LL-37
Cathelicidin LL-37
LL-37 is a peptide people usually talk about for Infections: Potential treatment for various bacterial, fungal, and viral infections, especially those resistant to conventional antibiotics. and Wound Healing: Application in chronic, non-healing wounds, such as diabetic foot ulcers.. It is still in the FDA review process, so people are watching both the research and the access question closely.
Why does this matter?
LL-37 matters because a lot of people hear about it online without a clear sense of what it may actually help with. This page gives you the plain-English version first, then shows where the research is strongest, what is still uncertain, and where the peptide stands in the FDA review process.
Molecular weight
Approximately 4.5 kDa.
Molecular formula
Not specified in the source research
Amino acid count
37
Review date
Before February 2027
Sequence / structure
37 amino acids starting with two leucines (LL) (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES).
Other names
LL-37, Cathelicidin, CAMP (Cathelicidin Antimicrobial Peptide), hCAP-18 (precursor protein), FALL-39 (an earlier identified fragment)
Status
Under FDA review for antimicrobial and infection-related use
LL-37 is one of the body’s own built-in defense peptides, which is why people often describe it as a natural antibiotic. It helps the immune system fight bacteria, fungi, and some viruses while also supporting wound healing and recovery in infected or irritated tissue. That makes it especially compelling for people looking at immune defense, chronic wounds, and hard-to-clear infections.
The quick version before the deep dive
- •People usually talk about LL-37 for Infections: Potential treatment for various bacterial, fungal, and viral infections, especially those resistant to conventional antibiotics. and Wound Healing: Application in chronic, non-healing wounds, such as diabetic foot ulcers..
- •Wound Healing: Application in chronic, non-healing wounds, such as diabetic foot ulcers.
- •LL-37 primarily targets and disrupts the cell membranes of pathogens. Its amphipathic alpha-helical structure allows it to insert into microbial lipid bilayers, leading to pore formation, membrane lysis, and cell death.
- •Helps regulate the inflammatory response by inducing the release of chemokines, promoting cell migration (chemotaxis) of immune cells to the site of infection, and neutralizing endotoxins (like LPS).
Deep Dive: Mechanism of Action +
Membrane Disruption: LL-37 primarily targets and disrupts the cell membranes of pathogens. Its amphipathic alpha-helical structure allows it to insert into microbial lipid bilayers, leading to pore formation, membrane lysis, and cell death.
Immunomodulation: Modulates the inflammatory response by inducing the release of chemokines, promoting cell migration (chemotaxis) of immune cells to the site of infection, and neutralizing endotoxins (like LPS).
Wound Healing: Promotes angiogenesis and re-epithelialization, which are critical steps in the wound healing process.
Anti-biofilm Activity: Potent activity against the formation of bacterial biofilms and can also degrade existing biofilms.
Where people usually see it discussed
Investigated Applications +
- Infections: Potential treatment for various bacterial, fungal, and viral infections, especially those resistant to conventional antibiotics.
- Wound Healing: Application in chronic, non-healing wounds, such as diabetic foot ulcers.
- Skin Conditions: Investigated for its role in inflammatory skin diseases and infections.
- Respiratory Infections: Potential therapy for cystic fibrosis and other lung conditions complicated by chronic infections.
- Biofilm-related Infections: Addressing persistent infections associated with medical devices or chronic wounds where biofilms are present.
Formal evidence and study snapshots
Deep Dive: Clinical Trials +
Various clinical trials have investigated LL-37 and its derivatives. Trials have explored topical applications for chronic wounds (e.g., venous leg ulcers), potential in treating skin conditions, and evaluating its immunomodulatory effects in different disease models.
Clinical researchAntimicrobial and infection-related use
Various clinical trials have investigated LL-37 and its derivatives. Trials have explored topical applications for chronic wounds (e.g., venous leg ulcers), potential in treating skin conditions, and evaluating its immunomodulatory effects in different disease models.
What the current safety discussion looks like
- ✓As an endogenous human peptide, LL-37 is generally considered to have a favorable safety profile when present at physiological levels. In therapeutic applications, potential issues include local irritation or systemic inflammatory responses if administered at inappropriate concentrations. Excessive levels of LL-37 have been implicated in the pathogenesis of certain inflammatory conditions like rosacea.
How the status timeline currently reads
Current status
Currently, LL-37 is broadly classified as an unapproved research chemical or investigational drug. It is listed under FDA Category 2 and is scheduled for an advisory committee review in February 2027 to assess its safety and potential clinical applications.
How dosing is usually described
Typical Research Protocols
Often administered subcutaneously or topically in research settings. Dosages vary significantly depending on the target condition and study design.
Research protocols only. Not medical advice.
The citations behind the page
Deep Dive: Key Research Papers +
- 1
Nijnik A, Hancock RE. "The roles of cathelicidin LL-37 in immune defences and novel clinical applications." 2009.
- 2
Wang G. "Human antimicrobial peptides and proteins." 2014.
- 3
Gombart AF. "The vitamin D-antimicrobial peptide pathway and its role in protection against infection." 2009.
- 4
Overhage J, et al. "Human host defense peptide LL-37 prevents bacterial biofilm formation." 2008.
Common questions about LL-37
What is LL-37? +
LL-37 is Cathelicidin LL-37, one of the peptides currently under review in connection with antimicrobial and infection-related use.
What is LL-37 being reviewed for? +
The current advisory review focuses on antimicrobial and infection-related use, with a listed review date of Before February 2027.
Which category does LL-37 belong to? +
LL-37 is grouped in this library under Healing.
How many amino acids are in LL-37? +
LL-37 is presented here as a 37-amino-acid peptide or peptide analog based on the source research and naming conventions.
What is the sequence or structure note for LL-37? +
37 amino acids starting with two leucines (LL) (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES)..
What research applications are most associated with LL-37? +
Infections: Potential treatment for various bacterial, fungal, and viral infections, especially those resistant to conventional antibiotics., Wound Healing: Application in chronic, non-healing wounds, such as diabetic foot ulcers., Skin Conditions: Investigated for its role in inflammatory skin diseases and infections., and Respiratory Infections: Potential therapy for cystic fibrosis and other lung conditions complicated by chronic infections.
How is LL-37 described as working in the current research? +
LL-37 primarily targets and disrupts the cell membranes of pathogens. Its amphipathic alpha-helical structure allows it to insert into microbial lipid bilayers, leading to pore formation, membrane lysis, and cell death. Helps regulate the inflammatory response by inducing the release of chemokines, promoting cell migration (chemotaxis) of immune cells to the site of infection, and neutralizing endotoxins (like LPS).
How is LL-37 usually discussed in protocols or treatment plans? +
LL-37 is most often described with typical research protocols protocols in the source material.
What does the safety discussion say about LL-37? +
As an endogenous human peptide, LL-37 is generally considered to have a favorable safety profile when present at physiological levels. In therapeutic applications, potential issues include local irritation or systemic inflammatory responses if administered at inappropriate concentrations. Excessive levels of LL-37 have been implicated in the pathogenesis of certain inflammatory conditions like rosacea.
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