Exploring the Relationship of Skin Pigmentation to Cardiovascular Health

Penn State undergraduate student Samantha Muller interviews Postdoctoral Fellow in Physiology Tony Wolf about his research on variance in cardiovascular responses to thermal stressors. Tony is particularly interested in understanding the various factors underlying population disparities in cardiovascular function that lead to increased risk of cardiovascular morbidity and mortality. Among these factors are skin pigmentation and socioeconomic background.

HOST:
Samantha Muller, Penn State undergraduate student in Forensic Science, with a minor in Anthropology; member of the MicroARCH Lab 

GUEST:
Dr. S. Tony Wolf, Postdoctoral Fellow, Penn State Physiology 

Transcript

Mark Shriver:

From Penn State’s Center for Human Evolution and Diversity, this is Tracking Traits

[MUSICAL THEME]

Mark Shriver: 

Hello and welcome to the sixth episode of the Tracking Traits podcast. I’m Mark Shriver, co-director of CHED – the Center for Human Evolution and Diversity at Penn State University. 

Nina Jablonski:

And I’m Nina Jablonski, the other co-director of CHED. Welcome to the podcast. 

Mark:

For today’s episode, Penn State undergrad Sam  Muller returns to the podcast to do another interview for us.

Nina:

Sam is majoring in Forensic Science with a minor in Anthropology and aspires to become a forensic pathologist. 

Mark:

She also used to work in my lab researching human phenotype variation. For Tracking Traits episode 4, Sam interviewed Natalia Grube about her research on the coevolution of tapeworms and the human diet. 

Nina:

For this latest episode, Sam goes in a completely different direction with Tony Wolf, a postdoctoral fellow in Physiology here at Penn State who is interested in in human body temperature and cardiovascular responses to thermal stressors. 

Mark:

Tony is taking a hard look at some really touchy material. He’s applying a critical lens to the way we categorize people in terms of their susceptibility to cardiovascular diseases as they relate to skin pigmentation. 

Nina:

This is a topic close to my heart, as you know Mark, since so much of my work revolves around the evolution of skin color and related health issues. There’s that relationship between Vitamin D absorption from the sun, and the amount of melanin in people’s skin that’s so important from a health perspective. 

Mark:

I know Nina, it’s great to see Tony exploring this area in his own way. He’s got this focus on the disparities we see in cardiovascular disease, and he’s got this new way of measuring vascular function that’s minimally invasive because it focuses on the microvasculature – those small blood vessels close to the skin. 

Nina:

And Sam does a great job asking Tony about all these related dimensions to this research, like the way that race is exposed as a racial construct. Because when we look at the way the American Heart Association looks at data, it’s not by relative darkness of skin pigmentation, which may be the best health indicator – but by race, which doesn’t necessarily have anything to do with melanin or Vitamin D absorption from the sun. 

Mark:

And this of course brings up other social dimensions like indoor vs. outdoor lifestyles, and economic disparities among people of different colors, and all the intersecting dimensions of this topic.

Nina:

And to top it off, there’s Tony personal story of transformation. He was a business major with a passion for motorcycle racing who had a bad accident that changed the whole direction of his life. 

Mark:

Well let’s not give too much away.

Nina:

OK Mark, good point! Let’s let the listeners hear it for themselves. Here’s Sam Muller interviewing Tony Wolf about his research exploring the relationship of skin pigmentation to cardiovascular health.

[MUSICAL INTERLUDE]

Samantha Muller:

Thank you so much for joining me today, Tony. Just to start it off, I'm going to have you introduce yourself. Tell me a little bit about you, about what you're interested in, and then just give me a little elevator pitch for your research.

Tony Wolf:

My name is Tony Wolf. My official PhD is in exercise physiology, technically, but I'm really more like an integrated physiologist. I'm particularly interested in better understanding individual characteristics that may predispose people to developing cardiovascular dysfunction and cardiovascular disease.

Samantha Muller:

Could you give us some examples of cardiovascular illnesses that most people would be aware of?

