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Thang LV, Demel SL, Crawford R, Kaminski NE, Swain GM, Van Rooijen N, Galligan JJ. Macrophage depletion lowers blood pressure and restores sympathetic nerve α2-adrenergic receptor function in mesenteric arteries of DOCA-salt hypertensive rats. Am J Physiol Heart Circ Physiol 2015; 309:H1186-97. [PMID: 26320034 DOI: 10.1152/ajpheart.00283.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/25/2015] [Indexed: 02/07/2023]
Abstract
We tested the hypothesis that vascular macrophage infiltration and O2 (-) release impairs sympathetic nerve α2-adrenergic autoreceptor (α2AR) function in mesenteric arteries (MAs) of DOCA-salt hypertensive rats. Male rats were uninephrectomized or sham operated (sham). DOCA pellets were implanted subcutaneously in uninephrectomized rats who were provided high-salt drinking water or high-salt water with apocynin. Sham rats received tap water. Blood pressure was measured using radiotelemetry. Treatment of sham and DOCA-salt rats with liposome-encapsulated clodronate was used to deplete macrophages. After 3-5, 10-13, and 18-21 days of DOCA-salt treatment, MAs and peritoneal fluid were harvested from euthanized rats. Norepinephrine (NE) release from periarterial sympathetic nerves was measured in vitro using amperometry with microelectrodes. Macrophage infiltration into MAs as well as TNF-α and p22(phox) were measured using immunohistochemistry. Peritoneal macrophage activation was measured by flow cytometry. O2 (-) was measured using dihydroethidium staining. Hypertension developed over 28 days, and apocynin reduced blood pressure on days 18-21. O2 (-) and macrophage infiltration were greater in DOCA-salt MAs compared with sham MAs after day 10. Peritoneal macrophage activation occurred after day 10 in DOCA-salt rats. Macrophages expressing TNF-α and p22(phox) were localized near sympathetic nerves. Impaired α2AR function and increased NE release from sympathetic nerves occurred in MAs from DOCA-salt rats after day 18. Macrophage depletion reduced blood pressure and vascular O2 (-) while restoring α2AR function in DOCA-salt rats. Macrophage infiltration into the vascular adventitia contributes to increased blood pressure in DOCA-salt rats by releasing O2 (-), which disrupts α2AR function, causing enhanced NE release from sympathetic nerves.
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Affiliation(s)
- Loc V Thang
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Stacie L Demel
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Robert Crawford
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan; Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan
| | - Norbert E Kaminski
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan; Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan
| | - Greg M Swain
- Neuroscience Program, Michigan State University, East Lansing, Michigan; Department of Chemistry, Michigan State University, East Lansing, Michigan; and
| | - Nico Van Rooijen
- Department of Molecular Cell Biology, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
| | - James J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan; Neuroscience Program, Michigan State University, East Lansing, Michigan;
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Khan MM, Liu Y, Khan ME, Gilman ML, Khan ST, Bromberg M, Colman RW. Upregulation of tissue factor in monocytes by cleaved high molecular weight kininogen is dependent on TNF-alpha and IL-1beta. Am J Physiol Heart Circ Physiol 2009; 298:H652-8. [PMID: 19966052 DOI: 10.1152/ajpheart.00825.2009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inflammatory bowel disease and arthritis are associated with contact activation that results in cleavage of kininogen to form high molecular weight kininogen (HKa) and bradykinin. We have previously demonstrated that HKa can stimulate inflammatory cytokine and chemokine secretion from human monocytes. We now show that HKa can upregulate tissue factor antigen and procoagulant activity on human monocytes as a function of time (1-4 h) and HKa concentration (75-900 nM). The amino acid sequence responsible to block HKa effects is G440-H455. The HKa receptor macrophage-1 (Mac-1; CD11b18) is the binding site as shown by inhibition by a monoclonal antibody to CD11b/18. Chemical inhibitors of JNK, ERK, and p38 signaling pathways block cell signaling, as does an inhibitor to the transcription factor NF-kappaB. A combination of monoclonal antibodies to TNF-alpha and IL-1beta but neither alone inhibited the HKa induction of tissue factor. These results suggest that HKa mimics LPS by triggering a paracrine pathway in monocytes that depends on TNF-alpha and IL-1beta. Antibodies to kininogen or peptidomimetics might be a useful and safe therapy in inflammatory diseases or sepsis involving cytokines.
