Organomegalies as a predictive indicator of leukemia cutis in patients with acute myeloid leukemia

BACKGROUND

Leukemia cutis (LC) is an extramedullary acute myeloid leukemia (AML) infiltrate. No previous study has described the clinical characteristics and outcomes of Thai patients diagnosed with AML with LC.

MATERIALS AND METHODS

We conducted a 7-year retrospective case-control study on Thai AML patients at Siriraj Hospital from November 2013 to July 2020. Patients were divided into LC and non-LC groups. Initial clinical presentations and laboratory findings were examined to identify LC-associated factors. Overall survival (OS) and relapse-free survival (RFS) were assessed. Pathological tissues underwent re-evaluation to validate the LC diagnoses.

RESULTS

The study included 159 patients in a 2:1 ratio (106 non-LC and 53 LC). The LC group had a mean ± SD age of 54.3 ± 15.5 years; females were predominant. Three-fifths of the LC patients had intermediate-risk cytogenetics; 20.4% had an adverse risk, and 10.2% had a favorable risk. Most were classified as AML-M4 and AML-M5. Leukemic nodules were the primary finding in 58.5% of the cases, mainly on the legs. In the multivariate analysis of predictive factors associated with LC, organomegalies, specifically hepatomegaly, and lymphadenopathy, remained significant factors associated with LC [OR 4.45 (95%CI 1.20, 16.50); p = 0.026 and OR 5.48 (95%CI 1.65, 18.20); p = 0.005], respectively. The LC group demonstrated a significantly reduced OS (log-rank test p = 0.002) (median OS of 8.6 months vs. 32.4 months). RFS was considerably lower in the LC group (log-rank test p = 0.001) (median duration of 10.3 months vs. 24.4 months in the non-LC).

CONCLUSIONS

AML patients who developed LC tended to experience notably poorer prognoses. Therefore, it is imperative to consider aggressive treatment options for such individuals. The presence of organomegalies in AML patients serves as a strong predictor of the possible occurrence of LC when accompanied by skin lesions.

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.

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.

The Potential Use of THP-1, a Monocytic Leukemia Cell Line, to Predict Immune-Suppressive Potency of Human Bone-Marrow Stromal Cells (BMSCs) In Vitro: A Pilot Study

Adoptive transfer of cultured BMSCs was shown to be immune-suppressive in various inflammatory settings. Many factors play a role in the process, but no master regulator of BMSC-driven immunomodulation was identified. Consequently, an assay that might predict BMSC product efficacy is still unavailable. Below, we show that BMSC donor variability can be monitored by IL-10 production of monocytes/macrophages using THP-1 cells (immortalized monocytic leukemia cells) co-cultured with BMSCs. Using a mixed lymphocyte reaction (MLR) assay, we also compared the ability of the different donor BMSCs to suppress T-cell proliferation, another measure of their immune-suppressive ability. We found that the BMSCs from a donor that induced the most IL-10 production were also the most efficient in suppressing T-cell proliferation. Transcriptome studies showed that the most potent BMSC batch also had higher expression of several known key immunomodulatory molecules such as hepatocyte growth factor (HGF), PDL1, and numerous members of the PGE2 pathway, including PTGS1 and TLR4. Multiplex ELISA experiments revealed higher expression of HGF and IL6 by the most potent BMSC donor. Based on these findings, we propose that THP-1 cells may be used to assess BMSC immunosuppressive activity as a product characterization assay.

Therapy-Related Acute Myeloid Leukemia Mimicking Lymphoma: a Diagnostic Dilemma

BACKGROUND

Based on the 2017 revision of the World Health Organization Classification, therapy-related myeloid neoplasms consist of therapy-related acute myeloid leukemia, therapy-related myelodysplastic syndromes, and therapy-related myelodysplastic/myeloproliferative neoplasms, which exist as a late-occurring complication of radiation and/or chemotherapy treatment due to previous application of iatrogenic mutagenic agents.

METHODS

Here we present the first described case of therapy-related acute monocytic leukemia mimicking lym-phoma after chemotherapy and radiotherapy for breast cancer.

RESULTS

Based on immunophenotypic analysis and biopsy of the BM, the patient was diagnosed with acute monocytic leukemia (AML FAB M5b) according to WHO classification. Due to short interval of development, a diagnosis of therapy-related acute monocytic leukemia was made.

CONCLUSIONS

The atypical morphology of the patient, a diagnostic mistake, resulted in an initial diagnosis of secondary lymphoma. Recognizing the atypical morphology is vital in distinguishing it from lymphoma, which is closely related to the treatment and prognosis of the patient.

Differential Immunomodulatory Effect of Graphene Oxide and Vanillin-Functionalized Graphene Oxide Nanoparticles in Human Acute Monocytic Leukemia Cell Line (THP-1)

Graphene and its derivatives are emerging as attractive materials for biomedical applications, including antibacterial, gene delivery, contrast imaging, and anticancer therapy applications. It is of fundamental importance to study the cytotoxicity and biocompatibility of these materials as well as how they interact with the immune system. The present study was conducted to assess the immunotoxicity of graphene oxide (GO) and vanillin-functionalized GO (V-rGO) on THP-1 cells, a human acute monocytic leukemia cell line. The synthesized GO and V-rGO were characterized by using various analytical techniques. Various concentrations of GO and V-rGO showed toxic effects on THP-1 cells such as the loss of cell viability and proliferation in a dose-dependent manner. Cytotoxicity was further demonstrated as an increased level of lactate dehydrogenase (LDH), loss of mitochondrial membrane potential (MMP), decreased level of ATP content, and cell death. Increased levels of reactive oxygen species (ROS) and lipid peroxidation caused redox imbalance in THP-1 cells, leading to increased levels of malondialdehyde (MDA) and decreased levels of anti-oxidants such as glutathione (GSH), glutathione peroxidase (GPX), super oxide dismutase (SOD), and catalase (CAT). Increased generation of ROS and reduced MMP with simultaneous increases in the expression of pro-apoptotic genes and downregulation of anti-apoptotic genes suggest that the mitochondria-mediated pathway is involved in GO and V-rGO-induced apoptosis. Apoptosis was induced consistently with the significant DNA damage caused by increased levels of 8-oxo-dG and upregulation of various key DNA-regulating genes in THP-1 cells, indicating that GO and V-rGO induce cell death through oxidative stress. As a result of these events, GO and V-rGO stimulated the secretion of various cytokines and chemokines, indicating that the graphene materials induced potent inflammatory responses to THP-1 cells. The harshness of V-rGO in all assays tested occurred because of better charge transfer, various carbon to oxygen ratios, and chemical compositions in the rGO. Overall, these findings suggest that it is essential to better understand the parameters governing GO and functionalized GO in immunotoxicity and inflammation. Rational design of safe GO-based formulations for various applications, including nanomedicine, may result in the development of risk management methods for people exposed to graphene and graphene family materials, as these nanoparticles can be used as delivery agents in various biomedical applications.

