Research Pillar: Biomedical

The acute impact of spinal cord injury on cardiac function, and novel hemodynamic management in SCI patients

Following acute spinal cord injury (SCI), one of the only presently available neuroprotective strategies is to try and optimize management of spinal cord blood flow. This treatment specifically aims to immediately increase blood flow to the injured spinal cord tissue to prevent the spread of injury to surrounding spinal cord tissues.
Currently, vasopressors are administered to increase blood pressure to a similar threshold in all patients; however, its efficacy in improving neurological outcomes has not been consistent, and in some patients has been found to actually worsen outcomes. A more optimized and individualized approach to blood flow management in SCI patients is needed.

High-thoracic SCI immediately impairs the brainstem and neural control of the heart. Our pilot data suggest this decentralization of the heart immediately impairs cardiac function, which could have significant implications for the acute management of blood flow in SCI patients. Dr. Williams will investigate the immediate and acute cardiac responses to high-thoracic SCI, and determine whether improvements to cardiac function can improve spinal cord blood flow and neurological outcomes in SCI patients.

Dr. Williams will conduct translational studies utilizing a porcine model of SCI. She will test the efficacy of potential novel management strategies, including restoring cardiac function alone or in combination with vasopressor therapy. A simultaneous study will look at acutely injured individuals with SCI at Vancouver General Hospital, examining heart function during the first three days after injury.

To date, very little work has characterized the impact of SCI on cardiac function in the initial period following injury. Combining invasive and integrative studies in pigs and humans provides us with the unique opportunity to conduct highly translatable studies that could have an immediate impact on SCI patient outcomes.

 

End of Award Update – July 2022

Most exciting outputs
Our research to date has identified how high-level spinal cord injuries (i.e. at or above the mid-back level) impact the heart immediately after the injury occurs. We found that those injuries impact the heart’s output within the first hours post-injury, and further identified a treatment that could harness the heart to support blood pressure and potentially reduce secondary damage to the spinal cord.

 

Impacts so far
The award has allowed us to examine alternative approaches to treating acute spinal cord injury which could ultimately improve outcomes if that approach is effective in the clinical setting. Moreover, as a trainee this award has provided the critical opportunity for me to expand my skillset in the realms of clinical and pre-clinical research, and apply gold-standard techniques to answer questions about the heart that have traditionally been overlooked in the field of spinal cord injury research.

 

Potential future influence
With the support of this award I have made significant strides in my training toward becoming an established cardiovascular researcher. First, it has allowed me to expand my expertise in the heart and its neural control. Second, I have gained invaluable experience in clinical and pre-clinical research, which truly round out my training as a physiologist. Finally, I have been able to produce and output impactful research across those domains and in doing so built strong collaborations with local and international leaders in these respective fields.

 

Next steps
We have yet to publish additional research that has stemmed from this award, looking at the long-term benefits of heart-focused approaches to treating spinal cord injury, and would like to pursue opportunities to implement such an approach in the clinical setting.

 

Useful links

The role of PCSK9 in clearance of bacterial lipids and the development of anti-PCSK9 treatment for sepsis

Sepsis, which is characterized as an uncontrolled inflammatory response to severe infection, is the leading cause of death in intensive care units. In Canada, sepsis led to a total of 13,500 deaths in 2011, which translates to approximately one in 18 deaths in Canada involving sepsis. Despite this pressing medical need, there are currently no effective treatments for sepsis. 

It is well established that bacterial lipids, such as lipopolysaccharide (LPS) in Gram-negative bacteria and lipoteichoic acid (LTA) in Gram-positive bacteria, induce aberrant inflammatory response in sepsis and they associate with various lipoprotein fractions in the blood. Recent research has revealed that septic patients with Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) loss-of-function mutations have better survival rates due to increased bacterial lipid clearance. It is likely that inhibition of PCSK9 leads to enhanced clearance of bacterial lipids and thus an improved chance of survival. 