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Affiliation(s)
- Mohammad M Khan
- The Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
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3
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Adachi R, Suzuki K. Lyn, one of the Src-family tyrosine kinases expressed in phagocytes, plays an important role in beta2 integrin-signalling pathways in opsonized zymosan-activated macrophage-like U937 cells. Cell Biochem Funct 2007; 25:323-33. [PMID: 17173331 DOI: 10.1002/cbf.1393] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have investigated the contribution of Hck, Lyn and Fgr, highly expressed Src family tyrosine kinases (SFKs) in signalling pathways in opsonized zymosan (OZ)-activated phagocytes by using short interfering RNAs (siRNAs). Treatment of macrophage-like U937 cells with the siRNAs targeted to these transcripts decreased the protein content of each kinase to less than half that of untreated cells. Among these siRNAs, siRNA targeted to Lyn was the most effective in diminishing two kinds of phagocyte functions, that is oxidative burst and phagocytosis. Phosphorylation of c-Cbl, a multidomain adaptor protein in the beta2 integrin-signalling pathway, was also largely inhibited by treatment with siRNA to Lyn. Thus, the results with siRNAs highly specific for Hck, Lyn and Fgr suggested that, among these three SFKs, Lyn plays the most important role in signalling pathways downstream of beta2 integrins in OZ-stimulated phagocytes.
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Affiliation(s)
- Reiko Adachi
- Division of Biosignaling, National Institute of Health Sciences, Setagaya-ku, Tokyo, Japan.
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4
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Luo X, Liu L, Tang N, Lu KQ, McCormick TS, Kang K, Cooper KD. Inhibition of monocyte-derived dendritic cell differentiation and interleukin-12 production by complement iC3b via a mitogen-activated protein kinase signalling pathway. Exp Dermatol 2005; 14:303-10. [PMID: 15810889 DOI: 10.1111/j.0906-6705.2005.00325.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have previously demonstrated that iC3b is deposited at the dermal-epidermal junction of the skin following ultraviolet (UV) exposure and that it plays a role in UV-induced immunosuppression and antigenic tolerance. In vitro, iC3b differentially regulates monocyte production of interleukin-10 (IL-10) and IL-12. Additionally, iC3b arrests monocytic cell differentiation into CD1c-expressing dendritic cell (DC) precursors. The present study addresses mitogen-activated protein kinase (MAPK) signalling following the cross-linking of CR3 by its ligand iC3b with regard to monocyte differentiation and cytokine regulation. Sheep erythrocytes were coated with IgM alone (EA) or iC3b (EAiC3b) to allow for CR3 cross-linking onto monocytes. EAiC3b increased the phosphorylation (p) of extracellular signal-regulated kinase (ERK) MAPK in fresh human monocyte, particularly in monocyte-derived DC (MDDC) that were differentiated by means of GM-CSF (1000 U/ml) and IL-4 (200 U/ml) for 2 days before iC3b exposure for an additional 24 h (P=0.034, n=3). CD1a expression, induced by GM-CSF and IL-4, was inhibited by iC3b (EAiC3b vs. EA, P=0.012, n=4). Conversely, the inhibition of ERK by the specific inhibitor (PD98059), but not the p-38 inhibitor SB203580, restored CD1a expression (P=0.011, n=4) in iC3b-stimulated MDDC. Concordantly, the inhibition of ERK during iC3b exposure fully reversed the inhibition of IL-12p70 induction in MDDC by 95% (P<0.01, n=4) and decreased IL-10 production. Taken together, our data demonstrate that iC3b interferes with MDDC differentiation and IL-12 and IL-10 production is mediated via an ERK MAPK-dependent mechanism. Thus, ERK MAPK inhibition may represent a therapeutic strategy for preventing monocytic precursor diversion away from DC differentiation when monocytes enter injured tissues in which iC3b is generated, such as UV-exposed skin.
