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Lactobacilli dominate the vagina in Belgian women

/in ISAPP Science Blog /by KC

By Prof. Sarah Lebeer, Research Professor in Microbiology and Molecular Biology, Department of Bioscience Engineering, University of Antwerp, Belgium

A little over a year ago, I wrote an ISAPP blog post about the setup of our Isala citizen science project on women’s health. Now, I can proudly say that we have the first results. Last year, more than 3300 women sent vaginal samples back to our lab, not only from the big cities but also from the smallest villages all over Flanders, Belgium (Figure 1). While Prof. Jack Ravel and many other colleagues have already done pioneering work in the US (e.g., Ravel et al. PNAS & Valencia study), Estonia and Africa, the vaginal microbiome of healthy women was less well mapped in the region where we live in Western Europe (Flanders, Belgium).

Figure 1: Map of Flanders (Belgium) showing regions from which the Isala participants sent their samples, with a gradient for the number of participants.

Last year, we managed to inspire women from a wide age range to donate two vaginal self-sampled swabs: the youngest participants were 18 years old, while a woman of 98 years old even participated. Each participant of Isala showed a unique vaginal microbiome (Figure 2).

Figure 2. Bar chart showing that each Isala participant had a unique vaginal microbiome composition, but also that lots of parallels could be drawn based on the most dominant bacterium.

Through various analyses, we were able to find parallels between the vaginal profiles of the Isala participants. We decided to divide the women in eight groups based on their most dominant microbe. Lactobacillus crispatus was found in 43% of all Isala women as most dominant bacterium, Lactobacillus iners in 28%, Lactobacillus jensenii in 4%, Lactobacillus gasseri in 3%, Gardnerella vaginalis in 12%, Prevotella in 6%, Bifidobacterium in 2% and Streptococcus in 2% of all Isala participants (Figure 3). Last June 2021, all women received this information, with a nice drawing for each bacterium and some interesting facts about these bacteria, as well as the relative abundance of this top 8. (See here.)

Figure 3. Chart showing the proportion of women participating in the Isala project that have a vaginal microbiota dominated by different bacterial genera or species.

Our work has only just begun. My team (see photo below) is now analyzing all the metadata collected via the detailed questionnaires and associating them with these microbiome profiles. The impact of the menstrual cycle, hormonal fluctuations, diet, smoking, sexual activity and other relevant factors is currently being explored. Hopefully, this will allow us to better understand for the vaginal tract what a ‘healthy microbiome’ really is and what action women can take to obtain or preserve  a ‘healthy’ or resilient microbiome. This is challenging to define with our current state of knowledge, but one characteristic of health of the microbiome may be its resilience. At the next annual ISAPP meeting, Karen Scott and I will co-chair a discussion group on ‘What do we really know about the microbiome and health?’. Now, I think it is fair to say that, compared to the gut, associations between specific microbiome members, such as lactobacilli, and health are quite strong for the vaginal tract. These lactobacilli form a protective barrier, are able to keep pathogens out, and prevent overt inflammation, so we could define lactobacilli-dominated vaginal communities as being resilient to many infections and disorders and thus probably ‘healthy’.

However, there is still much we do not know. Can women make certain changes in their lifestyle, diet, anticonception, underwear material etc. to promote lactobacilli such as L. crispatus in their vagina? What are the consequences of normal events in live such as pregnancy and menopause on these lactobacilli? Is a vaginal community with less lactobacilli always less healthy or resilient? On this page, you can get an overview of the different aspects we want to investigate. We hope to submit the first big Isala manuscript by the end of this year and will inform you as soon as possible about the results.

Lebeer lab, University of Antwerp

Citizen scientists step up for a research project on women’s health

/in ISAPP Science Blog /by KC

By Prof. Sarah Lebeer, Research Professor in Microbiology and Molecular Biology, Department of Bioscience Engineering, University of Antwerp, Belgium

Lactobacilli are a very important group of bacteria that live on the human body and in many other environments on Earth. They have been linked to human health for more than 100 years already, but mainly in the context of digestive health and dairy-based fermented foods. Knowledge about other habitats and applications of lactobacilli is lagging behind, and surprisingly, we know little about where lactobacilli come from in the life of an individual or even in the evolution of humans. Studying the genetic capabilities of lactobacilli and their interactions with the host will give us a clearer picture of how these bacteria help us stay healthy.

This knowledge gap inspired me to apply for a European Research Council (ERC) grant. Last year I was awarded with this prestigious grant, which provides funding to explore novel aspects about the ecology and evolutionary history of lactobacilli.

