Alterations of lecithin-cholesterol acyltransferase activity during Plasmodium chabaudi rodent malaria

Potential role of the low-density lipoprotein receptor family as mediators of cellular drug uptake

We highlight the importance of the low-density lipoprotein (LDL) receptor family and its pharmaceutical implications in the field of drug delivery. The members of the LDL receptor family are a group of cell surface receptors that transport a number of macromolecules into cells through a process called receptor-mediated endocytosis. This process involves the receptor recognizing a ligand from the extracellular membrane (ECM), internalizing it through clathrin-coated pits and degrading it upon fusion with lysosomes. There are nine members of the receptor family, which include the LDL receptor, low-density lipoprotein-related protein (LRP), megalin, very low-density lipoprotein (VLDL) receptor, apoER2 and sorLA/LRP11, LRP1b, MEGF7, LRP5/6; the former six having been identified in humans. Each member is expressed in a number of different tissues and has a wide range of different ligands, not specific to the recognition of the LDL particle. Thus, rather than the original hypothesis that the receptor is only a mediator of cholesterol uptake, it may also be involved in a number of other physiological functions, including the progression of certain disease states and, potentially, cellular drug uptake. A number of studies have suggested that the LDL receptors are involved in endocytosis of drugs and drug formulations including aminoglycosides, anionic liposomes and cyclosporine A (CsA). This article reviews the importance of lipoproteins as a drug delivery system and how LDL receptors are relevant to the design and targeting of specific drugs.

Role of plasma lipoproteins in modifying the biological activity of hydrophobic drugs

The plasma lipoprotein distribution of potential drug candidates is not commonly studied. For some hydrophobic drug candidates, attainment of similar plasma free drug levels has not been associated with uniform production of pharmacological activity in different animal species. It is well-known that plasma lipoprotein lipid profiles vary considerably between different animal species. In addition, human disease states can significantly influence plasma lipoprotein profiles, resulting in altered therapeutic outcomes. Current research has shown that lipoprotein binding of drug compounds can significantly influence not only the pharmacological and pharmacokinetic properties of the drug, but the relative toxicity as well. Elucidation of drug distribution among plasma lipoproteins is expected to yield valuable insight into factors governing the pharmacological activity and potential toxicity of the drug. This paper will present an historical perspective and summarize the latest research in the area of lipoprotein-drug interactions.

The course of Plasmodium berghei, P. chabaudi and P. yoelii infections in beta-thalassaemic mice

In order to study the effects of acclimatization of Plasmodium in beta-thalassaemic mice, we used a mouse model of beta-thalassaemia (DBA/2J/beta-thal/beta-thal), similar to that observed in humans. We acclimatized 3 rodent malarias (P. berghei, P. chabaudi and P. yoelii) in DBA/2J and DBA/2J/beta-thal mice lines, by 4 intraperitoneal serial transfers. All 3 rodent malarias developed in red blood cells of beta-thalassaemic mice without losing their virulence. There was no delay in infection and peaks of parasitaemia were similar in beta-thalassaemic and normal mice. The mortality occurred earlier in beta-thalassaemic mice than in control mice for P. berghei and P. chabaudi. The difference was more pronounced for P. yoelii NS where normal mice did not die. These results could be explained by a failure of erythropoiesis in beta-thalassaemic mice, which are unable to compensate for the destruction of red blood cells by the parasites, and the mice died of anaemia. Ultrastructural examination of the rodent malaria parasites in beta-thalassaemic RBC showed a normal development even in the presence of Heinz bodies. In conclusion, no effective protection against malaria was provided by the beta-thalassaemia in this mouse model.