Search Results (30)

Macrophages are highly plastic innate immune cells that integrate diverse microenvironmental cues to adopt pro-inflammatory (M1) or anti-inflammatory (M2) functional states, which critically influence the pathogenesis of infectious, autoimmune, inflammatory, and malignant diseases. This review provides an overview of current concepts of macrophage ontogeny, functional heterogeneity, and disease-associated phenotypes, with a specific focus on experimental approaches used as M1/M2 test systems for macrophage phenotyping. The scope of the review encompasses commonly used experimental models, induction protocols for M1- and M2-like polarization, and key readouts, including gene-expression signatures and metabolic parameters. Particular emphasis is placed on reporter-based platforms (luciferase, BRET, fluorescent nanoparticle probes), label-free biophysical methods such as electrical impedance monitoring and metabolic profiling, and their application to dynamic, real-time assessment of macrophage phenotype in the context of tumor microenvironments and chemotherapeutic exposure. The potential of integrating reporter systems with single-cell omics, spatial transcriptomics, and patient-derived ex vivo platforms is considered, with a view to transforming M1/M2 test systems into clinically oriented assays capable of tracking macrophage programs during therapy and supporting the development of macrophage-targeted diagnostics and treatments. Full article

Protein–protein interactions (PPIs) are fundamental to viral replication, regulating processes such as assembly, genome packaging, and virion maturation. Despite their biological importance, these interactions remain challenging to study and are relatively underexploited as therapeutic targets. Split reporter systems, based on protein-fragment complementation, provide quantitative platforms to measure PPIs by reconstituting reporter activity when interacting protein partners are brought into proximity. These systems can be applied in vitro and in live cells which enables detection of dynamic and multimeric interactions in physiologically relevant contexts. Major classes of split reporter systems include β-lactamase, alkaline phosphatase, luciferase-based platforms, green fluorescent protein, and horseradish peroxidase. Assay performance depends on factors such as fusion protein stability, expression levels, and reporter kinetics, which influence sensitivity, dynamic range, and reliability. These approaches have been applied to study viral protein interactions across diverse systems, including HIV-1 matrix and nucleocapsid proteins, flaviviral capsid proteins, hepatitis B virus core protein, and chikungunya virus capsid. Split reporter assays also enable high-throughput screening for small-molecule inhibitors that disrupt viral PPIs and multimerization. This provides a functional readout linked to viral replication. Despite the challenges that exist in assay optimization and protein stability, the sensitivity and versatility of these systems provide a framework to interrogate viral protein interactions and support the development of antiviral therapeutics.: Full article

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) involves the interplay of hepatic lipid accumulation and immune-mediated inflammatory signaling, yet human-relevant in vitro systems that capture both processes simultaneously in a scalable format remain limited. The objective of this study was to develop and characterize a matrix-free 3D hepatocyte–macrophage co-culture model enabling simultaneous assessment of lipid accumulation and NF-κB-mediated inflammatory activation under glucolipotoxic stress. Methods: A 3D liver co-culture model was established by combining HepG2 hepatocyte-like cells with phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 macrophage-like cells stably expressing a NF-κB–Luc2 reporter. Spheroids were generated using a hanging-drop method in standard 96-well plates and matured for 8–10 days. Mature spheroids were subjected to acute 24 h glucolipotoxic challenge combining high glucose and palmitic acid and assessed for neutral lipid accumulation, NF-κB reporter activation (luciferase), and macrophage marker expression (qPCR). Results: Time-course characterization demonstrated progressive hepatocyte marker remodeling (albumin, alpha-fetoprotein, CYP3A4) and dynamic macrophage phenotype shifts (CD14, CD206, MARCO, TREM2). Acute glucolipotoxic challenge induced dose-dependent increases in neutral lipid accumulation and NF-κB reporter activation, accompanied by coordinated macrophage-associated transcriptional changes consistent with lipid-handling and tissue-remodeling programs. Post-challenge metabolic activity was retained under the selected stress conditions. As a proof-of-concept demonstration, three botanical extracts showed distinct attenuation profiles across the lipid and inflammatory endpoints. Conclusions: This 3D hepatocyte–macrophage co-culture model provides orthogonal readouts of steatosis and NF-κB-mediated inflammatory activation under glucolipotoxic stress, offering a reproducible, fit-for-purpose screening tool for investigating early glucolipotoxic hepatic responses and evaluating candidate compounds in a defined in vitro setting. Full article

