Acne is one of the most common skin diseases in the United States, according to the American Academy of Dermatology Association, affecting up to 50 million Americans each year. It is also one of the least studied.
Hair follicles have been known to help in the development of a pimple, but new research suggests that skin cells outside of these hair follicles play a bigger role. The results published in the February 16, 2022 issue of Science Translational Medicine.
These discoveries could transform the way we treat acne. Previously, hair follicles were thought to be most important for the development of acne. In this study, we looked at cells outside the hair follicle and found that they had a major effect on controlling bacteria and the development of acne.”
Richard Gallo, MD, PhD, Ima Gigli Distinguished Professor of Dermatology and Chairman of the Department of Dermatology at UC San Diego School of Medicine
The cells are called fibroblasts, common in connective tissues throughout the body. In the skin, they produce an antimicrobial peptide called cathelicidin, which plays a key role in the development of acne, Gallo said.
To counter an infection in a hair follicle, the surrounding skin undergoes a process called reactive adipogenesis in which fibroblasts transform into fat cells. Cathelicidin is also produced to help fight infection by killing bacteria that can cause acne.
The discovery of the role of cathelicidin came as a surprise.
“We began our research wanting to understand the biology of acne and specifically looked at the role of fibroblasts, which typically provide structural support in the deeper layers of the skin,” said first author Alan O’Neill, PhD. , project scientist at UC San Diego School of Medicine. “What we found instead was that these cells were activated to produce large amounts of an important antimicrobial, cathelicidin, in response to acne-causing bacteria called Cutibacterium acnes.”
The research team performed skin biopsies on acne patients treated for several months with retinoids, a class of vitamin A-derived chemicals that promote healthy skin. To the researchers’ surprise, the drug enhanced cathelicidin expression after treatment, finding an additional unknown mechanism as to why retinoids help treat acne.
To back up these findings, the researchers studied skin lesions in mice injected with the acne-causing bacteria and observed similar responses to the treatment in the mice.
“Cathelicidine being so highly expressed in acne biopsy tissue was a very exciting finding for us,” Gallo said. “Knowing this will be helpful in developing a more targeted therapy to treat acne.”
Currently, retinoid treatment focuses on controlling the development of lipids in skin cells. A major side effect of these drugs are their teratogenic effects, causing fetal abnormalities in pregnant women. This limits the use of these drugs to severe cases only. The research team hopes these findings can help develop a more targeted approach to treating acne.
“This research could help identify new treatment options that specifically target the ability of fibroblasts to produce cathelicidin,” O’Neill said. “Thus creating an acne treatment that would be more selective with potentially less harmful side effects.”