PHAGOCYTOSIS INDUCED BY MT-II AND MT-III, TWO PLA2 ISOLATED FROM Bothrops asper SNAKE VENOM IN MACROPHAGES. ROLE OF PROTEIN KINASES.

Zuliani, J.P.¹; Yamanouye, N.¹; Gutierrez, J.M.²; Lomonte, B.²; Teixeira, C.F.P¹.

1 Lab. Farmacologia, Instituto Butantan – São Paulo, Brazil. 2 Instituto Clodomiro Picado – San José, Costa Rica.

Phagocytosis, a defense mechanism used by macrophages to clear invading pathogens, is characterized by a coordinated process involving lipids, signaling proteins, and the cytoskeleton. MT-III, an Asp-49 PLA2 catalytically active enzyme and MT-II, a Lys-49 PLA2 catalytically inactive variant, isolated from Bothrops asper snake venom display inflammatory events such as phagocytosis. The subject of this study is to evaluate the signal transduction pathway mediating MT-III and MT-II-induced phagocytosis via mannose receptor focusing PKC, PI 3-kinase and the role of C-terminal sequence 115-129 of both PLA2  in this event. Macrophages were obtained from Swiss mice peritoneal cavity 96 hours after intraperitoneal injection of thioglycollate (3%). Phagocytosis via mannose receptor was studied in vitro with non-opsonized zymosan in the presence or absence of specific inhibitors. Results showed that both toxins significantly increased phagocytosis from 5 to 60 minutes. The homologous peptide 115-129 from MT-II and MT-III did not reproduce this effect. Staurosporine and H7, PKC inhibitors and Wortmannin, a PI 3-kinase inhibitor, significantly reduced the effects of both toxins on macrophages (p<0.05). These findings indicate the ability of Lys-49 and Asp-49 PLA2 to induce phagocytosis via mannose receptors and suggest that C-terminal region of both toxins is not relevant for this effect. Moreover, PKC and PI 3-kinase have a role in the signaling events mediating MT-II and MT-III-induced phagocytosis via mannose receptors in macrophages.

Supported by FAPESP (02/01009-7).

Correspondence to: jzuliani@butantan.gov.br