Past Lab Members
Sophie's PhD project focused on re-arming patients’ own Natural Killer (NK) cells as a second-line therapy for ovarian cancer. In healthy individuals, Natural Killer (NK) cells have an intrinsic ability to distinguish and eliminate malignant cells and thus play a critical role in the body’s defense against cancer. However, cancer patient NK cells have diminished anti-tumour activity. While empowering a patient’s own (autologous) NK cells is an attractive immunotherapeutic approach, the impaired function of NK cells from cancer patients needs to be overcome. Contrary to cytotoxic peripheral blood NK cells, NK cells in the immunosuppressive tumour environment, such as ascites in the case of ovarian cancer, exhibit pro-tumourigenic functions and phenotype.
Sophie's project looked to overcome the limitations of autologous NK cell therapy against solid malignancies by re-arming ovarian cancer patients’ own peripheral blood- and tumour-associated ascites fluid-NK cells through expansion. Using a patient-derived xenograft model of human ovarian cancer established in our lab, we assess the therapeutic effects of adoptively transferring patients’ own expanded NK cells in a translational model of the patient’s own ovarian cancer. If NK cell function in the tumour microenvironment can be improved, NK cell therapy against solid malignancies may experience similar success as with hematological malignancies.
Sophie's undergraduate thesis project in the lab consisted of studying a powerful method of NK cell activation with combined IL-18, IL-15, and IL-12 cytokine stimulation. Given the potent activation of NK cells, this method of stimulation has been explored for cancer immunotherapies. This stimulation is known to induce the production of high levels of the anti-tumour cytokine IFN-γ. My project focused on the mechanism of regulation of NK cell cytokine production following stimulation and uncovered that NK cells also produce high levels of IL-8 in response to IL-18/IL-15/IL-12 stimulation.
Financial support provided by the Ontario Women's Health Scholars Award, CIHR Vanier Award, and many more.
Jonathan was introduced to immunology when taking the immunology courses during his first two years at Mac, and by the lab's own Immunology and Beyond podcast. As a previous NSERC USRA student at the Didar Lab in McMaster's School of Biomedical Engineering, Jonathan really enjoyed being able to work to solve problems in science, and wanted to continue this passion for research in the field of immunology. He's really interested in pursuing graduate school after his undergrad, integrating immunological research into disease therapy.
For his third and fourth-year thesis projects, Jonathan worked with Emily, continuing her work investigating the immunoregulatory role that interferons have on immune cell function during infection. Together, they investigated the poorly-elucidated functions of IFN-γ on macrophage phenotype and function.
Current position: MD Student, University of Toronto
Sara was first exposed to the field of Immunology in her first-year cellular biology class through a lecture on the innate immune system. After this lecture, her interest grew and she began listening to various podcasts such as the lab's own "Immunology and beyond". This year Sara is excited to immerse herself in the lab as well as learn even more about immunology through the third-year immunology elective she will be taking.
As a part of the Ashkar Lab, Sara will be working in collaboration with "the Doxey lab" to apply data mining techniques to identify and compare epithelial cell membrane proteins.
Matthew completed his BSc and MSc in Applied Health Sciences at Brock University (St. Catharines, Ontario), and PhD in Pharmacology and Toxicology at Queen’s University (Kingston, Ontario). Most recently Matthew completed a postdoctoral fellowship at Queen’s University in the laboratory of Dr. Mark Ormiston, studying the roles of Natural Killer cells in mediating the progression of pulmonary arterial hypertension in mouse and rat models of the disease.
