Macrophage-like THP-1 Cells Derived from High-Density Cell Culture Are Resistant to TRAIL-Induced Cell Death via Down-Regulation of Death-Receptors DR4 and DR5

Pro-Inflammatory Activation Suppresses TRAIL-induced Apoptosis of Acute Myeloid Leukemia Cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) is a promising agent for treatment of AML due to its specific apoptosis-inducing effect on tumor cells but not normal cells. However, emergence of resistance to TRAIL in the AML cells limits its potential as an antileukemic agent. Previously, we revealed increase in the resistance of the human AML THP-1 cells to the TRAIL-induced death during their LPS-dependent proinflammatory activation and in the in vitro model of LPS-independent proinflammatory activation - in a long-term high-density cell culture. In this study, we investigated mechanisms of this phenomenon using Western blot analysis, caspase 3 enzymatic activity analysis, quantitative reverse transcription-PCR, and flow cytometry. The results showed that the increased resistance to the TRAIL-induced cell death of AML THP-1 cells during their pro-inflammatory activation is associated with the decrease in the surface expression of the proapoptotic receptors TRAIL-R1/DR4 and TRAIL-R2/DR5, as well as with the increased content of members of the IAPs family - Livin and cIAP2. The results of this article open up new insights into the role of inflammation in formation of the resistance of AML cells to the action of mediators of antitumor immunity, in particular TRAIL.

Low-Temperature Calcium Phosphate Ceramics Can Modulate Monocytes and Macrophages Inflammatory Response In Vitro

Creating bioactive materials for bone tissue regeneration and augmentation remains a pertinent challenge. One of the most promising and rapidly advancing approaches involves the use of low-temperature ceramics that closely mimic the natural composition of the extracellular matrix of native bone tissue, such as Hydroxyapatite (HAp) and its phase precursors (Dicalcium Phosphate Dihydrate-DCPD, Octacalcium Phosphate-OCP, etc.). However, despite significant scientific interest, the current knowledge and understanding remain limited regarding the impact of these ceramics not only on reparative histogenesis processes but also on the immunostimulation and initiation of local aseptic inflammation leading to material rejection. Using the stable cell models of monocyte-like (THP-1ATRA) and macrophage-like (THP-1PMA) cells under the conditions of LPS-induced model inflammation in vitro, the influence of DCPD, OCP, and HAp on cell viability, ROS and intracellular NO production, phagocytosis, and the secretion of pro-inflammatory cytokines was assessed. The results demonstrate that all investigated ceramic particles exhibit biological activity toward human macrophage and monocyte cells in vitro, potentially providing conditions necessary for bone tissue restoration/regeneration in the peri-implant environment in vivo. Among the studied ceramics, DCPD appears to be the most preferable for implantation in patients with latent inflammation or unpredictable immune status, as this ceramic had the most favorable overall impact on the investigated cellular models.

Studying Signaling Pathway Activation in TRAIL-Resistant Macrophage-Like Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a malignant neoplasm characterized by extremely low curability and survival. The inflammatory microenvironment and maturation (differentiation) of AML cells induced by it contribute to the evasion of these cells from effectors of antitumor immunity. One of the key molecular effectors of immune surveillance, the cytokine TRAIL, is considered a promising platform for developing selective anticancer drugs. Previously, under in vitro conditions of the inflammatory microenvironment (a three-dimensional high-density culture of THP-1 AML cells), we demonstrated the emergence of differentiated macrophage-like THP-1ad clones resistant to TRAIL-induced death. In the present study, constitutive activation of proinflammatory signaling pathways, associated transcription factors, and increased expression of the anti-apoptotic BIRC3 gene were observed in TRAIL-resistant macrophage-like THP-1ad AML cells. For the first time, a bioinformatic analysis of the transcriptome revealed the main regulator, the IL1B gene, which triggers proinflammatory activation and induces resistance to TRAIL in THP-1ad macrophage-like cells.

