Graduate Student Harvard School of Public Health Boston, Massachusetts, United States
Disclosure(s):
Virginia Glick: No financial relationships to disclose
Introduction/Rationale: The human vaginal microbiome can be broadly described as either Lactobacillus-dominant, low-diversity communities or Lactobacillus-low, high-diversity communities. While the presence of lactobacilli is associated with reduced inflammation and pro-inflammatory cytokines in the vagina, diverse communities lacking lactobacilli dominance are correlated with increased risk of inflammatory conditions. It is unclear how the health-associated lactobacilli actively promote the anti-inflammatory homeostasis of the vaginal mucosa.
Methods: We previously identified anti-inflammatory beta-carboline (BC) compounds in the supernatant of Lactobacillus bacterial culture, also present in cervicovaginal lavage of healthy people. We expand on our past findings, further evaluating anti-inflammatory activity of purified BC on fibroblast, endocervical, and macrophage cell lines. Currently, we are working toward elucidating mechanisms by which these compounds exert their anti-inflammatory effects in host cells by generating a CRISPRi endocervical reporter cell line. We are also investigating immune and microbial correlates of BC production with cytokine profiling and LC/MS.
Results: In addition to suppressing NFkB and ISG signaling downstream of multiple TLRs, we also observed suppression of cytosolic pathways, such as the cGAS-STING signaling pathway, and other cytokine receptors, including TNFa receptor. We observed cell type specificity in anti-inflammatory activity, with BCs suppressing type I interferon receptor activation in macrophages but not primary epithelial cells, however it is unclear if differential uptake of compound is responsible. Ongoing work focuses on identifying the genes required for this inhibition.
Conclusion: While there appear to be cell type specific differences in response to BC6, anti-inflammatory activity is broad, and the target of these compounds has yet to be uncovered. Ultimately, this work highlights a method by which vaginal commensal microbiome might maintain immune homeostasis.
