Monocytic Cell Line THP-1 Research Articles

Preparation and Complex Characterisation of Stabilised Gold Nanoparticles: Biodistribution and Application for High Resolution In Vivo Imaging

The Turkevich method was optimized to prepare gold nanoparticles (AuNP) stabilized by polyethyleneglycol (PEG) for µCT. Using various independent modalities, we thoroughly characterized the optimized PEG-AuNPs. Here, we show that PEG-AuNPs are retained in the blood and provide a high contrast in the high-resolution µCT imaging of blood vessels and inner organs. The biodistribution is characterized by prolonged circulation in the blood and accumulation in the liver, spleen and skin. The accumulation of AuNP in the skin resulted in the blue discoloration of eyes and the whole skin. In vitro experiments using a leukemic monocyte THP-1 cell line model expressing high levels of NLRP3 demonstrated that the NLRP3inflammasome was not activated by PEG AuNP. Over 9 months, the mice were scanned by µCT and were in good health. Scans in mice using PEG-stabilized AuNPs in this study were sharper, with a higher contrast, when compared to a commercial contrasting agent at the same dose. The PEG-AuNPs were morphologically and chemically stable for at least two years when stored in the refrigerator.

The Effects of the oxLDL/β2GPI/anti-β2GPI Complex on Macrophage Autophagy and its Mechanism.

Previous research has established that the oxidized low-density lipoprotein/β2-glycoprotein I/anti-β2-glycoprotein I antibody (oxLDL/β2GPI/anti-β2GPI) complex can stimulate macrophages to secrete molecules associated with atherosclerosis (AS), such as monocyte chemotactic protein 1 (MCP-1), tissue factor (TF), and tumor necrosis factor-α (TNF-α). This complex also enhances the uptake of oxLDL, thereby accelerating foam cell formation through the Toll-like receptor-4/nuclear factor kappa B (TLR4/NF-κB) pathway. Given the critical role of macrophage autophagy in the instability of vulnerable atherosclerotic plaques, it is imperative to investigate whether the oxLDL/β2GPI/anti-β2GPI complex influences macrophage autophagy in AS. This study aims to elucidate the effects and underlying mechanisms of the oxLDL/β2GPI/anti-β2GPI complex on macrophage autophagy in AS. Experiments were conducted using murine macrophage RAW264.7 cells and the human monocytic cell line THP-1. Western blot analysis was employed to determine the expressions of autophagy-associated markers and signaling pathway proteins. Autophagosomes were detected through mRFP-GFP-LC3 adenoviral transfection and transmission electron microscopy (TEM). Treatment of macrophages with the oxLDL/β2GPI/anti-β2GPI complex resulted in decreased expressions of Beclin1 and LC3 proteins, alongside an upregulation of SQSTM1/P62 protein expression. Additionally, there was a reduction in the number of autophagosomes and autolysosomes. An increase in the phosphorylation levels of phosphoinositide-3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) was also observed. Notably, the expressions of autophagy-associated markers were partially restored when the TLR4/NF-κB and PI3K/AKT/mTOR pathways were inhibited by their respective inhibitors. Our findings indicate that the oxLDL/β2GPI/anti-β2GPI complex inhibits macrophage autophagy in AS via the TLR4/NF-κB and PI3K/AKT/mTOR signaling pathways.

CKIP-1 inhibits M2 macrophage polarization to suppress the progression of gastric cancer by inactivating JAK/STAT3 signaling.

Gastric cancer (GC) is a frequently occurring malignancy with poor prognosis. Casein kinase 2 interacting protein-1 (CKIP-1) is a PH domain-containing protein implicated in regulating tumorigenesis and macrophage homeostasis. This study aimed to elucidate the role and potential mechanism of CKIP-1 in the progression of GC. CKIP-1 expression in GC tumor and para-carcinoma tissues was detected using RT-qPCR. Then, human monocyte cell line THP-1 was treated with PMA, interleukin (IL)-4 and IL-13 to induce M2-polarized macrophages. CD206, arginase-1 (Arg-1) and transforming growth factorβ1 (TGFβ1) expression in M2-polarized macrophages with or without CKIP-1 overexpression was evaluated. Moreover, GC cell lines (MKN45 and HGC27 cells) were co-cultured with CKIP-1-overexpressed M2-polarized macrophages, and the viability, migration and invasion of GC cells were measured. Additionally, immunoblotting assessed the expression of JAK/STAT3 signaling-related proteins and STAT3 agonist Colivelin was used to treat GC cells to perform the rescue experiments to analyze the changes of malignant phenotypes of GC cells. Results showed that CKIP-1 was downregulated in GC tissues and M2-polarized macrophages. CKIP-1 overexpression inhibited M2 macrophage polarization and decreased TGFβ1 secretion. Besides, elevated CKIP-1 expression in M2-polarized macrophages inhibited the viability, migration and invasion of GC cells. Furthermore, CKIP-1 overexpression inactivated JAK2/STAT3 signaling in GC cells by inhibiting TGFβ1 level. Specifically, Colivelin treatment abrogated the influences of CKIP-1 upregulation on the malignant phenotypes of GC cells. Collectively, CKIP-1 inhibits M2 macrophage polarization to suppress the progression of GC by inactivating JAK/STAT3 signaling pathway.