Glioblastoma multiforme (GBM) is the most common and aggressive form of brain cancer, affecting about 4 in 100,000 adult Canadians. Even with the best treatment available, prognosis for those suffering from GBM is poor, and typically median survival time among GBM patients is approximately 15 months, and 5-year survival is less than 10%. Chimeric antigen receptor (CAR) Natural Killer (NK) cells are immune cells which have been engineered to recognize cells expressing a specified target antigen and attack them. Although CAR-T cells have been used successfully to treat certain blood cancers they have significant on-target off-tumour side effects, and will attack all cells expressing the target antigen, whether healthy or cancerous. Conversely, NK cells express a multitude of activating and inhibitory receptors which allow them to discriminate between healthy and cancerous cells. As such, CAR-NK cells have similar tumour killing ability as CAR-T cells but are much less toxic to healthy non-tumour cells. Matthew’s project will leverage the Ashkar lab’s expertise in autologous NK cell immunotherapy to design and generate CAR-NK cells to attack GBM cells.
Financial support provided by a CIHR Postdoctoral Fellowship.
Tyrah joined the lab as a 3rd year undergraduate student from the Health Sciences (Honours) program with a specialization in Biomedical Sciences at McMaster University. Tyrah had always been interested in human health and disease but after taking a class in human physiology she was immediately drawn to the complex nature of the immune system. She was also further interested in the possibility of using the immune system, specifically Natural Killer (NK) cells, for cancer immunotherapy.
Tyrah's undergraduate project shed light on the timeline of NK cell surface marker CD56 expression in expanded NK cells by exploring the phenotype, function, and metabolic profile of regulatory uterine NK cells pre- and post-expansion. Uterine NK cells are a unique subset to explore as they serve regulatory and protective functions in the placenta and represent a CD56superbrightCD16- phenotype. Tyrah continued her work into uterine NK cells during her MSc degree, when she studied the effects of CBD (cannabidiol) during pregnancy in mice, analyzing its effect on uterine NK cells. Tyrah also studied the role of CBD ingestion by pregnant mice, and its effects on fetal development. After successfully defending her MSc, Tyrah is studying to be a Doctor of Medicine (MD) at the University of Toronto as a member of the Class of 2026.
Current position: MD Student, University of Toronto
Lauren was an undergraduate project and thesis student in the Honors Biochemistry program. Lauren joined the lab as she had always been drawn to immunology and the pathological effects of diseases on the human body. Her past lab experiences were centered around cancer cell biology and gene networks, which subsequently sparked her interest in cancer treatment and immunotherapies. Joining the lab in her third year, she worked with Sophie and Tyrah studying the role of iron on NK cell metabolism and function in the tumor microenvironment (TME). She contrasted these with the effects of iron metabolism on expanded NK cells, which are typically resistant to metabolic immunosuppression by the TME.
Eduardo was a Master of Science student in Medical Sciences in the Ashkar lab. He completed his Bachelor of Science degree in Biochemistry at McMaster University. During his undergraduate he worked in an X-ray crystallography lab and a C. elegans lab where he developed his passion for research. In the meantime, immunology courses established his interest in autologous immunotherapies and the vital role NK-cell based therapies can have in the future treatment of cancers. He joined the Ashkar lab as a master’s student in the Fall of 2018 and is currently investigating novel methods for enhancing the efficacy of NK-cell therapies in solid tumours.
Current NK-cell anti-tumour therapies demonstrate high efficacy in targeting hematological malignancies as patients with acute myeloid leukemia have shown decreased cancer relapse and improved survival following treatment. However, in the immunosuppressive environment produced by solid tumours, NK-cells have faced challenges in sustaining cytotoxicity and preventing tumour metastases. Eduardo’s research focuses on silencing inhibitory signals affecting NK-cell function in the highly suppressive environment of solid tumours, while maintaining the natural ability of NK-cells to distinguish malignant cells from healthy cells. This research could become the foundation for enhancing autologous NK-cell therapies to effectively treat therapy resistant solid tumours.
