Microcystins -LA, -YR, and -LR action on neutrophil migration.

Paula Kujbida, Elaine Hatanaka, Marco Aurélio Ramirez Vinolo, Kaline Waismam, Danielle Maia de Holanda Cavalcanti, Rui Curi, Sandra Helena Poliselli Farsky, Ernani Pinto

Index: Biochem. Biophys. Res. Commun. 382(1) , 9-14, (2009)

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Abstract

Microcystins (MCs) produced by some freshwater cyanobacterial species possess potent liver toxicity as evidenced by acute neutrophil infiltration. Here, we investigate the ability of three structurally distinct toxins (MC-LA, MC-LR, and MC-YR) to evoke neutrophil recruitment per se and their effects on migration pathways. Intravital microscopic studies showed that topical application of only MC-LR enhanced the numbers of rolling and adhered leukocytes in the endothelium of postcapillary mesenteric venules. The latter effects may be dependent upon induction of the synthesis and expression of L-selectin and beta2-integrin in neutrophils, as assessed by flow cytometry and RT-PCR, respectively. Conversely, the three toxins promoted direct locomotion of neutrophils and enhanced their migration in response to fMLP, as measured by Boyden chamber assays, and increased intracellular calcium, a messenger in the chemotaxic process. In conclusion, our results show that MCs act on specific pathways of neutrophil recruitment, indicating their potential effect on neutrophils activation.