Chitosan oligosaccharide promotes osteoclast formation by stimulating the activation of MAPK and AKT signaling pathways

Chitosan Oligosaccharide (COS) has been widely used for the systemic treatment of clinical diseases such as bone tissue engineering. However, its influence on osteoclast formation, which plays a critical role in bone homeostasis, has never been investigated. The aim of this study was to investigate the effect of chitosan oligosaccharide on differentiation of osteoclast. Using cell counting kit-8, tartrate-resistant acid phosphatase staining, reverse transcription-quantitative polymerase chain reaction assay and western blot analysis, we demonstrated that chitosan oligosaccharide cannot inhibit RANKL-inducedosteoclast precursor proliferation but does promote osteoclast differentiation by stimulating the activation of p38/mitogen-activated protein kinase(MAPK), c-Jun N-terminal kinase (JNK)/MAPK, extracellular signal-regulated kinase (ERK)/MAPK and protein kinase B (AKT) without affecting nuclear factor kappaB (NF-kB)signaling pathways. Based on the promoting effect of chitosan oligosaccharide on osteoclast differentiation, we suggest that this property of chitosan oligosaccharide may have potential detrimental effect on bone homeostasis.