Current position: MD Student, University of Toronto
Armaan was a fourth year of an Honours Bachelor of Science in Integrated Science (Physics) degree. While his past lab experiences have focused on biophysics, he has always been interested in virology and immunology. Learning about these subjects in his courses was the stepping stone to spark his interest in Zika virus (ZIKV). Armaan’s fourth-year thesis focusesd on investigating how the route of ZIKV infection influences ZIKV pathogenesis and the immune response. While other flaviviruses are only transmitted through mosquito bites, ZIKV is unique because it can also be sexually transmitted between people. There is limited research on how the route of infection impacts viral replication, immune activation, and tissue tropism, which his thesis will investigate using our established ZIKV model
Niamh was a fourth year undergraduate thesis student in the Arts and Science and Biology program. Her fourth year thesis focused on determining why transgene expression rapidly decreases in expanded NK cells over time. Previous attempts to develop effective chimeric antigen receptor (CAR)-based NK cell cancer therapies have been hindered by the fact that NK cell populations cease to stably express the CAR construct after transduction with third generation lentivirus containing the CAR transgene. Interestingly, such decreases in transgene expression is not observed in T cells transduced with the same CAR construct, which suggests that expanded NK cells may have intrinsic mechanisms that impede transgene expression. Determining when and how transgene expression is suppressed by expanded NK cells is imperative for the development of effective CAR NK cell cancer therapies.
Abdullah was a fourth year undergraduate (Life Sciences) thesis student. Natural killer cells are constituents of the innate immune system having the ability to release cytotoxic granules to lyse their targets. In the past, it was found that antibodies are able to mediate and enhance the ability for natural killer cells to lyse their target cells, a process termed antibody dependent cellular cytotoxicity (ADCC). This is done when the antibody binds to an abundant receptor/antigen on the tumor cell at one end, and on the other binds the Fc segment to the CD16 receptor on NK cells to mediate cellular toxicity. Studies using natural killer cells and ADCC have shown promising results in vitro, however, their impact has been thwarted in vivo due to the restricting tumor microenvironment, in particular, due to the hypoxic conditions. Fortunately, recent experiments from the Ashkar Lab among others, have shown that expanding natural killer cells in presence of interleukin-21 allows NK cells to function in tumor microenvironments as well as enhance their cytotoxicity function. His project specifically focused on engineering an antibody most effective with expanded NK cells to render efficient ADCC, especially when placed in inhibiting environments.
This research was supported by the NSERC Undergraduate Student Research Award (NSERC USRA).
Seshini was a fourth year undergraduate (Biochemistry) thesis student. At the time, cytokine based therapy was a rapidly evolving science that can help to fight against viral infection, however, a thorough understanding of their physiological function was required. Previous work demonstrated that type I interferons (type I IFNs) can rapidly elicit an antiviral response during HSV-2 infection but also dampen its effects to prevent a dysregulated innate immune response. Although, it is unknown whether the dual action of type I IFNs is universal amongst other viruses or specific to HSV-2. Seshini, therefore, extended the project to Vaccinia (VACV). The goal was to further elucidate the effects of type I IFNs during VACV infection.
Elizabeth was a Master of Science student in the Medical Science program at McMaster University. She completed her undergraduate degree in Honours Life Sciences at McMaster University. For her undergraduate thesis, Elizabeth focused on examining the influence of the liver milieu on natural killer cell functioning. Her current research has switched over to infectious disease due to her fascination with these terrifying yet mesmerizing obligate parasites. Viruses contain genetic material that contain all information necessary to enable the replication and spread throughout the infected host, in the form of either RNA or DNA. During the innate immune response to infection, the body engages critical antiviral factors including type I interferon and natural killer cells. These components of the innate immune response have been previously shown to hold fundamental roles in controlling infection for a variety of viral pathogens. For her Masters, she focused on the poorly understood innate immune response to Zika virus infection with a focus on the role of type I interferon and natural killer cell functioning.
