Ship Is Essential for Both Endotoxin- and CpG-Induced Tolerance and for Their Cross-Tolerance.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3440-3440
Author(s):  
Laura M. Sly ◽  
Stephanie L. Omeis ◽  
Michael J. Rauh ◽  
Gerald Krystal
Keyword(s):  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Critical Role ◽  
Endotoxin Tolerance ◽  
Negative Regulator ◽  
In Vivo Studies ◽  
Initial Exposure ◽  
Inflammatory Cytokine Production ◽  
Induced Tolerance

Abstract An initial exposure to lipopolysaccharide (LPS, also known as endotoxin), which activates macrophages via Toll-like receptor 4 (TLR4), induces a transient state of hypo-responsiveness to a subsequent challenge with LPS. The mechanism underlying this phenomenon, termed endotoxin tolerance, remains poorly understood although the activation/upregulation of a number of negative regulators has been implicated. Related to this, we recently demonstrated that the SH2-containing inositol-5′-phosphatase, SHIP, which is a key negative regulator of the PI3K pathway in hematopoietic cells, is essential for endotoxin tolerance. Specifically, we found that SHIP−/− bone marrow derived macrophages (BMmΦs) do not display endotoxin tolerance. Moreover, an initial LPS treatment of wild-type BMmΦs increases the level of SHIP protein 10 fold and this increase is critical for the hypo-responsiveness to a subsequent LPS stimulation. Interestingly, this increase in SHIP protein is mediated by the LPS-induced production of autocrine-acting TGFβ and neutralizing antibodies to TGFβ, as well as antisense oligonucleotides to SHIP, block LPS-induced endotoxin tolerance. In vivo studies with SHIP+/+ and −/− mice confirm these in vitro findings and show a correlation between the duration of endotoxin tolerance and elevated SHIP levels (Sly et al., Immunity, in Press). We have now followed up on these studies by exploring the role of SHIP in the stimulation of other Toll-like receptors. Specifically, we asked whether SHIP plays a role in repressing CpG-induced pro-inflammatory cytokine production, which is mediated via the activation of TLR9. Our results, using SHIP+/+ and −/− BMmΦs, suggest that SHIP negatively regulates this TLR as well and is required for CpG-induced tolerance. Moreover, we found that CpG treated SHIP−/− BMmΦs show higher pro-inflammatory cytokine production compared to their SHIP+/+ counterparts when challenged with LPS. This indicates that SHIP plays a critical role in dampening down inflammatory responses in the innate immune system.

scholarly journals Leishmania donovani infection suppresses Allograft Inflammatory Factor-1 in monocytes and macrophages to inhibit inflammatory responses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ricardo Louzada da Silva ◽  
Diana M. Elizondo ◽  
Nailah Z. D. Brandy ◽  
Naomi L. Haddock ◽  
Thomas A. Boddie ◽  
...  
Keyword(s):  
Immune Evasion ◽  
Inflammatory Cytokine ◽  
Leishmania Donovani ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Bone Marrow Cells ◽  
Parasitic Infections ◽  
Inflammatory Factor ◽  
Immune Functions ◽  
Inflammatory Cytokine Production

AbstractMacrophages and monocytes are important for clearance of Leishmania infections. However, immune evasion tactics employed by the parasite results in suppressed inflammatory responses, marked by deficient macrophage functions and increased accumulation of monocytes. This results in an ineffective ability to clear parasite loads. Allograft Inflammatory Factor-1 (AIF1) is expressed in myeloid cells and serves to promote immune responses. However, AIF1 involvement in monocyte and macrophage functions during parasitic infections has not been explored. This study now shows that Leishmania donovani inhibits AIF1 expression in macrophages to block pro-inflammatory responses. Mice challenged with the parasite had markedly reduced AIF1 expression in splenic macrophages. Follow-up studies using in vitro approaches confirmed that L. donovani infection in macrophages suppresses AIF1 expression, which correlated with reduction in pro-inflammatory cytokine production and increased parasite load. Ectopic overexpression of AIF1 in macrophages provided protection from infection, marked by robust pro-inflammatory cytokine production and efficient pathogen clearance. Further investigations found that inhibiting AIF1 expression in bone marrow cells or monocytes impaired differentiation into functional macrophages. Collectively, results show that AIF1 is a critical regulatory component governing monocyte and macrophage immune functions and that L. donovani infection can suppress the gene as an immune evasion tactic.

