Antimicrobial peptides (First part)

We can defined antimicrobial peptides as a polypeptide antimicrobial substance.

More than hundreds of these peptides are identified in fungi, insects, humans too and they contained between twelve and fifty amino acids whose the majority are hydrophobic.

Their role is very important. Indeed, they innate defense mechanism.

The classification is known in biology : we can find Beta sheet with S-S bonds between cysteine amino acide, alpha helices, or loop structures.

As mentioned before, the antimicrobial peptides have very important functions:

  • They participate in the innate immune system

  • They protect a host of possible invasive microbial infections

  • Innate immune response to adaptative immune system

These peptides can be found in cells-neutrophils, in body fluids-complement proteins. In body secretion such as tears or saliva. Also, in intestinal mucus layer,…

Antimicrobial peptides broad activity vs bacteria, protozoa, viruses HSV-1 & HSV-2, cytotoxic against some cancer cells.

Pareth cells-terminally differentiated, specialized secretory cells located at the base of the crypts of Lierberkühn in the small intestine. They secrete antimicrobials to regulate micro biome:

They secrete granules containing defensine / cryptdins and lysozyme into the lumen. And they maintain gastro-intestinal barrier. For example, they disfunction in intestinal inflammation: we can see this case in the Crohn’s disease for example.

Immunobioly, 7th ed. Janeway and Travers. 2008

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