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Lin TK, Tsai CL, Tsai BCK, Kuo CH, Ho TJ, Hsieh DJY, Kuo WW, Huang CY. Low-concentration imiquimod treatment promotes enhanced skin barrier functions through epidermal melanization reaction regulation. ENVIRONMENTAL TOXICOLOGY 2024. [PMID: 38760990 DOI: 10.1002/tox.24332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/31/2024] [Accepted: 04/29/2024] [Indexed: 05/20/2024]
Abstract
The primary function of the skin is to form a mechanical, permeability, antimicrobial, and ultraviolet radiation barrier, which is essential for maintaining physiological homeostasis. Our previous studies demonstrated that cutaneous pigmentation could promote skin barrier function in addition to providing anti-ultraviolet irradiation defense. The present study aimed to develop a new regimen that enhances skin barrier function by regulating skin pigmentation using low-concentration imiquimod. Results showed that topical application of low-concentration imiquimod effectively induced skin hyperpigmentation in the dorsal skin and external ear of mice without inducing inflammatory cell infiltration. An in vitro study also revealed that low-concentration imiquimod did not induce any cytotoxic effects on melanoma cells but triggered excessive melanin synthesis. In coculture systems, low-concentration imiquimod was noted to increase tyrosinase activity in a broader cellular context, revealing the potential role of neighboring cells in melanin production. The next-generation sequencing result indicated that PKCη and Dnm3 might regulate melanin synthesis and release during imiquimod treatment. Overall, our study presents new insights into the regulation of melanin production by low-concentration imiquimod, both in a mice model and cultured cells. Furthermore, our study highlights the potential benefits of imiquimod in promoting melanin synthesis without causing skin disruptions or inducing inflammation, validating its potential to serve as a method for enhancing skin barrier functions by regulating the epidermal melanization reaction.
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Affiliation(s)
- Tzu-Kai Lin
- Department of Dermatology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chia-Lun Tsai
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Bruce Chi-Kang Tsai
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Chia-Hua Kuo
- Institute of Sports Sciences, University of Taipei, Taipei, Taiwan
- Laboratory of Exercise Biochemistry, Institute of Sports Sciences, University of Taipei, Tianmu Campus, Taipei, Taiwan
- Department of Kinesiology and Health Science, College of William and Mary, Williamsburg, Virginia, USA
| | - Tsung-Jung Ho
- Department of Chinese Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Integration Center of Traditional Chinese and Modern Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- School of Post-Baccalaureate Chinese Medicine, College of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Dennis Jine-Yuan Hsieh
- School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
- Clinical Laboratory, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Wei-Wen Kuo
- Department of Biological Science and Technology, College of Life Sciences, China Medical University, Taichung, Taiwan
- Ph.D. Program for Biotechnology Industry, China Medical University, Taichung, Taiwan
- School of Pharmacy, China Medical University, Taichung, Taiwan
| | - Chih-Yang Huang
- Cardiovascular and Mitochondrial Related Disease Research Center, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung, Taiwan
- Center of General Education, Buddhist Tzu Chi Medical Foundation, Tzu Chi University of Science and Technology, Hualien, Taiwan
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Hirobe T. Role of Dermal Factors Involved in Regulating the Melanin and Melanogenesis of Mammalian Melanocytes in Normal and Abnormal Skin. Int J Mol Sci 2024; 25:4560. [PMID: 38674144 PMCID: PMC11049857 DOI: 10.3390/ijms25084560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/13/2024] [Accepted: 04/14/2024] [Indexed: 04/28/2024] Open
Abstract
Mammalian melanin is produced in melanocytes and accumulated in melanosomes. Melanogenesis is supported by many factors derived from the surrounding tissue environment, such as the epidermis, dermis, and subcutaneous tissue, in addition to numerous melanogenesis-related genes. The roles of these genes have been fully investigated and the molecular analysis has been performed. Moreover, the role of paracrine factors derived from epidermis has also been studied. However, the role of dermis has not been fully studied. Thus, in this review, dermis-derived factors including soluble and insoluble components were overviewed and discussed in normal and abnormal circumstances. Dermal factors play an important role in the regulation of melanogenesis in the normal and abnormal mammalian skin.