Lactobacilli are dominant colonizers of the human vagina, where they play a key role in women’s health. Among the lactobacilli, I consider the vaginal lactobacilli as ‘mother lactobacilli’. As you might have noticed from our recent reclassification of the Lactobacillus genus complex, the vaginal type strains Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii and Lactobacillus iners all belong to the Lactobacillus genus strictu sensu, because they are closely related to the first Lactobacillus species ever described: Lactobacillus delbrueckii subsp. bulgaricus, originating from yogurt. So, the study of vaginal lactobacilli could also be seen as a study on the basics of the genus Lactobacillus and what makes this group so important for human health.

At present, it is not well understood why lactobacilli dominate the human vagina under healthy conditions. Interestingly, this appears to be the case only in humans and not in other mammals. We speculate that it is because lactobacilli have beneficial functions and, when transmitted from mother to infant in early life, have a peculiar capacity to inhibit dangerous pathogens for our offspring, including group B streptococci, Enterobacteriaceae, fungi and various viruses. Lactobacilli also have interesting immune modulatory capacities. A rather unique feature in humans is the menstrual cycle and the estrogen-stimulated production of glycogen being a major sugar source for the lactobacilli in the vagina, resulting in high production of lactic acid, an excellent antimicrobial molecule against numerous pathogens. But the short answer is that we have no really clear answer to these fundamental questions of human biology.

Because the ERC funding allows us to be a bit more aspirational than in our usual research endeavors, we decided to address some of these questions by engaging women as citizen scientists. So we launched an ambitious citizen science project on vaginal lactobacilli and women’s health, named the Isala Project (see www.isala.be — it’s only in Dutch, but easily translatable with Google Translate 😊). The project is named after Isala Van Diest (1842-1916), the very first female physician in Belgium.

Our initial ambition was to ask 200 healthy women at different points in their menstrual cycle to provide vaginal swabs for microbiome sequencing and culture of lactobacilli. Our plan was to launch the call for volunteers on International Women’s Day (March 8, 2020), but COVID-19 made us revise our plans. We postponed our call until March 24, realizing that most women were at home during the lockdown. We assumed that since the national news was dominated by the SARS-CoV-2 virus, it was going to be difficult to reach out with traditional news channels. However, within two weeks, more than 5500 women registered for Isala on our website and we even had to restrict sign-ups!

We thought many women would still drop out if they found out they had to fill in an extensive questionnaire with intimate and lifestyle-related questions, but this was not the case. Almost 4700 women filled out the extensive questionnaire, demonstrating strong enthusiasm, commitment, and engagement. We decided to send a self-sampling kit to all the women who had filled in the entire questionnaire and supplied their postal address. Over the summer, we sent 4100 self-sampling kits, and of these, 80% of the women have already sent back their swabs to us. Our lab members are overjoyed with the citizen science enthusiasm!

Even though managing the logistics of the postal packages was a huge administrative challenge, we managed to keep everything straight. Thanks to an amazing team of dedicated and super-organized PhD students, lab techs, postdocs, master students, clinicians, bio-informaticians, statisticians, and communication partners, we can now say that we are around halfway through the project. We have been able to process all swabs that arrived to DNA extracts (for microbiome sequencing) and glycerol stocks (for the lactobacilli biobank and metabolomics later). Within the next months, these samples will be run on our MiSeq for 16S rRNA amplicon sequencing; the functional, genetic, and metabolomic characterization will of course take much more time. Making vaginal microbiome profiles for all these citizen scientists by next spring is now our priority, as we want to send all participants a personal update by then.

With this project, we are also changing up the traditional publication timeline: we are communicating about the process while not having all the results yet. We will inform the participants about their microbiome profiles before we submit or publish the related peer-reviewed manuscripts. This is because we want to actively communicate with our participants, opening discussions on the topic — and empowering women, without delay, to think about their vaginal health. We even have suggested conversation starters on our website and in the sampling boxes.

Time will tell whether these efforts will pay off for women’s health! Citizen Science can sometimes be surprising, but so far, we are very happy with the contact we’ve made with our committed and enthusiastic participants. We even have a hashtag, ‘#LetsSwab for the future’. I highly encourage my fellow scientists to consider organizing citizen science projects on topics related to the human microbiome, probiotics and prebiotics, because it is a unique way to get inspired and to do research on a large scale.

 

“A healthy woman, a healthy baby, a healthy generation” lessons learned from the 4th Annual Women and their Microbes Conference

/in featured, ISAPP Science Blog /by Mary Ellen Sanders

By Dr. Mariya Petrova, Microbiome insights and Probiotics Consultancy, Bulgaria

The 4th annual Women and their Microbes conference took place at the beginning of March celebrating the International Women’s day. The first-ever conference outside Europe in Hamilton, Canada brought together top scientists to discuss the importance of women’s health through the prism of women’s specific microbiomes. The theme of the conference was Microbiome Management in Pregnancy with a uniquely designed high-quality program translating the latest research into the clinical setting. I was honored to serve on the organizing committee for this meeting, and I provide highlights below.

