S1P receptor mediated activity of FTY720 phosphate mimics

Various carboxylic acids, phosphonic acids, sulfonic acids, tetrazoles as well as sulfonylhydantoins were prepared as phosphate mimics of the chiral aminophosphate 1-P to act as agonists on the S1P1 receptor. It was found that amino phosphonates and amino carboxylates are potent S1P1 binders. Beta-amino acid 11 could be shown to reversibly reduce blood lymphocyte counts in rats after p.o. administration

One-step labelling of sphingolipids via a scrambling cross-metathesis reaction.

The alkyl chain in the backbone of sphingosine derivatives can be exchanged with functionalised (labelled) side chains in a single step under cross-metathesis reaction conditions

Synthesis of borondipyrromethene (BODIPY)-labeled sphingosine derivatives by cross-metathesis reaction.

A new efficient and flexible synthesis of fluorescently labeled sphingosine derivatives from commercially available Garner aldehyde (8) is described. For this, appropriate alkenylated borondipyrromethene (BODIPY) dyes were synthesized and used for the first time in a cross-metathesis reaction, the key step of the approach. The labeled sphingosines with appropriate chain length were accepted as substrates by sphingosine kinases (SPHKs), yielding the corresponding phosphorylated products. One of these derivatives (11d) was identified as the first reported selective substrate for SPHK-1

Structural States of RORγt: X-ray Elucidation of Molecular Mechanisms and Binding Interactions for Natural and Synthetic Compounds

The T-cell-specific retinoic acid receptor (RAR)-related orphan receptor-γ (RORγt) is a key transcription factor for the production of pro-inflammatory Th17 cytokines, which are implicated in the pathogenesis of autoimmune diseases. Over the years, several structurally diverse RORγt inverse agonists have been reported, but combining high potency and good physicochemical properties has remained a challenging task. We recently reported a new series of inverse agonists based on an imidazopyridine core with good physicochemical properties and excellent selectivity. Herein we report eight new X-ray crystal structures for different classes of natural and synthetic compounds, including examples selected from the patent literature. Analysis of their respective binding modes revealed insight into the molecular mechanisms that lead to agonism, antagonism, or inverse agonism. We report new molecular mechanisms for RORγt agonism and propose a separation of the inverse agonists into two classes: those that act via steric clash and those that act via other mechanisms (for the latter, co-crystallization with a co-activator peptide and helix 12 in the agonist position is still possible). For the non-steric clash inverse agonists, we propose a new mechanism (“water trapping”) which can be combined with other mechanisms (e.g., close contacts with H479). In addition, we compare the interactions made for selected compounds in the “back pocket” near S404 and in the “sulfate pocket” near R364 and R367. Taken together, these new mechanistic insights should prove useful for the design and optimization of further RORγt modulators

Optimizing a weakly binding fragment into a potent RORγt inverse agonist with efficacy in an in vivo inflammation model

The transcription factor RORγt is an attractive drug-target due to its role in the differentiation of IL-17 producing Th17 cells that play a critical role in the etiopathology of several autoimmune diseases. Identification of starting points for RORγt inverse agonists with good properties has been a challenge. We report the identification of a fragment hit which was converted into a potent inverse agonist through fragment optimization, growing and merging efforts. Further analysis of the binding mode revealed that inverse agonism was achieved by an unusual mechanism. In contrast to other reported inverse agonists, there is no direct interaction or displacement of helix 12. Nevertheless, compound 9 proved to be efficacious in a delayed-type hypersensitivity (DTH) inflammation model in rats

Discovery of novel pyrrolidineoxy-substituted heteroaromatics as potent and selective PI3K delta inhibitors with improved physicochemical properties

In the recent years, PI3Kδ has emerged as a promising target for the treatment of B- and T-cell mediated inflammatory diseases. A detailed analysis of our previously reported 4,6-diaryl quinazoline PI3Kδ inhibitor series revealed that the activity in cellular assays was logP dependent, with an optimum logP range between 2-3. We discovered novel analogues in this lipophilicity space that feature a chiral pyrrolidineoxy-group instead of one of the aromatic rings. Compared to 4,6-diaryl quinazolines, these Fsp3 enriched derivatives retain potency and selectivity towards PI3Kδ, yet their permeability profile is improved and molecular weight as well as PSA are reduced. These modifications offer additional possibilities for derivative generation in a good physicochemical property space and thus increase the chances to identify a clinical candidate

G-Protein-coupled Bile Acid Receptor 1 (GPBAR1, TGR5) agonists reduce the production of pro-inflammatory cytokines and stabilize the alternative macrophage phenotype

