Inadequate blood supply (ischemia), resulting in neuronal cell death caused by stroke, cardiac arrest or profound hypotension is a leading cause of death and permanent disability. Brain damage resulting from ischemic injury typically manifests as the immediate loss of neurons within the ischemic core, surrounded by a region of brain tissue exposed to reduced blood flow and oxygen called the penumbra or peri-infarct region. This peri-infarct region has been the target of therapeutic protection following ischemic insult (e.g. stroke), and is thought to play a potentially critical role in functional recovery following stroke. Although the precise mechanisms of underlying delayed neuronal cell death are multi-faceted, the over-activation of N-methyl-D-spartate receptors (NMDARs), is known to have a key role in mediating neuronal injury in both in vitro and in vivo models of stroke and traumatic brain injury. Dr. Allen Chan is examining the role of selective NMDAR activation and blockade on dendritic spine dynamics immediately following a focal ischemic stroke, with the aid of established pharmacological treatments and in vivo brain imaging techniques. Dendritic spines are hypothesized to be key structural substrates within the penumbra that mediate plasticity changes necessary for functional recovery after stroke. Dr. Chan’s project will increase our understanding of the mechanisms and pathology of stroke injury with respect to the damage and death caused to pivotal brain cell connections called synapses, and ways to potentially alleviate this damage and death. In so doing, rescue and protection of damaged but repairable parts of the brain may lead to treatments that enhance functional recovery and therapies that directly impact patient health and quality of life.
Research Pillar: Biomedical
The Role of Gap Junction Proteins in cytoskeletal rearrangements in B-lymphocytes
B-cell lymphomas are the most common type of blood cancer, accounting for 80-90 percent of non-Hodgkin’s lymphomas. Because lymphoma cancer cells can so readily spread from the blood stream to other tissues in the body, it is also a highly fatal form of disease. The key to preventing the spread of B-lymphomas is to prevent the proliferation and migration of these cancerous cells. To that end, an understanding of the underlying cellular processes is essential to the development of effective therapies. Recently, the Gap junction protein connexin43 (Cx43), was shown to cause neuronal migration in the brain. This novel role for gap junctions has led to speculation that Cx43 may be important for the migration of other cell types. Further, Cx43 expression on B-cells is important for hematopoiesis in the bone marrow, however the function of Cx43 on mature, circulating B-cells has remained elusive. Letitia Falk’s research involves a systematic dissection of the role of different protein domains of Cx43. Additionally, she is investigating the migration of B-lymphoid tumour cells expressing wild type and mutated forms of Cx43 in mouse models of tumour metastasis. These experiments will provide insight into processes that underlie normal lymphocyte development as well as the regulatory processes involved in the metastasis of B-cell leukemias, lymphomas and myelomas. Understanding in this area has the potential to aid in the development of novel anti-cancer therapeutics for the treatment of lymphoma cancers.
Targeting the Ras/MAPK pathway for treatment of high-grade pediatric brain tumors
Brain cancer is an extremely aggressive disease that remains difficult to cure and carries a high mortality rate. Every year, more than 3,500 children in North America are diagnosed with this disease. Brain tumours are the most common solid tumours and the second leading cause (after leukemia), of cancer-related deaths in children. The majority of patients (80 percent), with the more aggressive forms of brain tumours will survive less than two years. Surgical removal of brain tumours is challenging for a number of reasons, and complete removal of cancer cells is virtually impossible. The chemotherapeutic agent Temozolomide (TMZ), is used in patients with aggressive brain cancers however, in a subgroup of patients this drug does not work effectively because they are resistant to it. Furthermore, recent research shows that TMZ is not generally very effective at eliminating pediatric brain tumour cells. Consequently, certain ‘survivor’ tumour cells become ‘seeds’, generating more cells that subsequently form a new tumour. Cathy Lee’s research focuses on a protein called PLK1, which is essential to the cell division process in cancer cells. Many researchers have shown that PLK1 levels are higher in cancer cells than in normal cells and that tumour cells require this protein for survival. When this protein is eliminated, cancer cells either die or their growth is suppressed. Importantly, normal cells do not seem to be greatly affected by PLK1. Ms. Lee’s research will provide a deeper understanding of this protein. In related research, Lee will examine the ‘seeds’ of brain tumours, called ‘brain tumour initiating cells’, with a view to determining a way to prevent their expansion and induce cell death. The results of her research will improve our understanding of pediatric brain cancers and allow future design of novel, alternative therapeutic strategies that benefit patients’ health and improve the way we currently treat this devastating disease.
Structural analysis of proteins involved in bacterial cell wall biosynthesis
Antibiotics play an essential role in the treatment of bacterial infections. However, the overuse of antibiotics has resulted in the emergence of numerous drug resistant strains of important human pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). These, and related bacteria, represent major threats to human health if tools cannot be developed to combat these so called “”superbugs””. Potential targets for the development of these new antibacterial treatments include the enzymes involved in the production of the bacterial cell wall. Robert Gruninger’s research is focused on characterizing distinct aspects of cell-wall biogenesis. By clarifying the three dimensional structure of these enzymes, it will be possible to design drugs that will block their function, and combat the development and spread of “superbugs”.
