Kinetic Cellular Phenotypic Profiling: Prediction, Identification, and Analysis of Bioactive Natural Products

Differential Biological Effects of Trifolium pratense Extracts-In Vitro Studies on Breast Cancer Models

The increasing popularity of herbal supplements emphasizes the need of scientific data regarding their health benefits and possible toxicological concerns. The complexity of botanical extracts, which include thousands of distinct compounds, contributes to the challenging nature of this endeavor. In this study, we explored the hormetic effects of two Trifolium pratense extracts on breast cell lines. Using a wide range of concentrations (0.1 to 3.33 mg/mL), we analyzed how extracts modulate cellular processes such as viability, proliferation, and oxidative stress on breast adenocarcinoma highly invasive estrogen receptor negative (ER-) and noninvasive ER+ cells, as well as on non-tumorigenic ER- normal cells. The cytotoxicity and real-time cell analysis (RTCA) assays showed that both extracts exercised a biphasic dose effect on adenocarcinoma ER+ and normal ER- cell proliferation and oxidative stress. We report a monotonic dose-dependent cytotoxicity on highly invasive adenocarcinoma ER- cells; the induced apoptosis was based on the pro-oxidant activity of extracts. The reactive oxygen species (ROS) generation by high-dose ethanolic extract was observed in all cells, followed by mitochondria dysfunction. Oxidative stress parameters, such as malondialdehyde (MDA) and reduced glutathione (GSH) levels, and superoxide dismutase (SOD) activity were affected. Our study demonstrates that T. pratense extracts have chemoprevention potential in normal and tumorigenic breast cells by modulating cellular proliferation and oxidative stress.

Hirsutella sinensis fungus improves cardiac function in mouse model of heart failure

Cordyceps sinensis, including Hirsutella sinensis, is a highly valuable traditional Chinese medicine and is used to treat patients with pulmonary heart disease in clinical practice. However, the underlying mechanisms of its effects remain unclear. In this study, a mouse model of heart failure established by non-thoracic, transverse aortic constriction (TAC) was developed to determine the underlying mechanisms of therapeutic effects of Hirsutella sinensis fungus (HSF) powder. The results showed that HSF treatment remarkably ameliorated myocardial hypertrophy, collagen fiber hyperplasia, and cardiac function in mice with heart failure. Using transcriptional and epigenetic analyses, we found that the mechanism of HSF mainly involved a variety of signaling pathways related to myocardial fibrosis and determined that HSF could reduce the levels of TGF-β1 proteins in heart tissue, as well as type I and III collagen levels. These data suggest that HSF alleviates heart failure, inhibits irreversible ventricular remodeling, and improves cardiac function through the regulation of myocardial fibrosis-related signaling pathways, which can provide novel opportunities to improve heart failure therapy.

Hirsutella Sinensis Fungus Regulates CD8+ T Cell Exhaustion Through Involvement of T-Bet/Eomes in the Tumor Microenvironment

Background: Targeting exhausted T (Tex) cells is a promising strategy for anti-tumour treatment. Previously, we demonstrated that Hirsutella sinensis fungus (HSF) could significantly increase T cell infiltration and the effector T cell ratio in the tumor microenvironment, activating systemic immune responses. However, we do not know how HSF regulates Tex cells in the tumor microenvironment. Here, we explored the mechanism underlying HSF inhibition of Tex cells and tumor growth and metastasis in breast cancer. Methods: We examined the effects of HSF on various tumor mouse models using in vivo imaging technology. Lung metastasis was detected by H&E staining and the T cell subsets in the tumor microenvironment were assayed with flow cytometry. The in vitro proliferation, function and apoptosis of CD8⁺ T cells were measured, as well as the T-bet and PD-1 mRNA expressions. Results: HSF inhibited tumor growth and lung metastasis in the mice, and had significantly higher CD44^LowCD62L^Hi and CD44^HiCD62L^Lowpopulations in the tumour-infiltrating CD8⁺ T cells. However, HSF significantly reduced levels of inhibitory receptors, such as PD-1, TIGIT, CTLA-4, and regulatory T cells. In vitro, HSF inhibited the CD8⁺ T cell apoptosis rate, and promoted CD8⁺ T cell proliferation and secretion of interferon (IFN)-γ and granzyme B. Furthermore, HSF treatment both in vivo and in vitro significantly increased Eomes expression, while decreasing T-bet expression. Conclusion: HSF exerted anti-tumour effects mainly through the immune system, by promoting effector/memory T cells and reducing Tex cell production in the tumor microenvironment. The specific mechanisms involved inhibiting T-bet and promoting Eomes to decrease the expression of immune inhibitor receptors and enhance the T cell function, respectively.

