(iv) Synthetic peptides representing region I from the P.falciparum CS protein and region II-plus from the P.falciparum, P.berghei or P.vivax CS protein inhibit in vitro translation. We propose that Plasmodium manipulates hepatocyte protein synthesis to meet the requirements of a rapidly developing schizont. Since macrophages appear to be particularly sensitive to the presence of CS protein in the cytosol, inhibition of translation may represent a novel immune evasion mechanism of Plasmodium. Keywords: circumsporozoite protein/immune evasion/ membrane translocation/Plasmodium/protein synthesis IntroductionAfter the discovery that circumsporozoite (CS) protein is the most abundant protein on the surface of malaria sporozoites in the early 1980s (reviewed in Nussenzweig and Nussenzweig, 1985), the function of CS protein remained unknown for many years. Recent evidence suggests that the CS protein is a multifunctional molecule that plays a crucial role at various points of the malaria life cycle. CS protein is translocated continuously from the anterior to the posterior cell pole and has, therefore, been implicated in sporozoite gliding motility (Stewart and Vanderberg, 1991). The finding that malaria sporozoites invade the liver of the vertebrate host within minutes after 3816 © Oxford University Press transmission by an infected mosquito (Shin et al., 1982) suggested a receptor-mediated clearance mechanism. We and others have shown that the CS protein binds to highly sulfated, heparin-like oligosaccharides in heparan sulfate on the basolateral membrane of hepatocytes in the space of Disse (Cerami et al., 1992;Pancake et al., 1992;Frevert et al., 1993;Ying et al., 1997), and this interaction is held responsible for the rapid and selective targeting of the sporozoites to the liver sinusoid Sinnis et al., 1994Sinnis et al., , 1996. In vitro, the CS protein binds with high affinity to the low density lipoprotein receptorrelated protein (LRP), and the dual interaction with heparan sulfate and LRP plays a dominant role in sporozoite invasion (Shakibaei and Frevert, 1996). Most recently, CS protein knock-out studies have demonstrated the crucial involvement of the CS protein in the formation of sporozoites in the mosquito midgut (Ménard et al., 1997), and the presence of receptors on salivary glands has suggested a role for the CS protein in sporozoite adhesion to this organ of the mosquito (Sidjanski et al., 1997).We present data here which show that the CS protein may also have a function within cells of the vertebrate host. Upon cell contact, Plasmodium berghei and P.yoelii sporozoites actively translocate CS protein across the cell membrane into the cytoplasm of mammalian cells in vitro (Hügel et al., 1996). This translocation occurs in the absence of parasite invasion by an as yet unknown mechanism. It requires neither the metabolic nor the endocytic machinery of the mammalian cell. The CS protein spreads throughout the entire cytosol of the affected cell and binds to cytosolic and endoplasmic reticulumassociated r...

Human butyrylcholinesterase (HuBChE) has previously been shown to protect mice, rats, and monkeys against multiple lethal toxic doses of organophosphorus (OP) anticholinesterases that were challenged by i.v. bolus injections. This study examines the concept of using a cholinesterase scavenger as a prophylactic measure against inhalation toxicity, which is the more realistic simulation of exposure to volatile OPs. HuBChE-treated awake guinea pigs were exposed to controlled concentration of soman vapors ranging from 417 to 430 micrograms/liter, for 45 to 70 s. The correlation between the inhibition of circulating HuBChE and the dose of soman administered by sequential i.v. injections and by respiratory exposure indicated that the fraction of the inhaled dose of soman that reached the blood was 0.29. HuBChE to soman molar ratio of 0.11 was sufficient to prevent the manifestation of toxic signs in guinea pigs following exposure to 2.17x the inhaled LD50 dose of soman (ILD50, 101 micrograms/kg). A slight increase in HuBChE:soman ratio (0.15) produced sign-free animals after two sequential respiratory exposures with a cumulative dose of 4.5x ILD50. Protection was exceptionally high and far superior to the currently used traditional approach that consisted of pretreatment with pyridostigmine and postexposure combined administration of atropine, benactyzine, and an oxime reactivator. Quantitative analysis of the results suggests that in vivo sequestration of soman, and presumably other OPs, by exogenously administered HuBChE, is independent of the species used or the route of challenge entry. This assuring conclusion significantly expands the database of the bioscavenger strategy that now offers a dependable extrapolation from animals to human.

The present study shows the advantages of liposome-based nano-drugs as a novel strategy of delivering active pharmaceutical ingredients for treatment of neurodegenerative diseases that involve neuroinflammation. We used the most common animal model for multiple sclerosis (MS), mice experimental autoimmune encephalomyelitis (EAE). The main challenges to overcome are the drugs’ unfavorable pharmacokinetics and biodistribution, which result in inadequate therapeutic efficacy and in drug toxicity (due to high and repeated dosage). We designed two different liposomal nano-drugs, i.e., nano sterically stabilized liposomes (NSSL), remote loaded with: (a) a “water-soluble” amphipathic weak acid glucocorticosteroid prodrug, methylprednisolone hemisuccinate (MPS) or (b) the amphipathic weak base nitroxide, Tempamine (TMN). For the NSSL-MPS we also compared the effect of passive targeting alone and of active targeting based on short peptide fragments of ApoE or of β-amyloid. Our results clearly show that for NSSL-MPS, active targeting is not superior to passive targeting. For the NSSL-MPS and the NSSL-TMN it was demonstrated that these nano-drugs ameliorate the clinical signs and the pathology of EAE. We have further investigated the MPS nano-drug’s therapeutic efficacy and its mechanism of action in both the acute and the adoptive transfer EAE models, as well as optimizing the perfomance of the TMN nano-drug. The highly efficacious anti-inflammatory therapeutic feature of these two nano-drugs meets the criteria of disease-modifying drugs and supports further development and evaluation of these nano-drugs as potential therapeutic agents for diseases with an inflammatory component.

No abstract

No abstract