Although the role of cathepsin C (Cat C) in inflammation is gradually being elucidated, its function in periapical periodontitis, which is one of the most common infectious diseases worldwide, has not been studied. This study evaluated a surgically-induced model of periapical periodontitis in cathepsin C (Cat C) knock-down (KD) mice, which was constructed with a tetracycline operator, to evaluate the role of Cat C in the pathogenesis and progression of periapical periodontitis. Our results showed, for the first time, that there was a statistically significant increase in the expression of Cat C as periapical periodontitis progressed; this increase started from 1 week after surgery and reached a peak at 3 weeks after surgery, before gradually decreasing. The volume of periapical bone resorption in Cat C KD mice was significantly smaller than that in wild-type mice at 3 and 4 weeks after surgery (P<0.05). Inflammatory cell infiltration into the apical tissues of wild-type mice was also significantly higher than that of Cat C KD mice. The expression of receptor activator of nuclear factor-κB ligand (RANKL) in wild-type mice was also higher than that in Cat C KD mice. The difference in the number of osteoclasts in the apical area between the two groups was statistically significant after 2 weeks. Correlation analysis showed that there was a significant correlation between Cat C and RANKL expression (r= 0.835). Therefore, our data indicated that Cat C promoted the apical inflammation and bone destruction in mice.

尽管组织蛋白酶C（Cat C）在炎症中的作用正在逐步阐明，但尚未研究其在根尖周周炎中的功能，而根尖周炎是全世界最常见的传染病之一。这项研究评估了由四环素操纵基因构建的组织蛋白酶C（Cat C）敲除（KD）小鼠的外科手术诱发的根尖周炎的模型，以评估Cat C在根尖周炎性牙周炎的发病机理和进展中的作用。我们的结果首次显示，随着根尖周牙周炎的进展，Cat C的表达有统计学上的显着增加。这种增加从手术后1周开始，并在手术后3周达到峰值，然后逐渐降低。根尖周骨吸收量 Cat C KD小鼠在术后3周和4周显着小于野生型小鼠（P <0.05）。野生型小鼠的根尖组织中的炎性细胞浸润也显着高于 Cat C KD小鼠。野生型小鼠中核因子-κB配体（RANKL）的受体激活剂的表达也高于 Cat C KD小鼠。两组之间的顶端区域破骨细胞数量的差异在2周后具有统计学意义。相关分析表明，Cat C和RANKL表达之间存在显着相关性（r = 0.835）。因此，我们的数据表明，Cat C促进了小鼠的根尖发炎和骨破坏。