Medicine and Health Sciences Commons^™

Acute Neuroinflammation Induces Ais Structural Plasticity In A Nox2-Dependent Manner, S. D. Benusa, N. M. George, B. A. Sword, G. H. Devries, J. L. Dupree

Anatomy and Neurobiology Publications

Background

Chronic microglia-mediated inflammation and oxidative stress are well-characterized underlying factors in neurodegenerative disease, whereby reactive inflammatory microglia enhance ROS production and impact neuronal integrity. Recently, it has been shown that during chronic inflammation, neuronal integrity is compromised through targeted disruption of the axon initial segment (AIS), the axonal domain critical for action potential initiation. AIS disruption was associated with contact by reactive inflammatory microglia which wrap around the AIS, increasing association with disease progression. While it is clear that chronic microglial inflammation and enhanced ROS production impact neuronal integrity, little is known about how acute microglial inflammation influences AIS …

Altered Axon Initial Segment Structure And Function In Inflammatory Disease, Kareem C. Clark

Theses and Dissertations

Axonal pathology is a key contributor to long-term disability in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS), but the mechanisms that underlie axonal insults remain unclear. While most axonal pathologies characterized in MS are a direct consequence of myelin loss, we propose that axonal pathologies also occur independent of demyelination. In support of this idea, we recently reported that mice that develop experimental autoimmune encephalomyelitis (EAE), a model commonly used to mimic the pathogenesis of MS, exhibit a structural and functional disruption of the axon initial segment (AIS), a subdomain of the axon that …

Resolution Of Inflammation Rescues Axon Initial Segment Disruption, Nicholas M. George

Theses and Dissertations

Axonal domains are required for proper neuron function. These domains are unstable and degenerate concurrent with the inflammation in multiple sclerosis (MS) and the inflammatory disease models experimental autoimmune encephalomyelitis (EAE) and lipopolysaccharide (LPS) induced inflammation. Previous studies from our laboratory have shown that the axon initial segment (AIS) is maintained independently of the presence of myelin, but that AIS disruption is seen in MS as well as EAE and LPS-mediated inflammation. AIS loss can be interrupted in the early stage of EAE using the anti-inflammatory drug Didox. However, the potential for Didox directed repair of the AIS in later …

Differential Reactivity Of Microglia In Two Mouse Models Of Multiple Sclerosis, Rebecca K. Hartley

Theses and Dissertations

Multiple sclerosis (MS) is a neurodegenerative disorder characterized by CNS inflammation and axonal demyelination. In addition, axonal pathology has also been reported in MS and may be responsible for the functional deficits associated with this disease. Based on preliminary data from our laboratory, we propose that a specific domain of the neuron, known as the axon initial segment (AIS), is targeted in MS. Consistent with our work from the human tissue, we have also observed disruption of AIS integrity in a murine CNS inflammatory model and observations strongly implicate reactive microglia as mediators of AIS disruption. In contrast, a murine …

Differing Roles Of Autophagy In Hiv-Associated Neurocognitive Impairment And Encephalitis With Implications For Morphine Co-Exposure, Seth M. Dever, Myosotys Rodriguez, Jessica Lapierre, Blair N. Costin, Nazira El-Hage

Pharmacology and Toxicology Publications

We investigated the role of autophagy in HIV-infected subjects with neurocognitive impairment (NCI) ± HIV encephalitis (HIVE), many of which had a history of polysubstance abuse/dependence, using post-mortem brain tissues to determine whether differences in autophagy related factors may be more associated with NCI or NCI-encephalitis. Using qRT-PCR, we detected significant differences in gene expression levels with SQSTM1, LAMP1 higher in HIV-infected subjects without NCI while ATG5, SQSTM1 were then lower in HIV infection/NCI and ATG7, SQSTM1 being higher in NCI-HIVE. Immunohistochemical labeling of these autophagy associated proteins (also including Beclin 1 and LC3B) in Iba1-positive microglial cells showed generally …

Microglia Processes Associate With Diffusely Injured Axons Following Mild Traumatic Brain Injury In The Micro Pig, Audrey D. Lafrenaye, Masak Todani, Susan A. Walker, John T. Povlishock

Anatomy and Neurobiology Publications

Background

Mild traumatic brain injury (mTBI) is an all too common occurrence that exacts significant personal and societal costs. The pathophysiology of mTBI is complex, with reports routinely correlating diffuse axonal injury (DAI) with prolonged morbidity. Progressive chronic neuroinflammation has also recently been correlated to morbidity, however, the potential association between neuroinflammatory microglia and DAI is not well understood. The majority of studies exploring neuroinflammatory responses to TBI have focused on more chronic phases of injury involving phagocytosis associated with Wallerian change. Little, however, is known regarding the neuroinflammatory response seen acutely following diffuse mTBI and its potential relationship to …

Liver X Receptor-Dependent Inhibition Of Microglial Nitric Oxide Synthase 2, Julie R Secor Mcvoy, Hanadi Ajam Oughli, Unsong Oh

Neurology Publications

Background

The nuclear receptor liver X receptor (LXR) exerts transcriptional control over lipid metabolism and inflammatory response in cells of the myeloid lineage, suggesting that LXR may be a potential target in a number of chronic neuroinflammatory and neurodegenerative diseases where persistent microglial activation has been implicated in the pathogenesis.

