Human Monocytic Leukemia THP-1 Cells Research Articles

The pro-differentiating capability of a flavonoid-rich extract of Citrus bergamia juice prompts autophagic death in THP-1 cells

Acute myeloid leukemia (AML) is a hematologic neoplasm, characterized by a blockage of differentiation and an unconstrained proliferation of immature myeloid cells. Recently, the survival of leukemia patients has increased thanks to the use of differentiating agents, though these may cause serious side effects. Hence, the search for safer differentiating compounds is necessary. Our aim was to assess the pro-differentiating effects of a flavonoid-rich extract of bergamot juice (BJe) in human monocytic leukemia THP-1 cells, an in vitro AML model. For the first time, we showed that treatment with BJe induced differentiation of THP-1 cells, changes in cell morphology and increased expression of differentiation-associated surface antigens CD68, CD11b and CD14. Moreover, BJe enhanced protein levels of autophagy-associated markers, such as Beclin-1 and LC3, as well as induced the phosphorylation of the MAPKs JNK, ERK and p38, hence suggesting a potential mechanism underlying its antiproliferative effects. Indeed, parallel experiments highlighted that BJe was able to hamper THP-1 cell growth. In conclusion, our study suggests that BJe induces the differentiation of THP-1 cells and reduces their proliferation, highlighting its potential in differentiation therapy of AML.

Ethnobotanical survey and biological activities of plants used for cancer treatment in traditional Senegalese medicine

Female breast cancer is known to be one of the leading causes of death in Senegal. In Senegal, the absence of a national cancer control program, the lack of specialized infrastructure and qualified human resources and the exorbitant cost of care have contributed to the extensive use of traditional medecine, particularly in rural areas. This study aims to inventory the medicinal plants used by these healers and to assess the cytotoxic and antioxidant activities of the most widely used one. Data on healers and their use practices and information on plants were collected through the administration of a structured questionnaire. Based on their citation frequencies during the survey, Antiaris Africana Engler, Hymenocardia Acida Tul. and Halouf Halal (local name) were selected for chemical and biological studies. Their hydroalcoholic extracts were analyzed in terms of antioxidant capacity and cytotoxic effects, again, in the human cancer cell line. The study revealed a total of 65 medicinal plants belonging to 35 different families. The plant parts used by traditional healers are leaves (63.89%), roots (11.11%), bark (15.28%), fruits (2.78%), and others (6.94%). Generally, herbal medicine is prepared as a powder and mixed with water by maceration (55.38%) and administered orally. A. Africana ranked first with a citation frequency of 5.7% and its hydroalcoholic extract had the highest antioxidant activity in TEAC (6533.64±7 μmol ET/g dry plant) and in ORAC (3745.17±4.8 μmol ET/g dry plant) followed by H. Acida in TEAC (3115.6±145 μmol ET/g dry plant) and in ORAC (4105.29±872 μmol ET/g dry plant). The hydroalcoholic extract of A. Africana exhibited the highest cytotoxic activity in MCF-7 (Human mammary) and THP-1 (Human acute monocytic leukemia cell line) but had low activity against HTC-116 (Human carcinoma colorectal) and A-375 (Human skin malignant melanoma). The percentages of proapoptotic cells were, respectively, 68.85±6.22, 58.1±1.90 and 48.58±1.4%. These results provide scientific support for the traditional use of medicinal plants in cancer treatment and constitute a database for biological screening to isolate cytotoxic plant-based molecules.

Design, Synthesis, and Evaluation of a New Series of 2-Pyrazolines as Potential Antileukemic Agents.

In an attempt to identify small molecules for the treatment of leukemia, 12 new pyrazolines (2a-l) were synthesized efficiently. WST-1 assay was performed to examine their cytotoxic features on HL-60 human acute promyelocytic leukemia (APL), K562 human chronic myeloid leukemia (CML), and THP-1 human acute monocytic leukemia cells. Four compounds (2e, 2f, 2g, and 2h) were determined as promising antileukemic agents on HL-60 and K562 cells. IC50 values of compounds 2f, 2h, 2e, 2g, and bortezomib for the HL-60 cell line were found as 33.52, 42.89, 48.02, 62.34, and 31.75 μM, while IC50 values of compounds 2h, 2g, 2f, 2e, and bortezomib for K562 cells were determined as 33.61, 50.23, 57.28, 76.90, and 42.69 μM, respectively. Further studies were carried out to shed light on the mechanism of antileukemic action. According to the data obtained by in vitro experiments, 1-(4-fluorophenyl)-3-(thiophen-3-yl)-5-(4-(4-methylpiperazin-1-yl)phenyl)-2-pyrazoline (2f) and 1-(3-bromophenyl)-3-(thiophen-3-yl)-5-(4-(4-methylpiperazin-1-yl)phenyl)-2-pyrazoline (2h) have proved to be potential antileukemic agents with remarkable cytotoxicity against HL-60 and K562 cells by activation of caspase 3, thereby inducing apoptosis.

