Human biology
Endogenous LL-37
LL-37 is derived from the human cathelicidin hCAP18 and participates in antimicrobial defence, cell signalling and inflammation.
Evidence profile · O-014
LL-37: antimicrobial claims, human wound trials and immune risk
Endogenous does not mean simple or safe. LL-37 can kill microbes under some laboratory conditions, but it also changes inflammatory signalling and has produced mixed results in narrow topical wound trials.
LL-37 has real human research, but it does not support general antimicrobial treatment or self-administration claims.
Small topical wound studies reported selected healing signals. A larger 148-patient phase IIb venous-ulcer trial did not meet its primary endpoint in the full population, and its larger-wound signal came from a post hoc subgroup. Laboratory antimicrobial activity and a wound formulation cannot establish systemic benefit or safety.
Object definition
One peptide appears in three very different settings
The human defence peptide, an experimental wound formulation and a consumer vial do not have interchangeable evidence.
Clinical research
Topical ropocamptide
Wound trials tested defined topical preparations alongside standard wound care in selected ulcer populations.
Consumer object
An injectable or nasal vial
Different route, exposure and quality controls make this a different object from a topical clinical formulation.
Human evidence
What the human wound studies found
Human evidence exists, but its route, formulation and outcome boundaries are narrow and the largest result was negative overall.
| Evidence object | What was measured | Defensible reading | Main limit |
|---|---|---|---|
| First-in-human venous-ulcer trial | Healing-rate signals in 34 participants over a short topical treatment phase | Two lower concentrations produced signals that justified a larger trial | Small dose-finding study; the highest concentration did not outperform placebo |
| Phase IIb venous-ulcer trial | Complete healing in 148 treated participants | The defined topical product was tested in a larger multicentre design | Primary endpoint was not met in the full population; larger-wound finding was post hoc |
| Diabetic foot-ulcer trial | Granulation, wound area, inflammatory markers and bacterial colonisation in 25 participants | A small topical study reported selected granulation findings | Small sample and short follow-up cannot establish routine clinical use |
| Immunology literature | LL-37 interactions with cells, cytokines and self nucleic acids | The peptide has antimicrobial and immunomodulatory actions | The same complexity includes pro-inflammatory pathways in psoriasis and lupus |
Evidence quality
The larger trial changes the reading of the small trial
An early positive signal should become less certain when a larger confirmatory study misses its primary endpoint.
The 2014 venous-ulcer study was designed for first-in-human safety and dose response. It included 34 participants and found stronger healing-rate signals at two lower concentrations, while the highest concentration was no better than placebo. This non-linear pattern already argued against a simple more-is-better story.
The 2021 phase IIb study tested two concentrations in a larger multicentre population. It did not show a significant improvement in complete healing overall. A later signal in ulcers larger than 10 square centimetres was post hoc, so it is hypothesis-generating rather than confirmatory.
Product boundary
Antimicrobial activity is only one part of LL-37 biology
LL-37 can disrupt microbial membranes in experimental systems. It can also recruit immune cells, alter cytokine responses and form complexes with self-DNA or RNA. In psoriasis and lupus literature, those complexes are linked to interferon signalling and inflammation.
That does not mean LL-37 causes every autoimmune disease or that a specific product will trigger one. It does mean that marketing it as a natural antibiotic omits material biology. Product identity, aggregation, impurities and route-specific safety require separate evidence.
Endogenous roleAntimicrobial and signalling
Human trialsTopical wound formulations
Largest efficacy resultNegative overall
Systemic useNot established
Decision boundary
What remains unknown
A credible next step would confirm a prespecified wound subgroup and formulation, then report complete safety and clinically important outcomes.
- Whether the larger-ulcer subgroup finding can be reproduced in a new trial.
- Whether any topical benefit improves durable complete healing rather than intermediate wound measures.
- How immune-related harms vary by dose, route, tissue and underlying disease.
- Whether effects seen in selected chronic wounds apply to other infections or injuries.
- The quality, identity and microbiological controls of individual consumer products.
- Whether systemic or nasal administration has an acceptable human benefit-risk profile.
