Expression of Epithelial-Mesenchymal Transition Markers in Epidermal Layer of Atopic Dermatitis.

The epithelial-mesenchymal transition (EMT) is a phenomenon, in which epithelial cells acquire a mesenchymal cell phenotype. It is important during wound healing; however, chronic inflammation leads to excessive EMT and causes tissue barrier dysfunction with hyperplasia. EMT is induced by several cytokines, such as interleukin (IL)-4 and IL-13. Additionally, IL-4 and IL-13 are known to increase in atopic dermatitis (AD) characterized by intense itching and eczema. Therefore, we assumed that there was commonality between the respective EMT and AD phenotypes. Herein, we evaluated EMT marker expression in AD skin and demonstrated that EMT-maker Snai1 and Twist expression were increased in AD mice model and patients with AD. Moreover, the epithelial-marker keratin 5 and mesenchymal marker Vimentin were co-expressed in the skin epidermis of mice with AD, suggesting the existence of hybrid epithelial-mesenchymal (E/M) cells possessing both epithelial and mesenchymal characteristics. In fact, we found that ΔNp63a, a stabilizing factor for hybrid E/M cells, was upregulated in the skin epidermis of the AD model mouse. Interestingly, increased expression of EMT markers was observed even at a nonlesion site in a patient with AD without initial inflammation or scratching. Therefore, EMT-like phenomena may occur independently of wound healing in skin of patients with AD.

A Novel Function of Sphingosylphosphorylcholine on the Inhibitory Effects of Acetylcholinesterase Activity.

Acetylcholine (ACh), a quaternary ammonium cation, is known as one of the itch inducer in atopic dermatitis (AD), an inflammatory skin disease with intense itching. Previous research has reported accumulation of ACh in lesional site of AD patients. Generally, ACh is metabolized by cholinesterase (ChE). Therefore, one of the causes of ACh accumulation may be the suppression of ChE activity. Increased levels of the multifunctional bioactive sphingolipid sphingosylphosphorylcholine (SPC) have also been detected in AD. Since SPC possesses a quaternary ammonium cation, like ACh, it is possible that SPC affects the activity of ChE catalyzing ACh metabolization. We investigated whether SPC influences the activity of ChE by performing enzymatic analysis of ChE in the presence of SPC. We found that SPC strongly suppressed acetylcholinesterase (AChE) activity, but the suppression of butyrylcholinesterase by SPC was quite low. The Michaelis constant (Km) of AChE in the presence of SPC increased, and the maximum velocity (Vmax) decreased, indicating that SPC acts as mixed-type inhibitor for AChE. The analysis of SPC analogs clarified the importance of both the quaternary ammonium cation and the carbon chain length of SPC for the AChE inhibitory effect and showed that SPC was unique in AChE inhibition among the sphingolipids in this study. These findings indicate a novel function of SPC on AChE inhibition. Thus, the inhibition activity of SPC may be a factor in the increase of ACh in AD.

Novel nanocapsule of α-lipoic acid reveals pigmentation improvement: α-Lipoic acid stimulates the proliferation and differentiation of keratinocyte in murine skin by topical application.

α-Lipoic acid is amphipathic with low molecular sulphur-containing fatty acid and has strong antioxidant effects. It has been used at the purposes of anti-ageing, treatment of diabetic neuropathy, and supplement as antioxidant. Though α-lipoic acid is normally administered in oral or injection, it has not been used in a topical use via skin because of its bad penetration. We developed the novel nanocapsule of α-lipoic acid, named α-lipoactive (nLA), to improve skin permeability. The nLA is constructed as micelles of α-lipoic acid mixed with the non-ionic surfactant, and its surface of the micelles was coated with inorganic metal salts. It is water soluble and has a diameter of approximately 8-15 nm. After nLA was applied to the murine skin, epidermal thickening was observed. It was confirmed that this effect is caused by α-lipoic acid molecule, but not by the raw material used for encapsulation. In in vivo experiments, it was found that nLA is very effective for improving UV-induced pigmentation and epidermal thickening. Our findings suggest that nanoencapsulation of α-lipoic acid is considerably effective for topical application.