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Affiliation(s)
- Tomohisa Hirobe
- Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
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Speeckaert R, Belpaire A, Speeckaert M, van Geel N. The delicate relation between melanocytes and skin immunity: A game of hide and seek. Pigment Cell Melanoma Res 2022; 35:392-407. [PMID: 35298085 DOI: 10.1111/pcmr.13037] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 02/13/2022] [Accepted: 03/09/2022] [Indexed: 01/19/2023]
Abstract
Melanocytes exhibit a complex and intriguing relationship with the skin immune response, leading to several clinical conditions. In some disorders, inappropriate melanocyte destruction (e.g., vitiligo, halo naevi) is problematic, while in others, immune tolerance should be broken (melanoma). Important parts of the dysregulated pathways have been unraveled in pigment disorders, ranging from upregulated interferon (IFN)-γ signaling to memory T cells, regulatory T cells, and immune checkpoints. Although a network of many factors is involved, targeting key players such as IFN-γ or checkpoint inhibitors (e.g., programmed death-ligand 1 (PD-L1)] can shift the balance and lead to impressive outcomes. In this review, we focus on the immunological mechanisms of the most common inflammatory disorders where the interaction of the immune system with melanocytes plays a crucial role. This can provide new insights into the current state of melanocyte research.
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Affiliation(s)
| | - Arno Belpaire
- Department of Dermatology, Ghent University Hospital, Ghent, Belgium
| | | | - Nanja van Geel
- Department of Dermatology, Ghent University Hospital, Ghent, Belgium
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Hirobe T, Shibata T, Sato K. Human fibroblasts treated with hydrogen peroxide stimulate human melanoblast proliferation and melanocyte differentiation, but inhibit melanocyte proliferation in serum-free co-culture system. J Dermatol Sci 2016; 84:282-295. [DOI: 10.1016/j.jdermsci.2016.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/16/2016] [Accepted: 09/05/2016] [Indexed: 02/05/2023]
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Platelet-derived growth factor regulates the proliferation and differentiation of human melanocytes in a differentiation-stage-specific manner. J Dermatol Sci 2016; 83:200-9. [PMID: 27289338 DOI: 10.1016/j.jdermsci.2016.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/26/2016] [Accepted: 05/17/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Although many kinds of keratinocyte-derived factors are known to regulate the proliferation and differentiation of human melanocytes, it is not well defined whether dermis-derived factors work in a similar way. OBJECTIVE The aim of this study is to clarify whether dermal factors are involved in regulating the proliferation and differentiation of human melanocytes. METHODS Human epidermal melanoblasts were cultured serially in a serum-free growth medium. Platelet-derived growth factor-BB (PDGF-BB) was supplemented to the medium, and the effects on the proliferation of melanoblasts/melanocytes and the differentiation of melanocytes were studied. RESULTS PDGF-BB stimulated the proliferation of melanoblasts cultured in melanoblast-proliferation medium, but inhibited the proliferation of melanocytes cultured in melanocyte-proliferation medium. By contrast, PDGF-BB stimulated the differentiation, dendritogenesis, and melanogenesis of melanocytes through the stimulation of tyrosinase activity and the expressions of tyrosinase and tyrosinase-related protein-1. CONCLUSION These results suggest that PDGF-BB regulates the proliferation and differentiation of human melanocytes in a differentiation-stage-specific manner. PDGF-BB seems to be one of the dermal factors that regulate the proliferation and differentiation of human melanocytes.
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Kawakami T, Ohgushi A, Hirobe T, Soma Y. Effects of 1,25-dihydroxyvitamin D3 on human epidermal melanocytes and melanoblasts. J Dermatol Sci 2014; 76:72-4. [DOI: 10.1016/j.jdermsci.2014.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/21/2014] [Accepted: 07/06/2014] [Indexed: 11/29/2022]
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Lee BW, Schwartz RA, Hercogová J, Valle Y, Lotti TM. Vitiligo road map. Dermatol Ther 2013; 25 Suppl 1:S44-56. [PMID: 23237038 DOI: 10.1111/dth.12006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Vitiligo is a depigmenting disorder stemming from melanocyte loss or dysfunction. It has a complex, multifaceted etiology. We constructed a "vitiligo road map," consisting of basic science, clinical, and treatment components, in order to better portray our current understanding of vitiligo pathogenesis and reflect upon novel biomarkers and therapeutic targets for future research. The melanocyte map elaborates on the molecular processes and intracellular signaling pathways initiated by various external autocrine/paracrine factors in representing normal melanocyte homeostatic functions modulating its viability, proliferation, differentiation, dendricity, migration, and melanogenic processes. This vitiligo map identifies known inducers/triggers of vitiligo onset and progression that cultivate a microenvironment for melanocyte disappearance, real or functional. This map describes the molecular mechanisms of currently utilized clinical and experimental treatments of vitiligo that facilitate repigmentation.
