[Show abstract][Hide abstract] ABSTRACT: Acyl-CoA:cholesterol acyltransferase 1 (Acat1) converts cellular cholesterol to cholesteryl esters and is considered as a drug target for treating atherosclerosis. However,
in mouse models for atherosclerosis, global Acat1 knockout (Acat1-/-) did not prevent lesion development; Acat1-/- increased apoptosis within lesion, and led to several additional undesirable phenotypes including hair loss, dry eye, leukocytosis,
xanthomatosis, and reduced life span. To determine the roles of Acat1 in monocytes/macrophages in atherosclerosis, we produced myeloid- specific Acat1 knockout (Acat1-M/-M) mouse, and showed that in the Apoe knockout (Apoe-/-) mouse model for atherosclerosis, Acat1-M/-M decreased plaque area and reduced lesion size, without causing leukocytosis, dry eye, hair loss, or reduced life span.
Acat1-M/-M enhanced xanthomatosis in apoe-/-mice, a skin disease that is not associated with diet-induced atherosclerosis in humans. Analyses of atherosclerotic lesions
showed that Acat1-M/-M reduced macrophage number, diminished cholesterol and cholesteryl ester load, without causing detectable apoptotic cell death.
Leukocyte migration analysis in vivo showed that Acat1-/M/-M caused much less leukocytes to appear at the activated endothelium. Studies in inflammatory (Ly6Chi positive) monocytes and in cultured macrophages showed that inhibiting ACAT1 by gene knockout or by pharmacological inhibition caused significant decrease in integrin beta 1 (CD29) expression in activated
monocytes/macrophages. The sparse presence of lesion macrophages without Acat1 can thus in part be attributed to decreased
interaction between inflammatory monocytes/macrophages lacking Acat1 and the activated endothelium. We conclude that targeting ACAT1 in myeloid cell lineage suppresses atherosclerosis progression
while avoiding many of the undesirable side effects caused by global Acat1 inhibition.
Full-text · Article · Jan 2016 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: Clear cell meningioma (CCM) is an uncommon variant of meningioma. The authors describe a case of a pediatric CCM localized to the lumbar spine. After resection, sequencing revealed an inactivating mutation in the SWI/SNF chromatin remodeling complex subunit SMARCE1, with loss of the second allele in the tumor. The authors present a literature review of this mutation that is associated with CCM and a family history of spine tumors.
No preview · Article · Jun 2015 · Journal of Neurosurgery Pediatrics
[Show abstract][Hide abstract] ABSTRACT: Multiple sclerosis (MS) is a debilitating autoimmune neuroinflammatory disease influenced by genetics and the environment. MS incidence in female subjects has approximately tripled in the last century, suggesting a sex-specific environmental influence. Recent animal and human studies have implicated dietary sodium as a risk factor in MS, whereby high sodium augmented the generation of T helper (Th) 17 cells and exacerbated experimental autoimmune encephalomyelitis (EAE), the principal model of MS. However, whether dietary sodium interacts with sex or genetics remains unknown. Here, we show that high dietary sodium exacerbates EAE in a strain- and sex-specific fashion. In C57BL6/J mice, exposure to a high-salt diet exacerbated disease in both sexes, while in SJL/JCrHsd mice, it did so only in females. In further support of a genetic component, we found that sodium failed to modify EAE course in C57BL6/J mice carrying a 129/Sv-derived interval on chromosome 17. Furthermore, we found that the high-sodium diet did not augment Th17 or Th1 responses, but it did result in increased blood-brain barrier permeability and brain pathology. Our results demonstrate that the effects of dietary sodium on autoimmune neuroinflammation are sex specific, genetically controlled, and CNS mediated.-Krementsov, D. N., Case, L. K., Hickey, W. F., Teuscher, C. Exacerbation of autoimmune neuroinflammation by dietary sodium is genetically controlled and sex specific.
No preview · Article · Apr 2015 · The FASEB Journal
[Show abstract][Hide abstract] ABSTRACT: The immunological response during the first 24 hours after traumatic brain injury (TBI) may be a critical therapeutic interval for limiting the secondary neuronal damage that is influenced by enhanced inflammatory mediator expression.