Dr. Leung will characterize the role of PCSK9 in these two major pathways of bacterial lipid clearance by utilizing a novel in vivo imager to monitor the distribution of fluorescently-tagged LPS and LTA in mice. He will assess the therapeutic potential of PCKS9 inhibition by examining the ability of anti-PCSK9 monoclonal antibodies to clear bacterial lipid-laden LDL and VLDL through the LDLR and VLDLR pathways, respectively. 

Dr. Leung’s research will address a current knowledge gap in the role of lipoprotein pathways in the clearance of inflammatory bacterial lipids from circulation. 

 

Evolutionary determinants of treatment resistant high grade serous ovarian cancer investigated at single cell resolution

Women diagnosed with high grade serous ovarian cancer (HGS) continue to face poor prognosis, with ten-year survival at only 30-40%. Surgical cytoreduction followed by platinum and taxane-based chemotherapy result in clinical remission for a majority of patients. However, up to 80% of patients will suffer relapse because their disease is treatment resistant. Improved outcomes for HGS require both biomarkers of treatment resistance and development of additional treatments targeting tumour cells resistant to first line therapies.

Relapse in HGS is thought to result from the emergence of resistant tumour clones that evolve de-novo or are selected for during treatment. Dr. McPherson will leverage state-of-the-art single cell genome sequencing technologies to study the genomes of treatment naive primary and metastatic HGS samples, in addition to patient derived xenografts subjected to chemotherapeutic agents. His analysis will focus on understanding the genomic changes that confer treatment resistance, and the evolutionary dynamics that produce those changes.

An improved understanding of the mechanisms and dynamics of treatment resistance will result in improved ability to identify patients with relapse potential and provide targeted therapies to improve survival in HGS.

 

Targeting stress granules: A novel strategy to inhibit Ewing sarcoma metastasis

Metastatic disease remains the single most powerful predictor of adverse outcomes in Ewing sarcoma (ES) and other childhood sarcomas (malignant connective tissue tumours). High risk ES appears to be characterized by uninhibited outgrowth of neoplastic clones that have acquired additional genomic or epigenomic alterations, which facilitate the spread of the cancer cells. 

Considerable research has focused on understanding the genetic and biomolecular alterations that underlie ES, including drug resistance. The challenge is to identify targetable events that can be used to characterize metastatic disease, which is widely held as an inefficient process, with only a tiny fraction of primary tumour cells surviving. 

Emerging evidence suggests that a largely overlooked component of the spread of tumour cells is the impact of stress adaptation, occurring through acute changes in mRNA translation and protein synthesis. It is likely that specific ribonucleoprotein complexes known as stress granules (SG) are intimately connected to cancer biology, and even resistance to chemotherapy. However, targeting these structures in cancer cells has not been widely pursued. Dr. El-Naggar’s research will focus on understanding the link between stress granules  and conditions that promote the spread of cancer cells. 

 

Unraveling the genetics of severe reactions to chemotherapy: Moving towards maximum benefit with minimal harm

Drug treatments are essential for the survival of cancer patients. Unfortunately, medications needed for treatment can also cause permanent disabling side effects, severely impacting on the quality of life of patients already suffering the devastating consequences of cancer.

Although platinum-based drugs such as cisplatin are highly effective and are the most frequently used class of cancer medications, they are also accompanied by severe side effects. In fact, up to 80% of patients treated with cisplatin lose some ability to hear and/or experience kidney injury.

If clinicians were able to predict which patients are most likely to experience these side effects before prescribing cisplatin, they could take measures to avoid their occurrence. Pharmacogenomics, the study of how genetic differences influence why we respond differently to medications, aims to provide clinicians with this predictive information.

Dr. Drogemoller will investigate patients receiving cisplatin to identify the genetic and clinical variables that are associated with high risk of kidney failure and hearing loss. She will use these results to guide the development of predictive tests and novel treatment strategies. The results of this research will allow for the implementation of personalized treatment strategies which optimize benefits and reduce the chance of harm for cancer patients.

 

Molecular mechanisms of complex carbohydrate uptake by human gut microbiota

The complex microbial ecosystem inhabiting the distal human gut, known as the gut microbiota, is inextricably linked to human health, playing central roles in maintaining host immunity, safeguarding the host against pathogens, and extracting energy from the otherwise indigestible complex carbohydrates found in dietary fibre. 

