Optimizing THP-1 Macrophage Culture for an Immune-Responsive Human Intestinal Model

Assessing the differential responses in normal and inflamed in vitro intestinal models exposed to food contaminants complex mixtures

The intestinal barrier is crucial for gut health, and its dysfunction can lead to chronic inflammatory conditions. Food contaminants like pesticides, heavy metals, mycotoxins, heterocyclic aromatic amines (HAAs), and polycyclic aromatic hydrocarbons (PAHs) may worsen these conditions. However, research often overlooks the complex interactions between contaminants and the different cells in the intestine. This study explores the effects of repeated exposure to a mixture of 45 food contaminants on a triculture cell model (Caco-2/HT29-MTX monolayers and THP-1 cells) under normal and inflamed conditions. Two exposure scenarios were tested: a low-level mixture (LOW) reflecting daily diet exposure and a worst-case (WS) scenario. Cytotoxicity, barrier integrity, the expression of inflammation, oxidative stress, and intestinal barrier-related genes, as well as intestinal compounds absorption, were assessed. LOW and WS tested mixtures were confirmed to be non-cytotoxic to the monolayer. The inflamed model was validated with a 23 % reduction in TEER value compared to the normal. The WS mixture caused a maximum TEER decrease of 61 % after repeated exposure. The inflamed model was more vulnerable to contaminants, though the normal also showed significant effects. Gene expression revealed modulation of inflammation and oxidative stress, indicating that even real-life levels of food contaminants exacerbate these responses. The WS mixture induced 6-8 times the expression of inflammatory cytokines IL-8 and IL-1β. No significant differences (p > 0.05) were found in contaminants absorption between the models, but the absorption patterns align with known data. These findings enhance understanding of the intestinal effects of exposure to food contaminant mixtures in the diet.

Methyl-esterification, degree of polymerization and ∆4,5-unsaturation of galacturonic acid oligosaccharides as determinants of immunomodulation

In recent years, immunomodulation by pectin and pectin-derived galacturonic acid oligosaccharides has been the subject of wide-spread scientific research due to the potential of different pectin structures as bioactive biomolecules. Yet, gaps remain in understanding the structure-dependent immunomodulation of galacturonic acid. This study describes in vitro immunomodulatory effects of well-characterized galacturonic acid oligosaccharides. Both methyl-esterified and non-methyl-esterified galacturonic acid oligosaccharides with a saturated non-reducing end (degree of polymerization 1-10) significantly induced cytokine production by THP-1 macrophages and directly activated TLR2 and TLR4 in transfected HEK-293 cells, even when accounting for minor endotoxin contamination. In contrast, both methyl-esterified and non-methyl-esterified galacturonic acid oligosaccharides with a Δ4,5-unsaturated non-reducing end (degree of polymerization 1-7) did not activate TLR2 and TLR4 and led to significantly reduced cytokine production (p < 0.05), suggesting Δ4,5-(un)saturation as a pivotal factor for immunomodulation by galacturonic acid oligosaccharides. Exposure to non-methyl-esterified saturated galacturonic acid oligosaccharides resulted in significantly lower TNF-α production, IL-1β production and TLR4 activation (p < 0.05) compared to methyl-esterified saturated galacturonic acid oligosaccharides, while IL-10 production and TLR2 activation remained unchanged. These findings establish galacturonic acid oligosaccharides as versatile immunomodulators with TLR2 and TLR4 binding capacity, fit for different immunomodulatory applications depending on their structural characteristics.