[EVI1 expression, clinical and cytogenetical characteristics in 447 patients with acute myeloid leukemia]

Objective: To investigate EVI1 expression and its associated clinical and cytogenetic characteristics in 447 acute myeloid leukemia (AML) patients. Methods: EVI1 expressions were measured in 447 AML cases from Jan. 2007 to Apr. 2015 to couple with clinical, cytogenetic and mutations' characteristics to summarize the features of AMLs with high EVI1 expression. Results: 17.9% of AML were high EVI1 expression (EVI1 +), and the remainder low EVI1 expression (EVI1-). No significant differences between the two groups in terms of age, sex, hemoglobin level, white blood cell count and platelet count were observed. More M0, M5 and M6 subtypes were observed in EVI1+ group (P= 0.027, 0.004 and 0.011, respectively). Cytogenetic abnormalities of 11q15, 11q23/MLL, 3q26, -7/7q- and t (9;11) were observed more frequently in EVI1 + group (P<0.001, <0.001, <0.001, <0.001, =0.014, respectively). Normal karyotype, inv (16), t (8;21) were observed more frequent in EVI1- group (P=0.001, 0.009, 0.002, respectively). EVI1 + was more observed in high risk cytogenetics. Mutation of NPM1 was more observed in EVI1- group (P <0.001). Remission rate in EVI1 + group was significantly lower than EVI1- group (P<0.001). Leukemia-free survival was improved in EVI1 + AML patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Conclusions: High EVI1 expression was more observed in FAB subgroup M5, harbored more cytogenetic abnormalities of 11p15, 11q23/MLL, 3q26 rearrangement, -7/7q- and t (9;11). Remission rate of high EVI1 expression AML was lower, which could be improved by allo-HSCT.

Changes of gene expression profiles in macrophages stimulated by angiotensin II — Angiotensin II induces MCP-2 through AT1-receptor

Introduction. Macrophages play critical roles in the development of atherosclerosis and diabetic nephropathy as well as many inflammatory diseases. Angiotensin II type 1 receptor antagonists (AIIA) are beneficial for the prevention of atherosclerosis and diabetic nephropathy suggesting that angiotensin II (Ang II) promotes the development of these diseases. It has recently been reported that Ang II exerts proinflammatory actions in vivo and in vitro. This study was aimed to clarify the direct effects of Ang II on monocytes/macrophages.

Materials and methods. PMA-treated THP-1 cells, a human monocytic leukaemia cell line, were treated with Ang II (10-6 mol/L) for 24 hours with or without AIIA (CV11974). We evaluated gene expression profiles of these cells using DNA microarray system and quantified them by real-time RT-PCR.

Results. DNA microarray revealed that in total 19 genes, including monocyte chemoattractant protein (MCP)-2, were up-regulated by Ang II and down-regulated by AIIA. Real-tim D e RT-PCR showed that up-regulation of MCP-2 with Ang II is blocked by the AIIA (CV11974) but not by an AT2-receptor antagonist.

Conclusions. These results suggest that Ang II directly stimulates MCP-2 expression through AT1-receptors in activated macrophages.Ang II may contribute to the persistence or amplification of microinflammation in vessel walls, heart and kidney.Vasculoprotective or renoprotective effects of AIIA might partly depend on direct antiinflammatory effects on macrophages.

[Comparison between two different dose of r-ATG combined with CsA for treating children with severe aplastic anemia]

This study was purposed to compare the efficacy and safety of two different doses of rabbit anti-thymocyte globulin (r-ATG) combined with cyclosporine (CsA) for treating children with severe aplastic anemia (SAA). From January 2005 to July 2010, a total of 95 children with SAA accepted intensive immunosuppressive therapy (IIST) in our department, out of them 55 cases were treated with r-ATG 2.5 mg/(kg·d) for 5 days in combination with CsA (group I) and other 40 cases were treated with r-ATG 3.5 mg/(kg·d) for 5 days in combination with CsA (group II). The responsive rate, adverse reactions, early mortality, relapse and clonal disease were analyzed retrospectively and results between the two groups were compared. Out of 95 patients 43 were boys and 52 were girls, their ages were from 1 to 16 years. The sex, age, severity and course of the disease were comparable between the two groups. The results showed that after treating for 3 and 6 months, the response of patients in group II was higher than that of patients in group I (50% vs 32.1%, P = 0.08 and 65% vs 45.3%, P = 0.059), at 9 and 12 months the response rate of patients in group II and group I did not show significant difference (70.0% vs 71.1%,P = 0.904 and 82.5% vs 80.8%,P = 0.832); at 12 months of treatment, the complete response rate of patients in group II was significantly higher than that of patients in group I (40.0% vs 23.1%,P = 0.08); at 3, 6, 9 months of treatment, the complete response rate of 2 groups showed no obvious difference. The incidence of serum disease, early infection and early mortality did not show statistical difference between two groups. There was no statistical difference in 2 year overall survival rate of two groups. In group I 39 patients were followed-up for more than 2 years, among them 3 patients relapsed, 1 patient died and 1 patient was diagnosed as acute monocytic leukemia (M5). In group II 15 patients were followed up for more than 2 years, there were no relapse, death and clonal disease. It is concluded that the r-ATG combined with CsA is an effective and safe therapeutic regimen for the SAA children. The effect of r-ATG 3.5 mg/(kg·d) is better than the 2.5 mg/(kg·d). The early safety is comparable between the two groups. However, the long-term effect, complications and survival rate need longer follow-up study to evaluate.

[Effect of TIMP-2, MT1-MMP and MMP-2 expression on the in vitro invasive capacity of acute monocytic leukemia SHI-1 cells]

OBJECTIVE

To study the effect of matrix metalloproteinase 2 (MMP-2), membrane type 1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase 2 (TIMP-2) expressions on the in vitro invasive capacity of acute monocytic leukemia SHI-1 cells.

METHODS

SHI-1, NB4, K562, M937 and THP-1 human leukemia cell lines were cultured in vitro. The mRNA and protein expressions of TIMP-2, MMP-2 and MT1-MMP in different cells were detected by quantitative RT-PCR and western blot. A retroviral vector carrying human TIMP-2 cDNA was constructed and transfected into SHI-1 cells. Three subclone cells (S1, S2 and S3) were screened by G418 and selected by limiting dilution. RNA interference (RNAi) was used to knock down the expression of MMP-2, MT1-MMP and TIMP-2. Cell invasion capacity was performed through a reconstituted human basement membrane assays. Zymography was used to analyze the expression of MMP-2 in the supernatant of co-culture.

RESULTS

The expressions of MMP-2, MT1-MMP and TIMP-2 in SHI-1 cells were higher than that in other leukemic cells at both mRNA and protein levels (P < 0.05). The amount of proMMP-2 and activated MMP-2 in the conditioned media from SHI-1 cells co-cultured with bone marrow stromal cells (BMSCs) was more than that from other cells (P < 0.05). The in vitro invasive capacity of SHI-1 cells were higher than that of other cells (P < 0.05). The mRNA levels of TIMP-2 were increased by about 3 fold, 2 fold and 1.5 fold in S1, S2 and S3 cells, respectively (P < 0.05), while the protein levels were by about 2.6 fold, 1.5 fold and 1.3 fold than that of SHI-1 cells, respectively (P < 0.01). The invasion rates of subclone cells demonstrated a 1.5 - 2.5 fold' elevation (P < 0.05) and activated MMP-2 from their supernatants increased by 1.5 - 2.0 fold (P < 0.01). The knock-down efficiency of siRNA was 85% to 98%. The down-regulation of TIMP-2, MMP-2 and MT1-MMP decreased the invasion rates of SHI-1 cells by 60% - 70%, 50% - 60% and 40% - 50%, respectively (P < 0.05). No activated MMP-2 in the supernatants from any knock-down cells could be found.

CONCLUSIONS

SHI-1 cells constitutively overexpress MMP-2, MT1-MMP and TIMP-2 at both mRNA and protein levels. After co-cultured with BMSCs the SHI-1 cells increased MMP-2 activation and cell invasion. An increase of TIMP-2 expression in SHI-1 cells reflects an activating effect on cells invasion and MMP-2 activation.