Background: Hair loss (alopecia) is primarily driven by the premature transition of hair follicles from the anagen (growth) to the catagen (regression) phase. Intracellular calcium signaling is implicated in hair follicle biology, including the regulation of Wnt/β-catenin activity and the modulation of catagen-associated factors such as TGF-β2. Cyclic ADP-ribose (cADPR), a calcium-mobilizing second messenger synthesized by CD38, has recently emerged as a potential modulator of intracellular calcium dynamics. This study investigated whether cADPR is associated with changes in intracellular calcium retention and anagen-associated signaling pathways in human hair follicle dermal papilla cells (HHDPCs). Methods: HHDPCs were treated with cADPR (0.001–0.5 ppm) and analyzed for cell viability, intracellular calcium retention, β-catenin-dependent transcription, and the gene expression of LEF-1 and TGF-β2. Cell viability was evaluated using the MTT assay, intracellular calcium content was quantified by ICP–OES, β-catenin activation was assessed using a TOPFlash luciferase assay, and gene expression was measured by qRT-PCR. Results: cADPR did not induce marked cytotoxicity, maintaining more than 98% cell viability across all concentrations. The highest response was observed at 0.05 ppm, at which intracellular calcium content remained elevated for up to six hours as assessed by ICP–OES. At this concentration, β-catenin-dependent transcription increased by approximately 2.3-fold relative to control, LEF-1 expression was significantly upregulated (~2.5-fold), and TGF-β2 expression was significantly downregulated (~0.3-fold). These responses showed an overall concentration-dependent trend across assays. Conclusions: These findings indicate an association between cADPR treatment and modulation of intracellular calcium retention and anagen-related signaling readouts in HHDPCs, supporting the need for further studies to establish mechanistic causality and physiological relevance. Full article

Targeting mutation-derived neoantigens is a promising strategy for personalized immunotherapies. However, identifying true neoantigens and cognate T cell receptors (TCRs) remains challenging because computational prediction of neoantigen peptides is uncertain and most tumor-infiltrating lymphocytes are bystanders rather than tumor-reactive, necessitating functional validation. Here, we developed NeoPAIR-T (Neoantigen–TCR Pairing Assay using reporter T cells), a functional assay based on co-culture of TCR–T reporter cells and autologous antigen-presenting cells (APCs) to screen neoantigen–TCR pairs. Reporter T cells are Jurkat-derived cells engineered to express a luciferase/eGFP dual reporter, providing quantitative readouts of TCR activation, while APCs are immortalized autologous cells transfected with tandem minigenes (TMGs) encoding predicted neoantigens, bypassing peptide synthesis. NeoPAIR-T also includes TCRα-knockout with targeted knock-in of candidate TCRs at the TCRβ locus to prevent mispairing and enables parallel testing of multiple reporter T cell clones co-cultured with the same APCs for efficient identification of functional pairs. Using lung cancer samples, whole-exome and RNA sequencing predicted 63 candidate peptides assembled into three TMGs. Single-cell RNA/TCR sequencing identified eight TCR clonotypes, introduced into reporter T cells and tested in parallel. Co-culture with TMG-expressing APCs revealed two functional neoantigen–TCR pairs validated by peptide assays (EC₅₀: 10^−9.2–10^−6.7 M). Collectively, NeoPAIR-T streamlines neoantigen–TCR identification for vaccine and TCR-T applications. Full article