To gain further insight of the early injury response, we examined the expression of several inflammatory genes by real-time qPCR as a function of time or distance from injury in two distinct mammalian models: an ex vivo mouse cortical slice injury system and an in vivo piglet model of brain injury.
Interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), chemokine ligands 2 (CCL2), 3 (CCL3), 4 (CCL4), and prostaglandin-endoperoxide synthase 2 (PTGS2) mRNAs increased within 5 h after injury in mouse cortical slices. Chemokine and PTGS2 mRNAs remained elevated in slices at 24 h, whereas IL-1β and TNF-α expressions decreased from earlier peak levels. At 24 h after cortical injury in 1-month-old piglets, the expression of CCL2 mRNA was significantly increased in the lesion core and in the penumbra region. The expression of PTGS2, IL-1β, and TNF-α was variable among the piglets.
These in vitro and large animal models of cortical injury expand our understanding of the early timing and spread of the immunological response and can serve as preclinical systems to facilitate the discovery of therapeutic agents for TBI aimed at regulating inflammatory mediator expression.
Full-text · Article · Apr 2015 · Journal of Neuroinflammation
[Show abstract][Hide abstract] ABSTRACT: We recently reported SMARCE1 mutations as a cause of spinal clear cell meningiomas. Here, we have identified five further cases with non-NF2 spinal meningiomas and six with non-NF2 cranial meningiomas. Three of the spinal cases and three of the cranial cases were clear cell tumours. We screened them for SMARCE1 mutations, and investigated copy number changes in all point mutation negative samples. We identified two novel mutations in individuals with spinal clear cell meningiomas and three mutations in individuals with cranial clear cell meningiomas. Copy number analysis identified a large deletion of the 5’ end of SMARCE1 in two unrelated probands with spinal clear cell meningiomas. Testing of affected and unaffected relatives of one of these individuals identified the same deletion in two affected female siblings and their unaffected father, providing further evidence of incomplete penetrance of meningioma disease in males. In addition, we found loss of SMARCE1 protein in three of 10 paraffin embedded cranial clear cell meningiomas. Together, these results demonstrate that loss of SMARCE1 is relevant to cranial as well as spinal meningiomas.Our study broadens the spectrum of mutations in the SMARCE1 gene and expands the phenotype to include cranial clear cell meningiomas.
Full-text · Article · Dec 2014 · The Journal of Pathology
[Show abstract][Hide abstract] ABSTRACT: Limiting excessive production of inflammatory mediators is an effective therapeutic strategy for many diseases. It's also a promising remedy for neurodegenerative diseases and central nervous system (CNS) injuries. Glucocorticoids are valuable anti-inflammatory agents, but their use is constrained by adverse side-effects. Activators of NF-E2-related factor-2 (Nrf2) signaling represent an attractive anti-inflammatory alternative. In this study, dexamethasone, a synthetic glucocorticoid, and several molecular activators of Nrf2 were evaluated for efficacy in slices of cerebral cortex derived from adult SJL/J mice. Cortical explants increased expression of IL-1β and TNF-α mRNAs in culture within 5 h of sectioning. This expression was inhibited with dexamethasone in the explant medium or injected systemically in mice before sectioning. Semi-synthetic triterpenoid (SST) derivatives, potent activators of the Nrf2 pathway, demonstrated fast-acting anti-inflammatory activity in microglia cultures, but not in the cortical slice system. Quercetin, luteolin, and dimethyl fumarate were also evaluated as molecular activators of Nrf2. While expression of inflammatory mediators in microglia cultures was inhibited, these compounds did not demonstrate anti-inflammatory efficacy in cortical slices. In conclusion, brain slices were amenable to pharmacological modification as demonstrated by anti-inflammatory activity with dexamethasone. The utilization of Nrf2 activators to limit inflammatory mediators within the CNS requires further investigation. Inactivity in CNS tissue, however, suggests their safe use without neurological side-effects in treating non-CNS disorders. Short-term CNS explants may provide a more accurate model of in vivo conditions than microglia cultures since the complex tissue microenvironment is maintained.