GPBAR1 (also known as TGR5) is a G protein-coupled receptor (GPCR), which triggers intracellular signals upon ligation by various bile acids. The receptor has been studied mainly for its function in energy expenditure and glucose homeostasis, and there is little information on the role of GPBAR1 in the context of inflammation. After a high-throughput screening campaign, we identified isonicotinamides exemplified by compound 3 as non-steroidal GPBAR1 agonists. We optimized this series to potent derivatives that are active on both human and murine GPBAR1. These agonists inhibited the secretion of the pro-inflammatory cytokines TNF-alpha and IL-12, but not the anti-inflammatory IL-10 in primary human monocytes. These effects translate in vivo, as compound 15 inhibits LPS induced TNF-alpha and IL-12 release in mice. The response was GPBAR1 dependent, as demonstrated using knockout mice. Furthermore, agonism of GPBAR1 stabilized the phenotype of the alternative, non-inflammatory, M2-like type cells during differentiation of monocytes into macrophages. Overall, our results illustrate an important regulatory role for GPBAR1 agonists as controllers of inflammation

Optimizing a Weakly Binding Fragment into a Potent RORγt Inverse Agonist with Efficacy in an in Vivo Inflammation Model

The transcription factor RORγt is an attractive drug-target due to its role in the differentiation of IL-17 producing Th17 cells that play a critical role in the etiopathology of several autoimmune diseases. Identification of starting points for RORγt inverse agonists with good properties has been a challenge. We report the identification of a fragment hit and its conversion into a potent inverse agonist through fragment optimization, growing and merging efforts. Further analysis of the binding mode revealed that inverse agonism was achieved by an unusual mechanism. In contrast to other reported inverse agonists, there is no direct interaction or displacement of helix 12 observed in the crystal structure. Nevertheless, compound <b>9</b> proved to be efficacious in a delayed-type hypersensitivity (DTH) inflammation model in rats

Retinoic-acid-orphan-receptor C inhibition suppresses Th17 cells and induces thymic aberrations

Retinoic-acid-orphan-receptor-C (RORC) is a master regulator of Th17 cells which are pathogenic in several autoimmune diseases. Genetic Rorc deficiency in mice, while preventing autoimmunity, causes early lethality due to metastatic thymic T cell lymphomas. We sought to determine whether pharmacological RORC inhibition could be an effective and safe therapy for autoimmune diseases by evaluating its effects on Th17 cell functions and intrathymic T cell development. RORC inhibitors effectively inhibited Th17 differentiation and IL-17A production, and delayed-type hypersensitivity reactions. In vitro, RORC inhibitors induced apoptosis, as well as Bcl2l1 and BCL2L1 mRNA downregulation, in mouse and nonhuman primate thymocytes, respectively. Chronic, 13-week RORC inhibitor treatment in rats caused progressive thymic alterations in all analyzed rats similar to those in Rorc-deficient mice prior to T cell lymphoma development. One rat developed thymic cortical hyperplasia with preneoplastic features, including increased mitosis and reduced IKAROS expression, albeit without skewed T cell clonality. In summary, pharmacological inhibition of RORC not only blocks Th17 cell development and related cytokine production, but also recapitulates thymic aberrations seen in Rorc-deficient mice. While RORC inhibition may offer an effective therapeutic principle for Th17-mediated diseases, T cell lymphoma with chronic therapy remains an apparent risk

Retinoic-acid-orphan-receptor-C inhibition suppresses Th17 cells and induces thymic aberrations

Retinoic-acid-orphan-receptor-C (RORC) is a master regulator of Th17 cells, which are pathogenic in several autoimmune diseases. Genetic Rorc deficiency in mice, while preventing autoimmunity, causes early lethality due to metastatic thymic T cell lymphomas. We sought to determine whether pharmacological RORC inhibition could be an effective and safe therapy for autoimmune diseases by evaluating its effects on Th17 cell functions and intrathymic T cell development. RORC inhibitors effectively inhibited Th17 differentiation and IL-17A production, and delayed-type hypersensitivity reactions. In vitro, RORC inhibitors induced apoptosis, as well as Bcl2l1 and BCL2L1 mRNA downregulation, in mouse and nonhuman primate thymocytes, respectively. Chronic, 13-week RORC inhibitor treatment in rats caused progressive thymic alterations in all analyzed rats similar to those in Rorc-deficient mice prior to T cell lymphoma development. One rat developed thymic cortical hyperplasia with preneoplastic features, including increased mitosis and reduced IKAROS expression, albeit without skewed T cell clonality. In summary, pharmacological inhibition of RORC not only blocks Th17 cell development and related cytokine production, but also recapitulates thymic aberrations seen in Rorc-deficient mice. While RORC inhibition may offer an effective therapeutic principle for Th17-mediated diseases, T cell lymphoma with chronic therapy remains an apparent risk