Dysbiosis, an imbalance in the gut microbiota, is linked to a range of diseases, including inflammatory bowel diseases, metabolic syndrome, and Type 2 Diabetes. A growing body of evidence supports a role for microbial therapeutics, such as commercially available probiotics, in mitigating the effects of some dysbiosis-associated conditions. However, the implementation of novel, customizable therapeutics depends on the establishment of a comprehensive repository of species with known energetic requirements and ecological behaviours. 

Currently we lack atomic-resolution insight into the molecular machinery required for complex carbohydrate utilization by key gut symbionts. Understanding this machinery is critical to understanding the role of carbohydrate utilization in shaping microbial communities in the human gut.

Dr. Grondin will employ structural biology in a systems-based approach, incorporating complimentary bacterial genetics and carbohydrate biochemistry to determine the atomic structures of transport protein machinery  in complex with the related substrates. Comparative structure-function studies of carbohydrate-transporters, including measuring transport specificity and kinetics across substrate type and bacterial phylogeny, will delineate the role of individual complexes in fuelling microbial ecosystems. This research will provide detailed insights into the molecular mechanisms associated with the selective recognition, transport and metabolism of complex carbohydrates by the human gut microbiota. The results of will inform the development of therapeutics to address growing health concerns associated with microbiotal imbalance, such as inflammatory bowel diseases, metabolic syndrome, and Type 2 Diabetes. 

 

Development of a flow cytometry assay for accurate and selective measurement of lysosomal GBA1 activity in PBMC

Recently, loss-of-function mutations of the GBA1 gene, which encodes glucocerebrosidase (GCase), have been characterized as a major genetic risk for Parkinson’s disease (PD). Patients carrying these mutations have a much higher incidence of PD, earlier onset, and more severe disease.

These data strongly suggest that GCase activity may be useful for early diagnosis as well as monitoring the progression of PD. Dr. Gros will build on her previous work describing a substrate that specifically measures GCase activity both in vitro and in neuronal cells in microscopy. This research will lead into a proof-of-concept clinical study, using a flow cytometry assay to establish correlations between the progression of PD, GBA1 mutant status and GCase activity.

The results of this study will lead to the development of a new assay for clinical studies that will benefit Parkinson’s patients and deepen our overall understanding of the disease.

 

Evaluation of the role of FRMP on BDNF expression and signaling

Fragile-X syndrome (FXS) is the most common form of inherited intellectual disability and is the best characterized form of autism spectrum disorder. This genetic condition is caused by a mutation in the FMR1 gene, leading to the functional loss of FMR1 protein (FMRP). Besides being important for neuronal development, this protein also exerts a strong influence on synaptic plasticity. As a matter of fact, FMRP is highly expressed in the dentate gyrus (DG) of the hippocampus, one of the few regions of the adult brain where the birth of new neurons takes place. 

To understand this relationship, it is important to clarify the role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of FXS. BDNF is an important regulator of neural circuit development and function, and is thus strongly implicated in the development and treatment of several neurological conditions. Interestingly, it has been shown that BDNF and FMRP may reciprocally regulate each other.

However, BDNF is a complex signaling molecule, and its pro- and mature forms can elicit opposing biological effects. Thus, to fully understand the interaction between FMRP and BDNF it is important to study both its pro- and mature forms. Dr. Bettio will investigate how FMRP regulates BDNF/pro-BDNF expression in distinct brain regions and how changes in BDNF expression contribute to hippocampal circuit dysfunction and plasticity defects in FXS. 

The results of this study will expand scientific knowledge about the molecular mechanisms implicated in FXS, and will be key in the development of future BDNF-based therapeutic strategies.

 

Targeting neural transcription factor BRN2 in neuroendocrine tumours

One in eight men in Canada will be diagnosed with prostate cancer in their lifetime. Despite the availability of surgical, radiological and drug treatment options, many patients develop castration resistant prostate cancer (CRPC), an incurable disease which is especially resistant to drugs. In its most lethal form, drug resistant CRPC behaves like a neuroendocrine cancer, which is completely unresponsive to traditional prostate cancer therapies. 