Quercetin Alleviates Intestinal Oxidative Damage Induced by H2O2 via Modulation of GSH: In Vitro Screening and In Vivo Evaluation in a Colitis Model of Mice

The gastrointestinal tract is exposed to pro-oxidants from food, host immune factors, and microbial pathogens, which may induce oxidative damage. Oxidative stress has been shown to play an important role in the onset of inflammatory bowel disease. This study aimed to use a novel model to evaluate the effects of a screened natural component and explore its possible mechanism. An in vitro oxidative stress Caco2 cell model induced by H₂O₂ was established using a real-time cellular analysis system and verified by addition of glutathione (GSH). A variety of plant components were chosen for the screening. Quercetin was the most effective phytochemical to alleviate the decreased cell index caused by H₂O₂ among the tested plant components. Furthermore, quercetin ameliorated dextran sulfate sodium salt (DSS)-induced colitis and further increased the serum GSH. The mechanism of quercetin protection was explored in Caco2. Reversed H₂O₂-induced cell damage and decreased reactive oxygen species and apoptosis ratio were observed in quercetin-treated cells. Also, quercetin increased expression of the glutamate-cysteine ligase catalytic subunit (GCLC), the first rate-limiting enzyme of glutathione synthesis, and increased intracellular GSH concentration under H₂O₂ treatment. This effect was abolished by the GCLC inhibitor buthionine sulfoximine. These results indicated that quercetin can improve cell proliferation and increase intracellular GSH concentrations by upregulating transcription of GCLC to eliminate excessive reactive oxygen species (ROS). Increased extracellular H₂O₂ concentration induced by quercetin under oxidative stress was related to the inhibition of AQP3 and upregulation of NOX1/2, which may contribute to the observed protective effects of quercetin. Moreover, the novel H₂O₂-induced oxidative stress cell model based on the real-time cellular analysis system was an effective model to screen natural products to deal with intestinal oxidative damage and help accelerate the discovery of new drugs for inflammatory bowel disease (IBD).

Effect of calcium on the interaction of Acinetobacter baumannii with human respiratory epithelial cells

Background

Investigating the factors that influence Acinetobacter baumannii(Ab) adhesion/invasion of host cells is important to understand its pathogenicity. Metal cations have been shown to play an important role in regulating the biofilm formation and increasing the virulence of Ab; however, the effect of calcium on host-bacterial interaction has yet to be clarified. Here, the dynamic process of the interaction between Ab and human respiratory epithelial cells and the effect of calcium on host-bacterial interaction were explored using microscopic imaging, quantitative PCR and real time cellular analysis (RTCA).

Results

The concentration of calcium, multiplicity of infection and co-culture time were all demonstrated to have effects on host-bacterial interaction. A unique “double peak” phenomenon changed to a sharp “single peak” phenomenon during the process of Ab infection under the effect of calcium was observed in the time-dependent cell response profiles. Moreover, calcium can increase Ab adhesion/invasion of epithelial cells by regulating the expression of Ab-related genes (ompA, bfmRS, abaI).

Conclusions

Effective control of calcium concentrations can provide new approaches for the prevention and treatment of multi-drug resistant Ab.

