P. Gingivalis-Induced Nets Mediate Neuroinflammation Via Tlr4/Gsk3β/Akt

This study aimed to investigate the effects and underlying mechanisms of Porphyromonas gingivalis (P. gingivalis)-induced NETs on neuroinflammation. A mouse model of periodontitis was established through intraoral live Porphyromonas gingivalis (P. gingivalis) and was performed using micro-computed tomography. Neutrophils proportions were examined by flow cytometry. NETs formation were analyzed via corresponding kits. Its morphology, mRNA and protein expressions were shown by immunofluorescence (IF), reverse transcription-polymerase chain reaction (RT-PCR) and western blot. Cognitive ability, neuroinflammation and amyloid precursor protein (APP) processing were measured by behavior tests, RT-PCR and immunohistochemistry (IHC). In addition, NETs influences on BV2 and N2a cells were performed by CCK8, RT-PCR and IF, which can clarify the functional mechanism of NETs on glia-neuron unit. It was observed significant alveolar bone resorption in periondontitis mice group with increased neutrophils and NETs formation in the periphery and brain. Cognitive abilities were impaired by periodontitis, neuroinflammation was manifested by microglia and astrocytes activation and upregulated inflammatory cytokines and APP processing was determined by staining NeuN, APP and PSEN1 in the periodontitis mice group. In vitro, P. gingivalis-induced NETs could induce BV2 cells to M1 polarization and promote APP processing in N2a cells, along with the activation of TLR4/GSK3β/Akt, consistent with in vivo findings. It showed that P. gingivalis-induced NETs exerted a pivotal function in the relationship between periodontitis and neuroinflammation. Furthermore, the impacts of NETs on glia-neuron unit were both related to TLR4/GSK3β/Akt pathway.