What is the role of the eosinophil?

Eosinophilia in very low birth weight infants

BACKGROUND

Eosinophilia is common in premature infants, though its clinical significance remains unknown. This study investigated the pattern of eosinophilia and related factors in very low birth-weight (VLBW) infants.

METHODS

The medical records of VLBW infants (birth body weight < 1500 g) admitted to the neonatal intensive care unit of a tertiary care center of Cheng Kung University Hospital between January 2005 and June 2007 were analyzed. Complete blood counts (CBC) with differential leukocyte counts were performed weekly. Eosinophilia was defined as an eosinophil count of more than 0.700 x 10(9)/L. The possible related factors were analyzed.

RESULTS

A total of 142 infants were recruited into the study. Those who did not survive after the first 28 days and those with less than four available CBCs were excluded, leaving 107 infants and 828 CBC measurements. Overall, 19.0% of CBCs (157/828) indicated eosinophilia and 69.0% of all infants had at least one instance of eosinophilia during their hospital stay. Eosinophilia mainly occurred in the third week of life (27.1%), with an average peak eosinophil count of 0.520 x 10(9)/L. There were 37.3% of patients with mild eosinophilia (0.700-0.999 x 10(9)/L), 50.7% with moderate eosinophilia (1.000-2.999 x 10(9)/L), and 12% with severe eosinophilia (> or =3.000 x 10(9)/L). The demographic data and perinatal characteristics of infants with and without eosinophilia were comparable. Medical treatments including mechanical ventilation, antibiotic administration, total parenteral nutrition, intravenous catheterization, transfusion, and body weight gains were similar between the two groups. The eosinophil counts in the first week of life were significantly higher in infants with bronchopulmonary dysplasia (p < 0.05). They were also greater in VLBW infants with sepsis at the first, the third, the fourth, the fifth and the seventh weeks (p < 0.05).

CONCLUSION

Eosinophilia is common in VLBW infants and occurs mainly in the third week of life. Higher eosinophil counts were associated with sepsis and family history of atopic eczema. Bronchopulmonary dysplasia was associated with higher eosinophil counts in the first week of life.

Evaluation of eosinophilia in hospitalized preterm infants

OBJECTIVE

To characterize changes in eosinophil counts over time, and to draw comparisons across four gestational age groups with respect to the incidence of, and clinical conditions associated with eosinophilia over the first months of life in a single neonatal intensive care unit (NICU).

STUDY DESIGN

Weekly complete blood counts (CBCs) were collected from all NICU patients. Eosinophilia was classified as mild, moderate, or severe. Changes in eosinophil counts were examined over time, the incidence of eosinophilia was determined by gestational age group, and clinical correlations sought.

RESULTS

Eosinophil data from 1652 CBCs were analyzed from 332 infants. Eosinophilia occurred in 148 infants (45%) during their hospitalization. The prevalence, severity, and timing of eosinophilia varied by gestational age, infection, and red blood cell transfusions.

CONCLUSIONS

The incidence and severity of eosinophilia increased with immaturity, and was temporally associated with infection, necrotizing enterocolitis, and packed red blood cell transfusion.

Pharmacology of N-(3,5-dichloro-1-oxido-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline carboxamide (SCH 351591), a novel, orally active phosphodiesterase 4 inhibitor

N-(3,5-Dichloro-1-oxido-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline carboxamide (SCH 351591) has been identified as a potent (IC(50) = 58 nM) and highly selective type 4 phosphodiesterase (PDE4) inhibitor with oral bioactivity in several animal models of lung inflammation. N-(3,5-Dichloro-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline carboxamide (SCH 365351), the only significant in vivo metabolite, is also a potent and highly selective PDE4 inhibitor (IC(50) = 20 nM). Both SCH 351591 and SCH 365351 inhibited cytokine production in human blood mononuclear cell preparations. Oral SCH 351591 significantly attenuated allergen-induced eosinophilia and airway hyperreactivity in allergic guinea pigs at doses as low as 1 mg/kg. In this model, oral SCH 365351 showed similar potency. When SCH 351591 was administered orally to allergic cynomolgus monkeys at 3 mg/kg, Ascaris suum-induced lung eosinophilia was blocked. Hyperventilation-induced bronchospasm in nonallergic guinea pigs, a model for exercise-induced asthma, was also suppressed significantly by oral SCH 351591 at 0.3 mg/kg. Cilomilast (SB 207499; Ariflo), a PDE4 inhibitor currently being developed for asthma and chronic obstructive pulmonary disease (COPD), was 10- to 30-fold less potent than SCH 351591 at inhibiting guinea pig lung eosinophilia and hyperventilation-induced bronchospasm. In a ferret model of emesis, maximum nonemetic oral doses of SCH 351591 and cilomilast were 5 and 1 mg/kg, respectively. Comparison of plasma levels at these nonemetic doses in ferrets to those at doses inhibiting hyperventilation-induced bronchospasm in guinea pigs gave a therapeutic ratio of 16 for SCH 351591 and 4 for cilomilast. Thus, SCH 351591 exhibits a promising preclinical profile as a treatment for asthma and COPD.

