Discovery of the sEH Inhibitor Epoxykynin as a Potent Kynurenine Pathway Modulator.

Disease-related phenotypic assays enable unbiased discovery of novel bioactive small molecules and may provide novel insights into physiological systems and unprecedented molecular modes of action (MMOA). Herein, we report the identification and characterization of epoxykynin, a potent inhibitor of the soluble epoxide hydrolase (sEH). Epoxykynin was discovered by means of a cellular assay monitoring modulation of kynurenine (Kyn) levels in BxPC-3 cells upon stimulation with the cytokine interferon-γ (IFN-γ) and subsequent target identification employing affinity-based chemical proteomics. Increased Kyn levels are associated with immune suppression in the tumor microenvironment and, thus, the Kyn pathway and its key player indoleamine 2,3-dioxygenase 1 (IDO1) are appealing targets in immuno-oncology. However, targeting IDO1 directly has led to limited success in clinical investigations, demonstrating that alternative approaches to reduce Kyn levels are in high demand. We uncover a cross-talk between sEH and the Kyn pathway that may provide new opportunities to revert cancer-induced immune tolerance.

Prophylactic Administration of Mesenchymal Stromal Cells Does Not Prevent Arrested Lung Development in Extremely Premature-Born Non-Human Primates.

Premature birth is a leading cause of childhood morbidity and mortality and often followed by an arrest of postnatal lung development called bronchopulmonary dysplasia. Therapies using exogenous mesenchymal stromal cells (MSC) have proven highly efficacious in term-born rodent models of this disease, but effects of MSC in actual premature-born lungs are largely unknown. Here, we investigated thirteen non-human primates (baboons; Papio spp.) that were born at the limit of viability and given a single, intravenous dose of ten million human umbilical cord tissue-derived MSC per kilogram or placebo immediately after birth. Following two weeks of human-equivalent neonatal intensive care including mechanical ventilation, lung function testing and echocardiographic studies, lung tissues were analyzed using unbiased stereology. We noted that therapy with MSC was feasible, safe and without signs of engraftment when administered as controlled infusion over 15 minutes, but linked to adverse events when given faster. Administration of cells was associated with improved cardiovascular stability, but neither benefited lung structure, nor lung function after two weeks of extrauterine life. We concluded that a single, intravenous administration of MSC had no short- to mid-term lung-protective effects in extremely premature-born baboons, sharply contrasting data from term-born rodent models of arrested postnatal lung development and urging for investigations on the mechanisms of cell-based therapies for diseases of prematurity in actual premature organisms.

Designing a Small Fluorescent Inhibitor to Investigate Soluble Epoxide Hydrolase Engagement in Living Cells.

Soluble epoxide hydrolase (sEH) is a promising target for a number of inflammation-related diseases. In addition, inhibition of sEH has been shown to reduce neuroinflammation, which plays a critical role in the development of central nervous system (CNS) diseases such as Alzheimer's disease. In this study, we present the rational design of a small fluorescent sEH inhibitor. Starting from the clinical candidate GSK2256294A, we replaced the triazine moiety with the 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) fluorophore. The resulting fluorescent sEH inhibitor displayed excellent potency in an in vitro enzyme activity assay (IC50 < 2 nM). The developed inhibitor is applicable in a NanoBRET-based assay system suitable for studying sEH target engagement in living cells. Furthermore, the inhibitor can be used to visualize sEH in sEH-transfected HEK293 cells and in primary mouse astrocytes by fluorescence microscopy.

Stereoselective One-Pot Synthesis of Dihydropyrimido[2,1-a]isoindole-6(2H)-ones.

A diastereoselective one-pot synthesis of highly substituted dihydropyrimido[2,1-a]isoindole-6(2H)-ones containing three continuous stereocenters is reported. The reaction sequence is based on a hetero-Diels-Alder reaction between an enimide and a N-acylimine followed by an unprecedented Brønsted acid mediated rearrangement of an intermediate 5,6-dihydro-4H-1,3-oxazine to a pyrimido[2,1-a]isoindole.

Social experience modifies pheromone expression and mating behavior in male Drosophila melanogaster.

BACKGROUND: The social life of animals depends on communication between individuals. Recent studies in Drosophila melanogaster demonstrate that various behaviors are influenced by social interactions. For example, courtship is a social interaction mediated by pheromonal signaling that occurs more frequently during certain times of the day than others. In adult flies, sex pheromones are synthesized in cells called oenocytes and displayed on the surface of the cuticle. Although the role of Drosophila pheromones in sexual behavior is well established, little is known about the timing of these signals or how their regulation is influenced by the presence of other flies. RESULTS: We report that oenocytes contain functional circadian clocks that appear to regulate the synthesis of pheromones by controlling the transcription of desaturase1 (desat1), a gene required for production of male cuticular sex pheromones. Moreover, levels of these pheromones vary throughout the day in a pattern that depends on the clock genes and most likely also depends on the circadian control of desat1 in the oenocytes. To assess group dynamics, we manipulated the genotypic composition of social groups (single versus mixed genotypes). This manipulation significantly affects clock gene transcription both in the head and oenocytes, and it also affects the pattern of pheromonal accumulation on the cuticle. Remarkably, we found that flies in mixed social groups mate more frequently than do their counterparts in uniform groups. CONCLUSIONS: These results demonstrate that social context exerts a regulatory influence on the expression of chemical signals, while modulating sexual behavior in the fruit fly.