Environmental Toxicant Exposure and Your Reproductive Health with guest Dr. Kevin Osteen

Dr. Kevin Osteen is one of the premier scientists investigating endometriosis and environmental toxicants:

He is a professor of OBGYN, and pathology, microbiology, and immunology at Vanderbilt University School of Medicine, and also an adjunct professor of OBGYN at Meharry Medical College. He currently holds a Pierre Soupart Chair in obstetrics and gynecology. He also directs the International Endometriosis Association Research Program at Vanderbilt, and has served as an advisor to various biotech and large pharmaceutical companies.

Since the 1990s his research program has focused on the relevance of environmental endocrine disruptors in the pathophysiology of infertility related to the disease endometriosis.

His recent research efforts in his lab have begun to use recently developed “organ-on-a-chip” technology to create the first endometrium and endometriosis chip models. These models provide a comparative system in which to investigate the intrinsic properties and hyperinflammatory state of a normal and endometriosis endometrium that promotes disease progression.

Dr. Aimee: Welcome to the show, Dr. Osteen. Would you tell us more about what you do and what your focus is, and what brought you to OBGYN as well?

Dr. Kevin Osteen: That part is quite a story. I came to Vanderbilt to start the fourth IVF program in the country at that time. I was a post-doc in Baltimore with a lady who is a fairly famous ovarian physiologist and was mostly an ovarian physiologist by training. My PhD is in endocrinology, actually. So, when I moved to Nashville, to Vanderbilt, I had to really start an IVF program based on science that was developed mostly, at that time, back in the mid-1980s, by a lot of animal science people.

We had to develop clinical laboratory credentials for PhDs in animal science to be able to run human-based laboratories. We wrote an exam, which is called an HCLD, or high-complexity clinical laboratory director. Most people who run IVF laboratory, embryologists, have taken that exam or a version of it.

I was working with the chair of pathology at Vanderbilt, and he stopped by my lab one day and asked me if I would help him culture endometrial cells. He knew I had cultured ovarian cells. I said sure. I was listening to the Brandenburg Concerto late on a Sunday night. He stopped by first to listen to the music and then we talked some science, and hooked up as a nice team back in the ’80s to develop the technology to culture human endometrial tissue.

That allowed me to look at an end organ response from what the ovary was producing in terms of steroids, estrogen, and progesterone. But people didn’t know as much about the endometrial response during the early IVF days, and that was something that needed more study. More importantly, my sister-in-law, who had endometriosis, asked me to do it as an area of study, and I would not tell her no. That’s how I got into endometriosis, an ovarian physiologist learning how to culture endometrial cells.

Dr. Aimee: Much of your work has been around endometriosis and how endocrine disruptors impact reproductive health. Can you share what your findings have been and what they revealed about the link between toxicants and endometriosis?

Dr. Kevin Osteen: Yes. That whole story started in the early 1990s with a study that had been in primates that were involved in a feeding study with the toxicant we study, which is commonly called dioxin or TCDD. What had happened, that was not an endometriosis study, but ten years later several of the female primates died. When they did the autopsy, we were involved in that, and they had deep infiltrating endometriosis into the bowel, so the animals had bowel obstruction. It was a more invasive phenotype of endometriosis than you would typically see, certainly in a primate colony.

That piqued everybody’s interest. I was sort of brought in by the Endometriosis Association partners and asked if we could figure out maybe what was going on. My lab at that time studied enzymes that allow cells to become invasive, such as cancer cells, they’re called matrix metalloproteinases. Our lab at that time did the first study of these matrix metalloproteinases, or we called them MMPs, in the human endometrium. We published the first study of how they were expressed during the normal menstrual cycle and how these enzymes became expressed during menstruation, but they were suppressed by exposure to progesterone, which is the pregestational hormone that creates the endometrial environment that allows implantation and preserves the endometrium during and throughout pregnancy in the human.

By finding that progesterone was involved in suppressing the enzymes, then we looked to see maybe this toxicant was somehow interfering more with progesterone than it was acting as an estrogen mimic. That’s how we approached the early studies using our human in vitro culture models, and we were able to demonstrate that this toxicant was a pretty good inhibitor of progesterone’s ability to regulate the MMP system and that then would allow endometrial cells to potentially exhibit a more invasive phenotype.

