Metabolic rewiring revealed by cell-specific rate analyses from nontargeted exometabolomics during simultaneous consumption of glucose and lactic acid in a CHO fed-batch process.

Previously, we reported, based on an untargeted metabolomics, carnitine derivatives are part of a mechanism to overcome impaired mitochondrial functioning triggered by an acyl-group overflow in CHO cells. In this study, we analyzed the cell-specific rates of 24 selected metabolites using two metrics: correlation coefficients and root-mean-square deviations (RMSDs) between glucose-fed versus glucose/lactic acid-fed cultures. The time-course profiles of acetylcarnitine, adipoylcarnitine, glutarylcarnitine, glutamate, and succinate exhibited significant negative correlations between the two culture conditions. Based on RMSDs, seven carnitine derivatives, 3-hydroxy-methyl-glutarate, mevalonate, pyridoxamine-5-phosphate, succinate, and glycine were substantially different. The analyses from the two metrics reveal a distinctive rearrangement of rates from the following metabolic pathways: (i) high secretion rates of carnitines as part of the acyl-group removal, (ii) low secretion rates of succinate, related to the tricarboxylic acid cycle and the electron-transport chain, (iii) low secretion rates of pyridoxamine-5-phosphate - a co-factor for amino acid catabolism, transaminations, and transsulfuration, and (iv) increases in the consumption rates of glutamate and glycine, both used to produce glutathione. The rewiring in rates observed upon feeding lactic acid is best explained by the activation of pathways supporting homeostasis of acyl-groups and antioxidant synthesis, which are required for continuous proper functioning of oxidative phosphorylation.

Integrating metabolome dynamics and process data to guide cell line selection in biopharmaceutical process development.

The successful development of mammalian cell culture for the production of therapeutic antibodies is a resource-intensive and multistage process which requires the selection of high performing and stable cell lines at different scale-up stages. Accordingly, science-based approaches exploiting biological information, such as metabolomics, can support and accelerate the selection of promising cell lines to progress. In fact, the integration of dynamic biological information with process data can provide valuable insights on the cell physiological changes as a consequence of the cultivation process. This work studies the industrial development of monoclonal antibodies at micro-bioreactor scale (Ambr®15) and aims at accelerating the selection of the better performing cell lines. To that end, we apply a machine learning approach to integrate time-varying process and biological information (i.e., metabolomics), explicitly exploiting their dynamics. Strikingly, cell line performance during the cultivation can be predicted from early process timepoints by exploiting the gradual temporal evolution of metabolic phenotypes. Furthermore, product titer is estimated with good accuracy at late process timepoints, providing insights into its relationship with underlying metabolic mechanisms and enabling the identification of biomarkers to be further investigated. The biological insights obtained through the proposed machine learning approach provide data-driven metabolic understanding allowing early identification of high performing cell lines. Additionally, this analysis offers the opportunity to identify key metabolites which could be used as biomarkers for industrially relevant phenotypes and onward fit into our commercial manufacturing platforms.

Bioaccumulation of therapeutic drugs by human gut bacteria.

Bacteria in the gut can modulate the availability and efficacy of therapeutic drugs. However, the systematic mapping of the interactions between drugs and bacteria has only started recently1 and the main underlying mechanism proposed is the chemical transformation of drugs by microorganisms (biotransformation). Here we investigated the depletion of 15 structurally diverse drugs by 25 representative strains of gut bacteria. This revealed 70 bacteria-drug interactions, 29 of which had not to our knowledge been reported before. Over half of the new interactions can be ascribed to bioaccumulation; that is, bacteria storing the drug intracellularly without chemically modifying it, and in most cases without the growth of the bacteria being affected. As a case in point, we studied the molecular basis of bioaccumulation of the widely used antidepressant duloxetine by using click chemistry, thermal proteome profiling and metabolomics. We find that duloxetine binds to several metabolic enzymes and changes the metabolite secretion of the respective bacteria. When tested in a defined microbial community of accumulators and non-accumulators, duloxetine markedly altered the composition of the community through metabolic cross-feeding. We further validated our findings in an animal model, showing that bioaccumulating bacteria attenuate the behavioural response of Caenorhabditis elegans to duloxetine. Together, our results show that bioaccumulation by gut bacteria may be a common mechanism that alters drug availability and bacterial metabolism, with implications for microbiota composition, pharmacokinetics, side effects and drug responses, probably in an individual manner.

Exometabolome profiling reveals activation of the carnitine buffering pathway in fed-batch cultures of CHO cells co-fed with glucose and lactic acid.

