Publications by authors named "Nathalie Arbour"

56 Publications

Identification of SARS-CoV-2-specific immune alterations in acutely ill patients.

J Clin Invest 2021 Feb 26. Epub 2021 Feb 26.

Department of Neurosciences, CRCHUM University of Montreal, Montreal, Canada.

Dysregulated immune profiles have been described in symptomatic SARS-CoV-2-infected patients. Whether the reported immune alterations are specific to SARS-CoV-2 infection or also triggered by other acute illnesses remains unclear. We performed flow cytometry analysis on fresh peripheral blood from a consecutive cohort of i) patients hospitalized with acute SARS-CoV-2 infection; ii) patients of comparable age/sex hospitalized for other acute disease (SARS-CoV-2 negative); and iii) healthy controls. Using both data-driven and hypothesis-driven analyses, we found several dysregulations in immune cell subsets (e.g., decreased proportion of T cells) that are similarly associated with acute SARS-CoV-2 infection and non-COVID-19 related acute illnesses. In contrast, we identified specific differences in myeloid and lymphocyte subsets that are associated with SARS-CoV-2 status (e.g., elevated proportion of ICAM-1+ mature/activated neutrophils, ALCAM+ monocytes, and CD38+CD8+ T cells). A subset of SARS-CoV-2-specific immune alterations correlated with disease severity, disease outcome at 30 days and mortality. Our data provide an understanding of the immune dysregulation that are specifically associated with SARS-CoV-2 infection among acute care hospitalized patients. Our study lays the foundation for the development of specific biomarkers to stratify SARS-CoV-2+ patients at risk of unfavorable outcome and uncover candidate molecules to investigate from a therapeutic perspective.
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http://dx.doi.org/10.1172/JCI145853DOI Listing
February 2021

Interleukin-15 enhances proinflammatory T-cell responses in patients with MS and EAE.

Neurol Neuroimmunol Neuroinflamm 2021 01 15;8(1). Epub 2020 Dec 15.

From the Department of Neurosciences (C. Laurent, G.D., M.-L.C., A.C.M., N.F.-k., M.G., P.D., A.P., C. Larochelle, N.A.), Université de Montréal and CRCHUM; and MS-CHUM Clinic (M.G., P.D., A.P., C. Larochelle), Québec, Canada.

Objective: We posit that interleukin-15 (IL-15) is a relevant contributor to MS pathobiology as this cytokine is elevated in the CNS and periphery of patients with MS. We aim to investigate (1) the impact of IL-15 on T lymphocytes from patients with MS and (2) the in vivo role of IL-15 using the experimental autoimmune encephalomyelitis (EAE) mouse model.

Methods: We compared the impact of IL-15 on T lymphocytes obtained from untreated patients with MS (relapsing-remitting, secondary progressive, and primary progressive) to cells from age/sex-matched healthy controls (HCs) using multiparametric flow cytometry and in vitro assays. We tested the effects of peripheral IL-15 administration after EAE disease onset in C57BL/6 mice.

Results: IL-15 triggered STAT5 signaling in an elevated proportion of T cells from patients with MS compared with HCs. This cytokine also enhanced the production of key proinflammatory cytokines (interferon γ, granulocyte-macrophage colony-stimulating factor [GM-CSF], IL-17, and tumor necrosis factor) by T cells from both MS and controls, but these effects were more robust for the production of IL-17 and GM-CSF in T-cell subsets from patients with MS. At the peak of EAE disease, the proportion of CD4 and CD8 T cells expressing CD122, the key signaling IL-15 receptor chain, was enriched in the CNS compared with the spleen. Finally, peripheral administration of IL-15 into EAE mice after disease onset significantly aggravated clinical scores and increased the number of inflammatory CNS-infiltrating T cells long term after stopping IL-15 administration.

Conclusions: Our results underscore that IL-15 contributes to the amplification of T-cell inflammatory properties after disease onset in both MS and EAE.
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http://dx.doi.org/10.1212/NXI.0000000000000931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7745728PMC
January 2021

Increased frequency of proinflammatory CD4 T cells and pathological levels of serum neurofilament light chain in adult drug-resistant epilepsy.

Epilepsia 2021 Jan 2;62(1):176-189. Epub 2020 Nov 2.

Research Center of the University of Montreal Hospital Center, Montreal, QC, Canada.

Objective: Adult drug-resistant epilepsy (DRE) is associated with significant morbidity. Infiltration of immune cells is observed in DRE epileptic foci; however, the relation between DRE and the peripheral immune cell compartment remains only partially understood. We aimed to investigate differences in immune cell populations, cytokines, and neurodegenerative biomarkers in the peripheral blood of subjects with epilepsy versus healthy controls, and in DRE compared to well-controlled epilepsy (WCE).

Methods: Peripheral blood mononuclear cells and serum from >120 age- and sex-matched adults suffering from focal onset epilepsy and controls were analyzed by multipanel flow cytometry, multiplex immunoassays, and ultrasensitive single molecule array.

Results: Using a data-driven analytical approach, we identified that CD4 T cells in the peripheral blood are present in a higher proportion in DRE patients. Moreover, we observed that the frequency of CD4 T cells expressing proinflammatory cytokines interleukin (IL)-17A, IL-22, tumor necrosis factor, interferon-γ, and granulocyte-macrophage colony-stimulating factor, but not anti-inflammatory cytokines IL-10 and IL-4, is elevated in the peripheral blood of DRE subjects compared to WCE. In parallel, we found that Th17-related circulating proinflammatory cytokines are elevated, but Th2-related cytokine IL-4 is reduced, in the serum of epilepsy and DRE subjects. As Th17 cells can exert neurotoxicity, we measured levels of serum neurofilament light chain (sNfL), a marker of neuronal injury. We found significantly elevated levels of sNfL in DRE compared to controls, especially among older individuals.

Significance: Our data support that DRE is associated with an expansion of the CD4 Tcell subset in the peripheral blood and with a shift toward a proinflammatory Th17/Th1 CD4 Tcell immune profile. Our results further show that pathological levels of sNfL are more frequent in DRE, supporting a potential neurodegenerative component in adult DRE. With this work, we provide evidence for novel potential inflammatory and degenerative biomarkers in DRE.
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http://dx.doi.org/10.1111/epi.16742DOI Listing
January 2021

Interleukin-26, preferentially produced by T17 lymphocytes, regulates CNS barrier function.

