Construction of 3D models of the CYP11B family as a tool to predict ligand binding characteristics

Aldosterone is synthesised by aldosterone synthase (CYP11B2). CYP11B2 has a highly homologous isoform, steroid 11β-hydroxylase (CYP11B1), which is responsible for the biosynthesis of aldosterone precursors and glucocorticoids. To investigate aldosterone biosynthesis and facilitate the search for selective CYP11B2 inhibitors, we constructed three-dimensional models for CYP11B1 and CYP11B2 for both human and rat. The models were constructed based on the crystal structure of Pseudomonas Putida CYP101 and Oryctolagus Cuniculus CYP2C5. Small steric active site differences between the isoforms were found to be the most important determinants for the regioselective steroid synthesis. A possible explanation for these steric differences for the selective synthesis of aldosterone by CYP11B2 is presented. The activities of the known CYP11B inhibitors metyrapone, R-etomidate, R-fadrazole and S-fadrazole were determined using assays of V79MZ cells that express human CYP11B1 and CYP11B2, respectively. By investigating the inhibitors in the human CYP11B models using molecular docking and molecular dynamics simulations we were able to predict a similar trend in potency for the inhibitors as found in the in vitro assays. Importantly, based on the docking and dynamics simulations it is possible to understand the enantioselectivity of the human enzymes for the inhibitor fadrazole, the R-enantiomer being selective for CYP11B2 and the S-enantiomer being selective for CYP11B1

Endoscopic ultrasound-guided gastroenterostomy versus duodenal stenting for malignant gastric outlet obstruction: An international, multicenter, propensity score-matched comparison

Background  Endoscopic duodenal stenting is the current standard treatment for malignant gastric outlet obstruction (GOO) in patients with limited life expectancy. However, duodenal stenting is prone to stent dysfunction. Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) is a novel technique with potentially superior stent patency. We compared clinical success, safety, and stent dysfunction of EUS-GE and duodenal stenting in patients with malignant GOO using propensity score matching. Methods  This international, multicenter, retrospective study analyzed consecutive patients undergoing EUS-GE or duodenal stenting for GOO between 2015 and 2021 in three European centers. Primary outcomes were clinical success (GOO scoring system [GOOSS] ≥ 2) and stent dysfunction (GOOSS ≤ 1 after initial clinical success). A propensity score matching (1:1) analysis was performed using age, sex, underlying disease, disease stage, ascites, and peritoneal carcinomatosis as variables. Results  214 patients underwent EUS-GE (n = 107) or duodenal stenting (n = 107). After propensity score matching, 176 patients were matched and compared. Technical success rates for EUS-GE and duodenal stenting were 94 % (95 %CI 89 %-99 %) vs. 98 % (95 %CI 95 %-100 %), respectively (P  = 0.44). Clinical success rates were 91 % (95 %CI 85 %-97 %) vs. 75 % (95 %CI 66 %-84 %; P  = 0.008). Stent dysfunction occurred in 1 % (95 %CI 0-4 %) vs. 26 % (95 %CI 15 %-37 %) of patients (P  < 0.001). Adverse event rate was 10 % (95 %CI 4 %-17 %) vs. 21 % (95 %CI 12 %-29 %; P  = 0.09). Conclusion  EUS-GE had higher clinical success and lower stent dysfunction, with similar safety, compared with duodenal stenting, suggesting that EUS-GE may be preferred over duodenal stenting in patients with malignant GOO

Endoscopic ultrasound-guided gastroenterostomy versus duodenal stenting for malignant gastric outlet obstruction: An international, multicenter, propensity score-matched comparison

Background  Endoscopic duodenal stenting is the current standard treatment for malignant gastric outlet obstruction (GOO) in patients with limited life expectancy. However, duodenal stenting is prone to stent dysfunction. Endoscopic ultrasound-guided gastroenterostomy (EUS-GE) is a novel technique with potentially superior stent patency. We compared clinical success, safety, and stent dysfunction of EUS-GE and duodenal stenting in patients with malignant GOO using propensity score matching. Methods  This international, multicenter, retrospective study analyzed consecutive patients undergoing EUS-GE or duodenal stenting for GOO between 2015 and 2021 in three European centers. Primary outcomes were clinical success (GOO scoring system [GOOSS] ≥ 2) and stent dysfunction (GOOSS ≤ 1 after initial clinical success). A propensity score matching (1:1) analysis was performed using age, sex, underlying disease, disease stage, ascites, and peritoneal carcinomatosis as variables. Results  214 patients underwent EUS-GE (n = 107) or duodenal stenting (n = 107). After propensity score matching, 176 patients were matched and compared. Technical success rates for EUS-GE and duodenal stenting were 94 % (95 %CI 89 %-99 %) vs. 98 % (95 %CI 95 %-100 %), respectively (P  = 0.44). Clinical success rates were 91 % (95 %CI 85 %-97 %) vs. 75 % (95 %CI 66 %-84 %; P  = 0.008). Stent dysfunction occurred in 1 % (95 %CI 0-4 %) vs. 26 % (95 %CI 15 %-37 %) of patients (P  < 0.001). Adverse event rate was 10 % (95 %CI 4 %-17 %) vs. 21 % (95 %CI 12 %-29 %; P  = 0.09). Conclusion  EUS-GE had higher clinical success and lower stent dysfunction, with similar safety, compared with duodenal stenting, suggesting that EUS-GE may be preferred over duodenal stenting in patients with malignant GOO