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Affiliation(s)
- Xiaoqun Luo
- Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH 44106, USA
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5
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Lee JS, Hmama Z, Mui A, Reiner NE. Stable gene silencing in human monocytic cell lines using lentiviral-delivered small interference RNA. Silencing of the p110alpha isoform of phosphoinositide 3-kinase reveals differential regulation of adherence induced by 1alpha,25-dihydroxycholecalciferol and bacterial lipopolysaccharide. J Biol Chem 2003; 279:9379-88. [PMID: 14672955 DOI: 10.1074/jbc.m310638200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Studying mononuclear phagocyte cell biology through genetic manipulation by non-viral transfection methods has been challenging due to the dual problems of low transfection efficiency and the difficulty in obtaining stable transfection. To overcome this problem, we developed a system for mediating RNA interference in monocytic cells. The p110alpha isoform of phosphoinositide 3-kinases (PI3Ks) was silenced using a lentiviral vector expressing short hairpin RNA (shRNA). This resulted in the generation of stable THP-1 and U-937 monocytic cell lines deficient in p110alpha. Notably, p110alpha was silenced without affecting levels of either the other class I(A) PI3K catalytic subunits p110beta and p110delta, or the p85alpha regulatory subunit. The role of p110alpha in mediating cell adherence was examined. Monocyte adherence induced in response to either lipopolysaccharide (LPS) or 1alpha,25-dihydroxycholecalciferol (D(3)) was blocked by the PI3K inhibitor LY294002. However, although adherence induced in response to D(3) was sensitive to silencing of p110alpha, LPS-induced adherence was not. Expression of the monocyte differentiation marker CD11b was also induced by D(3) in a PI3K-dependent manner and gene silencing using shRNA showed that p110alpha was also required for this effect. Taken together, these findings demonstrate that LPS and D(3) use distinct isoforms of class I(A) PI3K to induce functional responses and that lentiviral-mediated delivery of shRNA is a powerful approach to study monocyte biology.
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Affiliation(s)
- Jimmy S Lee
- Department of Medicine (Division of Infectious Diseases), University of British Columbia, Vancouver, British Columbia V5Z 3J5, Canada
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6
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Engstad CS, Engstad RE, Olsen JO, Osterud B. The effect of soluble beta-1,3-glucan and lipopolysaccharide on cytokine production and coagulation activation in whole blood. Int Immunopharmacol 2002; 2:1585-97. [PMID: 12433059 DOI: 10.1016/s1567-5769(02)00134-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Soluble beta-1,3-glucan has been demonstrated to protect against infection and shock in rats and mice, and clinical studies suggest that administration of soluble glucans to trauma/surgical patients decreases septic complications and improves survival. However, little is known about the precise mechanisms by which glucans influence the state of activation of blood cells, which are responsible for the fulminant cytokine production and the activation of the coagulation system observed in serious gram-negative infection. We studied therefore the effect of an underivatized, soluble yeast beta-1,3-glucan and lipopolysaccharide (LPS), either alone or in combination, on tumor necrosis factor-alpha (TNFalpha), interleukin-6 (IL-6), IL-8 and IL-10 secretion and monocyte tissue factor (TF) expression in human whole blood. As expected, LPS induced the secretion of substantial amounts of all measured parameters, whereas only minor amounts of TNFalpha, IL-6, and IL-10 were induced by beta-glucan itself. However, beta-glucan itself induced the production of significant amounts of IL-8 and TF. Soluble beta-1,3-glucan had a strong synergistic effect on the LPS-induced secretion of IL-8, IL-10, and on monocyte TF activity, but not on TNFalpha and 1L-6 production. On the other hand, soluble beta-glucan strongly primed LPS stimulation of all parameters, including TNFalpha and IL-6. beta-Glucan also induced detectable neutrophil degranulation within 15 min, whereas a response to LPS was first detected after 90 min. In conclusion, soluble beta-1,3-glucan upregulated leukocyte activity, both on its own and in concert with LPS.
