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 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 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 Increased LPS levels coexist with systemic inflammation and result in monocyte activation in severe COVID-19 patients.

2021 ◽  
Author(s):  
Paula Coelho Teixeira ◽  
Gilson Pires Dorneles ◽  
Paulo Cesar de Santana Filho ◽  
Igor Martins da Silva ◽  
Lucas de Lima Schipper ◽  
...  
Keyword(s):  
Hospital Admission ◽  
Systemic Inflammation ◽  
Chemokine Receptors ◽  
Microbial Translocation ◽  
Monocyte Activation ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Cytokines And Chemokines ◽  
Tnf Α

This study aimed to evaluate the link between microbial translocation markers and systemic inflammation at the earliest time-point after hospitalization and at the last 72 h of hospitalization in survivors and non-survivors COVID-19 patients. Sixty-six SARS-CoV-2 RT-PCR+ infected patients and nine non-COVID-19 pneumonia controls were admitted in this study. Blood samples were collected at hospital admission (T1) (Controls and COVID-19+ patients) and 0-72 h before hospital discharge (T2, alive or dead) to analyze systemic cytokines and chemokines, LPS concentrations, and soluble CD14 (sCD14) levels. THP-1 human monocytic cell line was incubated with plasma from survivors and non-survivors COVID-19 patients and their phenotype, activation status, TLR4, and chemokine receptors were analyzed by flow cytometry. COVID-19 patients presented higher IL-6, IFN-γ, TNF-α, TGF-β1, CCL2/MCP-1, CCL4/MIP-1β, and CCL5/RANTES levels than controls. Moreover, LPS and sCD14 were higher at hospital admission in SARS-CoV-2-infected patients. Non-survivors COVID-19 patients had increased LPS levels concomitant with higher IL-6, TNF-α, CCL2/MCP-1, and CCL5/RANTES levels at T2. Increased expression of CD16 and CCR5 were identified in THP-1 cells incubated with the plasma of survivor patients obtained at T2. The incubation of THP-1 with T2 plasma of non-survivors COVID-19 leads to higher TLR4, CCR2, CCR5, CCR7, and CD69 expression. In conclusion, increased microbial translocation during hospitalization coexist with the inflammatory condition of SARS-CoV-2 infection and could lead to higher monocyte activation in non-survivors COVID-19 patients.

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.

scholarly journals Bioengineered Nanoparticles Loaded-Hydrogels to Target TNF Alpha in Inflammatory Diseases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1111
Author(s):  
Isabel Matos Oliveira ◽  
Diogo Castro Fernandes ◽  
Fátima Raquel Maia ◽  
Raphael Faustino Canadas ◽  
Rui Luís Reis ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Gellan Gum ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Tnf Α ◽  
Human Monocytic Cell ◽  
Vitro Model ◽  
Static Conditions

Rheumatoid Arthritis (RA) is an incurable autoimmune disease that promotes the chronic impairment of patients’ mobility. For this reason, it is vital to develop therapies that target early inflammatory symptoms and act before permanent articular damage. The present study offers two novel therapies based in advanced drug delivery systems for RA treatment: encapsulated chondroitin sulfate modified poly(amidoamine) dendrimer nanoparticles (NPs) covalently bonded to monoclonal anti-TNF α antibody in both Tyramine-Gellan Gum and Tyramine-Gellan Gum/Silk Fibroin hydrogels. Using pro-inflammatory THP-1 (i.e., human monocytic cell line), the therapy was tested in an inflammation in vitro model under both static and dynamic conditions. Firstly, we demonstrated effective NP-antibody functionalization and TNF-α capture. Upon encapsulation, the NPs were released steadily over 21 days. Moreover, in static conditions, the approaches presented good anti-inflammatory activity over time, enabling the retainment of a high percentage of TNF α. To mimic the physiological conditions of the human body, the hydrogels were evaluated in a dual-chamber bioreactor. Dynamic in vitro studies showed absent cytotoxicity in THP-1 cells and a significant reduction of TNF-α in suspension over 14 days for both hydrogels. Thus, the developed approach showed potential for use as personalized medicine to obtain better therapeutic outcomes and decreased adverse effects.

scholarly journals Interleukin-10 Modulates Proinflammatory Cytokines in the Human Monocytic Cell Line THP-1 Stimulated withBorrelia burgdorferi Lipoproteins

2000 ◽  
Vol 68 (12) ◽  
pp. 6663-6669 ◽  
Author(s):  
P. K. Murthy ◽  
Vida A. Dennis ◽  
Barbara L. Lasater ◽  
Mario T. Philipp
Keyword(s):  
Cell Line ◽  
Inflammatory Cytokines ◽  
Cytokine Production ◽  
Interleukin 10 ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Tnf Α ◽  
Human Monocytic Cell ◽  
Kinetics Of

ABSTRACT We determined previously that lipoproteins of Borrelia burgdorferi stimulate inflammatory and anti-inflammatory cytokines (interleukin-10 [IL-10]) in monocytes. IL-10 could have an effect on innate and acquired immune responses to B. burgdorferi and influence the magnitude of the infectious inoculum and disease outcome. To understand the mechanism(s) of IL-10 action during early infection, when innate immunity expressed chiefly by skin macrophages is key, we investigated the effect of exogenous and endogenous IL-10 on the production of the macrophage-derived cytokines IL-6, IL-1β, IL-12, and tumor necrosis factor alpha (TNF-α). We used the THP-1 human monocytic cell line and recombinant lipidated OspA (L-OspA) as the model target cell and stimulant, respectively. To determine the kinetics of cytokine production by THP-1 cells, we stimulated them with L-OspA and also with heat-killed B. burgdorferi cells (HBb) and lipopolysaccharide (LPS). Exogenous IL-10 dampened production of inflammatory cytokines, as elicited by lipoproteins. The inhibition of endogenous IL-10 function by anti-IL-10 antibody reduced the production of IL-12 and IL-6 but not that of IL-1β and TNF-α. An inspection of the kinetics of cytokine production clarified this finding. TNF-α was produced prior to, and IL-β was produced at the same time as, IL-10, whereas IL-6 and IL-12 were produced later. HBb, LPS, and L-OspA yielded similar kinetics of cytokine production. This result reinforces the notion that lipoproteins are the functional molecules in HBb and perhaps in vivo. It indicates also that signaling pathways utilized by LPS and lipoproteins may be extensively shared. The results are consistent with a major role played by IL-10 in controlling the initial phase of infection with this spirochete.

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