Roles of Gingipains in Periodontal Bone Loss

Gingipains are cysteine proteases produced by Porphyromonas gingivalis, one of the major pathogens of periodontitis. They are classified into lysine - specific gingipain (Kgp) and arginine - specific gingipains (Rgps) by the specificity of the proteolytic cutting sites. Gingipains are known to play a major role in the progression of periodontitis by inducing inflammation and tissue destruction in the periodontium, including alveolar bone loss by osteoclasts ; however, the roles of gingipains in osteoclastic bone resorption have not been elucidated yet. Recently, we reported that Kgp but not Rgps and active vitamin D-3\ or microbial components such as lipopolysaccharide (LPS) synergistically induced osteoclast formation and activation in a setting where both osteoblasts and osteoclast precursor cells co - exist. While LPS has been regarded as one of the major factors for osteoclastogenesis and alveolar bone loss in periodontitis, our findings revealed that not only LPS but also Kgp plays a pivotal role in alveolar bone loss in periodontitis.