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Educational reference only. Nothing on this page constitutes medical advice or encourages personal use of this compound. Always consult a qualified healthcare provider before any decision involving your health.

LL-37

LL-37 · hCAP18-Derived Peptide · CAMP

C
Animal replicated
RouteTopicalGray-market only
C
Evidence grade: Animal replicated

Effect demonstrated in multiple animal studies; human data sparse or extrapolated. Grades summarize evidence quality, not whether a compound is appropriate, legal, or risk-free.

At a glance
What it is
Cathelicidin / Human Cathelicidin Antimicrobial Peptide / hCAP18-Derived / CAMP — Antimicrobial Peptide, Cathelicidin, Immunomodulatory Peptide.
Why people use it
Used primarily for tissue repair and healing and skin, hair, and cosmetic use.
What the evidence supports
One of the more counterintuitive facts in LL-37 biology: while wound-healing literature treats low LL-37 as a problem to fix, dermatology literature identifies excessive LL-37 as the pathological mechanism of rosacea.
If you only read one thing

LL-37 is the only human cathelicidin — a 37-amino acid endogenous peptide that functions as antimicrobial, wound healer, angiogenic factor, immune modulator, and inflammatory coordinator simultaneously. It has genuine clinical trial evidence in chronic wound healing (venous leg ulcers, diabetic foot ulcers). It cannot develop bacterial resistance. It bridges innate and adaptive immunity in ways no conventional antibiotic can. And it is pro-tumor in ovarian, breast, lung, melanoma, and prostate cancers while being anti-tumor in colon and gastric cancers — the most bidirectional cancer pharmacology in this reference. Community users who take LL-37 for general immune optimization are administering a compound that, depending on whether they harbor any pre-malignant cells in ovary, breast, lung, or skin, may provide immune support or may provide growth signal to nascent tumors. The cancer paradox is not theoretical — it is documented in peer-reviewed oncology literature for multiple cancer types.

Route / form

Same compound, route-specific context. Switch forms instead of opening separate pages.

Evidence fit
Route-specific

Use the route notes below to match form, goal, and evidence quality.

Route caveat
Protocol not standardized

No route-matched protocol rows were parsed for this form; use the route notes and full dosing chapter before comparing options.

Protocol anchor
Full dosing section

Open the full report at the dosing chapter for protocol rows, cycle context, and administration notes.

Typical dose snapshot
See route notes
Evidence varies by use case
Published literature
2human RCTs5human studies5animal5in vitro

Human controlled evidence is topical/local chronic-wound LL-37 data such as venous leg ulcer and diabetic foot ulcer studies; systemic immune or injectable community use is not route-matched RCT evidence.

Evidence reality check
Human evidence
7 human studies
2 randomized; 5 observational.
Preclinical base
10 lab signals
5 animal; 5 in-vitro/mechanistic.
Evidence snapshot
One of the more counterintuitive facts in LL-37 biology: while wound-healing literature treats low LL-37 as a problem to fix, dermatology literature identifies excessive LL-37 as the pathological mechanism of rosacea.
From the chapter quick-reference block.

LL-37 is the only human cathelicidin — a 37-amino acid master coordinator of innate immunity, wound healing, and angiogenesis with genuine clinical trial evidence for topical wound healing and the most complex bidirectional cancer pharmacology of any compound in this reference.

The central tension resolved: LL-37's clinical evidence is real and concentrated in topical wound healing for LL-37-deficient chronic wounds — venous leg ulcers and diabetic foot ulcers. In that context, topical LL-37 is pharmacologically rational, evidence-supported, and well-tolerated. The 6-fold healing rate acceleration in the Grönberg 2014 VLU trial is a genuine and clinically meaningful result. No bacterial resistance development makes LL-37-based wound treatments particularly interesting for MRSA and multi-drug-resistant wound infections. The cancer paradox is the most critical safety issue and requires the most careful treatment: LL-37 is documented as pro-tumor in ovarian, breast, lung, melanoma, and prostate cancers through specific receptor-mediated mechanisms. Systemic injectable LL-37 for immune optimization distributes LL-37 to all tissues simultaneously, including potentially pre-malignant cells in cancer-relevant tissues, without the tissue-specific context control that physiological LL-37 production provides. The rosacea risk from excess LL-37 is real, mechanistically established, and can produce irreversible skin changes.

The practical guidance: the most evidence-supported, safest route to optimizing the cathelicidin arm of innate immunity is vitamin D optimization. Topical LL-37 for genuine LL-37-deficient chronic wound healing is the appropriate clinical application of the compound. Systemic injectable LL-37 for general immune optimization carries risks disproportionate to the evidence base supporting the use.

