Osteoblasts express NLRP3, a nucleotide-binding domain and leucine-rich repeat region containing receptor implicated in bacterially induced cell death
Osteoblasts express NLRP3, a nucleotide-binding domain and leucine-rich repeat region containing receptor implicated in bacterially induced cell death
复制标题
DOI：
10.1359/jbmr.071002
复制
发表时间：
2008-01-01
影响因子：
6.2
通讯作者：
Marriott, Ian
中科院分区：
文献类型：
--
作者：
McCall, Samuel H.;Sahraci, Mahnaz;Marriott, Ian
细菌诱导的成骨细胞凋亡可能是骨髓炎期间骨质流失的主要原因。我们提供了成骨细胞中 NLRP3 功能表达的证据，NLRP3 是细胞质受体 NLR 家族的成员，与程序性细胞死亡的启动有关。简介：成骨细胞在暴露于通常与骨髓炎相关的细胞内细菌病原体后会发生凋亡。这种骨形成细胞类型的死亡，加上破骨细胞数量和活性的增加，可能是细菌感染部位骨组织破坏的基础。迄今为止，细菌诱导的成骨细胞凋亡的机制尚未解决。 材料和方法：我们使用流式细胞术技术来确定在用肠沙门氏菌攻击后，原代成骨细胞中是否需要细胞内侵袭来实现最大程度的凋亡细胞死亡。此外，我们使用实时PCR和免疫印迹分析来评估含有核苷酸结合域、富含亮氨酸重复区域的细胞内受体（NLR）家族成员的成骨细胞表达，这些受体预计参与诱导程序性细胞死亡。此外，我们还使用免疫共沉淀和 siRNA 技术来确认此类传感器在该细胞类型中的功能。结果：在这项研究中，我们表明沙门氏菌侵入成骨细胞对于最大限度地诱导细胞凋亡是必要的。我们发现小鼠和人类成骨细胞表达 NLRP3（以前称为 CIAS1、cryopyrin、PYPAF1 或 NALP3），但不表达 NLRC4 (IPAF)，并表明这种胞质受体的表达水平在细菌攻击后受到调节。我们发现成骨细胞表达ASC（NLRP3的接头分子），并且这些分子在沙门氏菌感染后结合。此外，我们还发现，NLRP3 表达的减少可以减弱沙门氏菌诱导的成骨细胞中抗凋亡转录因子活性的降低。此外，我们发现，感染沙门氏菌后，NLRP3 的表达是成骨细胞中 caspase-1 激活和最大程度诱导细胞凋亡所必需的。结论：成骨细胞中 NLRP3 的功能表达提供了该细胞类型在受到细胞内细菌病原体攻击后细胞凋亡的潜在机制，并且可能是感染部位骨质流失的重要促成因素。
Bacterially induced osteoblast apoptosis may be a major contributor to bone loss during osteomyelitis. We provide evidence for the functional expression in osteoblasts of NLRP3, a member of the NLR family of cytosolic receptors that has been implicated in the initiation of programmed cell death.Introduction: Osteoblasts undergo apoptosis after exposure to intracellular bacterial pathogens commonly associated with osteomyelitis. Death of this bone-forming cell type, in conjunction with increased numbers and activity of osteoclasts, may underlie the destruction of bone tissue at sites of bacterial infection. To date, the mechanisms responsible for bacterially induced apoptotic osteoblast cell death have not been resolved.Materials and Methods: We used flow cytometric techniques to determine whether intracellular invasion is needed for maximal apoptotic cell death in primary osteoblasts after challenge with Salmonella enterica. In addition, we used real-time PCR and immunoblot analyses to assess osteoblast expression of members of the nucleotide-binding domain leucine-rich repeat region-containing family of intracellular receptors (NLRs) that have been predicted to be involved in the induction of programmed cell death. Furthermore, we have used co-immunoprecipitation and siRNA techniques to confirm the functionality of such sensors in this cell type.Results: In this study, we showed that invasion of osteoblasts by Salmonella is necessary for maximal induction of apoptosis. We showed that murine and human osteoblasts express NLRP3 (previously known as CIAS1, cryopyrin, PYPAF1, or NALP3) but not NLRC4 (IPAF) and showed that the level of expression of this cytosolic receptor is modulated after bacterial challenge. We showed that osteoblasts express ASC, an adaptor molecule for NLRP3, and that these molecules associate after Salmonella infection. In addition, we showed that a reduction in the expression of NLRP3 attenuates Salmonella-induced reductions in the activity of an anti-apoptotic transcription factor in osteoblasts. Furthermore, we showed that NLRP3 expression is needed for caspase-1 activation and maximal induction of apoptosis in osteoblasts after infection with Salmonella.Conclusions: The functional expression of NLRP3 in osteoblasts provides a potential mechanism underlying apoptotic cell death of this cell type after challenge with intracellular bacterial pathogens and may be a significant contributory factor to bone loss at sites of infection.