Increased subcutaneous adipose tissue impairs dermal function in diet-induced obese mice

Increment of subcutaneous adipose tissue is a risk factor for facial morphological changes, such as sagging, which may be at least partly because of the increased weight burden of accumulated fat. However, it is not clear how the increase of subcutaneous adipose tissue affects dermal structure and function. We examined this issue in HR-1 hairless mice given a high-fat diet (HFD). After having been fed with HFD for 12 weeks, the mice became obese and the subcutaneous adipose tissue layer was significantly thickened, while the dermal layer became significantly thinner than that of control mice fed normal diet. However, the thickness of the dermal layer was not changed in the ear pinna, which lacks a subcutaneous adipose layer, suggesting that increase of subcutaneous adipose tissue may induce dermal changes. The number of dermal fibroblasts in the dermis was significantly reduced in obese mice, although there was no change in gene expression levels of extracellular matrix components, including collagen, hyaluronic acid synthase, fibulin5, fibrillin-1, laminin beta 1, matrix metalloproteinases and tissue inhibitor of metalloproteinases. Dermal elasticity was significantly decreased in obese hairless mice. These results suggest that subcutaneous adipose cells in obese mice may reduce the proliferation of dermal fibroblasts and induce a decrease of dermal thickness and elasticity. Therefore, the increment of the subcutaneous adipose layer in obese subjects may induce impairment of dermal biomechanical characteristics and promote the appearance of sagging.