Cathelicidins are short cationic
peptides initially described as
antimicrobial peptides, which can also modulate the immune system. Because most findings have been described in the context of human LL-37 or murine
CRAMP, or have been investigated under varying conditions, it is unclear which functions are
cathelicidin specific and which functions are general
cathelicidin properties. This study compares 12
cathelicidins from 6 species under standardized conditions to better understand the conservation of
cathelicidin functions. Most tested
cathelicidins had strong antimicrobial activity against E. coli and/or MRSA. Interestingly, while more physiological culture conditions limit the antimicrobial activity of almost all
cathelicidins against E. coli, activity against MRSA is enhanced. Seven out of 12
cathelicidins were able to neutralize LPS and another 7
cathelicidins were able to neutralize LTA; however, there was no correlation found with LPS neutralization. In contrast, only 4
cathelicidins enhanced
DNA-induced TLR9 activation. In conclusion, these results provide new insight in the functional differences of
cathelicidins both within and between species. In addition, these results underline the importance not to generalize
cathelicidin functions and indicates that caution should be taken in extrapolating results from LL-37- or
CRAMP-related studies to other animal settings.