Research conducted at the University of California San Diego (UCSD) School of Medicine has revealed how dermal fibroblasts — specialized cells deep under the skin which generate connective tissue and help the skin recover from injury — develop into fat cells. The ability of these cells to convert into fat cells is what gives the skin a plump, youthful look and produces a peptide which plays a critical role in the immune system. The UCSD researchers have also identified a pathway that causes this process to cease as people age.
“We have discovered how the skin loses the ability to form fat during aging,” said Richard Gallo, MD, PhD, Distinguished Professor and chair of the Department of Dermatology at UCSD School of Medicine and senior author on study. “Loss of the ability of fibroblasts to convert into fat affects how the skin fights infections and will influence how the skin looks during aging.”
This loss of ability has been linked to a protein called transforming growth factor beta (TGF-β) which not only stops the conversion of dermal fibroblasts into fat cells but also prevents the cells from producing the antimicrobial peptide cathelicidin, which helps protect against bacterial infections.
“Babies have a lot of this type of fat under the skin, making their skin inherently good at fighting some types of infections. Aged dermal fibroblasts lose this ability and the capacity to form fat under the skin,” said Gallo. “Skin with a layer of fat under it looks more youthful. When we age, the appearance of the skin has a lot to do with the loss of fat.” These results cannot be achieved through the consumption of excess calories, as weight gain comes with its own set of health problems.
Part of the research included using chemical blockers to inhibit the TGF-β pathway in mice. This caused their skin to revert back to a more youthful form by allowing dermal fibroblasts to convert into fat cells. Subsequently, the researchers deactivated the TGF-β pathway using genetic techniques rather than chemical blockers and achieved the same results.
Understanding these biological processes could be used to treat skin infections such as Staphylococcus aureus (S. aureus) — a pathogenic bacteria that is the leading cause of infections of the skin and heart and a significant factor in diseases, like eczema.