Compatibility principle in the Tanyu Tongzhi Formula revealed by a cell-based analysis

ETHNOPHARMACOLOGICAL RELEVANCE

The concept of the prescription in Traditional Chinese Medicine (TCM) is usually characterized by the compatibility principle "monarch, minister, assistant, and guide", which means herbs play primary, secondary, auxiliary, or harmonic roles, respectively, to achieve the optimally holistic effect. Following this compatibility principle, the Tanyu Tongzhi Formula (TTF), used for many years to treat cardiovascular diseases, has been proved effective clinically and experimentally.

AIM OF THE STUDY

The ancient compatibility principle is based on experiences, but whether its underlying interactions can be explained at the cellular level is unknown. We aimed to explore the mechanisms of activity of the TTF herbs and the interactions between them.

MATERIALS AND METHODS

We used a real-time cell analyzer to record the responses of COS-7 cells to the herbs in TTF, both individually and in different combinations. We also used biochemical assays to further characterize the TTF activity.

RESULTS

Monarch herb Fructus trichosanthis acts as an inhibitor of the EGF signaling. It's cytotoxicity, derived from inhibition of tubulin polymerization, could be completely neutralized by the combination of the phlegm group, or the whole TTF combination. Meanwhile, the minister, assistant, and guide herbs in the TTF did not affect EGF signaling.

CONCLUSION

Our results provide a demonstration, at the cellular level, of the compatibility principle of "monarch, minister, assistant, and guide" in TTF. Under the guidance of this principle, TTF exerts the anti-inflammation and anti-tumor effects through inhibiting EGF signaling, while avoiding the microtubule-disrupting activity of Fructus trichosanthis.

xCELLanalyzer: A Framework for the Analysis of Cellular Impedance Measurements for Mode of Action Discovery

Mode of action (MoA) identification of bioactive compounds is very often a challenging and time-consuming task. We used a label-free kinetic profiling method based on an impedance readout to monitor the time-dependent cellular response profiles for the interaction of bioactive natural products and other small molecules with mammalian cells. Such approaches have been rarely used so far due to the lack of data mining tools to properly capture the characteristics of the impedance curves. We developed a data analysis pipeline for the xCELLigence Real-Time Cell Analysis detection platform to process the data, assess and score their reproducibility, and provide rank-based MoA predictions for a reference set of 60 bioactive compounds. The method can reveal additional, previously unknown targets, as exemplified by the identification of tubulin-destabilizing activities of the RNA synthesis inhibitor actinomycin D and the effects on DNA replication of vioprolide A. The data analysis pipeline is based on the statistical programming language R and is available to the scientific community through a GitHub repository.

Application of Real-Time Cell Electronic Analysis System in Modern Pharmaceutical Evaluation and Analysis

Objective: We summarized the progress of the xCELLigence real-time cell analysis (RTCA) technology application in recent years for the sake of enriching and developing the application of RTCA in the field of Chinese medicine. Background: The RTCA system is an established electronic cellular biosensor. This system uses micro-electronic biosensor technology that is confirmed for real-time, label-free, dynamic and non-offensive monitoring of cell viability, migration, growth, spreading, and proliferation. Methods: We summarized the relevant experiments and literature of RTCA technology from the principles, characteristics, applications, especially from the latest application progress. Results and conclusion: RTCA is attracting more and more attention. Now it plays an important role in drug screening, toxicology, Chinese herbal medicine and so on. It has wide application prospects in the area of modern pharmaceutical evaluation and analysis.

