Data_Sheet_1_Whole Transcriptome Analysis Reveals That Filifactor alocis Modulates TNFα-Stimulated MAPK Activation in Human Neutrophils.pdf

Periodontitis is an irreversible, bacteria-induced, chronic inflammatory disease that compromises the integrity of tooth-supporting tissues and adversely affects systemic health. As the immune system's first line of defense against bacteria, neutrophils use their microbicidal functions in the oral cavity to protect the host against periodontal disease. However, periodontal pathogens have adapted to resist neutrophil microbicidal mechanisms while still propagating inflammation, which provides essential nutrients for the bacteria to proliferate and cause disease. Advances in sequencing technologies have recognized several newly appreciated bacteria associated with periodontal lesions such as the Gram-positive anaerobic rod, Filifactor alocis. With the discovery of these oral bacterial species, there is also a growing need to assess their pathogenic potential and determine their contribution to disease progression. Currently, few studies have addressed the pathogenic mechanisms used by oral bacteria to manipulate the neutrophil functional responses at the level of the transcriptome. Thus, this study aims to characterize the global changes at the gene expression level in human neutrophils during infection with F. alocis. Our results indicate that the challenge of human neutrophils with F. alocis results in the differential expression of genes involved in multiple neutrophil effector functions such as chemotaxis, cytokine and chemokine signaling pathways, and apoptosis. Moreover, F. alocis challenges affected the expression of components from the TNF and MAPK kinase signaling pathways. This resulted in transient, dampened p38 MAPK activation by secondary stimuli TNFα but not by fMLF. Functionally, the F. alocis-mediated inhibition of p38 activation by TNFα resulted in decreased cytokine production but had no effect on the priming of the respiratory burst response or the delay of apoptosis by TNFα. Since the modulatory effect was characteristic of viable F. alocis only, we propose this as one of F. alocis' mechanisms to control neutrophils and their functional responses.

牙周炎（Periodontitis）是一类不可逆的、由细菌诱导的慢性炎症性疾病，可破坏牙支持组织的完整性，并对全身健康产生不利影响。作为免疫系统对抗细菌的第一道防线，中性粒细胞（neutrophil）可在口腔内发挥杀菌功能，从而保护宿主抵御牙周疾病。然而，牙周病原体已进化出对抗中性粒细胞杀菌机制的能力，同时仍可促发炎症反应——这一过程可为细菌增殖提供必需的营养物质，进而引发疾病。测序技术的进步已使多种与牙周病变相关的新发现细菌得以确认，例如革兰氏阳性厌氧杆菌、嗜纤维菌属（Filifactor）的福氏嗜纤维菌（Filifactor alocis）。随着这些口腔细菌物种的发现，评估其致病潜力、明确其在疾病进展中的作用的需求也日益增长。目前，鲜有研究从转录组层面探究口腔细菌调控中性粒细胞功能应答的致病机制。因此，本研究旨在刻画感染福氏嗜纤维菌（Filifactor alocis）期间，人类中性粒细胞基因表达水平的全局变化。我们的研究结果显示，人类中性粒细胞受到福氏嗜纤维菌（Filifactor alocis）刺激后，参与多种中性粒细胞效应功能的基因出现差异表达，这些功能包括趋化作用、细胞因子与趋化因子信号通路以及细胞凋亡。此外，福氏嗜纤维菌刺激还会影响肿瘤坏死因子（TNF）及丝裂原活化蛋白激酶（MAPK）信号通路相关组分的表达。这一变化导致在次级刺激肿瘤坏死因子α（TNFα）作用下，p38丝裂原活化蛋白激酶（p38 MAPK）的激活呈现一过性减弱，但在fMLF刺激下并未出现该现象。从功能层面来看，福氏嗜纤维菌介导的肿瘤坏死因子α诱导的p38激活抑制，会导致细胞因子生成减少，但对呼吸爆发反应的致敏或肿瘤坏死因子α介导的细胞凋亡延迟均无影响。由于这种调控效应仅在活菌福氏嗜纤维菌刺激下才会出现，我们推测这可能是福氏嗜纤维菌调控中性粒细胞及其功能应答的机制之一。