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Chakravorty SJ, Cockwell P, Girdlestone J, Brooks CJ, Savage COS. Fractalkine expression on human renal tubular epithelial cells: potential role in mononuclear cell adhesion. Clin Exp Immunol 2002; 129:150-9. [PMID: 12100035 PMCID: PMC1906421 DOI: 10.1046/j.1365-2249.2002.01906.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fractalkine (CX3CL1) is a transmembrane molecule with a CX3C chemokine domain attached to an extracellular mucin stalk which can induce both adhesion and migration of leucocytes. Mononuclear cell infiltration at renal tubular sites and associated tubular epithelial cell damage are key events during acute renal inflammation following renal allograft transplantation. Using northern and Western blot analysis, we have demonstrated the expression of fractalkine message and protein by renal tubular epithelial cells in vitro. The expression was up-regulated by TNF-alpha, a key proinflammatory cytokine in acute rejection. Investigation of surface expression of fractalkine on cultured proximal tubular epithelial cells revealed only a subpopulation of positively staining cells. Immunohistochemistry revealed that only a proportion of tubules in renal allograft biopsies showed induction of fractalkine expression. Studies using a static model of adhesion demonstrated CX3CR1/fractalkine interactions accounted for 26% of monocytic THP-1 cell and 17% of peripheral blood natural killer cell adhesion to tubular epithelial cells, suggesting that fractalkine may have a functional role in leucocyte adhesion and retention, at selected tubular sites in acute renal inflammation. Thus, fractalkine blockade strategies could reduce mononuclear cell mediated tubular damage and improve graft survival following kidney transplantation.
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MESH Headings
- Acute Disease
- CX3C Chemokine Receptor 1
- Cell Adhesion/drug effects
- Cell Adhesion/physiology
- Cell Adhesion Molecules/biosynthesis
- Cell Adhesion Molecules/genetics
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Chemokine CX3CL1
- Chemokines, CX3C/biosynthesis
- Chemokines, CX3C/genetics
- Chemokines, CX3C/pharmacology
- Chemokines, CX3C/physiology
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Gene Expression Regulation/drug effects
- Graft Rejection/metabolism
- Graft Rejection/pathology
- Humans
- Inflammation
- Kidney Transplantation
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/pathology
- Killer Cells, Natural/cytology
- Killer Cells, Natural/metabolism
- Membrane Proteins/biosynthesis
- Membrane Proteins/genetics
- Membrane Proteins/pharmacology
- Membrane Proteins/physiology
- Monocytes/cytology
- Monocytes/metabolism
- Receptors, Cytokine/physiology
- Receptors, HIV/physiology
- Recombinant Proteins/pharmacology
- Tumor Cells, Cultured
- Tumor Necrosis Factor-alpha/pharmacology
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Affiliation(s)
- S J Chakravorty
- Renal Immunobiology, MRC Centre for Immune Regulation, The Medical School, University of Birmingham, UK
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8
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McGilvray ID, Tsai V, Marshall JC, Dackiw APB, Rotstein OD. Monocyte adhesion and transmigration induce tissue factor expression: role of the mitogen-activated protein kinases. Shock 2002; 18:51-7. [PMID: 12095134 DOI: 10.1097/00024382-200207000-00010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The expression of tissue factor (TF) by monocytes that have transmigrated across the endothelium to sites of extravascular inflammation acts both to focus and amplify the inflammatory response. Because clustering of the integrins responsible for endothelial adhesion and transmigration induces tyrosine phosphorylation and activation of the mitogen-activated