Lactoferrin inhibits infection-related osteoclastogenesis without interrupting compressive force-related osteoclastogenesis

Background: Control of periodontal tissue inflammation during orthodontic treatment is very important in achieving a favourable therapeutic goal. We previously demonstrated that orally applied bovine lactoferrin (bLF) inhibited LPS-induced bone resorption but not orthodontic force-induced tooth movement in vivo. This study is designed to examine the underlying mechanism of it. Methods: We examined the inhibitory effects of bLF on the expression of RANKL, OPG, TNF-alpha and COX-2 in osteoblasts loaded with compressive stress (CS) in comparison with LPS stimulated osteoblasts. Formation-of osteoclasts was evaluated by co-culture system. Results: Both CS- and LPS-applications upregulated COX-2 and RANKL but downregulated OPG. TNF-a was upregulated in LPS-stimulated osteoblasts but downregulated in CS-loaded osteoblasts. NS398 (a specific inhibitor of COX-2) significantly inhibited CS-induced RANKL-upregulation but not LPS-induced RANKL upregulation, indicating a critical role of COX-2/PGE(2) pathway in CS-induced osteoclastogenesis. bLF significantly downregulated LPS-induced upregulation of RANKL and eliminated OPG suppression but not affected in CS-induced changes. Moreover, bLF significantly decreased LPS-induced osteoclast formation, whereas bLF had no effect on PGE(2)-induced osteoclast formation. Conclusions: bLF can effectively suppress harmful bone destruction associated with periodontitis without inhibiting bone remodelling by CS-loading. Therefore, oral administration of bLF may be highly beneficial for control of periodontitis in orthodontic patients. (C) 2013 Elsevier Ltd. All rights reserved.