Study on the Quality Evaluation of Compound Danshen Preparations Based on the xCELLigence Real-Time Cell-Based Assay and Pharmacodynamic Authentication

Objective: To perform a preliminary study on the quality evaluation of compound Danshen preparations based on the xCELLigence Real-Time Cell-based Assay (RTCA) system and make a pharmacodynamics verification. Methods: The compound Danshen was discussed as a methodological example, and the bioactivity of the compound Danshen preparations were evaluated by real-time cell electronic analysis technology. Meanwhile, an in vivo experiment on an acute blood stasis rat model was performed in order to verify this novel evaluation through the curative effect of dissipating blood stasis. Results: We determined the cell index (CI) and IC50 of the compound Danshen preparations and produced time/dose-dependent cell response profiles (TCRPs). The quality of the three kinds of compound Danshen preparations was evaluated through the RTCA data. The trend of CI and TCRPs reflected the effect of drugs on the cell (promoting or inhibiting), and it was verified that the results correlated with the biological activity of the drugs using a pharmacodynamics experiment. Conclusion: The RTCA system can be used to evaluate the quality of compound Danshen Preparations, and it can provide a new idea and new method for quantitatively characterizing the biological activity of traditional Chinese medicines (TCMs).

UPLC-QTOF/MSE and Bioassay Are Available Approaches for Identifying Quality Fluctuation of Xueshuantong Lyophilized Powder in Clinic

Xueshuantong Lyophilized Powder (XST), consisting of a series of saponins extracted from Panax notoginseng, is widely applied to treat acute cerebral infarction, stroke, and coronary heart disease in China. However, most adverse drug reactions (ADR) in clinic are caused by quality problems of XST. In this study, six batches of certainly abnormal, four batches of possibly abnormal XST, and eight batches of normal XST were obtained from the clinical practice. Their quality fluctuations were identified by ultra-performance liquid chromatography coupled with an electrospray ionization quadrupole time-of-flight mass spectrometry operating in MS^E mode (UPLC-QTOF/MS^E) and bioassays including antithrombin and proplasmin assay. Fourteen potential components responsible for clinical ADR were identified by UPLC-QTOF/MS^E, especially ginsenoside Rg1, Rg3, Rb1 and notoginsenoside R1. In addition, 83.3% (5/6) and 50.0% (3/6) certainly abnormal samples could be identified by UPLC-QTOF/MS^E and bioassay, respectively. Interestingly, further integration of the two methods could entirely identify all the certainly abnormal samples and inferred that all the possibly abnormal samples were closely related to their quality fluctuation. It indicates that it is advisable to combine UPLC-QTOF/MS^E and bioassay for identifying quality fluctuation of XST, and thus reduce its ADR in clinic.

Hirsutella sinensis Inhibits Lewis Lung Cancer via Tumor Microenvironment Effector T Cells in Mice

Hirsutella sinensis fungus (HSF) is an artificial substitute of the well-known medicine Cordyceps sinensis with similar beneficial effects in humans. We previously found that HSF can regulate immune function and inhibit tumor growth; however, the mechanisms involved in these effects were still unclear. Accordingly, in this study, we investigated the effects of HSF on immune cell subsets in the tumor microenvironment in mice. The results showed that HSF inhibited Lewis lung cancer growth, alleviated abnormalities in routine blood tests, and enhanced tumor-infiltrating T cells, particularly the proportion of effector CD8[Formula: see text] T cells. In addition, HSF also ameliorated the immune-suppressive microenvironment and decreased the proportions of regulatory T cell and myeloid-derived suppressor cell populations. To confirm the effects of HSF on promotion of effector CD8[Formula: see text] T-cell production, we further evaluated changes in postoperative metastasis following treatment with HSF. Indeed, orthotopic lung metastasis was significantly suppressed, and survival times were increased in HSF-treated mice. Taken together, our findings suggested that HSF inhibited Lewis lung cancer by enhancing the population of effective CD8[Formula: see text] T cells.

