LL-37
Evidence: B — Meaningful Human EvidenceAnti-inflammatory / gut / skin research
Evidence Snapshot
What this grade covers
A for identity; B/C for selected topical wound studies; D/E for systemic infection treatment, immune boosting, generalized wound healing, approval, safety, or dosing.
Regulatory Context
Endogenous human host-defense peptide studied experimentally; no FDA-approved systemic LL-37 medicine was identified.
Research Takeaway
LL-37 is the 37-amino-acid human cathelicidin peptide generated from the hCAP18 precursor; evidence for full-length hCAP18, rodent CRAMP, scrambled controls, shortened analogs, or proprietary LL-37 derivatives must be kept separate.
Evidence boundary: Endogenous peptide biology and the evidence for a manufactured therapeutic preparation are related but not interchangeable.
See all 6 evidence claims →Quick Summary
LL-37 is the 37-amino-acid active human cathelicidin host-defense peptide. Human topical wound trials have evaluated LL-37 formulations, while mechanistic research shows antimicrobial, wound-healing, and context-dependent inflammatory activity. These topical data do not establish safety or efficacy for systemic or injectable use.
Mechanism & Research Overview
LL-37 is a cationic, amphipathic host-defense peptide generated from the hCAP18 precursor. It can disrupt microbial membranes and also modulate chemotaxis, cytokine signaling, cell migration, angiogenesis, and nucleic-acid sensing. Its effects are context-dependent: the same peptide can support wound responses while contributing to inflammatory pathways such as psoriasis.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
LL-37 is the 37-amino-acid human cathelicidin peptide generated from the hCAP18 precursor; evidence for full-length hCAP18, rodent CRAMP, scrambled controls, shortened analogs, or proprietary LL-37 derivatives must be kept separate.
Does not establish
Evidence boundary: Endogenous peptide biology and the evidence for a manufactured therapeutic preparation are related but not interchangeable.
Supported
LL-37 has antimicrobial and immunomodulatory functions and also influences keratinocyte and wound-healing biology, but its immune effects are context-dependent rather than uniformly stimulatory.
Does not establish
Evidence boundary: Broad descriptions such as "immune boosting" oversimplify a peptide that can enhance, suppress, or redirect signaling depending on biological context.
Supported
Topically administered LL-37 has been evaluated in randomized human studies of hard-to-heal venous leg ulcers, providing direct human wound-healing evidence.
Does not establish
Evidence boundary: Evidence for topical chronic-wound use does not establish efficacy for systemic infection, generalized immune enhancement, or injectable use.
Sources: Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial; Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial
Supported
Human clinical investigation has also extended to LL-37-containing topical treatment in diabetic foot ulcers.
Does not establish
Evidence boundary: A wound-specific topical study should not be generalized to unrelated dermatologic, infectious, neurologic, or systemic indications.
Sources: Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer
Supported
LL-37 participates in complex inflammatory and host-defense pathways, and pathology studies have linked LL-37 biology to disease-promoting inflammatory processes in some settings; therefore it should not be characterized as universally protective.
Does not establish
Evidence boundary: Association or mechanistic contribution in a disease model does not prove that exogenous therapeutic LL-37 causes that disease.
Sources: Human antimicrobial peptide LL-37 contributes to Alzheimer's disease progression
Supported
LL-37 earns a higher evidence grade than most experimental peptides in Batch 7 because human randomized topical-wound trials exist, but that evidence remains route- and indication-specific and does not validate systemic research-market uses.
Does not establish
Evidence boundary: Grade B applies to the overall exact-compound evidence base, not to every proposed route or indication.
Sources: Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial; Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial; Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
Topical wound-trial data cannot be generalized to systemic or injectable use.Safety Consideration
LL-37 can form complexes with self-DNA or self-RNA and amplify innate immune signaling in psoriasis-related models.Safety Consideration
FDA identifies immunogenicity, peptide impurity, API-characterization, reproductive, and tissue-specific protumorigenic concerns for compounded LL-37.Safety Consideration
Local reactions increased at the highest concentration in an early topical dose-ranging study.Safety Consideration
Long-term systemic safety is unknown.Safety Consideration
Uncertain sequence, salt, purity, and active-ingredient characterization; sterility and endotoxin risk for any non-topical route; possible cytotoxicity or tissue injury from membrane-disruptive activity at antimicrobial concentrations; unknown cardiovascular, renal, hepatic, neurologic, and hematologic effects; unknown interaction with antibiotics, immunosuppressants, cancer therapy, and autoimmune disease treatment; unknown effects on pregnancy, fertility, fetal development, and lactation. Topical short-term tolerability does not establish injectable or systemic safety.
