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Melanie: Welcome to UF Vet Med Voice with the University of Florida College of Veterinary Medicine. I'm Melanie Cole. And today, we're discussing identification of a new treatment for allergic diseases in horses. Joining me is Dr. Rosanna Marsella. She's a Professor of Dermatology at the University of Florida College of Veterinary Medicine.

Dr. Marsella, it's a pleasure to have you join us today. Can you tell us a little bit about yourself, your background, the reason that veterinary dermatology is of such interest to you? And tell us about the strong program in Veterinary Dermatology at the University of Florida College of Veterinary Medicine.

Dr. Rosanna Marsella: Well, thank you for the opportunity. I have been a dermatologist for a couple of decades. And there is a tremendous need to help animals with skin diseases. Before becoming a specialist, I was a general practitioner and I realized how prevalent skin diseases are. I devoted all my career in identifying new treatments for allergic animals. And I started initially with dogs, because the canine disease eczema and we call it atopic dermatitis of dogs is basically similar to the disease of children. And there is a need to develop new treatments and to test them before making it available to the kids. And so I spent basically almost 20 years working on this atopic dermatitis in dogs.

And as time progressed, I realized that horses actually needed even more help in the identification on new treatments for this disease that is very, very common and, as a matter of fact, becoming increasingly common with time. The reasons for why allergies are becoming so common, I mean, we can go into that, but just know that, in the last 20 years, there's been an epidemic of allergies. And so this is a very common problem for people, it's a common problem for animals. And so basically, I've spent the time researching the mechanisms so that you can identify new treatments that are more targeted with fewer side effects in helping these patients.

Melanie: Well, thank you for that. And as you said, allergies are extremely common in horses and they tend to represent a diagnostic and therapeutic challenge for some practitioners. Can you tell us about how they're multifactorial and why it's so important to identify and correct as many of the factors, the external factors, as possible to control and make the patient more comfortable?

Dr. Rosanna Marsella: Yes. So, allergies are multifactorial. They have a genetic basis and then they are triggered upon environmental exposure. Now, I want to say that you can have animals that are itchy for many other reasons besides allergy and that is what becomes an additional challenge to make sure that we are not going after allergies when in reality the cause of itch is something else.

But once you have identified that the animal is indeed allergic, then we need to figure out a way to increase the ability of the immune system to cope with that stimulation. And so in order to do that, we need to know exactly what the triggers are that can range from foods to trees, grasses, weeds, pollens and so on.

So we do a lot of intradermal skin testing -- and that's similar to what is done in people, by the way -- to identify the culprit, so that we can make a customized immunotherapy. So it's called allergen-specific immunotherapy that is made specifically for that individual including the allergens to which that individual is overreacting. So that takes a little bit of effort and expertise so that you can identify the correct triggers for each patient.

Melanie: So have you found a common component in allergic horses that you have identified, that despite some of the advances in the understanding of the pathogenesis of disease that you can speak of, some things you can tell other providers to look for as a common component?

Dr. Rosanna Marsella: Well, insects are excruciatingly common, particularly in the south eastern United States. So many of this animals have an insect component, like no-see-ums are very, very prevalent. And then besides that, it's typically grasses because in horses, grasses are both cause of disease by inhalation as well as ingestion and physical contact. And so grasses are probably some of the most common triggers. That's why when we test for allergies, we have an extensive panel of different grasses and hays and things like that.

So some of this patients have both skin disease and respiratory disease. And that is very similar to what happens in people. In people, there is something called the atopic march, where basically you have skin disease as a kid, and then some individuals grow out of it. And then later on, they develop rhinitis and asthma. Horses mimic very much the same picture of humans, so you can have horses that just have the eczema component and some that also have the asthma component. And that is a major, major issue for these individuals, because they're very dependent on medications in order to breathe.

Melanie: So I'd love for you to tell us about your research working on the first biologic, the monoclonal antibodies to help allergic horses and horses with COPD. Tell us about veterinary medicine's history with inhibitors, how it applies to your work and tell other providers about your fascinating research.

