Researchers at the March of Dimes Prematurity Research Center at Imperial College London have found that some women who experience preterm birth have significantly different sugar profiles, or glycomes, in their cervicovaginal fluid shortly before birth than they had when they were further from labor.
Though the association needs to be validated in larger patient populations, it may suggest that imminent preterm or term birth alters a woman’s vaginal glycome profile, an important component of cellular makeup that can influence reproductive health.
The findings, recently published in the journal Scientific Reports, part of the Nature family of journals, come from an analysis of vaginal sugar profiles belonging to 40 women, 36 of whom were pregnant. In this study, glycomics experts, or scientists focused on the role of sugars in the body, studied vaginal mucus gathered from a cup placed under study participants’ cervix for 20 minutes.
For the pregnant women, samples were taken at various points during gestation; some women had only one sample taken, and other women had as many as three. Of the 36 pregnant women—who were all considered high risk for preterm birth—15 delivered preterm.
Sugars, which sit on every cell surface in the human body, can be found on proteins, fats, or in the case of ‘free glycans,’ can be free flowing. The Imperial study involved sugars found on proteins, considered the most important in glycobiology. To facilitate the sugar analysis, the PRC team separated the sugars from the proteins.
When PRC scientists and senior study authors Prof. Stuart Haslam and Prof. Anne Dell looked at the sugar profiles, or signatures, of the women who had multiple samples taken during pregnancy, they noticed a striking difference in the signatures of two women who went on to deliver about a week after the last sample was taken. Their last sample, the researchers found, looked much different than their first. Both those women delivered preterm; one around 26 weeks and the other around 27.5 weeks.
Because all the women in the study were sampled at different times, and in varying frequency, it’s unclear whether the glycomes of the rest of the pregnant women also changed right before they gave birth; the rest of the participants either gave birth many weeks after the last sample, or, in the case of several women who gave birth within days of being sampled, no comparison could be made because it was their only sample taken.
“We found that, maybe not surprisingly, every woman is unique and every woman produces a very complex series of sugars,” said Prof. Haslam. “We also observed that for the women with multiple samplings, the sugar signatures tended to stay the same except for when women went into preterm birth. Their sugar signature dramatically changed in the final sampling before preterm birth.”
“This suggests that imminent birth or preterm birth can change vaginal sugar signatures, and we’re looking to link this data with other data sets from the Imperial team to see if we can get a clearer picture of what’s going on.”
There were other interesting findings, Prof. Haslam said, including the fact that the glycomes of non-pregnant women looked different than the majority of pregnant women, and that some women’s glycomes shared similarities with the glycomes of human cancers.
“We observed that the glycan profile of some women was unusual and not what we would expect,” he said. “The unusual glycosylation profile has been previously identified in some human cancers and viral glycoproteins. We are not sure why, but we are absolutely not saying that any of the women have cancer or viral infection.”
Prof. Haslam, who has been studying the role of sugars in the body and their relationship to disease for 30 years, said the next step in this work involves linking the sugar profiles from his study with different immune profiles and vaginal microbiome bacteria that are either associated with preterm birth or protective against it. Both datasets exist at the Imperial PRC as part of the group’s world-leading inquiry into vaginal microbiome driven preterm birth.
He said he is also eager to study the glycome samples of low-risk pregnant women to see if any comparisons can be made with the high-risk group profiled in this most recent paper.
“We want to look at the control group in more detail and to have a bigger sample size so we can have more data and make more robust associations.”