from the testis, further analysis of this phenotype will include other organs such as skin and lung, which also show high Soat expression in the mouse.

Transport of steroid 3-sulfates and steroid 17-sulfates by the sodium-dependent organic anion transporter SOAT (SLC10A6)

The sodium-dependent organic anion transporter SOAT/Soat shows highly specific transport activity for sulfated steroids. SOAT substrates identified so far include dehydroepiandrosterone sulfate, 16α-hydroxydehydroepiandrosterone sulfate, estrone-3-sulfate, pregnenolone sulfate, 17β-estradiol-3-sulfate, and androstenediol sulfate. Apart from these compounds, many other sulfated steroids occur in mammals. Therefore, we aimed to expand the substrate spectrum of SOAT and analyzed the SOAT-mediated transport of eight different sulfated steroids by combining in vitro transport experiments in SOAT-transfected HEK293 cells with LC-MS/MS analytics of cell lysates. In addition, we aimed to better understand the structural requirements for SOAT substrates and so selected structural pairs varying only at specific positions: 3α/3β-sulfate, 17α/17β-sulfate, mono-sulfate/di-sulfate, and 17α-hydroxylation. We found significant and sodium-dependent SOAT-mediated transport of 17α-hydroxypregnenolone sulfate, 17β-estradiol-17-sulfate, androsterone sulfate, epiandrosterone sulfate, testosterone sulfate, epitestosterone sulfate, and 5α-dihydrotestosterone sulfate. However, 17β-estradiol-3,17-disulfate was not transported by SOAT.

IN CONCLUSION

SOAT substrates from the group of sulfated steroids are characterized by a planar and lipophilic steroid backbone in trans-trans-trans conformation of the rings and a negatively charged mono-sulfate group at positions 3' or 17' with flexibility for α- or β- orientation. Furthermore, 5α-reduction, 16α-hydroxylation, and 17α-hydroxylation are acceptable for SOAT substrate recognition, whereas addition of a second negatively charged sulfate group seems to abolish substrate binding to SOAT, and so 17β-estradiol-3,17-disulfate is not transported by SOAT.

Simultaneous profiles of sulfonated androgens, sulfonated estrogens and sulfonated progestogens in postpubertal boars (sus scrofa domestica) measured by LC-MS/MS

Sulfonated steroids (s-St) have been usually regarded as inactive metabolites but are progressively considered as precursors for the intra-tissue formation of bioactive steroids. Moreover, independent effects without preceding removal of the sulfate group have been observed. We use the porcine testicular-epididymal compartment as a model to investigate the still largely unknown s-St physiology as the boar exhibits an intriguingly broad s-St spectrum predominantly originating from the testis. The application of LC-MS/MS in steroidomics enables the determination of unconjugated and intact sulfonated steroids with currently highest specificity and good sensitivity, allowing the concurrent measuring of numerous analytes in larger quantities of samples. Profiles (6h, 20min intervals) were generated for sulfonated 5-androstene-3ß,17ß-diol (Adiol-S), androsterone (A-S), dehydroepiandrosterone (DHEA-S), epiandrosterone (EA-S), epitestosterone (ET-S), estrone (E1-S), estradiol-17β (E2-S), pregnenolone (P5-S), 17αOH-pregnenolone (OHP5-S) and unconjugated testosterone (T) in four unstimulated and four hCG-stimulated boars. Moreover, concentrations were measured in individual samples collected from testicular afferent and efferent blood to differentiate between testicular vs. extratesticular origin. Highest concentrations were found for EA-S, followed by ET-S, Adiol-S and DHEA-S, which mostly exceeded the levels of E1-S and A-S. Lowest concentrations were obtained for E2-S, P5-S and OHP5-S. The analytical profile also included sulfonated T, 5α-dihydrotestosterone and cholesterol. However, their concentrations were below the limit of quantification. Profiles of quantifiable s-St were consistent with a wave-like pattern associated with T pulses. In postpartal females (n=5) concentrations of all analytes assessed were undetectable, suggesting that in pigs the adrenals are not a quantitatively significant source of s-St.