Characterization of platelet-activating factor-induced cytosolic calcium mobilization in human eosinophils

BACKGROUND

Activated eosinophils play an important role in the pathogenesis of bronchial asthma and other allergic diseases, and platelet-activating factor (PAF) is a potent activator of eosinophils.

OBJECTIVE

To characterize the cytosolic Ca2+ ([Ca2+]i) mobilization in human eosinophils in response to PAF.

METHODS

[Ca2+]i responses to PAF were examined in human eosinophils using a microscopic fura-2 fluorescence-ratio imaging system.

RESULTS

PAF caused a significant and dose-dependent increase in (Ca2+)i, which consisted of an initial rapid rise followed by a sustained elevation. This PAF-induced (Ca2+)i rise was inhibited by WEB 2086, a specific PAF receptor antagonist. The addition of 5 mM EGTA or 1 mM Ni2+ to a nominally Ca2+-free solution did not appreciably reduce the initial rise but significantly inhibited the sustained rise. The application of a protein kinase C inhibitor, Ro31-8220, augmented the sustained increase by PAF. Thapsigargin, a microsomal Ca2+ ATPase inhibitor, induced no appreciable change in a nominally Ca2+-free solution but induced a marked increase in (Ca2+)i when changed to a Ca2+-containing solution.

CONCLUSIONS

The initial rapid rise and the following sustained rise in (Ca2+)i by PAF depends on Ca2+ release from the intracellular Ca2+ stores and Ca2+ influx, respectively, which are regulated by protein kinase C in human eosinophils. Furthermore, the so called Ca2+-capacitative entry is possibly involved in the Ca2+ influx from the extracellular solution in human eosinophils.

Utilization of biomarker data for clinical and environmental intervention

Of the 189 air toxics listed in the Clean Air Act, a substantial number are important in potentially causing adverse health effects in several organ systems. Although the major health effects are manifested as respiratory diseases, especially airways disease, these agents may cause cancer and premature mortality, probably from cardiopulmonary disease. Validated biologic markers may be useful in identifying early effects to improve our understanding of exposure-response relationships and clarify susceptibility. However, the knowledge obtained from epidemiologic studies utilizing these new molecular tools will reduce morbidity and mortality from air toxics only when they can be applied effectively in the prevention and control of disease. Intervention strategies using these markers can be used to identify etiologic factors and assess the effectiveness of exposure reduction, and, in some instances, chemoprevention. This paper illustrates examples of these intervention strategies and reviews the current strengths and limitations of environmental molecular epidemiology in controlling disease caused by air toxics.

Relationship between cells obtained by bronchoalveolar lavage and survival in idiopathic pulmonary fibrosis

BACKGROUND

The relationship between cell types in bronchoalveolar lavage (BAL) fluid and the clinical course of patients with idiopathic pulmonary fibrosis (IPF) has been the subject of several studies. However, the results of these studies are not conclusive. The aim of this study was to investigate the relationship between the absolute and relative cell numbers in BAL fluid from patients with IPF and their survival.

METHODS

Results obtained from the initial BAL fluid analyses of all histologically proven cases of IPF (n = 49) were selected retrospectively. Cox's proportional hazards survival analysis was used for estimating the relationship between absolute and relative cell numbers and survival.

RESULTS

A negative relationship was found between both the absolute numbers and percentages of eosinophils in BAL fluid samples and survival. No such relationship was demonstrated for the absolute numbers or the percentages of any other cell type.

CONCLUSIONS

Although this study has restrictions, these findings suggest a negative relationship between the absolute numbers and percentages of eosinophils in BAL fluid samples and survival in patients with IPF.