Neurol Neuroimmunol Neuroinflamm 2020 11 11;7(6). Epub 2020 Aug 11.

From the Neuroimmunology Unit and Multiple Sclerosis Clinic (B.B., S.Z., E.G., M.C., M.-A.L., O.T., L.H., L.B., J.-P.O., F.L., S.L., R.C., B.L., J.P., P.D., N.A., E.P., A.P.), The Research Center of the Centre Hospitalier de l'Université de Montréal (CRCHUM), Department of Neuroscience, Faculty of Medicine, Université de Montréal, Canada; Hasselt University (B.B.), Biomedical Research Institute and Transnationale Universiteit Limburg, School of Life Sciences, Diepenbeek, Belgium; and Division of Neurosurgery (A.B., R.M.), Centre Hospitalier de l'Université de Montréal (CHUM), Faculty of Medicine, Université de Montréal, Canada.

Objective: To investigate the involvement of interleukin (IL)-26 in neuroinflammatory processes in multiple sclerosis (MS), in particular in blood-brain barrier (BBB) integrity.

Methods: Expression of IL-26 was measured in serum, CSF, in vitro differentiated T helper (T) cell subsets, and postmortem brain tissue of patients with MS and controls by ELISA, quantitative PCR, and immunohistochemistry. Primary human and mouse BBB endothelial cells (ECs) were treated with IL-26 in vitro and assessed for BBB integrity. RNA sequencing was performed on IL-26-treated human BBB ECs. Myelin oligodendrocyte glycoprotein experimental autoimmune encephalomyelitis (EAE) mice were injected IP with IL-26. BBB leakage and immune cell infiltration were assessed in the CNS of these mice using immunohistochemistry and flow cytometry.

Results: IL-26 expression was induced in T lymphocytes by T17-inducing cytokines and was upregulated in the blood and CSF of patients with MS. CD4IL-26 T lymphocytes were found in perivascular infiltrates in MS brain lesions, and both receptor chains for IL-26 (IL-10R2 and IL-20R1) were detected on BBB ECs in vitro and in situ. In contrast to IL-17 and IL-22, IL-26 promoted integrity and reduced permeability of BBB ECs in vitro and in vivo. In EAE, IL-26 reduced disease severity and proinflammatory lymphocyte infiltration into the CNS, while increasing infiltration of Tregs.

Conclusions: Our study demonstrates that although IL-26 is preferentially expressed by T17 lymphocytes, it promotes BBB integrity in vitro and in vivo and is protective in chronic EAE, highlighting the functional diversity of cytokines produced by T17 lymphocytes.
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http://dx.doi.org/10.1212/NXI.0000000000000870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428369PMC
November 2020

Marital quality and inflammation: The moderating role of early life adversity.

Health Psychol 2020 Jan 12;39(1):58-67. Epub 2019 Sep 12.

Department of Psychology.

Objective: Although positive marital quality is usually associated with lower chronic low-grade inflammation, not everyone benefits equally from spousal support. Exposure to early life adversity (ELA) has been proposed as a factor that may impede the social buffering effect of positive social relationships. The goal of this study was to test whether ELA would moderate the impact of marital quality on inflammation.

Method: This cross-sectional study examined 168 partnered middle-aged women who either were experiencing a current chronic caregiving stressor, raising an adolescent with an autism spectrum disorder or intellectual disability, or who had the normative parenting experience of raising a typically developing adolescent. Participants completed self-report questionnaires on marital satisfaction, dyadic coping, and perceived partner responsiveness to create a composite index of marital quality, and they filled out the Childhood Trauma Questionnaire to assess ELA exposure. Participants also provided plasma samples for the assessment of interleukin-6, tumor necrosis factor-α, and C-reactive protein, three circulating biomarkers of inflammation.

Results: ELA moderated the association between marital quality and inflammation. Among individuals who endorsed lower ELA exposure, there was a significant, negative association between marital quality and interleukin-6 and tumor necrosis factor-α levels. However, this association was attenuated and not statistically significant among participants who reported higher ELA exposure. This effect was independent of current chronic stress.

Conclusions: These findings suggest that ELA may impair the social buffering effect of marital quality on inflammation. This impaired social buffering effect may be another mechanism through which ELA promotes sustained elevations in inflammation over time. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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http://dx.doi.org/10.1037/hea0000790DOI Listing
January 2020

Gross Motor Skills Training Leads to Increased Brain-Derived Neurotrophic Factor Levels in Healthy Older Adults: A Pilot Study.

Front Physiol 2019 12;10:410. Epub 2019 Apr 12.

Montreal Heart Institute, Montreal, QC, Canada.

Exercise is recognized as a promising approach to counteract aging-associated declines in cognitive functions. However, the exact molecular pathways involved remain unclear. Aerobic training interventions and improvements in peak oxygen uptake (VOpeak) have been associated with increases in the peripheral concentration of brain-derived neurotrophic factor (BDNF) and better cognitive performances. However, other training interventions such as resistance training and gross motor skills programs were also linked with improvements in cognitive functions. Thus far, few studies have compared different types of physical exercise training protocols and their impact on BDNF concentrations, especially in participants over 60 years old. The main objective of this study was to compare the effects of three exercise protocols on plasma BDNF concentrations at rest in healthy older adults. Thirty-four older adults were randomized into three interventions: (1) lower body strength and aerobic training (LBS-A), (2) upper body strength and aerobic training (UBS-A), or (3) gross motor activities (GMA). All interventions were composed of 3 weekly sessions over a period of 8 weeks. Physical, biochemical, and cognitive assessments were performed pre and post-intervention. All interventions resulted in improved cognitive functions but the GMA intervention induced a larger increase in plasma BDNF concentrations than LBS-A. No correlation was observed between changes in BDNF concentrations and cognitive performances. These findings suggest that a program of GMA could lead to enhancements in plasma BDNF concentrations. Moreover, cognition improvement could occur without concomitant detectable changes in BDNF, which highlights the multifactorial nature of the exercise-cognition relationship in older adults.
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http://dx.doi.org/10.3389/fphys.2019.00410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6473056PMC
April 2019

NKG2D and Its Ligand MULT1 Contribute to Disease Progression in a Mouse Model of Multiple Sclerosis.

