Development of novel biomarker assays in vascular diseases

Circulating MicroRNAs as Functional Biomarkers of Vascular Cognitive Impairment

Principal Investigator:
Dr. Mansoor Husain, Toronto General Research Institute

Dr. Jason Fish, Toronto General Research Institute

Our proposal addresses two priorities of the Canadian Vascular Network: “Development of robust preclinical models of VCI” and “Development of novel biomarkers for detection/prognostication of VCI”. Epidemiology has revealed that cardiovascular diseases, such as diabetes, are associated with VCI. While enhanced cerebrovascular inflammation in diabetics likely plays a contributing role in the development of VCI, this is difficult to assess in a non-invasive fashion. Identifying patients at risk for VCI may enable interventions to slow disease progression. Sadly, circulating markers that are specific for VCI are not available. Our proposal will utilize a mouse model of type-2 diabetes (T2D), which develops VCI pathology that is similar in many respects to human disease. We will assess circulating microvesicles (MVs) and their microRNA (miR) contents during the course of VCI progression in this model to identify novel markers of the early stages of the disease. We recently obtained intriguing data that demonstrate that circulating MVs are anti-inflammatory in healthy mice, which is mediated in part by the transfer of anti-inflammatory miRs to recipient cells (e.g. endothelial cells and monocytes). We have developed a robust assay to assess the function of MVs that can be utilized to determine whether the anti-inflammatory function of MVs is compromised in mouse models of VCI. Importantly, we have found that MVs isolated from mice with advanced cardiovascular disease lose their anti-inflammatory properties, but the relationship between this observation and development of VCI is not known. Our project will combine the expertise of the Husain lab in murine diabetic disease models with the expertise of the Fish lab in the analysis of MVs and miR function. The proposed studies will allow us to explore whether circulating MVs/miRs might be useful functional markers of VCI.

Evaluation of novel biomarkers to explain the link between prior preeclampsia and premature acute coronary syndrome in women: a GENESIS-PRAXY study

Principal Investigator:
Dr. Louise Pilote, McGill University Health Center

Dr. Duncan Stewart, Ottawa Hospital Research Institute
Dr. Natalie Dayan, McGill University Health Center

Dr. Kenny Schlosser, Ottawa Hospital Research Institute

Cardiovascular disease (CVD), including acute coronary syndromes (ACS), may be related to microvascular endothelial dysfunction in women. Risk factors for CVD unique to women include the occurrence of pregnancy complications such as preeclampsia. Preeclampsia is a complex hypertensive disorder of pregnancy that is related to improper placentation and subsequent maternal endothelial injury. It is possible that changes to the microvascular endothelium in women with preeclampsia may predispose to the future development of CVD.

There is increasing interest in microRNAs (miRNAs) as key intracellular regulators of gene expression, and as extracellular biomarkers of various disease states including CVD. We speculate that hierarchical clustering of serum miRNA profiles may reveal unique expression patterns between female patients with premature (< 55 years) ACS who have experienced preeclampsia as compared to those who have had a normotensive pregnancy.

GENESIS-PRAXY is a cohort of men and women with premature ACS. Of these, 306 women have had prior pregnancies: 230 with normotensive pregnancy, and 27 with preeclampsia. We propose to assess for a difference in both traditional biomarkers as well as patterns of expression of candidate miRNAs in women with premature ACS who have had preeclampsia compared to those with prior normotensive pregnancy.

This study is directly related to Research Theme 2 (Identifying novel methods of early detection of vascular conditions) of the Canadian Vascular Network and more specifically project 4 (Identifying novel biomarkers for early detection of CVD and VCI). The PRAXY cohort has frozen serum samples that can be used to respond directly to the 2 objectives: 1.To establish relevant experimental models to be used in identifying novel biomarkers for small vessel disease; and 2.To begin exploring the value of these novel indicators of microvascular disease to identify populations at risk.

Cognitive Impairment Post-Oophorectomy: Assessment of Novel Markers of Vascular-Health

Principal Investigator:
Dr. Edward O’Brien, Libin Cardiovascular Institute of Alberta

Dr. Todd Anderson, Libin Cardiovascular Institute of Alberta

Gillian Einstein
, University of Toronto
Preben  Kjølhede, Universitetssjukhuset, Sweden
Ninnie Borendal Wodlin, Universitetssjukhuset, Sweden
Liane Belland, University of Calgary
William Gerthoffer, University of South Alabama
Khokan Sikdar, University of Calgary

Women with a family history of certain cancers are often screened for gene mutations, and if found may elect to undergo surgical removal of their ovaries and fallopian tubes (i.e., a prophylactic salpingo-oophorectomy, PSO). Although PSO prevents cancer, the impact of this surgery on young women is not trivial as premature menopause will impact a woman’s cardiovascular health and potentially cognitive / mental health. Our ultimate goal aligns with Research Theme 2 and seeks to better understand if menopause results in vascular cognitive impairment.  To do this we will pursue two smaller projects in this seed grant that will allow us generate important data for a subsequent larger grant that encompasses our ultimate goal.  Specific Aim #1: In conjunction with Dr. Gillian Einstein (Laboratory of Cognitive Neuro-Sciences and Women’s Health, Dept. Psychology, Univ. Toronto) we will investigate the role of estrogen deprival post-PSO on cognitive function (qualitative and imaging studies) and relate this to a circulating biomarker of vascular disease, Heat Shock Protein 27 (HSP27). Dr. O’Brien’s laboratory studies ovarian hormone-related vascular protection, and discovered HSP27 as a potential down-stream “foot soldier” of estrogens, that is “vascular protective” and now recognized as a novel biomarker of cardiovascular events (MI, stroke, death).

Specific Aim #2: In conjunction with Dr. Todd Anderson, an expert in the study of microvascular dysfunction, we will validate the connection between vascular physiologic parameters (such as “VTI”) and levels of HSP27 in his “FATE” CAD cohort. Hence, with completion of these two specific aims we will be able to explore in future studies the correlation of vascular markers such as HSP27 and VTI with vascular cognitive impairment.