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Hans-Uwe Simon

Publications and source records attributed to Hans-Uwe Simon.

52 records · Page 3Linked to original sources
PubMed2003

Concurrent presence of agonistic and antagonistic anti-CD95 autoantibodies in intravenous Ig preparations.

BACKGROUND: Although there have been several reports suggesting the presence of physiologic anti-CD95 (Fas, APO-1) autoantibodies in human intravenous Ig (IVIg) preparations, it is still unclear whether and under which conditions these autoantibodies block or stimulate the CD95 receptor. OBJECTIVE: We examined the effects of IVIg on CD95-mediated apoptosis in CD95-sensitive human blood neutrophils in vitro. METHODS: The presence of anti-CD95 antibodies was determined by competition assays with flow cytometry. Cell death and apoptosis were assessed by ethidium bromide uptake test and annexin V staining, respectively. RESULTS: Pretreatment of neutrophils with IVIg prevented binding of FITC-conjugated anti-CD95 mAb to the cell surface, suggesting that IVIg contains CD95 autoantibodies. By using low concentrations of IVIg (1 to 10 mg/mL), we observed a dose-dependent inhibition of anti-CD95 mAb (CH11)-mediated neutrophil apoptosis. Higher concentrations of IVIg (20 to 50 mg/mL), however, induced neutrophil death and apoptosis in a dose-dependent manner. This effect was partially blocked by soluble CD95 receptors (recombinant Fc-Fas) but not by an anti-CD95 blocking mAb, which was shown to recognize the CH11 epitope of CD95. CONCLUSION: Both agonistic and antagonistic anti-CD95 antibodies are present in IVIg, and the effect on CD95 is dose-dependent. Our findings have potential implications for IVIg treatment, which is intended to target the CD95 receptor.

Apoptosis↗
PubMed2003

SHP-1: a regulator of neutrophil apoptosis.

The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1) has been implicated in the regulation of differentiation, proliferation, and activation of hematopoietic cells. In this review, we discuss the potential role of SHP-1 in modulating apoptosis pathways in neutrophils. Low enzymatic SHP-1 was associated with increased neutrophil survival in vitro and SHP-1-deficient mice were reported to develop severe neutrophilic inflammatory responses. In contrast, high expression of this phosphatase was observed in neutropenic patients. Moreover, when neutrophils were exposed to Fas ligand, TNF-alpha, or TRAIL, the anti-apoptotic effects of granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), or IFN-gamma were blocked, most likely by SHP-1-mediated inactivation of anti-apoptotic signaling molecules. In summary, the current available data point to an important role of SHP-1 in the regulation of neutrophil apoptosis.

Animals↗
PubMed2003

Neutrophil apoptosis pathways and their modifications in inflammation.

Neutrophils are constantly produced in large numbers in the bone marrow, and the same numbers of cells need to die within a defined time period in order to keep cellular homeostasis under physiologic conditions. Changing the rate of apoptosis rapidly changes cell numbers in such systems. For instance, in many bacterial and autoimmune inflammatory diseases, delayed apoptosis is one important mechanism for neutrophil accumulation. Excessive production of granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF), two important neutrophil survival factors, is often observed in such inflammatory responses. Cytokine withdrawal, as it occurs in the resolution phase of inflammation, leads to the induction of apoptosis. Moreover, neutrophil apoptosis can be accelerated both in the presence and in the absence of survival factors by activation of distinct members of the tumor necrosis factor/nerve growth factor receptor family. This review focuses on recently published work regarding signaling pathways that regulate neutrophil apoptosis.

Animals↗
PubMed2003

Natural history of primary eosinophilic esophagitis: a follow-up of 30 adult patients for up to 11.5 years.

BACKGROUND & AIMS: Primary eosinophilic esophagitis is a chronic, increasingly recognized, interleukin 5-driven inflammatory disorder of the esophagus. The leading symptom in adults is uniform attacks of dysphagia, and the established histologic sign is a dense eosinophilic infiltration of the esophageal epithelium. Before this study, the natural course of eosinophilic esophagitis had not been defined and information regarding potential long-term risks was lacking. METHODS: This prospective case series included 30 adult patients with eosinophilic esophagitis (22 men and 8 women; mean age, 40.6 years) whose diagnosis had been made >1 year before study debut based on typical history, consistent endoscopic abnormalities, and infiltration of the esophageal epithelium with >24 eosinophils/high-power field. After a mean of 7.2 years, patients underwent a comprehensive follow-up examination. RESULTS: All patients survived the study period in good health and stable nutritional state. Dysphagia persisted in 29 patients, exerting a major negative effect on socioprofessional activities on 1 patient and a minor impact on 15. Attacks of dysphagia were more frequent in patients with blood eosinophilia or pronounced endoscopic alterations. The esophageal eosinophilic infiltration persisted in all symptomatic patients, but cell numbers spontaneously decreased significantly (78.7 vs. 40.3 cells/high-power field). The inflammatory process evoked fibrosis of the esophageal lamina propria but did not spread to the stomach or duodenum. No case evolved to a hypereosinophilic syndrome. CONCLUSIONS: Eosinophilic esophagitis, a primary and chronic disease restricted to the esophagus, leads to persistent dysphagia and structural esophageal alterations but does not impact the nutritional state. To date, no malignant potential has been associated with this disease.