Front Immunol 2019 6;10:154. Epub 2019 Feb 6.

Department of Neurosciences Université de Montréal, Montreal, QC, Canada.

NKG2D is an activating receptor expressed on the surface of immune cells including subsets of T lymphocytes. NKG2D binds multiple ligands (NKG2DL) whose expression are differentially triggered in a cell type and stress specific manner. The NKG2D-NKG2DL interaction has been involved in autoimmune disorders but its role in animal models of multiple sclerosis (MS) remains incompletely resolved. Here we show that NKG2D and its ligand MULT1 contribute to the pathobiology of experimental autoimmune encephalomyelitis (EAE). MULT1 protein levels are increased in the central nervous system (CNS) at EAE disease peak; soluble MULT1 is elevated in the cerebrospinal fluid of both active and passive EAE. We establish that such soluble MULT1 enhances effector functions (e.g., IFNγ production) of activated CD8 T lymphocytes from wild type but not from NKG2D-deficient ( mice . The adoptive transfer of activated T lymphocytes from wild type donors induced a significantly reduced EAE disease in compared to wild type () recipients. Characterization of T lymphocytes infiltrating the CNS of recipient mice shows that donor (CD45.1) rather than endogenous (CD45.2) CD4 T cells are the main producers of key cytokines (IFNγ, GM-CSF). In contrast, infiltrating CD8 T lymphocytes include mainly endogenous (CD45.2) cells exhibiting effector properties (NKG2D, granzyme B and IFNγ). Our data support the notion that endogenous CD8 T cells contribute to passive EAE pathobiology in a NKG2D-dependent manner. Collectively, our results point to the deleterious role of NKG2D and its MULT1 in the pathobiology of a MS mouse model.
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http://dx.doi.org/10.3389/fimmu.2019.00154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6372829PMC
January 2020

CD4 Regulatory T Lymphocytes Prevent Impaired Cerebral Blood Flow in Angiotensin II-Induced Hypertension.

J Am Heart Assoc 2019 01;8(1):e009372

2 Groupe de recherche sur le système nerveux central (GRSNC) Université de Montréal Montréal Canada.

Background Immune cells are key regulators of the vascular inflammatory response characteristic of hypertension. In hypertensive rodents, regulatory T lymphocytes (Treg, CD 4 CD 25) prevented vascular injury, cardiac damage, and endothelial dysfunction of mesenteric arteries. Whether Treg modulate the cerebrovascular damage induced by hypertension is unknown. Methods and Results C57 BL /6 mice were perfused with angiotensin II (Ang II ; 1000 ng/kg per minute) for 14 days and adoptive transfer of 3×10 CD 4 CD 25 T cells was performed via 2 intravenous injections. Control mice received a sham surgery and PBS . Treg prevented Ang II -induced neurovascular uncoupling ( P<0.05) and endothelial impairment ( P<0.05), evaluated by laser Doppler flowmetry in the somatosensory cortex. The neuroprotective effect of Treg was abolished when they were isolated from mice deficient in interleukin-10. Administration of interleukin-10 (60 ng/d) to hypertensive mice prevented Ang II -induced neurovascular uncoupling ( P<0.05). Treg adoptive transfer also diminished systemic inflammation induced by Ang II ( P<0.05), examined with a peripheral blood cytokine array. Mice receiving Ang II + Treg exhibited reduced numbers of Iba-1+ cells in the brain cortex ( P<0.05) and hippocampus ( P<0.001) compared with mice infused only with Ang II. Treg prevented the increase in cerebral superoxide radicals. Overall, these effects did not appear to be directly modulated by Treg accumulating in the brain parenchyma, because only a nonsignificant number of Treg were detected in brain. Instead, Treg penetrated peripheral tissues such as the kidney, inguinal lymph nodes, and the spleen. Conclusions Treg prevent impaired cerebrovascular responses in Ang II -induced hypertension. The neuroprotective effects of Treg involve the modulation of inflammation in the brain and periphery.
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http://dx.doi.org/10.1161/JAHA.118.009372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6405729PMC
January 2019

Natural Killer Cells Regulate Th17 Cells After Autologous Hematopoietic Stem Cell Transplantation for Relapsing Remitting Multiple Sclerosis.

Front Immunol 2018 7;9:834. Epub 2018 May 7.

Neuroimmunology Unit, McGill University and Montreal Neurological Institute, Montreal, QC, Canada.

In autoimmunity, the balance of different helper T (Th) cell subsets can influence the tissue damage caused by autoreactive T cells. Pro-inflammatory Th1 and Th17 T cells are implicated as mediators of several human autoimmune conditions such as multiple sclerosis (MS). Autologous hematopoietic stem cell transplantation (aHSCT) has been tested in phase 2 clinical trials for MS patients with aggressive disease. Abrogation of new clinical relapses and brain lesions can be seen after ablative aHSCT, accompanied by significant reductions in Th17, but not Th1, cell populations and activity. The cause of this selective decrease in Th17 cell responses following ablative aHSCT is not completely understood. We identified an increase in the kinetics of natural killer (NK) cell reconstitution, relative to CD4 T cells, in MS patients post-aHSCT, resulting in an increased NK cell:CD4 T cell ratio that correlated with the degree of decrease in Th17 responses. removal of NK cells from post-aHSCT peripheral blood mononuclear cells resulted in higher Th17 cell responses, indicating that NK cells can regulate Th17 activity. NK cells were also found to be cytotoxic to memory Th17 cells, and this toxicity is mediated through NKG2D-dependent necrosis. Surprisingly, NK cells induced memory T cells to secrete more IL-17A. This was preceded by an early rise in T cell expression of and mRNA, and could be blocked with neutralizing antibodies against CD58, a costimulatory receptor expressed on NK cells. Thus, NK cells provide initial co-stimulation that supports the induction of a Th17 response, followed by NKG2D-dependent cytotoxicity that limits these cells. Together these data suggest that rapid reconstitution of NK cells following aHSCT contribute to the suppression of the re-emergence of Th17 cells. This highlights the importance of NK cells in shaping the reconstituting immune system following aHSCT in MS patients.
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http://dx.doi.org/10.3389/fimmu.2018.00834DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5951114PMC
June 2019

Nucleus accumbens inflammation mediates anxiodepressive behavior and compulsive sucrose seeking elicited by saturated dietary fat.