Anti-inflammatory effects of cold atmospheric plasma irradiation on the THP-1 human acute monocytic leukemia cell line.

Cold atmospheric plasma (CAP) has been studied and clinically applied to treat chronic wounds, cancer, periodontitis, and other diseases. CAP exerts cytotoxic, bactericidal, cell-proliferative, and anti-inflammatory effects on living tissues by generating reactive species. Therefore, CAP holds promise as a treatment for diseases involving chronic inflammation and bacterial infections. However, the cellular mechanisms underlying these anti-inflammatory effects of CAP are still unclear. Thus, this study aimed to elucidate the anti-inflammatory mechanisms of CAP in vitro. The human acute monocytic leukemia cell line, THP-1, was stimulated with lipopolysaccharide and irradiated with CAP, and the cytotoxic effects of CAP were evaluated. Time-course differentiation of gene expression was analyzed, and key transcription factors were identified via transcriptome analysis. Additionally, the nuclear localization of the CAP-induced transcription factor was examined using western blotting. The results indicated that CAP showed no cytotoxic effects after less than 70 s of irradiation and significantly inhibited interleukin 6 (IL6) expression after more than 40 s of irradiation. Transcriptome analysis revealed many differentially expressed genes (DEGs) following CAP irradiation at all time points. Cluster analysis classified the DEGs into four distinct groups, each with time-dependent characteristics. Gene ontology and gene set enrichment analyses revealed CAP-induced suppression of IL6 production, other inflammatory responses, and the expression of genes related to major histocompatibility complex (MHC) class II. Transcription factor analysis suggested that nuclear factor erythroid 2-related factor 2 (NRF2), which suppresses intracellular oxidative stress, is the most activated transcription factor. Contrarily, regulatory factor X5, which regulates MHC class II expression, is the most suppressed transcription factor. Western blotting revealed the nuclear localization of NRF2 following CAP irradiation. These data suggest that CAP suppresses the inflammatory response, possibly by promoting NRF2 nuclear translocation.

Serum amyloid A1 recruits neutrophils to the invasive front of T1 colorectal cancers.

The tumor microenvironment plays an essential role in the development and progression of colorectal cancer (CRC). We recently reported that crosstalk between CRC cells and tumor-associated macrophages (TAMs) via serum amyloid A1 (SAA1) promotes invasion by T1 CRCs. In the present study, we aimed to clarify the role of neutrophils in early CRCs. Immunohistochemical analysis of CD66b, chemokine CXC motif ligand 8 (CXCL8 or interleukin-8, IL-8) and matrix metalloproteinase-9 (MMP-9) was performed using primary T1 CRCs (n=49). The HL-60 human promyelocytic leukemia cell line and THP-1 human monocytic leukemia cell line were used to obtain neutrophil-like and macrophage-like cells, respectively. Boyden chamber assays were used to analyze cell migration and invasion, and quantitative RT-PCR was used to analyze gene expression. Immunohistochemical analysis revealed accumulation of neutrophils at the SAA1-positive invasive front of T1 CRCs. Experiments using HL-60 cells suggested that treatment with SAA1 induced neutrophil migration and expression of CXCL8 and MMP-9 in neutrophils and that neutrophils promote CRC cell migration and invasion. Immunohistochemistry confirmed accumulation of CXCL8- or MMP-9-positive neutrophils at the SAA1-positive invasive front of T1 CRCs. Moreover, co-culture experiments using CRC, THP-1 and HL-60 cells suggested that CRC cells activated by macrophages upregulate CXCL8 and MMP-9 in neutrophils. Our results suggest that interplay between macrophages and CRC cells leads to recruitment of neutrophils to the invasive front of T1 CRCs and that SAA1 secreted by CRC cells activate neutrophils to promote invasion.

Whey protein hydrolysate mitigates both inflammation and endotoxin tolerance in THP-1 human monocytic leukemia cells.

