Protective effect of melittin against inflammation and
apoptosis on Propionibacterium acnes-induced Human THP-1 monocytic cell
Eur J Pharmacol. 2014 Jul 22. pii: S0014-2999(14)00517-2
Melittin is a cationic, hemolytic peptide that is the main
toxic component in the venom of the honey bee (Apis mellifera). It has been
used in treatment of various chronic inflammatory diseases. However, the
cellular mechanism and the anti-apoptotic effect of melittin in
Propionibactierium acnes (P. acnes)-induced THP-1 cells have not been explored.
In the present study, we investigated the anti-inflammatory and anti-apoptotic
mechanism by examining the effect of melittin on P. acnes-induced THP-1 monocytic
cells. THP-1 monocytic cells were stimulated by heat-killed P. acnes in the
presence of melittin. The expression levels of pro-inflammatory cytokines,
NF-κB signaling, caspase family, and PARP signaling were measured by ELISA or
Western blot analysis. The number of apoptotic cells and changes of cell
morphology were examined using fluorescence microscopy and flow cytometry.
Heat-killed P. acnes increased the secretion of pro-inflammatory cytokines and
cleavage of caspase-3 and -8 in heat-killed P. acnes-induced THP-1 cells.
However, treatment with melittin inhibited the pro-inflammatory cytokines and
cleavage of the caspase-3 and -8. Moreover, the cleaved PARP appeared after 8h
of heat-killed P. acnes treatment and its cleavage was reduced by melittin treatment.
These results demonstrate that 1.0×107 CFU/ml of heat-killed P. acnes-induces
THP-1 cell apoptosis and secretion of inflammatory cytokines. Also,
administration of melittin significantly decreases the expression of various
inflammatory cytokines in heat-killed P. acnes-treated THP-1 monocytic cells.
In particular, melittin exerts anti-apoptotic effects against 1.0×107 CFU/ml of
heat-killed P. acnes injury to THP-1 cells.