LL-37
Human antimicrobial peptide involved in innate immune responses.
Editorial review: August 13, 2026Evidence snapshot
This drawer marks papers. It is not a plan, a dose, or a source. A paper is a bounded report. It is not a protocol. Grades name the object. They are not a safety rating.
Identity lock. LL-37 is the C-terminal antimicrobial peptide released from human cathelicidin hCAP-18 (development synonym ropocamptide). PubChem CID 16198951; formula C205H340N60O53 / MW 4493; CAS 154947-66-7. Distinguish endogenous human biology, in-vitro antimicrobial/immunomodulatory work, and topical venous-leg-ulcer trials of synthetic LL-37 from claims about unlabeled injectable “peptide vials.” No broad approved systemic anti-infective indication. Off-label does not invent a label. This drawer is not an infection-treatment plan.
Bottom line
Endogenous LL-37 biology is well described. A small first-in-human topical venous-leg-ulcer RCT (Grönberg 2014) reported an early healing signal at lower tested strengths. A larger multicenter Phase IIb topical trial (Mahlapuu 2021, HEAL LL-37) did not show significant healing improvement versus placebo in the full analysis population — primary efficacy was not met. Keep both facts visible: early signal does not erase the Phase IIb miss, and the miss does not erase that an early signal was reported. That pattern is the opposite of a general infection-cure narrative. Injectable or systemic “LL-37 vial” efficacy for infection is not established here.
Papers
Topical venous leg ulcers — human trials (synthetic LL-37 object)
PMID 25041740 — Grönberg 2014
Tested: randomized, placebo-controlled first-in-human topical LL-37 for hard-to-heal venous leg ulcers (small n; healing-rate endpoints after a placebo run-in).
Does not show: systemic antimicrobial therapy, diabetic-foot or pressure-ulcer claims, efficacy of a non-trial preparation, or that later Phase IIb confirmed this early signal.
PMID 34687253 — Mahlapuu 2021 (HEAL LL-37, Phase IIb)
Tested: multicentric, prospective, randomized, placebo-controlled Phase IIb topical LL-37 plus compression for hard-to-heal venous leg ulcers.
Does not show: significant healing benefit versus placebo in the full study population (primary efficacy not demonstrated). Post hoc large-wound subgroup findings are not a full-population win. Does not show a systemic infection indication.
Endogenous biology / discovery
PMID 8681941 — Gudmundsson 1996
Tested: cloning/processing context for the human FALL39/cathelin precursor to antibacterial peptide LL-37 in granulocytes.
Does not show: a drug trial. Establishes endogenous identity.
PMID 9452503 — Johansson 1998
Tested: conformation-dependent antibacterial activity of naturally occurring human LL-37 in laboratory systems.
Does not show: clinical treatment efficacy.
PMID 19808939 — Doss 2010
Tested: review of human defensins and LL-37 in mucosal immunity.
Does not show: a new interventional drug trial.
PMID 26434733 — Bandurska 2015
Tested: review of unique features of human cathelicidin LL-37 (structure, biology, dual roles).
Does not show: approved vial therapy.
PMID 30980360 — Wang 2019
Tested: review of antimicrobial-peptide design progress using LL-37 as a template.
Does not show: clinical infection cure rates for exogenous LL-37 products.
Preclinical wound / disease-model context (not vial claims)
PMID 38423213 — Xi 2024
Tested: LL-37 on wound healing in diabetic mice via autophagy-related mechanisms.
Does not show: a human diabetic-wound RCT, or systemic peptide-vial efficacy.
What is not established
A general approved infection-treatment indication for exogenous LL-37. Systemic or injectable “LL-37 peptide” efficacy for pneumonia, sepsis, sinus disease, or skin infection. That the small 2014 VLU signal was confirmed by the later Phase IIb (it was not, in the full population). Equivalence of endogenous LL-37 biology with unlabeled research vials. This drawer does not provide antimicrobial protocols.
Selected sources
25041740 34687253 8681941 9452503 19808939 26434733 30980360 38423213
Reported experiences
Immune function, infection, wound research
Reported topics are not established benefits.Risks and unknowns
Inflammatory or immune effects, unknown systemic safety, product-quality risks
Compare experiences with care.
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