Abstract 17107: Distribution of Anti-inflammatory Activity During Remodeling of High Density Lipoprotein: Studies With CSL112

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Svetlana A Diditchenko ◽  
Alexei V Navdaev ◽  
Martin O Spycher ◽  
Samuel D Wright
Keyword(s):  
Cholesterol Efflux ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Ex Vivo ◽  
Negative Regulator ◽  
Inflammatory Activity ◽  
Inhibitory Effects ◽  
Inflammatory Cytokine Production ◽  
Coronary Syndrome ◽  
Anti Inflammatory

Elevated levels of circulating inflammatory markers predict an unfavorable cardiovascular outcome in acute coronary syndrome patients. CSL112 is human apolipoprotein A-I (apoA-I), reconstituted with phosphatidylcholine to form HDL particles suitable for infusion. Addition of CSL112 to stimulated human whole blood ex vivo strongly reduces pro-inflammatory cytokine production. Infusion of CSL112 into human subjects or addition to human plasma ex vivo causes remodeling of endogenous HDL. Similar remodeling occurs upon incubation of CSL112 with purified HDL3 and results in accumulation of three HDL species: enlarged HDL (HDL2), a smaller, dense species (HDL3c), and lipid-poor apoA-I (pre-β1 HDL). Study aim was to determine the anti-inflammatory activity of remodeled HDL species. CSL112 was incubated with HDL3 and the products of particle remodeling were purified by ultracentrifugation. The inhibitory effects on pro-inflammatory cytokine production were examined using human peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin-M (PHA-M) in vitro. Lipid-poor apoA-I, HDL3c as well as parent CSL112 exerted powerful inhibitory effects on secretion of pro-inflammatory mediators (> 89.2% + 4.0% inhibition of TNF-α, IL-1β, IL-6 and Mip-1β); HDL3 and HDL2 were much less effective (< 54.1% + 3.9% inhibition). The extent of inhibition correlated positively with induction of the transcription repressor ATF3, a negative regulator of pro-inflammatory cytokine production, with lipid-poor apoA-I and HDL3c inducing higher protein levels of ATF3 in PHA-stimulated PBMC compared to control medium, HDL3 or HDL2. Anti-inflammatory activity of the remodeled species also correlated with their ability to support cellular cholesterol efflux via the ABCA1 transporter: lipid-poor apoA-I and HDL3c were potent acceptors of cholesterol; HDL2 was inactive. The ability to generate HDL species with high cholesterol efflux and anti-inflammatory activity makes CSL112 a promising candidate for removing cholesterol and reducing inflammation in atherosclerotic plaque, thus reducing the high risk of early recurrent atherothrombotic events following acute MI (AMI). A Phase IIb trial (AEGIS-I; NCT02108262) of CSL112 in AMI patients is ongoing.

scholarly journals C4b binding protein negatively regulates TLR1/2 response

2016 ◽  
Vol 23 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Naoko Morita ◽  
Ikuko Yamai ◽  
Koichiro Takahashi ◽  
Yutaka Kusumoto ◽  
Takuma Shibata ◽  
...  
Keyword(s):  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Binding Protein ◽  
Negative Regulation ◽  
Negative Regulator ◽  
Wild Type ◽  
Inflammatory Cytokine Production ◽  
Inflammatory Signals ◽  
Deficient Mice

