Browsing by Author "Prat, Alexandre"

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    Analysis of the microglia transcriptome across the human lifespan using single cell RNA sequencing
    (2023-05-30) Yaqubi, Moein; Groh, Adam M. R.; Dorion, Marie-France; Afanasiev, Elia; Luo, Julia X. X.; Hashemi, Hadi; Sinha, Sarthak; Kieran, Nicholas W.; Blain, Manon; Cui, Qiao-Ling; Biernaskie, Jeff; Srour, Myriam; Dudley, Roy; Hall, Jeffery A.; Sonnen, Joshua A.; Arbour, Nathalie; Prat, Alexandre; Stratton, Jo A.; Antel, Jack; Healy, Luke M.
    Abstract Background Microglia are tissue resident macrophages with a wide range of critically important functions in central nervous system development and homeostasis. Method In this study, we aimed to characterize the transcriptional landscape of ex vivo human microglia across different developmental ages using cells derived from pre-natal, pediatric, adolescent, and adult brain samples. We further confirmed our transcriptional observations using ELISA and RNAscope. Results We showed that pre-natal microglia have a distinct transcriptional and regulatory signature relative to their post-natal counterparts that includes an upregulation of phagocytic pathways. We confirmed upregulation of CD36, a positive regulator of phagocytosis, in pre-natal samples compared to adult samples in situ. Moreover, we showed adult microglia have more pro-inflammatory signature compared to microglia from other developmental ages. We indicated that adult microglia are more immune responsive by secreting increased levels of pro-inflammatory cytokines in response to LPS treatment compared to the pre-natal microglia. We further validated in situ up-regulation of IL18 and CXCR4 in human adult brain section compared to the pre-natal brain section. Finally, trajectory analysis indicated that the transcriptional signatures adopted by microglia throughout development are in response to a changing brain microenvironment and do not reflect predetermined developmental states. Conclusion In all, this study provides unique insight into the development of human microglia and a useful reference for understanding microglial contribution to developmental and age-related human disease.
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    The Canadian prospective cohort study to understand progression in multiple sclerosis (CanProCo): rationale, aims, and study design
    (2021-10-27) Oh, Jiwon; Arbour, Nathalie; Giuliani, Fabrizio; Guenette, Melanie; Kolind, Shannon; Lynd, Larry; Marrie, Ruth A.; Metz, Luanne M.; Patten, Scott B.; Prat, Alexandre; Schabas, Alice; Smyth, Penelope; Tam, Roger; Traboulsee, Anthony; Yong, V. W.
    Abstract Background Neurological disability progression occurs across the spectrum of people living with multiple sclerosis (MS). Although there are a handful of disease-modifying treatments approved for use in progressive phenotypes of MS, there are no treatments that substantially modify the course of clinical progression in MS. Characterizing the determinants of clinical progression can inform the development of novel therapeutic agents and treatment approaches that target progression in MS, which is one of the greatest unmet needs in clinical practice. Canada, having one of the world’s highest rates of MS and a publicly-funded health care system, represents an optimal country to achieve in-depth analysis of progression. Accordingly, the overarching aim of the Canadian Prospective Cohort Study to Understand Progression in MS (CanProCo) is to evaluate a wide spectrum of factors associated with the clinical onset and rate of disease progression in MS, and to describe how these factors relate to one another to influence progression. Methods CanProCo is a prospective, observational cohort study with investigators specializing in epidemiology, neuroimaging, neuroimmunology, health services research and health economics. CanProCo’s study design was approved by an international review panel, comprised of content experts and key stakeholders. One thousand individuals with radiologically-isolated syndrome, relapsing-remitting MS, and primary-progressive MS within 10–15 years of disease onset will be recruited from 5 academic MS centres in Canada. Participants will undergo detailed clinical evaluation annually over 5 years (including advanced, app-based clinical data collection). In a subset of participants within 5–10 years of disease onset (n = 500), blood, cerebrospinal fluid, and research MRIs will be collected allowing an integrated, in-depth evaluation of factors contributing to progression in MS from multiple perspectives. Factors of interest range from biological measures (e.g. single-cell RNA-sequencing), MRI-based microstructural assessment, participant characteristics (self-reported, performance-based, clinician-assessed, health-system based), and micro and macro-environmental factors. Discussion Halting the progression of MS remains a fundamental need to improve the lives of people living with MS. Achieving this requires leveraging transdisciplinary approaches to better characterize why clinical progression occurs. CanProCo is a pioneering multi-dimensional cohort study aiming to characterize these determinants to inform the development and implementation of efficacious and effective interventions.