LL-37

强效两亲性抗菌肽 / 人体固有免疫第一道防线的两亲性抗菌肽：带正电荷并破坏病原体细胞膜，同时趋化免疫细胞、调节炎症反应并促进血管生成以助慢性创面愈合

人体内源性的第一道防线广谱抗菌/抗病毒分子。穿透病原体细胞膜，同时调节组织炎症反应，促进血管生成以修复难愈合的慢性伤口。

Note: This PeptideSCM entry is a related form of the subject; the overview below is from the English Wikipedia article "Cathelicidin antimicrobial peptide".

Cathelicidin antimicrobial peptide (CAMP) is an antimicrobial peptide encoded in the human by the CAMP gene. The active form is LL-37, a 37 amino acid peptide having sequence LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES. In humans, CAMP encodes the peptide precursor CAP-18 (18 kDa), which is processed by proteinase 3-mediated extracellular cleavage into the active form LL-37.

The cathelicidin family includes 30 types of which LL-37 is the only cathelicidin in the human.

Cathelicidins are stored in the secretory granules of neutrophils and macrophages and can be released following activation by leukocytes. Cathelicidin peptides are dual-natured molecules called amphiphiles: one end of the molecule is attracted to water and repelled by fats and proteins, and the other end is attracted to fat and proteins and repelled by water. Members of this family react to pathogens by disintegrating, damaging, or puncturing cell membranes.

Cathelicidins thus serve a critical role in mammalian innate immune defense against invasive bacterial infection. The cathelicidin family of peptides are classified as antimicrobial peptides (AMPs). The AMP family also includes the defensins. Whilst the defensins share common structural features, cathelicidin-related peptides are highly heterogeneous. Members of the cathelicidin family of antimicrobial polypeptides are characterized by a highly conserved region (cathelin domain) and a highly variable cathelicidin peptide domain.

Cathelicidin peptides have been isolated from many different species of mammals, including marsupials. Cathelicidins are mostly found in neutrophils, monocytes, mast cells, dendritic cells and macrophages after activation by bacteria, viruses, fungi, parasites or the hormone 1,25-D, which is the hormonally active form of vitamin D. They have been found in some other cells, including epithelial cells and human keratinocytes. Some viruses evolved immunomodulatory mechanisms to avoid cathelicidin exposure by downregulating the cellular vitamin D receptor.

Source: English Wikipedia, "Cathelicidin antimicrobial peptide".

The general rule of the mechanism triggering cathelicidin action, like that of other antimicrobial peptides, involves the disintegration (damaging and puncturing) of cell membranes of organisms toward which the peptide is active.

Cathelicidins rapidly destroy the lipoprotein membranes of microbes enveloped in phagosomes after fusion with lysosomes in macrophages. Therefore, LL-37 can inhibit the formation of bacterial biofilms.

The pleiotropic properties of LL-37 in relation to the different cells and tissues ^ Kościuczuk EM, Lisowski P, Jarczak J, Strzałkowska N, Jóźwik A, Horbańczuk J, et al. (December 2012). "Cathelicidins: family of antimicrobial peptides. A review". Molecular Biology Reports. 39 (12): 10957–70. doi:10.1007/s11033-012-1997-x. PMC 3487008. PMID 23065264.

^ Dosler S, Karaaslan E (December 2014). "Inhibition and destruction of Pseudomonas aeruginosa biofilms by antibiotics and antimicrobial peptides". Peptides. 62: 32–7. doi:10.1016/j.peptides.2014.09.021. PMID 25285879. S2CID 207359996.