Influence of Microbiota-Related Metabolites Associated with Inflammation and Sepsis on the Peroxidase Activity of Cyclooxygenase in Healthy Human Monocytes and Acute Monocytic Leukemia Cells

The human microbiota produces metabolites that can enter the bloodstream and exert systemic effects on various functions in both healthy and pathological states. We have studied the participation of microbiota-related metabolites in bacterial infection by examining their influence on the activity of cyclooxygenase (COX) as a key enzyme of inflammation. The influence of aromatic microbial metabolites, derivatives of phenylalanine (phenylpropionic acid, PPA), tyrosine (4-hydroxyphenyllactic acid, HPLA), and tryptophan (indolacetic acids, IAA), the concentrations of which in the blood change notably during sepsis, was evaluated. Also, the effect of itaconic acid (ITA) was studied, which is formed in macrophages under the action of bacterial lipopolysaccharides (LPS) and appears in the blood in the early stages of infection. Metabiotic acetyl phosphate (AcP) as a strong acetylating agent was also tested. The activity of COX was measured via the TMPD oxidation colorimetric assay using the commercial pure enzyme, cultured healthy monocytes, and the human acute monocytic leukemia cell line THP-1. All metabolites in the concentration range of 100-500 μM lowered the activity of COX. The most pronounced inhibition was observed on the commercial pure enzyme, reaching up to 40% in the presence of AcP and 20-30% in the presence of the other metabolites. On cell lysates, the effect of metabolites was preserved, although it significantly decreased, probably due to their interaction with other targets subject to redox-dependent and acetylation processes. The possible contribution of the redox-dependent action of microbial metabolites was confirmed by assessing the activity of the enzyme in the presence of thiol reagents and in model conditions, when the COX-formed peroxy intermediate was replaced with tert-butyl hydroperoxide (TBH). The data show the involvement of the microbial metabolites in the regulation of COX activity, probably due to their influence on the peroxidase activity of the enzyme.

Improving the Stability and Effectiveness of Immunotropic Squalene Nanoemulsion by Adding Turpentine Oil

Turpentine oil, owing to the presence of 7-50 terpenes, has analgesic, anti-inflammatory, immunomodulatory, antibacterial, anticoagulant, antioxidant, and antitumor properties, which are important for medical emulsion preparation. The addition of turpentine oil to squalene emulsions can increase their effectiveness, thereby reducing the concentration of expensive and possibly deficient squalene, and increasing its stability and shelf life. In this study, squalene emulsions were obtained by adding various concentrations of turpentine oil via high-pressure homogenization, and the safety and effectiveness of the obtained emulsions were studied in vitro and in vivo. All emulsions showed high safety profiles, regardless of the concentration of turpentine oil used. However, these emulsions exhibited dose-dependent effects in terms of both efficiency and storage stability, and the squalene emulsion with 1.0% turpentine oil had the most pronounced adjuvant and cytokine-stimulating activity as well as the most pronounced stability indicators when stored at room temperature. Thus, it can be concluded that the squalene emulsion with 1% turpentine oil is a stable, monomodal, and reliably safe ultradispersed emulsion and may have pleiotropic effects with pronounced immunopotentiating properties.

Pterostilbene-isothiocyanate impedes RANK/TRAF6 interaction to inhibit osteoclastogenesis, promoting osteogenesis in vitro and alleviating glucocorticoid induced osteoporosis in rats

Prolonged glucocorticoid treatment often leads to glucocorticoid-induced osteoporosis (GIOP), a common iatrogenic complication. This study has explored the anti-osteoporotic potential of semi-synthetic compound, pterostilbene isothiocyanate (PTER-ITC) in GIOP rat model and bone formation potential in vitro. Dysregulated bone-remodelling leads to osteoporosis. PTER-ITC has shown anti-osteoclastogenic activity in vitro. However, its molecular target remains unidentified, which has been explored in this study through in silico and experimental approaches. Alizarin Red S and von-Kossa staining, and alkaline phosphatase (ALP) activity showed the osteogenic differentiation potential of PTER-ITC in pre-osteoblastic mouse MC3T3-E1 and human hFOB 1.19 cells, further, confirmed through the expressions of osteogenic markers at transcriptional (RT-qPCR) and translational (immunoblotting) levels. The anti-osteoclastogenic property of PTER-ITC was confirmed through inhibition of actin ring formation in mouse RAW 264.7 and human THP-1 macrophagic cells. Molecular docking and molecular dynamic simulation showed that PTER-ITC inhibited the crucial osteoclastogenic RANK/TRAF6 interaction, which was further confirmed biochemically through co-immunoprecipitation assay. Osteoporotic bone architecture [validated through scanning electron microscopy (SEM), X-ray radiography, and micro-computed tomography (µ-CT)], physiology (confirmed through compression testing, Young's modulus and stress versus strain output) and histology (verified through hematoxylin-eosin, Alizarin Red S, von-Kossa and Masson-trichrome staining) of PTER-ITC-treated GIOP female Wistar rats were assuaged. Osteoporotic amelioration through PTER-ITC treatment was further substantiated through serum biomarkers, like, parathyroid hormone (PTH), ALP, calcium (Ca²⁺), Procollagen type I N-terminal propeptide (P1NP), and 25-hydroxy vitamin D. In conclusion, this study identifies the molecular target of PTER-ITC in impeding osteoclastogenesis and facilitating osteogenesis to ameliorate osteoporosis.