Rich's previous research work focused on HPV positive and HPV negative head and neck cancers, and the role of high risk HPV oncoproteins on the Natural Killer (NK) cell response to these cancers. In this way, he developed his interest in NK cells and their crucial anti-tumour functions, which can be modulated by viral factors. His work in the Ashkar lab centred on the development of cancer immunotherapies for breast cancer, particularly triple negative breast cancer which is a subset of breast cancer to which effective treatments are lacking. He has demonstrated that NK cells expressing a tumour specific CAR do not direct their anti-tumour function towards healthy targets in which express the CAR target. This is unlike CAR T cells which are unable to effectively differentiate between healthy and malignant cells. As such NK cells constitute an effector cell for cancer immunotherapies which are highly effective against the tumour while limited in the adverse effects they are able to induce (effects which have plagued the use of CAR T cells in the clinic).
Lung cancer patients with pleural effusion (fluid buildup around the lungs) have the lowest survival rate compared to breast and ovarian cancer patients with similar clinical malignancies. As lung cancer is often diagnosed in later untreatable stages, research for new treatment modalities such as immunotherapy is warranted. Research on Natural Killer (NK) cells is growing as these lymphocytes spontaneously lyse tumour cells without requiring sensitization. To harness NK cells for immunotherapy, our lab has used a unique ex vivo expansion method that has previously allowed us to generate vast numbers of highly cytotoxic NK cells from the blood and ascites of ovarian cancer patients. Given the success of our NK cell expansion method, my project aims to assess whether NK cells isolated from the pleural effusion of lung cancer patients can be expanded ex vivo to acquire robust tumour lysis ability against lung cancer. The goal upon expansion is to evaluate the therapeutic potential of NK cells in a translational model of lung cancer.
HSV-2 is one of the most common sexually transmitted lifelong infections. It is the predominant cause of recurrent genital herpes and can cause severe complications in the immunocompromised and newborns. Furthermore, recent research has implicated HSV-2 infection with a higher risk of HIV infection and transmission. In Canada, approximately 19% of the population is infected with HSV-2.
The immune response to HSV-2 involves both an innate and adaptive immune response. My project focuses on the innate immune response, which controls early viral replication and stimulates the adaptive immune response to clear the infection. More specifically, we are interested in the interplay between type I interferon (a protein with antiviral effects), natural killer cells (innate immune cells important in controlling the early stages of infection), and nitric oxide (a potent antiviral molecule, capable of preventing viral replication). Studying these interactions and their importance in HSV-2 infection can lead to a better understanding of how this infection can be treated and contribute to new strategies for therapeutics against HSV-2.
I completed my undergraduate degree in Biology at McMaster. I completed my Master's degree in the Bienenstock lab, examining the effect of probiotic and antibiotic treatment on behaviour and the stress response (HPA axis) in mice. I joined the Ashkar lab as a research technician where I offer research support to our wonderful trainees and students.
After taking the Introduction to Immunology course I became extremely interested in the McMaster Immunology Research Centre and joined the Ashkar lab as an undergraduate Biochemistry co-op student in January 2015. My research in this lab focuses on autologous Natural Killer (NK) Cell Cancer Immunotherapy, which is the prospect of harnessing the power of a cancer patient's own immune cells to eradicate tumour cells.
During my co-op term, my first project looked at using umbilical cord blood as a valuable source for NK cell immunotherapy. I continued in the Ashkar lab for my fourth year senior thesis and started a new project, which aims to evaluate the clinical efficacy of Autologous NK Cell Cancer Immunotherapy as a second-line treatment for ovarian cancer.
Ovarian cancer (OC) is the fifth most common cancer in women and the leading cause of gynecological cancer-related deaths in both the USA and Europe. Eighty percent of patients experience disease reoccurrence after first-line surgery/chemotherapy regimens, thus there is a need for new second-line treatment modalities to improve the prognosis of ovarian cancer patients (OCPs). Ascites-derived natural killer cells (ascites-NK cells) from the peritoneal tumour environment of OCPs exhibit a protumorigenic phenotype and impaired cytotoxicity, which may play a role in perpetrating OC progression. We currently obtain clinical samples of peripheral blood and ascites from OCPs from the Juravinski Cancer Centre. Our group seeks to investigate the clinical efficacy of using an ex vivo expansion process to generate mature, activated expanded NK cells from the ascites of OCPs, for use in an autologous model of NK cell immunotherapy.