No preview · Article · Mar 2012 · Journal of Neuroimmune Pharmacology
[Show abstract][Hide abstract] ABSTRACT: While it is clear that inbred strains of mice have variations in immunological responsiveness, the influence of genetic background following tissue damage in the central nervous system is not fully understood. A cortical explant system was employed as a model for injury to determine whether the immediate transcriptional response to tissue resection revealed differences among three mouse strains.
Immunological mRNAs were measured in cerebral cortex from SJL/J, C57BL/6J, and BALB/cJ mice using real time RT-PCR. Freshly isolated cortical tissue and cortical sections incubated in explant medium were examined. Levels of mRNA, normalized to β-actin, were compared using one way analysis of variance with pooled samples from each mouse strain.
In freshly isolated cerebral cortex, transcript levels of many pro-inflammatory mediators were not significantly different among the strains or too low for comparison. Constitutive, baseline amounts of CD74 and antisecretory factor (ASF) mRNAs, however, were higher in SJL/J and C57BL/6J, respectively. When sections of cortical tissue were incubated in explant medium, increased message for a number of pro-inflammatory cytokines and chemokines occurred within five hours. Message for chemokines, IL-1α, and COX-2 transcripts were higher in C57BL/6J cortical explants relative to SJL/J and BALB/cJ. IL-1β, IL-12/23 p40, and TNF-α were lower in BALB/cJ explants relative to SJL/J and C57BL/6J. Similar to observations in freshly isolated cortex, CD74 mRNA remained higher in SJL/J explants. The ASF mRNA in SJL/J explants, however, was now lower than levels in both C57BL/6J and BALB/cJ explants.
The short-term cortical explant model employed in this study provides a basic approach to evaluate an early transcriptional response to neurological damage, and can identify expression differences in genes that are influenced by genetic background.
Full-text · Article · Sep 2011 · Journal of Neuroinflammation
[Show abstract][Hide abstract] ABSTRACT: GBM (glioblastoma multiforme) is a highly aggressive brain tumour with very poor prognosis despite multi-modalities of treatment. Furthermore, recent failure of targeted therapy for these tumours highlights the need of appropriate rodent models for preclinical studies. In this review, we highlight the most commonly used rodent models (U251, U86, GL261, C6, 9L and CNS-1) with a focus on the pathological and genetic similarities to the human disease. We end with a comprehensive review of the CNS-1 rodent model.
[Show abstract][Hide abstract] ABSTRACT: 2-Cyano-3,12-dioxoolean-1, 9-dien-28-oic acid (CDDO) is a semisynthetic triterpenoid. CDDO derivatives with an amide, butyl ester (BE), imidazolide (IM), or trifluoroethyl amide (TFEA) group at position C-28 of CDDO were evaluated in glial and neuronal cells, in vitro. Changes in intracellular NADPH:quinone oxidoreductase (NQO1) levels, protection against oxidative toxicity, endotoxin-induced free-radical production, and the median lethal concentration (LC50) were assessed. All four CDDO derivatives at nanomolar concentrations increased NQO1 levels in astrocytes and moderately in neurons, but not in microglial cells. Pretreatment with 100 nM of CDDO-amide, CDDO-TFEA, or CDDO-IM protected astrocytes from hydrogen peroxide toxicity. Only CDDO-amide protected neuronal cells. Pretreatment of microglial cells with CDDO derivatives at nanomolar concentrations attenuated endotoxin-induced nitric oxide protection. The effectiveness for NQO1 induction, protection against oxidative toxicity, and attenuation of nitric oxide production, as well as cell viability at higher concentrations, varied among the derivatives with different functional groups at C-28. CDDO-amide had comparable or even a greater effectiveness at altering cytoprotective and immunomodulatory properties while having higher LC50 values for each neural cell type examined. These results indicate that derivatives of CDDO modulate important pathways relevant to many neurological diseases that involve both chronic inflammation and free-radical damage with variable effects based on the functional group at C-28 and cell type.