Evidence ledger
Sources and limits
These records define the conclusions on this page. Each citation supports only the proposition stated beside it.
| Source | What it establishes | What it does not establish | Checked |
|---|---|---|---|
| 2014 venous-ulcer trial | A 34-participant topical dose-finding trial reported healing signals at lower concentrations. | It was small, short and did not establish broad clinical use. | 9 Aug 2026 |
| 2021 HEAL LL-37 phase IIb trial | A 148-participant multicentre trial did not meet its primary endpoint in the full population. | A post hoc larger-wound signal requires prospective confirmation. | 9 Aug 2026 |
| 2023 diabetic foot-ulcer trial | A small randomised topical study reported selected granulation and biomarker findings. | Twenty-five participants and short follow-up cannot establish routine treatment. | 9 Aug 2026 |
| LL-37 immunology review | Describes antimicrobial functions and pro-inflammatory self-nucleic-acid complexes in autoimmune disease. | Mechanistic associations do not quantify risk from a specific product. | 9 Aug 2026 |
| MHRA products database | The official route used to check UK medicine authorisation records. | A database search cannot identify the contents or safety of an online vial. | 9 Aug 2026 |
Continue the investigation
Read the connected evidence
- LL-37 and the wider immune claimsCompare gut, inflammation and immune claims without treating mechanisms as clinical outcomes.
- the immunological concerns in contextPlace known biological concerns beside unknown product and route risks.
- how we weigh a failed primary endpointSee why prespecified outcomes outrank post hoc subgroup signals.
- what testing cannot say about immune safetyA batch result cannot establish clinical benefit or a complete safety profile.
Quick answers
Frequently asked questions
Is LL-37 proven to treat infections?
No. Laboratory antimicrobial activity and narrow topical wound trials do not establish general treatment of bacterial, viral or fungal infections.
Has LL-37 been tested in people?
Yes. Defined topical formulations have been studied in venous and diabetic ulcers. These studies do not support systemic or self-directed use.
What did the largest LL-37 trial find?
The 148-participant phase IIb venous-ulcer trial did not meet its primary endpoint in the full population. A larger-wound signal was post hoc.
Is LL-37 safe because the body makes it?
No such conclusion follows. Endogenous LL-37 participates in complex immune signalling, including pathways linked to inflammation in psoriasis and lupus.
Can LL-37 evidence be transferred to an injectable vial?
No. The human trials used defined topical wound formulations. Route, exposure, manufacturing and microbiological controls differ for an injectable product.
What evidence is still needed?
Prospective confirmation of a prespecified topical indication, complete harm reporting and separate studies for any other route or clinical claim are still needed.
Evidence library
Claim-level evidence records
Open the individual records behind this profile. Each record links to the primary and official sources used for its verdict.
Profile-to-record links checked 10 August 2026. These evidence records received named scientific and clinical sign-off on 10 August 2026.
Editorial experience
From our work: how we checked this page
For topical-map item O-014, LL-37: antimicrobial claims and immune risk was checked as a distinct editorial task, not treated as a generic peptide page. We reviewed 5 unique external sources and 8 internal destinations in the page, then checked that the opening answer, headings, source descriptions and linked next steps stayed within the same claim boundary. The count records links in the published page and is not a claim that every source carries equal evidential weight.
Eleni Kiromitis checked study design, biomedical evidence, evidence directness and laboratory context. Dr Stavroula Nikitopoulou checked clinical claims, adverse effects, contraindications, red flags and patient-facing safety wording. Each reviewer stayed within the remit published on the governance page. Yianni Kiromitis retained responsibility for source verification, editorial decisions and correction management.
We did not use patient experience, a personal treatment outcome, seller testimony or an assumed product identity to support this page. The publication did not independently test a vial for this review. Where a page refers to a laboratory result, that result applies only to the named sample, method and attribute. We kept uncertainty beside the conclusion, recorded which source supports each material claim, and checked that the visible review date matches the publication record. A new controlled study, regulator update, corrected source, analytical report or credible safety signal can trigger reassessment through the public correction route.