I completed my fourth year undergraduate thesis project in the Ashkar lab and have currently returned to work as a summer student. I was introduced to immunology very early on and it has become a great interest of mine. My project examines the role of type I IFN in the immune response to different Toll-like receptor (TLR) ligands.
Type I IFN is an important cytokine involved in the anti-viral immune response and suppression of viral replication. It has also been implicated in immune responses to bacterial infection. Bacterial and viral components are recognized by pattern recognition receptors on immune cells, in particular TLRs. Activation of TLRs leads to the release of pro-inflammatory cytokines, as well as type I IFN. A relationship between type I IFN and TLR signaling has been explored and I aim to further elucidate this. Type I IFN is an important regulator of immune responses and I hope to be able to clarify how it interacts with innate recognition of viral and bacterial components.
Lung cancer is the most common cause of cancer globally and has the highest cancer-related mortality both in Canada and worldwide. The current conventional treatments have not been successful in increasing the 5-year survival rate to a great extent; however the use of immunotherapies such as the adoptive transfer of Natural Killer (NK) cells in preclinical and clinical studies has shown promising results in a number of other cancer types such as melanoma. Considering the importance of NK cells in recognizing and eliminating cancer cells, developing autologous NK cell adoptive therapy by ex vivo expansion and activation of NK cells would utilize and enhance an individual’s ability to fight off cancerous cells in their body. My project’s aim is to investigate the potential of expanded NK cells as an adoptive cell transfer therapy against human lung cancer. To address this, we will investigate the ability of ex vivo expanded NK cells from peripheral blood of healthy volunteers and lung cancer patients to kill human primary lung tumor cells.
Breast cancer is the leading cause of cancer and the second leading cause of cancer death in Canadian women. It accounts for 26% of all new cancer cases and 14% of all cancer related deaths.1 Despite all efforts to eradicate the disease, there are several breast cancer subtypes that are extremely resistant to current cancer therapies, with very high recurrence rates and a poor survival outlook for patients. Several therapies targeting specific breast cancer subtypes have lately been investigated, one of which is cancer immunotherapy, which harnesses the powers of the immune system to treat cancer. A new emerging immunotherapy uses Natural Killer (NK) cells, a type of innate lymphocyte, as an adoptive cell therapy. NK cells have the ability to recognize and kill transformed cells and tumor cells, and hence they play a major role in cancer immune surveillance. Recent advances allowed our lab to generate millions of NK cells from only a few milliliters of peripheral blood from patients, clearing a major hurdle in the use of NK cells as an adoptive cell therapy.
My project focuses on the use of NK cells to target breast tumor. I mainly focus on the use of breast cancer patients’ NK cells to eliminate and kill their own tumor cells in the hopes that we can use autologous NK cell transfer (Figure 1) to treat breast cancer and breast cancer metastasis.
When embarking on a journey of scientific discovery it is essential to consider the ramifications your findings could have on the lives of people around the world. Therefore, contributing to a cure for cancer was a natural interest of mine as the effects of this disease on individuals with it and their families are innumerable. Furthermore, while cancer can be a debilitating disease on its own the current lack of specificity of classical cancer therapies such as chemotherapy and radiation can translate into detrimental side effects clinically.
The Ashkar lab provides me with the opportunity to develop a highly specific cancer therapy that harnesses the natural anti-tumoral capabilities of activated natural killer (NK) cells. With the proper cell culture techniques we can isolate NK cells from blood, activate them and use them to destroy cancerous cells through reintroduction to the patient. However, work must be done to optimize this process as tumours create unique microenvironments in the body which shut down NK cell cytotoxic capabilities and truncate NK development. Therefore, I work to delineate the requirements that must be met for an NK cell to successfully destroy cancerous cells.
