Mann Allison E, Aumend Ciara, Crull Suzanne, O'Connell Lauren M, Osagie Esosa, Akhigbe Paul, Obuekwe Ozoemene, Omoigberale Augustine, Rowe Matthew, Blouin Thomas, Soule Ashlyn, Kelly Colton, Burne Robert A, Coker Modupe O, Richards Vincent P
University of Wyoming.
Clemson University.
Res Sq. 2024 Aug 10:rs.3.rs-4720457. doi: 10.21203/rs.3.rs-4720457/v1.
The oral microbiome comprises distinct microbial communities that colonize diverse ecological niches across the oral cavity, the composition of which are influenced by nutrient and substrate availability, host genetics, diet, behavior, age, and other diverse host and environmental factors. Unlike other densely populated human-associated microbial ecosystems (e.g., gut, urogenital), the oral microbiome is regularly and directly exposed to the external environment and is therefore likely less stable over time. Cross sectional studies of the oral microbiome capture a glimpse of this temporal dynamism, yet a full appreciation of the relative stability, robusticity, and spatial structure of the oral environment is necessary to understand the role of microbial communities in promoting health or disease.
Here we investigate the spatial and temporal stability of the oral microbiome over three sampling time points in the context of HIV infection and exposure. Individual teeth were sampled from a cohort of 565 Nigerian children with varying levels of tooth decay severity (i.e., caries disease). We collected 1,960 supragingival plaque samples and characterized the oral microbiome using a metataxonomic approach targeting an approximately 478 bp region of the bacterial C gene. We found that both infection and exposure to HIV have significant effects on the stability of the supragingival plaque microbiome at both the spatial and temporal scale. Specifically, we detect (1) significantly lower taxonomic turnover of the oral community among exposed and infected children compared to unexposed children, (2) we find that HIV infection homogenizes the oral community across the anterior and posterior dentition, and (3) that impaired immunity (i.e., low CD4 count) and low taxonomic turnover over time in children living with HIV is associated with higher frequency of cariogenic taxa including .
Our results document substantial community fluctuations over time in children unexposed to HIV independent of oral health status. This suggests that the oral community, under typical conditions, rapidly adapts to environmental perturbations to maintain homeostasis and that long-term taxonomic rigidity is a signal of community dysfunction, potentially leading to a higher incidence of oral disease including caries.
口腔微生物群由定殖于口腔内不同生态位的独特微生物群落组成，其组成受营养物质和底物可用性、宿主遗传学、饮食、行为、年龄以及其他各种宿主和环境因素影响。与其他人口密集的人类相关微生物生态系统（如肠道、泌尿生殖系统）不同，口腔微生物群经常且直接暴露于外部环境，因此随着时间推移可能稳定性较差。对口腔微生物群的横断面研究让我们得以一窥这种时间动态变化，但要理解微生物群落在促进健康或疾病中的作用，全面了解口腔环境的相对稳定性、稳健性和空间结构是必要的。
在此，我们在HIV感染和暴露的背景下，研究了口腔微生物群在三个采样时间点的空间和时间稳定性。从565名患有不同程度龋齿严重程度（即龋病）的尼日利亚儿童队列中采集单个牙齿样本。我们收集了1960份龈上菌斑样本，并使用靶向细菌C基因约478 bp区域的宏分类学方法对口腔微生物群进行了表征。我们发现，HIV感染和暴露在空间和时间尺度上均对龈上菌斑微生物群的稳定性有显著影响。具体而言，我们检测到：（1）与未暴露儿童相比，暴露和感染儿童的口腔群落分类学周转率显著降低；（2）我们发现HIV感染使前牙列和后牙列的口腔群落同质化；（3）感染HIV儿童的免疫功能受损（即CD4计数低）以及随着时间推移分类学周转率低与包括致龋菌属在内的致龋类群的较高频率相关。
我们的结果表明，未暴露于HIV的儿童口腔群落随时间存在显著波动，且与口腔健康状况无关。这表明在典型条件下，口腔群落会迅速适应环境扰动以维持体内平衡，而长期的分类学僵化是群落功能障碍的信号，可能导致包括龋齿在内的口腔疾病发病率更高。