Mol Metab 2018 04 31;10:1-13. Epub 2018 Jan 31.

Centre de Recherche du CHUM, Université de Montréal, Quebec, Canada; Montreal Diabetes Research Centre, Université de Montréal, Quebec, Canada; Department of Nutrition, Université de Montréal, Quebec, Canada. Electronic address:

Objective: The incidence of depression is significantly compounded by obesity. Obesity arising from excessive intake of high-fat food provokes anxiodepressive behavior and elicits molecular adaptations in the nucleus accumbens (NAc), a region well-implicated in the hedonic deficits associated with depression and in the control of food-motivated behavior. To determine the etiology of diet-induced depression, we studied the impact of different dietary lipids on anxiodepressive behavior and metabolic and immune outcomes and the contribution of NAc immune activity.

Methods: Adult C57Bl/6 mice were subjected to isocaloric high-fat/high-sucrose diets (HFD), enriched in either saturated or monounsaturated fat, or a control low-fat diet (LFD). Metabolic responses, anxiodepressive behavior, and plasma and NAc inflammatory markers were assessed after 12 weeks. In separate experiments, an adenoviral construct inhibiting IKKβ, an upstream component of the nuclear factor kappa-b (NFkB) pathway, was a priori injected into the NAc.

Results: Both HFDs resulted in obesity and hyperleptinemia; however, the saturated HFD uniquely triggered anxiety-like behavior, behavioral despair, hyperinsulinemia, glucose intolerance, peripheral inflammation, and multiple pro-inflammatory signs in the NAc, including reactive gliosis, increased expression of cytokines, antigen-presenting markers and NFкB transcriptional activity. Selective NAc IKKβ inhibition reversed the upregulated expression of inflammatory markers, prevented anxiodepressive behavior and blunted compulsive sucrose-seeking in mice fed the saturated HFD.

Conclusions: Metabolic inflammation and NFкB-mediated neuroinflammatory responses in the NAc contribute to the expression of anxiodepressive behavior and heightened food cravings caused by a diet high in saturated fat and sugar.
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http://dx.doi.org/10.1016/j.molmet.2018.01.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985233PMC
April 2018

Peripheral human CD4CD8 T lymphocytes exhibit a memory phenotype and enhanced responses to IL-2, IL-7 and IL-15.

Sci Rep 2017 09 14;7(1):11612. Epub 2017 Sep 14.

Department of Neurosciences, Université de Montréal and CRCHUM, Montreal, QC, H2X 0A9, Canada.

CD4CD8 T lymphocytes account for 1-2% of circulating human T lymphocytes, but their frequency is augmented in several diseases. The phenotypic and functional properties of these T lymphocytes are still ill-defined. We performed an ex vivo characterization of CD4CD8 T lymphocytes from the blood of healthy individuals. We observed that CD4CD8 T lymphocytes exhibit several characteristics associated with memory T lymphocytes including the expression of chemokine receptors (e.g. CCR7, CXCR3, CCR6) and activation markers (e.g. CD57, CD95). Moreover, we showed that a greater proportion of CD4CD8 T lymphocytes have an enhanced capacity to produce cytokines (IFNγ, TNFα, IL-2, IL-4, IL-17A) and lytic enzymes (perforin, granzyme B) compared to CD4 and/or CD8 T lymphocytes. Finally, we assessed the impact of three key cytokines in T cell biology on these cells. We observed that IL-2, IL-7 and IL-15 triggered STAT5 phosphorylation in a greater proportion of CD4CD8 T lymphocytes compared to CD4 and CD8 counterparts. We demonstrate that CD4CD8 T lymphocytes from healthy donors exhibit a phenotypic profile associated with memory T lymphocytes, an increased capacity to produce cytokines and lytic enzymes, and a higher proportion of cells responding to key cytokines implicated in T cell survival, homeostasis and activation.
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http://dx.doi.org/10.1038/s41598-017-11926-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5599513PMC
September 2017

Editorial: Lymphocytes in MS and EAE: More Than Just a CD4 World.

Front Immunol 2017 13;8:133. Epub 2017 Feb 13.

Department of Pathobiology, University of Pennsylvania , Philadelphia, PA , USA.

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http://dx.doi.org/10.3389/fimmu.2017.00133DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5303706PMC
February 2017

USP15 regulates type I interferon response and is required for pathogenesis of neuroinflammation.

Nat Immunol 2017 01 10;18(1):54-63. Epub 2016 Oct 10.

Department of Human Genetics, McGill University, Montreal, Quebec, Canada.

Genes and pathways in which inactivation dampens tissue inflammation present new opportunities for understanding the pathogenesis of common human inflammatory diseases, including inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis. We identified a mutation in the gene encoding the deubiquitination enzyme USP15 (Usp15) that protected mice against both experimental cerebral malaria (ECM) induced by Plasmodium berghei and experimental autoimmune encephalomyelitis (EAE). Combining immunophenotyping and RNA sequencing in brain (ECM) and spinal cord (EAE) revealed that Usp15-associated resistance to neuroinflammation was linked to dampened type I interferon responses in situ. In hematopoietic cells and in resident brain cells, USP15 was coexpressed with, and functionally acted together with the E3 ubiquitin ligase TRIM25 to positively regulate type I interferon responses and to promote pathogenesis during neuroinflammation. The USP15-TRIM25 dyad might be a potential target for intervention in acute or chronic states of neuroinflammation.
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http://dx.doi.org/10.1038/ni.3581DOI Listing
January 2017

ALS-linked misfolded SOD1 species have divergent impacts on mitochondria.

Acta Neuropathol Commun 2016 04 27;4(1):43. Epub 2016 Apr 27.

Centre de recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM) Université de Montréal, 900 rue Saint-Denis, Local R09.442, Montréal, QC, H2X 0A9, Canada.

