Integrin α5β1-fimbriae binding and actin rearrangement are essential for <it>Porphyromonas gingivalis</it> invasion of osteoblasts and subsequent activation of the JNK pathway

• Main Authors: Zhang Wenjian, Ju Jun, Rigney Todd, Tribble Gena
• Format: Article
• Language: English
• Published: BMC 2013-01-01
• Series: BMC Microbiology
• Subjects: Osteoblasts; <it>Porphyromonas gingivalis</it>; Integrins; Cytoskeleton; Signaling; Apoptosis
• Online Access: http://www.biomedcentral.com/1471-2180/13/5

<p>Abstract</p> <p>Background</p> <p>Chronic periodontitis is an infectious disease of the periodontium, which includes the gingival epithelium, periodontal ligament and alveolar bone. The signature clinical feature of periodontitis is resorption of alveolar bone and subsequent tooth loss. The Gram-negative oral anaerobe, <it>Porphyromonas gingivalis</it>, is strongly associated with periodontitis, and it has been shown previously that <it>P. gingivalis</it> is capable of invading osteoblasts in a dose- and time-dependent manner resulting in inhibition of osteoblast differentiation and mineralization <it>in vitro</it>. It is not yet clear which receptors and cytoskeletal components mediate the invasive process, nor how the signaling pathways and viability of osteoblasts are affected by bacterial internalization. This study aimed to investigate these issues using an <it>in vitro</it> model system involving the inoculation of <it>P. gingivalis</it> ATCC 33277 into primary osteoblast cultures.</p> <p>Results</p> <p>It was found that binding between <it>P. gingivalis</it> fimbriae and integrin α5β1 on osteoblasts, and subsequent peripheral condensation of actin, are essential for entry of <it>P. gingivalis</it> into osteoblasts. The JNK pathway was activated in invaded osteoblasts, and apoptosis was induced by repeated infections.</p> <p>Conclusions</p> <p>These observations indicate that <it>P. gingivalis</it> manipulates osteoblast function to promote its initial intracellular persistence by prolonging the host cell life span prior to its intercellular dissemination via host cell lysis. The identification of molecules critical to the interaction between <it>P. gingivalis</it> and osteoblasts will facilitate the development of new therapeutic strategies for the prevention of periodontal bone loss.</p>