Publications by authors named "Lesley A Ward"

13 Publications

  • Page 1 of 1

Early-life programming of mesenteric lymph node stromal cell identity by the lymphotoxin pathway regulates adult mucosal immunity.

Sci Immunol 2019 12;4(42)

Department of Immunology, University of Toronto, Toronto, Ontario, Canada.

Redundant mechanisms support immunoglobulin A (IgA) responses to intestinal antigens. These include multiple priming sites [mesenteric lymph nodes (MLNs), Peyer's patches, and isolated lymphoid follicles] and various cytokines that promote class switch to IgA, even in the absence of T cells. Despite these backup mechanisms, vaccination against enteric pathogens such as rotavirus has limited success in some populations. Genetic and environmental signals experienced during early life are known to influence mucosal immunity, yet the mechanisms for how these exposures operate remain unclear. Here, we used rotavirus infection to follow antigen-specific IgA responses through time and in different gut compartments. Using genetic and pharmacological approaches, we tested the role of the lymphotoxin (LT) pathway-known to support IgA responses-at different developmental stages. We found that LT-β receptor (LTβR) signaling in early life programs intestinal IgA responses in adulthood by affecting antibody class switch recombination to IgA and subsequent generation of IgA antibody-secreting cells within an intact MLN. In addition, early-life LTβR signaling dictates the phenotype and function of MLN stromal cells to support IgA responses in the adult. Collectively, our studies uncover new mechanistic insights into how early-life LTβR signaling affects mucosal immune responses during adulthood.
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http://dx.doi.org/10.1126/sciimmunol.aax1027DOI Listing
December 2019

Siponimod therapy implicates Th17 cells in a preclinical model of subpial cortical injury.

JCI Insight 2020 01 16;5(1). Epub 2020 Jan 16.

Department of Immunology, University of Toronto, Toronto, Ontario, Canada.

Subpial demyelination is a specific hallmark of multiple sclerosis and a correlate of disease progression. Although the mechanism(s) that mediate pathogenesis in the subpial compartment remain unclear, it has been speculated that inflammation in the overlying meninges may be associated with subpial injury. Here we show that adoptive transfer of proteolipid protein-primed Th17 cells into SJL/J recipient mice induces subpial demyelination associated with microglial/macrophage activation, disruption of the glial limitans, and evidence of an oxidative stress response. This pathology was topologically associated with foci of immune cells in the meninges and occurred in the absence of measurable anti-myelin oligodendrocyte glycoprotein IgM or IgG antibodies. To test the role of brain-infiltrating leukocytes on subpial injury, we modulated sphingosine 1-phosphate (S1P) receptor1,5 activity with BAF312 (siponimod) treatment. Administration of BAF312, even after adoptively transferred T cells had entered the brain, significantly ameliorated clinical experimental autoimmune encephalomyelitis and diminished subpial pathology, concomitant with a selective reduction in the capacity of transferred T cells to make Th17 cytokines. We conclude that sustained subpial cortical injury is associated with the capacity for brain-resident T cells to produce Th17 cytokines, and this pathological process occurs in an S1P receptor1,5-dependent manner.
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http://dx.doi.org/10.1172/jci.insight.132522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7030818PMC
January 2020

Recirculating Intestinal IgA-Producing Cells Regulate Neuroinflammation via IL-10.

Cell 2019 01 3;176(3):610-624.e18. Epub 2019 Jan 3.

Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address:

Plasma cells (PC) are found in the CNS of multiple sclerosis (MS) patients, yet their source and role in MS remains unclear. We find that some PC in the CNS of mice with experimental autoimmune encephalomyelitis (EAE) originate in the gut and produce immunoglobulin A (IgA). Moreover, we show that IgA PC are dramatically reduced in the gut during EAE, and likewise, a reduction in IgA-bound fecal bacteria is seen in MS patients during disease relapse. Removal of plasmablast (PB) plus PC resulted in exacerbated EAE that was normalized by the introduction of gut-derived IgA PC. Furthermore, mice with an over-abundance of IgA PB and/or PC were specifically resistant to the effector stage of EAE, and expression of interleukin (IL)-10 by PB plus PC was necessary and sufficient to confer resistance. Our data show that IgA PB and/or PC mobilized from the gut play an unexpected role in suppressing neuroinflammation.
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http://dx.doi.org/10.1016/j.cell.2018.11.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6903689PMC
January 2019

Isotype-Switched Autoantibodies Are Necessary To Facilitate Central Nervous System Autoimmune Disease in and Mice.

J Immunol 2018 08 6;201(4):1119-1130. Epub 2018 Jul 6.

Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada;

B cell-depleting therapies have been shown to ameliorate symptoms in multiple sclerosis (MS) patients; however, the mechanism of action remains unclear. Following priming with Ag, B cells undergo secondary diversification of their BCR, including BCR class-switch recombination (CSR) and somatic hypermutation (SHM), with both processes requiring the enzyme activation-induced (cytidine) deaminase. We previously reported that activation-induced (cytidine) deaminase is required for full clinical manifestation of disease in an animal model of MS (experimental autoimmune encephalomyelitis; EAE) provoked by immunization with the extracellular domain of recombinant human myelin oligodendrocyte glycoprotein (hMOG). In this study, we investigated the role of CSR versus SHM in the pathogenesis of EAE. We found that passive transfer of class-switched anti-MOG IgG1 Abs into hMOG-primed mice is sufficient to fully rescue EAE disease. In addition, we found that the nature of the Ag is an important determinant of EAE severity in mice because the lack of a diversified BCR does not affect the induction of EAE when immunized with the extracellular domain of rat MOG. To discriminate the effect of either CSR or SHM, we induced EAE in uracil DNA glycosylase-deficient mice () that exhibit a defect primarily in CSR. We observed that mice exhibit milder clinical disease compared with control mice, concomitant with a reduced amount of anti-MOG IgG class-switched Abs that preserved normal affinity. Collectively, these results indicate that CSR plays an important role in governing the incidence and severity of EAE induced with hMOG but not rat MOG.
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http://dx.doi.org/10.4049/jimmunol.1700729DOI Listing
August 2018

Integration of Th17- and Lymphotoxin-Derived Signals Initiates Meningeal-Resident Stromal Cell Remodeling to Propagate Neuroinflammation.

Immunity 2015 Dec;43(6):1160-73

Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address:

Tertiary lymphoid tissues (TLTs) have been observed in the meninges of multiple sclerosis (MS) patients, but the stromal cells and molecular signals that support TLTs remain unclear. Here, we show that T helper 17 (Th17) cells induced robust TLTs within the brain meninges that were associated with local demyelination during experimental autoimmune encephalitis (EAE). Th17-cell-induced TLTs were underpinned by a network of stromal cells producing extracellular matrix proteins and chemokines, enabling leukocytes to reside within, rather than simply transit through, the meninges. Within the CNS, interactions between lymphotoxin αβ (LTαβ) on Th17 cells and LTβR on meningeal radio-resistant cells were necessary for the propagation of de novo interleukin-17 responses, and activated T cells from MS patients expressed elevated levels of LTβR ligands. Therefore, input from both Th17 cells and the lymphotoxin pathway induce the formation of an immune-competent stromal cell niche in the meninges.
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http://dx.doi.org/10.1016/j.immuni.2015.11.010DOI Listing
December 2015

A Lymphotoxin/Type I IFN Axis Programs CD8+ T Cells To Infiltrate a Self-Tissue and Propagate Immunopathology.

J Immunol 2015 Nov 12;195(10):4650-9. Epub 2015 Oct 12.

Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada;

Type I IFNs (IFN-I) are cytokines that can mediate both immune suppression and activation. Dendritic cells (DC) are significant producers of IFN-I, and depending on the context (nature of Ag, duration of exposure to Ag), DC-derived IFN-I can have varying effects on CD8(+) T cell responses. In this study, we report that in the context of a CD8(+) T cell response to a self-Ag, DC-intrinsic expression of IFN regulatory factor 3 is required to induce optimal proliferation and migration of autoreactive CD8(+) T cells, ultimately determining their ability to infiltrate a target tissue (pancreas), and the development of glucose intolerance in rat insulin promoter-glycoprotein (RIP-GP) mice. Moreover, we show that signals through the lymphotoxin-β receptor (LTβR) in DC are also required for the proliferation of autoreactive CD8(+) T cells, the upregulation of VLA4/LFA1 on activated CD8(+) T cells, and their subsequent infiltration into the pancreas both in vitro and in vivo. Importantly, the defects in autoreactive CD8(+) T cell proliferation, accumulation of CD8(+) T cells in the pancreas, and consequent glucose intolerance observed in the context of priming by LTβR(-/-) DC could be rescued by exogenous addition of IFN-I. Collectively, our data demonstrate that the LTβR/IFN-I axis is essential for programming of CD8(+) T cells to mediate immunopathology in a self-tissue. A further understanding of the IFN-I/LTβR axis will provide valuable therapeutic insights for treatment of CD8(+) T cell-mediated autoimmune diseases.
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http://dx.doi.org/10.4049/jimmunol.1501053DOI Listing
November 2015

A TNF-α-CCL20-CCR6 axis regulates Nod1-induced B cell responses.

J Immunol 2014 Mar 17;192(6):2787-99. Epub 2014 Feb 17.

