Acetylcholinesterase is regulated by exposure of ultraviolet B in skin keratinocytes: A potential inducer of cholinergic urticaria.

Cholinergic urticaria is a dermatological disease characterized by the presence of large patches of red skin and transient hives triggered by factors, such as exercise, sweating, and psychological tension. This skin problem is hypothesized to be attributed to a reduced expression of acetylcholinesterase (AChE), an enzyme responsible for hydrolyzing acetylcholine (ACh). Consequently, ACh is thought to the leak from sympathetic nerves to skin epidermis. The redundant ACh stimulates the mast cells to release histamine, triggering immune responses in skin. Here, the exposure of ultraviolet B in skin suppressed the expression of AChE in keratinocytes, both in in vivo and in vitro models. The decrease of the enzyme was resulted from a declined transcription of ACHE gene mediated by micro-RNAs, that is, miR-132 and miR-212. The levels of miR-132 and miR-212 were markedly induced by exposure to ultraviolet B, which subsequently suppressed the transcriptional rate of ACHE. In the presence of low level of AChE, the overflow ACh caused the pro-inflammatory responses in skin epidermis, including increased secretion of cytokines and COX-2. These findings suggest that ultraviolet B exposure is one of the factors contributing to cholinergic urticaria in skin.

An Optimized Extract, Named Self-Growth Colony, from Platelet-Rich Plasma Shows Robust Skin Rejuvenation and Anti-Ageing Properties: A Novel Technology in Development of Cosmetics.

INTRODUCTION: Inspired by application of platelet-rich plasma (PRP) in skin treatment during injuries, an extracting method was developed here to recover high amounts of cytokines and growth factors from PRP; this prepared extract was named as self-growth colony (SGC). METHODS: In optimization of SGC preparation, various parameters were tested, for example, centrifugation force, freeze-thaw, sonication, and inclusion of calcium chelator. The amounts of cytokines and growth factors, including platelet factor 4, ß-thromboglobulin, epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, were measured by ELISA assay. RESULTS: By comparing to PRP, the prepared SGC contained a significant higher amount of measured growth factors. In addition, the degradation of growth factors within SGC during the storage was calibrated, which showed better stability as compared to that of PRP preparation. Having possible application in skin care, the optimized SGC was chemically standardized by using the enrichment of growth factors. Application of SGC in cultured keratinocytes stimulated the wound healing of injured cultures. In line to this notion, SGC was applied onto human skin, and thereafter the robust improvement of skin properties was revealed. CONCLUSIONS: The potential application of SGC in treating skin rejuvenation and ageing, as well as its elaborated application for medical purpose, that is, wound healing, was illustrated.

Cholinergic Signaling Mediated by Muscarinic Receptors Triggers the Ultraviolet-Induced Release of Melanosome in Cultured Melanoma Cells.

In skin, melanin is synthesized and stored in melanosomes. In epidermal melanocytes, melanosomes are transported to and internalized by the neighboring keratinocytes, subsequently leading to skin pigmentation. Ultraviolet (UV) radiation induces the release of acetylcholine (ACh) from keratinocytes, which in turn activates ACh receptors (AChRs) on nearby melanocytes, forming a proposed "skin synapse". Here, we illustrated that the UV-induced melanosome release from cultured B16F10 melanoma cells could be mediated by co-actions of ACh. In the cell cultures, UV exposure robustly elicited melanosome release. Applied bethanechol (BeCh), an agonist of muscarinic AChR (mAChR), could significantly enhance the release. In parallel, the intracellular Ca2+ mobilization was regulated. The applied antagonists of M1 and/or M3 mAChRs could block the UV-induced melanosome release and the mobilization of intracellular Ca2+. The phosphorylation of PKC, triggered by UV and BeCh treatments, could be suppressed by the applied mAChR antagonists. The expressions of tethering complex for exocytosis, for example, Sec8, Exo70, and Rab11b, as well as synaptotagmin, were increased under UV exposure together with mAChR agonist: The inductions were fully abolished by M1 or M3 antagonist. Here, we hypothesize that the cholinergic signaling is playing roles in UV-induced exocytosis of melanosomes.

The UV-induced uptake of melanosome by skin keratinocyte is triggered by α7 nicotinic acetylcholine receptor-mediated phagocytosis.

