LL-37 is a natural protein that helps fight infections and calm down inflammation. During severe infections like sepsis, its levels in the blood change a lot, and giving extra LL-37 to mice with sepsis helped them live longer. Scientists think that making stable versions of LL-37 could become a new way to diagnose or treat sepsis, but it’s still early‑stage research.

Antimicrobial peptides, which function as the first line of host immune defense, have recently been identified as important immunomodulators of inflammation, and are involved as regulatory molecules in infections, including sepsis. Treatment of sepsis is very complex and remains largely challenging and sometimes ineffective. This creates a need to develop new therapeutic strategies focusing not only on the elimination of sepsis-causing microorganisms, which can be achieved with antibiotics, but also on the control of the immune system and its overactive response resulting in increased vascular endothelial permeability. One approach to develop new treatments for patients with sepsis is to better understand the pleiotropic function of the human LL-37 peptide that originates from the human cathelicidin antibacterial protein (h-CAP18). An increasing number of studies indicate high dynamics of changes in LL-37 concentration in the blood during sepsis. Additionally, in animal models, administration of exogenous LL-37 peptide to mice with experimentally induced sepsis increases their survival. It can therefore be assumed that knowledge of the molecular mechanism of cathelicidin LL-37 action, as well as the synthesis of its stable analogs, will result in progress in the diagnosis and therapy of sepsis.