Impact of Senescent Cell-Derived Extracellular Vesicles on Innate Immune Cell Function.

Extracellular vesicles (EVs) are components of the senescence-associated secretory phenotype (SASP) that influence cellular functions via their cargo. Here, the interaction between EVs derived from senescent (SEVs) and non-senescent (N-SEVs) fibroblasts and the immune system is investigated. Via endocytosis, SEVs are phagocytosed by monocytes, neutrophils, and B cells. Studies with the monocytic THP-1 cell line find that pretreatment with SEVs results in a 32% (p < 0.0001) and 66% (p < 0.0001) increase in lipopolysaccharide (LPS)-induced tumor necrosis factor-alpha (TNF-α) production when compared to vehicle control or N-SEVs respectively. Interestingly, relative to vehicle control, THP-1 cells exposed to N-SEVs exhibit a 20% decrease in TNF-α secretion (p < 0.05). RNA sequencing reveals significant differences in gene expression in THP-1 cells treated with SEVs or N-SEVs, with vesicle-mediated transport and cell cycle regulation pathways featuring predominantly with N-SEV treatment, while pathways relating to SLITS/ROBO signaling, cell metabolism, and cell cycle regulation are enriched in THP-1 cells treated with SEVs. Proteomic analysis also reveals significant differences between SEV and N-SEV cargo. These results demonstrate that phagocytes and B cells uptake SEVs and drive monocytes toward a more proinflammatory phenotype upon LPS stimulation. SEVs may therefore contribute to the more proinflammatory immune response seen with aging.

Treatment of polyethylene microplastics degraded by ultraviolet light irradiation causes lysosome-deregulated cell death

BackgroundMicroplastics (MPs), plastic particles < 5 mm in size, are prevalent in the environment, and human exposure to them is inevitable. To assess the potential risk of MPs on human health, it is essential to consider the physicochemical properties of environmental MPs, including polymer types, size, shape, and surface chemical modifications. Notably, environmental MPs undergo degradation due to external factors such as ultraviolet (UV) rays and waves, leading to changes in their surface characteristics. However, limited knowledge exists regarding the health effects of MPs, with a specific focus on their surface degradation. This study concentrates on cytotoxic MPs with surface degradation through UV irradiation, aiming to identify the mechanisms underlying their cell toxicity.ResultsPolyethylene (PE) and surface-degraded PE achieved through UV light irradiation were employed as model MPs in this study. We explored the impact of PE and degraded PE on cell death in murine macrophage cell line RAW264.7 cells and human monocyte cell line THP-1 cells. Flow cytometric analysis revealed that degraded PE induced programmed cell death without activating caspase 3, while non-degraded PE did not trigger programmed cell death. These findings suggest that degraded PE might induce programmed cell death through mechanisms other than caspase-driven apoptosis. To understand the mechanisms of cell death, we investigated how cells responded to degraded PE-induced cellular stress. Immunofluorescence and western blotting analyses demonstrated that degraded PE induced autophagosome formation and increased p62 expression, indicating inhibited autophagy flux after exposure to degraded PE. Furthermore, degraded PE exposure led to a decrease in acidic lysosomes, indicating lysosomal dysregulation. These results imply that degraded PE induces lysosomal dysfunction, subsequently causing autophagy dysregulation and cell death.ConclusionsThis study unveils that UV-induced degradation of PE results in cell death attributed to lysosomal dysfunction. The findings presented herein provide novel insights into the effects of surface-degraded MPs on biological responses.