protein (MAP) kinases, we postulated that transmigration might lead to monocyte activation and TF production. Monocytes were migrated across TNFalpha-primed ECV304 cells grown on fibronectin-coated Transwell chambers in response to FMLP (10(-8) M). After transmigration, monocytes showed a time-dependent increase in surface TF expression and biological procoagulant activity. TF expression was dependent on monocyte adhesion to ECV304 cells. Specifically, TF was not induced by FMLP treatment of suspended monocytes, by migration across fibronectin alone, or by soluble factors induced during migration, whereas monocyte-ECV304 adhesion was sufficient to stimulate TF. Antibodies against CD29 (beta1 integrin), but not against CD18 (beta2 integrin) or CD31 (PECAM-1), inhibited TF expression. Monocyte adhesion to ECV304 cells induced tyrosine phosphorylation of cellular proteins and specifically of the ERK and p38 MAP kinases. Tyrosine kinase inhibition with genistein (10 microg/mL) blocked transmigration, whereas selective ERK inhibition with PD98059 (50 microM) or p38 inhibition with SB203580 (20 microM) did not. However, both ERK and p38 inhibition dose dependently abolished TF expression. These studies suggest that an extravascular focus of infection or inflammation can promote both intravascular thrombosis and extravascular fibrin deposition during the process of adhesion and transmigration across the endothelial barrier. The selective inhibition of the mitogen-activated protein kinases may offer a novel therapeutic means of modulating this inflammatory sequence.
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Affiliation(s)
- Ian D McGilvray
- Department of Surgery, University of Toronto and University Health Network, Ontario, Canada
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9
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Sabatier F, Roux V, Anfosso F, Camoin L, Sampol J, Dignat-George F. Interaction of endothelial microparticles with monocytic cells in vitro induces tissue factor-dependent procoagulant activity. Blood 2002; 99:3962-70. [PMID: 12010795 DOI: 10.1182/blood.v99.11.3962] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the present study we investigated whether endothelial microparticles (EMPs) can bind to monocytic THP-1 cells and modulate their procoagulant properties. Using flow cytometry, we demonstrated that EMPs express adhesive receptors similar to those expressed by activated endothelial cells. Expression of endothelial antigens by THP-1 cells incubated with EMP was shown by immunoperoxidase staining and flow cytometry using antibodies directed against E-selectin, VCAM-1, and endoglin. EMP binding to THP-1 cells was time- and concentration- dependent, reached a plateau at 15 minutes, and had an EMP-to-monocyte ratio of 50:1. EMP binding was not affected by low temperature and was not followed by the restoration of phosphatidylserine asymmetry, suggesting that adhesion was not followed by fusion. A 4-hour incubation of THP-1 cells with EMP led to an increase in procoagulant activity as measured by clotting assay. Concomitantly, THP-1 exhibited increased levels of tissue factor (TF) antigen and TF mRNA compared to control cells. The ability of EMP to induce THP-1 procoagulant activity was significantly reduced when THP-1 cells were incubated with EMP in the presence of blocking antibodies against ICAM-1 and beta2 integrins. These results demonstrate that EMPs interact with THP-1 cells in vitro and stimulate TF-mediated procoagulant activity that is partially dependent on the interaction of ICAM-1 on EMP and its counterreceptor, beta2 integrins, on THP-1 cells. Induction of procoagulant activity was also demonstrated using human monocytes, suggesting a novel mechanism by which EMP may participate in the dissemination and amplification of procoagulant cellular responses.