Bluetongue virus (BTV) is the causative agent of the significant livestock disease Bluetongue (BT), which causes severe economic losses associated with its considerable impact on the health and trade of ruminants. Background/Objectives: BTV infection and vaccination against the virus typically result in the induction of antibodies with the capacity to neutralize viral infection. Classic neutralization approaches resemble the methodology applied for neutralizing antibodies (NAbs) quantification. To improve long-standing and new-generation methodologies for the quantification of NAbs or evaluation of antivirals, we offer here the development of a new luciferase-based microneutralization approach as a proof-of-concept. Methods: Central to this innovative approach is the recently generated set of replication-competent reporter-expressing recombinant BTV, where the NanoLuc luciferase protein expression serves as a quantifiable readout for viral replication. After evaluating a set of heat-inactivated serum samples with neutralizing activity (measured via SNTs), these were incubated with 100 PFU of NLuc-expressing rBTV of serotype 1, 4 or 8 and Vero cells were infected with the serum–virus mixture. Then, the luminescent signal was measured at 48 h post-infection. Results: Using the proposed NLuc-based assay and the luminescent signal in the supernatant, we could detect neutralizing activity as soon as 48 h post-infection. Importantly, we were able to observe a strong correlation between NAbs titers measured by classic microneutralization assay and by our bioluminescent approach (BTV-1 Spearman r = 0.932901; p-value < 0.0001; BTV-4 Spearman r = 0.8070192; p-value < 0.0001; BTV-8 Spearman r = 0.9983; p-value < 0.0001). In addition, the NLuc-based assay displayed a serotype-specific character potentially equivalent to classic SNT methods. Conclusions: In summary, our reporter-based microneutralization assay provides a rapid and suitable method to quantify BTV-neutralizing antibodies in serum samples of natural hosts after vaccination or infection, with a serotype-specificity equivalent to classic SNT methods. Full article

Given their role in viral polyprotein processing, viral proteases (PRs) are excellent targets for antiviral therapy. Most assays developed for screening PR inhibitors are in vitro assays, and therefore have several limitations, including the inability to account for cell permeability, toxicity and the need for compounds activation within cells. The development of cellular reporters overcoming these limitations is therefore highly desirable. In this study, we developed two different Bioluminescence Resonance Energy Transfer (BRET)-based reporters for Human Immunodeficiency virus-1 (HIV-1) PR, allowing the simultaneous monitoring of cell viability and HIV-1 PR activity. The reporters employ two different BRET pairs as donor and acceptor moieties: Renilla luciferase (RLuc) with Yellow Fluorescent Protein (YFP), and Nano luciferase (NLuc) with mNeonGreen (mNG), both linked by the HIV-1 p2/p7 cleavage site. While both reporters specifically detected HIV-1 protease activity, mNG-p2/p7-NLuc exhibited higher sensitivity, increased energy transfer and better spectral separation between donor and acceptor emissions, resulting in a significantly higher BRET ratio. mNG-p2/p7-NLuc was used to quantify the effect of a panel of protease inhibitors in living cells, assessing simultaneously cell viability and HIV-1 PR activity. Additionally, it was employed to measure the potency of well-known HIV-1 PR inhibitors. Together, these findings demonstrate the utility of the mNG-p2/p7-NLuc reporter as a cell-based tool for the evaluation of HIV-1 PR activity and inhibitor efficacy. Its dual-readout capability provides a valuable platform for antiviral drug screening in physiologically relevant conditions. Full article

Studying influenza A viruses (IAVs) requires secondary experimental procedures to detect the presence of the virus in infected cells or animals. The ability to generate recombinant (r)IAV using reverse genetics techniques has allowed investigators to generate viruses expressing foreign genes, including fluorescent and luciferase proteins. These rIAVs expressing reporter genes have allowed for easily tracking viral infections in cultured cells and animal models of infection without the need for secondary approaches, representing an excellent option to study different aspects in the biology of IAV where expression of reporter genes can be used as a readout of viral replication and spread. Likewise, these reporter-expressing rIAVs provide an excellent opportunity for the rapid identification and characterization of prophylactic and/or therapeutic approaches. To date, rIAV expressing reporter genes from different viral segments have been described in the literature. Among those, rIAV expressing reporter genes from the viral NS segment have been shown to represent an excellent option to track IAV infection in vitro and in vivo, eliminating the need for secondary approaches to identify the presence of the virus. Here, we summarize the status on rIAV expressing traceable reporter genes from the viral NS segment and their applications for in vitro and in vivo influenza research. Full article

CAR-T cell-based therapies have demonstrated remarkable efficacy in treating malignant cancers, especially liquid tumors, and are increasingly being evaluated in clinical trials for solid tumors. With the FDA’s initiative to advance alternative methods for drug discovery and development, full human ex vivo assays are increasingly essential for precision CAR-T development. However, prevailing ex vivo CAR-T cell-mediated cytotoxicity assays are limited by their use of radioactive materials, lack of real-time measurement, low throughput, and inability to automate, among others. To address these limitations, we optimized the assay using multimodality imaging methods, including bioluminescence, impedance tracking, phase contrast, and fluorescence, to track CAR-T cells co-cultured with CD19, CD20, and HER2 luciferase reporter cancer cells in real-time. Additionally, we varied the ratio of CAR-T cells to cancer cells to determine optimal cytotoxicity readouts. Our findings demonstrated that the CAR-T cell group effectively attacked cancer cells, and the optimized assay provided superior temporal and spatial precision measurements of ex vivo CAR-T killing of cancer cells, confirming the reliability, consistency, and high throughput of the optimized assay. Full article

