title: Environment-induced lentigines: formation of solar lentigines beyond ultraviolet radiation.
abstract: There is no doubt that ultraviolet radiation (UVR) contributes to the generation of acquired lentigines in human skin, as indicated by the term solar lentigo. A growing number of recent epidemiological and mechanistic studies, however, strongly suggest that in addition to UVR, other environmental factors contribute to lentigines' formation as well. We therefore here introduce the term 'environment-induced lentigo' (EIL) to refer to acquired pigment spots of human skin. In this view point, we (i) summarize the existing evidence to support a role of environmental toxicants other than UVR in the pathogenesis of EILs, (ii) we argue that activation of aryl hydrocarbon receptor (AHR) signalling by UVR and environmental toxicants is critically involved in triggering and sustaining a crosstalk between melanocytes, keratinocytes and fibroblasts, which then causes the development and persistence of EILs in human skin, and (iii) we discuss clinical implications for the prevention and treatment of EILs resulting from this concept.
authors.affiliation: IUF - Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.|Department of Environmental and Geriatric Dermatology, Nagoya City University, Nagoya, Japan.
authors.forename: Motoki
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Department of Environmental and Geriatric Dermatology, Nagoya City University, Nagoya, Japan.
authors.forename: Akimichi
authors.initials: A
authors.lastname: Morita
authors.affiliation: L'Oréal, R&D, Asnierès, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Seité
authors.affiliation: IUF - Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Haarmann-Stemmann
authors.affiliation: IUF - Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Grether-Beck
authors.affiliation: IUF - Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany.
authors.forename: Jean
authors.initials: J
authors.lastname: Krutmann
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects; D004781:Environmental Exposure / Q000009:adverse effects*; D006801:Humans; D007911:Lentigo / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D018336:Receptors, Aryl Hydrocarbon / Q000502:physiology / Q000528:radiation effects; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D000393:Air Pollutants; D018336:Receptors, Aryl Hydrocarbon
keywords: air pollution; aryl hydrocarbon receptor; lentigo; skin ageing; ultraviolet radiation