Adolescent↗
PubMed2003

Fragility of the esophageal mucosa: a pathognomonic endoscopic sign of primary eosinophilic esophagitis?

BACKGROUND: Primary eosinophilic esophagitis, a chronic inflammatory disorder of the esophagus, evokes recurrent dysphagia. Endoscopy is often unremarkable, and no consensus exists regarding management of resultant dysphagia. The response of a series of patients with primary eosinophilic esophagitis to dilation is reported together with a description of a possibly pathognomonic sign: fragile esophageal mucosa, for which the term "crêpe-paper" mucosa is introduced. METHODS: Five men underwent endoscopy because of dysphagia confirmed (clinically, endoscopically, and histologically) to be caused by primary eosinophilic esophagitis and were treated by bouginage. OBSERVATIONS: All patients had extremely fragile, inelastic, and delicate mucosa, which tore easily even with minor trauma. After the procedure, patients remained asymptomatic for 3 to 24 months. CONCLUSIONS: Primary eosinophilic esophagitis is characterized by fragile esophageal mucosa that readily tears in response to minor trauma during otherwise uneventful diagnostic endoscopy. This "crêpe-paper" sign may alert endoscopists to the presence of the disease when other mucosal alterations are lacking. Dilation is effective for patients with symptoms with minimal morbidity, despite development of disquieting lesions in response to the procedure.

Adult↗
PubMed2003

Macrophage migration inhibitory factor delays apoptosis in neutrophils by inhibiting the mitochondria-dependent death pathway.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine known to activate macrophages and T cells. In this study, we demonstrate that recombinant MIF delays apoptosis of neutrophils in vitro. MIF action is dose and time dependent as well as specific since it was abolished with a neutralizing anti-MIF antibody. MIF, like G-CSF, delayed cleavage of the proapoptotic members of the Bcl-2 family Bid and Bax in neutrophils, suggesting that MIF inhibits apoptosis pathways proximal to mitochondria activation. Indeed, MIF also prevented release of cytochrome c and Smac from the mitochondria and subsequent activation of the critical effector caspase-3 in these cells. Moreover, we observed increased MIF plasma levels in patients with cystic fibrosis, a heterogeneous recessive genetic disorder associated with bacterial infections and delayed neutrophil apoptosis. In conclusion, MIF is a survival cytokine for human neutrophils, a finding with potential pathologic relevance in infectious diseases.

Apoptosis↗
PubMed2003

Metastatic carcinoma presenting with concomitant eosinophilia and thromboembolism.

A case of a 58-year-old female patient who presented with significant blood eosinophilia and thromboembolic events is described. The patient was eventually diagnosed as suffering from a disseminated malignancy of gastrointestinal origin. Immunohistochemical studies of the tumor are presented. These studies show that tumor cells produce interleukin-3 and -5 and granulocyte macrophage-colony stimulating factor. These cytokines are known to support differentiation, proliferation, and survival of eosinophils. Their secretion is the probable explanation for the appearance of high blood eosinophilia in this patient. To the best of our knowledge, combined blood eosinophilia and thromboembolism as presenting manifestations of a solid tumor have never been reported.

Carcinoma↗
PubMed2003

The interleukin-13 production by peripheral blood T cells from atopic dermatitis patients does not require CD2 costimulation.

BACKGROUND: Although allergic mechanisms appear to be important, the pathogenesis of both extrinsic and intrinsic forms of atopic dermatitis (AD) is unknown. METHODS: We compared the cytokine production of peripheral blood mononuclear cells of extrinsic AD (EAD) and intrinsic AD (IAD) patients and normal control individuals after stimulation with anti-CD3 and/or anti-CD28 monoclonal antibodies (mAbs) in the presence or absence of anti-CD2-blocking mAb. The cytokine production was measured by immunoassays in supernatants of 24-hour cultures. RESULTS: EAD patients showed a decreased capacity to synthesize interferon gamma and granulocyte-macrophage colony-stimulating factor upon anti-CD3 mAb stimulation as compared with IAD patients. Both EAD and IAD patients demonstrated an increased production of interleukin (IL)-5 and IL-13. As expected, interferon gamma, granulocyte-macrophage colony-stimulating factor, and IL-5 levels were reduced in the presence of anti-CD2-blocking mAbs. CD28 costimulation restored the release in cultures with anti-CD2 mAbs added, suggesting that CD2 and CD28 have redundant functions in T cell activation and subsequent cytokine production. Strikingly, the IL-13 production was not blocked by anti-CD2 mAbs and also not increased by agonistic anti-CD28 mAb, in particular within the EAD patient group. CONCLUSION: The signalling pathway initiated by the T cell receptor complex leading to increased IL-13 production in AD patients appears to be highly sensitive and is largely independent on CD2 costimulatory signals.

