scholarly journals TLR4-dependent hepcidin expression by myeloid cells in response to bacterial pathogens

Blood ◽  
2006 ◽  
Vol 107 (9) ◽  
pp. 3727-3732 ◽  
Author(s):  
Carole Peyssonnaux ◽  
Annelies S. Zinkernagel ◽  
Vivekanand Datta ◽  
Xavier Lauth ◽  
Randall S. Johnson ◽  
...  
Keyword(s):  
Iron Homeostasis ◽  
Group A Streptococcus ◽  
Bacterial Pathogens ◽  
Myeloid Cell ◽  
Cell Types ◽  
Hepcidin Expression ◽  
Endogenous Expression ◽  
Splenic Macrophages

Hepcidin is an antimicrobial peptide secreted by the liver during inflammation that plays a central role in mammalian iron homeostasis. Here we demonstrate the endogenous expression of hepcidin by macrophages and neutrophils in vitro and in vivo. These myeloid cell types produced hepcidin in response to bacterial pathogens in a toll-like receptor 4 (TLR4)-dependent fashion. Conversely, bacterial stimulation of macrophages triggered a TLR4-dependent reduction in the iron exporter ferroportin. In vivo, intraperitoneal challenge with Pseudomonas aeruginosa induced TLR4-dependent hepcidin expression and iron deposition in splenic macrophages, findings mirrored in subcutaneous infection with group A Streptococcus where hepcidin induction was further observed in neutrophils migrating to the tissue site of infection. Hepcidin expression in cultured hepatocytes or in the livers of mice infected with bacteria was independent of TLR4, suggesting the TLR4-hepcidin pathway is restricted to myeloid cell types. Our findings identify endogenous myeloid cell hepcidin production as a previously unrecognized component of the host response to bacterial pathogens.

scholarly journals Macromolecular Synthesis Shutoff Resistance by Myeloid Cells Is Critical to IRF7-Dependent Systemic Interferon Alpha/Beta Induction after Alphavirus Infection

2019 ◽  
Vol 93 (24) ◽  
Author(s):  
Nishank Bhalla ◽  
Christina L. Gardner ◽  
Sierra N. Downs ◽  
Matthew Dunn ◽  
Chengqun Sun ◽  
...  
Keyword(s):  
Host Cell ◽  
Myeloid Cells ◽  
Myeloid Cell ◽  
Cell Types ◽  
Macromolecular Synthesis ◽  
Transcription Inhibition ◽  
Antiviral Responses ◽  
Alphavirus Infection

ABSTRACT Alphavirus infection of fibroblastic cell types in vitro inhibits host cell translation and transcription, leading to suppression of interferon alpha/beta (IFN-α/β) production. However, the effect of infection upon myeloid cells, which are often the first cells encountered by alphaviruses in vivo, is unclear. Previous studies demonstrated an association of systemic IFN-α/β production with myeloid cell infection efficiency. Murine infection with wild-type Venezuelan equine encephalitis virus (VEEV), a highly myeloid-cell-tropic alphavirus, results in secretion of very high systemic levels of IFN-α/β, suggesting that stress responses in responding cells are active. Here, we infected myeloid cell cultures with VEEV to identify the cellular source of IFN-α/β, the timing and extent of translation and/or transcription inhibition in infected cells, and the transcription factors responsible for IFN-α/β induction. In contrast to fibroblast infection, myeloid cell cultures infected with VEEV secreted IFN-α/β that increased until cell death was observed. VEEV inhibited translation in most cells early after infection (<6 h postinfection [p.i.]), while transcription inhibition occurred later (>6 h p.i.). Furthermore, the interferon regulatory factor 7 (IRF7), but not IRF3, transcription factor was critical for IFN-α/β induction in vitro and in sera of mice. We identified a subset of infected Raw 264.7 myeloid cells that resisted VEEV-induced translation inhibition and secreted IFN-α/β despite virus infection. However, in the absence of IFN receptor signaling, the size of this cell population was diminished. These results indicate that IFN-α/β induction in vivo is IRF7 dependent and arises in part from a subset of myeloid cells that are resistant, in an IFN-α/β-dependent manner, to VEEV-induced macromolecular synthesis inhibition. IMPORTANCE Most previous research exploring the interaction of alphaviruses with host cell antiviral responses has been conducted using fibroblast lineage cell lines. Previous studies have led to the discovery of virus-mediated activities that antagonize host cell antiviral defense pathways, such as host cell translation and transcription inhibition and suppression of STAT1 signaling. However, their relevance and impact upon myeloid lineage cell types, which are key responders during the initial stages of alphavirus infection in vivo, have not been well studied. Here, we demonstrate the different abilities of myeloid cells to resist VEEV infection compared to nonmyeloid cell types and begin to elucidate the mechanisms by which host antiviral responses are upregulated in myeloid cells despite the actions of virus-encoded antagonists.