I am currently studying Health Sciences at McMaster University and I have joined the Ashkar lab to work on my fourth year thesis project. I have great interest in the fields of virology and immunology, and for this reason I intended to undertake my project in this lab. My project will consist primarily of in vivo murine models, which examine the role of nitric oxide (NO) and IFN-γ in the genital mucosal site against HSV-2.
IFN-γ is a type II interferon produced by NK cells that has inhibitory effects on viral replication, stemming from its overarching immunostimulatory and immunomodulatory effects. It has been shown that IFN- γ is a potent inducer of NO production through nitric oxide synthases (NOS). NO plays an important antimicrobial role against numerous pathogens and is particularly effective in the clearance of viruses. Studies have demonstrated that exogenous sources of NO reduces replication of HSV-2 in various cell lines. Based on many preliminary results generated by the Ashkar Lab, we hypothesize that NK cell-derived IFN-γ induces the production of NO from innate immune cells, leading to a reduction in viral replication and a more effective adaptive immune response against HSV-2. The experiments that I conduct will elucidate the interactions between NO, IFN-γ, and NK cells in the context of innate antiviral activity in the genital mucosal site.
Our lab is very interested in the role of innate immunity in cancer. Tumor cells form in our bodies all the time, but our innate immune system usually finds and destroys these aberrant cells. It has been shown in animal models that boosting innate immunity has anti-cancer effects. The Ashkar lab has several projects investigating the role of IL-15, NK cells and macrophages in breast tumors. We utilize both in vitro and in vivo murine models to explore these topics. We have found that NK cells and their phenotype are able to impact spontaneous breast tumor formation. Ultimately, we wish to identify which cells of the innate immune system are important targets for cancer immunotherapies and how we could increase their potency.
Breast cancer is currently the most common cancer in Canadian women. My project focuses on enhancing the immune system to protect from breast tumor formation. IL-15 is an immune molecule that can affect multiple immune cell types involved in cancer destruction- including NK cells, CD8 T cells and macrophages. We have found that by increasing levels of IL-15 in mice that form spontaneous breast tumors, we are able to initiate tumor destruction, decrease metastasis and increase survival. In contrast, mice that lack IL-15 have faster tumor formation and poor survival. The aim of this study is to understand exactly how IL-15 overexpression/absence affects spontaneous breast tumor formation, progression and metastasis. The goal of this research is to identify the cell types that have been altered and their relative contribution to tumor progression/destruction. Furthermore, we want to identify other immune targets that enhance the actions of IL-15 on tumor destruction. Ultimately, this project involves basic research that will contribute to a new, more effective immunotherapy directed against breast cancer.
Emerging evidence over the last decade has defined obesity as a chronic low grade inflammatory condition, due to a dysregulation in the production of cytokines affecting the regulation of whole-body energy metabolism and the development of obesity. Our lab is very interested in understanding how pro-inflammatory cytokines, such as Interleukin-15 (IL-15), may play a role in the development of obesity and its associated chronic conditions. The Ashkar lab has several projects investigating the role of IL-15 in regulating adipose tissue and cormorbidities associated with obesity, utilizing both in vitro and in vivo murine models. We have found that varying IL-15 expression impacts fat mass and obesity development. It is our ultimate goal that additional insights into IL-15 biology and its effects on adipose tissue regulation will contribute to novel therapeutic strategies for the treatment and prevention of obesity.
The alarming global rise in the prevalence of obesity and its contribution to the development of chronic diseases is a serious health concern. Recently, obesity has been described as a chronic low grade inflammatory condition, influenced by both adipose tissue and immune cells suggesting pro-inflammatory cytokines may play a role in its etiology. Intriguing research has recently emerged examining the role of intestinal microorganisms in energy homeostasis and obesity. Variations in gut bacterial diversity exists between obese and lean individuals, suggesting differences in digestion and absorption could be important factors in the pathogenesis of obesity.
