Assessment of a novel β2-adrenoceptor agonist, trantinterol, for interference with human liver cytochrome P450 enzymes activities

CGINet: graph convolutional network-based model for identifying chemical-gene interaction in an integrated multi-relational graph

Background

Elucidation of interactive relation between chemicals and genes is of key relevance not only for discovering new drug leads in drug development but also for repositioning existing drugs to novel therapeutic targets. Recently, biological network-based approaches have been proven to be effective in predicting chemical-gene interactions.

Results

We present CGINet, a graph convolutional network-based method for identifying chemical-gene interactions in an integrated multi-relational graph containing three types of nodes: chemicals, genes, and pathways. We investigate two different perspectives on learning node embeddings. One is to view the graph as a whole, and the other is to adopt a subgraph view that initial node embeddings are learned from the binary association subgraphs and then transferred to the multi-interaction subgraph for more focused learning of higher-level target node representations. Besides, we reconstruct the topological structures of target nodes with the latent links captured by the designed substructures. CGINet adopts an end-to-end way that the encoder and the decoder are trained jointly with known chemical-gene interactions. We aim to predict unknown but potential associations between chemicals and genes as well as their interaction types.

Conclusions

We study three model implementations CGINet-1/2/3 with various components and compare them with baseline approaches. As the experimental results suggest, our models exhibit competitive performances on identifying chemical-gene interactions. Besides, the subgraph perspective and the latent link both play positive roles in learning much more informative node embeddings and can lead to improved prediction.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Identification of the cytochrome P450 enzymes involved in the oxidative metabolism of trantinterol using ultra high-performance liquid chromatography coupled with tandem mass spectrometry

Trantinterol is a novel β₂-adrenoceptor agonist used for the treatment of asthma. This study aimed to identify the cytochrome P450 enzymes responsible for the metabolism of trantinterol to form 4-hydroxylamine trantinterol (M1) and tert-butyl hydroxylated trantinterol (M2), which was achieved using the chemical inhibition study, followed by the metabolism study of trantinterol in a panel of recombinant CYPs, as well as the kinetic study with the appropriate cDNA-expressed P450 enzymes. A highly selective and sensitive ultra high-performance liquid chromatography tandem mass spectrometry method was developed and validated for the simultaneous determination of M1 and M2. The inhibition study suggested that CYP2C19 and CYP3A4/5 were involved in the formation of M1 and M2, and CYP2D6 only contributed to the formation of M1. Assays with cDNA-expressed CYP enzymes further showed that the relative contributions of P450 isoforms were 2C19 > 3A4 > 2D6 > 2E1 for the formation of M1, and 3A4 > 2C19 > 2D6 for the formation of M2. The enzyme kinetic analysis was then performed in CYP2C19, CYP2D6 and CYP3A4. The kinetic parameters were determined and normalized with respect to the human hepatic microsomal P450 isoform concentrations. All the results support the conclusion that CYP3A4 and CYP2C19 are the major enzymes responsible for formation of M1 and M2, while CYP2D6 and CYP2E1 also engaged to a lesser degree. The results imply that potential drug–drug interactions may be noticed when trantinterol is used with CYP2C19 and CYP3A4 inducers or inhibitors, and we should pay attention to this phenomenon in clinical study.

The first report on the characterization of the main CYP450 enzymes and the kinetic study involved in trantinterol metabolism.

In vitro metabolism of 4, 5-dimethoxycanthin-6-one by human liver microsomes and its inhibition on human CYP1A2

AIMS

P. quassioides is a traditional Chinese medicine used for the treatment of gastroenteritis, snakebite, infection and hypertension in China. 4, 5-dimethoxycanthin-6-one is one of the main active canthinone alkaloid isolated from P. quassioides. The aim of this work was to identify the cytochrome P (CYP) 450 enzymes responsible for the metabolism of 4, 5-dimethoxycanthin-6-one (DCO) and to evaluate the inhibitory effect of DCO on CYP activity in human liver microsomes (HLM) in vitro.

MATERIALS AND METHODS

the CYP isoforms responsible for DCO metabolism and the inhibitory effects of DCO on CYP activity was studied in HLM.

KEY FINDINGS

The in vitro metabolic enzyme of DCO was CYP3A4 (mediated the formation of metabolites M1-M5), CYP2C9 (mediated the formation of metabolites M1-M3, M6 and M8) and CYP2D6 (mediated the formation of metabolite M3) in HLM. Furthermore, the present work found that DCO uncompetitively inhibited CYP1A2-mediated phenacetin O-deethylation with an IC₅₀ value of 1.7μM and a Ki value of 2.6μM.

SIGNIFICANCE

The results suggested that the metabolic interaction should be existed when the substrate drugs of CYP1A2 were co-administered with DCO or traditional Chinese medicine containing it, such as the extract of P. quassioides and Kumu injection.