Approximately 20 % of familial Amyotrophic Lateral Sclerosis (ALS) is caused by mutations in superoxide dismutase (SOD1), which leads to misfolding of the SOD1 protein, resulting in a toxic gain of function. Several conformation-restricted antibodies have been generated that specifically recognize misfolded SOD1 protein, and have been used as therapeutics in pre-clinical models. Misfolded SOD1 selectively associates with spinal cord mitochondria in SOD1 rodent models. Using the SOD1(G93A) rat model, we find that SOD1 conformational specific antibodies AMF7-63 and DSE2-3H1 labeled a fibrillar network concentrated in the anterior horn; while A5C3, B8H10, C4F6 and D3H5 labeled motor neurons as well as puncta in the neuropil. There is a time-dependent accumulation of misfolded SOD1 at the surface of spinal cord mitochondria with AMF7-63-labeled mitochondria having increased volume in contrast to a mitochondrial subset labeled with B8H10. In spinal cord homogenates and isolated mitochondria, AMF7-63, DSE2-3H1 and B8H10 detect misfolded SOD1 aggregates. SOD1 that lacks its metal cofactors has an increased affinity for naïve mitochondria and misfolded SOD1 antibodies B8H10 and DSE2-3H1 readily detect demetalated mutant and wild-type SOD1. Together, these data suggest that multiple non-native species of misfolded SOD1 may exist, some of which are associated with mitochondrial damage. Conformational antibodies are invaluable tools to identify and characterize the variation in misfolded SOD1 species with regards to biochemical characteristics and toxicity. This information is highly relevant to the further development of these reagents as therapeutics.
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http://dx.doi.org/10.1186/s40478-016-0313-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4847257PMC
April 2016

Immunological and pathological characterization of fatal rebound MS activity following natalizumab withdrawal.

Mult Scler 2017 01 11;23(1):72-81. Epub 2016 Jul 11.

Neuroimmunology Research Laboratory, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada/Multiple Sclerosis Clinic, Division of Neurology, CHUM-Notre-Dame Hospital, Montréal, QC, Canada/Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.

Background: Severe rebound multiple sclerosis (MS) activity is a life-threatening complication of natalizumab (NTZ) withdrawal, for which pathogenesis and treatment are still unclear. We report the immunological and pathological characterization of a case of central nervous system (CNS) inflammatory demyelination after NTZ discontinuation.

Objective: To understand the pathophysiology of this neuroinflammatory condition.

Methods: Antemortem blood and cerebrospinal fluid (CSF) analysis was compared with postmortem pathological studies, as well as with novel flow cytometry characterization of immune cells isolated from the CNS parenchyma.

Results: Pathological analysis of the brain revealed the presence of innumerable active inflammatory demyelinating lesions typical of immunopathological pattern II. Monocytes/macrophages and B cells were enriched in the CNS parenchyma compared to the CSF. Numerous plasma cells were present in the lesions, but CD8 T lymphocytes were predominant in the parenchyma, as opposed to CD4 in the CSF. CNS-infiltrating lymphocytes expressed high levels of adhesion molecules, granzyme B (GzB), interferon-gamma (IFN-γ), and interleukin (IL)-17.

Conclusions: Our results underline the differences in immune cell populations between the CSF and the CNS parenchyma, and suggest that aggressive immunosuppressive therapy targeting both T and B lymphocytes is warranted to control the overwhelming CNS inflammation.
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http://dx.doi.org/10.1177/1352458516641775DOI Listing
January 2017

Production of IL-27 in multiple sclerosis lesions by astrocytes and myeloid cells: Modulation of local immune responses.

Glia 2016 Apr 9;64(4):553-69. Epub 2015 Dec 9.

Department of Neurosciences, Université De Montréal and CRCHUM Montreal, Quebec, Canada, H2X 0A9.

The mechanisms whereby human glial cells modulate local immune responses are not fully understood. Interleukin-27 (IL-27), a pleiotropic cytokine, has been shown to dampen the severity of experimental autoimmune encephalomyelitis, but it is still unresolved whether IL-27 plays a role in the human disease multiple sclerosis (MS). IL-27 contribution to local modulation of immune responses in the brain of MS patients was investigated. The expression of IL-27 subunits (EBI3 and p28) and its cognate receptor IL-27R (the gp130 and TCCR chains) was elevated within post-mortem MS brain lesions compared with normal control brains. Moreover, astrocytes (GFAP(+) cells) as well as microglia and macrophages (Iba1(+) cells) were important sources of IL-27. Brain-infiltrating CD4 and CD8 T lymphocytes expressed the IL-27R specific chain (TCCR) implying that these cells could respond to local IL-27 sources. In primary cultures of human astrocytes inflammatory cytokines increased IL-27 production, whereas myeloid cell inflammatory M1 polarization and inflammatory cytokines enhanced IL-27 expression in microglia and macrophages. Astrocytes in postmortem tissues and in vitro expressed IL-27R. Moreover, IL-27 triggered the phosphorylation of the transcription regulator STAT1, but not STAT3 in human astrocytes; indeed IL-27 up-regulated MHC class I expression on astrocytes in a STAT1-dependent manner. These findings demonstrated that IL-27 and its receptor were elevated in MS lesions and that local IL-27 can modulate immune properties of astrocytes and infiltrating immune cells. Thus, therapeutic strategies targeting IL-27 may influence not only peripheral but also local inflammatory responses within the brain of MS patients.
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http://dx.doi.org/10.1002/glia.22948DOI Listing
April 2016

Multiple Sclerosis and T Lymphocytes: An Entangled Story.

J Neuroimmune Pharmacol 2015 Dec 7;10(4):528-46. Epub 2015 May 7.

Department of Neurosciences, Université de Montréal, CRCHUM Room R09.466, 900 St-Denis, Montréal, QC, Canada, H2X 0A9.

Multiple sclerosis (MS) is the prototypic inflammatory disease of the central nervous system (CNS) characterized by multifocal areas of demyelination, axonal damage, activation of glial cells, and immune cell infiltration. Despite intensive years of research, the etiology of this neurological disorder remains elusive. Nevertheless, the abundance of immune cells such as T lymphocytes and their products in CNS lesions of MS patients supports the notion that MS is an immune-mediated disorder. An important body of evidence gathered from MS animal models such as experimental autoimmune encephalomyelitis (EAE), points to the central contribution of CD4 T lymphocytes in disease pathogenesis. Both Th1 (producing interferon-γ) and Th17 (producing interleukin 17) CD4 T lymphocytes targeting CNS self-antigens have been implicated in MS and EAE pathobiology. Moreover, several publications suggest that CD8 T lymphocytes also participate in the development of MS lesions. The migration of activated T lymphocytes from the periphery into the CNS has been identified as a crucial step in the formation of MS lesions. Several factors promote such T cell extravasation including: molecules (e.g., cell adhesion molecules) implicated in the T cell-blood brain barrier interaction, and chemokines produced by neural cells. Finally, once in the CNS, T lymphocytes need to be reactivated by local antigen presenting cells prior to enter the parenchyma where they can initiate damage. Further investigations will be necessary to elucidate the impact of environmental factors (e.g., gut microbiota) and CNS intrinsic properties (e.g., microglial activation) on this inflammatory neurological disease.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5052065PMC
http://dx.doi.org/10.1007/s11481-015-9614-0DOI Listing
December 2015

Netrin 1 regulates blood-brain barrier function and neuroinflammation.

