Dr. Peter Zahradka, Molecular Physiology

Dr. Peter Zahradka

Principal Investigator
Molecular Physiology, Canadian Centre for Agri-food Research in Health and Medicine

Professor
Departments of Physiology and Pathophysiology & Human Nutritional Sciences, University of Manitoba

Research Focus

The Molecular Physiology laboratory has a long-standing interest in the cellular and molecular processes that control the functional properties of blood vessels. Our research in this area is going in two distinct directions. First, we are attempting to understand the relationship between vascular disease and metabolism. This is a key issue in today’s world, because metabolic dysfunction due to obesity and diabetes affect the health of blood vessels. In particular, it is now recognized that hormones produced by adipose (fat) tissue are required to keep blood vessels in good working condition. Furthermore, levels of these hormones decreases in obesity. The end result is an increase in the susceptibility to develop atherosclerosis, or hardening of the arteries, which is the main cause of heart attacks and strokes. We believe that a better understanding of how metabolic dysfunction negatively affects blood vessels will lead to better treatments for preventing the deaths that are caused by these conditions.

Second, the laboratory is investigating whether nutritional intervention with novel supplements or food products can be used in the treatment or prevention of cardiovascular disease. In this case, atherosclerosis is the main focus of our research. We have obtained novel equipment to assess hardening of the arteries in both humans and animals, thus providing us with the capability to directly compare results obtained in clinical trials with those of animal studies. This has given us a huge advantage when we for translating the laboratory findings to the public. Specifically, we are interested in identifying and characterizing new bioactive molecules from plants, and employing both animal and human studies to examine efficacy and safety of these molecules. The availability of some unique equipment that allows us to isolate the individual bioactives from the very complex mixtures present in plant extracts provides us with a huge advantage in performing this type of analysis. Our proficiency in cell culture and analytical chemistry also help us in determining which biological factors that mediate blood vessel function are influenced by specific bioactive ingredients in our food, especially in the context of atherosclerosis, obesity and diabetes. Given the importance of diet to these diseases, nutritional intervention is an important component of this work.

Why is this work important?

Our work with various nutritional interventions has shown that bioactive compounds derived from plant and animal sources may be applicable to the treatment of obesity-associated diseases, including atherosclerosis and metabolic syndrome. In particular, we have been able to establish that short-term changes in what we eat can affect the health of our blood vessels. These results provide us with strong rationale to move forward with testing other food products that have the potential to improve human health.

What techniques and equipment are used in this laboratory?

Some of our studies are conducted with cell culture models. We have cells that were derived from blood vessels (smooth muscle, endothelial), liver, adipose, colon, skeletal muscle and kidney tissues. These are available for monitoring the effects of growth factors, hormones and differentiation factors, or to help identify novel bioactive compounds and their mechanism of action. We also have access to animal models of obesity, diabetes and cardiovascular disease, and we have the capability to conduct studies with human volunteers. We have been studying signal transduction processes utilizing Western blotting and proteomic approaches. In addition, we can introduce recombinant DNA or small interfering RNAs into cells and animals. Finally, our access to human subjects has not only enabled us to decipher the way the food we eat affects our health, it has also allowed us to apply genomics to our examination of how nutritional factors influence vascular and metabolic disease.

About Dr. Peter Zahradka

Dr. Zahradka completed his undergraduate and graduate degrees at the University of Western Ontario in the Department of Biochemistry. He subsequently conducted post-doctoral studies at Stanford University (Laboratory of Experimental Oncology) and the University of Guelph (Molecular Biology and Genetics) before being hired as an assistant professor in the Department of Chemistry and Biochemistry at Guelph. After two years teaching 4 courses per year, he moved to the University of Manitoba where he joined the Department of Physiology as a member of the Division of Cardiovascular Sciences at the St. Boniface Research Centre. He has since been promoted from contingent assistant professor to tenured full professor and has seen the original division become the Institute of Cardiovascular Sciences. Finally, after 15 years with the Institute of Cardiovascular Sciences, he took over as Team Leader of the Canadian Centre for Agri-food Research in Health and Medicine (CCARM) in 2006. Over his seven years as Team Leader, he helped the unit grow from its original 3 scientists to 12 scientists who now occupy the entire second floor. From 2012 to 2018, he also served as head of the Division of Endocrinology and Metabolic Disease in the Department of Physiology, a role that fit well with his research program. In 2016, Dr. Zahradka began a term as Deputy Leader for CCARM.

For more information, contact:

Dr. Peter Zahradka
Tel. (204) 235-3507
Fax. (204) 237-2289
pzahradka@sbrc.ca

In Detail

Vascular Disease and Obesity: It is a well-established fact that obesity is closely linked with atherosclerosis, the underlying cause of coronary artery disease and peripheral vascular disease. Atherosclerosis is a disease of the blood vessels that begins when the lining of the vessels (or endothelium) is disrupted. In its most severe state, lesions capable of severely restricting blood flow are present. If these lesions block the vessels of key organs such as the heart, death may result. The reason obesity is associated with vascular disease is because atherosclerosis develops faster when blood lipid (cholesterol, triglycerides) levels are elevated. Interestingly, there is now strong evidence to suggest that hormones produced by adipose (fat storing) tissue help with maintaining the health of blood vessels. It has therefore been proposed that an alteration in the production of these hormones as a result of obesity may trigger or promote atherosclerosis.

