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Abstract
The link between systemic autoimmunity, brain pathology, and aberrant behavior is still a largely unexplored field of biomedical science. Accumulating evidence points to causal relationships between immune factors, neurodegeneration, and neuropsychiatric manifestations. By documenting autoimmunity-associated neuronal degeneration and cytotoxicity of the cerebrospinal fluid from disease-affected subjects, the murine MRL model had shown high validity in revealing principal pathogenic circuits. In addition, unlike any other autoimmune strain, MRL mice produce antibodies commonly found in patients suffering from lupus and other autoimmune disorders. This review highlights importance of the MRL model as a useful preparation in understanding the links between immune system and brain function.
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Affiliation(s)
- Boris Šakić
- Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, ON, Canada.
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Sakić B. The MRL model: an invaluable tool in studies of autoimmunity-brain interactions. Methods Mol Biol 2012; 934:277-99. [PMID: 22933151 DOI: 10.1007/978-1-62703-071-7_14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The link between systemic autoimmunity, brain pathology, and aberrant behavior is still largely unexplored field of biomedical science. Accumulating evidence points to causal relationships between immune factors, neurodegeneration, and neuropsychiatric manifestations. By documenting autoimmunity-associated neuronal degeneration and cytotoxicity of the cerebrospinal fluid from disease-affected subjects, the murine MRL model had shown high validity in revealing principal pathogenic circuits. In addition, unlike any other autoimmune strain, MRL mice produce antibodies commonly found in patients suffering from lupus and other autoimmune disorders. This review highlights importance of the MRL model as an indispensible preparation in understanding the links between immune system and brain function.
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Affiliation(s)
- Boris Sakić
- Department of Psychiatry and Behavioral Neurosciences, McMaster University, Hamilton, ON, Canada.
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3
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Ballok DA. Neuroimmunopathology in a murine model of neuropsychiatric lupus. ACTA ACUST UNITED AC 2006; 54:67-79. [PMID: 17223198 PMCID: PMC2577581 DOI: 10.1016/j.brainresrev.2006.12.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2006] [Revised: 12/09/2006] [Accepted: 12/11/2006] [Indexed: 01/18/2023]
Abstract
Animal models are extremely useful tools in defining pathogenesis and treatment of human disease. For many years researchers believed that structural damage to the brain of neuropsychiatric (NP) patients lead to abnormal mental function, but this possibility was not extensively explored until recently. Imaging studies of NP-systemic lupus erythematosus (SLE) support the notion that brain cell death accounts for the emergence of neurologic and psychiatric symptoms, and evidence suggests that it is an autoimmunity-induced brain disorder characterized by profound metabolic alterations and progressive neuronal loss. While there are a number of murine models of SLE, this article reviews recent literature on the immunological connections to neurodegeneration and behavioral dysfunction in the Fas-deficient MRL model of NP-SLE. Probable links between spontaneous peripheral immune activation, the subsequent central autoimmune/inflammatory responses in MRL/MpJ-Tnfrsf6(lpr) (MRL-lpr) mice and the sequential mode of events leading to Fas-independent neurodegenerative autoimmune-induced encephalitis will be reviewed. The role of hormones, alternative mechanisms of cell death, the impact of central dopaminergic degeneration on behavior, and germinal layer lesions on developmental/regenerative capacity of MRL-lpr brains will also be explored. This model can provide direction for future therapeutic interventions in patients with this complex neuroimmunological syndrome.
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Affiliation(s)
- David A Ballok
- Department of Psychiatry and Behavioral Neurosciences, HSC Rm 4N4, McMaster University, 1200 Main St. West, Hamilton, Ontario, Canada L8N 3Z5.
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Sakic B, Maric I, Koeberle PD, Millward JM, Szechtman H, Maric D, Denburg JA. Increased TUNEL staining in brains of autoimmune Fas-deficient mice. J Neuroimmunol 2000; 104:147-54. [PMID: 10713354 DOI: 10.1016/s0165-5728(99)00277-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Profound changes in brain morphology and behavior coincide with the spontaneous development of systemic autoimmune/inflammatory disease in Fas-deficient MRL-lpr mice. The dendrites atrophy, the density of hippocampal and cortical neurons decreases, and an anxious/depressive-like behavior emerges while lymphoid cells infiltrate into the choroid plexus of MRL-lpr mice. We hypothesized that the inherited lack of the Fas-dependent anti-inflammatory mechanism would lead to unsuppressed immune activity, characterized by reduced apoptosis in the MRL-lpr brain. Using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeled (TUNEL) method as an indicator of apoptosis, a surprisingly high incidence of TUNEL-positive cells was observed in the hippocampus, choroid plexus and periventricular regions of MRL-lpr mice, 5-10-fold higher than that found in the MRL +/+ control brain. Immunostaining with anti-CD3, CD4 and CD8 monoclonal antibodies showed limited overlap between CD-positive and TUNEL-positive cells, suggesting that the dying cells are for the most part (approximately 70%) not T-lymphocytes. Although further characterization of the phenotype of the dying cells and the mechanism of cell death are required, the present results suggest the involvement of a Fas-independent apoptotic process in neurodegeneration induced by systemic autoimmune disease.
