Localization of Cathepsin B and L in Rat Periodontal Tissues During Experimental Tooth Movement

Abstract

Cathepsins are common and well-characterized lysosomal cysteine proteinases involved in tissue destruction under pathological conditions. A recent immunocytochemical study reported that cathepsins B (CAB) and L (CAL) were localized in the periodontal ligament (PDL) of the rat molar. Further, our laboratory demonstrated that the levels of CAB and CAL in gingival crevicular fluid increased during orthodontic tooth movement. The present study focused on the localization of CAB and CAL during experimental tooth movement as well as participation by these cathepsins in the alteration of the periodontal tissues. Tooth movement was performed with the Waldo method, and the time points used for elastic band extraction were 1, 3, and 7 days after tooth movement. To determine localization of CAB and CAL using immunohistochemical analysis was used. Immunoreactivity for CAB and CAL was detected in osteoclasts and PDL fibroblasts. One day after tooth movement, the PDL fiber arrangement became coarse on both sides, and regressive lesions formed while the degree of staining for CAB and CAL increased in those cells as a whole. However, 3 days after tooth movement, many osteoclasts appeared in the compression and tension sides, and the immunoreactivity of CAB and CAL was increased in osteoclasts and fibroblasts. The present study demonstrated that CAB and CAL could be detected in PDL fibroblasts and osteoclasts and were increased in those cells following experimental tooth movement. Therefore, mechanical stress may be involved in extracellular matrix degradation and bone resorption through the stimulation of cathepsins, which is one of the important factors in the periodontal tissues.