Protective Effects of Topical Administration of Laminarin in Oxazolone-Induced Atopic Dermatitis-like Skin Lesions.

Laminarin is a polysaccharide isolated from brown marine algae and has a wide range of bioactivities, including immunoregulatory and anti-inflammatory properties. However, the effects of laminarin on atopic dermatitis have not been demonstrated. This study investigated the potential effects of topical administration of laminarin using a Balb/c mouse model of oxazolone-induced atopic dermatitis-like skin lesions. Our results showed that topical administration of laminarin to the ear of the mice improved the severity of the dermatitis, including swelling. Histological analysis revealed that topical laminarin significantly decreased the thickening of the epidermis and dermis and the infiltration of mast cells in the skin lesion. Serum immunoglobulin E levels were also significantly decreased by topical laminarin. Additionally, topical laminarin significantly suppressed protein levels of oxazolone-induced proinflammatory cytokines, such as interleukin-1ß, tumor necrosis factor-α, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1α in the skin lesion. These results indicate that topical administration of laminarin can alleviate oxazolone-induced atopic dermatitis by inhibiting hyperproduction of IgE, mast cell infiltration, and expressions of proinflammatory cytokines. Based on these findings, we propose that laminarin can be a useful candidate for the treatment of atopic dermatitis.

Receptor-mediated targeting of fluorescent probes in living cells.

A strategy was developed to label specified sites in living cells with a wide selection of fluorescent or other probes and applied to study pH regulation in Golgi. cDNA transfection was used to target a single-chain antibody to a specified site such as an organelle lumen. The targeted antibody functioned as a high affinity receptor to trap cell-permeable hapten-fluorophore conjugates. Synthesized conjugates of a hapten (4-ethoxymethylene-2-phenyl-2-oxazolin-5-one, phOx) and fluorescent probes (Bodipy Fl, tetramethylrhodamine, fluorescein) were bound with high affinity (approximately 5 nM) and specific localization to the single-chain antibody expressed in the endoplasmic reticulum, Golgi, and plasma membrane of living Chinese hamster ovary cells. Using the pH-sensitive phOx-fluorescein conjugate and ratio imaging microscopy, pH was measured in the lumen of Golgi (pH 6.25 +/- 0.06). Measurements of pH-dependent vacuolar H+/ATPase pump activity and H+ leak in Golgi provided direct evidence that resting Golgi pH is determined by balanced leak-pump kinetics rather than the inability of the H+/ATPase to pump against an electrochemical gradient. Like expression of the green fluorescent protein, the receptor-mediated fluorophore targeting approach permits specific intracellular fluorescence labeling. A significant advantage of the new approach is the ability to target chemical probes with custom-designed spectral and indicator properties.