scholarly journals Palmitate Activates CCL4 Expression in Human Monocytic Cells via TLR4/MyD88 Dependent Activation of NF-κB/MAPK/ PI3K Signaling Systems

2018 ◽  
Vol 46 (3) ◽  
pp. 953-964 ◽  
Author(s):  
Shihab Kochumon ◽  
Ajit Wilson ◽  
Betty Chandy ◽  
Steve Shenouda ◽  
Jaakko Tuomilehto ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Kinase Inhibitors ◽  
Underlying Mechanism ◽  
Positive Control ◽  
Pi3k Signaling ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Metabolic Inflammation ◽  
Wide Range

Background/Aims: Obesity is associated with adipose tissue inflammation which plays a key role in the development of insulin resistance and type 2 diabetes (T2D). Saturated free fatty acids (SFAs) levels are found to be elevated in obesity and T2D. Chemokines are known to have potent inflammatory functions in a wide range of biological processes linked to immunological disorders. Since CCL4 (Chemokine (C-C motif) ligand 4), also known as macrophage inflammatory protein-1β (MIP-1β), plays an important role in the migration of monocytes into the adipose tissue, we investigated the expression of CCL4 in monocytic cells/macrophages following activation with free fatty acid palmitate. Methods: Human monocytic cell line THP-1 and macrophages derived from THP-1 and primary monocytes were stimulated with palmitate and LPS (positive control). CCL4 expression and secretion were measured with real time RT-PCR and ELISA respectively. Signaling pathways were identified by using THP-1-XBlueTM cells, THP-1-XBlueTM-defMyD cells, anti-TLR4 mAb and TLR4 siRNA. Results: Palmitate induces CCL4 expression at both mRNA and protein levels in human monocytic cells. Palmitate-induced CCL4 production was markedly suppressed by neutralizing anti-TLR-4 antibody. Additionally, silencing of TLR4 by siRNA also significantly suppressed the palmitate-induced up-regulation of CCL4. MyD88-deficient cells did not express CCL4 in response to palmitate treatment. Inhibition of NF-kB and MAPK pathways suppressed the palmitate mediated induction of CCL4. Moreover, induction of CCL4 was blocked by PI3 Kinase inhibitors LY294002 and wortmannin. Conclusion: Collectively, our results show that palmitate induces CCL4 expression via activation of the TLR4-MyD88/NF-kB/MAPK/ PI3K signaling cascade. Thus, our findings suggest that the palmitate-induced CCL4 production might be an underlying mechanism of metabolic inflammation.

scholarly journals Palmitate-Induced MMP-9 Expression in the Human Monocytic Cells is Mediated through the TLR4-MyD88 Dependent Mechanism

2016 ◽  
Vol 39 (3) ◽  
pp. 889-900 ◽  
Author(s):  
Sardar Sindhu ◽  
Areej Al-Roub ◽  
Merin Koshy ◽  
Reeby Thomas ◽  
Rasheed Ahmad
Keyword(s):  
Underlying Mechanism ◽  
Positive Control ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Metabolic Inflammation ◽  
Human Monocytic Cell Line ◽  
Tnf Α ◽  
Human Monocytic Cell

Background/Aims: Obese individuals are known to have increased Matrix metalloproteinase (MMP)-9 plasma levels and MMP-9 is reported to play an important role in obesity-associated adipose tissue inflammation. Since in obesity, the levels of circulatory saturated free fatty acid (FFA) palmitate (palimitic acid) are increased and modulate the expression of inflammatory mediators, the role of palmitate in the regulation of MMP-9 remains unclear. Methods: Human monocytic cell line THP-1 and primary monocytes were stimulated with palmitate and TNF-α (positive control). MMP-9 expression was assessed with real time RT-PCR and ELISA. Signaling pathways were studied by using THP-1-XBlue™ cells, THP-1-XBlue™-defMyD cells, anti-TLR4 mAb and TLR4 siRNA. Phosphorylation of NF-kB and c-Jun was analyzed by Western blotting. Results: Here, we provide the evidence that palmitate induces MMP-9 expression at both mRNA (THP-1: 6.8 ± 1.2 Fold; P = 0.01; Primary monocytes: 5.9 ± 0.7 Fold; P = 0.0003) and protein (THP1: 1116 ±14 pg/ml; P<0.001; Primary monocytes: 1426 ± 13.8; P = 0.0005) levels in human monocytic cells. Palmitate-induced MMP-9 secretion was markedly suppressed by neutralizing anti-TLR-4 antibody (P < 0.05). Furthermore, genetic silencing of TLR4 by siRNA also significantly abrogated the palmitate-induced up-regulation of MMP-9. Additionally, MyD88-/- THP-1 cells did not express MMP-9 in response to palmitate treatment. Increased NF-κB/AP-1 activity (P<0.05) was also observed in palmitate-treated THP-1 cells. Conclusion: Altogether, these results show that palmitate induces TLR4-dependent activation of MMP-9 gene expression, which requires the recruitment of MyD88 leading to activation of NF-kB/AP-1 transcription factors. Thus, our findings suggest that the palmitate-induced MMP-9 secretion might be an underlying mechanism of its increased levels in obesity and related metabolic inflammation.

