Department of Oral Biology, University at Buffalo, The State University of New York, Buffalo, New York, USA.
Department of Oral Biology, University at Buffalo, The State University of New York, Buffalo, New York, USA
Infect Immun. 2019 Oct 18;87(11). doi: 10.1128/IAI.00553-19. Print 2019 Nov.
Periodontal disease is a significant health burden, causing tooth loss and poor oral and overall systemic health. Dysbiosis of the oral biofilm and a dysfunctional immune response drive chronic inflammation, causing destruction of soft tissue and alveolar bone supporting the teeth. , a spirochete abundant in the plaque biofilm of patients with severe periodontal disease, perturbs neutrophil function by modulating appropriate phosphoinositide (PIP) signaling. Through a series of immunoblotting and quantitative PCR (qPCR) experiments, we show that Msp does not alter the gene transcription or protein content of key enzymes responsible for PIP3 signaling: 3' phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), or 5' Src homology 2 domain-containing inositol phosphatase 1 (SHIP1). Instead, using immunoblotting and enzyme-linked immunosorbent assays (ELISAs), we found that Msp activates PTEN through dephosphorylation specifically at the S380 site. Msp in intact organisms or outer membrane vesicles also restricts PIP signaling. SHIP1 phosphatase release was assessed using chemical inhibition and immunoprecipitation to show that Msp moderately decreases SHIP1 activity. Msp also prevents secondary activation of the PTEN/PI3K response. We speculate that this result is due to the redirection of the PIP3 substrate away from SHIP1 to PTEN. Immunofluorescence microscopy revealed a redistribution of PTEN from the cytoplasm to the plasma membrane following exposure to Msp, which may contribute to PTEN activation. Mechanisms of how modulates and evades the host immune response are still poorly described, and here we provide further mechanistic evidence of how spirochetes modify PIP signaling to dampen neutrophil function. Understanding how oral bacteria evade the immune response to perpetuate the cycle of inflammation and infection is critical for combating periodontal disease to improve overall health outcomes.
牙周病是一种严重的健康负担，会导致牙齿脱落和口腔及整体全身健康状况不佳。口腔生物膜的失调和功能失调的免疫反应会引发慢性炎症，导致软组织和支持牙齿的牙槽骨破坏。螺旋体在严重牙周病患者的斑块生物膜中丰富，通过调节适当的磷酸肌醇（PIP）信号来扰乱中性粒细胞的功能。通过一系列免疫印迹和定量 PCR（qPCR）实验，我们表明 Msp 不会改变负责 PIP3 信号的关键酶的基因转录或蛋白含量：3'磷酸酶和张力蛋白同源物（PTEN）、磷脂酰肌醇 3-激酶（PI3K）或 5'Src 同源 2 结构域含肌醇磷酸酶 1（SHIP1）。相反，我们通过免疫印迹和酶联免疫吸附测定（ELISA）发现，Msp 通过特异性在 S380 位点去磷酸化来激活 PTEN。完整生物体或外膜囊泡中的 Msp 也限制了 PIP 信号。通过化学抑制和免疫沉淀评估 SHIP1 磷酸酶释放，表明 Msp 适度降低 SHIP1 活性。Msp 还防止了 PTEN/PI3K 反应的二次激活。我们推测，这一结果是由于 PIP3 底物从 SHIP1 转移到 PTEN。免疫荧光显微镜显示，暴露于 Msp 后，PTEN 从细胞质重新分布到质膜，这可能有助于 PTEN 的激活。关于如何调节和逃避宿主免疫反应的机制仍知之甚少，在这里，我们提供了进一步的机制证据，说明螺旋体如何修饰 PIP 信号以抑制中性粒细胞的功能。了解口腔细菌如何逃避免疫反应以维持炎症和感染的循环，对于防治牙周病以改善整体健康结果至关重要。
