Anatomy and Neuroscience - Research Publications

Permanent URI for this collection

Search Results

Now showing 1 - 7 of 7
  • Item
    Thumbnail Image
    Common and Low Frequency Variants in MERTK Are Independently Associated with Multiple Sclerosis Susceptibility with Discordant Association Dependent upon HLA-DRB1*15:01 Status
    Binder, MD ; Fox, AD ; Merlo, D ; Johnson, LJ ; Giuffrida, L ; Calvert, SE ; Akkermann, R ; Ma, GZM ; Perera, AA ; Gresle, MM ; Laverick, L ; Foo, G ; Fabis-Pedrini, MJ ; Spelman, T ; Jordan, MA ; Baxter, AG ; Foote, S ; Butzkueven, H ; Kilpatrick, TJ ; Field, J ; Gibson, G (PUBLIC LIBRARY SCIENCE, 2016-03)
    Multiple Sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. The risk of developing MS is strongly influenced by genetic predisposition, and over 100 loci have been established as associated with susceptibility. However, the biologically relevant variants underlying disease risk have not been defined for the vast majority of these loci, limiting the power of these genetic studies to define new avenues of research for the development of MS therapeutics. It is therefore crucial that candidate MS susceptibility loci are carefully investigated to identify the biological mechanism linking genetic polymorphism at a given gene to the increased chance of developing MS. MERTK has been established as an MS susceptibility gene and is part of a family of receptor tyrosine kinases known to be involved in the pathogenesis of demyelinating disease. In this study we have refined the association of MERTK with MS risk to independent signals from both common and low frequency variants. One of the associated variants was also found to be linked with increased expression of MERTK in monocytes and higher expression of MERTK was associated with either increased or decreased risk of developing MS, dependent upon HLA-DRB1*15:01 status. This discordant association potentially extended beyond MS susceptibility to alterations in disease course in established MS. This study provides clear evidence that distinct polymorphisms within MERTK are associated with MS susceptibility, one of which has the potential to alter MERTK transcription, which in turn can alter both susceptibility and disease course in MS patients.
  • Item
    Thumbnail Image
    Axonally derived matrilin-2 induces proinflammatory responses that exacerbate autoimmune neuroinflammation
    Jonas, A ; Thiem, S ; Kuhlmann, T ; Wagener, R ; Aszodi, A ; Nowell, C ; Hagemeier, M ; Laverick, L ; Perreau, V ; Jokubaitis, V ; Emery, B ; Kilpatrick, T ; Butzkueven, H ; Gresle, M (AMER SOC CLINICAL INVESTIGATION INC, 2014-11)
    In patients with multiple sclerosis (MS) and mice with experimental autoimmune encephalomyelitis (EAE), inflammatory axonal injury is a major determinant of disability; however, the drivers of this injury are incompletely understood. Here, we used the EAE model and determined that the extracellular matrix protein matrilin-2 (MATN2) is an endogenous neuronal molecule that is regulated in association with inflammatory axonal injury. Compared with WT mice, mice harboring a deletion of Matn2 exhibited reduced disease severity and axon damage following induction of EAE. Evaluation of neuron-macrophage cocultures revealed that exogenous MATN2 specifically signals through TLR4 and directly induces expression of proinflammatory genes in macrophages, promoting axonal damage. Moreover, the MATN2-induced proinflammatory response was attenuated greatly in macrophages from Myd88 KO mice. Examination of brain sections from patients with MS revealed that MATN2 is expressed in lesions but not in normal-appearing white matter. Together, our results indicate that MATN2 is a deleterious endogenous neuroaxonal injury response signal that activates innate immune cells and could contribute to early axonal damage in CNS inflammatory diseases like MS.
