The aim of this study was to identify whether periodontitis induces gut microbiota dysbiosis via invasion by salivary microbes. First, faecal and salivary samples were collected from periodontally healthy participants (PH group, n = 16) and patients with severe periodontitis (SP group, n = 21) and analysed by 16S ribosomal RNA sequencing. Significant differences were observed in both the faecal and salivary microbiota between the PH and SP groups. Notably, more saliva-sourced microbes were observed in the faecal samples of the SP group. Then, the remaining salivary microbes were transplanted into C57BL6/J mice (the C-PH group and the C-SP group), and it was found that the composition of the gut microbiota of the C-SP group was significantly different from that of the C-PH group, with Porphyromonadaceae and Fusobacterium being significantly enriched in the C-SP group. In the colon, the C-SP group showed significantly reduced crypt depth and zonula occludens-1 expression. The mRNA expression levels of pro-inflammatory cytokines, chemokines and tight junction proteins were significantly higher in the C-SP group. To further investigate whether salivary bacteria could persist in the intestine, the salivary microbiota was stained with carboxyfluorescein diacetate succinimidyl ester and transplanted into mice. We found that salivary microbes from both the PH group and the SP group could persist in the gut for at least 24 h. Thus, our data demonstrate that periodontitis may induce gut microbiota dysbiosis through the influx of salivary microbes.

本研究的目的是确定牙周炎是否通过唾液微生物的入侵引起肠道菌群失调。首先，从牙周健康参与者（PH 组， n  = 16）和严重牙周炎患者（SP 组，n = 21）收集粪便和唾液样本， 并通过 16S 核糖体 RNA 测序进行分析。在 PH 组和 SP 组之间的粪便和唾液微生物群中观察到显着差异。值得注意的是，在 SP 组的粪便样本中观察到更多唾液来源的微生物。然后，将剩余的唾液微生物移植到 C57BL6/J 小鼠（C-PH 组和 C-SP 组）中，发现 C-SP 组的肠道菌群组成与C-PH 组，与卟啉单胞菌科和梭杆菌在 C-SP 组中显着富集。在结肠中，C-SP 组显示出显着降低的隐窝深度和 zonula occludens-1 表达。C-SP组促炎细胞因子、趋化因子和紧密连接蛋白的mRNA表达水平显着升高。为了进一步研究唾液细菌是否可以在肠道中持续存在，唾液微生物群用羧基荧光素二乙酸琥珀酰亚胺酯染色并移植到小鼠体内。我们发现 PH 组和 SP 组的唾液微生物可以在肠道中持续至少 24 小时。因此，我们的数据表明，牙周炎可能通过唾液微生物的流入导致肠道菌群失调。