A novel release kinetics evaluation of Chinese compound medicine: Application of the xCELLigence RTCA system to determine the release characteristics of Sedum sarmentosum compound sustained-release pellets

Purpose: To establish a novel release kinetics evaluation method of Chinese compound medicine (Sedum Sarmentosum compound) with xCELLigence Real-Time Cell-based Assay (RTCA) system. Methods: Cell lines sensitive to Sedum Sarmentosum compound are screened, and cell index-time (CI-T) graphs and cell index release kinetics models are established based on the cell index (CI) monitored. The methodological studies of precision and repeatability were processed by the cell monitors system. The release profiles of the sustained-release Sedum Sarmentosum compound were determined. Consequently, the sustained-release property was characterized by the kinetic parameters based on the cell-index. Results: The accumulative release rate based on cell index of Sedum sarmentosum compound sustained-release preparation was determined and it had a good correlation with time, fitting better with First-order model, Higuchi model and Ritger-Peppas model, and fitting best with Weibull model. It indicated that the release rate is proportional with the diffusion coefficient. Conclusion: The new method of cell-index release kinetics may provide a quantitative description for the release of the multi active agents from Traditional Chinese Medicines. The application of xCELLigence RTCA system for evaluating the release kinetics of Chinese compound medicine is feasible.

Identification of Chinese medicinal fungus Cordyceps sinensis by depth-profiling mid-infrared photoacoustic spectroscopy

With increased demand for Cordyceps sinensis it needs rapid methods to meet the challenge of identification raised in quality control. In this study Cordyceps sinensis from four typical natural habitats in China was characterized by depth-profiling Fourier transform infrared photoacoustic spectroscopy. Results demonstrated that Cordyceps sinensis samples resulted in typical photoacoustic spectral appearance, but heterogeneity was sensed in the whole sample; due to the heterogeneity Cordyceps sinensis was represented by spectra of four groups including head, body, tail and leaf under a moving mirror velocity of 0.30cms^-1. The spectra of the four groups were used as input of a probabilistic neural network (PNN) to identify the source of Cordyceps sinensis, and all the samples were correctly identified by the PNN model. Therefore, depth-profiling Fourier transform infrared photoacoustic spectroscopy provides novel and unique technique to identify Cordyceps sinensis, which shows great potential in quality control of Cordyceps sinensis.

Safflower Yellow Prevents Pulmonary Metastasis of Breast Cancer by Inhibiting Tumor Cell Invadopodia

Carthamus tinctorius L. is a traditional Chinese medicine that activates blood circulation and dissipates blood stasis, and has been extensively used as antitumor treatment in a clinical setting in single or in compound preparation form. However, empirical evidence and a better understanding of the possible mechanisms involved are still required. Here, we investigated the role of safflower yellow (SY), the active ingredient of C. tinctorius, in the pulmonary metastasis of breast cancer, and the underlying mechanism of action. EGF-meditated time- and dose-dependent cell response profiles were applied to screen for the activity of SY in vitro, while orthotopic lung metastasis and intravenous injection were used to evaluate the antimetastatic role of SY in vivo. SY could dose-dependently inhibit EGF-mediated time- and dose-dependent cell response profiles by inhibiting cytoskeletal rearrangement. We also found that SY significantly inhibited the migration of breast cancer cells in vitro and pulmonary metastasis of breast cancer cells in vivo. Consistent with these phenotypes, formation of invadopodia and the expression of MMP-9 and p-Src proteins were decreased after EGF stimulation in MBA-MD-231 cells treat with SY, as well as in lung metastatic foci. Additionally, circulating tumor cells retained in lung capillaries were also reduced. These results suggest that the antimetastatic effect of SY is due to its inhibition of invadopodia formation, which occurs mainly through Src-dependent cytoskeleton rearrangement. We suggest that SY should be considered as a potential novel therapeutic agent for the treatment of breast cancer.