[Influences of Mycobacterium tuberculosis on the levels of human acute monocytic leukemia cell line THP-1 apoptosis and death]

OBJECTIVE

To explore the influences of Mycobacterium tuberculosis on the levels of human acute monocytic leukemia cell line THP-1 apoptosis and death.

METHODS

Human acute monocytic leukemia cell line THP-1 were infected with Mycobacterium tuberculosis strains H37Ra, H37Rv, or Beijing genotype (BJTB), respectively, to construct the infection models. Cell apoptosis was detected using flow cytometry. The distribution of the apoptotic proteins was detected using immunofluorescent staining assays. The cells late apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining assays. The change of cell death was determined by Tyrpan blue staining assays.

RESULTS

THP-1 apoptosis was induced by Mycobacterium tuberculosis strains H37Ra, H37Rv, and BJTB. H37Ra strongly induced THP-1 apoptosis, H37Rv weakly induced THP-1 apoptosis, and BJTB induced THP-1 apoptosis at the lowest level among these three Mycobacterium tuberculosis strains. On the contrary, BJTB strongly induced THP-1 death, H37Rv weakly induced THP-1 death, and H37Ra induced THP-1 death at the lowest level.

CONCLUSIONS

Mycobacterial strains with different virulence induce different levels of apoptosis and death of THP-1 cells. Compared with highly virulent strains, attenuated strains induce more apoptosis and less death.

HIV protease inhibitor lopinavir-induced TNF-alpha and IL-6 expression is coupled to the unfolded protein response and ERK signaling pathways in macrophages

HIV protease inhibitor (PI)-associated cardiovascular risk, especially atherosclerosis, has become a major concern in the clinic. Macrophages are key players in the inflammatory response and atherosclerosis formation. We have previously shown that HIV PIs induce endoplasmic reticulum (ER) stress, activate the unfolded protein response (UPR), and increase the synthesis of the inflammatory cytokines, TNF-alpha and IL-6, by regulating the intracellular translocation of RNA binding protein HuR in macrophages. However, the underlying signaling mechanisms remain unclear. We show here that the HIV PI lopinavir significantly activated the extracellular-signal regulated protein kinase (ERK), but not c-Jun N-terminal kinase (JNK) and p38 MAPK. Lopinavir-induced cytosolic translocation of HuR and TNF-alpha and IL-6 synthesis was attenuated by specific chemical inhibitor of MEK (PD98058) or over-expression of dominant negative mutant of MEK1. In addition, we demonstrated that lopinavir-induced ERK activation and TNF-alpha and IL-6 expression were completely inhibited in macrophages from CHOP null mice. Taken together, these results indicate activation of the UPR plays an essential role in HIV PI-induced inflammatory cytokine synthesis and release by activating ERK, which increases the cytosolic translocation of HuR and subsequent binding to the 3'UTR of TNF-alpha and IL-6 mRNAs in macrophages.

Synthesis and biological evaluation of novel C(6) modified baicalein derivatives as antioxidative agents

Baicalein, one of the major flavones, was found to be responsible for the antioxidative activity of the traditional Chinese medicinal herb Huang-Qin ( Scutellaria baicalensis Georgi), which is widely used as an antioxidative, anti-inflammatory, and antitumor agent. The hydroxyl group of the A ring of the baicalein was alkylated at position 6 with terpenoids such as prenyl, geranyl, and farnesyl groups, and their free radical scavenging activities and glutathione (GSH) depletion capacities were examined. Their free radical scavenging activity was measured according to the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(*+)) scavenging method. Baicalein and newly synthesized baicalein derivatives were found to be good free radical scavengers. Flow cytometrical method was employed to measure the intracellular antioxidative activity and GSH depletion capacity of these derivatives in human acute monocytic leukemia cell line (THP-1). It was also found that baicalein and its derivatives could decrease the levels of exogenous cumene hydroperoxide and H2O2 in THP-1 cells. These compounds also could significantly inhibit the intracellular GSH depletion induced by cumene hydroperoxide in THP-1 cells. The production of cumene hydroperoxide-induced Bax, a pro-apoptotic related protein, could also be inhibited by baicalein and its derivatives. These results suggested that baicalein and its derivatives could be beneficial to human health.

Human thioredoxin-1 ameliorates experimental murine colitis in association with suppressed macrophage inhibitory factor production

BACKGROUND & AIMS

Thioredoxin-1 (TRX) is a small multifunctional protein with antioxidative and redox-regulating functions. In this study, we investigated the significance of TRX in patients with inflammatory bowel disease (IBD) and the ability and mechanism to ameliorate experimental colitis.

METHODS

Serum TRX and macrophage migration inhibitory factor (MIF) levels were measured in patients with IBD. The effects of TRX were evaluated in a dextran sulfate sodium (DSS)-induced colitis model by comparing TRX-overexpressing transgenic (TRX-TG) and control mice. We further evaluated the effect of recombinant human TRX (rhTRX) administration on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (IL-10 KO) mice. Colonic inflammation was examined clinically and histologically. Proinflammatory cytokine levels were examined in colonic tissues, and MIF levels were measured in colonic tissues and sera in mice. The effect of TRX on MIF production was also analyzed in vitro.

RESULTS

Serum TRX and MIF levels were significantly higher in patients with IBD than normal controls, and TRX levels correlated with disease activity. TRX significantly ameliorated DSS-induced colitis and colonic inflammation of IL-10 KO mice. Increase of tumor necrosis factor-alpha and interferon-gamma in colonic tissues was significantly suppressed in TRX-TG mice compared with wild-type mice. MIF levels in colonic tissues and sera were significantly lower in TRX-TG mice than in wild-type mice, irrespective of DSS administration. Anti-TRX treatment exacerbated DSS-induced colitis. In vitro studies demonstrated that rhTRX suppressed MIF production in human monocyte cells.

CONCLUSIONS

TRX might have a potential as a novel therapeutic agent for the treatment of IBD.

Verotoxin-1 stimulation of macrophage-like THP-1 cells up-regulates tissue factor expression through activation of c-Yes tyrosine kinase: Possible signal transduction in tissue factor up-regulation

Verotoxin (VT)-producing Escherichia coli (E. coli) O157:H7 infections are frequently complicated by thrombotic angiopathy, hemolytic uremic syndrome (HUS) and neurological symptoms. The present data demonstrate that VT-1 (Shiga toxin) stimulation of macrophage-like THP-1 cells up-regulates the activity, antigen and mRNA levels of tissue factor (TF), a key cofactor of the coagulation-inflammation-thrombosis circuit. This up-regulation is accompanied by phosphorylation of phosphatidylinositol 3-kinase (PI3-kinase), IkappaB kinase beta (IKKbeta) and extracellular signal-regulated kinase 2 (ERK2). Changes in TF mRNA levels were in parallel with the activation of NF-kappaB/Rel and Egr-1 activation, but not with AP-1. Inhibition of PI3-kinase attenuated VT-1-induced phosphorylation of IKKbeta and ERK2, and the up-regulation of TF mRNA levels. VT-1 stimulation rapidly activated c-Yes tyrosine kinase, a member of the Src family. Treatment of the cells with c-Yes antisense oligos attenuated the VT-1-induced phosphorylation of PI3-kinase, IKKbeta and ERK2, activations of NF-kappaB/Rel and Egr-1, and up-regulation of TF mRNA levels. These results suggest that VT-1-induced macrophage stimulation activates c-Yes, which then up-regulates TF expression through activation of the IKKbeta/proteasome/NF-kappaB/Rel and MEK/ERK2/Egr-1 pathways via activation of PI3-kinase. Induction of macrophage TF expression by VT-1 may play an important role in the acceleration of the coagulation-inflammation-thrombosis circuit during infections by VT-producing E. coli.

