LL-37 5 mg

LL-37 5 mg research-grade lyophilized peptide powder in a glass vial. LL-37 is the only known human cathelicidin antimicrobial peptide (hCAP18) and a key effector of the innate immune system, widely used in models of antimicrobial defense, biofilm disruption, wound healing and immunomodulation.

Research Overview

LL-37 is a 37-amino-acid fragment of the human cathelicidin precursor hCAP18 and a broad-spectrum antimicrobial peptide. In experimental systems it is used as a tool compound to study innate immune defense, host–pathogen interactions, barrier function and tissue repair.

Primary Research Areas

• Innate immunity & antimicrobial activity: models exploring host defense against bacteria, viruses and fungi, including membrane disruption and pathogen killing [1].
• Biofilm disruption: in-vitro systems studying LL-37 effects on bacterial biofilms and persistence phenotypes [2].
• Wound-healing & barrier repair: keratinocyte and epithelial models focused on re-epithelialization, migration and tissue regeneration [3].
• Immunomodulation: investigations of chemotaxis, cytokine signaling and LL-37’s dual pro-/anti-inflammatory effects in immune-cell assays [4].
• Rosacea flushing and bumps: people with rosacea carry abnormally high amounts of this peptide in facial skin, and in a chopped-up form that healthy skin does not make. Injecting those rosacea forms into mouse skin caused inflammation, while mice bred without the peptide did not inflame. The finding concerns inflamed facial skin in rosacea [5].
• Psoriasis and self-attack: in human immune-cell experiments the peptide grabs the body’s own DNA and turns it into an alarm signal, switching on interferon production that normally only viruses trigger. The authors identify it as the key driver of this reaction in psoriasis. It can start an autoimmune response, not only fight germs [6].
• Feeding ovarian tumours: in mice carrying human ovarian tumour grafts, blocking the peptide cut the number of stem-like stromal cells drawn into the tumour and shrank tumour growth along with its blood-vessel network. It is overproduced in ovarian, breast and lung cancers. Adding more may not be harmless where a tumour exists [7].
• Clogged arteries in mice: the mouse version of this peptide behaved as a self-target in atherosclerosis-prone mice: a low immunising dose reduced plaque, but a higher dose made the disease worse with more neutrophils packing the plaques. Mice and a mouse look-alike peptide only, and the direction depended entirely on dose [8].

References

1. Turner J, Cho Y, Dinh NN, et al. Activities of LL-37, a cathelin-associated antimicrobial peptide of human neutrophils. Antimicrob Agents Chemother. 1998;42(9):2206-14. PMID 9736536. doi:10.1128/AAC.42.9.2206
2. Overhage J, Campisano A, Bains M, et al. Human host defense peptide LL-37 prevents bacterial biofilm formation. Infect Immun. 2008;76(9):4176-82. PMID 18591225. doi:10.1128/IAI.00318-08
3. Mahlapuu M, Sidorowicz A, Mikosinski J, et al. Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial. Wound Repair Regen. 2021;29(6):938-950. PMID 34687253. doi:10.1111/wrr.12977
4. De Yang, Chen Q, Schmidt AP, et al. 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. J Exp Med. 2000;192(7):1069-74. PMID 11015447. doi:10.1084/jem.192.7.1069
5. Yamasaki K, Di Nardo A, Bardan A, et al. Increased serine protease activity and cathelicidin promotes skin inflammation in rosacea. Nat Med. 2007;13(8):975-80. PMID 17676051. doi:10.1038/nm1616
6. Lande R, Gregorio J, Facchinetti V, et al. Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide. Nature. 2007;449(7162):564-9. PMID 17873860. doi:10.1038/nature06116
7. Coffelt SB, Marini FC, Watson K, et al. The pro-inflammatory peptide LL-37 promotes ovarian tumor progression through recruitment of multipotent mesenchymal stromal cells. Proc Natl Acad Sci U S A. 2009;106(10):3806-11. PMID 19234121. doi:10.1073/pnas.0900244106
8. Mihailovic PM, Lio WM, Yano J, et al. The cathelicidin protein CRAMP is a potential atherosclerosis self-antigen in ApoE(-/-) mice. PLoS One. 2017;12(11):e0187432. PMID 29091929. doi:10.1371/journal.pone.0187432