LL-37 5mg

LL-37 kills bacteria by disrupting their membranes through its amphipathic alpha-helical structure -- one face of the helix is hydrophobic, the other cationic. Bacterial membranes are negatively charged due to high phosphatidylglycerol and cardiolipin content, attracting the cationic LL-37. Once bound, the peptide inserts into and permeabilizes the bacterial membrane. Mammalian cell membranes are primarily zwitterionic (net neutral) and are less susceptible to this mechanism, though selectivity is concentration-dependent. High LL-37 concentrations can lyse mammalian cells. Research protocols must account for this concentration-dependent selectivity.

While mice and many other mammals have multiple cathelicidin genes, humans have only one -- the CAMP gene encoding the hCAP-18/LL-37 precursor. The reasons for this reduction to a single cathelicidin in human evolution are not fully understood, but it may relate to immune system specialization in humans toward other defense mechanisms. Despite being alone in its class, LL-37 is expressed at many epithelial surfaces and in immune cells, and its immunomodulatory functions extend well beyond direct antimicrobial killing -- suggesting it has evolved to serve multiple host defense roles that might be distributed across multiple cathelicidins in other species.

LL-37 promotes fibroblast proliferation in cited models through several mechanisms. It stimulates keratinocyte migration and proliferation, promotes angiogenesis through VEGF and FGF receptor activation, modulates the inflammatory phase of fibroblast proliferation in cited models, and has anti-biofilm activity that helps prevent wound infection. These properties have made LL-37 interesting for chronic wound research, where bacterial biofilm formation and dysregulated inflammation often prevent normal healing. Research has also explored LL-37-releasing dressings and scaffolds for wound care applications.