Adjustments to CHO cell physiology were recently observed during implementation of a Raman spectroscopy-based glucose and lactate control strategy. To further understand how these cells, under monoclonal antibody (mAb) production conditions, utilized the extra lactic acid fed, we performed a comprehensive semi-quantitative and time-dependent analysis of the exometabolome. This study focused on the CHO cell's metabolic shift from the fifth day of culture. We compared relative levels of extracellular metabolites in the absence or presence of a 2 g/L lactic acid setpoint while glucose was kept at 4 g/L. Our hypothesis is that extra lactic acid would supply more pyruvate, favoring oxidative phosphorylation. We subsequentially uncovered several carnitine derivatives as biomarkers of the simultaneous activation of TCA anaplerotic pathways as well as a carbon-buffering pathway. CHO cells exhibited a balance between intermediates from (i) amino acid catabolism, (ii) fatty acid ß-oxidation, and (iii) pyruvate from glycolysis and lactic acid; and the secretion of their intermediate carnitine derivatives. In addition, 3-hydroxy-methyl-glutaric acid (HMG) and mevalonate syntheses were found as biomarkers of alternative acyl group removal. Together, under a limited capacity to assimilate the surplus of acyl-CoA groups as well as an ability to maintain the acyl-CoA: free CoA ratio for proper and continuous functioning of the TCA cycle, CHO cells activate the carnitine-buffering system, HMG, and mevalonate pathways.

New insights into the mechanisms underlying 5-fluorouracil-induced intestinal toxicity based on transcriptomic and metabolomic responses in human intestinal organoids.

5-Fluorouracil (5-FU) is a widely used chemotherapeutical that induces acute toxicity in the small and large intestine of patients. Symptoms can be severe and lead to the interruption of cancer treatments. However, there is limited understanding of the molecular mechanisms underlying 5-FU-induced intestinal toxicity. In this study, well-established 3D organoid models of human colon and small intestine (SI) were used to characterize 5-FU transcriptomic and metabolomic responses. Clinically relevant 5-FU concentrations for in vitro testing in organoids were established using physiologically based pharmacokinetic simulation of dosing regimens recommended for cancer patients, resulting in exposures to 10, 100 and 1000 µM. After treatment, different measurements were performed: cell viability and apoptosis; image analysis of cell morphological changes; RNA sequencing; and metabolome analysis of supernatant from organoids cultures. Based on analysis of the differentially expressed genes, the most prominent molecular pathways affected by 5-FU included cell cycle, p53 signalling, mitochondrial ATP synthesis and apoptosis. Short time-series expression miner demonstrated tissue-specific mechanisms affected by 5-FU, namely biosynthesis and transport of small molecules, and mRNA translation for colon; cell signalling mediated by Rho GTPases and fork-head box transcription factors for SI. Metabolomic analysis showed that in addition to the effects on TCA cycle and oxidative stress in both organoids, tissue-specific metabolic alterations were also induced by 5-FU. Multi-omics integration identified transcription factor E2F1, a regulator of cell cycle and apoptosis, as the best key node across all samples. These results provide new insights into 5-FU toxicity mechanisms and underline the relevance of human organoid models in the safety assessment in drug development.

An integrated multiomic and quantitative label-free microscopy-based approach to study pro-fibrotic signalling in ex vivo human precision-cut lung slices.

Fibrosis can affect any organ, resulting in the loss of tissue architecture and function with often life-threatening consequences. Pathologically, fibrosis is characterised by the expansion of connective tissue due to excessive deposition of extracellular matrix (ECM) proteins, including the fibrillar forms of collagen. A significant limitation for discovering cures for fibrosis is the availability of suitable human models and techniques to quantify mature fibrillar collagen deposition as close as possible to human physiological conditions.Here we have extensively characterised an ex vivo cultured human lung tissue-derived, precision-cut lung slices (hPCLS) model using label-free second harmonic generation (SHG) light microscopy to quantify fibrillar collagen deposition and mass spectrometry-based techniques to obtain a proteomic and metabolomic fingerprint of hPCLS in ex vivo culture.We demonstrate that hPCLS are viable and metabolically active, with mesenchymal, epithelial, endothelial and immune cell types surviving for at least 2 weeks in ex vivo culture. Analysis of hPCLS-conditioned supernatants showed a strong induction of pulmonary fibrosis-related ECM proteins upon transforming growth factor-ß1 (TGF-ß1) stimulation. This upregulation of ECM proteins was not translated into an increased deposition of fibrillar collagen. In support of this observation, we revealed the presence of a pro-ECM degradation activity in our ex vivo cultures of hPCLS, inhibition of which by a metalloproteinase inhibitor resulted in increased collagen deposition in response to TGF-ß1 stimulation.Together the data show that an integrated approach of measuring soluble pro-fibrotic markers alongside quantitative SHG-based analysis of fibrillar collagen is a valuable tool for studying pro-fibrotic signalling and testing anti-fibrotic agents.

Complementary NAD+ replacement strategies fail to functionally protect dystrophin-deficient muscle.