The art of measuring steroids: Principles and practice of current hormonal steroid analysis

Steroids are small and highly important structural or signalling molecules in living organisms and their metabolism is complex. Due to the multiplicity of enzymes involved there are many different steroid related disorders. E.g., an individual enzyme defect is rather rare but can share various clinical symptoms and can thus be hardly diagnosed clinically. Therefore, reliable hormonal determination still presents the most reasonable initial diagnostic approach and helps to avoid uncritical and expensive attempts at molecular diagnostic testing. It also presents a backbone of monitoring these complex patients. In science, reliable hormone measurement is indispensable for the elucidation of new mechanisms of steroid hormone actions. Steroid analytics is highly challenging and should never be considered trivial. Most common methods for steroid determination comprise traditionally immunoassay, or more recently, mass spectrometry based methods. It is absolutely necessary that clinicians and scientists know the methods they are applying by heart. With the introduction of automated direct assays, a loss of quality could be observed over the last two decades in the field of steroid immunoassays. This review wants to meet the need for profound information and orientation in the field of steroid analysis. The pros and cons of the most important methods, such as immunoassays and mass spectrometry based methods will be discussed. The focus of the latter will lie on gas chromatography-mass spectrometry (GC-MS) as well as liquid chromatography-mass spectrometry (LC-MS). Selected analytical applications from our Deutsche Forschungsgemeinschaft Research Group FOR 1369 "Sulfated Steroids in Reproduction" will illustrate the contents. In brief, immunoassays have for long presented the traditional technique for steroid analysis. They are easy to set up. Only one analyte can be measured per immunoassay. Specificity problems can arise and caution has to be exerted especially regarding direct assays lacking purification steps. Mass spectrometry based methods provide structural information on the analyte and thus higher specificity. In combination with chromatographic techniques, they permit the simultaneous determination of a multitude of analytes. Highest specificity can be obtained using GC-MS, a sophisticated but most powerful tool for characterizing steroid metabolomes. LC-MS is a true high throughput technique and highly suited for detecting complex steroids. GC-MS and LC-MS are not competing but complementary techniques. Since reliable steroid determination requires extremely high expertise in the field of analytics as well as steroid biochemistry, it is recommended that collaborations and networking with highly specialized centers of expertise are developed.

Occurrence of sulfonated steroids and ovarian expression of steroid sulfatase and SULT1E1 in cyclic cows

Historically sulfonated steroids were primarily considered as inactive metabolites destined for elimination. However, more recently they have been increasingly recognized as precursors for the production of bioactive steroids in target tissues and as functional molecules without preceding hydrolysis. In order to comprehensively characterize their occurrence in cyclic cows and their formation and hydrolysis in bovine ovarian steroidogenesis, ovaries from cyclic cows were screened for the expression of oestrogen sulfotransferase (SULTE1) and steroid sulfatase (STS) by Western blot and immunohistochemistry. Moreover, a broad spectrum of 13 sulfonated steroids was measured applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) in blood samples collected from three cycling heifers during defined stages of the ovarian cycle and in fluid obtained from ovarian follicles of different size. SULT1E1 was undetectable in ovarian tissues. For STS only a weak immunostaining was found predominantly in granulosa cells of larger follicles. However, no specific band occurred in Western blot. In blood, concentrations of all sulfonated steroids investigated were below the limit of quantification (LOQ). In follicular fluid, only cholesterol sulfate was measured in considerable concentrations (328.3 ± 63.8 ng/ml). However, the role of cholesterol sulfate in bovine follicular steroidogenesis remains unclear as concentrations were obviously unrelated to follicular size. The remaining sulfonated steroids investigated were undetectable or only slightly exceeded LOQ in a minor proportion of samples. The results are clearly contrary to a role of sulfonated steroids as important precursors, intermediates or products of bovine ovarian steroidogenesis.

