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 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 Haemophilus influenzae Porin Induces Toll-Like Receptor 2-Mediated Cytokine Production in Human Monocytes and Mouse Macrophages

2004 ◽  
Vol 72 (2) ◽  
pp. 1204-1209 ◽  
Author(s):  
Marilena Galdiero ◽  
Massimiliano Galdiero ◽  
Emiliana Finamore ◽  
Fabio Rossano ◽  
Maria Gambuzza ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Adaptor Protein ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Necrosis Factor Alpha ◽  
Human Monocytic Cell Line ◽  
Tnf Α ◽  
Human Monocytic Cell

ABSTRACT The production of proinflammatory cytokines is likely to play a major pathophysiological role in meningitis and other infections caused by Haemophilus influenzae type b (Hib). Previous studies have shown that Hib porin contributes to signaling of the inflammatory cascade. We examined here the role of Toll-like receptors (TLRs) and the TLR-associated adaptor protein MyD88 in Hib porin-induced production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Hib porin-induced TNF-α and IL-6 production was virtually eliminated in macrophages from TLR2- or MyD88-deficient mice. In contrast, macrophages from lipopolysaccharide (LPS)-hyporesponsive C3H/HeJ mice, which are defective in TLR4 function, responded normally to Hib porin. Moreover anti-TLR2 antibodies but not anti-TLR4 antibodies significantly reduced Hib porin-stimulated TNF-α and IL-6 release from the human monocytic cell line THP-1. These data indicate that the TLR2/MyD88 pathway plays an essential role in Hib porin-mediated cytokine production. These findings may be useful in the development of alternative therapies aimed at reducing excessive inflammatory responses during Hib infections.

scholarly journals DENGUE VIRUS ALTERS SIALIC ACID RESIDUES CONFIGURATION IN MACROPHAGES

2021 ◽  
Author(s):  
Javier Serrato-Salas ◽  
Isabel Cruz Zazueta ◽  
Jose Luis Montiel Hernandez ◽  
Judith Gonzalez Christen
Keyword(s):  
Sialic Acid ◽  
Virus Infection ◽  
Dengue Virus ◽  
Dengue Virus Infection ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Human Monocytic Cell ◽  
Selective Mechanism

The activation of the innate immune response requires sialic acid residues removal. Nevertheless, it is unknown the role of these changes during the Dengue virus infection. We determine if during Dengue virus infection, the sialic acid residues alter on the macrophages. The human monocytic cell line THP-1 was differentiated into macrophages and were infected with Dengue virus. The changes in sialic acid were evaluated by lectin blot in the cellular lysate. The activity of neuraminidase was defined by RT-PCR and fluorescence assays. Macrophages infection with DENV-2 reduces α-2,6 sialic acid residues at 24 h, and α-2,3 sialic acid residues lower at 48 h in some proteins. Transcriptional profile and enzymatic activities of Neu-1 showed a narrow decrease. Sialic acid residues oscillation in varied conformations and times suggest a role of a selective mechanism to remove these residues. The lesser participation of Neu-1 in this process could be concomitant to other similar enzymes such as sialyl-transferases, or the phenomenon requires minimal activity to have a relevant biological function.

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 A dual positive and negative regulation of monocyte activation by leukocyte Ig-like receptor B4 depends on the position of the tyrosine residues in its ITIMs

2017 ◽  
Vol 23 (4) ◽  
pp. 381-391 ◽  
Author(s):  
Mijeong Park ◽  
Robert W Liu ◽  
Hongyan An ◽  
Carolyn L Geczy ◽  
Paul S Thomas ◽  
...  
Keyword(s):  
Cell Surface Receptor ◽  
Monocyte Activation ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Tyrosine Residues ◽  
Human Monocytic Cell Line ◽  
Tnf Α ◽  
Human Monocytic Cell ◽  
Surface Receptor ◽  
Bacteria Killing

The leukocyte Ig-like receptor B4 (LILRB4) is an inhibitory cell surface receptor, primarily expressed on mono-myeloid cells. It contains 2 C-type Ig-like extracellular domains and a long cytoplasmic domain that contains three intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIMs). Data suggest that LILRB4 suppresses Fc receptor-dependent monocyte functions via its ITIMs, but relative contributions of the three ITIMs are not characterised. To address this, tyrosine (Tyr) residues at positions 337, 389 and 419 were single, double or triple mutated to phenylalanine and stably transfected into a human monocytic cell line, THP-1. Intact Tyr389 was sufficient to maximally inhibit FcγRI-mediated TNF-α production in THP-1 cells, but, paradoxically, Tyr337 significantly enhanced TNF-α production. In contrast, bactericidal activity was significantly enhanced in mutants containing Tyr419, while Tyr337 markedly inhibited bacteria killing. Taken together, these results indicate that LILRB4 might have dual inhibitory and activating functions, depending on the position of the functional tyrosine residues in its ITIMs and/or the nature of the stimuli.

scholarly journals Regulation of Proinflammatory Cytokine Expression by Shiga Toxin 1 and/or Lipopolysaccharides in the Human Monocytic Cell Line THP-1

2004 ◽  
Vol 72 (5) ◽  
pp. 2618-2627 ◽  
Author(s):  
Lisa M. Harrison ◽  
Wilhelmina C. E. van Haaften ◽  
Vernon L. Tesh
Keyword(s):  
Cell Line ◽  
Shiga Toxin ◽  
Cytokine Expression ◽  
Receptor Expression ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Mrna Induction ◽  
Tnf Α ◽  
Human Monocytic Cell

ABSTRACT Infection with Shiga toxin (Stx)-producing bacteria and the subsequent release of Stxs and endotoxins into the bloodstream may damage blood vessels in the colon, kidneys, and central nervous system, leading to bloody diarrhea, acute renal failure, and neurological complications. The proinflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) may contribute to the pathogenesis of Stx-induced vascular lesions by up-regulating toxin receptor expression on endothelial cells. We previously showed that macrophages treated with purified Shiga toxin 1 (Stx1) or lipopolysaccharides (LPS) secrete TNF-α and IL-1β. Northern blot analysis revealed that treatment of the human monocytic cell line THP-1 with LPS induced a rapid and transient increase in steady-state TNF-α and IL-1β transcripts. In contrast, Stx1 induced slower but prolonged elevations in cytokine transcripts. The presence of both stimulants resulted in optimal cytokine mRNA induction in terms of kinetics and prolonged expression. Compared to LPS, Stx1 was a poor inducer of IL-1β protein expression, although levels of soluble IL-1β induced by all treatments continually increased over 72 h. IL-1β transcripts were not induced by Stx1 B-subunits. Using the transcriptional inhibitor actinomycin D, we determined that treatment with Stx1 or Stx1 plus LPS induced cytokine transcripts with increased stability compared to transcripts induced by LPS alone. For all treatments, IL-1β mRNA decay was slower than TNF-α. Collectively, our data suggest that Stxs affect cytokine expression, in part, at the posttranscriptional level by stabilizing mRNAs. Optimal TNF-α expression occurs when both Stxs and LPS are present.

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