Tony Wolf:

Yeah. Cardiovascular health in general just refers to the health of the heart and the blood vessels. So, cardiovascular diseases like coronary artery disease, cardiomyopathies, heart failure and heart attacks, at the more extreme end of the spectrum. More recently, more and more researchers have been starting to think of diseases like Alzheimer's disease and dementia as being cardiovascular in origin because individuals with cardiovascular disease are at increased risk of developing dementia and Alzheimer's. The   decreased perfusion of the brain that comes with cardiovascular diseases might be what's leading to the development of Alzheimer's and dementia. So, cardiovascular disease is pretty far reaching. 

Samantha Muller:

What kind of studies have you personally been doing in this general field?

Tony Wolf:

My research to this point has really been focused on the skin microcirculation. So, the really small blood vessels in the skin. And what's interesting about the skin microvasculature is that the function of the blood vessels within the skin are reflective of the function of small blood vessels throughout the body. And it's much more accessible and less invasive to actually study the skin microvasculature than blood vessels in the kidneys, for example, we can't really access those in humans.

 So, we use the skin microvasculature as a model for overall cardiovascular health. And so, we can very easily and again, with minimal invasiveness, do pharmacological interventions directly to the small blood vessels in the skin and see how those interventions influence vascular function in various populations. And so, that's kind of what our lab does, and my specific interest has been looking at the interactions between skin pigmentation, UV radiation exposure, like what we get from the sun, and skin microvascular function.

Samantha Muller:

Awesome. So, you mention  how you're working in different populations and with obviously this social construct of race being really based heavily off of skin pigmentation. How has that impacted how you've gone about studying this or studying these traits?

Tony Wolf:

So, there's been a lot of really, really good and important research in that kind of area, looking at so-called racial differences in cardiovascular health and in vascular function. And so, there are other lab groups who have used the skin microvasculature similarly to what we do, to try to pick apart the mechanisms of cardiovascular dysfunction in for example, the African-American population.

But as you noted, race is really more of a social construct and doesn't really have any basis in actual biology. So, my interest has been in starting to get at the underlying factors that might lead to those differences between populations and with, again, with my specific interest in how the skin may interact with the sun to influence vascular function. And so, a really important component of that, that most people are familiar with is the role of the sun in stimulating the production of vitamin D.

So, increased melanin in the skin absorbs UV radiation from the sun, making it less effective at producing vitamin D in those with more darkly pigmented skin. So, I've kind of tried to take research that's been done to better understand the mechanisms by which the African-American population has reduced cutaneous or skin microvascular function, and run with that to see if skin pigmentation and vitamin D status may explain those differences at all. 

Obviously, I don't think that vitamin D explains the whole variance between groups. So, there are obviously other factors that may influence cardiovascular health, like socioeconomic status-related factors, availability of healthy food, availability of space to do physical activity. So, there are so many different factors, but my focus has been trying to encourage people to get at those underlying factors rather than focus on the just race differences.

Samantha Muller:

So, what is the current understanding of the trends in regards to skin pigmentation and cardiovascular health?

Tony Wolf:

In terms of the actual role of skin pigmentation, there's not really much that's been done that I'm aware of, other than what we've been doing in our lab recently. We published a study last year, looking at the effects of vitamin D supplementation on skin blood vessel function in darkly pigmented African-American adults who are young, college-aged, otherwise healthy, and their more lightly pigmented European-American counterparts. And we found, similar to what other groups have shown, that the African-American group had reduced skin blood vessel responses to a skin heating stimulus.

If we heat the skin, we see increased blood flow in those skin blood vessels,   and the magnitude of that response is a good index of vascular function. And so, we showed similar to other groups, that the African-American group had reduced responses compared to the European-American group. But if we supplemented them with vitamin D for four weeks, that we could improve their vitamin D status, which was also lower than in the more lightly pigmented group. We could improve their vitamin D concentrations in their blood and that also resulted in an improvement in their blood vessel responses to skin heating. So, now we've moved on from that and been testing a more broad cohort of people with a broad range of skin pigmentation of all kinds of, I guess, racial background.