The Diabetes Connection: Individuals with diabetes (either type 1 or type 2) have a higher risk of developing atherosclerosis than the normal population, independent of their body mass. Furthermore, atherosclerosis progresses faster with diabetes. Consequently, cardiovascular disease is the primary cause of death for people with diabetes. It has been recently recognized that diabetes alters hormone production by adipose tissue, and that this change in hormone levels likely is responsible for stimulating atherosclerosis.

Targeting Adipokine Production to Treat Vascular Disease: Pharmaceutical agents provide their health benefits by impeding or augmenting specific cellular processes. Natural compounds present in a food product or delivered in pill form can achieve similar results. Consequently, there is considerable interest in developing functional foods and nutraceuticals as alternatives to pharmaceuticals. Our research has been aimed at identifying foods that contain compounds capable of preventing the onset or slowing the progression of vascular disease. We have found that conjugated linoleic acid (CLA) will elevate serum levels of adiponectin, a potent anti-atherosclerotic hormone produced by adipose tissue. We have shown that adiponectin affects blood vessels by preventing the first step of atherosclerosis: smooth muscle cell proliferation and migration. In addition, this adipokine is likely responsible for the reduction in renal failure, pancreatic dysfunction and liver steatosis that occurs in obese rats. Our studies have also been able to show that infusing adiponectin can decrease blood pressure in obese rats. A major finding has been the identification of thrombin as a key factor in the blood that regulates adiponectin activity. Since thrombin is important for blood clotting, we are proposing that adiponectin has a role in how blood vessels respond to injury.

Cell and Molecular Biology of Vascular Disease: Our research is also directed towards understanding the vascular response to injury, which is a key factor in the development of atherosclerotic disease. By identifying the cellular mechanisms responsible for triggering smooth muscle cell proliferation and migration, we expect to develop approaches for preventing disease progression. Our investigation of angiotensin II-stimulated smooth muscle cell proliferation, which is intended to identify the regulatory mechanisms responsible for mediating the biological actions of this hormone, has been a major focus of the lab. We have made substantial progress on several fronts. First, the events that are mediated by IGF-1 receptor transactivation are now becoming better understood. For instance, we now know that the IGF-1 receptor is required for activation of PI3-kinase in response to angiotensin II. Second, we have identified CREB as a critical factor for re-entry of cells into the cell cycle. Third, inhibitors capable of interfering with the function of these mediators are being tested for their ability to prevent restenosis, and thus restricting the formation of an arterial blockage in response to balloon angioplasty or bypass graft surgery. We recently demonstrated the importance of angiotensin II in restenosis by showing an angiotensin receptor blocker can reduce restenosis in a porcine model of balloon angioplasty. As part of this work we successfully demonstrated that application of an inhibitor of smooth muscle proliferation to the surface of a vessel is one way to prevent formation of lesions in vessels subjected to angioplasty. Based on our findings, we are recommending that compounds exhibiting efficacy be sought and tested using this novel method of administration.

Lifestyle, Naturally-derived Bioactives and Nutrigenomics: The lab has begun to investigate a variety of bioactive molecules to determine their utility in disease treatment. At this moment, we are actively engaged in studies with derivatives from buckwheat, dairy products and wheat. Buckwheat has an ingredient capable of reducing blood sugar levels in type 1 diabetic rats. Conjugated linoleic acid (CLA), which is present in dairy foods and beef, has been found to reverse the adverse effects of obesity. Wheat bran contains material that is capable of decreasing the amount of adipose tissue. In each case, we are intent on identifying, isolating and characterizing the specific agent(s) responsible for these beneficial actions. Future plans include conducting human studies to evaluate their ability to have the same effects. Consequently, we are developing the capacity to perform human studies, primarily in relation to cardiovascular disease. This program is already active for a study of the beneficial effects of pulses/legumes on blood vessel health.

Within this context, we are heading a new initiative to develop molecular tools appropriate for early diagnosis of vascular disease. This program includes the participation of several basic science and clinical researchers, each providing a distinct expertise. Our objective is to identify specific molecular markers of endothelial dysfunction by comparing the genetic profile of a select patient population. This approach is likewise being used with animal models to define the genetic changes that can be used to detect the presence of specific nutrients in the diet and their ability to influence disease. We anticipate nutrigenomics will eventually have a major impact on our ability to monitor and influence lifestyle by indicating what foods and food components have beneficial and detrimental effects on individuals.

Awards held by trainees

Jaime Clark

The Frederick Banting and Charles Best Canada Graduate Scholarship (CIHR) Tara Loader, Research Manitoba Scholarship, 2016
The Frederick Banting and Charles Best Canada Graduate Scholarship (CIHR), 2017
1st prize and People’s Choice Award at the Rapid Fire Research Symposium, 2017
2nd prize for oral presentations at the Functional Food and Natural Health Products Graduate Research Symposium, 2017

Tara Loader

2nd place for the Graduate Student Oral Presentations, Canadian Pulse Research Workshop, 2016
Research Manitoba Scholarship, 2016

Youjia Du

Janice Dodd Award for Excellence in Endocrine Physiology, Department of Physiology and Pathophysiology, University of Manitoba, 2016
1st prize for oral presentations at the Functional Food and Natural Health Products Graduate Research Symposium, 2017

Dr. Zahradka’s laboratory would like to gratefully acknowledge the following funding agencies and foundations: