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Mediators of Inflammation
Volume 2012, Article ID 198382, 10 pages
http://dx.doi.org/10.1155/2012/198382
Research Article

Activation of Human Neutrophils by the Anti-Inflammatory Mediator Esenbeckia leiocarpa Leads to Atypical Apoptosis

1Laboratoire de Recherche en Inflammation et Physiologie des Granulocytes, INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevord des Prairies, Laval, QC, Canada H7V 1B7
2Department of Clinical Analysis, Center of Health Sciences, Federal University of Santa Catarina, Campus Universitário, Trindade, 88040-970 Florianópolis, SC, Brazil
3Department of Chemistry, Center of Physical and Mathematical Sciences, Federal University of Santa Catarina, Campus Universitário, Trindade, 88040-970 Florianópolis, SC, Brazil

Received 22 December 2011; Revised 20 February 2012; Accepted 23 February 2012

Academic Editor: Elaine Hatanaka

Copyright © 2012 Rafael de Liz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Despite the fact that Esenbeckia leiocarpa, a Brazilian plant, possesses potential anti-inflammatory properties, its effect in neutrophils, key players in inflammation, has never been investigated. In this study, a crude hydroalcoholic extract (CHE) was used to evaluate the potential toxic or agonistic effect of E. leiocarpa in human neutrophils. At a noncytotoxic concentration of 500 μg/mL, CHE increased actin polymerization and cell signaling events, especially p38 MAPK. Its modulatory activity on neutrophil cell apoptosis was investigated by cytology and by flow cytometry and, although CHE increased the apoptotic rate (by cytology) and increased annexin-V binding, it did not, unexpectedly, increase CD16 shedding. CHE increased the degradation of the cytoskeletal proteins gelsolin and paxillin but, surprisingly, not of vimentin. The proapoptotic activity of CHE was reversed by a pan-caspase inhibitor but not by a p38 inhibitor. We conclude that CHE is a novel human neutrophil agonist that induces apoptosis by a caspase-dependent and p38-independent mechanism in an atypical fashion based on its lack of effect on CD16 shedding and vimentin degradation. Since the resolution of inflammation occurs by elimination of apoptotic neutrophils, the ability of CHE to induce neutrophil apoptosis correlates well with its anti-inflammatory properties, as previously reported.