During Plasmodium falciparum infection leading to cerebral malaria, cytokine production and cytoadherence of parasitized erythrocytes (PRBCs) to postcapillary venules are involved. We demonstrate that PRBC adhesion induces apoptosis in human endothelial cells (HLECs). PRBC adhesion modulated HLEC gene expression in tumor necrosis factor-alpha superfamily genes (Fas, Fas L, and DR-6) and apoptosis-related genes (Bad, Bax, caspase-3,SARP 2, DFF45/ICAD, IFN-gamma receptor 2, Bcl-w, Bik, and iNOS). Apoptosis was confirmed by (1) morphological modifications by electron microscopy, (2) annexin V binding, (3) DNA degradation, by measuring intracytoplasmic nucleosomes, and (4) caspase activity. The apoptotic stimulus was physical contact between HLECs and PRBCs and not parasite-secreted molecules. In addition, it was found that cytoplasmic (caspase 8) and mitochondrial (caspase 9) pathways were involved in this process. These data not only describe the direct apoptotic effect of PRBC adhesion on endothelial cells but also provide new useful tools that allow an evaluation of potential pharmaceuticals.

The in vitro activities of 25 quinolones and fluoroquinolones against erythrocytic stages of Plasmodium falciparum and against liver stages of Plasmodium yoelii yoelii and P. falciparum were studied. All compounds were inhibitory for chloroquine-sensitive and chloroquine-resistant P. falciparum grown in red blood cells. This inhibitory effect increased with prolonged incubation and according to the logarithm of the drug concentration. Grepafloxacin, trovafloxacin, and ciprofloxacin were the most effective drugs, with 50% inhibitory concentrations of <10 g/ml against both strains. Only grepafloxacin, piromidic acid, and trovafloxacin had an inhibitory effect against hepatic stages of P. falciparum and P. yoelii yoelii; this effect combined reductions of the numbers and the sizes of schizonts in treated cultures. Thus, quinolones have a potential for treatment or prevention of malaria through their unique antiparasitic effect against erythrocytic and hepatic stages of Plasmodium.The spread of multidrug-resistant Plasmodium falciparum has highlighted the urgent need to develop new antimalarial drugs (14). Quinolones and fluoroquinolones have already been proposed for treatment of malaria, as these drugs were proven to have in vitro antimalarial activity against chloroquine-sensitive and chloroquine-resistant P. falciparum (5,8,13,20,23). However, all these studies were restricted to the erythrocytic stages of P. falciparum and so far there is no information concerning the potential effects of the drugs against the hepatic development of the parasite.In this study we assessed the in vitro inhibitory effects of 25 quinolones and fluoroquinolones against blood stages of P. falciparum and hepatic stages of Plasmodium yoelii yoelii and P. falciparum.The 25 quinolones studied were cinoxacin, enoxacin, flumequine, nalidixic acid, norfloxacin, oxolinic acid, pipemidic acid, piromidic acid, sparfloxacin, temafloxacin, trovafloxacin (Sigma Aldrich, Paris, France), ciprofloxacin, moxifloxacin (Bayer Pharma), marbofloxacin (Vetoquinol), irloxacin (Laboratoire Dr. Esteve), grepafloxacin (Glaxo-Wellcome), gatifloxacin (Grünental), levofloxacin, ofloxacin, pefloxacin (Aventis), rufloxacin (Mediolanum Farmaceutic), lomefloxacin (Monsanto Searle), clinafloxacin (Parke-Davis), fleroxacin (Roche), and rosafloxacin (Sanofi Synthelabo). From a stock solution at a concentration of 1 mg/ml, serial dilutions were prepared in culture medium for in vitro tests against blood and hepatic stages of Plasmodium.In vitro drug susceptibility assays of blood stages of P. falciparum. Cultures of the 3D7 chloroquine-sensitive clone and NF54-R chloroquine-resistant strain derived from the NF54 strain were maintained in continuous culture according to a modified version of the method of Trager and Jensen (19).The in vitro activities of the drugs were evaluated by using the method of Desjardins et al. (4) with modifications. In brief, 200 l of ring stage parasitized erythrocytes (parasitemia, 0.5%; hematocrit, 1.8%) was distributed in 96-well plates pre...