In immature marsupials, because their immune system is underdeveloped at the time of birth,<unk> s play a major role in defense against pathogens. They are produced in the milk of the mother as well as by the young marsupial in question. In human breast milk,<unk> s play a central role in neonate immunity. The human genome contains theta-defensin genes, but they have a premature stop codon, hampering their expression. An artificial human theta-defensin, retrocyclin, was created by 'fixing' the pseudogene, and it was shown to be effective against HIV and other viruses, including herpes simplex virus and influenza A. They act primarily by preventing these viruses from entering their target cells. Also interesting is the effect of alpha-defensins on the exotoxin produced by anthrax (Bacillus anthracis). Chun Kim et al. showed how anthrax, which produces a metalloprotease lethal factor (LF) protein to target MAPKK, is vulnerable to human neutrophil protein-1 (HNP-1). This group showed HNP-1 to behave as a reversible noncompetitive inhibitor of LF. They have generally been considered to contribute to mucosal health; however, it is possible that these peptides can be considered biological factors that can be upregulated by bioactive compounds present in human breast milk. In this sense, the intestinal production of antimicrobial peptides as hBD2 and hBD4 by trefoil from milk might play an important role on neonate colonization, thereby enhancing the immune response of newborns against pathogens with which they may come in contact.
Defensin
Beta defensin
Alpha defensin
Histamine
Major basic protein
Interleukin
Leukotriene
Immunoevasin