Intracrine androgen biosynthesis, metabolism and action revisited

Androgens play an important role in metabolic homeostasis and reproductive health in both men and women. Androgen signalling is dependent on androgen receptor activation, mostly by testosterone and 5α-dihydrotestosterone. However, the intracellular or intracrine activation of C₁₉ androgen precursors to active androgens in peripheral target tissues of androgen action is of equal importance. Intracrine androgen synthesis is often not reflected by circulating androgens but rather by androgen metabolites and conjugates. In this review we provide an overview of human C₁₉ steroid biosynthesis including the production of 11-oxygenated androgens, their transport in circulation and uptake into peripheral tissues. We conceptualise the mechanisms of intracrinology and review the intracrine pathways of activation and inactivation in selected human tissues. The contribution of liver and kidney as organs driving androgen inactivation and renal excretion are also highlighted. Finally, the importance of quantifying androgen metabolites and conjugates to assess intracrine androgen production is discussed.

Neurosteroid Transport in the Brain: Role of ABC and SLC Transporters

Neurosteroids, comprising pregnane, androstane, and sulfated steroids can alter neuronal excitability through interaction with ligand-gated ion channels and other receptors and have therefore a therapeutic potential in several brain disorders. They can be formed in brain cells or are synthesized by an endocrine gland and reach the brain by penetrating the blood–brain barrier (BBB). Especially sulfated steroids such as pregnenolone sulfate (PregS) and dehydroepiandrosterone sulfate (DHEAS) depend on transporter proteins to cross membranes. In this review, we discuss the involvement of ATP-binding cassette (ABC)- and solute carrier (SLC)-type membrane proteins in the transport of these compounds at the BBB and in the choroid plexus (CP), but also in the secretion from neurons and glial cells. Among the ABC transporters, especially BCRP (ABCG2) and several MRP/ABCC subfamily members (MRP1, MRP4, MRP8) are expressed in the brain and known to efflux conjugated steroids. Furthermore, several SLC transporters have been shown to mediate cellular uptake of steroid sulfates. These include members of the OATP/SLCO subfamily, namely OATP1A2 and OATP2B1, as well as OAT3 (SLC22A3), which have been reported to be expressed at the BBB, in the CP and in part in neurons. Furthermore, a role of the organic solute transporter OSTα-OSTβ (SLC51A/B) in brain DHEAS/PregS homeostasis has been proposed. This transporter was reported to be localized especially in steroidogenic cells of the cerebellum and hippocampus. To date, the impact of transporters on neurosteroid homeostasis is still poorly understood. Further insights are desirable also with regard to the therapeutic potential of these compounds.

Polymorphic Human Sulfotransferase 2A1 Mediates the Formation of 25-Hydroxyvitamin D3-3-O-Sulfate, a Major Circulating Vitamin D Metabolite in Humans

Metabolism of 25-hydroxyvitamin D₃ (25OHD₃) plays a central role in regulating the biologic effects of vitamin D in the body. Although cytochrome P450-dependent hydroxylation of 25OHD₃ has been extensively investigated, limited information is available on the conjugation of 25OHD₃ In this study, we report that 25OHD₃ is selectively conjugated to 25OHD₃-3-O-sulfate by human sulfotransferase 2A1 (SULT2A1) and that the liver is a primary site of metabolite formation. At a low (50 nM) concentration of 25OHD₃, 25OHD₃-3-O-sulfate was the most abundant metabolite, with an intrinsic clearance approximately 8-fold higher than the next most efficient metabolic route. In addition, 25OHD₃ sulfonation was not inducible by the potent human pregnane X receptor agonist, rifampicin. The 25OHD₃ sulfonation rates in a bank of 258 different human liver cytosols were highly variable but correlated with the rates of dehydroepiandrosterone sulfonation. Further analysis revealed a significant association between a common single nucleotide variant within intron 1 of SULT2A1 (rs296361; minor allele frequency = 15% in whites) and liver cytosolic SULT2A1 content as well as 25OHD₃-3-O-sulfate formation rate, suggesting that variation in the SULT2A1 gene contributes importantly to interindividual differences in vitamin D homeostasis. Finally, 25OHD₃-3-O-sulfate exhibited high affinity for the vitamin D binding protein and was detectable in human plasma and bile but not in urine samples. Thus, circulating concentrations of 25OHD₃-3-O-sulfate appear to be protected from rapid renal elimination, raising the possibility that the sulfate metabolite may serve as a reservoir of 25OHD₃ in vivo, and contribute indirectly to the biologic effects of vitamin D.

