Thai propolis extract at 2.5 mg ml appears to be the most effective dose for preserving the viability of PDL cells, and this was comparable to HBSS.

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.

No abstract