BACKGROUND: Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder stemming from a loss of functional dystrophin. Current therapeutic options for DMD are limited, as small molecule modalities remain largely unable to decrease the incidence or mitigate the consequences of repetitive mechanical insults to the muscle during eccentric contractions (ECCs). METHODS: Using a metabolomics-based approach, we observed distinct and transient molecular phenotypes in muscles of dystrophin-deficient MDX mice subjected to ECCs. Among the most chronically depleted metabolites was nicotinamide adenine dinucleotide (NAD), an essential metabolic cofactor suggested to protect muscle from structural and metabolic degeneration over time. We tested whether the MDX muscle NAD pool can be expanded for therapeutic benefit using two complementary small molecule strategies: provision of a biosynthetic precursor, nicotinamide riboside, or specific inhibition of the NAD-degrading ADP-ribosyl cyclase, CD38. RESULTS: Administering a novel, potent, and orally available CD38 antagonist to MDX mice successfully reverted a majority of the muscle metabolome toward the wildtype state, with a pronounced impact on intermediates of the pentose phosphate pathway, while supplementing nicotinamide riboside did not significantly affect the molecular phenotype of the muscle. However, neither strategy sustainably increased the bulk tissue NAD pool, lessened muscle damage markers, nor improved maximal hindlimb strength following repeated rounds of eccentric challenge and recovery. CONCLUSIONS: In the absence of dystrophin, eccentric injury contributes to chronic intramuscular NAD depletion with broad pleiotropic effects on the molecular phenotype of the tissue. These molecular consequences can be more effectively overcome by inhibiting the enzymatic activity of CD38 than by supplementing nicotinamide riboside. However, we found no evidence that either small molecule strategy is sufficient to restore muscle contractile function or confer protection from eccentric injury, undermining the modulation of NAD metabolism as a therapeutic approach for DMD.

Selective targeting of BD1 and BD2 of the BET proteins in cancer and immunoinflammation.

The two tandem bromodomains of the BET (bromodomain and extraterminal domain) proteins enable chromatin binding to facilitate transcription. Drugs that inhibit both bromodomains equally have shown efficacy in certain malignant and inflammatory conditions. To explore the individual functional contributions of the first (BD1) and second (BD2) bromodomains in biology and therapy, we developed selective BD1 and BD2 inhibitors. We found that steady-state gene expression primarily requires BD1, whereas the rapid increase of gene expression induced by inflammatory stimuli requires both BD1 and BD2 of all BET proteins. BD1 inhibitors phenocopied the effects of pan-BET inhibitors in cancer models, whereas BD2 inhibitors were predominantly effective in models of inflammatory and autoimmune disease. These insights into the differential requirement of BD1 and BD2 for the maintenance and induction of gene expression may guide future BET-targeted therapies.

Identifying drug targets in tissues and whole blood with thermal-shift profiling.

Monitoring drug-target interactions with methods such as the cellular thermal-shift assay (CETSA) is well established for simple cell systems but remains challenging in vivo. Here we introduce tissue thermal proteome profiling (tissue-TPP), which measures binding of small-molecule drugs to proteins in tissue samples from drug-treated animals by detecting changes in protein thermal stability using quantitative mass spectrometry. We report organ-specific, proteome-wide thermal stability maps and derive target profiles of the non-covalent histone deacetylase inhibitor panobinostat in rat liver, lung, kidney and spleen and of the B-Raf inhibitor vemurafenib in mouse testis. In addition, we devised blood-CETSA and blood-TPP and applied it to measure target and off-target engagement of panobinostat and the BET family inhibitor JQ1 directly in whole blood. Blood-TPP analysis of panobinostat confirmed its binding to known targets and also revealed thermal stabilization of the zinc-finger transcription factor ZNF512. These methods will help to elucidate the mechanisms of drug action in vivo.

Multiplexed Proteome Dynamics Profiling Reveals Mechanisms Controlling Protein Homeostasis.

Protein degradation plays important roles in biological processes and is tightly regulated. Further, targeted proteolysis is an emerging research tool and therapeutic strategy. However, proteome-wide technologies to investigate the causes and consequences of protein degradation in biological systems are lacking. We developed "multiplexed proteome dynamics profiling" (mPDP), a mass-spectrometry-based approach combining dynamic-SILAC labeling with isobaric mass tagging for multiplexed analysis of protein degradation and synthesis. In three proof-of-concept studies, we uncover different responses induced by the bromodomain inhibitor JQ1 versus a JQ1 proteolysis targeting chimera; we elucidate distinct modes of action of estrogen receptor modulators; and we comprehensively classify HSP90 clients based on their requirement for HSP90 constitutively or during synthesis, demonstrating that constitutive HSP90 clients have lower thermal stability than non-clients, have higher affinity for the chaperone, vary between cell types, and change upon external stimuli. These findings highlight the potential of mPDP to identify dynamically controlled degradation mechanisms in cellular systems.