In his model of drug resistant CRPC, Dr. Munuganti has identified a molecular pathway that appears to be essential for prostate cancer to take on neuroendocrine features. A key protein in this pathway, BRN2, is high in patients with neuroendocrine prostate cancer and is critical for neuroendocrine tumour growth in a laboratory model. BRN2 expression also plays a critical role in other neuroendocrine cancers such as small cell lung cancer and Ewing sarcoma. There is an urgent need to develop drugs that have the ability to inhibit the function of BRN2 for the treatment of patients with deadly neuroendocrine tumors.

Using high-powered and intelligently designed computer models, Dr. Munuganti has developed drug prototypes that have the ability to prevent BRN2 from supporting neuroendocrine cancer cell growth in our laboratory models. Dr. Munuganti’s study will fine-tune the drug-like properties of the leading BRN2 inhibitors and test them in biological models of neuroendocrine cancers. The results of this research could lead to the development of new therapies capable of reducing or slowing the growth of lethal neuroendocrine cancers, substantially improving patient survival.

Findings will be presented at conferences and seminars such as AACR Annual Meetings and the ASCO Annual Meeting, providing an opportunity to exchange ideas with other researchers and clinicians in the field and opening up possible collaborations. The ultimate goal of this study will be to commercialize a BRN2 inhibitor for patients suffering from no-cure neuroendocrine tumours.

 

The maladaptive effects of wood smoke on abdominal aortic aneurysms

Cardiovascular disease is the leading cause of death worldwide. Approximately 80% of all aneurysms that form within the aorta (the major blood vessel that deliveries oxygenated blood to the body) occur in the abdominal region. These are classified as abdominal aortic aneurysms (AAA). AAA is associated with progressive weakening and, ultimately, rupture of the vessel wall, causing rapid and extreme blood loss and a high rate of mortality. Sadly, aneurysm rupture is often the first sign of the disease and many die before reaching a hospital. For those that are diagnosed, treatment is currently limited to open chest or endovascular surgical repair. However, surgical repair of AAA is a risky, complex procedure with a high mortality rate. 

In the past 40 years there has been a worldwide increase in forest fires. Although cigarette smoke is known to induce and advance AAA, the effect of wood smoke on blood vessel remodelling and AAA is currently unknown. Interestingly, firefighters are at a four times greater risk for having a heart attack compared to other emergency response personnel. In fact, firefighters are at a greater risk of dying from cardiovascular disease than from on the job burn injury. Although smoke exposure is thought to play a major role in the majority of firefighter cardiovascular deaths, the processes by which wood smoke may promote cardiovascular disease and AAA is unknown.

Granzyme B (GzmB) is an enzyme that breaks down the protein-based scaffolding between cells that is important in sustaining tissue structure and function. Human and mouse models of AAA have shown that GzmB expression is increased within the blood vessel wall of aneurysms and its degree of expression is directly related with aneurysm rupture. In animal models, drugs that inhibit of GzmB prevent aneurysm rupture and increase survival. Although cigarette smoke is associated with increased GzmB levels in those with lung disease such as COPD, the link between wood smoke, GzmB and AAA is not known.

Dr. Zeglinski will examine the effect of repeated exposure to wood smoke on GzmB expression in the vessel wall and its effect on AAA progression. To explore this relationship, he will use a well-established mouse model of AAA and determine what, if any, effect that wood smoke has on aneurysm formation and rupture. 

The results of this research could lead to the development of new drugs to treat AAA, a devastating disease with few treatment options. Should the results confirm that GzmB is involved in AAA, Dr. Zeglinski will team up with clinicians for a clinical study to assess the levels of GzmB in those who have been diagnosed or have died from an AAA. By translating findings from the bench to the clinic, Dr. Zeglinski will later be able to partner with drug companies to develop a novel therapeutic agent to block GzmB action to slow or stop the progression of AAA and prevent AAA ruptures.