Porphyromonas gingivalis (Pg.) is the main pathogen of periodontitis. Studies have found that Pg. can affect systemic diseases including type 2 diabetes mellitus (T2DM) through oral-intestinal pathway, but its specific mechanism remains unclear.

To explore whether Pg. has an effect on T2DM by changing intestinal mechanical and immune barriers.

A total of 24 among 40 SPF mice were randomly selected to construct T2DM models, among the successful models, 16 mice were selected to be divided into the model group (DM group, n=8) and model+Pg. group (PD group, n=8), and the other 16 mice were divided into the control group (N group, n=8) and Pg. group (n=8). After modeling, body mass and fasting plasma glucose (FPG) of mice were observed, and oral glucose tolerance test (OGTT) was performed at the 5th week, OGTT curve was plotted and the area under the curve (AUC) was calculated. Pg. group and PD group were gavaged with Pg. bacterial solution from the 7th week for 5 consecutive weeks. Lipopolysaccharide (LPS) was determined by enzyme-related immunosorbent assay (ELISA), colonic tight-junction protein and inflammatory factors were detected by real-time fluorescence quantitative PCR, and colonic tissue lesions were observed by hematoxylin-eosin (HE) staining. Pearson correlation or Spearman correlation analysis was used to investigate the relationship of FPG with colonic tight junction protein mRNA expression and serum LPS levels in mice.

Body weight of DM group was higher than that of N group and Pg. group at 2nd to 6th weeks before irrigation (P<0.05), and body weight of PD group was higher than that of N group and body weight of PD group was higher than that of Pg. group at 3rd to 6th weeks before irrigation (P<0.05). The body weight of N group and Pg group was higher than that of DM group and PD group at 9th to 11th weeks, and the body weight of PD group was lower than that of DM group at 11th week (P<0.05). FPG in PD group was higher than that in the N and Pg. groups at 3rd to 6th weeks, and FPG in the DM group at 4th to 6th weeks was higher than that in N and Pg. groups. FPG of Pg. group was lower than that of the DM group and PD group at 7th to 11th weeks, PD group was higher than that of the N group, and PD group at week 10 and 11 was higher than the Pg. group (P<0.05). AUC in the DM group was higher than that in the N group and Pg. group, and PD group was higher than that in the N group, DM group and Pg. group (P<0.05). LPS of PD group was higher than that of N group and DM group (P<0.05). Tight junction protein 1 (ZO-1) in the PD group was lower than that in the N group, occludin in the DM group was lower than that in the N group, occludin in the PD group was lower than that in the N group, DM group and Pg. group (P<0.05). The interleukin (IL) -17A in the PD group was lower than that in the N group and Pg. group, and IL-10 in the N group was higher than that in the DM group and Pg. group (P<0.05). Tumor necrosis factor α in the PD group was higher than that in the N group, DM group and Pg. group (P<0.05). Toll-like receptor 4 in the Pg. group and PD group was higher than that in N group (P<0.05). Correlation analysis showed that FPG was positively correlated with LPS, and negatively correlated with occludin, ZO-1 (P<0.05). The pathological results showed connective tissue hyperplasia with focal lymphocyte infiltration in the lamina propria in the Pg. and DM groups, and the lamina propria with focal lymphocyte infiltration in the PD group.

Pg. may aggravate the glucose metabolism disorders of T2DM mice by disrupting the intestinal mechanical barrier and immune barrier leading to LPS entry into the bloodstream.

牙龈卟啉单胞菌（Pg.）是牙周炎的主要致病菌，研究发现Pg.能够通过口腔-肠道途径对2型糖尿病（T2DM）在内的全身疾病产生影响，而其具体机制尚不完全明确。

探究Pg.是否通过改变肠道机械屏障及免疫屏障对T2DM产生影响。

40只SPF级小鼠，随机挑选24只构建T2DM模型，建模成功小鼠中挑选16只分为模型组（DM组，n=8）和模型+Pg.组（PD组，n=8），其余16只小鼠分为空白对照组（N组，n=8）和Pg.组（n=8）。建模后观察小鼠体质量和空腹血糖（FPG），第5周进行口服葡萄糖耐量试验（OGTT），绘制OGTT曲线并计算曲线下面积（AUC）。第7周起Pg.组和PD组灌饲Pg.菌液，连续灌饲5周。采用酶联免疫吸附测定脂多糖（LPS），实时荧光定量PCR检测结肠紧密连接蛋白及炎症因子，苏木素-伊红（HE）染色观察小鼠结肠组织病变。采用Pearson相关性或Spearman秩相关分析探究小鼠FPG与结肠紧密连接蛋白mRNA表达及血清LPS含量的关系。

灌胃前第2~6周DM组体质量高于N组、Pg.组，PD组体质量高于N组，第3~6周PD组体质量高于Pg.组（P<0.05）。第9~11周N组、Pg.组体质量高于DM组、PD组，第11周PD组体质量低于DM组（P<0.05）。第3~6周PD组FPG高于N组、Pg.组，第4~6周DM组高于N组、Pg.组（P<0.05）。第7~11周Pg.组FPG低于DM组、PD组，PD组高于N组，第10、11周PD组高于Pg.组（P<0.05）。DM组AUC高于N组、Pg.组，PD组高于N组、DM组、Pg.组，PD组LPS高于N组、DM组（P<0.05）。PD组紧密连接蛋白1（ZO-1）低于N组，DM组闭合蛋白低于N组，PD组闭合蛋白低于N组、DM组、Pg.组，PD组白介素（IL）-17A低于N组、Pg.组，N组IL-10高于DM组、Pg.组、PD组，PD组肿瘤坏死因子α高于N组、DM组、Pg.组，Pg.组、PD组Toll样受体4高于N组（P<0.05）。相关性分析结果表明，FPG与LPS呈正相关，与闭合蛋白、ZO-1呈负相关（P<0.05）。病理结果显示Pg.组和DM组固有层可见结缔组织增生，伴淋巴细胞灶性浸润，PD组固有层伴淋巴细胞灶性浸润。

Pg.可能通过破坏肠道机械屏障及免疫屏障导致LPS入血，加重T2DM小鼠糖代谢紊乱。