Characterization and functional analysis of HR-CATH2, a novel anti-septic Cathelicidin from Hoplobatrachus rugulosus

Antimicrobial peptides, including Cathelicidins, are critical components of innate immunity against invasive microbes and have emerged as promising targets for the development of novel antibiotics. However, the current understanding of the anti-inflammatory and antimicrobial aspects of Cathelicidins remains limited. Here, we identified a novel Cathelicidin peptide named by HR-CATH2 from the skin of Hoplobatrachus rugulosus frog. HR-CATH2 consisted of 30 amino acid residues (GRCNLLCKAKKKLRAVGNKIKEIKNVVFNR) with a highly amphipathic α-helix feature. HR-CATH2 could exert its antimicrobial activity via the mechanisms involving ROS accumulation and membrane disruption mode of action within bacteria. Moreover, HR-CATH2 could inhibit overproduction of the pro-inflammatory cytokines (IL-6, IL-1β, TNF-α), and nitric oxide (NO) in RAW264.7 cells by binding LPS and inactivating MAPK signaling. Notably, HR-CATH2 significantly attenuated the acute inflammatory response and mortality in CLP-induced septic mice. Together, our results suggest that HR-CATH2, having LPS-neutralizing, anti-inflammatory and antimicrobial abilities will be a promising therapeutic molecule for the treatment of bacterial infection diseases including sepsis.