Water is indispensable for life, yet many lack access to clean drinking water, resulting in fatalities from waterborne bacterial infections. Precise assessment of microbial abundance and viability in natural aquatic environments is vital. Adenosine triphosphate (ATP) serves as a parameter for viability assessments due to its presence in viable bacterial cells as an energy carrier. Traditional ATP detection methods involve chemical or enzymatic extraction, followed by measurement of light emission via the Luciferin–Luciferase complex. However, these methods are costly, present a low stability, require specialized equipment, and entail complex sample pretreatment. To overcome these limitations, we developed a biosensor based on aptamers, nucleic acid sequences with specific target-molecule-binding capabilities. Aptamers offer advantages such as an enhanced stability, a lower cost, and ease of design compared to antibodies. Recently, ATP has been used for aptamer selection testing. Our proposed biosensor utilizes a structure-switching ATP-binding DNA nanoswitch with two functional domains: a catalytic DNA-zyme domain and an ATP-binding aptamer domain. In the presence of ATP, its binding to the aptamer domain triggers the activation of the DNA-zyme domain, which is exploited for chemiluminescence (CL) detection. Integrating functional DNA biosensors with microfluidic paper-based analytical devices (µPADs) holds promise for point-of-care (POC) applications. However, achieving proper DNA binding on paper remains challenging, often requiring solution-based assay protocols, leaving µPADs for final signal readout. Here, we introduce an origami µPAD with preloaded dried reagents, allowing for on-paper assay execution upon sample addition and proper folding. Paper functionalization strategies and assay protocols were optimized to ensure simple and straightforward detection of ATP, employing a portable charge-coupled device (CCD) camera for CL detection. Calibration curves plotted against the logarithm of ATP concentration in the range of 1 to 500 µM facilitated determination of the assay’s limit of detection (LOD), which was found to be 3 µM. Full article

A wound healing model was developed to elucidate the role of mesenchymal-matrix-associated transglutaminase 2 (TG2) in keratinocyte re-epithelialisation. TG2 drives keratinocyte migratory responses by activation of disintegrin and metalloproteinase 17 (ADAM17). We demonstrate that epidermal growth factor (EGF) receptor ligand shedding leads to EGFR-transactivation and subsequent rapid keratinocyte migration on TG2-positive ECM. In contrast, keratinocyte migration was impaired in TG2 null conditions. We show that keratinocytes express the adhesion G-protein-coupled receptor, ADGRG1 (GPR56), which has been proposed as a TG2 receptor. Using ADAM17 activation as a readout and luciferase reporter assays, we demonstrate that TG2 activates GPR56. GPR56 activation by TG2 reached the same level as observed with an agonistic N-GPR56 antibody. The N-terminal GPR56 domain is required for TG2-regulated signalling response, as the constitutively active C-GPR56 receptor was not activated by TG2. Signalling required the C-terminal TG2 β-barrel domains and involved RhoA-associated protein kinase (ROCK) and ADAM17 activation, which was blocked by specific inhibitors. Cell surface binding of TG2 to the N-terminal GPR56 domain is rapid and is associated with TG2 and GPR56 endocytosis. TG2 and GPR56 represent a ligand receptor pair causing RhoA and EGFR transactivation. Furthermore, we determined a binding constant for the interaction of human TG2 with N-GPR56 and show for the first time that only the calcium-enabled “open” TG2 conformation associates with N-GPR56. Full article