Mcl-1 in Transgenic Mice Promotes Survival in a Spectrum of Hematopoietic Cell Types and Immortalization in the Myeloid Lineage

Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3226-3239 ◽  
Author(s):  
Ping Zhou ◽  
Liping Qian ◽  
Christine K. Bieszczad ◽  
Randolph Noelle ◽  
Michael Binder ◽  
...  
Keyword(s):  
Myeloid Cells ◽  
Myeloid Cell ◽  
Cell Types ◽  
Cell Number ◽  
Hematopoietic Cell ◽  
Viable Cell Number ◽  
Wide Range ◽  
Transgenic Cells

Abstract Mcl-1 is a member of the Bcl-2 family that is expressed in early monocyte differentiation and that can promote viability on transfection into immature myeloid cells. However, the effects of Mcl-1 are generally short lived compared with those of Bcl-2 and are not obvious in some transfectants. To further explore the effects of this gene, mice were produced that expressed Mcl-1 as a transgene in hematolymphoid tissues. The Mcl-1 transgene was found to cause moderate viability enhancement in a wide range of hematopoietic cell types, including lymphoid (B and T) as well as myeloid cells at both immature and mature stages of differentiation. However, enhanced hematopoietic capacity in transgenic bone marrow and spleen was not reflected in any change in pool sizes in the peripheral blood. In addition, among transgenic cells, mature T cells remained long lived compared with B cells and macrophages could live longer than either of these. Interestingly, when hematopoietic cells were maintained in tissue culture in the presence of interleukin-3, Mcl-1 enhanced the probability of outgrowth of continuously proliferating myeloid cell lines. Thus, Mcl-1 transgenic cells remained subject to normal in vivo homeostatic mechanisms controlling viable cell number, but these constraints could be overridden under specific conditions in vitro. Within the organism, Bcl-2 family members may act at “viability gates” along the differentiation continuum, functioning as part of a system for controlled hematopoietic cell amplification. Enforced expression of even a moderate viability-promoting member of this family such as Mcl-1, within a conducive intra- and extracellular environment in isolation from normal homeostatic constraints, can substantially increase the probability of cell immortalization. © 1998 by The American Society of Hematology.

scholarly journals Albumin coated liposomes: a novel platform for macrophage specific drug delivery

2011 ◽  
Vol 1 (1) ◽  
pp. 2 ◽  
Author(s):  
Clément Vuarchey ◽  
Sushil Kumar ◽  
Reto Schwendener
Keyword(s):  
Drug Delivery ◽  
Drug Carrier ◽  
Cell Types ◽  
Specific Drug ◽  
Splenic Macrophages ◽  
Peg Liposomes ◽  
Short Time ◽  
Liposome Surface

Here we report a new and efficient approach of macrophage specific drug delivery by coating liposomes with albumin. Activated albumin was reacted with liposomes containing polyethylene glycol (PEG) as hydrophilic spacers to create a flexible layer of covalently bound albumin molecules on the liposome surface. Albumin coated liposomes were taken up faster and more efficiently than uncoated liposomes by murine macrophages. Liposome uptake was significantly higher in macropha - ges as compared to other cell types tested (endothelial cells, fibroblasts, tumor cells), suggesting specificity for macrophages. In vivo, splenic macrophages phagocytosed BSA coated liposomes (BSA-L) at faster rates compared to conventional liposomes (L) and PEG liposomes (PEG-L). To prove the effectiveness of this new macrophage specific drug carrier, the bisphosphonates clodronate and zoledronate were encapsulated in BSA-L and compared with conventional liposomes. <em>In vitro</em>, treatment of macrophages with clodronate or zoledronate in BSA-L led to cytotoxic activity within a very short time and to up to 50-fold reduced IC50 concentrations. <em>In vivo</em>, clodronate encapsulated in BSA-L depleted splenic macrophages at a 5-fold lower concentration as conventional clodronate-liposomes. Our results highlight the pharmaceutical benefits of albumin-coated liposomes for macrophage specific drug delivery.

scholarly journals Dopamine Is a Siderophore-Like Iron Chelator That PromotesSalmonella entericaSerovar Typhimurium Virulence in Mice