Research Areas Being Studied
Research areas discussed on this page reflect the Anti-inflammatory / gut / skin research category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer (2023):
- Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial (2021):
- Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial (2014):
- Cathelicidin antimicrobial peptide LL-37 in psoriasis enables keratinocyte reactivity against TLR9 ligands (2012):
- Self-RNA-antimicrobial peptide complexes activate human dendritic cells through TLR7 and TLR8 (2009):
- Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide LL37 in psoriasis (2007):
- LL-37 and Self-RNA-Mediated Inflammatory Signaling ():
- LL-37 as a T-Cell Autoantigen in Psoriasis ():
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer | 2023 | Patients with mildly infected diabetic foot ulcers | The study reported a higher wound-healing rate but did not show reductions in measured inflammatory cytokines or aerobic bacterial counts.
| Small/local study; not evidence for systemic use. | |
| Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: a multicentric prospective randomized placebo-controlled clinical trial | 2021 | Adults with hard-to-heal venous leg ulcers | The phase 2b trial evaluated complete closure and healing outcomes; signals appeared dependent on ulcer size and did not establish broad efficacy.
| Topical trial data cannot be generalized to systemic administration. | |
| Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial | 2014 | 34 adults with hard-to-heal venous leg ulcers | Lower topical concentrations were associated with improved wound-healing-rate measures versus placebo in this small trial.
| Local reactions were more frequent at the highest concentration; topical wound use does not establish safety for systemic or injectable routes. | |
| Cathelicidin antimicrobial peptide LL-37 in psoriasis enables keratinocyte reactivity against TLR9 ligands | 2012 | Human psoriatic skin and keratinocyte models | The study linked elevated LL-37 and TLR9-related signaling in psoriasis. | Supports caution about immune activation; not an administered-treatment study. | |
| Self-RNA-antimicrobial peptide complexes activate human dendritic cells through TLR7 and TLR8 | 2009 | Human immune cells and psoriasis-associated material | LL-37 complexes with self-RNA activated innate immune signaling, illustrating context-dependent pro-inflammatory activity. | Mechanistic human-cell evidence, not clinical dosing evidence. | |
| Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide LL37 in psoriasis | 2007 | Human psoriasis tissue and immune-cell experiments | LL-37–self-DNA complexes activated plasmacytoid dendritic cells, supporting a role in psoriasis pathogenesis. | Mechanistic disease research; not an administered-treatment trial. | |
| LL-37 and Self-RNA-Mediated Inflammatory Signaling | LL-37 can form complexes with self-RNA that stimulate innate immune signaling, contributing to inflammatory and autoimmune biology rather than acting as a simple immune enhancer. This is a distinct source record from the dataset's existing self-DNA (PMID 17873860) and self-RNA/TLR7-8 (PMID 19703986) studies, which carry different PMIDs. | ||||
| LL-37 as a T-Cell Autoantigen in Psoriasis | LL-37 is recognized as a T-cell autoantigen in psoriasis, implicating it in autoimmune pathophysiology and contradicting simplistic claims that more LL-37 is always beneficial. Distinct source record from the dataset's existing PMID 21850017 (keratinocyte/TLR9 reactivity) study. |
Animal / Cell / Preclinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Human antimicrobial peptide LL-37 contributes to Alzheimer's disease progression | 2022 | This work demonstrates that LL-37 can participate in inflammatory/pathologic signaling in an Alzheimer's-disease model context, underscoring that LL-37 is immunologically active rather than a uniformly beneficial antimicrobial peptide. It does not establish clinical toxicity from therapeutic LL-37 use. |
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| FDA summary of identified safety risks for compounded cathelicidin LL-37 | 2026 | FDA states that compounded cathelicidin LL-37 may pose immunogenicity and peptide-impurity/API-characterization risks and that safety information is insufficient for proposed routes. | FDA also cites nonclinical reproductive and tissue-specific protumorigenic concerns; this is compounding-risk context, not a finding that every LL-37 preparation causes those outcomes. | ||
| Efficacy of LL-37 cream for diabetic foot ulcers | 2019 | Patients with diabetic foot ulcers | Official trial registry record associated with topical LL-37 wound research. | ||
| FDA Pharmacy Compounding Advisory Committee Future Meeting Page | FDA has announced that cathelicidin LL-37 is intended for future Pharmacy Compounding Advisory Committee discussion. No meeting date, advisory vote, final listing decision, or favorable FDA action was identified as of the research cutoff (2026-07-30). A future advisory review is not approval and does not establish compounding eligibility. |
Review Articles / Secondary Sources
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| The human cathelicidin LL-37: a pore-forming antibacterial peptide and host-cell modulator | 2016 | Review summarizes antimicrobial membrane activity and diverse host-cell signaling effects. | Secondary overview; does not establish safety or efficacy for unapproved systemic use. | ||
| Emerging roles of the host defense peptide LL-37 in human cancer and its potential therapeutic applications | 2010 | Review describes context-dependent tumor-promoting and tumor-suppressive observations across models. | Secondary source; cancer effects are tissue- and model-dependent. |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Educational information only. This page summarizes published and official research and does not provide medical advice, a recommendation, or instructions for human use.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-07-30.
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