scholarly journals Differential Expression of Human MicroRNAs During Dengue Virus Infection in THP-1 Monocytes

2021 ◽  
Vol 11 ◽  
Author(s):  
Átila Duque Rossi ◽  
Luiza Mendonça Higa ◽  
Alice Laschuk Herlinger ◽  
Marcelo Ribeiro-Alves ◽  
Mariane Talon de Menezes ◽  
...  
Keyword(s):  
Dengue Virus ◽  
Differential Expression ◽  
Cellular Response ◽  
Clinical Manifestations ◽  
Hemorrhagic Fever ◽  
Denv Infection ◽  
Proinflammatory Response ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Wide Range

Dengue virus (DENV) is the most widespread arbovirus, responsible for a wide range of clinical manifestations, varying from self-limited illness to severe hemorrhagic fever. Dengue severity is associated with host intense proinflammatory response and monocytes have been considered one of the key cell types involved in the early steps of DENV infection and immunopathogenesis. To better understand cellular mechanisms involved in monocyte infection by DENV, we analyzed the expression levels of 754 human microRNAs in DENV-infected THP-1 cells, a human monocytic cell line. Eleven human microRNAs showed differential expression after DENV infection and gene ontology and enrichment analysis revealed biological processes potentially affected by these molecules. Five downregulated microRNAs were significantly linked to cellular response to stress, four to cell death/apoptosis, two to innate immune responses and one upregulated to vesicle mediated, TGF-β signaling, phosphatidylinositol mediated signaling, lipid metabolism process and blood coagulation.

Comparison of SP-A and LPS effects on the THP-1 monocytic cell line

2000 ◽  
Vol 279 (1) ◽  
pp. L110-L117 ◽  
Author(s):  
Mingchen Song ◽  
David S. Phelps
Keyword(s):  
Protein A ◽  
Surfactant Protein ◽  
Polymyxin B ◽  
Inhibitory Effects ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Similar Treatment ◽  
Tnf Α ◽  
Factor Α

Surfactant protein A (SP-A) increases production of proinflammatory cytokines by monocytic cells, including THP-1 cells, as does lipopolysaccharide (LPS). Herein we report differences in responses to these agents. First, polymyxin B inhibits the LPS response but not the SP-A response. Second, SP-A-induced increases in tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-8 are reduced by >60% if SP-A is preincubated with Survanta (200 μg/ml) for 15 min before addition to THP-1 cells. However, the LPS effects on TNF-α and IL-8 are inhibited by <20% and the effect on IL-1β by <50%. Third, at Survanta levels of 1 mg/ml, SP-A-induced responses are reduced by >90%, and although the inhibitory effects on LPS action increase, they still do not reach those seen with SP-A. Finally, we tested whether SP-A could induce tolerance as LPS does. Pretreatment of THP-1 cells with LPS inhibits their response to subsequent LPS treatment 24 h later, including TNF-α, IL-1β, and IL-8. Similar treatment with SP-A reduces TNF-α, but IL-1β and IL-8 are further increased by the second treatment with SP-A rather than inhibited as with LPS. Thus, whereas both SP-A and LPS stimulate cytokine production, their mechanisms differ with respect to inhibition by surfactant lipids and in ability to induce tolerance.

scholarly journals Interferon-gamma upregulates interleukin-8 gene expression in human monocytic cells by a posttranscriptional mechanism

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 537-542
Author(s):  
MC Bosco ◽  
GL Gusella ◽  
I Espinoza-Delgado ◽  
DL Longo ◽  
L Varesio
Keyword(s):  
Gene Expression ◽  
Interferon Gamma ◽  
Mononuclear Phagocytes ◽  
Interleukin 8 ◽  
Dependent Manner ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Ifn Gamma ◽  
Potent Inducer