Cigarette smoke induces proinflammatory cytokine release by activation of NF-κB and posttranslational modifications of histone deacetylase in macrophages

Cigarette smoke-mediated oxidative stress induces an inflammatory response in the lungs by stimulating the release of proinflammatory cytokines. Chromatin remodeling due to histone acetylation and deacetylation is known to play an important role in transcriptional regulation of proinflammatory genes. The aim of this study was to investigate the molecular mechanism(s) of inflammatory responses caused by cigarette smoke extract (CSE) in the human macrophage-like cell line MonoMac6 and whether the treatment of these cells with the antioxidant glutathione (GSH) monoethyl ester, or modulation of the thioredoxin redox system, can attenuate cigarette smoke-mediated IL-8 release. Exposure of MonoMac6 cells to CSE (1% and 2.5%) increased IL-8 and TNF-α production vs. control at 24 h and was associated with significant depletion of GSH levels associated with increased reactive oxygen species release in addition to activation of NF-κB. Inhibition of IKK ablated the CSE-mediated IL-8 release, suggesting that this process is dependent on the NF-κB pathway. CSE also reduced histone deacetylase (HDAC) activity and HDAC1, HDAC2, and HDAC3 protein levels. This was associated with posttranslational modification of HDAC1, HDAC2, and HDAC3 protein by nitrotyrosine and aldehyde-adduct formation. Pretreatment of cells with GSH monoethyl ester, but not thioredoxin/thioredoxin reductase, reversed cigarette smoke-induced reduction in HDAC levels and significantly inhibited IL-8 release. Thus cigarette smoke-induced release of IL-8 is associated with activation of NF-κB via IKK and reduction in HDAC levels/activity in macrophages. Moreover, cigarette smoke-mediated proinflammatory events are regulated by the redox status of the cells.

[Growth and infiltration of human monocytic leukemia cell in nude mice: a model for central nervous system leukemia]

OBJECTIVE

To establish a model of human monocytic leukemia with CNS infiltration in BALB/c nude mice.

METHODS

BALB/c nu/nu mice pre-treated by splenectomy, cytoxan intraperitoneal injection, and sublethal irradiation (SCI), were transplanted intravenously with 1 x 10(7) of human monocytic leukemic SHI-1 cells. The leukemic cells engrafted in the mice were detected by RT-PCR, histopathological examination, immunohistochemistry and FCM.

RESULTS

The survival time of SCI-nu/nu mice was 33-46 d. Paraplegia occurred in some of the mice. 5 weeks after transplantation, SHI-1 cells engrafted in SCI-nu/nu mice, multi-organs were involved and green solid neoplasms were formed in some organs. Histopathological examination found that SHI-1 cells infiltrated in liver, lung, kidney and testis of the mice and vertebral and skull bone marrow was replaced by leukemic cells. Leukemic cell penetrated through the surface of vertebrae, formed neoplasm, and entered the subdural space, but seldom involved the spinal parenchyma. In brain leukemia cells were filled in the subdural space and pia-arachnoid, covered the surface of cerebrum, cerebellum, spread along the virchow-robin space on the surface of pia mater, and eventually invaded the brain parenchyma.

CONCLUSION

SHI-1 cells could engrafted in the SCI-nu/nu mice, form an efficient and reproducible experimental model of CNSL and systematic leukemia. This model may be useful for studying the pathogenesis of CNSL.

Stereospecific and Redox-Sensitive Increase in Monocyte Adhesion to Endothelial Cells by Homocysteine

Objective— Previous studies have shown that elevated homocysteine (Hcy) levels promote the development of atherosclerotic lesions in atherosclerosis-prone animal models. There is evidence that oxidant stress contributes to Hcy’s deleterious effects on the vasculature. The accumulation and adhesion of monocytes to the vascular endothelium is a critical event in the development of atherosclerosis. We investigated the effects of Hcy on the interaction between human endothelial cells (EC) (EC line EA.hy 926 and primary human umbilical vein EC [HUVEC]) and the monocytic cell line THP-1, and the impact of vascular oxidant stress and redox-sensitive signaling pathways on these events.

Methods and Results— L-Hcy, but not D-Hcy, increases the production of reactive oxygen species inside EC, enhances nuclear factor(NF)-κB activation, and stimulates intercellular adhesion molecule-1 (ICAM-1) RNA transcription and cell surface expression. This leads to a time- and dose-dependent increase in monocyte adhesion to ECs. Pretreatment of ECs with superoxide scavengers (MnTBAP and Tiron) or with an inhibitor of NF-κB activation abolished Hcy-induced monocyte adhesion, ICAM-1 expression, and nuclear translocation of NF-κB.

Conclusions— These findings suggest that reactive oxygen species produced under hyperhomocysteinemic conditions may induce a proinflammatory situation in the vessel wall that initiates and promotes atherosclerotic lesion development.

ABCA1 and ABCG1 Synergize to Mediate Cholesterol Export to ApoA-I

OBJECTIVE

To study the acceptor specificity for human ABCG1 (hABCG1)-mediated cholesterol efflux.

METHODS AND RESULTS

Cells overexpressing hABCG1 were created in Chinese Hamster Ovary (CHO-K1) cells and characterized in terms of lipid composition. hABCG1 expressed in these cells formed homodimers and was mostly present intracellularly. Cholesterol efflux from hABCG1 cells to HDL2 and HDL3 was increased but not to lipid-free apolipoproteins. A range of phospholipid containing acceptors apart from high-density lipoprotein (HDL) subclasses were also efficient in mediating ABCG1-dependent export of cholesterol. Importantly, a buoyant phospholipid-containing fraction generated from incubation of lipid-free apoA-I with macrophages was nearly as efficient as HDL2. The capacity of acceptors to induce ABCG1-mediated efflux was strongly correlated with their total phospholipid content, suggesting that acceptor phospholipids drive ABCG1-mediated efflux. Most importantly, acceptors for ABCG1-mediated cholesterol export could be generated from incubation of cells with lipid-free apoA-I through the action of ABCA1 alone.

CONCLUSIONS

These results indicate a synergistic relationship between ABCA1 and ABCG1 in peripheral tissues, where ABCA1 lipidates any lipid-poor/free apoA-I to generate nascent or pre-beta-HDL. These particles in turn may serve as substrates for ABCG1-mediated cholesterol export.

Elevated concentrations of nonesterified fatty acids increase monocyte expression of CD11b and adhesion to endothelial cells

OBJECTIVE

Monocyte proinflammatory activity has been demonstrated in obesity, insulin resistance, and type 2 diabetes, metabolic conditions that are frequently associated with elevated levels of nonesterified fatty acids (NEFA). We therefore tested the hypothesis that NEFA may induce monocyte inflammation.

METHODS AND RESULTS

Monocytes exposed to NEFA for 2 days demonstrated a dose-related increase in intracellular reactive oxygen species (ROS) formation and adhesion to endothelial cells. All of these effects were inhibited by the coaddition of antioxidants such as glutathione or butylated hydroxytoluene, by inhibition of ROS generation by NADPH oxidase inhibitors, and by inhibition of protein kinase C, a recognized stimulator of NAPDH oxidase. Monocytes exposed to NEFA also demonstrated a significant increase in CD11b message expression. Stimulation of monocyte adhesion to endothelial cells by NEFA was inhibited by addition of neutralizing antibodies to either CD11b or CD18. Finally, surface expression of CD11b increased significantly on monocytes as measured by flow cytometry, after their incubation with NEFA.