Characterization of macrophages associated with human skin models exposed to UV radiation.

Skin macrophages play important roles in the response to external stimuli. Human skin equivalents (HSEs) incorporating the human monocytic cell line THP-1 were fabricated to generate immunocompetent human skin models. These HSEs were used to investigate the influence of the skin microenvironment and ultraviolet A (UVA) on macrophages. Transcriptomic analysis revealed that THP-1 cells in HSEs were enriched in extracellular matrix interaction hallmark but downregulated in DNA replication hallmark. Upon UVA exposure, immunocompetent HSEs presented epidermal distortion and increased DNA double-strand breaks (DSBs). The genes associated with oxidative stress and the inflammatory response were significantly upregulated in THP-1 cells. When the photoprotective agent mycosporine-2-glycine from cyanobacteria was applied to HSEs, the incidence of UVA-induced DSBs was significantly lower, and inflammatory and UV response hallmarks were downregulated in THP-1 cells. Taken together, these results suggest that immunocompetent HSEs can be used to investigate the responses of skin-resident macrophages to external stimuli.

Increased CRHR1 expression on monocytes from patients with AA enables a pro-inflammatory response to corticotrophin-releasing hormone.

Stress may play a key role in alopecia areata (AA), though the exact interactions of stress with AA remain undefined. Corticotropin-releasing hormone (CRH), the proximal regulator of the stress axis, has been recognized as an immunomodulatory factor in tissues and peripheral blood mononuclear cells (PBMCs). We used multicolour flow cytometry to identify receptor CRHR1 expression on PBMC subsets in AA patients (n = 54) and controls (n = 66). We found that CRHR1 was primarily expressed by circulating monocytes. CRHR1 expression on monocytes was enhanced in AA compared with controls (3.17% vs. 1.44%, p = 0.002, chi-squared test). AA incidence was correlated to elevated CD14+ monocyte numbers (R = 0.092, p = 0.036) and markedly independently correlated with increased CRHR1 expression (R = 0.215, p = 0.027). High CRHR1 expression was significantly related to chronic AA (disease duration >1 year; p = 0.003, chi-squared test), and large lesion area (AA area >25%; p = 0.049, chi-squared test). We also observed enhanced percentages of active monocytes and reduced CD16+ CD3- NK cell numbers in AA patients' PBMCs (p = 0.010; 0.025, respectively). Invitro CRH treatment of PBMCs and human monocyte cell line THP-1 promoted CD86 upregulation. The findings imply that stress-related factors CRH and CRHR1 contribute to AA development and progression where higher CRHR1 expression is associated with chronic AA and larger lesions.

Cytokine secretion by in vitro cultures of lung epithelial cells, differentiated macrophages and differentiated dendritic cells incubated with pneumococci and pneumococcal extracellular vesicles.

Streptococcus pneumoniae is an important human pathogen that can colonize the respiratory tract of healthy individuals. The respiratory tract mucosa is thus the first barrier for this pathogen. In this study, we have tested three models of the respiratory epithelium with immune cells: (i) monolayer of A549 human lung epithelial cells, (ii) A549 + macrophages differentiated from the human monocytic THP-1 cell line (dMφ) and (iii) A549 + dMφ + dendritic cells differentiated from THP-1 (dDC) using a two-chamber system. Pneumococcal strains Rx1 (non-encapsulated) and BHN418 (serotype 6B) were incubated with the cells and secretion of IL-6, IL-8, IL-1β, TNF-α and IL-10 was evaluated. Overall, the models using co-cultures of A549 + dMφ and A549 + dMφ + dDC elicited higher levels of pro-inflammatory cytokines and the non-encapsulated strain elicited an earlier cytokine response. BHN418 pspA (pneumococcal surface protein A) and pspC (pneumococcal surface protein C) knockouts elicited similar cytokine secretion in the co-culture models, whereas BHN18 ply (pneumolysin) knockout induced much lower levels. The results are in accordance with the activation of the inflammasome by Ply. Finally, we evaluated pneumococcal extracellular vesicles (pEVs) in the co-culture models and observed secretion of pro-inflammatory cytokines in the absence of cytotoxicity. Since pEVs are being studied as vaccine candidate against pneumococcal infections, the co-cultures of A549 + dMφ and A549 + dMφ + dDC are simple models that could be used to evaluate pEV vaccine batches.

