On the biosynthesis of specialized pro-resolving mediators in human neutrophils and the influence of cell integrity.

Neutrophils are key players in inflammation initiation and resolution. Little attention has been paid to the detailed biosynthesis of specialized pro-resolving mediators (SPM) in these cells. We investigated SPM formation in human polymorphonuclear leukocytes (PMNL), in broken PMNL preparations and recombinant human 5-lipoxygenase (5-LO) supplemented with the SPM precursor lipids 15-Hydroxyeicosatetraenoic acid (15-HETE), 18-Hydroxyeicosapentaenoic acid (18-HEPE) or 17-Hydroxydocosahexaenoic acid (17-HDHA). In addition, the influence of 5-LO activating protein (FLAP) inhibition on SPM formation in PMNL was assessed. Intact human PMNL preferred ARA over DHA for lipid mediator formation. In contrast, in incubations supplemented with the SPM precursor lipids DHA-derived 17-HDHA was preferred over 15-HETE and 18-HEPE. SPM formation in the cells was dominated by 5(S),15(S)-diHETE (800 pmol/20 mio cells) and Resolvin D5 (2300 pmol/20 mio cells). Formation of lipoxins (<10 pmol/20 mio cells), E-series (<70 pmol/20 mio cells) and other D-series resolvins (<20 pmol/20 mio cells) was low and only detected after addition of the precursor lipids. Upon destruction of cell integrity, formation of lipoxins and 5(S),15(S)-diHETE increased while formation of 17-HDHA- and 18-HEPE-derived SPMs was attenuated. Recombinant 5-LO did not accept the precursors for SPM formation and FLAP inhibition prevented the formation of the 5-LO-dependent SPMs. Together with the data on FLAP inhibition our results point to unknown factors that control SPM formation in human neutrophils and also render lipoxin and 5(S),15(S)-diHETE formation independent of membrane association and FLAP when cellular integrity is destroyed.

l-Thyroxin and the Nonclassical Thyroid Hormone TETRAC Are Potent Activators of PPARγ.

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.

Urate transporter inhibitor lesinurad is a selective peroxisome proliferator-activated receptor gamma modulator (sPPARγM) in vitro.

Gout is the most common arthritic disease in human but was long neglected and therapeutic options are not satisfying. However, with the recent approval of the urate transporter inhibitor lesinurad, gout treatment has experienced a major innovation. Here we show that lesinurad possesses considerable modulatory potency on peroxisome proliferator-activated receptor γ (PPARγ). Since gout has a strong association with metabolic diseases such as type 2 diabetes, this side-activity appears as very valuable contributing factor to the clinical efficacy profile of lesinurad. Importantly, despite robustly activating PPARγ in vitro, lesinurad lacked adipogenic activity, which seems due to differential coactivator recruitment and is characterized as selective PPARγ modulator (sPPARγM).

Boosting Anti-Inflammatory Potency of Zafirlukast by Designed Polypharmacology.

Multitarget design offers access to bioactive small molecules with potentially superior efficacy and safety. Particularly multifactorial chronic inflammatory diseases demand multiple pharmacological interventions for stable treatment. By minor structural changes, we have developed a close analogue of the cysteinyl-leukotriene receptor antagonist zafirlukast that simultaneously inhibits soluble epoxide hydrolase and activates peroxisome proliferator-activated receptor γ. The triple modulator exhibits robust anti-inflammatory activity in vivo and highlights the therapeutic potential of designed multitarget agents.

A Dual Modulator of Farnesoid X Receptor and Soluble Epoxide Hydrolase To Counter Nonalcoholic Steatohepatitis.

Nonalcoholic steatohepatitis arising from Western diet and lifestyle is characterized by accumulation of fat in liver causing inflammation and fibrosis. It evolves as serious health burden with alarming incidence, but there is no satisfying pharmacological therapy to date. Considering the disease's multifactorial nature, modulation of multiple targets might provide superior therapeutic efficacy. In particular, farnesoid X receptor (FXR) activation that revealed antisteatotic and antifibrotic effects in clinical trials combined with inhibition of soluble epoxide hydrolase (sEH) as anti-inflammatory strategy promises synergies. To exploit this dual concept, we developed agents exerting partial FXR agonism and sEH inhibitory activity. Merging known pharmacophores and systematic exploration of the structure-activity relationship on both targets produced dual modulators with low nanomolar potency. Extensive in vitro characterization confirmed high dual efficacy in cellular context combined with low toxicity, and pilot in vivo data revealed favorable pharmacokinetics as well as engagement on both targets in vivo.