Hepatic reduction of the secondary bile acid 7-oxolithocholic acid is mediated by 11β-hydroxysteroid dehydrogenase 1

The oxidized bile acid 7-oxoLCA (7-oxolithocholic acid), formed primarily by gut micro-organisms, is reduced in human liver to CDCA (chenodeoxycholic acid) and, to a lesser extent, UDCA (ursodeoxycholic acid). The enzyme(s) responsible remained unknown. Using human liver microsomes, we observed enhanced 7-oxoLCA reduction in the presence of detergent. The reaction was dependent on NADPH and stimulated by glucose 6-phosphate, suggesting localization of the enzyme in the ER (endoplasmic reticulum) and dependence on NADPH-generating H6PDH (hexose-6-phosphate dehydrogenase). Using recombinant human 11β-HSD1 (11β-hydroxysteroid dehydrogenase 1), we demonstrate efficient conversion of 7-oxoLCA into CDCA and, to a lesser extent, UDCA. Unlike the reversible metabolism of glucocorticoids, 11β-HSD1 mediated solely 7-oxo reduction of 7-oxoLCA and its taurine and glycine conjugates. Furthermore, we investigated the interference of bile acids with 11β-HSD1-dependent interconversion of glucocorticoids. 7-OxoLCA and its conjugates preferentially inhibited cortisone reduction, and CDCA and its conjugates inhibited cortisol oxidation. Three-dimensional modelling provided an explanation for the binding mode and selectivity of the bile acids studied. The results reveal that 11β-HSD1 is responsible for 7-oxoLCA reduction in humans, providing a further link between hepatic glucocorticoid activation and bile acid metabolism. These findings also suggest the need for animal and clinical studies to explore whether inhibition of 11β-HSD1 to reduce cortisol levels would also lead to an accumulation of 7-oxoLCA, thereby potentially affecting bile acid-mediated functions.     

Effects of decomposition and storage conditions on the δ13C and δ15N isotope values of killer whale (Orcinus orca) skin and blubber tissues

Several different factors in the collection and preservation of whale skin and blubber samples were examined to determine their effect on the results obtained by stable nitrogen and carbon isotope (δ¹⁵N and δ¹³C) analysis. Samples of wet killer whale skin retained their original stable isotope values for up to 14 d at 4°C or lower. However, decomposition significantly changed the δ¹⁵N value within 3 d at 20°C. Storage at ?20°C was as effective as ?80°C for the preservation of skin and blubber samples for stable isotope analysis for at least a year. By contrast, once a skin sample had been freeze‐dried and lipid extracted, the stable isotope values did not change significantly when it was stored dry at room temperature for at least 12 mo. Preservation of whale skin samples for a month in DMSO‐salt solution, frozen or at room temperature, did not significantly change the δ¹⁵N and δ¹³C values of lipid extracted tissues, although the slight changes seen could influence results of a study if only small changes are expected.     

Antibodies to watch in 2016

The number of novel antibody therapeutics that received first marketing approvals in 2015 met expectations, with 6 (alirocumab (Praluent®), evolocumab (Repatha®), daratumumab (Darzalex®), dinutuximab (Unituxin®), idarucizumab (Praxbind®), mepolizumab (Nucala®)) granted first approvals as of mid-November*. Seven novel antibody therapeutics (begelomab, brodalumab, elotuzumab, ixekizumab, necitumumab, obiltoxaximab, reslizumab) are in regulatory review, and thus a similar number, if not more, are projected to gain first approvals in 2016. Commercial late-stage antibody therapeutics development exceeded expectations by increasing from 39 candidates in Phase 3 studies as of late 2014 to 53 as of late 2015. Of the 53 candidates, transitions to regulatory review by the end of 2016 are projected for 8 (atezolizumab, benralizumab, bimagrumab, durvalumab, inotuzumab ozogamicin, lebrikizumab, ocrelizumab, tremelimumab). Other "antibodies to watch" include 15 candidates (bavituximab, bococizumab, dupilumab, fasinumab, fulranumab, gevokizumab, guselkumab, ibalizumab, LY2951742, onartuzumab, REGN2222, roledumab, romosozumab, sirukumab, Xilonix) undergoing evaluation in Phase 3 studies that have estimated primary completion dates in 2016. As evidenced by the antibody therapeutics discussed in this perspective, the biopharmaceutical industry has a highly active late-stage clinical pipeline that may deliver numerous new products to the global market in the near future. *See Note added in proof for updates through December 31, 2015.     

Dual immunofluorescence studies of cortisone-induced thymic involution: evidence for a major cortical component to cortisone-resistant thymocytes

Cortisone-resistant thymocytes (CRT) have been used as the experimental equivalent of medullary thymocytes for the past 15 yr. Studies with CRT have provided evidence that the medullary population is similar to mature T cells in phenotype and function and may therefore be the major source of thymus emigrants. However, we have recently demonstrated that CRT differ from medullary thymocytes in their expression of the homing receptor molecule recognized by the monoclonal antibody MEL-14. Thus, many CRT express high levels of the MEL-14-defined homing receptor, whereas medullary thymocytes are MEL-14- to MEL-14lo. In normal adult mice, only 1 to 3% of thymocytes are MEL-14hi; these cells are located exclusively in the cortex and many are phenotypically and functionally mature. In this study we have used dual immunofluorescence techniques to further characterize those thymocytes resistant to cortisone treatment. Aside from being of mature phenotype with respect to expression of peanut agglutinin binding sites and the cell surface molecules H-2K, Ly-1, Lyt-2, and L3T4, CRT can be divided into MEL-14lo and MEL-14hi subpopulations, suggesting that they may actually be derived from both the medullary and the MEL-14hi cortical thymocyte subsets.