Effects of Three Retrograde Filling Materials on Production of Inflammatory Cytokines and Resorbing Mediators

: Root-end filling materials are typically used following endodontic surgeries, and due to their different chemical compositions, they have varying effects on the survival and differentiation of tissues around the root apex. The purpose of this in vitro study was to evaluate the effects of three retrograde filling materials—ProRoot MTA, Super ethoxy benzoic acid (EBA), and Geristore—on the production of pro-inflammatory and resorptive cytokines (RANK, RANK-L, OPG, IL-1β, and TNF-α). After mixing and setting, the experimental materials were exposed to UV rays and then applied to the prepared cells. This study used osteoblast (MG-63) and THP-1 monocyte cell lines, as well as peripheral blood monocytes (PBM). The evaluation times for RANK-L and OPG were 24 and 48 hours, while IL-1β and tumor necrosis factor (TNF-α) were evaluated at 24 hours. The RANK levels were measured using flow cytometry, and monocyte survival was assessed at different times using the MTT assay. The results were analyzed using Minitab statistical software, which indicated that the type of material significantly affected cytokine production. Exposure of monocytes to EBA resulted in a decrease in TNF-α and IL-1β secretion compared to the other groups. However, in the THP-1 cell line, there was no significant difference in the release of pro-inflammatory cytokines between the groups. Conversely, Geristore induced the highest level of RANK-L and the lowest level of OPG in cultures with the MG-63 cell line. According to the MTT assay, the viability order of the materials from early to late was Geristore &lt; EBA &lt; MTA.

Abstract MP15: Macrophage PPARα is essential to increased immune function induced by angiotensin converting enzyme (ACE).

Mice with increased macrophage expression of angiotensin converting enzyme (ACE), called ACE 10/10 mice, have a profound increase of macrophage function in response to diverse immune challenges including tumors, infection, atherosclerosis, and Alzheimer’s disease. ACE 10/10 macrophages are highly efficient in oxidative ATP generation, and they express increased amounts of peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor that controls lipid metabolism. To pinpoint the role of PPARα in increasing macrophage immune function, we used LysM-Cre-LoxP system to generate ACE 10/10 mice selectively lacking macrophage PPARα (A10-PPARα-Cre mice). This reduced macrophage fatty acid metabolism, reduced oxidative metabolism, and lowered macrophage intracellular ATP. Functionally, A10-PPARα-Cre macrophage are impaired in both adaptive and innate immunity. A10-PPARα-Cre mice have larger tumor growth of B16-F10 melanoma, less intratumor macrophages, reduced anti-tumor cytokines, and reduced generation of tumor antigen-specific CD8 + T cells. The mice also have a very attenuated anti-bacterial response to methicillin-resistant Staphylococcus aureus (MRSA) infection, with more severe MRSA tissue colonization in vivo . In addition, increasing ACE expression or adding a PPARα agonist to the human monocytic cell line THP-1 enhances tumor cell cytotoxicity, phagocytosis of bacteria, and bacterial killing. Thus, we find that elevated macrophage PPARα is absolutely required for the increased immunity of ACE 10/10 mice. This may indicate a pathway to increasing human immunity.

THP1-based cybrid cells with various mtDNA mutations differ by the ability to form inflammatory response

Most age-related human diseases are accompanied by chronic inflammation. Modern research is aimed at studying the principles of the formation of the immune response. The reasons why the local inflammatory reaction cannot be resolved and becomes a sluggish chronic form are still unknown. Immune cells secrete cytokines in response to pathogens. To avoid cell death as a result of high concentrations of cytokines and resulting tissue damage, there is a mechanism of innate immune tolerance. Innate immune tolerance involves a decrease in the secretion of proinflammatory cytokines in response to repeated exposure to a pathogen. It is known that mitochondria play an important role in the formation of the immune response. Consequently, impaired mitochondrial function can lead to impaired immune response. To control the quality of mitochondria in the cell, there is a mechanism – mitophagy. Previously, we have created cybrid lines based on the monocytic cell line THP-1. Cybrids were obtained by fusion of THP-1 cells (mitochondria were removed) with platelets from patients. Each of the cybrid lines had the THP-1 nuclear genome and an individual patient’s mitochondrial genome. In our study, we decided to study the ability of cells carrying different mitochondrial genomes to generate a proinflammatory response, as well as to form tolerance in the future. For this purpose, we chose a model of ecdotoxin tolerance. Thus, we stimulated the cybrid lines twice with lipopolysaccharide and then assessed the secretion of the cytokines TNFα, IL-1β, IL-6, IL-8, and CCL2 using ELISA. The cybrids demonstrated two levels of proinflammatory response: high and low. Moreover, cybrids with a high proinflammatory response either did or did not develop tolerance upon repeated stimulation. In our study, cells that differed from each other only in mitochondrial genome demonstrated three types of reactions upon the induction of immune tolerance to LPS. Future studies will improve our understanding of the mechanisms of mitochondrial involvement in pathological processes. It is likely that studies of deficient mitophagy and the role of certain mtDNA mutations in its development will yield promising results.