Cellular Phenotypic Analysis of Macrophage Activation Unveils Kinetic Responses of Agents Targeting Phosphorylation

Macrophages are highly plastic cells, which serve as sentinels of the host immune system due to their ability to recognize and respond to microbial products rapidly and dynamically. Appropriate regulation of macrophage activation is essential for pathogen clearance or preventing autoimmune diseases. However, regularly used endpoint assays for analyzing macrophage functions have the limitations of being static and non-high throughput. In this study, we introduced a real-time and convenient method based on changes in cellular impedance that are detected by microelectronic biosensors. This new method can record the time/dose-dependent cell response profiles (TCRPs) of macrophages in real time and generates physiologically relevant data. The TCRPs generated from classically interferon-γ/lipopolysaccharide-activated macrophages showed considerable consistency with the data generated from standard endpoint assays. We further explored this approach by using it for global screening of a library of protein tyrosine kinase/phosphatase (PTK/PTP) inhibitors to investigate their impact on macrophage activation. Collectively, our findings suggest that the cellular impedance-based assay provides a promising approach for dynamically monitoring macrophage functions in a convenient and high-throughput manner.

Cell-based phenotypic screening of mast cell degranulation unveils kinetic perturbations of agents targeting phosphorylation

Mast cells play an essential role in initiating allergic diseases. The activation of mast cells are controlled by a complicated signal network of reversible phosphorylation, and finding the key regulators involved in this network has been the focus of the pharmaceutical industry. In this work, we used a method named Time-dependent cell responding profile (TCRP) to track the process of mast cell degranulation under various perturbations caused by agents targeting phosphorylation. To test the feasibility of this high-throughput cell-based phenotypic screening method, a variety of biological techniques were used. We further screened 145 inhibitors and clustered them based on the similarities of their TCRPs. Stat3 phosphorylation has been widely reported as a key step in mast cell degranulation. Interestingly, our TCRP results showed that a Stat3 inhibitor JSI124 did not inhibit degranulation like other Stat3 inhibitors, such as Stattic, clearly inhibited degranulation. Regular endpoint assays demonstrated that the distinctive TCRP of JSI124 potentially correlated with the ability to induce apoptosis. Consequently, different agents possibly have disparate functions, which can be conveniently detected by TCRP. From this perspective, our TCRP screening method is reliable and sensitive when it comes to discovering and selecting novel compounds for new drug developments.

The Inhibition of Mast Cell Activation of Radix Paeoniae alba Extraction Identified by TCRP Based and Conventional Cell Function Assay Systems

Chinese herbs have long been used to treat allergic disease, but recently the development was greatly impeded by the lack of good methods to explore the mechanism of action. Here, we showed the effects of Chinese herb Radix Paeoniae alba were identified and characterized by a mast cell activation assay that involves electronic impedance readouts for dynamic monitoring of cellular responses to produce time-dependent cell responding profiles (TCRPs), and the anti-allergic activities were further confirmed with various conventional molecular and cell biology tools. We found Radix P. alba can dose-dependently inhibit TCPRs, and have anti-allergic function in vitro and in vivo. Radix P. alba suppressed mast cell degranulation not only inhibiting the translocation of granules to the plasma membrane, but also blocking membrane fusion and exocytosis; and that there may be other anti-allergic components in addition to paeoniflorin. Our results suggest that Radix P. alba regulated mast cell activation with multiple targets, and this approach is also suitable for discovering other mast cell degranulation-targeting Chinese herbs and their potential multi-target mechanisms.

Compound annotation with real time cellular activity profiles to improve drug discovery

INTRODUCTION

In the past decade, a range of innovative strategies have been developed to improve the productivity of pharmaceutical research and development. In particular, compound annotation, combined with informatics, has provided unprecedented opportunities for drug discovery.

AREAS COVERED

In this review, a literature search from 2000 to 2015 was conducted to provide an overview of the compound annotation approaches currently used in drug discovery. Based on this, a framework related to a compound annotation approach using real-time cellular activity profiles for probe, drug, and biology discovery is proposed.

EXPERT OPINION

Compound annotation with chemical structure, drug-like properties, bioactivities, genome-wide effects, clinical phenotypes, and textural abstracts has received significant attention in early drug discovery. However, these annotations are mostly associated with endpoint results. Advances in assay techniques have made it possible to obtain real-time cellular activity profiles of drug molecules under different phenotypes, so it is possible to generate compound annotation with real-time cellular activity profiles. Combining compound annotation with informatics, such as similarity analysis, presents a good opportunity to improve the rate of discovery of novel drugs and probes, and enhance our understanding of the underlying biology.