TLR2 associates with TLR1 and recognizes microbial lipoproteins. Pam3CSK4, a triacylated lipoprotein, is anchored to the extracellular domain of TLR1 and TLR2 and induces pro-inflammatory signals. Here we show that C4b binding protein (C4BP), which is a complement pathway inhibitor, is a TLR2-associated molecule. Immunoprecipitation assay using anti-TLR2 mAb shows that C4BP binds to TLR2. In C4BP-deficient mice, Pam3CSK4-induced IL-6 levels were increased compared with wild type mice. In C4BP-expressing cells, Pam3CSK4-induced IL-8 production was reduced depending on the C4BP expression levels. These results reveal the important role of C4BP in negative regulation of TLR1/2-dependent pro-inflammatory cytokine production. Furthermore, using a fluorescent conjugated Pam3CSK4, we show that C4BP blocks the binding of Pam3CSK4 to TLR1/2. Finally, we show that exogenous C4BP also inhibits Pam3CSK4-induced signaling leading to IL-8 production. Our results indicate C4BP binding to TLR2 and consequent neutralization of its activity otherwise inducing pro-inflammatory cytokine production. C4BP is a negative regulator of TLR1/2 activity.

scholarly journals Functionally distinct subsets of human FOXP3+ Treg cells that phenotypically mirror effector Th cells

Blood ◽  
2012 ◽  
Vol 119 (19) ◽  
pp. 4430-4440 ◽  
Author(s):  
Thomas Duhen ◽  
Rebekka Duhen ◽  
Antonio Lanzavecchia ◽  
Federica Sallusto ◽  
Daniel J. Campbell
Keyword(s):  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Treg Cells ◽  
Receptor Expression ◽  
Inflammatory Cytokine Production ◽  
Th Cell ◽  
Different Types ◽  
Anti Inflammatory ◽  
Anti Inflammatory Cytokine

Abstract FOXP3+ regulatory T (Treg) cells are a broadly acting and potent anti-inflammatory population of CD4+ T cells essential for maintaining immune homeostasis and preventing debilitating autoimmunity. Based on chemokine receptor expression, we identified distinct populations of Treg cells in human blood expected to colocalize with different Th cell subsets. Although each population was functionally suppressive, they displayed unique patterns of pro- and anti-inflammatory cytokine production, differentially expressed lineage-specifying transcription factors, and responded differently to antigens associated with Th1 and Th17 responses. These results highlight a previously unappreciated degree of phenotypic and functional diversity in human Treg cells that allows subsets with unique specificities and immunomodulatory functions to be targeted to defined immune environments during different types of inflammatory responses.

scholarly journals SARS-CoV-2/ACE2 Interaction Suppresses IRAK-M Expression and Promotes Pro-Inflammatory Cytokine Production in Macrophages

2021 ◽  
Vol 12 ◽  
Author(s):  
Ioanna Pantazi ◽  
Ahmed A. Al-Qahtani ◽  
Fatimah S Alhamlan ◽  
Hani Alothaid ◽  
Sabine Matou-Nasri ◽  
...  
Keyword(s):  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Cell Types ◽  
Mrna Levels ◽  
Cytokine Storm ◽  
Inflammatory Cytokine Production ◽  
S Protein ◽  
Cytokines And Chemokines ◽  
Anti Inflammatory

