Reduction in serine protease activity correlates with improved rosacea severity in a small, randomized pilot study of a topical serine protease inhibitor

Individuals with rosacea express high baseline levels of cathelicidin and kallikrein 5 (KLK5) (Yamasaki, et al, 2007). The significance of elevated KLK5 is that this trypsin-like serine protease controls the cleavage of the cathelicidin precursor protein into LL-37 (Yamasaki et al, 2007; Yamasaki et al, 2006). LL-37 is both pro-inflammatory and angiogenic (Koczulla et al, 2003; Lande et al, 2004; Morizane et al, 2012). Based on these findings, we hypothesized that inhibition of KLK5 may improve the clinical signs of rosacea by decreasing LL-37 production.