Methods

The effect of LXR activation on microglia and central nervous system (CNS) inflammation was studied using a synthetic LXR agonist in cultured microglia, a microglial cell line and experimental allergic encephalomyelitis (EAE), an animal model of CNS inflammation.

Results

LXR activation inhibited nitric oxide synthase 2, inducible (Nos2 …

Microglial Activation Decreases Retention Of The Protease Inhibitor Saquinavir: Implications For Hiv Treatment, Shannon Dallas, Michelle L. Block, Deborah M. Thompson, Marcelo G. Bonini, Patrick T. Ronaldson, Reina Bendayan, David S. Miller

Anatomy and Neurobiology Publications

Background

Active HIV infection within the central nervous system (CNS) is confined primarily to microglia. The glial cell compartment acts as a viral reservoir behind the blood-brain barrier. It provides an additional roadblock to effective pharmacological treatment via expression of multiple drug efflux transporters, including P-glycoprotein. HIV/AIDS patients frequently suffer bacterial and viral co-infections, leading to deregulation of glial cell function and release of pro-inflammatory mediators including cytokines, chemokines, and nitric oxide.

Methods

To better define the role of inflammation in decreased HIV drug accumulation into CNS targets, accumulation of the antiretroviral saquinavir was examined in purified cultures of rodent …

The Effect Of Minocycline Treatment On Cell Proliferation And Neurogenesis In The Hippocampus In Young And Aged Brains Following Traumatic Brain Injury, Ashley Harvin

Theses and Dissertations

Following traumatic brain injury, there is an enhanced cell proliferative and neurogenic response in the young adult hippocampus, which may be associated with innate cognitive recovery. However, in the aged brain, an increased level of inflammatory cell responses was observed following injury concomitant to decreased hippocampal neurogenesis and cognitive recovery in the aging population. This suggests that excessive inflammation produced in the injured aging brain has a detrimental effect on neurogenesis and cognitive function. In this study, we examined the effect of anti-inflammatory treatment with minocycline on cell proliferation and generation of new neurons in the dentate gyrus (DG) of …

Triptolide Is A Potential Therapeutic Agent For Alzheimer’S Disease, Matthew Allsbrook

Theses and Dissertations

Mounting evidence indicates an involvement of inflammation in the pathogenesis of Alzheimer’s disease. While there are other mechanisms involved, it is this role of inflammatory processes that we wish to investigate. Triptolide is the major constituent in the Chinese herb, Tripterygium wilfordii Hook F, and has been used for centuries as part of Chinese herbal medicine. The four ringed structure has close homology to drugs of the steroid class and it has been shown to be beneficial as an anti-inflammatory for rheumatoid arthritis and for treatment of certain cancers. The aim of this study was to evaluate the potential therapeutic …

The Role Of Acanthamoeba Culbertsoni Serine Proteases In Abating Microglial-Like Cell Cytokines And Chemokines, Jenica Harrison

Theses and Dissertations

Acanthamoeba culbertsoni is an opportunistic free-living amoeba that is causative of granulomatous amoebic encephalitis (GAE), a chronic and often fatal central nervous system (CNS) disease that is most prevalent in immune compromised individuals. One hallmark of this disease is the formation of granulomas within the CNS, which are commonly absent in immune compromised individuals. Granulomas are usually composed of amoebae, microglia (CNS macrophages), macrophages, T cells, B cells, and neutrophils. Previous studies have demonstrated that microglia respond to Acanthamoeba by producing pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1α, and IL-1β. In addition, activated microglia and macrophages …

Cannabinoid Modulation Of Chemotaxis Of Macrophages And Macrophage-Like Cells, Erinn Shenee Raborn

Theses and Dissertations

Exogenous and endogenous cannabinoids have been reported to modulate functional activities of macrophages. It is recognized that macrophages express primarily the CB2 cannabinoid receptor, but recent studies indicate that its expression is differential in relation to activation state with maximal levels occurring when cells are in "responsive" and "primed" states. The functional activities of macrophages when in these states of activation are the most susceptible to the action of cannabinoids, at least in terms of a functional linkage to the CB2. To assess the effect of cannabinoid treatment on macrophage chemotaxis and test the hypothesis that cannabinoids inhibit the chemotactic …