Exposure of Polystyrene Nano- and Microplastics in Increasingly Complex In Vitro Intestinal Cell Models

With the rise in global plastic production and the presence of plastic waste in the environment, microplastics are considered an emerging environmental contaminant. Human exposure and the impact of microplastics on human health are not well studied. Recent studies have observed the presence of microplastics in human tissues and several studies have noted toxicity in in vitro and in vivo mammalian models. We examined the impact of polystyrene nano- and microplastics in increasingly complex intestinal cell models. Using an undifferentiated Caco-2 mono-culture model, we assessed particle association, cytotoxicity, and particle clearance/retention, whereas in differentiated mono- and tri-culture transwell models, we assessed membrane integrity and particle translocation. Only 50 nm and 500 nm particles were internalized in the undifferentiated cells; however, no signs of cellular toxicity were observed at any concentrations tested. Additionally, polystyrene particles had no impact on barrier integrity, but the 50 nm particles were able to cross to the basolateral side, albeit attenuated in the tri-culture model that had a mucus layer. This study reduced some of the variability common to MNPL testing across various in vitro models, but further testing is needed to fully understand the potential effects of human MNPL exposure.

Outer membrane vesicles from Pseudomonas aeruginosa induce autophagy-regulated pyroptosis in THP-1 cells

Outer membrane vesicles derived from Pseudomonas aeruginosa (PA-OMVs) play a crucial role in bacterial pathogenesis, mediating immune modulation and inflammation. Autophagy, a process that degrades damaged organelles, and pyroptosis, a form of programmed cell death, both regulate immune responses and contribute to infection defense. However, the relationship between PA-OMVs, autophagy, and pyroptosis remains insufficiently explored, particularly regarding their regulatory mechanisms. This study investigates how PA-OMVs influence cellular autophagy and pyroptosis, with the aim of identifying potential therapeutic strategies for infectious diseases. Bulk RNA sequencing and bioinformatics analysis were conducted on cells treated with PA-OMVs. Autophagy inhibitors, chloroquine (CQ) and 3-methyladenine (3-MA), were used to explore their effects on pyroptosis, with RT-PCR and ELISA applied to assess pyroptosis levels. The results revealed a complex interplay between autophagy and pyroptosis, with PA-OMVs modulating key immune and inflammatory pathways. Autophagy inhibition decreased the expression of pyroptosis markers, suggesting a regulatory role. These findings highlight the potential of targeting the autophagy-pyroptosis axis for new infection control strategies and vaccine development.

Malignant behaviors and immune response in melanoma: Epstein-Barr virus induced gene 3 as a therapeutic target based on an in-vitro exploration

Background

Epstein-Barr virus induced gene 3 (EBI3), a member of the IL-12 family, is known to be involved in malignant progression in a variety of cancers, but its role in melanoma is unclear. The aim of this study was to explore the effects of EBI3 on the malignant phenotype melanoma to reveal its potential as a therapeutic target.

Methods

In this study, we used bioinformatics to analyze the expression of EBI3 in pan-cancer and verified its expression level in melanoma cells by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Subsequently, the effects of EBI3 knockdown on cell proliferation, migration and invasion were detected using the Cell Counting Kit-8 (CCK-8) and Transwell assays. Changes in immune-related cytokines were detected by ELISA, and macrophage polarization was observed using immunofluorescence. Finally, the phosphorylation levels of signaling pathways such as Smad3, STAT6 and cGAS-STING were analyzed by Western blot.

Results

EBI3 was evidently highly-expressed in melanoma, and silencing of EBI3 could visibly suppress the survival and migration/invasion of melanoma cells, concurrent with the increased levels of BAX and CDH1 and the decreased expressions of BCL2 and CDH2. Meanwhile, EBI3 knockdown diminished the phosphorylation levels of both Smad3 and STAT6 and the levels of immune response-relevant cytokines in melanoma cells, while aggravating the macrophage M1 polarization and the expression of cGAS, p-STING and p-IRE1 α in THP-1 monocyte-derived macrophages co-cultured with EBI3-silenced melanoma cells.

Conclusion

This study filled the blank on the involvement of EBI3 in melanoma, hinting the possibility of controlling EBI3 as a therapeutic strategy in the management of melanoma.