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Affiliation(s)
- B Sakic
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, HSC 4N77A, 1200 Main Street, Hamilton, Ontario, Canada.
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Brey RL, Sakic B, Szechtman H, Denburg JA. Animal models for nervous system disease in systemic lupus erythematosus. Ann N Y Acad Sci 1997; 823:97-106. [PMID: 9292036 DOI: 10.1111/j.1749-6632.1997.tb48382.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Animal models have much to teach us about nervous system dysfunction in SLE. It should be stressed that the murine strains described in this review have variable expression in the onset and severity of clinical and serological features, perhaps making them more like a heterogeneous human population with SLE. With this in mind, studies involving animal models like those involving human subjects should use a sample size that ensures adequate power. It is not surprising that studies that use sample sizes as low as four to five animals per group would find discrepant results, especially in outcomes that are measured prior to the terminal phases of the disease. Similar to human SLE patients, murine models have systemic autoimmune as well as neurological manifestations. Studies with murine models must continue to consider some type of SLE disease activity measures in order to control for the effects of systemic disease on nervous system dysfunction. Because of the short time window between the earliest evidence of neurologic dysfunction and severe autoimmune disease manifestations, especially in MRL/lpr mice, the disease acceleration model may allow a more careful dissection of how immunological events are related to nervous system dysfunction. Alternatively, the study of MRL/lpr mice ultraearly (e.g., 3 weeks of age) could also provide invaluable information about the first events leading to nervous system dysfunction in SLE. Both approaches promise to identify predictors of specific nervous system manifestations that may suggest novel and more specific therapeutic interventions.
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Affiliation(s)
- R L Brey
- Department of Medicine, University of Texas Health Science Center at San Antonio 78284-7883, USA.
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6
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Abstract
Inbred MRL, NZB and BXSB strains of mice spontaneously develop a systemic, lupus-like autoimmune disease. The progress of autoimmunity is accompanied with a cascade of behavioral changes, most consistently observed in tasks reflective of emotional reactivity and the two-way avoidance learning task. Given the possibility that behavioral alterations may reflect a detrimental consequence of autoimmune-inflammatory processes and/or an adaptive response to chronic malaise, they are tentatively labeled as autoimmunity-associated behavioral syndrome (AABS). It is hypothesized that neuroactive immune factors (pro-inflammatory cytokines, brain-reactive antibodies) together with endocrine mediators (corticotropin-releasing factor, glucocorticoids) participate in the etiology of AABS. Since AABS develops natively, and has a considerable face and predictive validity, and since the principal pathway to autoimmunity is known, AABS may be a useful model for the study of CNS involvement in human autoimmune diseases and by extension, for testing autoimmune hypotheses of several mental disorders (major depression, schizophrenia, Alzheimer's disease, autism and AIDS-related dementia).
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Affiliation(s)
- B Sakić
- Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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Farrell M, Sakić B, Szechtman H, Denburg JA. Effect of cyclophosphamide on leukocytic infiltration in the brain of MRL/lpr mice. Lupus 1997; 6:268-74. [PMID: 9104735 DOI: 10.1177/096120339700600310] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neuropsychiatric manifestations are a poorly understood and potentially life-threatening complication of systemic lupus erythematosus (SLE). MRL/lpr mice spontaneously develop a lupus-like syndrome which is similar to the human disease in many respects, including behavioural abnormalities. Our previous findings indicated that the age at which infiltration of immune cells into the choroid plexus is first observed coincides with the appearance of behavioural dysfunction in MRL/lpr mice. This present study quantified leukocyte infiltration in relation to prolonged administration of cyclophosphamide (CY), a treatment effective in preventing some behavioural deficits. Compared to MRL +/+ controls, saline-treated MRL/lpr mice had significantly more CD45-positive cells (leukocytes) and CD45R-positive (B) cells in the choroid plexus and in the brain parenchyma. A six week course of CY (100 mg/kg i.p.) significantly reduced the infiltration of CD45, but not of CD45R-positive cells into the choroid plexus of the MRL/lpr substrain. In addition, the presence of leukocytes correlated positively with measures on one behavioural test (floating in the forced swim test) but not on another test (novel object test). These findings suggest that CY treatment has a differential effect on the infiltration of leukocyte subtypes and strengthen the hypothesis that some abnormal behaviour in MRL/lpr mice may be related to the presence of immunocompetent cells in the brain.