Phosphodiesterase inhibitors reduce bronchial hyperreactivity and airway inflammation in unrestrained guinea pigs

A new guinea pig model of allergic asthma was used to investigate the effects of low doses of the phosphodiesterase inhibitors, rolipram (phosphodiesterase IV selective), ORG 20241 (N-hydroxy-4-(3,4-dimethoxyphenyl)-thiazole-2-carboximidamide; dual phosphodiesterase III/IV inhibitor with some selectivity for the phosphodiesterase IV isoenzyme), and of theophylline (non-selective) on allergen-induced early and late phase asthmatic reactions, bronchial hyperreactivity to histamine inhalation, and airway inflammation. Theophylline (25 mg/kg i.p.) and ORG 20241 (5 mg/kg i.p.) did not affect histamine-induced bronchoconstriction, whereas rolipram (75 micrograms/kg i.p.) only slightly reduced the response to histamine at 7 h after administration. However, bronchial hyperreactivity after the early and after the late reaction was significantly reduced by theophylline, rolipram and ORG 20241, while bronchoalveolar lavage studies revealed a selective inhibition of airway inflammation by the phosphodiesterase inhibitors. Theophylline significantly reduced the number of eosinophils, neutrophils and macrophages; rolipram reduced the number of neutrophils and lymphocytes, and ORG 20241, the number of eosinophils and macrophages. None of the compounds at the dosage indicated reduced the early and late reaction when administered i.p. 1 h before allergen exposure to defined dual responding animals. These results indicate that non-bronchodilator doses of these phosphodiesterase inhibitors markedly reduce the allergen-induced development of bronchial hyperreactivity as well as airway inflammation, presumably by selectively inhibiting cellular migration. The results suggest that an orchestrated series of cellular interactions is involved in the development of bronchial hyperreactivity. It is concluded that phosphodiesterase inhibitors may be very useful in the treatment of bronchial asthma.

Comparison of the role of nasal polyp and normal nasal mucosal epithelial cells on in vitro eosinophil survival. Mediation by GM-CSF and inhibition by dexamethasone

Eosinophilic infiltration of the respiratory mucosa is considered an inflammatory hallmark of allergic rhinitis, bronchial asthma and nasal polyposis. However, the mechanisms involved in this infiltration have not yet been totally elucidated. The objective of this study was to investigate and compare the influence of epithelial cell secretions from both nasal polyps (NP) and normal nasal mucosa (NM) on in vitro eosinophil survival. Epithelial cells were identified by microscopy and immunohistochemistry, cultured to confluence, and human epithelial cell conditioned media (HECM) was generated from cultures. Eosinophils were isolated at high viability and purity (> 90%) from peripheral blood and incubated with HECM. HECM from both NM and NP increased eosinophil survival in a dose-dependent manner, this effect being maximal at a concentration of 25% for NM (73.4% +/- 5.5%, n = 26, P < 0.001) and of 10% for NP (74.5% +/- 8.4%, n = 18, P < 0.001). Incubation of monoclonal antibody to human GM-CSF with HECM, neutralized the induction of eosinophil survival by HECM from both NM and NP. HECM from NP contained higher concentrations of GM-CSF (111 +/- 25.4 pg/ml, n = 17) than HECM from NM (97.1 +/- 15.2 pg/ml, n = 8), without reaching statistical significance. Pre-incubation of dexamethasone with eosinophils also blocked HECM-induced eosinophil survival from both NM (10(-8)-10(-5) M; IC50 = 9.5 nM) and NP (10(-7)-10(-5) M; IC50 = 83 nM). These results suggest that: firstly eosinophil infiltration into the respiratory mucosa during allergic reaction and nasal polyposis may be modulated at least in part by GM-CSF from epithelial cells; and secondly epithelial cells from NP might have a more potent effect on inducing eosinophil infiltration of the respiratory mucosa than epithelial cells from NM. Finally, we may consider this as a reliable in vitro model to compare the role of epithelial cells from inflammatory (NP) and non-inflammatory (NM) tissue in respiratory inflammation.

Influence of allergen avoidance at high altitude on serum markers of eosinophil activation in children with allergic asthma

A cohort of 12 asthmatic children was followed over several months, during which they moved back and forth from an allergen-free to an allergen-rich environment at high and low altitude, respectively. The children were treated with non-steroidal anti-asthmatic drugs as clinically needed. Histamine PC20-FEV1 was unaltered during the study period, whereas serum levels of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) showed significant changes when the children were exposed to the offending allergens. The total IgE significantly increased during exposure. The serum levels of myeloperoxidase (MPO) as well as of chemotactic factors for both neutrophils and eosinophils were unaltered during allergen exposure. We conclude that the serum markers of eosinophil activity ECP and EPX are sensitive indices of allergen exposure in asthmatic atopic children.