That’s how we got started in the toxicant of interest to us of the dioxin studies.

Dr. Aimee: Where can dioxin be found in the environment?

Dr. Kevin Osteen: Dioxin is a member of a family of toxicants. People have heard of PCBs before. These PCBs were actually used in things like transformers and industry sort of uses. They’re really persistent toxicants. They’re not used anymore in the transformers or heat exchangers, like they used to be. Dioxin is also created as a product of combustion. If you follow the studies about this, you would see that it’s not really generated as something that anybody wants to make, it’s a byproduct. It’s one of the more toxicant of the PCB family.

Currently, for example, humans who would be exposed at a high level are soldiers in Iraq or Afghanistan, because of oil fires and burn pits. It was also a contaminant in Agent Orange during the Vietnam War, so the soldiers that were spraying Agent Orange could have been exposed to fairly high levels.

Our interest in terms of the women with endometriosis then also extends to where you live, and that could have an impact on level of exposure. These toxicants get into the food chain, so we ingest them in food and water. Then they’re carried by weather patterns, so they can accumulate. In the United States, the weather pattern would take a lot of these across New England, for example.

Dr. Aimee: What’s the difference between a toxicant and a toxin? You hear people talk about environmental toxins and we’re using the term toxicant. Can you clarify the difference for us?

Dr. Kevin Osteen: Yes. We started thinking of them as toxins, but really when we started studying it from the chemical perspective and the chemists, a toxicant is something that is being produced by some process, such as combustion, whereas toxins are generally produced by various animals as defense mechanisms. Snake venom is a toxin, for example, and certain frogs produce toxin. So, they’re defense mechanisms that animals would use, those are toxins.

Dr. Aimee: You recently published an article titled Early Environmental Toxicant Exposure and Reproductive Health, and you covered some really fascinating new ground in the field, and I love that you’re here to talk to us about it. Some of what you discovered was how toxicants can impact reproductive health in a transgenerational capacity.

Before we get to those findings, I want to make the audience understands the organ-on-a-chip technology (or endo-chip) that you’re using to model human endocrine systems. Can you explain to us how that works?

Dr. Kevin Osteen: Yes. Basic culture models that people have used have cells in a static sort of location. So, a tissue culture model would be you put cells in a petri dish and then you change the media every once in a while. Those cells are really not representative of cells in an organ in the body in which blood and nutrients roll across an organ system and then the waste is carried away by the vacillatory and organ system. The organ-on-a-chip technology allows us to have a microfluidic flow of nutrients and culture media through a culture environment that is more representative of how an organ is exposed to products of the blood or hormones in the blood.

I don’t know if you can see it if I hold it up, but that’s an organ-on-a-chip model of the endometrium. They’re called microfluidic because they’re very small. It allows small volumes of culture media and then you have a pump system that can be devised to deliver nutrients to your cells, but you can also expose the cells to toxicants or to hormones in order to test the impact of the toxicant.

Of course, if you do toxicology in people, everything we know is from retrospective accidental exposure. You don’t expose people on purpose to a toxicant that you know could be detrimental. The only way other than animal models that we can really study in a prospective fashion what a toxicant might do to an organ system is to have a three-dimensional in vitro system that mirrors the way cells are responding to hormones or toxicants in the body.

Dr. Aimee: What have you discovered about the endometrium by studying it on the endo-chip?

Dr. Kevin Osteen: The main thing we were able to do and demonstrate is that the toxicant that we study actually acts on human endometrial cells to epigenetically modify progesterone receptors. Now, I’m going to have to define epigenetics, I think, for your audience.

We all know that we have genetics that we got from our parents and we have genes that we got from our fathers and our mothers. Epigenetics means on top of genetics. Epigenetics is ways in which the gene can be modified so that it’s expressed or not expressed. As organs develop, the liver doesn’t need the same proteins made as the heart does, so they’re natural mechanisms by which certain genes are suppressed in the body along the line of differentiation to a special tissue.

It turns out that epigenetics is also a mechanism by which toxicants can act to modify the expression of really important genes. What we were able to show, and other colleagues in the field, was that the toxicant epigenetically modifies the promoter region of the progesterone receptor gene and makes the progesterone receptor itself to be expressed at a lower level.

