G protein-coupled receptors (GPCRs) continue to be important discovery targets for the treatment of type 2 diabetes mellitus (T2DM). Many GPCRs are directly involved in the development of insulin resistance and -cell dysfunction, and in the etiology of inflammation that can lead to obesity-induced T2DM. This review summarizes the current literature describing a number of well-validated GPCR targets, but also outlines several new and promising targets for drug discovery. We highlight the importance of understanding the role of these receptors in the disease pathology, and their basic pharmacology, which will pave the way to the development of novel pharmacological probes that will enable these targets to fulfill their promise for the treatment of these metabolic disorders.

Chronic inflammation is a component of numerous diseases including autoimmune, metabolic, neurodegenerative, and cancer. The discovery and characterization of specialized proresolving mediators (SPMs) critical to the resolution of inflammation, and their cognate G protein-coupled receptors (GPCRs) has led to a significant increase in the understanding of this physiological process. Approximately 20 ligands, including lipoxins, resolvins, maresins, and protectins, and 6 receptors (FPR2/ALX, GPR32, GPR18, chemerin 1 , BLT 1 , and GPR37) have been identified highlighting the complex and multilayered nature of resolution. Therapeutic efforts in targeting these receptors have proved challenging, with very few ligands apparently progressing through to preclinical or clinical development. To date, some knowledge gaps remain in the understanding of how the activation of these receptors, and their downstream signaling, results in efficient resolution via apoptosis, phagocytosis, and efferocytosis of polymorphonuclear leukocytes (mainly neutrophils) and macrophages. SPMs bind and activate multiple receptors (ligand poly-pharmacology), while most receptors are activated by multiple ligands (receptor pleiotropy). In addition, allosteric binding sites have been identified signifying the capacity of more than one ligand to bind simultaneously. These fundamental characteristics of SPM receptors enable alternative targeting strategies to be considered, including biased signaling and allosteric modulation. This review describes those ligands and receptors involved in the resolution of inflammation, and highlights the most recent clinical trial results. Furthermore, we describe alternative mechanisms by which these SPM receptors could be targeted, paving the way for the identification of new therapeutics, perhaps with greater efficacy and fidelity.

Here we describe the pharmacologic properties of a series of clinically relevant chemoattractant receptor-homologous molecules expressed on T-helper type 2 (CRTh2) receptor antagonists, including fevipiprant (NVP-QAW039 or QAW039), which is currently in development for the treatment of allergic diseases. min 21 and 0.048 minute 21 , respectively. Importantly, the k off of QAW039 (half-life 5 14.4 minutes) was .7-fold slower than the slowest reference compound tested, AZD-1981. In functional studies, QAW039 behaved as an insurmountable antagonist of PGD 2 -stimulated [35 S]-GTPgS activation, and its effects were not fully reversed by increasing concentrations of PGD 2 after an initial 15-minute incubation period. This behavior is consistent with its relatively slow dissociation from the human CRTh2 receptor.In contrast for the other ligands tested this time-dependent effect on maximal stimulation was fully reversed by the 15-minute time point, whereas QAW039's effects persisted for .180 minutes. All CRTh2 antagonists tested inhibited PGD 2 -stimulated human eosinophil shape change, but importantly QAW039 retained its potency in the whole-blood shape-change assay relative to the isolated shape change assay, potentially reflective of its relatively slower off rate from the CRTh2 receptor. QAW039 was also a potent inhibitor of PGD 2 -induced cytokine release in human Th2 cells. Slow CRTh2 antagonist dissociation could provide increased receptor coverage in the face of pathologic PGD 2 concentrations, which may be clinically relevant.