Our health starts long before birth. The developing fetus receives information from the mother in the form of hormones and nutrients and uses these to predict the external environment. The fetus then uses this information to adapt its development to better its chances of survival after birth. However, the developing fetus can be “misinformed.” This happens through the maternal factors such as her use of drugs, stress, and diseases such as obesity and asthma. For example, both absolute maternal weight and weight gain during pregnancy affect microbiota development in infants (Carmen Collado et al., 2010). Maternal microbiota can also shape the immune system of the newborns. Therefore, keeping women on the right course before pregnancy and healthy during pregnancy must be a priority. This will later be translated into a healthier life for the infant through adulthood. Many of us associate healthy pregnancy with women taking the right nutrients and minerals such as folic acid, B12 vitamins, and iron and we are not wrong. But microbes also play an essential role in health. Microbes are a crucial factor providing nutrients, immune protection and regulating host physiology. Particular strains of Lactobacillus sp. and Bifidobacteria sp. can produce vitamin B12 and folic acid in the gut (Magnusdottir et al., 2015), which may be very beneficial during pregnancy. Of interest, this production increases when paired with prebiotics. Not only that, but microbes are increasingly recognized as important in reproduction, pregnancy, and development. Fertilization doesn’t happen in a sterile environment. Distinct bacterial communities are present in the female reproductive tract, but semen health and male fertility are also important (Weng et al., 2014). So don’t forget the “Y” in the equation – fathers also play a role in the health of their offspring. Gestational tissue microbes can also play an important role in development. More research is needed to better understand these microbiomes and the extent to which they can be influenced by maternal diet and health state.

What if the things go wrong – adverse pregnancy outcomes. Preterm birth is an ongoing challenge with rates steadily growing and with limited approaches for prevention. It results in 75% of neonatal morbidity and mortality. High numbers (55-80 %) of preterm births are associated with dysbiosis and a shift of the vaginal microbiota towards a more diverse state (Freitas et al., 2018). It seems likely that the vaginal microbiome can protect against adverse pregnancy outcomes. However, it appears that both antibiotics and probiotic therapy used to date are not effective at preventing preterm birth. “How to prevent adverse pregnancy outcomes?” is a million dollar question. We need a highly discriminatory diagnostic test that defines versions of ‘abnormal’ vaginal microbiomes. This test needs to be significantly associated with adverse health outcomes. The type of abnormal profile that results in preterm birth needs to be distinguishable from other possible ‘abnormal’ profiles. Such a diagnostic tool needs to be simple enough for a clinical environment and cost-effective. We need to have a safe intervention that can ‘treat’ or normalize a microbiome ideally preconception or early pregnancy.

Where do probiotics fit? Probiotics and prebiotics can enhance the nutrient status of the mother via increasing micronutrient and mineral absorption. During pregnancy, about 3.6% of North American women, 14% of The Netherlands women and 23% of Australian women consume probiotics. A lot of studies focus on the role of probiotics for preventing Group B Streptococcus infections, maternal obesities, postpartum depression, and mastitis. Although results are promising, more studies are needed to make clear conclusions and select the best strains for each condition. Importantly, currently used probiotics do not appear to pose safety concerns for pregnant and lactating women. Nevertheless, consumers’ knowledge regarding probiotics is not very precise. This confusion often may stem from a probiotic market with many different manufacturers, some of which are not legitimate, selling products that are not well defined, with very little clinical evidence. A major effort in educating clinicians, pharmacists and the consumers has been made by creating probiotic guidelines. Dragana Skokovic Sunjic has been working in the last ten years in publishing and updating the “probiotic chart.” The probiotic chart summarizes commercially available probiotic supplements or foods sold in Canada or the USA that have published clinical evidence for the particular strain(s) present in each product. Of note, for products containing multiple strains, evidence must be provided for the specified combination and not extrapolated from the evidence for the separate probiotic strains. At present these guidelines are used by primary care providers, specialists (pediatrics, GI), academic teaching hospitals, universities and others.

With the increasing number of microbiome studies, we are witnessing a paradigm shift in the scientific literature with more people focusing on the importance of microbes in human health. Women’s health is a cornerstone for successful reproduction, with important implications for the health of the next generation. Initiatives such as Women and their Microbes are crucial to link the science and medicine together to bring awareness within the healthcare and academic community.