Identifying clinically relevant biomarkers in lymphoma using next-generation sequencing
Lymphomas are a class of cancers that generally derive from blood cells known as B-cells that are present within organs called lymph nodes. Similar to other cancers, lymphoma tumours can be surgically removed. However, patients often relapse after surgery because, inevitably, a small number of cancer cells remain in the body. Diffuse large B-cell lymphoma (DLBCL), is one of the most common types of lymphoma. Sophisticated techniques that allow one to view the abundance of genes (expression,) or the genetic code (DNA sequence), of cancer cells can reveal clinically relevant distinctions between cases of DLBCL. This type of grouping is important because, for example, patients with one subgroup of lymphoma known as the ABC variety appear to have an inferior response to current standard therapies compared to those with the more common GCB variety of DLBCL. The signals that define distinct subtypes of cancers are often referred to as biomarkers and their presence or absence can, in some cases, be tested in a clinical setting. Ryan Morin is focusing his research on the identification of new biomarkers in cancer cells from a clinically diverse group of lymphoma patients. Additionally, Mr. Morin’s research will focus on the identification of genes that have been damaged by somatic mutations, and thereby the identification of genes important to the development of DLBCL. By cataloguing the identified cancer driver mutations, it may be possible to use their signatures to define new subgroups of lymphoma with distinct characteristics. Marrying this information to new biomarkers may help determine whether any new biomarker is associated with positive (i.e. cure), or negative (i.e. relapse), clinical outcomes. Finally, the identification of biomarkers and specifically somatic mutations altering protein function may reveal possible vulnerabilities of a cancer cell to specific drugs. For example, a mutation that results in activation of an oncoprotein may allow a clinician to choose an appropriate drug that inhibits that protein. Further, if no drugs are available, these findings may spur the development of new drugs to specifically target the mutated or activated proteins responsible for malignancy.
Molecular dissection of the Campylobacter jejuni regulatory system CprRS and its control of key aspects of pathogenesis and biofilm formation
Campylobacter jejuni is the leading cause of bacterial food poisoning in the developed world. Infection with C. jejuni typically presents as severe gastroenteritis, termed campylobacteriosis, and presents as intense, often bloody, diarrhea, vomiting, fever and stomach cramps. Prior infection correlates strongly with autoimmune disorders such as irritable bowel syndrome, reactive arthritis and alarmingly, Guillain-Barré syndrome. Furthermore, antibiotic resistance is skyrocketing in C. jejuni isolates, and an effective human vaccine is not presently available. Currently, very little is known about the virulence mechanisms of C. jejuni. Even less is understood about how this fastidious organism survives and thrives in hostile environments, including those associated with environmental transmission and in vivo stresses such as acid, bile and the immune system. In her research, Sarah Svensson is characterizing the CprRS (Campylobacter planktonic growth regulation) two-component regulatory system (TCRS). TCRS represents ideal targets for antibiotic treatment due to their omnipresence in bacteria (and not humans) and control of phenomena related to virulence. By determining 1) genes that comprise the CprRS regulon; 2) how information is relayed from the environment through CprRS and connected regulatory proteins to elicit the appropriate physiological response; and 3) how survival strategies such as biofilm formation are controlled by CprRS, will contribute to our understanding of what makes apparently fragile bacterial pathogens such as C. jejuni so prevalent. As a result, this work will also provide a framework for design of novel infection control antimicrobial treatment, and vaccine strategies for an underappreciated bacterial pathogen.
The Next Generation of Multifunctional Nanoparticles for Cancer Imaging and Therapy
In photodynamic therapy (PDT), a nano particle (NP), is placed within the body and is illuminated with light from outside the body. Normally, the light that gets absorbed by the NP can produce high energy oxygen molecules which will chemically react with and destroy most organic molecules that are next to them, like tumours. This type of light therapy can also be employed to release small drug molecules from the surface of the NP. PDT can be far less expensive than radiotherapy or surgical operation and post operative care. Furthermore, PDT recovery typically requires hours or days rather than weeks, and does not leave a toxic trail of reactive molecules throughout the body as is the case with chemotherapy. This is because the light is targeted at the precise location of the NPs. PDT therefore, is potentially a non-invasive procedure for treatment of diseases, growths and tumours. Additionally, NPs with multiphoton upconversion properties are useful for the diagnosis and treatment of cancer and hold great promise for biosensing and bioimaging. Dr. John-Christopher Boyer is involved in designing the next generation of multifunctional NPs capable of both imaging and selectively targeting cancer cells using photodynamic therapy based on molecular switches. The ultimate goal of his project is to develop nanoparticles with photon upconversion properties, and apply them in sensitive cancer detection. Consequently, a focus of his current research project is to evaluate the performance of the upconverting NPs when applied to sensitive detection and treatment of prostate cancer. Dr. Boyer’s research could significantly enhance Canada’s position in nanomedicine, and developments in this area may well revolutionise medical practice in cancer detection and treatment over the coming years.
