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Non-alcoholic steatohepatitis demands multiple modes of action for robust therapeutic efficacy. Here the authors design and optimize a triple modulator of farnesoid X receptor and peroxisome proliferator-activated receptors α and δ that counteracts hepatic inflammation and reverses hepatic fibrosis in mice.

Thyroid hormones (THs) operate numerous physiological processes through modulation of the nuclear thyroid hormone receptors and several other proteins. We report direct activation of the nuclear peroxisome proliferator-activated receptor gamma (PPARγ) and retinoid X receptor (RXR) by classical and nonclassical THs as another molecular activity of THs. The T4 metabolite TETRAC was the most active TH on PPARγ with nanomolar potency and binding affinity. We demonstrate that TETRAC promotes PPARγ/RXR signaling in cell-free, cellular, and in vivo settings. Simultaneous activation of the heterodimer partners PPARγ and RXR resulted in high dimer activation efficacy. Compared to fatty acids as known natural ligands of PPARγ and RXR, TETRAC differs markedly in its molecular structure and the PPARγ-TETRAC complex revealed a distinctive binding mode of the TH. Our observations suggest a potential connection of TH and PPAR signaling through overlapping ligand recognition and may hold implications for TH and PPAR pharmacology.

[Image: see text] The nuclear retinoid X receptors (RXRs) are key ligand sensing transcription factors that serve as universal nuclear receptor heterodimer partners and are thus involved in numerous physiological processes. Therapeutic targeting of RXRs holds high potential but available RXR activators suffer from limited safety. Selectivity for RXR subtypes or for certain RXR heterodimers are promising strategies for safer RXR modulation. Here, we report systematic structure–activity relationship studies on biphenyl carboxylates as new RXR ligand chemotype. We discovered specific structural modifications that enhance potency on RXRs, govern subtype preference, and vary modulation of different RXR heterodimers. Fusion of these structural motifs enabled specific tuning of subtype preferential profiles with markedly improved potency. Our results provide further evidence that RXR subtype selective ligands can be designed and present a novel chemotype of RXR modulators that can be tuned for subtype and heterodimer preferences.

Automated computational analogue design and scoring can speed up hit-to-lead optimization and appears particularly promising in selective optimization of side-activities (SOSA) where possible analogue diversity is confined. Probing this concept, we employed the cysteinyl leukotriene receptor 1 (CysLT1 R) antagonist cinalukast as lead for which we discovered peroxisome proliferator-activated receptor α (PPARα) modulatory activity. We automatically generated a virtual library of close analogues and classified these roughly 8000 compounds for PPARα agonism and CysLT1 R antagonism using automated affinity scoring and machine learning. A computationally preferred analogue for SOSA was synthesized, and in vitro characterization indeed revealed a marked activity shift toward enhanced PPARα activation and diminished CysLT1 R antagonism. Thereby, this prospective application study highlights the potential of automating SOSA.

Designed multitarget ligands are a popular approach to generating efficient and safe drugs, and fragment‐based strategies have been postulated as a versatile avenue to discover multitarget ligand leads. To systematically probe the potential of fragment‐based multiple ligand discovery, we have employed a large fragment library for comprehensive screening on five targets chosen from proteins for which multitarget ligands have been successfully developed previously (soluble epoxide hydrolase, leukotriene A4 hydrolase, 5‐lipoxygenase, retinoid X receptor, farnesoid X receptor). Differential scanning fluorimetry served as primary screening method before fragments hitting at least two targets were validated in orthogonal assays. Thereby, we obtained valuable fragment leads with dual‐target engagement for six out of ten target combinations. Our results demonstrate the applicability of fragment‐based approaches to identify starting points for polypharmacological compound development with certain limitations., Thinking outside the pharmacophore: This study systematically investigates the potential of fragment‐based multiple ligand discovery. We employed a large fragment library for comprehensive screening on five targets and obtained valuable fragment leads with dual‐target engagement for six out of ten target combinations.

Nonalcoholic steatohepatitis (NASH) is considered as severe hepatic manifestation of the metabolic syndrome and has alarming global prevalence. The ligand-activated transcription factors farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR) δ have been validated as molecular targets to counter NASH. To achieve robust therapeutic efficacy in this multifactorial pathology, combined peripheral PPARδ-mediated activity and hepatic effects of FXR activation appear as a promising multitarget approach. We have designed a minimal dual FXR/PPARδ activator scaffold by rational fusion of pharmacophores derived from selective agonists. Our dual agonist lead compound exhibited weak agonism on FXR and PPARδ and was structurally refined to a potent and balanced FXR/PPARδ activator in a computer-aided fashion. The resulting dual FXR/PPARδ modulator comprises high selectivity over related nuclear receptors and activates the two target transcription factors in native cellular settings.

The fatty acid sensing nuclear receptor families retinoid X receptors (RXRs) and peroxisome proliferator-activated receptors (PPARs) hold therapeutic potential in neurodegeneration. Valuable pleiotropic activities of Wy14,643 in models of such conditions exceed its known PPAR agonistic profile. Here, we characterize the compound as an RXR agonist explaining the pleiotropic effects and report its systematic structure-activity relationship analysis with the discovery of specific molecular determinants driving activity on PPARs and RXRs. We have designed close analogues of the drug comprising selective and dual agonism on RXRs and PPARs that may serve as superior pharmacological tools to study the role and interplay of the nuclear receptors in various pathologies. A systematically optimized high potency RXR agonist revealed activity in vivo and active concentrations in brain. With its lack of RXR/liver X receptor-mediated side effects and superior profile compared to classical rexinoids, it establishes a new class of innovative RXR modulators to overcome key challenges in RXR targeting drug discovery.

Thyroid hormones (THs) operate numerous physiological processes through the nuclear thyroid hormone receptors and several other proteins. Here we report direct peroxisome proliferator-activated receptor gamma (PPARγ) and retinoid X receptor (RXR) activation by the T4 metabolite TETRAC at nanomolar affinity. We demonstrate that TETRAC is a highly active PPARγ agonist promoting PPARγ signaling in cell-free, cellular and in vivo settings suggesting that TETRAC and other THs are activators of PPARγ linking TH and PPAR signaling.

WY14643 - also known as pirinixic acid - is a versatile fatty acid mimetic that was originally developed as lipid lowering agent without knowledge of its molecular target. Various later studies discovered somewhat promiscuous activity of the compound on several receptors and enzymes. Pirinixic acid though never having reached clinical use was subjected to many in vivo studies and exerted beneficial effects in a variety of disease models. Areas covered: Inventions claiming the use of WY14643 for numerous indications ranging from the originally intended application in metabolic dysbalances over cancer and inflammation to some rare syndromes have been evaluated. Expert opinion: It is rather unlikely that pirinixic acid will gain relevance in treatment of metabolic diseases for which it was originally developed because more efficient and selective alternatives are available. Instead, several other claimed activities of the compound e.g. in inflammation, neurodegeneration and cancer seem very promising. However, some of the underlying studies are biased and for some effects of pirinixic acid, the molecular target and mode of action remain to be identified.