In a groundbreaking study, scientists have identified a key role for the protein IL-17 in skin aging. The researchers found that certain immune cells in the skin express high levels of IL-17 during aging, leading to an inflammatory state. By inhibiting IL-17, they noticed a delayed onset of aging symptoms, such as impaired hair follicle growth, percutaneous water loss, slow wound healing and genetic markers of aging.
A team of scientists from the Barcelona Biomedical Research Institute (IRB Barcelona) in collaboration with the National Center for Genome Analysis (CNAG) has discovered that the IL-17 protein plays a central role in skin aging. The study, led by Dr Guiomar Solanas, Dr Salvador Aznar Benitah from IRB Barcelona and Dr Holger Heyn from CNAG, highlights the IL-17-mediated aging process to the inflammatory state.
Skin aging is characterized by a series of structural and functional changes that gradually lead to age-related deterioration and fragility. Aging skin has reduced regenerative capacity, poor healing ability, and weakened barrier function. The study, published in Nature Aging, describes the changes that different types of cells undergo as we age and identifies how some immune cells in the skin express high levels of IL-17.
"Our findings suggest that IL-17 is involved in various functions associated with aging. We observed that blocking the function of this protein slows the appearance of various defects associated with skin aging. For example, the discovery opens up new possibilities for treating certain symptoms or promoting skin recovery after surgery," explains Dr. Aznar Benitah, ICREA researcher and head of the IRB Stem Cell and Cancer Laboratory in Barcelona.
"Single-cell sequencing allowed us to delve into the complexity of the cell types and states that form the skin, and how they change over the life cycle. We found not only differences in the composition of aging skin, but also changes in the active state of the cells. Specifically immune cells exhibit specific age-related signatures, which we can determine by analyzing thousands of individual cells at a time," says Dr. Holger Hein, head of CNAG's Single Cell Genomics Laboratory.
Immune cells, inflammation and aging
In addition to a wide variety of epithelial cells, hair follicle cells, and other components, the skin is also home to immune cells that play a vital role in preventing infection and protecting against various types of damage.
The study describes how some of these immune cells, namely γδ T cells, innate lymphoid cells and CD4+ T cells, increase dramatically in the skin during aging. These cells also began to express very high levels of the pro-inflammatory cytokine IL-17.
"Aging is associated with mild but persistent inflammation and, in the skin, is characterized by a marked increase in IL-17, which leads to skin deterioration," explains Dr Paloma sol and Dr Elisisabetta Mereu, first authors of the paper. Now a researcher at the Josep Carreras Leukemia Institute.
Reverses the symptoms of skin aging
Previous studies have described IL-17 as being involved in some autoimmune skin diseases such as psoriasis, and there are existing treatments that block the protein. The research team studied the response to blocking various aspects of IL-17 activity, including hair follicle growth, transdermal water loss, wound healing and genetic markers of aging. All four parameters improved after treatment, as the acquisition of these aging traits was significantly delayed.
"The IL-17 protein is critical to important functions in the body, such as defense against microbes and wound healing, so permanently blocking it is not possible. What we have observed is that its temporal inhibition provides benefits that may be of interest at the therapeutic level," said Dr Guiomar Solanas, an IRB research associate in Barcelona.
Future work by the researchers will focus on clarifying the aging processes associated with the inflammatory state of the skin and how these processes are linked to IL-17. The team will also investigate whether IL-17 is involved in the aging and degeneration of other tissues and organs.
Background
What is the role of Interleukin-17?
The cytokine interleukin 17 (IL17) family is produced by T cells that have been activated and acts as a pro-inflammatory factor. The IL 17 family consists of several members, including IL 17A, IL 17B, IL 17C, IL 17D, IL 17E, and IL 17F. The structure, sequence, and functions of these cytokines are comparable.
Members of the IL 17 family play critical roles in various arms of the adaptive immune response and are crucial in understanding cytokine networks that coordinate innate and adaptive immunity to specific pathogens. As a result, the IL 17 family members may have a significant impact on health.
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