Heparin Interaction with the Primed Polymorphonuclear Leukocyte CD11b Induces Apoptosis and Prevents Cell Activation.

Meital Cohen-Mazor,Shifra Sela,Inbal Ziv,Erik B Kistler,Rafi Mazor,Batya Kristal,Judith Chezar

doi:10.1155/2015/751014

Abstract

Heparin is known to have anti-inflammatory effects, yet the mechanisms are not completely understood. In this study, we tested the hypothesis that heparin has a direct effect on activated polymorphonuclear leukocytes (PMNLs), changing their activation state, and can explain its anti-inflammatory effect. To test our hypothesis, we designed both in vitro and ex vivo studies to elucidate the mechanism by which heparin modulates PMNL functions and therefore the inflammatory response. We specifically tested the hypothesis that priming of PMNLs renders them more susceptible to heparin. Amplified levels of CD11b and increased rate of superoxide release manifested PMNL priming. Increase in cell priming resulted in a dose-dependent increase in heparin binding to PMNLs followed by augmented apoptosis. Blocking antibodies to CD11b inhibited heparin binding and abolished the apoptotic response. Moreover, heparin caused a significant dose-dependent decrease in the rate of superoxide release from PMNLs, which was blunted by blocking antibodies to CD11b. Altogether, this study shows that the interaction of heparin with the PMNL CD11b results in cell apoptosis and explains heparin's anti-inflammatory effects.

Highlights

In many inflammatory responses, polymorphonuclear leukocytes (PMNLs) are among the first cells to exit the blood stream and migrate to an inflammatory site, where they become fully activated
The rate of superoxide release following phorbol myristate acetate (PMA) stimulation was higher in PMNLs isolated from HD patients compared to platelet activating factor (PAF) untreated normal control (NC) cells (33.5 ± 4 versus 24.7 ± 5 nmoles/106 cells/10 min, resp., ∗P < 0.05, Figure 1(a)) and was similar to the rate achieved by stimulation with the highest concentration of PAF
The expression of CD11b was higher in HD PMNLs than in NC PMNLs (61 ± 25 versus 29 ± 11 mean fluorescence intensity (MFI), resp., ∗P < 0.05, Figure 1(b)) and comparable to the levels measured in NC cells stimulated with the highest concentration of PAF

Summary

Introduction

Polymorphonuclear leukocytes (PMNLs) are among the first cells to exit the blood stream and migrate to an inflammatory site, where they become fully activated. This activation is a two-stage process: PMNLs first encounter a stimulus that does not activate the cells directly but leaves them in a “primed” state. Upon encountering a second stimulus in the inflamed site, the transition into a fully activated state will occur [1, 2] This process involves the production of free radicals and release of granule enzymes into the surrounding milieu. Heparin decreases phorbol myristate acetate (PMA), N-formyl-methionyl-leucylphenylalanine (fMLP), and opsonized zymosan-induced superoxide production [7], a decrease which is even greater

Methods

Results

Conclusion