Experimental laboratory models have shown that intradermal injections of LL-37 increase the expression of TNF-alpha, interleukin (IL)-6, vascular endothelial growth factor (VEGF), and MMP-9 in the skin of mice with rosacea compared to controls [17], indicating that these proteins are involved in the pathogenesis of the dermatosis. This evidence concerns the gene MMP9 and rosacea.