The major cause of death in SARS-CoV-2 infected patients is due to de-regulation of the innate immune system and development of cytokine storm. SARS-CoV-2 infects multiple cell types in the lung, including macrophages, by engagement of its spike (S) protein on angiotensin converting enzyme 2 (ACE2) receptor. ACE2 receptor initiates signals in macrophages that modulate their activation, including production of cytokines and chemokines. IL-1R-associated kinase (IRAK)-M is a central regulator of inflammatory responses regulating the magnitude of TLR responsiveness. Aim of the work was to investigate whether SARS-CoV-2 S protein-initiated signals modulate pro-inflammatory cytokine production in macrophages. For this purpose, we treated PMA-differentiated THP-1 human macrophages with SARS-CoV-2 S protein and measured the induction of inflammatory mediators including IL6, TNFα, IL8, CXCL5, and MIP1a. The results showed that SARS-CoV-2 S protein induced IL6, MIP1a and TNFα mRNA expression, while it had no effect on IL8 and CXCL5 mRNA levels. We further examined whether SARS-CoV-2 S protein altered the responsiveness of macrophages to TLR signals. Treatment of LPS-activated macrophages with SARS-CoV-2 S protein augmented IL6 and MIP1a mRNA, an effect that was evident at the protein level only for IL6. Similarly, treatment of PAM3csk4 stimulated macrophages with SARS-CoV-2 S protein resulted in increased mRNA of IL6, while TNFα and MIP1a were unaffected. The results were confirmed in primary human peripheral monocytic cells (PBMCs) and isolated CD14+ monocytes. Macrophage responsiveness to TLR ligands is regulated by IRAK-M, an inactive IRAK kinase isoform. Indeed, we found that SARS-CoV-2 S protein suppressed IRAK-M mRNA and protein expression both in THP1 macrophages and primary human PBMCs and CD14+ monocytes. Engagement of SARS-CoV-2 S protein with ACE2 results in internalization of ACE2 and suppression of its activity. Activation of ACE2 has been previously shown to induce anti-inflammatory responses in macrophages. Treatment of macrophages with the ACE2 activator DIZE suppressed the pro-inflammatory action of SARS-CoV-2. Our results demonstrated that SARS-CoV-2/ACE2 interaction rendered macrophages hyper-responsive to TLR signals, suppressed IRAK-M and promoted pro-inflammatory cytokine expression. Thus, activation of ACE2 may be a potential anti-inflammatory therapeutic strategy to eliminate the development of cytokine storm observed in COVID-19 patients.

scholarly journals IRF5 Promotes Influenza Virus-Induced Inflammatory Responses in Human Induced Pluripotent Stem Cell-Derived Myeloid Cells and Murine Models

2020 ◽  
Vol 94 (9) ◽  
Author(s):  
Jessica L. Forbester ◽  
Mathew Clement ◽  
Dannielle Wellington ◽  
Amy Yeung ◽  
Sandra Dimonte ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Replication ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Myeloid Cells ◽  
Innate Immune ◽  
Inflammatory Cytokine Production ◽  
Induced Pluripotent

ABSTRACT Recognition of influenza A virus (IAV) by the innate immune system triggers pathways that restrict viral replication, activate innate immune cells, and regulate adaptive immunity. However, excessive innate immune activation can exaggerate disease. The pathways promoting excessive activation are incompletely understood, with limited experimental models to investigate the mechanisms driving influenza virus-induced inflammation in humans. Interferon regulatory factor 5 (IRF5) is a transcription factor that plays important roles in the induction of cytokines after viral sensing. In an in vivo model of IAV infection, IRF5 deficiency reduced IAV-driven immune pathology and associated inflammatory cytokine production, specifically reducing cytokine-producing myeloid cell populations in Irf5−/− mice but not impacting type 1 interferon (IFN) production or virus replication. Using cytometry by time of flight (CyTOF), we identified that human lung IRF5 expression was highest in cells of the myeloid lineage. To investigate the role of IRF5 in mediating human inflammatory responses by myeloid cells to IAV, we employed human-induced pluripotent stem cells (hIPSCs) with biallelic mutations in IRF5, demonstrating for the first time that induced pluripotent stem cell-derived dendritic cells (iPS-DCs) with biallelic mutations can be used to investigate the regulation of human virus-induced immune responses. Using this technology, we reveal that IRF5 deficiency in human DCs, or macrophages, corresponded with reduced virus-induced inflammatory cytokine production, with IRF5 acting downstream of Toll-like receptor 7 (TLR7) and, possibly, retinoic acid-inducible gene I (RIG-I) after viral sensing. Thus, IRF5 acts as a regulator of myeloid cell inflammatory cytokine production during IAV infection in mice and humans and drives immune-mediated viral pathogenesis independently of type 1 IFN and virus replication. IMPORTANCE The inflammatory response to influenza A virus (IAV) participates in infection control but contributes to disease severity. After viral detection, intracellular pathways are activated, initiating cytokine production, but these pathways are incompletely understood. We show that interferon regulatory factor 5 (IRF5) mediates IAV-induced inflammation and, in mice, drives pathology. This was independent of antiviral type 1 IFN and virus replication, implying that IRF5 could be specifically targeted to treat influenza virus-induced inflammation. We show for the first time that human iPSC technology can be exploited in genetic studies of virus-induced immune responses. Using this technology, we deleted IRF5 in human myeloid cells. These IRF5-deficient cells exhibited impaired influenza virus-induced cytokine production and revealed that IRF5 acts downstream of Toll-like receptor 7 and possibly retinoic acid-inducible gene I. Our data demonstrate the importance of IRF5 in influenza virus-induced inflammation, suggesting that genetic variation in the IRF5 gene may influence host susceptibility to viral diseases.

