LL-37

In simple words

LL-37 is the only peptide of its family that the human body produces itself to defend against microbes. It is studied as a means against resistant bacteria and for healing chronic wounds.

What this molecule is

LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES — 37 aa. α-helical. C-terminal fragment of hCAP18. The only human cathelicidin. ~4493 Da.

Why it is studied

A key antimicrobial + immunomodulatory peptide of innate immunity. Active against MRSA, MSSA. ↓Chronic wound biofilms. ↑Wound healing (↑angiogenesis, ↑epithelialization). Promising for acne, rosacea, chronic wounds, sepsis.

How it works

Amphipathic α-helix → electrostatic interaction with the bacterial membrane → pore formation → lysis. Immunomodulation: ↑neutrophil/DC chemotaxis, ↓NLRP3/caspase-1/GSDMD (pyroptosis). ↑Skin cell migration → ↑epithelialization.

Doses used in studies

Studies used 5-10 mg topically in a cream/gel; systemically (Research) — 0.5-1 mg SC into the affected area 2-3 times/week.

Combined with in studies

• GHK-Cu — regeneration + antimicrobial
• BPC-157 — deep recovery
• Defensins — innate immunity together

Level of evidence

Level C Animal studies. Effects have been shown in animals. Whether they carry over to humans has not been proven. animals + in vitro. High clinical potential.

Important to know

⚠️ Degraded by skin proteases (short T½). No completed RCTs. Research only.

Studies in PubMed

1. LL-37 improves sepsis-induced acute lung injury by suppressing pyroptosis in alveolar epithelial cells. (Int Immunopharmacol, 2024)
2. The human cathelicidin peptide LL-37 inhibits pancreatic cancer growth by suppressing autophagy and reprogramming of the tumor immune microenvironment. (Front Pharmacol, 2022)
3. The Potential of Human Peptide LL-37 as an Antimicrobial and Anti-Biofilm Agent. (Antibiotics (Basel), 2021)
4. Efficacy of antimicrobial peptide LL-37 against biofilm forming Staphylococcus aureus strains obtained from chronic wound infections. (Microb Pathog, 2022)
5. Therapeutic Potential of Cathelicidin Peptide LL-37, an Antimicrobial Agent, in a Murine Sepsis Model. (Int J Mol Sci, 2020)