Are hypodense eosinophils in children activated or immature?

In patients with allergic asthma and rhinitis high numbers of hypodense eosinophils (HE) have been demonstrated. In a previous study we reported that asthmatic and healthy children had more HE than their adult counterparts. We assumed that this might, in part, be due to the presence of immature eosinophils in children. To distinguish between immature and activated eosinophils, determination of eosinophil cationic protein (ECP) might be interesting as it is known that high serum levels of ECP are associated with increased activation of eosinophils. In this study we determined the levels of ECP in serum in asthmatic and healthy children and adults trying to distinguish activated from immature eosinophils. We found that ECP levels were not increased in children (healthy and asthmatic) compared to adults (healthy and asthmatic). This supports the hypothesis that increased numbers of HE in childhood are, at least in part, immature eosinophils. Nevertheless, we could confirm that inflammation was present in children because soluble interleukin-2-receptor (sIL-2R), a marker of lymphocyte activation, was higher in asthmatic children as compared to healthy children. IL-6, a marker of macrophage/monocyte activation, was not different in the different patient groups. We conclude that although signs of inflammation are present in childhood asthma, the increased numbers of HE in children are in part due to the presence of immature eosinophils.

High concentrations of eosinophil cationic protein and eosinophil protein X in eosinophilic pleural effusions

To analyze the association of the eosinophil granulocyte with pleural effusions, we measured the concentrations of two eosinophil proteins, eosinophil cationic protein (ECP) and eosinophil protein X (EPX), in pleural fluid and serum of 92 patients with pleural effusions of various causes. We observed significantly higher ECP and EPX concentrations in eosinophilic than in noneosinophilic pleural effusions (p < 0.001 and p < 0.05, respectively) and a positive correlation between the concentrations of both eosinophil proteins in pleural fluid and the total number of eosinophils in pleural fluid (ECP: r = 0.66, p < 0.0001; and EPX: r = 0.62, p < 0.0001). There was a positive correlation between the concentrations of ECP in pleural fluid and serum (r = 0.74, p < 0.0001) and between the concentrations of EPX in pleural fluid and serum (r = 0.41, p < 0.001). High ECP and EPX concentrations in pleural fluid indicated nonspecific etiology and not tuberculosis as the cause of the effusion. Our results suggest that eosinophils in pleural effusions release eosinophil proteins and probably actively participate in the local inflammatory reaction.

Early histological features of small intestinal injury induced by indomethacin

The early histological features of indomethacin-induced jejunal injury in the rat are described in tissues preserved by perfusion-fixation with 10% formol-saline. After an oral dose of indomethacin (15 mg/kg, known to cause severe multifocal ulceration of the rat jejunum), groups of rats were anaesthetized with subsequent perfusion-fixation of the gastrointestinal tract at 1, 2, 3, 6 and 48 h after dosing. Using routine light microscopic techniques, we have observed a sequence of four distinct stages, in time, of small intestinal injury. The earliest histological features were shortening of the villi, epithelial stratification, basal lamina degeneration, eosinophil degranulation and infiltration of the epithelium prior to infiltration of the mucosa by neutrophils. We consider that these earliest changes, seen at 1, 2 and 3 h, represent a distinct histological entity termed Type 1 change or villous 'tufting'. Type 2 change includes all of the features of Type 1 change plus the subsequent infiltration of the mucosa by neutrophils at 2, 3 and 6 h. Type 3 change includes necrosis of the upper-third of the villi and was mainly seen at 3 and 6 h. Type 4 change describes extreme injury to more than one-third of the mucosa with severe, acute inflammation and perforation of the bowel wall by 48 h. Although a small number of neutrophils had appeared to infiltrate the mucosa as early as 2 h after dosing, they were only significantly increased at 3, 6 and 48 h. Possible pathogenic mechanisms involved in shortening of villi as a result of smooth muscle contraction and the role of mucosal eosinophils in NSAID-induced jejunal injury in the rat are discussed.