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Stefanie Dichtl ◽  
Egon Demetz ◽  
David Haschka ◽  
Piotr Tymoszuk ◽  
Verena Petzer ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Iron Uptake ◽  
Iron Homeostasis ◽  
Iron Acquisition ◽  
Lipocalin 2 ◽  
Intracellular Iron ◽  
Content Type ◽  
Hepcidin Expression

ABSTRACTWe have recently shown that the catecholamine dopamine regulates cellular iron homeostasis in macrophages. As iron is an essential nutrient for microbes, and intracellular iron availability affects the growth of intracellular bacteria, we studied whether dopamine administration impacts the course ofSalmonellainfections. Dopamine was found to promote the growth ofSalmonellaboth in culture and within bone marrow-derived macrophages, which was dependent on increased bacterial iron acquisition. Dopamine administration to mice infected withSalmonella entericaserovar Typhimurium resulted in significantly increased bacterial burdens in liver and spleen, as well as reduced survival. The promotion of bacterial growth by dopamine was independent of the siderophore-binding host peptide lipocalin-2. Rather, dopamine enhancement of iron uptake requires both the histidine sensor kinase QseC and bacterial iron transporters, in particular SitABCD, and may also involve the increased expression of bacterial iron uptake genes. Deletion or pharmacological blockade of QseC reduced but did not abolish the growth-promoting effects of dopamine. Dopamine also modulated systemic iron homeostasis by increasing hepcidin expression and depleting macrophages of the iron exporter ferroportin, which enhanced intracellular bacterial growth.Salmonellalacking all central iron uptake pathways failed to benefit from dopamine treatment. These observations are potentially relevant to critically ill patients, in whom the pharmacological administration of catecholamines to improve circulatory performance may exacerbate the course of infection with siderophilic bacteria.IMPORTANCEHere we show that dopamine increases bacterial iron incorporation and promotesSalmonellaTyphimurium growth bothin vitroandin vivo. These observations suggest the potential hazards of pharmacological catecholamine administration in patients with bacterial sepsis but also suggest that the inhibition of bacterial iron acquisition might provide a useful approach to antimicrobial therapy.

Mcl-1 in Transgenic Mice Promotes Survival in a Spectrum of Hematopoietic Cell Types and Immortalization in the Myeloid Lineage

Blood ◽  
1998 ◽  
Vol 92 (9) ◽  
pp. 3226-3239 ◽  
Author(s):  
Ping Zhou ◽  
Liping Qian ◽  
Christine K. Bieszczad ◽  
Randolph Noelle ◽  
Michael Binder ◽  
...  
Keyword(s):  
Myeloid Cells ◽  
Myeloid Cell ◽  
Cell Types ◽  
Cell Number ◽  
Hematopoietic Cell ◽  
Viable Cell Number ◽  
Wide Range ◽  
Transgenic Cells

Mcl-1 is a member of the Bcl-2 family that is expressed in early monocyte differentiation and that can promote viability on transfection into immature myeloid cells. However, the effects of Mcl-1 are generally short lived compared with those of Bcl-2 and are not obvious in some transfectants. To further explore the effects of this gene, mice were produced that expressed Mcl-1 as a transgene in hematolymphoid tissues. The Mcl-1 transgene was found to cause moderate viability enhancement in a wide range of hematopoietic cell types, including lymphoid (B and T) as well as myeloid cells at both immature and mature stages of differentiation. However, enhanced hematopoietic capacity in transgenic bone marrow and spleen was not reflected in any change in pool sizes in the peripheral blood. In addition, among transgenic cells, mature T cells remained long lived compared with B cells and macrophages could live longer than either of these. Interestingly, when hematopoietic cells were maintained in tissue culture in the presence of interleukin-3, Mcl-1 enhanced the probability of outgrowth of continuously proliferating myeloid cell lines. Thus, Mcl-1 transgenic cells remained subject to normal in vivo homeostatic mechanisms controlling viable cell number, but these constraints could be overridden under specific conditions in vitro. Within the organism, Bcl-2 family members may act at “viability gates” along the differentiation continuum, functioning as part of a system for controlled hematopoietic cell amplification. Enforced expression of even a moderate viability-promoting member of this family such as Mcl-1, within a conducive intra- and extracellular environment in isolation from normal homeostatic constraints, can substantially increase the probability of cell immortalization. © 1998 by The American Society of Hematology.

scholarly journals An integrated analysis of myeloid cells identifies gaps in in vitro models of in vivo biology

