Unsymmetrical Phosphodiesters as GPR84 Antagonists with High Blood Exposure for the Treatment of Lung Inflammation

CuO nanoparticles elicit intestinal immunotoxicity in zebrafish based on intestinal microbiota dysbiosis

Copper II oxide nanoparticles (CuO NPs), a kind of widely used nanomaterial, have been detected in food and the environment, which has aroused widespread public concern. Recently, increasing data have suggested that intestinal microecology is closely related to immune homeostasis. However, the intestinal immunotoxicity induced by CuO NPs through intestinal microbiota is still unknown. Therefore, in this study, zebrafish were exposed to CuO NPs to explore intestinal immunotoxicity by evaluating physiological indicators, intestinal tissue injury, antioxidant enzyme activities, gene expression of immune factors, and changes in intestinal microbiota and its metabolites (short-chain fatty acids (SCFAs) and lipopolysaccharides (LPS)). The results revealed that the intestinal immunotoxicity of CuO NPs was mediated by the impact on intestinal microbiota and its metabolite levels. Specifically, changes were observed in the abundance of microbes that participated in the metabolism of SCFAs and LPS. The reduction in acetic acid, propionic acid and valeric acid upregulated GPR84 expression, and the decline in LPS levels further resulted in the suppression of the key immune regulatory pathways TLR4/MyD88/NF-κB, ultimately leading to intestinal immunotoxicity. This study would provide a scientific basis for the risk assessment of CuO NPs and a new perspective for research on the immunotoxicity of nanoparticles.

Taking advantage of the interaction between the sulfoxide and heme cofactor to develop indoleamine 2, 3-dioxygenase 1 inhibitors

Taking advantage of key interactions between sulfoxide and heme cofactor, we used the sulfoxide as the anchor functional group to develop two series of indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitors: 2-benzylsulfinylbenzoxazoles (series 1) and 2-phenylsulfinylbenzoxazoles (series 2). In vitro enzymatic screening shows that both series can inhibit the activity of IDO1 in low micromolar (series 1) or nanomolar (series 2) levels. They also show inhibitory selectivity between IDO1 and tryptophan 2, 3-dioxygenase 2. Interestingly, although series 1 is less potent IDO1 inhibitors of these two series, it exhibited stronger inhibitory activity toward kynurenine production in interferon-γ stimulated BxPC-3 cells. Enzyme kinetics and binding studies demonstrated that 2-sulfinylbenzoxazoles are non-competitive inhibitors of tryptophan, and they interact with the ferrous form of heme. These results demonstrated 2-sulfinylbenzoxazoles as type II IDO1 inhibitors. Furthermore, molecular docking studies supports the sulfoxide being of the key functional group that interacts with the heme cofactor. Compound 22 (series 1) can inhibit NO production in a concentration dependent manner in lipopolysaccharides (LPS) stimulated RAW264.7 cells, and can relieve pulmonary edema and lung injury in LPS induced mouse acute lung injury models.

Biased agonists of GPR84 and insights into biological control

GPR84 was first identified as an open reading frame encoding an orphan Class A G protein coupled receptor in 2001. Gpr84 mRNA is expressed in a limited number of cell types with the highest levels of expression being in innate immune cells, M1 polarised macrophages and neutrophils. The first reported ligands for this receptor were medium chain fatty acids with chain lengths between 9 and 12 carbons. Subsequently, a series of synthetic agonists that signal via the GPR84 receptor were identified. Radioligand binding assays and molecular modelling with site-directed mutagenesis suggest the presence of three ligand binding sites on the receptor, but the physiological agonist(s) of the receptor remain unidentified. Here, we review the effects of GPR84 agonists on innate immune cells following a series of chemical discoveries since 2001. The development of highly biased agonists has helped to probe receptor function in vitro, and the remaining challenge is to follow the effects of biased signalling to the physiological functions of innate immune cell types. LINKED ARTICLES: This article is part of a themed issue GPR84 Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.10/issuetoc.