Far-infrared suppresses skin photoaging in ultraviolet B-exposed fibroblasts and hairless mice

PLoS One. 2017 Mar 16;12(3):e0174042. doi: 10.1371/journal.pone.0174042. eCollection 2017.


Ultraviolet (UV) induces skin photoaging, which is characterized by thickening, wrinkling, pigmentation, and dryness. Collagen, which is one of the main building blocks of human skin, is regulated by collagen synthesis and collagen breakdown. Autophagy was found to block the epidermal hyperproliferative response to UVB and may play a crucial role in preventing skin photoaging. In the present study, we investigated whether far-infrared (FIR) therapy can inhibit skin photoaging via UVB irradiation in NIH 3T3 mouse embryonic fibroblasts and SKH-1 hairless mice. We found that FIR treatment significantly increased procollagen type I through the induction of the TGF-β/Smad axis. Furthermore, UVB significantly enhanced the expression of matrix metalloproteinase-1 (MMP-1) and MMP-9. FIR inhibited UVB-induced MMP-1 and MMP-9. Treatment with FIR reversed UVB-decreased type I collagen. In addition, FIR induced autophagy by inhibiting the Akt/mTOR signaling pathway. In UVB-induced skin photoaging in a hairless mouse model, FIR treatment resulted in decreased skin thickness in UVB irradiated mice and inhibited the degradation of collagen fibers. Moreover, FIR can increase procollagen type I via the inhibition of MMP-9 and induction of TGF-β in skin tissues. Therefore, our study provides evidence for the beneficial effects of FIR exposure in a model of skin photoaging.

MeSH terms

  • Animals
  • Autophagy / radiation effects
  • Collagen Type I / metabolism
  • Fibroblasts / radiation effects
  • Infrared Rays*
  • Matrix Metalloproteinase 1 / metabolism
  • Matrix Metalloproteinase 9 / metabolism
  • Mice
  • Mice, Hairless
  • NIH 3T3 Cells
  • Proto-Oncogene Proteins c-akt / metabolism
  • Signal Transduction / radiation effects
  • Skin Aging / radiation effects*
  • TOR Serine-Threonine Kinases / metabolism
  • Ultraviolet Rays*


  • Collagen Type I
  • mTOR protein, mouse
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Matrix Metalloproteinase 9
  • Matrix Metalloproteinase 1

Grants and funding

This study was supported by the Taipei Medical University-Shuang Ho Hospital (105TMU-SHH-12) and the Ministry of Science and Technology, Taiwan (MOST 105-2320-B-038 -021 -MY3). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.