Therapeutically targeting the CALR/CD47 pathway in MPN to reactivate natural immunosurveillance mechanisms within the body to enhance treatment outcomes.

170 Background: MPNs are a group of related myeloid malignancies characterized by alterations in mature blood cell production/bone marrow environment and have a tendency to evolve into acute myeloid leukaemia. We demonstrated that CD47 blockade in combination with ruxolitinib, increased CALR expression enhancing cytotoxicity in vitro, promoting enhanced neoplastic clone clearance. With this study we describe a potential methodology for assessing effect of new compounds or combinations and the impact of modulating the immunoresponse upon myeloid malignant clones. Methods: Utilising HEL 92.1.7 and SET-2 cells (JAK2 mutated), Marimo cells (CALR mutated) and K562 cell line models; we will incubate with routine therapies (hydroxyurea, anagrelide, ruxolitinib) in combination with a range of anti-CD47 compounds (Anti-CD47 monocloncal antibodies, BET-1 inhibitors, SIRa inhibitor) and will determine the impact upon CD47 and CALR cell surface expression via flow cytometry. Monocyte derived macrophage (MDM) will be produced through Phorbol 12-myristate 13-acetate (PMA) differentiation of a monocytic Thp-1 cell line. Expression of macrophage cell surface markers (CD11b, CD14), as well as intracellular markers (CD68), will be detected by flow cytometry. MDM will then be polarized to either a pro-inflammatory M1, or anti-inflammatory M2 phenotype, with lipopolysaccharide/interferon gamma or interleukins 4 and 13, respectively. Co-culture experiments will then be undertaken to determine how different anti-CD47 therapy combination impact macrophage polarization and destruction of MPN cell lines. Results: We predict that CALR/CD47 levels on each cell line subtype will respond differently highlighting heterogeneity within MPNs and demonstrating the clear need for a more personalised immunotherapy approach. Alterations in JAK/STAT pathway and BET inhibition may hinder macrophage polarisation to the anti-tumorigenic M1 macrophage phenotype. We theorise that indirect co-culture of M1 macrophage with MPN suspension cells under different treatment modalities will enhance MPN cell death and decrease CD47 expression to a greater level than that which we expect to see in M2 polarised macrophage. We also anticipate that the M2 polarised macrophage, which dominate in the tumour microenvironment as MPN progresses, will fail to phagocytose MPN cells and may not be rescued by novel immunotherapeutics. Conclusions: Our group demonstrated the role of CD47 and CALR expression as a key mechanism and a potential target to enhance presentation of the cancer cell to the immune system, and we believe that understanding the interaction of CD47/CALR – macrophages, will drive new therapeutical approaches able to modulate the immune response and improve patients outcomes, potentially leading to complete MPN clone eradiation and cure.

Carbon Nanotube Immunotoxicity in Alveolar Epithelial Type II Cells Is Mediated by Physical Contact-Independent Cell-Cell Interaction with Macrophages as Demonstrated in an Optimized Air-Liquid Interface (ALI) Coculture Model.

There is a need for the assessment of respiratory hazard potential and mode of action of carbon nanotubes (CNTs) before their approval for technological or medical applications. In CNT-exposed lungs, both alveolar macrophages (MФs), which phagocytose CNTs, and alveolar epithelial type II cells (AECII cells), which show tissue injury, are impacted but cell-cell interactions between them and the impacted mechanisms are unclear. To investigate this, we first optimized an air-liquid interface (ALI) transwell coculture of human AECII cell line A549 (upper chamber) and human monocyte cell line THP-1 derived macrophages (lower chamber) in a 12-well culture by exposing macrophages to CNTs at varying doses (5-60 ng/well) for 12-48 h and measuring the epithelial response markers for cell differentiation/maturation (proSP-C), proliferation (Ki-67), and inflammation (IL-1β). In optimal ALI epithelial-macrophage coculture (3:1 ratio), expression of Ki-67 in AECII cells showed dose dependence, peaking at 15 ng/well CNT dose; the Ki-67 and IL-1β responses were detectable within 12 h, peaking at 24-36 h in a time-course. Using the optimized ALI transwell coculture set up with and without macrophages, we demonstrated that direct interaction between CNTs and MФs, but not a physical cell-cell contact between MФ and AECII cells, was essential for inducing immunotoxicity (proliferative and inflammatory responses) in the AECII cells.