scholarly journals Entamoeba histolytica activation of caspase-1 degrades cullin that attenuates NF-κB dependent signaling from macrophages

2021 ◽  
Vol 17 (9) ◽  
pp. e1009936
Author(s):  
Attinder Chadha ◽  
France Moreau ◽  
Shanshan Wang ◽  
Antoine Dufour ◽  
Kris Chadee
Keyword(s):  
Entamoeba Histolytica ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Cysteine Proteinases ◽  
Inflammatory Cytokine Production ◽  
Downstream Signaling ◽  
Caspase 1 ◽  
Tnf Α ◽  
Cullin 4A

While Entamoeba histolytica (Eh)-induced pro-inflammatory responses are critical in disease pathogenesis, the downstream signaling pathways that subsequently dampens inflammation and the immune response remains unclear. Eh in contact with macrophages suppresses NF-κB signaling while favoring NLRP3-dependent pro-inflammatory cytokine production by an unknown mechanism. Cullin-1 and cullin-5 (cullin-1/5) assembled into a multi-subunit RING E3 ubiquitin ligase complex are substrates for neddylation that regulates the ubiquitination pathway important in NF-κB activity and pro-inflammatory cytokine production. In this study, we showed that upon live Eh contact with human macrophages, cullin-1/4A/4B/5 but not cullin-2/3, were degraded within 10 minutes. Similar degradation of cullin-1/5 were observed from colonic epithelial cells and proximal colonic loops tissues of mice inoculated with live Eh. Degradation of cullin-1/5 was dependent on Eh-induced activation of caspase-1 via the NLRP3 inflammasome. Unlike cullin-4B, the degradation of cullin-4A was partially dependent on caspase-1 and was inhibited with a pan caspase inhibitor. Cullin-1/5 degradation was dependent on Eh cysteine proteinases EhCP-A1 and EhCP-A4, but not EhCP-A5, based on pharmacological inhibition of the cysteine proteinases and EhCP-A5 deficient parasites. siRNA silencing of cullin-1/5 decreased the phosphorylation of pIκ-Bα in response to Eh and LPS stimulation and downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. These results unravel a unique outside-in strategy employed by Eh to attenuate NF-κB-dependent pro-inflammatory responses via NLRP3 activation of caspase-1 that degraded cullin-1/5 from macrophages.