It is important to control both inflammation and immunosuppression after severe insults, such as sepsis, trauma, and surgery. Endotoxin tolerance is one of the immunosuppressive conditions and it has been known that endotoxin tolerance relates to poorer clinical outcomes in patients with severe insults. This study investigated whether whey protein hydrolysate (WPH) mitigates inflammation and endotoxin tolerance in THP-1 human monocytic leukemia cells. Endotoxin tolerance can be experimentally reproduced by two consecutive stimulations with lipopolysaccharide (LPS). THP-1 cells were incubated with LPS and WPH (first stimulation). After collecting the culture supernatant to evaluate the effect on inflammation, the cells were washed and restimulated by 100 ng/ml LPS (second stimulation). The culture supernatant was again collected to evaluate the effect on endotoxin tolerance. Concentrations of LPS and WPH in the first stimulation were adjusted to evaluate their dose dependency. Cytokine levels in the supernatant were determined by enzyme-linked immunosorbent assay. Statistical analysis was performed using the student's t-test or Dunnett's test. Five mg/ml WPH significantly decreased interleukin (IL)-6 (p = .006) and IL-10 (p < .001) levels after the first LPS stimulation (1000 ng/ml). WPH significantly increased tumor necrosis factor-alpha (p < .001) and IL-10 (p = .014) levels after the second LPS stimulation. The suppressive effect of WPH on inflammation and endotoxin tolerance was dependent on the concentrations of LPS and WPH. The effective dose of WPH for endotoxin tolerance was lower than its effective dose for inflammation. WPH mitigated both inflammation and endotoxin tolerance. Therefore, WPH might be a candidate for valuable food ingredients to control both inflammation and immunosuppression after severe insults.

Diclofenac-Induced Cytotoxicity in Direct and Indirect Co-Culture of HepG2 Cells with Differentiated THP-1 Cells.

Non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (DIC) frequently induce drug-induced liver injury (DILI). It is unclear whether macrophages such as M1 and M2 participate in NSAID-associated DILI; elucidating this relationship could lead to a better understanding of the detailed mechanism of DILI. We co-cultured human hepatoma HepG2 cells with M1 or M2 derived from human monocytic leukemia THP-1 cells to examine the roles of M1 and M2 in DIC-induced cytotoxicity. DIC was added to the direct or indirect co-cultures of HepG2 cells with M1 or M2 (HepG2/M1 or HepG2/M2, respectively) at cell ratios of (1:0, 1:0.1, 1:0.4, and 1:1). In both direct and indirect HepG2/M2 co-cultures (1:0.4), there was lower lactate dehydrogenase release compared with HepG2/M1 co-cultures. Other NSAIDs as well as DIC showed similar protective effects of DIC-induced cytotoxicity. There were only slight differences in mRNA levels of apoptosis- and endoplasmic reticulum stress-associated factors between M1 and M2 after DIC treatment, suggesting that other factors determined the protective effects of M2 on DIC-induced cytotoxicity. Levels of high mobility group box 1 (HMGB1) in the medium and the mRNA expression levels of HMGB1 receptors were different between M1 and M2 after DIC treatment. Increased HMGB1 concentrations and expression of toll-like receptor 2 mRNA in M1 were observed compared with M2 after DIC treatment. In conclusion, these results suggested that the HMGB1/TLR2 signaling axis can be suppressed in M2 but not M1, leading to the different roles of M1 and M2 in NSAID-induced cytotoxicity.

Ergosta-7,9(11),22-trien-3β-ol Attenuates Inflammatory Responses via Inhibiting MAPK/AP-1 Induced IL-6/JAK/STAT Pathways and Activating Nrf2/HO-1 Signaling in LPS-Stimulated Macrophage-like Cells.

Chronic inflammation induces autoimmune disorders and chronic diseases. Several natural products activate nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, attenuating inflammatory responses. Ergosta-7,9(11),22-trien-3β-ol (EK100) isolated from Cordyceps militaris showed anti-inflammatory and antioxidative activity, but those mechanisms are still unclear. This study is the first to investigate EK100 on antioxidant Nrf2 relative genes expression in LPS-stimulated macrophage-like cell lines. The results showed that EK100 reduced IL-6 (interleukin-6) and tumor necrosis factor-α production. EK100 also attenuated a mitogen-activated protein kinase/activator protein-1 (MAPK/AP-1) pathway and interleukin-6/Janus kinase/signal transducer and activator of transcription (IL-6/JAK/STAT) pathway in LPS-stimulated cells. Toll-like receptor 4 (TLR4) inhibitor CLI-095 and MAPK inhibitors can synergize the anti-inflammatory response of EK100 in LPS-stimulated cells. Moreover, EK100 activated Nrf2/HO-1 (heme oxygenase-1) signaling in LPS-stimulated murine macrophage-like RAW 264.7 cells, murine microglial BV2 cells, and human monocytic leukemia THP-1 cells. However, Nrf2 small interfering RNA (Nrf2 siRNA) reversed EK100-induced antioxidative proteins expressions. In conclusion, EK100 showed anti-inflammatory responses via activating the antioxidative Nrf2/HO-1 signaling and inhibiting TLR4 related MAPK/AP-1 induced IL-6/JAK/STAT pathways in the LPS-stimulated cells in vitro. The results suggest EK100 acts as a novel antioxidant with multiple therapeutic targets that can potentially be developed to treat chronic inflammation-related diseases.

