Pluronic F127-modified liposome-containing tacrolimus-cyclodextrin inclusion complexes:improved solubility, cellular uptake and intestinal penetration

Objective The aim of this study was to investigate Pluronic F127-modified liposome-containing cyclodextrin (CD) inclusion complex (FLIC) for improving the solubility, cellular uptake and intestinal penetration of tacrolimus (FK 506) in the gastrointestinal (GI) tract. Methods Molecular modelling was performed to screen the optimal CD for the solubilization of FK 506. FLIC was prepared by thin-lipid film hydration with the inclusion complex solutions followed by membrane extrusion. Dilution tests were conducted in simulated gastric fluids and phosphate-buffered solution of sodium taurocholate to investigate the solubility improvement of FK506. The cellular uptake of nanocarriers was studied in Caco-2 cells, and intestinal mucous membrane penetration in the GI tract was evaluated in Sprague-Dawley rats. Key findings The results showed that β-CD had the strongest binding energy with the guest molecule among the CDs. The prepared FLIC has an average diameter of 180.8 ± 8.1 nm with a spherical shape. The solubility and cellular uptake of FK 506 was greatly improved by the incorporation of CD complexes in the Pluronic F127-modified liposomes. Intestinal mucous membrane penetration was also significantly improved by the preparation of FLIC. Conclusion With improved drug solubility and intestinal mucous membrane penetration, FLIC shows a promising oral delivery system for FK 506. © 2013 Royal Pharmaceutical Society.

Healthy ageing and depletion of intracellular glutathione influences T cell membrane thioredoxin-1 levels and cytokine secretion

Background: During ageing an altered redox balance has been observed in both intracellular and extracellular compartments, primarily due to glutathione depletion and metabolic stress. Maintaining redox homeostasis is important for controlling proliferation and apoptosis in response to specific stimuli for a variety of cells. For T cells, the ability to generate specific response to antigen is dependent on the oxidation state of cell surface and cytoplasmic protein-thiols. Intracellular thiols are maintained in their reduced state by a network of redox regulating peptides, proteins and enzymes such as glutathione, thioredoxins and thioredoxin reductase. Here we have investigated whether any relationship exists between age and secreted or cell surface thioredoxin-1, intracellular glutathione concentration and T cell surface thioredoxin 1 (Trx-1) and how this is related to interleukin (IL)-2 production.Results: Healthy older adults have reduced lymphocyte surface expression and lower circulating plasma Trx-1 concentrations. Using buthionine sulfoximine to deplete intracellular glutathione in Jurkat T cells we show that cell surface Trx-1 is lowered, secretion of Trx-1 is decreased and the response to the lectin phytohaemagglutinin measured as IL-2 production is also affected. These effects are recapitulated by another glutathione depleting agent, diethylmaleate.Conclusion: Together these data suggest that a relationship exists between the intracellular redox compartment and Trx-1 proteins. Loss of lymphocyte surface Trx-1 may be a useful biomarker of healthy ageing. © 2013 Carilho Torrao et al.; licensee Chemistry Central Ltd.

Disparate effects of non-steroidal anti-inflammatory drugs on apoptosis in guinea-pig gastric mucous cells: inhibition of basal apoptosis by diclofenac

Non-steroidal anti-inflammatory drugs (NSAIDs) induce apoptosis in gastrointestinal cancer cell lines. Similar actions on normal gastric epithelial cells could contribute to NSAID gastropathy. The present work therefore compared the actions of diclofenac, ibuprofen, indomethacin, and the cyclo-oxygenase-2 selective inhibitor, NS-398, on a primary culture of guinea-pig gastric mucous epithelial cells. Cell number was assessed by staining with crystal violet. Apoptotic activity was determined by condensation and fragmentation of nuclei and by assay of caspase-3-like activity. Necrosis was evaluated from release of cellular enzymes. Ibuprofen (250 μM for 24 h) promoted cell loss, and apoptosis, under both basal conditions and when apoptosis was increased by 25 μM N-Hexanoyl-D-sphingosine (C6-ceramide). Diclofenac (250 μM for 24 h) reduced the proportion of apoptotic nuclei from 5.2 to 2.1%, and caused inhibition of caspase-3-like activity, without causing necrosis under basal conditions. No such reduction in apoptotic activity was evident in the presence of 25 μM C6-ceramide. The inhibitory effect of diclofenac on basal caspase-3-like activity was also exhibited by the structurally similar mefenamic and flufenamic acids (1–250 μM), but not by niflumic acid. Inhibition of superoxide production by the cells increased caspase-3-like activity, but the inhibitory action of diclofenac on caspase activity remained. Diclofenac did not affect superoxide production. Diclofenac inhibited caspase-3-like activity in cell homogenates and also inhibited human recombinant caspase-3. In conclusion, NSAIDs vary in their effect on apoptotic activity in a primary culture of guinea-pig gastric mucous epithelial cells, and the inhibitory effect of diclofenac on basal apoptosis could involve an action on caspase activity.