As a physician, you know that women with endometriosis have this resistance to progesterone. We can generate that endometrial phenotype in the laboratory using the organ-on-a-chip technology.

Dr. Aimee: Is epigenetics similar to transgenerational? Do you use those words synonymously? What’s the difference between seeing something as epigenetically versus transgenerational risk?

Dr. Kevin Osteen: One of the things that we were able to do in the lab — again, we cannot do exposures to human populations, we always do that on the organ-on-a-chip model or cultures — but we do have a mouse model of exposure during pregnancy in which we expose a pregnant mouse to this toxicant at the end of her pregnancy.

Then she has her babies that are born, and those babies would be called the F1 generation. There’s the mom, that’s the F0, the babies are the F1. Then when you expose the mom during pregnancy the babies are exposed, the fetuses are exposed, and then the germ cells in the ovaries of the babies that are born were also exposed. Those would become the F2 generation of mice.

When a pregnant woman is exposed to a toxicant, she is exposing herself, the baby, and the germ cells in the baby that are going to become the baby’s babies all at one time. That’s called multigenerational.

To get to transgenerational, you have to actually go to the F3, which are the great-grandchildren. Those are the first offspring that were not directly exposed during that initial pregnancy. That’s called transgenerational as opposed to multigenerational.

In our mouse model, the babies have a phenotype which is not unlike the phenotype of the F1 babies which were directly exposed to the toxicant. There are no other exposures except for that first pregnancy, and the third generation still carries a reduced sensitivity to progesterone and an increased risk of infertility and increased risk of preterm birth if they are fertile. This is what we, sadly, identified is that the exposure foreshadows problems across several generations, and you don’t have to have a direct exposure.

Dr. Aimee: Right. I understand how the technology will be used to help fertility patients by what you’ve already shared, but can you share with our audience how can we use this technology to improve fertility outcomes for people moving forward?

Dr. Kevin Osteen: One of the most important things we found, I have a colleague named Dr. Kaylon Bruner-Tran, if you look at my publications, you’ll see hers as well. She’s interested in the male. We’ve identified that the male babies have their own infertility phenotype, they have reduced sperm production, reduced sperm quality.

The thing for your patients that I think is most interesting and not always understood is that the placenta of pregnancy is derived largely by the paternal genes. So, the dad’s exposure can change the phenotype of the placenta. In our animal model, it didn’t matter whether the mom was the exposed animal or the father was the exposed animal, we got the same transgenerational phenotype.

When I would talk in front of endometriosis patients, often their fathers would go somewhat white when they heard that maybe their daughter is suffering from endometriosis because of something in their background. That’s often not appreciated. One thing to understand is the father’s history of potential toxicant exposure should be taken as part of the history of the patient when they’re counseled for an IVF procedure.

The other thing was the more hopeful component. We’ve been able to nutritionally intervene in the animal model as a proof of principle and reduce the risk of infertility and preterm birth in the offspring. The reason that works is because of the anti-inflammatory diet that’s a more healthy diet. That’s something that I think your patients would appreciate and want to know.

In general, our diet is an inflammatory diet, the western diet is not particularly healthy in terms of it being an inflammatory diet with the amount of red meat, sugars, corn syrup in particular. The original hunter-gatherer diet would have been 50% omega-3 50% omega-6. You need both, but American diet can be 30–1 omega-6 to omega-3.

In terms of having an anti-inflammatory diet or a healthy diet, prior to the initiation of pregnancy would be the advice that we would give from our observations. Many people show up once they’re pregnant to their gynecologist or the MFM and they don’t really plan for the pregnancy. It would be much better if we all planned for healthy pregnancies and adjusted our diets and other ways that we take care of ourselves, emotionally, exercise, diet, and general wellbeing before you become pregnant would be ideal. That’s not always possible, but ideal.

Dr. Aimee: You also mentioned taking a careful history on the sperm source. What kind of questions should I be asking to make sure that I’m not missing something really important for my patients?