Unfortunately to this point, people haven't really thought about race as just being people with differently pigmented skin, very much. So, the data that come out, so the American Heart Association always updates prevalence trends of cardiovascular disease and hypertension, and they split it up by races, but they don't split it up by skin pigmentation per se.

Samantha Muller:

Yeah. Gotcha.

Tony Wolf:

Yeah. So, you have to extrapolate the skin pigmentation based on the recorded race of the participants. Yeah. So, I think that there's a lot of work to be done there to like I said, start to get at the underlying factors rather than just looking at the effect of race.

Samantha Muller:

Have you had any challenges conveying that information because the public so heavily ties skin pigmentation and race and often has difficulty separating it.

Tony Wolf:

So far, my experiences have been very positive, that people have been pretty accepting of the limitations of just looking at race, but to be honest, most of those conversations that I've had to-date, have been with other scientists. And so, they can see the validity of what I'm saying. I think we're starting to get the message out there and so, the verdict is still out to see how well it's received.

Samantha Muller:

So, since you're kind of starting that trend, what would you want the general public to perceive from your research?

Tony Wolf:

I would really love to see people get past the concept of race, not look at each other as being of different races, but just as people of differently pigmented skin, because that's really ultimately what we're talking about. And again, obviously there are other potential factors that are influencing cardiovascular health that's not really based in biology, potentially skin pigmentation, but other than that, the potential socio-cultural influences are probably more important, but race is unimportant.

Samantha Muller:

Yeah, definitely. So, as you said, obviously your research deals a lot with human diversity as a whole and not just in a cultural sense of human diversity, but a real phenotypic sense of human diversity. So, what have you done in your research planning and just when you build your team and when you're conducting these studies to frame your research through the lens of diversity?

Tony Wolf:

The stuff that we're doing right now is, as I said, really including a very diverse cohort of people just with a wide range of skin pigmentation without really any thoughts of race, so it's just the influence of skin pigmentation. And then, we're also including metrics of socioeconomic status and stuff like that, to try to better, as I said, try to better get at those underlying mechanisms or factors that are resulting in reduced vascular function. Again, because it is such a diverse cohort, I think that hopefully it will promote overall diversity just by again, trying to show that these aren't racial differences, they're something else.

Samantha Muller:

How would you say that those socioeconomic backgrounds are tied to things like cardiovascular health, right? So, is it access to food? Is it the lifestyle? What elements of that background are you looking at?

Tony Wolf:

I think that all of those are factors that need to be further studied and addressed. So, there's certainly research out there showing that all of these things influence vascular and cardiovascular health. So yeah, access to food, access to good healthcare, daily psychosocial stressors. So many factors that all have been shown to have associations with cardiovascular health. And some of those factors have had more mechanistic investigation associated with them. So, there was a postdoc in our lab while I was still a PhD student here, Jody Greaney, and she's still doing this kind of research. She's interested in the influence of depression and psychosocial stressors on, again, on skin microvascular function.

And so, it may be that serotonin is an important signaling molecule for promoting normal blood vessel function. Yeah, there are so many different factors that can be addressed and there's certainly no perfect study that can address all of these things. In terms of how to get at those factors, it definitely becomes tougher. It can become pretty muddled, right?

The socioeconomic status questionnaires that we have been including, they include just generally, just a few questions about childhood and a few questions about adulthood, socioeconomic status, income, education. It's just more simple questions like that, but there's a lot of room to go deeper with all of that. And I think that the more things that you're able to include in a study, then you can take that and look at it from a more multi-variate perspective and look at the potential contributions of each factor on vascular health. But yeah, it can get tough for sure.

