Defenses That Are Very Similar and Very Different

Organisms have an innate immunity, or an inborn immunity, which protects against microorganism invasion.  As a part of this defense, the host defense peptides (HDPs) are promising alternatives to antibiotics, given that they have a multitude of options in fighting against a variety of bacteria, envelope viruses, fungi, spirochetes, and mycobacteria.  The cathelicidins are a family with the HDPs and not only do they stop the spread of these invaders, they also bolster the immune system.  In humans, LL-37 is currently the only known cathelicidin, however, four have been discovered in chickens and 11 have been identified in pigs.  As a result of past widespread antibiotic abuse, the livestock industry has had to look for new options in keeping their herds healthy.  Perhaps the cathelicidins will be the answer. 

In a new Nature Scientific Reports publication, a team, led by Maaike R. Scheenstra out of Utrecht University in the Netherlands, has tested three cathelicidins, human LL-37, chicken CATH-2, and pig myeloid antibacterial peptide 36 (PMAP-36).  All three effectively destroy e. coli and also differ in their modes of action.   Of the three, PMAP-36 was the most efficacious.  Lipopolysaccharide (LPS) is a large component of the bacterial cell wall and all three peptides caused disruption in LPS-induced macrophage activation, with LL-37 being the most successful.  The importance of the cysteine in PMAP-36 was evaluated for its significance and it was found that the formation of a dimer seemed to play a critical role in its immunomodulatory activity.  Read more about this interesting work in the reference below.1


  1. M.R. Scheenstra et al., Scientific Reports, 9, 4780 (2019).


Peptides International is pleased to offer LL-37 and CATH-2.  For a custom synthesis of PMAP-36 or any other projects, please contact us.


Industry News , Biologically Active Peptides

Denise Karounos

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Denise Karounos joined Peptides International in October 2016. After completing her BS in chemistry from West Virginia University, she spent time as an organic chemist at Bachem Bioscience synthesizing peptides and amino acid derivatives. Denise has experience with both solid and solution-phase peptide synthesis, and has worked under both research and cGMP settings. After completion of her MBA at Saint Joseph’s University, Denise transitioned into product management of peptides and amino acid derivatives. Denise has spent her time at PI focusing on both sales and marketing, including quoting, product management, market research and sales analysis, generating technical marketing content, and attending industry conferences.