CONCLUSIONS

These studies indicate that elevated concentrations of NEFA may enhance integrin facilitated monocyte adhesion to endothelial cells and these effects appear mediated, in part, through activation of NADPH oxidase and oxidative stress.

The Leukocyte Integrin Gene CD11d Is Repressed by Gut-enriched Kruppel-like Factor 4 in Myeloid Cells

The myeloid-specific leukocyte integrin CD11d encodes the alphaD subunit for the alphaDbeta2 receptor. A yeast one-hybrid screen showed that a longer isoform of gut-enriched Kruppel-like factor 4 (GKLF) we term GKLFa interacts with the CD11d promoter. Purified GST-GKLFa protein was shown to bind within the -61 to -44 region that overlaps a binding site for the CD11d transcriptional activators Sp1 and transforming growth factor beta-inducible early gene-1 (TIEG1). Transfection of GKLF/GKLFa in myeloid cells reduced CD11d promoter activity, whereas, down-regulation of GKLF/GKLFa with small interfering RNAs led to up-regulation of CD11d expression. Differentiation of myeloid cells with phorbol ester led to activation of the CD11d promoter and reduced occupancy of the promoter by GKLF/GKLFa but an increased occupancy by TIEG1 in vivo. Binding of GKLF/GKLFa, Sp1, and TIEG1 to the CD11d promoter in vivo is dependent on their zinc finger DNA binding domains. GKLFa physically associates with the histone deacetylases (HDAC) 1 and 2, and both HDACs are bound to the CD11d promoter in vivo but released after exposure of myeloid cells to phorbol ester suggesting that GKLF/GKLFa recruits HDACs to effect repression.

Amyloid Precursor Protein Mediates Proinflammatory Activation of Monocytic Lineage Cells

Alzheimer's disease is a progressive neurodegenerative disorder characterized by extracellular deposition of beta-amyloid (Abeta) peptide containing neuritic plaques. Abeta peptides are proteolytically derived from the membrane-bound amyloid precursor protein (APP). Although the function of APP is not entirely clear, previous studies demonstrate that neuronal APP colocalizes with beta(1) integrin receptors at sites of focal adhesion, suggesting that APP is involved in mediating neuronal process adhesion. Integrin-dependent adhesion is also a well-characterized component of immune cell proinflammatory activation. Using primary mouse microglia and the human monocytic cell line, THP-1, we have begun investigating the role of APP in integrin-dependent activation. Co-immunoprecipitation studies demonstrate that APP is recruited into a multi-receptor signaling complex during beta(1) integrin-mediated adhesion of monocytes. Stimulation induces a subsequent, specific recruitment of tyrosine phosphorylated proteins to APP, including Lyn and Syk. Antibody cross-linking of cell surface APP leads to a similar response characterized by activation and recruitment of tyrosine kinases to APP as well as subsequent activation of mitogen-activated protein kinases and increased proinflammatory protein levels. These data demonstrate that APP can act as a proinflammatory receptor in monocytic lineage cells and provide insight into the contribution of this protein to the inflammatory conditions described in Alzheimer's disease.

Large matrix proteoglycans, versican and perlecan, are expressed and secreted by human leukemic monocytes

THP-1 is a monocytic cell line originally derived from a patient with acute monocytic leukemia. Interactions of THP-1 cells with other cells and their microenvironment are largely determined by proteoglycans (PGs), the identity of which has not been determined. Previous studies on glycosaminoglycan expression by THP-1 cells and peripheral blood mononuclear cells from healthy individuals showed that both cell types secrete mainly chondroitin sulfate PGs to the culture medium, whereas heparan sulfate PGs are mainly retarded at the cell membrane. However, limited data on the type of PGs synthesized by THP-1 is available. In this study, the identification of PG types synthesised by THP-1 cells, which are not differentiated to macrophages, was examined. Analysis at the mRNA level by RT-PCR showed the expression of six cell membrane-associated PGs: syndecan-1, -2 and -4, glypican-1, thrombomodulin and CD44. Cell extraction, ion-exchange chromatography and dot blot analysis of the isolated PG populations with monoclonal antibodies showed the presence of syndecan-1 and thrombomodulin; the other two syndecans were not detected in any of the isolated populations. The synthesis of matrix PGs was also studied. THP-1 monocytes were positive for the mRNA encoding for versican and perlecan, but not for those encoding for decorin, biglycan, betaglycan and fibromodulin. The mRNA encoding for two versican splice variants V0 (351 bp) and V1 (386 bp), but not for V2, were identified. Biochemical analysis showed the presence of perlecan and of two populations of versican in culture medium with protein cores of average molecular sizes similar to those of V0 and V1. The production of these large matrix PGs by THP-1 monocytes is reported for the first time and may be of importance in monocyte malignant transformation and differentiation.

Comparative DNA microarray analysis of host cell transcriptional responses to infection by Coxiella burnetii or Chlamydia trachomatis

DNA microarray analysis was conducted to investigate the transcriptional responses of the human monocytic leukemia cell line THP-1 to infection by Chlamydia trachomatis or Coxiella burnetii. RNA was isolated from mock infected cells and cells infected for 36 hours using TRIzol reagent. Biotinylated probes synthesized from RNA samples were hybridized to an Affymetrix U133A human genome chip consisting of 18,462 human gene probe sets. A total of 335 and 548 THP-1 genes were up- or downregulated at least twofold in cells infected with C. burnetii or C. trachomatis, respectively, when compared to uninfected cells. There was a high degree of overlap in transcriptional responses to infection with shared responses observed for 39 downregulated and 189 upregulated genes. Numerous pathogen-specific transcriptional responses were also observed. Quantitative RT-PCR and immunoblotting confirmed up- or down-regulation of a subset of THP-1 genes in response to infection by C. burnetii. This study provides insight into the host transcriptional responses to infection by Chlamydia and Coxiella that may affect the infectious cycle of each organism.

Synergically increased expression of CD36, CLA-1 and CD68, but not of SR-A and LOX-1, with the progression to foam cells from macrophages

Several species of scavenger receptors have so far been identified. However, it remains unclear which receptors are more crucial for the foam cell formation and progression. In the present study, we compared five major scavenger receptors (SR-A, CD36, CLA-1, CD68, and LOX-1) in their levels of expression at the different stages of foam cells derived from THP-1 cells. The expression of all scavenger receptors examined was up-regulated by the stimulation with TPA for 48 hours, despite the expressions of SR-A, CD36 and LOX-1 being very low before the treatment with TPA. Four to 7 days after the removal of TPA, the levels of CD36, CLA-1 and CD68 were increased significantly. In contrast, the expression of SR-A was suppressed significantly, and no change was observed in that of LOX-1. Furthermore, when the transformed macrophages were incubated with oxidized LDL, in which the uptake of [3H] cholesteryl oleoyl ether-labeled OxLDL was linear up to 7 days after the addition of OxLDL, the expression of CD36, CLA-1 and CD68 were greatly enhanced. This enhancement was more prominent than that without oxidized LDL, and the enhancement was sustained throughout the experimental period. On the other hand, SR-A was not up-regulated, and LOX-1 was down-regulated. We thus propose that CD36, CLA-1 and CD68, but not SR-A and LOX-1, may play crucial roles in the progression of macrophages to foam cells, which is a key step for the initiation of atherosclerosis.