Brain 2015 Jun 22;138(Pt 6):1598-612. Epub 2015 Apr 22.

1 Neuroimmunology Unit, Department of Neuroscience, Centre de Recherche du CHUM (CRCHUM), Université de Montréal, Montréal, Québec, Canada

Blood-brain barrier function is driven by the influence of astrocyte-secreted factors. During neuroinflammatory responses the blood-brain barrier is compromised resulting in central nervous system damage and exacerbated pathology. Here, we identified endothelial netrin 1 induction as a vascular response to astrocyte-derived sonic hedgehog that promotes autocrine barrier properties during homeostasis and increases with inflammation. Netrin 1 supports blood-brain barrier integrity by upregulating endothelial junctional protein expression, while netrin 1 knockout mice display disorganized tight junction protein expression and barrier breakdown. Upon inflammatory conditions, blood-brain barrier endothelial cells significantly upregulated netrin 1 levels in vitro and in situ, which prevented junctional breach and endothelial cell activation. Finally, netrin 1 treatment during experimental autoimmune encephalomyelitis significantly reduced blood-brain barrier disruption and decreased clinical and pathological indices of disease severity. Our results demonstrate that netrin 1 is an important regulator of blood-brain barrier maintenance that protects the central nervous system against inflammatory conditions such as multiple sclerosis and experimental autoimmune encephalomyelitis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614143PMC
http://dx.doi.org/10.1093/brain/awv092DOI Listing
June 2015

Melanoma cell adhesion molecule-positive CD8 T lymphocytes mediate central nervous system inflammation.

Ann Neurol 2015 Jul 20;78(1):39-53. Epub 2015 May 20.

Neuroimmunology Research Laboratory, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada.

Objective: Although Tc17 lymphocytes are enriched in the central nervous system (CNS) of multiple sclerosis (MS) subjects and of experimental autoimmune encephalomyelitis (EAE) animals, limited information is available about their recruitment into the CNS and their role in neuroinflammation. Identification of adhesion molecules used by autoaggressive CD8(+) T lymphocytes to enter the CNS would allow further characterization of this pathogenic subset and could provide new therapeutic targets in MS. We propose that melanoma cell adhesion molecule (MCAM) is a surface marker and adhesion molecule used by pathogenic CD8(+) T lymphocytes to access the CNS.

Methods: Frequency, phenotype, and function of MCAM(+) CD8(+) T lymphocytes was characterized using a combination of ex vivo, in vitro, in situ, and in vivo approaches in humans and mice, including healthy controls, MS subjects, and EAE animals.

Results: Herein, we report that MCAM is expressed by human effector CD8(+) T lymphocytes and it is strikingly upregulated during MS relapses. We further demonstrate that MCAM(+) CD8(+) T lymphocytes express more interleukin 17, interferon γ, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor than MCAM(-) lymphocytes, and exhibit an enhanced killing capacity toward oligodendrocytes. MCAM blockade restricts the transmigration of CD8(+) T lymphocytes across human blood-brain barrier endothelial cells in vitro, and blocking or depleting MCAM in vivo reduces chronic neurological deficits in active, transfer, and spontaneous progressive EAE models.

Interpretation: Our data demonstrate that MCAM identifies encephalitogenic CD8(+) T lymphocytes, suggesting that MCAM could represent a biomarker of MS disease activity and a valid target for the treatment of neuroinflammatory conditions.
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http://dx.doi.org/10.1002/ana.24415DOI Listing
July 2015

An optimized method to process mouse CNS to simultaneously analyze neural cells and leukocytes by flow cytometry.

J Neurosci Methods 2015 May 25;247:23-31. Epub 2015 Mar 25.

Department of Neurosciences, Université de Montréal, Montreal, QC, Canada H3C 3J7; CRCHUM, Montreal, QC, Canada H2X 0A9. Electronic address:

Background: Flow cytometry is an efficient and powerful technique to characterize and quantify numerous cells. However, the strengths of this technique have not been widely harnessed in neurosciences due to the critical step of CNS tissue preparation into a single cell suspension. Previous reports assessed either neural cells or infiltrating leukocytes but simultaneous detection has not been extensively implemented. We optimized CNS tissue preparation for flow cytometry analysis.

New Method: We subjected CNS tissue from individual adult mice to different digestion protocols and Percoll™ methods. We quantified and characterized by flow cytometry neural cells (neurons, oligodendrocytes, microglia) and leukocytes (macrophages, T lymphocytes).

Results: The one step Percoll™ method significantly increased cell yield compared to the gradient Percoll™ method. The collagenase D+DNase I digestion led to the maximal cell number recovery while preserving cell marker (O4, NeuN, CD45, CD11b, CD3, CD4, CD8) integrity compared to papain, trypsin digestion, and no digestion. The combination of collagenase D+DNase I digestion and one step Percoll™ method was optimal for the recovery and analysis of cells from the CNS of naïve and experimental autoimmune encephalomyelitis (multiple sclerosis model) mice.

Comparison With Existing Method(s): Although flow cytometry does not reveal CNS localization, this technique allows concurrent quantification of multiple parameters. In contrast to other protocols, our novel method simultaneously analyzes neural and immune cells in individual mice in healthy and pathological conditions.

Conclusions: We strongly believe that the field of neurosciences will benefit from an optimal use of flow cytometry to elucidate physiological and pathological processes.
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http://dx.doi.org/10.1016/j.jneumeth.2015.03.021DOI Listing
May 2015

Immunodetection of outer membrane proteins by flow cytometry of isolated mitochondria.

J Vis Exp 2014 Sep 18(91):51887. Epub 2014 Sep 18.