Department of Microbiology and Immunology, McGill University, Complex Traits Group, Montreal, Quebec H3G 0B1, Canada;

Innate immune responses provoke the accumulation of leukocytes at sites of inflammation. In addition to monocytes and granulocytes, B cells also participate in antimicrobial innate immune responses; however, the mechanisms for accumulation of B cells to sites of inflammation are not well understood. To study B cell accumulation following systemic inflammation, we used a model synthetic ligand that stimulates a specific pattern recognition molecule, nucleotide-binding oligomerization domain-containing protein 1 (Nod1). Upon exposure to Nod1 agonists, both B cells and neutrophils rapidly accumulate within the spleen, and dendritic cells migrate into the periarterial lymphoid sheath. Nod1 stimulation led to a marked increase in several chemokines within the spleen, including CXCL13, CCL2, and CCL20. Whereas the lymphotoxin pathway was critical for the induction of the B cell chemoattractant CXCL13 in response to Nod1 agonists, B cell accumulation within the spleen following Nod1-induced systemic inflammation was independent of the lymphotoxin pathway. In contrast, a CCR6/CCL20 chemokine loop instructed rapid increase of B cells in the spleen in response to systemic administration of Nod1 agonists in a TNF-α-dependent manner. Moreover, CCR6 was required to regulate Nod1-mediated B cell responses. These results reveal a novel mechanism of B cells during inflammation and shed light on how B cells participate in innate immune responses to microbial stimulation.
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http://dx.doi.org/10.4049/jimmunol.1203310DOI Listing
March 2014

BAI3, CDX2 and VIL1: a panel of three antibodies to distinguish small cell from large cell neuroendocrine lung carcinomas.

Histopathology 2014 Mar 25;64(4):547-56. Epub 2013 Nov 25.

Department of Pathology, Dow International Medical College, Karachi, Pakistan; Department of Pathology, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK; Divisions of Reproduction and Metabolic and Vascular Health, Warwick Medical School, Coventry, UK.

Aims: Discriminating small-cell lung carcinoma (SCLC) from large-cell neuroendocrine carcinoma (LCNEC) rests on morphological criteria, and reproducibility has been shown to be poor. We aimed to identify immunohistochemical markers to assist this diagnosis.

Methods And Results: Gene expression profiling on laser captured frozen tumour samples from eight SCLC and eight LCNEC tumours identified a total of 888 differentially expressed genes (DEGs), 23 of which were validated by qRT-PCR. Antibodies to four selected gene products were then evaluated as immunohistochemical markers on a cohort of 173 formalin-fixed paraffin-embedded (FFPE) SCLC/LCNEC tumour samples, including 26 indeterminate tumours without a consensus diagnosis. Three markers, CDX2, VIL1 and BAI3, gave significantly different results in the two tumour types (P < 0.0001): CDX2 and VIL1 in combination (either marker positive) showed sensitivity and specificity of 81% for LCNEC while BAI3 showed 89% sensitivity and 75% specificity for SCLC. Of the 26 indeterminate tumours 15 (58%) showed an immunophenotype suggesting either SCLC or LCNEC, eight (31%) showed staining of both tumour types, and three (11%) were negative for all markers.

Conclusion: A panel of three markers, BAI3, CDX2 and VIL1, is a useful adjunct in the diagnosis of these tumour types.
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http://dx.doi.org/10.1111/his.12278DOI Listing
March 2014

AID-expressing germinal center B cells cluster normally within lymph node follicles in the absence of FDC-M1+ CD35+ follicular dendritic cells but dissipate prematurely.

J Immunol 2013 Nov 25;191(9):4521-30. Epub 2013 Sep 25.

Department of Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.

Upon activation with T-dependent Ag, B cells enter germinal centers (GC) and upregulate activation-induced deaminase (AID). AID(+) GC B cells then undergo class-switch recombination and somatic hypermutation. Follicular dendritic cells (FDC) are stromal cells that underpin GC and require constitutive signaling through the lymphotoxin (LT) β receptor to be maintained in a fully mature, differentiated state. Although it was shown that FDC can be dispensable for the generation of affinity-matured Ab, in the absence of FDC it is unclear where AID expression occurs. In a mouse model that lacks mature FDC, as well as other LT-sensitive cells, we show that clusters of AID(+)PNA(+)GL7(+) Ag-specific GC B cells form within the B cell follicles of draining lymph nodes, suggesting that FDC are not strictly required for GC formation. However, later in the primary response, FDC-less GC dissipated prematurely, correlating with impaired affinity maturation. We examined whether GC dissipation was due to a lack of FDC or other LTβ receptor-dependent accessory cells and found that, in response to nonreplicating protein Ag, FDC proved to be more critical for long-term GC maintenance. Our study provides a spatial-temporal analysis of Ag-specific B cell activation and AID expression in the context of a peripheral lymph node that lacks FDC-M1(+) CD35(+) FDC and other LT-sensitive cell types, and reveals that FDC are not strictly required for the induction of AID within an organized GC-like environment.
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http://dx.doi.org/10.4049/jimmunol.1300769DOI Listing
November 2013

Substrain differences reveal novel disease-modifying gene candidates that alter the clinical course of a rodent model of multiple sclerosis.