Establishment of a stable THP-1 cell line expressing PSMB9-eGFP-His protein and detection of immunoproteasome activity

The ubiquitin/proteasome system (UPS) plays a crucial role in maintaining cellular protein homeostasis. The catalytic activity of proteasome in the UPS is regulated by β1 (PSMB6), β2 (PSMB7), and β5 (PSMB5) subunits. Interferon (IFN)-γ, tumor necrosis factor (TNF)-α, inflammation, and oxidative stress can induce the replacement of β1, β2, and β5 with their respective immuno-subunits β1i (PSMB9), β2i (PSMB10), and β5i (PSMB8), which can be assembled into the immunoproteasome. Compared with the standard proteasome, the immunoproteasome exerts enhanced regulatory effects on immune responses, such as processing and presenting MHC class Ⅰ antigens, production of pro-inflammatory cytokines, and T cell differentiation and proliferation. Abnormal aggregation of immunoproteasomes can cause neurodegenerative diseases like Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. To explore the function of PSMB9 after bacterial infection, we constructed a lentivirus plasmid overexpressing PSMB9-eGFP-His and transfected the plasmid into HEK293T cells for packaging by using a triple-plasmid system in this study. After screening with puromycin, we obtained a stable human leukemia monocytic THP-1 cell line expressing the fusion protein of PSMB9. Western blotting (WB) and fluorescence microscopy verified the expression of the fusion protein in the stable THP-1 cells. Quantitative PCR (qPCR) was employed to measure the copies of PSMB9-eGFP in THP-1 cells. Immunofluorescence results found that eGFP-His did not affect the subcellular localization of PSMB9. The purification with nickel affinity chromatography confirmed that the fusion protein could be assembled into the 20S immunoproteasome and exhibited cleaving activity for fluorescent peptide substrates. These results indicated that the PSMB9-eGFP fusion gene was integrated into the chromosome, and could be stably expressed in the constructed THP-1 cell line. This cell line can be utilized for the research on subcellular localization, dynamic expression, and activity of PSMB9 in live cells at different infection conditions and disease stages. It also provides a model for the stable cell lines construction of other immunoproteasome subunits PSMB8 and PSMB10.

Macropinocytosis Is the Principal Uptake Mechanism of Antigen-Presenting Cells for Allergen-Specific Virus-like Nanoparticles.

Virus-like nanoparticles (VNP) are regarded as efficient vaccination platforms and have proven to be useful for the non-anaphylactogenic delivery of allergen-specific immunotherapy in preclinical models previously. Herein, we sought to determine the mode of VNP uptake by antigen presenting cells (APC). Accordingly, we screened a collection of substances known to inhibit different uptake pathways by APC. The human leukemia monocytic cell line THP-1 and the murine dendritic cell line DC 2.4 were examined for the uptake of fluorescently labelled VNP in the presence or absence of inhibitors. The inhibitory effect of candidate substances that blocked VNP uptake in APC lines was subsequently evaluated in studies with primary APC present in splenocyte and lung cell homogenates in vitro and upon intratracheal application of VNP in vivo. The uptake of allergen-specific VNP in vitro and in vivo was mainly observed by macrophages and CD103+ dendritic cells and was sensitive to inhibitors that block macropinocytosis, such as hyperosmolarity induced by sucrose or the polyphenol compound Rottlerin at low micromolar concentrations but not by other inhibitors. Also, T-cell proliferation induced by allergen-specific VNP was significantly reduced by both substances. In contrast, substances that stimulate macropinocytosis, such as Heparin and phorbol myristate acetate (PMA), increased VNP-uptake and may, thus, help modulate allergen-specific T-cell responses. We have identified macropinocytosis as the principal uptake mechanism of APC for allergen-specific VNP in vitro and in vivo, paving the way for further improvement of VNP-based therapies, especially those that can be used for tolerance induction in allergy, in the future.

