Elucidating the functions of MCL-1 in DNA repair

Mammalian cells have developed elaborate DNA damage response (DDR) and DNA repair systems in order when to protect and repair their DNA encountering toxic agents. In tumour cells, activation of these molecular events can make tumour cells resistant to chemotherapy or radiotherapy-induced DNA damage. Therefore, decoding how the DDR and DNA repair mechanisms are controlled is very important for understanding how cells become resistant to chemotherapy and to find ways to improve conventional cancer therapies. MCL-1 is a pro-survival protein that has multiple roles within the cell and has been shown to protect cells from death. It can interact with multiple important nuclear proteins involved in DDR response. Loss of MCL-1 increases genome instability after DNA damage. These studies indicate that MCL-1 may be an important component of the DDR machinery to regulate the repair of DNA lesions. Dr. Yemin Wang is investigating how MCL-1 regulates DDR and DNA repair. He is taking an intracellular approach to understand how MCL-1 is delivered into the nucleus after DNA damage and will also use this approach to investigate how MCL-1 regulates crucial events in DDR and DNA repair machinery. Dr. Wang will also examine whether the presence of MCL-1 in the nucleus affects how the cell responds to chemotherapy and whether the role of MCL-1 in DDR affects tumor development. The results of Dr. Wang’s work will provide us with a better understanding of MCL-1 in DDR and DNA repair processes, explain its essential function in vertebrate development, and help us to design improved therapeutic interventions for cancer treatment.

The mechanism by which SOCS3 mediates IL-10 inhibition of macrophage activation

Inflammation is a protective response generated by immune cells against infection. However, when inflammation becomes unregulated within the body, it can cause diseases. A key anti-inflammatory regulator of immune cells is a cytokine (a type of hormone), called interleukin-10 (IL-10). The importance of IL-10 in regulating immune cell function is illustrated by the fact that many tumour cells and intracellular pathogens produce or elicit production of IL-10 for their survival. A main target of IL-10 is macrophages. Activation of macrophages by interferons, or bacterial cell products such as lipopolysaccharide (LPS), induces a number of immunologic responses including production of pro-inflammatory mediators such as the cytokine TNF. IL-10 is able to suppress these events by interfering with pathways utilized by LPS, but its mechanism is unclear. Previous research on the intracellular signal transduction pathways utilized by IL-10 has shown that an important component is a protein called SOCS3 which is thought to target specific proteins for degradation. In order to understand how IL-10 uses SOCS3 to inhibit macrophage activation, Tsz Ying Sylvia Cheung’s research is focusing on proteins that interact with SOCS3 in cells stimulated with IL-10. Identification of these proteins will allow for a further research focus on understanding the role they play in macrophage activation and why they are targeted by IL-10. Developing a clear understanding of the mechanism by which IL-10 regulates the network of intracellular signal transduction pathways will better enable the development of therapeutics mimicking the beneficial anti-inflammatory effects of IL-10, and allow for the development of strategies to counter the immunosuppressive effects of certain tumours and immune cell pathogens.

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.

Regulation and Function of Human T helper 17 Cells

Immune system homeostasis is determined by the balance between responses that control infection and tumour growth and reciprocal responses that prevent inflammation and autoimmune diseases. Dysregulated immune responses, such as those that occur with autoimmune disorders and organ rejection, result when and an individual’s immune system mistakenly attacks normal cells. Current treatment approaches involve following a strict regimen of immunosuppressive drugs for the duration of a patient’s life. These treatments, however, seriously compromise an individual’s ability to fight infection and are associated with an increased risk of developing cancer. Sarah Crome’s research has two main focuses. The first is on the regulation and function of a newly discovered class of inflammatory white blood cells (WBC), termed T helper 17 (Th17) cells, which serve an essential function in host defense against extracellular pathogens. While being key players that protect the body from harmful pathogens, Th17 cells are also linked to inflammatory diseases including rejection of transplanted organs and cells, rheumatoid arthritis, psoriasis and inflammatory bowel disease. Therefore, it is essential to understand the mechanisms that regulate this cell population in order to be able to treat patients with dysregulated immune responses. Secondly, Ms. Crome and colleagues are examining interactions between Th17 cells and another WBC population, termed T regulatory (Treg) cells, which serve a protective function by suppressing harmful immune responses. Currently, Treg cells are being clinically tested as a cell-based therapeutic alternative to immunosuppressive drugs. However, the diseases where Treg cell-based therapies are being investigated are the same diseases that are associated with Th17 cell activity. Therefore, understanding the interactions between these two cell populations will be essential for clinical based studies of Treg cells, and the development of improved therapies.

