Effects of liposome-encapsulated drugs on macrophages: comparative activity of the diamidine 4',6-diamidino-2-phenylindole and the phenanthridinium salts ethidium bromide and propidium iodide

Synthesis and characterization of chitosan–zinc composite electrodeposits with enhanced antibacterial properties

Chitosan–zinc composite electrodeposits with enhanced broad-spectrum bactericidal property were successfully synthesized based on the chelation action for marine application.

Effects of Kupffer Cell Depletion on Acute Alpha-Naphthylisothiocyanate-induced Liver Toxicity in Male Mice

Depletion of Kupffer cells, known to modulate chemical-induced hepatocellular injury, has not been studied with regard to biliary epithelial injury. Here, the authors investigated the effect of Kupffer cell depletion by clodronate on the toxicity of alpha-naphthylisothiocyanate (ANIT), known to injure biliary epithelium as well as hepatocytes. Up to 99% depletion of Kupffer cells occurred in ANIT and liposome-encapsulated clodronate-treated mice. The effect of Kupffer cell depletion was most evident one day following ANIT treatment. Histologically, there was a modest increase in neutrophil infiltration of the bile ducts, hepatocytic necrosis, and microvesicular vacuolization in the ANIT and clodronate-treated mice, but differences between other groups did not persist. Clinical pathology analytes related to the biliary or hepatocellular injury were significantly elevated in ANIT and clodronate-treated mice compared to mice given clodronate only. This was also true for mice given ANIT and empty liposomes in the case of the biliary analytes. However, group means were typically higher for the ANIT and clodronate-treated group than others on the first 2 days following ANIT injection. These findings suggest that Kupffer cell reduction increases hepatobiliary damage due to ANIT treatment.

Distinct macrophage phenotypes contribute to kidney injury and repair

The ischemically injured kidney undergoes tubular cell necrosis and apoptosis, accompanied by an interstitial inflammatory cell infiltrate. In this study, we show that iNos-positive proinflammatory (M1) macrophages are recruited into the kidney in the first 48 hours after ischemia/reperfusion injury, whereas arginase 1- and mannose receptor-positive, noninflammatory (M2) macrophages predominate at later time points. Furthermore, depletion of macrophages before ischemia/reperfusion diminishes kidney injury, whereas depletion at 3 to 5 days after injury slows tubular cell proliferation and repair. Infusion of Ifnγ-stimulated, bone marrow-derived macrophages into macrophage-depleted mice at the time of kidney reperfusion restored injury to the level seen without macrophage depletion, suggesting that proinflammatory macrophages worsen kidney damage. In contrast, the appearance of macrophages with the M2 phenotype correlated with the proliferative phase of kidney repair. In vitro studies showed that IFNγ-stimulated, proinflammatory macrophages begin to express markers of M2 macrophages when cocultured with renal tubular cells. Moreover, IL-4-stimulated macrophages with an M2 phenotype, but not IFNγ-stimulated proinflammatory macrophages, promoted renal tubular cell proliferation. Finally, tracking fluorescently labeled, IFNγ-stimulated macrophages that were injected after injury showed that inflammatory macrophages can switch to an M2 phenotype in the kidney at the onset of kidney repair. Taken together, these studies show that macrophages undergo a switch from a proinflammatory to a trophic phenotype that supports the transition from tubule injury to tubule repair.

Naposomes: a new class of peptide-derivatized, target-selective multimodal nanoparticles for imaging and therapeutic applications

Modified supramolecular aggregates for selective delivery of contrast agents and/or drugs are examined with a focus on a new class of peptide-derivatized nanoparticles: naposomes. These nanoparticles are based on the co-aggregation of two different amphiphilic monomers that give aggregates of different shapes and sizes (micelles, vesicles and liposomes) with diameters ranging between 10 and 300 nm. Structural properties and in vitro and in vivo behaviors are discussed. For the high relaxitivity values (12–19 mM-1s-1) and to detect for the presence of a surface-exposed peptide, the new peptide-derived supramolecular aggregates are very promising candidates as target-selective MRI contrast agents. The efficiency of surface-exposed peptides in homing these nanovectors to a specific target introduces promising new opportunities for the development of diagnostic and therapeutic agents with high specificity toward the biological target and reduced toxic side effects on nontarget organs.

Fine-tuning of POPC liposomal leakage by the use of beta-cyclodextrin and several hydrophobic guests

The effect of entrapped beta-cyclodextrin (beta-CD) on the stability of multilamellar vesicles (MLVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), prepared by the dehydration-rehydration method, was studied by monitoring the release of 5(6)-carboxyfluorescein encapsulated into the liposomes. Different hydrophobic guests, such as Fullerene C(60), have been incorporated into the POPC bilayer in order to modify the membrane composition. The kinetic results as well as ESI-MS measurements evidenced that the destabilizing activity of beta-CD is due to the formation of beta-CD inclusion complexes and the consequent removal of selected bilayer constituents from the liposomal membrane. Hence, when beta-CD was added to the liposomes in the form of a strong, water-soluble 2:1 beta-CD/C(60) inclusion complex, such a destabilizing effect was not observed. However, the same beta-CD/C(60) inclusion complex does not form as a result of C(60) extraction from the bilayer. This may be attributed either to the overwhelming concentration of POPC with respect to C(60) and/or to the fact that C(60) is largely aggregated in the bilayer. Turbidimetric and fluorimetric determinations of lamellarity and entrapped volume of the studied MLVs provided further evidence of the alteration of the liposomal bilayer as a consequence of the addition of beta-CD and/or the presence of the studied guests.

Liposome-based drug delivery to alveolar macrophages

The recent development of liposomal formulations compatible with aerosol delivery has expanded the potential to utilise chemotherapeutic agents directly targeted to the lungs more effectively. These are agents that would otherwise not be used because of their low solubility or toxicity. Various properties of liposomal carriers, including size, surface charge, composition and the presence of ligands, alter their efficacy and specificity towards alveolar macrophages to a great extent. This editorial summarises the advances in liposome-based drug delivery to alveolar macrophages.