The dual role of FSP1 in programmed cell death: resisting ferroptosis in the cell membrane and promoting necroptosis in the nucleus of THP-1 cells

BackgroundAcute monocytic leukemia-M5 (AML-M5) remains a challenging disease due to its high morbidity and poor prognosis. In addition to the evidence mentioned earlier, several studies have shown that programmed cell death (PCD) serves a critical function in treatment of AML-M5. However, the role and relationship between ferroptosis and necroptosis in AML-M5 remains unclear.MethodsTHP-1 cells were mainly treated with Erastin and IMP-366. The changes of ferroptosis and necroptosis levels were detected by CCK-8, western blot, quantitative real-time PCR, and electron microscopy. Flow cytometry was applied to detect the ROS and lipid ROS levels. MDA, 4-HNE, GSH and GSSG were assessed by ELISA kits. Intracellular distribution of FSP1 was studied by immunofluorescent staining and western blot.ResultsThe addition of the myristoylation inhibitor IMP-366 to erastin-treated acute monocytic leukemia cell line THP-1 cell not only resulted in greater susceptibility to ferroptosis characterized by lipid peroxidation, glutathione (GSH) depletion and mitochondrial shrinkage, as the FSP1 position on membrane was inhibited, but also increased p-RIPK1 and p-MLKL protein expression, as well as a decrease in caspase-8 expression, and triggered the characteristic necroptosis phenomena, including cytoplasmic translucency, mitochondrial swelling, membranous fractures by FSP1 migration into the nucleus via binding importin α2. It is interesting to note that ferroptosis inhibitor fer-1 reversed necroptosis.ConclusionWe demonstrated that inhibition of myristoylation by IMP-366 is capable of switching ferroptosis and ferroptosis-dependent necroptosis in THP-1 cells. In these findings, FSP1-mediated ferroptosis and necroptosis are described as alternative mechanisms of PCD of THP-1 cells, providing potential therapeutic strategies and targets for AML-M5.

1,25-dihydroxyvitamin D3 augments low-dose PMA-based monocyte-to-macrophage differentiation in THP-1 cells

The human monocytic THP-1 cell line is the most routinely employed in vitro model for studying monocyte-to-macrophage differentiation. Despite the wide use of this model, differentiation protocols using phorbol 12-myristate-13-acetate (PMA) or 1,25-dihydroxyvitamin D3 (1,25D3) vary drastically between studies. Given that differences in differentiation protocols have the potential to impact the characteristics of the macrophages produced, we aimed to assess the efficacy of three different THP-1 differentiation protocols by assessing changes in morphology and gene- and cell surface macrophage marker expression. THP-1 cells were differentiated with either 5 nM PMA, 10 nM 1,25D3, or a combination thereof, followed by a rest period. The results indicated that all three protocols significantly increased the expression of the macrophage markers, CD11b (p < 0.001) and CD14 (p < 0.010). Despite this, THP-1 cells exposed to 1,25D3 alone did not adopt the morphological and expression characteristics associated with macrophages. PMA was required to produce these characteristics, which were found to be more pronounced in the presence of 1,25D3. Both PMA- and PMA with 1,25D3−differentiated THP-1 cells were capable of M1 and M2 macrophage polarization, though the gene expression of polarization-associated markers was most pronounced in PMA with 1,25D3−differentiated THP-1 cells. Moreover, the combination of PMA with 1,25D3 appeared to support the process of commitment to a particular polarization state.

Molecular and epigenetic ex vivo profiling of testis cancer-associated fibroblasts and their interaction with germ cell tumor cells and macrophages