Abstract 382: Lipin-1 Links Pro-inflammatory Responses and Foam Cell Formation by Oxidized-Low Density Lipoprotein-Elicited Macrophages

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Aaron R Navratil ◽  
Aimee E Vozenilek ◽  
James A Cardelli ◽  
Jonette M Green ◽  
A W Orr ◽  
...  
Keyword(s):  
Lipid Droplet ◽  
Inflammatory Cytokine ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Foam Cell ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Wild Type ◽  
Inflammatory Cytokine Production ◽  
Lipin 1

Atherosclerosis is a chronic inflammatory disease of large and medium-sized arteries and one of the underlying causes of cardiovascular disease (CVD). Macrophages participate decisively in the development and promotion of atherosclerosis. Macrophages infiltrate the arterial intima to ingest modified low density lipoproteins (e.g. oxLDLs) via scavenger receptors. The scavenging of oxLDLs results in foam cell formation due to enhanced lipid droplet biogenesis. These foam cells eventually release pro-inflammatory cytokines that promote atherosclerosis. However, it is currently unknown whether there is a link between lipid droplet biogenesis and pro-inflammatory cytokine production in macrophages that scavenge oxLDL. Lipin-1, a phosphatidate phosphohydrolase enzyme, partially contributes to macrophage pro-inflammatory cytokine production following stimulation with bacteria. Lipin-1 is also required for lipid droplet biogenesis in macrophages. Finally, we observed lipin-1 protein within macrophages from human atherosclerotic plaques. Thus, we hypothesized that lipid droplet biogenesis, via lipin-1 activity, directly contributes to foam cell pro-inflammatory cytokine production. To test this hypothesis we compared lipid droplet biogenesis and pro-inflammatory cytokine responses of oxLDL-stimulated wild type and lipin-1-depleted macrophages. Depletion of lipin-1 inhibited oxLDL-induced foam cell generation by reducing lipid droplet number, area, and staining intensity. There were no differences in scavenger receptor expression or uptake of oxLDL between wild type and lipin-1-depleted cells. In addition, depletion of lipin-1 also ablated oxLDL-elicited production of the pro-atherogenic cytokines tumor necrosis factor-α and interleukin-6. These findings demonstrate a critical role for lipin-1 in the regulation of macrophage inflammatory responses to oxLDL. Furthermore, these data begin to link foam cell formation, via lipid droplet biogenesis, and pro-inflammatory cytokine production within oxLDL stimulated macrophages. Thus, our studies suggest that lipid droplet biogenesis may be an ideal therapeutic target to inhibit inflammation associated with atherosclerosis to treat CVD.

scholarly journals miR-146a Attenuates Sepsis-Induced Myocardial Dysfunction by Suppressing IRAK1 and TRAF6 via Targeting ErbB4 Expression

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Rui An ◽  
Jianxin Feng ◽  
Cong Xi ◽  
Jian Xu ◽  
Lijun Sun
Keyword(s):  
Myocardial Injury ◽  
Caspase 3 ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Myocardial Dysfunction ◽  
Innate Immune ◽  
Negative Regulator ◽  
Protective Effects ◽  
Inflammatory Cytokine Production ◽  
Potent Negative Regulator

Myocardial dysfunction is a major manifestation of sepsis and closely associated with the increased mortality. MicroRNA-146 is one of the most important microRNAs identified as a potent negative regulator in innate immune and inflammatory responses induced by lipopolysaccharide (LPS). We aimed to identify the role and potential regulatory mechanism of miR-146a in sepsis-induced cardiac dysfunction with the induction of ErbB4 signaling. H9C2 cells were treated with LPS to induce sepsis, and miR-146a overexpression significantly increased the cell viability, reduced the apoptosis and ROS level, and attenuated the release of proinflammatory cytokines including TNF-α and IL-1β. Levels of ErbB4, p-NF-κB, NF-κB, TRAF6, IRAK1, caspase 3, Bcl-2, and Bax were measured by Western blot. The overexpression of miR-146a significantly increased the ErbB4 expression, decreased the expression of TRAF6, IRAK1, caspase 3, and the phosphorylation level of NF-κB, and also increased the Bcl-2/Bax ratio, suggesting the inhibition of inflammation and apoptosis. The protective effects were all abolished by the use of siErbB4. In conclusion, our results demonstrated that the overexpression of miR-146a mitigates myocardial injury by negatively regulating NF-κB activation and inflammatory cytokine production via targeting ErbB4 in LPS-induced sepsis.

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