Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Stomatological Hospital of Chongqing Medical University, Chongqing, China.
Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China.
Front Cell Infect Microbiol. 2023 Jan 10;12:1057327. doi: 10.3389/fcimb.2022.1057327. eCollection 2022.
Oral microbial homeostasis is a key factor affecting oral health, and saliva plays a significant role in maintaining oral microbial homeostasis. The submandibular gland (SMG) and sublingual gland (SLG) together produce the most saliva at rest. Organic ingredients, including antimicrobial proteins, are rich and distinctive and depend on the type of acinar cells in the SMG and SLG. However, the functions of the SMG and SLG in maintaining oral microbial homeostasis have been difficult to identify and distinguish, given their unique anatomical structures.
In this study, we independently removed either the SMG or SLG from mouse models. SMGs were aseptically removed in three mice in the SMG-removal group, and SLGs were aseptically removed in three mice in the SLG-removal group. Three mice from the sham-operated group were only anesthetized and incised the skin. After one month, we analyzed their oral microbiome through 16S rRNA sequencing. And then, we analyzed each gland using proteomics and single-cell RNA sequencing.
Our study revealed that the microbiome balance was significantly disturbed, with decreased bacterial richness, diversity, and uniformity in the groups with the SMG or SLG removed compared with the sham-operated group. We identified eight secreted proteins in the SMG and two in the SLG that could be involved in maintaining oral microbial homeostasis. Finally, we identified multiple types of cells in the SMG and SLG (including serous acinar, mucinous acinar, ductal epithelial, mesenchymal, and immune cells) that express potential microbiota homeostasis regulatory proteins. Our results suggest that both the SMG and SLG play crucial roles in maintaining oral microbial homeostasis via excretion. Furthermore, the contribution of the SMG in maintaining oral microbial homeostasis appears to be superior to that of the SLG. These findings also revealed the possible antimicrobial function of gland secreta.
Our results suggest that control of oral microbial dysbiosis is necessary when the secretory function of the SMG or SLG is impaired. Our study could be the basis for further research on the prevention of oral diseases caused by microbial dysbiosis.
口腔微生物稳态是影响口腔健康的关键因素，唾液在维持口腔微生物稳态方面起着重要作用。下颌下腺 (SMG) 和舌下腺 (SLG) 在休息时共同产生最多的唾液。有机成分，包括抗菌蛋白，丰富而独特，取决于 SMG 和 SLG 中的腺泡细胞类型。然而，由于其独特的解剖结构，SMG 和 SLG 维持口腔微生物稳态的功能一直难以识别和区分。
在本研究中，我们分别从小鼠模型中去除了 SMG 或 SLG。在 SMG 去除组的 3 只小鼠中无菌去除 SMGs，在 SLG 去除组的 3 只小鼠中无菌去除 SLGs。来自假手术组的 3 只小鼠仅接受麻醉和皮肤切开。一个月后，我们通过 16S rRNA 测序分析了它们的口腔微生物组。然后，我们使用蛋白质组学和单细胞 RNA 测序分析了每个腺体。
我们的研究表明，与假手术组相比，去除 SMG 或 SLG 的组中微生物组的平衡明显受到干扰，细菌丰富度、多样性和均匀性降低。我们在 SMG 中鉴定出 8 种分泌蛋白，在 SLG 中鉴定出 2 种可能参与维持口腔微生物稳态的蛋白。最后，我们在 SMG 和 SLG 中鉴定出多种类型的细胞（包括浆液腺泡、粘液腺泡、导管上皮、间充质和免疫细胞），这些细胞表达潜在的微生物群稳态调节蛋白。我们的结果表明，SMG 和 SLG 均通过排泄在维持口腔微生物稳态方面发挥关键作用。此外，SMG 在维持口腔微生物稳态方面的作用似乎优于 SLG。这些发现还揭示了腺体分泌物可能具有的抗菌功能。
当 SMG 或 SLG 的分泌功能受损时，控制口腔微生物失调是必要的。我们的研究可以为进一步研究预防由微生物失调引起的口腔疾病提供基础。