Samantha Muller:

Yeah, I can see how that would be a little bit difficult to pry apart. In addition to that, I feel like a lot of the socioeconomic factors and backgrounds that you're talking about are often tied to race, especially just in culture today. So, how do you go about studying those risk factors across racial lines? So, common risk factors in all of humanity and not just one specific race.

Tony Wolf:

Yeah. So, there are certainly ... I'd say that most risk factors are shared among racial groups. There are some that are maybe unique to certain groups or that are experienced to a greater degree, that's for certain. So, a lot of the research that's been done in the research that's more directly related to what I've been doing, has been done in young, healthy college students. So, there's certainly a selection bias there, right?

So, there could definitely be a lot more to be done with a wider range of people from different backgrounds outside of universities obviously, more rural communities potentially, inner city communities. And I think that, that's something that needs to be done, is to try to include more people from a more broad range of backgrounds to better get at how those overlapping risk factors may be influencing the disparities that we're seeing.

Samantha Muller:

Yeah. So, you would say not only getting more data, but really diversifying that data is important?

Tony Wolf:

Yeah. Certainly.

[MUSICAL INTERLUDE]

Samantha Muller:

So, in a different sense, as a whole humans are very increasingly spending more time indoors, not just because of obviously the pandemic that we're in right now, but just in the age of digital technology, offices are indoors, all of this stuff. So, how is your research relevant to this cultural shift in all of humanity?

Tony Wolf:

Obviously, the more time we spend inside the less we're being exposed to the sun and if you're just not getting enough sun exposure to promote adequate vitamin D availability, then those people may need to supplement with vitamin D regardless of their skin pigmentation. And there are so many factors that go into this, not only how much time you're spending indoors, but also regional differences. So, here, we're in the Northeastern region of the United States, where a good chunk of the year, even if you're going outside a lot, the UVB component of sun exposure is not enough to actually stimulate vitamin D production in the skin.

And then, if you spend a good chunk of the other seasons indoors, then you're likely to be vitamin D deficient all year, potentially. Again, if you're in other regions where the UV radiation intensity is higher than you might be a lower risk. And then again, the skin pigmentation question comes into play. And so, there are a lot of factors, whether you live in more of an inner city area where sunlight doesn't reach the ground as well because of tall buildings. And so, there are so many factors that go into this equation. Yeah, I think that there's a good case to be made that a lot of people would benefit from vitamin D supplementation regardless of skin pigmentation. But then of course, there comes the question, how much differently pigmented people may need different levels of how much they need to supplement vitamin D?

Samantha Muller:

Definitely. Yeah. That's a really interesting thing to think about. As you were telling me about this research that you're doing, I can't help but notice how interdisciplinary it is. It really is combining a lot of different elements from very different, you would think, areas of science. So, you have a lot of your physiology, which is very science heavy. Then you also have this anthropology element that ties in that cultural sense of diversity. So, I guess, my question to you is how do you think your background has influenced your ability to work in such an interdisciplinary niche?

Tony Wolf:

Yeah. It's so important to promote the interdisciplinary research programs, and I've been really fortunate to work with amazing people in physiology and anthropology. And having those different points of view going to address certain questions is so important because if you just have a narrow frame through which you see your research, then you may never ask the best questions, right? And so, when I was developing this current research, it seemed so obvious to me, that it was like, why has this not been done? Right?

But it's because I think again, people stay inside their niche and the focus can be a little bit narrow. And so, if you start to include people with broader backgrounds and different ways of thinking and learn from those people and work together, then you can do really great things. And so, yeah, I think during my PhD studies, I was so fortunate to work with those people and help mold the way that I think about these questions.

Samantha Muller:

Definitely. Can you talk a little bit about your educational background and how you got into this field of science?

Tony Wolf:

Yeah. It's a long road to get to where I am. So, I was never really that great in school. I just never really tried that hard growing up and I went to college because I thought I needed to go to college, but I didn't know what I wanted to do. So, I was a business major for a couple of years and very, very far from a stellar student, let's just put it that way. And I raced motorcycles my whole life and ended up getting hurt really badly. And during the recovery process of that, I really came to appreciate the positive effects of exercise for both physical and mental health, and that made me decide to change my area of study, to study exercise science and exercise physiology.