Adult↗
PubMed2002

Eosinophils express functional IL-13 in eosinophilic inflammatory diseases.

IL-13 is an immunoregulatory and effector cytokine in allergic diseases such as bronchial asthma. A variety of immune and non-immune cells are known as IL-13 producers. In this study we investigated whether and under what conditions human eosinophils generate IL-13. Freshly isolated highly purified peripheral blood eosinophils from patients with several eosinophilic inflammatory diseases and from normal control individuals were investigated. We observed that blood eosinophils from patients suffering from bronchial asthma, atopic dermatitis, parasitic infections, hypereosinophilic syndrome, and idiopathic eosinophilic esophagitis expressed IL-13, as assessed by ELISA, ELISPOT assay, flow cytometry, and immunocytochemistry. By using nasal polyp tissues and immunohistochemistry, we demonstrated IL-13 expression in eosinophils under in vivo conditions. In contrast, blood eosinophils from control individuals as well as blood neutrophils from both eosinophilic and control patients did not produce detectable IL-13 levels. However, when blood eosinophils from control individuals were stimulated with GM-CSF or IL-5 in vitro, they generated IL-13 mRNA and protein, suggesting that IL-13 expression by eosinophils under inflammatory conditions is a cytokine-driven process. Stimulation of blood eosinophils containing IL-13 by eotaxin resulted in a rapid release of this cytokine. Eosinophil-derived IL-13 was functional, as it increased the surface expression of the low affinity IgE receptor (CD23) on purified B cells. In conclusion, human eosinophils are able to produce and release functional IL-13 in eosinophilic inflammatory responses.

Adult↗
PubMed2002

Proteomic analysis of human eosinophil activation mediated by mast cells, granulocyte macrophage colony stimulating factor and tumor necrosis factor alpha.

We assessed mast cell influence on eosinophils, the prominent cells in late and chronic allergic reactions, by comparing the proteomic pattern of eosinophils incubated with mast cells, tumor necrosis factor alpha (TNF-alpha) or granulocyte macrophage colony stimulating factor (GM-CSF). Eosinophils were incubated with the human mast cell line HMC-1 cellular sonicate and their survival and GM-CSF production were evaluated. For proteomic studies, eosinophils were cultured with HMC-1 sonicate, TNF-alpha or GM-CSF in the presence of [(35)S]methionine, solubilized and submitted to isolelectric focusing separation and sodium dodecyl sulfate polyacrylamide gel electrophoresis in the ISODALT system, followed by radiofluorography and computer image analysis. HMC-1-incubated eosinophils displayed increased survival partly mediated by mast cell-associated TNF-alpha, and produced GM-CSF. Metabolically labeled eosinophils incubated with either HMC-1, TNF-alpha or GM-CSF released eosinophil peroxidase. Comparison of two-dimensional gel spots from the eosinophils revealed that each of the three activating signals yielded a distinctly different proteomic pattern of labeled polypeptides. GM-CSF provided the strongest signal and the highest rate of protein synthesis (1,018 spots) followed by TNF-alpha (747 spots) and HMC-1 sonicate (611 spots). A portion of spots differed both in terms of quality and quantity. Although each stimulus induced similar functional effects, the resulting biosynthetic programs of the eosinophils greatly differed. The presented proteomic analysis is the first step in the exploration of molecular mechanisms involved in eosinophil activation.

Autocrine Communication↗
PubMed2002

Anti-inflammatory activity of an extract of Petasites hybridus in allergic rhinitis.

Previous studies have suggested that histamine and leukotrienes (LTs) play an important pathobiological role in IgE-mediated allergic diseases. In vitro studies suggested that an extract of Petasites hybridus (Ze339) blocks LT synthesis in monocytes and granulocytes. Petasins are considered to be the pharmacologically active fraction within Ze339. Patients suffering from allergic rhinitis received three times a day two tablets of Ze339 standardized to 8 mg petasins within a time period of 1 week. After 5 days of treatment, Ze339 significantly improved primary end points, which were day- and nighttime nasal symptoms. Nasal resistance, which was measured by rhinomanometry, gradually decreased as a consequence of Ze339 treatment reaching normal levels after 5 days (rhinomanometry: from 403.5+/-62.0 to 844.8+/-38.8 ml). Levels of inflammatory mediators in nasal fluids and serum were measured 90 min after drug administration every day in the morning. After 5 days of treatment, a significant reduction of histamine (from 153.7+/-32.1 to 53.0+/-8.4 pg/ml) and LT levels (LTB4: from 313.1+/-46.5 to 180.6+/-32.2 pg/ml; cysteinyl-LT: from 137.0+/-42.2 to 70.1+/-16.5 pg/ml) could be observed. Moreover, quality-of-life scores significantly improved. The drug had no effect on the distribution of lymphocyte subpopulations in the blood as well as on the capacity of blood leukocytes to generate cytokines and lipid mediators. These results suggest that Ze339 is effective in treating allergic rhinitis patients by decreasing levels of nasal inflammatory mediators.

