Laboratorio de Microbiología Celular, Instituto de Investigación y Postgrado, Facultad de Ciencias de La Salud, Universidad Central de Chile, 8330546, Santiago, Chile.
Laboratory of Cellular Communication, Center for Studies On Exercise Metabolism and Cancer (CEMC), Institute of Biomedical Sciences (ICBM), Facultad de Medicina, Universidad de Chile, 8380453, Santiago, Chile.
J Neuroinflammation. 2023 Mar 9;20(1):66. doi: 10.1186/s12974-023-02728-7.
Helicobacter pylori (Hp) infects the stomach of 50% of the world's population. Importantly, chronic infection by this bacterium correlates with the appearance of several extra-gastric pathologies, including neurodegenerative diseases. In such conditions, brain astrocytes become reactive and neurotoxic. However, it is still unclear whether this highly prevalent bacterium or the nanosized outer membrane vesicles (OMVs) they produce, can reach the brain, thus affecting neurons/astrocytes. Here, we evaluated the effects of Hp OMVs on astrocytes and neurons in vivo and in vitro.
Purified OMVs were characterized by mass spectrometry (MS/MS). Labeled OMVs were administered orally or injected into the mouse tail vein to study OMV-brain distribution. By immunofluorescence of tissue samples, we evaluated: GFAP (astrocytes), βIII tubulin (neurons), and urease (OMVs). The in vitro effect of OMVs in astrocytes was assessed by monitoring NF-κB activation, expression of reactivity markers, cytokines in astrocyte-conditioned medium (ACM), and neuronal cell viability.
Urease and GroEL were prominent proteins in OMVs. Urease (OMVs) was present in the mouse brain and its detection coincided with astrocyte reactivity and neuronal damage. In vitro, OMVs induced astrocyte reactivity by increasing the intermediate filament proteins GFAP and vimentin, the plasma membrane αβ integrin, and the hemichannel connexin 43. OMVs also produced neurotoxic factors and promoted the release of IFNγ in a manner dependent on the activation of the transcription factor NF-κB. Surface antigens on reactive astrocytes, as well as secreted factors in response to OMVs, were shown to inhibit neurite outgrowth and damage neurons.
OMVs administered orally or injected into the mouse bloodstream reach the brain, altering astrocyte function and promoting neuronal damage in vivo. The effects of OMVs on astrocytes were confirmed in vitro and shown to be NF-κB-dependent. These findings suggest that Hp could trigger systemic effects by releasing nanosized vesicles that cross epithelial barriers and access the CNS, thus altering brain cells.
幽门螺杆菌（Hp）感染了全球 50%人口的胃部。重要的是，这种细菌的慢性感染与几种胃外病理有关，包括神经退行性疾病。在这种情况下，大脑星形胶质细胞会变得反应性和神经毒性。然而，目前尚不清楚是这种高度流行的细菌还是它们产生的纳米大小的外膜囊泡（OMVs）能够到达大脑，从而影响神经元/星形胶质细胞。在这里，我们评估了 Hp OMVs 对体内和体外星形胶质细胞和神经元的影响。
通过质谱（MS/MS）对纯化的 OMVs 进行了表征。用标记的 OMVs 进行口服或尾静脉注射，以研究 OMV 与大脑的分布。通过对组织样本进行免疫荧光染色，我们评估了 GFAP（星形胶质细胞）、βIII 微管蛋白（神经元）和脲酶（OMVs）。通过监测 NF-κB 激活、反应性标志物表达、星形胶质细胞条件培养基（ACM）中的细胞因子以及神经元细胞活力，评估了 OMVs 对星形胶质细胞的体外作用。
脲酶和 GroEL 是 OMVs 中的主要蛋白质。在小鼠大脑中检测到脲酶（OMVs），其存在与星形胶质细胞反应性和神经元损伤一致。在体外，OMVs 通过增加中间丝蛋白 GFAP 和波形蛋白、质膜 αβ 整联蛋白和半通道连接蛋白 43 来诱导星形胶质细胞反应性。OMVs 还产生了神经毒性因子，并以依赖于转录因子 NF-κB 激活的方式促进 IFNγ 的释放。反应性星形胶质细胞上的表面抗原以及对 OMVs 做出反应的分泌因子，被证明会抑制轴突生长并损害神经元。
口服给予或注射到小鼠血液中的 OMVs 到达大脑，改变星形胶质细胞功能并在体内促进神经元损伤。在体外证实了 OMVs 对星形胶质细胞的作用，并表明该作用依赖于 NF-κB。这些发现表明，Hp 可以通过释放纳米大小的囊泡来触发全身性效应，这些囊泡可以穿过上皮屏障并进入中枢神经系统，从而改变脑细胞。
