Tomokazu Kakazu

Effect of platelet-activating factor and platelet factor 4 on eosinophil adhesion.

The effect of platelet-activating factor (PAF) and platelet factor 4 (PF4) on the adhesion of isolated human eosinophils or eosinophilic cell lines (EoL-1, EoL-3) was examined. Both PAF and PF4 augmented eosinophil adhesion to plates coated with AB plasma or recombinant soluble intercellular adhesion molecule-1 (r-sICAM-1). These findings suggest that PAF and PF4 not only modulate chemotactic activity of eosinophils but also intensify the function of eosinophil adhesion. Since PAF and PF4 induce the expression of adhesion molecules (LFA-1 alpha, LFA-1 beta, CR3) on eosinophils, we could conclude that PAF or PF4 are closely related to eosinophil accumulation not only as chemotactic agents but also as augmentative agents for eosinophil adhesion through involvement in functional eosinophil adherence as well as surface expression of adhesion molecules on eosinophils.

Degranulation of eosinophils mediated by intercellular adhesion molecule-1 and its ligands is involved in adhesion molecule expression on endothelial cells–selective induction of VCAM-1

BACKGROUND Adhesion molecules and eosinophils may play an important role in the pathogenesis of allergic inflammatory reactions. OBJECTIVE We attempted to clarify eosinophil activation, such as degranulation, by signaling through adhesion molecule and to determine whether degranulation is involved in adhesion molecule expression on endothelial cells. METHODS Eosinophils were cultured with or without recombinant soluble intercellular adhesion molecule-1 (ICAM-1), and the levels of eosinophil cationic protein and eosinophil-derived neurotoxin were determined. The influence of these eosinophil granule proteins or supernatant from eosinophil cultured with ICAM-1 on the expression of ICAM-1 or vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells was also examined by flow-cytometric analysis. RESULTS Supernatant levels of eosinophil granule protein were significantly increased by culture for 4 hourss or 16 hours with recombinant soluble ICAM-1, suggesting degranulation by adherence to ICAM-1. Both granule proteins and the supernatants of eosinophils cultured with recombinant soluble ICAM-1 induced expression of ICAM-1 and VCAM-1 on endothelial cells, with the latter showing a more prominant increase. CONCLUSION Degranulation mediated through adherence to endothelial cells by ICAM-1 and its ligands may be involved in the expression of adhesion molecules, such as ICAM-1 or VCAM-1, on these cells. Our finding of the selective induction of VCAM-1 expression suggests that eosinophil adherence to endothelial cells, even if it is because of ICAM-1, may be involved in selective eosinophil recruitment and accumulation at sites of allergic inflammation.

Eosinophil Cationic Protein Induces Insulin-Like Growth Factor I Receptor Expression on Bronchial Epithelial Cells

Although the biologic activity of eosinophil-specific granule proteins, e.g. eosinophil cationic protein (ECP) has been attributed to cytotoxic properties, it has also been shown to be attributable to non-cytotoxic activation of various inflammatory cells. In addition, airway epithelial cells have been reported to express insulin-like growth factor I (IGF-I) receptor and proliferate in response to IGF-I. The present study examined the regulation of expression of IGF-I receptor on bronchial epithelial cells by eosinophil granule proteins was examined. ECP significantly induced IGF-I receptor expression on bronchial epithelial cells compared with unstimulated cells. These findings suggest that eosinophils participate in the repair process of injured bronchial epithelial cells in the inflamed focus through augmentation of IGF-I receptor expression by suboptimal degranulation of eosinophil granule proteins, e.g. ECP.

Induction of Expression of Adhesion Molecules on an Eosinophilic Cell Line (EoL-1) by the Supernatant of Lymphocytes Stimulated with Specific Allergen from Asthmatic Patients

Recently, adhesion molecules have been considered to play an important role in inflammatory processes in bronchial asthma. To extend our understanding of the high-intensity expression of adhesion molecules (CR3, LFA-1 alpha, LFA-1 beta, ICAM-1) on hypodense eosinophils, which was observed in our previous study, we examined whether the supernatant of lymphocytes from mite-allergic asthmatic patients is involved in adhesion molecule expression using an eosinophilic cell line (EoL-1). These characteristics of adhesion molecule expression were induced by the supernatant of lymphocytes obtained from mite-allergic asthmatic patients cultured with specific allergen as well as a combination of recombinant cytokines (IL-3, GM-CSF, IL-5). Thus, we could conclude that some lymphokines produced by specific allergen in asthma might be involved in the high-intensity expression of adhesion molecules on hypodense eosinophils in asthma or allergic disorders.

RANTES Augments Eosinophil Lucigenin-Dependent Chemiluminescence

Background: RANTES (regulated on activation, normal T expressed and secreted) has been shown to possess chemotactic activity for eosinophils. Eosinophils have been considered to play a key role in the allergic inflammation through the release of inflammatory molecules such as radical oxygen products. Thus, in this study, we examined the effect of RANTES on radical oxygen products from eosinophils. Methods: Eosinophils were isolated from heparinized venous blood of patients with bronchial asthma by the modified CD16-negative depletion method. Radical oxygen products were examined in terms of lucigenin-dependent chemiluminescence. To a mixture of 50 µl of eosinophils (2×106/ml) and 50 µl of lucigenin (5×10–4M), 50 µl of calcium ionophore A23187 (final concentration 10–5M) was added, and radical oxygen products were determined for 600 s. Results: RANTES treatment resulted in the enhancement of peak value (0.64±0.23 RLU) and integrated value (119.08±20.52 RLU) as compared to untreated cells (0.15±0.03 RLU, 29.48±8.92 RLU, respectively). Conclusion: We could conclude that RANTES might play an important role in the pathogenesis of allergic inflammation through involvement in selective eosinophil infiltration and eosinophil activation by augmentation of eosinophil oxidative metabolism.

Expression of CD23, CD32, Mac-1 and Other Adhesion Molecules in Eosinophils in Strongyloidiasis and HTLV-I-Positive Patients

The relationship between human T-lymphotropic virus I (HTLV-I) infection and strongyloidiasis has recently become an important problem. This study compared the expression of CD23, CD32, Mac-1 and other adhesion molecules in eosinophils of patients with strongyloidiasis positive for anti-(HTLV-I) antibodies and in those negative for the antibodies. The expression of CD23, Mac-1 and intercellular adhesion molecule-1 (ICAM-1) on eosinophils of patients with strongyloidiasis was augmented in comparison with normal subjects and HTLV-I carriers. There were no significant differences, however, in the expression of CD23, CD32, Mac-1 and adhesion molecules (ICAM-1, leukocyte function-associated antigen-1 alpha (LFA-1 alpha), LFA-1 beta, very late antigen-4) on eosinophils of patients with strongyloidiasis positive for anti-HTLV-I antibodies in comparison with those negative for these antibodies.