Synthesis of new thiazole derivatives and evaluation of their antimicrobial and cytotoxic activities

Novel 2-heteroaryl-N-[4-(substituted aryl)thiazol-2-yl]propanamide derivatives (7a–7o) were synthesized and investigated for their antimicrobial activity. Among the tested compounds, 2-[(1H-Benzimidazol-2-yl)thio]-N-[4-(naphthalen-2-yl)thiazol-2-yl]propanamide (7e) and N-[4-(4-Chlorophenyl)thiazol-2-yl]-2-[(1-methyl-1H-tetrazol-5-yl)thio]propanamide (7f) showed the highest antibacterial activity, whereas 2-[Benzothiazol-2-ylthio]-N-[4-(4-chlorophenyl)thiazol-2-yl]propanamide (7i) and 2-[(1H-Benzimidazol-2-yl)thio]-N-[4-(4-chlorophenyl)thiazol-2-yl]propanamide (7j) displayed anticandidal effect against C. parapsilosis and C. glabrata. The cytotoxic activity of the compounds (7a–7o) was also tested against HL-60 human leukemia cells, THP-1 human monocytic leukemia cells, and NIH/3T3 mouse embryonic fibroblast cells. Compound N-[4-(4-Chlorophenyl)thiazol-2-yl]-2-[(1-methyl-1H-imidazol-2-yl)thio]propanamide (7 g) and compound 7j exhibited high cytotoxicity against HL-60; and compounds 2-[(1-Methyl-1H-imidazol-2-yl)thio]-N-[4-(naphthalen-2-yl)thiazol-2-yl]propanamide (7b), 7 g and N-[4-(4-Methoxyphenyl)thiazol-2-yl]-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]propanamide (7 m) also had cytotoxic activity against THP-1 compared with standard drug with selective profile. Additionally, in silico physicochemical properties of the compounds were described.

The effect of Kagocel® on gene expression of Toll-like receptors of innate immunity in THP-1 human monocytes with different levels of differentiation

Kagocel® is used in Russia for the treatment of viral infections. In terms of its chemical structure, Kagocel® active ingredient is a copolymer of gossypol polyphenol and carboxymethylcellulose. The study investigated antiviral and cytokine-inducing activity of Kagocel®, as well as its toxic effects. The aim of the study was to investigate the effect of Kagocel® active ingredient on the induction of expression of the innate immune system receptor genes (Toll-like receptors, TLR) in the THP-1 human acute monocytic leukemia cell line with different levels of differentiation. Materials and methods: the effect of Kagocel active ingredient was investigated at the concentrations of 0.2 and 2 mg/mL in the THP-1 human acute monocytic leukemia cell line with different levels of differentiation: non-differentiated monocytes, and monocytes differentiated into macrophage-like cells. Comparative analysis of the activity of TLR 2, 3, 4, 7, 8, 9 genes was carried out by quantitative RT-PCR. The study determined standard deviations of the levels of gene expression in the experimental cells (2deltaCq ± SD) relative to the expression in the control cells. Results: Kagocel active ingredient at the concentration of 0.2 mg/mL induced activation of TLR2 expression in THP-1 monocytes by 3.5 times, TLR3 by 2 times, TLR4 by 1.6 times, and at the concentration of 2 mg/mL also induced activation of TLR7 and TLR8 by 1.4 times, and TLR9 by 2 times. The levels of TLR2, TLR3, TLR9 induction were significantly higher in THP-1 monocytes partially differentiated into macrophage-like cells, and the highest stimulation level was observed for TLR2 (8 times). Conclusions: the results obtained characterise Kagocel® as a stimulator of TLR genes in the THP-1 cell line. The number of TLR genes induced in THP-1 monocytes was shown to increase with the increase in the product concentration. THP-1 monocyte differentiation into macrophage-like cells enhances susceptibility to Kagocel®. The positive regulation of TLR genes activity may account for antiviral and interferon-inducing properties of Kagocel®, and also suggests the possibility of expanding the use of the product for various immune-associated diseases.