Trantinterol, a novel β2-adrenoceptor agonist, noncompetitively inhibits P-glycoprotein function in vitro and in vivo

P-glycoprotein (P-gp)-mediated drug-drug interactions are important factors causing adverse effects of drugs in clinical use. The aim of this study was to determine whether trantinterol (also known as SPFF), a novel β2-adrenoceptor agonist, was a P-gp inhibitor or substrate. The results showed that trantinterol was not a substrate of P-gp but increased rhodamine 123 (Rho 123) uptake by MDCK-MDR1 cells and decreased the efflux transport of both Rho 123 and cyclosporine A (CsA) in bidirectional transport studies across MDCK-MDR1 cell monolayers. This suggested that trantinterol was a P-gp inhibitor but not a P-gp substrate. The mechanism of inhibition was investigated in the P-gp-Glo assay system, where it was found that trantinterol inhibited P-gp ATPase activity in a dose-dependent manner. A subsequent study using the antibody binding assay with the conformation-sensitive P-gp-specific antibody UIC2 confirmed that trantinterol decreased UIC2 binding at 10 μM in contrast to the competitive inhibitor, verapamil. This suggested that trantinterol was a noncompetitive inhibitor of P-gp. Finally, a pharmacokinetic study in rat showed that trantinterol significantly increased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) of digoxin and paclitaxel (PAC), and the Cmax of cyclosporine A (CsA). In summary, trantinterol is a potent noncompetitive P-gp inhibitor which may increase the bioavailability of other P-gp substrate drugs coadministered with it.

Macrophage heterogeneity in liver injury and fibrosis

Hepatic macrophages are central in the pathogenesis of chronic liver injury and have been proposed as potential targets in combatting fibrosis. Recent experimental studies in animal models revealed that hepatic macrophages are a remarkably heterogeneous population of immune cells that fulfill diverse functions in homeostasis, disease progression, and regression from injury. These range from clearance of pathogens or cellular debris and maintenance of immunological tolerance in steady state conditions; central roles in initiating and perpetuating inflammation in response to injury; promoting liver fibrosis via activating hepatic stellate cells in chronic liver damage; and, finally, resolution of inflammation and fibrosis by degradation of extracellular matrix and release of anti-inflammatory cytokines. Cellular heterogeneity in the liver is partly explained by the origin of macrophages. Hepatic macrophages can either arise from circulating monocytes, which are recruited to the injured liver via chemokine signals, or from self-renewing embryo-derived local macrophages, termed Kupffer cells. Kupffer cells appear essential for sensing tissue injury and initiating inflammatory responses, while infiltrating Ly-6C(+) monocyte-derived macrophages are linked to chronic inflammation and fibrogenesis. In addition, proliferation of local or recruited macrophages may possibly further contribute to their accumulation in injured liver. During fibrosis regression, monocyte-derived cells differentiate into Ly-6C (Ly6C, Gr1) low expressing 'restorative' macrophages and promote resolution from injury. Understanding the mechanisms that regulate hepatic macrophage heterogeneity, either by monocyte subset recruitment, by promoting restorative macrophage polarization or by impacting distinctive macrophage effector functions, may help to develop novel macrophage subset-targeted therapies for liver injury and fibrosis.

In vivo and in vitro metabolism of a novel β2-adrenoceptor agonist, trantinterol: metabolites isolation and identification by LC-MS/MS and NMR

Trantinterol is a novel β(2)-adrenoceptor agonist used for the treatment of asthma. The aim of this study is to identify the metabolites of trantinterol using liquid chromatography tandem mass spectrometry (LC-MS/MS), to isolate the main metabolites, and confirm their structures by nuclear magnetic resonance (NMR). Urine, feces, bile, and blood samples of rats were obtained and analyzed. Reference standards of six metabolites were achieved with the combination of chemical synthesis, microbial transformation, and the model systems of rats. Moreover, in order to investigate the phase I metabolism of trantinterol in humans and to study the species differences between rats and humans, incubations with liver microsomes were performed. The biotransformation by a microbial model Cunninghamella blakesleana AS 3.970 was also studied. A total of 18 metabolites were identified in vivo and in vitro together, 13 of which were newly detected. Three phase I metabolites were detected in vivo and in vitro as well as in the microbial model, including the arylhydroxylamine (M1), the tert-butyl hydroxylated trantinterol (M2) and the 1-carbonyltrantinterol (M3). Another important pathway in rats is glutathione conjugation and further catabolism and oxidation to form consecutive derivatives (M4 through M10). Other metabolites include glucuronide, glucoside, and sulfate conjugates. The results of in vitro experiments indicate no species difference exists among rats, humans, and C. blakesleana AS 3.970 on the phase I metabolism of trantinterol. Our study provided the most comprehensive picture for trantinterol in vivo and in vitro metabolism to this day, and may predict its metabolism in humans.