2019 ◽  
Author(s):  
Nadia Rajab ◽  
Paul W Angel ◽  
Yidi Deng ◽  
Jennifer Gu ◽  
Vanta Jameson ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Stem Cell ◽  
Myeloid Cell ◽  
Cell Types ◽  
In Vitro Models ◽  
Integrated Analysis ◽  
Dendritic Cell Subsets ◽  
Cell Data

SummaryThe Stemformatics myeloid atlas is an integrated transcriptome atlas of human macrophages and dendritic cells that systematically compares freshly isolated tissue-resident, cultured, and stem-cell derived myeloid cell types. We identified two broad classes of tissue-resident macrophages with lung, gut and tumour-associated macrophages most similar to monocytes. Microglia, Kupffer cells and synovial macrophages shared similar profiles with each other, and with cultured macrophages. Pluripotent stem cell-derived macrophages were not reminiscent of fetal-derived cells. Instead, they were characterized by atypical expression of collagen and a highly efferocytotic phenotype. Likewise, Flt3L-derived cord blood dendritic cells were distinct from conventional dendritic cell subsets isolated from primary tissues and lacked expression of key pattern recognition receptors. Myeloid subsets were reproducible across different experimental series, showing the resource is a robust reference for new data. External users can annotate and benchmark their own samples, including annotation of myeloid single cell data at www.stemformatics.org/atlas/myeloid/.

Analysis Of The Molecular Mechanisms Leading To Significantly Higher Serum Hepcidin and More Severe Anemia In Multicentric Castleman’s Disease (MCD) Patients Than In Rheumatoid Arthritis (RA) Patients

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2181-2181
Author(s):  
Soken-Nakazawa J. Song ◽  
Hiroshi Kawabata ◽  
Kazuyuki Yoshizaki
Keyword(s):  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Severe Anemia ◽  
Negative Regulators ◽  
Hepcidin Expression ◽  
Serum Hepcidin ◽  
The Mean

Abstract Background Hepcidin is a key regulator of body iron homeostasis and its increase in synthesis is implicated in anemia of inflammation (AI), which is commonly observed in patients with chronic inflammatory disorders such as MCD and RA. Inflammatory cytokines, mainly interleukin-6 (IL-6), play a central role in hepcidin induction during inflammation. However, tumor necrosis factor-a (TNF-a) does not induce but rather inhibits hepcidin expression in vitro and in vivo. The bone morphogenetic proteins (BMP) and erythropoietin (EPO) are the known positive and negative regulators of hepcidin expression. Our preliminary data has showed that MCD patients have more severe anemia and higher serum hepcidin-25 concentration than did RA patients. To clarify the mechanisms resulting in this difference, the activated patterns of hepcidin-regulating cytokines and their associations with serum hepcidin-25 levels and severity of anemia were analyzed in MCD and RA patients. Methods 42 patients with AI (14 with MCD and 28 with RA) treated with tocilizumab (an anti-IL-6 receptor antibody) were enrolled in this study. Major iron-related parameters including serum hepcidin-25, and serum levels of cytokines including IL-6, TNF-a, BMP and EPO were measured and correlations with hepcidin-25 as well as Hb were evaluated. Effects of cytokines on IL-6-induced hepcidin expression were analyzed in hepatoma cells by quantitative real-time PCR. Results The mean levels of hepcidin-25 at baseline was significantly higher (44.6 ng/ml), and Hb was significantly lower (9.2 g/dL) in MCD, than those in RA (28.6 ng/ml for hepcidin-25, 11.2 g/dL for Hb). There were significant and positive correlations of serum hepcidin-25 levels with serum ferritin and CRP in both groups (r=0.67 and 0.68 for ferritin, and r=0.41 and 0.36 for CRP, p< 0.001 respectively for both). In contrast, serum hepcidin-25 levels did not show any significant correlation with the levels of serum IL-6 or BMP or TNF-a (p > 0.05, respectively for both groups). The mean values of IL-6, TNF-a, BMP2, BMP4 and hepcidin-25 at baseline were elevated in two groups as compared to healthy control. Of note, we found that MCD patients showed significantly lower serum TNF-a (mean 195 pg/ml) and higher serum BMP4 (mean 193 pg/ml) concentrations than did RA patients (TNF-a= 241 pg/ml, BMP4= 92 pg/ml), although the two patient groups showed comparably elevated values for IL-6, BMP2 and EPO (p> 0.05, respectively). Significant improvements in anemia and systemic symptoms, and reductions in serum hepcidin-25 levels were observed within 2 weeks in both groups after tocilizumab treatment. In in vitro experiments, IL-6-induced hepcidin mRNA expression in hepatocytes was completely inhibited with tocilizumab and partially with TNF-a, but enhanced by BMP4 as well as MCD patient's serum. These results suggest that the negative effect of TNF-a on the IL-6-induced hepcidin was more pronounced in the RA than in MCD, in contrast, the positive effect of BMP was stronger in MCD than in RA. In addition, the finding that IL-6-induced hepcidin in hepatocytes was enhanced only by adding MCD patients’ serum but not RA patients’ serum, indicating the activated pattern of serum hepcidin-regulating factors in the MCD different from it in RA. Conclusions Our results suggest that the difference between MCD and RA in serum hepcidin-25 levels is partially due to the different activated patterns of positive and negative regulators of hepcidin expression. By the evidence that treatment with tocilizumab can reduce serum hepcidin and improve AI in patients with MCD and RA, we believe that IL-6 plays an essential role in the induction of hepcidin which leads to AI in MCD and RA, although multiple factors affect hepcidin levels. Disclosures: No relevant conflicts of interest to declare.