Poly-D,L-Lactic Acid Fillers Increase Subcutaneous Adipose Tissue Volume by Promoting Adipogenesis in Aged Animal Skin

During aging, subcutaneous white adipose tissue (sWAT) thickness and the adipogenic potential of adipose-derived stem cells (ASCs) decline. Poly-D,L-lactic acid (PDLLA) fillers are commonly used to restore diminished facial volume. Piezo1 increases polarizing macrophages towards the M2 phenotype, which promotes the secretion of fibroblast growth factor 2 (FGF2), thereby increasing ASC survival. This study evaluated whether PDLLA enhances adipogenesis in ASCs by modulating M2 polarization in an in vitro senescence model and in aged animals. Lipopolysaccharide (LPS)-induced senescent macrophages showed decreased Piezo1, which was upregulated by PDLLA. CD163 (an M2 marker) and FGF2 were downregulated in senescent macrophages but were upregulated by PDLLA. We evaluated whether reduced FGF2 secretion from senescent macrophages affects ASCs by applying conditioned media (CM) from macrophage cultures to ASCs. CM from senescent macrophages decreased ERK1/2 and proliferation in ASCs, both of which were restored by CM from PDLLA-stimulated senescent macrophages. Adipogenesis inducers (PPAR-γ and C/EBP-α) were downregulated by CM from senescent macrophages but upregulated by CM from PDLLA-stimulated senescent macrophages in ASCs. Similar patterns were observed in aged animal adipose tissue. PDLLA increased Piezo1 activity, M2 polarization, and FGF2 levels. PDLLA also enhanced ERK1/2, cell proliferation, PPAR-γ, and C/EBP-α expression, leading to increased adipose tissue thickness. In conclusion, our study showed that PDLLA increased adipose tissue thickness by modulating adipogenesis.

Amplified response of drug-induced liver fibrosis via immune cell co-culture in a 3D in vitro hepatic fibrosis model

Liver fibrosis, a critical consequence of chronic liver diseases, is characterized by excessive extracellular matrix (ECM) deposition driven by inflammation. This process involves complex interactions among hepatocytes, hepatic stellate cells (HSCs), and Kupffer cells, the liver's resident macrophages. Kupffer cells are essential in initiating fibrosis through the release of pro-inflammatory cytokines that activate HSCs. Although various in vitro liver fibrosis models have been developed, there is a lack of models that include the immune environment of the liver to clarify the influence of immune cells on the progression of liver fibrosis. We developed an in vitro liver fibrosis model by co-culturing hepatocytes (HepaRG), a hepatic stellate cell line (LX-2), and macrophages (differentiated THP-1). The effects of liver fibrosis inducers, transforming growth factor-beta1 (TGF-β1) and methotrexate (MTX), on the inflammatory response and stellate cell activation were evaluated in this triple co-culture model. A triple co-culture condition was developed as a 3D in vitro model using gelatin methacrylate (GelMA), offering a more biomimetic environment and achieving liver fibrosis via immune cell activation associated ECM deposition. In this study, the developed triple co-culture model has the potential to elucidate cell progression roles in liver fibrosis and can be applied in drug screening and toxicity assessments targeting liver fibrosis.

Mangiferin Represses Inflammation in Macrophages Under a Hyperglycemic Environment Through Nrf2 Signaling