Phosphorylation of the cell cycle inhibitor p21Cip1/WAF1 by Pim-1 kinase

The serine/threonine kinase, Pim-1, appears to be involved in regulating proliferation, differentiation and cell survival of lymphoid and myeloid cells. In this study, we have found that amino acid residues 140-147 (RKRRQTSM) at the C-terminal end of p21(Cip1/WAF1), a cyclin-dependent kinase (CDK) inhibitor, constitute an ideal phosphorylation consensus sequence for Pim-1. We demonstrate that Pim-1 efficiently phosphorylates this peptide sequence as well as the p21 protein in vitro. We also demonstrate by pull-down assay and by immunoprecipitation that Pim-1 associates with p21. During phorbol ester-induced differentiation of U937 cells, both Pim-1 and p21 expression levels increase with Pim-1 levels increasing in both the nucleus and cytoplasm while p21 remains primarily cytoplasmic. Co-transfection of wild type p21 with wild type Pim-1 results in cytoplasmic localization of p21 while co-transfection of wild type p21 with kinase dead Pim-1 results in nuclear localization of p21. Consistent with the results from the phosphoamino acid assay, Pim-1 phosphorylates transfected p21 only on Thr(145) in p21-deficient human fibroblasts and this phosphorylation event results in the cytoplasmic localization of p21. These findings demonstrate that Pim-1 associates with and phosphorylates p21 in vivo, which influences the subcellular localization of p21.

The serine/threonine phosphatase, PP2A: endogenous regulator of inflammatory cell signaling

We have investigated the regulation of kinases and phosphatases in early gene activation in monocytes because these cells are implicated in the pathogenesis of acute inflammatory states, such as sepsis and acute lung injury. One early gene up-regulated by endotoxin is c-Jun, a member of the activating protein (AP) family. C-Jun is phosphorylated by c-Jun N-terminal kinase (JNK) and associates with c-Fos to form the AP-1 transcriptional activation complex that can drive cytokine expression. Inhibition of the serine/threonine phosphatase, PP2-A, with okadaic acid resulted in a significant increase in JNK activity. This finding was associated with increased phosphorylation of c-Jun, AP-1 transcriptional activity, and IL-1beta expression. Activation of PP2A inhibited JNK activity and JNK coprecipitated with the regulatory subunit, PP2A-Aalpha, supporting the conclusion that PP2A is a key regulator of JNK in the context of an inflammatory stimulus.

Modulation of the effects of osteoprotegerin (OPG) ligand in a human leukemic cell line by OPG and calcitonin

The discovery of osteoprotegerin (OPG), osteoprotegerin ligand (OPGL), and RANK has elucidated the mechanism by which osteoblasts and stromal cells regulate osteoclastic differentiation and function and mediate the effects exerted by other hormones and cytokines. We have investigated the effects of these novel cytokines on the preosteoclastic cell line FLG 29.1. We show that OPGL alone and in combination with macrophage colony-stimulating factor (CSF-1) dramatically reduced replication and increased tartrate-resistant acid phosphatase activity. However, although FLG29.1 cells appear to adhere to the bone surface, they are not able to form resorption lacunae. OPG and calcitonin completely abolished the differentiation induced by OPGL. RANK was detectable in FLG 29.1 and the number of positive cells was increased by OPGL/CSF-1 treatment while reduced by calcitonin. We propose that calcitonin could interact with the OPG/OPGL, and its effects on RANK may explain in part the action of this hormone in suppressing bone resorption.

Pharmacological characterisation of the P2Y11 receptor in stably transfected haematological cell lines

The recently cloned P2Y11 receptor is unique amongst P2Y receptors with its coupling to the adenylyl cyclase pathway. P2Y11 has previously been shown to be expressed in human acute promyelocytic leukemia (APL) HL-60 and NB4 cell lines, and both cell types elevate cyclic AMP (cAMP) levels upon stimulation with extracellular ATP. Acute erythroleukemic K562 cells and acute monocytic leukemia U937 cells did not elevate cAMP levels upon exposure to 1 mM extracellular ATP. However, K562 and U937 cells stably transfected with P2Y11 (K11 and U11 cells, respectively) were responsive to extracellular ATP, with an EC50 of 31 and 21 microM, respectively. The most potent agonists in both K11 and U11 cells were ATPgammaS (adenosine 5'-O-[3-thiotriphosphate]), ATPalphaS (adenosine 5'-O-[1-thiotriphosphate]), dATP and ADPbetaS (adenosine 5'-O-[2-thiobisphosphate]), which were of similar or greater potency compared to ATP itself. ADP and alpha,beta-methylene ATP were less potent compared to ATP. The order of potency for ATP breakdown products was ATP > ADP > AMP > or = Ado. UTP, a known activator of P2Y2 and P2Y4, was largely ineffective. In the transfected cells, ATP-induced cAMP elevation was inhibited by suramin (0.5 mM), but not XAC (20 microM) nor PPADS (100 microM). AMPS inhibited ATP-induced cAMP elevation in both K11 and U11 cells (EC50 approximately 3 mM) and may be a P2Y11-selective inhibitor. These results are similar to those observed for HL-60 cells and NB4 cells implicating P2Y11 as the receptor responsible for the ATP-induced cAMP elevations in these cells.

A simple semisolid subtraction method using carbodiimide-coated microplates

In this article, we develop a novel subtraction method using carbodiimide-bound microplates. This method utilizes the high affinity of carbodiimides for both single- and double-stranded nucleic acids. Carbodiimide-mediated end-attachment of driver RNA to microplates allows semisolid phase hybridization between driver RNA and target cDNA, and ensures easy removal of RNA/cDNA hybrids composed of the genes commonly expressed in driver and target. As a result, the target-specific genes are left unhybridized and enriched in the hybridization supernatant. We define the optimal conditions for the method as a target/driver RNA ratio of 1:10 and a period of hybridization of 24 h. There are at least three major advantages with the present method: (1) The entire procedure, which consists of two steps, is very simple; (2) hybridization efficiency can be monitored before further processing of the samples; and (3) rare transcripts can be effectively enriched. This method may be a powerful tool to isolate the genes specifically expressed in particular cell or tissue types, and is easily applicable to many studies in molecular biology and genetics. Isolation of polyploid megakaryocyte-specific genes is shown as an example.

Induction of IL-1 receptor antagonist by interferon beta: implication for the treatment of multiple sclerosis

IFNbeta has been the first drug approved for the treatment of multiple sclerosis patients, but we still lack a full understanding of the mechanisms underlying its clinical effects and the great variability of its therapeutic efficacy among different patients. Serum levels of the anti-inflammatory cytokine IL-1 receptor antagonist increase after IFNbeta administration in MS patients. We now report that IFNbeta induced IL-1ra mRNA and mature protein in three myelomonocytic cell lines. The induction of IL-1ra was already visible after 2 h of stimulation and persisted at least for 24 h. The amounts of induced IL-1ra were equal or higher than those obtained using other IL-1ra stimuli (LPS, IL-1beta, IFNgamma, IL-4, dexamethasone). This prolonged and quantitatively elevated induction of IL-1ra may contribute to the anti-inflammatory effect of IFNbeta and partially account for the reduction of exacerbation rate shown in most IFNbeta-treated MS patients.

