Human Eosinophils (human + eosinophil)

Distribution by Scientific Domains


Selected Abstracts


Inhibitory effects of N -acetylcysteine on the functional responses of human eosinophils in vitro

CLINICAL & EXPERIMENTAL ALLERGY, Issue 5 2007
M. Martinez-Losa
Summary Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N -acetyl- l -cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow cytometry), p47phox,p67phox translocation (Western blot) and eosinophil cationic protein (ECP) release (radioimmunoassay). Results NAC (0.1,1 mm) inhibited the extracellular generation of oxygen species induced by N -formyl- l -methionyl- l -leucyl- l -phenylalanine (fMLP) and eotaxin (in the presence of IL-5) with ,logIC50 values of 3.61±0.03 and 3.36±0.09, respectively. Also, the intracellular generation of hydrogen peroxide was virtually abolished by NAC (0.5,1 mm). NAC (1 mm) did not alter the fMLP-induced Ca2+ signal but augmented the eosinophil content of reduced GSH and inhibited p47phox,p67phox translocation. NAC inhibited the release of ECP (,90% inhibition at 1 mm) from fMLP-activated eosinophils. Conclusion Inhibition by NAC of human eosinophil functions in vitro is potentially useful in the treatment of allergic inflammation. [source]


CCR3 functional responses are regulated by both CXCR3 and its ligands CXCL9, CXCL10 and CXCL11

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2003
Georgina Xanthou
Abstract The chemokine receptor CXCR3 is predominantly expressed on T lymphocytes, and its agonists CXCL9, CXCL10 and CXCL11 are IFN-,-inducible chemokines that promote Th1 responses. In contrast, the CCR3 agonists CCL11, CCL24 and CCL26 are involved in the recruitment of cells such as eosinophils and basophils during Th2 responses. Here, we report that although CCL11, CCL24 and CCL26 are neither agonists nor antagonists of CXCR3, CCL11 binds with high affinity to CXCR3. This suggests that, in vivo, CXCR3 may act as a decoy receptor, sequestering locally produced CCL11. We alsodemonstrate that the CXCR3 ligands inhibit CCR3-mediated functional responses of both human eosinophils and CCR3 transfectants induced by all three eotaxins, with CXCL11 being the most efficacious antagonist. The examination of CCR3,CCR1 chimeric constructs revealed that CCL11 and CXCL11 share overlapping binding sites contained within the CCR3 extracellular loops, a region that was previously shown to be essential for effective receptor-activation. Hence, eosinophil responses mediated by chemokines acting at CCR3 may be regulated by two distinct mechanisms: the antagonistic effects of CXCR3 ligands and the sequestration of CCL11 by CXCR3-expressing cells. Such interplay may serve to finely tune inflammatory responses in vivo. [source]


Osteopontin is expressed and functional in human eosinophils

ALLERGY, Issue 2 2010
I. Puxeddu
To cite this article: Puxeddu I, Berkman N, Ribatti D, Bader R, Haitchi HM, Davies DE, Howarth PH, Levi-Schaffer F. Osteopontin is expressed and functional in human eosinophils. Allergy 2010; 65: 168,174. Abstract Background:, Eosinophils are critically involved in allergic inflammation and tissue remodeling. Osteopontin (OPN) is a glycoprotein molecule which exhibits pro-fibrogenic and pro-angiogenic properties and has recently also been implicated in allergic diseases. In this study, we investigated the expression and function of OPN in human eosinophils. Methods:, Osteopontin mRNA (RT-PCR) and protein (immunofluorescence) expression in peripheral blood eosinophils from atopic human subjects were evaluated. Soluble OPN release was determined in resting and activated eosinophils. The contribution of OPN to eosinophil-induced angiogenesis was determined using the chick embryo chorio- allantoic membrane (CAM) assay and OPN-induced eosinophil chemotaxis was determined (ChemoTx System microplate wells). Finally, OPN expression in bronchoalveolar lavage (BAL) fluids from mild asthmatic and normal control subjects was determined. Results:, Osteopontin is expressed in human eosinophils and is increased following GM-CSF and IL-5 activation. Eosinophil-derived OPN contributes to eosinophil-induced angiogenesis. Recombinant OPN promotes eosinophil chemotaxis in vitro and this effect is mediated by ,4,1 integrin binding. Soluble OPN is increased in the bronchoalveolar lavage fluid from mild asthmatic subjects and correlates with eosinophil counts. Conclusions:, We therefore conclude that OPN is likely to contribute to the process of angiogenesis observed in the airways in asthma. [source]


Thioredoxin reduces C-C chemokine-induced chemotaxis of human eosinophils

ALLERGY, Issue 8 2009
N. Kobayashi
Background:, Human thioredoxin (TRX) is one of redox-active proteins that regulate reactive oxidative metabolisms. In recent study, we found that serum levels of TRX were elevated in asthmatic patients with exacerbation; however, few details are known about the physiological role of TRX in allergic inflammation, involving eosinophil infiltration. Objective:, In the present study, we examined whether TRX modulated C-C chemokine-induced chemotaxis of human eosinophils. Methods:, Eosinophils were isolated from subjects with mild eosinophilia by modified CD16 negative selection. After incubation with or without recombinant TRX, chemotaxis of human eosinophils was measured using Boyden chamber. Results:, Preincubation with TRX suppressed eotaxin- and regulated on activation, normal T-cell expressed and secreted (RANTES)-induced chemotaxis of eosinophils. Although, TRX had no effect on the expression of C-C chemokine receptor 3, which is a receptor of eotaxin and RANTES, we demonstrated that the activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinases, which play an important role in eosinophil migration, was attenuated by the treatment with TRX. Conclusion:, Our results suggest that the elicited TRX is beneficial to reduce allergic inflammation through negative regulation of eosinophil functions and has potential in the treatment of allergic diseases, such as asthma. [source]