Heparin: a potent inhibitor of hepcidin expression in vitro and in vivo

Blood ◽  
2011 ◽  
Vol 117 (3) ◽  
pp. 997-1004 ◽  
Author(s):  
Maura Poli ◽  
Domenico Girelli ◽  
Natascia Campostrini ◽  
Federica Maccarinelli ◽  
Dario Finazzi ◽  
...  
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Serum Iron ◽  
Iron Homeostasis ◽  
Iron Concentration ◽  
Deficiency Anemia ◽  
Hepcidin Expression ◽  
Vein Thrombosis ◽  
Protein Levels

Abstract Hepcidin is a major regulator of iron homeostasis, and its expression in liver is regulated by iron, inflammation, and erythropoietic activity with mechanisms that involve bone morphogenetic proteins (BMPs) binding their receptors and coreceptors. Here we show that exogenous heparin strongly inhibited hepcidin expression in hepatic HepG2 cells at pharmacologic concentrations, with a mechanism that probably involves bone morphogenetic protein 6 sequestering and the blocking of SMAD signaling. Treatment of mice with pharmacologic doses of heparin inhibited liver hepcidin mRNA expression and SMAD phosphorylation, reduced spleen iron concentration, and increased serum iron. Moreover, we observed a strong reduction of serum hepcidin in 5 patients treated with heparin to prevent deep vein thrombosis, which was accompanied by an increase of serum iron and a reduction of C-reactive protein levels. The data show an unrecognized role for heparin in regulating iron homeostasis and indicate novel approaches to the treatment of iron-restricted iron deficiency anemia.

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

Epithelial Organotypic Cultures: A Viable Model to Address Mechanisms of Carcinogenesis by Epitheliotropic Viruses

2018 ◽  
Vol 18 (4) ◽  
pp. 246-255 ◽  
Author(s):  
Lara Termini ◽  
Enrique Boccardo
Keyword(s):  
Three Dimensional ◽  
Cell Types ◽  
Experimental Models ◽  
Biological Research ◽  
Specific Gene ◽  
Specific Cell ◽  
Organotypic Cultures ◽  
Skin Physiology

In vitro culture of primary or established cell lines is one of the leading techniques in many areas of basic biological research. The use of pure or highly enriched cultures of specific cell types obtained from different tissues and genetics backgrounds has greatly contributed to our current understanding of normal and pathological cellular processes. Cells in culture are easily propagated generating an almost endless source of material for experimentation. Besides, they can be manipulated to achieve gene silencing, gene overexpression and genome editing turning possible the dissection of specific gene functions and signaling pathways. However, monolayer and suspension cultures of cells do not reproduce the cell type diversity, cell-cell contacts, cell-matrix interactions and differentiation pathways typical of the three-dimensional environment of tissues and organs from where they were originated. Therefore, different experimental animal models have been developed and applied to address these and other complex issues in vivo. However, these systems are costly and time consuming. Most importantly the use of animals in scientific research poses moral and ethical concerns facing a steadily increasing opposition from different sectors of the society. Therefore, there is an urgent need for the development of alternative in vitro experimental models that accurately reproduce the events observed in vivo to reduce the use of animals. Organotypic cultures combine the flexibility of traditional culture systems with the possibility of culturing different cell types in a 3D environment that reproduces both the structure and the physiology of the parental organ. Here we present a summarized description of the use of epithelial organotypic for the study of skin physiology, human papillomavirus biology and associated tumorigenesis.

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