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Affiliation(s)
- Florence Sabatier
- INSERM EMI 00-19, Laboratoire d'Hématologie et d'Immunologie, UFR de Pharmacie, Université de la Méditerranée, Marseilles, France
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10
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Rosengart MR, Arbabi S, Bauer GJ, Garcia I, Jelacic S, Maier RV. The actin cytoskeleton: an essential component for enhanced TNFalpha production by adherent monocytes. Shock 2002; 17:109-13. [PMID: 11837785 DOI: 10.1097/00024382-200202000-00005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Monocyte adherence induces the formation of focal adhesions, the interaction sites of intracellular signaling molecules and cytoskeletal proteins such as actin. We previously demonstrated that adherence potentiates human monocyte LPS-induced TNFalpha production. Hence, we hypothesized that the actin cytoskeleton is integral to adherence-induced priming for enhanced LPS-induced TNFalpha production. In contrast to nonadherent cells, LPS induced significant transcription of TNFalpha mRNA and production of TNFalpha in adherent monocytes. Disrupting the actin cytoskeleton with cytochalasin D (CD) in adherent monocytes inhibited LPS-induced TNFalpha production by 55%, thereby abrogating adherence-induced priming. Moreover, CD pretreatment abrogated adherence-induced activation of Pyk2, a major focal adhesion kinase, and ERK 1/2, a component of the mitogen-activated protein kinase (MAPK) signaling pathway, and it completely inhibited LPS-induced ERK 1/2 activation. However, CD treatment of nonadherent monocytes failed to inhibit cytokine production. In conclusion, the actin cytoskeleton is integral in the reprogramming of the monocyte for enhanced cytokine production and in maintaining this "primed" state.
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11
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Affiliation(s)
- K. Murali Krishna Rao
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia
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12
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Whitlock BB, Gardai S, Fadok V, Bratton D, Henson PM. Differential roles for alpha(M)beta(2) integrin clustering or activation in the control of apoptosis via regulation of akt and ERK survival mechanisms. J Cell Biol 2000; 151:1305-20. [PMID: 11121444 PMCID: PMC2190581 DOI: 10.1083/jcb.151.6.1305] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2000] [Accepted: 10/27/2000] [Indexed: 12/17/2022] Open
Abstract
The role of integrins in leukocyte apoptosis is unclear, some studies suggest enhancement, others inhibition. We have found that beta(2)-integrin engagement on neutrophils can either inhibit or enhance apoptosis depending on the activation state of the integrin and the presence of proapoptotic stimuli. Both clustering and activation of alpha(M)beta(2) delays spontaneous, or unstimulated, apoptosis, maintains mitochondrial membrane potential, and prevents cytochrome c release. In contrast, in the presence of proapoptotic stimuli, such as Fas ligation, TNFalpha, or UV irradiation, ligation of active alpha(M)beta(2) resulted in enhanced mitochondrial changes and apoptosis. Clustering of inactive integrins did not show this proapoptotic effect and continued to inhibit apoptosis. This discrepancy was attributed to differential signaling in response to integrin clustering versus activation. Clustered, inactive alpha(M)beta(2) was capable of stimulating the kinases ERK and Akt. Activated alpha(M)beta(2) stimulated Akt, but not ERK. When proapoptotic stimuli were combined with either alpha(M)beta(2) clustering or activation, Akt activity was blocked, allowing integrin activation to enhance apoptosis. Clustered, inactive alpha(M)beta(2) continued to inhibit stimulated apoptosis due to maintained ERK activity. Therefore, beta(2)-integrin engagement can both delay and enhance apoptosis in the same cell, suggesting that integrins can play a dual role in the apoptotic progression of leukocytes.