Application of a Ligand-Based Theoretical Approach to Derive Conversion Paths and Ligand Conformations in CYP11B2-Mediated Aldosterone Formation

The biosynthesis of the mineralocorticoid hormone aldosterone involves a multistep hydroxylation of 11-deoxycorticosterone at the 11- and 18-positions, resulting in the formation of corticosterone and 18-hydroxycorticosterone, the final precursor of aldosterone. Two members of the cytochrome P450 11B family, CYP11B1 and CYP11B2, are known to catalyze these 11- and 18-hydroxylations, however, only CYP11B2 can oxidize 18-hydroxycorticosterone to aldosterone. It is unknown what sequence of hydroxylations leads to the formation of 18-hydroxycorticosterone. In this study we have investigated which of the possible conversion paths towards formation of 18-hydroxycorticosterone and aldosterone are most likely from the ligand perspective. Therefore, we combined quantum mechanical investigations on the steroid conformations of 11-deoxycorticosterone and its ensuing reaction intermediates with Fukui indices calculations to predict the reactivity of their carbon atoms for an attack by the iron-oxygen species. Both F(-) and F(0) were calculated to account for different mechanisms of substrate conversion. We show which particular initial conformations of 11-deoxycorticosterone and which conversion paths are likely to result in the successful synthesis of aldosterone, and thereby may be representative for the mechanism of aldosterone biosynthesis by CYP11B2. Moreover, we found that the most likely path for aldosterone synthesis coincides with the substrate conformation proposed in an earlier publication (Ref. (2)). To summarize, we show that on a theoretical and strictly ligand-directed basis only a limited number of reaction paths in the conversion of 11-deoxycorticosterone to aldosterone is possible. Despite its theoretical nature, this knowledge may help to understand the catalytic function of CYP11B1 and CYP11B2

Synthesis, Biological Evaluation, and Molecular Modeling of 1-Benzyl-1H-imidazoles as Selective Inhibitors of Aldosterone Synthase (CYP11B2)

Reducing aldosterone action is beneficial in various major diseases such as heart failure. Currently, flits is achieved with mineralocorticoid receptor antagonists, however, aldosterone synthase (CYP11B2) inhibitors may offer a promising alternative. In this study, WC used three-dimensional modeling of CYP11B2 to model the binding modes of the natural substrate 18-hydroxycorticosterone and the recently published CYP11B2 inhibitor R-fadrozole as a rational guide to design 44 structurally simple and achiral 1-benzyl-1H-imidazoles. Their syntheses, in vitro inhibitor potencies, and in silico docking are described. Some promising CYP11B2 inhibitors were identified, with our novel lead MOERAS115 (4-((5-phenyl-1H-imidazol-1-y1)methyl)benzonitrile) displaying an IC50 for CYP11B2 of 1.7 nM, and a CYP11B2 (versus CYP11B1) selectivity of 16.5, comparable to R-fadrozole (IC50 for CYP11B2 6.0 nM. Selectivity 19.8). Molecular docking of the Inhibitors in the models enabled us to generate posthoc hypotheses oil their binding modes, providing a Valuable basis for future Studies and further design of CYP11B2 inhibitors

Long-term efficacy of metal versus plastic stents in inoperable perihilar cholangiocarcinoma; a multicenter retrospective propensity score matched comparison

Background: For palliative drainage of inoperable perihilar cholangiocarcinoma (pCCA) uncovered metal stents are preferred over plastic stents. However, there is a lack of data on re-interventions at the long-term. The aim is to evaluate the potential difference in the number of re-interventions in patients surviving at least 6 months. Methods: Retrospective study including patients with pCCA who underwent plastic stent placement(s) or had metal stent(s) in situ for at least 6 months. The primary outcome was the number of re-interventions per patient-year. A propensity score matching (1:1) analysis was performed using age, Bismuth classification, reason for inoperability, pathological confirmation, systemic therapy and initial approach (endoscopic vs percutaneous). Results: Patients in the metal stent group (n = 87) underwent fewer re-interventions compared with the plastic stent group (n = 40) (3.0 vs. 4.7 per patient-year; IRR, 0.64; 95% CI, 0.47 to 0.88). When only non-elective re-interventions were included, there was no significant difference (2.1 vs. 2.7; IRR, 0.76; 95% CI, 0.55 to 1.08). Results were similar in the propensity score-matched dataset. Conclusions: This study shows that, also in patients with inoperable pCCA who survive at least 6 months, placement of metal stent(s) leads to fewer re-interventions in comparison with plastic stents