LL-37

ID: ll37

Aliases: LL-37 antimicrobial peptide, cathelicidin LL-37, CAP18 fragment

Type: compound

Route/form: topical in venous-ulcer human trial; systemic/injectable route is not clinically established

Status: investigational_or_research

Evidence level: human RCT

Best data tier: human controlled/review; exact-use indirect

Support scope: human, non-human/mechanistic, review/regulatory

Source types: human_rct, preclinical, review

Linked sources: 6

Broad outcomes: Gut / immune / inflammation, Muscle growth / performance / recovery, Skin / wound repair

Reading note: These are curation notes anchored to linked sources, not a clinical recommendation or protocol.

Targets / mechanism

• cathelicidin antimicrobial activity
• chemotaxis and immune-cell modulation
• epithelial repair and wound healing
• biofilm/membrane antimicrobial mechanisms
• context-dependent inflammatory signaling

Optimization domains

• wound healing
• skin
• infection
• inflammation
• immune
• antimicrobial
• gut
• barrier
• rosacea

Research basis

• LL-37 has a real human anchor in topical venous-ulcer RCT data, plus broad antimicrobial, epithelial-repair, chemotactic, and immunomodulatory biology in review literature.
• Mechanistically it belongs in the repair/immune bucket because cathelicidin biology spans skin, GI barrier, microbiome interaction, antifungal/antibacterial effects, and tissue repair.
• Derivative and formulation reviews help explain why the field is interested in LL-37 analogs rather than assuming native LL-37 is already a ready-to-use systemic drug.

Limits, risks, and missing evidence

• The positive human evidence is topical wound-context evidence, not proof for systemic injectable wellness or general immune optimization.
• LL-37 can also be pro-inflammatory depending on tissue context, concentration, receptor environment, and disease state; the rosacea model is an important warning against one-way pro-healing framing.
• Native LL-37 has stability, cytotoxicity, production, and delivery problems that motivate analog development.

Risk flags

• context dependent immunology
• pro inflammatory possible
• route specific claims
• topical human anchor
• systemic use unestablished
• antimicrobial resistance context

Linked papers, labels, and reviews

1. Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized placebo-controlled clinical trial
   human_rct / pubmed_ll37_venous_ulcer_rct_2014
   First-in-man topical LL-37 venous leg ulcer trial.
2. The human cathelicidin LL-37: a multifunctional peptide involved in infection and inflammation
   review / pmc_ll37_immunomodulation_review_2005
   Mechanistic review for LL-37 antimicrobial and immunomodulatory biology.
3. LL-37: Cathelicidin-related antimicrobial peptide with pleiotropic activity
   review / pubmed_ll37_pleiotropic_review_2016
   Core LL-37 review covering antimicrobial, chemotactic, immunomodulatory, respiratory, GI, and skin biology; useful mechanism anchor beyond the venous-ulcer RCT.
4. LL-37: Biological Mechanisms and Emerging Therapeutic Applications in Intestinal Disease
   review / pubmed_ll37_intestinal_review_2026
   Intestinal-immune axis review emphasizing context-dependent LL-37 biology, including antibacterial, immunomodulatory, tissue-repair, microbiome, IBD, and CRC considerations.
5. Antimicrobial Peptides of the Cathelicidin Family: Focus on LL-37 and Its Modifications
   review / pubmed_ll37_cathelicidin_modifications_review_2025
   Review of LL-37 and modified cathelicidin analogs; highlights broad antimicrobial/immunomodulatory promise but also proteolytic stability, cytotoxicity, production, and safety barriers.
6. Therapeutic effect of an MRGPRX2/MRGPRB2 antagonist on LL-37-induced rosacea-like inflammation in mice
   preclinical / pubmed_ll37_rosacea_mouse_2025
   Mouse and cell rosacea-like inflammation model where LL-37 acts as a pro-inflammatory trigger through mast-cell/MRGPR biology; important counterweight to only pro-healing framing.