Interleukin-8 (IL-8) is a neutrophil chemotactic and activating cytokine that is produced in response to several stimuli. Because monocytic cells are important producers of IL-8, we investigated whether interferon-gamma (IFN-gamma), a potent inducer of activation and differentiation of mononuclear phagocytes, affected IL-8 expression in this cell lineage. We found a low constitutive level of IL-8 mRNA expression that was upregulated by IFN-gamma in a dose- and time- dependent manner and via a protein-synthesis-dependent process in the human monocytic cell line U937. IL-8 protein secretion was also stimulated by IFN-gamma. Nuclear run-on experiments showed that the IL- 8 gene was transcriptionally active in control cells and that IFN-gamma did not enhance the transcriptional activity. The increase in IL-8 mRNA by IFN-gamma was concomitant with the stabilization of the mRNA and, therefore, controlled primarily at a posttranscriptional level. These results represent the first evidence that IFN-gamma upregulates IL-8 gene expression in cells of the monocytic lineage, and show the involvement of posttranscriptional mechanisms in the induction of IL-8 mRNA.

scholarly journals Tissue factor mRNA in THP-1 monocytic cells is regulated at both transcriptional and posttranscriptional levels in response to lipopolysaccharide.

1991 ◽  
Vol 11 (9) ◽  
pp. 4732-4738 ◽  
Author(s):  
K Brand ◽  
B J Fowler ◽  
T S Edgington ◽  
N Mackman
Keyword(s):  
Tissue Factor ◽  
Half Life ◽  
Control Mechanisms ◽  
Mrna Levels ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Human Monocytic Cell Line ◽  
Human Monocytic Cell ◽  
Tf Gene

Tissue factor (TF) is transiently expressed in human monocytes exposed to the inflammatory agonist bacterial lipopolysaccharide (LPS). Since TF is the major cellular initiator of the coagulation protease cascades, it is inferred that its expression within the vasculature is strictly regulated. In this study, we investigated mechanisms which control TF mRNA expression in the human monocytic cell line THP-1. LPS induced a rapid and transient accumulation of the mature 2.2-kb TF mRNA, which was maximal at 2 h. After stimulation, the rate of transcription of the TF gene was increased (3.3 +/- 1.3)fold. In addition, we observed a significant change in TF mRNA stability: at 1 h after LPS stimulation, TF mRNA was stable during a 60-min period and had a half-life of greater than 120 min, whereas at 2 h, the half-life had declined to 25 +/- 5 min. Furthermore, a larger (3.4-kb) TF RNA species was induced in these cells; the size of this species and data from selective hybridizations with intron-specific probes are consistent with the presence of an unspliced copy of intron 1. These results demonstrate that the LPS-induced accumulation of TF mRNA levels in these monocytic cells is accomplished by both transcriptional and posttranscriptional control mechanisms.

scholarly journals Fish Monocytes as a Model for Mycobacterial Host-Pathogen Interactions

2001 ◽  
Vol 69 (12) ◽  
pp. 7310-7317 ◽  
Author(s):  
Sahar H. El-Etr ◽  
Ling Yan ◽  
Jeffrey D. Cirillo
Keyword(s):  
Mycobacterium Smegmatis ◽  
Virulence Determinants ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Vitro Model ◽  
Mycobacterial Pathogenesis ◽  
Identification And Characterization

ABSTRACT Mycobacterium marinum, a relatively rapid-growing fish and human pathogen, has become an important model for the investigation of mycobacterial pathogenesis. M. marinumis closely related to the Mycobacterium tuberculosiscomplex and causes a disease in fish and amphibians with pathology similar to tuberculosis. We have developed an in vitro model for the study of M. marinum virulence mechanisms using the carp monocytic cell line CLC (carp leukocyte culture). We found that fish monocytes can differentiate between pathogenic and nonpathogenic mycobacterial species. Interestingly, M. marinum enters fish monocytes at a 40- to 60-fold-higher rate thanMycobacterium smegmatis. In addition, M. marinum survives and replicates in fish monocytes whileM. smegmatis is killed. We also found that M. marinum inhibits lysosomal fusion in fish monocytes, indicating that these cells may be used to dissect the mechanisms of intracellular trafficking in mycobacteria. We conclude from these observations that monocytic cells from fish, a natural host for M. marinum, provide an extremely valuable model for the identification and characterization of mycobacterial virulence determinants in the laboratory.

scholarly journals NALP1 Influences Susceptibility to Human Congenital Toxoplasmosis, Proinflammatory Cytokine Response, and Fate ofToxoplasma gondii-Infected Monocytic Cells

2010 ◽  
Vol 79 (2) ◽  
pp. 756-766 ◽  
Author(s):  
William H. Witola ◽  
Ernest Mui ◽  
Aubrey Hargrave ◽  
Susan Liu ◽  
Magali Hypolite ◽  
...  
Keyword(s):  
Immune Responses ◽  
Proinflammatory Cytokines ◽  
Congenital Toxoplasmosis ◽  
Genetically Engineered ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells

ABSTRACTNALP1 is a member of the NOD-like receptor (NLR) family of proteins that form inflammasomes. Upon cellular infection or stress, inflammasomes are activated, triggering maturation of proinflammatory cytokines and downstream cellular signaling mediated through the MyD88 adaptor.Toxoplasma gondiiis an obligate intracellular parasite that stimulates production of high levels of proinflammatory cytokines that are important in innate immunity. In this study, susceptibility alleles for human congenital toxoplasmosis were identified in the NALP1 gene. To investigate the role of the NALP1 inflammasome during infection withT. gondii, we genetically engineered a human monocytic cell line for NALP1 gene knockdown by RNA interference. NALP1 silencing attenuated progression ofT. gondiiinfection, with accelerated host cell death and eventual cell disintegration. In line with this observation, upregulation of the proinflammatory cytokines interleukin-1β (IL-1β), IL-18, and IL-12 uponT. gondiiinfection was not observed in monocytic cells with NALP1 knockdown. These findings suggest that the NALP1 inflammasome is critical for mediating innate immune responses toT. gondiiinfection and pathogenesis. Although there have been recent advances in understanding the potent activity of inflammasomes in directing innate immune responses to disease, this is the first report, to our knowledge, on the crucial role of the NALP1 inflammasome in the pathogenesis ofT. gondiiinfections in humans.

scholarly journals Interferon-gamma upregulates interleukin-8 gene expression in human monocytic cells by a posttranscriptional mechanism

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 537-542 ◽  
Author(s):  
MC Bosco ◽  
GL Gusella ◽  
I Espinoza-Delgado ◽  
DL Longo ◽  
L Varesio
Keyword(s):  
Gene Expression ◽  
Interferon Gamma ◽  
Mononuclear Phagocytes ◽  
Interleukin 8 ◽  
Dependent Manner ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Ifn Gamma ◽  
Potent Inducer

Abstract Interleukin-8 (IL-8) is a neutrophil chemotactic and activating cytokine that is produced in response to several stimuli. Because monocytic cells are important producers of IL-8, we investigated whether interferon-gamma (IFN-gamma), a potent inducer of activation and differentiation of mononuclear phagocytes, affected IL-8 expression in this cell lineage. We found a low constitutive level of IL-8 mRNA expression that was upregulated by IFN-gamma in a dose- and time- dependent manner and via a protein-synthesis-dependent process in the human monocytic cell line U937. IL-8 protein secretion was also stimulated by IFN-gamma. Nuclear run-on experiments showed that the IL- 8 gene was transcriptionally active in control cells and that IFN-gamma did not enhance the transcriptional activity. The increase in IL-8 mRNA by IFN-gamma was concomitant with the stabilization of the mRNA and, therefore, controlled primarily at a posttranscriptional level. These results represent the first evidence that IFN-gamma upregulates IL-8 gene expression in cells of the monocytic lineage, and show the involvement of posttranscriptional mechanisms in the induction of IL-8 mRNA.

scholarly journals The Major Receptor for C-Reactive Protein on Leukocytes Is Fcγ Receptor II

1999 ◽  
Vol 190 (4) ◽  
pp. 585-590 ◽  
Author(s):  
Dwaipayan Bharadwaj ◽  
Mary-Pat Stein ◽  
Michael Volzer ◽  
Carolyn Mold ◽  
Terry W. Du Clos
Keyword(s):  
C Reactive Protein ◽  
Phagocytic Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Color Flow ◽  
Monocytic Cells ◽  
Reactive Protein ◽  
High Affinity Receptor ◽  
Affinity Receptor ◽  
K 562 Cells

C-reactive protein (CRP) is an acute phase serum protein that shares several functions with immunoglobulin (Ig)G including complement activation and binding to receptors on monocytes and neutrophils. The identity of the receptor for CRP has been the target of extensive research. We previously determined that CRP binds to the high affinity receptor for IgG, FcγRI (CD64). However, this interaction could not account for the majority of binding of CRP to neutrophils or monocytic cells. We now determine that CRP also interacts with FcγRIIa (CD32), the low affinity receptor for IgG on monocytes and neutrophils. COS-7 cells were transfected with a construct containing the human FcγRIIA cDNA. CRP binding and the presence of CD32 were detected by mAb and analyzed by two-color flow cytometry. Cells expressing CD32 bound CRP in a dose-dependent and saturable manner consistent with receptor binding. CRP bound to transfectants and K-562 cells with similar kinetics, and in both cases binding was completely inhibited by aggregated IgG. On monocytic cell lines, treatment with Bt2cAMP increased FcγRII expression and enhanced CRP binding. CRP also specifically precipitated FcγRI and FcγRII from the monocytic cell line, THP-1. It is suggested that the major receptor for CRP on phagocytic cells is FcγRII.

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