BACKGROUND: Compared with the detailed characterization of the ultraviolet (UV) response in human skin, the effects of infrared (IR) and other regions of the sunlight are scarce. OBJECTIVES: To determine the participation of IR/visible light and heat components of the sunlight on matrix metalloproteinases (MMPs) and type I procollagen expression, and inflammatory cell infiltration in human skin in vivo. METHODS: The buttocks of 16 healthy volunteers (aged 24-43 years, 10 male and 6 female) were irradiated with a 1.1-3 minimal erythema dose (MED) of natural sunlight. To determine the differential effects of UV, IR/visible rays and solar heat alone, the exposed sites were covered with either a UV filter or black cloth, respectively, during irradiation. Skin samples were taken 24h later. RESULTS: IR/visible light spectrum of sunlight significantly increased MMP-1 and MMP-9 expression and decreased type I procollagen expression. Solar heat also contributed to the increased MMP-1 expression. Only the UV region recruited neutrophils into the dermis, while UV, IR/visible light and heat contributed to macrophage infiltration. CONCLUSIONS: IR/visible light and heat of natural sunlight, in addition to UV, play a role in modulating the expressions of MMPs and procollagen, and inflammatory cell infiltration in human skin.
BACKGROUND: Compared with the detailed characterization of the ultraviolet (UV) response in human skin, the effects of infrared (IR) and other regions of the sunlight are scarce. OBJECTIVES: To determine the participation of IR/visible light and heat components of the sunlight on matrix metalloproteinases (MMPs) and type I procollagen expression, and inflammatory cell infiltration in human skin in vivo. METHODS: The buttocks of 16 healthy volunteers (aged 24-43 years, 10 male and 6 female) were irradiated with a 1.1-3 minimal erythema dose (MED) of natural sunlight. To determine the differential effects of UV, IR/visible rays and solar heat alone, the exposed sites were covered with either a UV filter or black cloth, respectively, during irradiation. Skin samples were taken 24h later. RESULTS: IR/visible light spectrum of sunlight significantly increased MMP-1 and MMP-9 expression and decreased type I procollagen expression. Solar heat also contributed to the increased MMP-1 expression. Only the UV region recruited neutrophils into the dermis, while UV, IR/visible light and heat contributed to macrophage infiltration. CONCLUSIONS: IR/visible light and heat of natural sunlight, in addition to UV, play a role in modulating the expressions of MMPs and procollagen, and inflammatory cell infiltration in human skin.
Authors: Sérgio Schalka; Denise Steiner; Flávia Naranjo Ravelli; Tatiana Steiner; Aripuanã Cobério Terena; Carolina Reato Marçon; Eloisa Leis Ayres; Flávia Alvim Sant'anna Addor; Helio Amante Miot; Humberto Ponzio; Ida Duarte; Jane Neffá; José Antônio Jabur da Cunha; Juliana Catucci Boza; Luciana de Paula Samorano; Marcelo de Paula Corrêa; Marcus Maia; Nilton Nasser; Olga Maria Rodrigues Ribeiro Leite; Otávio Sergio Lopes; Pedro Dantas Oliveira; Renata Leal Bregunci Meyer; Tânia Cestari; Vitor Manoel Silva dos Reis; Vitória Regina Pedreira de Almeida Rego Journal: An Bras Dermatol Date: 2014 Nov-Dec Impact factor: 1.896