Properties
Active malignancy: hard stop✓ Human RCTHPTA: suppressiveInjectable: extrapolated
Evidence
CAnimal replicated
The Functional Breadth
LL-37 is not primarily an antimicrobial peptide — it is a multifunctional host defense molecule that happens to kill bacteria. Functions: (1) Direct antimicrobial activity against bacteria (Gram-positive, Gram-negative), fungi, some viruses; (2) Anti-biofilm activity at sub-MIC concentrations; (3) Immunomodulation — modulates neutrophil, macrophage, DC, and lymphocyte behavior; (4) Wound healing — stimulates keratinocyte migration and proliferation, fibroblast activation, angiogenesis via VEGF/FPRL1; (5) Anti-inflammatory — blocks LPS binding to TLR4; (6) Pro-inflammatory (context-dependent) — activates TLR-2 and EGFR; (7) Chemotaxis — recruits neutrophils, monocytes, lymphocytes via FPRL1/FPR2; (8) Antiviral — disrupts lipid-enveloped viruses; neutralizes dsRNA danger signals.
The Cancer Paradox — Critical
LL-37's cancer biology is the most complex and bidirectional of any compound in this reference. PRO-TUMOR (overexpressed and growth-promoting): ovarian cancer; breast cancer; lung cancer; melanoma; prostate cancer. Mechanisms: MSC recruitment via FPRL1; EGFR transactivation; MMP9/CXCL5 induction; angiogenesis. ANTI-TUMOR (suppressive and apoptosis-inducing): colon cancer; gastric cancer. The direction depends on which receptors and signaling pathways the cancer cells express — different receptor landscapes in different cancer types produce opposite outcomes from the same molecule. Active malignancy: ABSOLUTE CAUTION — cannot recommend LL-37 in any active malignancy without oncologist assessment. The pro-tumor evidence in ovarian, breast, lung, and melanoma is substantial.
The Rosacea Paradox
Rosacea is caused by excessive LL-37: kallikrein 5 (skin serine protease) is overactive in rosacea-prone skin, cleaving hCAP18 to LL-37 in excess; excess LL-37 activates TLR-2 on keratinocytes → innate immune cascade → inflammation → rosacea erythema, telangiectasia, papules/pustules. Community users contemplating LL-37 injections for immune support should understand that long-term LL-37 administration in mouse models produces irreversible rosacea-like skin lesions. Individuals with rosacea or rosacea-prone skin: specific caution.
Clinical Trial Evidence
Best human evidence: Grönberg et al. 2014 (Wound Repair and Regeneration): n=34 venous leg ulcer (VLU) patients; DBRPC; 4 weeks topical LL-37 cream; 0.5 mg/mL produced 6x higher healing rate constant vs placebo (p=0.003). HEAL LL-37 Phase IIb (multicenter, DBRPC): positive VLU healing results. Diabetic foot ulcer RCT (Jakarta 2023, Archives of Dermatological Research): positive healing outcomes with topical LL-37 cream. Grade B — multiple small-medium RCTs; topical wound healing is the most evidenced application; no systemic human clinical trial for immune optimization.
Vitamin D Connection
Vitamin D (1,25-dihydroxyvitamin D3) is the most powerful known natural inducer of LL-37 expression in keratinocytes, macrophages, and neutrophils. Vitamin D3 binding to its nuclear receptor (VDR) directly transcribes the CAMP gene (cathelicidin antimicrobial peptide) → hCAP18 → LL-37. This means adequate vitamin D status is prerequisite for optimal endogenous LL-37 production. For community members seeking systemic immune support through the cathelicidin system: optimizing vitamin D levels (target serum 25-OH vitamin D 60-80 ng/mL) is safer, cheaper, and more evidence-supported than exogenous LL-37 injection.
No Bacterial Resistance
LL-37 has not induced resistance in bacteria through more than 30 serial passage experiments — a property unique among antimicrobials. Bacteria cannot easily develop resistance to membrane disruption (a physical-chemical mechanism) in the way they develop resistance to enzyme-inhibiting antibiotics. LL-37 also prevents biofilm formation at concentrations 1/128 of the minimum inhibitory concentration (MIC) — sub-MIC biofilm prevention that conventional antibiotics cannot achieve. These properties make LL-37 specifically interesting for MRSA, multi-drug resistant Gram-negative infections, and chronic biofilm-associated wounds.
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