In this study, a series of new artificial luciferases (ALucs) was created using sequential insights on missing peptide blocks, which were revealed using the alignment of existing ALuc sequences. Through compensating for the missing peptide blocks in the alignment, 10 sibling sequences were artificially fabricated and named from ALuc55 to ALuc68. The phylogenetic analysis showed that the new ALucs formed an independent branch that was genetically isolated from other natural marine luciferases. The new ALucs successfully survived and luminesced with native coelenterazine (nCTZ) and its analogs in living mammalian cells. The results showed that the bioluminescence (BL) intensities of the ALucs were interestingly proportional to the length of the appended peptide blocks. The computational modeling revealed that the appended peptide blocks created a flexible region near the active site, potentially modulating the enzymatic activities. The new ALucs generated various colors with maximally approximately 90 nm redshifted BL spectra in orange upon reaction with the authors’ previously reported 1- and 2-series coelenterazine analogs. The utilities of the new ALucs in bioassays were demonstrated through the construction of single-chain molecular strain probes and protein fragment complementation assay (PCA) probes. The success of this study can guide new insights into how we can engineer and functionalize marine luciferases to expand the toolbox of optical readouts for bioassays and molecular imaging. Full article

The basidiomycete Ustilago maydis is a well-characterized model organism for studying pathogen–host interactions and of great interest for a broad spectrum of biotechnological applications. To facilitate research and enable applications, in this study, three luminescence-based and one enzymatic quantitative reporter were implemented and characterized. Several dual-reporter constructs were generated for ratiometric normalization that can be used as a fast-screening platform for reporter gene expression, applicable to in vitro and in vivo detection. Furthermore, synthetic bidirectional promoters that enable bicisitronic expression for gene expression studies and engineering strategies were constructed and implemented. These noninvasive, quantitative reporters and expression tools will significantly widen the application range of biotechnology in U. maydis and enable the in planta detection of fungal infection. Full article

Bioluminescence (BL) is an excellent optical readout for bioassays and molecular imaging. Herein, we accomplished new near infrared bioluminescence resonance energy transfer (NIR-BRET) templates for monitoring molecular events in cells with higher sensitivity. We first identified the best resonance energy donor for the NIR-BRET templates through the characterization of many coelenterazine (CTZ)–marine luciferase combinations. As a result, we found that NLuc–DBlueC and ALuc47–nCTZ combinations showed luminescence in the blue emission wavelength with excellent BL intensity and stability, for example, the NLuc–DBlueC and ALuc47–nCTZ combinations were 17-fold and 22-fold brighter than their second highest combinations, respectively, and were stably bright in living mammalian cells for at least 10 min. To harness the excellent BL properties to the NIR-BRET systems, NLuc and ALuc47 were genetically fused to fluorescent proteins (FPs), allowing large “blue-to-red” shifts, such as LSSmChe, LSSmKate2, and LSSmNep (where LSS means Large Stokes Shift). The excellent LSSmNep–NLuc combination showed approximately 170 nm large resonance energy shift from blue to red. The established templates were further utilized in the development of new NIR-BRET systems for imaging steroid hormone activities by sandwiching the ligand-binding domain of a nuclear receptor (NR-LBD) between the luciferase and the FP of the template. The NIR-BRET systems showed a specific luminescence signal upon exposure to steroid hormones, such as androgen, estrogen, and cortisol. The present NIR-BRET templates are important additions for utilizing their advantageous imaging of various molecular events with high efficiency and brightness in physiological samples. Full article

Japanese encephalitis virus (JEV) is the major cause of viral encephalitis in humans throughout Asia. In the past twenty years, the emergence of the genotype I (GI) JEV as the dominant genotype in Asian countries has raised a significant threat to public health security. However, no clinically approved drug is available for the specific treatment of JEV infection, and the commercial vaccines derived from the genotype III JEV strains merely provided partial protection against the GI JEV. Thus, an easy-to-perform platform in high-throughput is urgently needed for the antiviral drug screening and assessment of neutralizing antibodies specific against the GI JEV. In this study, we established a reverse genetics system for the GI JEV strain (YZ-1) using a homologous recombination strategy. Using this reverse genetic system, a gaussia luciferase (Gluc) expression cassette was inserted into the JEV genome to generate a reporter virus (rGI-Gluc). The reporter virus exhibited similar growth kinetics to the parental virus and remained genetically stable for at least ten passages in vitro. Of note, the bioluminescence signal strength of Gluc in the culture supernatants was well correlated with the viral progenies determined by viral titration. Taking advantage of this reporter virus, we established Gluc readout-based assays for antiviral drug screening and neutralizing antibody detection against the GI JEV. These Gluc readout-based assays exhibited comparable performance to the assays using an actual virus and are less time consuming and are applicable for a high-throughput format. Taken together, we generated a GI JEV reporter virus expressing a Gluc gene that could be a valuable tool for an antiviral drug screening assay and neutralization assay. Full article