Imaging Early Micro-Structural Bone Changes in the Rheumatoid Hand: A High Resolution-Peripheral Computed Tomography (HR-pQCT) Study in People with Newly Diagnosed RA

Rheumatoid Arthritis (RA), affects one percent of the general population. Radiographic (x-ray), evidence of bone thinning (osteoporosis), and bony destruction (erosions), in the bone surrounding inflamed joints is an important diagnostic criterion for RA. These changes are present in the hands and feet of 80 percent of people with RA and can have profound implications with regard to the development of hand deformity, functional limitations and the need for restorative joint surgery. Early presentation of destructive bone changes is associated with a more aggressive disease progression and evidence suggests that starting disease-modifying anti-rheumatic drugs (DMARDs), soon after the diagnosis of RA may help prevent some people from developing bone damage. However, not all people with early RA respond to DMARDs, with ‘non-responders’ requiring more aggressive interventions including trials of combinations of different drug treatments or biologic response modifier drugs. Unfortunately, the time delay associated with implementing effective treatment in people with more aggressive or resistant RA means they are at greater risk for permanent bone damage. Current clinical imaging with Dual X-ray Absorptiometry (DXA), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI), can detect bone damage earlier than x-ray but these tools are not able to identify the initial ‘micro-structural’ changes in the early RA hand. Dr. Lynne Feehan is characterizing early ‘micro’ structural hand bone changes over a two-year period in people with newly diagnosed RA using High Resolution – Peripheral Quantitative Computed Tomography (HR-pQCT), a promising new imaging system capable of imaging the very fine bone internal ‘micro’ detail at a resolution equivalent to the diameter of a human hair. The results of Dr. Feehan’s research could improve patient’s early access to appropriate therapy, and thereby improve their quality of life.

Borrelidin: a novel therapeutic agent for treatment of inflammatory diseases

Inflammation is the body's normal physiological response to injury, infection or foreign substances. While the ability to mount an inflammatory response is essential for survival, the ability to control inflammation is also necessary for health. Inflammatory diseases such as rheumatoid arthritis, osteoarthritis, Chrohn's disease, ulcerative colitis, inflammatory bowel disease, asthma, allergies, septic shock, atherosclerosis and many others are a group of disorders characterized by uncontrolled or excessive inflammatory responses. Often, clinical intervention is required to prevent tissue damage and organ dysfunction in these disorders. While there have been advances in anti-inflammatory therapies over the years, long term use of steroidal and non-steroidal anti-inflammatory drugs (NSAIDS,) is limited due to drug-induced toxicities such as stomach ulcer, gastric erosion, exacerbation of asthma and nephrotoxicity. Therefore, the identification of novel agents that can effectively suppress inflammatory responses without associated long term toxicities represent a major unmet medical need. One of the key ways that the body controls inflammation is through the expression of immunoregulatory enzymes. An example of this natural immunoregulation occurs in pregnant mammals: cells of the placenta that surround the fetus express an immunoregulatory enzyme called indoleamine 2,3-dioxygenase (IDO). IDO expression protects the fetus from being attacked by the mother's immune system. Earlier research has revealed that the small molecule drug, borrelidin, could be used to specifically mimic the signalling effects induced by IDO expression and suppress the action of inflammatory cells. Nadya Ogloff's research builds on this evidence by providing pre-clinical proof-of-principle data to support further development of borrelidin as a potent immunosuppresive agent for treatment of inflammatory diseases.

Regulation of the BACE1 gene expression in Alzheimer's Disease pathogenesis

Alzheimer’s disease (AD) is the most common neurodegenerative disorder leading to dementia, affecting approximately 10 per cent of the Canadian population over the age of 65. One of the pathological hallmarks of AD is increased deposition of the beta-amyloid protein, which forms amyloid plaques in the brains of AD patients. This is caused by dysfunction of the BACE enzyme, which regulates processing of the amyloid precursor protein to generate beta-amyloid proteins. Levels of the BACE enzyme have been shown to be elevated in Alzheimer’s. Philip Ly is interested in studying the underlying molecular mechanisms regulating the BACE enzyme expression and activity. He is studying a region of the BACE gene called the BACE promoter. This region has been demonstrated to be important for BACE expression. However, the regulations at the level of BACE gene transcription – the first step in the expression of the genetic information – remain elusive. Using a series of molecular and biochemical approaches, Ly is examining the transcriptional controls that regulate BACE gene expression in neurons. He is also examining if specific mutations in these transcription factors affect BACE expression and contribute to AD pathogenesis. Ly’s research will be the first to thoroughly characterize the transcriptional regulation of the BACE1 and the role of abnormal gene expression in AD pathogenesis. In addition to providing much needed information regarding signal transduction in amyloid precursor protein processing, these studies have important pharmaceutical implications, such as potential development of BACE enzyme inhibitors to improve treatment of Alzheimer’s disease.

