Abstract
Atopic dermatitis (AD) is a skin allergy accompanied by acute and chronic dermal inflammation. In traditional oriental medicine, Laminaria japonica has been used to treat various diseases, including inflammatory diseases. Therefore, to determine the therapeutic potential of L. japonica against AD, we investigated the inhibitory effects of L. japonica water extract (LJWE) on the inflammatory mediators and AD-like skin lesions. We determined the cell viability of LJWE-treated HaCaT cells using the cell counting kit-8 assay and the levels of inflammatory cytokines using cytometric bead array kits. Additionally, we analyzed the modulatory effects of LJWE on the signaling pathways in tumor necrosis factor-α/interferon-γ-stimulated HaCaT cells via Western blotting. Furthermore, we determined the in vivo effect of LJWE on NC/Nga mice and found that LJWE remarkably improved the skin moisture, reduced dermatitis severity, and inhibited the overproduction of inflammatory mediators in 2,4-dinitrochlorobenzene-sensitized NC/Nga mice. We also observed that LJWE inhibits the expression of inflammatory chemokines in human keratinocytes by downregulating the p38 mitogen-activated protein kinase signaling pathway and activating the signal transducer and activator of transcription 1. In conclusion, LJWE has the therapeutic potential against AD by healing AD-like skin lesions, and suppressing inflammatory mediators and major signaling molecules.
Highlights
Atopic dermatitis (AD), a skin allergy that affects infants and adults, is characterized by clinical symptoms such as redness, dryness, itchiness, and the thickening of the inflamed skin lesions [1,2].The pathogenesis of AD is affected by a variety of factors, including genetics, environment, psychological state, host immune dysfunction, and defective epidermal barriers [1]
Keratinocytes stimulated by pro-inflammatory cytokines secrete inflammatory mediators under the regulation of nuclear factor-kappa B (NF-κB), mitogen-activated protein kinases (MAPKs), and signal transducer and activator of transcription (STAT), leading to the infiltration of monocytes, mast cells, and T lymphocytes and the stimulation of inflammatory response in the dermis [6,7,8]
We investigated the inhibitory effects of L. japonica water extract (LJWE) on the overproduction of inflammatory cytokines in tumor necrosis factor (TNF)-α and IFN-γ-stimulated human keratinocytes, and assessed the beneficial effects of LJWE in AD-like skin lesions in NC/Nga mice
Summary
Atopic dermatitis (AD), a skin allergy that affects infants and adults, is characterized by clinical symptoms such as redness, dryness, itchiness, and the thickening of the inflamed skin lesions [1,2].The pathogenesis of AD is affected by a variety of factors, including genetics, environment, psychological state, host immune dysfunction, and defective epidermal barriers [1]. The pathogenesis of AD is not fully clarified, many researchers have found that AD is associated with a defective skin barrier and leads to allergic responses in inflamed keratinocytes [3]. In the skin lesion of acute AD, the secretion of IL-4, IL-5, and IL-13 by Th-2 cells, and IgE production by B cells, are increased [4]. Keratinocytes stimulated by pro-inflammatory cytokines secrete inflammatory mediators under the regulation of nuclear factor-kappa B (NF-κB), mitogen-activated protein kinases (MAPKs), and signal transducer and activator of transcription (STAT), leading to the infiltration of monocytes, mast cells, and T lymphocytes and the stimulation of inflammatory response in the dermis [6,7,8]. The development and application of herbal medicines and their derivatives, as complementary and alternative candidates, to relieve the symptoms of AD are increasing because of their long-term use and effectiveness against AD [10]
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