Free Glycogen in Vaginal Fluids Is Associated with Lactobacillus Colonization and Low Vaginal pH

ObjectiveLactobacillus dominates the lower genital tract microbiota of many women, producing a low vaginal pH, and is important for healthy pregnancy outcomes and protection against several sexually transmitted pathogens. Yet, factors that promote Lactobacillus remain poorly understood. We hypothesized that the amount of free glycogen in the lumen of the lower genital tract is an important determinant of Lactobacillus colonization and a low vaginal pH.MethodsFree glycogen in lavage samples was quantified. Pyrosequencing of the 16S rRNA gene was used to identify microbiota from 21 African American women collected over 8–11 years.ResultsFree glycogen levels varied greatly between women and even in the same woman. Samples with the highest free glycogen had a corresponding median genital pH that was significantly lower (pH 4.4) than those with low glycogen (pH 5.8; pLactobacillus was highest in samples with high glycogen versus those with low glycogen (median = 0.97 vs. 0.05, pL. crispatus and L. jensenii, but not L. iners.ConclusionThese findings show that free glycogen in genital fluid is associated with a genital microbiota dominated by Lactobacillus, suggesting glycogen is important for maintaining genital health. Treatments aimed at increasing genital free glycogen might impact Lactobacillus colonization.研究背景：乳酸杆菌（Lactobacillus）是多数女性下生殖道菌群的优势菌种，可通过代谢产生乳酸以维持阴道低pH环境，对健康妊娠结局的维持以及抵御多种性传播病原体均具有关键作用。然而，当前促进乳酸杆菌定植的相关调控机制仍不甚明晰。本研究提出假说：下生殖道管腔内的游离糖原含量，是决定乳酸杆菌定植能力与阴道低pH环境形成的重要因素。 研究方法：对生殖道灌洗样本中的游离糖原进行定量检测；通过对16S rRNA基因进行焦磷酸测序，对21名非裔美国女性在8至11年的随访周期内采集的样本进行菌群组成鉴定。 研究结果：不同女性之间乃至同一女性的不同采样时点，游离糖原水平均存在显著差异。游离糖原含量最高的样本，其生殖道pH中位数为4.4，显著低于低糖原样本的5.8（p值未完整标注）；高糖原样本中的乳酸杆菌相对丰度中位数为0.97，显著高于低糖原样本的0.05（p值未完整标注），且优势菌种为卷曲乳酸杆菌（L. crispatus）与詹氏乳酸杆菌（L. jensenii），而非伊氏乳酸杆菌（L. iners）。 研究结论：本研究结果表明，生殖道液中的游离糖原与以乳酸杆菌为主导的生殖道菌群结构密切相关，提示糖原在维持生殖道健康中发挥重要作用。以提升生殖道游离糖原水平为目标的干预策略，或可有效调控乳酸杆菌的定植过程。