Insight into antimicrobial activity of substituted phenylcarbamoyloxypiperazinylpropanols

3-[4-(Substituted)phenyl-/4-(diphenylmethyl)phenylpiperazin-1-yl]-2-hydroxypropyl-1-[(substituted)phenyl]carbamates and their salts with hydrochloric acid were synthesized, characterized, and tested in vitro against Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 as reference and quality control strains, against three methicillin-resistant isolates of S. aureus, and three isolates of vancomycin-resistant E. faecalis. All the compounds were evaluated against Mycobacterium tuberculosis H37Ra/ATCC 25177, M. kansasii DSM 44162, and M. smegmatis ATCC 700084. All of the tested compounds demonstrated very good activity against all the tested strains/isolates comparable with or better than that of clinically used drugs (ampicillin, ciprofloxacin, vancomycin, isoniazid). 1-[{(3-Trifluoromethyl)phenyl}carbamoyloxy-2-hydroxypropyl]-4-(3,4-dichlorophenyl)piperazin-1-ium chloride demonstrated the highest potency against all the tested strains/isolates (MICs ranged from 3.78 to 30.2 µM), and 1-[{(3-trifluoromethyl)phenyl}carbamoyloxy-2-hydroxypropyl]-4-(diphenylmethyl)piperazin-1-ium chloride was the most effective against all the screened mycobacterial strains (MICs ranged from 3.64 to 14.5 µM). All the investigated derivatives had strong antibiofilm activity against S. aureus ATCC 29123 and a synergistic or additive effect with gentamicin against isolates of E. faecalis with both intrinsic and acquired resistance to gentamicin. The screening of the cytotoxicity of the compounds was performed using human monocytic leukemia THP-1 cells. The IC50 values of the most effective compounds ranged from ca. 2.8 to 7.3 µM; thus, it can be stated that the antimicrobial effect is closely connected with their cytotoxicity. These observations disqualify these compounds from further development as antimicrobial agents, but they can be considered potential multi-target drugs with a preferred anticancer effect with good water solubility and additional anti-infectious activity.

CD47 decline in pancreatic islet cells promotes macrophage-mediated phagocytosis in type I diabetes.

BACKGROUNDType I diabetes (T1D) is characterized by insulin loss caused by inflammatory cells that excessively infiltrate and destroy the pancreas, resulting in dysregulation of tissue homeostasis, mechanobiological properties, and the immune response. The streptozotocin (STZ)-induced mouse model exhibits multiple features of human T1D and enables mechanistic analysis of disease progression. However, the relationship between the mechanochemical signaling regulation of STZ-induced T1D and macrophage migration and phagocytosis is unclear.AIMTo study the mechanochemical regulation of STZ-induced macrophage response on pancreatic beta islet cells to gain a clearer understanding of T1D.METHODSWe performed experiments using different methods. We stimulated isolated pancreatic beta islet cells with STZ and then tested the macrophage migration and phagocytosis.RESULTSIn this study, we discovered that the integrin-associated surface factor CD47 played a critical role in immune defense in the STZ-induced T1D model by preventing pancreatic beta islet inflammation. In comparison with healthy mice, STZ-treated mice showed decreased levels of CD47 on islet cells and reduced interaction of CD47 with signal regulatory protein α (SIRPα), which negatively regulates macrophage-mediated phagocytosis. This resulted in weakened islet cell immune defense and promoted macrophage migration and phagocytosis of target inflammatory cells. Moreover, lipopolysaccharide-activated human acute monocytic leukemia THP-1 cells also exhibited enhanced phagocytosis in the STZ-treated islets, and the aggressive attack of the inflammatory islets correlated with impaired CD47-SIRPα interactions. In addition, CD47 overexpression rescued the pre-labeled targeted cells.CONCLUSIONThis study indicates that CD47 deficiency promotes the migration and phagocytosis of macrophages and provides mechanistic insights into T1D by associating the interactions between membrane structures and inflammatory disease progression.