Germ cell tumors (GCT) are the most common solid tumors in young men of age 15 - 40. In previous studies, we profiled the interaction of GCT cells with cells of the tumor microenvironment (TM), which showed that especially the 3D interaction of fibroblasts (FB) or macrophages with GCT cells influenced the growth behavior and cisplatin response as well as the transcriptome and secretome of the tumor cells, suggesting that the crosstalk of these cells with GCT cells is crucial for tumor progression and therapy outcome.In this study, we shed light on the mechanisms of activation of cancer-associated fibroblasts (CAF) in the GCT setting and their effects on GCT cells lines and the monocyte cell line THP-1. Ex vivo cultures of GCT-derived CAF were established and characterized molecularly and epigenetically by performing DNA methylation arrays, RNA sequencing, and mass spectrometry-based secretome analysis.We demonstrated that the activation state of CAF is influenced by their former prevailing tumor environment in which they have resided. Hereby, we postulate that seminoma (SE) and embryonal carcinoma (EC) activate CAF, while teratoma (TER) play only a minor role in CAF formation. In turn, CAF influence proliferation and the expression of cisplatin sensitivity-related factors in GCT cells lines as well as polarization of in vitro-induced macrophages by the identified effector molecules IGFBP1, LGALS3BP, LYVE1, and PTX3.Our data suggests that the vital interaction of CAF with GCT cells and with macrophages has a huge influence on shaping the extracellular matrix as well as on recruitment of immune cells to the TM. In conclusion, therapeutically interfering with CAF and / or macrophages in addition to the standard therapy might slow-down progression of GCT and re-shaping of the TM to a tumor-promoting environment.Significance: The interaction of CAF with GCT and macrophages considerably influences the microenvironment. Thus, therapeutically interfering with CAF might slow-down progression of GCT and re-shaping of the microenvironment to a tumor-promoting environment.

Interleukin-1–mediated hyperinflammation in XIAP deficiency is associated with defective autophagy

AbstractDeficiency of X-linked inhibitor of apoptosis protein (XIAP) is a rare genetic condition that can present with recurrent episodes of hemophagocytic lymphohistiocytosis (HLH), though the exact mechanisms leading to this hyperinflammatory disorder are unclear. Understanding its biology is critical to developing targeted therapies for this potentially fatal disease. Here, we report on a novel multiexonic intragenic duplication leading to XIAP deficiency with recurrent HLH that demonstrated complete response to interleukin (IL)-1β blockade. We further demonstrate using both primary patient cells and genetically modified THP-1 monocyte cell lines that, contrary to what has previously been shown in mouse cells, XIAP-deficient human macrophages do not produce excess IL-1β when stimulated under standard conditions. Instead, nucleotide-binding oligomerization domain–like receptor family pyrin domain containing 3 (NLRP3) inflammasome–mediated hyperproduction of IL-1β is observed only when the XIAP-deficient cells are stimulated under autophagy-promoting conditions and this correlates with defective autophagic flux as measured by decreased accumulation of the early autophagy marker LC3-II. This work, therefore, highlights IL-1β blockade as a therapeutic option for patients with XIAP deficiency experiencing recurrent HLH and identifies a critical role for XIAP in promoting autophagy as a means of limiting IL-1β–mediated hyperinflammation during periods of cellular stress.

Non-invasive Physical Plasma Modulates Macrophage Polarization: A Potential Strategy for Tumor Microenvironment Remodeling.

Non-invasive physical plasma (NIPP) has shown promise in the treatment of cancer. However, conflicting results have been reported regarding the effect of NIPP on macrophage polarization. As tumor-associated macrophages (TAMs) are essential in the regulation of cancer development, this study aimed to determine the role of NIPP treatment in macrophage polarization and tumor-microenvironment (TME) remodeling. A portable NIPP device, Plasma Care (Terraplasma Medical, Garching, Germany), was employed as the source of NIPP. The human monocytic cell line THP-1 was adopted as the cell model for macrophage differentiation and polarization. The effects of NIPP treatment on temperature, pH value, and oxidative stress induction of the culture medium were examined to validate the feasibility of applying the NIPP device in subsequent cell treatment. The changes in morphology, viability, and proliferation of THP-1 cells after NIPP treatment were determined. The expression of M1/M2 macrophage markers was examined by real-time quantitative polymerase chain reaction. No significant changes were observed in temperature and pH value after NIPP treatment, while the formation of hydrogen peroxide was promoted in a time-dependent manner. Cell morphology, viability, and proliferation were not affected by up to 6 minutes of NIPP treatment. In monocytes, 6 minutes of NIPP treatment significantly increased the expression of M1 markers (TNF-α and IL-6) and suppressed the M2 marker (CD206), findings which were consistent in the monocyte-derived macrophages. Furthermore, NIPP treatment also significantly promoted M1 polarization in the monocyte-derived macrophages induced by phorbol 12-myristate 13-acetate. NIPP is a safe and robust oxidative stress inducer and showed potential in TAM regulation by promoting M1 macrophage polarization.