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Affiliation(s)
- M Farrell
- Department of Medicine, McMaster University, Hamilton, ON
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Moore PM, Joshi I, Ghanekar SA. Affinity isolation of neuron-reactive antibodies in MRL/lpr mice. J Neurosci Res 1994; 39:140-7. [PMID: 7837284 DOI: 10.1002/jnr.490390204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Autoantibodies from the MRL/lpr mice react with numerous proteins on neuronal cell surfaces. The purpose of this study was to isolate and characterize a population of autoantibodies reactive preferentially or exclusively with nervous system tissue. Using a purified plasma membrane preparation from brain cortex of balb/c mice coupled to diaminopropylamine agarose gel, we affinity-isolated antineuronal antibodies from pooled MRL/lpr immunoglobulins. The isolated immunoglobulins reacted with brain cortex plasma membranes and neuroblastoma cells (but not liver, kidney, or fibroblasts) by Western blot and indirect immunofluorescence with confocal microscopy. By Western blot, the epitopes in the brain cortex were proteins of apparent molecular weights 101, 63, 53, 43, 39, and 33, kd; the epitopes in the neuroblastoma cells were 63, 57, and 53 kd. Lectin column isolation revealed that the 101 and 63 kd epitopes were glycosylated. Indirect immunofluorescence revealed that the antibodies bound to the cell soma more intensely than to the cell processes of viable cultured neuroblastoma cells. The cell surface localization of this binding was confirmed by confocal microscopy. Within the central nervous system the antibodies bound more intensely to primary cultures of isolated neurons from fetal cortex than to hippocampal or neostriatal cells. With these antibodies we can begin studies of their potential pathogenic effects.
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Affiliation(s)
- P M Moore
- Department of Neurology, Wayne State University, Detroit, Michigan
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Rubin SA, Waltrip RW, Bautista JR, Carbone KM. Borna disease virus in mice: host-specific differences in disease expression. J Virol 1993; 67:548-52. [PMID: 8416380 PMCID: PMC237392 DOI: 10.1128/jvi.67.1.548-552.1993] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We developed a mouse model of Borna disease to facilitate immunopathogenesis research by adaptation of Borna disease virus to mice through serial passage in mouse brain tissue. Borna disease virus replication, antibody production, inflammation, and Borna disease expression in several different strains of mice were examined.
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Affiliation(s)
- S A Rubin
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Vogelweid CM, Johnson GC, Besch-Williford CL, Basler J, Walker SE. Inflammatory central nervous system disease in lupus-prone MRL/lpr mice: comparative histologic and immunohistochemical findings. J Neuroimmunol 1991; 35:89-99. [PMID: 1955574 DOI: 10.1016/0165-5728(91)90164-3] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The brains of pathogen-free autoimmune MRL/lpr, NZBWF1 and NZB mice were examined for central nervous system (CNS) inflammation in premoribund 8-week-old animals and at ages when active systemic lupus erythematosus (SLE) was present. CNS inflammation was observed only in MRL/lpr mice. Immunohistochemical studies of brains from young MRL/lpr mice found that infiltrates were composed primarily of CD4+ cells. Older MRL/lpr mice (22 and 26 weeks of age) had CD4+ cells predominantly, but CD8+ and B220+ cells were also present. Perivascular leakage of IgG was a prominent and unexpected finding in the MRL/lpr model. Congenic MRL/+ mice with late-onset autoimmunity had no inflammatory cells in brain tissue, and there was no perivascular staining with IgG or albumin. Our findings suggest that MRL/lpr mice are a useful model for studies of lupus-associated CNS inflammatory disease, and perivascular leakage may be a primary mechanism for entry of IgG into the brain.
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Affiliation(s)
- C M Vogelweid
- Department of Pathology, College of Veterinary Medicine, University of Missouri, Columbia 65212
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