We previously examined the effects of Interleukin-15 (IL-15) on adipose tissue and its association with obesity . Although this cytokine is mainly known to activate immune cells such as Natural Killer (NK) cells , our data demonstrates over-expression of IL-15 results in a lean body condition, while lack of IL-15 results in a significant increase in weight gain. Treatment with IL-15 induces weight loss in obese mice placed on a high-fat diet independent of food intake. The presence of IL-15 also causes decreased lipid deposition upon differentiation of human adipose derived mesenchymal stem cells into adipocytes, suggesting IL-15 mediates these effects directly. Additionally, serum IL-15 is significantly lower in obese patients when compared to normal weight individuals, demonstrating an association with body fat mass. Also, since IL-15 is the main cytokine involved in NK cell development and function , it has yet to be determined if these cells play a role in IL-15 mediated weight loss in vivo.
For my fourth year undergraduate thesis, I joined the Ashkar lab with a vast interest in virology and microbiology. As I am looking to continue my education in bacterial and infectious disease research, working in the Ashkar lab has provided me opportunities to further appreciate these topics.
The replacement of antibiotic/antiviral treatment to drugless therapy to combat sexually transmitted infections has been a recently trending topic. As the number of STI cases skyrocket among teenagers and elders, new advances in the field are critical. My research primarily focuses on using natural immunity of the vaginal tract to enhance protection against STIs, such as bacterial vaginosis and genital herpes. Natural immunity of the vaginal mucosa encompasses the roles of glycogen derived from vaginal epithelial cells, commensal bacteria colonizing the vaginal tract and vaginal pH. The intimate relationship between these elements is yet to be definitively characterized, and thus we are interested in determining their interdependence. Additionally, natural immunity has been observed to fluctuate with age and reproductive capability. Studying such changes may provide insight into the increased susceptibility of STIs in elders and women taking contraception. The eventual goal of this project is to manipulate and enhance natural immunity and provide preventative measures, as well as treatments, against common STIs.
I am a fourth year student in the Bachelor of Health Sciences program at McMaster. I am currently undertaking my fourth year thesis project in the Ashkar Lab. My interest for immunology first sparked at a brief exposure to the subject during an anatomy and physiology course during my second year. My fascination with the immune system, specifically innate immunity, grew as I continued to take introductory and advanced immunology courses in my third year. This led to a decision to pursue research of the innate immune system, specifically natural killer cells, for my fourth year project.
It is well known that natural killer (NK) cells play an integral role in our innate immune system’s defense against viral infections. As such, the conditions and mechanisms by which NK cells are activated and inhibited are imperative to understand. One paradox that is in need of further exploration is the positive and negative regulatory effects of interferon (IFN)-alpha and IFN-beta on NK cell activation.
Type I IFN, secreted upon viral invasion of host tissue, has been shown to have differing effects on the activation of NK cells. First, type I IFN (IFN-alpha and IFN-beta) can activate NK cells via the JAK-STAT pathway to induce the production of the anti-viral cytokine IFN-gamma. However, it has also been shown that type I IFN can negatively regulate production of IFN-gamma. As such, my project explores the effects of type I IFN on NK cell activation.
Numerous reviews in the field of NK cell biology demonstrate the pivotal role that NK cells play in tumor rejection. Although these cell types were originally described based on their cytotoxic ability, we now know that NK cells are not necessarily born to kill. Both cellular interactions and the local environment in which the NK cell resides may influence its maturation. The tumor environment is an example of a localized site where NK cells are recruited to and may become dysfunctional. NK cells, which are present in tumor tissues, display a tumor associated NK cell phenotype characterized by decreased cytotoxicity, defective expression of activating receptors, and overexpression of inhibitory receptors.