The melanosome is an organelle that produces melanin for skin pigmentation, which is synthesized by epidermal melanocytes, subsequently transported and internalized by epidermal keratinocytes. Exposure to ultraviolet (UV) from sunlight radiation is a major stimulator of melanosome uptake by keratinocytes. Acetylcholine (ACh) is known to be released by keratinocytes under UV exposure, which regulates melanin production in melanocytes by participating in which has been named as 'skin synapse'. Here, the role of cholinergic molecules, i.e. ACh and α7 nicotinic acetylcholine receptor (nAChR), in regulating melanosome uptake through phagocytosis by keratinocytes was illustrated. In cultured keratinocytes (HaCaT cells), the fluorescent beads at different sizes imitating melanosomes, or melanosomes, were phagocytosed under UV exposure. The UV-induced phagocytosis in keratinocytes was markedly increased by applied ACh, an acetylcholinesterase (AChE) inhibitor or an α7 nAChR agonist. By contrast, the antagonist of α7 nAChR was able to fully block the UV-induced phagocytosis, suggesting the role of α7 nAChR in this event. The intracellular Ca++ mobilization was triggered by UV exposure, accounting for the initiation of phagocytosis. The blockage of UV-mediated Ca++ mobilization, triggered by BAPTA-AM or α7 nAChR antagonist, resulted in a complete termination of phagocytosis. Besides, the phosphorylation of cofilin, as well as expression and activation of RhoA, accounting for phagocytosis was induced by UV exposure: the phosphorylation was blocked by BAPTA-AM or α7 nAChR antagonist. The result suggests that the cholinergic system, especially α7 nAChR, is playing a regulatory role in modulating melanosome uptake in keratinocytes being induced by UV exposure.

Scutellarin potentiates the skin regenerative function of self growth colony, an optimized platelet-rich plasma extract, in cultured keratinocytes through VEGF receptor and MAPK signaling.

BACKGROUND: Migration of keratinocyte plays an essential role in wound healing. The proprietary platelet-rich plasma from human blood, named as self-growth colony (SGC), functions in stimulating migration of wounded keratinocytes. In addition, the growth factors, including VEGF, being enriched in SGC could account for this function. Scutellarin, an active phytochemical from root of Scutellaria barbata D. Don, has been proposed to have various pharmacological functions; however, the activity in epidermal skin cells is yet to be explored. Here, the role of scutellarin in potentiating the functionality of SGC to promote the regeneration of wounded keratinocyte was probed. METHODS: Molecular docking and ultrafiltration-based LC-MS were performed to verify the binding between scutellarin and VEGF, which potentiated the VEGF-mediated functions. Scratch assay, performed on cultured keratinocytes, was to analyze the treatments of SGC and scutellarin in the process of wound healing. Western blot analysis was to confirm the involvement of signaling cascades in observed effects. RESULTS: We have identified the binding of scutellarin with VEGF. The binding accounted for the potentiation role of scutellarin in skin regeneration, as triggered by SGC. The co-treatment of scutellarin and SGC onto scratched keratinocyte cultures was able to enhance the process of wound healing, that is, scutellarin showed a potentiating effect to SGC. In addition, the potentiation of scutellarin was shown to be mediated by phosphorylation of VEGF receptor-2 (VEGFR2) and mitogen-activated protein kinase (MAPK) signaling. CONCLUSION: These findings support the application of scutellarin as an enhancing agent in potentiating the SGC-mediated wound healing.

A prepared platelet-rich plasma extract, namely Self-Growth Colony, inhibits melanogenesis by down-regulating microphthalmia-associated transcription factor in skin melanocyte.

BACKGROUND: During melanogenesis, melanocytes produce melanin through enzymatic reactions. Microphthalmia-associated transcription factor (MITF) is a major regulator in controlling the expressions of melanogenic enzymes tyrosinase (TYR), tyrosine-related protein-1 (TRP1), and dopachrome tautomerase (DCT). Self-Growth Colony (SGC) is prepared from human platelet-rich plasma (PRP) having an enrichment of growth factors, and which has claimed skin regeneration function. AIM: In this study, we aim to identify and investigate the novel role of SGC in skin melanogenesis. METHODS: MTT assay was performed to determine the cytotoxicity of applied SGC. Melanin assay was adopted to quantify the intracellular melanin after SGC treatment. Promoter-driven luciferase assay, real-time PCR, and Western blotting were performed to determine the expressions of melanogenic enzymes and MITF in SGC-treated cultured Melan-A cells, being treated with or without UV induction. Ex vivo mouse skin was treated with SGC, and then was subjected to Western blotting and histochemical staining. RESULTS: We identified that SGC inhibited melanogenesis in cultured melanocytes and ex vivo mouse skin. The phenomena were attributed to a reduction of MITF expression, which subsequently down-regulated the melanogenic enzymes, that is, TYR, TRP1, and DCT. Moreover, ERK signaling was activated in the SGC-inhibited melanogenesis. CONCLUSIONS: The findings suggest that SGC extracting from human blood can be a safe and potential agent in promoting skin whitening.