LL-37
Published research and evidence base
LL-37 is the sole human cathelicidin antimicrobial peptide, a 37-residue amphipathic alpha-helical peptide released by proteolytic cleavage of the hCAP18 precursor encoded by the CAMP gene. It is expressed by neutrophils, monocytes and epithelial cells, transcriptionally induced by 1,25-dihydroxyvitamin D3, and acts through direct membrane permeabilisation of microbes, neutralisation of lipopolysaccharide, and receptor-mediated chemotaxis and immunomodulation. Its biological effect is strongly concentration- and context-dependent, and elevated LL-37 is implicated as a pathogenic driver in rosacea, psoriasis and atherosclerosis as well as a host-defence effector. The great majority of the literature is in vitro or animal work; human interventional data are limited to a small number of topical and oral formulations.
- Studies cited
- 17
- Published 2023+
- 13
- Newest paper
- 2026
- Last reviewed
- Aug 2026
Recurring themes in the literature
- antimicrobial and antibiofilm activity
- vitamin D-driven CAMP gene induction
- LPS neutralisation
- chemotaxis via FPR2/FPRL1
- wound healing and angiogenesis
- rosacea and psoriasis inflammation
- antiviral activity
- neutrophil extracellular traps
- atherosclerosis autoantigen
- engineered LL-37 analogues and ceragenins
Compound identifiers
- CAS
- 154947-66-7
- PubChem
- 16198951
What LL-37 is, chemically.
- Molecular formula
- C205H340N60O53
- Molecular weight
- 4493 g/mol
- CAS number
- 154947-66-7
- PubChem CID
- 16198951
ropocamptide, Cap-18, cathelicidin LL-37
These figures come from the PubChem record for this compound and describe the free base. Lyophilised peptide is normally supplied as an acetate or trifluoroacetate salt and carries residual water, so the mass of powder in a vial is not the same quantity as the molecular weight above would suggest. Chromatographic purity on a certificate of analysis does not resolve that difference either — how to read a certificate of analysis explains why.
17 published studies.
Ordered by strength of study design, then by recency. Every entry links to its source record so the finding can be checked against the paper rather than taken on our word.
- 01Systematic review2026
Cathelicidin antimicrobial peptides: current progress and future prospects in immunotherapy
Ding A, et al. · Developmental and Comparative Immunology · Systematic review of cathelicidin structure, biology and clinical translation
The review catalogued the molecular structure, cellular sources and mechanisms of cathelicidin peptides and their progress toward clinical application in infectious and non-infectious disease. The authors noted that limitations of current candidates constrain translation despite growing interest driven by antibiotic resistance.
- 02Human clinical2026
LL-37-ApoB-100 Complex Serves as a Biomarker of Coronary Artery Disease
Fang Y, et al. · Arteriosclerosis, Thrombosis, and Vascular Biology · Observational case-control study, 1103 patients undergoing coronary angiography across two independent centres, with supporting surface plasmon resonance and Apoe-/- mouse work
Circulating LL-37-ApoB-100 complex correlated with angiographic disease severity (Gensini score r = 0.60) and discriminated obstructive coronary artery disease with an AUC of 0.82. Elevated levels remained an independent predictor after adjustment for lipid and clinical measures (adjusted OR 6.51, 95% CI 4.34 to 9.77).
- 03Human clinical2026
Adaptive immune response to the autoantigen LL-37 differentiates atherosclerotic cardiovascular disease phenotypes
Dimayuga PC, et al. · Clinical & Translational Immunology · Observational immunophenotyping study of PBMCs and plasma from patients with stable atherosclerotic cardiovascular disease after myocardial infarction, stroke or peripheral artery disease
LL-37 provoked an increased CD4+CD25+CD134+ T-cell response in post-myocardial-infarction patients while CD8+ responses were reduced in peripheral artery disease. LL-37 IgG immune complexes were elevated across disease phenotypes and cross-reacted with native LDL only in post-infarction plasma.
- 04Human clinical2023
Efficacy and safety of Oral LL-37 against the Omicron BA.5.1.3 variant of SARS-COV-2: A randomized trial
Zhao Y, et al. · Journal of Medical Virology · Open-label randomised placebo-controlled single-centre trial, 238 adult COVID-19 inpatients, recombinant LL-37 Lactococcus lactis oral formulation
Oral LL-37 shortened SARS-CoV-2 RNA negative conversion time relative to placebo (9.80 +/- 2.67 versus 14.04 +/- 5.89 days, p < 0.01) when started within six days of confirmation. Benefit was concentrated in early treatment, with an adjusted hazard ratio of 6.28 (95% CI 3.63 to 10.85) versus later initiation.