Neuroimmunotherapy of advanced solid neoplasms with single evening subcutaneous injection of low-dose interleukin-2 and melatonin: preliminary results

On the basis of the demonstrated existence of immunoneuroendocrine interactions and on the previously observed synergistic action between the pineal hormone melatonin (MLT) and interleukin-2 (IL-2), we have designed a neuroimmunotherapeutic combination consisting of low-dose IL-2 and MLT in the treatment of advanced solid neoplasms. The study included 24 patients with advanced solid tumours (non-small cell lung cancer 9; colorectal cancer 7; gastric cancer 3; breast cancer 2; cancer of pancreas 1; hepatocarcinoma 1; unknown primary tumour 1), 21 of whom showed distant organ metastases. Not all patients responded to previous chemotherapies, or had tumours for which no standard therapy was available. Moreover, not all patients were able to tolerate IL-2 immunotherapy at the conventional doses. IL-2 was given subcutaneously at a dose of 3 x 10(6) U/day at 8:00 p.m. for 6 days/week for 4 weeks. MLT was given orally at a dose of 50 mg at 8:00 p.m. every day, starting 7 days before IL-2 injection. In non-progressed patients, a second cycle was given after a 21-day rest period. A partial response was seen in 3/24 patients (lung 2; stomach 1; duration: 11, 4, 4 months, respectively). Moreover, a minimal response (duration: 8+ months) was seen in 1 lung cancer patient. Stable disease was obtained in 14/24 patients (median duration: 6+ months), while the remaining 6 patients progressed. An improvement in performance status was seen in 7/24 patients. No important toxicity was observed. Mean eosinophil and lymphocyte levels significantly increased during the immunotherapy, and their rise was significantly higher in patients with response or stable disease than in those with progressive disease. These preliminary results show that neuroimmunotherapy with low-dose IL-2 and the pineal hormone MLT is a biologically active and well tolerated strategy, capable of determining an apparent control of tumour growth in patients with advanced solid neoplasms, for whom no standard effective therapy is available.

Induction of granule release by intracellular application of calcium and guanosine-5'-O-(3-thiotriphosphate) in human eosinophils

The roles of Ca and G proteins in granule release from human eosinophils were examined by use of a patch-clamp technique in single cells. The morphologic changes and the release of eosinophil peroxidase (EPO) from single cells were simultaneously observed. In addition, the expression of small molecular weight guanine nucleotide binding protein (small G protein) mRNA (smg p25A [rab 3] and smg p21 [rab 1]) was investigated. The intracellular application of Ca, 10 mumol/L, and guanosine-5'-O-(3-thiotriphosphate) (GTP-gamma-S), 100 mumol/L, induced fusion of EPO containing granules with the surface membrane, which was associated with a marked increase in membrane capacitance. Ca alone caused a rapid granule release at an early stage of cell dialysis, but most granules still remained in a cluster. GTP-gamma-S alone caused a gradual degranulation. Northern blot analysis revealed the definite expression of smg p21 mRNA with no appreciable expression of smg p25A. These results provide direct evidence of granule fusion by intracellular application of Ca and GTP-gamma-S. In addition, Ca dependent proteins and G proteins act cooperatively in granule release, and these proteins likely regulate the different processes of degranulation. Furthermore, a protein, encoded by smg p21, may be involved in the granule release process in human eosinophils.

Superoxide production by human eosinophils can be inhibited in an agonist-selective manner

This paper focuses on eosinophil activation and its selective inhibition. Superoxide anion (O2-) production by human eosinophils, an indicator of their activation, was induced by a variety of activators. Several compounds which are known to inhibit protein kinase C (staurosporine, K252a, sphingosine) inhibited O2- production induced by phorbol ester (PMA) but failed to inhibit O2- production induced by IgG coupled to Sepharose beads. Inhibition of O2- production by other agents (plasma-activated zymosan, fMLP, and leukotriene B4 (LTB4), was intermediate. By contrast, wortmannin, a compound which has been previously reported to inhibit O2- production in neutrophils via a protein kinase-independent pathway, potently inhibited O2- production in eosinophils which had been activated by IgG and by Platelet-Activating Factor but was virtually inactive against PMA-induced O2- production. Taken together, the results indicate that, as a minimum, there must be two pathways of induction of O2- production in eosinophils. Moreover, the intermediate levels of inhibition in cells which had been activated with serum-activated zymosan, FMLP, and LTB4 suggest that these agents may either be acting via both of these pathways or that yet other pathways may exist.