Inflammation in macrophages is exacerbated under hyperglycemic conditions, contributing to chronic inflammation and impaired wound healing in diabetes. This study investigates the potential of mangiferin, a natural polyphenol, to alleviate this inflammatory response by targeting a redox-sensitive transcription factor, nuclear factor erythroid 2-related factor 2 (Nrf2). Mangiferin, a known Nrf2 activator, was evaluated for its ability to counteract the hyperglycemia-induced inhibition of Nrf2 and enhance antioxidant defenses. The protective effects of mangiferin on macrophages in a hyperglycemic environment were assessed by examining the expression of Nrf2, NF-κB, NLRP3, HO-1, CAT, COX-2, IL-6, and IL-10 through gene and protein expression analyses using qPCR and immunoblotting, respectively. The mangiferin-mediated nuclear translocation of Nrf2 was evidenced, leading to a robust antioxidant response in macrophages exposed to a hyperglycemic microenvironment. This activation suppressed NF-κB signaling, reducing the expression of pro-inflammatory mediators such as COX-2 and IL-6. Additionally, mangiferin decreased NLRP3 inflammasome activation and reactive oxygen species accumulation in hyperglycemia exposed macrophages. Our findings revealed that mangiferin alleviated hyperglycemia-induced reductions in AKT phosphorylation, highlighting its potential role in modulating key signaling pathways. Furthermore, mangiferin significantly enhanced the invasiveness and migration of macrophages in a hyperglycemic environment, indicating its potential to improve wound healing. In conclusion, this study suggests that mangiferin may offer a promising therapeutic approach for managing inflammation and promoting wound healing in diabetic patients by regulating Nrf2 activity in hyperglycemia-induced macrophages.

Introducing FISCAS, a Tool for the Effective Generation of Single Cell MALDI-MSI Data

We introduce Fluorescence Integrated Single-Cell Analysis Script (FISCAS), which combines fluorescence microscopy with MALDI-MSI to streamline single-cell analysis. FISCAS enables automated selection of tight measurement regions, thereby reducing the acquisition of off-target pixels, and makes use of established algorithms for cell segmentation and coregistration to rapidly compile single-cell spectra. MALDI-compatible staining of membranes, nuclei, and lipid droplets allows the collection of fluorescence data prior to the MALDI-MSI measurement on a timsTOF fleX MALDI-2. Usefulness of the software is demonstrated by the example of THP-1 cells during stimulated differentiation into macrophages at different time points. In this proof-of-principle study, FISCAS was used to automatically generate single-cell mass spectra along with a wide range of morphometric parameters for a total number of roughly 1300 cells collected at 24, 48, and 72 h after the onset of stimulation. Data analysis of the combined morphometric and single-cell mass spectrometry data shows significant molecular heterogeneity within the cell population at each time point, indicating an independent differentiation of each individual cell rather than a synchronized mechanism. Here, the grouping of cells based on their molecular phenotype revealed an overall clearer distinction of the different phases of differentiation into macrophages and delivered an increased number of lipid signals as possible markers compared with traditional bulk analysis. Utilizing the linkage between mass spectrometric data and fluorescence microscopy confirmed the expected positive correlation between lipid droplet staining and the overall signal for triacylglyceride (TG), demonstrating the usefulness of this multimodal approach.

Hyaluronic Acid Viscosupplement Modulates Inflammatory Mediators in Chondrocyte and Macrophage Coculture via MAPK and NF-κB Signaling Pathways

Osteoarthritis (OA) is a chronic musculoskeletal disorder characterized by cartilage degeneration and synovial inflammation. Paracrine interactions between chondrocytes and macrophages play an essential role in the onset and progression of OA. In this study, in replicating the inflammatory response during OA pathogenesis, chondrocytes were treated with interleukin-1β (IL-1β), and macrophages were treated with lipopolysaccharide and interferon-γ. In addition, a coculture system was developed to simulate the biological situation in the joint. In this study, we examined the impact of hyaluronic acid (HA) viscosupplement, particularly Hyruan Plus, on chondrocytes and macrophages. Notably, this viscosupplement has demonstrated promising outcomes in reducing inflammation; however, the underlying mechanism of action remains elusive. The viscosupplement attenuated inflammation, showing an inhibitory effect on nitric oxide production, downregulating proinflammatory cytokines such as matrix metalloproteinases (MMP13 and MMP3), and upregulating the expression levels of type II collagen and aggrecan in chondrocytes. HA also reduced the expression level of inflammatory cytokines such as IL-1β, TNF-α, and IL-6 in macrophages, and HA exerted an overall protective effect by partially suppressing the MAPK pathway in chondrocytes and p65/NF-κB signaling in macrophages. Therefore, HA shows potential as a viscosupplement for treating arthritic joints.

