McMaster University

McMaster University

Caleb Zavitz,


Lecturer (part-time)
Pathology and Molecular Medicine

Toronto General Research Institute
Division of Advanced Diagnostics
University Health Network
101 College Street, TMDT 3-906
Toronto M5G 1L7
Tel: 416-581-7511
photo of Dr Zavits

Faculty Biography

Education and Professional Standing

Postdoctoral Fellowship, University of Toronto, 2013
Postdoctoral Fellowship, McMaster University, 2011
PhD, McMaster University, 2009
BSc, McMaster University, 2003


Basic Science Research

We are each protected by an elegant and multi-layered system of overlapping immune defences that are collectively termed the “host defence” system. My research focuses on understanding two situations in which the host defence system can mistakenly cause, rather than protect us against disease; atherosclerotic vascular disease, and Acute Respiratory Distress Syndrome (ARDS).

My first area of interest is in understanding the immunologic mechanisms which drive atherosclerosis. Atherosclerosis or “hardening of the arteries” is a common condition, and atherosclerotic diseases, most notably heart attacks, strokes, and peripheral vascular disease are the leading cause of death and disability in the developed world. Atherosclerosis represents an efficient but ultimately maladaptive response to vascular injury and lipid overload on the part of the immune system, in which monocytes and macrophages engulf lipids, accumulate in the walls of our blood vessels, and can ultimately break through the vessel wall or close it off completely, with devastating consequences. It is still unclear how and why this buildup of fats and cells is initiated, and why it worsens over time. We have recently shown that macrophage proliferation within the plaque, not an influx of monocytes into it. The thrust of my current research is on developing a more detailed understanding of the receptors and ligands responsible for the movement of cells into the blood vessel wall, and the mechanisms which drive lesional macrophage proliferation in both humans and in experimental models.

My second area of interest is in understanding the host defence system’s response to complex immune challenges, wherein the immune system sometimes struggles to mount two dramatically different responses at the same time. This is perhaps most important in severe pneumonia and ARDS that follows influenza virus infections. While our immune system is quite adept at combatting influenza viruses, and similarly adept at fighting pulmonary bacterial infections, it often struggles to control the secondary bacterial infections that arise in the days following a primary influenza challenge. Numerous mechanisms have been identified by which viral infection can predispose a person to bacteria, but these have not resulted in effective new therapies for ARDS. Antibiotics, steroids, and numerous investigational drugs have failed to materially impact on the morbidity and mortality of ARDS. I am currently interested in the role of CXCL2, an chemokine we have recently shown to be a potential therapeutic target in treating severe pneumonia in mixed viral-bacterial infection.

Clinical Research

My clinical research focuses on mechanisms to assure the application of clinical and basic science knowledge in clinical practice. Much has been made of “translational” or “bench to bedside” research which takes new results and converts them into useful clinical knowledge, but it is apparent that this knowledge does not make its way into daily clinical practice. For many reasons, there is a high degree of variability in the healthcare system, with different providers making different decisions, not all of which are supported by current best evidence. As a result, a patient’s odds of successful diagnosis and treatment depend substantially on the physician they see. My long-term goal is to see this inequity engineered out of our healthcare system so that every patient can be confident they are getting the best care. To that end, I am involved in research and development of new strategies and technologies to make it easy for clinicians to “do the right thing, every time.”


I am involved in teaching through Health Sciences 2F03/2FF3 (Human physiology and anatomy), and 4D03/4W03 (Special topics in health sciences)

Selected Publications

View my publications on PubMed

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