Identification of a human blood biomarker of pharmacological 11β-hydroxysteroid dehydrogenase 1 inhibition

BACKGROUND AND PURPOSE

11β-Hydroxysteroid dehydrogenase-1 (11β-HSD1) catalyses the oxoreduction of cortisone to cortisol, amplifying levels of active glucocorticoids. It is a pharmaceutical target in metabolic disease and cognitive impairments. 11β-HSD1 also converts some 7oxo-steroids to their 7β-hydroxy forms. A recent study in mice described the ratio of tauroursodeoxycholic acid (TUDCA)/tauro-7oxolithocholic acid (T7oxoLCA) as a biomarker for decreased 11β-HSD1 activity. The present study evaluates the equivalent bile acid ratio of glycoursodeoxycholic acid (GUDCA)/glyco-7oxolithocholic acid (G7oxoLCA) as a biomarker for pharmacological 11β-HSD1 inhibition in humans and compares it with the currently applied urinary (5α-tetrahydrocortisol + tetrahydrocortisol)/tetrahydrocortisone ((5αTHF + THF)/THE) ratio.

EXPERIMENTAL APPROACH

Bile acid profiles were analysed by ultra-HPLC tandem-MS in blood samples from two independent, double-blind placebo-controlled clinical studies of the orally administered selective 11β-HSD1 inhibitor AZD4017. The blood GUDCA/G7oxoLCA ratio was compared with the urinary tetrahydro-glucocorticoid ratio for ability to detect 11β-HSD1 inhibition.

KEY RESULTS

No significant alterations were observed in bile acid profiles following 11β-HSD1 inhibition by AZD4017, except for an increase of the secondary bile acid G7oxoLCA. The enzyme product/substrate ratio GUDCA/G7oxoLCA was found to be more reliable to detect 11β-HSD1 inhibition than the absolute G7oxoLCA concentration in both cohorts. Comparison of the blood GUDCA/G7oxoLCA ratio with the urinary (5αTHF + THF)/THE ratio revealed that both successfully detect 11β-HSD1 inhibition.

CONCLUSIONS AND IMPLICATIONS

11β-HSD1 inhibition does not cause major alterations in bile acid homeostasis. The GUDCA/G7oxoLCA ratio represents the first blood biomarker of pharmacological 11β-HSD1 inhibition and may replace or complement the urinary (5αTHF + THF)/THE ratio biomarker.

Is the 1mg-dexamethasone suppression test a precise marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas?

AIM

To analyze if the 1mg-dexamethasone suppression test (DST) is a reliable marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas (AIs).

METHODS

Cross-sectional study of patients with nonfunctioning adrenal incidentalomas (NFAIs, defined by cortisol post-DST ≤ 1.8 µg/dL) and patients with autonomous cortisol secretion (ACS, defined by cortisol post-DST > 1.8 µg/Dl). The urinary steroid profile (USP) was determined by gas chromatography coupled to mass spectrometry. Both groups were matched by sex, age and body mass index.

RESULTS

Forty-nine patients with AIs (25 with ACS and 24 with NFAI) were included. As a whole, AIs showed a high excretion of β-cortolone, tetrahydro-11-deoxycortisol (THS), α-cortolone, α-cortol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE). A positive yet modest correlation between post-DST cortisol and total excretion of glucocorticoid metabolites (r = 0.401, P = 0.004) was observed, with the stronger being observed with total THS (r = 0.548, P < 0.001) and THF (r = 0.441, P = 0.002). Some of the metabolites that were elevated in patients with AIs, were higher in patients with ACS-related comorbidities than in those without comorbidities. Post-DST cortisol showed a fair diagnostic accuracy for the prediction of ACS-related comorbidities (AUC 0.767 [95% CI 0.634-0.882]). However, post-DST diagnostic accuracy improved when combined with urinary cortisone, α-cortol, THS and serum DHEAS (0.853 [0.712‒0.954]).

CONCLUSION

The DST has a positive, but modest, correlation with urinary glucocorticoid excretion. Similarly, the diagnostic accuracy of the DST for the prediction of ACS-related comorbidities is only fair, but it may be improved if combined with the results of the USP and serum DHEAS.

SIGNIFICANCE STATEMENT

This is the first study aimed to evaluate if 1mg-dexamethasone suppression test (DST) is a reliable marker of glucocorticoid excess and cardiometabolic risk in patients with adrenal incidentalomas (AIs) and if urinary steroid profile was measured by GS-MS could improve such a prediction. We found a positive yet modest correlation between post-DST cortisol and total excretion of glucocorticoid metabolites, with the stronger being observed with total tetrahydro-11-deoxycortisol (THS) and tetrahydrocortisol. Post-DST cortisol showed a fair diagnostic accuracy for the prediction of ACS-related comorbidities (AUC 0.767). However, post-DST diagnostic accuracy improved when combined with urinary cortisone, α-cortol, THS and serum DHEAS (0.853).

High-resolution daily profiles of tissue adrenal steroids by portable automated collection

Rhythms are intrinsic to endocrine systems, and disruption of these hormone oscillations occurs at very early stages of the disease. Because adrenal hormones are secreted with both circadian and ultradian periods, conventional single-time point measurements provide limited information about rhythmicity and, crucially, do not provide information during sleep, when many hormones fluctuate from nadir to peak concentrations. If blood sampling is attempted overnight, then this necessitates admission to a clinical research unit, can be stressful, and disturbs sleep. To overcome this problem and to measure free hormones within their target tissues, we used microdialysis, an ambulatory fraction collector, and liquid chromatography-tandem mass spectrometry to obtain high-resolution profiles of tissue adrenal steroids over 24 hours in 214 healthy volunteers. For validation, we compared tissue against plasma measurements in a further seven healthy volunteers. Sample collection from subcutaneous tissue was safe, well tolerated, and allowed most normal activities to continue. In addition to cortisol, we identified daily and ultradian variation in free cortisone, corticosterone, 18-hydroxycortisol, aldosterone, tetrahydrocortisol and allo-tetrahydrocortisol, and the presence of dehydroepiandrosterone sulfate. We used mathematical and computational methods to quantify the interindividual variability of hormones at different times of the day and develop "dynamic markers" of normality in healthy individuals stratified by sex, age, and body mass index. Our results provide insight into the dynamics of adrenal steroids in tissue in real-world settings and may serve as a normative reference for biomarkers of endocrine disorders (ULTRADIAN, NCT02934399).

URINARY METABOLOMICS OF CENTRAL SEROUS CHORIORETINOPATHY

PURPOSE

To analyze the urinary metabolomic profile of central serous chorioretinopathy cases.

METHODS

In a cross-sectional study, 80 participants with central serous chorioretinopathy were compared with 80 age-matched and sex-matched controls. Urinary metabolites were measured using Metabolon's Discovery HD4 platform.

RESULTS

Of 1,031 metabolites total that were measured in urine samples, 53 were upregulated and 27 downregulated in central serous chorioretinopathy participants compared with controls. After exclusion of potentially confounding xenobiotics and bile compounds that could represent digestive processes, 14 metabolites were significantly higher and 12 metabolites were significantly lower in cases compared with controls. One upregulated metabolite (tetrahydrocortisol sulfate) is involved in the corticosteroid subpathway. The downregulated metabolites are unrelated to the identified corticosteroid subpathway.

CONCLUSION

The upregulation of urinary tetrahydrocortisol sulfate in central serous chorioretinopathy cases provides a precise molecular basis to further study the role of corticosteroids in producing choroidal venous congestion.

3Alpha-hydroxysteroid dehydrogenase from Pseudomonas testosteroni: kinetic properties with NAD and its thionicotinamide analogue

The kinetics of 3alpha-hydroxysteroid : NAD oxidoreductase (EC 1.1.1.50) from Pseudomonas testosteroni (ATCC 11996) have been investigated. The kinetic analysis based on initial activity measurements and product inhibition studies, indicates that the addition of substrate to the enzyme and the release of products from it, follows an obligatory order (ordered bi bi mechanism). The ability of the enzyme to utilize the thionicotinamide analogue of NAD (sNAD) as cofactor has been investigated using various 3alpha-hydroxysteroids from both the C19, C21, and C24 series. The results show that the reaction velocity with sNAD as the cofactor is generally lower than with NAD. The decrease, however, varies considerably, being negligible with some steroids such as litocholic acid and deoxycholic acid and very pronounced with other such as tetrahydrocortisol and tetrahydrocortisone. The introduction of an 11beta-hydroxy or an 11-oxo group into the steroid molecule significantly reduces the ability of the enzyme to attack the 3alpha-hydroxy group. No such effect could be seen when the 11-hydroxy group was in the alpha-position. The results also indicate that, whereas NAD can serve as cofactor for both the monomeric and the dimeric forms of the enzyme, sNAD only acts as cofactor for the monomeric form. Thus sNAD is a valuable tool for the study of the reversible, concentration-depenedent monomeric-dimeric transition of the 3alpha-hydroxysteroid dehydrogenase.