Eosinophil adhesion to cholinergic nerves via ICAM-1 and VCAM-1 and associated eosinophil degranulation

Abstract

In vivo, eosinophils localize to airway cholinergic nerves in antigen-challenged animals, and inhibition of this localization prevents antigen-induced hyperreactivity. In this study, the mechanism of eosinophil localization to nerves was investigated by examining adhesion molecule expression by cholinergic nerves. Immunohistochemical and functional studies demonstrated that primary cultures of parasympathetic nerves express vascular cell adhesion molecule-1 (VCAM-1) and after cytokine pretreatment with tumor necrosis factor-α and interferon-γ intercellular adhesion molecule-1 (ICAM-1). Eosinophils adhere to these parasympathetic neurones after cytokine pretreatment via a CD11/18-dependent pathway. Immunohistochemistry and Western blotting showed that a human cholinergic nerve cell line (IMR-32) expressed VCAM-1 and ICAM-1. Inhibitory experiments using monoclonal blocking antibodies to ICAM-1, VCAM-1, or CD11/18 and with the very late antigen-4 peptide inhibitor ZD-7349 showed that eosinophils adhered to IMR-32 cells via these adhesion molecules. The protein kinase C signaling pathway is involved in this process as a specific inhibitor-attenuated adhesion. Eosinophil adhesion to IMR-32 cells was associated with the release of eosinophil peroxidase and leukotriene C4. Thus eosinophils adhere to cholinergic nerves via specific adhesion molecules, and this leads to eosinophil activation and degranulation; this may be part of the mechanism of eosinophil-induced vagal hyperreactivity.

Neuronal eotaxin and the effects of ccr3 antagonist on airway hyperreactivity and M2 receptor dysfunction

“…Eosinophils were incubated with cultured guinea pig parasympathetic neurons for 30 minutes, after which nonadherent eosinophils were washed off. As we have previously shown (13), treating cultured parasympathetic neurons with TNF-α and IFN-γ increased eosinophil adherence. This is the result of increased ICAM-1 expression by the nerves (13).…”

“…As we have previously shown (13), treating cultured parasympathetic neurons with TNF-α and IFN-γ increased eosinophil adherence. This is the result of increased ICAM-1 expression by the nerves (13). Treating these cells with the CCR3 antagonist prevented the increased adherence of eosinophils to these neurons ( Figure 13).…”

Eosinophil Adhesion to Cholinergic IMR-32 Cells Protects against Induced Neuronal Apoptosis

“…In addition, to study whether the protection was due to contact between cells or due to factors released from the cells, we prepared eosinophil membranes by removal of nuclear and cytoplasmic material. We have previously shown that these preparations express adhesion molecules and adhere to cholinergic IMR-32 nerve cells in the same manner as viable whole eosinophils (9). These studies showed that eosinophil membranes in coculture with IMR-32 cells prevent neuronal apoptosis, as observed by expression of phosphatidylserine on the outer nerve membrane, caspase-3 activation, and DNA laddering.…”

“…Alternatively, eosinophils were inactivated with 4% paraformaldehyde for 20 min, centrifuged at 400 ϫ g for 5 min, and suspended in culture medium, and the process was repeated twice more. Flow cytometry and functional studies showed that these preparations retain an ability to adhere via CD11/18 and VLA-4 to nerve cells (9,10,14).…”

“…In in vitro studies, we have shown that eosinophils adhere to cholinergic nerves via specific adhesion molecules (9). Eosinophil adhesion leads to the activation of a number of intracellular pathways within the nerve cells, including the MAPKs ERK1/2 and p38, and in turn these lead to activation of NF-B and AP-1, respectively (10).…”