No preview · Article · Mar 2011 · Journal of Neuroimmune Pharmacology
[Show abstract][Hide abstract] ABSTRACT: Decreased immune surveillance is thought to be one of the mechanisms by which neoplastic cells are able to thrive. When cancer
is located in the nervous system, an immune privileged site, its ability to evade detection, and targeting by immune cells
may contribute to its aggressive behavior. Furthermore, high-grade gliomas, the most frequent and lethal primary brain tumors,
induce both a local and systemic state of immune suppression that hampers efforts to manipulate the immune system as an effective
therapeutic modality. On the other hand, there are rare instances when the immune response elucidated against systemic cancer
causes nervous system injury without direct spread of the tumor. Although the neural injury is thought to be mediated by an
autoimmune process, in most cases it is uncertain if it is caused by a humoral response, a cellular response, or a combination
of both. This chapter reviews concepts related to the unique relationship between the nervous and immune systems, when cancer
is present, as well as immune therapeutic modalities employed when the neural structures are affected directly by a primary
tumor or indirectly in the case of paraneoplastic neurologic syndromes. The distinct immunologic characteristics of the central
nervous system (CNS) become more unique and complex in the setting of neoplastic disease. In 2008, approximately 1,437,180
new cancer cases, including 21,810 arising from the nervous system, were diagnosed in the USA . Gliomas, the most frequent
type of brain tumors, are characterized by the infiltration of normal cerebral tissue, but this rarely results in systemic
metastases. The tumor microenvironment shows a meager inflammatory response often accompanied by systemic immune suppression.
These alterations might be considered epiphenomena unrelated to tumor pathogenesis, but experimental and clinical observations
suggest that the immune system plays an important role in glioma biology. Our current concept of glioma immunobiology lends
strong support to the idea of manipulating the immune system as a therapeutic approach for primary brain tumors. Glioma immunotherapy
has evolved over the years, unfortunately as yet, without a major success. Nevertheless, extraneural or systemic neoplasms
can trigger an immune response that in rare instances have repercussions in the nervous system. These interactions indirectly
cause clinical syndromes that are aptly termed paraneoplastic neurologic syndromes. In some cases, antibodies have been identified
as the element responsible for the phenomenon, but as primary tumors of the brain and spinal cord, the role that the immune
system plays in the pathogenesis of these syndromes has not been clearly elucidated.
KeywordsGliomas-Immunology-Nervous system-Paraneoplastic syndromes
[Show abstract][Hide abstract] ABSTRACT: Theiler's murine encephalomyelitis virus-induced demyelination (TMEVD) and experimental allergic encephalomyelitis (EAE) are the principal animal models of multiple sclerosis (MS). Previously, we provided evidence that Tmevd2 and Eae3 may represent either a shared susceptibility locus or members of a gene complex controlling susceptibility to central nervous system inflammatory demyelinating disease. To explore the genetic relationship between Tmevd2 and Eae3, we generated a D2.C-Tmevd2 interval-specific congenic (ISC) line and three overlapping interval-specific recombinant congenic (ISRC) lines in which the Tmevd2-resistant allele from BALB/cByJ was introgressed onto the TMEVD-susceptible DBA/2J background. These mice, all H2(d), were studied for susceptibility to EAE elicited by immunization with proteolipid protein peptide 180-199. Compared with DBA/2J mice, D2.C-Tmevd2 mice developed a significantly less severe clinical disease course and EAE pathology in the spinal cord, confirming the existence of Eae3 and its linkage to Tmevd2 in this strain combination. Compared with DBA/2J and D2.C-Tmevd2, all three ISRC lines exhibited clinical disease courses of intermediate severity. Neither differences in ex vivo antigen-specific cytokine nor proliferative responses uniquely cosegregated with differences in disease severity. These results indicate that multiple quantitative trait loci (QTLs) within the Tmevd2/Eae3 interval influence EAE severity, one of which includes a homology region for a QTL found in MS by admixture mapping.
