4 research outputs found
The Antimicrobial Peptide, LL-37, Inhibits in vitro Osteoclastogenesis
Uncoupled bone resorption leads to net alveolar bone loss in periodontitis.
The deficiency of LL-37, the only human antimicrobial peptide in the
cathelicidin family, in patients with aggressive periodontitis suggests that
LL-37 may play a pivotal role in the inhibition of alveolar bone destruction
in periodontitis. We aimed to investigate a novel function of LL-37 in
osteoimmunity by blocking osteoclastogenesis in vitro. Human osteoclast
progenitor cells were isolated from a buffy coat of blood samples. The cells
were cultured in the presence of various concentrations of LL-37 during an in
vitro induction of osteoclastogenesis. Non-toxic doses of LL-37 could block
multinuclear formation of the progenitor cells and significantly diminish the
number of tartrate-resistant acid-phosphatase-positive cells and the formation
of resorption pits (p < 0.05), whereas these concentrations induced cellular
proliferation, as demonstrated by increased expression of proliferating cell
nuclear antigen. Expression of several osteoclast genes was down-regulated by
LL-37 treatment. It was demonstrated that nuclear translocation of nuclear-
factor-activated T-cells 2 (NFAT2) was blocked by LL-37 treatment, consistent
with a significant reduction in the calcineurin activity (p < 0.005).
Collectively, our findings demonstrate that LL-37 inhibits the in vitro
osteoclastogenesis by inhibiting the calcineurin activity, thus preventing
nuclear translocation of NFAT2. Abbreviations: CALCR, calcitonin receptor;
ClC-7, chloride-proton exchanger; CTSK, cathepsin K; DAPI,
4′,6-diamidino-2-phenylindole; EGTA, ethylene glycol tetraacetic acid; GAPDH,
glyceraldehyde-3-phosphate dehydrogenase; M-CSF/CSF1, macrophage-colony-
stimulating factor; MMP-9, matrix metalloproteinase-9; MTT, [3-(4,
5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]; NFAT2, nuclear
factor of activated T-cells 2; PBS, phosphate-buffered saline; PCNA,
proliferating cell nuclear antigen; PCR, polymerase chain reaction; RANK,
receptor activator of nuclear factor kappa-B; RANKL, receptor activator of
nuclear factor kappa-B ligand; RT-PCR, reverse-transcription polymerase chain-
reaction; TBS, Tris-buffered saline; TCIRG1, T-cell, immune regulator 1,
ATPase, H+ transporting, lysosomal V0 subunit A3; TRAcP, tartrate-resistant
acid phosphatase