Adult↗
PubMed2002

Death receptors bind SHP-1 and block cytokine-induced anti-apoptotic signaling in neutrophils.

Death domain-containing receptors of the tumor necrosis factor (TNF)/nerve growth factor (NGF) family can induce apoptosis upon activation in many cellular systems. We show here that a conserved phosphotyrosine-containing motif within the death domain of these receptors can mediate inhibitory functions. The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1), SHP-2 and SH2-containing inositol phosphatase (SHIP) bound to this motif in a caspase-independent but cell-dependent manner. We also found that stimulation of death receptors disrupted anti-apoptosis pathways initiated (at least under certain conditions) by survival factors in neutrophils. In these cells, activation of the tyrosine kinase Lyn, an important anti-apoptotic event, was prevented as a consequence of death-receptor stimulation, most likely through association of the receptor with activated SHP-1. Thus, we provide molecular and functional evidence for negative signaling by death receptors.

Amino Acid Sequence↗
PubMed2002

Inhibitory activity of tryptanthrin on prostaglandin and leukotriene synthesis.

The indolo[2,1- b]quinazoline alkaloid tryptanthrin has previously been identified as the cyclooxygenase-2 (COX-2) inhibitory principle in the extract ZE550 prepared from the medicinal plant Isatis tinctoria (Brassicaceae). We here investigated the potential inhibitory activity of tryptanthrin and ZE550 on COX-2, COX-1 in cellular and cell-free systems. A certain degree of selectivity towards COX-2 was observed when COX-1-dependent formation of thromboxane B(2) (TxB(2)) in HEL cells and COX-2-dependent formation of 6-ketoprostaglandin F(1alpha) (6-keto-PGF(1alpha)) in Mono Mac 6 and RAW 264.7 cells were compared. Preferential inhibition of COX-2 by two orders of magnitude was found in phorbol myristate acetate (PMA) activated bovine aortic coronary endothelial cells (BAECs). Assays with purified COX isoenzymes from sheep confirmed the high selectivity towards COX-2. The leukotriene B(4) (LTB(4)) release from calcium ionophore-stimulated human granulocytes (neutrophils) was used as a model to determine 5-lipoxygenase (5-LOX) activity. Tryptanthrin and the extract ZE550 inhibited LTB(4) release in a dose dependent manner and with a potency comparable to that of the clinically used 5-LOX inhibitor zileuton.

Animals↗
PubMed2002

High serum thymus and activation-regulated chemokine levels in the lymphocytic variant of the hypereosinophilic syndrome.

The idiopathic hypereosinophilic syndrome is associated with expansion of an IL-5-producing T-cell subset in a subgroup of patients. Identification of such patients is critical to adequate management because there is some evidence that they present an increased risk for development of T-cell lymphoma. Although the T(H)2-like cells often bear an aberrant surface phenotype and can readily be detected with flow cytometry, we now show that lymphocyte phenotyping might be normal in some cases. In contrast, serum thymus and activation-regulated chemokine levels are consistently increased in such patients compared with others with persistent idiopathic hyper-eosinophilia and could therefore represent a useful diagnostic tool.

Adolescent↗
PubMed2002

The neutralization of interleukin-5 as a therapeutic concept in allergic inflammation.

Interleukin-5 (IL-5) is an eosinophil differentiation factor. Therefore, increased levels of IL-5 in the bone marrow are associated with increased eosinophil numbers in blood. In addition, IL-5 increases the sensitivity of eosinophils towards other stimuli and delays their cell death. In contrast to other cytokines, IL-5 acts on a limited number of cells only. In fact, high-affinity IL-5 receptors are exclusively expressed by eosinophils and basophils, but no other human cells. Therefore, neutralization of IL-5 appears to be an obvious approach to treat eosinophilic disorders, since no major side effects due to effects on other cells are expected. Results from animal experiments suggested that anti-IL-5 antibodies may have anti-asthmatic activities. In this article, I summarize our current knowledge regarding anti-IL-5 therapy and speculate on the potential use of these drugs in the future.

Animals↗