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Affiliation(s)
- Ben B. Whitlock
- Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206
| | - Shyra Gardai
- Departments of Pathology and Immunology, University of Colorado Health Sciences Center, Denver, Colorado 80262
| | - Valerie Fadok
- Departments of Pathology and Immunology, University of Colorado Health Sciences Center, Denver, Colorado 80262
| | - Donna Bratton
- Departments of Pathology and Immunology, University of Colorado Health Sciences Center, Denver, Colorado 80262
| | - Peter M. Henson
- Departments of Pathology and Immunology, University of Colorado Health Sciences Center, Denver, Colorado 80262
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13
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Engagement of CD11b and CD11c β2 integrin by antibodies or soluble CD23 induces IL-1β production on primary human monocytes through mitogen-activated protein kinase–dependent pathways. Blood 2000. [DOI: 10.1182/blood.v95.12.3868] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstractβ2 integrins are involved in the recruitment of leukocytes to inflammatory sites and in cellular activation. We demonstrate that ligation of CD11b (Mac-1, CR3) or CD11c (p150, CR4) alpha chains of β2 integrins by mAbs or soluble chimeric CD23 (sCD23) on human freshly isolated monocytes rapidly stimulates high levels of interleukin-1β production. This induction takes place at the transcriptional level and is regulated by members of the mitogen-activated protein kinase (MAPK) family. Indeed, stimulation of monocytes through engagement of CD11b or CD11c results in the phosphorylation and activation of ERK1, ERK2, and p38/SAPK2 MAP kinases. U0126, a potent inhibitor of the upstream activator of ERK1/2, ie, MEK1/2, suppresses IL-1β messenger RNA (mRNA) expression in a dose-dependent fashion, showing the implication of this pathway in the transcriptional control of IL-1β production. On the other hand, inhibition of p38 by SB203580 indicates that this MAPK is involved in the control of IL-1β production at both transcriptional and translational levels. Together these data demonstrate that ligation of CD11b and CD11c β2 integrins by mAbs or sCD23 fusion proteins triggers the activation of 2 distinct MAPK signaling pathways that cooperate in controlling IL-1β synthesis at different levels.
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14
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Engagement of CD11b and CD11c β2 integrin by antibodies or soluble CD23 induces IL-1β production on primary human monocytes through mitogen-activated protein kinase–dependent pathways. Blood 2000. [DOI: 10.1182/blood.v95.12.3868.012k43_3868_3877] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
β2 integrins are involved in the recruitment of leukocytes to inflammatory sites and in cellular activation. We demonstrate that ligation of CD11b (Mac-1, CR3) or CD11c (p150, CR4) alpha chains of β2 integrins by mAbs or soluble chimeric CD23 (sCD23) on human freshly isolated monocytes rapidly stimulates high levels of interleukin-1β production. This induction takes place at the transcriptional level and is regulated by members of the mitogen-activated protein kinase (MAPK) family. Indeed, stimulation of monocytes through engagement of CD11b or CD11c results in the phosphorylation and activation of ERK1, ERK2, and p38/SAPK2 MAP kinases. U0126, a potent inhibitor of the upstream activator of ERK1/2, ie, MEK1/2, suppresses IL-1β messenger RNA (mRNA) expression in a dose-dependent fashion, showing the implication of this pathway in the transcriptional control of IL-1β production. On the other hand, inhibition of p38 by SB203580 indicates that this MAPK is involved in the control of IL-1β production at both transcriptional and translational levels. Together these data demonstrate that ligation of CD11b and CD11c β2 integrins by mAbs or sCD23 fusion proteins triggers the activation of 2 distinct MAPK signaling pathways that cooperate in controlling IL-1β synthesis at different levels.
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15
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Abstract
The endothelium plays a crucial dynamic role as a protective interface between blood and the underlying tissues during the haemostatic process, which maintains blood flow in the circulation and prevents life-threatening blood loss. Following vessel wall injury with initial platelet adhesion and aggregation to exposed subendothelial extracellular matrix, the initiation, amplification, and control of haemostasis depend on structurally unrelated membrane-associated receptors for blood coagulation proteases including tissue factor, G-protein-coupled protease-activatable receptors, thrombomodulin, and protein C receptor, respectively. In addition to their regulatory role in haemostasis, the respective (pro-)enzyme ligands such as Factors VIIa and Xa, thrombin or protein C mediate specific signalling pathways in vascular cells related to migration, proliferation or adhesion. The functional importance of these receptors beyond haemostasis has been manifested by various lethal and pathological phenotypes in knock-out mice. These protease receptors thereby provide important molecular links in the vascular system and serve to integrate haemostasis with endothelial cell functions which are relevant for the (patho-)physiological responses to injury or inflammatory challenges.
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Affiliation(s)
- K T Preissner
- Institut für Biochemie, Fachbereich Humanmedizin, Justus-Liebig-Universität, D-35392 Giessen, Germany.
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