Distinct anti-proliferative effects of herbal melanin on human acute monocytic leukemia THP-1 cells and embryonic kidney HEK293 cells

BackgroundHerbal melanin (HM) is a dark pigment extracted from the seed coat of Nigella sativa L. and known to exert biological effects via toll-like receptor 4 (TLR4). Recently, TLR4 was described as involved in natural programmed cell death (apoptosis). Tumor and embryonic cells are used as in vitro cellular models for drug and anti-cancer agent screening. To date, no cytotoxic studies have been reported of HM in TLR4-positive acute monocytic leukemia THP-1 cells compared to TLR4-negative human embryonic kidney HEK293 cells.MethodsWe studied the anti-proliferative effects of several HM concentrations on THP-1 and HEK293 cells by evaluating cell viability using the CellTiter-Glo® luminescent assay, assessing the TLR4 expression level, determining the apoptotic status, and analyzing the cell cycle distribution using flow cytometry. Apoptotic pathways were investigated using mitochondrial transition pore opening, caspase activity assays and immunoblot technology.ResultsLow HM concentrations did not affect THP-1 cell viability, but high HM concentrations (62.5–500 μg/mL) did decrease THP-1 cell viability and induced G0/G1 phase cell cycle arrest. Only at the highest concentration (500 μg/mL), HM slightly increased the TLR4 expression on the THP-1 cell surface, concomitantly upregulated TLR4 whole protein and gene expression, and induced apoptosis in THP-1 cells via activation of the extrinsic and intrinsic pathways. No change of apoptotic status was noticed in TLR4-negative HEK293 cells, although HM decreased HEK293 cell viability and induced cell growth arrest in the G2 phase.ConclusionHM exerts distinct anti-proliferative effects on human acute monocytic leukemia and embryonic kidney cells mainly through cell cycle interference in a TLR4-independent manner and through apoptosis induction in a TLR4-dependent manner, as observed in only the THP-1 cells.

RETRACTED: Levetiracetam inhibits THP-1 monocyte chemotaxis and adhesion via the synaptic vesicle 2A

Long-term therapy with older antiepileptic drugs (AEDs), but not levetiracetam (LEV), may increase the risk of atherosclerosis (AS), suggesting that LEV may have a potential anti-AS effect. The synaptic vesicle 2A (SV2A) is known to the specific binding site of LEV. Numerous studies have documented that SV2A is a membrane protein specifically expressed in nervous system. Interestingly, our previous research showed that SV2A also existed in human CD8+ T lymphocytes. Therefore, we hypothesized that LEV was associated with decreased risk of AS by regulating monocytes chemotaxis and adhesion. We showed that SV2A protein were detected in THP-1 human monocytic leukemia cells. LEV (300μM) inhibited the chemotaxis and adhesion of THP-1cells after transfection with plasmids expressing SV2AWT, but not SV2AR383Q which was a known functional mutation site of human SV2A. Furthermore, RT-PCR and western blot analysis demonstrated that LEV (300μM) decreased the expression level of chemokine-related receptors (CX3CL1, CCR1, CCR2, and CCR5),and reduced levels of phosphorylated AKT (p-AKT) in THP-1cells with SV2AWT expressing plasmids. Taken together, these findings indicated that LEV has an inhibitory effect on THP-1 monocyte adhesion and chemotaxis, suggesting that SV2A may serve as a novel therapeutic target to prevent AS.

M2-like polarization of THP-1 monocyte-derived macrophages under chronic iron overload.

Macrophages are characterized by phenotypical and functional heterogeneity. In different microenvironments, macrophages can polarize into two types: classically activated macrophages (M1) or alternatively activated macrophages (M2). M1 macrophages are a well-known bacteriostatic macrophage, and conversely, M2 macrophages may play an important role in tumor growth and tissue remodeling. M1 macrophages have been reported to have high intracellular iron stores, while M2 macrophages contain lower intracellular iron. It has been well-described that disturbances of iron homeostasis are associated with altered immune function. Thus, it is important to investigate if chronic iron overload is capable of polarizing macrophages. Human monocytic leukemia THP-1 cells were maintained in culture medium that contained 100μM ferrous sulfate heptahydrate (FeSO4) (I-THP-1) and differentiated into THP-1-derived macrophages (I-TDMs) by induction with phorbol 12-myristate 13-acetate (PMA). We characterized that I-TDMs not only enhanced the surface expression of CD163 and CD206 but also increased arginase and decreased iNOS protein expression. I-TDMs enhanced pSTAT6 expression and decreased pSTAT1 and NF-κB expressions. Furthermore, the gene expression profile of I-TDMs was comparable with M2 macrophages by performing human oligonucleotide DNA microarray analysis. Finally, functional assays demonstrated I-TDMs secreted higher levels of IL-10 but not M1 cytokines. Additionally, the conditional medium of I-TDMs had enhanced migration and increased invasion of A375 melanoma cells which was similar to the characteristics of tumor-associated macrophages. Taken together, we demonstrated that THP-1-derived macrophages polarized to a phenotype of M2-like characteristics when subjected to chronic iron overload.