J Immunol 2010 Mar 19;184(6):3174-85. Epub 2010 Feb 19.

Department of Immunology, University of Toronto, Toronto, Ontario, Canada.

Experimental autoimmune encephalomyelitis (EAE) is a rodent model of multiple sclerosis that is executed in animals by immunization with myelin Ag in adjuvant. The SJL/J autoimmune-prone strain of mouse has been used to model relapsing-remitting multiple sclerosis. However, significant variations in peak scores, timing of onset, and incidence are observed among laboratories, with the postacute (relapse) phase of the disease exhibiting significant inconsistency. We characterized two substrains of SJL/J mice that exhibit profoundly different EAE disease parameters. Induction of EAE in the first SJL/J substrain resulted in many cases of chronic EAE that was dominated by an aggressive B cell response to the immunizing Ag and to endogenous CNS Ags. In contrast, the other SJL/J substrain exhibited a relapsing-remitting form of EAE concomitant with an elevated number of cytokine-producing CD4(+) T cells in the CNS. Exploiting these interstrain differences, we performed a genome-wide copy number analysis on the two disparate SJL/J substrains and discovered numerous gene-dosage differences. In particular, one inflammation-associated gene, Naip1, was present at a higher copy number in the SJL/J substrain that exhibited relapsing-remitting EAE. These results demonstrate that substrain differences, perhaps at the level of genomic copy number, can account for variability in the postacute phase of EAE and may drive chronic versus relapsing disease.
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http://dx.doi.org/10.4049/jimmunol.0902881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160975PMC
March 2010

Differential requirement of MALT1 for BAFF-induced outcomes in B cell subsets.

J Exp Med 2009 Nov 16;206(12):2671-83. Epub 2009 Nov 16.

Department of Immunology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada.

B cell activation factor of the TNF family (BAFF) activates noncanonical nuclear factor kappaB (NF-kappaB) heterodimers that promote B cell survival. We show that although MALT1 is largely dispensable for canonical NF-kappaB signaling downstream of the B cell receptor, the absence of MALT1 results in impaired BAFF-induced phosphorylation of NF-kappaB2 (p100), p100 degradation, and RelB nuclear translocation in B220(+) B cells. This corresponds with impaired survival of MALT1(-/-) marginal zone (MZ) but not follicular B cells in response to BAFF stimulation in vitro. MALT1(-/-) MZ B cells also express higher amounts of TRAF3, a known negative regulator of BAFF receptor-mediated signaling, and TRAF3 was found to interact with MALT1. Furthermore, phenotypes associated with overexpression of BAFF, including increased MZ B cell numbers, elevated serum immunoglobulin titers, and spontaneous germinal center formation, were found to be dependent on B cell-intrinsic MALT1 expression. Our results demonstrate a novel role for MALT1 in biological outcomes induced by BAFF-mediated signal transduction.
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http://dx.doi.org/10.1084/jem.20091802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2806610PMC
November 2009

Expression of lymphotoxin-alphabeta on antigen-specific T cells is required for DC function.

J Exp Med 2007 May 23;204(5):1071-81. Epub 2007 Apr 23.

Department of Immunology, University of Toronto, Toronto, Ontario, Canada.

During an immune response, activated antigen (Ag)-specific T cells condition dendritic cells (DCs) to enhance DC function and survival within the inflamed draining lymph node (LN). It has been difficult to ascertain the role of the tumor necrosis factor (TNF) superfamily member lymphotoxin-alphabeta (LTalphabeta) in this process because signaling through the LTbeta-receptor (LTbetaR) controls multiple aspects of lymphoid tissue organization. To resolve this, we have used an in vivo system where the expression of TNF family ligands is manipulated only on the Ag-specific T cells that interact with and condition Ag-bearing DCs. We report that LTalphabeta is a critical participant required for optimal DC function, independent of its described role in maintaining lymphoid tissue organization. In the absence of LTalphabeta or CD40L on Ag-specific T cells, DC dysfunction could be rescued in vivo via CD40 or LTbetaR stimulation, respectively, suggesting that these two pathways cooperate for optimal DC conditioning.
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http://dx.doi.org/10.1084/jem.20061968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2118582PMC
May 2007