  • Item
    Thumbnail Image
    The MS Risk Allele of CD40 Is Associated with Reduced Cell-Membrane Bound Expression in Antigen Presenting Cells: Implications for Gene Function
    Field, J ; Shahijanian, F ; Schibeci, S ; Johnson, L ; Gresle, M ; Laverick, L ; Parnell, G ; Stewart, G ; McKay, F ; Kilpatrick, T ; Butzkueven, H ; Booth, D ; Haziot, A (PUBLIC LIBRARY SCIENCE, 2015-06-11)
    Human genetic and animal studies have implicated the costimulatory molecule CD40 in the development of multiple sclerosis (MS). We investigated the cell specific gene and protein expression variation controlled by the CD40 genetic variant(s) associated with MS, i.e. the T-allele at rs1883832. Previously we had shown that the risk allele is expressed at a lower level in whole blood, especially in people with MS. Here, we have defined the immune cell subsets responsible for genotype and disease effects on CD40 expression at the mRNA and protein level. In cell subsets in which CD40 is most highly expressed, B lymphocytes and dendritic cells, the MS-associated risk variant is associated with reduced CD40 cell-surface protein expression. In monocytes and dendritic cells, the risk allele additionally reduces the ratio of expression of full-length versus truncated CD40 mRNA, the latter encoding secreted CD40. We additionally show that MS patients, regardless of genotype, express significantly lower levels of CD40 cell-surface protein compared to unaffected controls in B lymphocytes. Thus, both genotype-dependent and independent down-regulation of cell-surface CD40 is a feature of MS. Lower expression of a co-stimulator of T cell activation, CD40, is therefore associated with increased MS risk despite the same CD40 variant being associated with reduced risk of other inflammatory autoimmune diseases. Our results highlight the complexity and likely individuality of autoimmune pathogenesis, and could be consistent with antiviral and/or immunoregulatory functions of CD40 playing an important role in protection from MS.
  • Item
    Thumbnail Image
    Ceruloplasmin gene-deficient mice with experimental autoimmune encephalomyelitis show attenuated early disease evolution
    Gresle, MM ; Schulz, K ; Jonas, A ; Perreau, VM ; Cipriani, T ; Baxter, AG ; Miranda-Hernandez, S ; Field, J ; Jokubaitis, VG ; Cherny, R ; Volitakis, I ; David, S ; Kilpatrick, TJ ; Butzkueven, H (WILEY, 2014-06)
    We conducted a microarray study to identify genes that are differentially regulated in the spinal cords of mice with the inflammatory disease experimental autoimmune encephalomyelitis (EAE) relative to healthy mice. In total 181 genes with at least a two-fold increase in expression were identified, and most of these genes were associated with immune function. Unexpectedly, ceruloplasmin (Cp), a ferroxidase that converts toxic ferrous iron to its nontoxic ferric form and also promotes the efflux of iron from astrocytes in the CNS, was shown to be highly upregulated (13.2-fold increase) in EAE spinal cord. Expression of Cp protein is known to be increased in several neurological conditions, but the role of Cp regulation in CNS autoimmune disease is not known. To investigate this, we induced EAE in Cp gene knockout, heterozygous, and wild-type mice. Cp knockout mice were found to have slower disease evolution than wild-type mice (EAE days 13-17; P = 0.05). Interestingly, Cp knockout mice also exhibited a significant increase in the number of astrocytes with reactive morphology in early EAE compared with wild-type mice at the same stage of disease. CNS iron levels were not increased with EAE in these mice. Based on these observations, we propose that an increase in Cp expression could contribute to tissue damage in early EAE. In addition, endogenous CP either directly or indirectly inhibits astrocyte reactivity during early disease, which could also worsen early disease evolution.
  • Item
    Thumbnail Image
    Association of plasma levels of Protein S with disease severity in multiple sclerosis
    Gresle, ; Laverick, ; Butzkueven, ; Field, ; Kilpatrick, (Sage Publications, 2015)
    The TAM family of receptor tyrosine kinases (TYRO3, AXL and MERTK) play important roles in modulating innate immune responses and central demyelination. The TAM receptor ligand Protein S (PROS) has also been shown to modulate innate immune cell responses.We assessed whether plasma levels of PROS are changed in multiple sclerosis (MS) patients and whether changes are associated with disease severity.Plasma levels of total and free PROS were measured using enzyme-linked immunosorbent assay in a discovery cohort (MS: 65, control: 14) and an independent replication cohort (MS: 29, control: 29). The Multiple Sclerosis Severity Score (MSSS) was used to evaluate associations between plasma PROS levels and disease severity.We found plasma levels of total, but not free PROS, were decreased in MS patients compared with controls. In female MS patients, we observed decreases in total and free PROS levels compared with controls. In addition, we also observed higher MSSS in patients with very low levels of plasma free PROS.These data suggest PROS may represent a potential marker of disease severity in MS.