The NK cells originally recruited to the tumor site are able to stimulate immune responses and aid in tumor destruction but eventually become influenced by mechanisms of immunosuppression. We believe that tumor associated macrophages play a large role in altering the functional capabilities of NK cells within a tumor. Tumor-associated macrophages (TAMs) are the main regulatory population of myeloid cells in the tumor and are characterized by their ability to promote tumor cell proliferation and metastasis. The aim of this study is to understand how tumor associated macrophages can effect NK cell phenotype and function within a tumor setting.
My research focus is in molecular virology and virus-host interactions. I earned an Honours B.Sc in Molecular Biology and Genetics from McMaster University in 2011. For my honours thesis I joined the Ashkar lab to understand mucosal immunity and to study virus-host interactions from the alternative perspective.
The current paradigm in Interleukin-15 (IL-15) biology states that its biological function is necessarily mediated through JAK/STAT signaling. This assertion stems from the study of IL-15 in the lymphoid lineage, in which JAK/STAT signaling is critical to IL-15 function. Outside of the lymphoid lineage, IL-15 can act on a broad range of cells including adipocytes, epithelium and macrophages.
Macrophages are an important component of mucosal innate immunity and the focus of my research. Previously, our lab has shown that macrophages can be primed into an anti-viral state with IL-15 pre-treatment. My research focuses on the characterization of the molecular mechanisms controlling IL-15-mediated macrophage priming. The research has lead me to explore alternative (non-JAK/STAT) signalling pathways through which IL-15 functions. These alternative signals may have important implications in understanding and redefining the biological activity of IL-15.
My broad area of interest is host-virus interactions. Though I have obtained extensive background in studying host-virus interactions relevant to agricultural animals, the aim of my post-doctoral work is to study innate immune responses at the mucosal surfaces to human viruses such as influenza A (H1N1) and herpes simplex virus-2, with a view of developing more effective control strategies against these human pathogens. Influenza A work has been directed to study the role of interleukin-15 and natural killer cells against this zoonotic pathogen in a mouse model. I am also working to see whether bacterial components could be used as innate immune stimulants against influenza A virus and herpes simplex virus-2 infections.
Interleukin-15 (IL-15) is a pro-inflammatory cytokine that plays many important roles within the immune system. For example, IL-15 is not only vital for the homeostasis and function of innate natural killer cells, but also maintains adaptive CD8+ memory T cell populations. IL-15 signals are delivered to these cells in vivo via trans-presentation, where accessory cells including macrophages and dendritic cells present IL-15 bound to its high affinity IL-15Rα chain in trans to the IL-2/IL-15Rβ and common γc chains expressed by responsive NK cells and CD8+ memory T cells. The trans-presentation of IL-15, which involves direct cell-to-cell contact and geographic compartmentalization of delivered signals, is thought to be the dominant means by which IL-15 signals in vivo. Alternatively, in monocytes and macrophages, IL-15 can signal via reverse signaling, leading to cell adhesion and cytokine production. In this model, membrane-bound IL-15 on the surface of the monocyte or macrophage performs as a receptor, while soluble IL-15Rα behaves as a ligand.
The focus of my study is to explore IL-15 and IL-15 receptor biology by investigating potential mechanisms of IL-15 signaling other than trans-presentation and reverse signaling, utilizing predominantly in vitro methodology. It is our ultimate goal that additional insights into the biology of IL-15 and its receptor may lead to novel therapeutic strategies aimed at bolstering immune responses against cancer and infectious disease.
Phil was involved in the Toll-like Receptor (TLR) project, focusing on TLR-mediated local cytokines in murine vaginal-associated lymphoid tissue. Phil worked in the lab while completing his Bachelor of Health Sciences (Honours) degree at McMaster.
Since leaving the Ashkar lab, Phil completed his medical degree. He is now living in South Australia and practicing Family Medicine.