Full-text · Article · Dec 2010 · Genes and immunity
[Show abstract][Hide abstract] ABSTRACT: Cholesterol metabolism has been implicated in the pathogenesis of several neurodegenerative diseases, including the abnormal accumulation of amyloid-beta, one of the pathological hallmarks of Alzheimer disease (AD). Acyl-CoA:cholesterol acyltransferases (ACAT1 and ACAT2) are two enzymes that convert free cholesterol to cholesteryl esters. ACAT inhibitors have recently emerged as promising drug candidates for AD therapy. However, how ACAT inhibitors act in the brain has so far remained unclear. Here we show that ACAT1 is the major functional isoenzyme in the mouse brain. ACAT1 gene ablation (A1-) in triple transgenic (i.e., 3XTg-AD) mice leads to more than 60% reduction in full-length human APPswe as well as its proteolytic fragments, and ameliorates cognitive deficits. At 4 months of age, A1- causes a 32% content increase in 24-hydroxycholesterol (24SOH), the major oxysterol in the brain. It also causes a 65% protein content decrease in HMG-CoA reductase (HMGR) and a 28% decrease in sterol synthesis rate in AD mouse brains. In hippocampal neurons, A1- causes an increase in the 24SOH synthesis rate; treating hippocampal neuronal cells with 24SOH causes rapid declines in hAPP and in HMGR protein levels. A model is provided to explain our findings: in neurons, A1- causes increases in cholesterol and 24SOH contents in the endoplasmic reticulum, which cause reductions in hAPP and HMGR protein contents and lead to amelioration of amyloid pathology. Our study supports the potential of ACAT1 as a therapeutic target for treating certain forms of AD.
Full-text · Article · Feb 2010 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: The role of neuroinflammation in motor neuron death of amyotrophic lateral sclerosis (ALS) is unclear. The human mutant superoxide dismutase-1 (hmSOD1)-expressing murine transgenic model of ALS has provided some insight into changes in microglia activity during disease progression. The purpose of this study was to gain further knowledge by characterizing the immunological changes during disease progression in the spinal cord and peripheral nerve using the more recently developed hmSOD1 rat transgenic model of ALS.
Using immunohistochemistry, the extent and intensity of tissue CD11b expression in spinal cord, lumbar nerve roots, and sciatic nerve were evaluated in hmSOD1 rats that were pre-clinical, at clinical onset, and near disease end-stage. Changes in CD11b expression were compared to the detection of MHC class II and CD68 microglial activation markers in the ventral horn of the spinal cord, as well as to the changes in astrocytic GFAP expression.
Our study reveals an accumulation of microglia/macrophages both in the spinal cord and peripheral nerve prior to clinical onset based on CD11b tissue expression. The microglia formed focal aggregates in the ventral horn and became more widespread as the disease progressed. Hypertrophic astrocytes were not prominent in the ventral horn until after clinical onset, and the enhancement of GFAP did not have a strong correlation to increased CD11b expression. Detection of MHC class II and CD68 expression was found in the ventral horn only after clinical onset. The macrophages in the ventral nerve root and sciatic nerve of hmSOD1 rats were observed encircling axons.
These findings describe for the first time in the hmSOD1 rat transgenic model of ALS that enhancement of microglia/macrophage activity occurs pre-clinically both in the peripheral nerve and in the spinal cord. CD11b expression is shown to be a superior indicator for early immunological changes compared to other microglia activation markers and astrogliosis. Furthermore, we suggest that the early activity of microglia/macrophages is involved in the early phase of motor neuron degeneration and propose that studies involving immunomodulation in hmSOD1transgenic models need to consider effects on macrophages in peripheral nerves as well as to microglia in the spinal cord.