- 05Human clinical2023
Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer: a randomized double-blind controlled trial
Miranda E, et al. · Archives of Dermatological Research · Randomised double-blind placebo-controlled trial, mildly infected diabetic foot ulcers, topical LL-37 cream twice weekly for 4 weeks (NCT04098562)
The granulation index increased more in the LL-37 arm at days 7, 14, 21 and 28 (p = 0.031, 0.009, 0.006 and 0.037). LL-37 cream did not significantly reduce IL-1alpha, TNF-alpha or aerobic bacterial colonisation compared with placebo.
- 06Human clinical2021
Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial
Mahlapuu M, et al. · Wound Repair and Regeneration · Phase IIb double-blind randomised placebo-controlled trial (HEAL LL-37), 148 patients with hard-to-heal venous leg ulcers, topical LL-37 at 0.5 or 1.6 mg/mL
Efficacy analysis across the full cohort found no significant improvement in healing with LL-37 versus placebo. A post-hoc subgroup with wounds of at least 10 cm2 showed improvement across several healing parameters, and the drug was well tolerated at both dose strengths.
- 07Animal in vivo2026
Serine protease HtrA promotes Campylobacter jejuni intestinal colonization through degrading antimicrobial peptide LL-37
Li X, et al. · Science Advances · Campylobacter jejuni bacterial genetics with mouse intestinal colonisation experiments
LL-37 exposure activated the regulator NssR, upregulating htrA, whose secreted protease cleaved LL-37 at the Ile20-Val21 site and abolished antimicrobial activity. A non-cleavable LL-37 variant showed enhanced antibacterial activity and promoted bacterial clearance in mice.
- 08Animal in vivo2026
Immunomodulatory Effects of Poly-D,L-Lactic Acid on LL-37-Driven Rosacea-like Inflammation via Suppression of mTORC1 Signaling
Byun KA, et al. · International Journal of Molecular Sciences · LL-37-injected mouse model of rosacea-like cutaneous inflammation
LL-37 injection reduced IL-10 and pSTAT3 while increasing TLR2/KLK5/LL-37 amplification, NF-kappaB, VEGF and NLRP3 inflammasome signalling, reproducing rosacea-like disease. Poly-D,L-lactic acid partially restored the STAT3/DDIT4-AMPK pattern, suppressed mTORC1 and reduced lesion area.
- 09Animal in vivo2025
A pilot study of healing critical-sized calvarial defects by LL-37-generated monoosteophils
Le K, et al. · Frontiers in Bioengineering and Biotechnology · Critical-sized calvarial defect model using monoosteophils differentiated from monocytes by LL-37
LL-37-generated monoosteophils formed intracellular hydroxyapatite-containing nodules confirmed by SEM/EDS and filled large calvarial defects in a pilot experiment. The authors reported that bone repair function required hydroxyapatite formation within the cells.
- 10Animal in vivo2024
Cathelicidin LL-37 promotes wound healing in diabetic mice by regulating TFEB-dependent autophagy
Xi L, et al. · Peptides · Diabetic mouse wound model with HaCaT keratinocyte experiments under high glucose
LL-37 accelerated wound closure in diabetic mice, and the effect was reversed by the autophagy inhibitor 3-MA. Mechanistically LL-37 drove nuclear translocation of TFEB and upregulation of ATG5, ATG7 and beclin 1, and TFEB knockdown abolished the promotion of keratinocyte migration.
- 11In vitro2026
Human cathelicidin peptide LL-37 compacts nucleic acids and alters neutrophil extracellular trap structure
Zielke C, et al. · Scientific Reports · Biophysical study of LL-37 with nucleic acids and isolated neutrophil extracellular traps
LL-37 condensed double-stranded DNA into particles of roughly 150 nm through electrostatic interaction between its cationic side chains and the phosphodiester backbone, a process requiring the peptide's amphipathic alpha-helical structure. High LL-37 concentrations significantly reduced projected NET area.
- 12In vitro2026
LL-37 Inhibits EV71 Infection by Upregulating STAC via the EGFR-ERK Signaling Pathway
Zhang J, et al. · Viruses · Cell culture models of enterovirus 71 infection with transcriptomics and shRNA knockdown
LL-37 suppressed enterovirus 71 protein expression and infectious titres, acting predominantly after viral entry. The effect was mediated by EGFR-ERK-dependent upregulation of the SH3 and cysteine-rich domain protein Stac, since Stac silencing enhanced infection and overexpression reduced it.