Dr. Kevin Osteen: It’s one of the things that’s most difficult to answer definitively because, in animal models like we study, we can put the animals on a special diet and they have no other choice. They can’t go out to McDonalds on the weekend or whatever that they might want to do. With people who eat a lot of different foods, they may exercise or not, they may not be aware of the toxicant history that they might have, what their father or even grandfather or grandmother might have done. It’s very difficult, nobody can go back and change what their father or grandfathers or grandmothers did.

In general, we believe that probably dietary intervention is the easiest simplest thing that people can do for themselves.

In our world, like I said, we don’t do prospective human exposures to toxicants that we know might be harmful. The data would say that women that live within 4 kilometers of an incinerator have a higher risk of preterm birth, for example. Those kinds of studies would say they looked at the women, they looked at the medical history, but did anybody ask about the father, where did he live, probably there as well, and the history of the entire family unit.

Some of the people obviously can’t move because of where they live. Again, Meharry Medical College where I have the adjunct appointment, is one of the top minority-focused medical schools in the country. Social justice and environmental justice is something they think a lot about. Our students from Meharry know that women of color would have twice the risk of preterm birth as Caucasians. We don’t know all of the genetics or epigenetics about that, but we do know that where you live and your access to nutritional food can make a difference.

Those are the things that I think we can control more than our history, what our parents and grandparents did.

Dr. Aimee: The information you’re sharing with us today is extremely important for all of my patients to hear. Even if you’re not my patient, for people who are planning a pregnancy, I feel like it’s vital for people to know. Thank you for all of the work that you do.

I want to go back to the endo-chip and how eventually we could use this technology to improve fertility outcomes.

Dr. Kevin Osteen: With the chip, one of the things that we’re doing, and we have some new funding by the Bill and Linda Gates Foundation, to have a chip that’s called the endo-chip married also to a chip called the MFI-chip, the maternal-fetal interface. The Gates Foundation has interest in contraceptives, for example, but every contraceptive has a failure rate. What happens if you test that contraceptive in a chip device that would mirror the beginning of a pregnancy, then we could see this particular contraceptive would be more detrimental to an early pregnancy even though it might be a reasonably good contraceptive.

That’s not what you’re trying to do in general, but that’s an example of how you can test a drug before it would go into clinical trial using a human tissue-based model so that you don’t get into trial and have a bad outcome, you could pick that up by testing it directly in a reproductive system.

Of course, the organ-on-a-chips in general, there are several organ-on-a-chips that we have within our biomedical group at Vanderbilt. There’s even a brain-on-a-chip, for example. You’re able to see how organs interface. We put a liver-on-a-chip upstream of our endometrium-on-a-chip so that we can test the metabolites of a drug or a toxicant that comes across the liver, gets metabolized, and then affects the next organ system. Those kinds of interactive organ-to-organ communications can be done in an organ-on-a-chip system before you would ever do those trials in a human population.

The organ-on-a-chips, for all of us who do care about the use of animals in research, it lets us reduce the use of animals for research, which is really important.

Dr. Aimee: Are there any tips or words of wisdom for people who are listening to us today who have endometriosis or who are worried about toxicants in the environment?

Dr. Kevin Osteen: Yes. I think that being aware of where the toxicants are being generated, being aware of the foods that you eat, trying to avoid having an inflammatory diet, thinking about that.

For example, we have colleagues in Japan. They don’t have landfills, they incinerate all of their trash. So, they have a whole institute building that is dedicated to the toxicants that we study, because they would really be concerned about that. What they’re looking at, there are ways that you can chelate a toxicant and remove it from the body.

But to me, that’s way downstream from what we should be doing in terms of just taking better care through choosing the foods that we eat. I know you have to advise your patients about they should eat more fish for good omega-3s, but certain fish, the top of the food chain fish like sharks or tuna, will have more toxicants that they accumulate, because of all of the smaller fish that continue to accumulate. While you do want to have a fish-rich diet, you want to be choosy about the type of fish that you would eat. Of course, you can take fish oil. Several people in my group do that.

I think it’s a matter of taking care of your body nutritionally and being aware of where the toxicants are being generated. There’s a lot of good information on the web about the toxicants and what you might not want to do in terms of your own exposure.