And so, that's eventually, I did my master's degree in that area and it brought me here to Penn State to do my PhD. And I mean, it's evolved quite a bit because most of my research now, it's not exercise related necessarily, but yeah, it was a long road to get here, but fortunately I made it.

Samantha Muller:

Yeah, definitely. Can you talk a little bit about how Penn State as a whole, but then also both Chad and any mentors that you've had here, have helped you on that research journey?

Tony Wolf:

Penn State has just a really great, vibrant, productive research community. And there was a survey that came across my email the other day, some study that was done showing that Penn State has some of the top programs in the country in kinesiology and anthropology. Again, those are the two departments that I'm really involved with. And so, Penn State's a really great place to be doing the kind of research that I'm doing.

And then, I've had really, really great mentors during my time here with my PhD advisor, Dr. Larry Kenney, who's a world leading expert in thermoregulation and microvascular physiology, and he's just been great to work with. And also, working with Dr. Nina Jablonski within the anthropology department has again, really changed the way that I think about the research questions that I have. Like I said, I've been really fortunate to work with really great people and great departments at Penn State.

Samantha Muller:

Yeah. It's a great community and we're happy to have you here as well. So, what do you see for the future of not only your research, but your scientific field? Where would you like it to go?

Tony Wolf:

It's a tough question. I kind of want to continue on this path that I've been on, trying to get at those underlying factors that result in disparities in cardiovascular health. So, there's a lot there, like we've talked about throughout this discussion, there's a lot of work to be done. And I just want to keep trying to chip away at that. In terms of the general research field, I think that there's more and more push to understand really, at the individual level, what factors may be predisposing individuals to the development of cardiovascular disease and dysfunction.

There's a lot of focus on genetics. That really microscopic level of what's going on, but I think you can get as deep as looking at the genetics, but you can also zoom further out and again, look at things like skin pigmentation and socioeconomic status, and hopefully help to better understand specifically what's causing disparities in cardiovascular health, and then try to figure out good strategies to mitigate those disparities.

Samantha Muller:

Definitely. As a final question we do want to ask, what is a piece of advice that you would like to give to the next generation of scientists? 

Tony Wolf:

I think that a lot of trainees and even early career researchers hear about this concept of imposter syndrome, where they feel like they don't belong among the great scientists that they're working with. And that, I think stems from a lack of confidence because they don't know everything. And if you set the benchmark for having confidence in yourself as knowing everything, I mean, that's really unrealistic benchmark because nobody knows everything. My advice is to really instead, find confidence in your ability to learn. And if you've gotten this far, then you clearly have the ability to learn, and that's all you really need to have a successful career as a scientist.

And I think building on that, is never be afraid to ask questions, whether you're a graduate student and you have questions for your advisor, don't be afraid to ask those questions because there's a chance that other people have not thought of those questions yet. Even if you feel like it's a dumb question, it probably isn't and it may turn into something really great.

Samantha Muller:

Awesome. That's some great advice. Well, thank you so much having a conversation with me. It's been a pleasure to talk to you and thanks again for just having a chat. It's been great.

Tony Wolf:

Yeah, it's been fun. I'm really glad that we were able to do this. I hope that I adequately answered those questions. They're tough questions.

Samantha Muller:

You did a great job.

[MUSICAL INTERLUDE]

Mark Shriver:

Tracking Traits is a production of Penn State’s Center for Human Evolution and Diversity. Our producer, audio engineer and musical theme composer is Cole Hons, and our logo was designed by Michael Tribone of mtribone design.

 If you enjoyed this podcast, please subscribe through your favorite app, and help us reach more people by sharing it with others and rating us on Apple podcasts.

You can also follow us on social media and learn more about CHED and all of our interviewers and guests at our website, ched – that’s C H E D dot L A dot P S U dot E D U.