Functional characterization of T cells and T regulatory cells in Inflammatory Bowel Disease
Crohn's disease and ulcerative colitis, two forms of Inflammatory Bowel Disease (IBD), are disorders believed to be caused by the cells of the immune system mistakenly attacking the tissues of the digestive tract. This phenomenon, known as autoimmunity, leads to massive inflammation of the affected area and consequently causes severe pain, diarrhea, bleeding and other debilitating symptoms. With few treatments and no cure to date, this disease continues to impact both the general population and our health care system. Current research suggests that the inflammation associated with IBD is caused by self-reactive immune cells called T cells that attack the gut tissue, along with a loss of T regulatory cells (Tregs), which act to 'turn off' the immune system. Furthermore, flagellin, a protein present on all motile bacteria including the microflora found within the intestine, may also contribute to the establishment of IBD associated inflammation through its influence on T cells and Tregs. Indeed, studies have shown an immune response is generated against flagellin in 50 percent of patients with Crohn’s disease. However, the nature of these responses remain largely uncharacterized. Megan Himmel's research aims to optimize a novel method of identifying T cells and Tregs which are specifically reactive to flagellin, in order to study their function and their possible contribution to the pathogenesis of IBD. This work may lead to a novel diagnostic marker for IBD, as well as further insight into the immune mechanisms contributing to this disease. Furthermore, Ms. Himmel’s research will provide important insight into the overall role of T cells and Tregs in the establishment and progression of IBD in humans, with the ultimate goal of establishing methods to therapeutically manipulate the balance of pathogenic versus regulatory immune responses.
Seasonal plasticity in brain estrogen signaling mechanisms regulating aggression
While estradiol, a kind of estrogen, is often considered a “”female”” hormone, it is fundamentally important for both female and male brain function. It is a hormone with a wide range of effects on the brain and human behaviour. In early life, estradiol plays an important role in the growth of brain cells and in the establishment of differences between male and female brains. In adulthood, estradiol activates both male and female reproductive behaviour. Studies also implicate estradiol in the regulation of aggression, learning and memory, muscle control and the perception of pain. Furthermore, estradiol has been shown to influence depression, recovery from stroke and brain injury, Parkinson’s disease and Alzheimer’s disease. Because estradiol is involved in a vast array of brain functions, many of which are critical to human health, it is important to understand how estradiol affects brain cells. Dr. Sarah Heimovics’ research explores the degree to which there is plasticity in how estradiol affects the brain and behaviour. Specifically, she is investigating the effect of environmental factors, such as photoperiod, on estradiol signalling mechanisms the brain. Traditionally, estradiol has been understood to influence brain and behaviour genomically, via changes in gene expression over a relatively long timescale (days to weeks). However, a growing body of research suggestes that estradiol also has rapid (within 30 minutes), non-genomic effects. Dr. Heimovics will compare the role of genomic and non-genomic estradiol signalling mechanisms in the neural regulation of aggressive behaviour on short and long photoperiods. She is testing the hypothesis that non-genomic estradiol signalling is more pronounced on short photoperiod (as during the winter in BC), which may have implications relative to depression. The results of this research will contribute to the greater understanding of how estradiol acts on the brain, which is a critical issue for the health of British Columbians.
The role of microbiota in susceptibility to inflammatory bowel disease.
The cause of inflammatory bowel disease (IBD), including intestinal disorders characterized by chronic inflammation such as Crohn’s disease and ulcerative colitis, remains unclear. However, changes in the microbiota have been linked to IBD, including Crohn's disease and ulcerative colitis, as significant differences exist between the microbiota of IBD patients and healthy individuals. As western societies have developed, improvements in health and hygiene have altered human-microbe interactions through increased sanitation, antibiotic usage and vaccination. Concordantly, epidemiological studies have shown an alarming increase in the occurrence of immune mediated disorders, such as IBD. However, whether a change in microbiota composition precedes and contributes to onset of IBD or is a result of IBD remains to be determined. Marta Wlodarska and colleagues have previously shown that clinical levels of antibiotics will cause a shift in, but not complete ablation of the microbiota which results in a differential disease outcome by Salmonella Typhimurium infection. Her current research project expands on this work by investigating how antibiotic-induced fluctuations of the microbiota disrupt the homeostatic state of the intestinal immune system, potentially leading to increased susceptibility to IBD. Specifically, she is using clinical levels of antibiotics to shift the composition of the microbiota and evaluate how that affects the outcome and severity of C.rodentium-induced colitis. Additionally, her research should also provide an understanding of how changes in microbiota composition affect the homeostatic state of the mucosal immune system through intestinal epithelial cell-mediated cytokine secretion. Collectively, her work will increase the understanding of the interplay between the microbiota and immune responses as well as any associated impact on colitis. These issues are central to increasing our understanding of IBD in general, and may lead to the development of new diagnostic and therapeutic tools.