Single-Cell Untargeted Lipidomics Using Liquid Chromatography and Data-Dependent Acquisition after Live Cell Selection

We report the development and validation of an untargeted single-cell lipidomics method based on microflow chromatography coupled to a data-dependent mass spectrometry method for fragmentation-based identification of lipids. Given the absence of single-cell lipid standards, we show how the methodology should be optimized and validated using a dilute cell extract. The methodology is applied to dilute pancreatic cancer and macrophage cell extracts and standards to demonstrate the sensitivity requirements for confident assignment of lipids and classification of the cell type at the single-cell level. The method is then coupled to a system that can provide automated sampling of live, single cells into capillaries under microscope observation. This workflow retains the spatial information and morphology of cells during sampling and highlights the heterogeneity in lipid profiles observed at the single-cell level. The workflow is applied to show changes in single-cell lipid profiles as a response to oxidative stress, coinciding with expanded lipid droplets. This demonstrates that the workflow is sufficiently sensitive to observing changes in lipid profiles in response to a biological stimulus. Understanding how lipids vary in single cells will inform future research into a multitude of biological processes as lipids play important roles in structural, biophysical, energy storage, and signaling functions.

A Lacticaseibacillus rhamnosus secretome induces immunoregulatory transcriptional, functional and immunometabolic signatures in human THP-1 monocytes

Macrophage responses to activation are fluid and dynamic in their ability to respond appropriately to challenges, a role integral to host defence. While bacteria can influence macrophage differentiation and polarization into pro-inflammatory and alternatively activated phenotypes through direct interactions, many questions surround indirect communication mechanisms mediated through secretomes derived from gut bacteria, such as lactobacilli. We examined effects of secretome-mediated conditioning on THP-1 human monocytes, focusing on the ability of the Lacticaseibacillus rhamnosus R0011 secretome (LrS) to drive macrophage differentiation and polarization and prime immune responses to subsequent challenge with lipopolysaccharide (LPS). Genome-wide transcriptional profiling revealed increased M2-associated gene transcription in response to LrS conditioning in THP-1 cells. Cytokine and chemokine profiling confirmed these results, indicating increased M2-associated chemokine and cytokine production (IL-1Ra, IL-10). These cells had increased cell-surface marker expression of CD11b, CD86, and CX3CR1, coupled with reduced expression of the M1 macrophage-associated marker CD64. Mitochondrial substrate utilization assays indicated diminished reliance on glycolytic substrates, coupled with increased utilization of citric acid cycle intermediates, characteristics of functional M2 activity. LPS challenge of LrS-conditioned THP-1s revealed heightened responsiveness, indicative of innate immune priming. Resting stage THP-1 macrophages co-conditioned with LrS and retinoic acid also displayed an immunoregulatory phenotype with expression of CD83, CD11c and CD103 and production of regulatory cytokines. Secretome-mediated conditioning of macrophages into an immunoregulatory phenotype is an uncharacterized and potentially important route through which lactic acid bacteria and the gut microbiota may train and shape innate immunity at the gut-mucosal interface.

Exploiting the predictive power of educated spheroids to detect immune-mediated idiosyncratic drug-induced liver injury: the case of troglitazone

Idiosyncratic drug-induced liver injury (iDILI) is a major concern in drug development because its occurrence is unpredictable. Presently, iDILI prediction is a challenge, and cell toxicity is observed only at concentrations that are much higher than the therapeutic doses in preclinical models. Applying a proprietary cell educating technology, we developed a person-dependent spheroid system that contains autologous educated immune cells that can detect iDILI risk at therapeutic concentrations. Integrating this system into a high-throughput screening platform will help pharmaceutical companies accurately detect the iDILI risk of new molecules de-risking drug development.