Preparation of Fluorescent Recombinant Shiga Toxin B Subunit and Its Application to Flow Cytometry.

Shiga toxin (Stx) is a major virulence factor of enterohemorrhagic Escherichia coli (E. coli). Stx consists of one enzymatic A subunit and five B subunits (StxB) that are involved in binding. The StxB pentamer specifically recognizes a glycosphingolipid, globotriaosylceramide (Gb3), as a receptor; therefore, it can be used as a probe to detect Gb3. This chapter describes the preparation of recombinant Stx1B proteins using E. coli, their conjugation with fluorescent dyes, and their application for flow cytometry. The prepared fluorescent StxB proteins bound to cells of several lines, including the HeLa human cervix adenocarcinoma cell line and the THP-1 human monocytic leukemia cell line. Furthermore, the probe was useful for confirmation of several sphingolipid-deficient HeLa cell lines that were constructed using genome editing.

Abstract 2354: Targeted IRAK-M degradation as a novel and efficacious cancer-immunotherapy overcoming innate-driven immunosuppression

Abstract IRAK-M has an important role in tightly controlling innate immune responsiveness to preserve homeostasis, mediating immune tolerance, and acts as a negative feedback regulator of TLR/IL-1R signaling pathway. Targeting IRAK-M, which expression is restricted to myeloid cells, would be potentially limiting adverse events against non-target tissues. From supporting evidence for the role of IRAK-M in innate immunosuppressive capacity of tumor-associated macrophages (TAMs) or dendritic cells (DCs), we have developed compounds targeting IRAK-M as an effective cancer-immunotherapy strategy. Since IRAK-M is a pseudokinase which is characterized by the lack of conserved motifs involved in catalytic kinase activity, drug design for inhibition of IRAK-M has been challenging because the conventional small molecule could not modulate its function in cells. Therefore, we conceived and optimized heterobifunctional for degradation comprising IRAK-M-binding moiety linked to the our proprietary XIAP binders to eliminate the IRAK-M protein via ubiquitin-proteasome system. We demonstrated a concentration-dependent degradation of IRAK-M protein in THP1 human monocytic leukemia cells with degraders, and this degradation activity was confirmed to be proteasome-dependent by rescue of depletion following pre-incubation with the proteasome inhibitor epoxomicin. In addition, to estimate the cellular degradation selectivity of our degrader to IRAK-M in an unbiased manner, we carried out whole proteome mass spectrometry in THP1 cells and exhibited good selectivity against identified quantifiable proteins including IRAK-4. As functional studies, we performed MDSC suppression assays in a co-culture model with T cells and found IRAK-M degrader could release the suppressive function of MDSC. Lead optimization steps for IRAK-M degraders have conducted by applying RaPPIDSTM which is a proprietary divergent degrader synthetic platform and already identified multiple drug candidates within a year. Finally, in LLC Lewis lung carcinoma syngeneic model, treatment with candidate resulted in significant tumor growth inhibition. Pre-clinical toxicological studies have been entered and backup compounds are also in development. Taken together, these results highlight the promise of combined IRAK-M silent binder and targeted protein degradation technology as a novel therapeutic strategy for the cancer-immunotherapy that shifts the balance between tolerance and immunity by releasing immunosuppressive activity and in turn by unleashing tumor-specific T-lymphocytes. Citation Format: Kanae Gamo, Naomi Kitamoto, Yoshihide Tomata, Yusuke Tominari. Targeted IRAK-M degradation as a novel and efficacious cancer-immunotherapy overcoming innate-driven immunosuppression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2354.