Modulation of ocular motor decisions by reward: an investigation of neural processes using converging methods

The prospect of reward or punishment is known to affect how people make decisions. However, it is not clear which neural systems are involved in this process. This is an important topic in healthcare, because impaired processing of reward information is known to affect the decision-making abilities of many people, including those with damage to the frontal lobe of their brains, Parkinson’s disease, depression/anxiety, obsessive compulsive disorder, and even normal aging. A striking example of this situation occurs among some people with Parkinson’s disease, who can develop pathological gambling behaviours as a result of taking dopaminergic drugs. An effective way to study these neural systems is to track eye movement decisions – in other words where people focus their visual attention. Typically, people are faster to make an eye movement and are more accurate in their eye positions when the movement is rewarded by monetary gain. However, these effects are degraded in certain psychiatric conditions, such as anxiety and depression. Dr. Linda Lanyon is investigating the brain circuits that mediate these reward-related decisions in healthy humans. Her findings will enable her to develop a computer model of the brain circuitry and function that is able to simulate the behaviours observed in humans. In addition to demonstrating how these systems operate in healthy humans, the computer model can also be selectively damaged in order to simulate pathological behaviours observed in patients. By using healthy subjects to create a computer model for decision-making, Linda hopes to improve the understanding of the pathology of neurologically-impaired circuits.

Immunomodulation of regulatory mechanisms in mucosal immunity

Inflammatory bowel diseases (IBD) are chronic conditions characterized by severe inflammation of parts of the bowel, causing significant symptoms, such as diarrhea, pain and intestinal bleeding. There are two main types of IBD: Crohn’s disease and ulcerative colitis. IBD is prevalent in Canada, with an estimated 170,000 people suffering from the disease. Despite years of effort, the causes of these disorders remain incompletely and inadequately understood. The intestinal inflammation in IBD is thought to result from abnormal responses to the bacteria that live normally in the gut. In healthy individuals, the immune system is able to distinguish between harmless (commensal) bacteria and those that cause infections (pathogens). In IBD patients, the immune system elicits an aberrant and aggressive response against components of host commensal bacteria. Dendritic cells (DC) and regulatory T cells (nTreg) are two types of cells important in maintaining a healthy intestinal immune system. Defects in the development or function of these cells could ultimately lead to inappropriate responses to commensal bacteria, or certain commensal bacteria or pathogens could perturb the normal immune state of the gut. Dr. Gijs Hardenberg is investigating the interplay between host commensal bacteria and the immune system in IBD. He is studying the roles of nTreg and immune responses, focusing on the bacterial protein flagellin, which has been shown to be the major target of intestinal immune responses in Crohn’s disease patients. His work aims to understand how IBD begins and persists how it might ultimately be treated or even prevented. The findings from these studies may also be broadly applicable to other autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and lupus.

Healthcare workers and antineoplastic drugs: Identifying the determinants of exposure and current challenges to reducing exposure

In health care settings, antineoplastic drugs are prepared and administered daily, mainly for the treatment of cancer. These drugs are inherently toxic and can therefore affect normal, healthy cells. On-the-job (occupational) exposure to antineoplastic drugs has been shown to cause a variety of health effects including cell mutations, adverse developmental and reproductive outcomes, and cancer. Absorption through the skin is suspected to be the main route of occupational exposure to antineoplastic drugs, and in spite of control measures used during their handling and preparation, studies have found antineoplastic drug contamination of surfaces in health care facilities. However, few studies have examined the potential for occupational dermal exposure. Chun-Yip Hon previously conducted a pilot study assessing the occupational dermal exposure risks of antineoplastic drugs to healthcare workers, and evaluated the cleaning protocols for drug-contaminated surfaces. He found that antineoplastic drug contamination of the drug preparation area is likely in British Columbian hospital pharmacies even after cleaning, and that the hands of pharmacy personnel may be contaminated even if the worker was not responsible for preparing the drug products. He’s now undertaking a full-scale study at hospitals situated within the Lower Mainland, investigating the procedures and process flows of antineoplastic drug handling, and determining who may come into contact with the drugs. He is quantifying antineoplastic drug contamination levels on surfaces throughout their process flow in each hospital, assessing workers’ knowledge of safe handling procedures as well as their risk of occupational dermal exposure. He will also determine the presence of antineoplastic drugs in health care workers through biological monitoring. Hon’s findings will determine the risk factors associated with occupational exposure to antineoplastic drugs in the health care sector, providing key information for those who work with antineoplastic drugs, occupational health and safety professionals, risk managers and policy makers.