Dr. Rosanna Marsella: Well, thank you. So the cytokine, which is the molecule, I guess, that we're targeting is called IL-31, interleukin 31. And this is a cytokine that has attracted a lot of interest in recent years. And vet med is being the first one to have a biologic for that in dogs. It's called cytopoint. It's basically an injection that specifically targets the molecule that mediates itch. So we have had that for a few years, but no work had been done in horses.

And so basically, what I have been working on is the sequencing of this molecule in horses. We made a recombinant that we can inject in normal horses to demonstrate that when you inject it, you stimulate itch. We are measuring the levels of this molecule and the idea we're in the process of making monoclonal antibodies against that. So the idea is that you will no longer depend on steroids because steroids have a lot of broad-spectrum adverse effects and to basically have an injection, that can selectively target this molecule.

Now, this molecule, there is preliminary evidence that it plays a role not just in the skin disease, but also in the lung disease. So if this proves to be true, we could have a potential treatment that would be a benefit for both the eczema component and the respiratory disease. So that's the idea, to basically create alternatives that don't include steroids. Because right now, horses have primarily steroids and compared to other species where you have many more options, they don't. And steroids can have devastating adverse effects in horses like laminitis plus athletes cannot compete on steroids. I guess the Kentucky Derby made us all aware of that, so you cannot give steroids to horses that compete.

Melanie: Wow. This research could really be life-changing for horses, Dr. Marsella. So how do you see or envision this research translating from lab to bedside as it were? Where do you see it having an impact on both veterinary medicine and human medicine?

Dr. Rosanna Marsella: Well, the idea is to develop a new therapeutic that can then be made available to patients. So this is a very clinically relevant research. So we studied the mediator with the intent to produce something to block it. And so the impact is tangible, is direct. And, again, this is something that has the potential translating on the human side. In human medicine, there are several biologics for allergic individuals. The idea is to see if you can have a biologic that can potentially help both for the skin disease and the respiratory disease, and so bridge this to different manifestations of allergic disease. So of course, each species has its own cytokine, right? In other words, the sequence is different. So that's very important to make sure that we all understand you cannot take a biologic from one specie and give it to another, but it's the concept, right? So the sequence is different, but it's the concept of how to approach the disease and see if it can benefit both the skin and the respiratory disease.

Melanie: Isn't this a fascinating discussion and your research is so interesting, Dr. Marcella. So as we wrap up, this research is exciting because as you said, it's both innovative and translational in the sense that, you know, bench work, it has these clinical applications and comparative, as you just stated across species. So wrap it up with a summary for other providers about how you feel this could impact the world of veterinary medicine, human medicine, and what you would like the take home message to be about your research.

Dr. Rosanna Marsella: The take-home message is that there is a tremendous need to identify sustainable long-term targeted treatments with minimal adverse effects. Anytime that as doctors we prescribe a broad-spectrum treatment, we are increasing the risk of unwanted adverse effects. The identification of targeted treatments like the concept of a biologic and, with this word, I mean, an antibody that is specifically targeting the molecule that is causing the problem. It's something new and potentially very, very beneficial in human medicine and veterinary medicine. Human medicine has other biologics for other diseases. The idea is to be targeted and to minimize adverse effects.

So my hope is that we realize that animals have similar diseases to humans. Well, we can learn from them, can benefit not just the animals, but increase our understanding on how that also applies to humans. So I have worked with the College of Medicine for a few years. I can tell you that animals in many ways perfectly mimic the human condition. And I think that if we can put together physicians and veterinarians working together, we can all learn from each other about the mechanism of the disease and how we can help our patients. So that's my hope for this take-home message.

Melanie: Beautifully said. So really well-stated and such an important aspect of the topic we were discussing today. Really thank you so much, Dr. Marsella, for joining us. To listen to more podcasts from the experts at the University of Florida College of Veterinary Medicine, please visit vetmed.ufl.edu. That concludes today's episode of UF Vet Med Voice brought to you by the University of Florida College of Veterinary Medicine, advancing animal and environmental health. I'm Melanie Cole. Thanks so much for tuning in.