Metabolic profiling putatively identifies plasma biomarkers of male infertility using UPLC-ESI-IT-TOFMS

Male infertility has become a global health problem. Currently, the diagnosis of male infertility depends on the results of semen quality or requires invasive surgical intervention. The process is complex and time-consuming. Metabolomics is an emerging platform with unique advantages in disease diagnosis and pathological mechanism research. In this study, ultra-performance liquid chromatography-electrospray ionization-ion trap-time of flight mass spectrometry (UPLC-ESI-IT-TOFMS) combined with chemometrics methods was used to discover potential biomarkers of male infertility based on non-targeted plasma metabolomics. Plasma samples from healthy controls (HC, n = 43) and various types of infertile patients, i.e., patients having oligozoospermia (OS, n = 36), asthenospermia (AS, n = 56) and erectile dysfunction (ED, n = 45) were analyzed by UPLC-ESI-IT-TOFMS. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed. The results of OPLS-DA showed that HCs could be discriminated from infertile patients including OS (R² = 0.903, Q² = 0.617, AUC = 0.992), AS (R² = 0.985, Q² = 0.658, AUC = 0.999) or ED (R² = 0.942, Q² = 0.500, AUC = 0.998). Some potential biomarkers were successfully discovered by variable selection methods and variable important in the projection (VIP) in combination with the T-test. Statistical significance was set at p < 0.05; the Benjamini–Hochberg false discovery rate was used to reduce type 1 errors resulting from multiple comparisons. The identified biomarkers were associated with energy consumption, hormone regulation and antioxidant defenses in spermatogenesis. To elucidate the pathophysiology of male infertility, relative metabolic pathways were studied. It was found that male infertility is closely related to disturbed phospholipid metabolism, amino acid metabolism, steroid hormone biosynthesis metabolism, metabolism of fatty acids and products of carnitine acylation, and purine and pyrimidine metabolisms. Plasma metabolomics provides a novel strategy for the diagnosis of male infertility and offers a new insight to study pathogenesis mechanism.

Ultra-performance liquid chromatography-electrospray ionization-ion trap-time of flight mass spectrometry combined with chemometrics methods was used to discover potential biomarkers of male infertility based on untargeted plasma metabolomics.

The role of sulfated steroid hormones in reproductive processes

Sulfated steroid hormones, such as dehydroepiandrosterone sulfate or estrone-3-sulfate, have long been regarded as inactive metabolites as they cannot activate classical steroid receptors. Some of them are present in the blood circulation at quite high concentrations, but generally sulfated steroids exhibit low membrane permeation due to their hydrophilic properties. However, sulfated steroid hormones can actively be imported into specific target cells via uptake carriers, such as the sodium-dependent organic anion transporter SOAT, and, after hydrolysis by the steroid sulfatase (so-called sulfatase pathway), contribute to the overall regulation of steroid responsive organs. To investigate the biological significance of sulfated steroid hormones for reproductive processes in humans and animals, the research group "Sulfated Steroids in Reproduction" was established by the German Research Foundation DFG (FOR1369). Projects of this group deal with transport of sulfated steroids, sulfation of free steroids, desulfation by the steroid sulfatase, effects of sulfated steroids on steroid biosynthesis and membrane receptors as well as MS-based profiling of sulfated steroids in biological samples. This review and concept paper presents key findings from all these projects and provides a broad overview over the current research on sulfated steroid hormones in the field of reproduction.