Full-text · Article · Jan 2010 · Journal of Neuroinflammation
[Show abstract][Hide abstract] ABSTRACT: Genes controlling immunopathologic diseases of differing etiopathology may also influence susceptibility to autoimmune disease. B10.D1-H2(q)/SgJ mice with a 2538 G-->A missense mutation in the tyrosine kinase-2 gene (Tyk2) are susceptible to Toxoplasma gondii yet resistant to autoimmune arthritis, unlike the wild-type B10.Q/Ai substrain. To understand whether Tyk2 is also important in a second autoimmune model, experimental allergic encephalomyelitis (EAE) was induced in B10.D1-H2(q)/SgJ (Tyk2(A)) and B10.Q/Ai (Tyk2(G)) mice with the myelin oligodendrocyte glycoprotein peptide 79-96. B10.D1-H2(q)/SgJ mice were resistant to EAE whereas B10.Q/Ai mice were susceptible, and a single copy of the Tyk2(G) allele conferred EAE susceptibility in F(1) hybrids. Furthermore, EAE resistance in B10.D1-H2(q)/SgJ mice was overridden when pertussis toxin (PTX) was used to mimic the effects of environmental factors derived from infectious agents. Numerous cytokines and chemokines were increased when PTX was included in the immunization protocol. However, only RANTES, IL-6, and IFN-gamma increased significantly with both genetic compensation and PTX treatment. These data indicate that Tyk2 is a shared autoimmune disease susceptibility gene whose genetic contribution to disease susceptibility can be modified by environmental factors. Single nucleotide polymorphisms like the one that distinguishes Tyk2 alleles are of considerable significance given the potential role of gene-by-environment interactions in autoimmune disease susceptibility.
Full-text · Article · Jun 2009 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Worldwide, approximately two billion people are chronically infected with Toxoplasma gondii with largely unknown consequences.
To better understand long-term effects and pathogenesis of this common, persistent brain infection, mice were infected at a time in human years equivalent to early to mid adulthood and studied 5-12 months later. Appearance, behavior, neurologic function and brain MRIs were studied. Additional analyses of pathogenesis included: correlation of brain weight and neurologic findings; histopathology focusing on brain regions; full genome microarrays; immunohistochemistry characterizing inflammatory cells; determination of presence of tachyzoites and bradyzoites; electron microscopy; and study of markers of inflammation in serum. Histopathology in genetically resistant mice and cytokine and NRAMP knockout mice, effects of inoculation of isolated parasites, and treatment with sulfadiazine or alphaPD1 ligand were studied.
Twelve months after infection, a time equivalent to middle to early elderly ages, mice had behavioral and neurological deficits, and brain MRIs showed mild to moderate ventricular dilatation. Lower brain weight correlated with greater magnitude of neurologic abnormalities and inflammation. Full genome microarrays of brains reflected inflammation causing neuronal damage (Gfap), effects on host cell protein processing (ubiquitin ligase), synapse remodeling (Complement 1q), and also increased expression of PD-1L (a ligand that allows persistent LCMV brain infection) and CD 36 (a fatty acid translocase and oxidized LDL receptor that mediates innate immune response to beta amyloid which is associated with pro-inflammation in Alzheimer's disease). Immunostaining detected no inflammation around intra-neuronal cysts, practically no free tachyzoites, and only rare bradyzoites. Nonetheless, there were perivascular, leptomeningeal inflammatory cells, particularly contiguous to the aqueduct of Sylvius and hippocampus, CD4+ and CD8+ T cells, and activated microglia in perivascular areas and brain parenchyma. Genetically resistant, chronically infected mice had substantially less inflammation.
In outbred mice, chronic, adult acquired T. gondii infection causes neurologic and behavioral abnormalities secondary to inflammation and loss of brain parenchyma. Perivascular inflammation is prominent particularly contiguous to the aqueduct of Sylvius and hippocampus. Even resistant mice have perivascular inflammation. This mouse model of chronic T. gondii infection raises questions of whether persistence of this parasite in brain can cause inflammation or neurodegeneration in genetically susceptible hosts.
Full-text · Article · Nov 2008 · Journal of Neuroinflammation
[Show abstract][Hide abstract] ABSTRACT: Balance and Agility of an uninfected mouse and a chronically infected mouse. Mouse number 20 is uninfected while mouse number 5 is chronically infected with T. gondii.