  • Item
    Thumbnail Image
    A rare P2X7 variant Arg307Gln with absent pore formation function protects against neuroinflammation in multiple sclerosis
    Gu, BJ ; Field, J ; Dutertre, S ; Ou, A ; Kilpatrick, TJ ; Lechner-Scott, J ; Scott, R ; Lea, R ; Taylor, BV ; Stankovich, J ; Butzkueven, H ; Gresle, M ; Laws, SM ; Petrou, S ; Hoffjan, S ; Akkad, DA ; Graham, CA ; Hawkins, S ; Glaser, A ; Bedri, SK ; Hillert, J ; Matute, C ; Antiguedad, A ; Wiley, JS (OXFORD UNIV PRESS, 2015-10-01)
    Multiple sclerosis (MS) is a chronic relapsing-remitting inflammatory disease of the central nervous system characterized by oligodendrocyte damage, demyelination and neuronal death. Genetic association studies have shown a 2-fold or greater prevalence of the HLA-DRB1*1501 allele in the MS population compared with normal Caucasians. In discovery cohorts of Australasian patients with MS (total 2941 patients and 3008 controls), we examined the associations of 12 functional polymorphisms of P2X7, a microglial/macrophage receptor with proinflammatory effects when activated by extracellular adenosine triphosphate (ATP). In discovery cohorts, rs28360457, coding for Arg307Gln was associated with MS and combined analysis showed a 2-fold lower minor allele frequency compared with controls (1.11% for MS and 2.15% for controls, P = 0.0000071). Replication analysis of four independent European MS case-control cohorts (total 2140 cases and 2634 controls) confirmed this association [odds ratio (OR) = 0.69, P = 0.026]. A meta-analysis of all Australasian and European cohorts indicated that Arg307Gln confers a 1.8-fold protective effect on MS risk (OR = 0.57, P = 0.0000024). Fresh human monocytes heterozygous for Arg307Gln have >85% loss of 'pore' function of the P2X7 receptor measured by ATP-induced ethidium uptake. Analysis shows Arg307Gln always occurred with 270His suggesting a single 307Gln-270His haplotype that confers dominant negative effects on P2X7 function and protection against MS. Modeling based on the homologous zP2X4 receptor showed Arg307 is located in a region rich in basic residues located only 12 Å from the ligand binding site. Our data show the protective effect against MS of a rare genetic variant of P2RX7 with heterozygotes showing near absent proinflammatory 'pore' function.
  • Item
    Thumbnail Image
    EphA4 Receptor Tyrosine Kinase Is a Modulator of Onset and Disease Severity of Experimental Autoimmune Encephalomyelitis (EAE)
    Munro, KM ; Dixon, KJ ; Gresle, MM ; Jonas, A ; Kemper, D ; Doherty, W ; Fabri, LJ ; Owczarek, CM ; Pearse, M ; Boyd, AW ; Kilpatrick, TJ ; Butzkueven, H ; Turnley, AM ; Fujinami, RS (PUBLIC LIBRARY SCIENCE, 2013-02-04)
    The EphA4 receptor tyrosine kinase is a major regulator of axonal growth and astrocyte reactivity and is a possible inflammatory mediator. Given that multiple sclerosis (MS) is primarily an inflammatory demyelinating disease and in mouse models of MS, such as experimental autoimmune encephalomyelitis (EAE), axonal degeneration and reactive gliosis are prominent clinical features, we hypothesised that endogenous EphA4 could play a role in modulating EAE. EAE was induced in EphA4 knockout and wildtype mice using MOG peptide immunisation and clinical severity and histological features of the disease were then compared in lumbar spinal cord sections. EphA4 knockout mice exhibited a markedly less severe clinical course than wildtype mice, with a lower maximum disease grade and a slightly later onset of clinical symptoms. Numbers of infiltrating T cells and macrophages, the number and size of the lesions, and the extent of astrocytic gliosis were similar in both genotypes; however, EphA4 knockout mice appeared to have decreased axonal pathology. Blocking of EphA4 in wildtype mice by administration of soluble EphA4 (EphA4-Fc) as a decoy receptor following induction of EAE produced a delay in onset of clinical symptoms; however, most mice had clinical symptoms of similar severity by 22 days, indicating that EphA4 blocking treatment slowed early EAE disease evolution. Again there were no apparent differences in histopathology. To determine whether the role of EphA4 in modulating EAE was CNS mediated or due to an altered immune response, MOG primed T cells from wildtype and EphA4 knockout mice were passively transferred into naive recipient mice and both were shown to induce disease of equivalent severity. These results are consistent with a non-inflammatory, CNS specific, deleterious effect of EphA4 during neuroinflammation that results in axonal pathology.