Protein kinase C-alpha and -beta play antagonistic roles in the differentiation process of THP-1 cells

The roles of protein kinase C (PKC) isoenzymes in the differentiation process of THP-1 cells are investigated. Inhibition of PKC by RO 31-8220 reduces the phagocytosis of latex particles and the release of superoxide, prostaglandin E(2) (PGE(2)), and tumour necrosis factor (TNF)-alpha. The proliferation of THP-1 cells is slightly enhanced by RO 31-8220. Stable transfection of THP-1 cells with asPKC-alpha, and incubation of THP-1 cells with antisense (as) PKC-alpha oligodeoxynucleotides reduces PKC-alpha levels and PKC activity. asPKC-alpha-transfected THP-1 cells show a decreased phagocytosis and a decreased release of superoxide, PGE(2) and TNF-alpha. The proliferation of asPKC-alpha-transfected THP-1 cells is enhanced. Stable transfection of THP-1 cells with asPKC-beta, and incubation of THP-1 cells with asPKC-beta oligodeoxynucleotides, reduces PKC-beta levels and PKC activity. asPKC-beta-transfected THP-1 cells show a decreased phagocytosis, a decreased TNF-alpha release, and a decreased proliferation. However, no difference is measured in the release of superoxide and PGE(2). These results suggest that: (1) PKC-alpha but not PKC-beta is involved in the release of superoxide and PGE(2); (2) TNF-alpha release and the phagocytosis of latex particles are mediated by PKC-alpha, PKC-beta, and other PKC isoenzymes; and (3) PKC-alpha and PKC-beta play antagonistic roles in the differentiation process of THP-1 cells. PKC-alpha promotes the differentiation process of THP-1 cells, PKC-beta retards the differentiation of THP-1 cells into macrophage-like cells.

Modulation of PAF production by incorporation of arachidonic acid and eicosapentaenoic acid in phospholipids of human leukemic monocyte-like cells THP-1

Stimulated leukocytes generate platelet-activating factor (PAF) from membrane 1-O-alkyl-2-acyl-sn-glycerophosphocholine through hydrolysis of fatty acid and subsequent acetylation at the sn2 position of glycerol. Since the enzymes involved in the hydrolysis step of PAF biosynthesis have relative selectivity for arachidonic acid (AA), the fatty acid composition of PAF precursors might modulate PAF production. We studied the effect of AA and eicosapentaenoic acid (EPA) incorporation on PAF biosynthesis, by measuring the incorporation of [(3)H]acetate, in Ca(2+) ionophore (A23187)-stimulated human leukemic monocyte-like cells, THP-1. Supplementation of THP-1 with AA (25 microM, 1 week) or EPA (25 microM, 1 week) led to their efficient incorporation, in comparable quantities and with similar distributions, into phosphatidylcholine and phosphatidylethanolamine, and to a lesser extent into phosphatidylinositol. THP-1 cells supplemented with AA or with EPA synthetized similar amounts of PAF and of acyl analog of PAF under resting condition. However, AA-supplemented cells responded to A23187 stimulation by important raises of PAF (+125.71%) and of acyl analog of PAF (+381.75%) productions, whereas the same stimulation had little effect or no effect at all in cells supplemented with EPA. These results show that both EPA and AA may influence PAF production through their incorporation into PAF precursors, indicating that PAF production might be modulated by the fatty acid composition of its precursors.

In vitro expression of proalpha1(I) collagen mRNA by human pre-osteoclastic cells

In vitro studies have demonstrated that the extracellular matrix modulates the cell phenotype. In the present study we have investigated in vitro proalpha1(I) collagen mRNA expression in a human pre-osteoclastic cell line (FLG 29.1 cells) in basal condition and after various stimuli. In addition, in order to evaluate the effect of cell-cell interactions on collagen type I mRNA expression, we have cultured the human pre-osteoclastic cells FLG 29.1 with either the human osteoblast-like cell line Saos-2 or the bovine bone endothelial cell line BBE. We showed that the FLG 29.1 cells express proal (I) collagen mRNA, whose expression is modulated by phorbol esters (TPA). Co-culturing FLG 29.1 cells with either Saos-2 or BBE cells induced decrease of proalpha1(I) collagen mRNA expression.

Cyclic adenosine monophosphate-responsive elements are involved in the transcriptional activation of the human IL-10 gene in monocytic cells

IL-10 plays an important role in the regulation of immune responses. We and others have demonstrated recently that cyclic adenosine monophosphate (cAMP)-elevating substances up-regulate monocytic IL-10 expression in vitro and in vivo. Computer analysis of the IL-10 promoter/enhancer region localized four putative cAMP-responsive elements (CRE1- 4) with homology to the CRE consensus motif. In electrophoretic mobility shift assays CRE1 and CRE4 bound protein complexes consisting of transcription factors CREB-1 and ATF-1, while CRE3 bound only marginal amounts of CREB-1/ATF-1 in combination with unknown protein(s). CRE2 showed no protein binding activity. In vitro mutation of CRE1 and CRE4 reduced the level of cAMP-stimulated transactivation in reporter gene assays in comparison to the wild-type promoter by 20 % and 50 %, respectively, while mutation of CRE3 had no effect. The main action of CRE4 on cAMP-dependent stimulation is probably based on its adjacent localization to the TATA box and its sequence comprising a perfect half site. Experiments with double and triple mutants and with deleted promoter fragments indicated the participation of additional elements beside the CRE motifs in the cAMP-dependent stimulation. Our data suggest that intracellular cAMP may directly affect expression of the immunoregulatory cytokine IL-10 in monocytic cells via activation of the eukaryotic transcription factors CREB-1 and ATF-1 and their binding to CRE1 and CRE4 in the upstream enhancer of the IL-10 promoter.

Interaction of cationic liposomes and their DNA complexes with monocytic leukemia cells

Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. We examined the relationship between the characteristics of the lipoplexes, their mode of interaction with monocytic THP-1 cells and their ability to transfect these cells. We determined the size and zeta potential of cationic liposomes (composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and its mixtures with neutral lipids), and lipoplexes at different (+/-) charge ratios. As the (+/-) charge ratio of the lipoplexes decreased to (1/1), a significant reduction in zeta potential and an increase in size was observed. The increase in size resulted from fusion between liposomes promoted by DNA, as demonstrated by a lipid mixing assay, and from aggregation of the complexes. Interaction of liposomes and lipoplexes with THP-1 cells was assessed by monitoring lipid mixing ('fusion') as well as binding and cell association. While no lipid mixing was observed with the 1/2 (+/-) lipid/DNA complexes, lipoplexes with higher (+/-) charge ratios underwent significant fusion in conjunction with extensive cell binding. Liposome binding to cells was dependent on the positive charge of the liposomes, and their fusion could be modulated by the co-lipid. DOTAP/phosphatidylethanolamine (1:1) liposomes fused with THP-1 cells, unlike DOTAP/phosphatidylcholine (1:1) liposomes, although both liposome types bound to the cells to a similar extent. The use of inhibitors of endocytosis indicated that fusion of the cationic liposomes with cells occurred mainly at the plasma membrane level. The presence of serum increased the size of the cationic liposomes, but not that of the lipoplexes. Low concentrations of serum (3%) completely inhibited the fusion of cationic liposomes with cells, while inhibiting binding by only 20%. Our results suggest that binding of cationic liposomes and lipoplexes to cells is governed primarily by electrostatic interactions, whereas their fusion is regulated by the lipid composition and sterically favorable interactions with cell surface molecules. In addition our results indicate no correlation between fusion of the lipoplexes with the plasma membrane and the levels of transfection.

TGF-beta increases leukotriene C4 synthase expression in the monocyte-like cell line, THP-1

The goal of this study was to determine whether cytokines modulate leukotriene C4 (LTC4) synthase expression in mononuclear phagocytes. A panel of cytokines was surveyed for changes in LTC4 synthase mRNA in THP-1 cells. TGF-beta1, -2, and -3 had significant stimulatory effects. The addition of TGF-beta resulted in a time-dependent increase in LTC4 synthase mRNA at 6 h, which persisted through 48 h. Furthermore, this conditioning resulted in an increase in immunoreactive protein for LTC4 synthase through 7 days. TGF-beta conditioning of cells resulted in a time- and dose-dependent increase in stimulated LTC4 synthase activity. Following transient transfection of THP-1 cells with a promoter-reporter construct containing 1.2 kb of the LTC4 synthase promoter, TGF-beta treatment resulted in a 2-fold increase in reporter activity. Conditioning with TGF-beta did not prolong the half-life of LTC4 synthase mRNA, as assessed by RNase protection assays in actinomycin D-treated cells. Cycloheximide exposure experiments revealed that new protein synthesis was not required for the observed stimulatory effect of TGF-beta on LTC4 synthase mRNA. We conclude that LTC4 synthase expression is increased at a transcriptional level by TGF-beta in mononuclear phagocytes.