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Affiliation(s)
- Brian W Lee
- Dermatology and Pathology, New Jersey Medical School, Newark, New Jersey 07103-2714, USA
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Zhao Z, Jin C, Ding K, Ge X, Dai L. Dedifferentiation of human epidermal melanocytes into melanoblasts in vitro. Exp Dermatol 2012; 21:504-8. [PMID: 22540983 DOI: 10.1111/j.1600-0625.2012.01488.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Melanoblasts (MB) are also called melanocyte (MC) precursor cells. In recent years, people have successfully cultivated human and mouse MB. Previous studies have shown that EDN3 induces cultivated bird MC to re-differentiate into double potential progenitor cells of MB. However, no study has reported whether in vitro cultivated human MC can be dedifferentiated. Our research on MC that were purified and cultivated in vitro found that adding 10 nm endothelin 1 (EDN1) (ET-1) to the MC medium without phorbol 12-myristate 13-acetate (PMA) induced a few MC to dedifferentiate and become a new type of cell. This new cell type was separated, purified, cloned and identified using multiple approaches. The results show that 88.7%, 8.69% and 2.5% of this new cell type were cells in the G(0) -G(1) , G(2) -M and S stages, respectively. The new cell type did not exhibit an apparent apoptotic peak, and its apoptotic rate was 0.09%. Stage I melanosomes were observed in the cytoplasm and were negative for the DOPA reaction. The cell surface antigen expression was positive for tyrosinase-related protein 2, negative or positive for c-kit and negative for S-100 and HMB45, showing that these cells were dedifferentiated MB of MC. Our findings provided evidence for atavism of mature human MC under certain conditions.
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Affiliation(s)
- Zhiguo Zhao
- Department of Dermatology, the Affiliated of People's Hospital of Jiangsu University, Jiangsu, China.
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UV-B radiation induces macrophage migration inhibitory factor-mediated melanogenesis through activation of protease-activated receptor-2 and stem cell factor in keratinocytes. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:679-87. [PMID: 21281800 DOI: 10.1016/j.ajpath.2010.10.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 10/05/2010] [Accepted: 10/15/2010] [Indexed: 12/15/2022]
Abstract
UV radiation indirectly regulates melanogenesis in melanocytes through a paracrine regulatory mechanism involving keratinocytes. Protease-activated receptor (PAR)-2 activation induces melanosome transfer by increasing phagocytosis of melanosomes by keratinocytes. This study demonstrated that macrophage migration inhibitory factor (MIF) stimulated PAR-2 expression in human keratinocytes. In addition, we showed that MIF stimulated stem cell factor (SCF) release in keratinocytes; however, MIF had no effect on the release of endothelin-1 or prostaglandin E2 in keratinocytes. In addition, MIF had no direct effect on melanin and tyrosinase synthesis in cultured human melanocytes. The effect of MIF on melanogenesis was also examined using a three-dimensional reconstituted human epidermal culture model, which is a novel, commercially available, cultured human epidermis containing functional melanocytes. Migration inhibitory factor induced an increase in melanin content in the epidermis after a 9-day culture period. Moreover, melanin synthesis induced by UV-B stimulation was significantly down-regulated by anti-MIF antibody treatment. An in vivo study showed that the back skin of MIF transgenic mice had a higher melanin content than that of wild-type mice after 12 weeks of UV-B exposure. Therefore, MIF-mediated melanogenesis occurs mainly through the activation of PAR-2 and SCF expression in keratinocytes after exposure to UV-B radiation.
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Abstract
Coat colors are determined by melanin (eumelanin and pheomelanin). Melanin is synthesized in melanocytes and accumulates in special organelles, melanosomes, which upon maturation are transferred to keratinocytes. Melanocytes differentiate from undifferentiated precursors, called melanoblasts, which are derived from neural crest cells. Melanoblast/melanocyte proliferation and differentiation are regulated by the tissue environment, especially by keratinocytes, which synthesize endothelins, steel factor, hepatocyte growth factor, leukemia inhibitory factor and granulocyte-macrophage colony-stimulating factor. Melanocyte differentiation is also stimulated by alpha-melanocyte stimulating hormone; in the mouse, however, this hormone is likely carried through the bloodstream and not produced locally in the skin. Melanoblast migration, proliferation and differentiation are also regulated by many coat color genes otherwise known for their ability to regulate melanosome formation and maturation, pigment type switching and melanosome distribution and transfer. Thus, melanocyte proliferation and differentiation are not only regulated by genes encoding typical growth factors and their receptors but also by genes classically known for their role in pigment formation.
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Affiliation(s)
- Tomohisa Hirobe
- Radiation Effect Mechanisms Research Group, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba, Japan Graduate School of Science, Chiba University, Yayoi-cho, Inage-ku, Chiba, Japan.
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Elias PM, Menon G, Wetzel BK, Williams JJW. Evidence that stress to the epidermal barrier influenced the development of pigmentation in humans. Pigment Cell Melanoma Res 2009; 22:420-34. [PMID: 19508412 DOI: 10.1111/j.1755-148x.2009.00588.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Peter M Elias
- Dermatology Services, Veterans Affairs Medical Center, University of California, San Francisco, CA, USA.
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