Prevention of pulmonary fibrosis with salvianolic acid a by inducing fibroblast cell cycle arrest and promoting apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Danshen (Salvia miltiorrhiza Bunge) is widely used in traditional Chinese medicine (TCM), often in combination with other herbs, to treat a diversity of ailments. More recent studies have focused on its possible roles in the treatment of respiratory diseases (pneumonia and pulmonary fibrosis) and found that it has pharmacological activity that protects pulmonary morphology and function. However, the mechanism underlying this activity has not yet been clarified.

MATERIALS AND METHODS

The purpose of this study was to investigate the anti-pulmonary fibrosis effects exerted by salvianolic acid A (SAA), the ingredient responsible for the pharmacological activity of Danshen, and the underlying mechanisms. Bleomycin (BLM)-induced rat pulmonary fibrosis was used to evaluate the antifibrotic role of SAA, and fibroblast cells were used to study the mechanism involved.

RESULTS

BLM-treated rats exhibited increased alveolar wall thickness and collagen deposition in lung tissues, but these pathologies were greatly attenuated by daily administration of SAA. We also found that SAA significantly inhibited the proliferation, adhesion and migration of fibroblasts in vitro. This was partly due to a strong induction of cell cycle arrest and apoptosis upon SAA treatment. Consistent with these phenotypes, we observed decreased expression of the cell cycle-related proteins cyclin D1, cyclin E1, and cyclin B1, and increased expression of p53 and p21 in SAA-treated cells. In addition, the anti-apoptotic Bcl-2 protein decreased in a dose-dependent manner, while cleaved caspase-3 protein increased upon SAA treatment.

CONCLUSIONS

These results suggest that the alleviation of rat pulmonary fibrosis by SAA is due to the inhibition of fibroblast proliferation and induction of apoptosis, which occurs mainly through p53-dependent growth arrest and apoptosis. We suggest that SAA should be considered as a potential novel therapeutic agent for the treatment of fibrotic lung diseases.

Label-free drug discovery

Current drug discovery is dominated by label-dependent molecular approaches, which screen drugs in the context of a predefined and target-based hypothesis in vitro. Given that target-based discovery has not transformed the industry, phenotypic screen that identifies drugs based on a specific phenotype of cells, tissues, or animals has gained renewed interest. However, owing to the intrinsic complexity in drug-target interactions, there is often a significant gap between the phenotype screened and the ultimate molecular mechanism of action sought. This paper presents a label-free strategy for early drug discovery. This strategy combines label-free cell phenotypic profiling with computational approaches, and holds promise to bridge the gap by offering a kinetic and holistic representation of the functional consequences of drugs in disease relevant cells that is amenable to mechanistic deconvolution.

Phenotypic pattern-based assay for dynamically monitoring host cellular responses to Salmonella infections

The interaction between mammalian host cells and bacteria is a dynamic process, and the underlying pathologic mechanisms are poorly characterized. Limited information describing the host-bacterial interaction is based mainly on studies using label-based endpoint assays that detect changes in cell behavior at a given time point, yielding incomplete information. In this paper, a novel, label-free, real-time cell-detection system based on electronic impedance sensor technology was adapted to dynamically monitor the entire process of intestinal epithelial cells response to Salmonella infection. Changes in cell morphology and attachment were quantitatively and continuously recorded following infection. The resulting impedance-based time-dependent cell response profiles (TCRPs) were compared to standard assays and showed good correlation and sensitivity. Biochemical assays further suggested that TCRPs were correlated with cytoskeleton-associated morphological dynamics, which can be largely attenuated by inhibitions of actin and microtubule polymerization. Collectively, our data indicate that cell-electrode impedance measurements not only provide a novel, real-time, label-free method for investigating bacterial infection but also help advance our understanding of host responses in a more physiological and continuous manner that is beyond the scope of current endpoint assays.