405 Original Paper Cell Physiol Biochem 2008;22:405-412 Accepted: October 08, 2008 Cellular Physiology Cellular Physiology Cellular Physiology Cellular Physiology Cellular Physiology and Biochemistr and Biochemistr and Biochemistr and Biochemistr and Biochemistry Copyright © 2008 S. Karger AG, Basel Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 2008 S. Karger AG, Basel 1015-8987/08/0226-0405$24.50/0 Accessible online at: www.karger.com/cpb Influence of Amitriptyline on Eryptosis, Parasitemia and Survival of Plasmodium Berghei- Infected Mice Verena Brand 1* , Saisudha Koka 1* , Camelia Lang 1 , Verena Jendrossek 3 , Stephan M. Huber 1,2 , Erich Gulbins 4 and Florian Lang 1 1 Department of Physiology, and 2 Radiation Oncology, University of Tübingen, 3 Department of Molecular Cell Biology, University of Essen, 4 Department of Molecular Biology, University of Essen, *equally contributed to the study and thus share first authorship Prof. Dr. Florian Lang Physiologisches Institut der Universität Tübingen Gmelinstr. 5, 72076 Tübingen (Germany) Tel. +49 7071 29 72194, Fax +49 7071 29 5618 E-Mail florian.lang@uni-tuebingen.de Key Words Malaria  Cell volume  Phosphatidylserine  Sphingomyelinase  Ceramide Abstract Plasmodia express a sphingomyelinase, which is ap- parently required for their development. On the other hand, the sphingomyelinase product ceramide has previously been shown to delay parasite develop- ment. Moreover, ceramide triggers suicidal erythro- cyte death or eryptosis, characterized by exposure of phosphatidylserine at the erythrocyte surface and cell shrinkage. Accelerated eryptosis of infected erythrocytes is considered to clear infected erythro- cytes from circulating blood and, thus, to favourably influence the clinical course of malaria. The present experiments explored whether the sphingomyelinase inhibitor amitriptyline or genetic knockout of host acid sphingomyelinase influence in vitro parasite growth, eryptosis of Plasmodium falciparum-infected human erythrocytes, in vivo parasitemia and survival of P. berghei-infected mice. Phosphatidylserine exposure was determined by annexin V-binding and cell vol- ume by forward scatter in FACS analysis. In vitro in- fection of human erythrocytes increased annexin- binding, an effect blunted in the presence of amitriptyline (≥ 50 µM). Amitriptyline did not signifi- cantly alter intraerythrocytic parasite development but significantly ( ≥ 1 µM) delayed the increase in parasitemia in vitro. Most importantly, amitriptyline treatment (1 mM in drinking water) resulted in a sig- nificant delay of parasitemia and death of infected mice. However, upon infection, ceramide formation was stimulated in both, acid sphingomyelinase knock- out mice (Smpd1 -/- ) and their wild type littermates (Smpd1 +/+ ). Parasitemia following P. berghei infection was significantly lower in Smpd1 -/- than in Smpd1 +/+ mice but did not significantly extend the life span of infected animals. In conclusion, mammalian and para- site sphingomyelinase contribute to ceramide forma- tion during malaria, whereby the parasite sphingo- myelinase ultimately determines the course of the infection. Amitriptyline presumably blocks both sphingomyelinases and, thus, its use might be a novel strategy to treat malaria. Introduction The malaria pathogen Plasmodium expresses a sphingomyelinase, which appears to be important for