Alternative skin sensitization prediction and risk assessment using proinflammatory biomarkers, interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS)

ABSTRACTAs an alternative to animal tests for skin sensitization potency and risk assessment, cell viability and biomarkers related to skin sensitization were analyzed in THP-1 human monocytic leukemia cells. Cell viabilities of 90% (CV90) and 75% (CV75) were determined for 24 selected test chemicals. Further biomarkers related to skin sensitization were also determined under equivalent comparative conditions. In cell viability analyses, potent skin sensitizers exhibited high cytotoxicity, but non-sensitizers did not display this tendency. In biomarker analyses, interleukin-I beta (IL-1β), inducible nitric oxide synthase (iNOS), IL-1β+iNOS, and THP-1 IL-1β+Raw 264.7 IL-1β were found to be suitable for prediction of skin sensitization potency following classification as either skin sensitizers or non-sensitizers (accuracies of 91.7%, 87.5%, 83.3%, and 82.6%, respectively). A significant positive correlation was found between biomarkers and skin sensitization potency, with a correlation coefficient (R) of 0.7 or more (correlation coefficients of 0.77, 0.72, 0.7, and 0.84, respectively). Finally, the skin sensitization potency effective threefold concentration (EC) 3% was predicted using a biomarker equation, with resulting prediction rates (match rate with actual data) of 58.3%, 54.2%, 62.5%, and 60.9%, respectively. The prediction accuracy for the EC3 value obtained from animal data was calculated as 83.3%, 79.2%, 79.2%, and 73.9%, respectively. Thus, these biomarkers, IL-1β and iNOS, may be alternatively used to predict skin sensitization potency and risk assessment.

Parallel in vitro and in silico investigations into anti-inflammatory effects of non-prenylated stilbenoids

Stilbenoids represent a large group of bioactive compounds, which occur in food and medicinal plants.Twenty-five stilbenoids were screened in vitro for their ability to inhibit COX-1, COX-2 and 5-LOX. Piceatannol and pinostilbene showed activity comparable to the zileuton and ibuprofen, respectively.The anti-inflammatory potential of stilbenoids was further evaluated using THP-1 human monocytic leukemia cell line. Tests of the cytotoxicity on the THP-1 and HCT116 cell lines showed very low toxic effects. The tested stilbenoids were evaluated for their ability to attenuate the LPS-stimulated activation of NF-κB/AP-1. Most of the tested substances reduced the activity of NF-κB/AP-1 and later attenuated the expression of TNF-α.The effects of selected stilbenoids were further investigated on inflammatory signaling pathways. Non-prenylated stilbenoids regulated attenuation of NF-ĸB/AP-1 activity upstream by inhibiting the phosphorylation of MAPKs.A docking study used to in silico analyze the tested compounds confirmed their interaction with NF-ĸB, COX-2 and 5-LOX.

PARP-1 (Poly[ADP-Ribose] Polymerase 1) Inhibition Protects From Ang II (Angiotensin II)-Induced Abdominal Aortic Aneurysm in Mice.

Abdominal aortic aneurysm (AAA) is a common vascular degenerative disease. PARP-1 (poly[ADP-ribose] polymerase 1) is a nuclear enzyme, which plays a critical role in vascular diseases. We hypothesized that PARP-1 inhibition might have protective effects on AAA. In vivo, Ang II (angiotensin II) was continuously infused by a micropump for 28 days to induce AAA in mice. In vitro, aortic endothelial cells and smooth muscle cells were stimulated by Ang II for 24 hours. Ang II infusion increased PARP-1 expression and activity and successfully induced AAA formation partly with a hemorrhage in ApoE-/- mice. Genetic deletion of PARP-1 markedly reduced the AAA incidence, abdominal aortic diameter, macrophage infiltration, ICAM-1 (intercellular adhesion molecule 1) and VCAM-1 (vascular adhesion molecule 1) expression, and MMP (matrix metalloproteinase) expression, as well as MMP activity; but increased smooth muscle cells content and collagens expression in AAA. PARP-1 inhibition by PJ-34 also exerted a protective effect on AAA in mice. In aortic endothelial cells, Ang II-induced oxidative stress and DNA damage, resulting in increased PARP-1 expression and activity. Compared with the control, Ang II increased TNF-α (tumor necrosis factor α) and IL-6 (interleukin-6) secretions, ICAM-1 expression and THP-1 (human acute monocytic leukemia cell line) cells adhesion, while PARP-1 inhibition by siRNA reduced the inflammatory response probably through inhibition of the phosphorylation of ERK (extracellular signal-regulated kinase), NF-κB (nuclear factor-κB), and Akt signaling pathways. In smooth muscle cells, Ang II promoted cell migration, proliferation, and apoptosis, reduced collagens expression, but increased MMPs expression, while PARP-1 deletion alleviated these effects partly by reducing NF-κB-targeted MMP-9 expression. PARP-1 inhibition might be a feasible strategy for the treatment of AAA.