Inhibitory effects of N -acetylcysteine on the functional responses of human eosinophils in vitro

CLINICAL & EXPERIMENTAL ALLERGY, Issue 5 2007
M. Martinez-Losa
Summary Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N -acetyl- l -cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow cytometry), p47phox,p67phox translocation (Western blot) and eosinophil cationic protein (ECP) release (radioimmunoassay). Results NAC (0.1,1 mm) inhibited the extracellular generation of oxygen species induced by N -formyl- l -methionyl- l -leucyl- l -phenylalanine (fMLP) and eotaxin (in the presence of IL-5) with ,logIC50 values of 3.61±0.03 and 3.36±0.09, respectively. Also, the intracellular generation of hydrogen peroxide was virtually abolished by NAC (0.5,1 mm). NAC (1 mm) did not alter the fMLP-induced Ca2+ signal but augmented the eosinophil content of reduced GSH and inhibited p47phox,p67phox translocation. NAC inhibited the release of ECP (,90% inhibition at 1 mm) from fMLP-activated eosinophils. Conclusion Inhibition by NAC of human eosinophil functions in vitro is potentially useful in the treatment of allergic inflammation. [source]


Expression of the neutrophil-activating CXC chemokine ENA-78/CXCL5 by human eosinophils

CLINICAL & EXPERIMENTAL ALLERGY, Issue 4 2003
T. Persson
Summary Background Eosinophils are seen at sites of inflammation in diseases such as helminthic infestation, asthma, ulcerative colitis and some neoplastic diseases. They are also associated with connective tissue remodelling, for example in longstanding asthma. In the present study, we investigated whether eosinophils express the CXC chemokine epithelial cell-derived neutrophil activating peptide (ENA-78/CXCL5), a chemokine that can activate neutrophils and in addition possesses angiogenic properties. Immunocytochemistry detected CXCL5 in eosinophils and the peptide was localized in the specific granules by immunoelectron microscopy. Methods and Results In eosinophil lysates, 12 ± 2 pg (mean ± SEM) of CXCL5 was detected per 106 cells by enzyme-linked immunosorbent assay (ELISA). Weak constitutive expression of CXCL5, as well as the related CXC chemokine IL,8/CXCL8, could be detected in freshly isolated eosinophils by RT,PCR. However, during prolonged incubation of eosinophils, a strong increase in both CXCL5 and IL-8/CXCL8 expression was seen, as detected by RT-PCR, and increasing amounts of CXCL5 peptide with time were detected in the incubation medium by ELISA. Addition of TNF-, neutralizing antibodies during prolonged incubation significantly inhibited CXCL5 production, demonstrating involvement of auto- and paracrine effects from TNF-, produced by eosinophils themselves. Addition of IFN-, showed a strong inhibitory effect on CXCL5 synthesis. Conclusion These findings suggest that, through expression of CXCL5, eosinophils can recruit and activate CXC receptor 2 (CXCR2)-bearing cells such as neutrophils at sites of inflammation. Eosinophils may also promote connective tissue remodelling through release of this peptide. [source]


Function of Siglec-8 on human eosinophils

CLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 2004
E. Nutku
Summary Eosinophil recruitment and activation are regarded as central to the pathophysiology of allergic diseases, including asthma. An improved understanding of the mechanisms involved in these responses is therefore of great relevance to asthma pathogenesis and the development of new therapeutics. As part of ongoing efforts to discover novel eosinophil-specific molecules, we recently cloned Siglec-8 (formerly called sialoadhesin family member-2) from a human eosinophil cDNA library. Siglecs (sialic acid binding Ig-like lectins) are a family of transmembrane, I-type lectins characterized by an N-terminal V-set Ig domain that binds sialic acid. We now know that Siglec-8 is expressed only on human eosinophils, basophils and mast cells, giving it a unique expression pattern on effector cells of allergic disease. We have determined that in eosinophils, Siglec-8 exists in two isoforms, one of which contains two putative cytoplasmic tyrosine-based signalling motifs, including an ITIM (immunoreceptor tyrosine-based inhibitory motif) sequence. Because of the ITIM sequence, we hypothesized that Siglec-8 ligation would inhibit eosinophil functions. Initial studies found that incubation of eosinophils with Siglec-8 binding monoclonal antibodies under cross-linking conditions caused rapid and profound caspase-dependent apoptosis, and this response could not be rescued by the survival-promoting cytokine interleukin (IL)-5. In fact, IL-5 enhanced the ability of Siglec-8 cross-linking to induce eosinophil apoptosis. Activation via Siglec-8 could potentially be used to inhibit eosinophil survival in vivo, providing a novel strategy for reducing or inhibiting these cells in allergic and other diseases. [source]