Comparative analysis of intercellular lipid organization and composition between psoriatic and healthy stratum corneum.

The lipid composition and organization of the stratum corneum (SC) in patients with psoriasis and healthy subjects were compared using X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and ultraperformance liquid chromatography, combined with time-of-flight mass spectrometry (UPLC-TOFMS). In healthy SC (HSC), SC lipids formed two lamellar phases (long and short periodicity phases). Hexagonal and orthorhombic hydrocarbon-chain packing were observed in the lateral lipid organization at 30 °C via X-ray diffraction. In HSC, the lamellar phases and the hydrocarbon-chain packing organizations changed with elevated temperatures and finally disappeared. In these behaviors, the high-temperature hexagonal hydrocarbon-chain packing organization, which appeared above the orthorhombic hydrocarbon-chain packing organization, transformed to the liquid phase at about 90 °C in HSC. In psoriatic SC (PSC), hexagonal hydrocarbon-chain packing organization disappeared at about 65 °C with elevated temperatures. No high-temperature hexagonal hydrocarbon-chain packing organization were observed in PSC during heating process. Disorder of the hydrocarbon-chain packing of SC lipids was observed in PSC via FT-IR. In UPLC-TOFMS, free fatty acid (FFA) and ceramide (CER) compositions differed between patients with PSC and HSC. Specifically, the levels of ultra-long chain fatty acids containing CER and phytosphingosine-containing CER were decreased, while those of sphingosine and dihydrosphingosine-containing CER and unsaturated FFA were increased in PSC. Furthermore, FFA and CER carbon chain lengths decreased in patients with PSC. These results suggest that the alteration of SC lipid composition and the reduction of carbon chain lengths in PSC lowered the structural transformation temperature, thereby reducing barrier function.

Development of novel polyglycerol fatty acid ester-based nanoparticles for the dermal delivery of tocopherol acetate.

The aim of this study was to develop and evaluate novel polyglycerol fatty acid ester (PGFE)-based nanoparticles (NPs) for the dermal delivery of tocopherol acetate (TA). TA-loaded PGFE-based NPs (PGFE-NPs) were prepared by mixing PGFE, soya phosphatidylcholine, dimyristoylphosphatidylglycerol, and TA with film using the film rehydration and extrusion method. The prepared formulations were analyzed by dynamic light scattering, small-angle X-ray diffraction and polarization microscopy. An in vitro skin accumulation test was performed with TA under occlusive and non-occlusive applications, using Yucatan micropig skin. The size range of the TA-loaded liposome and PGFE-NPs was 107-128 nm, and they were encapsulated in 1.6-2.3 mg/mL TA. All PGFE-NP formulations were negatively charged and stable for 2 weeks. Under occlusive applications, all formulations induced small amounts of TA accumulation in the epidermis but not in the dermis. However, under non-occlusive applications, some of PGFE-NP formulations enhanced TA accumulation in the epidermis. Furthermore, only the polyglycerol 4-laurate (PG4L)-based formulation induced dermal TA accumulation with the change in the formulation from a vesicular to bilayer stacked structure following water evaporation under non-occlusive applications. These results indicated that the novel TA-loaded PG4L formulation enabled the dermal delivery of TA in non-occlusive applications.

Development of phospholipid nanoparticles encapsulating 3-O-cetyl ascorbic acid and tocopherol acetate (TA-Cassome) for improving their skin accumulation.

Phospholipid nanoparticles (PNs) encapsulating vitamin C and E derivatives, 3-O-cetyl ascorbic acid (CA) and tocopherol acetate (TA), respectively, were examined using the film rehydration and extrusion method. PN formulations (TA-Cassome) were prepared by mixing CA, soya phosphatidylcholine (Soya PC), sodium cholate, and TA at a molar ratio of 20/80/5/6. Glycerol (GL) or diglycerol (DG) were also added to improve the skin accumulation of CA and TA. Three TA-Cassome formulations were evaluated using a dynamic light scattering (DLS), NMR, TEM, skin accumulation test for CA and TA, and small-angle X-ray diffraction (SAXD) analysis. TA-Cassome formulations (150 nm) were stable for two weeks and they encapsulated 1.8 mg/mL of TA. TEM and SAXD analysis revealed that the nanoparticles formed a spherical multilayer structure. 1H and 31P NMR indicated that GL and DG enhanced the proton mobility of choline groups of soya PC molecules located on the membrane surface of TA-Cassome. Accumulation of CA and TA in the dermis was increased by adding GL and DG. SAXD analysis revealed that GL and DG promoted the formation of new lamellar structures on the stratum corneum, which contributed to improving the skin accumulation of CA and TA.