Things like grilling meats is one way to create some of these toxicants. Obviously, smoking is one way to generate some of the toxicants. We can use the cigarette smoke extract in our organ-on-a-chip model and we get the same impact we get from exposure to the dioxin. So, there are some personal choices we can make to reduce the toxicants that we can choose not to do as much of. Then there are nutritional interventions, choosing an anti-inflammatory diet, that can work against the toxicant.

The toxicant that we study, without getting too much into the cell biology, seems to do its negative work by creating a proinflammatory cytokine storm within the endometrial cells and the immune system. The proinflammatory cytokines seem to be doing the dirty work of the toxicant downstream from the exposure. That’s why we say we’re always focused so much on anti-inflammatory intervention.

Dr. Aimee: I’m not sure if you’ve ever been approached by any documentarian to document everything that you’re sharing and then actually show people what happens when you expose the endo-chip to the different things that you’re sharing and then showing people what happens. I feel like if people actually see it, they will believe it, rather than me just talking about it and saying things like it’s bad for your sperm or it’s bad for your eggs. I feel like if I could say, “Click here and watch this video, and you’ll see exactly how bad it is.”

Dr. Kevin Osteen: That’s right. The visual part of this, when we can show immune cells tracking to the endometrium, tracking to endometriosis and creating this proinflammatory macro environment that would drive the disease process.

There’s an area of research, it gets a little more technical sometimes, but most people are aware that when you get a vaccine — now with COVID, everybody is thinking about this — that you get some immunity to the virus, to Coronavirus, for example. But there are areas of immunity where if you were vaccinated against one sort of candida type infection, then you could have immunity develop against another even unrelated infection.

This is a new concept called immune cell training that shows that innate immune cells, which are the first line of defense as opposed to acquired immunity, which is the antibodies and secondary sort of protection, that innate immune cells remember their exposure to an infection, and the next time they’re exposed, they have an altered reaction, a more defensive reaction generally. That would be a hyperinflammatory response. But some things can cause the immune cells to have a reduced expression, which would be a hypo response. That could be like diminishing immune response to a cancer, where the cancer causes the immune system to be less effective in attacking the cancer cells.

This immune cell training appears to be very similar to the immune reactions we’re seeing to the toxicant, so we’re currently looking at how much of the risk for endometriosis is being carried by immune cells themselves and could that even be part of the transgenerational effects that we’re seeing. Dr. Bruner-Tran can show the babies that are born to her mice would have more necrotizing enterocolitis because of their mother’s or father’s toxicant exposure.

I think we’re going to see more and more of immunomodulation that can be pharmaceutical going forward. We use dietary because pregnant women don’t need too many pharmaceuticals, as you know, and they haven’t been tested in pregnant women for the most part. That’s why we say nutritional intervention. But in the father, before the pregnancy, an anti-inflammatory drug could potentially be useful. I think downstream immunomodulatory mechanisms are going to be more and more involved in preventing the development of endometriosis.

Dr. Aimee: That will be a great day, because endometriosis is one of the worst things that as a fertility doctor I deal with. As you know, it causes the ovaries to age faster than my patients’ chronological age. No matter how good their fertility levels are or how young they are, if endometriosis is present, it can really cause a lot of damage, decreased risk of implantation, increased risk of miscarriage. So, I appreciate all of the work that you’re doing.

Is there anything else that you want to share with our audience?

Dr. Kevin Osteen: One of the things I think you touched on just a little bit is our goal would be to be able to identify the risk of the young woman or the young man prior to them developing endometriosis or a related inflammatory condition, and then being able to intervene effectively so that they never become the endometriosis patient. We would like to put you out of business.

Dr. Aimee: That would be amazing. If we could literally find a cure before it even became a problem, that would be literally a dream come true for me.

Dr. Osteen, thank you for joining us on The Egg Whisperer Show. For people who want to read more about you and your research, where can they go?

Dr. Kevin Osteen: They can contact me directly, so we can try to answer as many questions as possible. I’m just Kevin.Osteen@vumc.org, and I can send the question along to our clinical partners when it’s appropriate. They can Google me and find some of this work out there as well and stuff you can do.

Dr. Aimee: Thank you so much for your time. Thank you for your dedication to this field. I so appreciate you. Thank you.

Dr. Kevin Osteen: You’re welcome. My best.

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