Department of Neurosciences, Université de Montréal, CRCHUM;

Methods to detect and monitor mitochondrial outer membrane protein components in animal tissues are vital to study mitochondrial physiology and pathophysiology. This protocol describes a technique where mitochondria isolated from rodent tissue are immunolabeled and analyzed by flow cytometry. Mitochondria are isolated from rodent spinal cords and subjected to a rapid enrichment step so as to remove myelin, a major contaminant of mitochondrial fractions prepared from nervous tissue. Isolated mitochondria are then labeled with an antibody of choice and a fluorescently conjugated secondary antibody. Analysis by flow cytometry verifies the relative purity of mitochondrial preparations by staining with a mitochondrial specific dye, followed by detection and quantification of immunolabeled protein. This technique is rapid, quantifiable and high-throughput, allowing for the analysis of hundreds of thousands of mitochondria per sample. It is applicable to assess novel proteins at the mitochondrial surface under normal physiological conditions as well as the proteins that may become mislocalized to this organelle during pathology. Importantly, this method can be coupled to fluorescent indicator dyes to report on certain activities of mitochondrial subpopulations and is feasible for mitochondria from the central nervous system (brain and spinal cord) as well as liver.
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http://dx.doi.org/10.3791/51887DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4828110PMC
September 2014

Mitochondrial damage revealed by immunoselection for ALS-linked misfolded SOD1.

Hum Mol Genet 2013 Oct 4;22(19):3947-59. Epub 2013 Jun 4.

Mutant superoxide dismutase 1 (SOD1) selectively associates with spinal cord mitochondria in rodent models of SOD1-mediated amyotrophic lateral sclerosis. A portion of mutant SOD1 exists in a non-native/misfolded conformation that is selectively recognized by conformational antibodies. Misfolded SOD1 is common to all mutant SOD1 models, is uniquely found in areas affected by the disease and is considered to mediate toxicity. We report that misfolded SOD1 recognized by the antibody B8H10 is present in greater abundance in mitochondrial fractions of SOD1(G93A) rat spinal cords compared with oxidized SOD1, as recognized by the C4F6 antibody. Using a novel flow cytometric assay, we detect an age-dependent deposition of B8H10-reactive SOD1 on spinal cord mitochondria from both SOD1(G93A) rats and SOD1(G37R) mice. Mitochondrial damage, including increased mitochondrial volume, excess superoxide production and increased exposure of the toxic BH3 domain of Bcl-2, tracks positively with the presence of misfolded SOD1. Lastly, B8H10 reactive misfolded SOD1 is present in the lysates and mitochondrial fractions of lymphoblasts derived from ALS patients carrying SOD1 mutations, but not in controls. Together, these results highlight misfolded SOD1 as common to two ALS rodent animal models and familial ALS patient lymphoblasts with four different SOD1 mutations. Studies in the animal models point to a role for misfolded SOD1 in mitochondrial dysfunction in ALS pathogenesis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5052069PMC
http://dx.doi.org/10.1093/hmg/ddt249DOI Listing
October 2013

Diminished Th17 (not Th1) responses underlie multiple sclerosis disease abrogation after hematopoietic stem cell transplantation.

Ann Neurol 2013 Mar 5;73(3):341-54. Epub 2013 Mar 5.

Neuroimmunology Unit, Montreal Neurological Institute, McGill University, and Laboratory of Immunology, University of Montreal Hospital Research Centre, Montreal, Quebec, Canada.

Objective: To define changes in phenotype and functional responses of reconstituting T cells in patients with aggressive multiple sclerosis (MS) treated with ablative chemotherapy and autologous hematopoietic stem cell transplantation (HSCT).

Methods: Clinical and brain magnetic resonance imaging measures of disease activity were monitored serially in patients participating in the Canadian MS HSCT Study. Reconstitution kinetics of immune-cell subsets were determined by flow cytometry, whereas thymic function was assessed using T-cell receptor excision circle analyses as well as flow cytometry measurements of CD31+ recent thymic emigrants (RTEs). Functional assays were performed to track central nervous system-autoreactive antigen-specific T-cell responses, and the relative capacity to generate Th1, Th17, or Th1/17 T-cell responses.

Results: Complete abrogation of new clinical relapses and new focal inflammatory brain lesions throughout the 2 years of immune monitoring following treatment was associated with sustained decrease in naive T cells, in spite of restoration of both thymic function and release of RTEs during reconstitution. Re-emergence as well as in vivo expansion of autoreactive T cells to multiple myelin targets was evident in all patients studied. The reconstituted myelin-specific T cells exhibited the same Th1 and Th2 responses as preablation myelin-reactive T cells. In contrast, the post-therapy T-cell repertoire exhibited a significantly diminished capacity for Th17 responses.

Interpretation: Our results indicate that diminished Th17 and Th1/17 responses, rather than Th1 responses, are particularly relevant to the abrogation of new relapsing disease activity observed in this cohort of patients with aggressive MS following chemoablation and HSCT.
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http://dx.doi.org/10.1002/ana.23784DOI Listing
March 2013

Cytotoxic NKG2C+ CD4 T cells target oligodendrocytes in multiple sclerosis.

J Immunol 2013 Mar 8;190(6):2510-8. Epub 2013 Feb 8.

Department of Medicine, Research Center of the Hospital Center of the University of Montreal-Notre-Dame Hospital, Montreal, Quebec H2L 4M1, Canada;

The mechanisms whereby immune cells infiltrating the CNS in multiple sclerosis patients contribute to tissue injury remain to be defined. CD4 T cells are key players of this inflammatory response. Myelin-specific CD4 T cells expressing CD56, a surrogate marker of NK cells, were shown to be cytotoxic to human oligodendrocytes. Our aim was to identify NK-associated molecules expressed by human CD4 T cells that confer this oligodendrocyte-directed cytotoxicity. We observed that myelin-reactive CD4 T cell lines, as well as short-term PHA-activated CD4 T cells, can express NKG2C, the activating receptor interacting with HLA-E, a nonclassical MHC class I molecule. These cells coexpress CD56 and NKG2D, have elevated levels of cytotoxic molecules FasL, granzyme B, and perforin compared with their NKG2C-negative counterparts, and mediate significant in vitro cytotoxicity toward human oligodendrocytes, which upregulated HLA-E upon inflammatory cytokine treatment. A significantly elevated proportion of ex vivo peripheral blood CD4 T cells, but not CD8 T cells or NK cells, from multiple sclerosis patients express NKG2C compared with controls. In addition, immunohistochemical analyses showed that multiple sclerosis brain tissues display HLA-E(+) oligodendrocytes and NKG2C(+) CD4 T cells. Our results implicate a novel mechanism through which infiltrating CD4 T cells contribute to tissue injury in multiple sclerosis.
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http://dx.doi.org/10.4049/jimmunol.1202725DOI Listing
March 2013

Melanoma cell adhesion molecule identifies encephalitogenic T lymphocytes and promotes their recruitment to the central nervous system.

