The study shows that UV light can worsen rosacea by boosting the skin's LL-37 peptide and other inflammatory molecules, leading to redness, swelling, and new blood vessels. Blocking UV exposure could therefore help keep rosacea under control.

Rosacea is a common chronic inflammatory skin disease that predominantly affects the central face. It can impair appearance and cause various discomforts, thus negatively impacting patients' physical and mental well-being as well as their quality of life. Its pathophysiological mechanisms involve multiple factors. Studies have confirmed that ultraviolet radiation plays a significant role in the pathogenesis of rosacea, affecting skin tissues, cells, DNA, and proteins, and inducing oxidative damage. Ultraviolet can lead to the occurrence and development of rosacea by up-regulating the expression of LL-37, matrix metalloproteinase, vascular endothelial growth factor, and reactive oxygen species, and influence their interactions, thereby triggering inflammatory responses, altering the dermal matrix, and promoting capillary dilation and neovascularization, which contribute to the onset and progression of rosacea. Exploring the role of ultraviolet in the pathogenesis of rosacea can provide new strategies for protection and treatment, and enhance awareness of ultraviolet protection among patients with rosacea.