Abstract: Objective    To investigate the role of the Caspase-1/gasdermin D（GSDMD）signaling pathway in inflammatory responses and bone destruction of peri-implantitis by establishing a mouse model simulating the progression of peri-implantitis. Methods    The study was conducted in the Central Laboratory of the Affiliated Hospital of Qingdao University from October 2024 to November 2025. Totally eighteen C57BL/6J mice received immediate implantation of mini-implants into extraction sockets. After osseointegration，the mice were randomly divided into three groups：control，ligation，and ligation + Porphyromonas gingivalis（P. gingivalis）groups（n = 6 per group）. The control group received injection of 20 μL phosphate-buffered saline（PBS）into peri-implant tissues. The ligation group underwent subgingival ligation around the implants followed by 20 μL PBS injection，while the ligation + P. gingivalis group received injection of 20 μL heat-inactivated P. gingivalis suspension after ligation. Injections were administered every 48 h for 2 weeks. Micro-CT，hematoxylin-eosin（HE）staining，immunofluorescence staining，RT-qPCR，and Western blot were used to compare the differences in marginal bone height and bone mineral density（BMD）around implants，inflammatory cell infiltration，fibrous tissue hyperplasia and morphological changes in bone tissue，the mean fluorescence intensity of interleukin（IL）-1β and GSDMD in bone tissue，the relative mRNA expression levels of GSDMD，IL-1β，IL-18，receptor activator of nuclear factor-κB ligand（RANKL），osteoprotegerin（OPG），and the ratio of RANKL and OPG（RANKL/OPG）in gingival tissue，as well as the relative protein expression levels of IL-1β，IL-18，cleaved Caspase-1（the active form of Caspase-1），and GSDMD-N（the N-terminal active fragment of GSDMD）in gingival tissue among the three groups. Results    Marginal bone height and bone mineral density（BMD）in the ligation and ligation + P. gingivalis groups were significantly decreased compared with the control group，with more pronounced reduction in the ligation + P. gingivalis group（P < 0.05）. In the control group，the peri-implant tissues around the implant neck were morphologically normal，with no obvious inflammatory cell infiltration. In the ligation group，fibrous tissue hyperplasia and inflammatory cell infiltration were observed around the implant neck. In the ligation + P. gingivalis group，active osteoclasts and osteoblasts were observed on the bone surface，necrotic bone formation was present at the bone interface，and abundant fibrous tissue hyperplasia was observed. The mean fluorescence intensities of GSDMD and IL-1β in the ligation and ligation + P. gingivalis groups were significantly increased compared with the control group，with a more pronounced increase in GSDMD in the ligation + P. gingivalis group（P < 0.05）. The relative mRNA expression levels of IL-1β，IL-18，and RANKL/OPG in the ligation and ligation + P. gingivalis groups were significantly increased，whereas the relative mRNA expression level of OPG was significantly decreased compared with the control group；the increases in IL-18 and RANKL/OPG were more pronounced in the ligation + P. gingivalis group. In addition，the relative mRNA expression levels of GSDMD and RANKL in the ligation + P. gingivalis group were significantly higher than those in the control and ligation groups（P < 0.05）. The relative protein expression levels of IL-1β，IL-18，cleaved Caspase-1，and GSDMD-N in the ligation and ligation + P. gingivalis groups were significantly increased compared with the control group，with greater increase in the ligation + P. gingivalis group（P < 0.05）. Conclusion    This study has successfully established a mouse model of rapidly progressive peri-implantitis. The Caspase-1/GSDMD signaling pathway may be involved in inflammatory responses and bone resorption of peri-implantitis，and may play a role in the occurrence and progression of bone destruction.

Key words: peri-implantitis, pyroptosis, gasdermin D, Porphyromonas gingivalis, bone resorption

摘要： 目的    通过构建能够稳定模拟种植体周炎进展的小鼠模型，探究半胱氨酸天冬氨酸蛋白酶（Caspase）-1/gasdermin D（GSDMD）信号通路在种植体周炎炎症反应与骨破坏中的作用。方法    研究于2024年10月至2025年11月在青岛大学附属医院中心实验室进行。在18只C57BL/6J小鼠拔牙窝内即刻植入微型种植体，骨结合形成后随机分为对照组、结扎组及结扎+牙龈卟啉单胞菌组（每组6只）。对照组种植体周围组织注射20 μL无菌磷酸盐缓冲溶液（phosphate buffered saline，PBS），结扎组丝线环绕种植体龈下打结并注射20 μL无菌PBS，结扎+牙龈卟啉单胞菌组结扎后注射20 μL热灭活牙龈卟啉单胞菌悬液；每48 h注射1次，连续注射2周。分别通过Micro-CT、HE染色、免疫荧光染色、RT-qPCR、蛋白免疫印迹方法比较3组小鼠种植体周围边缘骨高度和骨密度（bone mineral density，BMD），骨组织炎症细胞浸润、纤维组织增生及骨组织形态变化，骨组织白细胞介素（interleukin，IL）-1β、GSDMD的平均荧光强度差异，牙龈组织GSDMD、IL-1β、IL-18、核因子κB受体活化因子配体（receptor activator of nuclear factor-κB ligand，RANKL）、骨保护素（osteoprotegerin，OPG）的mRNA相对表达量和RANKL与OPG的mRNA相对表达量比值（RANKL/OPG），以及牙龈组织IL-1β、IL-18、cleaved Caspase-1（Caspase-1活性形式）、GSDMD-N（GSDMD的N端活化片段）的蛋白相对表达量差异。结果    结扎组和结扎+牙龈卟啉单胞菌组的边缘骨高度和BMD均较对照组明显下降，且结扎+牙龈卟啉单胞菌组下降更明显，差异均有统计学意义（均P < 0.05）。对照组种植体颈部周围组织形态正常，未见明显炎性细胞浸润；结扎组种植体颈部周围可见纤维组织增生及炎性细胞浸润；结扎+牙龈卟啉单胞菌组骨表面可见活跃的破骨细胞与成骨细胞，骨界面处出现死骨形成，并伴大量纤维组织增生。结扎组和结扎+牙龈卟啉单胞菌组GSDMD和IL-1β的平均荧光强度均较对照组明显增加，且结扎+牙龈卟啉单胞菌组的GSDMD平均荧光强度增加更明显，差异均有统计学意义（均P < 0.05）。结扎组和结扎+牙龈卟啉单胞菌组OPG的mRNA相对表达量较对照组明显降低，IL-1β、IL-18的mRNA相对表达量和RANKL/OPG较对照组明显增加，且结扎+牙龈卟啉单胞菌组的IL-18和RANKL/OPG增加更明显；结扎+牙龈卟啉单胞菌组GSDMD和RANKL的mRNA相对表达量较对照组和结扎组明显增加，差异均有统计学意义（均P < 0.05）。结扎组和结扎+牙龈卟啉单胞菌组IL-1β、IL-18、cleaved Caspase-1和GSDMD-N的蛋白相对表达量均较对照组明显增加，且结扎+牙龈卟啉单胞菌组增加更明显，差异均有统计学意义（均P < 0.05）。结论    研究成功建立了小鼠种植体周炎的快速进展模型。Caspase-1/GSDMD信号通路可能参与种植体周炎的炎症反应与骨吸收过程，并在骨破坏的发生发展中发挥作用。

关键词: 种植体周炎, 细胞焦亡, gasdermin D, 牙龈卟啉单胞菌, 骨吸收