Brain 2012 Oct 13;135(Pt 10):2906-24. Epub 2012 Sep 13.

Neuroimmunology Research Laboratory, Centre of Excellence in Neuromics, Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montréal, Québec, H2L 2W5, Canada.

In multiple sclerosis, encephalitogenic CD4(+) lymphocytes require adhesion molecules to accumulate into central nervous system inflammatory lesions. Using proteomic techniques, we identified expression of melanoma cell adhesion molecule (MCAM) on a subset of human effector memory CD4(+) lymphocytes and on human blood-brain barrier endothelium. Herein, we demonstrate that MCAM is a stable surface marker that refines the identification of interleukin 17(+), interleukin 22(+), RAR-related orphan receptor γ and interleukin 23 receptor(+) cells within the CD161(+)CCR6(+) subset of memory CD4(+) lymphocytes. We also show that MCAM(+) lymphocytes express significantly more granulocyte/macrophage colony stimulating factor and granzyme B than MCAM(-) lymphocytes. Furthermore, the proportion of MCAM(+) CD4(+) lymphocytes is significantly increased in the blood and in the central nervous system of patients with multiple sclerosis and experimental autoimmune encephalomyelitis animals compared with healthy controls or other neurological diseases, and MCAM expression is upregulated at the blood-brain barrier within inflammatory lesions. Moreover, blockade of MCAM or depletion of MCAM(+) CD4(+) T lymphocytes both restrict the migration of T(H)17 lymphocytes across blood-brain barrier endothelial cells and decrease the severity of experimental autoimmune encephalomyelitis. Our findings indicate that MCAM could serve as a potential biomarker for multiple sclerosis and represents a valuable target for the treatment of neuroinflammatory conditions.
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http://dx.doi.org/10.1093/brain/aws212DOI Listing
October 2012

Stimulation of Wnt/ß-catenin pathway in human CD8+ T lymphocytes from blood and lung tumors leads to a shared young/memory phenotype.

PLoS One 2012 30;7(7):e41074. Epub 2012 Jul 30.

Research Centre, Centre Hospitalier de l'Université de Montréal, Université de Montréal and Institut du Cancer de Montréal, Hôpital Notre-Dame, Montréal, Québec, Canada.

Cancer can be treated by adoptive cell transfer (ACT) of T lymphocytes. However, how to optimally raise human T cells to a differentiation state allowing the best persistence in ACT is a challenge. It is possible to differentiate mouse CD8(+) T cells towards stem cell-like memory (T(SCM)) phenotype upon TCR stimulation with Wnt/ß-catenin pathway activation. Here, we evaluated if T(SCM) can be obtained from human mature CD8(+) T cells following TCR and Wnt/ß-catenin activation through treatment with the chemical agent 4,6-disubstituted pyrrolopyrimidine (TWS119), which inhibits the glycogen synthase kinase-3β (GSK-3β), key inhibitor of the Wnt pathway. Human CD8(+) T cells isolated from peripheral blood or tumor-infiltrating lymphocytes (TIL), and treated with TWS119 gave rise to CD62L(+)CD45RA(+) cells, indicative of early differentiated stage, also expressing CD127 which is normally found on memory cells, and CD133, an hematopoietic stem cell marker. T(SCM) cells raised from either TIL or blood secreted numerous inflammatory mediators, but in lower amounts than those measured without TWS119. Finally, generated T(SCM) CD8(+) T cells expressed elevated Bcl-2 and no detectable caspase-3 activity, suggesting increased persistence. Our data support a role for Wnt/ß-catenin pathway in promoting the T(SCM) subset in human CD8(+) T cells from TIL and the periphery, which are relevant for ACT.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0041074PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408435PMC
April 2013

Journal club: Intrathecal effects of daclizumab treatment of multiple sclerosis.

Neurology 2012 May;78(22):e131-3

Department of Medicine, University of Toronto, Toronto, Canada.

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http://dx.doi.org/10.1212/WNL.0b013e31825830e3DOI Listing
May 2012

Lipocalin 2 is a novel immune mediator of experimental autoimmune encephalomyelitis pathogenesis and is modulated in multiple sclerosis.

Glia 2012 Jul 12;60(7):1145-59. Epub 2012 Apr 12.

Center for Research in Neuroscience, The Research Institute of The McGill University Health Center, Montreal, Quebec, Canada.

Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model of multiple sclerosis (MS), an inflammatory, demyelinating disease of the central nervous system (CNS). EAE pathogenesis involves various cell types, cytokines, chemokines, and adhesion molecules. Given the complexity of the inflammatory response in EAE, it is likely that many immune mediators still remain to be discovered. To identify novel immune mediators of EAE pathogenesis, we performed an Affymetrix gene array screen on the spinal cords of mice at the onset stage of disease. This screening identified the gene encoding lipocalin 2 (Lcn2) as being significantly upregulated. Lcn2 is a multi-functional protein that plays a role in glial activation, matrix metalloproteinase (MMP) stabilization, and cellular iron flux. As many of these processes have been implicated in EAE, we characterized the expression and role of Lcn2 in this disease in C57BL/6 mice. We show that Lcn2 is significantly upregulated in the spinal cord throughout EAE and is expressed predominantly by monocytes and reactive astrocytes. The Lcn2 receptor, 24p3R, is also expressed on monocytes, macrophages/microglia, and astrocytes in EAE. In addition, we show that EAE severity is increased in Lcn2(-/-) mice as compared with wild-type controls. Finally, we demonstrate that elevated levels of Lcn2 are detected in the plasma and cerebrospinal fluid (CSF) in MS and in immune cells in CNS lesions in MS tissue sections. These data indicate that Lcn2 is a modulator of EAE pathogenesis and suggest that it may also play a role in MS.
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http://dx.doi.org/10.1002/glia.22342DOI Listing
July 2012