- 13In vitro2008
Human host defense peptide LL-37 prevents bacterial biofilm formation
Overhage J, et al. · Infection and Immunity · Pseudomonas aeruginosa biofilm assays with microarray transcriptomics
LL-37 inhibited biofilm formation and disrupted pre-grown Pseudomonas aeruginosa biofilms at concentrations far below its minimum inhibitory concentration of 64 microgram/mL. It acted by reducing bacterial attachment, stimulating twitching motility and downregulating the Las and Rhl quorum-sensing systems.
- 14In vitro2004
Cutting edge: 1,25-dihydroxyvitamin D3 is a direct inducer of antimicrobial peptide gene expression
Wang TT, et al. · Journal of Immunology · Human keratinocytes, monocytes, neutrophils and cell lines
The CAMP and defensin beta 2 genes were shown to contain consensus vitamin D response elements mediating 1,25(OH)2D3-dependent transcription, with synergistic induction by LPS in neutrophils. Treated cells secreted increased antimicrobial activity against pathogens including Pseudomonas aeruginosa.
- 15In vitro2000
LL-37, the neutrophil granule- and epithelial cell-derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) as a receptor to chemoattract human peripheral blood neutrophils, monocytes, and T cells
De Yang, et al. · Journal of Experimental Medicine · Human monocytes, neutrophils and T cells plus FPRL1-transfected HEK293 cells
LL-37 was chemotactic for human monocytes, neutrophils and T lymphocytes and induced calcium mobilisation in FPRL1-transfected cells, an effect cross-desensitised by an FPRL1-specific agonist. This established a receptor-mediated immunological role for LL-37 distinct from direct microbicidal killing.
- 16Review2026
LL-37: Biological Mechanisms and Emerging Therapeutic Applications in Intestinal Disease
Liu Q, et al. · Immunity, Inflammation and Disease · Narrative review of LL-37 in the intestinal immune axis
The review described LL-37 as maintaining intestinal homeostasis through antibacterial, immunomodulatory and tissue-repair functions whose direction depends on peptide concentration, receptor binding, disease stage and local microenvironment. It set out the conditions under which LL-37 activity converts from protective to pathogenic in inflammatory bowel disease and colorectal cancer.
- 17Review2026
Exploring the role of cathelicidin LL-37 and ceragenins in wound healing processes
Łuckiewicz M, et al. · European Journal of Pharmacology · Narrative review of antimicrobial peptides and synthetic ceragenin analogues in wound healing
The review summarised mechanisms by which LL-37 and ceragenins support healing, including antimicrobial action preventing infection and promotion of cell migration and proliferation. It framed these agents as candidates for chronic wound and hypertrophic scar management rather than as established therapies.
What this evidence does not establish.
There is no approved LL-37 product and no human data on systemic or injectable administration; the only controlled human trials use topical or oral formulations, and the largest of these, the phase IIb HEAL LL-37 venous leg ulcer trial, was negative on its primary analysis. LL-37 is simultaneously implicated as a pathogenic driver in rosacea, psoriasis and atherosclerosis, so its concentration- and context-dependent switch between protective and inflammatory behaviour is not adequately characterised, and human pharmacokinetics, dose-response and long-term safety are unestablished.
Common questions about the research.
- What is LL-37?
LL-37 is the only human cathelicidin-derived antimicrobial peptide. It is cleaved from the precursor protein hCAP-18, which is stored in neutrophil granules and expressed by epithelial cells, and is named for its two leading leucine residues and 37-amino-acid length.
- Is LL-37 an antibiotic?
It is described in the literature as a host-defence peptide with direct membrane-disrupting activity against bacteria, which is not the same as a clinical antibiotic. No LL-37 product is approved as an anti-infective anywhere, and the research material on this page is not supplied or intended for treating infection.
- How does LL-37 differ from KPV?
Both appear in inflammation and barrier-tissue research, but they are structurally unrelated. LL-37 is a 37-amino-acid cationic helix derived from human cathelicidin and studied for membrane and host-defence activity; KPV is the tripeptide C-terminal fragment of alpha-MSH studied for melanocortin-pathway signalling.
Available from our catalog
For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice, and no study summarised here should be read as a recommendation.