Targeted Diagnosis, Therapeutic Monitoring, and Assessment of Atherosclerosis Based on Mesoporous Silica Nanoparticles Coated with cRGD-Platelets

Objective

The off-target effects and severe side effects of PPARα and LXRα agonists greatly limit their application in atherosclerosis (AS). Therefore, this study intended to use mesoporous silica nanoparticles as carriers to generate MnO nanoparticles in situ with T1WI-MRI in mesoporous pores and simultaneously load PPARα and LXRα agonists. Afterward, cRGD-chelated platelet membranes can be used for coating to construct a new nanotheranostic agent.

Methods

cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles were synthesized by a chemical method. Dynamic light scattering (DLS) was utilized to detect the size distribution and polydispersity index (PDI) of the nanoparticles. The safety of the nanoparticles was detected by CCK8 in vitro and HE staining and kidney function in vivo. Cell apoptosis was detected by flow cytometry detection and TUNEL staining. Oxidative stress responses (ROS, SOD, MDA, and NOX levels) were tested via a DCFH-DA assay and commercial kits. Immunofluorescence and phagocytosis experiments were used to detect the targeting of nanoparticles. Magnetic resonance imaging (MRI) was used to detect the imaging performance of cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles. Using western blotting, the expression changes in LXRα and ABCA1 were identified.

Results

cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles were successfully established, with a particle size of approximately 150 nm and PDI less than 0.3, and showed high safety both in vitro and in vivo. cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles showed good targeting properties and better MRI imaging performance in AS. cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles showed better antioxidative capacities, MRI imaging performance, and diagnostic and therapeutic effects on AS by regulating the expression of LXRα and ABCA1.

Conclusion

In the present study, cRGD-platelet@MnO/MSN@PPARα/LXRα nanoparticles with high safety and the capacity to target vulnerable plaques of AS were successfully established. They showed better performance on MRI images and treatment effects on AS by promoting cholesterol efflux through the regulation of ABCA1. These findings might address the problems of off-target effects and side effects of nanoparticle-mediated drug delivery, which will enhance the efficiency of AS treatment and provide new ideas for the clinical treatment of AS.

The Increase in the Drug Resistance of Acute Myeloid Leukemia THP-1 Cells in High-Density Cell Culture Is Associated with Inflammatory-like Activation and Anti-Apoptotic Bcl-2 Proteins

It is known that cell culture density can modulate the drug resistance of acute myeloid leukemia (AML) cells. In this work, we studied the drug sensitivity of AML cells in high-density cell cultures (cell lines THP-1, HL-60, MV4-11, and U937). It was shown that the AML cells in high-density cell cultures in vitro were significantly more resistant to DNA-damaging drugs and recombinant ligand izTRAIL than those in low-density cell cultures. To elucidate the mechanism of the increased drug resistance of AML cells in high-density cell cultures, we studied the activation of Bcl-2, Hif-1alpha, and NF-kB proteins, as well as cytokine secretion, the inflammatory immunophenotype, and the transcriptome for THP-1 cells in the low-density and high-density cultures. The results indicated that the increase in the drug resistance of proliferating THP-1 cells in high-density cell cultures was associated with the accumulation of inflammatory cytokines in extracellular medium, and the formation of NF-kB-dependent inflammatory-like cell activation with the anti-apoptotic proteins Bcl-2 and Bcl-xl. The increased drug resistance of THP-1 cells in high-density cultures can be reduced by ABT-737, an inhibitor of Bcl-2 family proteins, and by inhibitors of NF-kB. The results suggest a mechanism for increasing the drug resistance of AML cells in the bone marrow and are of interest for developing a strategy to suppress this resistance.