Angiotensin II type 1 receptor-mediated peroxide production in human macrophages

Our previous experiments demonstrated upregulation of the renin-angiotensin system in macrophages, including angiotensin II type 1 (AT1) and type 2 (AT2) receptors, during transformation from monocytes. We investigated the role of angiotensin II in oxidative stress of monocytes/macrophages, which plays a role in the advance of atherosclerosis. THP1, a human monocytic leukemia cell line, was differentiated to macrophages by adding of phorbol 12-myristate 13-acetate for 24 hours. The intracellular production of peroxide was measured by a cytofluorometric assay with 2', 7'-dichlorofluorescein-diacetate with a flow cytometer scan. Peroxide was detected in monocytes and upregulated during the transformation to macrophages by 3.18+/-0.52 times in relative fluorescein of peak value (P<0.01). Angiotensin II (1 micromol/L) induced oxidative stress in macrophages, with the peak at 15 minutes by 451+/-223%, and returned to the control level within 1 hour. EC50 was 5.4x10(-9) mol/L. AT1 antagonist (CV11974, 1 micromol/L) significantly decreased angiotensin II-induced oxidative stress in macrophages, but AT2 antagonist (PD123319, 1 micromol/L) did not. Of interest, AT1 antagonist also decreased basal levels of peroxide production in macrophages in a dose-dependent manner. These results suggest that upregulation of the expression of AT1 receptor in macrophages contributes in part to upregulation of peroxide production. AT1 receptor antagonists may be useful to suppress oxidative stress of macrophages in atherosclerotic lesions.

Structure activity relationships of antiproliferative rocaglamide derivatives from Aglaia species (Meliaceae)

Eleven rocaglamide derivatives (cyclopentatetrahydrobenzofurans) and one structurally related aglain congener all isolated from different Aglaia species (Meliaceae) were tested for growth inhibiting properties using the human cancer cell lines MONO-MAC-6 and MEL-JUSO. Proliferation of both cell lines was efficiently inhibited in a dose and compound dependent manner. Applying MTT-Assay, the IC50 of the most active compound didesmethyl-rocaglamide (1) was observed at 0.002 and 0.006 micrograms/ml (0.004 and 0.013 microM) depending on the cell line investigated. Bulky aminoacyl substituents at C-2, acetylation of the OH substituent at C-1 or insertion of a OH or OMe substituent at C-3 of the rocaglamide skeleton all diminished the activity of the compounds investigated. The aglain derivative 12 was inactive up to a concentration of 3 micrograms/ml (4.6 microM). This loss of activity is assumed to be mainly due to the presence of a pyran ring in the aglains vs. a furan ring as found in rocaglamide derivatives. Rocaglamide derivatives may act primarily by inhibition of cell proliferation as evidenced by the absence of a significant cytotoxic effect in long-term cultures of MONO-MAC-6 cells treated with high doses of didesmethylrocaglamide. Our data suggest that rocaglamide derivatives could exert a potential role in the treatment of malignant diseases and are worth to be investigated in further studies of experimental medicine and pharmacology.

Telomerase inhibition, telomere shortening, and senescence of cancer cells by tea catechins

Animal in vivo studies and human epidemiological observations indicated potent anticancer effects for tea. Here we demonstrate that epigallocatechin gallate (EGCG), a major tea catechin, strongly and directly inhibits telomerase, an enzyme essential for unlocking the proliferative capacity of cancer cells by maintaining the tips of their chromosomes. Telomerase inhibition was elaborated in a cell-free system (cell extract) as well as in living cells. In addition, the continued growth of two representative human cancer cell lines, U937 monoblastoid leukemia cells and HT29 colon adenocarcinoma cells, in the presence of nontoxic concentrations of EGCG showed life span limitations accompanied with telomere shortening, chromosomal abnormalities, and expression of the senescence-associated beta-galactosidase. It is suggested that telomerase inhibition could be one of the major mechanisms underlying the anticancer effects of tea.

Multiple splicing events involved in regulation of human aromatase expression by a novel promoter, I.6

The expression of aromatase is regulated in a tissue-specific fashion through alternative use of multiple promoter-specific first exons. To date, eight different first exons have been reported in human aromatase, namely I.1., I.2, I.3. I.4, I.5, PII, 2a, and 1f. Recently, we have found a new putative exon I in a RACE-generated library of THP-1 cells and have conducted studies to characterize this new exon I. We confirmed that the constructs containing -1552/+17 or less flanking sequence of this exon function as a promoter in THP-1 cells, JEG-3 cells and osteoblast-like cells obtained from a human fetus. Results of transfection assays using a series of deletion constructs and mutation constructs indicate that a 1-bp mismatch of the consensus TATA-like box (TTTAAT) and the consensus sequence of the initiator site, which is located 45 bp downstream of the putative TATA box, were functioning cooperatively as a core promoter. The putative transcription site was confirmed by the results of RT-PCR southern blot analysis. We examined the regulation and the expression of this exon, I.6, in several human cells and tissues by RT-PCR Southern blot analysis. THP-1 cells (mononuclear leukemic origin) and JEG-3 cells (choriocarcinoma origin) expressed exon I.6 in serum-free media. The level of expression was increased by serum and phorbol myristyl acetate (PMA) in both cell lines. Adipose stromal cells also expressed exon I.6 in the presence of PMA. In fetal osteoblasts, the expression of exon I.6 was increased most effectively by serum and less so by dexamethasone (DEX) + IL-1beta and DEX + IL-11, whereas induction by serum was suppressed by the addition of DEX. The level of expression was low in granulosa cells in culture and did not change with forskolin. On the other hand, dibutyryl cAMP suppressed PMA-stimulated expression of exon I.6 in THP-1 cells and adipose stromal cells. This result supports the hypothesis that the expression of exon I.6 is regulated mainly via an AP-1 binding site that is found upstream of the initiator site of the promoter region. Expression of exon I.6-specific transcripts was examined in several human tissues. Testis and bone obtained from normal adults expressed exon I.6. Testicular tumor and hepatic carcinoma expressed high levels of exon I.6, whereas granulosa cell tumor did not. Fetal liver and bone also showed a significant level of exon I.6 expression, but not so much as testicular tumor and hepatic tumor. Several splicing variants of exon I.6 were detected especially in THP-1 and JEG-3 cells, and to a lesser extent in primary cultures and tissue samples. These variants were identified as an unspliced form, a form spliced at the end of exon I.4, a form spliced at the end of exon I.3 (truncated) and a form spliced 220 bp downstream of the 3' end of exon I.6. The last variant revealed a new splicing site. Because most of the splicing variants contain the sequence specific for exon I.3, RT-PCR specific for exon I.3 can coamplify these splicing variants of exon I.6 transcripts. These results suggests that it is necessary to examine the expression of I.6 in tissues that are known to express exon I.3 such as breast adipose tissue, in which promoter usage of exon I of the aromatase gene switches from exon I.4 to I.3 in the course of malignant transformation.