KLK5 and rosacea: For example, activated TLR2 was reported to elevate rosacea-related kallikrein 5 (KLK5), subsequently producing the pro-inflammatory forms of antimicrobial peptide LL37, and LL37 interacts with TLR2 to activate mTOR signaling, eventually inducing the development of rosacea (Deng et al., 2021a; Yamasaki et al., 2007).