Click chemistry enables preclinical evaluation of targeted epigenetic therapies.

The success of new therapies hinges on our ability to understand their molecular and cellular mechanisms of action. We modified BET bromodomain inhibitors, an epigenetic-based therapy, to create functionally conserved compounds that are amenable to click chemistry and can be used as molecular probes in vitro and in vivo. We used click proteomics and click sequencing to explore the gene regulatory function of BRD4 (bromodomain containing protein 4) and the transcriptional changes induced by BET inhibitors. In our studies of mouse models of acute leukemia, we used high-resolution microscopy and flow cytometry to highlight the heterogeneity of drug activity within tumor cells located in different tissue compartments. We also demonstrate the differential distribution and effects of BET inhibitors in normal and malignant cells in vivo. This study provides a potential framework for the preclinical assessment of a wide range of drugs.

A Modular Probe Strategy for Drug Localization, Target Identification and Target Occupancy Measurement on Single Cell Level.

Late stage failures of candidate drug molecules are frequently caused by off-target effects or inefficient target engagement in vivo. In order to address these fundamental challenges in drug discovery, we developed a modular probe strategy based on bioorthogonal chemistry that enables the attachment of multiple reporters to the same probe in cell extracts and live cells. In a systematic evaluation, we identified the inverse electron demand Diels-Alder reaction between trans-cyclooctene labeled probe molecules and tetrazine-tagged reporters to be the most efficient bioorthogonal reaction for this strategy. Bioorthogonal biotinylation of the probe allows the identification of drug targets in a chemoproteomics competition binding assay using quantitative mass spectrometry. Attachment of a fluorescent reporter enables monitoring of spatial localization of probes as well as drug-target colocalization studies. Finally, direct target occupancy of unlabeled drugs can be determined at single cell resolution by competitive binding with fluorescently labeled probe molecules. The feasibility of the modular probe strategy is demonstrated with noncovalent PARP inhibitors.

New imidazoquinoxaline derivatives: Synthesis, biological evaluation on melanoma, effect on tubulin polymerization and structure-activity relationships.

Microtubules are considered as important targets of anticancer therapy. EAPB0503 and its structural imidazo[1,2-a]quinoxaline derivatives are major microtubule-interfering agents with potent anticancer activity. In this study, the synthesis of several new derivatives of EAPB0503 is described, and the anticancer efficacy of 13 novel derivatives on A375 human melanoma cell line is reported. All new compounds show significant antiproliferative activity with IC50 in the range of 0.077-122µM against human melanoma cell line (A375). Direct inhibition of tubulin polymerization assay in vitro is also assessed. Results show that compounds 6b, 6e, 6g, and EAPB0503 highly inhibit tubulin polymerization with percentages of inhibition of 99%, 98%, 90%, and 84% respectively. Structure-activity relationship studies within the series are also discussed in line with molecular docking studies into the colchicine-binding site of tubulin.

Structural characterization of in vitro metabolites of the new anticancer agent EAPB0503 by liquid chromatography-tandem mass spectrometry.

EAPB0503, belonging to the imidazo[1,2-a]quinoxaline series, is an anticancer drug with antitumoral activity against a variety of tumors. Previous studies have shown that this drug undergoes demethylation and oxygenation reactions. In this paper, liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was employed to assess the structures of unknown oxygenated metabolites of EAPB0503. EAPB0503 and its identified demethylated metabolites, EAPB0502 and EAPB0603, were incubated with human, rat, dog and mouse liver microsomes, as well as human, rat and dog hepatocytes. After separation on a C8 analytical column with a gradient elution of acetonitrile-formate buffer, positive ESI-MS/MS experiments were performed. To facilitate metabolite identification, the detailed fragmentation pathways of the parent compounds were first studied using high-resolution MS/MS. Additional hydrogen/deuterium exchange LC-MS/MS experiments were used to support the identification and structural characterization of metabolites. Four hydroxylated metabolites were identified: M'4 and its demethylated derivative M'1 (OH in ortho position on the phenyl substituent in position 1), and M'6 and its demethylated derivative M'3 (OH on the imidazole ring at the C2 position). Three phase II metabolites (Met A, EAPB0602 glucuronide; Met B, M'4 glucuronide; Met C, EAPB0603 glucuronide) were also evidenced. Elucidation of the metabolite structures was performed by comparing the chromatographic behaviors (changes in retention times), by measuring the molecular masses (mass increment), by studying the MS(2) spectral patterns of metabolites with those of parent drugs and for M'1 and M'4 by co-analysis with synthetic standards. The results of the present study provided important structural information relating to the metabolism of EAPB0503.